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