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"
22 #define TRACE_GRAPH_INDENT 2
25 #define TRACE_GRAPH_PRINT_OVERRUN 0x1
26 #define TRACE_GRAPH_PRINT_CPU 0x2
27 #define TRACE_GRAPH_PRINT_OVERHEAD 0x4
28 #define TRACE_GRAPH_PRINT_PROC 0x8
29 #define TRACE_GRAPH_PRINT_DURATION 0x10
30 #define TRACE_GRAPH_PRINT_ABS_TIME 0X20
32 static struct tracer_opt trace_opts[] = {
33 /* Display overruns? (for self-debug purpose) */
34 { TRACER_OPT(funcgraph-overrun, TRACE_GRAPH_PRINT_OVERRUN) },
36 { TRACER_OPT(funcgraph-cpu, TRACE_GRAPH_PRINT_CPU) },
37 /* Display Overhead ? */
38 { TRACER_OPT(funcgraph-overhead, TRACE_GRAPH_PRINT_OVERHEAD) },
39 /* Display proc name/pid */
40 { TRACER_OPT(funcgraph-proc, TRACE_GRAPH_PRINT_PROC) },
41 /* Display duration of execution */
42 { TRACER_OPT(funcgraph-duration, TRACE_GRAPH_PRINT_DURATION) },
43 /* Display absolute time of an entry */
44 { TRACER_OPT(funcgraph-abstime, TRACE_GRAPH_PRINT_ABS_TIME) },
48 static struct tracer_flags tracer_flags = {
49 /* Don't display overruns and proc by default */
50 .val = TRACE_GRAPH_PRINT_CPU | TRACE_GRAPH_PRINT_OVERHEAD |
51 TRACE_GRAPH_PRINT_DURATION,
55 /* pid on the last trace processed */
58 /* Add a function return address to the trace stack on thread info.*/
60 ftrace_push_return_trace(unsigned long ret, unsigned long func, int *depth)
62 unsigned long long calltime;
65 if (!current->ret_stack)
68 /* The return trace stack is full */
69 if (current->curr_ret_stack == FTRACE_RETFUNC_DEPTH - 1) {
70 atomic_inc(¤t->trace_overrun);
74 calltime = trace_clock_local();
76 index = ++current->curr_ret_stack;
78 current->ret_stack[index].ret = ret;
79 current->ret_stack[index].func = func;
80 current->ret_stack[index].calltime = calltime;
81 current->ret_stack[index].subtime = 0;
87 /* Retrieve a function return address to the trace stack on thread info.*/
89 ftrace_pop_return_trace(struct ftrace_graph_ret *trace, unsigned long *ret)
93 index = current->curr_ret_stack;
95 if (unlikely(index < 0)) {
98 /* Might as well panic, otherwise we have no where to go */
99 *ret = (unsigned long)panic;
103 *ret = current->ret_stack[index].ret;
104 trace->func = current->ret_stack[index].func;
105 trace->calltime = current->ret_stack[index].calltime;
106 trace->overrun = atomic_read(¤t->trace_overrun);
107 trace->depth = index;
111 * Send the trace to the ring-buffer.
112 * @return the original return address.
114 unsigned long ftrace_return_to_handler(void)
116 struct ftrace_graph_ret trace;
119 ftrace_pop_return_trace(&trace, &ret);
120 trace.rettime = trace_clock_local();
121 ftrace_graph_return(&trace);
123 current->curr_ret_stack--;
125 if (unlikely(!ret)) {
128 /* Might as well panic. What else to do? */
129 ret = (unsigned long)panic;
135 static int graph_trace_init(struct trace_array *tr)
137 int ret = register_ftrace_graph(&trace_graph_return,
141 tracing_start_cmdline_record();
146 static void graph_trace_reset(struct trace_array *tr)
148 tracing_stop_cmdline_record();
149 unregister_ftrace_graph();
152 static inline int log10_cpu(int nb)
161 static enum print_line_t
162 print_graph_cpu(struct trace_seq *s, int cpu)
166 int log10_this = log10_cpu(cpu);
167 int log10_all = log10_cpu(cpumask_weight(cpu_online_mask));
171 * Start with a space character - to make it stand out
172 * to the right a bit when trace output is pasted into
175 ret = trace_seq_printf(s, " ");
178 * Tricky - we space the CPU field according to the max
179 * number of online CPUs. On a 2-cpu system it would take
180 * a maximum of 1 digit - on a 128 cpu system it would
181 * take up to 3 digits:
183 for (i = 0; i < log10_all - log10_this; i++) {
184 ret = trace_seq_printf(s, " ");
186 return TRACE_TYPE_PARTIAL_LINE;
188 ret = trace_seq_printf(s, "%d) ", cpu);
190 return TRACE_TYPE_PARTIAL_LINE;
192 return TRACE_TYPE_HANDLED;
195 #define TRACE_GRAPH_PROCINFO_LENGTH 14
197 static enum print_line_t
198 print_graph_proc(struct trace_seq *s, pid_t pid)
200 char comm[TASK_COMM_LEN];
201 /* sign + log10(MAX_INT) + '\0' */
208 trace_find_cmdline(pid, comm);
210 sprintf(pid_str, "%d", pid);
212 /* 1 stands for the "-" character */
213 len = strlen(comm) + strlen(pid_str) + 1;
215 if (len < TRACE_GRAPH_PROCINFO_LENGTH)
216 spaces = TRACE_GRAPH_PROCINFO_LENGTH - len;
218 /* First spaces to align center */
219 for (i = 0; i < spaces / 2; i++) {
220 ret = trace_seq_printf(s, " ");
222 return TRACE_TYPE_PARTIAL_LINE;
225 ret = trace_seq_printf(s, "%s-%s", comm, pid_str);
227 return TRACE_TYPE_PARTIAL_LINE;
229 /* Last spaces to align center */
230 for (i = 0; i < spaces - (spaces / 2); i++) {
231 ret = trace_seq_printf(s, " ");
233 return TRACE_TYPE_PARTIAL_LINE;
235 return TRACE_TYPE_HANDLED;
239 /* If the pid changed since the last trace, output this event */
240 static enum print_line_t
241 verif_pid(struct trace_seq *s, pid_t pid, int cpu, struct fgraph_data *data)
248 return TRACE_TYPE_HANDLED;
250 last_pid = &(per_cpu_ptr(data, cpu)->last_pid);
252 if (*last_pid == pid)
253 return TRACE_TYPE_HANDLED;
255 prev_pid = *last_pid;
259 return TRACE_TYPE_HANDLED;
261 * Context-switch trace line:
263 ------------------------------------------
264 | 1) migration/0--1 => sshd-1755
265 ------------------------------------------
268 ret = trace_seq_printf(s,
269 " ------------------------------------------\n");
271 return TRACE_TYPE_PARTIAL_LINE;
273 ret = print_graph_cpu(s, cpu);
274 if (ret == TRACE_TYPE_PARTIAL_LINE)
275 return TRACE_TYPE_PARTIAL_LINE;
277 ret = print_graph_proc(s, prev_pid);
278 if (ret == TRACE_TYPE_PARTIAL_LINE)
279 return TRACE_TYPE_PARTIAL_LINE;
281 ret = trace_seq_printf(s, " => ");
283 return TRACE_TYPE_PARTIAL_LINE;
285 ret = print_graph_proc(s, pid);
286 if (ret == TRACE_TYPE_PARTIAL_LINE)
287 return TRACE_TYPE_PARTIAL_LINE;
289 ret = trace_seq_printf(s,
290 "\n ------------------------------------------\n\n");
292 return TRACE_TYPE_PARTIAL_LINE;
294 return TRACE_TYPE_HANDLED;
297 static struct ftrace_graph_ret_entry *
298 get_return_for_leaf(struct trace_iterator *iter,
299 struct ftrace_graph_ent_entry *curr)
301 struct ring_buffer_iter *ring_iter;
302 struct ring_buffer_event *event;
303 struct ftrace_graph_ret_entry *next;
305 ring_iter = iter->buffer_iter[iter->cpu];
307 /* First peek to compare current entry and the next one */
309 event = ring_buffer_iter_peek(ring_iter, NULL);
311 /* We need to consume the current entry to see the next one */
312 ring_buffer_consume(iter->tr->buffer, iter->cpu, NULL);
313 event = ring_buffer_peek(iter->tr->buffer, iter->cpu,
320 next = ring_buffer_event_data(event);
322 if (next->ent.type != TRACE_GRAPH_RET)
325 if (curr->ent.pid != next->ent.pid ||
326 curr->graph_ent.func != next->ret.func)
329 /* this is a leaf, now advance the iterator */
331 ring_buffer_read(ring_iter, NULL);
336 /* Signal a overhead of time execution to the output */
338 print_graph_overhead(unsigned long long duration, struct trace_seq *s)
340 /* If duration disappear, we don't need anything */
341 if (!(tracer_flags.val & TRACE_GRAPH_PRINT_DURATION))
344 /* Non nested entry or return */
346 return trace_seq_printf(s, " ");
348 if (tracer_flags.val & TRACE_GRAPH_PRINT_OVERHEAD) {
349 /* Duration exceeded 100 msecs */
350 if (duration > 100000ULL)
351 return trace_seq_printf(s, "! ");
353 /* Duration exceeded 10 msecs */
354 if (duration > 10000ULL)
355 return trace_seq_printf(s, "+ ");
358 return trace_seq_printf(s, " ");
361 static int print_graph_abs_time(u64 t, struct trace_seq *s)
363 unsigned long usecs_rem;
365 usecs_rem = do_div(t, NSEC_PER_SEC);
368 return trace_seq_printf(s, "%5lu.%06lu | ",
369 (unsigned long)t, usecs_rem);
372 static enum print_line_t
373 print_graph_irq(struct trace_iterator *iter, unsigned long addr,
374 enum trace_type type, int cpu, pid_t pid)
377 struct trace_seq *s = &iter->seq;
379 if (addr < (unsigned long)__irqentry_text_start ||
380 addr >= (unsigned long)__irqentry_text_end)
381 return TRACE_TYPE_UNHANDLED;
384 if (tracer_flags.val & TRACE_GRAPH_PRINT_ABS_TIME) {
385 ret = print_graph_abs_time(iter->ts, s);
387 return TRACE_TYPE_PARTIAL_LINE;
391 if (tracer_flags.val & TRACE_GRAPH_PRINT_CPU) {
392 ret = print_graph_cpu(s, cpu);
393 if (ret == TRACE_TYPE_PARTIAL_LINE)
394 return TRACE_TYPE_PARTIAL_LINE;
397 if (tracer_flags.val & TRACE_GRAPH_PRINT_PROC) {
398 ret = print_graph_proc(s, pid);
399 if (ret == TRACE_TYPE_PARTIAL_LINE)
400 return TRACE_TYPE_PARTIAL_LINE;
401 ret = trace_seq_printf(s, " | ");
403 return TRACE_TYPE_PARTIAL_LINE;
407 ret = print_graph_overhead(-1, s);
409 return TRACE_TYPE_PARTIAL_LINE;
411 if (type == TRACE_GRAPH_ENT)
412 ret = trace_seq_printf(s, "==========>");
414 ret = trace_seq_printf(s, "<==========");
417 return TRACE_TYPE_PARTIAL_LINE;
419 /* Don't close the duration column if haven't one */
420 if (tracer_flags.val & TRACE_GRAPH_PRINT_DURATION)
421 trace_seq_printf(s, " |");
422 ret = trace_seq_printf(s, "\n");
425 return TRACE_TYPE_PARTIAL_LINE;
426 return TRACE_TYPE_HANDLED;
430 trace_print_graph_duration(unsigned long long duration, struct trace_seq *s)
432 unsigned long nsecs_rem = do_div(duration, 1000);
433 /* log10(ULONG_MAX) + '\0' */
439 sprintf(msecs_str, "%lu", (unsigned long) duration);
442 ret = trace_seq_printf(s, "%s", msecs_str);
444 return TRACE_TYPE_PARTIAL_LINE;
446 len = strlen(msecs_str);
448 /* Print nsecs (we don't want to exceed 7 numbers) */
450 snprintf(nsecs_str, 8 - len, "%03lu", nsecs_rem);
451 ret = trace_seq_printf(s, ".%s", nsecs_str);
453 return TRACE_TYPE_PARTIAL_LINE;
454 len += strlen(nsecs_str);
457 ret = trace_seq_printf(s, " us ");
459 return TRACE_TYPE_PARTIAL_LINE;
461 /* Print remaining spaces to fit the row's width */
462 for (i = len; i < 7; i++) {
463 ret = trace_seq_printf(s, " ");
465 return TRACE_TYPE_PARTIAL_LINE;
467 return TRACE_TYPE_HANDLED;
470 static enum print_line_t
471 print_graph_duration(unsigned long long duration, struct trace_seq *s)
475 ret = trace_print_graph_duration(duration, s);
476 if (ret != TRACE_TYPE_HANDLED)
479 ret = trace_seq_printf(s, "| ");
481 return TRACE_TYPE_PARTIAL_LINE;
483 return TRACE_TYPE_HANDLED;
486 /* Case of a leaf function on its call entry */
487 static enum print_line_t
488 print_graph_entry_leaf(struct trace_iterator *iter,
489 struct ftrace_graph_ent_entry *entry,
490 struct ftrace_graph_ret_entry *ret_entry, struct trace_seq *s)
492 struct fgraph_data *data = iter->private;
493 struct ftrace_graph_ret *graph_ret;
494 struct ftrace_graph_ent *call;
495 unsigned long long duration;
499 graph_ret = &ret_entry->ret;
500 call = &entry->graph_ent;
501 duration = graph_ret->rettime - graph_ret->calltime;
505 int *depth = &(per_cpu_ptr(data, cpu)->depth);
508 * Comments display at + 1 to depth. Since
509 * this is a leaf function, keep the comments
510 * equal to this depth.
512 *depth = call->depth - 1;
516 ret = print_graph_overhead(duration, s);
518 return TRACE_TYPE_PARTIAL_LINE;
521 if (tracer_flags.val & TRACE_GRAPH_PRINT_DURATION) {
522 ret = print_graph_duration(duration, s);
523 if (ret == TRACE_TYPE_PARTIAL_LINE)
524 return TRACE_TYPE_PARTIAL_LINE;
528 for (i = 0; i < call->depth * TRACE_GRAPH_INDENT; i++) {
529 ret = trace_seq_printf(s, " ");
531 return TRACE_TYPE_PARTIAL_LINE;
534 ret = seq_print_ip_sym(s, call->func, 0);
536 return TRACE_TYPE_PARTIAL_LINE;
538 ret = trace_seq_printf(s, "();\n");
540 return TRACE_TYPE_PARTIAL_LINE;
542 return TRACE_TYPE_HANDLED;
545 static enum print_line_t
546 print_graph_entry_nested(struct trace_iterator *iter,
547 struct ftrace_graph_ent_entry *entry,
548 struct trace_seq *s, int cpu)
550 struct ftrace_graph_ent *call = &entry->graph_ent;
551 struct fgraph_data *data = iter->private;
557 int *depth = &(per_cpu_ptr(data, cpu)->depth);
559 *depth = call->depth;
563 ret = print_graph_overhead(-1, s);
565 return TRACE_TYPE_PARTIAL_LINE;
568 if (tracer_flags.val & TRACE_GRAPH_PRINT_DURATION) {
569 ret = trace_seq_printf(s, " | ");
571 return TRACE_TYPE_PARTIAL_LINE;
575 for (i = 0; i < call->depth * TRACE_GRAPH_INDENT; i++) {
576 ret = trace_seq_printf(s, " ");
578 return TRACE_TYPE_PARTIAL_LINE;
581 ret = seq_print_ip_sym(s, call->func, 0);
583 return TRACE_TYPE_PARTIAL_LINE;
585 ret = trace_seq_printf(s, "() {\n");
587 return TRACE_TYPE_PARTIAL_LINE;
590 * we already consumed the current entry to check the next one
591 * and see if this is a leaf.
593 return TRACE_TYPE_NO_CONSUME;
596 static enum print_line_t
597 print_graph_prologue(struct trace_iterator *iter, struct trace_seq *s,
598 int type, unsigned long addr)
600 struct fgraph_data *data = iter->private;
601 struct trace_entry *ent = iter->ent;
606 if (verif_pid(s, ent->pid, cpu, data) == TRACE_TYPE_PARTIAL_LINE)
607 return TRACE_TYPE_PARTIAL_LINE;
611 ret = print_graph_irq(iter, addr, type, cpu, ent->pid);
612 if (ret == TRACE_TYPE_PARTIAL_LINE)
613 return TRACE_TYPE_PARTIAL_LINE;
617 if (tracer_flags.val & TRACE_GRAPH_PRINT_ABS_TIME) {
618 ret = print_graph_abs_time(iter->ts, s);
620 return TRACE_TYPE_PARTIAL_LINE;
624 if (tracer_flags.val & TRACE_GRAPH_PRINT_CPU) {
625 ret = print_graph_cpu(s, cpu);
626 if (ret == TRACE_TYPE_PARTIAL_LINE)
627 return TRACE_TYPE_PARTIAL_LINE;
631 if (tracer_flags.val & TRACE_GRAPH_PRINT_PROC) {
632 ret = print_graph_proc(s, ent->pid);
633 if (ret == TRACE_TYPE_PARTIAL_LINE)
634 return TRACE_TYPE_PARTIAL_LINE;
636 ret = trace_seq_printf(s, " | ");
638 return TRACE_TYPE_PARTIAL_LINE;
644 static enum print_line_t
645 print_graph_entry(struct ftrace_graph_ent_entry *field, struct trace_seq *s,
646 struct trace_iterator *iter)
649 struct ftrace_graph_ent *call = &field->graph_ent;
650 struct ftrace_graph_ret_entry *leaf_ret;
652 if (print_graph_prologue(iter, s, TRACE_GRAPH_ENT, call->func))
653 return TRACE_TYPE_PARTIAL_LINE;
655 leaf_ret = get_return_for_leaf(iter, field);
657 return print_graph_entry_leaf(iter, field, leaf_ret, s);
659 return print_graph_entry_nested(iter, field, s, cpu);
663 static enum print_line_t
664 print_graph_return(struct ftrace_graph_ret *trace, struct trace_seq *s,
665 struct trace_entry *ent, struct trace_iterator *iter)
667 unsigned long long duration = trace->rettime - trace->calltime;
668 struct fgraph_data *data = iter->private;
669 pid_t pid = ent->pid;
676 int *depth = &(per_cpu_ptr(data, cpu)->depth);
679 * Comments display at + 1 to depth. This is the
680 * return from a function, we now want the comments
681 * to display at the same level of the bracket.
683 *depth = trace->depth - 1;
686 if (print_graph_prologue(iter, s, 0, 0))
687 return TRACE_TYPE_PARTIAL_LINE;
690 ret = print_graph_overhead(duration, s);
692 return TRACE_TYPE_PARTIAL_LINE;
695 if (tracer_flags.val & TRACE_GRAPH_PRINT_DURATION) {
696 ret = print_graph_duration(duration, s);
697 if (ret == TRACE_TYPE_PARTIAL_LINE)
698 return TRACE_TYPE_PARTIAL_LINE;
702 for (i = 0; i < trace->depth * TRACE_GRAPH_INDENT; i++) {
703 ret = trace_seq_printf(s, " ");
705 return TRACE_TYPE_PARTIAL_LINE;
708 ret = trace_seq_printf(s, "}\n");
710 return TRACE_TYPE_PARTIAL_LINE;
713 if (tracer_flags.val & TRACE_GRAPH_PRINT_OVERRUN) {
714 ret = trace_seq_printf(s, " (Overruns: %lu)\n",
717 return TRACE_TYPE_PARTIAL_LINE;
720 ret = print_graph_irq(iter, trace->func, TRACE_GRAPH_RET, cpu, pid);
721 if (ret == TRACE_TYPE_PARTIAL_LINE)
722 return TRACE_TYPE_PARTIAL_LINE;
724 return TRACE_TYPE_HANDLED;
727 static enum print_line_t
728 print_graph_comment(struct trace_seq *s, struct trace_entry *ent,
729 struct trace_iterator *iter)
731 unsigned long sym_flags = (trace_flags & TRACE_ITER_SYM_MASK);
732 struct fgraph_data *data = iter->private;
733 struct trace_event *event;
739 depth = per_cpu_ptr(data, iter->cpu)->depth;
741 if (print_graph_prologue(iter, s, 0, 0))
742 return TRACE_TYPE_PARTIAL_LINE;
745 ret = print_graph_overhead(-1, s);
747 return TRACE_TYPE_PARTIAL_LINE;
750 if (tracer_flags.val & TRACE_GRAPH_PRINT_DURATION) {
751 ret = trace_seq_printf(s, " | ");
753 return TRACE_TYPE_PARTIAL_LINE;
758 for (i = 0; i < (depth + 1) * TRACE_GRAPH_INDENT; i++) {
759 ret = trace_seq_printf(s, " ");
761 return TRACE_TYPE_PARTIAL_LINE;
765 ret = trace_seq_printf(s, "/* ");
767 return TRACE_TYPE_PARTIAL_LINE;
769 switch (iter->ent->type) {
771 ret = trace_print_bprintk_msg_only(iter);
772 if (ret != TRACE_TYPE_HANDLED)
776 ret = trace_print_printk_msg_only(iter);
777 if (ret != TRACE_TYPE_HANDLED)
781 event = ftrace_find_event(ent->type);
783 return TRACE_TYPE_UNHANDLED;
785 ret = event->trace(iter, sym_flags);
786 if (ret != TRACE_TYPE_HANDLED)
790 /* Strip ending newline */
791 if (s->buffer[s->len - 1] == '\n') {
792 s->buffer[s->len - 1] = '\0';
796 ret = trace_seq_printf(s, " */\n");
798 return TRACE_TYPE_PARTIAL_LINE;
800 return TRACE_TYPE_HANDLED;
805 print_graph_function(struct trace_iterator *iter)
807 struct trace_entry *entry = iter->ent;
808 struct trace_seq *s = &iter->seq;
810 switch (entry->type) {
811 case TRACE_GRAPH_ENT: {
812 struct ftrace_graph_ent_entry *field;
813 trace_assign_type(field, entry);
814 return print_graph_entry(field, s, iter);
816 case TRACE_GRAPH_RET: {
817 struct ftrace_graph_ret_entry *field;
818 trace_assign_type(field, entry);
819 return print_graph_return(&field->ret, s, entry, iter);
822 return print_graph_comment(s, entry, iter);
825 return TRACE_TYPE_HANDLED;
828 static void print_graph_headers(struct seq_file *s)
832 if (tracer_flags.val & TRACE_GRAPH_PRINT_ABS_TIME)
833 seq_printf(s, " TIME ");
834 if (tracer_flags.val & TRACE_GRAPH_PRINT_CPU)
835 seq_printf(s, "CPU");
836 if (tracer_flags.val & TRACE_GRAPH_PRINT_PROC)
837 seq_printf(s, " TASK/PID ");
838 if (tracer_flags.val & TRACE_GRAPH_PRINT_DURATION)
839 seq_printf(s, " DURATION ");
840 seq_printf(s, " FUNCTION CALLS\n");
844 if (tracer_flags.val & TRACE_GRAPH_PRINT_ABS_TIME)
845 seq_printf(s, " | ");
846 if (tracer_flags.val & TRACE_GRAPH_PRINT_CPU)
848 if (tracer_flags.val & TRACE_GRAPH_PRINT_PROC)
849 seq_printf(s, " | | ");
850 if (tracer_flags.val & TRACE_GRAPH_PRINT_DURATION)
851 seq_printf(s, " | | ");
852 seq_printf(s, " | | | |\n");
855 static void graph_trace_open(struct trace_iterator *iter)
857 /* pid and depth on the last trace processed */
858 struct fgraph_data *data = alloc_percpu(struct fgraph_data);
862 pr_warning("function graph tracer: not enough memory\n");
864 for_each_possible_cpu(cpu) {
865 pid_t *pid = &(per_cpu_ptr(data, cpu)->last_pid);
866 int *depth = &(per_cpu_ptr(data, cpu)->depth);
871 iter->private = data;
874 static void graph_trace_close(struct trace_iterator *iter)
876 free_percpu(iter->private);
879 static struct tracer graph_trace __read_mostly = {
880 .name = "function_graph",
881 .open = graph_trace_open,
882 .close = graph_trace_close,
883 .wait_pipe = poll_wait_pipe,
884 .init = graph_trace_init,
885 .reset = graph_trace_reset,
886 .print_line = print_graph_function,
887 .print_header = print_graph_headers,
888 .flags = &tracer_flags,
889 #ifdef CONFIG_FTRACE_SELFTEST
890 .selftest = trace_selftest_startup_function_graph,
894 static __init int init_graph_trace(void)
896 return register_tracer(&graph_trace);
899 device_initcall(init_graph_trace);