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Merge commit 'v2.6.36-rc7' into perf/core
[deliverable/linux.git] / kernel / trace / trace_functions_graph.c
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/debugfs.h>
10 #include <linux/uaccess.h>
11 #include <linux/ftrace.h>
12 #include <linux/slab.h>
13 #include <linux/fs.h>
14
15 #include "trace.h"
16 #include "trace_output.h"
17
18 /* When set, irq functions will be ignored */
19 static int ftrace_graph_skip_irqs;
20
21 struct fgraph_cpu_data {
22 pid_t last_pid;
23 int depth;
24 int depth_irq;
25 int ignore;
26 unsigned long enter_funcs[FTRACE_RETFUNC_DEPTH];
27 };
28
29 struct fgraph_data {
30 struct fgraph_cpu_data __percpu *cpu_data;
31
32 /* Place to preserve last processed entry. */
33 struct ftrace_graph_ent_entry ent;
34 struct ftrace_graph_ret_entry ret;
35 int failed;
36 int cpu;
37 };
38
39 #define TRACE_GRAPH_INDENT 2
40
41 /* Flag options */
42 #define TRACE_GRAPH_PRINT_OVERRUN 0x1
43 #define TRACE_GRAPH_PRINT_CPU 0x2
44 #define TRACE_GRAPH_PRINT_OVERHEAD 0x4
45 #define TRACE_GRAPH_PRINT_PROC 0x8
46 #define TRACE_GRAPH_PRINT_DURATION 0x10
47 #define TRACE_GRAPH_PRINT_ABS_TIME 0x20
48 #define TRACE_GRAPH_PRINT_IRQS 0x40
49
50 static struct tracer_opt trace_opts[] = {
51 /* Display overruns? (for self-debug purpose) */
52 { TRACER_OPT(funcgraph-overrun, TRACE_GRAPH_PRINT_OVERRUN) },
53 /* Display CPU ? */
54 { TRACER_OPT(funcgraph-cpu, TRACE_GRAPH_PRINT_CPU) },
55 /* Display Overhead ? */
56 { TRACER_OPT(funcgraph-overhead, TRACE_GRAPH_PRINT_OVERHEAD) },
57 /* Display proc name/pid */
58 { TRACER_OPT(funcgraph-proc, TRACE_GRAPH_PRINT_PROC) },
59 /* Display duration of execution */
60 { TRACER_OPT(funcgraph-duration, TRACE_GRAPH_PRINT_DURATION) },
61 /* Display absolute time of an entry */
62 { TRACER_OPT(funcgraph-abstime, TRACE_GRAPH_PRINT_ABS_TIME) },
63 /* Display interrupts */
64 { TRACER_OPT(funcgraph-irqs, TRACE_GRAPH_PRINT_IRQS) },
65 { } /* Empty entry */
66 };
67
68 static struct tracer_flags tracer_flags = {
69 /* Don't display overruns and proc by default */
70 .val = TRACE_GRAPH_PRINT_CPU | TRACE_GRAPH_PRINT_OVERHEAD |
71 TRACE_GRAPH_PRINT_DURATION | TRACE_GRAPH_PRINT_IRQS,
72 .opts = trace_opts
73 };
74
75 static struct trace_array *graph_array;
76
77
78 /* Add a function return address to the trace stack on thread info.*/
79 int
80 ftrace_push_return_trace(unsigned long ret, unsigned long func, int *depth,
81 unsigned long frame_pointer)
82 {
83 unsigned long long calltime;
84 int index;
85
86 if (!current->ret_stack)
87 return -EBUSY;
88
89 /*
90 * We must make sure the ret_stack is tested before we read
91 * anything else.
92 */
93 smp_rmb();
94
95 /* The return trace stack is full */
96 if (current->curr_ret_stack == FTRACE_RETFUNC_DEPTH - 1) {
97 atomic_inc(&current->trace_overrun);
98 return -EBUSY;
99 }
100
101 calltime = trace_clock_local();
102
103 index = ++current->curr_ret_stack;
104 barrier();
105 current->ret_stack[index].ret = ret;
106 current->ret_stack[index].func = func;
107 current->ret_stack[index].calltime = calltime;
108 current->ret_stack[index].subtime = 0;
109 current->ret_stack[index].fp = frame_pointer;
110 *depth = index;
111
112 return 0;
113 }
114
115 /* Retrieve a function return address to the trace stack on thread info.*/
116 static void
117 ftrace_pop_return_trace(struct ftrace_graph_ret *trace, unsigned long *ret,
118 unsigned long frame_pointer)
119 {
120 int index;
121
122 index = current->curr_ret_stack;
123
124 if (unlikely(index < 0)) {
125 ftrace_graph_stop();
126 WARN_ON(1);
127 /* Might as well panic, otherwise we have no where to go */
128 *ret = (unsigned long)panic;
129 return;
130 }
131
132 #ifdef CONFIG_HAVE_FUNCTION_GRAPH_FP_TEST
133 /*
134 * The arch may choose to record the frame pointer used
135 * and check it here to make sure that it is what we expect it
136 * to be. If gcc does not set the place holder of the return
137 * address in the frame pointer, and does a copy instead, then
138 * the function graph trace will fail. This test detects this
139 * case.
140 *
141 * Currently, x86_32 with optimize for size (-Os) makes the latest
142 * gcc do the above.
143 */
144 if (unlikely(current->ret_stack[index].fp != frame_pointer)) {
145 ftrace_graph_stop();
146 WARN(1, "Bad frame pointer: expected %lx, received %lx\n"
147 " from func %ps return to %lx\n",
148 current->ret_stack[index].fp,
149 frame_pointer,
150 (void *)current->ret_stack[index].func,
151 current->ret_stack[index].ret);
152 *ret = (unsigned long)panic;
153 return;
154 }
155 #endif
156
157 *ret = current->ret_stack[index].ret;
158 trace->func = current->ret_stack[index].func;
159 trace->calltime = current->ret_stack[index].calltime;
160 trace->overrun = atomic_read(&current->trace_overrun);
161 trace->depth = index;
162 }
163
164 /*
165 * Send the trace to the ring-buffer.
166 * @return the original return address.
167 */
168 unsigned long ftrace_return_to_handler(unsigned long frame_pointer)
169 {
170 struct ftrace_graph_ret trace;
171 unsigned long ret;
172
173 ftrace_pop_return_trace(&trace, &ret, frame_pointer);
174 trace.rettime = trace_clock_local();
175 ftrace_graph_return(&trace);
176 barrier();
177 current->curr_ret_stack--;
178
179 if (unlikely(!ret)) {
180 ftrace_graph_stop();
181 WARN_ON(1);
182 /* Might as well panic. What else to do? */
183 ret = (unsigned long)panic;
184 }
185
186 return ret;
187 }
188
189 int __trace_graph_entry(struct trace_array *tr,
190 struct ftrace_graph_ent *trace,
191 unsigned long flags,
192 int pc)
193 {
194 struct ftrace_event_call *call = &event_funcgraph_entry;
195 struct ring_buffer_event *event;
196 struct ring_buffer *buffer = tr->buffer;
197 struct ftrace_graph_ent_entry *entry;
198
199 if (unlikely(__this_cpu_read(ftrace_cpu_disabled)))
200 return 0;
201
202 event = trace_buffer_lock_reserve(buffer, TRACE_GRAPH_ENT,
203 sizeof(*entry), flags, pc);
204 if (!event)
205 return 0;
206 entry = ring_buffer_event_data(event);
207 entry->graph_ent = *trace;
208 if (!filter_current_check_discard(buffer, call, entry, event))
209 ring_buffer_unlock_commit(buffer, event);
210
211 return 1;
212 }
213
214 static inline int ftrace_graph_ignore_irqs(void)
215 {
216 if (!ftrace_graph_skip_irqs)
217 return 0;
218
219 return in_irq();
220 }
221
222 int trace_graph_entry(struct ftrace_graph_ent *trace)
223 {
224 struct trace_array *tr = graph_array;
225 struct trace_array_cpu *data;
226 unsigned long flags;
227 long disabled;
228 int ret;
229 int cpu;
230 int pc;
231
232 if (!ftrace_trace_task(current))
233 return 0;
234
235 /* trace it when it is-nested-in or is a function enabled. */
236 if (!(trace->depth || ftrace_graph_addr(trace->func)) ||
237 ftrace_graph_ignore_irqs())
238 return 0;
239
240 local_irq_save(flags);
241 cpu = raw_smp_processor_id();
242 data = tr->data[cpu];
243 disabled = atomic_inc_return(&data->disabled);
244 if (likely(disabled == 1)) {
245 pc = preempt_count();
246 ret = __trace_graph_entry(tr, trace, flags, pc);
247 } else {
248 ret = 0;
249 }
250
251 atomic_dec(&data->disabled);
252 local_irq_restore(flags);
253
254 return ret;
255 }
256
257 int trace_graph_thresh_entry(struct ftrace_graph_ent *trace)
258 {
259 if (tracing_thresh)
260 return 1;
261 else
262 return trace_graph_entry(trace);
263 }
264
265 void __trace_graph_return(struct trace_array *tr,
266 struct ftrace_graph_ret *trace,
267 unsigned long flags,
268 int pc)
269 {
270 struct ftrace_event_call *call = &event_funcgraph_exit;
271 struct ring_buffer_event *event;
272 struct ring_buffer *buffer = tr->buffer;
273 struct ftrace_graph_ret_entry *entry;
274
275 if (unlikely(__this_cpu_read(ftrace_cpu_disabled)))
276 return;
277
278 event = trace_buffer_lock_reserve(buffer, TRACE_GRAPH_RET,
279 sizeof(*entry), flags, pc);
280 if (!event)
281 return;
282 entry = ring_buffer_event_data(event);
283 entry->ret = *trace;
284 if (!filter_current_check_discard(buffer, call, entry, event))
285 ring_buffer_unlock_commit(buffer, event);
286 }
287
288 void trace_graph_return(struct ftrace_graph_ret *trace)
289 {
290 struct trace_array *tr = graph_array;
291 struct trace_array_cpu *data;
292 unsigned long flags;
293 long disabled;
294 int cpu;
295 int pc;
296
297 local_irq_save(flags);
298 cpu = raw_smp_processor_id();
299 data = tr->data[cpu];
300 disabled = atomic_inc_return(&data->disabled);
301 if (likely(disabled == 1)) {
302 pc = preempt_count();
303 __trace_graph_return(tr, trace, flags, pc);
304 }
305 atomic_dec(&data->disabled);
306 local_irq_restore(flags);
307 }
308
309 void set_graph_array(struct trace_array *tr)
310 {
311 graph_array = tr;
312
313 /* Make graph_array visible before we start tracing */
314
315 smp_mb();
316 }
317
318 void trace_graph_thresh_return(struct ftrace_graph_ret *trace)
319 {
320 if (tracing_thresh &&
321 (trace->rettime - trace->calltime < tracing_thresh))
322 return;
323 else
324 trace_graph_return(trace);
325 }
326
327 static int graph_trace_init(struct trace_array *tr)
328 {
329 int ret;
330
331 set_graph_array(tr);
332 if (tracing_thresh)
333 ret = register_ftrace_graph(&trace_graph_thresh_return,
334 &trace_graph_thresh_entry);
335 else
336 ret = register_ftrace_graph(&trace_graph_return,
337 &trace_graph_entry);
338 if (ret)
339 return ret;
340 tracing_start_cmdline_record();
341
342 return 0;
343 }
344
345 static void graph_trace_reset(struct trace_array *tr)
346 {
347 tracing_stop_cmdline_record();
348 unregister_ftrace_graph();
349 }
350
351 static int max_bytes_for_cpu;
352
353 static enum print_line_t
354 print_graph_cpu(struct trace_seq *s, int cpu)
355 {
356 int ret;
357
358 /*
359 * Start with a space character - to make it stand out
360 * to the right a bit when trace output is pasted into
361 * email:
362 */
363 ret = trace_seq_printf(s, " %*d) ", max_bytes_for_cpu, cpu);
364 if (!ret)
365 return TRACE_TYPE_PARTIAL_LINE;
366
367 return TRACE_TYPE_HANDLED;
368 }
369
370 #define TRACE_GRAPH_PROCINFO_LENGTH 14
371
372 static enum print_line_t
373 print_graph_proc(struct trace_seq *s, pid_t pid)
374 {
375 char comm[TASK_COMM_LEN];
376 /* sign + log10(MAX_INT) + '\0' */
377 char pid_str[11];
378 int spaces = 0;
379 int ret;
380 int len;
381 int i;
382
383 trace_find_cmdline(pid, comm);
384 comm[7] = '\0';
385 sprintf(pid_str, "%d", pid);
386
387 /* 1 stands for the "-" character */
388 len = strlen(comm) + strlen(pid_str) + 1;
389
390 if (len < TRACE_GRAPH_PROCINFO_LENGTH)
391 spaces = TRACE_GRAPH_PROCINFO_LENGTH - len;
392
393 /* First spaces to align center */
394 for (i = 0; i < spaces / 2; i++) {
395 ret = trace_seq_printf(s, " ");
396 if (!ret)
397 return TRACE_TYPE_PARTIAL_LINE;
398 }
399
400 ret = trace_seq_printf(s, "%s-%s", comm, pid_str);
401 if (!ret)
402 return TRACE_TYPE_PARTIAL_LINE;
403
404 /* Last spaces to align center */
405 for (i = 0; i < spaces - (spaces / 2); i++) {
406 ret = trace_seq_printf(s, " ");
407 if (!ret)
408 return TRACE_TYPE_PARTIAL_LINE;
409 }
410 return TRACE_TYPE_HANDLED;
411 }
412
413
414 static enum print_line_t
415 print_graph_lat_fmt(struct trace_seq *s, struct trace_entry *entry)
416 {
417 if (!trace_seq_putc(s, ' '))
418 return 0;
419
420 return trace_print_lat_fmt(s, entry);
421 }
422
423 /* If the pid changed since the last trace, output this event */
424 static enum print_line_t
425 verif_pid(struct trace_seq *s, pid_t pid, int cpu, struct fgraph_data *data)
426 {
427 pid_t prev_pid;
428 pid_t *last_pid;
429 int ret;
430
431 if (!data)
432 return TRACE_TYPE_HANDLED;
433
434 last_pid = &(per_cpu_ptr(data->cpu_data, cpu)->last_pid);
435
436 if (*last_pid == pid)
437 return TRACE_TYPE_HANDLED;
438
439 prev_pid = *last_pid;
440 *last_pid = pid;
441
442 if (prev_pid == -1)
443 return TRACE_TYPE_HANDLED;
444 /*
445 * Context-switch trace line:
446
447 ------------------------------------------
448 | 1) migration/0--1 => sshd-1755
449 ------------------------------------------
450
451 */
452 ret = trace_seq_printf(s,
453 " ------------------------------------------\n");
454 if (!ret)
455 return TRACE_TYPE_PARTIAL_LINE;
456
457 ret = print_graph_cpu(s, cpu);
458 if (ret == TRACE_TYPE_PARTIAL_LINE)
459 return TRACE_TYPE_PARTIAL_LINE;
460
461 ret = print_graph_proc(s, prev_pid);
462 if (ret == TRACE_TYPE_PARTIAL_LINE)
463 return TRACE_TYPE_PARTIAL_LINE;
464
465 ret = trace_seq_printf(s, " => ");
466 if (!ret)
467 return TRACE_TYPE_PARTIAL_LINE;
468
469 ret = print_graph_proc(s, pid);
470 if (ret == TRACE_TYPE_PARTIAL_LINE)
471 return TRACE_TYPE_PARTIAL_LINE;
472
473 ret = trace_seq_printf(s,
474 "\n ------------------------------------------\n\n");
475 if (!ret)
476 return TRACE_TYPE_PARTIAL_LINE;
477
478 return TRACE_TYPE_HANDLED;
479 }
480
481 static struct ftrace_graph_ret_entry *
482 get_return_for_leaf(struct trace_iterator *iter,
483 struct ftrace_graph_ent_entry *curr)
484 {
485 struct fgraph_data *data = iter->private;
486 struct ring_buffer_iter *ring_iter = NULL;
487 struct ring_buffer_event *event;
488 struct ftrace_graph_ret_entry *next;
489
490 /*
491 * If the previous output failed to write to the seq buffer,
492 * then we just reuse the data from before.
493 */
494 if (data && data->failed) {
495 curr = &data->ent;
496 next = &data->ret;
497 } else {
498
499 ring_iter = iter->buffer_iter[iter->cpu];
500
501 /* First peek to compare current entry and the next one */
502 if (ring_iter)
503 event = ring_buffer_iter_peek(ring_iter, NULL);
504 else {
505 /*
506 * We need to consume the current entry to see
507 * the next one.
508 */
509 ring_buffer_consume(iter->tr->buffer, iter->cpu,
510 NULL, NULL);
511 event = ring_buffer_peek(iter->tr->buffer, iter->cpu,
512 NULL, NULL);
513 }
514
515 if (!event)
516 return NULL;
517
518 next = ring_buffer_event_data(event);
519
520 if (data) {
521 /*
522 * Save current and next entries for later reference
523 * if the output fails.
524 */
525 data->ent = *curr;
526 /*
527 * If the next event is not a return type, then
528 * we only care about what type it is. Otherwise we can
529 * safely copy the entire event.
530 */
531 if (next->ent.type == TRACE_GRAPH_RET)
532 data->ret = *next;
533 else
534 data->ret.ent.type = next->ent.type;
535 }
536 }
537
538 if (next->ent.type != TRACE_GRAPH_RET)
539 return NULL;
540
541 if (curr->ent.pid != next->ent.pid ||
542 curr->graph_ent.func != next->ret.func)
543 return NULL;
544
545 /* this is a leaf, now advance the iterator */
546 if (ring_iter)
547 ring_buffer_read(ring_iter, NULL);
548
549 return next;
550 }
551
552 /* Signal a overhead of time execution to the output */
553 static int
554 print_graph_overhead(unsigned long long duration, struct trace_seq *s,
555 u32 flags)
556 {
557 /* If duration disappear, we don't need anything */
558 if (!(flags & TRACE_GRAPH_PRINT_DURATION))
559 return 1;
560
561 /* Non nested entry or return */
562 if (duration == -1)
563 return trace_seq_printf(s, " ");
564
565 if (flags & TRACE_GRAPH_PRINT_OVERHEAD) {
566 /* Duration exceeded 100 msecs */
567 if (duration > 100000ULL)
568 return trace_seq_printf(s, "! ");
569
570 /* Duration exceeded 10 msecs */
571 if (duration > 10000ULL)
572 return trace_seq_printf(s, "+ ");
573 }
574
575 return trace_seq_printf(s, " ");
576 }
577
578 static int print_graph_abs_time(u64 t, struct trace_seq *s)
579 {
580 unsigned long usecs_rem;
581
582 usecs_rem = do_div(t, NSEC_PER_SEC);
583 usecs_rem /= 1000;
584
585 return trace_seq_printf(s, "%5lu.%06lu | ",
586 (unsigned long)t, usecs_rem);
587 }
588
589 static enum print_line_t
590 print_graph_irq(struct trace_iterator *iter, unsigned long addr,
591 enum trace_type type, int cpu, pid_t pid, u32 flags)
592 {
593 int ret;
594 struct trace_seq *s = &iter->seq;
595
596 if (addr < (unsigned long)__irqentry_text_start ||
597 addr >= (unsigned long)__irqentry_text_end)
598 return TRACE_TYPE_UNHANDLED;
599
600 /* Absolute time */
601 if (flags & TRACE_GRAPH_PRINT_ABS_TIME) {
602 ret = print_graph_abs_time(iter->ts, s);
603 if (!ret)
604 return TRACE_TYPE_PARTIAL_LINE;
605 }
606
607 /* Cpu */
608 if (flags & TRACE_GRAPH_PRINT_CPU) {
609 ret = print_graph_cpu(s, cpu);
610 if (ret == TRACE_TYPE_PARTIAL_LINE)
611 return TRACE_TYPE_PARTIAL_LINE;
612 }
613
614 /* Proc */
615 if (flags & TRACE_GRAPH_PRINT_PROC) {
616 ret = print_graph_proc(s, pid);
617 if (ret == TRACE_TYPE_PARTIAL_LINE)
618 return TRACE_TYPE_PARTIAL_LINE;
619 ret = trace_seq_printf(s, " | ");
620 if (!ret)
621 return TRACE_TYPE_PARTIAL_LINE;
622 }
623
624 /* No overhead */
625 ret = print_graph_overhead(-1, s, flags);
626 if (!ret)
627 return TRACE_TYPE_PARTIAL_LINE;
628
629 if (type == TRACE_GRAPH_ENT)
630 ret = trace_seq_printf(s, "==========>");
631 else
632 ret = trace_seq_printf(s, "<==========");
633
634 if (!ret)
635 return TRACE_TYPE_PARTIAL_LINE;
636
637 /* Don't close the duration column if haven't one */
638 if (flags & TRACE_GRAPH_PRINT_DURATION)
639 trace_seq_printf(s, " |");
640 ret = trace_seq_printf(s, "\n");
641
642 if (!ret)
643 return TRACE_TYPE_PARTIAL_LINE;
644 return TRACE_TYPE_HANDLED;
645 }
646
647 enum print_line_t
648 trace_print_graph_duration(unsigned long long duration, struct trace_seq *s)
649 {
650 unsigned long nsecs_rem = do_div(duration, 1000);
651 /* log10(ULONG_MAX) + '\0' */
652 char msecs_str[21];
653 char nsecs_str[5];
654 int ret, len;
655 int i;
656
657 sprintf(msecs_str, "%lu", (unsigned long) duration);
658
659 /* Print msecs */
660 ret = trace_seq_printf(s, "%s", msecs_str);
661 if (!ret)
662 return TRACE_TYPE_PARTIAL_LINE;
663
664 len = strlen(msecs_str);
665
666 /* Print nsecs (we don't want to exceed 7 numbers) */
667 if (len < 7) {
668 snprintf(nsecs_str, min(sizeof(nsecs_str), 8UL - len), "%03lu",
669 nsecs_rem);
670 ret = trace_seq_printf(s, ".%s", nsecs_str);
671 if (!ret)
672 return TRACE_TYPE_PARTIAL_LINE;
673 len += strlen(nsecs_str);
674 }
675
676 ret = trace_seq_printf(s, " us ");
677 if (!ret)
678 return TRACE_TYPE_PARTIAL_LINE;
679
680 /* Print remaining spaces to fit the row's width */
681 for (i = len; i < 7; i++) {
682 ret = trace_seq_printf(s, " ");
683 if (!ret)
684 return TRACE_TYPE_PARTIAL_LINE;
685 }
686 return TRACE_TYPE_HANDLED;
687 }
688
689 static enum print_line_t
690 print_graph_duration(unsigned long long duration, struct trace_seq *s)
691 {
692 int ret;
693
694 ret = trace_print_graph_duration(duration, s);
695 if (ret != TRACE_TYPE_HANDLED)
696 return ret;
697
698 ret = trace_seq_printf(s, "| ");
699 if (!ret)
700 return TRACE_TYPE_PARTIAL_LINE;
701
702 return TRACE_TYPE_HANDLED;
703 }
704
705 /* Case of a leaf function on its call entry */
706 static enum print_line_t
707 print_graph_entry_leaf(struct trace_iterator *iter,
708 struct ftrace_graph_ent_entry *entry,
709 struct ftrace_graph_ret_entry *ret_entry,
710 struct trace_seq *s, u32 flags)
711 {
712 struct fgraph_data *data = iter->private;
713 struct ftrace_graph_ret *graph_ret;
714 struct ftrace_graph_ent *call;
715 unsigned long long duration;
716 int ret;
717 int i;
718
719 graph_ret = &ret_entry->ret;
720 call = &entry->graph_ent;
721 duration = graph_ret->rettime - graph_ret->calltime;
722
723 if (data) {
724 struct fgraph_cpu_data *cpu_data;
725 int cpu = iter->cpu;
726
727 cpu_data = per_cpu_ptr(data->cpu_data, cpu);
728
729 /*
730 * Comments display at + 1 to depth. Since
731 * this is a leaf function, keep the comments
732 * equal to this depth.
733 */
734 cpu_data->depth = call->depth - 1;
735
736 /* No need to keep this function around for this depth */
737 if (call->depth < FTRACE_RETFUNC_DEPTH)
738 cpu_data->enter_funcs[call->depth] = 0;
739 }
740
741 /* Overhead */
742 ret = print_graph_overhead(duration, s, flags);
743 if (!ret)
744 return TRACE_TYPE_PARTIAL_LINE;
745
746 /* Duration */
747 if (flags & TRACE_GRAPH_PRINT_DURATION) {
748 ret = print_graph_duration(duration, s);
749 if (ret == TRACE_TYPE_PARTIAL_LINE)
750 return TRACE_TYPE_PARTIAL_LINE;
751 }
752
753 /* Function */
754 for (i = 0; i < call->depth * TRACE_GRAPH_INDENT; i++) {
755 ret = trace_seq_printf(s, " ");
756 if (!ret)
757 return TRACE_TYPE_PARTIAL_LINE;
758 }
759
760 ret = trace_seq_printf(s, "%ps();\n", (void *)call->func);
761 if (!ret)
762 return TRACE_TYPE_PARTIAL_LINE;
763
764 return TRACE_TYPE_HANDLED;
765 }
766
767 static enum print_line_t
768 print_graph_entry_nested(struct trace_iterator *iter,
769 struct ftrace_graph_ent_entry *entry,
770 struct trace_seq *s, int cpu, u32 flags)
771 {
772 struct ftrace_graph_ent *call = &entry->graph_ent;
773 struct fgraph_data *data = iter->private;
774 int ret;
775 int i;
776
777 if (data) {
778 struct fgraph_cpu_data *cpu_data;
779 int cpu = iter->cpu;
780
781 cpu_data = per_cpu_ptr(data->cpu_data, cpu);
782 cpu_data->depth = call->depth;
783
784 /* Save this function pointer to see if the exit matches */
785 if (call->depth < FTRACE_RETFUNC_DEPTH)
786 cpu_data->enter_funcs[call->depth] = call->func;
787 }
788
789 /* No overhead */
790 ret = print_graph_overhead(-1, s, flags);
791 if (!ret)
792 return TRACE_TYPE_PARTIAL_LINE;
793
794 /* No time */
795 if (flags & TRACE_GRAPH_PRINT_DURATION) {
796 ret = trace_seq_printf(s, " | ");
797 if (!ret)
798 return TRACE_TYPE_PARTIAL_LINE;
799 }
800
801 /* Function */
802 for (i = 0; i < call->depth * TRACE_GRAPH_INDENT; i++) {
803 ret = trace_seq_printf(s, " ");
804 if (!ret)
805 return TRACE_TYPE_PARTIAL_LINE;
806 }
807
808 ret = trace_seq_printf(s, "%ps() {\n", (void *)call->func);
809 if (!ret)
810 return TRACE_TYPE_PARTIAL_LINE;
811
812 /*
813 * we already consumed the current entry to check the next one
814 * and see if this is a leaf.
815 */
816 return TRACE_TYPE_NO_CONSUME;
817 }
818
819 static enum print_line_t
820 print_graph_prologue(struct trace_iterator *iter, struct trace_seq *s,
821 int type, unsigned long addr, u32 flags)
822 {
823 struct fgraph_data *data = iter->private;
824 struct trace_entry *ent = iter->ent;
825 int cpu = iter->cpu;
826 int ret;
827
828 /* Pid */
829 if (verif_pid(s, ent->pid, cpu, data) == TRACE_TYPE_PARTIAL_LINE)
830 return TRACE_TYPE_PARTIAL_LINE;
831
832 if (type) {
833 /* Interrupt */
834 ret = print_graph_irq(iter, addr, type, cpu, ent->pid, flags);
835 if (ret == TRACE_TYPE_PARTIAL_LINE)
836 return TRACE_TYPE_PARTIAL_LINE;
837 }
838
839 /* Absolute time */
840 if (flags & TRACE_GRAPH_PRINT_ABS_TIME) {
841 ret = print_graph_abs_time(iter->ts, s);
842 if (!ret)
843 return TRACE_TYPE_PARTIAL_LINE;
844 }
845
846 /* Cpu */
847 if (flags & TRACE_GRAPH_PRINT_CPU) {
848 ret = print_graph_cpu(s, cpu);
849 if (ret == TRACE_TYPE_PARTIAL_LINE)
850 return TRACE_TYPE_PARTIAL_LINE;
851 }
852
853 /* Proc */
854 if (flags & TRACE_GRAPH_PRINT_PROC) {
855 ret = print_graph_proc(s, ent->pid);
856 if (ret == TRACE_TYPE_PARTIAL_LINE)
857 return TRACE_TYPE_PARTIAL_LINE;
858
859 ret = trace_seq_printf(s, " | ");
860 if (!ret)
861 return TRACE_TYPE_PARTIAL_LINE;
862 }
863
864 /* Latency format */
865 if (trace_flags & TRACE_ITER_LATENCY_FMT) {
866 ret = print_graph_lat_fmt(s, ent);
867 if (ret == TRACE_TYPE_PARTIAL_LINE)
868 return TRACE_TYPE_PARTIAL_LINE;
869 }
870
871 return 0;
872 }
873
874 /*
875 * Entry check for irq code
876 *
877 * returns 1 if
878 * - we are inside irq code
879 * - we just extered irq code
880 *
881 * retunns 0 if
882 * - funcgraph-interrupts option is set
883 * - we are not inside irq code
884 */
885 static int
886 check_irq_entry(struct trace_iterator *iter, u32 flags,
887 unsigned long addr, int depth)
888 {
889 int cpu = iter->cpu;
890 struct fgraph_data *data = iter->private;
891 int *depth_irq = &(per_cpu_ptr(data->cpu_data, cpu)->depth_irq);
892
893 if (flags & TRACE_GRAPH_PRINT_IRQS)
894 return 0;
895
896 /*
897 * We are inside the irq code
898 */
899 if (*depth_irq >= 0)
900 return 1;
901
902 if ((addr < (unsigned long)__irqentry_text_start) ||
903 (addr >= (unsigned long)__irqentry_text_end))
904 return 0;
905
906 /*
907 * We are entering irq code.
908 */
909 *depth_irq = depth;
910 return 1;
911 }
912
913 /*
914 * Return check for irq code
915 *
916 * returns 1 if
917 * - we are inside irq code
918 * - we just left irq code
919 *
920 * returns 0 if
921 * - funcgraph-interrupts option is set
922 * - we are not inside irq code
923 */
924 static int
925 check_irq_return(struct trace_iterator *iter, u32 flags, int depth)
926 {
927 int cpu = iter->cpu;
928 struct fgraph_data *data = iter->private;
929 int *depth_irq = &(per_cpu_ptr(data->cpu_data, cpu)->depth_irq);
930
931 if (flags & TRACE_GRAPH_PRINT_IRQS)
932 return 0;
933
934 /*
935 * We are not inside the irq code.
936 */
937 if (*depth_irq == -1)
938 return 0;
939
940 /*
941 * We are inside the irq code, and this is returning entry.
942 * Let's not trace it and clear the entry depth, since
943 * we are out of irq code.
944 *
945 * This condition ensures that we 'leave the irq code' once
946 * we are out of the entry depth. Thus protecting us from
947 * the RETURN entry loss.
948 */
949 if (*depth_irq >= depth) {
950 *depth_irq = -1;
951 return 1;
952 }
953
954 /*
955 * We are inside the irq code, and this is not the entry.
956 */
957 return 1;
958 }
959
960 static enum print_line_t
961 print_graph_entry(struct ftrace_graph_ent_entry *field, struct trace_seq *s,
962 struct trace_iterator *iter, u32 flags)
963 {
964 struct fgraph_data *data = iter->private;
965 struct ftrace_graph_ent *call = &field->graph_ent;
966 struct ftrace_graph_ret_entry *leaf_ret;
967 static enum print_line_t ret;
968 int cpu = iter->cpu;
969
970 if (check_irq_entry(iter, flags, call->func, call->depth))
971 return TRACE_TYPE_HANDLED;
972
973 if (print_graph_prologue(iter, s, TRACE_GRAPH_ENT, call->func, flags))
974 return TRACE_TYPE_PARTIAL_LINE;
975
976 leaf_ret = get_return_for_leaf(iter, field);
977 if (leaf_ret)
978 ret = print_graph_entry_leaf(iter, field, leaf_ret, s, flags);
979 else
980 ret = print_graph_entry_nested(iter, field, s, cpu, flags);
981
982 if (data) {
983 /*
984 * If we failed to write our output, then we need to make
985 * note of it. Because we already consumed our entry.
986 */
987 if (s->full) {
988 data->failed = 1;
989 data->cpu = cpu;
990 } else
991 data->failed = 0;
992 }
993
994 return ret;
995 }
996
997 static enum print_line_t
998 print_graph_return(struct ftrace_graph_ret *trace, struct trace_seq *s,
999 struct trace_entry *ent, struct trace_iterator *iter,
1000 u32 flags)
1001 {
1002 unsigned long long duration = trace->rettime - trace->calltime;
1003 struct fgraph_data *data = iter->private;
1004 pid_t pid = ent->pid;
1005 int cpu = iter->cpu;
1006 int func_match = 1;
1007 int ret;
1008 int i;
1009
1010 if (check_irq_return(iter, flags, trace->depth))
1011 return TRACE_TYPE_HANDLED;
1012
1013 if (data) {
1014 struct fgraph_cpu_data *cpu_data;
1015 int cpu = iter->cpu;
1016
1017 cpu_data = per_cpu_ptr(data->cpu_data, cpu);
1018
1019 /*
1020 * Comments display at + 1 to depth. This is the
1021 * return from a function, we now want the comments
1022 * to display at the same level of the bracket.
1023 */
1024 cpu_data->depth = trace->depth - 1;
1025
1026 if (trace->depth < FTRACE_RETFUNC_DEPTH) {
1027 if (cpu_data->enter_funcs[trace->depth] != trace->func)
1028 func_match = 0;
1029 cpu_data->enter_funcs[trace->depth] = 0;
1030 }
1031 }
1032
1033 if (print_graph_prologue(iter, s, 0, 0, flags))
1034 return TRACE_TYPE_PARTIAL_LINE;
1035
1036 /* Overhead */
1037 ret = print_graph_overhead(duration, s, flags);
1038 if (!ret)
1039 return TRACE_TYPE_PARTIAL_LINE;
1040
1041 /* Duration */
1042 if (flags & TRACE_GRAPH_PRINT_DURATION) {
1043 ret = print_graph_duration(duration, s);
1044 if (ret == TRACE_TYPE_PARTIAL_LINE)
1045 return TRACE_TYPE_PARTIAL_LINE;
1046 }
1047
1048 /* Closing brace */
1049 for (i = 0; i < trace->depth * TRACE_GRAPH_INDENT; i++) {
1050 ret = trace_seq_printf(s, " ");
1051 if (!ret)
1052 return TRACE_TYPE_PARTIAL_LINE;
1053 }
1054
1055 /*
1056 * If the return function does not have a matching entry,
1057 * then the entry was lost. Instead of just printing
1058 * the '}' and letting the user guess what function this
1059 * belongs to, write out the function name.
1060 */
1061 if (func_match) {
1062 ret = trace_seq_printf(s, "}\n");
1063 if (!ret)
1064 return TRACE_TYPE_PARTIAL_LINE;
1065 } else {
1066 ret = trace_seq_printf(s, "} /* %ps */\n", (void *)trace->func);
1067 if (!ret)
1068 return TRACE_TYPE_PARTIAL_LINE;
1069 }
1070
1071 /* Overrun */
1072 if (flags & TRACE_GRAPH_PRINT_OVERRUN) {
1073 ret = trace_seq_printf(s, " (Overruns: %lu)\n",
1074 trace->overrun);
1075 if (!ret)
1076 return TRACE_TYPE_PARTIAL_LINE;
1077 }
1078
1079 ret = print_graph_irq(iter, trace->func, TRACE_GRAPH_RET,
1080 cpu, pid, flags);
1081 if (ret == TRACE_TYPE_PARTIAL_LINE)
1082 return TRACE_TYPE_PARTIAL_LINE;
1083
1084 return TRACE_TYPE_HANDLED;
1085 }
1086
1087 static enum print_line_t
1088 print_graph_comment(struct trace_seq *s, struct trace_entry *ent,
1089 struct trace_iterator *iter, u32 flags)
1090 {
1091 unsigned long sym_flags = (trace_flags & TRACE_ITER_SYM_MASK);
1092 struct fgraph_data *data = iter->private;
1093 struct trace_event *event;
1094 int depth = 0;
1095 int ret;
1096 int i;
1097
1098 if (data)
1099 depth = per_cpu_ptr(data->cpu_data, iter->cpu)->depth;
1100
1101 if (print_graph_prologue(iter, s, 0, 0, flags))
1102 return TRACE_TYPE_PARTIAL_LINE;
1103
1104 /* No overhead */
1105 ret = print_graph_overhead(-1, s, flags);
1106 if (!ret)
1107 return TRACE_TYPE_PARTIAL_LINE;
1108
1109 /* No time */
1110 if (flags & TRACE_GRAPH_PRINT_DURATION) {
1111 ret = trace_seq_printf(s, " | ");
1112 if (!ret)
1113 return TRACE_TYPE_PARTIAL_LINE;
1114 }
1115
1116 /* Indentation */
1117 if (depth > 0)
1118 for (i = 0; i < (depth + 1) * TRACE_GRAPH_INDENT; i++) {
1119 ret = trace_seq_printf(s, " ");
1120 if (!ret)
1121 return TRACE_TYPE_PARTIAL_LINE;
1122 }
1123
1124 /* The comment */
1125 ret = trace_seq_printf(s, "/* ");
1126 if (!ret)
1127 return TRACE_TYPE_PARTIAL_LINE;
1128
1129 switch (iter->ent->type) {
1130 case TRACE_BPRINT:
1131 ret = trace_print_bprintk_msg_only(iter);
1132 if (ret != TRACE_TYPE_HANDLED)
1133 return ret;
1134 break;
1135 case TRACE_PRINT:
1136 ret = trace_print_printk_msg_only(iter);
1137 if (ret != TRACE_TYPE_HANDLED)
1138 return ret;
1139 break;
1140 default:
1141 event = ftrace_find_event(ent->type);
1142 if (!event)
1143 return TRACE_TYPE_UNHANDLED;
1144
1145 ret = event->funcs->trace(iter, sym_flags, event);
1146 if (ret != TRACE_TYPE_HANDLED)
1147 return ret;
1148 }
1149
1150 /* Strip ending newline */
1151 if (s->buffer[s->len - 1] == '\n') {
1152 s->buffer[s->len - 1] = '\0';
1153 s->len--;
1154 }
1155
1156 ret = trace_seq_printf(s, " */\n");
1157 if (!ret)
1158 return TRACE_TYPE_PARTIAL_LINE;
1159
1160 return TRACE_TYPE_HANDLED;
1161 }
1162
1163
1164 enum print_line_t
1165 print_graph_function_flags(struct trace_iterator *iter, u32 flags)
1166 {
1167 struct ftrace_graph_ent_entry *field;
1168 struct fgraph_data *data = iter->private;
1169 struct trace_entry *entry = iter->ent;
1170 struct trace_seq *s = &iter->seq;
1171 int cpu = iter->cpu;
1172 int ret;
1173
1174 if (data && per_cpu_ptr(data->cpu_data, cpu)->ignore) {
1175 per_cpu_ptr(data->cpu_data, cpu)->ignore = 0;
1176 return TRACE_TYPE_HANDLED;
1177 }
1178
1179 /*
1180 * If the last output failed, there's a possibility we need
1181 * to print out the missing entry which would never go out.
1182 */
1183 if (data && data->failed) {
1184 field = &data->ent;
1185 iter->cpu = data->cpu;
1186 ret = print_graph_entry(field, s, iter, flags);
1187 if (ret == TRACE_TYPE_HANDLED && iter->cpu != cpu) {
1188 per_cpu_ptr(data->cpu_data, iter->cpu)->ignore = 1;
1189 ret = TRACE_TYPE_NO_CONSUME;
1190 }
1191 iter->cpu = cpu;
1192 return ret;
1193 }
1194
1195 switch (entry->type) {
1196 case TRACE_GRAPH_ENT: {
1197 /*
1198 * print_graph_entry() may consume the current event,
1199 * thus @field may become invalid, so we need to save it.
1200 * sizeof(struct ftrace_graph_ent_entry) is very small,
1201 * it can be safely saved at the stack.
1202 */
1203 struct ftrace_graph_ent_entry saved;
1204 trace_assign_type(field, entry);
1205 saved = *field;
1206 return print_graph_entry(&saved, s, iter, flags);
1207 }
1208 case TRACE_GRAPH_RET: {
1209 struct ftrace_graph_ret_entry *field;
1210 trace_assign_type(field, entry);
1211 return print_graph_return(&field->ret, s, entry, iter, flags);
1212 }
1213 case TRACE_STACK:
1214 case TRACE_FN:
1215 /* dont trace stack and functions as comments */
1216 return TRACE_TYPE_UNHANDLED;
1217
1218 default:
1219 return print_graph_comment(s, entry, iter, flags);
1220 }
1221
1222 return TRACE_TYPE_HANDLED;
1223 }
1224
1225 static enum print_line_t
1226 print_graph_function(struct trace_iterator *iter)
1227 {
1228 return print_graph_function_flags(iter, tracer_flags.val);
1229 }
1230
1231 static enum print_line_t
1232 print_graph_function_event(struct trace_iterator *iter, int flags,
1233 struct trace_event *event)
1234 {
1235 return print_graph_function(iter);
1236 }
1237
1238 static void print_lat_header(struct seq_file *s, u32 flags)
1239 {
1240 static const char spaces[] = " " /* 16 spaces */
1241 " " /* 4 spaces */
1242 " "; /* 17 spaces */
1243 int size = 0;
1244
1245 if (flags & TRACE_GRAPH_PRINT_ABS_TIME)
1246 size += 16;
1247 if (flags & TRACE_GRAPH_PRINT_CPU)
1248 size += 4;
1249 if (flags & TRACE_GRAPH_PRINT_PROC)
1250 size += 17;
1251
1252 seq_printf(s, "#%.*s _-----=> irqs-off \n", size, spaces);
1253 seq_printf(s, "#%.*s / _----=> need-resched \n", size, spaces);
1254 seq_printf(s, "#%.*s| / _---=> hardirq/softirq \n", size, spaces);
1255 seq_printf(s, "#%.*s|| / _--=> preempt-depth \n", size, spaces);
1256 seq_printf(s, "#%.*s||| / _-=> lock-depth \n", size, spaces);
1257 seq_printf(s, "#%.*s|||| / \n", size, spaces);
1258 }
1259
1260 void print_graph_headers_flags(struct seq_file *s, u32 flags)
1261 {
1262 int lat = trace_flags & TRACE_ITER_LATENCY_FMT;
1263
1264 if (lat)
1265 print_lat_header(s, flags);
1266
1267 /* 1st line */
1268 seq_printf(s, "#");
1269 if (flags & TRACE_GRAPH_PRINT_ABS_TIME)
1270 seq_printf(s, " TIME ");
1271 if (flags & TRACE_GRAPH_PRINT_CPU)
1272 seq_printf(s, " CPU");
1273 if (flags & TRACE_GRAPH_PRINT_PROC)
1274 seq_printf(s, " TASK/PID ");
1275 if (lat)
1276 seq_printf(s, "|||||");
1277 if (flags & TRACE_GRAPH_PRINT_DURATION)
1278 seq_printf(s, " DURATION ");
1279 seq_printf(s, " FUNCTION CALLS\n");
1280
1281 /* 2nd line */
1282 seq_printf(s, "#");
1283 if (flags & TRACE_GRAPH_PRINT_ABS_TIME)
1284 seq_printf(s, " | ");
1285 if (flags & TRACE_GRAPH_PRINT_CPU)
1286 seq_printf(s, " | ");
1287 if (flags & TRACE_GRAPH_PRINT_PROC)
1288 seq_printf(s, " | | ");
1289 if (lat)
1290 seq_printf(s, "|||||");
1291 if (flags & TRACE_GRAPH_PRINT_DURATION)
1292 seq_printf(s, " | | ");
1293 seq_printf(s, " | | | |\n");
1294 }
1295
1296 void print_graph_headers(struct seq_file *s)
1297 {
1298 print_graph_headers_flags(s, tracer_flags.val);
1299 }
1300
1301 void graph_trace_open(struct trace_iterator *iter)
1302 {
1303 /* pid and depth on the last trace processed */
1304 struct fgraph_data *data;
1305 int cpu;
1306
1307 iter->private = NULL;
1308
1309 data = kzalloc(sizeof(*data), GFP_KERNEL);
1310 if (!data)
1311 goto out_err;
1312
1313 data->cpu_data = alloc_percpu(struct fgraph_cpu_data);
1314 if (!data->cpu_data)
1315 goto out_err_free;
1316
1317 for_each_possible_cpu(cpu) {
1318 pid_t *pid = &(per_cpu_ptr(data->cpu_data, cpu)->last_pid);
1319 int *depth = &(per_cpu_ptr(data->cpu_data, cpu)->depth);
1320 int *ignore = &(per_cpu_ptr(data->cpu_data, cpu)->ignore);
1321 int *depth_irq = &(per_cpu_ptr(data->cpu_data, cpu)->depth_irq);
1322
1323 *pid = -1;
1324 *depth = 0;
1325 *ignore = 0;
1326 *depth_irq = -1;
1327 }
1328
1329 iter->private = data;
1330
1331 return;
1332
1333 out_err_free:
1334 kfree(data);
1335 out_err:
1336 pr_warning("function graph tracer: not enough memory\n");
1337 }
1338
1339 void graph_trace_close(struct trace_iterator *iter)
1340 {
1341 struct fgraph_data *data = iter->private;
1342
1343 if (data) {
1344 free_percpu(data->cpu_data);
1345 kfree(data);
1346 }
1347 }
1348
1349 static int func_graph_set_flag(u32 old_flags, u32 bit, int set)
1350 {
1351 if (bit == TRACE_GRAPH_PRINT_IRQS)
1352 ftrace_graph_skip_irqs = !set;
1353
1354 return 0;
1355 }
1356
1357 static struct trace_event_functions graph_functions = {
1358 .trace = print_graph_function_event,
1359 };
1360
1361 static struct trace_event graph_trace_entry_event = {
1362 .type = TRACE_GRAPH_ENT,
1363 .funcs = &graph_functions,
1364 };
1365
1366 static struct trace_event graph_trace_ret_event = {
1367 .type = TRACE_GRAPH_RET,
1368 .funcs = &graph_functions
1369 };
1370
1371 static struct tracer graph_trace __read_mostly = {
1372 .name = "function_graph",
1373 .open = graph_trace_open,
1374 .pipe_open = graph_trace_open,
1375 .close = graph_trace_close,
1376 .pipe_close = graph_trace_close,
1377 .wait_pipe = poll_wait_pipe,
1378 .init = graph_trace_init,
1379 .reset = graph_trace_reset,
1380 .print_line = print_graph_function,
1381 .print_header = print_graph_headers,
1382 .flags = &tracer_flags,
1383 .set_flag = func_graph_set_flag,
1384 #ifdef CONFIG_FTRACE_SELFTEST
1385 .selftest = trace_selftest_startup_function_graph,
1386 #endif
1387 };
1388
1389 static __init int init_graph_trace(void)
1390 {
1391 max_bytes_for_cpu = snprintf(NULL, 0, "%d", nr_cpu_ids - 1);
1392
1393 if (!register_ftrace_event(&graph_trace_entry_event)) {
1394 pr_warning("Warning: could not register graph trace events\n");
1395 return 1;
1396 }
1397
1398 if (!register_ftrace_event(&graph_trace_ret_event)) {
1399 pr_warning("Warning: could not register graph trace events\n");
1400 return 1;
1401 }
1402
1403 return register_tracer(&graph_trace);
1404 }
1405
1406 device_initcall(init_graph_trace);
Linux kernel - Deliverables
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