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TOMOYO Linux Cross Reference
Linux/kernel/trace/ftrace.c

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  1 // SPDX-License-Identifier: GPL-2.0
  2 /*
  3  * Infrastructure for profiling code inserted by 'gcc -pg'.
  4  *
  5  * Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com>
  6  * Copyright (C) 2004-2008 Ingo Molnar <mingo@redhat.com>
  7  *
  8  * Originally ported from the -rt patch by:
  9  *   Copyright (C) 2007 Arnaldo Carvalho de Melo <acme@redhat.com>
 10  *
 11  * Based on code in the latency_tracer, that is:
 12  *
 13  *  Copyright (C) 2004-2006 Ingo Molnar
 14  *  Copyright (C) 2004 Nadia Yvette Chambers
 15  */
 16 
 17 #include <linux/stop_machine.h>
 18 #include <linux/clocksource.h>
 19 #include <linux/sched/task.h>
 20 #include <linux/kallsyms.h>
 21 #include <linux/seq_file.h>
 22 #include <linux/suspend.h>
 23 #include <linux/tracefs.h>
 24 #include <linux/hardirq.h>
 25 #include <linux/kthread.h>
 26 #include <linux/uaccess.h>
 27 #include <linux/bsearch.h>
 28 #include <linux/module.h>
 29 #include <linux/ftrace.h>
 30 #include <linux/sysctl.h>
 31 #include <linux/slab.h>
 32 #include <linux/ctype.h>
 33 #include <linux/sort.h>
 34 #include <linux/list.h>
 35 #include <linux/hash.h>
 36 #include <linux/rcupdate.h>
 37 
 38 #include <trace/events/sched.h>
 39 
 40 #include <asm/sections.h>
 41 #include <asm/setup.h>
 42 
 43 #include "trace_output.h"
 44 #include "trace_stat.h"
 45 
 46 #define FTRACE_WARN_ON(cond)                    \
 47         ({                                      \
 48                 int ___r = cond;                \
 49                 if (WARN_ON(___r))              \
 50                         ftrace_kill();          \
 51                 ___r;                           \
 52         })
 53 
 54 #define FTRACE_WARN_ON_ONCE(cond)               \
 55         ({                                      \
 56                 int ___r = cond;                \
 57                 if (WARN_ON_ONCE(___r))         \
 58                         ftrace_kill();          \
 59                 ___r;                           \
 60         })
 61 
 62 /* hash bits for specific function selection */
 63 #define FTRACE_HASH_BITS 7
 64 #define FTRACE_FUNC_HASHSIZE (1 << FTRACE_HASH_BITS)
 65 #define FTRACE_HASH_DEFAULT_BITS 10
 66 #define FTRACE_HASH_MAX_BITS 12
 67 
 68 #ifdef CONFIG_DYNAMIC_FTRACE
 69 #define INIT_OPS_HASH(opsname)  \
 70         .func_hash              = &opsname.local_hash,                  \
 71         .local_hash.regex_lock  = __MUTEX_INITIALIZER(opsname.local_hash.regex_lock),
 72 #define ASSIGN_OPS_HASH(opsname, val) \
 73         .func_hash              = val, \
 74         .local_hash.regex_lock  = __MUTEX_INITIALIZER(opsname.local_hash.regex_lock),
 75 #else
 76 #define INIT_OPS_HASH(opsname)
 77 #define ASSIGN_OPS_HASH(opsname, val)
 78 #endif
 79 
 80 static struct ftrace_ops ftrace_list_end __read_mostly = {
 81         .func           = ftrace_stub,
 82         .flags          = FTRACE_OPS_FL_RECURSION_SAFE | FTRACE_OPS_FL_STUB,
 83         INIT_OPS_HASH(ftrace_list_end)
 84 };
 85 
 86 /* ftrace_enabled is a method to turn ftrace on or off */
 87 int ftrace_enabled __read_mostly;
 88 static int last_ftrace_enabled;
 89 
 90 /* Current function tracing op */
 91 struct ftrace_ops *function_trace_op __read_mostly = &ftrace_list_end;
 92 /* What to set function_trace_op to */
 93 static struct ftrace_ops *set_function_trace_op;
 94 
 95 static bool ftrace_pids_enabled(struct ftrace_ops *ops)
 96 {
 97         struct trace_array *tr;
 98 
 99         if (!(ops->flags & FTRACE_OPS_FL_PID) || !ops->private)
100                 return false;
101 
102         tr = ops->private;
103 
104         return tr->function_pids != NULL;
105 }
106 
107 static void ftrace_update_trampoline(struct ftrace_ops *ops);
108 
109 /*
110  * ftrace_disabled is set when an anomaly is discovered.
111  * ftrace_disabled is much stronger than ftrace_enabled.
112  */
113 static int ftrace_disabled __read_mostly;
114 
115 static DEFINE_MUTEX(ftrace_lock);
116 
117 static struct ftrace_ops __rcu *ftrace_ops_list __read_mostly = &ftrace_list_end;
118 ftrace_func_t ftrace_trace_function __read_mostly = ftrace_stub;
119 static struct ftrace_ops global_ops;
120 
121 #if ARCH_SUPPORTS_FTRACE_OPS
122 static void ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip,
123                                  struct ftrace_ops *op, struct pt_regs *regs);
124 #else
125 /* See comment below, where ftrace_ops_list_func is defined */
126 static void ftrace_ops_no_ops(unsigned long ip, unsigned long parent_ip);
127 #define ftrace_ops_list_func ((ftrace_func_t)ftrace_ops_no_ops)
128 #endif
129 
130 /*
131  * Traverse the ftrace_global_list, invoking all entries.  The reason that we
132  * can use rcu_dereference_raw_notrace() is that elements removed from this list
133  * are simply leaked, so there is no need to interact with a grace-period
134  * mechanism.  The rcu_dereference_raw_notrace() calls are needed to handle
135  * concurrent insertions into the ftrace_global_list.
136  *
137  * Silly Alpha and silly pointer-speculation compiler optimizations!
138  */
139 #define do_for_each_ftrace_op(op, list)                 \
140         op = rcu_dereference_raw_notrace(list);                 \
141         do
142 
143 /*
144  * Optimized for just a single item in the list (as that is the normal case).
145  */
146 #define while_for_each_ftrace_op(op)                            \
147         while (likely(op = rcu_dereference_raw_notrace((op)->next)) &&  \
148                unlikely((op) != &ftrace_list_end))
149 
150 static inline void ftrace_ops_init(struct ftrace_ops *ops)
151 {
152 #ifdef CONFIG_DYNAMIC_FTRACE
153         if (!(ops->flags & FTRACE_OPS_FL_INITIALIZED)) {
154                 mutex_init(&ops->local_hash.regex_lock);
155                 ops->func_hash = &ops->local_hash;
156                 ops->flags |= FTRACE_OPS_FL_INITIALIZED;
157         }
158 #endif
159 }
160 
161 static void ftrace_pid_func(unsigned long ip, unsigned long parent_ip,
162                             struct ftrace_ops *op, struct pt_regs *regs)
163 {
164         struct trace_array *tr = op->private;
165 
166         if (tr && this_cpu_read(tr->trace_buffer.data->ftrace_ignore_pid))
167                 return;
168 
169         op->saved_func(ip, parent_ip, op, regs);
170 }
171 
172 static void ftrace_sync(struct work_struct *work)
173 {
174         /*
175          * This function is just a stub to implement a hard force
176          * of synchronize_sched(). This requires synchronizing
177          * tasks even in userspace and idle.
178          *
179          * Yes, function tracing is rude.
180          */
181 }
182 
183 static void ftrace_sync_ipi(void *data)
184 {
185         /* Probably not needed, but do it anyway */
186         smp_rmb();
187 }
188 
189 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
190 static void update_function_graph_func(void);
191 
192 /* Both enabled by default (can be cleared by function_graph tracer flags */
193 static bool fgraph_sleep_time = true;
194 static bool fgraph_graph_time = true;
195 
196 #else
197 static inline void update_function_graph_func(void) { }
198 #endif
199 
200 
201 static ftrace_func_t ftrace_ops_get_list_func(struct ftrace_ops *ops)
202 {
203         /*
204          * If this is a dynamic, RCU, or per CPU ops, or we force list func,
205          * then it needs to call the list anyway.
206          */
207         if (ops->flags & (FTRACE_OPS_FL_DYNAMIC | FTRACE_OPS_FL_RCU) ||
208             FTRACE_FORCE_LIST_FUNC)
209                 return ftrace_ops_list_func;
210 
211         return ftrace_ops_get_func(ops);
212 }
213 
214 static void update_ftrace_function(void)
215 {
216         ftrace_func_t func;
217 
218         /*
219          * Prepare the ftrace_ops that the arch callback will use.
220          * If there's only one ftrace_ops registered, the ftrace_ops_list
221          * will point to the ops we want.
222          */
223         set_function_trace_op = rcu_dereference_protected(ftrace_ops_list,
224                                                 lockdep_is_held(&ftrace_lock));
225 
226         /* If there's no ftrace_ops registered, just call the stub function */
227         if (set_function_trace_op == &ftrace_list_end) {
228                 func = ftrace_stub;
229 
230         /*
231          * If we are at the end of the list and this ops is
232          * recursion safe and not dynamic and the arch supports passing ops,
233          * then have the mcount trampoline call the function directly.
234          */
235         } else if (rcu_dereference_protected(ftrace_ops_list->next,
236                         lockdep_is_held(&ftrace_lock)) == &ftrace_list_end) {
237                 func = ftrace_ops_get_list_func(ftrace_ops_list);
238 
239         } else {
240                 /* Just use the default ftrace_ops */
241                 set_function_trace_op = &ftrace_list_end;
242                 func = ftrace_ops_list_func;
243         }
244 
245         update_function_graph_func();
246 
247         /* If there's no change, then do nothing more here */
248         if (ftrace_trace_function == func)
249                 return;
250 
251         /*
252          * If we are using the list function, it doesn't care
253          * about the function_trace_ops.
254          */
255         if (func == ftrace_ops_list_func) {
256                 ftrace_trace_function = func;
257                 /*
258                  * Don't even bother setting function_trace_ops,
259                  * it would be racy to do so anyway.
260                  */
261                 return;
262         }
263 
264 #ifndef CONFIG_DYNAMIC_FTRACE
265         /*
266          * For static tracing, we need to be a bit more careful.
267          * The function change takes affect immediately. Thus,
268          * we need to coorditate the setting of the function_trace_ops
269          * with the setting of the ftrace_trace_function.
270          *
271          * Set the function to the list ops, which will call the
272          * function we want, albeit indirectly, but it handles the
273          * ftrace_ops and doesn't depend on function_trace_op.
274          */
275         ftrace_trace_function = ftrace_ops_list_func;
276         /*
277          * Make sure all CPUs see this. Yes this is slow, but static
278          * tracing is slow and nasty to have enabled.
279          */
280         schedule_on_each_cpu(ftrace_sync);
281         /* Now all cpus are using the list ops. */
282         function_trace_op = set_function_trace_op;
283         /* Make sure the function_trace_op is visible on all CPUs */
284         smp_wmb();
285         /* Nasty way to force a rmb on all cpus */
286         smp_call_function(ftrace_sync_ipi, NULL, 1);
287         /* OK, we are all set to update the ftrace_trace_function now! */
288 #endif /* !CONFIG_DYNAMIC_FTRACE */
289 
290         ftrace_trace_function = func;
291 }
292 
293 static void add_ftrace_ops(struct ftrace_ops __rcu **list,
294                            struct ftrace_ops *ops)
295 {
296         rcu_assign_pointer(ops->next, *list);
297 
298         /*
299          * We are entering ops into the list but another
300          * CPU might be walking that list. We need to make sure
301          * the ops->next pointer is valid before another CPU sees
302          * the ops pointer included into the list.
303          */
304         rcu_assign_pointer(*list, ops);
305 }
306 
307 static int remove_ftrace_ops(struct ftrace_ops __rcu **list,
308                              struct ftrace_ops *ops)
309 {
310         struct ftrace_ops **p;
311 
312         /*
313          * If we are removing the last function, then simply point
314          * to the ftrace_stub.
315          */
316         if (rcu_dereference_protected(*list,
317                         lockdep_is_held(&ftrace_lock)) == ops &&
318             rcu_dereference_protected(ops->next,
319                         lockdep_is_held(&ftrace_lock)) == &ftrace_list_end) {
320                 *list = &ftrace_list_end;
321                 return 0;
322         }
323 
324         for (p = list; *p != &ftrace_list_end; p = &(*p)->next)
325                 if (*p == ops)
326                         break;
327 
328         if (*p != ops)
329                 return -1;
330 
331         *p = (*p)->next;
332         return 0;
333 }
334 
335 static void ftrace_update_trampoline(struct ftrace_ops *ops);
336 
337 static int __register_ftrace_function(struct ftrace_ops *ops)
338 {
339         if (ops->flags & FTRACE_OPS_FL_DELETED)
340                 return -EINVAL;
341 
342         if (WARN_ON(ops->flags & FTRACE_OPS_FL_ENABLED))
343                 return -EBUSY;
344 
345 #ifndef CONFIG_DYNAMIC_FTRACE_WITH_REGS
346         /*
347          * If the ftrace_ops specifies SAVE_REGS, then it only can be used
348          * if the arch supports it, or SAVE_REGS_IF_SUPPORTED is also set.
349          * Setting SAVE_REGS_IF_SUPPORTED makes SAVE_REGS irrelevant.
350          */
351         if (ops->flags & FTRACE_OPS_FL_SAVE_REGS &&
352             !(ops->flags & FTRACE_OPS_FL_SAVE_REGS_IF_SUPPORTED))
353                 return -EINVAL;
354 
355         if (ops->flags & FTRACE_OPS_FL_SAVE_REGS_IF_SUPPORTED)
356                 ops->flags |= FTRACE_OPS_FL_SAVE_REGS;
357 #endif
358 
359         if (!core_kernel_data((unsigned long)ops))
360                 ops->flags |= FTRACE_OPS_FL_DYNAMIC;
361 
362         add_ftrace_ops(&ftrace_ops_list, ops);
363 
364         /* Always save the function, and reset at unregistering */
365         ops->saved_func = ops->func;
366 
367         if (ftrace_pids_enabled(ops))
368                 ops->func = ftrace_pid_func;
369 
370         ftrace_update_trampoline(ops);
371 
372         if (ftrace_enabled)
373                 update_ftrace_function();
374 
375         return 0;
376 }
377 
378 static int __unregister_ftrace_function(struct ftrace_ops *ops)
379 {
380         int ret;
381 
382         if (WARN_ON(!(ops->flags & FTRACE_OPS_FL_ENABLED)))
383                 return -EBUSY;
384 
385         ret = remove_ftrace_ops(&ftrace_ops_list, ops);
386 
387         if (ret < 0)
388                 return ret;
389 
390         if (ftrace_enabled)
391                 update_ftrace_function();
392 
393         ops->func = ops->saved_func;
394 
395         return 0;
396 }
397 
398 static void ftrace_update_pid_func(void)
399 {
400         struct ftrace_ops *op;
401 
402         /* Only do something if we are tracing something */
403         if (ftrace_trace_function == ftrace_stub)
404                 return;
405 
406         do_for_each_ftrace_op(op, ftrace_ops_list) {
407                 if (op->flags & FTRACE_OPS_FL_PID) {
408                         op->func = ftrace_pids_enabled(op) ?
409                                 ftrace_pid_func : op->saved_func;
410                         ftrace_update_trampoline(op);
411                 }
412         } while_for_each_ftrace_op(op);
413 
414         update_ftrace_function();
415 }
416 
417 #ifdef CONFIG_FUNCTION_PROFILER
418 struct ftrace_profile {
419         struct hlist_node               node;
420         unsigned long                   ip;
421         unsigned long                   counter;
422 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
423         unsigned long long              time;
424         unsigned long long              time_squared;
425 #endif
426 };
427 
428 struct ftrace_profile_page {
429         struct ftrace_profile_page      *next;
430         unsigned long                   index;
431         struct ftrace_profile           records[];
432 };
433 
434 struct ftrace_profile_stat {
435         atomic_t                        disabled;
436         struct hlist_head               *hash;
437         struct ftrace_profile_page      *pages;
438         struct ftrace_profile_page      *start;
439         struct tracer_stat              stat;
440 };
441 
442 #define PROFILE_RECORDS_SIZE                                            \
443         (PAGE_SIZE - offsetof(struct ftrace_profile_page, records))
444 
445 #define PROFILES_PER_PAGE                                       \
446         (PROFILE_RECORDS_SIZE / sizeof(struct ftrace_profile))
447 
448 static int ftrace_profile_enabled __read_mostly;
449 
450 /* ftrace_profile_lock - synchronize the enable and disable of the profiler */
451 static DEFINE_MUTEX(ftrace_profile_lock);
452 
453 static DEFINE_PER_CPU(struct ftrace_profile_stat, ftrace_profile_stats);
454 
455 #define FTRACE_PROFILE_HASH_BITS 10
456 #define FTRACE_PROFILE_HASH_SIZE (1 << FTRACE_PROFILE_HASH_BITS)
457 
458 static void *
459 function_stat_next(void *v, int idx)
460 {
461         struct ftrace_profile *rec = v;
462         struct ftrace_profile_page *pg;
463 
464         pg = (struct ftrace_profile_page *)((unsigned long)rec & PAGE_MASK);
465 
466  again:
467         if (idx != 0)
468                 rec++;
469 
470         if ((void *)rec >= (void *)&pg->records[pg->index]) {
471                 pg = pg->next;
472                 if (!pg)
473                         return NULL;
474                 rec = &pg->records[0];
475                 if (!rec->counter)
476                         goto again;
477         }
478 
479         return rec;
480 }
481 
482 static void *function_stat_start(struct tracer_stat *trace)
483 {
484         struct ftrace_profile_stat *stat =
485                 container_of(trace, struct ftrace_profile_stat, stat);
486 
487         if (!stat || !stat->start)
488                 return NULL;
489 
490         return function_stat_next(&stat->start->records[0], 0);
491 }
492 
493 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
494 /* function graph compares on total time */
495 static int function_stat_cmp(void *p1, void *p2)
496 {
497         struct ftrace_profile *a = p1;
498         struct ftrace_profile *b = p2;
499 
500         if (a->time < b->time)
501                 return -1;
502         if (a->time > b->time)
503                 return 1;
504         else
505                 return 0;
506 }
507 #else
508 /* not function graph compares against hits */
509 static int function_stat_cmp(void *p1, void *p2)
510 {
511         struct ftrace_profile *a = p1;
512         struct ftrace_profile *b = p2;
513 
514         if (a->counter < b->counter)
515                 return -1;
516         if (a->counter > b->counter)
517                 return 1;
518         else
519                 return 0;
520 }
521 #endif
522 
523 static int function_stat_headers(struct seq_file *m)
524 {
525 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
526         seq_puts(m, "  Function                               "
527                  "Hit    Time            Avg             s^2\n"
528                     "  --------                               "
529                  "---    ----            ---             ---\n");
530 #else
531         seq_puts(m, "  Function                               Hit\n"
532                     "  --------                               ---\n");
533 #endif
534         return 0;
535 }
536 
537 static int function_stat_show(struct seq_file *m, void *v)
538 {
539         struct ftrace_profile *rec = v;
540         char str[KSYM_SYMBOL_LEN];
541         int ret = 0;
542 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
543         static struct trace_seq s;
544         unsigned long long avg;
545         unsigned long long stddev;
546 #endif
547         mutex_lock(&ftrace_profile_lock);
548 
549         /* we raced with function_profile_reset() */
550         if (unlikely(rec->counter == 0)) {
551                 ret = -EBUSY;
552                 goto out;
553         }
554 
555 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
556         avg = rec->time;
557         do_div(avg, rec->counter);
558         if (tracing_thresh && (avg < tracing_thresh))
559                 goto out;
560 #endif
561 
562         kallsyms_lookup(rec->ip, NULL, NULL, NULL, str);
563         seq_printf(m, "  %-30.30s  %10lu", str, rec->counter);
564 
565 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
566         seq_puts(m, "    ");
567 
568         /* Sample standard deviation (s^2) */
569         if (rec->counter <= 1)
570                 stddev = 0;
571         else {
572                 /*
573                  * Apply Welford's method:
574                  * s^2 = 1 / (n * (n-1)) * (n * \Sum (x_i)^2 - (\Sum x_i)^2)
575                  */
576                 stddev = rec->counter * rec->time_squared -
577                          rec->time * rec->time;
578 
579                 /*
580                  * Divide only 1000 for ns^2 -> us^2 conversion.
581                  * trace_print_graph_duration will divide 1000 again.
582                  */
583                 do_div(stddev, rec->counter * (rec->counter - 1) * 1000);
584         }
585 
586         trace_seq_init(&s);
587         trace_print_graph_duration(rec->time, &s);
588         trace_seq_puts(&s, "    ");
589         trace_print_graph_duration(avg, &s);
590         trace_seq_puts(&s, "    ");
591         trace_print_graph_duration(stddev, &s);
592         trace_print_seq(m, &s);
593 #endif
594         seq_putc(m, '\n');
595 out:
596         mutex_unlock(&ftrace_profile_lock);
597 
598         return ret;
599 }
600 
601 static void ftrace_profile_reset(struct ftrace_profile_stat *stat)
602 {
603         struct ftrace_profile_page *pg;
604 
605         pg = stat->pages = stat->start;
606 
607         while (pg) {
608                 memset(pg->records, 0, PROFILE_RECORDS_SIZE);
609                 pg->index = 0;
610                 pg = pg->next;
611         }
612 
613         memset(stat->hash, 0,
614                FTRACE_PROFILE_HASH_SIZE * sizeof(struct hlist_head));
615 }
616 
617 int ftrace_profile_pages_init(struct ftrace_profile_stat *stat)
618 {
619         struct ftrace_profile_page *pg;
620         int functions;
621         int pages;
622         int i;
623 
624         /* If we already allocated, do nothing */
625         if (stat->pages)
626                 return 0;
627 
628         stat->pages = (void *)get_zeroed_page(GFP_KERNEL);
629         if (!stat->pages)
630                 return -ENOMEM;
631 
632 #ifdef CONFIG_DYNAMIC_FTRACE
633         functions = ftrace_update_tot_cnt;
634 #else
635         /*
636          * We do not know the number of functions that exist because
637          * dynamic tracing is what counts them. With past experience
638          * we have around 20K functions. That should be more than enough.
639          * It is highly unlikely we will execute every function in
640          * the kernel.
641          */
642         functions = 20000;
643 #endif
644 
645         pg = stat->start = stat->pages;
646 
647         pages = DIV_ROUND_UP(functions, PROFILES_PER_PAGE);
648 
649         for (i = 1; i < pages; i++) {
650                 pg->next = (void *)get_zeroed_page(GFP_KERNEL);
651                 if (!pg->next)
652                         goto out_free;
653                 pg = pg->next;
654         }
655 
656         return 0;
657 
658  out_free:
659         pg = stat->start;
660         while (pg) {
661                 unsigned long tmp = (unsigned long)pg;
662 
663                 pg = pg->next;
664                 free_page(tmp);
665         }
666 
667         stat->pages = NULL;
668         stat->start = NULL;
669 
670         return -ENOMEM;
671 }
672 
673 static int ftrace_profile_init_cpu(int cpu)
674 {
675         struct ftrace_profile_stat *stat;
676         int size;
677 
678         stat = &per_cpu(ftrace_profile_stats, cpu);
679 
680         if (stat->hash) {
681                 /* If the profile is already created, simply reset it */
682                 ftrace_profile_reset(stat);
683                 return 0;
684         }
685 
686         /*
687          * We are profiling all functions, but usually only a few thousand
688          * functions are hit. We'll make a hash of 1024 items.
689          */
690         size = FTRACE_PROFILE_HASH_SIZE;
691 
692         stat->hash = kcalloc(size, sizeof(struct hlist_head), GFP_KERNEL);
693 
694         if (!stat->hash)
695                 return -ENOMEM;
696 
697         /* Preallocate the function profiling pages */
698         if (ftrace_profile_pages_init(stat) < 0) {
699                 kfree(stat->hash);
700                 stat->hash = NULL;
701                 return -ENOMEM;
702         }
703 
704         return 0;
705 }
706 
707 static int ftrace_profile_init(void)
708 {
709         int cpu;
710         int ret = 0;
711 
712         for_each_possible_cpu(cpu) {
713                 ret = ftrace_profile_init_cpu(cpu);
714                 if (ret)
715                         break;
716         }
717 
718         return ret;
719 }
720 
721 /* interrupts must be disabled */
722 static struct ftrace_profile *
723 ftrace_find_profiled_func(struct ftrace_profile_stat *stat, unsigned long ip)
724 {
725         struct ftrace_profile *rec;
726         struct hlist_head *hhd;
727         unsigned long key;
728 
729         key = hash_long(ip, FTRACE_PROFILE_HASH_BITS);
730         hhd = &stat->hash[key];
731 
732         if (hlist_empty(hhd))
733                 return NULL;
734 
735         hlist_for_each_entry_rcu_notrace(rec, hhd, node) {
736                 if (rec->ip == ip)
737                         return rec;
738         }
739 
740         return NULL;
741 }
742 
743 static void ftrace_add_profile(struct ftrace_profile_stat *stat,
744                                struct ftrace_profile *rec)
745 {
746         unsigned long key;
747 
748         key = hash_long(rec->ip, FTRACE_PROFILE_HASH_BITS);
749         hlist_add_head_rcu(&rec->node, &stat->hash[key]);
750 }
751 
752 /*
753  * The memory is already allocated, this simply finds a new record to use.
754  */
755 static struct ftrace_profile *
756 ftrace_profile_alloc(struct ftrace_profile_stat *stat, unsigned long ip)
757 {
758         struct ftrace_profile *rec = NULL;
759 
760         /* prevent recursion (from NMIs) */
761         if (atomic_inc_return(&stat->disabled) != 1)
762                 goto out;
763 
764         /*
765          * Try to find the function again since an NMI
766          * could have added it
767          */
768         rec = ftrace_find_profiled_func(stat, ip);
769         if (rec)
770                 goto out;
771 
772         if (stat->pages->index == PROFILES_PER_PAGE) {
773                 if (!stat->pages->next)
774                         goto out;
775                 stat->pages = stat->pages->next;
776         }
777 
778         rec = &stat->pages->records[stat->pages->index++];
779         rec->ip = ip;
780         ftrace_add_profile(stat, rec);
781 
782  out:
783         atomic_dec(&stat->disabled);
784 
785         return rec;
786 }
787 
788 static void
789 function_profile_call(unsigned long ip, unsigned long parent_ip,
790                       struct ftrace_ops *ops, struct pt_regs *regs)
791 {
792         struct ftrace_profile_stat *stat;
793         struct ftrace_profile *rec;
794         unsigned long flags;
795 
796         if (!ftrace_profile_enabled)
797                 return;
798 
799         local_irq_save(flags);
800 
801         stat = this_cpu_ptr(&ftrace_profile_stats);
802         if (!stat->hash || !ftrace_profile_enabled)
803                 goto out;
804 
805         rec = ftrace_find_profiled_func(stat, ip);
806         if (!rec) {
807                 rec = ftrace_profile_alloc(stat, ip);
808                 if (!rec)
809                         goto out;
810         }
811 
812         rec->counter++;
813  out:
814         local_irq_restore(flags);
815 }
816 
817 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
818 static int profile_graph_entry(struct ftrace_graph_ent *trace)
819 {
820         int index = trace->depth;
821 
822         function_profile_call(trace->func, 0, NULL, NULL);
823 
824         /* If function graph is shutting down, ret_stack can be NULL */
825         if (!current->ret_stack)
826                 return 0;
827 
828         if (index >= 0 && index < FTRACE_RETFUNC_DEPTH)
829                 current->ret_stack[index].subtime = 0;
830 
831         return 1;
832 }
833 
834 static void profile_graph_return(struct ftrace_graph_ret *trace)
835 {
836         struct ftrace_profile_stat *stat;
837         unsigned long long calltime;
838         struct ftrace_profile *rec;
839         unsigned long flags;
840 
841         local_irq_save(flags);
842         stat = this_cpu_ptr(&ftrace_profile_stats);
843         if (!stat->hash || !ftrace_profile_enabled)
844                 goto out;
845 
846         /* If the calltime was zero'd ignore it */
847         if (!trace->calltime)
848                 goto out;
849 
850         calltime = trace->rettime - trace->calltime;
851 
852         if (!fgraph_graph_time) {
853                 int index;
854 
855                 index = trace->depth;
856 
857                 /* Append this call time to the parent time to subtract */
858                 if (index)
859                         current->ret_stack[index - 1].subtime += calltime;
860 
861                 if (current->ret_stack[index].subtime < calltime)
862                         calltime -= current->ret_stack[index].subtime;
863                 else
864                         calltime = 0;
865         }
866 
867         rec = ftrace_find_profiled_func(stat, trace->func);
868         if (rec) {
869                 rec->time += calltime;
870                 rec->time_squared += calltime * calltime;
871         }
872 
873  out:
874         local_irq_restore(flags);
875 }
876 
877 static int register_ftrace_profiler(void)
878 {
879         return register_ftrace_graph(&profile_graph_return,
880                                      &profile_graph_entry);
881 }
882 
883 static void unregister_ftrace_profiler(void)
884 {
885         unregister_ftrace_graph();
886 }
887 #else
888 static struct ftrace_ops ftrace_profile_ops __read_mostly = {
889         .func           = function_profile_call,
890         .flags          = FTRACE_OPS_FL_RECURSION_SAFE | FTRACE_OPS_FL_INITIALIZED,
891         INIT_OPS_HASH(ftrace_profile_ops)
892 };
893 
894 static int register_ftrace_profiler(void)
895 {
896         return register_ftrace_function(&ftrace_profile_ops);
897 }
898 
899 static void unregister_ftrace_profiler(void)
900 {
901         unregister_ftrace_function(&ftrace_profile_ops);
902 }
903 #endif /* CONFIG_FUNCTION_GRAPH_TRACER */
904 
905 static ssize_t
906 ftrace_profile_write(struct file *filp, const char __user *ubuf,
907                      size_t cnt, loff_t *ppos)
908 {
909         unsigned long val;
910         int ret;
911 
912         ret = kstrtoul_from_user(ubuf, cnt, 10, &val);
913         if (ret)
914                 return ret;
915 
916         val = !!val;
917 
918         mutex_lock(&ftrace_profile_lock);
919         if (ftrace_profile_enabled ^ val) {
920                 if (val) {
921                         ret = ftrace_profile_init();
922                         if (ret < 0) {
923                                 cnt = ret;
924                                 goto out;
925                         }
926 
927                         ret = register_ftrace_profiler();
928                         if (ret < 0) {
929                                 cnt = ret;
930                                 goto out;
931                         }
932                         ftrace_profile_enabled = 1;
933                 } else {
934                         ftrace_profile_enabled = 0;
935                         /*
936                          * unregister_ftrace_profiler calls stop_machine
937                          * so this acts like an synchronize_sched.
938                          */
939                         unregister_ftrace_profiler();
940                 }
941         }
942  out:
943         mutex_unlock(&ftrace_profile_lock);
944 
945         *ppos += cnt;
946 
947         return cnt;
948 }
949 
950 static ssize_t
951 ftrace_profile_read(struct file *filp, char __user *ubuf,
952                      size_t cnt, loff_t *ppos)
953 {
954         char buf[64];           /* big enough to hold a number */
955         int r;
956 
957         r = sprintf(buf, "%u\n", ftrace_profile_enabled);
958         return simple_read_from_buffer(ubuf, cnt, ppos, buf, r);
959 }
960 
961 static const struct file_operations ftrace_profile_fops = {
962         .open           = tracing_open_generic,
963         .read           = ftrace_profile_read,
964         .write          = ftrace_profile_write,
965         .llseek         = default_llseek,
966 };
967 
968 /* used to initialize the real stat files */
969 static struct tracer_stat function_stats __initdata = {
970         .name           = "functions",
971         .stat_start     = function_stat_start,
972         .stat_next      = function_stat_next,
973         .stat_cmp       = function_stat_cmp,
974         .stat_headers   = function_stat_headers,
975         .stat_show      = function_stat_show
976 };
977 
978 static __init void ftrace_profile_tracefs(struct dentry *d_tracer)
979 {
980         struct ftrace_profile_stat *stat;
981         struct dentry *entry;
982         char *name;
983         int ret;
984         int cpu;
985 
986         for_each_possible_cpu(cpu) {
987                 stat = &per_cpu(ftrace_profile_stats, cpu);
988 
989                 name = kasprintf(GFP_KERNEL, "function%d", cpu);
990                 if (!name) {
991                         /*
992                          * The files created are permanent, if something happens
993                          * we still do not free memory.
994                          */
995                         WARN(1,
996                              "Could not allocate stat file for cpu %d\n",
997                              cpu);
998                         return;
999                 }
1000                 stat->stat = function_stats;
1001                 stat->stat.name = name;
1002                 ret = register_stat_tracer(&stat->stat);
1003                 if (ret) {
1004                         WARN(1,
1005                              "Could not register function stat for cpu %d\n",
1006                              cpu);
1007                         kfree(name);
1008                         return;
1009                 }
1010         }
1011 
1012         entry = tracefs_create_file("function_profile_enabled", 0644,
1013                                     d_tracer, NULL, &ftrace_profile_fops);
1014         if (!entry)
1015                 pr_warn("Could not create tracefs 'function_profile_enabled' entry\n");
1016 }
1017 
1018 #else /* CONFIG_FUNCTION_PROFILER */
1019 static __init void ftrace_profile_tracefs(struct dentry *d_tracer)
1020 {
1021 }
1022 #endif /* CONFIG_FUNCTION_PROFILER */
1023 
1024 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
1025 static int ftrace_graph_active;
1026 #else
1027 # define ftrace_graph_active 0
1028 #endif
1029 
1030 #ifdef CONFIG_DYNAMIC_FTRACE
1031 
1032 static struct ftrace_ops *removed_ops;
1033 
1034 /*
1035  * Set when doing a global update, like enabling all recs or disabling them.
1036  * It is not set when just updating a single ftrace_ops.
1037  */
1038 static bool update_all_ops;
1039 
1040 #ifndef CONFIG_FTRACE_MCOUNT_RECORD
1041 # error Dynamic ftrace depends on MCOUNT_RECORD
1042 #endif
1043 
1044 struct ftrace_func_entry {
1045         struct hlist_node hlist;
1046         unsigned long ip;
1047 };
1048 
1049 struct ftrace_func_probe {
1050         struct ftrace_probe_ops *probe_ops;
1051         struct ftrace_ops       ops;
1052         struct trace_array      *tr;
1053         struct list_head        list;
1054         void                    *data;
1055         int                     ref;
1056 };
1057 
1058 /*
1059  * We make these constant because no one should touch them,
1060  * but they are used as the default "empty hash", to avoid allocating
1061  * it all the time. These are in a read only section such that if
1062  * anyone does try to modify it, it will cause an exception.
1063  */
1064 static const struct hlist_head empty_buckets[1];
1065 static const struct ftrace_hash empty_hash = {
1066         .buckets = (struct hlist_head *)empty_buckets,
1067 };
1068 #define EMPTY_HASH      ((struct ftrace_hash *)&empty_hash)
1069 
1070 static struct ftrace_ops global_ops = {
1071         .func                           = ftrace_stub,
1072         .local_hash.notrace_hash        = EMPTY_HASH,
1073         .local_hash.filter_hash         = EMPTY_HASH,
1074         INIT_OPS_HASH(global_ops)
1075         .flags                          = FTRACE_OPS_FL_RECURSION_SAFE |
1076                                           FTRACE_OPS_FL_INITIALIZED |
1077                                           FTRACE_OPS_FL_PID,
1078 };
1079 
1080 /*
1081  * Used by the stack undwinder to know about dynamic ftrace trampolines.
1082  */
1083 struct ftrace_ops *ftrace_ops_trampoline(unsigned long addr)
1084 {
1085         struct ftrace_ops *op = NULL;
1086 
1087         /*
1088          * Some of the ops may be dynamically allocated,
1089          * they are freed after a synchronize_sched().
1090          */
1091         preempt_disable_notrace();
1092 
1093         do_for_each_ftrace_op(op, ftrace_ops_list) {
1094                 /*
1095                  * This is to check for dynamically allocated trampolines.
1096                  * Trampolines that are in kernel text will have
1097                  * core_kernel_text() return true.
1098                  */
1099                 if (op->trampoline && op->trampoline_size)
1100                         if (addr >= op->trampoline &&
1101                             addr < op->trampoline + op->trampoline_size) {
1102                                 preempt_enable_notrace();
1103                                 return op;
1104                         }
1105         } while_for_each_ftrace_op(op);
1106         preempt_enable_notrace();
1107 
1108         return NULL;
1109 }
1110 
1111 /*
1112  * This is used by __kernel_text_address() to return true if the
1113  * address is on a dynamically allocated trampoline that would
1114  * not return true for either core_kernel_text() or
1115  * is_module_text_address().
1116  */
1117 bool is_ftrace_trampoline(unsigned long addr)
1118 {
1119         return ftrace_ops_trampoline(addr) != NULL;
1120 }
1121 
1122 struct ftrace_page {
1123         struct ftrace_page      *next;
1124         struct dyn_ftrace       *records;
1125         int                     index;
1126         int                     size;
1127 };
1128 
1129 #define ENTRY_SIZE sizeof(struct dyn_ftrace)
1130 #define ENTRIES_PER_PAGE (PAGE_SIZE / ENTRY_SIZE)
1131 
1132 /* estimate from running different kernels */
1133 #define NR_TO_INIT              10000
1134 
1135 static struct ftrace_page       *ftrace_pages_start;
1136 static struct ftrace_page       *ftrace_pages;
1137 
1138 static __always_inline unsigned long
1139 ftrace_hash_key(struct ftrace_hash *hash, unsigned long ip)
1140 {
1141         if (hash->size_bits > 0)
1142                 return hash_long(ip, hash->size_bits);
1143 
1144         return 0;
1145 }
1146 
1147 /* Only use this function if ftrace_hash_empty() has already been tested */
1148 static __always_inline struct ftrace_func_entry *
1149 __ftrace_lookup_ip(struct ftrace_hash *hash, unsigned long ip)
1150 {
1151         unsigned long key;
1152         struct ftrace_func_entry *entry;
1153         struct hlist_head *hhd;
1154 
1155         key = ftrace_hash_key(hash, ip);
1156         hhd = &hash->buckets[key];
1157 
1158         hlist_for_each_entry_rcu_notrace(entry, hhd, hlist) {
1159                 if (entry->ip == ip)
1160                         return entry;
1161         }
1162         return NULL;
1163 }
1164 
1165 /**
1166  * ftrace_lookup_ip - Test to see if an ip exists in an ftrace_hash
1167  * @hash: The hash to look at
1168  * @ip: The instruction pointer to test
1169  *
1170  * Search a given @hash to see if a given instruction pointer (@ip)
1171  * exists in it.
1172  *
1173  * Returns the entry that holds the @ip if found. NULL otherwise.
1174  */
1175 struct ftrace_func_entry *
1176 ftrace_lookup_ip(struct ftrace_hash *hash, unsigned long ip)
1177 {
1178         if (ftrace_hash_empty(hash))
1179                 return NULL;
1180 
1181         return __ftrace_lookup_ip(hash, ip);
1182 }
1183 
1184 static void __add_hash_entry(struct ftrace_hash *hash,
1185                              struct ftrace_func_entry *entry)
1186 {
1187         struct hlist_head *hhd;
1188         unsigned long key;
1189 
1190         key = ftrace_hash_key(hash, entry->ip);
1191         hhd = &hash->buckets[key];
1192         hlist_add_head(&entry->hlist, hhd);
1193         hash->count++;
1194 }
1195 
1196 static int add_hash_entry(struct ftrace_hash *hash, unsigned long ip)
1197 {
1198         struct ftrace_func_entry *entry;
1199 
1200         entry = kmalloc(sizeof(*entry), GFP_KERNEL);
1201         if (!entry)
1202                 return -ENOMEM;
1203 
1204         entry->ip = ip;
1205         __add_hash_entry(hash, entry);
1206 
1207         return 0;
1208 }
1209 
1210 static void
1211 free_hash_entry(struct ftrace_hash *hash,
1212                   struct ftrace_func_entry *entry)
1213 {
1214         hlist_del(&entry->hlist);
1215         kfree(entry);
1216         hash->count--;
1217 }
1218 
1219 static void
1220 remove_hash_entry(struct ftrace_hash *hash,
1221                   struct ftrace_func_entry *entry)
1222 {
1223         hlist_del_rcu(&entry->hlist);
1224         hash->count--;
1225 }
1226 
1227 static void ftrace_hash_clear(struct ftrace_hash *hash)
1228 {
1229         struct hlist_head *hhd;
1230         struct hlist_node *tn;
1231         struct ftrace_func_entry *entry;
1232         int size = 1 << hash->size_bits;
1233         int i;
1234 
1235         if (!hash->count)
1236                 return;
1237 
1238         for (i = 0; i < size; i++) {
1239                 hhd = &hash->buckets[i];
1240                 hlist_for_each_entry_safe(entry, tn, hhd, hlist)
1241                         free_hash_entry(hash, entry);
1242         }
1243         FTRACE_WARN_ON(hash->count);
1244 }
1245 
1246 static void free_ftrace_mod(struct ftrace_mod_load *ftrace_mod)
1247 {
1248         list_del(&ftrace_mod->list);
1249         kfree(ftrace_mod->module);
1250         kfree(ftrace_mod->func);
1251         kfree(ftrace_mod);
1252 }
1253 
1254 static void clear_ftrace_mod_list(struct list_head *head)
1255 {
1256         struct ftrace_mod_load *p, *n;
1257 
1258         /* stack tracer isn't supported yet */
1259         if (!head)
1260                 return;
1261 
1262         mutex_lock(&ftrace_lock);
1263         list_for_each_entry_safe(p, n, head, list)
1264                 free_ftrace_mod(p);
1265         mutex_unlock(&ftrace_lock);
1266 }
1267 
1268 static void free_ftrace_hash(struct ftrace_hash *hash)
1269 {
1270         if (!hash || hash == EMPTY_HASH)
1271                 return;
1272         ftrace_hash_clear(hash);
1273         kfree(hash->buckets);
1274         kfree(hash);
1275 }
1276 
1277 static void __free_ftrace_hash_rcu(struct rcu_head *rcu)
1278 {
1279         struct ftrace_hash *hash;
1280 
1281         hash = container_of(rcu, struct ftrace_hash, rcu);
1282         free_ftrace_hash(hash);
1283 }
1284 
1285 static void free_ftrace_hash_rcu(struct ftrace_hash *hash)
1286 {
1287         if (!hash || hash == EMPTY_HASH)
1288                 return;
1289         call_rcu_sched(&hash->rcu, __free_ftrace_hash_rcu);
1290 }
1291 
1292 void ftrace_free_filter(struct ftrace_ops *ops)
1293 {
1294         ftrace_ops_init(ops);
1295         free_ftrace_hash(ops->func_hash->filter_hash);
1296         free_ftrace_hash(ops->func_hash->notrace_hash);
1297 }
1298 
1299 static struct ftrace_hash *alloc_ftrace_hash(int size_bits)
1300 {
1301         struct ftrace_hash *hash;
1302         int size;
1303 
1304         hash = kzalloc(sizeof(*hash), GFP_KERNEL);
1305         if (!hash)
1306                 return NULL;
1307 
1308         size = 1 << size_bits;
1309         hash->buckets = kcalloc(size, sizeof(*hash->buckets), GFP_KERNEL);
1310 
1311         if (!hash->buckets) {
1312                 kfree(hash);
1313                 return NULL;
1314         }
1315 
1316         hash->size_bits = size_bits;
1317 
1318         return hash;
1319 }
1320 
1321 
1322 static int ftrace_add_mod(struct trace_array *tr,
1323                           const char *func, const char *module,
1324                           int enable)
1325 {
1326         struct ftrace_mod_load *ftrace_mod;
1327         struct list_head *mod_head = enable ? &tr->mod_trace : &tr->mod_notrace;
1328 
1329         ftrace_mod = kzalloc(sizeof(*ftrace_mod), GFP_KERNEL);
1330         if (!ftrace_mod)
1331                 return -ENOMEM;
1332 
1333         ftrace_mod->func = kstrdup(func, GFP_KERNEL);
1334         ftrace_mod->module = kstrdup(module, GFP_KERNEL);
1335         ftrace_mod->enable = enable;
1336 
1337         if (!ftrace_mod->func || !ftrace_mod->module)
1338                 goto out_free;
1339 
1340         list_add(&ftrace_mod->list, mod_head);
1341 
1342         return 0;
1343 
1344  out_free:
1345         free_ftrace_mod(ftrace_mod);
1346 
1347         return -ENOMEM;
1348 }
1349 
1350 static struct ftrace_hash *
1351 alloc_and_copy_ftrace_hash(int size_bits, struct ftrace_hash *hash)
1352 {
1353         struct ftrace_func_entry *entry;
1354         struct ftrace_hash *new_hash;
1355         int size;
1356         int ret;
1357         int i;
1358 
1359         new_hash = alloc_ftrace_hash(size_bits);
1360         if (!new_hash)
1361                 return NULL;
1362 
1363         if (hash)
1364                 new_hash->flags = hash->flags;
1365 
1366         /* Empty hash? */
1367         if (ftrace_hash_empty(hash))
1368                 return new_hash;
1369 
1370         size = 1 << hash->size_bits;
1371         for (i = 0; i < size; i++) {
1372                 hlist_for_each_entry(entry, &hash->buckets[i], hlist) {
1373                         ret = add_hash_entry(new_hash, entry->ip);
1374                         if (ret < 0)
1375                                 goto free_hash;
1376                 }
1377         }
1378 
1379         FTRACE_WARN_ON(new_hash->count != hash->count);
1380 
1381         return new_hash;
1382 
1383  free_hash:
1384         free_ftrace_hash(new_hash);
1385         return NULL;
1386 }
1387 
1388 static void
1389 ftrace_hash_rec_disable_modify(struct ftrace_ops *ops, int filter_hash);
1390 static void
1391 ftrace_hash_rec_enable_modify(struct ftrace_ops *ops, int filter_hash);
1392 
1393 static int ftrace_hash_ipmodify_update(struct ftrace_ops *ops,
1394                                        struct ftrace_hash *new_hash);
1395 
1396 static struct ftrace_hash *
1397 __ftrace_hash_move(struct ftrace_hash *src)
1398 {
1399         struct ftrace_func_entry *entry;
1400         struct hlist_node *tn;
1401         struct hlist_head *hhd;
1402         struct ftrace_hash *new_hash;
1403         int size = src->count;
1404         int bits = 0;
1405         int i;
1406 
1407         /*
1408          * If the new source is empty, just return the empty_hash.
1409          */
1410         if (ftrace_hash_empty(src))
1411                 return EMPTY_HASH;
1412 
1413         /*
1414          * Make the hash size about 1/2 the # found
1415          */
1416         for (size /= 2; size; size >>= 1)
1417                 bits++;
1418 
1419         /* Don't allocate too much */
1420         if (bits > FTRACE_HASH_MAX_BITS)
1421                 bits = FTRACE_HASH_MAX_BITS;
1422 
1423         new_hash = alloc_ftrace_hash(bits);
1424         if (!new_hash)
1425                 return NULL;
1426 
1427         new_hash->flags = src->flags;
1428 
1429         size = 1 << src->size_bits;
1430         for (i = 0; i < size; i++) {
1431                 hhd = &src->buckets[i];
1432                 hlist_for_each_entry_safe(entry, tn, hhd, hlist) {
1433                         remove_hash_entry(src, entry);
1434                         __add_hash_entry(new_hash, entry);
1435                 }
1436         }
1437 
1438         return new_hash;
1439 }
1440 
1441 static int
1442 ftrace_hash_move(struct ftrace_ops *ops, int enable,
1443                  struct ftrace_hash **dst, struct ftrace_hash *src)
1444 {
1445         struct ftrace_hash *new_hash;
1446         int ret;
1447 
1448         /* Reject setting notrace hash on IPMODIFY ftrace_ops */
1449         if (ops->flags & FTRACE_OPS_FL_IPMODIFY && !enable)
1450                 return -EINVAL;
1451 
1452         new_hash = __ftrace_hash_move(src);
1453         if (!new_hash)
1454                 return -ENOMEM;
1455 
1456         /* Make sure this can be applied if it is IPMODIFY ftrace_ops */
1457         if (enable) {
1458                 /* IPMODIFY should be updated only when filter_hash updating */
1459                 ret = ftrace_hash_ipmodify_update(ops, new_hash);
1460                 if (ret < 0) {
1461                         free_ftrace_hash(new_hash);
1462                         return ret;
1463                 }
1464         }
1465 
1466         /*
1467          * Remove the current set, update the hash and add
1468          * them back.
1469          */
1470         ftrace_hash_rec_disable_modify(ops, enable);
1471 
1472         rcu_assign_pointer(*dst, new_hash);
1473 
1474         ftrace_hash_rec_enable_modify(ops, enable);
1475 
1476         return 0;
1477 }
1478 
1479 static bool hash_contains_ip(unsigned long ip,
1480                              struct ftrace_ops_hash *hash)
1481 {
1482         /*
1483          * The function record is a match if it exists in the filter
1484          * hash and not in the notrace hash. Note, an emty hash is
1485          * considered a match for the filter hash, but an empty
1486          * notrace hash is considered not in the notrace hash.
1487          */
1488         return (ftrace_hash_empty(hash->filter_hash) ||
1489                 __ftrace_lookup_ip(hash->filter_hash, ip)) &&
1490                 (ftrace_hash_empty(hash->notrace_hash) ||
1491                  !__ftrace_lookup_ip(hash->notrace_hash, ip));
1492 }
1493 
1494 /*
1495  * Test the hashes for this ops to see if we want to call
1496  * the ops->func or not.
1497  *
1498  * It's a match if the ip is in the ops->filter_hash or
1499  * the filter_hash does not exist or is empty,
1500  *  AND
1501  * the ip is not in the ops->notrace_hash.
1502  *
1503  * This needs to be called with preemption disabled as
1504  * the hashes are freed with call_rcu_sched().
1505  */
1506 static int
1507 ftrace_ops_test(struct ftrace_ops *ops, unsigned long ip, void *regs)
1508 {
1509         struct ftrace_ops_hash hash;
1510         int ret;
1511 
1512 #ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
1513         /*
1514          * There's a small race when adding ops that the ftrace handler
1515          * that wants regs, may be called without them. We can not
1516          * allow that handler to be called if regs is NULL.
1517          */
1518         if (regs == NULL && (ops->flags & FTRACE_OPS_FL_SAVE_REGS))
1519                 return 0;
1520 #endif
1521 
1522         rcu_assign_pointer(hash.filter_hash, ops->func_hash->filter_hash);
1523         rcu_assign_pointer(hash.notrace_hash, ops->func_hash->notrace_hash);
1524 
1525         if (hash_contains_ip(ip, &hash))
1526                 ret = 1;
1527         else
1528                 ret = 0;
1529 
1530         return ret;
1531 }
1532 
1533 /*
1534  * This is a double for. Do not use 'break' to break out of the loop,
1535  * you must use a goto.
1536  */
1537 #define do_for_each_ftrace_rec(pg, rec)                                 \
1538         for (pg = ftrace_pages_start; pg; pg = pg->next) {              \
1539                 int _____i;                                             \
1540                 for (_____i = 0; _____i < pg->index; _____i++) {        \
1541                         rec = &pg->records[_____i];
1542 
1543 #define while_for_each_ftrace_rec()             \
1544                 }                               \
1545         }
1546 
1547 
1548 static int ftrace_cmp_recs(const void *a, const void *b)
1549 {
1550         const struct dyn_ftrace *key = a;
1551         const struct dyn_ftrace *rec = b;
1552 
1553         if (key->flags < rec->ip)
1554                 return -1;
1555         if (key->ip >= rec->ip + MCOUNT_INSN_SIZE)
1556                 return 1;
1557         return 0;
1558 }
1559 
1560 /**
1561  * ftrace_location_range - return the first address of a traced location
1562  *      if it touches the given ip range
1563  * @start: start of range to search.
1564  * @end: end of range to search (inclusive). @end points to the last byte
1565  *      to check.
1566  *
1567  * Returns rec->ip if the related ftrace location is a least partly within
1568  * the given address range. That is, the first address of the instruction
1569  * that is either a NOP or call to the function tracer. It checks the ftrace
1570  * internal tables to determine if the address belongs or not.
1571  */
1572 unsigned long ftrace_location_range(unsigned long start, unsigned long end)
1573 {
1574         struct ftrace_page *pg;
1575         struct dyn_ftrace *rec;
1576         struct dyn_ftrace key;
1577 
1578         key.ip = start;
1579         key.flags = end;        /* overload flags, as it is unsigned long */
1580 
1581         for (pg = ftrace_pages_start; pg; pg = pg->next) {
1582                 if (end < pg->records[0].ip ||
1583                     start >= (pg->records[pg->index - 1].ip + MCOUNT_INSN_SIZE))
1584                         continue;
1585                 rec = bsearch(&key, pg->records, pg->index,
1586                               sizeof(struct dyn_ftrace),
1587                               ftrace_cmp_recs);
1588                 if (rec)
1589                         return rec->ip;
1590         }
1591 
1592         return 0;
1593 }
1594 
1595 /**
1596  * ftrace_location - return true if the ip giving is a traced location
1597  * @ip: the instruction pointer to check
1598  *
1599  * Returns rec->ip if @ip given is a pointer to a ftrace location.
1600  * That is, the instruction that is either a NOP or call to
1601  * the function tracer. It checks the ftrace internal tables to
1602  * determine if the address belongs or not.
1603  */
1604 unsigned long ftrace_location(unsigned long ip)
1605 {
1606         return ftrace_location_range(ip, ip);
1607 }
1608 
1609 /**
1610  * ftrace_text_reserved - return true if range contains an ftrace location
1611  * @start: start of range to search
1612  * @end: end of range to search (inclusive). @end points to the last byte to check.
1613  *
1614  * Returns 1 if @start and @end contains a ftrace location.
1615  * That is, the instruction that is either a NOP or call to
1616  * the function tracer. It checks the ftrace internal tables to
1617  * determine if the address belongs or not.
1618  */
1619 int ftrace_text_reserved(const void *start, const void *end)
1620 {
1621         unsigned long ret;
1622 
1623         ret = ftrace_location_range((unsigned long)start,
1624                                     (unsigned long)end);
1625 
1626         return (int)!!ret;
1627 }
1628 
1629 /* Test if ops registered to this rec needs regs */
1630 static bool test_rec_ops_needs_regs(struct dyn_ftrace *rec)
1631 {
1632         struct ftrace_ops *ops;
1633         bool keep_regs = false;
1634 
1635         for (ops = ftrace_ops_list;
1636              ops != &ftrace_list_end; ops = ops->next) {
1637                 /* pass rec in as regs to have non-NULL val */
1638                 if (ftrace_ops_test(ops, rec->ip, rec)) {
1639                         if (ops->flags & FTRACE_OPS_FL_SAVE_REGS) {
1640                                 keep_regs = true;
1641                                 break;
1642                         }
1643                 }
1644         }
1645 
1646         return  keep_regs;
1647 }
1648 
1649 static bool __ftrace_hash_rec_update(struct ftrace_ops *ops,
1650                                      int filter_hash,
1651                                      bool inc)
1652 {
1653         struct ftrace_hash *hash;
1654         struct ftrace_hash *other_hash;
1655         struct ftrace_page *pg;
1656         struct dyn_ftrace *rec;
1657         bool update = false;
1658         int count = 0;
1659         int all = false;
1660 
1661         /* Only update if the ops has been registered */
1662         if (!(ops->flags & FTRACE_OPS_FL_ENABLED))
1663                 return false;
1664 
1665         /*
1666          * In the filter_hash case:
1667          *   If the count is zero, we update all records.
1668          *   Otherwise we just update the items in the hash.
1669          *
1670          * In the notrace_hash case:
1671          *   We enable the update in the hash.
1672          *   As disabling notrace means enabling the tracing,
1673          *   and enabling notrace means disabling, the inc variable
1674          *   gets inversed.
1675          */
1676         if (filter_hash) {
1677                 hash = ops->func_hash->filter_hash;
1678                 other_hash = ops->func_hash->notrace_hash;
1679                 if (ftrace_hash_empty(hash))
1680                         all = true;
1681         } else {
1682                 inc = !inc;
1683                 hash = ops->func_hash->notrace_hash;
1684                 other_hash = ops->func_hash->filter_hash;
1685                 /*
1686                  * If the notrace hash has no items,
1687                  * then there's nothing to do.
1688                  */
1689                 if (ftrace_hash_empty(hash))
1690                         return false;
1691         }
1692 
1693         do_for_each_ftrace_rec(pg, rec) {
1694                 int in_other_hash = 0;
1695                 int in_hash = 0;
1696                 int match = 0;
1697 
1698                 if (rec->flags & FTRACE_FL_DISABLED)
1699                         continue;
1700 
1701                 if (all) {
1702                         /*
1703                          * Only the filter_hash affects all records.
1704                          * Update if the record is not in the notrace hash.
1705                          */
1706                         if (!other_hash || !ftrace_lookup_ip(other_hash, rec->ip))
1707                                 match = 1;
1708                 } else {
1709                         in_hash = !!ftrace_lookup_ip(hash, rec->ip);
1710                         in_other_hash = !!ftrace_lookup_ip(other_hash, rec->ip);
1711 
1712                         /*
1713                          * If filter_hash is set, we want to match all functions
1714                          * that are in the hash but not in the other hash.
1715                          *
1716                          * If filter_hash is not set, then we are decrementing.
1717                          * That means we match anything that is in the hash
1718                          * and also in the other_hash. That is, we need to turn
1719                          * off functions in the other hash because they are disabled
1720                          * by this hash.
1721                          */
1722                         if (filter_hash && in_hash && !in_other_hash)
1723                                 match = 1;
1724                         else if (!filter_hash && in_hash &&
1725                                  (in_other_hash || ftrace_hash_empty(other_hash)))
1726                                 match = 1;
1727                 }
1728                 if (!match)
1729                         continue;
1730 
1731                 if (inc) {
1732                         rec->flags++;
1733                         if (FTRACE_WARN_ON(ftrace_rec_count(rec) == FTRACE_REF_MAX))
1734                                 return false;
1735 
1736                         /*
1737                          * If there's only a single callback registered to a
1738                          * function, and the ops has a trampoline registered
1739                          * for it, then we can call it directly.
1740                          */
1741                         if (ftrace_rec_count(rec) == 1 && ops->trampoline)
1742                                 rec->flags |= FTRACE_FL_TRAMP;
1743                         else
1744                                 /*
1745                                  * If we are adding another function callback
1746                                  * to this function, and the previous had a
1747                                  * custom trampoline in use, then we need to go
1748                                  * back to the default trampoline.
1749                                  */
1750                                 rec->flags &= ~FTRACE_FL_TRAMP;
1751 
1752                         /*
1753                          * If any ops wants regs saved for this function
1754                          * then all ops will get saved regs.
1755                          */
1756                         if (ops->flags & FTRACE_OPS_FL_SAVE_REGS)
1757                                 rec->flags |= FTRACE_FL_REGS;
1758                 } else {
1759                         if (FTRACE_WARN_ON(ftrace_rec_count(rec) == 0))
1760                                 return false;
1761                         rec->flags--;
1762 
1763                         /*
1764                          * If the rec had REGS enabled and the ops that is
1765                          * being removed had REGS set, then see if there is
1766                          * still any ops for this record that wants regs.
1767                          * If not, we can stop recording them.
1768                          */
1769                         if (ftrace_rec_count(rec) > 0 &&
1770                             rec->flags & FTRACE_FL_REGS &&
1771                             ops->flags & FTRACE_OPS_FL_SAVE_REGS) {
1772                                 if (!test_rec_ops_needs_regs(rec))
1773                                         rec->flags &= ~FTRACE_FL_REGS;
1774                         }
1775 
1776                         /*
1777                          * If the rec had TRAMP enabled, then it needs to
1778                          * be cleared. As TRAMP can only be enabled iff
1779                          * there is only a single ops attached to it.
1780                          * In otherwords, always disable it on decrementing.
1781                          * In the future, we may set it if rec count is
1782                          * decremented to one, and the ops that is left
1783                          * has a trampoline.
1784                          */
1785                         rec->flags &= ~FTRACE_FL_TRAMP;
1786 
1787                         /*
1788                          * flags will be cleared in ftrace_check_record()
1789                          * if rec count is zero.
1790                          */
1791                 }
1792                 count++;
1793 
1794                 /* Must match FTRACE_UPDATE_CALLS in ftrace_modify_all_code() */
1795                 update |= ftrace_test_record(rec, 1) != FTRACE_UPDATE_IGNORE;
1796 
1797                 /* Shortcut, if we handled all records, we are done. */
1798                 if (!all && count == hash->count)
1799                         return update;
1800         } while_for_each_ftrace_rec();
1801 
1802         return update;
1803 }
1804 
1805 static bool ftrace_hash_rec_disable(struct ftrace_ops *ops,
1806                                     int filter_hash)
1807 {
1808         return __ftrace_hash_rec_update(ops, filter_hash, 0);
1809 }
1810 
1811 static bool ftrace_hash_rec_enable(struct ftrace_ops *ops,
1812                                    int filter_hash)
1813 {
1814         return __ftrace_hash_rec_update(ops, filter_hash, 1);
1815 }
1816 
1817 static void ftrace_hash_rec_update_modify(struct ftrace_ops *ops,
1818                                           int filter_hash, int inc)
1819 {
1820         struct ftrace_ops *op;
1821 
1822         __ftrace_hash_rec_update(ops, filter_hash, inc);
1823 
1824         if (ops->func_hash != &global_ops.local_hash)
1825                 return;
1826 
1827         /*
1828          * If the ops shares the global_ops hash, then we need to update
1829          * all ops that are enabled and use this hash.
1830          */
1831         do_for_each_ftrace_op(op, ftrace_ops_list) {
1832                 /* Already done */
1833                 if (op == ops)
1834                         continue;
1835                 if (op->func_hash == &global_ops.local_hash)
1836                         __ftrace_hash_rec_update(op, filter_hash, inc);
1837         } while_for_each_ftrace_op(op);
1838 }
1839 
1840 static void ftrace_hash_rec_disable_modify(struct ftrace_ops *ops,
1841                                            int filter_hash)
1842 {
1843         ftrace_hash_rec_update_modify(ops, filter_hash, 0);
1844 }
1845 
1846 static void ftrace_hash_rec_enable_modify(struct ftrace_ops *ops,
1847                                           int filter_hash)
1848 {
1849         ftrace_hash_rec_update_modify(ops, filter_hash, 1);
1850 }
1851 
1852 /*
1853  * Try to update IPMODIFY flag on each ftrace_rec. Return 0 if it is OK
1854  * or no-needed to update, -EBUSY if it detects a conflict of the flag
1855  * on a ftrace_rec, and -EINVAL if the new_hash tries to trace all recs.
1856  * Note that old_hash and new_hash has below meanings
1857  *  - If the hash is NULL, it hits all recs (if IPMODIFY is set, this is rejected)
1858  *  - If the hash is EMPTY_HASH, it hits nothing
1859  *  - Anything else hits the recs which match the hash entries.
1860  */
1861 static int __ftrace_hash_update_ipmodify(struct ftrace_ops *ops,
1862                                          struct ftrace_hash *old_hash,
1863                                          struct ftrace_hash *new_hash)
1864 {
1865         struct ftrace_page *pg;
1866         struct dyn_ftrace *rec, *end = NULL;
1867         int in_old, in_new;
1868 
1869         /* Only update if the ops has been registered */
1870         if (!(ops->flags & FTRACE_OPS_FL_ENABLED))
1871                 return 0;
1872 
1873         if (!(ops->flags & FTRACE_OPS_FL_IPMODIFY))
1874                 return 0;
1875 
1876         /*
1877          * Since the IPMODIFY is a very address sensitive action, we do not
1878          * allow ftrace_ops to set all functions to new hash.
1879          */
1880         if (!new_hash || !old_hash)
1881                 return -EINVAL;
1882 
1883         /* Update rec->flags */
1884         do_for_each_ftrace_rec(pg, rec) {
1885 
1886                 if (rec->flags & FTRACE_FL_DISABLED)
1887                         continue;
1888 
1889                 /* We need to update only differences of filter_hash */
1890                 in_old = !!ftrace_lookup_ip(old_hash, rec->ip);
1891                 in_new = !!ftrace_lookup_ip(new_hash, rec->ip);
1892                 if (in_old == in_new)
1893                         continue;
1894 
1895                 if (in_new) {
1896                         /* New entries must ensure no others are using it */
1897                         if (rec->flags & FTRACE_FL_IPMODIFY)
1898                                 goto rollback;
1899                         rec->flags |= FTRACE_FL_IPMODIFY;
1900                 } else /* Removed entry */
1901                         rec->flags &= ~FTRACE_FL_IPMODIFY;
1902         } while_for_each_ftrace_rec();
1903 
1904         return 0;
1905 
1906 rollback:
1907         end = rec;
1908 
1909         /* Roll back what we did above */
1910         do_for_each_ftrace_rec(pg, rec) {
1911 
1912                 if (rec->flags & FTRACE_FL_DISABLED)
1913                         continue;
1914 
1915                 if (rec == end)
1916                         goto err_out;
1917 
1918                 in_old = !!ftrace_lookup_ip(old_hash, rec->ip);
1919                 in_new = !!ftrace_lookup_ip(new_hash, rec->ip);
1920                 if (in_old == in_new)
1921                         continue;
1922 
1923                 if (in_new)
1924                         rec->flags &= ~FTRACE_FL_IPMODIFY;
1925                 else
1926                         rec->flags |= FTRACE_FL_IPMODIFY;
1927         } while_for_each_ftrace_rec();
1928 
1929 err_out:
1930         return -EBUSY;
1931 }
1932 
1933 static int ftrace_hash_ipmodify_enable(struct ftrace_ops *ops)
1934 {
1935         struct ftrace_hash *hash = ops->func_hash->filter_hash;
1936 
1937         if (ftrace_hash_empty(hash))
1938                 hash = NULL;
1939 
1940         return __ftrace_hash_update_ipmodify(ops, EMPTY_HASH, hash);
1941 }
1942 
1943 /* Disabling always succeeds */
1944 static void ftrace_hash_ipmodify_disable(struct ftrace_ops *ops)
1945 {
1946         struct ftrace_hash *hash = ops->func_hash->filter_hash;
1947 
1948         if (ftrace_hash_empty(hash))
1949                 hash = NULL;
1950 
1951         __ftrace_hash_update_ipmodify(ops, hash, EMPTY_HASH);
1952 }
1953 
1954 static int ftrace_hash_ipmodify_update(struct ftrace_ops *ops,
1955                                        struct ftrace_hash *new_hash)
1956 {
1957         struct ftrace_hash *old_hash = ops->func_hash->filter_hash;
1958 
1959         if (ftrace_hash_empty(old_hash))
1960                 old_hash = NULL;
1961 
1962         if (ftrace_hash_empty(new_hash))
1963                 new_hash = NULL;
1964 
1965         return __ftrace_hash_update_ipmodify(ops, old_hash, new_hash);
1966 }
1967 
1968 static void print_ip_ins(const char *fmt, const unsigned char *p)
1969 {
1970         int i;
1971 
1972         printk(KERN_CONT "%s", fmt);
1973 
1974         for (i = 0; i < MCOUNT_INSN_SIZE; i++)
1975                 printk(KERN_CONT "%s%02x", i ? ":" : "", p[i]);
1976 }
1977 
1978 static struct ftrace_ops *
1979 ftrace_find_tramp_ops_any(struct dyn_ftrace *rec);
1980 static struct ftrace_ops *
1981 ftrace_find_tramp_ops_next(struct dyn_ftrace *rec, struct ftrace_ops *ops);
1982 
1983 enum ftrace_bug_type ftrace_bug_type;
1984 const void *ftrace_expected;
1985 
1986 static void print_bug_type(void)
1987 {
1988         switch (ftrace_bug_type) {
1989         case FTRACE_BUG_UNKNOWN:
1990                 break;
1991         case FTRACE_BUG_INIT:
1992                 pr_info("Initializing ftrace call sites\n");
1993                 break;
1994         case FTRACE_BUG_NOP:
1995                 pr_info("Setting ftrace call site to NOP\n");
1996                 break;
1997         case FTRACE_BUG_CALL:
1998                 pr_info("Setting ftrace call site to call ftrace function\n");
1999                 break;
2000         case FTRACE_BUG_UPDATE:
2001                 pr_info("Updating ftrace call site to call a different ftrace function\n");
2002                 break;
2003         }
2004 }
2005 
2006 /**
2007  * ftrace_bug - report and shutdown function tracer
2008  * @failed: The failed type (EFAULT, EINVAL, EPERM)
2009  * @rec: The record that failed
2010  *
2011  * The arch code that enables or disables the function tracing
2012  * can call ftrace_bug() when it has detected a problem in
2013  * modifying the code. @failed should be one of either:
2014  * EFAULT - if the problem happens on reading the @ip address
2015  * EINVAL - if what is read at @ip is not what was expected
2016  * EPERM - if the problem happens on writting to the @ip address
2017  */
2018 void ftrace_bug(int failed, struct dyn_ftrace *rec)
2019 {
2020         unsigned long ip = rec ? rec->ip : 0;
2021 
2022         switch (failed) {
2023         case -EFAULT:
2024                 FTRACE_WARN_ON_ONCE(1);
2025                 pr_info("ftrace faulted on modifying ");
2026                 print_ip_sym(ip);
2027                 break;
2028         case -EINVAL:
2029                 FTRACE_WARN_ON_ONCE(1);
2030                 pr_info("ftrace failed to modify ");
2031                 print_ip_sym(ip);
2032                 print_ip_ins(" actual:   ", (unsigned char *)ip);
2033                 pr_cont("\n");
2034                 if (ftrace_expected) {
2035                         print_ip_ins(" expected: ", ftrace_expected);
2036                         pr_cont("\n");
2037                 }
2038                 break;
2039         case -EPERM:
2040                 FTRACE_WARN_ON_ONCE(1);
2041                 pr_info("ftrace faulted on writing ");
2042                 print_ip_sym(ip);
2043                 break;
2044         default:
2045                 FTRACE_WARN_ON_ONCE(1);
2046                 pr_info("ftrace faulted on unknown error ");
2047                 print_ip_sym(ip);
2048         }
2049         print_bug_type();
2050         if (rec) {
2051                 struct ftrace_ops *ops = NULL;
2052 
2053                 pr_info("ftrace record flags: %lx\n", rec->flags);
2054                 pr_cont(" (%ld)%s", ftrace_rec_count(rec),
2055                         rec->flags & FTRACE_FL_REGS ? " R" : "  ");
2056                 if (rec->flags & FTRACE_FL_TRAMP_EN) {
2057                         ops = ftrace_find_tramp_ops_any(rec);
2058                         if (ops) {
2059                                 do {
2060                                         pr_cont("\ttramp: %pS (%pS)",
2061                                                 (void *)ops->trampoline,
2062                                                 (void *)ops->func);
2063                                         ops = ftrace_find_tramp_ops_next(rec, ops);
2064                                 } while (ops);
2065                         } else
2066                                 pr_cont("\ttramp: ERROR!");
2067 
2068                 }
2069                 ip = ftrace_get_addr_curr(rec);
2070                 pr_cont("\n expected tramp: %lx\n", ip);
2071         }
2072 }
2073 
2074 static int ftrace_check_record(struct dyn_ftrace *rec, int enable, int update)
2075 {
2076         unsigned long flag = 0UL;
2077 
2078         ftrace_bug_type = FTRACE_BUG_UNKNOWN;
2079 
2080         if (rec->flags & FTRACE_FL_DISABLED)
2081                 return FTRACE_UPDATE_IGNORE;
2082 
2083         /*
2084          * If we are updating calls:
2085          *
2086          *   If the record has a ref count, then we need to enable it
2087          *   because someone is using it.
2088          *
2089          *   Otherwise we make sure its disabled.
2090          *
2091          * If we are disabling calls, then disable all records that
2092          * are enabled.
2093          */
2094         if (enable && ftrace_rec_count(rec))
2095                 flag = FTRACE_FL_ENABLED;
2096 
2097         /*
2098          * If enabling and the REGS flag does not match the REGS_EN, or
2099          * the TRAMP flag doesn't match the TRAMP_EN, then do not ignore
2100          * this record. Set flags to fail the compare against ENABLED.
2101          */
2102         if (flag) {
2103                 if (!(rec->flags & FTRACE_FL_REGS) != 
2104                     !(rec->flags & FTRACE_FL_REGS_EN))
2105                         flag |= FTRACE_FL_REGS;
2106 
2107                 if (!(rec->flags & FTRACE_FL_TRAMP) != 
2108                     !(rec->flags & FTRACE_FL_TRAMP_EN))
2109                         flag |= FTRACE_FL_TRAMP;
2110         }
2111 
2112         /* If the state of this record hasn't changed, then do nothing */
2113         if ((rec->flags & FTRACE_FL_ENABLED) == flag)
2114                 return FTRACE_UPDATE_IGNORE;
2115 
2116         if (flag) {
2117                 /* Save off if rec is being enabled (for return value) */
2118                 flag ^= rec->flags & FTRACE_FL_ENABLED;
2119 
2120                 if (update) {
2121                         rec->flags |= FTRACE_FL_ENABLED;
2122                         if (flag & FTRACE_FL_REGS) {
2123                                 if (rec->flags & FTRACE_FL_REGS)
2124                                         rec->flags |= FTRACE_FL_REGS_EN;
2125                                 else
2126                                         rec->flags &= ~FTRACE_FL_REGS_EN;
2127                         }
2128                         if (flag & FTRACE_FL_TRAMP) {
2129                                 if (rec->flags & FTRACE_FL_TRAMP)
2130                                         rec->flags |= FTRACE_FL_TRAMP_EN;
2131                                 else
2132                                         rec->flags &= ~FTRACE_FL_TRAMP_EN;
2133                         }
2134                 }
2135 
2136                 /*
2137                  * If this record is being updated from a nop, then
2138                  *   return UPDATE_MAKE_CALL.
2139                  * Otherwise,
2140                  *   return UPDATE_MODIFY_CALL to tell the caller to convert
2141                  *   from the save regs, to a non-save regs function or
2142                  *   vice versa, or from a trampoline call.
2143                  */
2144                 if (flag & FTRACE_FL_ENABLED) {
2145                         ftrace_bug_type = FTRACE_BUG_CALL;
2146                         return FTRACE_UPDATE_MAKE_CALL;
2147                 }
2148 
2149                 ftrace_bug_type = FTRACE_BUG_UPDATE;
2150                 return FTRACE_UPDATE_MODIFY_CALL;
2151         }
2152 
2153         if (update) {
2154                 /* If there's no more users, clear all flags */
2155                 if (!ftrace_rec_count(rec))
2156                         rec->flags = 0;
2157                 else
2158                         /*
2159                          * Just disable the record, but keep the ops TRAMP
2160                          * and REGS states. The _EN flags must be disabled though.
2161                          */
2162                         rec->flags &= ~(FTRACE_FL_ENABLED | FTRACE_FL_TRAMP_EN |
2163                                         FTRACE_FL_REGS_EN);
2164         }
2165 
2166         ftrace_bug_type = FTRACE_BUG_NOP;
2167         return FTRACE_UPDATE_MAKE_NOP;
2168 }
2169 
2170 /**
2171  * ftrace_update_record, set a record that now is tracing or not
2172  * @rec: the record to update
2173  * @enable: set to 1 if the record is tracing, zero to force disable
2174  *
2175  * The records that represent all functions that can be traced need
2176  * to be updated when tracing has been enabled.
2177  */
2178 int ftrace_update_record(struct dyn_ftrace *rec, int enable)
2179 {
2180         return ftrace_check_record(rec, enable, 1);
2181 }
2182 
2183 /**
2184  * ftrace_test_record, check if the record has been enabled or not
2185  * @rec: the record to test
2186  * @enable: set to 1 to check if enabled, 0 if it is disabled
2187  *
2188  * The arch code may need to test if a record is already set to
2189  * tracing to determine how to modify the function code that it
2190  * represents.
2191  */
2192 int ftrace_test_record(struct dyn_ftrace *rec, int enable)
2193 {
2194         return ftrace_check_record(rec, enable, 0);
2195 }
2196 
2197 static struct ftrace_ops *
2198 ftrace_find_tramp_ops_any(struct dyn_ftrace *rec)
2199 {
2200         struct ftrace_ops *op;
2201         unsigned long ip = rec->ip;
2202 
2203         do_for_each_ftrace_op(op, ftrace_ops_list) {
2204 
2205                 if (!op->trampoline)
2206                         continue;
2207 
2208                 if (hash_contains_ip(ip, op->func_hash))
2209                         return op;
2210         } while_for_each_ftrace_op(op);
2211 
2212         return NULL;
2213 }
2214 
2215 static struct ftrace_ops *
2216 ftrace_find_tramp_ops_next(struct dyn_ftrace *rec,
2217                            struct ftrace_ops *op)
2218 {
2219         unsigned long ip = rec->ip;
2220 
2221         while_for_each_ftrace_op(op) {
2222 
2223                 if (!op->trampoline)
2224                         continue;
2225 
2226                 if (hash_contains_ip(ip, op->func_hash))
2227                         return op;
2228         } 
2229 
2230         return NULL;
2231 }
2232 
2233 static struct ftrace_ops *
2234 ftrace_find_tramp_ops_curr(struct dyn_ftrace *rec)
2235 {
2236         struct ftrace_ops *op;
2237         unsigned long ip = rec->ip;
2238 
2239         /*
2240          * Need to check removed ops first.
2241          * If they are being removed, and this rec has a tramp,
2242          * and this rec is in the ops list, then it would be the
2243          * one with the tramp.
2244          */
2245         if (removed_ops) {
2246                 if (hash_contains_ip(ip, &removed_ops->old_hash))
2247                         return removed_ops;
2248         }
2249 
2250         /*
2251          * Need to find the current trampoline for a rec.
2252          * Now, a trampoline is only attached to a rec if there
2253          * was a single 'ops' attached to it. But this can be called
2254          * when we are adding another op to the rec or removing the
2255          * current one. Thus, if the op is being added, we can
2256          * ignore it because it hasn't attached itself to the rec
2257          * yet.
2258          *
2259          * If an ops is being modified (hooking to different functions)
2260          * then we don't care about the new functions that are being
2261          * added, just the old ones (that are probably being removed).
2262          *
2263          * If we are adding an ops to a function that already is using
2264          * a trampoline, it needs to be removed (trampolines are only
2265          * for single ops connected), then an ops that is not being
2266          * modified also needs to be checked.
2267          */
2268         do_for_each_ftrace_op(op, ftrace_ops_list) {
2269 
2270                 if (!op->trampoline)
2271                         continue;
2272 
2273                 /*
2274                  * If the ops is being added, it hasn't gotten to
2275                  * the point to be removed from this tree yet.
2276                  */
2277                 if (op->flags & FTRACE_OPS_FL_ADDING)
2278                         continue;
2279 
2280 
2281                 /*
2282                  * If the ops is being modified and is in the old
2283                  * hash, then it is probably being removed from this
2284                  * function.
2285                  */
2286                 if ((op->flags & FTRACE_OPS_FL_MODIFYING) &&
2287                     hash_contains_ip(ip, &op->old_hash))
2288                         return op;
2289                 /*
2290                  * If the ops is not being added or modified, and it's
2291                  * in its normal filter hash, then this must be the one
2292                  * we want!
2293                  */
2294                 if (!(op->flags & FTRACE_OPS_FL_MODIFYING) &&
2295                     hash_contains_ip(ip, op->func_hash))
2296                         return op;
2297 
2298         } while_for_each_ftrace_op(op);
2299 
2300         return NULL;
2301 }
2302 
2303 static struct ftrace_ops *
2304 ftrace_find_tramp_ops_new(struct dyn_ftrace *rec)
2305 {
2306         struct ftrace_ops *op;
2307         unsigned long ip = rec->ip;
2308 
2309         do_for_each_ftrace_op(op, ftrace_ops_list) {
2310                 /* pass rec in as regs to have non-NULL val */
2311                 if (hash_contains_ip(ip, op->func_hash))
2312                         return op;
2313         } while_for_each_ftrace_op(op);
2314 
2315         return NULL;
2316 }
2317 
2318 /**
2319  * ftrace_get_addr_new - Get the call address to set to
2320  * @rec:  The ftrace record descriptor
2321  *
2322  * If the record has the FTRACE_FL_REGS set, that means that it
2323  * wants to convert to a callback that saves all regs. If FTRACE_FL_REGS
2324  * is not not set, then it wants to convert to the normal callback.
2325  *
2326  * Returns the address of the trampoline to set to
2327  */
2328 unsigned long ftrace_get_addr_new(struct dyn_ftrace *rec)
2329 {
2330         struct ftrace_ops *ops;
2331 
2332         /* Trampolines take precedence over regs */
2333         if (rec->flags & FTRACE_FL_TRAMP) {
2334                 ops = ftrace_find_tramp_ops_new(rec);
2335                 if (FTRACE_WARN_ON(!ops || !ops->trampoline)) {
2336                         pr_warn("Bad trampoline accounting at: %p (%pS) (%lx)\n",
2337                                 (void *)rec->ip, (void *)rec->ip, rec->flags);
2338                         /* Ftrace is shutting down, return anything */
2339                         return (unsigned long)FTRACE_ADDR;
2340                 }
2341                 return ops->trampoline;
2342         }
2343 
2344         if (rec->flags & FTRACE_FL_REGS)
2345                 return (unsigned long)FTRACE_REGS_ADDR;
2346         else
2347                 return (unsigned long)FTRACE_ADDR;
2348 }
2349 
2350 /**
2351  * ftrace_get_addr_curr - Get the call address that is already there
2352  * @rec:  The ftrace record descriptor
2353  *
2354  * The FTRACE_FL_REGS_EN is set when the record already points to
2355  * a function that saves all the regs. Basically the '_EN' version
2356  * represents the current state of the function.
2357  *
2358  * Returns the address of the trampoline that is currently being called
2359  */
2360 unsigned long ftrace_get_addr_curr(struct dyn_ftrace *rec)
2361 {
2362         struct ftrace_ops *ops;
2363 
2364         /* Trampolines take precedence over regs */
2365         if (rec->flags & FTRACE_FL_TRAMP_EN) {
2366                 ops = ftrace_find_tramp_ops_curr(rec);
2367                 if (FTRACE_WARN_ON(!ops)) {
2368                         pr_warn("Bad trampoline accounting at: %p (%pS)\n",
2369                                 (void *)rec->ip, (void *)rec->ip);
2370                         /* Ftrace is shutting down, return anything */
2371                         return (unsigned long)FTRACE_ADDR;
2372                 }
2373                 return ops->trampoline;
2374         }
2375 
2376         if (rec->flags & FTRACE_FL_REGS_EN)
2377                 return (unsigned long)FTRACE_REGS_ADDR;
2378         else
2379                 return (unsigned long)FTRACE_ADDR;
2380 }
2381 
2382 static int
2383 __ftrace_replace_code(struct dyn_ftrace *rec, int enable)
2384 {
2385         unsigned long ftrace_old_addr;
2386         unsigned long ftrace_addr;
2387         int ret;
2388 
2389         ftrace_addr = ftrace_get_addr_new(rec);
2390 
2391         /* This needs to be done before we call ftrace_update_record */
2392         ftrace_old_addr = ftrace_get_addr_curr(rec);
2393 
2394         ret = ftrace_update_record(rec, enable);
2395 
2396         ftrace_bug_type = FTRACE_BUG_UNKNOWN;
2397 
2398         switch (ret) {
2399         case FTRACE_UPDATE_IGNORE:
2400                 return 0;
2401 
2402         case FTRACE_UPDATE_MAKE_CALL:
2403                 ftrace_bug_type = FTRACE_BUG_CALL;
2404                 return ftrace_make_call(rec, ftrace_addr);
2405 
2406         case FTRACE_UPDATE_MAKE_NOP:
2407                 ftrace_bug_type = FTRACE_BUG_NOP;
2408                 return ftrace_make_nop(NULL, rec, ftrace_old_addr);
2409 
2410         case FTRACE_UPDATE_MODIFY_CALL:
2411                 ftrace_bug_type = FTRACE_BUG_UPDATE;
2412                 return ftrace_modify_call(rec, ftrace_old_addr, ftrace_addr);
2413         }
2414 
2415         return -1; /* unknow ftrace bug */
2416 }
2417 
2418 void __weak ftrace_replace_code(int enable)
2419 {
2420         struct dyn_ftrace *rec;
2421         struct ftrace_page *pg;
2422         int failed;
2423 
2424         if (unlikely(ftrace_disabled))
2425                 return;
2426 
2427         do_for_each_ftrace_rec(pg, rec) {
2428 
2429                 if (rec->flags & FTRACE_FL_DISABLED)
2430                         continue;
2431 
2432                 failed = __ftrace_replace_code(rec, enable);
2433                 if (failed) {
2434                         ftrace_bug(failed, rec);
2435                         /* Stop processing */
2436                         return;
2437                 }
2438         } while_for_each_ftrace_rec();
2439 }
2440 
2441 struct ftrace_rec_iter {
2442         struct ftrace_page      *pg;
2443         int                     index;
2444 };
2445 
2446 /**
2447  * ftrace_rec_iter_start, start up iterating over traced functions
2448  *
2449  * Returns an iterator handle that is used to iterate over all
2450  * the records that represent address locations where functions
2451  * are traced.
2452  *
2453  * May return NULL if no records are available.
2454  */
2455 struct ftrace_rec_iter *ftrace_rec_iter_start(void)
2456 {
2457         /*
2458          * We only use a single iterator.
2459          * Protected by the ftrace_lock mutex.
2460          */
2461         static struct ftrace_rec_iter ftrace_rec_iter;
2462         struct ftrace_rec_iter *iter = &ftrace_rec_iter;
2463 
2464         iter->pg = ftrace_pages_start;
2465         iter->index = 0;
2466 
2467         /* Could have empty pages */
2468         while (iter->pg && !iter->pg->index)
2469                 iter->pg = iter->pg->next;
2470 
2471         if (!iter->pg)
2472                 return NULL;
2473 
2474         return iter;
2475 }
2476 
2477 /**
2478  * ftrace_rec_iter_next, get the next record to process.
2479  * @iter: The handle to the iterator.
2480  *
2481  * Returns the next iterator after the given iterator @iter.
2482  */
2483 struct ftrace_rec_iter *ftrace_rec_iter_next(struct ftrace_rec_iter *iter)
2484 {
2485         iter->index++;
2486 
2487         if (iter->index >= iter->pg->index) {
2488                 iter->pg = iter->pg->next;
2489                 iter->index = 0;
2490 
2491                 /* Could have empty pages */
2492                 while (iter->pg && !iter->pg->index)
2493                         iter->pg = iter->pg->next;
2494         }
2495 
2496         if (!iter->pg)
2497                 return NULL;
2498 
2499         return iter;
2500 }
2501 
2502 /**
2503  * ftrace_rec_iter_record, get the record at the iterator location
2504  * @iter: The current iterator location
2505  *
2506  * Returns the record that the current @iter is at.
2507  */
2508 struct dyn_ftrace *ftrace_rec_iter_record(struct ftrace_rec_iter *iter)
2509 {
2510         return &iter->pg->records[iter->index];
2511 }
2512 
2513 static int
2514 ftrace_code_disable(struct module *mod, struct dyn_ftrace *rec)
2515 {
2516         int ret;
2517 
2518         if (unlikely(ftrace_disabled))
2519                 return 0;
2520 
2521         ret = ftrace_make_nop(mod, rec, MCOUNT_ADDR);
2522         if (ret) {
2523                 ftrace_bug_type = FTRACE_BUG_INIT;
2524                 ftrace_bug(ret, rec);
2525                 return 0;
2526         }
2527         return 1;
2528 }
2529 
2530 /*
2531  * archs can override this function if they must do something
2532  * before the modifying code is performed.
2533  */
2534 int __weak ftrace_arch_code_modify_prepare(void)
2535 {
2536         return 0;
2537 }
2538 
2539 /*
2540  * archs can override this function if they must do something
2541  * after the modifying code is performed.
2542  */
2543 int __weak ftrace_arch_code_modify_post_process(void)
2544 {
2545         return 0;
2546 }
2547 
2548 void ftrace_modify_all_code(int command)
2549 {
2550         int update = command & FTRACE_UPDATE_TRACE_FUNC;
2551         int err = 0;
2552 
2553         /*
2554          * If the ftrace_caller calls a ftrace_ops func directly,
2555          * we need to make sure that it only traces functions it
2556          * expects to trace. When doing the switch of functions,
2557          * we need to update to the ftrace_ops_list_func first
2558          * before the transition between old and new calls are set,
2559          * as the ftrace_ops_list_func will check the ops hashes
2560          * to make sure the ops are having the right functions
2561          * traced.
2562          */
2563         if (update) {
2564                 err = ftrace_update_ftrace_func(ftrace_ops_list_func);
2565                 if (FTRACE_WARN_ON(err))
2566                         return;
2567         }
2568 
2569         if (command & FTRACE_UPDATE_CALLS)
2570                 ftrace_replace_code(1);
2571         else if (command & FTRACE_DISABLE_CALLS)
2572                 ftrace_replace_code(0);
2573 
2574         if (update && ftrace_trace_function != ftrace_ops_list_func) {
2575                 function_trace_op = set_function_trace_op;
2576                 smp_wmb();
2577                 /* If irqs are disabled, we are in stop machine */
2578                 if (!irqs_disabled())
2579                         smp_call_function(ftrace_sync_ipi, NULL, 1);
2580                 err = ftrace_update_ftrace_func(ftrace_trace_function);
2581                 if (FTRACE_WARN_ON(err))
2582                         return;
2583         }
2584 
2585         if (command & FTRACE_START_FUNC_RET)
2586                 err = ftrace_enable_ftrace_graph_caller();
2587         else if (command & FTRACE_STOP_FUNC_RET)
2588                 err = ftrace_disable_ftrace_graph_caller();
2589         FTRACE_WARN_ON(err);
2590 }
2591 
2592 static int __ftrace_modify_code(void *data)
2593 {
2594         int *command = data;
2595 
2596         ftrace_modify_all_code(*command);
2597 
2598         return 0;
2599 }
2600 
2601 /**
2602  * ftrace_run_stop_machine, go back to the stop machine method
2603  * @command: The command to tell ftrace what to do
2604  *
2605  * If an arch needs to fall back to the stop machine method, the
2606  * it can call this function.
2607  */
2608 void ftrace_run_stop_machine(int command)
2609 {
2610         stop_machine(__ftrace_modify_code, &command, NULL);
2611 }
2612 
2613 /**
2614  * arch_ftrace_update_code, modify the code to trace or not trace
2615  * @command: The command that needs to be done
2616  *
2617  * Archs can override this function if it does not need to
2618  * run stop_machine() to modify code.
2619  */
2620 void __weak arch_ftrace_update_code(int command)
2621 {
2622         ftrace_run_stop_machine(command);
2623 }
2624 
2625 static void ftrace_run_update_code(int command)
2626 {
2627         int ret;
2628 
2629         ret = ftrace_arch_code_modify_prepare();
2630         FTRACE_WARN_ON(ret);
2631         if (ret)
2632                 return;
2633 
2634         /*
2635          * By default we use stop_machine() to modify the code.
2636          * But archs can do what ever they want as long as it
2637          * is safe. The stop_machine() is the safest, but also
2638          * produces the most overhead.
2639          */
2640         arch_ftrace_update_code(command);
2641 
2642         ret = ftrace_arch_code_modify_post_process();
2643         FTRACE_WARN_ON(ret);
2644 }
2645 
2646 static void ftrace_run_modify_code(struct ftrace_ops *ops, int command,
2647                                    struct ftrace_ops_hash *old_hash)
2648 {
2649         ops->flags |= FTRACE_OPS_FL_MODIFYING;
2650         ops->old_hash.filter_hash = old_hash->filter_hash;
2651         ops->old_hash.notrace_hash = old_hash->notrace_hash;
2652         ftrace_run_update_code(command);
2653         ops->old_hash.filter_hash = NULL;
2654         ops->old_hash.notrace_hash = NULL;
2655         ops->flags &= ~FTRACE_OPS_FL_MODIFYING;
2656 }
2657 
2658 static ftrace_func_t saved_ftrace_func;
2659 static int ftrace_start_up;
2660 
2661 void __weak arch_ftrace_trampoline_free(struct ftrace_ops *ops)
2662 {
2663 }
2664 
2665 static void ftrace_startup_enable(int command)
2666 {
2667         if (saved_ftrace_func != ftrace_trace_function) {
2668                 saved_ftrace_func = ftrace_trace_function;
2669                 command |= FTRACE_UPDATE_TRACE_FUNC;
2670         }
2671 
2672         if (!command || !ftrace_enabled)
2673                 return;
2674 
2675         ftrace_run_update_code(command);
2676 }
2677 
2678 static void ftrace_startup_all(int command)
2679 {
2680         update_all_ops = true;
2681         ftrace_startup_enable(command);
2682         update_all_ops = false;
2683 }
2684 
2685 static int ftrace_startup(struct ftrace_ops *ops, int command)
2686 {
2687         int ret;
2688 
2689         if (unlikely(ftrace_disabled))
2690                 return -ENODEV;
2691 
2692         ret = __register_ftrace_function(ops);
2693         if (ret)
2694                 return ret;
2695 
2696         ftrace_start_up++;
2697 
2698         /*
2699          * Note that ftrace probes uses this to start up
2700          * and modify functions it will probe. But we still
2701          * set the ADDING flag for modification, as probes
2702          * do not have trampolines. If they add them in the
2703          * future, then the probes will need to distinguish
2704          * between adding and updating probes.
2705          */
2706         ops->flags |= FTRACE_OPS_FL_ENABLED | FTRACE_OPS_FL_ADDING;
2707 
2708         ret = ftrace_hash_ipmodify_enable(ops);
2709         if (ret < 0) {
2710                 /* Rollback registration process */
2711                 __unregister_ftrace_function(ops);
2712                 ftrace_start_up--;
2713                 ops->flags &= ~FTRACE_OPS_FL_ENABLED;
2714                 return ret;
2715         }
2716 
2717         if (ftrace_hash_rec_enable(ops, 1))
2718                 command |= FTRACE_UPDATE_CALLS;
2719 
2720         ftrace_startup_enable(command);
2721 
2722         ops->flags &= ~FTRACE_OPS_FL_ADDING;
2723 
2724         return 0;
2725 }
2726 
2727 static int ftrace_shutdown(struct ftrace_ops *ops, int command)
2728 {
2729         int ret;
2730 
2731         if (unlikely(ftrace_disabled))
2732                 return -ENODEV;
2733 
2734         ret = __unregister_ftrace_function(ops);
2735         if (ret)
2736                 return ret;
2737 
2738         ftrace_start_up--;
2739         /*
2740          * Just warn in case of unbalance, no need to kill ftrace, it's not
2741          * critical but the ftrace_call callers may be never nopped again after
2742          * further ftrace uses.
2743          */
2744         WARN_ON_ONCE(ftrace_start_up < 0);
2745 
2746         /* Disabling ipmodify never fails */
2747         ftrace_hash_ipmodify_disable(ops);
2748 
2749         if (ftrace_hash_rec_disable(ops, 1))
2750                 command |= FTRACE_UPDATE_CALLS;
2751 
2752         ops->flags &= ~FTRACE_OPS_FL_ENABLED;
2753 
2754         if (saved_ftrace_func != ftrace_trace_function) {
2755                 saved_ftrace_func = ftrace_trace_function;
2756                 command |= FTRACE_UPDATE_TRACE_FUNC;
2757         }
2758 
2759         if (!command || !ftrace_enabled) {
2760                 /*
2761                  * If these are dynamic or per_cpu ops, they still
2762                  * need their data freed. Since, function tracing is
2763                  * not currently active, we can just free them
2764                  * without synchronizing all CPUs.
2765                  */
2766                 if (ops->flags & FTRACE_OPS_FL_DYNAMIC)
2767                         goto free_ops;
2768 
2769                 return 0;
2770         }
2771 
2772         /*
2773          * If the ops uses a trampoline, then it needs to be
2774          * tested first on update.
2775          */
2776         ops->flags |= FTRACE_OPS_FL_REMOVING;
2777         removed_ops = ops;
2778 
2779         /* The trampoline logic checks the old hashes */
2780         ops->old_hash.filter_hash = ops->func_hash->filter_hash;
2781         ops->old_hash.notrace_hash = ops->func_hash->notrace_hash;
2782 
2783         ftrace_run_update_code(command);
2784 
2785         /*
2786          * If there's no more ops registered with ftrace, run a
2787          * sanity check to make sure all rec flags are cleared.
2788          */
2789         if (rcu_dereference_protected(ftrace_ops_list,
2790                         lockdep_is_held(&ftrace_lock)) == &ftrace_list_end) {
2791                 struct ftrace_page *pg;
2792                 struct dyn_ftrace *rec;
2793 
2794                 do_for_each_ftrace_rec(pg, rec) {
2795                         if (FTRACE_WARN_ON_ONCE(rec->flags & ~FTRACE_FL_DISABLED))
2796                                 pr_warn("  %pS flags:%lx\n",
2797                                         (void *)rec->ip, rec->flags);
2798                 } while_for_each_ftrace_rec();
2799         }
2800 
2801         ops->old_hash.filter_hash = NULL;
2802         ops->old_hash.notrace_hash = NULL;
2803 
2804         removed_ops = NULL;
2805         ops->flags &= ~FTRACE_OPS_FL_REMOVING;
2806 
2807         /*
2808          * Dynamic ops may be freed, we must make sure that all
2809          * callers are done before leaving this function.
2810          * The same goes for freeing the per_cpu data of the per_cpu
2811          * ops.
2812          */
2813         if (ops->flags & FTRACE_OPS_FL_DYNAMIC) {
2814                 /*
2815                  * We need to do a hard force of sched synchronization.
2816                  * This is because we use preempt_disable() to do RCU, but
2817                  * the function tracers can be called where RCU is not watching
2818                  * (like before user_exit()). We can not rely on the RCU
2819                  * infrastructure to do the synchronization, thus we must do it
2820                  * ourselves.
2821                  */
2822                 schedule_on_each_cpu(ftrace_sync);
2823 
2824                 /*
2825                  * When the kernel is preeptive, tasks can be preempted
2826                  * while on a ftrace trampoline. Just scheduling a task on
2827                  * a CPU is not good enough to flush them. Calling
2828                  * synchornize_rcu_tasks() will wait for those tasks to
2829                  * execute and either schedule voluntarily or enter user space.
2830                  */
2831                 if (IS_ENABLED(CONFIG_PREEMPT))
2832                         synchronize_rcu_tasks();
2833 
2834  free_ops:
2835                 arch_ftrace_trampoline_free(ops);
2836         }
2837 
2838         return 0;
2839 }
2840 
2841 static void ftrace_startup_sysctl(void)
2842 {
2843         int command;
2844 
2845         if (unlikely(ftrace_disabled))
2846                 return;
2847 
2848         /* Force update next time */
2849         saved_ftrace_func = NULL;
2850         /* ftrace_start_up is true if we want ftrace running */
2851         if (ftrace_start_up) {
2852                 command = FTRACE_UPDATE_CALLS;
2853                 if (ftrace_graph_active)
2854                         command |= FTRACE_START_FUNC_RET;
2855                 ftrace_startup_enable(command);
2856         }
2857 }
2858 
2859 static void ftrace_shutdown_sysctl(void)
2860 {
2861         int command;
2862 
2863         if (unlikely(ftrace_disabled))
2864                 return;
2865 
2866         /* ftrace_start_up is true if ftrace is running */
2867         if (ftrace_start_up) {
2868                 command = FTRACE_DISABLE_CALLS;
2869                 if (ftrace_graph_active)
2870                         command |= FTRACE_STOP_FUNC_RET;
2871                 ftrace_run_update_code(command);
2872         }
2873 }
2874 
2875 static u64              ftrace_update_time;
2876 unsigned long           ftrace_update_tot_cnt;
2877 
2878 static inline int ops_traces_mod(struct ftrace_ops *ops)
2879 {
2880         /*
2881          * Filter_hash being empty will default to trace module.
2882          * But notrace hash requires a test of individual module functions.
2883          */
2884         return ftrace_hash_empty(ops->func_hash->filter_hash) &&
2885                 ftrace_hash_empty(ops->func_hash->notrace_hash);
2886 }
2887 
2888 /*
2889  * Check if the current ops references the record.
2890  *
2891  * If the ops traces all functions, then it was already accounted for.
2892  * If the ops does not trace the current record function, skip it.
2893  * If the ops ignores the function via notrace filter, skip it.
2894  */
2895 static inline bool
2896 ops_references_rec(struct ftrace_ops *ops, struct dyn_ftrace *rec)
2897 {
2898         /* If ops isn't enabled, ignore it */
2899         if (!(ops->flags & FTRACE_OPS_FL_ENABLED))
2900                 return false;
2901 
2902         /* If ops traces all then it includes this function */
2903         if (ops_traces_mod(ops))
2904                 return true;
2905 
2906         /* The function must be in the filter */
2907         if (!ftrace_hash_empty(ops->func_hash->filter_hash) &&
2908             !__ftrace_lookup_ip(ops->func_hash->filter_hash, rec->ip))
2909                 return false;
2910 
2911         /* If in notrace hash, we ignore it too */
2912         if (ftrace_lookup_ip(ops->func_hash->notrace_hash, rec->ip))
2913                 return false;
2914 
2915         return true;
2916 }
2917 
2918 static int ftrace_update_code(struct module *mod, struct ftrace_page *new_pgs)
2919 {
2920         struct ftrace_page *pg;
2921         struct dyn_ftrace *p;
2922         u64 start, stop;
2923         unsigned long update_cnt = 0;
2924         unsigned long rec_flags = 0;
2925         int i;
2926 
2927         start = ftrace_now(raw_smp_processor_id());
2928 
2929         /*
2930          * When a module is loaded, this function is called to convert
2931          * the calls to mcount in its text to nops, and also to create
2932          * an entry in the ftrace data. Now, if ftrace is activated
2933          * after this call, but before the module sets its text to
2934          * read-only, the modification of enabling ftrace can fail if
2935          * the read-only is done while ftrace is converting the calls.
2936          * To prevent this, the module's records are set as disabled
2937          * and will be enabled after the call to set the module's text
2938          * to read-only.
2939          */
2940         if (mod)
2941                 rec_flags |= FTRACE_FL_DISABLED;
2942 
2943         for (pg = new_pgs; pg; pg = pg->next) {
2944 
2945                 for (i = 0; i < pg->index; i++) {
2946 
2947                         /* If something went wrong, bail without enabling anything */
2948                         if (unlikely(ftrace_disabled))
2949                                 return -1;
2950 
2951                         p = &pg->records[i];
2952                         p->flags = rec_flags;
2953 
2954 #ifndef CC_USING_NOP_MCOUNT
2955                         /*
2956                          * Do the initial record conversion from mcount jump
2957                          * to the NOP instructions.
2958                          */
2959                         if (!ftrace_code_disable(mod, p))
2960                                 break;
2961 #endif
2962 
2963                         update_cnt++;
2964                 }
2965         }
2966 
2967         stop = ftrace_now(raw_smp_processor_id());
2968         ftrace_update_time = stop - start;
2969         ftrace_update_tot_cnt += update_cnt;
2970 
2971         return 0;
2972 }
2973 
2974 static int ftrace_allocate_records(struct ftrace_page *pg, int count)
2975 {
2976         int order;
2977         int cnt;
2978 
2979         if (WARN_ON(!count))
2980                 return -EINVAL;
2981 
2982         order = get_count_order(DIV_ROUND_UP(count, ENTRIES_PER_PAGE));
2983 
2984         /*
2985          * We want to fill as much as possible. No more than a page
2986          * may be empty.
2987          */
2988         while ((PAGE_SIZE << order) / ENTRY_SIZE >= count + ENTRIES_PER_PAGE)
2989                 order--;
2990 
2991  again:
2992         pg->records = (void *)__get_free_pages(GFP_KERNEL | __GFP_ZERO, order);
2993 
2994         if (!pg->records) {
2995                 /* if we can't allocate this size, try something smaller */
2996                 if (!order)
2997                         return -ENOMEM;
2998                 order >>= 1;
2999                 goto again;
3000         }
3001 
3002         cnt = (PAGE_SIZE << order) / ENTRY_SIZE;
3003         pg->size = cnt;
3004 
3005         if (cnt > count)
3006                 cnt = count;
3007 
3008         return cnt;
3009 }
3010 
3011 static struct ftrace_page *
3012 ftrace_allocate_pages(unsigned long num_to_init)
3013 {
3014         struct ftrace_page *start_pg;
3015         struct ftrace_page *pg;
3016         int order;
3017         int cnt;
3018 
3019         if (!num_to_init)
3020                 return 0;
3021 
3022         start_pg = pg = kzalloc(sizeof(*pg), GFP_KERNEL);
3023         if (!pg)
3024                 return NULL;
3025 
3026         /*
3027          * Try to allocate as much as possible in one continues
3028          * location that fills in all of the space. We want to
3029          * waste as little space as possible.
3030          */
3031         for (;;) {
3032                 cnt = ftrace_allocate_records(pg, num_to_init);
3033                 if (cnt < 0)
3034                         goto free_pages;
3035 
3036                 num_to_init -= cnt;
3037                 if (!num_to_init)
3038                         break;
3039 
3040                 pg->next = kzalloc(sizeof(*pg), GFP_KERNEL);
3041                 if (!pg->next)
3042                         goto free_pages;
3043 
3044                 pg = pg->next;
3045         }
3046 
3047         return start_pg;
3048 
3049  free_pages:
3050         pg = start_pg;
3051         while (pg) {
3052                 order = get_count_order(pg->size / ENTRIES_PER_PAGE);
3053                 free_pages((unsigned long)pg->records, order);
3054                 start_pg = pg->next;
3055                 kfree(pg);
3056                 pg = start_pg;
3057         }
3058         pr_info("ftrace: FAILED to allocate memory for functions\n");
3059         return NULL;
3060 }
3061 
3062 #define FTRACE_BUFF_MAX (KSYM_SYMBOL_LEN+4) /* room for wildcards */
3063 
3064 struct ftrace_iterator {
3065         loff_t                          pos;
3066         loff_t                          func_pos;
3067         loff_t                          mod_pos;
3068         struct ftrace_page              *pg;
3069         struct dyn_ftrace               *func;
3070         struct ftrace_func_probe        *probe;
3071         struct ftrace_func_entry        *probe_entry;
3072         struct trace_parser             parser;
3073         struct ftrace_hash              *hash;
3074         struct ftrace_ops               *ops;
3075         struct trace_array              *tr;
3076         struct list_head                *mod_list;
3077         int                             pidx;
3078         int                             idx;
3079         unsigned                        flags;
3080 };
3081 
3082 static void *
3083 t_probe_next(struct seq_file *m, loff_t *pos)
3084 {
3085         struct ftrace_iterator *iter = m->private;
3086         struct trace_array *tr = iter->ops->private;
3087         struct list_head *func_probes;
3088         struct ftrace_hash *hash;
3089         struct list_head *next;
3090         struct hlist_node *hnd = NULL;
3091         struct hlist_head *hhd;
3092         int size;
3093 
3094         (*pos)++;
3095         iter->pos = *pos;
3096 
3097         if (!tr)
3098                 return NULL;
3099 
3100         func_probes = &tr->func_probes;
3101         if (list_empty(func_probes))
3102                 return NULL;
3103 
3104         if (!iter->probe) {
3105                 next = func_probes->next;
3106                 iter->probe = list_entry(next, struct ftrace_func_probe, list);
3107         }
3108 
3109         if (iter->probe_entry)
3110                 hnd = &iter->probe_entry->hlist;
3111 
3112         hash = iter->probe->ops.func_hash->filter_hash;
3113         size = 1 << hash->size_bits;
3114 
3115  retry:
3116         if (iter->pidx >= size) {
3117                 if (iter->probe->list.next == func_probes)
3118                         return NULL;
3119                 next = iter->probe->list.next;
3120                 iter->probe = list_entry(next, struct ftrace_func_probe, list);
3121                 hash = iter->probe->ops.func_hash->filter_hash;
3122                 size = 1 << hash->size_bits;
3123                 iter->pidx = 0;
3124         }
3125 
3126         hhd = &hash->buckets[iter->pidx];
3127 
3128         if (hlist_empty(hhd)) {
3129                 iter->pidx++;
3130                 hnd = NULL;
3131                 goto retry;
3132         }
3133 
3134         if (!hnd)
3135                 hnd = hhd->first;
3136         else {
3137                 hnd = hnd->next;
3138                 if (!hnd) {
3139                         iter->pidx++;
3140                         goto retry;
3141                 }
3142         }
3143 
3144         if (WARN_ON_ONCE(!hnd))
3145                 return NULL;
3146 
3147         iter->probe_entry = hlist_entry(hnd, struct ftrace_func_entry, hlist);
3148 
3149         return iter;
3150 }
3151 
3152 static void *t_probe_start(struct seq_file *m, loff_t *pos)
3153 {
3154         struct ftrace_iterator *iter = m->private;
3155         void *p = NULL;
3156         loff_t l;
3157 
3158         if (!(iter->flags & FTRACE_ITER_DO_PROBES))
3159                 return NULL;
3160 
3161         if (iter->mod_pos > *pos)
3162                 return NULL;
3163 
3164         iter->probe = NULL;
3165         iter->probe_entry = NULL;
3166         iter->pidx = 0;
3167         for (l = 0; l <= (*pos - iter->mod_pos); ) {
3168                 p = t_probe_next(m, &l);
3169                 if (!p)
3170                         break;
3171         }
3172         if (!p)
3173                 return NULL;
3174 
3175         /* Only set this if we have an item */
3176         iter->flags |= FTRACE_ITER_PROBE;
3177 
3178         return iter;
3179 }
3180 
3181 static int
3182 t_probe_show(struct seq_file *m, struct ftrace_iterator *iter)
3183 {
3184         struct ftrace_func_entry *probe_entry;
3185         struct ftrace_probe_ops *probe_ops;
3186         struct ftrace_func_probe *probe;
3187 
3188         probe = iter->probe;
3189         probe_entry = iter->probe_entry;
3190 
3191         if (WARN_ON_ONCE(!probe || !probe_entry))
3192                 return -EIO;
3193 
3194         probe_ops = probe->probe_ops;
3195 
3196         if (probe_ops->print)
3197                 return probe_ops->print(m, probe_entry->ip, probe_ops, probe->data);
3198 
3199         seq_printf(m, "%ps:%ps\n", (void *)probe_entry->ip,
3200                    (void *)probe_ops->func);
3201 
3202         return 0;
3203 }
3204 
3205 static void *
3206 t_mod_next(struct seq_file *m, loff_t *pos)
3207 {
3208         struct ftrace_iterator *iter = m->private;
3209         struct trace_array *tr = iter->tr;
3210 
3211         (*pos)++;
3212         iter->pos = *pos;
3213 
3214         iter->mod_list = iter->mod_list->next;
3215 
3216         if (iter->mod_list == &tr->mod_trace ||
3217             iter->mod_list == &tr->mod_notrace) {
3218                 iter->flags &= ~FTRACE_ITER_MOD;
3219                 return NULL;
3220         }
3221 
3222         iter->mod_pos = *pos;
3223 
3224         return iter;
3225 }
3226 
3227 static void *t_mod_start(struct seq_file *m, loff_t *pos)
3228 {
3229         struct ftrace_iterator *iter = m->private;
3230         void *p = NULL;
3231         loff_t l;
3232 
3233         if (iter->func_pos > *pos)
3234                 return NULL;
3235 
3236         iter->mod_pos = iter->func_pos;
3237 
3238         /* probes are only available if tr is set */
3239         if (!iter->tr)
3240                 return NULL;
3241 
3242         for (l = 0; l <= (*pos - iter->func_pos); ) {
3243                 p = t_mod_next(m, &l);
3244                 if (!p)
3245                         break;
3246         }
3247         if (!p) {
3248                 iter->flags &= ~FTRACE_ITER_MOD;
3249                 return t_probe_start(m, pos);
3250         }
3251 
3252         /* Only set this if we have an item */
3253         iter->flags |= FTRACE_ITER_MOD;
3254 
3255         return iter;
3256 }
3257 
3258 static int
3259 t_mod_show(struct seq_file *m, struct ftrace_iterator *iter)
3260 {
3261         struct ftrace_mod_load *ftrace_mod;
3262         struct trace_array *tr = iter->tr;
3263 
3264         if (WARN_ON_ONCE(!iter->mod_list) ||
3265                          iter->mod_list == &tr->mod_trace ||
3266                          iter->mod_list == &tr->mod_notrace)
3267                 return -EIO;
3268 
3269         ftrace_mod = list_entry(iter->mod_list, struct ftrace_mod_load, list);
3270 
3271         if (ftrace_mod->func)
3272                 seq_printf(m, "%s", ftrace_mod->func);
3273         else
3274                 seq_putc(m, '*');
3275 
3276         seq_printf(m, ":mod:%s\n", ftrace_mod->module);
3277 
3278         return 0;
3279 }
3280 
3281 static void *
3282 t_func_next(struct seq_file *m, loff_t *pos)
3283 {
3284         struct ftrace_iterator *iter = m->private;
3285         struct dyn_ftrace *rec = NULL;
3286 
3287         (*pos)++;
3288 
3289  retry:
3290         if (iter->idx >= iter->pg->index) {
3291                 if (iter->pg->next) {
3292                         iter->pg = iter->pg->next;
3293                         iter->idx = 0;
3294                         goto retry;
3295                 }
3296         } else {
3297                 rec = &iter->pg->records[iter->idx++];
3298                 if (((iter->flags & (FTRACE_ITER_FILTER | FTRACE_ITER_NOTRACE)) &&
3299                      !ftrace_lookup_ip(iter->hash, rec->ip)) ||
3300 
3301                     ((iter->flags & FTRACE_ITER_ENABLED) &&
3302                      !(rec->flags & FTRACE_FL_ENABLED))) {
3303 
3304                         rec = NULL;
3305                         goto retry;
3306                 }
3307         }
3308 
3309         if (!rec)
3310                 return NULL;
3311 
3312         iter->pos = iter->func_pos = *pos;
3313         iter->func = rec;
3314 
3315         return iter;
3316 }
3317 
3318 static void *
3319 t_next(struct seq_file *m, void *v, loff_t *pos)
3320 {
3321         struct ftrace_iterator *iter = m->private;
3322         loff_t l = *pos; /* t_probe_start() must use original pos */
3323         void *ret;
3324 
3325         if (unlikely(ftrace_disabled))
3326                 return NULL;
3327 
3328         if (iter->flags & FTRACE_ITER_PROBE)
3329                 return t_probe_next(m, pos);
3330 
3331         if (iter->flags & FTRACE_ITER_MOD)
3332                 return t_mod_next(m, pos);
3333 
3334         if (iter->flags & FTRACE_ITER_PRINTALL) {
3335                 /* next must increment pos, and t_probe_start does not */
3336                 (*pos)++;
3337                 return t_mod_start(m, &l);
3338         }
3339 
3340         ret = t_func_next(m, pos);
3341 
3342         if (!ret)
3343                 return t_mod_start(m, &l);
3344 
3345         return ret;
3346 }
3347 
3348 static void reset_iter_read(struct ftrace_iterator *iter)
3349 {
3350         iter->pos = 0;
3351         iter->func_pos = 0;
3352         iter->flags &= ~(FTRACE_ITER_PRINTALL | FTRACE_ITER_PROBE | FTRACE_ITER_MOD);
3353 }
3354 
3355 static void *t_start(struct seq_file *m, loff_t *pos)
3356 {
3357         struct ftrace_iterator *iter = m->private;
3358         void *p = NULL;
3359         loff_t l;
3360 
3361         mutex_lock(&ftrace_lock);
3362 
3363         if (unlikely(ftrace_disabled))
3364                 return NULL;
3365 
3366         /*
3367          * If an lseek was done, then reset and start from beginning.
3368          */
3369         if (*pos < iter->pos)
3370                 reset_iter_read(iter);
3371 
3372         /*
3373          * For set_ftrace_filter reading, if we have the filter
3374          * off, we can short cut and just print out that all
3375          * functions are enabled.
3376          */
3377         if ((iter->flags & (FTRACE_ITER_FILTER | FTRACE_ITER_NOTRACE)) &&
3378             ftrace_hash_empty(iter->hash)) {
3379                 iter->func_pos = 1; /* Account for the message */
3380                 if (*pos > 0)
3381                         return t_mod_start(m, pos);
3382                 iter->flags |= FTRACE_ITER_PRINTALL;
3383                 /* reset in case of seek/pread */
3384                 iter->flags &= ~FTRACE_ITER_PROBE;
3385                 return iter;
3386         }
3387 
3388         if (iter->flags & FTRACE_ITER_MOD)
3389                 return t_mod_start(m, pos);
3390 
3391         /*
3392          * Unfortunately, we need to restart at ftrace_pages_start
3393          * every time we let go of the ftrace_mutex. This is because
3394          * those pointers can change without the lock.
3395          */
3396         iter->pg = ftrace_pages_start;
3397         iter->idx = 0;
3398         for (l = 0; l <= *pos; ) {
3399                 p = t_func_next(m, &l);
3400                 if (!p)
3401                         break;
3402         }
3403 
3404         if (!p)
3405                 return t_mod_start(m, pos);
3406 
3407         return iter;
3408 }
3409 
3410 static void t_stop(struct seq_file *m, void *p)
3411 {
3412         mutex_unlock(&ftrace_lock);
3413 }
3414 
3415 void * __weak
3416 arch_ftrace_trampoline_func(struct ftrace_ops *ops, struct dyn_ftrace *rec)
3417 {
3418         return NULL;
3419 }
3420 
3421 static void add_trampoline_func(struct seq_file *m, struct ftrace_ops *ops,
3422                                 struct dyn_ftrace *rec)
3423 {
3424         void *ptr;
3425 
3426         ptr = arch_ftrace_trampoline_func(ops, rec);
3427         if (ptr)
3428                 seq_printf(m, " ->%pS", ptr);
3429 }
3430 
3431 static int t_show(struct seq_file *m, void *v)
3432 {
3433         struct ftrace_iterator *iter = m->private;
3434         struct dyn_ftrace *rec;
3435 
3436         if (iter->flags & FTRACE_ITER_PROBE)
3437                 return t_probe_show(m, iter);
3438 
3439         if (iter->flags & FTRACE_ITER_MOD)
3440                 return t_mod_show(m, iter);
3441 
3442         if (iter->flags & FTRACE_ITER_PRINTALL) {
3443                 if (iter->flags & FTRACE_ITER_NOTRACE)
3444                         seq_puts(m, "#### no functions disabled ####\n");
3445                 else
3446                         seq_puts(m, "#### all functions enabled ####\n");
3447                 return 0;
3448         }
3449 
3450         rec = iter->func;
3451 
3452         if (!rec)
3453                 return 0;
3454 
3455         seq_printf(m, "%ps", (void *)rec->ip);
3456         if (iter->flags & FTRACE_ITER_ENABLED) {
3457                 struct ftrace_ops *ops;
3458 
3459                 seq_printf(m, " (%ld)%s%s",
3460                            ftrace_rec_count(rec),
3461                            rec->flags & FTRACE_FL_REGS ? " R" : "  ",
3462                            rec->flags & FTRACE_FL_IPMODIFY ? " I" : "  ");
3463                 if (rec->flags & FTRACE_FL_TRAMP_EN) {
3464                         ops = ftrace_find_tramp_ops_any(rec);
3465                         if (ops) {
3466                                 do {
3467                                         seq_printf(m, "\ttramp: %pS (%pS)",
3468                                                    (void *)ops->trampoline,
3469                                                    (void *)ops->func);
3470                                         add_trampoline_func(m, ops, rec);
3471                                         ops = ftrace_find_tramp_ops_next(rec, ops);
3472                                 } while (ops);
3473                         } else
3474                                 seq_puts(m, "\ttramp: ERROR!");
3475                 } else {
3476                         add_trampoline_func(m, NULL, rec);
3477                 }
3478         }       
3479 
3480         seq_putc(m, '\n');
3481 
3482         return 0;
3483 }
3484 
3485 static const struct seq_operations show_ftrace_seq_ops = {
3486         .start = t_start,
3487         .next = t_next,
3488         .stop = t_stop,
3489         .show = t_show,
3490 };
3491 
3492 static int
3493 ftrace_avail_open(struct inode *inode, struct file *file)
3494 {
3495         struct ftrace_iterator *iter;
3496 
3497         if (unlikely(ftrace_disabled))
3498                 return -ENODEV;
3499 
3500         iter = __seq_open_private(file, &show_ftrace_seq_ops, sizeof(*iter));
3501         if (!iter)
3502                 return -ENOMEM;
3503 
3504         iter->pg = ftrace_pages_start;
3505         iter->ops = &global_ops;
3506 
3507         return 0;
3508 }
3509 
3510 static int
3511 ftrace_enabled_open(struct inode *inode, struct file *file)
3512 {
3513         struct ftrace_iterator *iter;
3514 
3515         iter = __seq_open_private(file, &show_ftrace_seq_ops, sizeof(*iter));
3516         if (!iter)
3517                 return -ENOMEM;
3518 
3519         iter->pg = ftrace_pages_start;
3520         iter->flags = FTRACE_ITER_ENABLED;
3521         iter->ops = &global_ops;
3522 
3523         return 0;
3524 }
3525 
3526 /**
3527  * ftrace_regex_open - initialize function tracer filter files
3528  * @ops: The ftrace_ops that hold the hash filters
3529  * @flag: The type of filter to process
3530  * @inode: The inode, usually passed in to your open routine
3531  * @file: The file, usually passed in to your open routine
3532  *
3533  * ftrace_regex_open() initializes the filter files for the
3534  * @ops. Depending on @flag it may process the filter hash or
3535  * the notrace hash of @ops. With this called from the open
3536  * routine, you can use ftrace_filter_write() for the write
3537  * routine if @flag has FTRACE_ITER_FILTER set, or
3538  * ftrace_notrace_write() if @flag has FTRACE_ITER_NOTRACE set.
3539  * tracing_lseek() should be used as the lseek routine, and
3540  * release must call ftrace_regex_release().
3541  */
3542 int
3543 ftrace_regex_open(struct ftrace_ops *ops, int flag,
3544                   struct inode *inode, struct file *file)
3545 {
3546         struct ftrace_iterator *iter;
3547         struct ftrace_hash *hash;
3548         struct list_head *mod_head;
3549         struct trace_array *tr = ops->private;
3550         int ret = 0;
3551 
3552         ftrace_ops_init(ops);
3553 
3554         if (unlikely(ftrace_disabled))
3555                 return -ENODEV;
3556 
3557         iter = kzalloc(sizeof(*iter), GFP_KERNEL);
3558         if (!iter)
3559                 return -ENOMEM;
3560 
3561         if (trace_parser_get_init(&iter->parser, FTRACE_BUFF_MAX)) {
3562                 kfree(iter);
3563                 return -ENOMEM;
3564         }
3565 
3566         iter->ops = ops;
3567         iter->flags = flag;
3568         iter->tr = tr;
3569 
3570         mutex_lock(&ops->func_hash->regex_lock);
3571 
3572         if (flag & FTRACE_ITER_NOTRACE) {
3573                 hash = ops->func_hash->notrace_hash;
3574                 mod_head = tr ? &tr->mod_notrace : NULL;
3575         } else {
3576                 hash = ops->func_hash->filter_hash;
3577                 mod_head = tr ? &tr->mod_trace : NULL;
3578         }
3579 
3580         iter->mod_list = mod_head;
3581 
3582         if (file->f_mode & FMODE_WRITE) {
3583                 const int size_bits = FTRACE_HASH_DEFAULT_BITS;
3584 
3585                 if (file->f_flags & O_TRUNC) {
3586                         iter->hash = alloc_ftrace_hash(size_bits);
3587                         clear_ftrace_mod_list(mod_head);
3588                 } else {
3589                         iter->hash = alloc_and_copy_ftrace_hash(size_bits, hash);
3590                 }
3591 
3592                 if (!iter->hash) {
3593                         trace_parser_put(&iter->parser);
3594                         kfree(iter);
3595                         ret = -ENOMEM;
3596                         goto out_unlock;
3597                 }
3598         } else
3599                 iter->hash = hash;
3600 
3601         if (file->f_mode & FMODE_READ) {
3602                 iter->pg = ftrace_pages_start;
3603 
3604                 ret = seq_open(file, &show_ftrace_seq_ops);
3605                 if (!ret) {
3606                         struct seq_file *m = file->private_data;
3607                         m->private = iter;
3608                 } else {
3609                         /* Failed */
3610                         free_ftrace_hash(iter->hash);
3611                         trace_parser_put(&iter->parser);
3612                         kfree(iter);
3613                 }
3614         } else
3615                 file->private_data = iter;
3616 
3617  out_unlock:
3618         mutex_unlock(&ops->func_hash->regex_lock);
3619 
3620         return ret;
3621 }
3622 
3623 static int
3624 ftrace_filter_open(struct inode *inode, struct file *file)
3625 {
3626         struct ftrace_ops *ops = inode->i_private;
3627 
3628         return ftrace_regex_open(ops,
3629                         FTRACE_ITER_FILTER | FTRACE_ITER_DO_PROBES,
3630                         inode, file);
3631 }
3632 
3633 static int
3634 ftrace_notrace_open(struct inode *inode, struct file *file)
3635 {
3636         struct ftrace_ops *ops = inode->i_private;
3637 
3638         return ftrace_regex_open(ops, FTRACE_ITER_NOTRACE,
3639                                  inode, file);
3640 }
3641 
3642 /* Type for quick search ftrace basic regexes (globs) from filter_parse_regex */
3643 struct ftrace_glob {
3644         char *search;
3645         unsigned len;
3646         int type;
3647 };
3648 
3649 /*
3650  * If symbols in an architecture don't correspond exactly to the user-visible
3651  * name of what they represent, it is possible to define this function to
3652  * perform the necessary adjustments.
3653 */
3654 char * __weak arch_ftrace_match_adjust(char *str, const char *search)
3655 {
3656         return str;
3657 }
3658 
3659 static int ftrace_match(char *str, struct ftrace_glob *g)
3660 {
3661         int matched = 0;
3662         int slen;
3663 
3664         str = arch_ftrace_match_adjust(str, g->search);
3665 
3666         switch (g->type) {
3667         case MATCH_FULL:
3668                 if (strcmp(str, g->search) == 0)
3669                         matched = 1;
3670                 break;
3671         case MATCH_FRONT_ONLY:
3672                 if (strncmp(str, g->search, g->len) == 0)
3673                         matched = 1;
3674                 break;
3675         case MATCH_MIDDLE_ONLY:
3676                 if (strstr(str, g->search))
3677                         matched = 1;
3678                 break;
3679         case MATCH_END_ONLY:
3680                 slen = strlen(str);
3681                 if (slen >= g->len &&
3682                     memcmp(str + slen - g->len, g->search, g->len) == 0)
3683                         matched = 1;
3684                 break;
3685         case MATCH_GLOB:
3686                 if (glob_match(g->search, str))
3687                         matched = 1;
3688                 break;
3689         }
3690 
3691         return matched;
3692 }
3693 
3694 static int
3695 enter_record(struct ftrace_hash *hash, struct dyn_ftrace *rec, int clear_filter)
3696 {
3697         struct ftrace_func_entry *entry;
3698         int ret = 0;
3699 
3700         entry = ftrace_lookup_ip(hash, rec->ip);
3701         if (clear_filter) {
3702                 /* Do nothing if it doesn't exist */
3703                 if (!entry)
3704                         return 0;
3705 
3706                 free_hash_entry(hash, entry);
3707         } else {
3708                 /* Do nothing if it exists */
3709                 if (entry)
3710                         return 0;
3711 
3712                 ret = add_hash_entry(hash, rec->ip);
3713         }
3714         return ret;
3715 }
3716 
3717 static int
3718 ftrace_match_record(struct dyn_ftrace *rec, struct ftrace_glob *func_g,
3719                 struct ftrace_glob *mod_g, int exclude_mod)
3720 {
3721         char str[KSYM_SYMBOL_LEN];
3722         char *modname;
3723 
3724         kallsyms_lookup(rec->ip, NULL, NULL, &modname, str);
3725 
3726         if (mod_g) {
3727                 int mod_matches = (modname) ? ftrace_match(modname, mod_g) : 0;
3728 
3729                 /* blank module name to match all modules */
3730                 if (!mod_g->len) {
3731                         /* blank module globbing: modname xor exclude_mod */
3732                         if (!exclude_mod != !modname)
3733                                 goto func_match;
3734                         return 0;
3735                 }
3736 
3737                 /*
3738                  * exclude_mod is set to trace everything but the given
3739                  * module. If it is set and the module matches, then
3740                  * return 0. If it is not set, and the module doesn't match
3741                  * also return 0. Otherwise, check the function to see if
3742                  * that matches.
3743                  */
3744                 if (!mod_matches == !exclude_mod)
3745                         return 0;
3746 func_match:
3747                 /* blank search means to match all funcs in the mod */
3748                 if (!func_g->len)
3749                         return 1;
3750         }
3751 
3752         return ftrace_match(str, func_g);
3753 }
3754 
3755 static int
3756 match_records(struct ftrace_hash *hash, char *func, int len, char *mod)
3757 {
3758         struct ftrace_page *pg;
3759         struct dyn_ftrace *rec;
3760         struct ftrace_glob func_g = { .type = MATCH_FULL };
3761         struct ftrace_glob mod_g = { .type = MATCH_FULL };
3762         struct ftrace_glob *mod_match = (mod) ? &mod_g : NULL;
3763         int exclude_mod = 0;
3764         int found = 0;
3765         int ret;
3766         int clear_filter = 0;
3767 
3768         if (func) {
3769                 func_g.type = filter_parse_regex(func, len, &func_g.search,
3770                                                  &clear_filter);
3771                 func_g.len = strlen(func_g.search);
3772         }
3773 
3774         if (mod) {
3775                 mod_g.type = filter_parse_regex(mod, strlen(mod),
3776                                 &mod_g.search, &exclude_mod);
3777                 mod_g.len = strlen(mod_g.search);
3778         }
3779 
3780         mutex_lock(&ftrace_lock);
3781 
3782         if (unlikely(ftrace_disabled))
3783                 goto out_unlock;
3784 
3785         do_for_each_ftrace_rec(pg, rec) {
3786 
3787                 if (rec->flags & FTRACE_FL_DISABLED)
3788                         continue;
3789 
3790                 if (ftrace_match_record(rec, &func_g, mod_match, exclude_mod)) {
3791                         ret = enter_record(hash, rec, clear_filter);
3792                         if (ret < 0) {
3793                                 found = ret;
3794                                 goto out_unlock;
3795                         }
3796                         found = 1;
3797                 }
3798         } while_for_each_ftrace_rec();
3799  out_unlock:
3800         mutex_unlock(&ftrace_lock);
3801 
3802         return found;
3803 }
3804 
3805 static int
3806 ftrace_match_records(struct ftrace_hash *hash, char *buff, int len)
3807 {
3808         return match_records(hash, buff, len, NULL);
3809 }
3810 
3811 static void ftrace_ops_update_code(struct ftrace_ops *ops,
3812                                    struct ftrace_ops_hash *old_hash)
3813 {
3814         struct ftrace_ops *op;
3815 
3816         if (!ftrace_enabled)
3817                 return;
3818 
3819         if (ops->flags & FTRACE_OPS_FL_ENABLED) {
3820                 ftrace_run_modify_code(ops, FTRACE_UPDATE_CALLS, old_hash);
3821                 return;
3822         }
3823 
3824         /*
3825          * If this is the shared global_ops filter, then we need to
3826          * check if there is another ops that shares it, is enabled.
3827          * If so, we still need to run the modify code.
3828          */
3829         if (ops->func_hash != &global_ops.local_hash)
3830                 return;
3831 
3832         do_for_each_ftrace_op(op, ftrace_ops_list) {
3833                 if (op->func_hash == &global_ops.local_hash &&
3834                     op->flags & FTRACE_OPS_FL_ENABLED) {
3835                         ftrace_run_modify_code(op, FTRACE_UPDATE_CALLS, old_hash);
3836                         /* Only need to do this once */
3837                         return;
3838                 }
3839         } while_for_each_ftrace_op(op);
3840 }
3841 
3842 static int ftrace_hash_move_and_update_ops(struct ftrace_ops *ops,
3843                                            struct ftrace_hash **orig_hash,
3844                                            struct ftrace_hash *hash,
3845                                            int enable)
3846 {
3847         struct ftrace_ops_hash old_hash_ops;
3848         struct ftrace_hash *old_hash;
3849         int ret;
3850 
3851         old_hash = *orig_hash;
3852         old_hash_ops.filter_hash = ops->func_hash->filter_hash;
3853         old_hash_ops.notrace_hash = ops->func_hash->notrace_hash;
3854         ret = ftrace_hash_move(ops, enable, orig_hash, hash);
3855         if (!ret) {
3856                 ftrace_ops_update_code(ops, &old_hash_ops);
3857                 free_ftrace_hash_rcu(old_hash);
3858         }
3859         return ret;
3860 }
3861 
3862 static bool module_exists(const char *module)
3863 {
3864         /* All modules have the symbol __this_module */
3865         const char this_mod[] = "__this_module";
3866         char modname[MAX_PARAM_PREFIX_LEN + sizeof(this_mod) + 2];
3867         unsigned long val;
3868         int n;
3869 
3870         n = snprintf(modname, sizeof(modname), "%s:%s", module, this_mod);
3871 
3872         if (n > sizeof(modname) - 1)
3873                 return false;
3874 
3875         val = module_kallsyms_lookup_name(modname);
3876         return val != 0;
3877 }
3878 
3879 static int cache_mod(struct trace_array *tr,
3880                      const char *func, char *module, int enable)
3881 {
3882         struct ftrace_mod_load *ftrace_mod, *n;
3883         struct list_head *head = enable ? &tr->mod_trace : &tr->mod_notrace;
3884         int ret;
3885 
3886         mutex_lock(&ftrace_lock);
3887 
3888         /* We do not cache inverse filters */
3889         if (func[0] == '!') {
3890                 func++;
3891                 ret = -EINVAL;
3892 
3893                 /* Look to remove this hash */
3894                 list_for_each_entry_safe(ftrace_mod, n, head, list) {
3895                         if (strcmp(ftrace_mod->module, module) != 0)
3896                                 continue;
3897 
3898                         /* no func matches all */
3899                         if (strcmp(func, "*") == 0 ||
3900                             (ftrace_mod->func &&
3901                              strcmp(ftrace_mod->func, func) == 0)) {
3902                                 ret = 0;
3903                                 free_ftrace_mod(ftrace_mod);
3904                                 continue;
3905                         }
3906                 }
3907                 goto out;
3908         }
3909 
3910         ret = -EINVAL;
3911         /* We only care about modules that have not been loaded yet */
3912         if (module_exists(module))
3913                 goto out;
3914 
3915         /* Save this string off, and execute it when the module is loaded */
3916         ret = ftrace_add_mod(tr, func, module, enable);
3917  out:
3918         mutex_unlock(&ftrace_lock);
3919 
3920         return ret;
3921 }
3922 
3923 static int
3924 ftrace_set_regex(struct ftrace_ops *ops, unsigned char *buf, int len,
3925                  int reset, int enable);
3926 
3927 #ifdef CONFIG_MODULES
3928 static void process_mod_list(struct list_head *head, struct ftrace_ops *ops,
3929                              char *mod, bool enable)
3930 {
3931         struct ftrace_mod_load *ftrace_mod, *n;
3932         struct ftrace_hash **orig_hash, *new_hash;
3933         LIST_HEAD(process_mods);
3934         char *func;
3935         int ret;
3936 
3937         mutex_lock(&ops->func_hash->regex_lock);
3938 
3939         if (enable)
3940                 orig_hash = &ops->func_hash->filter_hash;
3941         else
3942                 orig_hash = &ops->func_hash->notrace_hash;
3943 
3944         new_hash = alloc_and_copy_ftrace_hash(FTRACE_HASH_DEFAULT_BITS,
3945                                               *orig_hash);
3946         if (!new_hash)
3947                 goto out; /* warn? */
3948 
3949         mutex_lock(&ftrace_lock);
3950 
3951         list_for_each_entry_safe(ftrace_mod, n, head, list) {
3952 
3953                 if (strcmp(ftrace_mod->module, mod) != 0)
3954                         continue;
3955 
3956                 if (ftrace_mod->func)
3957                         func = kstrdup(ftrace_mod->func, GFP_KERNEL);
3958                 else
3959                         func = kstrdup("*", GFP_KERNEL);
3960 
3961                 if (!func) /* warn? */
3962                         continue;
3963 
3964                 list_del(&ftrace_mod->list);
3965                 list_add(&ftrace_mod->list, &process_mods);
3966 
3967                 /* Use the newly allocated func, as it may be "*" */
3968                 kfree(ftrace_mod->func);
3969                 ftrace_mod->func = func;
3970         }
3971 
3972         mutex_unlock(&ftrace_lock);
3973 
3974         list_for_each_entry_safe(ftrace_mod, n, &process_mods, list) {
3975 
3976                 func = ftrace_mod->func;
3977 
3978                 /* Grabs ftrace_lock, which is why we have this extra step */
3979                 match_records(new_hash, func, strlen(func), mod);
3980                 free_ftrace_mod(ftrace_mod);
3981         }
3982 
3983         if (enable && list_empty(head))
3984                 new_hash->flags &= ~FTRACE_HASH_FL_MOD;
3985 
3986         mutex_lock(&ftrace_lock);
3987 
3988         ret = ftrace_hash_move_and_update_ops(ops, orig_hash,
3989                                               new_hash, enable);
3990         mutex_unlock(&ftrace_lock);
3991 
3992  out:
3993         mutex_unlock(&ops->func_hash->regex_lock);
3994 
3995         free_ftrace_hash(new_hash);
3996 }
3997 
3998 static void process_cached_mods(const char *mod_name)
3999 {
4000         struct trace_array *tr;
4001         char *mod;
4002 
4003         mod = kstrdup(mod_name, GFP_KERNEL);
4004         if (!mod)
4005                 return;
4006 
4007         mutex_lock(&trace_types_lock);
4008         list_for_each_entry(tr, &ftrace_trace_arrays, list) {
4009                 if (!list_empty(&tr->mod_trace))
4010                         process_mod_list(&tr->mod_trace, tr->ops, mod, true);
4011                 if (!list_empty(&tr->mod_notrace))
4012                         process_mod_list(&tr->mod_notrace, tr->ops, mod, false);
4013         }
4014         mutex_unlock(&trace_types_lock);
4015 
4016         kfree(mod);
4017 }
4018 #endif
4019 
4020 /*
4021  * We register the module command as a template to show others how
4022  * to register the a command as well.
4023  */
4024 
4025 static int
4026 ftrace_mod_callback(struct trace_array *tr, struct ftrace_hash *hash,
4027                     char *func_orig, char *cmd, char *module, int enable)
4028 {
4029         char *func;
4030         int ret;
4031 
4032         /* match_records() modifies func, and we need the original */
4033         func = kstrdup(func_orig, GFP_KERNEL);
4034         if (!func)
4035                 return -ENOMEM;
4036 
4037         /*
4038          * cmd == 'mod' because we only registered this func
4039          * for the 'mod' ftrace_func_command.
4040          * But if you register one func with multiple commands,
4041          * you can tell which command was used by the cmd
4042          * parameter.
4043          */
4044         ret = match_records(hash, func, strlen(func), module);
4045         kfree(func);
4046 
4047         if (!ret)
4048                 return cache_mod(tr, func_orig, module, enable);
4049         if (ret < 0)
4050                 return ret;
4051         return 0;
4052 }
4053 
4054 static struct ftrace_func_command ftrace_mod_cmd = {
4055         .name                   = "mod",
4056         .func                   = ftrace_mod_callback,
4057 };
4058 
4059 static int __init ftrace_mod_cmd_init(void)
4060 {
4061         return register_ftrace_command(&ftrace_mod_cmd);
4062 }
4063 core_initcall(ftrace_mod_cmd_init);
4064 
4065 static void function_trace_probe_call(unsigned long ip, unsigned long parent_ip,
4066                                       struct ftrace_ops *op, struct pt_regs *pt_regs)
4067 {
4068         struct ftrace_probe_ops *probe_ops;
4069         struct ftrace_func_probe *probe;
4070 
4071         probe = container_of(op, struct ftrace_func_probe, ops);
4072         probe_ops = probe->probe_ops;
4073 
4074         /*
4075          * Disable preemption for these calls to prevent a RCU grace
4076          * period. This syncs the hash iteration and freeing of items
4077          * on the hash. rcu_read_lock is too dangerous here.
4078          */
4079         preempt_disable_notrace();
4080         probe_ops->func(ip, parent_ip, probe->tr, probe_ops, probe->data);
4081         preempt_enable_notrace();
4082 }
4083 
4084 struct ftrace_func_map {
4085         struct ftrace_func_entry        entry;
4086         void                            *data;
4087 };
4088 
4089 struct ftrace_func_mapper {
4090         struct ftrace_hash              hash;
4091 };
4092 
4093 /**
4094  * allocate_ftrace_func_mapper - allocate a new ftrace_func_mapper
4095  *
4096  * Returns a ftrace_func_mapper descriptor that can be used to map ips to data.
4097  */
4098 struct ftrace_func_mapper *allocate_ftrace_func_mapper(void)
4099 {
4100         struct ftrace_hash *hash;
4101 
4102         /*
4103          * The mapper is simply a ftrace_hash, but since the entries
4104          * in the hash are not ftrace_func_entry type, we define it
4105          * as a separate structure.
4106          */
4107         hash = alloc_ftrace_hash(FTRACE_HASH_DEFAULT_BITS);
4108         return (struct ftrace_func_mapper *)hash;
4109 }
4110 
4111 /**
4112  * ftrace_func_mapper_find_ip - Find some data mapped to an ip
4113  * @mapper: The mapper that has the ip maps
4114  * @ip: the instruction pointer to find the data for
4115  *
4116  * Returns the data mapped to @ip if found otherwise NULL. The return
4117  * is actually the address of the mapper data pointer. The address is
4118  * returned for use cases where the data is no bigger than a long, and
4119  * the user can use the data pointer as its data instead of having to
4120  * allocate more memory for the reference.
4121  */
4122 void **ftrace_func_mapper_find_ip(struct ftrace_func_mapper *mapper,
4123                                   unsigned long ip)
4124 {
4125         struct ftrace_func_entry *entry;
4126         struct ftrace_func_map *map;
4127 
4128         entry = ftrace_lookup_ip(&mapper->hash, ip);
4129         if (!entry)
4130                 return NULL;
4131 
4132         map = (struct ftrace_func_map *)entry;
4133         return &map->data;
4134 }
4135 
4136 /**
4137  * ftrace_func_mapper_add_ip - Map some data to an ip
4138  * @mapper: The mapper that has the ip maps
4139  * @ip: The instruction pointer address to map @data to
4140  * @data: The data to map to @ip
4141  *
4142  * Returns 0 on succes otherwise an error.
4143  */
4144 int ftrace_func_mapper_add_ip(struct ftrace_func_mapper *mapper,
4145                               unsigned long ip, void *data)
4146 {
4147         struct ftrace_func_entry *entry;
4148         struct ftrace_func_map *map;
4149 
4150         entry = ftrace_lookup_ip(&mapper->hash, ip);
4151         if (entry)
4152                 return -EBUSY;
4153 
4154         map = kmalloc(sizeof(*map), GFP_KERNEL);
4155         if (!map)
4156                 return -ENOMEM;
4157 
4158         map->entry.ip = ip;
4159         map->data = data;
4160 
4161         __add_hash_entry(&mapper->hash, &map->entry);
4162 
4163         return 0;
4164 }
4165 
4166 /**
4167  * ftrace_func_mapper_remove_ip - Remove an ip from the mapping
4168  * @mapper: The mapper that has the ip maps
4169  * @ip: The instruction pointer address to remove the data from
4170  *
4171  * Returns the data if it is found, otherwise NULL.
4172  * Note, if the data pointer is used as the data itself, (see 
4173  * ftrace_func_mapper_find_ip(), then the return value may be meaningless,
4174  * if the data pointer was set to zero.
4175  */
4176 void *ftrace_func_mapper_remove_ip(struct ftrace_func_mapper *mapper,
4177                                    unsigned long ip)
4178 {
4179         struct ftrace_func_entry *entry;
4180         struct ftrace_func_map *map;
4181         void *data;
4182 
4183         entry = ftrace_lookup_ip(&mapper->hash, ip);
4184         if (!entry)
4185                 return NULL;
4186 
4187         map = (struct ftrace_func_map *)entry;
4188         data = map->data;
4189 
4190         remove_hash_entry(&mapper->hash, entry);
4191         kfree(entry);
4192 
4193         return data;
4194 }
4195 
4196 /**
4197  * free_ftrace_func_mapper - free a mapping of ips and data
4198  * @mapper: The mapper that has the ip maps
4199  * @free_func: A function to be called on each data item.
4200  *
4201  * This is used to free the function mapper. The @free_func is optional
4202  * and can be used if the data needs to be freed as well.
4203  */
4204 void free_ftrace_func_mapper(struct ftrace_func_mapper *mapper,
4205                              ftrace_mapper_func free_func)
4206 {
4207         struct ftrace_func_entry *entry;
4208         struct ftrace_func_map *map;
4209         struct hlist_head *hhd;
4210         int size = 1 << mapper->hash.size_bits;
4211         int i;
4212 
4213         if (free_func && mapper->hash.count) {
4214                 for (i = 0; i < size; i++) {
4215                         hhd = &mapper->hash.buckets[i];
4216                         hlist_for_each_entry(entry, hhd, hlist) {
4217                                 map = (struct ftrace_func_map *)entry;
4218                                 free_func(map);
4219                         }
4220                 }
4221         }
4222         free_ftrace_hash(&mapper->hash);
4223 }
4224 
4225 static void release_probe(struct ftrace_func_probe *probe)
4226 {
4227         struct ftrace_probe_ops *probe_ops;
4228 
4229         mutex_lock(&ftrace_lock);
4230 
4231         WARN_ON(probe->ref <= 0);
4232 
4233         /* Subtract the ref that was used to protect this instance */
4234         probe->ref--;
4235 
4236         if (!probe->ref) {
4237                 probe_ops = probe->probe_ops;
4238                 /*
4239                  * Sending zero as ip tells probe_ops to free
4240                  * the probe->data itself
4241                  */
4242                 if (probe_ops->free)
4243                         probe_ops->free(probe_ops, probe->tr, 0, probe->data);
4244                 list_del(&probe->list);
4245                 kfree(probe);
4246         }
4247         mutex_unlock(&ftrace_lock);
4248 }
4249 
4250 static void acquire_probe_locked(struct ftrace_func_probe *probe)
4251 {
4252         /*
4253          * Add one ref to keep it from being freed when releasing the
4254          * ftrace_lock mutex.
4255          */
4256         probe->ref++;
4257 }
4258 
4259 int
4260 register_ftrace_function_probe(char *glob, struct trace_array *tr,
4261                                struct ftrace_probe_ops *probe_ops,
4262                                void *data)
4263 {
4264         struct ftrace_func_entry *entry;
4265         struct ftrace_func_probe *probe;
4266         struct ftrace_hash **orig_hash;
4267         struct ftrace_hash *old_hash;
4268         struct ftrace_hash *hash;
4269         int count = 0;
4270         int size;
4271         int ret;
4272         int i;
4273 
4274         if (WARN_ON(!tr))
4275                 return -EINVAL;
4276 
4277         /* We do not support '!' for function probes */
4278         if (WARN_ON(glob[0] == '!'))
4279                 return -EINVAL;
4280 
4281 
4282         mutex_lock(&ftrace_lock);
4283         /* Check if the probe_ops is already registered */
4284         list_for_each_entry(probe, &tr->func_probes, list) {
4285                 if (probe->probe_ops == probe_ops)
4286                         break;
4287         }
4288         if (&probe->list == &tr->func_probes) {
4289                 probe = kzalloc(sizeof(*probe), GFP_KERNEL);
4290                 if (!probe) {
4291                         mutex_unlock(&ftrace_lock);
4292                         return -ENOMEM;
4293                 }
4294                 probe->probe_ops = probe_ops;
4295                 probe->ops.func = function_trace_probe_call;
4296                 probe->tr = tr;
4297                 ftrace_ops_init(&probe->ops);
4298                 list_add(&probe->list, &tr->func_probes);
4299         }
4300 
4301         acquire_probe_locked(probe);
4302 
4303         mutex_unlock(&ftrace_lock);
4304 
4305         mutex_lock(&probe->ops.func_hash->regex_lock);
4306 
4307         orig_hash = &probe->ops.func_hash->filter_hash;
4308         old_hash = *orig_hash;
4309         hash = alloc_and_copy_ftrace_hash(FTRACE_HASH_DEFAULT_BITS, old_hash);
4310 
4311         ret = ftrace_match_records(hash, glob, strlen(glob));
4312 
4313         /* Nothing found? */
4314         if (!ret)
4315                 ret = -EINVAL;
4316 
4317         if (ret < 0)
4318                 goto out;
4319 
4320         size = 1 << hash->size_bits;
4321         for (i = 0; i < size; i++) {
4322                 hlist_for_each_entry(entry, &hash->buckets[i], hlist) {
4323                         if (ftrace_lookup_ip(old_hash, entry->ip))
4324                                 continue;
4325                         /*
4326                          * The caller might want to do something special
4327                          * for each function we find. We call the callback
4328                          * to give the caller an opportunity to do so.
4329                          */
4330                         if (probe_ops->init) {
4331                                 ret = probe_ops->init(probe_ops, tr,
4332                                                       entry->ip, data,
4333                                                       &probe->data);
4334                                 if (ret < 0) {
4335                                         if (probe_ops->free && count)
4336                                                 probe_ops->free(probe_ops, tr,
4337                                                                 0, probe->data);
4338                                         probe->data = NULL;
4339                                         goto out;
4340                                 }
4341                         }
4342                         count++;
4343                 }
4344         }
4345 
4346         mutex_lock(&ftrace_lock);
4347 
4348         if (!count) {
4349                 /* Nothing was added? */
4350                 ret = -EINVAL;
4351                 goto out_unlock;
4352         }
4353 
4354         ret = ftrace_hash_move_and_update_ops(&probe->ops, orig_hash,
4355                                               hash, 1);
4356         if (ret < 0)
4357                 goto err_unlock;
4358 
4359         /* One ref for each new function traced */
4360         probe->ref += count;
4361 
4362         if (!(probe->ops.flags & FTRACE_OPS_FL_ENABLED))
4363                 ret = ftrace_startup(&probe->ops, 0);
4364 
4365  out_unlock:
4366         mutex_unlock(&ftrace_lock);
4367 
4368         if (!ret)
4369                 ret = count;
4370  out:
4371         mutex_unlock(&probe->ops.func_hash->regex_lock);
4372         free_ftrace_hash(hash);
4373 
4374         release_probe(probe);
4375 
4376         return ret;
4377 
4378  err_unlock:
4379         if (!probe_ops->free || !count)
4380                 goto out_unlock;
4381 
4382         /* Failed to do the move, need to call the free functions */
4383         for (i = 0; i < size; i++) {
4384                 hlist_for_each_entry(entry, &hash->buckets[i], hlist) {
4385                         if (ftrace_lookup_ip(old_hash, entry->ip))
4386                                 continue;
4387                         probe_ops->free(probe_ops, tr, entry->ip, probe->data);
4388                 }
4389         }
4390         goto out_unlock;
4391 }
4392 
4393 int
4394 unregister_ftrace_function_probe_func(char *glob, struct trace_array *tr,
4395                                       struct ftrace_probe_ops *probe_ops)
4396 {
4397         struct ftrace_ops_hash old_hash_ops;
4398         struct ftrace_func_entry *entry;
4399         struct ftrace_func_probe *probe;
4400         struct ftrace_glob func_g;
4401         struct ftrace_hash **orig_hash;
4402         struct ftrace_hash *old_hash;
4403         struct ftrace_hash *hash = NULL;
4404         struct hlist_node *tmp;
4405         struct hlist_head hhd;
4406         char str[KSYM_SYMBOL_LEN];
4407         int count = 0;
4408         int i, ret = -ENODEV;
4409         int size;
4410 
4411         if (!glob || !strlen(glob) || !strcmp(glob, "*"))
4412                 func_g.search = NULL;
4413         else {
4414                 int not;
4415 
4416                 func_g.type = filter_parse_regex(glob, strlen(glob),
4417                                                  &func_g.search, &not);
4418                 func_g.len = strlen(func_g.search);
4419 
4420                 /* we do not support '!' for function probes */
4421                 if (WARN_ON(not))
4422                         return -EINVAL;
4423         }
4424 
4425         mutex_lock(&ftrace_lock);
4426         /* Check if the probe_ops is already registered */
4427         list_for_each_entry(probe, &tr->func_probes, list) {
4428                 if (probe->probe_ops == probe_ops)
4429                         break;
4430         }
4431         if (&probe->list == &tr->func_probes)
4432                 goto err_unlock_ftrace;
4433 
4434         ret = -EINVAL;
4435         if (!(probe->ops.flags & FTRACE_OPS_FL_INITIALIZED))
4436                 goto err_unlock_ftrace;
4437 
4438         acquire_probe_locked(probe);
4439 
4440         mutex_unlock(&ftrace_lock);
4441 
4442         mutex_lock(&probe->ops.func_hash->regex_lock);
4443 
4444         orig_hash = &probe->ops.func_hash->filter_hash;
4445         old_hash = *orig_hash;
4446 
4447         if (ftrace_hash_empty(old_hash))
4448                 goto out_unlock;
4449 
4450         old_hash_ops.filter_hash = old_hash;
4451         /* Probes only have filters */
4452         old_hash_ops.notrace_hash = NULL;
4453 
4454         ret = -ENOMEM;
4455         hash = alloc_and_copy_ftrace_hash(FTRACE_HASH_DEFAULT_BITS, old_hash);
4456         if (!hash)
4457                 goto out_unlock;
4458 
4459         INIT_HLIST_HEAD(&hhd);
4460 
4461         size = 1 << hash->size_bits;
4462         for (i = 0; i < size; i++) {
4463                 hlist_for_each_entry_safe(entry, tmp, &hash->buckets[i], hlist) {
4464 
4465                         if (func_g.search) {
4466                                 kallsyms_lookup(entry->ip, NULL, NULL,
4467                                                 NULL, str);
4468                                 if (!ftrace_match(str, &func_g))
4469                                         continue;
4470                         }
4471                         count++;
4472                         remove_hash_entry(hash, entry);
4473                         hlist_add_head(&entry->hlist, &hhd);
4474                 }
4475         }
4476 
4477         /* Nothing found? */
4478         if (!count) {
4479                 ret = -EINVAL;
4480                 goto out_unlock;
4481         }
4482 
4483         mutex_lock(&ftrace_lock);
4484 
4485         WARN_ON(probe->ref < count);
4486 
4487         probe->ref -= count;
4488 
4489         if (ftrace_hash_empty(hash))
4490                 ftrace_shutdown(&probe->ops, 0);
4491 
4492         ret = ftrace_hash_move_and_update_ops(&probe->ops, orig_hash,
4493                                               hash, 1);
4494 
4495         /* still need to update the function call sites */
4496         if (ftrace_enabled && !ftrace_hash_empty(hash))
4497                 ftrace_run_modify_code(&probe->ops, FTRACE_UPDATE_CALLS,
4498                                        &old_hash_ops);
4499         synchronize_sched();
4500 
4501         hlist_for_each_entry_safe(entry, tmp, &hhd, hlist) {
4502                 hlist_del(&entry->hlist);
4503                 if (probe_ops->free)
4504                         probe_ops->free(probe_ops, tr, entry->ip, probe->data);
4505                 kfree(entry);
4506         }
4507         mutex_unlock(&ftrace_lock);
4508 
4509  out_unlock:
4510         mutex_unlock(&probe->ops.func_hash->regex_lock);
4511         free_ftrace_hash(hash);
4512 
4513         release_probe(probe);
4514 
4515         return ret;
4516 
4517  err_unlock_ftrace:
4518         mutex_unlock(&ftrace_lock);
4519         return ret;
4520 }
4521 
4522 void clear_ftrace_function_probes(struct trace_array *tr)
4523 {
4524         struct ftrace_func_probe *probe, *n;
4525 
4526         list_for_each_entry_safe(probe, n, &tr->func_probes, list)
4527                 unregister_ftrace_function_probe_func(NULL, tr, probe->probe_ops);
4528 }
4529 
4530 static LIST_HEAD(ftrace_commands);
4531 static DEFINE_MUTEX(ftrace_cmd_mutex);
4532 
4533 /*
4534  * Currently we only register ftrace commands from __init, so mark this
4535  * __init too.
4536  */
4537 __init int register_ftrace_command(struct ftrace_func_command *cmd)
4538 {
4539         struct ftrace_func_command *p;
4540         int ret = 0;
4541 
4542         mutex_lock(&ftrace_cmd_mutex);
4543         list_for_each_entry(p, &ftrace_commands, list) {
4544                 if (strcmp(cmd->name, p->name) == 0) {
4545                         ret = -EBUSY;
4546                         goto out_unlock;
4547                 }
4548         }
4549         list_add(&cmd->list, &ftrace_commands);
4550  out_unlock:
4551         mutex_unlock(&ftrace_cmd_mutex);
4552 
4553         return ret;
4554 }
4555 
4556 /*
4557  * Currently we only unregister ftrace commands from __init, so mark
4558  * this __init too.
4559  */
4560 __init int unregister_ftrace_command(struct ftrace_func_command *cmd)
4561 {
4562         struct ftrace_func_command *p, *n;
4563         int ret = -ENODEV;
4564 
4565         mutex_lock(&ftrace_cmd_mutex);
4566         list_for_each_entry_safe(p, n, &ftrace_commands, list) {
4567                 if (strcmp(cmd->name, p->name) == 0) {
4568                         ret = 0;
4569                         list_del_init(&p->list);
4570                         goto out_unlock;
4571                 }
4572         }
4573  out_unlock:
4574         mutex_unlock(&ftrace_cmd_mutex);
4575 
4576         return ret;
4577 }
4578 
4579 static int ftrace_process_regex(struct ftrace_iterator *iter,
4580                                 char *buff, int len, int enable)
4581 {
4582         struct ftrace_hash *hash = iter->hash;
4583         struct trace_array *tr = iter->ops->private;
4584         char *func, *command, *next = buff;
4585         struct ftrace_func_command *p;
4586         int ret = -EINVAL;
4587 
4588         func = strsep(&next, ":");
4589 
4590         if (!next) {
4591                 ret = ftrace_match_records(hash, func, len);
4592                 if (!ret)
4593                         ret = -EINVAL;
4594                 if (ret < 0)
4595                         return ret;
4596                 return 0;
4597         }
4598 
4599         /* command found */
4600 
4601         command = strsep(&next, ":");
4602 
4603         mutex_lock(&ftrace_cmd_mutex);
4604         list_for_each_entry(p, &ftrace_commands, list) {
4605                 if (strcmp(p->name, command) == 0) {
4606                         ret = p->func(tr, hash, func, command, next, enable);
4607                         goto out_unlock;
4608                 }
4609         }
4610  out_unlock:
4611         mutex_unlock(&ftrace_cmd_mutex);
4612 
4613         return ret;
4614 }
4615 
4616 static ssize_t
4617 ftrace_regex_write(struct file *file, const char __user *ubuf,
4618                    size_t cnt, loff_t *ppos, int enable)
4619 {
4620         struct ftrace_iterator *iter;
4621         struct trace_parser *parser;
4622         ssize_t ret, read;
4623 
4624         if (!cnt)
4625                 return 0;
4626 
4627         if (file->f_mode & FMODE_READ) {
4628                 struct seq_file *m = file->private_data;
4629                 iter = m->private;
4630         } else
4631                 iter = file->private_data;
4632 
4633         if (unlikely(ftrace_disabled))
4634                 return -ENODEV;
4635 
4636         /* iter->hash is a local copy, so we don't need regex_lock */
4637 
4638         parser = &iter->parser;
4639         read = trace_get_user(parser, ubuf, cnt, ppos);
4640 
4641         if (read >= 0 && trace_parser_loaded(parser) &&
4642             !trace_parser_cont(parser)) {
4643                 ret = ftrace_process_regex(iter, parser->buffer,
4644                                            parser->idx, enable);
4645                 trace_parser_clear(parser);
4646                 if (ret < 0)
4647                         goto out;
4648         }
4649 
4650         ret = read;
4651  out:
4652         return ret;
4653 }
4654 
4655 ssize_t
4656 ftrace_filter_write(struct file *file, const char __user *ubuf,
4657                     size_t cnt, loff_t *ppos)
4658 {
4659         return ftrace_regex_write(file, ubuf, cnt, ppos, 1);
4660 }
4661 
4662 ssize_t
4663 ftrace_notrace_write(struct file *file, const char __user *ubuf,
4664                      size_t cnt, loff_t *ppos)
4665 {
4666         return ftrace_regex_write(file, ubuf, cnt, ppos, 0);
4667 }
4668 
4669 static int
4670 ftrace_match_addr(struct ftrace_hash *hash, unsigned long ip, int remove)
4671 {
4672         struct ftrace_func_entry *entry;
4673 
4674         if (!ftrace_location(ip))
4675                 return -EINVAL;
4676 
4677         if (remove) {
4678                 entry = ftrace_lookup_ip(hash, ip);
4679                 if (!entry)
4680                         return -ENOENT;
4681                 free_hash_entry(hash, entry);
4682                 return 0;
4683         }
4684 
4685         return add_hash_entry(hash, ip);
4686 }
4687 
4688 static int
4689 ftrace_set_hash(struct ftrace_ops *ops, unsigned char *buf, int len,
4690                 unsigned long ip, int remove, int reset, int enable)
4691 {
4692         struct ftrace_hash **orig_hash;
4693         struct ftrace_hash *hash;
4694         int ret;
4695 
4696         if (unlikely(ftrace_disabled))
4697                 return -ENODEV;
4698 
4699         mutex_lock(&ops->func_hash->regex_lock);
4700 
4701         if (enable)
4702                 orig_hash = &ops->func_hash->filter_hash;
4703         else
4704                 orig_hash = &ops->func_hash->notrace_hash;
4705 
4706         if (reset)
4707                 hash = alloc_ftrace_hash(FTRACE_HASH_DEFAULT_BITS);
4708         else
4709                 hash = alloc_and_copy_ftrace_hash(FTRACE_HASH_DEFAULT_BITS, *orig_hash);
4710 
4711         if (!hash) {
4712                 ret = -ENOMEM;
4713                 goto out_regex_unlock;
4714         }
4715 
4716         if (buf && !ftrace_match_records(hash, buf, len)) {
4717                 ret = -EINVAL;
4718                 goto out_regex_unlock;
4719         }
4720         if (ip) {
4721                 ret = ftrace_match_addr(hash, ip, remove);
4722                 if (ret < 0)
4723                         goto out_regex_unlock;
4724         }
4725 
4726         mutex_lock(&ftrace_lock);
4727         ret = ftrace_hash_move_and_update_ops(ops, orig_hash, hash, enable);
4728         mutex_unlock(&ftrace_lock);
4729 
4730  out_regex_unlock:
4731         mutex_unlock(&ops->func_hash->regex_lock);
4732 
4733         free_ftrace_hash(hash);
4734         return ret;
4735 }
4736 
4737 static int
4738 ftrace_set_addr(struct ftrace_ops *ops, unsigned long ip, int remove,
4739                 int reset, int enable)
4740 {
4741         return ftrace_set_hash(ops, 0, 0, ip, remove, reset, enable);
4742 }
4743 
4744 /**
4745  * ftrace_set_filter_ip - set a function to filter on in ftrace by address
4746  * @ops - the ops to set the filter with
4747  * @ip - the address to add to or remove from the filter.
4748  * @remove - non zero to remove the ip from the filter
4749  * @reset - non zero to reset all filters before applying this filter.
4750  *
4751  * Filters denote which functions should be enabled when tracing is enabled
4752  * If @ip is NULL, it failes to update filter.
4753  */
4754 int ftrace_set_filter_ip(struct ftrace_ops *ops, unsigned long ip,
4755                          int remove, int reset)
4756 {
4757         ftrace_ops_init(ops);
4758         return ftrace_set_addr(ops, ip, remove, reset, 1);
4759 }
4760 EXPORT_SYMBOL_GPL(ftrace_set_filter_ip);
4761 
4762 /**
4763  * ftrace_ops_set_global_filter - setup ops to use global filters
4764  * @ops - the ops which will use the global filters
4765  *
4766  * ftrace users who need global function trace filtering should call this.
4767  * It can set the global filter only if ops were not initialized before.
4768  */
4769 void ftrace_ops_set_global_filter(struct ftrace_ops *ops)
4770 {
4771         if (ops->flags & FTRACE_OPS_FL_INITIALIZED)
4772                 return;
4773 
4774         ftrace_ops_init(ops);
4775         ops->func_hash = &global_ops.local_hash;
4776 }
4777 EXPORT_SYMBOL_GPL(ftrace_ops_set_global_filter);
4778 
4779 static int
4780 ftrace_set_regex(struct ftrace_ops *ops, unsigned char *buf, int len,
4781                  int reset, int enable)
4782 {
4783         return ftrace_set_hash(ops, buf, len, 0, 0, reset, enable);
4784 }
4785 
4786 /**
4787  * ftrace_set_filter - set a function to filter on in ftrace
4788  * @ops - the ops to set the filter with
4789  * @buf - the string that holds the function filter text.
4790  * @len - the length of the string.
4791  * @reset - non zero to reset all filters before applying this filter.
4792  *
4793  * Filters denote which functions should be enabled when tracing is enabled.
4794  * If @buf is NULL and reset is set, all functions will be enabled for tracing.
4795  */
4796 int ftrace_set_filter(struct ftrace_ops *ops, unsigned char *buf,
4797                        int len, int reset)
4798 {
4799         ftrace_ops_init(ops);
4800         return ftrace_set_regex(ops, buf, len, reset, 1);
4801 }
4802 EXPORT_SYMBOL_GPL(ftrace_set_filter);
4803 
4804 /**
4805  * ftrace_set_notrace - set a function to not trace in ftrace
4806  * @ops - the ops to set the notrace filter with
4807  * @buf - the string that holds the function notrace text.
4808  * @len - the length of the string.
4809  * @reset - non zero to reset all filters before applying this filter.
4810  *
4811  * Notrace Filters denote which functions should not be enabled when tracing
4812  * is enabled. If @buf is NULL and reset is set, all functions will be enabled
4813  * for tracing.
4814  */
4815 int ftrace_set_notrace(struct ftrace_ops *ops, unsigned char *buf,
4816                         int len, int reset)
4817 {
4818         ftrace_ops_init(ops);
4819         return ftrace_set_regex(ops, buf, len, reset, 0);
4820 }
4821 EXPORT_SYMBOL_GPL(ftrace_set_notrace);
4822 /**
4823  * ftrace_set_global_filter - set a function to filter on with global tracers
4824  * @buf - the string that holds the function filter text.
4825  * @len - the length of the string.
4826  * @reset - non zero to reset all filters before applying this filter.
4827  *
4828  * Filters denote which functions should be enabled when tracing is enabled.
4829  * If @buf is NULL and reset is set, all functions will be enabled for tracing.
4830  */
4831 void ftrace_set_global_filter(unsigned char *buf, int len, int reset)
4832 {
4833         ftrace_set_regex(&global_ops, buf, len, reset, 1);
4834 }
4835 EXPORT_SYMBOL_GPL(ftrace_set_global_filter);
4836 
4837 /**
4838  * ftrace_set_global_notrace - set a function to not trace with global tracers
4839  * @buf - the string that holds the function notrace text.
4840  * @len - the length of the string.
4841  * @reset - non zero to reset all filters before applying this filter.
4842  *
4843  * Notrace Filters denote which functions should not be enabled when tracing
4844  * is enabled. If @buf is NULL and reset is set, all functions will be enabled
4845  * for tracing.
4846  */
4847 void ftrace_set_global_notrace(unsigned char *buf, int len, int reset)
4848 {
4849         ftrace_set_regex(&global_ops, buf, len, reset, 0);
4850 }
4851 EXPORT_SYMBOL_GPL(ftrace_set_global_notrace);
4852 
4853 /*
4854  * command line interface to allow users to set filters on boot up.
4855  */
4856 #define FTRACE_FILTER_SIZE              COMMAND_LINE_SIZE
4857 static char ftrace_notrace_buf[FTRACE_FILTER_SIZE] __initdata;
4858 static char ftrace_filter_buf[FTRACE_FILTER_SIZE] __initdata;
4859 
4860 /* Used by function selftest to not test if filter is set */
4861 bool ftrace_filter_param __initdata;
4862 
4863 static int __init set_ftrace_notrace(char *str)
4864 {
4865         ftrace_filter_param = true;
4866         strlcpy(ftrace_notrace_buf, str, FTRACE_FILTER_SIZE);
4867         return 1;
4868 }
4869 __setup("ftrace_notrace=", set_ftrace_notrace);
4870 
4871 static int __init set_ftrace_filter(char *str)
4872 {
4873         ftrace_filter_param = true;
4874         strlcpy(ftrace_filter_buf, str, FTRACE_FILTER_SIZE);
4875         return 1;
4876 }
4877 __setup("ftrace_filter=", set_ftrace_filter);
4878 
4879 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
4880 static char ftrace_graph_buf[FTRACE_FILTER_SIZE] __initdata;
4881 static char ftrace_graph_notrace_buf[FTRACE_FILTER_SIZE] __initdata;
4882 static int ftrace_graph_set_hash(struct ftrace_hash *hash, char *buffer);
4883 
4884 static int __init set_graph_function(char *str)
4885 {
4886         strlcpy(ftrace_graph_buf, str, FTRACE_FILTER_SIZE);
4887         return 1;
4888 }
4889 __setup("ftrace_graph_filter=", set_graph_function);
4890 
4891 static int __init set_graph_notrace_function(char *str)
4892 {
4893         strlcpy(ftrace_graph_notrace_buf, str, FTRACE_FILTER_SIZE);
4894         return 1;
4895 }
4896 __setup("ftrace_graph_notrace=", set_graph_notrace_function);
4897 
4898 static int __init set_graph_max_depth_function(char *str)
4899 {
4900         if (!str)
4901                 return 0;
4902         fgraph_max_depth = simple_strtoul(str, NULL, 0);
4903         return 1;
4904 }
4905 __setup("ftrace_graph_max_depth=", set_graph_max_depth_function);
4906 
4907 static void __init set_ftrace_early_graph(char *buf, int enable)
4908 {
4909         int ret;
4910         char *func;
4911         struct ftrace_hash *hash;
4912 
4913         hash = alloc_ftrace_hash(FTRACE_HASH_DEFAULT_BITS);
4914         if (WARN_ON(!hash))
4915                 return;
4916 
4917         while (buf) {
4918                 func = strsep(&buf, ",");
4919                 /* we allow only one expression at a time */
4920                 ret = ftrace_graph_set_hash(hash, func);
4921                 if (ret)
4922                         printk(KERN_DEBUG "ftrace: function %s not "
4923                                           "traceable\n", func);
4924         }
4925 
4926         if (enable)
4927                 ftrace_graph_hash = hash;
4928         else
4929                 ftrace_graph_notrace_hash = hash;
4930 }
4931 #endif /* CONFIG_FUNCTION_GRAPH_TRACER */
4932 
4933 void __init
4934 ftrace_set_early_filter(struct ftrace_ops *ops, char *buf, int enable)
4935 {
4936         char *func;
4937 
4938         ftrace_ops_init(ops);
4939 
4940         while (buf) {
4941                 func = strsep(&buf, ",");
4942                 ftrace_set_regex(ops, func, strlen(func), 0, enable);
4943         }
4944 }
4945 
4946 static void __init set_ftrace_early_filters(void)
4947 {
4948         if (ftrace_filter_buf[0])
4949                 ftrace_set_early_filter(&global_ops, ftrace_filter_buf, 1);
4950         if (ftrace_notrace_buf[0])
4951                 ftrace_set_early_filter(&global_ops, ftrace_notrace_buf, 0);
4952 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
4953         if (ftrace_graph_buf[0])
4954                 set_ftrace_early_graph(ftrace_graph_buf, 1);
4955         if (ftrace_graph_notrace_buf[0])
4956                 set_ftrace_early_graph(ftrace_graph_notrace_buf, 0);
4957 #endif /* CONFIG_FUNCTION_GRAPH_TRACER */
4958 }
4959 
4960 int ftrace_regex_release(struct inode *inode, struct file *file)
4961 {
4962         struct seq_file *m = (struct seq_file *)file->private_data;
4963         struct ftrace_iterator *iter;
4964         struct ftrace_hash **orig_hash;
4965         struct trace_parser *parser;
4966         int filter_hash;
4967         int ret;
4968 
4969         if (file->f_mode & FMODE_READ) {
4970                 iter = m->private;
4971                 seq_release(inode, file);
4972         } else
4973                 iter = file->private_data;
4974 
4975         parser = &iter->parser;
4976         if (trace_parser_loaded(parser)) {
4977                 ftrace_match_records(iter->hash, parser->buffer, parser->idx);
4978         }
4979 
4980         trace_parser_put(parser);
4981 
4982         mutex_lock(&iter->ops->func_hash->regex_lock);
4983 
4984         if (file->f_mode & FMODE_WRITE) {
4985                 filter_hash = !!(iter->flags & FTRACE_ITER_FILTER);
4986 
4987                 if (filter_hash) {
4988                         orig_hash = &iter->ops->func_hash->filter_hash;
4989                         if (iter->tr && !list_empty(&iter->tr->mod_trace))
4990                                 iter->hash->flags |= FTRACE_HASH_FL_MOD;
4991                 } else
4992                         orig_hash = &iter->ops->func_hash->notrace_hash;
4993 
4994                 mutex_lock(&ftrace_lock);
4995                 ret = ftrace_hash_move_and_update_ops(iter->ops, orig_hash,
4996                                                       iter->hash, filter_hash);
4997                 mutex_unlock(&ftrace_lock);
4998         } else {
4999                 /* For read only, the hash is the ops hash */
5000                 iter->hash = NULL;
5001         }
5002 
5003         mutex_unlock(&iter->ops->func_hash->regex_lock);
5004         free_ftrace_hash(iter->hash);
5005         kfree(iter);
5006 
5007         return 0;
5008 }
5009 
5010 static const struct file_operations ftrace_avail_fops = {
5011         .open = ftrace_avail_open,
5012         .read = seq_read,
5013         .llseek = seq_lseek,
5014         .release = seq_release_private,
5015 };
5016 
5017 static const struct file_operations ftrace_enabled_fops = {
5018         .open = ftrace_enabled_open,
5019         .read = seq_read,
5020         .llseek = seq_lseek,
5021         .release = seq_release_private,
5022 };
5023 
5024 static const struct file_operations ftrace_filter_fops = {
5025         .open = ftrace_filter_open,
5026         .read = seq_read,
5027         .write = ftrace_filter_write,
5028         .llseek = tracing_lseek,
5029         .release = ftrace_regex_release,
5030 };
5031 
5032 static const struct file_operations ftrace_notrace_fops = {
5033         .open = ftrace_notrace_open,
5034         .read = seq_read,
5035         .write = ftrace_notrace_write,
5036         .llseek = tracing_lseek,
5037         .release = ftrace_regex_release,
5038 };
5039 
5040 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
5041 
5042 static DEFINE_MUTEX(graph_lock);
5043 
5044 struct ftrace_hash *ftrace_graph_hash = EMPTY_HASH;
5045 struct ftrace_hash *ftrace_graph_notrace_hash = EMPTY_HASH;
5046 
5047 enum graph_filter_type {
5048         GRAPH_FILTER_NOTRACE    = 0,
5049         GRAPH_FILTER_FUNCTION,
5050 };
5051 
5052 #define FTRACE_GRAPH_EMPTY      ((void *)1)
5053 
5054 struct ftrace_graph_data {
5055         struct ftrace_hash              *hash;
5056         struct ftrace_func_entry        *entry;
5057         int                             idx;   /* for hash table iteration */
5058         enum graph_filter_type          type;
5059         struct ftrace_hash              *new_hash;
5060         const struct seq_operations     *seq_ops;
5061         struct trace_parser             parser;
5062 };
5063 
5064 static void *
5065 __g_next(struct seq_file *m, loff_t *pos)
5066 {
5067         struct ftrace_graph_data *fgd = m->private;
5068         struct ftrace_func_entry *entry = fgd->entry;
5069         struct hlist_head *head;
5070         int i, idx = fgd->idx;
5071 
5072         if (*pos >= fgd->hash->count)
5073                 return NULL;
5074 
5075         if (entry) {
5076                 hlist_for_each_entry_continue(entry, hlist) {
5077                         fgd->entry = entry;
5078                         return entry;
5079                 }
5080 
5081                 idx++;
5082         }
5083 
5084         for (i = idx; i < 1 << fgd->hash->size_bits; i++) {
5085                 head = &fgd->hash->buckets[i];
5086                 hlist_for_each_entry(entry, head, hlist) {
5087                         fgd->entry = entry;
5088                         fgd->idx = i;
5089                         return entry;
5090                 }
5091         }
5092         return NULL;
5093 }
5094 
5095 static void *
5096 g_next(struct seq_file *m, void *v, loff_t *pos)
5097 {
5098         (*pos)++;
5099         return __g_next(m, pos);
5100 }
5101 
5102 static void *g_start(struct seq_file *m, loff_t *pos)
5103 {
5104         struct ftrace_graph_data *fgd = m->private;
5105 
5106         mutex_lock(&graph_lock);
5107 
5108         if (fgd->type == GRAPH_FILTER_FUNCTION)
5109                 fgd->hash = rcu_dereference_protected(ftrace_graph_hash,
5110                                         lockdep_is_held(&graph_lock));
5111         else
5112                 fgd->hash = rcu_dereference_protected(ftrace_graph_notrace_hash,
5113                                         lockdep_is_held(&graph_lock));
5114 
5115         /* Nothing, tell g_show to print all functions are enabled */
5116         if (ftrace_hash_empty(fgd->hash) && !*pos)
5117                 return FTRACE_GRAPH_EMPTY;
5118 
5119         fgd->idx = 0;
5120         fgd->entry = NULL;
5121         return __g_next(m, pos);
5122 }
5123 
5124 static void g_stop(struct seq_file *m, void *p)
5125 {
5126         mutex_unlock(&graph_lock);
5127 }
5128 
5129 static int g_show(struct seq_file *m, void *v)
5130 {
5131         struct ftrace_func_entry *entry = v;
5132 
5133         if (!entry)
5134                 return 0;
5135 
5136         if (entry == FTRACE_GRAPH_EMPTY) {
5137                 struct ftrace_graph_data *fgd = m->private;
5138 
5139                 if (fgd->type == GRAPH_FILTER_FUNCTION)
5140                         seq_puts(m, "#### all functions enabled ####\n");
5141                 else
5142                         seq_puts(m, "#### no functions disabled ####\n");
5143                 return 0;
5144         }
5145 
5146         seq_printf(m, "%ps\n", (void *)entry->ip);
5147 
5148         return 0;
5149 }
5150 
5151 static const struct seq_operations ftrace_graph_seq_ops = {
5152         .start = g_start,
5153         .next = g_next,
5154         .stop = g_stop,
5155         .show = g_show,
5156 };
5157 
5158 static int
5159 __ftrace_graph_open(struct inode *inode, struct file *file,
5160                     struct ftrace_graph_data *fgd)
5161 {
5162         int ret = 0;
5163         struct ftrace_hash *new_hash = NULL;
5164 
5165         if (file->f_mode & FMODE_WRITE) {
5166                 const int size_bits = FTRACE_HASH_DEFAULT_BITS;
5167 
5168                 if (trace_parser_get_init(&fgd->parser, FTRACE_BUFF_MAX))
5169                         return -ENOMEM;
5170 
5171                 if (file->f_flags & O_TRUNC)
5172                         new_hash = alloc_ftrace_hash(size_bits);
5173                 else
5174                         new_hash = alloc_and_copy_ftrace_hash(size_bits,
5175                                                               fgd->hash);
5176                 if (!new_hash) {
5177                         ret = -ENOMEM;
5178                         goto out;
5179                 }
5180         }
5181 
5182         if (file->f_mode & FMODE_READ) {
5183                 ret = seq_open(file, &ftrace_graph_seq_ops);
5184                 if (!ret) {
5185                         struct seq_file *m = file->private_data;
5186                         m->private = fgd;
5187                 } else {
5188                         /* Failed */
5189                         free_ftrace_hash(new_hash);
5190                         new_hash = NULL;
5191                 }
5192         } else
5193                 file->private_data = fgd;
5194 
5195 out:
5196         if (ret < 0 && file->f_mode & FMODE_WRITE)
5197                 trace_parser_put(&fgd->parser);
5198 
5199         fgd->new_hash = new_hash;
5200 
5201         /*
5202          * All uses of fgd->hash must be taken with the graph_lock
5203          * held. The graph_lock is going to be released, so force
5204          * fgd->hash to be reinitialized when it is taken again.
5205          */
5206         fgd->hash = NULL;
5207 
5208         return ret;
5209 }
5210 
5211 static int
5212 ftrace_graph_open(struct inode *inode, struct file *file)
5213 {
5214         struct ftrace_graph_data *fgd;
5215         int ret;
5216 
5217         if (unlikely(ftrace_disabled))
5218                 return -ENODEV;
5219 
5220         fgd = kmalloc(sizeof(*fgd), GFP_KERNEL);
5221         if (fgd == NULL)
5222                 return -ENOMEM;
5223 
5224         mutex_lock(&graph_lock);
5225 
5226         fgd->hash = rcu_dereference_protected(ftrace_graph_hash,
5227                                         lockdep_is_held(&graph_lock));
5228         fgd->type = GRAPH_FILTER_FUNCTION;
5229         fgd->seq_ops = &ftrace_graph_seq_ops;
5230 
5231         ret = __ftrace_graph_open(inode, file, fgd);
5232         if (ret < 0)
5233                 kfree(fgd);
5234 
5235         mutex_unlock(&graph_lock);
5236         return ret;
5237 }
5238 
5239 static int
5240 ftrace_graph_notrace_open(struct inode *inode, struct file *file)
5241 {
5242         struct ftrace_graph_data *fgd;
5243         int ret;
5244 
5245         if (unlikely(ftrace_disabled))
5246                 return -ENODEV;
5247 
5248         fgd = kmalloc(sizeof(*fgd), GFP_KERNEL);
5249         if (fgd == NULL)
5250                 return -ENOMEM;
5251 
5252         mutex_lock(&graph_lock);
5253 
5254         fgd->hash = rcu_dereference_protected(ftrace_graph_notrace_hash,
5255                                         lockdep_is_held(&graph_lock));
5256         fgd->type = GRAPH_FILTER_NOTRACE;
5257         fgd->seq_ops = &ftrace_graph_seq_ops;
5258 
5259         ret = __ftrace_graph_open(inode, file, fgd);
5260         if (ret < 0)
5261                 kfree(fgd);
5262 
5263         mutex_unlock(&graph_lock);
5264         return ret;
5265 }
5266 
5267 static int
5268 ftrace_graph_release(struct inode *inode, struct file *file)
5269 {
5270         struct ftrace_graph_data *fgd;
5271         struct ftrace_hash *old_hash, *new_hash;
5272         struct trace_parser *parser;
5273         int ret = 0;
5274 
5275         if (file->f_mode & FMODE_READ) {
5276                 struct seq_file *m = file->private_data;
5277 
5278                 fgd = m->private;
5279                 seq_release(inode, file);
5280         } else {
5281                 fgd = file->private_data;
5282         }
5283 
5284 
5285         if (file->f_mode & FMODE_WRITE) {
5286 
5287                 parser = &fgd->parser;
5288 
5289                 if (trace_parser_loaded((parser))) {
5290                         ret = ftrace_graph_set_hash(fgd->new_hash,
5291                                                     parser->buffer);
5292                 }
5293 
5294                 trace_parser_put(parser);
5295 
5296                 new_hash = __ftrace_hash_move(fgd->new_hash);
5297                 if (!new_hash) {
5298                         ret = -ENOMEM;
5299                         goto out;
5300                 }
5301 
5302                 mutex_lock(&graph_lock);
5303 
5304                 if (fgd->type == GRAPH_FILTER_FUNCTION) {
5305                         old_hash = rcu_dereference_protected(ftrace_graph_hash,
5306                                         lockdep_is_held(&graph_lock));
5307                         rcu_assign_pointer(ftrace_graph_hash, new_hash);
5308                 } else {
5309                         old_hash = rcu_dereference_protected(ftrace_graph_notrace_hash,
5310                                         lockdep_is_held(&graph_lock));
5311                         rcu_assign_pointer(ftrace_graph_notrace_hash, new_hash);
5312                 }
5313 
5314                 mutex_unlock(&graph_lock);
5315 
5316                 /* Wait till all users are no longer using the old hash */
5317                 synchronize_sched();
5318 
5319                 free_ftrace_hash(old_hash);
5320         }
5321 
5322  out:
5323         free_ftrace_hash(fgd->new_hash);
5324         kfree(fgd);
5325 
5326         return ret;
5327 }
5328 
5329 static int
5330 ftrace_graph_set_hash(struct ftrace_hash *hash, char *buffer)
5331 {
5332         struct ftrace_glob func_g;
5333         struct dyn_ftrace *rec;
5334         struct ftrace_page *pg;
5335         struct ftrace_func_entry *entry;
5336         int fail = 1;
5337         int not;
5338 
5339         /* decode regex */
5340         func_g.type = filter_parse_regex(buffer, strlen(buffer),
5341                                          &func_g.search, &not);
5342 
5343         func_g.len = strlen(func_g.search);
5344 
5345         mutex_lock(&ftrace_lock);
5346 
5347         if (unlikely(ftrace_disabled)) {
5348                 mutex_unlock(&ftrace_lock);
5349                 return -ENODEV;
5350         }
5351 
5352         do_for_each_ftrace_rec(pg, rec) {
5353 
5354                 if (rec->flags & FTRACE_FL_DISABLED)
5355                         continue;
5356 
5357                 if (ftrace_match_record(rec, &func_g, NULL, 0)) {
5358                         entry = ftrace_lookup_ip(hash, rec->ip);
5359 
5360                         if (!not) {
5361                                 fail = 0;
5362 
5363                                 if (entry)
5364                                         continue;
5365                                 if (add_hash_entry(hash, rec->ip) < 0)
5366                                         goto out;
5367                         } else {
5368                                 if (entry) {
5369                                         free_hash_entry(hash, entry);
5370                                         fail = 0;
5371                                 }
5372                         }
5373                 }
5374         } while_for_each_ftrace_rec();
5375 out:
5376         mutex_unlock(&ftrace_lock);
5377 
5378         if (fail)
5379                 return -EINVAL;
5380 
5381         return 0;
5382 }
5383 
5384 static ssize_t
5385 ftrace_graph_write(struct file *file, const char __user *ubuf,
5386                    size_t cnt, loff_t *ppos)
5387 {
5388         ssize_t read, ret = 0;
5389         struct ftrace_graph_data *fgd = file->private_data;
5390         struct trace_parser *parser;
5391 
5392         if (!cnt)
5393                 return 0;
5394 
5395         /* Read mode uses seq functions */
5396         if (file->f_mode & FMODE_READ) {
5397                 struct seq_file *m = file->private_data;
5398                 fgd = m->private;
5399         }
5400 
5401         parser = &fgd->parser;
5402 
5403         read = trace_get_user(parser, ubuf, cnt, ppos);
5404 
5405         if (read >= 0 && trace_parser_loaded(parser) &&
5406             !trace_parser_cont(parser)) {
5407 
5408                 ret = ftrace_graph_set_hash(fgd->new_hash,
5409                                             parser->buffer);
5410                 trace_parser_clear(parser);
5411         }
5412 
5413         if (!ret)
5414                 ret = read;
5415 
5416         return ret;
5417 }
5418 
5419 static const struct file_operations ftrace_graph_fops = {
5420         .open           = ftrace_graph_open,
5421         .read           = seq_read,
5422         .write          = ftrace_graph_write,
5423         .llseek         = tracing_lseek,
5424         .release        = ftrace_graph_release,
5425 };
5426 
5427 static const struct file_operations ftrace_graph_notrace_fops = {
5428         .open           = ftrace_graph_notrace_open,
5429         .read           = seq_read,
5430         .write          = ftrace_graph_write,
5431         .llseek         = tracing_lseek,
5432         .release        = ftrace_graph_release,
5433 };
5434 #endif /* CONFIG_FUNCTION_GRAPH_TRACER */
5435 
5436 void ftrace_create_filter_files(struct ftrace_ops *ops,
5437                                 struct dentry *parent)
5438 {
5439 
5440         trace_create_file("set_ftrace_filter", 0644, parent,
5441                           ops, &ftrace_filter_fops);
5442 
5443         trace_create_file("set_ftrace_notrace", 0644, parent,
5444                           ops, &ftrace_notrace_fops);
5445 }
5446 
5447 /*
5448  * The name "destroy_filter_files" is really a misnomer. Although
5449  * in the future, it may actualy delete the files, but this is
5450  * really intended to make sure the ops passed in are disabled
5451  * and that when this function returns, the caller is free to
5452  * free the ops.
5453  *
5454  * The "destroy" name is only to match the "create" name that this
5455  * should be paired with.
5456  */
5457 void ftrace_destroy_filter_files(struct ftrace_ops *ops)
5458 {
5459         mutex_lock(&ftrace_lock);
5460         if (ops->flags & FTRACE_OPS_FL_ENABLED)
5461                 ftrace_shutdown(ops, 0);
5462         ops->flags |= FTRACE_OPS_FL_DELETED;
5463         mutex_unlock(&ftrace_lock);
5464 }
5465 
5466 static __init int ftrace_init_dyn_tracefs(struct dentry *d_tracer)
5467 {
5468 
5469         trace_create_file("available_filter_functions", 0444,
5470                         d_tracer, NULL, &ftrace_avail_fops);
5471 
5472         trace_create_file("enabled_functions", 0444,
5473                         d_tracer, NULL, &ftrace_enabled_fops);
5474 
5475         ftrace_create_filter_files(&global_ops, d_tracer);
5476 
5477 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
5478         trace_create_file("set_graph_function", 0644, d_tracer,
5479                                     NULL,
5480                                     &ftrace_graph_fops);
5481         trace_create_file("set_graph_notrace", 0644, d_tracer,
5482                                     NULL,
5483                                     &ftrace_graph_notrace_fops);
5484 #endif /* CONFIG_FUNCTION_GRAPH_TRACER */
5485 
5486         return 0;
5487 }
5488 
5489 static int ftrace_cmp_ips(const void *a, const void *b)
5490 {
5491         const unsigned long *ipa = a;
5492         const unsigned long *ipb = b;
5493 
5494         if (*ipa > *ipb)
5495                 return 1;
5496         if (*ipa < *ipb)
5497                 return -1;
5498         return 0;
5499 }
5500 
5501 static int ftrace_process_locs(struct module *mod,
5502                                unsigned long *start,
5503                                unsigned long *end)
5504 {
5505         struct ftrace_page *start_pg;
5506         struct ftrace_page *pg;
5507         struct dyn_ftrace *rec;
5508         unsigned long count;
5509         unsigned long *p;
5510         unsigned long addr;
5511         unsigned long flags = 0; /* Shut up gcc */
5512         int ret = -ENOMEM;
5513 
5514         count = end - start;
5515 
5516         if (!count)
5517                 return 0;
5518 
5519         sort(start, count, sizeof(*start),
5520              ftrace_cmp_ips, NULL);
5521 
5522         start_pg = ftrace_allocate_pages(count);
5523         if (!start_pg)
5524                 return -ENOMEM;
5525 
5526         mutex_lock(&ftrace_lock);
5527 
5528         /*
5529          * Core and each module needs their own pages, as
5530          * modules will free them when they are removed.
5531          * Force a new page to be allocated for modules.
5532          */
5533         if (!mod) {
5534                 WARN_ON(ftrace_pages || ftrace_pages_start);
5535                 /* First initialization */
5536                 ftrace_pages = ftrace_pages_start = start_pg;
5537         } else {
5538                 if (!ftrace_pages)
5539                         goto out;
5540 
5541                 if (WARN_ON(ftrace_pages->next)) {
5542                         /* Hmm, we have free pages? */
5543                         while (ftrace_pages->next)
5544                                 ftrace_pages = ftrace_pages->next;
5545                 }
5546 
5547                 ftrace_pages->next = start_pg;
5548         }
5549 
5550         p = start;
5551         pg = start_pg;
5552         while (p < end) {
5553                 addr = ftrace_call_adjust(*p++);
5554                 /*
5555                  * Some architecture linkers will pad between
5556                  * the different mcount_loc sections of different
5557                  * object files to satisfy alignments.
5558                  * Skip any NULL pointers.
5559                  */
5560                 if (!addr)
5561                         continue;
5562 
5563                 if (pg->index == pg->size) {
5564                         /* We should have allocated enough */
5565                         if (WARN_ON(!pg->next))
5566                                 break;
5567                         pg = pg->next;
5568                 }
5569 
5570                 rec = &pg->records[pg->index++];
5571                 rec->ip = addr;
5572         }
5573 
5574         /* We should have used all pages */
5575         WARN_ON(pg->next);
5576 
5577         /* Assign the last page to ftrace_pages */
5578         ftrace_pages = pg;
5579 
5580         /*
5581          * We only need to disable interrupts on start up
5582          * because we are modifying code that an interrupt
5583          * may execute, and the modification is not atomic.
5584          * But for modules, nothing runs the code we modify
5585          * until we are finished with it, and there's no
5586          * reason to cause large interrupt latencies while we do it.
5587          */
5588         if (!mod)
5589                 local_irq_save(flags);
5590         ftrace_update_code(mod, start_pg);
5591         if (!mod)
5592                 local_irq_restore(flags);
5593         ret = 0;
5594  out:
5595         mutex_unlock(&ftrace_lock);
5596 
5597         return ret;
5598 }
5599 
5600 struct ftrace_mod_func {
5601         struct list_head        list;
5602         char                    *name;
5603         unsigned long           ip;
5604         unsigned int            size;
5605 };
5606 
5607 struct ftrace_mod_map {
5608         struct rcu_head         rcu;
5609         struct list_head        list;
5610         struct module           *mod;
5611         unsigned long           start_addr;
5612         unsigned long           end_addr;
5613         struct list_head        funcs;
5614         unsigned int            num_funcs;
5615 };
5616 
5617 #ifdef CONFIG_MODULES
5618 
5619 #define next_to_ftrace_page(p) container_of(p, struct ftrace_page, next)
5620 
5621 static LIST_HEAD(ftrace_mod_maps);
5622 
5623 static int referenced_filters(struct dyn_ftrace *rec)
5624 {
5625         struct ftrace_ops *ops;
5626         int cnt = 0;
5627 
5628         for (ops = ftrace_ops_list; ops != &ftrace_list_end; ops = ops->next) {
5629                 if (ops_references_rec(ops, rec))
5630                     cnt++;
5631         }
5632 
5633         return cnt;
5634 }
5635 
5636 static void
5637 clear_mod_from_hash(struct ftrace_page *pg, struct ftrace_hash *hash)
5638 {
5639         struct ftrace_func_entry *entry;
5640         struct dyn_ftrace *rec;
5641         int i;
5642 
5643         if (ftrace_hash_empty(hash))
5644                 return;
5645 
5646         for (i = 0; i < pg->index; i++) {
5647                 rec = &pg->records[i];
5648                 entry = __ftrace_lookup_ip(hash, rec->ip);
5649                 /*
5650                  * Do not allow this rec to match again.
5651                  * Yeah, it may waste some memory, but will be removed
5652                  * if/when the hash is modified again.
5653                  */
5654                 if (entry)
5655                         entry->ip = 0;
5656         }
5657 }
5658 
5659 /* Clear any records from hashs */
5660 static void clear_mod_from_hashes(struct ftrace_page *pg)
5661 {
5662         struct trace_array *tr;
5663 
5664         mutex_lock(&trace_types_lock);
5665         list_for_each_entry(tr, &ftrace_trace_arrays, list) {
5666                 if (!tr->ops || !tr->ops->func_hash)
5667                         continue;
5668                 mutex_lock(&tr->ops->func_hash->regex_lock);
5669                 clear_mod_from_hash(pg, tr->ops->func_hash->filter_hash);
5670                 clear_mod_from_hash(pg, tr->ops->func_hash->notrace_hash);
5671                 mutex_unlock(&tr->ops->func_hash->regex_lock);
5672         }
5673         mutex_unlock(&trace_types_lock);
5674 }
5675 
5676 static void ftrace_free_mod_map(struct rcu_head *rcu)
5677 {
5678         struct ftrace_mod_map *mod_map = container_of(rcu, struct ftrace_mod_map, rcu);
5679         struct ftrace_mod_func *mod_func;
5680         struct ftrace_mod_func *n;
5681 
5682         /* All the contents of mod_map are now not visible to readers */
5683         list_for_each_entry_safe(mod_func, n, &mod_map->funcs, list) {
5684                 kfree(mod_func->name);
5685                 list_del(&mod_func->list);
5686                 kfree(mod_func);
5687         }
5688 
5689         kfree(mod_map);
5690 }
5691 
5692 void ftrace_release_mod(struct module *mod)
5693 {
5694         struct ftrace_mod_map *mod_map;
5695         struct ftrace_mod_map *n;
5696         struct dyn_ftrace *rec;
5697         struct ftrace_page **last_pg;
5698         struct ftrace_page *tmp_page = NULL;
5699         struct ftrace_page *pg;
5700         int order;
5701 
5702         mutex_lock(&ftrace_lock);
5703 
5704         if (ftrace_disabled)
5705                 goto out_unlock;
5706 
5707         list_for_each_entry_safe(mod_map, n, &ftrace_mod_maps, list) {
5708                 if (mod_map->mod == mod) {
5709                         list_del_rcu(&mod_map->list);
5710                         call_rcu_sched(&mod_map->rcu, ftrace_free_mod_map);
5711                         break;
5712                 }
5713         }
5714 
5715         /*
5716          * Each module has its own ftrace_pages, remove
5717          * them from the list.
5718          */
5719         last_pg = &ftrace_pages_start;
5720         for (pg = ftrace_pages_start; pg; pg = *last_pg) {
5721                 rec = &pg->records[0];
5722                 if (within_module_core(rec->ip, mod) ||
5723                     within_module_init(rec->ip, mod)) {
5724                         /*
5725                          * As core pages are first, the first
5726                          * page should never be a module page.
5727                          */
5728                         if (WARN_ON(pg == ftrace_pages_start))
5729                                 goto out_unlock;
5730 
5731                         /* Check if we are deleting the last page */
5732                         if (pg == ftrace_pages)
5733                                 ftrace_pages = next_to_ftrace_page(last_pg);
5734 
5735                         ftrace_update_tot_cnt -= pg->index;
5736                         *last_pg = pg->next;
5737 
5738                         pg->next = tmp_page;
5739                         tmp_page = pg;
5740                 } else
5741                         last_pg = &pg->next;
5742         }
5743  out_unlock:
5744         mutex_unlock(&ftrace_lock);
5745 
5746         for (pg = tmp_page; pg; pg = tmp_page) {
5747 
5748                 /* Needs to be called outside of ftrace_lock */
5749                 clear_mod_from_hashes(pg);
5750 
5751                 order = get_count_order(pg->size / ENTRIES_PER_PAGE);
5752                 free_pages((unsigned long)pg->records, order);
5753                 tmp_page = pg->next;
5754                 kfree(pg);
5755         }
5756 }
5757 
5758 void ftrace_module_enable(struct module *mod)
5759 {
5760         struct dyn_ftrace *rec;
5761         struct ftrace_page *pg;
5762 
5763         mutex_lock(&ftrace_lock);
5764 
5765         if (ftrace_disabled)
5766                 goto out_unlock;
5767 
5768         /*
5769          * If the tracing is enabled, go ahead and enable the record.
5770          *
5771          * The reason not to enable the record immediatelly is the
5772          * inherent check of ftrace_make_nop/ftrace_make_call for
5773          * correct previous instructions.  Making first the NOP
5774          * conversion puts the module to the correct state, thus
5775          * passing the ftrace_make_call check.
5776          *
5777          * We also delay this to after the module code already set the
5778          * text to read-only, as we now need to set it back to read-write
5779          * so that we can modify the text.
5780          */
5781         if (ftrace_start_up)
5782                 ftrace_arch_code_modify_prepare();
5783 
5784         do_for_each_ftrace_rec(pg, rec) {
5785                 int cnt;
5786                 /*
5787                  * do_for_each_ftrace_rec() is a double loop.
5788                  * module text shares the pg. If a record is
5789                  * not part of this module, then skip this pg,
5790                  * which the "break" will do.
5791                  */
5792                 if (!within_module_core(rec->ip, mod) &&
5793                     !within_module_init(rec->ip, mod))
5794                         break;
5795 
5796                 cnt = 0;
5797 
5798                 /*
5799                  * When adding a module, we need to check if tracers are
5800                  * currently enabled and if they are, and can trace this record,
5801                  * we need to enable the module functions as well as update the
5802                  * reference counts for those function records.
5803                  */
5804                 if (ftrace_start_up)
5805                         cnt += referenced_filters(rec);
5806 
5807                 /* This clears FTRACE_FL_DISABLED */
5808                 rec->flags = cnt;
5809 
5810                 if (ftrace_start_up && cnt) {
5811                         int failed = __ftrace_replace_code(rec, 1);
5812                         if (failed) {
5813                                 ftrace_bug(failed, rec);
5814                                 goto out_loop;
5815                         }
5816                 }
5817 
5818         } while_for_each_ftrace_rec();
5819 
5820  out_loop:
5821         if (ftrace_start_up)
5822                 ftrace_arch_code_modify_post_process();
5823 
5824  out_unlock:
5825         mutex_unlock(&ftrace_lock);
5826 
5827         process_cached_mods(mod->name);
5828 }
5829 
5830 void ftrace_module_init(struct module *mod)
5831 {
5832         if (ftrace_disabled || !mod->num_ftrace_callsites)
5833                 return;
5834 
5835         ftrace_process_locs(mod, mod->ftrace_callsites,
5836                             mod->ftrace_callsites + mod->num_ftrace_callsites);
5837 }
5838 
5839 static void save_ftrace_mod_rec(struct ftrace_mod_map *mod_map,
5840                                 struct dyn_ftrace *rec)
5841 {
5842         struct ftrace_mod_func *mod_func;
5843         unsigned long symsize;
5844         unsigned long offset;
5845         char str[KSYM_SYMBOL_LEN];
5846         char *modname;
5847         const char *ret;
5848 
5849         ret = kallsyms_lookup(rec->ip, &symsize, &offset, &modname, str);
5850         if (!ret)
5851                 return;
5852 
5853         mod_func = kmalloc(sizeof(*mod_func), GFP_KERNEL);
5854         if (!mod_func)
5855                 return;
5856 
5857         mod_func->name = kstrdup(str, GFP_KERNEL);
5858         if (!mod_func->name) {
5859                 kfree(mod_func);
5860                 return;
5861         }
5862 
5863         mod_func->ip = rec->ip - offset;
5864         mod_func->size = symsize;
5865 
5866         mod_map->num_funcs++;
5867 
5868         list_add_rcu(&mod_func->list, &mod_map->funcs);
5869 }
5870 
5871 static struct ftrace_mod_map *
5872 allocate_ftrace_mod_map(struct module *mod,
5873                         unsigned long start, unsigned long end)
5874 {
5875         struct ftrace_mod_map *mod_map;
5876 
5877         mod_map = kmalloc(sizeof(*mod_map), GFP_KERNEL);
5878         if (!mod_map)
5879                 return NULL;
5880 
5881         mod_map->mod = mod;
5882         mod_map->start_addr = start;
5883         mod_map->end_addr = end;
5884         mod_map->num_funcs = 0;
5885 
5886         INIT_LIST_HEAD_RCU(&mod_map->funcs);
5887 
5888         list_add_rcu(&mod_map->list, &ftrace_mod_maps);
5889 
5890         return mod_map;
5891 }
5892 
5893 static const char *
5894 ftrace_func_address_lookup(struct ftrace_mod_map *mod_map,
5895                            unsigned long addr, unsigned long *size,
5896                            unsigned long *off, char *sym)
5897 {
5898         struct ftrace_mod_func *found_func =  NULL;
5899         struct ftrace_mod_func *mod_func;
5900 
5901         list_for_each_entry_rcu(mod_func, &mod_map->funcs, list) {
5902                 if (addr >= mod_func->ip &&
5903                     addr < mod_func->ip + mod_func->size) {
5904                         found_func = mod_func;
5905                         break;
5906                 }
5907         }
5908 
5909         if (found_func) {
5910                 if (size)
5911                         *size = found_func->size;
5912                 if (off)
5913                         *off = addr - found_func->ip;
5914                 if (sym)
5915                         strlcpy(sym, found_func->name, KSYM_NAME_LEN);
5916 
5917                 return found_func->name;
5918         }
5919 
5920         return NULL;
5921 }
5922 
5923 const char *
5924 ftrace_mod_address_lookup(unsigned long addr, unsigned long *size,
5925                    unsigned long *off, char **modname, char *sym)
5926 {
5927         struct ftrace_mod_map *mod_map;
5928         const char *ret = NULL;
5929 
5930         /* mod_map is freed via call_rcu_sched() */
5931         preempt_disable();
5932         list_for_each_entry_rcu(mod_map, &ftrace_mod_maps, list) {
5933                 ret = ftrace_func_address_lookup(mod_map, addr, size, off, sym);
5934                 if (ret) {
5935                         if (modname)
5936                                 *modname = mod_map->mod->name;
5937                         break;
5938                 }
5939         }
5940         preempt_enable();
5941 
5942         return ret;
5943 }
5944 
5945 int ftrace_mod_get_kallsym(unsigned int symnum, unsigned long *value,
5946                            char *type, char *name,
5947                            char *module_name, int *exported)
5948 {
5949         struct ftrace_mod_map *mod_map;
5950         struct ftrace_mod_func *mod_func;
5951 
5952         preempt_disable();
5953         list_for_each_entry_rcu(mod_map, &ftrace_mod_maps, list) {
5954 
5955                 if (symnum >= mod_map->num_funcs) {
5956                         symnum -= mod_map->num_funcs;
5957                         continue;
5958                 }
5959 
5960                 list_for_each_entry_rcu(mod_func, &mod_map->funcs, list) {
5961                         if (symnum > 1) {
5962                                 symnum--;
5963                                 continue;
5964                         }
5965 
5966                         *value = mod_func->ip;
5967                         *type = 'T';
5968                         strlcpy(name, mod_func->name, KSYM_NAME_LEN);
5969                         strlcpy(module_name, mod_map->mod->name, MODULE_NAME_LEN);
5970                         *exported = 1;
5971                         preempt_enable();
5972                         return 0;
5973                 }
5974                 WARN_ON(1);
5975                 break;
5976         }
5977         preempt_enable();
5978         return -ERANGE;
5979 }
5980 
5981 #else
5982 static void save_ftrace_mod_rec(struct ftrace_mod_map *mod_map,
5983                                 struct dyn_ftrace *rec) { }
5984 static inline struct ftrace_mod_map *
5985 allocate_ftrace_mod_map(struct module *mod,
5986                         unsigned long start, unsigned long end)
5987 {
5988         return NULL;
5989 }
5990 #endif /* CONFIG_MODULES */
5991 
5992 struct ftrace_init_func {
5993         struct list_head list;
5994         unsigned long ip;
5995 };
5996 
5997 /* Clear any init ips from hashes */
5998 static void
5999 clear_func_from_hash(struct ftrace_init_func *func, struct ftrace_hash *hash)
6000 {
6001         struct ftrace_func_entry *entry;
6002 
6003         if (ftrace_hash_empty(hash))
6004                 return;
6005 
6006         entry = __ftrace_lookup_ip(hash, func->ip);
6007 
6008         /*
6009          * Do not allow this rec to match again.
6010          * Yeah, it may waste some memory, but will be removed
6011          * if/when the hash is modified again.
6012          */
6013         if (entry)
6014                 entry->ip = 0;
6015 }
6016 
6017 static void
6018 clear_func_from_hashes(struct ftrace_init_func *func)
6019 {
6020         struct trace_array *tr;
6021 
6022         mutex_lock(&trace_types_lock);
6023         list_for_each_entry(tr, &ftrace_trace_arrays, list) {
6024                 if (!tr->ops || !tr->ops->func_hash)
6025                         continue;
6026                 mutex_lock(&tr->ops->func_hash->regex_lock);
6027                 clear_func_from_hash(func, tr->ops->func_hash->filter_hash);
6028                 clear_func_from_hash(func, tr->ops->func_hash->notrace_hash);
6029                 mutex_unlock(&tr->ops->func_hash->regex_lock);
6030         }
6031         mutex_unlock(&trace_types_lock);
6032 }
6033 
6034 static void add_to_clear_hash_list(struct list_head *clear_list,
6035                                    struct dyn_ftrace *rec)
6036 {
6037         struct ftrace_init_func *func;
6038 
6039         func = kmalloc(sizeof(*func), GFP_KERNEL);
6040         if (!func) {
6041                 WARN_ONCE(1, "alloc failure, ftrace filter could be stale\n");
6042                 return;
6043         }
6044 
6045         func->ip = rec->ip;
6046         list_add(&func->list, clear_list);
6047 }
6048 
6049 void ftrace_free_mem(struct module *mod, void *start_ptr, void *end_ptr)
6050 {
6051         unsigned long start = (unsigned long)(start_ptr);
6052         unsigned long end = (unsigned long)(end_ptr);
6053         struct ftrace_page **last_pg = &ftrace_pages_start;
6054         struct ftrace_page *pg;
6055         struct dyn_ftrace *rec;
6056         struct dyn_ftrace key;
6057         struct ftrace_mod_map *mod_map = NULL;
6058         struct ftrace_init_func *func, *func_next;
6059         struct list_head clear_hash;
6060         int order;
6061 
6062         INIT_LIST_HEAD(&clear_hash);
6063 
6064         key.ip = start;
6065         key.flags = end;        /* overload flags, as it is unsigned long */
6066 
6067         mutex_lock(&ftrace_lock);
6068 
6069         /*
6070          * If we are freeing module init memory, then check if
6071          * any tracer is active. If so, we need to save a mapping of
6072          * the module functions being freed with the address.
6073          */
6074         if (mod && ftrace_ops_list != &ftrace_list_end)
6075                 mod_map = allocate_ftrace_mod_map(mod, start, end);
6076 
6077         for (pg = ftrace_pages_start; pg; last_pg = &pg->next, pg = *last_pg) {
6078                 if (end < pg->records[0].ip ||
6079                     start >= (pg->records[pg->index - 1].ip + MCOUNT_INSN_SIZE))
6080                         continue;
6081  again:
6082                 rec = bsearch(&key, pg->records, pg->index,
6083                               sizeof(struct dyn_ftrace),
6084                               ftrace_cmp_recs);
6085                 if (!rec)
6086                         continue;
6087 
6088                 /* rec will be cleared from hashes after ftrace_lock unlock */
6089                 add_to_clear_hash_list(&clear_hash, rec);
6090 
6091                 if (mod_map)
6092                         save_ftrace_mod_rec(mod_map, rec);
6093 
6094                 pg->index--;
6095                 ftrace_update_tot_cnt--;
6096                 if (!pg->index) {
6097                         *last_pg = pg->next;
6098                         order = get_count_order(pg->size / ENTRIES_PER_PAGE);
6099                         free_pages((unsigned long)pg->records, order);
6100                         kfree(pg);
6101                         pg = container_of(last_pg, struct ftrace_page, next);
6102                         if (!(*last_pg))
6103                                 ftrace_pages = pg;
6104                         continue;
6105                 }
6106                 memmove(rec, rec + 1,
6107                         (pg->index - (rec - pg->records)) * sizeof(*rec));
6108                 /* More than one function may be in this block */
6109                 goto again;
6110         }
6111         mutex_unlock(&ftrace_lock);
6112 
6113         list_for_each_entry_safe(func, func_next, &clear_hash, list) {
6114                 clear_func_from_hashes(func);
6115                 kfree(func);
6116         }
6117 }
6118 
6119 void __init ftrace_free_init_mem(void)
6120 {
6121         void *start = (void *)(&__init_begin);
6122         void *end = (void *)(&__init_end);
6123 
6124         ftrace_free_mem(NULL, start, end);
6125 }
6126 
6127 void __init ftrace_init(void)
6128 {
6129         extern unsigned long __start_mcount_loc[];
6130         extern unsigned long __stop_mcount_loc[];
6131         unsigned long count, flags;
6132         int ret;
6133 
6134         local_irq_save(flags);
6135         ret = ftrace_dyn_arch_init();
6136         local_irq_restore(flags);
6137         if (ret)
6138                 goto failed;
6139 
6140         count = __stop_mcount_loc - __start_mcount_loc;
6141         if (!count) {
6142                 pr_info("ftrace: No functions to be traced?\n");
6143                 goto failed;
6144         }
6145 
6146         pr_info("ftrace: allocating %ld entries in %ld pages\n",
6147                 count, count / ENTRIES_PER_PAGE + 1);
6148 
6149         last_ftrace_enabled = ftrace_enabled = 1;
6150 
6151         ret = ftrace_process_locs(NULL,
6152                                   __start_mcount_loc,
6153                                   __stop_mcount_loc);
6154 
6155         set_ftrace_early_filters();
6156 
6157         return;
6158  failed:
6159         ftrace_disabled = 1;
6160 }
6161 
6162 /* Do nothing if arch does not support this */
6163 void __weak arch_ftrace_update_trampoline(struct ftrace_ops *ops)
6164 {
6165 }
6166 
6167 static void ftrace_update_trampoline(struct ftrace_ops *ops)
6168 {
6169         arch_ftrace_update_trampoline(ops);
6170 }
6171 
6172 void ftrace_init_trace_array(struct trace_array *tr)
6173 {
6174         INIT_LIST_HEAD(&tr->func_probes);
6175         INIT_LIST_HEAD(&tr->mod_trace);
6176         INIT_LIST_HEAD(&tr->mod_notrace);
6177 }
6178 #else
6179 
6180 static struct ftrace_ops global_ops = {
6181         .func                   = ftrace_stub,
6182         .flags                  = FTRACE_OPS_FL_RECURSION_SAFE |
6183                                   FTRACE_OPS_FL_INITIALIZED |
6184                                   FTRACE_OPS_FL_PID,
6185 };
6186 
6187 static int __init ftrace_nodyn_init(void)
6188 {
6189         ftrace_enabled = 1;
6190         return 0;
6191 }
6192 core_initcall(ftrace_nodyn_init);
6193 
6194 static inline int ftrace_init_dyn_tracefs(struct dentry *d_tracer) { return 0; }
6195 static inline void ftrace_startup_enable(int command) { }
6196 static inline void ftrace_startup_all(int command) { }
6197 /* Keep as macros so we do not need to define the commands */
6198 # define ftrace_startup(ops, command)                                   \
6199         ({                                                              \
6200                 int ___ret = __register_ftrace_function(ops);           \
6201                 if (!___ret)                                            \
6202                         (ops)->flags |= FTRACE_OPS_FL_ENABLED;          \
6203                 ___ret;                                                 \
6204         })
6205 # define ftrace_shutdown(ops, command)                                  \
6206         ({                                                              \
6207                 int ___ret = __unregister_ftrace_function(ops);         \
6208                 if (!___ret)                                            \
6209                         (ops)->flags &= ~FTRACE_OPS_FL_ENABLED;         \
6210                 ___ret;                                                 \
6211         })
6212 
6213 # define ftrace_startup_sysctl()        do { } while (0)
6214 # define ftrace_shutdown_sysctl()       do { } while (0)
6215 
6216 static inline int
6217 ftrace_ops_test(struct ftrace_ops *ops, unsigned long ip, void *regs)
6218 {
6219         return 1;
6220 }
6221 
6222 static void ftrace_update_trampoline(struct ftrace_ops *ops)
6223 {
6224 }
6225 
6226 #endif /* CONFIG_DYNAMIC_FTRACE */
6227 
6228 __init void ftrace_init_global_array_ops(struct trace_array *tr)
6229 {
6230         tr->ops = &global_ops;
6231         tr->ops->private = tr;
6232         ftrace_init_trace_array(tr);
6233 }
6234 
6235 void ftrace_init_array_ops(struct trace_array *tr, ftrace_func_t func)
6236 {
6237         /* If we filter on pids, update to use the pid function */
6238         if (tr->flags & TRACE_ARRAY_FL_GLOBAL) {
6239                 if (WARN_ON(tr->ops->func != ftrace_stub))
6240                         printk("ftrace ops had %pS for function\n",
6241                                tr->ops->func);
6242         }
6243         tr->ops->func = func;
6244         tr->ops->private = tr;
6245 }
6246 
6247 void ftrace_reset_array_ops(struct trace_array *tr)
6248 {
6249         tr->ops->func = ftrace_stub;
6250 }
6251 
6252 static inline void
6253 __ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip,
6254                        struct ftrace_ops *ignored, struct pt_regs *regs)
6255 {
6256         struct ftrace_ops *op;
6257         int bit;
6258 
6259         bit = trace_test_and_set_recursion(TRACE_LIST_START, TRACE_LIST_MAX);
6260         if (bit < 0)
6261                 return;
6262 
6263         /*
6264          * Some of the ops may be dynamically allocated,
6265          * they must be freed after a synchronize_sched().
6266          */
6267         preempt_disable_notrace();
6268 
6269         do_for_each_ftrace_op(op, ftrace_ops_list) {
6270                 /*
6271                  * Check the following for each ops before calling their func:
6272                  *  if RCU flag is set, then rcu_is_watching() must be true
6273                  *  if PER_CPU is set, then ftrace_function_local_disable()
6274                  *                          must be false
6275                  *  Otherwise test if the ip matches the ops filter
6276                  *
6277                  * If any of the above fails then the op->func() is not executed.
6278                  */
6279                 if ((!(op->flags & FTRACE_OPS_FL_RCU) || rcu_is_watching()) &&
6280                     ftrace_ops_test(op, ip, regs)) {
6281                         if (FTRACE_WARN_ON(!op->func)) {
6282                                 pr_warn("op=%p %pS\n", op, op);
6283                                 goto out;
6284                         }
6285                         op->func(ip, parent_ip, op, regs);
6286                 }
6287         } while_for_each_ftrace_op(op);
6288 out:
6289         preempt_enable_notrace();
6290         trace_clear_recursion(bit);
6291 }
6292 
6293 /*
6294  * Some archs only support passing ip and parent_ip. Even though
6295  * the list function ignores the op parameter, we do not want any
6296  * C side effects, where a function is called without the caller
6297  * sending a third parameter.
6298  * Archs are to support both the regs and ftrace_ops at the same time.
6299  * If they support ftrace_ops, it is assumed they support regs.
6300  * If call backs want to use regs, they must either check for regs
6301  * being NULL, or CONFIG_DYNAMIC_FTRACE_WITH_REGS.
6302  * Note, CONFIG_DYNAMIC_FTRACE_WITH_REGS expects a full regs to be saved.
6303  * An architecture can pass partial regs with ftrace_ops and still
6304  * set the ARCH_SUPPORTS_FTRACE_OPS.
6305  */
6306 #if ARCH_SUPPORTS_FTRACE_OPS
6307 static void ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip,
6308                                  struct ftrace_ops *op, struct pt_regs *regs)
6309 {
6310         __ftrace_ops_list_func(ip, parent_ip, NULL, regs);
6311 }
6312 #else
6313 static void ftrace_ops_no_ops(unsigned long ip, unsigned long parent_ip)
6314 {
6315         __ftrace_ops_list_func(ip, parent_ip, NULL, NULL);
6316 }
6317 #endif
6318 
6319 /*
6320  * If there's only one function registered but it does not support
6321  * recursion, needs RCU protection and/or requires per cpu handling, then
6322  * this function will be called by the mcount trampoline.
6323  */
6324 static void ftrace_ops_assist_func(unsigned long ip, unsigned long parent_ip,
6325                                    struct ftrace_ops *op, struct pt_regs *regs)
6326 {
6327         int bit;
6328 
6329         if ((op->flags & FTRACE_OPS_FL_RCU) && !rcu_is_watching())
6330                 return;
6331 
6332         bit = trace_test_and_set_recursion(TRACE_LIST_START, TRACE_LIST_MAX);
6333         if (bit < 0)
6334                 return;
6335 
6336         preempt_disable_notrace();
6337 
6338         op->func(ip, parent_ip, op, regs);
6339 
6340         preempt_enable_notrace();
6341         trace_clear_recursion(bit);
6342 }
6343 
6344 /**
6345  * ftrace_ops_get_func - get the function a trampoline should call
6346  * @ops: the ops to get the function for
6347  *
6348  * Normally the mcount trampoline will call the ops->func, but there
6349  * are times that it should not. For example, if the ops does not
6350  * have its own recursion protection, then it should call the
6351  * ftrace_ops_assist_func() instead.
6352  *
6353  * Returns the function that the trampoline should call for @ops.
6354  */
6355 ftrace_func_t ftrace_ops_get_func(struct ftrace_ops *ops)
6356 {
6357         /*
6358          * If the function does not handle recursion, needs to be RCU safe,
6359          * or does per cpu logic, then we need to call the assist handler.
6360          */
6361         if (!(ops->flags & FTRACE_OPS_FL_RECURSION_SAFE) ||
6362             ops->flags & FTRACE_OPS_FL_RCU)
6363                 return ftrace_ops_assist_func;
6364 
6365         return ops->func;
6366 }
6367 
6368 static void
6369 ftrace_filter_pid_sched_switch_probe(void *data, bool preempt,
6370                     struct task_struct *prev, struct task_struct *next)
6371 {
6372         struct trace_array *tr = data;
6373         struct trace_pid_list *pid_list;
6374 
6375         pid_list = rcu_dereference_sched(tr->function_pids);
6376 
6377         this_cpu_write(tr->trace_buffer.data->ftrace_ignore_pid,
6378                        trace_ignore_this_task(pid_list, next));
6379 }
6380 
6381 static void
6382 ftrace_pid_follow_sched_process_fork(void *data,
6383                                      struct task_struct *self,
6384                                      struct task_struct *task)
6385 {
6386         struct trace_pid_list *pid_list;
6387         struct trace_array *tr = data;
6388 
6389         pid_list = rcu_dereference_sched(tr->function_pids);
6390         trace_filter_add_remove_task(pid_list, self, task);
6391 }
6392 
6393 static void
6394 ftrace_pid_follow_sched_process_exit(void *data, struct task_struct *task)
6395 {
6396         struct trace_pid_list *pid_list;
6397         struct trace_array *tr = data;
6398 
6399         pid_list = rcu_dereference_sched(tr->function_pids);
6400         trace_filter_add_remove_task(pid_list, NULL, task);
6401 }
6402 
6403 void ftrace_pid_follow_fork(struct trace_array *tr, bool enable)
6404 {
6405         if (enable) {
6406                 register_trace_sched_process_fork(ftrace_pid_follow_sched_process_fork,
6407                                                   tr);
6408                 register_trace_sched_process_exit(ftrace_pid_follow_sched_process_exit,
6409                                                   tr);
6410         } else {
6411                 unregister_trace_sched_process_fork(ftrace_pid_follow_sched_process_fork,
6412                                                     tr);
6413                 unregister_trace_sched_process_exit(ftrace_pid_follow_sched_process_exit,
6414                                                     tr);
6415         }
6416 }
6417 
6418 static void clear_ftrace_pids(struct trace_array *tr)
6419 {
6420         struct trace_pid_list *pid_list;
6421         int cpu;
6422 
6423         pid_list = rcu_dereference_protected(tr->function_pids,
6424                                              lockdep_is_held(&ftrace_lock));
6425         if (!pid_list)
6426                 return;
6427 
6428         unregister_trace_sched_switch(ftrace_filter_pid_sched_switch_probe, tr);
6429 
6430         for_each_possible_cpu(cpu)
6431                 per_cpu_ptr(tr->trace_buffer.data, cpu)->ftrace_ignore_pid = false;
6432 
6433         rcu_assign_pointer(tr->function_pids, NULL);
6434 
6435         /* Wait till all users are no longer using pid filtering */
6436         synchronize_sched();
6437 
6438         trace_free_pid_list(pid_list);
6439 }
6440 
6441 void ftrace_clear_pids(struct trace_array *tr)
6442 {
6443         mutex_lock(&ftrace_lock);
6444 
6445         clear_ftrace_pids(tr);
6446 
6447         mutex_unlock(&ftrace_lock);
6448 }
6449 
6450 static void ftrace_pid_reset(struct trace_array *tr)
6451 {
6452         mutex_lock(&ftrace_lock);
6453         clear_ftrace_pids(tr);
6454 
6455         ftrace_update_pid_func();
6456         ftrace_startup_all(0);
6457 
6458         mutex_unlock(&ftrace_lock);
6459 }
6460 
6461 /* Greater than any max PID */
6462 #define FTRACE_NO_PIDS          (void *)(PID_MAX_LIMIT + 1)
6463 
6464 static void *fpid_start(struct seq_file *m, loff_t *pos)
6465         __acquires(RCU)
6466 {
6467         struct trace_pid_list *pid_list;
6468         struct trace_array *tr = m->private;
6469 
6470         mutex_lock(&ftrace_lock);
6471         rcu_read_lock_sched();
6472 
6473         pid_list = rcu_dereference_sched(tr->function_pids);
6474 
6475         if (!pid_list)
6476                 return !(*pos) ? FTRACE_NO_PIDS : NULL;
6477 
6478         return trace_pid_start(pid_list, pos);
6479 }
6480 
6481 static void *fpid_next(struct seq_file *m, void *v, loff_t *pos)
6482 {
6483         struct trace_array *tr = m->private;
6484         struct trace_pid_list *pid_list = rcu_dereference_sched(tr->function_pids);
6485 
6486         if (v == FTRACE_NO_PIDS)
6487                 return NULL;
6488 
6489         return trace_pid_next(pid_list, v, pos);
6490 }
6491 
6492 static void fpid_stop(struct seq_file *m, void *p)
6493         __releases(RCU)
6494 {
6495         rcu_read_unlock_sched();
6496         mutex_unlock(&ftrace_lock);
6497 }
6498 
6499 static int fpid_show(struct seq_file *m, void *v)
6500 {
6501         if (v == FTRACE_NO_PIDS) {
6502                 seq_puts(m, "no pid\n");
6503                 return 0;
6504         }
6505 
6506         return trace_pid_show(m, v);
6507 }
6508 
6509 static const struct seq_operations ftrace_pid_sops = {
6510         .start = fpid_start,
6511         .next = fpid_next,
6512         .stop = fpid_stop,
6513         .show = fpid_show,
6514 };
6515 
6516 static int
6517 ftrace_pid_open(struct inode *inode, struct file *file)
6518 {
6519         struct trace_array *tr = inode->i_private;
6520         struct seq_file *m;
6521         int ret = 0;
6522 
6523         if (trace_array_get(tr) < 0)
6524                 return -ENODEV;
6525 
6526         if ((file->f_mode & FMODE_WRITE) &&
6527             (file->f_flags & O_TRUNC))
6528                 ftrace_pid_reset(tr);
6529 
6530         ret = seq_open(file, &ftrace_pid_sops);
6531         if (ret < 0) {
6532                 trace_array_put(tr);
6533         } else {
6534                 m = file->private_data;
6535                 /* copy tr over to seq ops */
6536                 m->private = tr;
6537         }
6538 
6539         return ret;
6540 }
6541 
6542 static void ignore_task_cpu(void *data)
6543 {
6544         struct trace_array *tr = data;
6545         struct trace_pid_list *pid_list;
6546 
6547         /*
6548          * This function is called by on_each_cpu() while the
6549          * event_mutex is held.
6550          */
6551         pid_list = rcu_dereference_protected(tr->function_pids,
6552                                              mutex_is_locked(&ftrace_lock));
6553 
6554         this_cpu_write(tr->trace_buffer.data->ftrace_ignore_pid,
6555                        trace_ignore_this_task(pid_list, current));
6556 }
6557 
6558 static ssize_t
6559 ftrace_pid_write(struct file *filp, const char __user *ubuf,
6560                    size_t cnt, loff_t *ppos)
6561 {
6562         struct seq_file *m = filp->private_data;
6563         struct trace_array *tr = m->private;
6564         struct trace_pid_list *filtered_pids = NULL;
6565         struct trace_pid_list *pid_list;
6566         ssize_t ret;
6567 
6568         if (!cnt)
6569                 return 0;
6570 
6571         mutex_lock(&ftrace_lock);
6572 
6573         filtered_pids = rcu_dereference_protected(tr->function_pids,
6574                                              lockdep_is_held(&ftrace_lock));
6575 
6576         ret = trace_pid_write(filtered_pids, &pid_list, ubuf, cnt);
6577         if (ret < 0)
6578                 goto out;
6579 
6580         rcu_assign_pointer(tr->function_pids, pid_list);
6581 
6582         if (filtered_pids) {
6583                 synchronize_sched();
6584                 trace_free_pid_list(filtered_pids);
6585         } else if (pid_list) {
6586                 /* Register a probe to set whether to ignore the tracing of a task */
6587                 register_trace_sched_switch(ftrace_filter_pid_sched_switch_probe, tr);
6588         }
6589 
6590         /*
6591          * Ignoring of pids is done at task switch. But we have to
6592          * check for those tasks that are currently running.
6593          * Always do this in case a pid was appended or removed.
6594          */
6595         on_each_cpu(ignore_task_cpu, tr, 1);
6596 
6597         ftrace_update_pid_func();
6598         ftrace_startup_all(0);
6599  out:
6600         mutex_unlock(&ftrace_lock);
6601 
6602         if (ret > 0)
6603                 *ppos += ret;
6604 
6605         return ret;
6606 }
6607 
6608 static int
6609 ftrace_pid_release(struct inode *inode, struct file *file)
6610 {
6611         struct trace_array *tr = inode->i_private;
6612 
6613         trace_array_put(tr);
6614 
6615         return seq_release(inode, file);
6616 }
6617 
6618 static const struct file_operations ftrace_pid_fops = {
6619         .open           = ftrace_pid_open,
6620         .write          = ftrace_pid_write,
6621         .read           = seq_read,
6622         .llseek         = tracing_lseek,
6623         .release        = ftrace_pid_release,
6624 };
6625 
6626 void ftrace_init_tracefs(struct trace_array *tr, struct dentry *d_tracer)
6627 {
6628         trace_create_file("set_ftrace_pid", 0644, d_tracer,
6629                             tr, &ftrace_pid_fops);
6630 }
6631 
6632 void __init ftrace_init_tracefs_toplevel(struct trace_array *tr,
6633                                          struct dentry *d_tracer)
6634 {
6635         /* Only the top level directory has the dyn_tracefs and profile */
6636         WARN_ON(!(tr->flags & TRACE_ARRAY_FL_GLOBAL));
6637 
6638         ftrace_init_dyn_tracefs(d_tracer);
6639         ftrace_profile_tracefs(d_tracer);
6640 }
6641 
6642 /**
6643  * ftrace_kill - kill ftrace
6644  *
6645  * This function should be used by panic code. It stops ftrace
6646  * but in a not so nice way. If you need to simply kill ftrace
6647  * from a non-atomic section, use ftrace_kill.
6648  */
6649 void ftrace_kill(void)
6650 {
6651         ftrace_disabled = 1;
6652         ftrace_enabled = 0;
6653         ftrace_trace_function = ftrace_stub;
6654 }
6655 
6656 /**
6657  * Test if ftrace is dead or not.
6658  */
6659 int ftrace_is_dead(void)
6660 {
6661         return ftrace_disabled;
6662 }
6663 
6664 /**
6665  * register_ftrace_function - register a function for profiling
6666  * @ops - ops structure that holds the function for profiling.
6667  *
6668  * Register a function to be called by all functions in the
6669  * kernel.
6670  *
6671  * Note: @ops->func and all the functions it calls must be labeled
6672  *       with "notrace", otherwise it will go into a
6673  *       recursive loop.
6674  */
6675 int register_ftrace_function(struct ftrace_ops *ops)
6676 {
6677         int ret = -1;
6678 
6679         ftrace_ops_init(ops);
6680 
6681         mutex_lock(&ftrace_lock);
6682 
6683         ret = ftrace_startup(ops, 0);
6684 
6685         mutex_unlock(&ftrace_lock);
6686 
6687         return ret;
6688 }
6689 EXPORT_SYMBOL_GPL(register_ftrace_function);
6690 
6691 /**
6692  * unregister_ftrace_function - unregister a function for profiling.
6693  * @ops - ops structure that holds the function to unregister
6694  *
6695  * Unregister a function that was added to be called by ftrace profiling.
6696  */
6697 int unregister_ftrace_function(struct ftrace_ops *ops)
6698 {
6699         int ret;
6700 
6701         mutex_lock(&ftrace_lock);
6702         ret = ftrace_shutdown(ops, 0);
6703         mutex_unlock(&ftrace_lock);
6704 
6705         return ret;
6706 }
6707 EXPORT_SYMBOL_GPL(unregister_ftrace_function);
6708 
6709 int
6710 ftrace_enable_sysctl(struct ctl_table *table, int write,
6711                      void __user *buffer, size_t *lenp,
6712                      loff_t *ppos)
6713 {
6714         int ret = -ENODEV;
6715 
6716         mutex_lock(&ftrace_lock);
6717 
6718         if (unlikely(ftrace_disabled))
6719                 goto out;
6720 
6721         ret = proc_dointvec(table, write, buffer, lenp, ppos);
6722 
6723         if (ret || !write || (last_ftrace_enabled == !!ftrace_enabled))
6724                 goto out;
6725 
6726         last_ftrace_enabled = !!ftrace_enabled;
6727 
6728         if (ftrace_enabled) {
6729 
6730                 /* we are starting ftrace again */
6731                 if (rcu_dereference_protected(ftrace_ops_list,
6732                         lockdep_is_held(&ftrace_lock)) != &ftrace_list_end)
6733                         update_ftrace_function();
6734 
6735                 ftrace_startup_sysctl();
6736 
6737         } else {
6738                 /* stopping ftrace calls (just send to ftrace_stub) */
6739                 ftrace_trace_function = ftrace_stub;
6740 
6741                 ftrace_shutdown_sysctl();
6742         }
6743 
6744  out:
6745         mutex_unlock(&ftrace_lock);
6746         return ret;
6747 }
6748 
6749 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
6750 
6751 static struct ftrace_ops graph_ops = {
6752         .func                   = ftrace_stub,
6753         .flags                  = FTRACE_OPS_FL_RECURSION_SAFE |
6754                                    FTRACE_OPS_FL_INITIALIZED |
6755                                    FTRACE_OPS_FL_PID |
6756                                    FTRACE_OPS_FL_STUB,
6757 #ifdef FTRACE_GRAPH_TRAMP_ADDR
6758         .trampoline             = FTRACE_GRAPH_TRAMP_ADDR,
6759         /* trampoline_size is only needed for dynamically allocated tramps */
6760 #endif
6761         ASSIGN_OPS_HASH(graph_ops, &global_ops.local_hash)
6762 };
6763 
6764 void ftrace_graph_sleep_time_control(bool enable)
6765 {
6766         fgraph_sleep_time = enable;
6767 }
6768 
6769 void ftrace_graph_graph_time_control(bool enable)
6770 {
6771         fgraph_graph_time = enable;
6772 }
6773 
6774 int ftrace_graph_entry_stub(struct ftrace_graph_ent *trace)
6775 {
6776         return 0;
6777 }
6778 
6779 /* The callbacks that hook a function */
6780 trace_func_graph_ret_t ftrace_graph_return =
6781                         (trace_func_graph_ret_t)ftrace_stub;
6782 trace_func_graph_ent_t ftrace_graph_entry = ftrace_graph_entry_stub;
6783 static trace_func_graph_ent_t __ftrace_graph_entry = ftrace_graph_entry_stub;
6784 
6785 /* Try to assign a return stack array on FTRACE_RETSTACK_ALLOC_SIZE tasks. */
6786 static int alloc_retstack_tasklist(struct ftrace_ret_stack **ret_stack_list)
6787 {
6788         int i;
6789         int ret = 0;
6790         int start = 0, end = FTRACE_RETSTACK_ALLOC_SIZE;
6791         struct task_struct *g, *t;
6792 
6793         for (i = 0; i < FTRACE_RETSTACK_ALLOC_SIZE; i++) {
6794                 ret_stack_list[i] =
6795                         kmalloc_array(FTRACE_RETFUNC_DEPTH,
6796                                       sizeof(struct ftrace_ret_stack),
6797                                       GFP_KERNEL);
6798                 if (!ret_stack_list[i]) {
6799                         start = 0;
6800                         end = i;
6801                         ret = -ENOMEM;
6802                         goto free;
6803                 }
6804         }
6805 
6806         read_lock(&tasklist_lock);
6807         do_each_thread(g, t) {
6808                 if (start == end) {
6809                         ret = -EAGAIN;
6810                         goto unlock;
6811                 }
6812 
6813                 if (t->ret_stack == NULL) {
6814                         atomic_set(&t->tracing_graph_pause, 0);
6815                         atomic_set(&t->trace_overrun, 0);
6816                         t->curr_ret_stack = -1;
6817                         /* Make sure the tasks see the -1 first: */
6818                         smp_wmb();
6819                         t->ret_stack = ret_stack_list[start++];
6820                 }
6821         } while_each_thread(g, t);
6822 
6823 unlock:
6824         read_unlock(&tasklist_lock);
6825 free:
6826         for (i = start; i < end; i++)
6827                 kfree(ret_stack_list[i]);
6828         return ret;
6829 }
6830 
6831 static void
6832 ftrace_graph_probe_sched_switch(void *ignore, bool preempt,
6833                         struct task_struct *prev, struct task_struct *next)
6834 {
6835         unsigned long long timestamp;
6836         int index;
6837 
6838         /*
6839          * Does the user want to count the time a function was asleep.
6840          * If so, do not update the time stamps.
6841          */
6842         if (fgraph_sleep_time)
6843                 return;
6844 
6845         timestamp = trace_clock_local();
6846 
6847         prev->ftrace_timestamp = timestamp;
6848 
6849         /* only process tasks that we timestamped */
6850         if (!next->ftrace_timestamp)
6851                 return;
6852 
6853         /*
6854          * Update all the counters in next to make up for the
6855          * time next was sleeping.
6856          */
6857         timestamp -= next->ftrace_timestamp;
6858 
6859         for (index = next->curr_ret_stack; index >= 0; index--)
6860                 next->ret_stack[index].calltime += timestamp;
6861 }
6862 
6863 /* Allocate a return stack for each task */
6864 static int start_graph_tracing(void)
6865 {
6866         struct ftrace_ret_stack **ret_stack_list;
6867         int ret, cpu;
6868 
6869         ret_stack_list = kmalloc_array(FTRACE_RETSTACK_ALLOC_SIZE,
6870                                        sizeof(struct ftrace_ret_stack *),
6871                                        GFP_KERNEL);
6872 
6873         if (!ret_stack_list)
6874                 return -ENOMEM;
6875 
6876         /* The cpu_boot init_task->ret_stack will never be freed */
6877         for_each_online_cpu(cpu) {
6878                 if (!idle_task(cpu)->ret_stack)
6879                         ftrace_graph_init_idle_task(idle_task(cpu), cpu);
6880         }
6881 
6882         do {
6883                 ret = alloc_retstack_tasklist(ret_stack_list);
6884         } while (ret == -EAGAIN);
6885 
6886         if (!ret) {
6887                 ret = register_trace_sched_switch(ftrace_graph_probe_sched_switch, NULL);
6888                 if (ret)
6889                         pr_info("ftrace_graph: Couldn't activate tracepoint"
6890                                 " probe to kernel_sched_switch\n");
6891         }
6892 
6893         kfree(ret_stack_list);
6894         return ret;
6895 }
6896 
6897 /*
6898  * Hibernation protection.
6899  * The state of the current task is too much unstable during
6900  * suspend/restore to disk. We want to protect against that.
6901  */
6902 static int
6903 ftrace_suspend_notifier_call(struct notifier_block *bl, unsigned long state,
6904                                                         void *unused)
6905 {
6906         switch (state) {
6907         case PM_HIBERNATION_PREPARE:
6908                 pause_graph_tracing();
6909                 break;
6910 
6911         case PM_POST_HIBERNATION:
6912                 unpause_graph_tracing();
6913                 break;
6914         }
6915         return NOTIFY_DONE;
6916 }
6917 
6918 static int ftrace_graph_entry_test(struct ftrace_graph_ent *trace)
6919 {
6920         if (!ftrace_ops_test(&global_ops, trace->func, NULL))
6921                 return 0;
6922         return __ftrace_graph_entry(trace);
6923 }
6924 
6925 /*
6926  * The function graph tracer should only trace the functions defined
6927  * by set_ftrace_filter and set_ftrace_notrace. If another function
6928  * tracer ops is registered, the graph tracer requires testing the
6929  * function against the global ops, and not just trace any function
6930  * that any ftrace_ops registered.
6931  */
6932 static void update_function_graph_func(void)
6933 {
6934         struct ftrace_ops *op;
6935         bool do_test = false;
6936 
6937         /*
6938          * The graph and global ops share the same set of functions
6939          * to test. If any other ops is on the list, then
6940          * the graph tracing needs to test if its the function
6941          * it should call.
6942          */
6943         do_for_each_ftrace_op(op, ftrace_ops_list) {
6944                 if (op != &global_ops && op != &graph_ops &&
6945                     op != &ftrace_list_end) {
6946                         do_test = true;
6947                         /* in double loop, break out with goto */
6948                         goto out;
6949                 }
6950         } while_for_each_ftrace_op(op);
6951  out:
6952         if (do_test)
6953                 ftrace_graph_entry = ftrace_graph_entry_test;
6954         else
6955                 ftrace_graph_entry = __ftrace_graph_entry;
6956 }
6957 
6958 static struct notifier_block ftrace_suspend_notifier = {
6959         .notifier_call = ftrace_suspend_notifier_call,
6960 };
6961 
6962 int register_ftrace_graph(trace_func_graph_ret_t retfunc,
6963                         trace_func_graph_ent_t entryfunc)
6964 {
6965         int ret = 0;
6966 
6967         mutex_lock(&ftrace_lock);
6968 
6969         /* we currently allow only one tracer registered at a time */
6970         if (ftrace_graph_active) {
6971                 ret = -EBUSY;
6972                 goto out;
6973         }
6974 
6975         register_pm_notifier(&ftrace_suspend_notifier);
6976 
6977         ftrace_graph_active++;
6978         ret = start_graph_tracing();
6979         if (ret) {
6980                 ftrace_graph_active--;
6981                 goto out;
6982         }
6983 
6984         ftrace_graph_return = retfunc;
6985 
6986         /*
6987          * Update the indirect function to the entryfunc, and the
6988          * function that gets called to the entry_test first. Then
6989          * call the update fgraph entry function to determine if
6990          * the entryfunc should be called directly or not.
6991          */
6992         __ftrace_graph_entry = entryfunc;
6993         ftrace_graph_entry = ftrace_graph_entry_test;
6994         update_function_graph_func();
6995 
6996         ret = ftrace_startup(&graph_ops, FTRACE_START_FUNC_RET);
6997 out:
6998         mutex_unlock(&ftrace_lock);
6999         return ret;
7000 }
7001 
7002 void unregister_ftrace_graph(void)
7003 {
7004         mutex_lock(&ftrace_lock);
7005 
7006         if (unlikely(!ftrace_graph_active))
7007                 goto out;
7008 
7009         ftrace_graph_active--;
7010         ftrace_graph_return = (trace_func_graph_ret_t)ftrace_stub;
7011         ftrace_graph_entry = ftrace_graph_entry_stub;
7012         __ftrace_graph_entry = ftrace_graph_entry_stub;
7013         ftrace_shutdown(&graph_ops, FTRACE_STOP_FUNC_RET);
7014         unregister_pm_notifier(&ftrace_suspend_notifier);
7015         unregister_trace_sched_switch(ftrace_graph_probe_sched_switch, NULL);
7016 
7017  out:
7018         mutex_unlock(&ftrace_lock);
7019 }
7020 
7021 static DEFINE_PER_CPU(struct ftrace_ret_stack *, idle_ret_stack);
7022 
7023 static void
7024 graph_init_task(struct task_struct *t, struct ftrace_ret_stack *ret_stack)
7025 {
7026         atomic_set(&t->tracing_graph_pause, 0);
7027         atomic_set(&t->trace_overrun, 0);
7028         t->ftrace_timestamp = 0;
7029         /* make curr_ret_stack visible before we add the ret_stack */
7030         smp_wmb();
7031         t->ret_stack = ret_stack;
7032 }
7033 
7034 /*
7035  * Allocate a return stack for the idle task. May be the first
7036  * time through, or it may be done by CPU hotplug online.
7037  */
7038 void ftrace_graph_init_idle_task(struct task_struct *t, int cpu)
7039 {
7040         t->curr_ret_stack = -1;
7041         /*
7042          * The idle task has no parent, it either has its own
7043          * stack or no stack at all.
7044          */
7045         if (t->ret_stack)
7046                 WARN_ON(t->ret_stack != per_cpu(idle_ret_stack, cpu));
7047 
7048         if (ftrace_graph_active) {
7049                 struct ftrace_ret_stack *ret_stack;
7050 
7051                 ret_stack = per_cpu(idle_ret_stack, cpu);
7052                 if (!ret_stack) {
7053                         ret_stack =
7054                                 kmalloc_array(FTRACE_RETFUNC_DEPTH,
7055                                               sizeof(struct ftrace_ret_stack),
7056                                               GFP_KERNEL);
7057                         if (!ret_stack)
7058                                 return;
7059                         per_cpu(idle_ret_stack, cpu) = ret_stack;
7060                 }
7061                 graph_init_task(t, ret_stack);
7062         }
7063 }
7064 
7065 /* Allocate a return stack for newly created task */
7066 void ftrace_graph_init_task(struct task_struct *t)
7067 {
7068         /* Make sure we do not use the parent ret_stack */
7069         t->ret_stack = NULL;
7070         t->curr_ret_stack = -1;
7071 
7072         if (ftrace_graph_active) {
7073                 struct ftrace_ret_stack *ret_stack;
7074 
7075                 ret_stack = kmalloc_array(FTRACE_RETFUNC_DEPTH,
7076                                           sizeof(struct ftrace_ret_stack),
7077                                           GFP_KERNEL);
7078                 if (!ret_stack)
7079                         return;
7080                 graph_init_task(t, ret_stack);
7081         }
7082 }
7083 
7084 void ftrace_graph_exit_task(struct task_struct *t)
7085 {
7086         struct ftrace_ret_stack *ret_stack = t->ret_stack;
7087 
7088         t->ret_stack = NULL;
7089         /* NULL must become visible to IRQs before we free it: */
7090         barrier();
7091 
7092         kfree(ret_stack);
7093 }
7094 #endif
7095 

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