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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 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);
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * trace task wakeup timings
4 *
5 * Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com>
6 * Copyright (C) 2008 Ingo Molnar <mingo@redhat.com>
7 *
8 * Based on code from the latency_tracer, that is:
9 *
10 * Copyright (C) 2004-2006 Ingo Molnar
11 * Copyright (C) 2004 Nadia Yvette Chambers
12 */
13#include <linux/module.h>
14#include <linux/kallsyms.h>
15#include <linux/uaccess.h>
16#include <linux/ftrace.h>
17#include <linux/sched/rt.h>
18#include <linux/sched/deadline.h>
19#include <trace/events/sched.h>
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 bool wakeup_rt;
30static bool wakeup_dl;
31static bool tracing_dl;
32
33static arch_spinlock_t wakeup_lock =
34 (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
35
36static void wakeup_reset(struct trace_array *tr);
37static void __wakeup_reset(struct trace_array *tr);
38static int start_func_tracer(struct trace_array *tr, int graph);
39static void stop_func_tracer(struct trace_array *tr, int graph);
40
41static int save_flags;
42
43#ifdef CONFIG_FUNCTION_GRAPH_TRACER
44# define is_graph(tr) ((tr)->trace_flags & TRACE_ITER_DISPLAY_GRAPH)
45#else
46# define is_graph(tr) false
47#endif
48
49#ifdef CONFIG_FUNCTION_TRACER
50
51static bool function_enabled;
52
53/*
54 * Prologue for the wakeup function tracers.
55 *
56 * Returns 1 if it is OK to continue, and preemption
57 * is disabled and data->disabled is incremented.
58 * 0 if the trace is to be ignored, and preemption
59 * is not disabled and data->disabled is
60 * kept the same.
61 *
62 * Note, this function is also used outside this ifdef but
63 * inside the #ifdef of the function graph tracer below.
64 * This is OK, since the function graph tracer is
65 * dependent on the function tracer.
66 */
67static int
68func_prolog_preempt_disable(struct trace_array *tr,
69 struct trace_array_cpu **data,
70 unsigned int *trace_ctx)
71{
72 long disabled;
73 int cpu;
74
75 if (likely(!wakeup_task))
76 return 0;
77
78 *trace_ctx = tracing_gen_ctx();
79 preempt_disable_notrace();
80
81 cpu = raw_smp_processor_id();
82 if (cpu != wakeup_current_cpu)
83 goto out_enable;
84
85 *data = per_cpu_ptr(tr->array_buffer.data, cpu);
86 disabled = atomic_inc_return(&(*data)->disabled);
87 if (unlikely(disabled != 1))
88 goto out;
89
90 return 1;
91
92out:
93 atomic_dec(&(*data)->disabled);
94
95out_enable:
96 preempt_enable_notrace();
97 return 0;
98}
99
100#ifdef CONFIG_FUNCTION_GRAPH_TRACER
101
102static int wakeup_display_graph(struct trace_array *tr, int set)
103{
104 if (!(is_graph(tr) ^ set))
105 return 0;
106
107 stop_func_tracer(tr, !set);
108
109 wakeup_reset(wakeup_trace);
110 tr->max_latency = 0;
111
112 return start_func_tracer(tr, set);
113}
114
115static int wakeup_graph_entry(struct ftrace_graph_ent *trace)
116{
117 struct trace_array *tr = wakeup_trace;
118 struct trace_array_cpu *data;
119 unsigned int trace_ctx;
120 int ret = 0;
121
122 if (ftrace_graph_ignore_func(trace))
123 return 0;
124 /*
125 * Do not trace a function if it's filtered by set_graph_notrace.
126 * Make the index of ret stack negative to indicate that it should
127 * ignore further functions. But it needs its own ret stack entry
128 * to recover the original index in order to continue tracing after
129 * returning from the function.
130 */
131 if (ftrace_graph_notrace_addr(trace->func))
132 return 1;
133
134 if (!func_prolog_preempt_disable(tr, &data, &trace_ctx))
135 return 0;
136
137 ret = __trace_graph_entry(tr, trace, trace_ctx);
138 atomic_dec(&data->disabled);
139 preempt_enable_notrace();
140
141 return ret;
142}
143
144static void wakeup_graph_return(struct ftrace_graph_ret *trace)
145{
146 struct trace_array *tr = wakeup_trace;
147 struct trace_array_cpu *data;
148 unsigned int trace_ctx;
149
150 ftrace_graph_addr_finish(trace);
151
152 if (!func_prolog_preempt_disable(tr, &data, &trace_ctx))
153 return;
154
155 __trace_graph_return(tr, trace, trace_ctx);
156 atomic_dec(&data->disabled);
157
158 preempt_enable_notrace();
159 return;
160}
161
162static struct fgraph_ops fgraph_wakeup_ops = {
163 .entryfunc = &wakeup_graph_entry,
164 .retfunc = &wakeup_graph_return,
165};
166
167static void wakeup_trace_open(struct trace_iterator *iter)
168{
169 if (is_graph(iter->tr))
170 graph_trace_open(iter);
171}
172
173static void wakeup_trace_close(struct trace_iterator *iter)
174{
175 if (iter->private)
176 graph_trace_close(iter);
177}
178
179#define GRAPH_TRACER_FLAGS (TRACE_GRAPH_PRINT_PROC | \
180 TRACE_GRAPH_PRINT_CPU | \
181 TRACE_GRAPH_PRINT_REL_TIME | \
182 TRACE_GRAPH_PRINT_DURATION | \
183 TRACE_GRAPH_PRINT_OVERHEAD | \
184 TRACE_GRAPH_PRINT_IRQS)
185
186static enum print_line_t wakeup_print_line(struct trace_iterator *iter)
187{
188 /*
189 * In graph mode call the graph tracer output function,
190 * otherwise go with the TRACE_FN event handler
191 */
192 if (is_graph(iter->tr))
193 return print_graph_function_flags(iter, GRAPH_TRACER_FLAGS);
194
195 return TRACE_TYPE_UNHANDLED;
196}
197
198static void wakeup_print_header(struct seq_file *s)
199{
200 if (is_graph(wakeup_trace))
201 print_graph_headers_flags(s, GRAPH_TRACER_FLAGS);
202 else
203 trace_default_header(s);
204}
205#endif /* else CONFIG_FUNCTION_GRAPH_TRACER */
206
207/*
208 * wakeup uses its own tracer function to keep the overhead down:
209 */
210static void
211wakeup_tracer_call(unsigned long ip, unsigned long parent_ip,
212 struct ftrace_ops *op, struct ftrace_regs *fregs)
213{
214 struct trace_array *tr = wakeup_trace;
215 struct trace_array_cpu *data;
216 unsigned long flags;
217 unsigned int trace_ctx;
218
219 if (!func_prolog_preempt_disable(tr, &data, &trace_ctx))
220 return;
221
222 local_irq_save(flags);
223 trace_function(tr, ip, parent_ip, trace_ctx);
224 local_irq_restore(flags);
225
226 atomic_dec(&data->disabled);
227 preempt_enable_notrace();
228}
229
230static int register_wakeup_function(struct trace_array *tr, int graph, int set)
231{
232 int ret;
233
234 /* 'set' is set if TRACE_ITER_FUNCTION is about to be set */
235 if (function_enabled || (!set && !(tr->trace_flags & TRACE_ITER_FUNCTION)))
236 return 0;
237
238 if (graph)
239 ret = register_ftrace_graph(&fgraph_wakeup_ops);
240 else
241 ret = register_ftrace_function(tr->ops);
242
243 if (!ret)
244 function_enabled = true;
245
246 return ret;
247}
248
249static void unregister_wakeup_function(struct trace_array *tr, int graph)
250{
251 if (!function_enabled)
252 return;
253
254 if (graph)
255 unregister_ftrace_graph(&fgraph_wakeup_ops);
256 else
257 unregister_ftrace_function(tr->ops);
258
259 function_enabled = false;
260}
261
262static int wakeup_function_set(struct trace_array *tr, u32 mask, int set)
263{
264 if (!(mask & TRACE_ITER_FUNCTION))
265 return 0;
266
267 if (set)
268 register_wakeup_function(tr, is_graph(tr), 1);
269 else
270 unregister_wakeup_function(tr, is_graph(tr));
271 return 1;
272}
273#else /* CONFIG_FUNCTION_TRACER */
274static int register_wakeup_function(struct trace_array *tr, int graph, int set)
275{
276 return 0;
277}
278static void unregister_wakeup_function(struct trace_array *tr, int graph) { }
279static int wakeup_function_set(struct trace_array *tr, u32 mask, int set)
280{
281 return 0;
282}
283#endif /* else CONFIG_FUNCTION_TRACER */
284
285#ifndef CONFIG_FUNCTION_GRAPH_TRACER
286static enum print_line_t wakeup_print_line(struct trace_iterator *iter)
287{
288 return TRACE_TYPE_UNHANDLED;
289}
290
291static void wakeup_trace_open(struct trace_iterator *iter) { }
292static void wakeup_trace_close(struct trace_iterator *iter) { }
293
294static void wakeup_print_header(struct seq_file *s)
295{
296 trace_default_header(s);
297}
298#endif /* !CONFIG_FUNCTION_GRAPH_TRACER */
299
300static void
301__trace_function(struct trace_array *tr,
302 unsigned long ip, unsigned long parent_ip,
303 unsigned int trace_ctx)
304{
305 if (is_graph(tr))
306 trace_graph_function(tr, ip, parent_ip, trace_ctx);
307 else
308 trace_function(tr, ip, parent_ip, trace_ctx);
309}
310
311static int wakeup_flag_changed(struct trace_array *tr, u32 mask, int set)
312{
313 struct tracer *tracer = tr->current_trace;
314
315 if (wakeup_function_set(tr, mask, set))
316 return 0;
317
318#ifdef CONFIG_FUNCTION_GRAPH_TRACER
319 if (mask & TRACE_ITER_DISPLAY_GRAPH)
320 return wakeup_display_graph(tr, set);
321#endif
322
323 return trace_keep_overwrite(tracer, mask, set);
324}
325
326static int start_func_tracer(struct trace_array *tr, int graph)
327{
328 int ret;
329
330 ret = register_wakeup_function(tr, graph, 0);
331
332 if (!ret && tracing_is_enabled())
333 tracer_enabled = 1;
334 else
335 tracer_enabled = 0;
336
337 return ret;
338}
339
340static void stop_func_tracer(struct trace_array *tr, int graph)
341{
342 tracer_enabled = 0;
343
344 unregister_wakeup_function(tr, graph);
345}
346
347/*
348 * Should this new latency be reported/recorded?
349 */
350static bool report_latency(struct trace_array *tr, u64 delta)
351{
352 if (tracing_thresh) {
353 if (delta < tracing_thresh)
354 return false;
355 } else {
356 if (delta <= tr->max_latency)
357 return false;
358 }
359 return true;
360}
361
362static void
363probe_wakeup_migrate_task(void *ignore, struct task_struct *task, int cpu)
364{
365 if (task != wakeup_task)
366 return;
367
368 wakeup_current_cpu = cpu;
369}
370
371static void
372tracing_sched_switch_trace(struct trace_array *tr,
373 struct task_struct *prev,
374 struct task_struct *next,
375 unsigned int trace_ctx)
376{
377 struct trace_event_call *call = &event_context_switch;
378 struct trace_buffer *buffer = tr->array_buffer.buffer;
379 struct ring_buffer_event *event;
380 struct ctx_switch_entry *entry;
381
382 event = trace_buffer_lock_reserve(buffer, TRACE_CTX,
383 sizeof(*entry), trace_ctx);
384 if (!event)
385 return;
386 entry = ring_buffer_event_data(event);
387 entry->prev_pid = prev->pid;
388 entry->prev_prio = prev->prio;
389 entry->prev_state = task_state_index(prev);
390 entry->next_pid = next->pid;
391 entry->next_prio = next->prio;
392 entry->next_state = task_state_index(next);
393 entry->next_cpu = task_cpu(next);
394
395 if (!call_filter_check_discard(call, entry, buffer, event))
396 trace_buffer_unlock_commit(tr, buffer, event, trace_ctx);
397}
398
399static void
400tracing_sched_wakeup_trace(struct trace_array *tr,
401 struct task_struct *wakee,
402 struct task_struct *curr,
403 unsigned int trace_ctx)
404{
405 struct trace_event_call *call = &event_wakeup;
406 struct ring_buffer_event *event;
407 struct ctx_switch_entry *entry;
408 struct trace_buffer *buffer = tr->array_buffer.buffer;
409
410 event = trace_buffer_lock_reserve(buffer, TRACE_WAKE,
411 sizeof(*entry), trace_ctx);
412 if (!event)
413 return;
414 entry = ring_buffer_event_data(event);
415 entry->prev_pid = curr->pid;
416 entry->prev_prio = curr->prio;
417 entry->prev_state = task_state_index(curr);
418 entry->next_pid = wakee->pid;
419 entry->next_prio = wakee->prio;
420 entry->next_state = task_state_index(wakee);
421 entry->next_cpu = task_cpu(wakee);
422
423 if (!call_filter_check_discard(call, entry, buffer, event))
424 trace_buffer_unlock_commit(tr, buffer, event, trace_ctx);
425}
426
427static void notrace
428probe_wakeup_sched_switch(void *ignore, bool preempt,
429 struct task_struct *prev, struct task_struct *next)
430{
431 struct trace_array_cpu *data;
432 u64 T0, T1, delta;
433 unsigned long flags;
434 long disabled;
435 int cpu;
436 unsigned int trace_ctx;
437
438 tracing_record_cmdline(prev);
439
440 if (unlikely(!tracer_enabled))
441 return;
442
443 /*
444 * When we start a new trace, we set wakeup_task to NULL
445 * and then set tracer_enabled = 1. We want to make sure
446 * that another CPU does not see the tracer_enabled = 1
447 * and the wakeup_task with an older task, that might
448 * actually be the same as next.
449 */
450 smp_rmb();
451
452 if (next != wakeup_task)
453 return;
454
455 /* disable local data, not wakeup_cpu data */
456 cpu = raw_smp_processor_id();
457 disabled = atomic_inc_return(&per_cpu_ptr(wakeup_trace->array_buffer.data, cpu)->disabled);
458 if (likely(disabled != 1))
459 goto out;
460
461 local_irq_save(flags);
462 trace_ctx = tracing_gen_ctx_flags(flags);
463
464 arch_spin_lock(&wakeup_lock);
465
466 /* We could race with grabbing wakeup_lock */
467 if (unlikely(!tracer_enabled || next != wakeup_task))
468 goto out_unlock;
469
470 /* The task we are waiting for is waking up */
471 data = per_cpu_ptr(wakeup_trace->array_buffer.data, wakeup_cpu);
472
473 __trace_function(wakeup_trace, CALLER_ADDR0, CALLER_ADDR1, trace_ctx);
474 tracing_sched_switch_trace(wakeup_trace, prev, next, trace_ctx);
475 __trace_stack(wakeup_trace, trace_ctx, 0);
476
477 T0 = data->preempt_timestamp;
478 T1 = ftrace_now(cpu);
479 delta = T1-T0;
480
481 if (!report_latency(wakeup_trace, delta))
482 goto out_unlock;
483
484 if (likely(!is_tracing_stopped())) {
485 wakeup_trace->max_latency = delta;
486 update_max_tr(wakeup_trace, wakeup_task, wakeup_cpu, NULL);
487 }
488
489out_unlock:
490 __wakeup_reset(wakeup_trace);
491 arch_spin_unlock(&wakeup_lock);
492 local_irq_restore(flags);
493out:
494 atomic_dec(&per_cpu_ptr(wakeup_trace->array_buffer.data, cpu)->disabled);
495}
496
497static void __wakeup_reset(struct trace_array *tr)
498{
499 wakeup_cpu = -1;
500 wakeup_prio = -1;
501 tracing_dl = false;
502
503 if (wakeup_task)
504 put_task_struct(wakeup_task);
505
506 wakeup_task = NULL;
507}
508
509static void wakeup_reset(struct trace_array *tr)
510{
511 unsigned long flags;
512
513 tracing_reset_online_cpus(&tr->array_buffer);
514
515 local_irq_save(flags);
516 arch_spin_lock(&wakeup_lock);
517 __wakeup_reset(tr);
518 arch_spin_unlock(&wakeup_lock);
519 local_irq_restore(flags);
520}
521
522static void
523probe_wakeup(void *ignore, struct task_struct *p)
524{
525 struct trace_array_cpu *data;
526 int cpu = smp_processor_id();
527 long disabled;
528 unsigned int trace_ctx;
529
530 if (likely(!tracer_enabled))
531 return;
532
533 tracing_record_cmdline(p);
534 tracing_record_cmdline(current);
535
536 /*
537 * Semantic is like this:
538 * - wakeup tracer handles all tasks in the system, independently
539 * from their scheduling class;
540 * - wakeup_rt tracer handles tasks belonging to sched_dl and
541 * sched_rt class;
542 * - wakeup_dl handles tasks belonging to sched_dl class only.
543 */
544 if (tracing_dl || (wakeup_dl && !dl_task(p)) ||
545 (wakeup_rt && !dl_task(p) && !rt_task(p)) ||
546 (!dl_task(p) && (p->prio >= wakeup_prio || p->prio >= current->prio)))
547 return;
548
549 disabled = atomic_inc_return(&per_cpu_ptr(wakeup_trace->array_buffer.data, cpu)->disabled);
550 if (unlikely(disabled != 1))
551 goto out;
552
553 trace_ctx = tracing_gen_ctx();
554
555 /* interrupts should be off from try_to_wake_up */
556 arch_spin_lock(&wakeup_lock);
557
558 /* check for races. */
559 if (!tracer_enabled || tracing_dl ||
560 (!dl_task(p) && p->prio >= wakeup_prio))
561 goto out_locked;
562
563 /* reset the trace */
564 __wakeup_reset(wakeup_trace);
565
566 wakeup_cpu = task_cpu(p);
567 wakeup_current_cpu = wakeup_cpu;
568 wakeup_prio = p->prio;
569
570 /*
571 * Once you start tracing a -deadline task, don't bother tracing
572 * another task until the first one wakes up.
573 */
574 if (dl_task(p))
575 tracing_dl = true;
576 else
577 tracing_dl = false;
578
579 wakeup_task = get_task_struct(p);
580
581 data = per_cpu_ptr(wakeup_trace->array_buffer.data, wakeup_cpu);
582 data->preempt_timestamp = ftrace_now(cpu);
583 tracing_sched_wakeup_trace(wakeup_trace, p, current, trace_ctx);
584 __trace_stack(wakeup_trace, trace_ctx, 0);
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, trace_ctx);
592
593out_locked:
594 arch_spin_unlock(&wakeup_lock);
595out:
596 atomic_dec(&per_cpu_ptr(wakeup_trace->array_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 goto fail_deprobe_sched_switch;
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_sched_switch:
647 unregister_trace_sched_switch(probe_wakeup_sched_switch, NULL);
648fail_deprobe_wake_new:
649 unregister_trace_sched_wakeup_new(probe_wakeup, NULL);
650fail_deprobe:
651 unregister_trace_sched_wakeup(probe_wakeup, NULL);
652}
653
654static void stop_wakeup_tracer(struct trace_array *tr)
655{
656 tracer_enabled = 0;
657 stop_func_tracer(tr, is_graph(tr));
658 unregister_trace_sched_switch(probe_wakeup_sched_switch, NULL);
659 unregister_trace_sched_wakeup_new(probe_wakeup, NULL);
660 unregister_trace_sched_wakeup(probe_wakeup, NULL);
661 unregister_trace_sched_migrate_task(probe_wakeup_migrate_task, NULL);
662}
663
664static bool wakeup_busy;
665
666static int __wakeup_tracer_init(struct trace_array *tr)
667{
668 save_flags = tr->trace_flags;
669
670 /* non overwrite screws up the latency tracers */
671 set_tracer_flag(tr, TRACE_ITER_OVERWRITE, 1);
672 set_tracer_flag(tr, TRACE_ITER_LATENCY_FMT, 1);
673
674 tr->max_latency = 0;
675 wakeup_trace = tr;
676 ftrace_init_array_ops(tr, wakeup_tracer_call);
677 start_wakeup_tracer(tr);
678
679 wakeup_busy = true;
680 return 0;
681}
682
683static int wakeup_tracer_init(struct trace_array *tr)
684{
685 if (wakeup_busy)
686 return -EBUSY;
687
688 wakeup_dl = false;
689 wakeup_rt = false;
690 return __wakeup_tracer_init(tr);
691}
692
693static int wakeup_rt_tracer_init(struct trace_array *tr)
694{
695 if (wakeup_busy)
696 return -EBUSY;
697
698 wakeup_dl = false;
699 wakeup_rt = true;
700 return __wakeup_tracer_init(tr);
701}
702
703static int wakeup_dl_tracer_init(struct trace_array *tr)
704{
705 if (wakeup_busy)
706 return -EBUSY;
707
708 wakeup_dl = true;
709 wakeup_rt = false;
710 return __wakeup_tracer_init(tr);
711}
712
713static void wakeup_tracer_reset(struct trace_array *tr)
714{
715 int lat_flag = save_flags & TRACE_ITER_LATENCY_FMT;
716 int overwrite_flag = save_flags & TRACE_ITER_OVERWRITE;
717
718 stop_wakeup_tracer(tr);
719 /* make sure we put back any tasks we are tracing */
720 wakeup_reset(tr);
721
722 set_tracer_flag(tr, TRACE_ITER_LATENCY_FMT, lat_flag);
723 set_tracer_flag(tr, TRACE_ITER_OVERWRITE, overwrite_flag);
724 ftrace_reset_array_ops(tr);
725 wakeup_busy = false;
726}
727
728static void wakeup_tracer_start(struct trace_array *tr)
729{
730 wakeup_reset(tr);
731 tracer_enabled = 1;
732}
733
734static void wakeup_tracer_stop(struct trace_array *tr)
735{
736 tracer_enabled = 0;
737}
738
739static struct tracer wakeup_tracer __read_mostly =
740{
741 .name = "wakeup",
742 .init = wakeup_tracer_init,
743 .reset = wakeup_tracer_reset,
744 .start = wakeup_tracer_start,
745 .stop = wakeup_tracer_stop,
746 .print_max = true,
747 .print_header = wakeup_print_header,
748 .print_line = wakeup_print_line,
749 .flag_changed = wakeup_flag_changed,
750#ifdef CONFIG_FTRACE_SELFTEST
751 .selftest = trace_selftest_startup_wakeup,
752#endif
753 .open = wakeup_trace_open,
754 .close = wakeup_trace_close,
755 .allow_instances = true,
756 .use_max_tr = true,
757};
758
759static struct tracer wakeup_rt_tracer __read_mostly =
760{
761 .name = "wakeup_rt",
762 .init = wakeup_rt_tracer_init,
763 .reset = wakeup_tracer_reset,
764 .start = wakeup_tracer_start,
765 .stop = wakeup_tracer_stop,
766 .print_max = true,
767 .print_header = wakeup_print_header,
768 .print_line = wakeup_print_line,
769 .flag_changed = wakeup_flag_changed,
770#ifdef CONFIG_FTRACE_SELFTEST
771 .selftest = trace_selftest_startup_wakeup,
772#endif
773 .open = wakeup_trace_open,
774 .close = wakeup_trace_close,
775 .allow_instances = true,
776 .use_max_tr = true,
777};
778
779static struct tracer wakeup_dl_tracer __read_mostly =
780{
781 .name = "wakeup_dl",
782 .init = wakeup_dl_tracer_init,
783 .reset = wakeup_tracer_reset,
784 .start = wakeup_tracer_start,
785 .stop = wakeup_tracer_stop,
786 .print_max = true,
787 .print_header = wakeup_print_header,
788 .print_line = wakeup_print_line,
789 .flag_changed = wakeup_flag_changed,
790#ifdef CONFIG_FTRACE_SELFTEST
791 .selftest = trace_selftest_startup_wakeup,
792#endif
793 .open = wakeup_trace_open,
794 .close = wakeup_trace_close,
795 .allow_instances = true,
796 .use_max_tr = true,
797};
798
799__init static int init_wakeup_tracer(void)
800{
801 int ret;
802
803 ret = register_tracer(&wakeup_tracer);
804 if (ret)
805 return ret;
806
807 ret = register_tracer(&wakeup_rt_tracer);
808 if (ret)
809 return ret;
810
811 ret = register_tracer(&wakeup_dl_tracer);
812 if (ret)
813 return ret;
814
815 return 0;
816}
817core_initcall(init_wakeup_tracer);