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

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  1 // SPDX-License-Identifier: GPL-2.0
  2 /*
  3  *
  4  * Function graph tracer.
  5  * Copyright (c) 2008-2009 Frederic Weisbecker <fweisbec@gmail.com>
  6  * Mostly borrowed from function tracer which
  7  * is Copyright (c) Steven Rostedt <srostedt@redhat.com>
  8  *
  9  */
 10 #include <linux/uaccess.h>
 11 #include <linux/ftrace.h>
 12 #include <linux/interrupt.h>
 13 #include <linux/slab.h>
 14 #include <linux/fs.h>
 15 
 16 #include "trace.h"
 17 #include "trace_output.h"
 18 
 19 static bool kill_ftrace_graph;
 20 
 21 /**
 22  * ftrace_graph_is_dead - returns true if ftrace_graph_stop() was called
 23  *
 24  * ftrace_graph_stop() is called when a severe error is detected in
 25  * the function graph tracing. This function is called by the critical
 26  * paths of function graph to keep those paths from doing any more harm.
 27  */
 28 bool ftrace_graph_is_dead(void)
 29 {
 30         return kill_ftrace_graph;
 31 }
 32 
 33 /**
 34  * ftrace_graph_stop - set to permanently disable function graph tracincg
 35  *
 36  * In case of an error int function graph tracing, this is called
 37  * to try to keep function graph tracing from causing any more harm.
 38  * Usually this is pretty severe and this is called to try to at least
 39  * get a warning out to the user.
 40  */
 41 void ftrace_graph_stop(void)
 42 {
 43         kill_ftrace_graph = true;
 44 }
 45 
 46 /* When set, irq functions will be ignored */
 47 static int ftrace_graph_skip_irqs;
 48 
 49 struct fgraph_cpu_data {
 50         pid_t           last_pid;
 51         int             depth;
 52         int             depth_irq;
 53         int             ignore;
 54         unsigned long   enter_funcs[FTRACE_RETFUNC_DEPTH];
 55 };
 56 
 57 struct fgraph_data {
 58         struct fgraph_cpu_data __percpu *cpu_data;
 59 
 60         /* Place to preserve last processed entry. */
 61         struct ftrace_graph_ent_entry   ent;
 62         struct ftrace_graph_ret_entry   ret;
 63         int                             failed;
 64         int                             cpu;
 65 };
 66 
 67 #define TRACE_GRAPH_INDENT      2
 68 
 69 unsigned int fgraph_max_depth;
 70 
 71 static struct tracer_opt trace_opts[] = {
 72         /* Display overruns? (for self-debug purpose) */
 73         { TRACER_OPT(funcgraph-overrun, TRACE_GRAPH_PRINT_OVERRUN) },
 74         /* Display CPU ? */
 75         { TRACER_OPT(funcgraph-cpu, TRACE_GRAPH_PRINT_CPU) },
 76         /* Display Overhead ? */
 77         { TRACER_OPT(funcgraph-overhead, TRACE_GRAPH_PRINT_OVERHEAD) },
 78         /* Display proc name/pid */
 79         { TRACER_OPT(funcgraph-proc, TRACE_GRAPH_PRINT_PROC) },
 80         /* Display duration of execution */
 81         { TRACER_OPT(funcgraph-duration, TRACE_GRAPH_PRINT_DURATION) },
 82         /* Display absolute time of an entry */
 83         { TRACER_OPT(funcgraph-abstime, TRACE_GRAPH_PRINT_ABS_TIME) },
 84         /* Display interrupts */
 85         { TRACER_OPT(funcgraph-irqs, TRACE_GRAPH_PRINT_IRQS) },
 86         /* Display function name after trailing } */
 87         { TRACER_OPT(funcgraph-tail, TRACE_GRAPH_PRINT_TAIL) },
 88         /* Include sleep time (scheduled out) between entry and return */
 89         { TRACER_OPT(sleep-time, TRACE_GRAPH_SLEEP_TIME) },
 90         /* Include time within nested functions */
 91         { TRACER_OPT(graph-time, TRACE_GRAPH_GRAPH_TIME) },
 92         { } /* Empty entry */
 93 };
 94 
 95 static struct tracer_flags tracer_flags = {
 96         /* Don't display overruns, proc, or tail by default */
 97         .val = TRACE_GRAPH_PRINT_CPU | TRACE_GRAPH_PRINT_OVERHEAD |
 98                TRACE_GRAPH_PRINT_DURATION | TRACE_GRAPH_PRINT_IRQS |
 99                TRACE_GRAPH_SLEEP_TIME | TRACE_GRAPH_GRAPH_TIME,
100         .opts = trace_opts
101 };
102 
103 static struct trace_array *graph_array;
104 
105 /*
106  * DURATION column is being also used to display IRQ signs,
107  * following values are used by print_graph_irq and others
108  * to fill in space into DURATION column.
109  */
110 enum {
111         FLAGS_FILL_FULL  = 1 << TRACE_GRAPH_PRINT_FILL_SHIFT,
112         FLAGS_FILL_START = 2 << TRACE_GRAPH_PRINT_FILL_SHIFT,
113         FLAGS_FILL_END   = 3 << TRACE_GRAPH_PRINT_FILL_SHIFT,
114 };
115 
116 static void
117 print_graph_duration(struct trace_array *tr, unsigned long long duration,
118                      struct trace_seq *s, u32 flags);
119 
120 /* Add a function return address to the trace stack on thread info.*/
121 int
122 ftrace_push_return_trace(unsigned long ret, unsigned long func, int *depth,
123                          unsigned long frame_pointer, unsigned long *retp)
124 {
125         unsigned long long calltime;
126         int index;
127 
128         if (unlikely(ftrace_graph_is_dead()))
129                 return -EBUSY;
130 
131         if (!current->ret_stack)
132                 return -EBUSY;
133 
134         /*
135          * We must make sure the ret_stack is tested before we read
136          * anything else.
137          */
138         smp_rmb();
139 
140         /* The return trace stack is full */
141         if (current->curr_ret_stack == FTRACE_RETFUNC_DEPTH - 1) {
142                 atomic_inc(&current->trace_overrun);
143                 return -EBUSY;
144         }
145 
146         /*
147          * The curr_ret_stack is an index to ftrace return stack of
148          * current task.  Its value should be in [0, FTRACE_RETFUNC_
149          * DEPTH) when the function graph tracer is used.  To support
150          * filtering out specific functions, it makes the index
151          * negative by subtracting huge value (FTRACE_NOTRACE_DEPTH)
152          * so when it sees a negative index the ftrace will ignore
153          * the record.  And the index gets recovered when returning
154          * from the filtered function by adding the FTRACE_NOTRACE_
155          * DEPTH and then it'll continue to record functions normally.
156          *
157          * The curr_ret_stack is initialized to -1 and get increased
158          * in this function.  So it can be less than -1 only if it was
159          * filtered out via ftrace_graph_notrace_addr() which can be
160          * set from set_graph_notrace file in tracefs by user.
161          */
162         if (current->curr_ret_stack < -1)
163                 return -EBUSY;
164 
165         calltime = trace_clock_local();
166 
167         index = ++current->curr_ret_stack;
168         if (ftrace_graph_notrace_addr(func))
169                 current->curr_ret_stack -= FTRACE_NOTRACE_DEPTH;
170         barrier();
171         current->ret_stack[index].ret = ret;
172         current->ret_stack[index].func = func;
173         current->ret_stack[index].calltime = calltime;
174 #ifdef HAVE_FUNCTION_GRAPH_FP_TEST
175         current->ret_stack[index].fp = frame_pointer;
176 #endif
177 #ifdef HAVE_FUNCTION_GRAPH_RET_ADDR_PTR
178         current->ret_stack[index].retp = retp;
179 #endif
180         *depth = current->curr_ret_stack;
181 
182         return 0;
183 }
184 
185 /* Retrieve a function return address to the trace stack on thread info.*/
186 static void
187 ftrace_pop_return_trace(struct ftrace_graph_ret *trace, unsigned long *ret,
188                         unsigned long frame_pointer)
189 {
190         int index;
191 
192         index = current->curr_ret_stack;
193 
194         /*
195          * A negative index here means that it's just returned from a
196          * notrace'd function.  Recover index to get an original
197          * return address.  See ftrace_push_return_trace().
198          *
199          * TODO: Need to check whether the stack gets corrupted.
200          */
201         if (index < 0)
202                 index += FTRACE_NOTRACE_DEPTH;
203 
204         if (unlikely(index < 0 || index >= FTRACE_RETFUNC_DEPTH)) {
205                 ftrace_graph_stop();
206                 WARN_ON(1);
207                 /* Might as well panic, otherwise we have no where to go */
208                 *ret = (unsigned long)panic;
209                 return;
210         }
211 
212 #ifdef HAVE_FUNCTION_GRAPH_FP_TEST
213         /*
214          * The arch may choose to record the frame pointer used
215          * and check it here to make sure that it is what we expect it
216          * to be. If gcc does not set the place holder of the return
217          * address in the frame pointer, and does a copy instead, then
218          * the function graph trace will fail. This test detects this
219          * case.
220          *
221          * Currently, x86_32 with optimize for size (-Os) makes the latest
222          * gcc do the above.
223          *
224          * Note, -mfentry does not use frame pointers, and this test
225          *  is not needed if CC_USING_FENTRY is set.
226          */
227         if (unlikely(current->ret_stack[index].fp != frame_pointer)) {
228                 ftrace_graph_stop();
229                 WARN(1, "Bad frame pointer: expected %lx, received %lx\n"
230                      "  from func %ps return to %lx\n",
231                      current->ret_stack[index].fp,
232                      frame_pointer,
233                      (void *)current->ret_stack[index].func,
234                      current->ret_stack[index].ret);
235                 *ret = (unsigned long)panic;
236                 return;
237         }
238 #endif
239 
240         *ret = current->ret_stack[index].ret;
241         trace->func = current->ret_stack[index].func;
242         trace->calltime = current->ret_stack[index].calltime;
243         trace->overrun = atomic_read(&current->trace_overrun);
244         trace->depth = index;
245 }
246 
247 /*
248  * Send the trace to the ring-buffer.
249  * @return the original return address.
250  */
251 unsigned long ftrace_return_to_handler(unsigned long frame_pointer)
252 {
253         struct ftrace_graph_ret trace;
254         unsigned long ret;
255 
256         ftrace_pop_return_trace(&trace, &ret, frame_pointer);
257         trace.rettime = trace_clock_local();
258         barrier();
259         current->curr_ret_stack--;
260         /*
261          * The curr_ret_stack can be less than -1 only if it was
262          * filtered out and it's about to return from the function.
263          * Recover the index and continue to trace normal functions.
264          */
265         if (current->curr_ret_stack < -1) {
266                 current->curr_ret_stack += FTRACE_NOTRACE_DEPTH;
267                 return ret;
268         }
269 
270         /*
271          * The trace should run after decrementing the ret counter
272          * in case an interrupt were to come in. We don't want to
273          * lose the interrupt if max_depth is set.
274          */
275         ftrace_graph_return(&trace);
276 
277         if (unlikely(!ret)) {
278                 ftrace_graph_stop();
279                 WARN_ON(1);
280                 /* Might as well panic. What else to do? */
281                 ret = (unsigned long)panic;
282         }
283 
284         return ret;
285 }
286 
287 /**
288  * ftrace_graph_ret_addr - convert a potentially modified stack return address
289  *                         to its original value
290  *
291  * This function can be called by stack unwinding code to convert a found stack
292  * return address ('ret') to its original value, in case the function graph
293  * tracer has modified it to be 'return_to_handler'.  If the address hasn't
294  * been modified, the unchanged value of 'ret' is returned.
295  *
296  * 'idx' is a state variable which should be initialized by the caller to zero
297  * before the first call.
298  *
299  * 'retp' is a pointer to the return address on the stack.  It's ignored if
300  * the arch doesn't have HAVE_FUNCTION_GRAPH_RET_ADDR_PTR defined.
301  */
302 #ifdef HAVE_FUNCTION_GRAPH_RET_ADDR_PTR
303 unsigned long ftrace_graph_ret_addr(struct task_struct *task, int *idx,
304                                     unsigned long ret, unsigned long *retp)
305 {
306         int index = task->curr_ret_stack;
307         int i;
308 
309         if (ret != (unsigned long)return_to_handler)
310                 return ret;
311 
312         if (index < -1)
313                 index += FTRACE_NOTRACE_DEPTH;
314 
315         if (index < 0)
316                 return ret;
317 
318         for (i = 0; i <= index; i++)
319                 if (task->ret_stack[i].retp == retp)
320                         return task->ret_stack[i].ret;
321 
322         return ret;
323 }
324 #else /* !HAVE_FUNCTION_GRAPH_RET_ADDR_PTR */
325 unsigned long ftrace_graph_ret_addr(struct task_struct *task, int *idx,
326                                     unsigned long ret, unsigned long *retp)
327 {
328         int task_idx;
329 
330         if (ret != (unsigned long)return_to_handler)
331                 return ret;
332 
333         task_idx = task->curr_ret_stack;
334 
335         if (!task->ret_stack || task_idx < *idx)
336                 return ret;
337 
338         task_idx -= *idx;
339         (*idx)++;
340 
341         return task->ret_stack[task_idx].ret;
342 }
343 #endif /* HAVE_FUNCTION_GRAPH_RET_ADDR_PTR */
344 
345 int __trace_graph_entry(struct trace_array *tr,
346                                 struct ftrace_graph_ent *trace,
347                                 unsigned long flags,
348                                 int pc)
349 {
350         struct trace_event_call *call = &event_funcgraph_entry;
351         struct ring_buffer_event *event;
352         struct ring_buffer *buffer = tr->trace_buffer.buffer;
353         struct ftrace_graph_ent_entry *entry;
354 
355         event = trace_buffer_lock_reserve(buffer, TRACE_GRAPH_ENT,
356                                           sizeof(*entry), flags, pc);
357         if (!event)
358                 return 0;
359         entry   = ring_buffer_event_data(event);
360         entry->graph_ent                        = *trace;
361         if (!call_filter_check_discard(call, entry, buffer, event))
362                 trace_buffer_unlock_commit_nostack(buffer, event);
363 
364         return 1;
365 }
366 
367 static inline int ftrace_graph_ignore_irqs(void)
368 {
369         if (!ftrace_graph_skip_irqs || trace_recursion_test(TRACE_IRQ_BIT))
370                 return 0;
371 
372         return in_irq();
373 }
374 
375 int trace_graph_entry(struct ftrace_graph_ent *trace)
376 {
377         struct trace_array *tr = graph_array;
378         struct trace_array_cpu *data;
379         unsigned long flags;
380         long disabled;
381         int ret;
382         int cpu;
383         int pc;
384 
385         if (!ftrace_trace_task(tr))
386                 return 0;
387 
388         if (ftrace_graph_ignore_func(trace))
389                 return 0;
390 
391         if (ftrace_graph_ignore_irqs())
392                 return 0;
393 
394         /*
395          * Do not trace a function if it's filtered by set_graph_notrace.
396          * Make the index of ret stack negative to indicate that it should
397          * ignore further functions.  But it needs its own ret stack entry
398          * to recover the original index in order to continue tracing after
399          * returning from the function.
400          */
401         if (ftrace_graph_notrace_addr(trace->func))
402                 return 1;
403 
404         /*
405          * Stop here if tracing_threshold is set. We only write function return
406          * events to the ring buffer.
407          */
408         if (tracing_thresh)
409                 return 1;
410 
411         local_irq_save(flags);
412         cpu = raw_smp_processor_id();
413         data = per_cpu_ptr(tr->trace_buffer.data, cpu);
414         disabled = atomic_inc_return(&data->disabled);
415         if (likely(disabled == 1)) {
416                 pc = preempt_count();
417                 ret = __trace_graph_entry(tr, trace, flags, pc);
418         } else {
419                 ret = 0;
420         }
421 
422         atomic_dec(&data->disabled);
423         local_irq_restore(flags);
424 
425         return ret;
426 }
427 
428 static void
429 __trace_graph_function(struct trace_array *tr,
430                 unsigned long ip, unsigned long flags, int pc)
431 {
432         u64 time = trace_clock_local();
433         struct ftrace_graph_ent ent = {
434                 .func  = ip,
435                 .depth = 0,
436         };
437         struct ftrace_graph_ret ret = {
438                 .func     = ip,
439                 .depth    = 0,
440                 .calltime = time,
441                 .rettime  = time,
442         };
443 
444         __trace_graph_entry(tr, &ent, flags, pc);
445         __trace_graph_return(tr, &ret, flags, pc);
446 }
447 
448 void
449 trace_graph_function(struct trace_array *tr,
450                 unsigned long ip, unsigned long parent_ip,
451                 unsigned long flags, int pc)
452 {
453         __trace_graph_function(tr, ip, flags, pc);
454 }
455 
456 void __trace_graph_return(struct trace_array *tr,
457                                 struct ftrace_graph_ret *trace,
458                                 unsigned long flags,
459                                 int pc)
460 {
461         struct trace_event_call *call = &event_funcgraph_exit;
462         struct ring_buffer_event *event;
463         struct ring_buffer *buffer = tr->trace_buffer.buffer;
464         struct ftrace_graph_ret_entry *entry;
465 
466         event = trace_buffer_lock_reserve(buffer, TRACE_GRAPH_RET,
467                                           sizeof(*entry), flags, pc);
468         if (!event)
469                 return;
470         entry   = ring_buffer_event_data(event);
471         entry->ret                              = *trace;
472         if (!call_filter_check_discard(call, entry, buffer, event))
473                 trace_buffer_unlock_commit_nostack(buffer, event);
474 }
475 
476 void trace_graph_return(struct ftrace_graph_ret *trace)
477 {
478         struct trace_array *tr = graph_array;
479         struct trace_array_cpu *data;
480         unsigned long flags;
481         long disabled;
482         int cpu;
483         int pc;
484 
485         local_irq_save(flags);
486         cpu = raw_smp_processor_id();
487         data = per_cpu_ptr(tr->trace_buffer.data, cpu);
488         disabled = atomic_inc_return(&data->disabled);
489         if (likely(disabled == 1)) {
490                 pc = preempt_count();
491                 __trace_graph_return(tr, trace, flags, pc);
492         }
493         atomic_dec(&data->disabled);
494         local_irq_restore(flags);
495 }
496 
497 void set_graph_array(struct trace_array *tr)
498 {
499         graph_array = tr;
500 
501         /* Make graph_array visible before we start tracing */
502 
503         smp_mb();
504 }
505 
506 static void trace_graph_thresh_return(struct ftrace_graph_ret *trace)
507 {
508         if (tracing_thresh &&
509             (trace->rettime - trace->calltime < tracing_thresh))
510                 return;
511         else
512                 trace_graph_return(trace);
513 }
514 
515 static int graph_trace_init(struct trace_array *tr)
516 {
517         int ret;
518 
519         set_graph_array(tr);
520         if (tracing_thresh)
521                 ret = register_ftrace_graph(&trace_graph_thresh_return,
522                                             &trace_graph_entry);
523         else
524                 ret = register_ftrace_graph(&trace_graph_return,
525                                             &trace_graph_entry);
526         if (ret)
527                 return ret;
528         tracing_start_cmdline_record();
529 
530         return 0;
531 }
532 
533 static void graph_trace_reset(struct trace_array *tr)
534 {
535         tracing_stop_cmdline_record();
536         unregister_ftrace_graph();
537 }
538 
539 static int graph_trace_update_thresh(struct trace_array *tr)
540 {
541         graph_trace_reset(tr);
542         return graph_trace_init(tr);
543 }
544 
545 static int max_bytes_for_cpu;
546 
547 static void print_graph_cpu(struct trace_seq *s, int cpu)
548 {
549         /*
550          * Start with a space character - to make it stand out
551          * to the right a bit when trace output is pasted into
552          * email:
553          */
554         trace_seq_printf(s, " %*d) ", max_bytes_for_cpu, cpu);
555 }
556 
557 #define TRACE_GRAPH_PROCINFO_LENGTH     14
558 
559 static void print_graph_proc(struct trace_seq *s, pid_t pid)
560 {
561         char comm[TASK_COMM_LEN];
562         /* sign + log10(MAX_INT) + '\0' */
563         char pid_str[11];
564         int spaces = 0;
565         int len;
566         int i;
567 
568         trace_find_cmdline(pid, comm);
569         comm[7] = '\0';
570         sprintf(pid_str, "%d", pid);
571 
572         /* 1 stands for the "-" character */
573         len = strlen(comm) + strlen(pid_str) + 1;
574 
575         if (len < TRACE_GRAPH_PROCINFO_LENGTH)
576                 spaces = TRACE_GRAPH_PROCINFO_LENGTH - len;
577 
578         /* First spaces to align center */
579         for (i = 0; i < spaces / 2; i++)
580                 trace_seq_putc(s, ' ');
581 
582         trace_seq_printf(s, "%s-%s", comm, pid_str);
583 
584         /* Last spaces to align center */
585         for (i = 0; i < spaces - (spaces / 2); i++)
586                 trace_seq_putc(s, ' ');
587 }
588 
589 
590 static void print_graph_lat_fmt(struct trace_seq *s, struct trace_entry *entry)
591 {
592         trace_seq_putc(s, ' ');
593         trace_print_lat_fmt(s, entry);
594 }
595 
596 /* If the pid changed since the last trace, output this event */
597 static void
598 verif_pid(struct trace_seq *s, pid_t pid, int cpu, struct fgraph_data *data)
599 {
600         pid_t prev_pid;
601         pid_t *last_pid;
602 
603         if (!data)
604                 return;
605 
606         last_pid = &(per_cpu_ptr(data->cpu_data, cpu)->last_pid);
607 
608         if (*last_pid == pid)
609                 return;
610 
611         prev_pid = *last_pid;
612         *last_pid = pid;
613 
614         if (prev_pid == -1)
615                 return;
616 /*
617  * Context-switch trace line:
618 
619  ------------------------------------------
620  | 1)  migration/0--1  =>  sshd-1755
621  ------------------------------------------
622 
623  */
624         trace_seq_puts(s, " ------------------------------------------\n");
625         print_graph_cpu(s, cpu);
626         print_graph_proc(s, prev_pid);
627         trace_seq_puts(s, " => ");
628         print_graph_proc(s, pid);
629         trace_seq_puts(s, "\n ------------------------------------------\n\n");
630 }
631 
632 static struct ftrace_graph_ret_entry *
633 get_return_for_leaf(struct trace_iterator *iter,
634                 struct ftrace_graph_ent_entry *curr)
635 {
636         struct fgraph_data *data = iter->private;
637         struct ring_buffer_iter *ring_iter = NULL;
638         struct ring_buffer_event *event;
639         struct ftrace_graph_ret_entry *next;
640 
641         /*
642          * If the previous output failed to write to the seq buffer,
643          * then we just reuse the data from before.
644          */
645         if (data && data->failed) {
646                 curr = &data->ent;
647                 next = &data->ret;
648         } else {
649 
650                 ring_iter = trace_buffer_iter(iter, iter->cpu);
651 
652                 /* First peek to compare current entry and the next one */
653                 if (ring_iter)
654                         event = ring_buffer_iter_peek(ring_iter, NULL);
655                 else {
656                         /*
657                          * We need to consume the current entry to see
658                          * the next one.
659                          */
660                         ring_buffer_consume(iter->trace_buffer->buffer, iter->cpu,
661                                             NULL, NULL);
662                         event = ring_buffer_peek(iter->trace_buffer->buffer, iter->cpu,
663                                                  NULL, NULL);
664                 }
665 
666                 if (!event)
667                         return NULL;
668 
669                 next = ring_buffer_event_data(event);
670 
671                 if (data) {
672                         /*
673                          * Save current and next entries for later reference
674                          * if the output fails.
675                          */
676                         data->ent = *curr;
677                         /*
678                          * If the next event is not a return type, then
679                          * we only care about what type it is. Otherwise we can
680                          * safely copy the entire event.
681                          */
682                         if (next->ent.type == TRACE_GRAPH_RET)
683                                 data->ret = *next;
684                         else
685                                 data->ret.ent.type = next->ent.type;
686                 }
687         }
688 
689         if (next->ent.type != TRACE_GRAPH_RET)
690                 return NULL;
691 
692         if (curr->ent.pid != next->ent.pid ||
693                         curr->graph_ent.func != next->ret.func)
694                 return NULL;
695 
696         /* this is a leaf, now advance the iterator */
697         if (ring_iter)
698                 ring_buffer_read(ring_iter, NULL);
699 
700         return next;
701 }
702 
703 static void print_graph_abs_time(u64 t, struct trace_seq *s)
704 {
705         unsigned long usecs_rem;
706 
707         usecs_rem = do_div(t, NSEC_PER_SEC);
708         usecs_rem /= 1000;
709 
710         trace_seq_printf(s, "%5lu.%06lu |  ",
711                          (unsigned long)t, usecs_rem);
712 }
713 
714 static void
715 print_graph_irq(struct trace_iterator *iter, unsigned long addr,
716                 enum trace_type type, int cpu, pid_t pid, u32 flags)
717 {
718         struct trace_array *tr = iter->tr;
719         struct trace_seq *s = &iter->seq;
720         struct trace_entry *ent = iter->ent;
721 
722         if (addr < (unsigned long)__irqentry_text_start ||
723                 addr >= (unsigned long)__irqentry_text_end)
724                 return;
725 
726         if (tr->trace_flags & TRACE_ITER_CONTEXT_INFO) {
727                 /* Absolute time */
728                 if (flags & TRACE_GRAPH_PRINT_ABS_TIME)
729                         print_graph_abs_time(iter->ts, s);
730 
731                 /* Cpu */
732                 if (flags & TRACE_GRAPH_PRINT_CPU)
733                         print_graph_cpu(s, cpu);
734 
735                 /* Proc */
736                 if (flags & TRACE_GRAPH_PRINT_PROC) {
737                         print_graph_proc(s, pid);
738                         trace_seq_puts(s, " | ");
739                 }
740 
741                 /* Latency format */
742                 if (tr->trace_flags & TRACE_ITER_LATENCY_FMT)
743                         print_graph_lat_fmt(s, ent);
744         }
745 
746         /* No overhead */
747         print_graph_duration(tr, 0, s, flags | FLAGS_FILL_START);
748 
749         if (type == TRACE_GRAPH_ENT)
750                 trace_seq_puts(s, "==========>");
751         else
752                 trace_seq_puts(s, "<==========");
753 
754         print_graph_duration(tr, 0, s, flags | FLAGS_FILL_END);
755         trace_seq_putc(s, '\n');
756 }
757 
758 void
759 trace_print_graph_duration(unsigned long long duration, struct trace_seq *s)
760 {
761         unsigned long nsecs_rem = do_div(duration, 1000);
762         /* log10(ULONG_MAX) + '\0' */
763         char usecs_str[21];
764         char nsecs_str[5];
765         int len;
766         int i;
767 
768         sprintf(usecs_str, "%lu", (unsigned long) duration);
769 
770         /* Print msecs */
771         trace_seq_printf(s, "%s", usecs_str);
772 
773         len = strlen(usecs_str);
774 
775         /* Print nsecs (we don't want to exceed 7 numbers) */
776         if (len < 7) {
777                 size_t slen = min_t(size_t, sizeof(nsecs_str), 8UL - len);
778 
779                 snprintf(nsecs_str, slen, "%03lu", nsecs_rem);
780                 trace_seq_printf(s, ".%s", nsecs_str);
781                 len += strlen(nsecs_str) + 1;
782         }
783 
784         trace_seq_puts(s, " us ");
785 
786         /* Print remaining spaces to fit the row's width */
787         for (i = len; i < 8; i++)
788                 trace_seq_putc(s, ' ');
789 }
790 
791 static void
792 print_graph_duration(struct trace_array *tr, unsigned long long duration,
793                      struct trace_seq *s, u32 flags)
794 {
795         if (!(flags & TRACE_GRAPH_PRINT_DURATION) ||
796             !(tr->trace_flags & TRACE_ITER_CONTEXT_INFO))
797                 return;
798 
799         /* No real adata, just filling the column with spaces */
800         switch (flags & TRACE_GRAPH_PRINT_FILL_MASK) {
801         case FLAGS_FILL_FULL:
802                 trace_seq_puts(s, "              |  ");
803                 return;
804         case FLAGS_FILL_START:
805                 trace_seq_puts(s, "  ");
806                 return;
807         case FLAGS_FILL_END:
808                 trace_seq_puts(s, " |");
809                 return;
810         }
811 
812         /* Signal a overhead of time execution to the output */
813         if (flags & TRACE_GRAPH_PRINT_OVERHEAD)
814                 trace_seq_printf(s, "%c ", trace_find_mark(duration));
815         else
816                 trace_seq_puts(s, "  ");
817 
818         trace_print_graph_duration(duration, s);
819         trace_seq_puts(s, "|  ");
820 }
821 
822 /* Case of a leaf function on its call entry */
823 static enum print_line_t
824 print_graph_entry_leaf(struct trace_iterator *iter,
825                 struct ftrace_graph_ent_entry *entry,
826                 struct ftrace_graph_ret_entry *ret_entry,
827                 struct trace_seq *s, u32 flags)
828 {
829         struct fgraph_data *data = iter->private;
830         struct trace_array *tr = iter->tr;
831         struct ftrace_graph_ret *graph_ret;
832         struct ftrace_graph_ent *call;
833         unsigned long long duration;
834         int i;
835 
836         graph_ret = &ret_entry->ret;
837         call = &entry->graph_ent;
838         duration = graph_ret->rettime - graph_ret->calltime;
839 
840         if (data) {
841                 struct fgraph_cpu_data *cpu_data;
842                 int cpu = iter->cpu;
843 
844                 cpu_data = per_cpu_ptr(data->cpu_data, cpu);
845 
846                 /* If a graph tracer ignored set_graph_notrace */
847                 if (call->depth < -1)
848                         call->depth += FTRACE_NOTRACE_DEPTH;
849 
850                 /*
851                  * Comments display at + 1 to depth. Since
852                  * this is a leaf function, keep the comments
853                  * equal to this depth.
854                  */
855                 cpu_data->depth = call->depth - 1;
856 
857                 /* No need to keep this function around for this depth */
858                 if (call->depth < FTRACE_RETFUNC_DEPTH &&
859                     !WARN_ON_ONCE(call->depth < 0))
860                         cpu_data->enter_funcs[call->depth] = 0;
861         }
862 
863         /* Overhead and duration */
864         print_graph_duration(tr, duration, s, flags);
865 
866         /* Function */
867         for (i = 0; i < call->depth * TRACE_GRAPH_INDENT; i++)
868                 trace_seq_putc(s, ' ');
869 
870         trace_seq_printf(s, "%ps();\n", (void *)call->func);
871 
872         return trace_handle_return(s);
873 }
874 
875 static enum print_line_t
876 print_graph_entry_nested(struct trace_iterator *iter,
877                          struct ftrace_graph_ent_entry *entry,
878                          struct trace_seq *s, int cpu, u32 flags)
879 {
880         struct ftrace_graph_ent *call = &entry->graph_ent;
881         struct fgraph_data *data = iter->private;
882         struct trace_array *tr = iter->tr;
883         int i;
884 
885         if (data) {
886                 struct fgraph_cpu_data *cpu_data;
887                 int cpu = iter->cpu;
888 
889                 /* If a graph tracer ignored set_graph_notrace */
890                 if (call->depth < -1)
891                         call->depth += FTRACE_NOTRACE_DEPTH;
892 
893                 cpu_data = per_cpu_ptr(data->cpu_data, cpu);
894                 cpu_data->depth = call->depth;
895 
896                 /* Save this function pointer to see if the exit matches */
897                 if (call->depth < FTRACE_RETFUNC_DEPTH &&
898                     !WARN_ON_ONCE(call->depth < 0))
899                         cpu_data->enter_funcs[call->depth] = call->func;
900         }
901 
902         /* No time */
903         print_graph_duration(tr, 0, s, flags | FLAGS_FILL_FULL);
904 
905         /* Function */
906         for (i = 0; i < call->depth * TRACE_GRAPH_INDENT; i++)
907                 trace_seq_putc(s, ' ');
908 
909         trace_seq_printf(s, "%ps() {\n", (void *)call->func);
910 
911         if (trace_seq_has_overflowed(s))
912                 return TRACE_TYPE_PARTIAL_LINE;
913 
914         /*
915          * we already consumed the current entry to check the next one
916          * and see if this is a leaf.
917          */
918         return TRACE_TYPE_NO_CONSUME;
919 }
920 
921 static void
922 print_graph_prologue(struct trace_iterator *iter, struct trace_seq *s,
923                      int type, unsigned long addr, u32 flags)
924 {
925         struct fgraph_data *data = iter->private;
926         struct trace_entry *ent = iter->ent;
927         struct trace_array *tr = iter->tr;
928         int cpu = iter->cpu;
929 
930         /* Pid */
931         verif_pid(s, ent->pid, cpu, data);
932 
933         if (type)
934                 /* Interrupt */
935                 print_graph_irq(iter, addr, type, cpu, ent->pid, flags);
936 
937         if (!(tr->trace_flags & TRACE_ITER_CONTEXT_INFO))
938                 return;
939 
940         /* Absolute time */
941         if (flags & TRACE_GRAPH_PRINT_ABS_TIME)
942                 print_graph_abs_time(iter->ts, s);
943 
944         /* Cpu */
945         if (flags & TRACE_GRAPH_PRINT_CPU)
946                 print_graph_cpu(s, cpu);
947 
948         /* Proc */
949         if (flags & TRACE_GRAPH_PRINT_PROC) {
950                 print_graph_proc(s, ent->pid);
951                 trace_seq_puts(s, " | ");
952         }
953 
954         /* Latency format */
955         if (tr->trace_flags & TRACE_ITER_LATENCY_FMT)
956                 print_graph_lat_fmt(s, ent);
957 
958         return;
959 }
960 
961 /*
962  * Entry check for irq code
963  *
964  * returns 1 if
965  *  - we are inside irq code
966  *  - we just entered irq code
967  *
968  * retunns 0 if
969  *  - funcgraph-interrupts option is set
970  *  - we are not inside irq code
971  */
972 static int
973 check_irq_entry(struct trace_iterator *iter, u32 flags,
974                 unsigned long addr, int depth)
975 {
976         int cpu = iter->cpu;
977         int *depth_irq;
978         struct fgraph_data *data = iter->private;
979 
980         /*
981          * If we are either displaying irqs, or we got called as
982          * a graph event and private data does not exist,
983          * then we bypass the irq check.
984          */
985         if ((flags & TRACE_GRAPH_PRINT_IRQS) ||
986             (!data))
987                 return 0;
988 
989         depth_irq = &(per_cpu_ptr(data->cpu_data, cpu)->depth_irq);
990 
991         /*
992          * We are inside the irq code
993          */
994         if (*depth_irq >= 0)
995                 return 1;
996 
997         if ((addr < (unsigned long)__irqentry_text_start) ||
998             (addr >= (unsigned long)__irqentry_text_end))
999                 return 0;
1000 
1001         /*
1002          * We are entering irq code.
1003          */
1004         *depth_irq = depth;
1005         return 1;
1006 }
1007 
1008 /*
1009  * Return check for irq code
1010  *
1011  * returns 1 if
1012  *  - we are inside irq code
1013  *  - we just left irq code
1014  *
1015  * returns 0 if
1016  *  - funcgraph-interrupts option is set
1017  *  - we are not inside irq code
1018  */
1019 static int
1020 check_irq_return(struct trace_iterator *iter, u32 flags, int depth)
1021 {
1022         int cpu = iter->cpu;
1023         int *depth_irq;
1024         struct fgraph_data *data = iter->private;
1025 
1026         /*
1027          * If we are either displaying irqs, or we got called as
1028          * a graph event and private data does not exist,
1029          * then we bypass the irq check.
1030          */
1031         if ((flags & TRACE_GRAPH_PRINT_IRQS) ||
1032             (!data))
1033                 return 0;
1034 
1035         depth_irq = &(per_cpu_ptr(data->cpu_data, cpu)->depth_irq);
1036 
1037         /*
1038          * We are not inside the irq code.
1039          */
1040         if (*depth_irq == -1)
1041                 return 0;
1042 
1043         /*
1044          * We are inside the irq code, and this is returning entry.
1045          * Let's not trace it and clear the entry depth, since
1046          * we are out of irq code.
1047          *
1048          * This condition ensures that we 'leave the irq code' once
1049          * we are out of the entry depth. Thus protecting us from
1050          * the RETURN entry loss.
1051          */
1052         if (*depth_irq >= depth) {
1053                 *depth_irq = -1;
1054                 return 1;
1055         }
1056 
1057         /*
1058          * We are inside the irq code, and this is not the entry.
1059          */
1060         return 1;
1061 }
1062 
1063 static enum print_line_t
1064 print_graph_entry(struct ftrace_graph_ent_entry *field, struct trace_seq *s,
1065                         struct trace_iterator *iter, u32 flags)
1066 {
1067         struct fgraph_data *data = iter->private;
1068         struct ftrace_graph_ent *call = &field->graph_ent;
1069         struct ftrace_graph_ret_entry *leaf_ret;
1070         static enum print_line_t ret;
1071         int cpu = iter->cpu;
1072 
1073         if (check_irq_entry(iter, flags, call->func, call->depth))
1074                 return TRACE_TYPE_HANDLED;
1075 
1076         print_graph_prologue(iter, s, TRACE_GRAPH_ENT, call->func, flags);
1077 
1078         leaf_ret = get_return_for_leaf(iter, field);
1079         if (leaf_ret)
1080                 ret = print_graph_entry_leaf(iter, field, leaf_ret, s, flags);
1081         else
1082                 ret = print_graph_entry_nested(iter, field, s, cpu, flags);
1083 
1084         if (data) {
1085                 /*
1086                  * If we failed to write our output, then we need to make
1087                  * note of it. Because we already consumed our entry.
1088                  */
1089                 if (s->full) {
1090                         data->failed = 1;
1091                         data->cpu = cpu;
1092                 } else
1093                         data->failed = 0;
1094         }
1095 
1096         return ret;
1097 }
1098 
1099 static enum print_line_t
1100 print_graph_return(struct ftrace_graph_ret *trace, struct trace_seq *s,
1101                    struct trace_entry *ent, struct trace_iterator *iter,
1102                    u32 flags)
1103 {
1104         unsigned long long duration = trace->rettime - trace->calltime;
1105         struct fgraph_data *data = iter->private;
1106         struct trace_array *tr = iter->tr;
1107         pid_t pid = ent->pid;
1108         int cpu = iter->cpu;
1109         int func_match = 1;
1110         int i;
1111 
1112         if (check_irq_return(iter, flags, trace->depth))
1113                 return TRACE_TYPE_HANDLED;
1114 
1115         if (data) {
1116                 struct fgraph_cpu_data *cpu_data;
1117                 int cpu = iter->cpu;
1118 
1119                 cpu_data = per_cpu_ptr(data->cpu_data, cpu);
1120 
1121                 /*
1122                  * Comments display at + 1 to depth. This is the
1123                  * return from a function, we now want the comments
1124                  * to display at the same level of the bracket.
1125                  */
1126                 cpu_data->depth = trace->depth - 1;
1127 
1128                 if (trace->depth < FTRACE_RETFUNC_DEPTH &&
1129                     !WARN_ON_ONCE(trace->depth < 0)) {
1130                         if (cpu_data->enter_funcs[trace->depth] != trace->func)
1131                                 func_match = 0;
1132                         cpu_data->enter_funcs[trace->depth] = 0;
1133                 }
1134         }
1135 
1136         print_graph_prologue(iter, s, 0, 0, flags);
1137 
1138         /* Overhead and duration */
1139         print_graph_duration(tr, duration, s, flags);
1140 
1141         /* Closing brace */
1142         for (i = 0; i < trace->depth * TRACE_GRAPH_INDENT; i++)
1143                 trace_seq_putc(s, ' ');
1144 
1145         /*
1146          * If the return function does not have a matching entry,
1147          * then the entry was lost. Instead of just printing
1148          * the '}' and letting the user guess what function this
1149          * belongs to, write out the function name. Always do
1150          * that if the funcgraph-tail option is enabled.
1151          */
1152         if (func_match && !(flags & TRACE_GRAPH_PRINT_TAIL))
1153                 trace_seq_puts(s, "}\n");
1154         else
1155                 trace_seq_printf(s, "} /* %ps */\n", (void *)trace->func);
1156 
1157         /* Overrun */
1158         if (flags & TRACE_GRAPH_PRINT_OVERRUN)
1159                 trace_seq_printf(s, " (Overruns: %lu)\n",
1160                                  trace->overrun);
1161 
1162         print_graph_irq(iter, trace->func, TRACE_GRAPH_RET,
1163                         cpu, pid, flags);
1164 
1165         return trace_handle_return(s);
1166 }
1167 
1168 static enum print_line_t
1169 print_graph_comment(struct trace_seq *s, struct trace_entry *ent,
1170                     struct trace_iterator *iter, u32 flags)
1171 {
1172         struct trace_array *tr = iter->tr;
1173         unsigned long sym_flags = (tr->trace_flags & TRACE_ITER_SYM_MASK);
1174         struct fgraph_data *data = iter->private;
1175         struct trace_event *event;
1176         int depth = 0;
1177         int ret;
1178         int i;
1179 
1180         if (data)
1181                 depth = per_cpu_ptr(data->cpu_data, iter->cpu)->depth;
1182 
1183         print_graph_prologue(iter, s, 0, 0, flags);
1184 
1185         /* No time */
1186         print_graph_duration(tr, 0, s, flags | FLAGS_FILL_FULL);
1187 
1188         /* Indentation */
1189         if (depth > 0)
1190                 for (i = 0; i < (depth + 1) * TRACE_GRAPH_INDENT; i++)
1191                         trace_seq_putc(s, ' ');
1192 
1193         /* The comment */
1194         trace_seq_puts(s, "/* ");
1195 
1196         switch (iter->ent->type) {
1197         case TRACE_BPUTS:
1198                 ret = trace_print_bputs_msg_only(iter);
1199                 if (ret != TRACE_TYPE_HANDLED)
1200                         return ret;
1201                 break;
1202         case TRACE_BPRINT:
1203                 ret = trace_print_bprintk_msg_only(iter);
1204                 if (ret != TRACE_TYPE_HANDLED)
1205                         return ret;
1206                 break;
1207         case TRACE_PRINT:
1208                 ret = trace_print_printk_msg_only(iter);
1209                 if (ret != TRACE_TYPE_HANDLED)
1210                         return ret;
1211                 break;
1212         default:
1213                 event = ftrace_find_event(ent->type);
1214                 if (!event)
1215                         return TRACE_TYPE_UNHANDLED;
1216 
1217                 ret = event->funcs->trace(iter, sym_flags, event);
1218                 if (ret != TRACE_TYPE_HANDLED)
1219                         return ret;
1220         }
1221 
1222         if (trace_seq_has_overflowed(s))
1223                 goto out;
1224 
1225         /* Strip ending newline */
1226         if (s->buffer[s->seq.len - 1] == '\n') {
1227                 s->buffer[s->seq.len - 1] = '\0';
1228                 s->seq.len--;
1229         }
1230 
1231         trace_seq_puts(s, " */\n");
1232  out:
1233         return trace_handle_return(s);
1234 }
1235 
1236 
1237 enum print_line_t
1238 print_graph_function_flags(struct trace_iterator *iter, u32 flags)
1239 {
1240         struct ftrace_graph_ent_entry *field;
1241         struct fgraph_data *data = iter->private;
1242         struct trace_entry *entry = iter->ent;
1243         struct trace_seq *s = &iter->seq;
1244         int cpu = iter->cpu;
1245         int ret;
1246 
1247         if (data && per_cpu_ptr(data->cpu_data, cpu)->ignore) {
1248                 per_cpu_ptr(data->cpu_data, cpu)->ignore = 0;
1249                 return TRACE_TYPE_HANDLED;
1250         }
1251 
1252         /*
1253          * If the last output failed, there's a possibility we need
1254          * to print out the missing entry which would never go out.
1255          */
1256         if (data && data->failed) {
1257                 field = &data->ent;
1258                 iter->cpu = data->cpu;
1259                 ret = print_graph_entry(field, s, iter, flags);
1260                 if (ret == TRACE_TYPE_HANDLED && iter->cpu != cpu) {
1261                         per_cpu_ptr(data->cpu_data, iter->cpu)->ignore = 1;
1262                         ret = TRACE_TYPE_NO_CONSUME;
1263                 }
1264                 iter->cpu = cpu;
1265                 return ret;
1266         }
1267 
1268         switch (entry->type) {
1269         case TRACE_GRAPH_ENT: {
1270                 /*
1271                  * print_graph_entry() may consume the current event,
1272                  * thus @field may become invalid, so we need to save it.
1273                  * sizeof(struct ftrace_graph_ent_entry) is very small,
1274                  * it can be safely saved at the stack.
1275                  */
1276                 struct ftrace_graph_ent_entry saved;
1277                 trace_assign_type(field, entry);
1278                 saved = *field;
1279                 return print_graph_entry(&saved, s, iter, flags);
1280         }
1281         case TRACE_GRAPH_RET: {
1282                 struct ftrace_graph_ret_entry *field;
1283                 trace_assign_type(field, entry);
1284                 return print_graph_return(&field->ret, s, entry, iter, flags);
1285         }
1286         case TRACE_STACK:
1287         case TRACE_FN:
1288                 /* dont trace stack and functions as comments */
1289                 return TRACE_TYPE_UNHANDLED;
1290 
1291         default:
1292                 return print_graph_comment(s, entry, iter, flags);
1293         }
1294 
1295         return TRACE_TYPE_HANDLED;
1296 }
1297 
1298 static enum print_line_t
1299 print_graph_function(struct trace_iterator *iter)
1300 {
1301         return print_graph_function_flags(iter, tracer_flags.val);
1302 }
1303 
1304 static enum print_line_t
1305 print_graph_function_event(struct trace_iterator *iter, int flags,
1306                            struct trace_event *event)
1307 {
1308         return print_graph_function(iter);
1309 }
1310 
1311 static void print_lat_header(struct seq_file *s, u32 flags)
1312 {
1313         static const char spaces[] = "                " /* 16 spaces */
1314                 "    "                                  /* 4 spaces */
1315                 "                 ";                    /* 17 spaces */
1316         int size = 0;
1317 
1318         if (flags & TRACE_GRAPH_PRINT_ABS_TIME)
1319                 size += 16;
1320         if (flags & TRACE_GRAPH_PRINT_CPU)
1321                 size += 4;
1322         if (flags & TRACE_GRAPH_PRINT_PROC)
1323                 size += 17;
1324 
1325         seq_printf(s, "#%.*s  _-----=> irqs-off        \n", size, spaces);
1326         seq_printf(s, "#%.*s / _----=> need-resched    \n", size, spaces);
1327         seq_printf(s, "#%.*s| / _---=> hardirq/softirq \n", size, spaces);
1328         seq_printf(s, "#%.*s|| / _--=> preempt-depth   \n", size, spaces);
1329         seq_printf(s, "#%.*s||| /                      \n", size, spaces);
1330 }
1331 
1332 static void __print_graph_headers_flags(struct trace_array *tr,
1333                                         struct seq_file *s, u32 flags)
1334 {
1335         int lat = tr->trace_flags & TRACE_ITER_LATENCY_FMT;
1336 
1337         if (lat)
1338                 print_lat_header(s, flags);
1339 
1340         /* 1st line */
1341         seq_putc(s, '#');
1342         if (flags & TRACE_GRAPH_PRINT_ABS_TIME)
1343                 seq_puts(s, "     TIME       ");
1344         if (flags & TRACE_GRAPH_PRINT_CPU)
1345                 seq_puts(s, " CPU");
1346         if (flags & TRACE_GRAPH_PRINT_PROC)
1347                 seq_puts(s, "  TASK/PID       ");
1348         if (lat)
1349                 seq_puts(s, "||||");
1350         if (flags & TRACE_GRAPH_PRINT_DURATION)
1351                 seq_puts(s, "  DURATION   ");
1352         seq_puts(s, "               FUNCTION CALLS\n");
1353 
1354         /* 2nd line */
1355         seq_putc(s, '#');
1356         if (flags & TRACE_GRAPH_PRINT_ABS_TIME)
1357                 seq_puts(s, "      |         ");
1358         if (flags & TRACE_GRAPH_PRINT_CPU)
1359                 seq_puts(s, " |  ");
1360         if (flags & TRACE_GRAPH_PRINT_PROC)
1361                 seq_puts(s, "   |    |        ");
1362         if (lat)
1363                 seq_puts(s, "||||");
1364         if (flags & TRACE_GRAPH_PRINT_DURATION)
1365                 seq_puts(s, "   |   |      ");
1366         seq_puts(s, "               |   |   |   |\n");
1367 }
1368 
1369 static void print_graph_headers(struct seq_file *s)
1370 {
1371         print_graph_headers_flags(s, tracer_flags.val);
1372 }
1373 
1374 void print_graph_headers_flags(struct seq_file *s, u32 flags)
1375 {
1376         struct trace_iterator *iter = s->private;
1377         struct trace_array *tr = iter->tr;
1378 
1379         if (!(tr->trace_flags & TRACE_ITER_CONTEXT_INFO))
1380                 return;
1381 
1382         if (tr->trace_flags & TRACE_ITER_LATENCY_FMT) {
1383                 /* print nothing if the buffers are empty */
1384                 if (trace_empty(iter))
1385                         return;
1386 
1387                 print_trace_header(s, iter);
1388         }
1389 
1390         __print_graph_headers_flags(tr, s, flags);
1391 }
1392 
1393 void graph_trace_open(struct trace_iterator *iter)
1394 {
1395         /* pid and depth on the last trace processed */
1396         struct fgraph_data *data;
1397         gfp_t gfpflags;
1398         int cpu;
1399 
1400         iter->private = NULL;
1401 
1402         /* We can be called in atomic context via ftrace_dump() */
1403         gfpflags = (in_atomic() || irqs_disabled()) ? GFP_ATOMIC : GFP_KERNEL;
1404 
1405         data = kzalloc(sizeof(*data), gfpflags);
1406         if (!data)
1407                 goto out_err;
1408 
1409         data->cpu_data = alloc_percpu_gfp(struct fgraph_cpu_data, gfpflags);
1410         if (!data->cpu_data)
1411                 goto out_err_free;
1412 
1413         for_each_possible_cpu(cpu) {
1414                 pid_t *pid = &(per_cpu_ptr(data->cpu_data, cpu)->last_pid);
1415                 int *depth = &(per_cpu_ptr(data->cpu_data, cpu)->depth);
1416                 int *ignore = &(per_cpu_ptr(data->cpu_data, cpu)->ignore);
1417                 int *depth_irq = &(per_cpu_ptr(data->cpu_data, cpu)->depth_irq);
1418 
1419                 *pid = -1;
1420                 *depth = 0;
1421                 *ignore = 0;
1422                 *depth_irq = -1;
1423         }
1424 
1425         iter->private = data;
1426 
1427         return;
1428 
1429  out_err_free:
1430         kfree(data);
1431  out_err:
1432         pr_warn("function graph tracer: not enough memory\n");
1433 }
1434 
1435 void graph_trace_close(struct trace_iterator *iter)
1436 {
1437         struct fgraph_data *data = iter->private;
1438 
1439         if (data) {
1440                 free_percpu(data->cpu_data);
1441                 kfree(data);
1442         }
1443 }
1444 
1445 static int
1446 func_graph_set_flag(struct trace_array *tr, u32 old_flags, u32 bit, int set)
1447 {
1448         if (bit == TRACE_GRAPH_PRINT_IRQS)
1449                 ftrace_graph_skip_irqs = !set;
1450 
1451         if (bit == TRACE_GRAPH_SLEEP_TIME)
1452                 ftrace_graph_sleep_time_control(set);
1453 
1454         if (bit == TRACE_GRAPH_GRAPH_TIME)
1455                 ftrace_graph_graph_time_control(set);
1456 
1457         return 0;
1458 }
1459 
1460 static struct trace_event_functions graph_functions = {
1461         .trace          = print_graph_function_event,
1462 };
1463 
1464 static struct trace_event graph_trace_entry_event = {
1465         .type           = TRACE_GRAPH_ENT,
1466         .funcs          = &graph_functions,
1467 };
1468 
1469 static struct trace_event graph_trace_ret_event = {
1470         .type           = TRACE_GRAPH_RET,
1471         .funcs          = &graph_functions
1472 };
1473 
1474 static struct tracer graph_trace __tracer_data = {
1475         .name           = "function_graph",
1476         .update_thresh  = graph_trace_update_thresh,
1477         .open           = graph_trace_open,
1478         .pipe_open      = graph_trace_open,
1479         .close          = graph_trace_close,
1480         .pipe_close     = graph_trace_close,
1481         .init           = graph_trace_init,
1482         .reset          = graph_trace_reset,
1483         .print_line     = print_graph_function,
1484         .print_header   = print_graph_headers,
1485         .flags          = &tracer_flags,
1486         .set_flag       = func_graph_set_flag,
1487 #ifdef CONFIG_FTRACE_SELFTEST
1488         .selftest       = trace_selftest_startup_function_graph,
1489 #endif
1490 };
1491 
1492 
1493 static ssize_t
1494 graph_depth_write(struct file *filp, const char __user *ubuf, size_t cnt,
1495                   loff_t *ppos)
1496 {
1497         unsigned long val;
1498         int ret;
1499 
1500         ret = kstrtoul_from_user(ubuf, cnt, 10, &val);
1501         if (ret)
1502                 return ret;
1503 
1504         fgraph_max_depth = val;
1505 
1506         *ppos += cnt;
1507 
1508         return cnt;
1509 }
1510 
1511 static ssize_t
1512 graph_depth_read(struct file *filp, char __user *ubuf, size_t cnt,
1513                  loff_t *ppos)
1514 {
1515         char buf[15]; /* More than enough to hold UINT_MAX + "\n"*/
1516         int n;
1517 
1518         n = sprintf(buf, "%d\n", fgraph_max_depth);
1519 
1520         return simple_read_from_buffer(ubuf, cnt, ppos, buf, n);
1521 }
1522 
1523 static const struct file_operations graph_depth_fops = {
1524         .open           = tracing_open_generic,
1525         .write          = graph_depth_write,
1526         .read           = graph_depth_read,
1527         .llseek         = generic_file_llseek,
1528 };
1529 
1530 static __init int init_graph_tracefs(void)
1531 {
1532         struct dentry *d_tracer;
1533 
1534         d_tracer = tracing_init_dentry();
1535         if (IS_ERR(d_tracer))
1536                 return 0;
1537 
1538         trace_create_file("max_graph_depth", 0644, d_tracer,
1539                           NULL, &graph_depth_fops);
1540 
1541         return 0;
1542 }
1543 fs_initcall(init_graph_tracefs);
1544 
1545 static __init int init_graph_trace(void)
1546 {
1547         max_bytes_for_cpu = snprintf(NULL, 0, "%u", nr_cpu_ids - 1);
1548 
1549         if (!register_trace_event(&graph_trace_entry_event)) {
1550                 pr_warn("Warning: could not register graph trace events\n");
1551                 return 1;
1552         }
1553 
1554         if (!register_trace_event(&graph_trace_ret_event)) {
1555                 pr_warn("Warning: could not register graph trace events\n");
1556                 return 1;
1557         }
1558 
1559         return register_tracer(&graph_trace);
1560 }
1561 
1562 core_initcall(init_graph_trace);
1563 

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