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>
9 #include <linux/debugfs.h>
10 #include <linux/uaccess.h>
11 #include <linux/ftrace.h>
15 #include "trace_output.h"
17 #define TRACE_GRAPH_INDENT 2
20 #define TRACE_GRAPH_PRINT_OVERRUN 0x1
21 #define TRACE_GRAPH_PRINT_CPU 0x2
22 #define TRACE_GRAPH_PRINT_OVERHEAD 0x4
23 #define TRACE_GRAPH_PRINT_PROC 0x8
24 #define TRACE_GRAPH_PRINT_DURATION 0x10
25 #define TRACE_GRAPH_PRINT_ABS_TIME 0X20
27 static struct tracer_opt trace_opts[] = {
28 /* Display overruns? (for self-debug purpose) */
29 { TRACER_OPT(funcgraph-overrun, TRACE_GRAPH_PRINT_OVERRUN) },
31 { TRACER_OPT(funcgraph-cpu, TRACE_GRAPH_PRINT_CPU) },
32 /* Display Overhead ? */
33 { TRACER_OPT(funcgraph-overhead, TRACE_GRAPH_PRINT_OVERHEAD) },
34 /* Display proc name/pid */
35 { TRACER_OPT(funcgraph-proc, TRACE_GRAPH_PRINT_PROC) },
36 /* Display duration of execution */
37 { TRACER_OPT(funcgraph-duration, TRACE_GRAPH_PRINT_DURATION) },
38 /* Display absolute time of an entry */
39 { TRACER_OPT(funcgraph-abstime, TRACE_GRAPH_PRINT_ABS_TIME) },
43 static struct tracer_flags tracer_flags = {
44 /* Don't display overruns and proc by default */
45 .val = TRACE_GRAPH_PRINT_CPU | TRACE_GRAPH_PRINT_OVERHEAD |
46 TRACE_GRAPH_PRINT_DURATION,
50 /* pid on the last trace processed */
53 /* Add a function return address to the trace stack on thread info.*/
55 ftrace_push_return_trace(unsigned long ret, unsigned long long time,
56 unsigned long func, int *depth)
60 if (!current->ret_stack)
63 /* The return trace stack is full */
64 if (current->curr_ret_stack == FTRACE_RETFUNC_DEPTH - 1) {
65 atomic_inc(¤t->trace_overrun);
69 index = ++current->curr_ret_stack;
71 current->ret_stack[index].ret = ret;
72 current->ret_stack[index].func = func;
73 current->ret_stack[index].calltime = time;
79 /* Retrieve a function return address to the trace stack on thread info.*/
81 ftrace_pop_return_trace(struct ftrace_graph_ret *trace, unsigned long *ret)
85 index = current->curr_ret_stack;
87 if (unlikely(index < 0)) {
90 /* Might as well panic, otherwise we have no where to go */
91 *ret = (unsigned long)panic;
95 *ret = current->ret_stack[index].ret;
96 trace->func = current->ret_stack[index].func;
97 trace->calltime = current->ret_stack[index].calltime;
98 trace->overrun = atomic_read(¤t->trace_overrun);
101 current->curr_ret_stack--;
106 * Send the trace to the ring-buffer.
107 * @return the original return address.
109 unsigned long ftrace_return_to_handler(void)
111 struct ftrace_graph_ret trace;
114 ftrace_pop_return_trace(&trace, &ret);
115 trace.rettime = trace_clock_local();
116 ftrace_graph_return(&trace);
118 if (unlikely(!ret)) {
121 /* Might as well panic. What else to do? */
122 ret = (unsigned long)panic;
128 static int graph_trace_init(struct trace_array *tr)
130 int ret = register_ftrace_graph(&trace_graph_return,
134 tracing_start_cmdline_record();
139 static void graph_trace_reset(struct trace_array *tr)
141 tracing_stop_cmdline_record();
142 unregister_ftrace_graph();
145 static inline int log10_cpu(int nb)
154 static enum print_line_t
155 print_graph_cpu(struct trace_seq *s, int cpu)
159 int log10_this = log10_cpu(cpu);
160 int log10_all = log10_cpu(cpumask_weight(cpu_online_mask));
164 * Start with a space character - to make it stand out
165 * to the right a bit when trace output is pasted into
168 ret = trace_seq_printf(s, " ");
171 * Tricky - we space the CPU field according to the max
172 * number of online CPUs. On a 2-cpu system it would take
173 * a maximum of 1 digit - on a 128 cpu system it would
174 * take up to 3 digits:
176 for (i = 0; i < log10_all - log10_this; i++) {
177 ret = trace_seq_printf(s, " ");
179 return TRACE_TYPE_PARTIAL_LINE;
181 ret = trace_seq_printf(s, "%d) ", cpu);
183 return TRACE_TYPE_PARTIAL_LINE;
185 return TRACE_TYPE_HANDLED;
188 #define TRACE_GRAPH_PROCINFO_LENGTH 14
190 static enum print_line_t
191 print_graph_proc(struct trace_seq *s, pid_t pid)
198 /* sign + log10(MAX_INT) + '\0' */
201 strncpy(comm, trace_find_cmdline(pid), 7);
203 sprintf(pid_str, "%d", pid);
205 /* 1 stands for the "-" character */
206 len = strlen(comm) + strlen(pid_str) + 1;
208 if (len < TRACE_GRAPH_PROCINFO_LENGTH)
209 spaces = TRACE_GRAPH_PROCINFO_LENGTH - len;
211 /* First spaces to align center */
212 for (i = 0; i < spaces / 2; i++) {
213 ret = trace_seq_printf(s, " ");
215 return TRACE_TYPE_PARTIAL_LINE;
218 ret = trace_seq_printf(s, "%s-%s", comm, pid_str);
220 return TRACE_TYPE_PARTIAL_LINE;
222 /* Last spaces to align center */
223 for (i = 0; i < spaces - (spaces / 2); i++) {
224 ret = trace_seq_printf(s, " ");
226 return TRACE_TYPE_PARTIAL_LINE;
228 return TRACE_TYPE_HANDLED;
232 /* If the pid changed since the last trace, output this event */
233 static enum print_line_t
234 verif_pid(struct trace_seq *s, pid_t pid, int cpu, pid_t *last_pids_cpu)
241 return TRACE_TYPE_HANDLED;
243 last_pid = per_cpu_ptr(last_pids_cpu, cpu);
245 if (*last_pid == pid)
246 return TRACE_TYPE_HANDLED;
248 prev_pid = *last_pid;
252 return TRACE_TYPE_HANDLED;
254 * Context-switch trace line:
256 ------------------------------------------
257 | 1) migration/0--1 => sshd-1755
258 ------------------------------------------
261 ret = trace_seq_printf(s,
262 " ------------------------------------------\n");
264 return TRACE_TYPE_PARTIAL_LINE;
266 ret = print_graph_cpu(s, cpu);
267 if (ret == TRACE_TYPE_PARTIAL_LINE)
268 return TRACE_TYPE_PARTIAL_LINE;
270 ret = print_graph_proc(s, prev_pid);
271 if (ret == TRACE_TYPE_PARTIAL_LINE)
272 return TRACE_TYPE_PARTIAL_LINE;
274 ret = trace_seq_printf(s, " => ");
276 return TRACE_TYPE_PARTIAL_LINE;
278 ret = print_graph_proc(s, pid);
279 if (ret == TRACE_TYPE_PARTIAL_LINE)
280 return TRACE_TYPE_PARTIAL_LINE;
282 ret = trace_seq_printf(s,
283 "\n ------------------------------------------\n\n");
285 return TRACE_TYPE_PARTIAL_LINE;
287 return TRACE_TYPE_HANDLED;
290 static struct ftrace_graph_ret_entry *
291 get_return_for_leaf(struct trace_iterator *iter,
292 struct ftrace_graph_ent_entry *curr)
294 struct ring_buffer_iter *ring_iter;
295 struct ring_buffer_event *event;
296 struct ftrace_graph_ret_entry *next;
298 ring_iter = iter->buffer_iter[iter->cpu];
300 /* First peek to compare current entry and the next one */
302 event = ring_buffer_iter_peek(ring_iter, NULL);
304 /* We need to consume the current entry to see the next one */
305 ring_buffer_consume(iter->tr->buffer, iter->cpu, NULL);
306 event = ring_buffer_peek(iter->tr->buffer, iter->cpu,
313 next = ring_buffer_event_data(event);
315 if (next->ent.type != TRACE_GRAPH_RET)
318 if (curr->ent.pid != next->ent.pid ||
319 curr->graph_ent.func != next->ret.func)
322 /* this is a leaf, now advance the iterator */
324 ring_buffer_read(ring_iter, NULL);
329 /* Signal a overhead of time execution to the output */
331 print_graph_overhead(unsigned long long duration, struct trace_seq *s)
333 /* If duration disappear, we don't need anything */
334 if (!(tracer_flags.val & TRACE_GRAPH_PRINT_DURATION))
337 /* Non nested entry or return */
339 return trace_seq_printf(s, " ");
341 if (tracer_flags.val & TRACE_GRAPH_PRINT_OVERHEAD) {
342 /* Duration exceeded 100 msecs */
343 if (duration > 100000ULL)
344 return trace_seq_printf(s, "! ");
346 /* Duration exceeded 10 msecs */
347 if (duration > 10000ULL)
348 return trace_seq_printf(s, "+ ");
351 return trace_seq_printf(s, " ");
354 static int print_graph_abs_time(u64 t, struct trace_seq *s)
356 unsigned long usecs_rem;
358 usecs_rem = do_div(t, NSEC_PER_SEC);
361 return trace_seq_printf(s, "%5lu.%06lu | ",
362 (unsigned long)t, usecs_rem);
365 static enum print_line_t
366 print_graph_irq(struct trace_iterator *iter, unsigned long addr,
367 enum trace_type type, int cpu, pid_t pid)
370 struct trace_seq *s = &iter->seq;
372 if (addr < (unsigned long)__irqentry_text_start ||
373 addr >= (unsigned long)__irqentry_text_end)
374 return TRACE_TYPE_UNHANDLED;
377 if (tracer_flags.val & TRACE_GRAPH_PRINT_ABS_TIME) {
378 ret = print_graph_abs_time(iter->ts, s);
380 return TRACE_TYPE_PARTIAL_LINE;
384 if (tracer_flags.val & TRACE_GRAPH_PRINT_CPU) {
385 ret = print_graph_cpu(s, cpu);
386 if (ret == TRACE_TYPE_PARTIAL_LINE)
387 return TRACE_TYPE_PARTIAL_LINE;
390 if (tracer_flags.val & TRACE_GRAPH_PRINT_PROC) {
391 ret = print_graph_proc(s, pid);
392 if (ret == TRACE_TYPE_PARTIAL_LINE)
393 return TRACE_TYPE_PARTIAL_LINE;
394 ret = trace_seq_printf(s, " | ");
396 return TRACE_TYPE_PARTIAL_LINE;
400 ret = print_graph_overhead(-1, s);
402 return TRACE_TYPE_PARTIAL_LINE;
404 if (type == TRACE_GRAPH_ENT)
405 ret = trace_seq_printf(s, "==========>");
407 ret = trace_seq_printf(s, "<==========");
410 return TRACE_TYPE_PARTIAL_LINE;
412 /* Don't close the duration column if haven't one */
413 if (tracer_flags.val & TRACE_GRAPH_PRINT_DURATION)
414 trace_seq_printf(s, " |");
415 ret = trace_seq_printf(s, "\n");
418 return TRACE_TYPE_PARTIAL_LINE;
419 return TRACE_TYPE_HANDLED;
422 static enum print_line_t
423 print_graph_duration(unsigned long long duration, struct trace_seq *s)
425 unsigned long nsecs_rem = do_div(duration, 1000);
426 /* log10(ULONG_MAX) + '\0' */
432 sprintf(msecs_str, "%lu", (unsigned long) duration);
435 ret = trace_seq_printf(s, "%s", msecs_str);
437 return TRACE_TYPE_PARTIAL_LINE;
439 len = strlen(msecs_str);
441 /* Print nsecs (we don't want to exceed 7 numbers) */
443 snprintf(nsecs_str, 8 - len, "%03lu", nsecs_rem);
444 ret = trace_seq_printf(s, ".%s", nsecs_str);
446 return TRACE_TYPE_PARTIAL_LINE;
447 len += strlen(nsecs_str);
450 ret = trace_seq_printf(s, " us ");
452 return TRACE_TYPE_PARTIAL_LINE;
454 /* Print remaining spaces to fit the row's width */
455 for (i = len; i < 7; i++) {
456 ret = trace_seq_printf(s, " ");
458 return TRACE_TYPE_PARTIAL_LINE;
461 ret = trace_seq_printf(s, "| ");
463 return TRACE_TYPE_PARTIAL_LINE;
464 return TRACE_TYPE_HANDLED;
468 /* Case of a leaf function on its call entry */
469 static enum print_line_t
470 print_graph_entry_leaf(struct trace_iterator *iter,
471 struct ftrace_graph_ent_entry *entry,
472 struct ftrace_graph_ret_entry *ret_entry, struct trace_seq *s)
474 struct ftrace_graph_ret *graph_ret;
475 struct ftrace_graph_ent *call;
476 unsigned long long duration;
480 graph_ret = &ret_entry->ret;
481 call = &entry->graph_ent;
482 duration = graph_ret->rettime - graph_ret->calltime;
485 ret = print_graph_overhead(duration, s);
487 return TRACE_TYPE_PARTIAL_LINE;
490 if (tracer_flags.val & TRACE_GRAPH_PRINT_DURATION) {
491 ret = print_graph_duration(duration, s);
492 if (ret == TRACE_TYPE_PARTIAL_LINE)
493 return TRACE_TYPE_PARTIAL_LINE;
497 for (i = 0; i < call->depth * TRACE_GRAPH_INDENT; i++) {
498 ret = trace_seq_printf(s, " ");
500 return TRACE_TYPE_PARTIAL_LINE;
503 ret = seq_print_ip_sym(s, call->func, 0);
505 return TRACE_TYPE_PARTIAL_LINE;
507 ret = trace_seq_printf(s, "();\n");
509 return TRACE_TYPE_PARTIAL_LINE;
511 return TRACE_TYPE_HANDLED;
514 static enum print_line_t
515 print_graph_entry_nested(struct ftrace_graph_ent_entry *entry,
516 struct trace_seq *s, pid_t pid, int cpu)
520 struct ftrace_graph_ent *call = &entry->graph_ent;
523 ret = print_graph_overhead(-1, s);
525 return TRACE_TYPE_PARTIAL_LINE;
528 if (tracer_flags.val & TRACE_GRAPH_PRINT_DURATION) {
529 ret = trace_seq_printf(s, " | ");
531 return TRACE_TYPE_PARTIAL_LINE;
535 for (i = 0; i < call->depth * TRACE_GRAPH_INDENT; i++) {
536 ret = trace_seq_printf(s, " ");
538 return TRACE_TYPE_PARTIAL_LINE;
541 ret = seq_print_ip_sym(s, call->func, 0);
543 return TRACE_TYPE_PARTIAL_LINE;
545 ret = trace_seq_printf(s, "() {\n");
547 return TRACE_TYPE_PARTIAL_LINE;
550 * we already consumed the current entry to check the next one
551 * and see if this is a leaf.
553 return TRACE_TYPE_NO_CONSUME;
556 static enum print_line_t
557 print_graph_entry(struct ftrace_graph_ent_entry *field, struct trace_seq *s,
558 struct trace_iterator *iter)
562 pid_t *last_entry = iter->private;
563 struct trace_entry *ent = iter->ent;
564 struct ftrace_graph_ent *call = &field->graph_ent;
565 struct ftrace_graph_ret_entry *leaf_ret;
568 if (verif_pid(s, ent->pid, cpu, last_entry) == TRACE_TYPE_PARTIAL_LINE)
569 return TRACE_TYPE_PARTIAL_LINE;
572 ret = print_graph_irq(iter, call->func, TRACE_GRAPH_ENT, cpu, ent->pid);
573 if (ret == TRACE_TYPE_PARTIAL_LINE)
574 return TRACE_TYPE_PARTIAL_LINE;
577 if (tracer_flags.val & TRACE_GRAPH_PRINT_ABS_TIME) {
578 ret = print_graph_abs_time(iter->ts, s);
580 return TRACE_TYPE_PARTIAL_LINE;
584 if (tracer_flags.val & TRACE_GRAPH_PRINT_CPU) {
585 ret = print_graph_cpu(s, cpu);
586 if (ret == TRACE_TYPE_PARTIAL_LINE)
587 return TRACE_TYPE_PARTIAL_LINE;
591 if (tracer_flags.val & TRACE_GRAPH_PRINT_PROC) {
592 ret = print_graph_proc(s, ent->pid);
593 if (ret == TRACE_TYPE_PARTIAL_LINE)
594 return TRACE_TYPE_PARTIAL_LINE;
596 ret = trace_seq_printf(s, " | ");
598 return TRACE_TYPE_PARTIAL_LINE;
601 leaf_ret = get_return_for_leaf(iter, field);
603 return print_graph_entry_leaf(iter, field, leaf_ret, s);
605 return print_graph_entry_nested(field, s, iter->ent->pid, cpu);
609 static enum print_line_t
610 print_graph_return(struct ftrace_graph_ret *trace, struct trace_seq *s,
611 struct trace_entry *ent, struct trace_iterator *iter)
616 pid_t *last_pid = iter->private, pid = ent->pid;
617 unsigned long long duration = trace->rettime - trace->calltime;
620 if (verif_pid(s, pid, cpu, last_pid) == TRACE_TYPE_PARTIAL_LINE)
621 return TRACE_TYPE_PARTIAL_LINE;
624 if (tracer_flags.val & TRACE_GRAPH_PRINT_ABS_TIME) {
625 ret = print_graph_abs_time(iter->ts, s);
627 return TRACE_TYPE_PARTIAL_LINE;
631 if (tracer_flags.val & TRACE_GRAPH_PRINT_CPU) {
632 ret = print_graph_cpu(s, cpu);
633 if (ret == TRACE_TYPE_PARTIAL_LINE)
634 return TRACE_TYPE_PARTIAL_LINE;
638 if (tracer_flags.val & TRACE_GRAPH_PRINT_PROC) {
639 ret = print_graph_proc(s, ent->pid);
640 if (ret == TRACE_TYPE_PARTIAL_LINE)
641 return TRACE_TYPE_PARTIAL_LINE;
643 ret = trace_seq_printf(s, " | ");
645 return TRACE_TYPE_PARTIAL_LINE;
649 ret = print_graph_overhead(duration, s);
651 return TRACE_TYPE_PARTIAL_LINE;
654 if (tracer_flags.val & TRACE_GRAPH_PRINT_DURATION) {
655 ret = print_graph_duration(duration, s);
656 if (ret == TRACE_TYPE_PARTIAL_LINE)
657 return TRACE_TYPE_PARTIAL_LINE;
661 for (i = 0; i < trace->depth * TRACE_GRAPH_INDENT; i++) {
662 ret = trace_seq_printf(s, " ");
664 return TRACE_TYPE_PARTIAL_LINE;
667 ret = trace_seq_printf(s, "}\n");
669 return TRACE_TYPE_PARTIAL_LINE;
672 if (tracer_flags.val & TRACE_GRAPH_PRINT_OVERRUN) {
673 ret = trace_seq_printf(s, " (Overruns: %lu)\n",
676 return TRACE_TYPE_PARTIAL_LINE;
679 ret = print_graph_irq(iter, trace->func, TRACE_GRAPH_RET, cpu, pid);
680 if (ret == TRACE_TYPE_PARTIAL_LINE)
681 return TRACE_TYPE_PARTIAL_LINE;
683 return TRACE_TYPE_HANDLED;
686 static enum print_line_t
687 print_graph_comment(struct print_entry *trace, struct trace_seq *s,
688 struct trace_entry *ent, struct trace_iterator *iter)
693 pid_t *last_pid = iter->private;
696 if (verif_pid(s, ent->pid, cpu, last_pid) == TRACE_TYPE_PARTIAL_LINE)
697 return TRACE_TYPE_PARTIAL_LINE;
700 if (tracer_flags.val & TRACE_GRAPH_PRINT_ABS_TIME) {
701 ret = print_graph_abs_time(iter->ts, s);
703 return TRACE_TYPE_PARTIAL_LINE;
707 if (tracer_flags.val & TRACE_GRAPH_PRINT_CPU) {
708 ret = print_graph_cpu(s, cpu);
709 if (ret == TRACE_TYPE_PARTIAL_LINE)
710 return TRACE_TYPE_PARTIAL_LINE;
714 if (tracer_flags.val & TRACE_GRAPH_PRINT_PROC) {
715 ret = print_graph_proc(s, ent->pid);
716 if (ret == TRACE_TYPE_PARTIAL_LINE)
717 return TRACE_TYPE_PARTIAL_LINE;
719 ret = trace_seq_printf(s, " | ");
721 return TRACE_TYPE_PARTIAL_LINE;
725 ret = print_graph_overhead(-1, s);
727 return TRACE_TYPE_PARTIAL_LINE;
730 if (tracer_flags.val & TRACE_GRAPH_PRINT_DURATION) {
731 ret = trace_seq_printf(s, " | ");
733 return TRACE_TYPE_PARTIAL_LINE;
737 if (trace->depth > 0)
738 for (i = 0; i < (trace->depth + 1) * TRACE_GRAPH_INDENT; i++) {
739 ret = trace_seq_printf(s, " ");
741 return TRACE_TYPE_PARTIAL_LINE;
745 ret = trace_seq_printf(s, "/* %s", trace->buf);
747 return TRACE_TYPE_PARTIAL_LINE;
749 /* Strip ending newline */
750 if (s->buffer[s->len - 1] == '\n') {
751 s->buffer[s->len - 1] = '\0';
755 ret = trace_seq_printf(s, " */\n");
757 return TRACE_TYPE_PARTIAL_LINE;
759 return TRACE_TYPE_HANDLED;
764 print_graph_function(struct trace_iterator *iter)
766 struct trace_seq *s = &iter->seq;
767 struct trace_entry *entry = iter->ent;
769 switch (entry->type) {
770 case TRACE_GRAPH_ENT: {
771 struct ftrace_graph_ent_entry *field;
772 trace_assign_type(field, entry);
773 return print_graph_entry(field, s, iter);
775 case TRACE_GRAPH_RET: {
776 struct ftrace_graph_ret_entry *field;
777 trace_assign_type(field, entry);
778 return print_graph_return(&field->ret, s, entry, iter);
781 struct print_entry *field;
782 trace_assign_type(field, entry);
783 return print_graph_comment(field, s, entry, iter);
786 return TRACE_TYPE_UNHANDLED;
790 static void print_graph_headers(struct seq_file *s)
794 if (tracer_flags.val & TRACE_GRAPH_PRINT_ABS_TIME)
795 seq_printf(s, " TIME ");
796 if (tracer_flags.val & TRACE_GRAPH_PRINT_CPU)
797 seq_printf(s, "CPU");
798 if (tracer_flags.val & TRACE_GRAPH_PRINT_PROC)
799 seq_printf(s, " TASK/PID ");
800 if (tracer_flags.val & TRACE_GRAPH_PRINT_DURATION)
801 seq_printf(s, " DURATION ");
802 seq_printf(s, " FUNCTION CALLS\n");
806 if (tracer_flags.val & TRACE_GRAPH_PRINT_ABS_TIME)
807 seq_printf(s, " | ");
808 if (tracer_flags.val & TRACE_GRAPH_PRINT_CPU)
810 if (tracer_flags.val & TRACE_GRAPH_PRINT_PROC)
811 seq_printf(s, " | | ");
812 if (tracer_flags.val & TRACE_GRAPH_PRINT_DURATION)
813 seq_printf(s, " | | ");
814 seq_printf(s, " | | | |\n");
817 static void graph_trace_open(struct trace_iterator *iter)
819 /* pid on the last trace processed */
820 pid_t *last_pid = alloc_percpu(pid_t);
824 pr_warning("function graph tracer: not enough memory\n");
826 for_each_possible_cpu(cpu) {
827 pid_t *pid = per_cpu_ptr(last_pid, cpu);
831 iter->private = last_pid;
834 static void graph_trace_close(struct trace_iterator *iter)
836 percpu_free(iter->private);
839 static struct tracer graph_trace __read_mostly = {
840 .name = "function_graph",
841 .open = graph_trace_open,
842 .close = graph_trace_close,
843 .wait_pipe = poll_wait_pipe,
844 .init = graph_trace_init,
845 .reset = graph_trace_reset,
846 .print_line = print_graph_function,
847 .print_header = print_graph_headers,
848 .flags = &tracer_flags,
849 #ifdef CONFIG_FTRACE_SELFTEST
850 .selftest = trace_selftest_startup_function_graph,
854 static __init int init_graph_trace(void)
856 return register_tracer(&graph_trace);
859 device_initcall(init_graph_trace);