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

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  1 /*
  2  *
  3  * Function graph tracer.
  4  * Copyright (c) 2008-2009 Frederic Weisbecker <fweisbec@gmail.com>
  5  * Mostly borrowed from function tracer which
  6  * is Copyright (c) Steven Rostedt <srostedt@redhat.com>
  7  *
  8  */
  9 #include <linux/uaccess.h>
 10 #include <linux/ftrace.h>
 11 #include <linux/interrupt.h>
 12 #include <linux/slab.h>
 13 #include <linux/fs.h>
 14 
 15 #include "trace.h"
 16 #include "trace_output.h"
 17 
 18 static bool kill_ftrace_graph;
 19 
 20 /**
 21  * ftrace_graph_is_dead - returns true if ftrace_graph_stop() was called
 22  *
 23  * ftrace_graph_stop() is called when a severe error is detected in
 24  * the function graph tracing. This function is called by the critical
 25  * paths of function graph to keep those paths from doing any more harm.
 26  */
 27 bool ftrace_graph_is_dead(void)
 28 {
 29         return kill_ftrace_graph;
 30 }
 31 
 32 /**
 33  * ftrace_graph_stop - set to permanently disable function graph tracincg
 34  *
 35  * In case of an error int function graph tracing, this is called
 36  * to try to keep function graph tracing from causing any more harm.
 37  * Usually this is pretty severe and this is called to try to at least
 38  * get a warning out to the user.
 39  */
 40 void ftrace_graph_stop(void)
 41 {
 42         kill_ftrace_graph = true;
 43 }
 44 
 45 /* When set, irq functions will be ignored */
 46 static int ftrace_graph_skip_irqs;
 47 
 48 struct fgraph_cpu_data {
 49         pid_t           last_pid;
 50         int             depth;
 51         int             depth_irq;
 52         int             ignore;
 53         unsigned long   enter_funcs[FTRACE_RETFUNC_DEPTH];
 54 };
 55 
 56 struct fgraph_data {
 57         struct fgraph_cpu_data __percpu *cpu_data;
 58 
 59         /* Place to preserve last processed entry. */
 60         struct ftrace_graph_ent_entry   ent;
 61         struct ftrace_graph_ret_entry   ret;
 62         int                             failed;
 63         int                             cpu;
 64 };
 65 
 66 #define TRACE_GRAPH_INDENT      2
 67 
 68 static unsigned int max_depth;
 69 
 70 static struct tracer_opt trace_opts[] = {
 71         /* Display overruns? (for self-debug purpose) */
 72         { TRACER_OPT(funcgraph-overrun, TRACE_GRAPH_PRINT_OVERRUN) },
 73         /* Display CPU ? */
 74         { TRACER_OPT(funcgraph-cpu, TRACE_GRAPH_PRINT_CPU) },
 75         /* Display Overhead ? */
 76         { TRACER_OPT(funcgraph-overhead, TRACE_GRAPH_PRINT_OVERHEAD) },
 77         /* Display proc name/pid */
 78         { TRACER_OPT(funcgraph-proc, TRACE_GRAPH_PRINT_PROC) },
 79         /* Display duration of execution */
 80         { TRACER_OPT(funcgraph-duration, TRACE_GRAPH_PRINT_DURATION) },
 81         /* Display absolute time of an entry */
 82         { TRACER_OPT(funcgraph-abstime, TRACE_GRAPH_PRINT_ABS_TIME) },
 83         /* Display interrupts */
 84         { TRACER_OPT(funcgraph-irqs, TRACE_GRAPH_PRINT_IRQS) },
 85         /* Display function name after trailing } */
 86         { TRACER_OPT(funcgraph-tail, TRACE_GRAPH_PRINT_TAIL) },
 87         /* Include sleep time (scheduled out) between entry and return */
 88         { TRACER_OPT(sleep-time, TRACE_GRAPH_SLEEP_TIME) },
 89         /* Include time within nested functions */
 90         { TRACER_OPT(graph-time, TRACE_GRAPH_GRAPH_TIME) },
 91         { } /* Empty entry */
 92 };
 93 
 94 static struct tracer_flags tracer_flags = {
 95         /* Don't display overruns, proc, or tail by default */
 96         .val = TRACE_GRAPH_PRINT_CPU | TRACE_GRAPH_PRINT_OVERHEAD |
 97                TRACE_GRAPH_PRINT_DURATION | TRACE_GRAPH_PRINT_IRQS |
 98                TRACE_GRAPH_SLEEP_TIME | TRACE_GRAPH_GRAPH_TIME,
 99         .opts = trace_opts
100 };
101 
102 static struct trace_array *graph_array;
103 
104 /*
105  * DURATION column is being also used to display IRQ signs,
106  * following values are used by print_graph_irq and others
107  * to fill in space into DURATION column.
108  */
109 enum {
110         FLAGS_FILL_FULL  = 1 << TRACE_GRAPH_PRINT_FILL_SHIFT,
111         FLAGS_FILL_START = 2 << TRACE_GRAPH_PRINT_FILL_SHIFT,
112         FLAGS_FILL_END   = 3 << TRACE_GRAPH_PRINT_FILL_SHIFT,
113 };
114 
115 static void
116 print_graph_duration(struct trace_array *tr, unsigned long long duration,
117                      struct trace_seq *s, u32 flags);
118 
119 /* Add a function return address to the trace stack on thread info.*/
120 int
121 ftrace_push_return_trace(unsigned long ret, unsigned long func, int *depth,
122                          unsigned long frame_pointer)
123 {
124         unsigned long long calltime;
125         int index;
126 
127         if (unlikely(ftrace_graph_is_dead()))
128                 return -EBUSY;
129 
130         if (!current->ret_stack)
131                 return -EBUSY;
132 
133         /*
134          * We must make sure the ret_stack is tested before we read
135          * anything else.
136          */
137         smp_rmb();
138 
139         /* The return trace stack is full */
140         if (current->curr_ret_stack == FTRACE_RETFUNC_DEPTH - 1) {
141                 atomic_inc(&current->trace_overrun);
142                 return -EBUSY;
143         }
144 
145         /*
146          * The curr_ret_stack is an index to ftrace return stack of
147          * current task.  Its value should be in [0, FTRACE_RETFUNC_
148          * DEPTH) when the function graph tracer is used.  To support
149          * filtering out specific functions, it makes the index
150          * negative by subtracting huge value (FTRACE_NOTRACE_DEPTH)
151          * so when it sees a negative index the ftrace will ignore
152          * the record.  And the index gets recovered when returning
153          * from the filtered function by adding the FTRACE_NOTRACE_
154          * DEPTH and then it'll continue to record functions normally.
155          *
156          * The curr_ret_stack is initialized to -1 and get increased
157          * in this function.  So it can be less than -1 only if it was
158          * filtered out via ftrace_graph_notrace_addr() which can be
159          * set from set_graph_notrace file in tracefs by user.
160          */
161         if (current->curr_ret_stack < -1)
162                 return -EBUSY;
163 
164         calltime = trace_clock_local();
165 
166         index = ++current->curr_ret_stack;
167         if (ftrace_graph_notrace_addr(func))
168                 current->curr_ret_stack -= FTRACE_NOTRACE_DEPTH;
169         barrier();
170         current->ret_stack[index].ret = ret;
171         current->ret_stack[index].func = func;
172         current->ret_stack[index].calltime = calltime;
173         current->ret_stack[index].subtime = 0;
174         current->ret_stack[index].fp = frame_pointer;
175         *depth = current->curr_ret_stack;
176 
177         return 0;
178 }
179 
180 /* Retrieve a function return address to the trace stack on thread info.*/
181 static void
182 ftrace_pop_return_trace(struct ftrace_graph_ret *trace, unsigned long *ret,
183                         unsigned long frame_pointer)
184 {
185         int index;
186 
187         index = current->curr_ret_stack;
188 
189         /*
190          * A negative index here means that it's just returned from a
191          * notrace'd function.  Recover index to get an original
192          * return address.  See ftrace_push_return_trace().
193          *
194          * TODO: Need to check whether the stack gets corrupted.
195          */
196         if (index < 0)
197                 index += FTRACE_NOTRACE_DEPTH;
198 
199         if (unlikely(index < 0 || index >= FTRACE_RETFUNC_DEPTH)) {
200                 ftrace_graph_stop();
201                 WARN_ON(1);
202                 /* Might as well panic, otherwise we have no where to go */
203                 *ret = (unsigned long)panic;
204                 return;
205         }
206 
207 #if defined(CONFIG_HAVE_FUNCTION_GRAPH_FP_TEST) && !defined(CC_USING_FENTRY)
208         /*
209          * The arch may choose to record the frame pointer used
210          * and check it here to make sure that it is what we expect it
211          * to be. If gcc does not set the place holder of the return
212          * address in the frame pointer, and does a copy instead, then
213          * the function graph trace will fail. This test detects this
214          * case.
215          *
216          * Currently, x86_32 with optimize for size (-Os) makes the latest
217          * gcc do the above.
218          *
219          * Note, -mfentry does not use frame pointers, and this test
220          *  is not needed if CC_USING_FENTRY is set.
221          */
222         if (unlikely(current->ret_stack[index].fp != frame_pointer)) {
223                 ftrace_graph_stop();
224                 WARN(1, "Bad frame pointer: expected %lx, received %lx\n"
225                      "  from func %ps return to %lx\n",
226                      current->ret_stack[index].fp,
227                      frame_pointer,
228                      (void *)current->ret_stack[index].func,
229                      current->ret_stack[index].ret);
230                 *ret = (unsigned long)panic;
231                 return;
232         }
233 #endif
234 
235         *ret = current->ret_stack[index].ret;
236         trace->func = current->ret_stack[index].func;
237         trace->calltime = current->ret_stack[index].calltime;
238         trace->overrun = atomic_read(&current->trace_overrun);
239         trace->depth = index;
240 }
241 
242 /*
243  * Send the trace to the ring-buffer.
244  * @return the original return address.
245  */
246 unsigned long ftrace_return_to_handler(unsigned long frame_pointer)
247 {
248         struct ftrace_graph_ret trace;
249         unsigned long ret;
250 
251         ftrace_pop_return_trace(&trace, &ret, frame_pointer);
252         trace.rettime = trace_clock_local();
253         barrier();
254         current->curr_ret_stack--;
255         /*
256          * The curr_ret_stack can be less than -1 only if it was
257          * filtered out and it's about to return from the function.
258          * Recover the index and continue to trace normal functions.
259          */
260         if (current->curr_ret_stack < -1) {
261                 current->curr_ret_stack += FTRACE_NOTRACE_DEPTH;
262                 return ret;
263         }
264 
265         /*
266          * The trace should run after decrementing the ret counter
267          * in case an interrupt were to come in. We don't want to
268          * lose the interrupt if max_depth is set.
269          */
270         ftrace_graph_return(&trace);
271 
272         if (unlikely(!ret)) {
273                 ftrace_graph_stop();
274                 WARN_ON(1);
275                 /* Might as well panic. What else to do? */
276                 ret = (unsigned long)panic;
277         }
278 
279         return ret;
280 }
281 
282 int __trace_graph_entry(struct trace_array *tr,
283                                 struct ftrace_graph_ent *trace,
284                                 unsigned long flags,
285                                 int pc)
286 {
287         struct trace_event_call *call = &event_funcgraph_entry;
288         struct ring_buffer_event *event;
289         struct ring_buffer *buffer = tr->trace_buffer.buffer;
290         struct ftrace_graph_ent_entry *entry;
291 
292         event = trace_buffer_lock_reserve(buffer, TRACE_GRAPH_ENT,
293                                           sizeof(*entry), flags, pc);
294         if (!event)
295                 return 0;
296         entry   = ring_buffer_event_data(event);
297         entry->graph_ent                        = *trace;
298         if (!call_filter_check_discard(call, entry, buffer, event))
299                 __buffer_unlock_commit(buffer, event);
300 
301         return 1;
302 }
303 
304 static inline int ftrace_graph_ignore_irqs(void)
305 {
306         if (!ftrace_graph_skip_irqs || trace_recursion_test(TRACE_IRQ_BIT))
307                 return 0;
308 
309         return in_irq();
310 }
311 
312 int trace_graph_entry(struct ftrace_graph_ent *trace)
313 {
314         struct trace_array *tr = graph_array;
315         struct trace_array_cpu *data;
316         unsigned long flags;
317         long disabled;
318         int ret;
319         int cpu;
320         int pc;
321 
322         if (!ftrace_trace_task(current))
323                 return 0;
324 
325         /* trace it when it is-nested-in or is a function enabled. */
326         if ((!(trace->depth || ftrace_graph_addr(trace->func)) ||
327              ftrace_graph_ignore_irqs()) || (trace->depth < 0) ||
328             (max_depth && trace->depth >= max_depth))
329                 return 0;
330 
331         /*
332          * Do not trace a function if it's filtered by set_graph_notrace.
333          * Make the index of ret stack negative to indicate that it should
334          * ignore further functions.  But it needs its own ret stack entry
335          * to recover the original index in order to continue tracing after
336          * returning from the function.
337          */
338         if (ftrace_graph_notrace_addr(trace->func))
339                 return 1;
340 
341         local_irq_save(flags);
342         cpu = raw_smp_processor_id();
343         data = per_cpu_ptr(tr->trace_buffer.data, cpu);
344         disabled = atomic_inc_return(&data->disabled);
345         if (likely(disabled == 1)) {
346                 pc = preempt_count();
347                 ret = __trace_graph_entry(tr, trace, flags, pc);
348         } else {
349                 ret = 0;
350         }
351 
352         atomic_dec(&data->disabled);
353         local_irq_restore(flags);
354 
355         return ret;
356 }
357 
358 static int trace_graph_thresh_entry(struct ftrace_graph_ent *trace)
359 {
360         if (tracing_thresh)
361                 return 1;
362         else
363                 return trace_graph_entry(trace);
364 }
365 
366 static void
367 __trace_graph_function(struct trace_array *tr,
368                 unsigned long ip, unsigned long flags, int pc)
369 {
370         u64 time = trace_clock_local();
371         struct ftrace_graph_ent ent = {
372                 .func  = ip,
373                 .depth = 0,
374         };
375         struct ftrace_graph_ret ret = {
376                 .func     = ip,
377                 .depth    = 0,
378                 .calltime = time,
379                 .rettime  = time,
380         };
381 
382         __trace_graph_entry(tr, &ent, flags, pc);
383         __trace_graph_return(tr, &ret, flags, pc);
384 }
385 
386 void
387 trace_graph_function(struct trace_array *tr,
388                 unsigned long ip, unsigned long parent_ip,
389                 unsigned long flags, int pc)
390 {
391         __trace_graph_function(tr, ip, flags, pc);
392 }
393 
394 void __trace_graph_return(struct trace_array *tr,
395                                 struct ftrace_graph_ret *trace,
396                                 unsigned long flags,
397                                 int pc)
398 {
399         struct trace_event_call *call = &event_funcgraph_exit;
400         struct ring_buffer_event *event;
401         struct ring_buffer *buffer = tr->trace_buffer.buffer;
402         struct ftrace_graph_ret_entry *entry;
403 
404         event = trace_buffer_lock_reserve(buffer, TRACE_GRAPH_RET,
405                                           sizeof(*entry), flags, pc);
406         if (!event)
407                 return;
408         entry   = ring_buffer_event_data(event);
409         entry->ret                              = *trace;
410         if (!call_filter_check_discard(call, entry, buffer, event))
411                 __buffer_unlock_commit(buffer, event);
412 }
413 
414 void trace_graph_return(struct ftrace_graph_ret *trace)
415 {
416         struct trace_array *tr = graph_array;
417         struct trace_array_cpu *data;
418         unsigned long flags;
419         long disabled;
420         int cpu;
421         int pc;
422 
423         local_irq_save(flags);
424         cpu = raw_smp_processor_id();
425         data = per_cpu_ptr(tr->trace_buffer.data, cpu);
426         disabled = atomic_inc_return(&data->disabled);
427         if (likely(disabled == 1)) {
428                 pc = preempt_count();
429                 __trace_graph_return(tr, trace, flags, pc);
430         }
431         atomic_dec(&data->disabled);
432         local_irq_restore(flags);
433 }
434 
435 void set_graph_array(struct trace_array *tr)
436 {
437         graph_array = tr;
438 
439         /* Make graph_array visible before we start tracing */
440 
441         smp_mb();
442 }
443 
444 static void trace_graph_thresh_return(struct ftrace_graph_ret *trace)
445 {
446         if (tracing_thresh &&
447             (trace->rettime - trace->calltime < tracing_thresh))
448                 return;
449         else
450                 trace_graph_return(trace);
451 }
452 
453 static int graph_trace_init(struct trace_array *tr)
454 {
455         int ret;
456 
457         set_graph_array(tr);
458         if (tracing_thresh)
459                 ret = register_ftrace_graph(&trace_graph_thresh_return,
460                                             &trace_graph_thresh_entry);
461         else
462                 ret = register_ftrace_graph(&trace_graph_return,
463                                             &trace_graph_entry);
464         if (ret)
465                 return ret;
466         tracing_start_cmdline_record();
467 
468         return 0;
469 }
470 
471 static void graph_trace_reset(struct trace_array *tr)
472 {
473         tracing_stop_cmdline_record();
474         unregister_ftrace_graph();
475 }
476 
477 static int graph_trace_update_thresh(struct trace_array *tr)
478 {
479         graph_trace_reset(tr);
480         return graph_trace_init(tr);
481 }
482 
483 static int max_bytes_for_cpu;
484 
485 static void print_graph_cpu(struct trace_seq *s, int cpu)
486 {
487         /*
488          * Start with a space character - to make it stand out
489          * to the right a bit when trace output is pasted into
490          * email:
491          */
492         trace_seq_printf(s, " %*d) ", max_bytes_for_cpu, cpu);
493 }
494 
495 #define TRACE_GRAPH_PROCINFO_LENGTH     14
496 
497 static void print_graph_proc(struct trace_seq *s, pid_t pid)
498 {
499         char comm[TASK_COMM_LEN];
500         /* sign + log10(MAX_INT) + '\0' */
501         char pid_str[11];
502         int spaces = 0;
503         int len;
504         int i;
505 
506         trace_find_cmdline(pid, comm);
507         comm[7] = '\0';
508         sprintf(pid_str, "%d", pid);
509 
510         /* 1 stands for the "-" character */
511         len = strlen(comm) + strlen(pid_str) + 1;
512 
513         if (len < TRACE_GRAPH_PROCINFO_LENGTH)
514                 spaces = TRACE_GRAPH_PROCINFO_LENGTH - len;
515 
516         /* First spaces to align center */
517         for (i = 0; i < spaces / 2; i++)
518                 trace_seq_putc(s, ' ');
519 
520         trace_seq_printf(s, "%s-%s", comm, pid_str);
521 
522         /* Last spaces to align center */
523         for (i = 0; i < spaces - (spaces / 2); i++)
524                 trace_seq_putc(s, ' ');
525 }
526 
527 
528 static void print_graph_lat_fmt(struct trace_seq *s, struct trace_entry *entry)
529 {
530         trace_seq_putc(s, ' ');
531         trace_print_lat_fmt(s, entry);
532 }
533 
534 /* If the pid changed since the last trace, output this event */
535 static void
536 verif_pid(struct trace_seq *s, pid_t pid, int cpu, struct fgraph_data *data)
537 {
538         pid_t prev_pid;
539         pid_t *last_pid;
540 
541         if (!data)
542                 return;
543 
544         last_pid = &(per_cpu_ptr(data->cpu_data, cpu)->last_pid);
545 
546         if (*last_pid == pid)
547                 return;
548 
549         prev_pid = *last_pid;
550         *last_pid = pid;
551 
552         if (prev_pid == -1)
553                 return;
554 /*
555  * Context-switch trace line:
556 
557  ------------------------------------------
558  | 1)  migration/0--1  =>  sshd-1755
559  ------------------------------------------
560 
561  */
562         trace_seq_puts(s, " ------------------------------------------\n");
563         print_graph_cpu(s, cpu);
564         print_graph_proc(s, prev_pid);
565         trace_seq_puts(s, " => ");
566         print_graph_proc(s, pid);
567         trace_seq_puts(s, "\n ------------------------------------------\n\n");
568 }
569 
570 static struct ftrace_graph_ret_entry *
571 get_return_for_leaf(struct trace_iterator *iter,
572                 struct ftrace_graph_ent_entry *curr)
573 {
574         struct fgraph_data *data = iter->private;
575         struct ring_buffer_iter *ring_iter = NULL;
576         struct ring_buffer_event *event;
577         struct ftrace_graph_ret_entry *next;
578 
579         /*
580          * If the previous output failed to write to the seq buffer,
581          * then we just reuse the data from before.
582          */
583         if (data && data->failed) {
584                 curr = &data->ent;
585                 next = &data->ret;
586         } else {
587 
588                 ring_iter = trace_buffer_iter(iter, iter->cpu);
589 
590                 /* First peek to compare current entry and the next one */
591                 if (ring_iter)
592                         event = ring_buffer_iter_peek(ring_iter, NULL);
593                 else {
594                         /*
595                          * We need to consume the current entry to see
596                          * the next one.
597                          */
598                         ring_buffer_consume(iter->trace_buffer->buffer, iter->cpu,
599                                             NULL, NULL);
600                         event = ring_buffer_peek(iter->trace_buffer->buffer, iter->cpu,
601                                                  NULL, NULL);
602                 }
603 
604                 if (!event)
605                         return NULL;
606 
607                 next = ring_buffer_event_data(event);
608 
609                 if (data) {
610                         /*
611                          * Save current and next entries for later reference
612                          * if the output fails.
613                          */
614                         data->ent = *curr;
615                         /*
616                          * If the next event is not a return type, then
617                          * we only care about what type it is. Otherwise we can
618                          * safely copy the entire event.
619                          */
620                         if (next->ent.type == TRACE_GRAPH_RET)
621                                 data->ret = *next;
622                         else
623                                 data->ret.ent.type = next->ent.type;
624                 }
625         }
626 
627         if (next->ent.type != TRACE_GRAPH_RET)
628                 return NULL;
629 
630         if (curr->ent.pid != next->ent.pid ||
631                         curr->graph_ent.func != next->ret.func)
632                 return NULL;
633 
634         /* this is a leaf, now advance the iterator */
635         if (ring_iter)
636                 ring_buffer_read(ring_iter, NULL);
637 
638         return next;
639 }
640 
641 static void print_graph_abs_time(u64 t, struct trace_seq *s)
642 {
643         unsigned long usecs_rem;
644 
645         usecs_rem = do_div(t, NSEC_PER_SEC);
646         usecs_rem /= 1000;
647 
648         trace_seq_printf(s, "%5lu.%06lu |  ",
649                          (unsigned long)t, usecs_rem);
650 }
651 
652 static void
653 print_graph_irq(struct trace_iterator *iter, unsigned long addr,
654                 enum trace_type type, int cpu, pid_t pid, u32 flags)
655 {
656         struct trace_array *tr = iter->tr;
657         struct trace_seq *s = &iter->seq;
658         struct trace_entry *ent = iter->ent;
659 
660         if (addr < (unsigned long)__irqentry_text_start ||
661                 addr >= (unsigned long)__irqentry_text_end)
662                 return;
663 
664         if (tr->trace_flags & TRACE_ITER_CONTEXT_INFO) {
665                 /* Absolute time */
666                 if (flags & TRACE_GRAPH_PRINT_ABS_TIME)
667                         print_graph_abs_time(iter->ts, s);
668 
669                 /* Cpu */
670                 if (flags & TRACE_GRAPH_PRINT_CPU)
671                         print_graph_cpu(s, cpu);
672 
673                 /* Proc */
674                 if (flags & TRACE_GRAPH_PRINT_PROC) {
675                         print_graph_proc(s, pid);
676                         trace_seq_puts(s, " | ");
677                 }
678 
679                 /* Latency format */
680                 if (tr->trace_flags & TRACE_ITER_LATENCY_FMT)
681                         print_graph_lat_fmt(s, ent);
682         }
683 
684         /* No overhead */
685         print_graph_duration(tr, 0, s, flags | FLAGS_FILL_START);
686 
687         if (type == TRACE_GRAPH_ENT)
688                 trace_seq_puts(s, "==========>");
689         else
690                 trace_seq_puts(s, "<==========");
691 
692         print_graph_duration(tr, 0, s, flags | FLAGS_FILL_END);
693         trace_seq_putc(s, '\n');
694 }
695 
696 void
697 trace_print_graph_duration(unsigned long long duration, struct trace_seq *s)
698 {
699         unsigned long nsecs_rem = do_div(duration, 1000);
700         /* log10(ULONG_MAX) + '\0' */
701         char usecs_str[21];
702         char nsecs_str[5];
703         int len;
704         int i;
705 
706         sprintf(usecs_str, "%lu", (unsigned long) duration);
707 
708         /* Print msecs */
709         trace_seq_printf(s, "%s", usecs_str);
710 
711         len = strlen(usecs_str);
712 
713         /* Print nsecs (we don't want to exceed 7 numbers) */
714         if (len < 7) {
715                 size_t slen = min_t(size_t, sizeof(nsecs_str), 8UL - len);
716 
717                 snprintf(nsecs_str, slen, "%03lu", nsecs_rem);
718                 trace_seq_printf(s, ".%s", nsecs_str);
719                 len += strlen(nsecs_str) + 1;
720         }
721 
722         trace_seq_puts(s, " us ");
723 
724         /* Print remaining spaces to fit the row's width */
725         for (i = len; i < 8; i++)
726                 trace_seq_putc(s, ' ');
727 }
728 
729 static void
730 print_graph_duration(struct trace_array *tr, unsigned long long duration,
731                      struct trace_seq *s, u32 flags)
732 {
733         if (!(flags & TRACE_GRAPH_PRINT_DURATION) ||
734             !(tr->trace_flags & TRACE_ITER_CONTEXT_INFO))
735                 return;
736 
737         /* No real adata, just filling the column with spaces */
738         switch (flags & TRACE_GRAPH_PRINT_FILL_MASK) {
739         case FLAGS_FILL_FULL:
740                 trace_seq_puts(s, "              |  ");
741                 return;
742         case FLAGS_FILL_START:
743                 trace_seq_puts(s, "  ");
744                 return;
745         case FLAGS_FILL_END:
746                 trace_seq_puts(s, " |");
747                 return;
748         }
749 
750         /* Signal a overhead of time execution to the output */
751         if (flags & TRACE_GRAPH_PRINT_OVERHEAD)
752                 trace_seq_printf(s, "%c ", trace_find_mark(duration));
753         else
754                 trace_seq_puts(s, "  ");
755 
756         trace_print_graph_duration(duration, s);
757         trace_seq_puts(s, "|  ");
758 }
759 
760 /* Case of a leaf function on its call entry */
761 static enum print_line_t
762 print_graph_entry_leaf(struct trace_iterator *iter,
763                 struct ftrace_graph_ent_entry *entry,
764                 struct ftrace_graph_ret_entry *ret_entry,
765                 struct trace_seq *s, u32 flags)
766 {
767         struct fgraph_data *data = iter->private;
768         struct trace_array *tr = iter->tr;
769         struct ftrace_graph_ret *graph_ret;
770         struct ftrace_graph_ent *call;
771         unsigned long long duration;
772         int i;
773 
774         graph_ret = &ret_entry->ret;
775         call = &entry->graph_ent;
776         duration = graph_ret->rettime - graph_ret->calltime;
777 
778         if (data) {
779                 struct fgraph_cpu_data *cpu_data;
780                 int cpu = iter->cpu;
781 
782                 cpu_data = per_cpu_ptr(data->cpu_data, cpu);
783 
784                 /*
785                  * Comments display at + 1 to depth. Since
786                  * this is a leaf function, keep the comments
787                  * equal to this depth.
788                  */
789                 cpu_data->depth = call->depth - 1;
790 
791                 /* No need to keep this function around for this depth */
792                 if (call->depth < FTRACE_RETFUNC_DEPTH)
793                         cpu_data->enter_funcs[call->depth] = 0;
794         }
795 
796         /* Overhead and duration */
797         print_graph_duration(tr, duration, s, flags);
798 
799         /* Function */
800         for (i = 0; i < call->depth * TRACE_GRAPH_INDENT; i++)
801                 trace_seq_putc(s, ' ');
802 
803         trace_seq_printf(s, "%ps();\n", (void *)call->func);
804 
805         return trace_handle_return(s);
806 }
807 
808 static enum print_line_t
809 print_graph_entry_nested(struct trace_iterator *iter,
810                          struct ftrace_graph_ent_entry *entry,
811                          struct trace_seq *s, int cpu, u32 flags)
812 {
813         struct ftrace_graph_ent *call = &entry->graph_ent;
814         struct fgraph_data *data = iter->private;
815         struct trace_array *tr = iter->tr;
816         int i;
817 
818         if (data) {
819                 struct fgraph_cpu_data *cpu_data;
820                 int cpu = iter->cpu;
821 
822                 cpu_data = per_cpu_ptr(data->cpu_data, cpu);
823                 cpu_data->depth = call->depth;
824 
825                 /* Save this function pointer to see if the exit matches */
826                 if (call->depth < FTRACE_RETFUNC_DEPTH)
827                         cpu_data->enter_funcs[call->depth] = call->func;
828         }
829 
830         /* No time */
831         print_graph_duration(tr, 0, s, flags | FLAGS_FILL_FULL);
832 
833         /* Function */
834         for (i = 0; i < call->depth * TRACE_GRAPH_INDENT; i++)
835                 trace_seq_putc(s, ' ');
836 
837         trace_seq_printf(s, "%ps() {\n", (void *)call->func);
838 
839         if (trace_seq_has_overflowed(s))
840                 return TRACE_TYPE_PARTIAL_LINE;
841 
842         /*
843          * we already consumed the current entry to check the next one
844          * and see if this is a leaf.
845          */
846         return TRACE_TYPE_NO_CONSUME;
847 }
848 
849 static void
850 print_graph_prologue(struct trace_iterator *iter, struct trace_seq *s,
851                      int type, unsigned long addr, u32 flags)
852 {
853         struct fgraph_data *data = iter->private;
854         struct trace_entry *ent = iter->ent;
855         struct trace_array *tr = iter->tr;
856         int cpu = iter->cpu;
857 
858         /* Pid */
859         verif_pid(s, ent->pid, cpu, data);
860 
861         if (type)
862                 /* Interrupt */
863                 print_graph_irq(iter, addr, type, cpu, ent->pid, flags);
864 
865         if (!(tr->trace_flags & TRACE_ITER_CONTEXT_INFO))
866                 return;
867 
868         /* Absolute time */
869         if (flags & TRACE_GRAPH_PRINT_ABS_TIME)
870                 print_graph_abs_time(iter->ts, s);
871 
872         /* Cpu */
873         if (flags & TRACE_GRAPH_PRINT_CPU)
874                 print_graph_cpu(s, cpu);
875 
876         /* Proc */
877         if (flags & TRACE_GRAPH_PRINT_PROC) {
878                 print_graph_proc(s, ent->pid);
879                 trace_seq_puts(s, " | ");
880         }
881 
882         /* Latency format */
883         if (tr->trace_flags & TRACE_ITER_LATENCY_FMT)
884                 print_graph_lat_fmt(s, ent);
885 
886         return;
887 }
888 
889 /*
890  * Entry check for irq code
891  *
892  * returns 1 if
893  *  - we are inside irq code
894  *  - we just entered irq code
895  *
896  * retunns 0 if
897  *  - funcgraph-interrupts option is set
898  *  - we are not inside irq code
899  */
900 static int
901 check_irq_entry(struct trace_iterator *iter, u32 flags,
902                 unsigned long addr, int depth)
903 {
904         int cpu = iter->cpu;
905         int *depth_irq;
906         struct fgraph_data *data = iter->private;
907 
908         /*
909          * If we are either displaying irqs, or we got called as
910          * a graph event and private data does not exist,
911          * then we bypass the irq check.
912          */
913         if ((flags & TRACE_GRAPH_PRINT_IRQS) ||
914             (!data))
915                 return 0;
916 
917         depth_irq = &(per_cpu_ptr(data->cpu_data, cpu)->depth_irq);
918 
919         /*
920          * We are inside the irq code
921          */
922         if (*depth_irq >= 0)
923                 return 1;
924 
925         if ((addr < (unsigned long)__irqentry_text_start) ||
926             (addr >= (unsigned long)__irqentry_text_end))
927                 return 0;
928 
929         /*
930          * We are entering irq code.
931          */
932         *depth_irq = depth;
933         return 1;
934 }
935 
936 /*
937  * Return check for irq code
938  *
939  * returns 1 if
940  *  - we are inside irq code
941  *  - we just left irq code
942  *
943  * returns 0 if
944  *  - funcgraph-interrupts option is set
945  *  - we are not inside irq code
946  */
947 static int
948 check_irq_return(struct trace_iterator *iter, u32 flags, int depth)
949 {
950         int cpu = iter->cpu;
951         int *depth_irq;
952         struct fgraph_data *data = iter->private;
953 
954         /*
955          * If we are either displaying irqs, or we got called as
956          * a graph event and private data does not exist,
957          * then we bypass the irq check.
958          */
959         if ((flags & TRACE_GRAPH_PRINT_IRQS) ||
960             (!data))
961                 return 0;
962 
963         depth_irq = &(per_cpu_ptr(data->cpu_data, cpu)->depth_irq);
964 
965         /*
966          * We are not inside the irq code.
967          */
968         if (*depth_irq == -1)
969                 return 0;
970 
971         /*
972          * We are inside the irq code, and this is returning entry.
973          * Let's not trace it and clear the entry depth, since
974          * we are out of irq code.
975          *
976          * This condition ensures that we 'leave the irq code' once
977          * we are out of the entry depth. Thus protecting us from
978          * the RETURN entry loss.
979          */
980         if (*depth_irq >= depth) {
981                 *depth_irq = -1;
982                 return 1;
983         }
984 
985         /*
986          * We are inside the irq code, and this is not the entry.
987          */
988         return 1;
989 }
990 
991 static enum print_line_t
992 print_graph_entry(struct ftrace_graph_ent_entry *field, struct trace_seq *s,
993                         struct trace_iterator *iter, u32 flags)
994 {
995         struct fgraph_data *data = iter->private;
996         struct ftrace_graph_ent *call = &field->graph_ent;
997         struct ftrace_graph_ret_entry *leaf_ret;
998         static enum print_line_t ret;
999         int cpu = iter->cpu;
1000 
1001         if (check_irq_entry(iter, flags, call->func, call->depth))
1002                 return TRACE_TYPE_HANDLED;
1003 
1004         print_graph_prologue(iter, s, TRACE_GRAPH_ENT, call->func, flags);
1005 
1006         leaf_ret = get_return_for_leaf(iter, field);
1007         if (leaf_ret)
1008                 ret = print_graph_entry_leaf(iter, field, leaf_ret, s, flags);
1009         else
1010                 ret = print_graph_entry_nested(iter, field, s, cpu, flags);
1011 
1012         if (data) {
1013                 /*
1014                  * If we failed to write our output, then we need to make
1015                  * note of it. Because we already consumed our entry.
1016                  */
1017                 if (s->full) {
1018                         data->failed = 1;
1019                         data->cpu = cpu;
1020                 } else
1021                         data->failed = 0;
1022         }
1023 
1024         return ret;
1025 }
1026 
1027 static enum print_line_t
1028 print_graph_return(struct ftrace_graph_ret *trace, struct trace_seq *s,
1029                    struct trace_entry *ent, struct trace_iterator *iter,
1030                    u32 flags)
1031 {
1032         unsigned long long duration = trace->rettime - trace->calltime;
1033         struct fgraph_data *data = iter->private;
1034         struct trace_array *tr = iter->tr;
1035         pid_t pid = ent->pid;
1036         int cpu = iter->cpu;
1037         int func_match = 1;
1038         int i;
1039 
1040         if (check_irq_return(iter, flags, trace->depth))
1041                 return TRACE_TYPE_HANDLED;
1042 
1043         if (data) {
1044                 struct fgraph_cpu_data *cpu_data;
1045                 int cpu = iter->cpu;
1046 
1047                 cpu_data = per_cpu_ptr(data->cpu_data, cpu);
1048 
1049                 /*
1050                  * Comments display at + 1 to depth. This is the
1051                  * return from a function, we now want the comments
1052                  * to display at the same level of the bracket.
1053                  */
1054                 cpu_data->depth = trace->depth - 1;
1055 
1056                 if (trace->depth < FTRACE_RETFUNC_DEPTH) {
1057                         if (cpu_data->enter_funcs[trace->depth] != trace->func)
1058                                 func_match = 0;
1059                         cpu_data->enter_funcs[trace->depth] = 0;
1060                 }
1061         }
1062 
1063         print_graph_prologue(iter, s, 0, 0, flags);
1064 
1065         /* Overhead and duration */
1066         print_graph_duration(tr, duration, s, flags);
1067 
1068         /* Closing brace */
1069         for (i = 0; i < trace->depth * TRACE_GRAPH_INDENT; i++)
1070                 trace_seq_putc(s, ' ');
1071 
1072         /*
1073          * If the return function does not have a matching entry,
1074          * then the entry was lost. Instead of just printing
1075          * the '}' and letting the user guess what function this
1076          * belongs to, write out the function name. Always do
1077          * that if the funcgraph-tail option is enabled.
1078          */
1079         if (func_match && !(flags & TRACE_GRAPH_PRINT_TAIL))
1080                 trace_seq_puts(s, "}\n");
1081         else
1082                 trace_seq_printf(s, "} /* %ps */\n", (void *)trace->func);
1083 
1084         /* Overrun */
1085         if (flags & TRACE_GRAPH_PRINT_OVERRUN)
1086                 trace_seq_printf(s, " (Overruns: %lu)\n",
1087                                  trace->overrun);
1088 
1089         print_graph_irq(iter, trace->func, TRACE_GRAPH_RET,
1090                         cpu, pid, flags);
1091 
1092         return trace_handle_return(s);
1093 }
1094 
1095 static enum print_line_t
1096 print_graph_comment(struct trace_seq *s, struct trace_entry *ent,
1097                     struct trace_iterator *iter, u32 flags)
1098 {
1099         struct trace_array *tr = iter->tr;
1100         unsigned long sym_flags = (tr->trace_flags & TRACE_ITER_SYM_MASK);
1101         struct fgraph_data *data = iter->private;
1102         struct trace_event *event;
1103         int depth = 0;
1104         int ret;
1105         int i;
1106 
1107         if (data)
1108                 depth = per_cpu_ptr(data->cpu_data, iter->cpu)->depth;
1109 
1110         print_graph_prologue(iter, s, 0, 0, flags);
1111 
1112         /* No time */
1113         print_graph_duration(tr, 0, s, flags | FLAGS_FILL_FULL);
1114 
1115         /* Indentation */
1116         if (depth > 0)
1117                 for (i = 0; i < (depth + 1) * TRACE_GRAPH_INDENT; i++)
1118                         trace_seq_putc(s, ' ');
1119 
1120         /* The comment */
1121         trace_seq_puts(s, "/* ");
1122 
1123         switch (iter->ent->type) {
1124         case TRACE_BPRINT:
1125                 ret = trace_print_bprintk_msg_only(iter);
1126                 if (ret != TRACE_TYPE_HANDLED)
1127                         return ret;
1128                 break;
1129         case TRACE_PRINT:
1130                 ret = trace_print_printk_msg_only(iter);
1131                 if (ret != TRACE_TYPE_HANDLED)
1132                         return ret;
1133                 break;
1134         default:
1135                 event = ftrace_find_event(ent->type);
1136                 if (!event)
1137                         return TRACE_TYPE_UNHANDLED;
1138 
1139                 ret = event->funcs->trace(iter, sym_flags, event);
1140                 if (ret != TRACE_TYPE_HANDLED)
1141                         return ret;
1142         }
1143 
1144         if (trace_seq_has_overflowed(s))
1145                 goto out;
1146 
1147         /* Strip ending newline */
1148         if (s->buffer[s->seq.len - 1] == '\n') {
1149                 s->buffer[s->seq.len - 1] = '\0';
1150                 s->seq.len--;
1151         }
1152 
1153         trace_seq_puts(s, " */\n");
1154  out:
1155         return trace_handle_return(s);
1156 }
1157 
1158 
1159 enum print_line_t
1160 print_graph_function_flags(struct trace_iterator *iter, u32 flags)
1161 {
1162         struct ftrace_graph_ent_entry *field;
1163         struct fgraph_data *data = iter->private;
1164         struct trace_entry *entry = iter->ent;
1165         struct trace_seq *s = &iter->seq;
1166         int cpu = iter->cpu;
1167         int ret;
1168 
1169         if (data && per_cpu_ptr(data->cpu_data, cpu)->ignore) {
1170                 per_cpu_ptr(data->cpu_data, cpu)->ignore = 0;
1171                 return TRACE_TYPE_HANDLED;
1172         }
1173 
1174         /*
1175          * If the last output failed, there's a possibility we need
1176          * to print out the missing entry which would never go out.
1177          */
1178         if (data && data->failed) {
1179                 field = &data->ent;
1180                 iter->cpu = data->cpu;
1181                 ret = print_graph_entry(field, s, iter, flags);
1182                 if (ret == TRACE_TYPE_HANDLED && iter->cpu != cpu) {
1183                         per_cpu_ptr(data->cpu_data, iter->cpu)->ignore = 1;
1184                         ret = TRACE_TYPE_NO_CONSUME;
1185                 }
1186                 iter->cpu = cpu;
1187                 return ret;
1188         }
1189 
1190         switch (entry->type) {
1191         case TRACE_GRAPH_ENT: {
1192                 /*
1193                  * print_graph_entry() may consume the current event,
1194                  * thus @field may become invalid, so we need to save it.
1195                  * sizeof(struct ftrace_graph_ent_entry) is very small,
1196                  * it can be safely saved at the stack.
1197                  */
1198                 struct ftrace_graph_ent_entry saved;
1199                 trace_assign_type(field, entry);
1200                 saved = *field;
1201                 return print_graph_entry(&saved, s, iter, flags);
1202         }
1203         case TRACE_GRAPH_RET: {
1204                 struct ftrace_graph_ret_entry *field;
1205                 trace_assign_type(field, entry);
1206                 return print_graph_return(&field->ret, s, entry, iter, flags);
1207         }
1208         case TRACE_STACK:
1209         case TRACE_FN:
1210                 /* dont trace stack and functions as comments */
1211                 return TRACE_TYPE_UNHANDLED;
1212 
1213         default:
1214                 return print_graph_comment(s, entry, iter, flags);
1215         }
1216 
1217         return TRACE_TYPE_HANDLED;
1218 }
1219 
1220 static enum print_line_t
1221 print_graph_function(struct trace_iterator *iter)
1222 {
1223         return print_graph_function_flags(iter, tracer_flags.val);
1224 }
1225 
1226 static enum print_line_t
1227 print_graph_function_event(struct trace_iterator *iter, int flags,
1228                            struct trace_event *event)
1229 {
1230         return print_graph_function(iter);
1231 }
1232 
1233 static void print_lat_header(struct seq_file *s, u32 flags)
1234 {
1235         static const char spaces[] = "                " /* 16 spaces */
1236                 "    "                                  /* 4 spaces */
1237                 "                 ";                    /* 17 spaces */
1238         int size = 0;
1239 
1240         if (flags & TRACE_GRAPH_PRINT_ABS_TIME)
1241                 size += 16;
1242         if (flags & TRACE_GRAPH_PRINT_CPU)
1243                 size += 4;
1244         if (flags & TRACE_GRAPH_PRINT_PROC)
1245                 size += 17;
1246 
1247         seq_printf(s, "#%.*s  _-----=> irqs-off        \n", size, spaces);
1248         seq_printf(s, "#%.*s / _----=> need-resched    \n", size, spaces);
1249         seq_printf(s, "#%.*s| / _---=> hardirq/softirq \n", size, spaces);
1250         seq_printf(s, "#%.*s|| / _--=> preempt-depth   \n", size, spaces);
1251         seq_printf(s, "#%.*s||| /                      \n", size, spaces);
1252 }
1253 
1254 static void __print_graph_headers_flags(struct trace_array *tr,
1255                                         struct seq_file *s, u32 flags)
1256 {
1257         int lat = tr->trace_flags & TRACE_ITER_LATENCY_FMT;
1258 
1259         if (lat)
1260                 print_lat_header(s, flags);
1261 
1262         /* 1st line */
1263         seq_putc(s, '#');
1264         if (flags & TRACE_GRAPH_PRINT_ABS_TIME)
1265                 seq_puts(s, "     TIME       ");
1266         if (flags & TRACE_GRAPH_PRINT_CPU)
1267                 seq_puts(s, " CPU");
1268         if (flags & TRACE_GRAPH_PRINT_PROC)
1269                 seq_puts(s, "  TASK/PID       ");
1270         if (lat)
1271                 seq_puts(s, "||||");
1272         if (flags & TRACE_GRAPH_PRINT_DURATION)
1273                 seq_puts(s, "  DURATION   ");
1274         seq_puts(s, "               FUNCTION CALLS\n");
1275 
1276         /* 2nd line */
1277         seq_putc(s, '#');
1278         if (flags & TRACE_GRAPH_PRINT_ABS_TIME)
1279                 seq_puts(s, "      |         ");
1280         if (flags & TRACE_GRAPH_PRINT_CPU)
1281                 seq_puts(s, " |  ");
1282         if (flags & TRACE_GRAPH_PRINT_PROC)
1283                 seq_puts(s, "   |    |        ");
1284         if (lat)
1285                 seq_puts(s, "||||");
1286         if (flags & TRACE_GRAPH_PRINT_DURATION)
1287                 seq_puts(s, "   |   |      ");
1288         seq_puts(s, "               |   |   |   |\n");
1289 }
1290 
1291 static void print_graph_headers(struct seq_file *s)
1292 {
1293         print_graph_headers_flags(s, tracer_flags.val);
1294 }
1295 
1296 void print_graph_headers_flags(struct seq_file *s, u32 flags)
1297 {
1298         struct trace_iterator *iter = s->private;
1299         struct trace_array *tr = iter->tr;
1300 
1301         if (!(tr->trace_flags & TRACE_ITER_CONTEXT_INFO))
1302                 return;
1303 
1304         if (tr->trace_flags & TRACE_ITER_LATENCY_FMT) {
1305                 /* print nothing if the buffers are empty */
1306                 if (trace_empty(iter))
1307                         return;
1308 
1309                 print_trace_header(s, iter);
1310         }
1311 
1312         __print_graph_headers_flags(tr, s, flags);
1313 }
1314 
1315 void graph_trace_open(struct trace_iterator *iter)
1316 {
1317         /* pid and depth on the last trace processed */
1318         struct fgraph_data *data;
1319         gfp_t gfpflags;
1320         int cpu;
1321 
1322         iter->private = NULL;
1323 
1324         /* We can be called in atomic context via ftrace_dump() */
1325         gfpflags = (in_atomic() || irqs_disabled()) ? GFP_ATOMIC : GFP_KERNEL;
1326 
1327         data = kzalloc(sizeof(*data), gfpflags);
1328         if (!data)
1329                 goto out_err;
1330 
1331         data->cpu_data = alloc_percpu_gfp(struct fgraph_cpu_data, gfpflags);
1332         if (!data->cpu_data)
1333                 goto out_err_free;
1334 
1335         for_each_possible_cpu(cpu) {
1336                 pid_t *pid = &(per_cpu_ptr(data->cpu_data, cpu)->last_pid);
1337                 int *depth = &(per_cpu_ptr(data->cpu_data, cpu)->depth);
1338                 int *ignore = &(per_cpu_ptr(data->cpu_data, cpu)->ignore);
1339                 int *depth_irq = &(per_cpu_ptr(data->cpu_data, cpu)->depth_irq);
1340 
1341                 *pid = -1;
1342                 *depth = 0;
1343                 *ignore = 0;
1344                 *depth_irq = -1;
1345         }
1346 
1347         iter->private = data;
1348 
1349         return;
1350 
1351  out_err_free:
1352         kfree(data);
1353  out_err:
1354         pr_warn("function graph tracer: not enough memory\n");
1355 }
1356 
1357 void graph_trace_close(struct trace_iterator *iter)
1358 {
1359         struct fgraph_data *data = iter->private;
1360 
1361         if (data) {
1362                 free_percpu(data->cpu_data);
1363                 kfree(data);
1364         }
1365 }
1366 
1367 static int
1368 func_graph_set_flag(struct trace_array *tr, u32 old_flags, u32 bit, int set)
1369 {
1370         if (bit == TRACE_GRAPH_PRINT_IRQS)
1371                 ftrace_graph_skip_irqs = !set;
1372 
1373         if (bit == TRACE_GRAPH_SLEEP_TIME)
1374                 ftrace_graph_sleep_time_control(set);
1375 
1376         if (bit == TRACE_GRAPH_GRAPH_TIME)
1377                 ftrace_graph_graph_time_control(set);
1378 
1379         return 0;
1380 }
1381 
1382 static struct trace_event_functions graph_functions = {
1383         .trace          = print_graph_function_event,
1384 };
1385 
1386 static struct trace_event graph_trace_entry_event = {
1387         .type           = TRACE_GRAPH_ENT,
1388         .funcs          = &graph_functions,
1389 };
1390 
1391 static struct trace_event graph_trace_ret_event = {
1392         .type           = TRACE_GRAPH_RET,
1393         .funcs          = &graph_functions
1394 };
1395 
1396 static struct tracer graph_trace __tracer_data = {
1397         .name           = "function_graph",
1398         .update_thresh  = graph_trace_update_thresh,
1399         .open           = graph_trace_open,
1400         .pipe_open      = graph_trace_open,
1401         .close          = graph_trace_close,
1402         .pipe_close     = graph_trace_close,
1403         .init           = graph_trace_init,
1404         .reset          = graph_trace_reset,
1405         .print_line     = print_graph_function,
1406         .print_header   = print_graph_headers,
1407         .flags          = &tracer_flags,
1408         .set_flag       = func_graph_set_flag,
1409 #ifdef CONFIG_FTRACE_SELFTEST
1410         .selftest       = trace_selftest_startup_function_graph,
1411 #endif
1412 };
1413 
1414 
1415 static ssize_t
1416 graph_depth_write(struct file *filp, const char __user *ubuf, size_t cnt,
1417                   loff_t *ppos)
1418 {
1419         unsigned long val;
1420         int ret;
1421 
1422         ret = kstrtoul_from_user(ubuf, cnt, 10, &val);
1423         if (ret)
1424                 return ret;
1425 
1426         max_depth = val;
1427 
1428         *ppos += cnt;
1429 
1430         return cnt;
1431 }
1432 
1433 static ssize_t
1434 graph_depth_read(struct file *filp, char __user *ubuf, size_t cnt,
1435                  loff_t *ppos)
1436 {
1437         char buf[15]; /* More than enough to hold UINT_MAX + "\n"*/
1438         int n;
1439 
1440         n = sprintf(buf, "%d\n", max_depth);
1441 
1442         return simple_read_from_buffer(ubuf, cnt, ppos, buf, n);
1443 }
1444 
1445 static const struct file_operations graph_depth_fops = {
1446         .open           = tracing_open_generic,
1447         .write          = graph_depth_write,
1448         .read           = graph_depth_read,
1449         .llseek         = generic_file_llseek,
1450 };
1451 
1452 static __init int init_graph_tracefs(void)
1453 {
1454         struct dentry *d_tracer;
1455 
1456         d_tracer = tracing_init_dentry();
1457         if (IS_ERR(d_tracer))
1458                 return 0;
1459 
1460         trace_create_file("max_graph_depth", 0644, d_tracer,
1461                           NULL, &graph_depth_fops);
1462 
1463         return 0;
1464 }
1465 fs_initcall(init_graph_tracefs);
1466 
1467 static __init int init_graph_trace(void)
1468 {
1469         max_bytes_for_cpu = snprintf(NULL, 0, "%d", nr_cpu_ids - 1);
1470 
1471         if (!register_trace_event(&graph_trace_entry_event)) {
1472                 pr_warn("Warning: could not register graph trace events\n");
1473                 return 1;
1474         }
1475 
1476         if (!register_trace_event(&graph_trace_ret_event)) {
1477                 pr_warn("Warning: could not register graph trace events\n");
1478                 return 1;
1479         }
1480 
1481         return register_tracer(&graph_trace);
1482 }
1483 
1484 core_initcall(init_graph_trace);
1485 

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