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1/*
2 * trace task wakeup timings
3 *
4 * Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com>
5 * Copyright (C) 2008 Ingo Molnar <mingo@redhat.com>
6 *
7 * Based on code from the latency_tracer, that is:
8 *
9 * Copyright (C) 2004-2006 Ingo Molnar
10 * Copyright (C) 2004 Nadia Yvette Chambers
11 */
12#include <linux/module.h>
13#include <linux/kallsyms.h>
14#include <linux/uaccess.h>
15#include <linux/ftrace.h>
16#include <linux/sched/rt.h>
17#include <linux/sched/deadline.h>
18#include <trace/events/sched.h>
19#include "trace.h"
20
21static struct trace_array *wakeup_trace;
22static int __read_mostly tracer_enabled;
23
24static struct task_struct *wakeup_task;
25static int wakeup_cpu;
26static int wakeup_current_cpu;
27static unsigned wakeup_prio = -1;
28static int wakeup_rt;
29static int wakeup_dl;
30static int tracing_dl = 0;
31
32static arch_spinlock_t wakeup_lock =
33 (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
34
35static void wakeup_reset(struct trace_array *tr);
36static void __wakeup_reset(struct trace_array *tr);
37
38static int save_flags;
39
40#ifdef CONFIG_FUNCTION_GRAPH_TRACER
41static int wakeup_display_graph(struct trace_array *tr, int set);
42# define is_graph(tr) ((tr)->trace_flags & TRACE_ITER_DISPLAY_GRAPH)
43#else
44static inline int wakeup_display_graph(struct trace_array *tr, int set)
45{
46 return 0;
47}
48# define is_graph(tr) false
49#endif
50
51
52#ifdef CONFIG_FUNCTION_TRACER
53
54static int wakeup_graph_entry(struct ftrace_graph_ent *trace);
55static void wakeup_graph_return(struct ftrace_graph_ret *trace);
56
57static bool function_enabled;
58
59/*
60 * Prologue for the wakeup function tracers.
61 *
62 * Returns 1 if it is OK to continue, and preemption
63 * is disabled and data->disabled is incremented.
64 * 0 if the trace is to be ignored, and preemption
65 * is not disabled and data->disabled is
66 * kept the same.
67 *
68 * Note, this function is also used outside this ifdef but
69 * inside the #ifdef of the function graph tracer below.
70 * This is OK, since the function graph tracer is
71 * dependent on the function tracer.
72 */
73static int
74func_prolog_preempt_disable(struct trace_array *tr,
75 struct trace_array_cpu **data,
76 int *pc)
77{
78 long disabled;
79 int cpu;
80
81 if (likely(!wakeup_task))
82 return 0;
83
84 *pc = preempt_count();
85 preempt_disable_notrace();
86
87 cpu = raw_smp_processor_id();
88 if (cpu != wakeup_current_cpu)
89 goto out_enable;
90
91 *data = per_cpu_ptr(tr->trace_buffer.data, cpu);
92 disabled = atomic_inc_return(&(*data)->disabled);
93 if (unlikely(disabled != 1))
94 goto out;
95
96 return 1;
97
98out:
99 atomic_dec(&(*data)->disabled);
100
101out_enable:
102 preempt_enable_notrace();
103 return 0;
104}
105
106/*
107 * wakeup uses its own tracer function to keep the overhead down:
108 */
109static void
110wakeup_tracer_call(unsigned long ip, unsigned long parent_ip,
111 struct ftrace_ops *op, struct pt_regs *pt_regs)
112{
113 struct trace_array *tr = wakeup_trace;
114 struct trace_array_cpu *data;
115 unsigned long flags;
116 int pc;
117
118 if (!func_prolog_preempt_disable(tr, &data, &pc))
119 return;
120
121 local_irq_save(flags);
122 trace_function(tr, ip, parent_ip, flags, pc);
123 local_irq_restore(flags);
124
125 atomic_dec(&data->disabled);
126 preempt_enable_notrace();
127}
128
129static int register_wakeup_function(struct trace_array *tr, int graph, int set)
130{
131 int ret;
132
133 /* 'set' is set if TRACE_ITER_FUNCTION is about to be set */
134 if (function_enabled || (!set && !(tr->trace_flags & TRACE_ITER_FUNCTION)))
135 return 0;
136
137 if (graph)
138 ret = register_ftrace_graph(&wakeup_graph_return,
139 &wakeup_graph_entry);
140 else
141 ret = register_ftrace_function(tr->ops);
142
143 if (!ret)
144 function_enabled = true;
145
146 return ret;
147}
148
149static void unregister_wakeup_function(struct trace_array *tr, int graph)
150{
151 if (!function_enabled)
152 return;
153
154 if (graph)
155 unregister_ftrace_graph();
156 else
157 unregister_ftrace_function(tr->ops);
158
159 function_enabled = false;
160}
161
162static int wakeup_function_set(struct trace_array *tr, u32 mask, int set)
163{
164 if (!(mask & TRACE_ITER_FUNCTION))
165 return 0;
166
167 if (set)
168 register_wakeup_function(tr, is_graph(tr), 1);
169 else
170 unregister_wakeup_function(tr, is_graph(tr));
171 return 1;
172}
173#else
174static int register_wakeup_function(struct trace_array *tr, int graph, int set)
175{
176 return 0;
177}
178static void unregister_wakeup_function(struct trace_array *tr, int graph) { }
179static int wakeup_function_set(struct trace_array *tr, u32 mask, int set)
180{
181 return 0;
182}
183#endif /* CONFIG_FUNCTION_TRACER */
184
185static int wakeup_flag_changed(struct trace_array *tr, u32 mask, int set)
186{
187 struct tracer *tracer = tr->current_trace;
188
189 if (wakeup_function_set(tr, mask, set))
190 return 0;
191
192#ifdef CONFIG_FUNCTION_GRAPH_TRACER
193 if (mask & TRACE_ITER_DISPLAY_GRAPH)
194 return wakeup_display_graph(tr, set);
195#endif
196
197 return trace_keep_overwrite(tracer, mask, set);
198}
199
200static int start_func_tracer(struct trace_array *tr, int graph)
201{
202 int ret;
203
204 ret = register_wakeup_function(tr, graph, 0);
205
206 if (!ret && tracing_is_enabled())
207 tracer_enabled = 1;
208 else
209 tracer_enabled = 0;
210
211 return ret;
212}
213
214static void stop_func_tracer(struct trace_array *tr, int graph)
215{
216 tracer_enabled = 0;
217
218 unregister_wakeup_function(tr, graph);
219}
220
221#ifdef CONFIG_FUNCTION_GRAPH_TRACER
222static int wakeup_display_graph(struct trace_array *tr, int set)
223{
224 if (!(is_graph(tr) ^ set))
225 return 0;
226
227 stop_func_tracer(tr, !set);
228
229 wakeup_reset(wakeup_trace);
230 tr->max_latency = 0;
231
232 return start_func_tracer(tr, set);
233}
234
235static int wakeup_graph_entry(struct ftrace_graph_ent *trace)
236{
237 struct trace_array *tr = wakeup_trace;
238 struct trace_array_cpu *data;
239 unsigned long flags;
240 int pc, ret = 0;
241
242 if (!func_prolog_preempt_disable(tr, &data, &pc))
243 return 0;
244
245 local_save_flags(flags);
246 ret = __trace_graph_entry(tr, trace, flags, pc);
247 atomic_dec(&data->disabled);
248 preempt_enable_notrace();
249
250 return ret;
251}
252
253static void wakeup_graph_return(struct ftrace_graph_ret *trace)
254{
255 struct trace_array *tr = wakeup_trace;
256 struct trace_array_cpu *data;
257 unsigned long flags;
258 int pc;
259
260 if (!func_prolog_preempt_disable(tr, &data, &pc))
261 return;
262
263 local_save_flags(flags);
264 __trace_graph_return(tr, trace, flags, pc);
265 atomic_dec(&data->disabled);
266
267 preempt_enable_notrace();
268 return;
269}
270
271static void wakeup_trace_open(struct trace_iterator *iter)
272{
273 if (is_graph(iter->tr))
274 graph_trace_open(iter);
275}
276
277static void wakeup_trace_close(struct trace_iterator *iter)
278{
279 if (iter->private)
280 graph_trace_close(iter);
281}
282
283#define GRAPH_TRACER_FLAGS (TRACE_GRAPH_PRINT_PROC | \
284 TRACE_GRAPH_PRINT_ABS_TIME | \
285 TRACE_GRAPH_PRINT_DURATION)
286
287static enum print_line_t wakeup_print_line(struct trace_iterator *iter)
288{
289 /*
290 * In graph mode call the graph tracer output function,
291 * otherwise go with the TRACE_FN event handler
292 */
293 if (is_graph(iter->tr))
294 return print_graph_function_flags(iter, GRAPH_TRACER_FLAGS);
295
296 return TRACE_TYPE_UNHANDLED;
297}
298
299static void wakeup_print_header(struct seq_file *s)
300{
301 if (is_graph(wakeup_trace))
302 print_graph_headers_flags(s, GRAPH_TRACER_FLAGS);
303 else
304 trace_default_header(s);
305}
306
307static void
308__trace_function(struct trace_array *tr,
309 unsigned long ip, unsigned long parent_ip,
310 unsigned long flags, int pc)
311{
312 if (is_graph(tr))
313 trace_graph_function(tr, ip, parent_ip, flags, pc);
314 else
315 trace_function(tr, ip, parent_ip, flags, pc);
316}
317#else
318#define __trace_function trace_function
319
320static enum print_line_t wakeup_print_line(struct trace_iterator *iter)
321{
322 return TRACE_TYPE_UNHANDLED;
323}
324
325static void wakeup_trace_open(struct trace_iterator *iter) { }
326static void wakeup_trace_close(struct trace_iterator *iter) { }
327
328#ifdef CONFIG_FUNCTION_TRACER
329static int wakeup_graph_entry(struct ftrace_graph_ent *trace)
330{
331 return -1;
332}
333static void wakeup_graph_return(struct ftrace_graph_ret *trace) { }
334static void wakeup_print_header(struct seq_file *s)
335{
336 trace_default_header(s);
337}
338#else
339static void wakeup_print_header(struct seq_file *s)
340{
341 trace_latency_header(s);
342}
343#endif /* CONFIG_FUNCTION_TRACER */
344#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
345
346/*
347 * Should this new latency be reported/recorded?
348 */
349static bool report_latency(struct trace_array *tr, cycle_t delta)
350{
351 if (tracing_thresh) {
352 if (delta < tracing_thresh)
353 return false;
354 } else {
355 if (delta <= tr->max_latency)
356 return false;
357 }
358 return true;
359}
360
361static void
362probe_wakeup_migrate_task(void *ignore, struct task_struct *task, int cpu)
363{
364 if (task != wakeup_task)
365 return;
366
367 wakeup_current_cpu = cpu;
368}
369
370static void
371tracing_sched_switch_trace(struct trace_array *tr,
372 struct task_struct *prev,
373 struct task_struct *next,
374 unsigned long flags, int pc)
375{
376 struct trace_event_call *call = &event_context_switch;
377 struct ring_buffer *buffer = tr->trace_buffer.buffer;
378 struct ring_buffer_event *event;
379 struct ctx_switch_entry *entry;
380
381 event = trace_buffer_lock_reserve(buffer, TRACE_CTX,
382 sizeof(*entry), flags, pc);
383 if (!event)
384 return;
385 entry = ring_buffer_event_data(event);
386 entry->prev_pid = prev->pid;
387 entry->prev_prio = prev->prio;
388 entry->prev_state = prev->state;
389 entry->next_pid = next->pid;
390 entry->next_prio = next->prio;
391 entry->next_state = next->state;
392 entry->next_cpu = task_cpu(next);
393
394 if (!call_filter_check_discard(call, entry, buffer, event))
395 trace_buffer_unlock_commit(tr, buffer, event, flags, pc);
396}
397
398static void
399tracing_sched_wakeup_trace(struct trace_array *tr,
400 struct task_struct *wakee,
401 struct task_struct *curr,
402 unsigned long flags, int pc)
403{
404 struct trace_event_call *call = &event_wakeup;
405 struct ring_buffer_event *event;
406 struct ctx_switch_entry *entry;
407 struct ring_buffer *buffer = tr->trace_buffer.buffer;
408
409 event = trace_buffer_lock_reserve(buffer, TRACE_WAKE,
410 sizeof(*entry), flags, pc);
411 if (!event)
412 return;
413 entry = ring_buffer_event_data(event);
414 entry->prev_pid = curr->pid;
415 entry->prev_prio = curr->prio;
416 entry->prev_state = curr->state;
417 entry->next_pid = wakee->pid;
418 entry->next_prio = wakee->prio;
419 entry->next_state = wakee->state;
420 entry->next_cpu = task_cpu(wakee);
421
422 if (!call_filter_check_discard(call, entry, buffer, event))
423 trace_buffer_unlock_commit(tr, buffer, event, flags, pc);
424}
425
426static void notrace
427probe_wakeup_sched_switch(void *ignore, bool preempt,
428 struct task_struct *prev, struct task_struct *next)
429{
430 struct trace_array_cpu *data;
431 cycle_t T0, T1, delta;
432 unsigned long flags;
433 long disabled;
434 int cpu;
435 int pc;
436
437 tracing_record_cmdline(prev);
438
439 if (unlikely(!tracer_enabled))
440 return;
441
442 /*
443 * When we start a new trace, we set wakeup_task to NULL
444 * and then set tracer_enabled = 1. We want to make sure
445 * that another CPU does not see the tracer_enabled = 1
446 * and the wakeup_task with an older task, that might
447 * actually be the same as next.
448 */
449 smp_rmb();
450
451 if (next != wakeup_task)
452 return;
453
454 pc = preempt_count();
455
456 /* disable local data, not wakeup_cpu data */
457 cpu = raw_smp_processor_id();
458 disabled = atomic_inc_return(&per_cpu_ptr(wakeup_trace->trace_buffer.data, cpu)->disabled);
459 if (likely(disabled != 1))
460 goto out;
461
462 local_irq_save(flags);
463 arch_spin_lock(&wakeup_lock);
464
465 /* We could race with grabbing wakeup_lock */
466 if (unlikely(!tracer_enabled || next != wakeup_task))
467 goto out_unlock;
468
469 /* The task we are waiting for is waking up */
470 data = per_cpu_ptr(wakeup_trace->trace_buffer.data, wakeup_cpu);
471
472 __trace_function(wakeup_trace, CALLER_ADDR0, CALLER_ADDR1, flags, pc);
473 tracing_sched_switch_trace(wakeup_trace, prev, next, flags, pc);
474
475 T0 = data->preempt_timestamp;
476 T1 = ftrace_now(cpu);
477 delta = T1-T0;
478
479 if (!report_latency(wakeup_trace, delta))
480 goto out_unlock;
481
482 if (likely(!is_tracing_stopped())) {
483 wakeup_trace->max_latency = delta;
484 update_max_tr(wakeup_trace, wakeup_task, wakeup_cpu);
485 }
486
487out_unlock:
488 __wakeup_reset(wakeup_trace);
489 arch_spin_unlock(&wakeup_lock);
490 local_irq_restore(flags);
491out:
492 atomic_dec(&per_cpu_ptr(wakeup_trace->trace_buffer.data, cpu)->disabled);
493}
494
495static void __wakeup_reset(struct trace_array *tr)
496{
497 wakeup_cpu = -1;
498 wakeup_prio = -1;
499 tracing_dl = 0;
500
501 if (wakeup_task)
502 put_task_struct(wakeup_task);
503
504 wakeup_task = NULL;
505}
506
507static void wakeup_reset(struct trace_array *tr)
508{
509 unsigned long flags;
510
511 tracing_reset_online_cpus(&tr->trace_buffer);
512
513 local_irq_save(flags);
514 arch_spin_lock(&wakeup_lock);
515 __wakeup_reset(tr);
516 arch_spin_unlock(&wakeup_lock);
517 local_irq_restore(flags);
518}
519
520static void
521probe_wakeup(void *ignore, struct task_struct *p)
522{
523 struct trace_array_cpu *data;
524 int cpu = smp_processor_id();
525 unsigned long flags;
526 long disabled;
527 int pc;
528
529 if (likely(!tracer_enabled))
530 return;
531
532 tracing_record_cmdline(p);
533 tracing_record_cmdline(current);
534
535 /*
536 * Semantic is like this:
537 * - wakeup tracer handles all tasks in the system, independently
538 * from their scheduling class;
539 * - wakeup_rt tracer handles tasks belonging to sched_dl and
540 * sched_rt class;
541 * - wakeup_dl handles tasks belonging to sched_dl class only.
542 */
543 if (tracing_dl || (wakeup_dl && !dl_task(p)) ||
544 (wakeup_rt && !dl_task(p) && !rt_task(p)) ||
545 (!dl_task(p) && (p->prio >= wakeup_prio || p->prio >= current->prio)))
546 return;
547
548 pc = preempt_count();
549 disabled = atomic_inc_return(&per_cpu_ptr(wakeup_trace->trace_buffer.data, cpu)->disabled);
550 if (unlikely(disabled != 1))
551 goto out;
552
553 /* interrupts should be off from try_to_wake_up */
554 arch_spin_lock(&wakeup_lock);
555
556 /* check for races. */
557 if (!tracer_enabled || tracing_dl ||
558 (!dl_task(p) && p->prio >= wakeup_prio))
559 goto out_locked;
560
561 /* reset the trace */
562 __wakeup_reset(wakeup_trace);
563
564 wakeup_cpu = task_cpu(p);
565 wakeup_current_cpu = wakeup_cpu;
566 wakeup_prio = p->prio;
567
568 /*
569 * Once you start tracing a -deadline task, don't bother tracing
570 * another task until the first one wakes up.
571 */
572 if (dl_task(p))
573 tracing_dl = 1;
574 else
575 tracing_dl = 0;
576
577 wakeup_task = p;
578 get_task_struct(wakeup_task);
579
580 local_save_flags(flags);
581
582 data = per_cpu_ptr(wakeup_trace->trace_buffer.data, wakeup_cpu);
583 data->preempt_timestamp = ftrace_now(cpu);
584 tracing_sched_wakeup_trace(wakeup_trace, p, current, flags, pc);
585
586 /*
587 * We must be careful in using CALLER_ADDR2. But since wake_up
588 * is not called by an assembly function (where as schedule is)
589 * it should be safe to use it here.
590 */
591 __trace_function(wakeup_trace, CALLER_ADDR1, CALLER_ADDR2, flags, pc);
592
593out_locked:
594 arch_spin_unlock(&wakeup_lock);
595out:
596 atomic_dec(&per_cpu_ptr(wakeup_trace->trace_buffer.data, cpu)->disabled);
597}
598
599static void start_wakeup_tracer(struct trace_array *tr)
600{
601 int ret;
602
603 ret = register_trace_sched_wakeup(probe_wakeup, NULL);
604 if (ret) {
605 pr_info("wakeup trace: Couldn't activate tracepoint"
606 " probe to kernel_sched_wakeup\n");
607 return;
608 }
609
610 ret = register_trace_sched_wakeup_new(probe_wakeup, NULL);
611 if (ret) {
612 pr_info("wakeup trace: Couldn't activate tracepoint"
613 " probe to kernel_sched_wakeup_new\n");
614 goto fail_deprobe;
615 }
616
617 ret = register_trace_sched_switch(probe_wakeup_sched_switch, NULL);
618 if (ret) {
619 pr_info("sched trace: Couldn't activate tracepoint"
620 " probe to kernel_sched_switch\n");
621 goto fail_deprobe_wake_new;
622 }
623
624 ret = register_trace_sched_migrate_task(probe_wakeup_migrate_task, NULL);
625 if (ret) {
626 pr_info("wakeup trace: Couldn't activate tracepoint"
627 " probe to kernel_sched_migrate_task\n");
628 return;
629 }
630
631 wakeup_reset(tr);
632
633 /*
634 * Don't let the tracer_enabled = 1 show up before
635 * the wakeup_task is reset. This may be overkill since
636 * wakeup_reset does a spin_unlock after setting the
637 * wakeup_task to NULL, but I want to be safe.
638 * This is a slow path anyway.
639 */
640 smp_wmb();
641
642 if (start_func_tracer(tr, is_graph(tr)))
643 printk(KERN_ERR "failed to start wakeup tracer\n");
644
645 return;
646fail_deprobe_wake_new:
647 unregister_trace_sched_wakeup_new(probe_wakeup, NULL);
648fail_deprobe:
649 unregister_trace_sched_wakeup(probe_wakeup, NULL);
650}
651
652static void stop_wakeup_tracer(struct trace_array *tr)
653{
654 tracer_enabled = 0;
655 stop_func_tracer(tr, is_graph(tr));
656 unregister_trace_sched_switch(probe_wakeup_sched_switch, NULL);
657 unregister_trace_sched_wakeup_new(probe_wakeup, NULL);
658 unregister_trace_sched_wakeup(probe_wakeup, NULL);
659 unregister_trace_sched_migrate_task(probe_wakeup_migrate_task, NULL);
660}
661
662static bool wakeup_busy;
663
664static int __wakeup_tracer_init(struct trace_array *tr)
665{
666 save_flags = tr->trace_flags;
667
668 /* non overwrite screws up the latency tracers */
669 set_tracer_flag(tr, TRACE_ITER_OVERWRITE, 1);
670 set_tracer_flag(tr, TRACE_ITER_LATENCY_FMT, 1);
671
672 tr->max_latency = 0;
673 wakeup_trace = tr;
674 ftrace_init_array_ops(tr, wakeup_tracer_call);
675 start_wakeup_tracer(tr);
676
677 wakeup_busy = true;
678 return 0;
679}
680
681static int wakeup_tracer_init(struct trace_array *tr)
682{
683 if (wakeup_busy)
684 return -EBUSY;
685
686 wakeup_dl = 0;
687 wakeup_rt = 0;
688 return __wakeup_tracer_init(tr);
689}
690
691static int wakeup_rt_tracer_init(struct trace_array *tr)
692{
693 if (wakeup_busy)
694 return -EBUSY;
695
696 wakeup_dl = 0;
697 wakeup_rt = 1;
698 return __wakeup_tracer_init(tr);
699}
700
701static int wakeup_dl_tracer_init(struct trace_array *tr)
702{
703 if (wakeup_busy)
704 return -EBUSY;
705
706 wakeup_dl = 1;
707 wakeup_rt = 0;
708 return __wakeup_tracer_init(tr);
709}
710
711static void wakeup_tracer_reset(struct trace_array *tr)
712{
713 int lat_flag = save_flags & TRACE_ITER_LATENCY_FMT;
714 int overwrite_flag = save_flags & TRACE_ITER_OVERWRITE;
715
716 stop_wakeup_tracer(tr);
717 /* make sure we put back any tasks we are tracing */
718 wakeup_reset(tr);
719
720 set_tracer_flag(tr, TRACE_ITER_LATENCY_FMT, lat_flag);
721 set_tracer_flag(tr, TRACE_ITER_OVERWRITE, overwrite_flag);
722 ftrace_reset_array_ops(tr);
723 wakeup_busy = false;
724}
725
726static void wakeup_tracer_start(struct trace_array *tr)
727{
728 wakeup_reset(tr);
729 tracer_enabled = 1;
730}
731
732static void wakeup_tracer_stop(struct trace_array *tr)
733{
734 tracer_enabled = 0;
735}
736
737static struct tracer wakeup_tracer __read_mostly =
738{
739 .name = "wakeup",
740 .init = wakeup_tracer_init,
741 .reset = wakeup_tracer_reset,
742 .start = wakeup_tracer_start,
743 .stop = wakeup_tracer_stop,
744 .print_max = true,
745 .print_header = wakeup_print_header,
746 .print_line = wakeup_print_line,
747 .flag_changed = wakeup_flag_changed,
748#ifdef CONFIG_FTRACE_SELFTEST
749 .selftest = trace_selftest_startup_wakeup,
750#endif
751 .open = wakeup_trace_open,
752 .close = wakeup_trace_close,
753 .allow_instances = true,
754 .use_max_tr = true,
755};
756
757static struct tracer wakeup_rt_tracer __read_mostly =
758{
759 .name = "wakeup_rt",
760 .init = wakeup_rt_tracer_init,
761 .reset = wakeup_tracer_reset,
762 .start = wakeup_tracer_start,
763 .stop = wakeup_tracer_stop,
764 .print_max = true,
765 .print_header = wakeup_print_header,
766 .print_line = wakeup_print_line,
767 .flag_changed = wakeup_flag_changed,
768#ifdef CONFIG_FTRACE_SELFTEST
769 .selftest = trace_selftest_startup_wakeup,
770#endif
771 .open = wakeup_trace_open,
772 .close = wakeup_trace_close,
773 .allow_instances = true,
774 .use_max_tr = true,
775};
776
777static struct tracer wakeup_dl_tracer __read_mostly =
778{
779 .name = "wakeup_dl",
780 .init = wakeup_dl_tracer_init,
781 .reset = wakeup_tracer_reset,
782 .start = wakeup_tracer_start,
783 .stop = wakeup_tracer_stop,
784 .print_max = true,
785 .print_header = wakeup_print_header,
786 .print_line = wakeup_print_line,
787 .flag_changed = wakeup_flag_changed,
788#ifdef CONFIG_FTRACE_SELFTEST
789 .selftest = trace_selftest_startup_wakeup,
790#endif
791 .open = wakeup_trace_open,
792 .close = wakeup_trace_close,
793 .use_max_tr = true,
794};
795
796__init static int init_wakeup_tracer(void)
797{
798 int ret;
799
800 ret = register_tracer(&wakeup_tracer);
801 if (ret)
802 return ret;
803
804 ret = register_tracer(&wakeup_rt_tracer);
805 if (ret)
806 return ret;
807
808 ret = register_tracer(&wakeup_dl_tracer);
809 if (ret)
810 return ret;
811
812 return 0;
813}
814core_initcall(init_wakeup_tracer);
1/*
2 * trace task wakeup timings
3 *
4 * Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com>
5 * Copyright (C) 2008 Ingo Molnar <mingo@redhat.com>
6 *
7 * Based on code from the latency_tracer, that is:
8 *
9 * Copyright (C) 2004-2006 Ingo Molnar
10 * Copyright (C) 2004 William Lee Irwin III
11 */
12#include <linux/module.h>
13#include <linux/fs.h>
14#include <linux/debugfs.h>
15#include <linux/kallsyms.h>
16#include <linux/uaccess.h>
17#include <linux/ftrace.h>
18#include <trace/events/sched.h>
19
20#include "trace.h"
21
22static struct trace_array *wakeup_trace;
23static int __read_mostly tracer_enabled;
24
25static struct task_struct *wakeup_task;
26static int wakeup_cpu;
27static int wakeup_current_cpu;
28static unsigned wakeup_prio = -1;
29static int wakeup_rt;
30
31static arch_spinlock_t wakeup_lock =
32 (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
33
34static void wakeup_reset(struct trace_array *tr);
35static void __wakeup_reset(struct trace_array *tr);
36static int wakeup_graph_entry(struct ftrace_graph_ent *trace);
37static void wakeup_graph_return(struct ftrace_graph_ret *trace);
38
39static int save_lat_flag;
40
41#define TRACE_DISPLAY_GRAPH 1
42
43static struct tracer_opt trace_opts[] = {
44#ifdef CONFIG_FUNCTION_GRAPH_TRACER
45 /* display latency trace as call graph */
46 { TRACER_OPT(display-graph, TRACE_DISPLAY_GRAPH) },
47#endif
48 { } /* Empty entry */
49};
50
51static struct tracer_flags tracer_flags = {
52 .val = 0,
53 .opts = trace_opts,
54};
55
56#define is_graph() (tracer_flags.val & TRACE_DISPLAY_GRAPH)
57
58#ifdef CONFIG_FUNCTION_TRACER
59
60/*
61 * Prologue for the wakeup function tracers.
62 *
63 * Returns 1 if it is OK to continue, and preemption
64 * is disabled and data->disabled is incremented.
65 * 0 if the trace is to be ignored, and preemption
66 * is not disabled and data->disabled is
67 * kept the same.
68 *
69 * Note, this function is also used outside this ifdef but
70 * inside the #ifdef of the function graph tracer below.
71 * This is OK, since the function graph tracer is
72 * dependent on the function tracer.
73 */
74static int
75func_prolog_preempt_disable(struct trace_array *tr,
76 struct trace_array_cpu **data,
77 int *pc)
78{
79 long disabled;
80 int cpu;
81
82 if (likely(!wakeup_task))
83 return 0;
84
85 *pc = preempt_count();
86 preempt_disable_notrace();
87
88 cpu = raw_smp_processor_id();
89 if (cpu != wakeup_current_cpu)
90 goto out_enable;
91
92 *data = tr->data[cpu];
93 disabled = atomic_inc_return(&(*data)->disabled);
94 if (unlikely(disabled != 1))
95 goto out;
96
97 return 1;
98
99out:
100 atomic_dec(&(*data)->disabled);
101
102out_enable:
103 preempt_enable_notrace();
104 return 0;
105}
106
107/*
108 * wakeup uses its own tracer function to keep the overhead down:
109 */
110static void
111wakeup_tracer_call(unsigned long ip, unsigned long parent_ip)
112{
113 struct trace_array *tr = wakeup_trace;
114 struct trace_array_cpu *data;
115 unsigned long flags;
116 int pc;
117
118 if (!func_prolog_preempt_disable(tr, &data, &pc))
119 return;
120
121 local_irq_save(flags);
122 trace_function(tr, ip, parent_ip, flags, pc);
123 local_irq_restore(flags);
124
125 atomic_dec(&data->disabled);
126 preempt_enable_notrace();
127}
128
129static struct ftrace_ops trace_ops __read_mostly =
130{
131 .func = wakeup_tracer_call,
132 .flags = FTRACE_OPS_FL_GLOBAL,
133};
134#endif /* CONFIG_FUNCTION_TRACER */
135
136static int start_func_tracer(int graph)
137{
138 int ret;
139
140 if (!graph)
141 ret = register_ftrace_function(&trace_ops);
142 else
143 ret = register_ftrace_graph(&wakeup_graph_return,
144 &wakeup_graph_entry);
145
146 if (!ret && tracing_is_enabled())
147 tracer_enabled = 1;
148 else
149 tracer_enabled = 0;
150
151 return ret;
152}
153
154static void stop_func_tracer(int graph)
155{
156 tracer_enabled = 0;
157
158 if (!graph)
159 unregister_ftrace_function(&trace_ops);
160 else
161 unregister_ftrace_graph();
162}
163
164#ifdef CONFIG_FUNCTION_GRAPH_TRACER
165static int wakeup_set_flag(u32 old_flags, u32 bit, int set)
166{
167
168 if (!(bit & TRACE_DISPLAY_GRAPH))
169 return -EINVAL;
170
171 if (!(is_graph() ^ set))
172 return 0;
173
174 stop_func_tracer(!set);
175
176 wakeup_reset(wakeup_trace);
177 tracing_max_latency = 0;
178
179 return start_func_tracer(set);
180}
181
182static int wakeup_graph_entry(struct ftrace_graph_ent *trace)
183{
184 struct trace_array *tr = wakeup_trace;
185 struct trace_array_cpu *data;
186 unsigned long flags;
187 int pc, ret = 0;
188
189 if (!func_prolog_preempt_disable(tr, &data, &pc))
190 return 0;
191
192 local_save_flags(flags);
193 ret = __trace_graph_entry(tr, trace, flags, pc);
194 atomic_dec(&data->disabled);
195 preempt_enable_notrace();
196
197 return ret;
198}
199
200static void wakeup_graph_return(struct ftrace_graph_ret *trace)
201{
202 struct trace_array *tr = wakeup_trace;
203 struct trace_array_cpu *data;
204 unsigned long flags;
205 int pc;
206
207 if (!func_prolog_preempt_disable(tr, &data, &pc))
208 return;
209
210 local_save_flags(flags);
211 __trace_graph_return(tr, trace, flags, pc);
212 atomic_dec(&data->disabled);
213
214 preempt_enable_notrace();
215 return;
216}
217
218static void wakeup_trace_open(struct trace_iterator *iter)
219{
220 if (is_graph())
221 graph_trace_open(iter);
222}
223
224static void wakeup_trace_close(struct trace_iterator *iter)
225{
226 if (iter->private)
227 graph_trace_close(iter);
228}
229
230#define GRAPH_TRACER_FLAGS (TRACE_GRAPH_PRINT_PROC | \
231 TRACE_GRAPH_PRINT_ABS_TIME | \
232 TRACE_GRAPH_PRINT_DURATION)
233
234static enum print_line_t wakeup_print_line(struct trace_iterator *iter)
235{
236 /*
237 * In graph mode call the graph tracer output function,
238 * otherwise go with the TRACE_FN event handler
239 */
240 if (is_graph())
241 return print_graph_function_flags(iter, GRAPH_TRACER_FLAGS);
242
243 return TRACE_TYPE_UNHANDLED;
244}
245
246static void wakeup_print_header(struct seq_file *s)
247{
248 if (is_graph())
249 print_graph_headers_flags(s, GRAPH_TRACER_FLAGS);
250 else
251 trace_default_header(s);
252}
253
254static void
255__trace_function(struct trace_array *tr,
256 unsigned long ip, unsigned long parent_ip,
257 unsigned long flags, int pc)
258{
259 if (is_graph())
260 trace_graph_function(tr, ip, parent_ip, flags, pc);
261 else
262 trace_function(tr, ip, parent_ip, flags, pc);
263}
264#else
265#define __trace_function trace_function
266
267static int wakeup_set_flag(u32 old_flags, u32 bit, int set)
268{
269 return -EINVAL;
270}
271
272static int wakeup_graph_entry(struct ftrace_graph_ent *trace)
273{
274 return -1;
275}
276
277static enum print_line_t wakeup_print_line(struct trace_iterator *iter)
278{
279 return TRACE_TYPE_UNHANDLED;
280}
281
282static void wakeup_graph_return(struct ftrace_graph_ret *trace) { }
283static void wakeup_trace_open(struct trace_iterator *iter) { }
284static void wakeup_trace_close(struct trace_iterator *iter) { }
285
286#ifdef CONFIG_FUNCTION_TRACER
287static void wakeup_print_header(struct seq_file *s)
288{
289 trace_default_header(s);
290}
291#else
292static void wakeup_print_header(struct seq_file *s)
293{
294 trace_latency_header(s);
295}
296#endif /* CONFIG_FUNCTION_TRACER */
297#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
298
299/*
300 * Should this new latency be reported/recorded?
301 */
302static int report_latency(cycle_t delta)
303{
304 if (tracing_thresh) {
305 if (delta < tracing_thresh)
306 return 0;
307 } else {
308 if (delta <= tracing_max_latency)
309 return 0;
310 }
311 return 1;
312}
313
314static void
315probe_wakeup_migrate_task(void *ignore, struct task_struct *task, int cpu)
316{
317 if (task != wakeup_task)
318 return;
319
320 wakeup_current_cpu = cpu;
321}
322
323static void notrace
324probe_wakeup_sched_switch(void *ignore,
325 struct task_struct *prev, struct task_struct *next)
326{
327 struct trace_array_cpu *data;
328 cycle_t T0, T1, delta;
329 unsigned long flags;
330 long disabled;
331 int cpu;
332 int pc;
333
334 tracing_record_cmdline(prev);
335
336 if (unlikely(!tracer_enabled))
337 return;
338
339 /*
340 * When we start a new trace, we set wakeup_task to NULL
341 * and then set tracer_enabled = 1. We want to make sure
342 * that another CPU does not see the tracer_enabled = 1
343 * and the wakeup_task with an older task, that might
344 * actually be the same as next.
345 */
346 smp_rmb();
347
348 if (next != wakeup_task)
349 return;
350
351 pc = preempt_count();
352
353 /* disable local data, not wakeup_cpu data */
354 cpu = raw_smp_processor_id();
355 disabled = atomic_inc_return(&wakeup_trace->data[cpu]->disabled);
356 if (likely(disabled != 1))
357 goto out;
358
359 local_irq_save(flags);
360 arch_spin_lock(&wakeup_lock);
361
362 /* We could race with grabbing wakeup_lock */
363 if (unlikely(!tracer_enabled || next != wakeup_task))
364 goto out_unlock;
365
366 /* The task we are waiting for is waking up */
367 data = wakeup_trace->data[wakeup_cpu];
368
369 __trace_function(wakeup_trace, CALLER_ADDR0, CALLER_ADDR1, flags, pc);
370 tracing_sched_switch_trace(wakeup_trace, prev, next, flags, pc);
371
372 T0 = data->preempt_timestamp;
373 T1 = ftrace_now(cpu);
374 delta = T1-T0;
375
376 if (!report_latency(delta))
377 goto out_unlock;
378
379 if (likely(!is_tracing_stopped())) {
380 tracing_max_latency = delta;
381 update_max_tr(wakeup_trace, wakeup_task, wakeup_cpu);
382 }
383
384out_unlock:
385 __wakeup_reset(wakeup_trace);
386 arch_spin_unlock(&wakeup_lock);
387 local_irq_restore(flags);
388out:
389 atomic_dec(&wakeup_trace->data[cpu]->disabled);
390}
391
392static void __wakeup_reset(struct trace_array *tr)
393{
394 wakeup_cpu = -1;
395 wakeup_prio = -1;
396
397 if (wakeup_task)
398 put_task_struct(wakeup_task);
399
400 wakeup_task = NULL;
401}
402
403static void wakeup_reset(struct trace_array *tr)
404{
405 unsigned long flags;
406
407 tracing_reset_online_cpus(tr);
408
409 local_irq_save(flags);
410 arch_spin_lock(&wakeup_lock);
411 __wakeup_reset(tr);
412 arch_spin_unlock(&wakeup_lock);
413 local_irq_restore(flags);
414}
415
416static void
417probe_wakeup(void *ignore, struct task_struct *p, int success)
418{
419 struct trace_array_cpu *data;
420 int cpu = smp_processor_id();
421 unsigned long flags;
422 long disabled;
423 int pc;
424
425 if (likely(!tracer_enabled))
426 return;
427
428 tracing_record_cmdline(p);
429 tracing_record_cmdline(current);
430
431 if ((wakeup_rt && !rt_task(p)) ||
432 p->prio >= wakeup_prio ||
433 p->prio >= current->prio)
434 return;
435
436 pc = preempt_count();
437 disabled = atomic_inc_return(&wakeup_trace->data[cpu]->disabled);
438 if (unlikely(disabled != 1))
439 goto out;
440
441 /* interrupts should be off from try_to_wake_up */
442 arch_spin_lock(&wakeup_lock);
443
444 /* check for races. */
445 if (!tracer_enabled || p->prio >= wakeup_prio)
446 goto out_locked;
447
448 /* reset the trace */
449 __wakeup_reset(wakeup_trace);
450
451 wakeup_cpu = task_cpu(p);
452 wakeup_current_cpu = wakeup_cpu;
453 wakeup_prio = p->prio;
454
455 wakeup_task = p;
456 get_task_struct(wakeup_task);
457
458 local_save_flags(flags);
459
460 data = wakeup_trace->data[wakeup_cpu];
461 data->preempt_timestamp = ftrace_now(cpu);
462 tracing_sched_wakeup_trace(wakeup_trace, p, current, flags, pc);
463
464 /*
465 * We must be careful in using CALLER_ADDR2. But since wake_up
466 * is not called by an assembly function (where as schedule is)
467 * it should be safe to use it here.
468 */
469 __trace_function(wakeup_trace, CALLER_ADDR1, CALLER_ADDR2, flags, pc);
470
471out_locked:
472 arch_spin_unlock(&wakeup_lock);
473out:
474 atomic_dec(&wakeup_trace->data[cpu]->disabled);
475}
476
477static void start_wakeup_tracer(struct trace_array *tr)
478{
479 int ret;
480
481 ret = register_trace_sched_wakeup(probe_wakeup, NULL);
482 if (ret) {
483 pr_info("wakeup trace: Couldn't activate tracepoint"
484 " probe to kernel_sched_wakeup\n");
485 return;
486 }
487
488 ret = register_trace_sched_wakeup_new(probe_wakeup, NULL);
489 if (ret) {
490 pr_info("wakeup trace: Couldn't activate tracepoint"
491 " probe to kernel_sched_wakeup_new\n");
492 goto fail_deprobe;
493 }
494
495 ret = register_trace_sched_switch(probe_wakeup_sched_switch, NULL);
496 if (ret) {
497 pr_info("sched trace: Couldn't activate tracepoint"
498 " probe to kernel_sched_switch\n");
499 goto fail_deprobe_wake_new;
500 }
501
502 ret = register_trace_sched_migrate_task(probe_wakeup_migrate_task, NULL);
503 if (ret) {
504 pr_info("wakeup trace: Couldn't activate tracepoint"
505 " probe to kernel_sched_migrate_task\n");
506 return;
507 }
508
509 wakeup_reset(tr);
510
511 /*
512 * Don't let the tracer_enabled = 1 show up before
513 * the wakeup_task is reset. This may be overkill since
514 * wakeup_reset does a spin_unlock after setting the
515 * wakeup_task to NULL, but I want to be safe.
516 * This is a slow path anyway.
517 */
518 smp_wmb();
519
520 if (start_func_tracer(is_graph()))
521 printk(KERN_ERR "failed to start wakeup tracer\n");
522
523 return;
524fail_deprobe_wake_new:
525 unregister_trace_sched_wakeup_new(probe_wakeup, NULL);
526fail_deprobe:
527 unregister_trace_sched_wakeup(probe_wakeup, NULL);
528}
529
530static void stop_wakeup_tracer(struct trace_array *tr)
531{
532 tracer_enabled = 0;
533 stop_func_tracer(is_graph());
534 unregister_trace_sched_switch(probe_wakeup_sched_switch, NULL);
535 unregister_trace_sched_wakeup_new(probe_wakeup, NULL);
536 unregister_trace_sched_wakeup(probe_wakeup, NULL);
537 unregister_trace_sched_migrate_task(probe_wakeup_migrate_task, NULL);
538}
539
540static int __wakeup_tracer_init(struct trace_array *tr)
541{
542 save_lat_flag = trace_flags & TRACE_ITER_LATENCY_FMT;
543 trace_flags |= TRACE_ITER_LATENCY_FMT;
544
545 tracing_max_latency = 0;
546 wakeup_trace = tr;
547 start_wakeup_tracer(tr);
548 return 0;
549}
550
551static int wakeup_tracer_init(struct trace_array *tr)
552{
553 wakeup_rt = 0;
554 return __wakeup_tracer_init(tr);
555}
556
557static int wakeup_rt_tracer_init(struct trace_array *tr)
558{
559 wakeup_rt = 1;
560 return __wakeup_tracer_init(tr);
561}
562
563static void wakeup_tracer_reset(struct trace_array *tr)
564{
565 stop_wakeup_tracer(tr);
566 /* make sure we put back any tasks we are tracing */
567 wakeup_reset(tr);
568
569 if (!save_lat_flag)
570 trace_flags &= ~TRACE_ITER_LATENCY_FMT;
571}
572
573static void wakeup_tracer_start(struct trace_array *tr)
574{
575 wakeup_reset(tr);
576 tracer_enabled = 1;
577}
578
579static void wakeup_tracer_stop(struct trace_array *tr)
580{
581 tracer_enabled = 0;
582}
583
584static struct tracer wakeup_tracer __read_mostly =
585{
586 .name = "wakeup",
587 .init = wakeup_tracer_init,
588 .reset = wakeup_tracer_reset,
589 .start = wakeup_tracer_start,
590 .stop = wakeup_tracer_stop,
591 .print_max = 1,
592 .print_header = wakeup_print_header,
593 .print_line = wakeup_print_line,
594 .flags = &tracer_flags,
595 .set_flag = wakeup_set_flag,
596#ifdef CONFIG_FTRACE_SELFTEST
597 .selftest = trace_selftest_startup_wakeup,
598#endif
599 .open = wakeup_trace_open,
600 .close = wakeup_trace_close,
601 .use_max_tr = 1,
602};
603
604static struct tracer wakeup_rt_tracer __read_mostly =
605{
606 .name = "wakeup_rt",
607 .init = wakeup_rt_tracer_init,
608 .reset = wakeup_tracer_reset,
609 .start = wakeup_tracer_start,
610 .stop = wakeup_tracer_stop,
611 .wait_pipe = poll_wait_pipe,
612 .print_max = 1,
613 .print_header = wakeup_print_header,
614 .print_line = wakeup_print_line,
615 .flags = &tracer_flags,
616 .set_flag = wakeup_set_flag,
617#ifdef CONFIG_FTRACE_SELFTEST
618 .selftest = trace_selftest_startup_wakeup,
619#endif
620 .open = wakeup_trace_open,
621 .close = wakeup_trace_close,
622 .use_max_tr = 1,
623};
624
625__init static int init_wakeup_tracer(void)
626{
627 int ret;
628
629 ret = register_tracer(&wakeup_tracer);
630 if (ret)
631 return ret;
632
633 ret = register_tracer(&wakeup_rt_tracer);
634 if (ret)
635 return ret;
636
637 return 0;
638}
639device_initcall(init_wakeup_tracer);