Merge remote-tracking branch 'pfdo/drm-fixes' into drm-next
[firefly-linux-kernel-4.4.55.git] / kernel / trace / trace_sched_wakeup.c
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/fs.h>
14 #include <linux/debugfs.h>
15 #include <linux/kallsyms.h>
16 #include <linux/uaccess.h>
17 #include <linux/ftrace.h>
18 #include <linux/sched/rt.h>
19 #include <trace/events/sched.h>
20 #include "trace.h"
21
22 static struct trace_array       *wakeup_trace;
23 static int __read_mostly        tracer_enabled;
24
25 static struct task_struct       *wakeup_task;
26 static int                      wakeup_cpu;
27 static int                      wakeup_current_cpu;
28 static unsigned                 wakeup_prio = -1;
29 static int                      wakeup_rt;
30
31 static arch_spinlock_t wakeup_lock =
32         (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
33
34 static void wakeup_reset(struct trace_array *tr);
35 static void __wakeup_reset(struct trace_array *tr);
36 static int wakeup_graph_entry(struct ftrace_graph_ent *trace);
37 static void wakeup_graph_return(struct ftrace_graph_ret *trace);
38
39 static int save_flags;
40 static bool function_enabled;
41
42 #define TRACE_DISPLAY_GRAPH     1
43
44 static struct tracer_opt trace_opts[] = {
45 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
46         /* display latency trace as call graph */
47         { TRACER_OPT(display-graph, TRACE_DISPLAY_GRAPH) },
48 #endif
49         { } /* Empty entry */
50 };
51
52 static struct tracer_flags tracer_flags = {
53         .val  = 0,
54         .opts = trace_opts,
55 };
56
57 #define is_graph() (tracer_flags.val & TRACE_DISPLAY_GRAPH)
58
59 #ifdef CONFIG_FUNCTION_TRACER
60
61 /*
62  * Prologue for the wakeup function tracers.
63  *
64  * Returns 1 if it is OK to continue, and preemption
65  *            is disabled and data->disabled is incremented.
66  *         0 if the trace is to be ignored, and preemption
67  *            is not disabled and data->disabled is
68  *            kept the same.
69  *
70  * Note, this function is also used outside this ifdef but
71  *  inside the #ifdef of the function graph tracer below.
72  *  This is OK, since the function graph tracer is
73  *  dependent on the function tracer.
74  */
75 static int
76 func_prolog_preempt_disable(struct trace_array *tr,
77                             struct trace_array_cpu **data,
78                             int *pc)
79 {
80         long disabled;
81         int cpu;
82
83         if (likely(!wakeup_task))
84                 return 0;
85
86         *pc = preempt_count();
87         preempt_disable_notrace();
88
89         cpu = raw_smp_processor_id();
90         if (cpu != wakeup_current_cpu)
91                 goto out_enable;
92
93         *data = per_cpu_ptr(tr->trace_buffer.data, cpu);
94         disabled = atomic_inc_return(&(*data)->disabled);
95         if (unlikely(disabled != 1))
96                 goto out;
97
98         return 1;
99
100 out:
101         atomic_dec(&(*data)->disabled);
102
103 out_enable:
104         preempt_enable_notrace();
105         return 0;
106 }
107
108 /*
109  * wakeup uses its own tracer function to keep the overhead down:
110  */
111 static void
112 wakeup_tracer_call(unsigned long ip, unsigned long parent_ip,
113                    struct ftrace_ops *op, struct pt_regs *pt_regs)
114 {
115         struct trace_array *tr = wakeup_trace;
116         struct trace_array_cpu *data;
117         unsigned long flags;
118         int pc;
119
120         if (!func_prolog_preempt_disable(tr, &data, &pc))
121                 return;
122
123         local_irq_save(flags);
124         trace_function(tr, ip, parent_ip, flags, pc);
125         local_irq_restore(flags);
126
127         atomic_dec(&data->disabled);
128         preempt_enable_notrace();
129 }
130
131 static struct ftrace_ops trace_ops __read_mostly =
132 {
133         .func = wakeup_tracer_call,
134         .flags = FTRACE_OPS_FL_GLOBAL | FTRACE_OPS_FL_RECURSION_SAFE,
135 };
136 #endif /* CONFIG_FUNCTION_TRACER */
137
138 static int register_wakeup_function(int graph, int set)
139 {
140         int ret;
141
142         /* 'set' is set if TRACE_ITER_FUNCTION is about to be set */
143         if (function_enabled || (!set && !(trace_flags & TRACE_ITER_FUNCTION)))
144                 return 0;
145
146         if (graph)
147                 ret = register_ftrace_graph(&wakeup_graph_return,
148                                             &wakeup_graph_entry);
149         else
150                 ret = register_ftrace_function(&trace_ops);
151
152         if (!ret)
153                 function_enabled = true;
154
155         return ret;
156 }
157
158 static void unregister_wakeup_function(int graph)
159 {
160         if (!function_enabled)
161                 return;
162
163         if (graph)
164                 unregister_ftrace_graph();
165         else
166                 unregister_ftrace_function(&trace_ops);
167
168         function_enabled = false;
169 }
170
171 static void wakeup_function_set(int set)
172 {
173         if (set)
174                 register_wakeup_function(is_graph(), 1);
175         else
176                 unregister_wakeup_function(is_graph());
177 }
178
179 static int wakeup_flag_changed(struct tracer *tracer, u32 mask, int set)
180 {
181         if (mask & TRACE_ITER_FUNCTION)
182                 wakeup_function_set(set);
183
184         return trace_keep_overwrite(tracer, mask, set);
185 }
186
187 static int start_func_tracer(int graph)
188 {
189         int ret;
190
191         ret = register_wakeup_function(graph, 0);
192
193         if (!ret && tracing_is_enabled())
194                 tracer_enabled = 1;
195         else
196                 tracer_enabled = 0;
197
198         return ret;
199 }
200
201 static void stop_func_tracer(int graph)
202 {
203         tracer_enabled = 0;
204
205         unregister_wakeup_function(graph);
206 }
207
208 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
209 static int wakeup_set_flag(u32 old_flags, u32 bit, int set)
210 {
211
212         if (!(bit & TRACE_DISPLAY_GRAPH))
213                 return -EINVAL;
214
215         if (!(is_graph() ^ set))
216                 return 0;
217
218         stop_func_tracer(!set);
219
220         wakeup_reset(wakeup_trace);
221         tracing_max_latency = 0;
222
223         return start_func_tracer(set);
224 }
225
226 static int wakeup_graph_entry(struct ftrace_graph_ent *trace)
227 {
228         struct trace_array *tr = wakeup_trace;
229         struct trace_array_cpu *data;
230         unsigned long flags;
231         int pc, ret = 0;
232
233         if (!func_prolog_preempt_disable(tr, &data, &pc))
234                 return 0;
235
236         local_save_flags(flags);
237         ret = __trace_graph_entry(tr, trace, flags, pc);
238         atomic_dec(&data->disabled);
239         preempt_enable_notrace();
240
241         return ret;
242 }
243
244 static void wakeup_graph_return(struct ftrace_graph_ret *trace)
245 {
246         struct trace_array *tr = wakeup_trace;
247         struct trace_array_cpu *data;
248         unsigned long flags;
249         int pc;
250
251         if (!func_prolog_preempt_disable(tr, &data, &pc))
252                 return;
253
254         local_save_flags(flags);
255         __trace_graph_return(tr, trace, flags, pc);
256         atomic_dec(&data->disabled);
257
258         preempt_enable_notrace();
259         return;
260 }
261
262 static void wakeup_trace_open(struct trace_iterator *iter)
263 {
264         if (is_graph())
265                 graph_trace_open(iter);
266 }
267
268 static void wakeup_trace_close(struct trace_iterator *iter)
269 {
270         if (iter->private)
271                 graph_trace_close(iter);
272 }
273
274 #define GRAPH_TRACER_FLAGS (TRACE_GRAPH_PRINT_PROC | \
275                             TRACE_GRAPH_PRINT_ABS_TIME | \
276                             TRACE_GRAPH_PRINT_DURATION)
277
278 static enum print_line_t wakeup_print_line(struct trace_iterator *iter)
279 {
280         /*
281          * In graph mode call the graph tracer output function,
282          * otherwise go with the TRACE_FN event handler
283          */
284         if (is_graph())
285                 return print_graph_function_flags(iter, GRAPH_TRACER_FLAGS);
286
287         return TRACE_TYPE_UNHANDLED;
288 }
289
290 static void wakeup_print_header(struct seq_file *s)
291 {
292         if (is_graph())
293                 print_graph_headers_flags(s, GRAPH_TRACER_FLAGS);
294         else
295                 trace_default_header(s);
296 }
297
298 static void
299 __trace_function(struct trace_array *tr,
300                  unsigned long ip, unsigned long parent_ip,
301                  unsigned long flags, int pc)
302 {
303         if (is_graph())
304                 trace_graph_function(tr, ip, parent_ip, flags, pc);
305         else
306                 trace_function(tr, ip, parent_ip, flags, pc);
307 }
308 #else
309 #define __trace_function trace_function
310
311 static int wakeup_set_flag(u32 old_flags, u32 bit, int set)
312 {
313         return -EINVAL;
314 }
315
316 static int wakeup_graph_entry(struct ftrace_graph_ent *trace)
317 {
318         return -1;
319 }
320
321 static enum print_line_t wakeup_print_line(struct trace_iterator *iter)
322 {
323         return TRACE_TYPE_UNHANDLED;
324 }
325
326 static void wakeup_graph_return(struct ftrace_graph_ret *trace) { }
327 static void wakeup_trace_open(struct trace_iterator *iter) { }
328 static void wakeup_trace_close(struct trace_iterator *iter) { }
329
330 #ifdef CONFIG_FUNCTION_TRACER
331 static void wakeup_print_header(struct seq_file *s)
332 {
333         trace_default_header(s);
334 }
335 #else
336 static void wakeup_print_header(struct seq_file *s)
337 {
338         trace_latency_header(s);
339 }
340 #endif /* CONFIG_FUNCTION_TRACER */
341 #endif /* CONFIG_FUNCTION_GRAPH_TRACER */
342
343 /*
344  * Should this new latency be reported/recorded?
345  */
346 static int report_latency(cycle_t delta)
347 {
348         if (tracing_thresh) {
349                 if (delta < tracing_thresh)
350                         return 0;
351         } else {
352                 if (delta <= tracing_max_latency)
353                         return 0;
354         }
355         return 1;
356 }
357
358 static void
359 probe_wakeup_migrate_task(void *ignore, struct task_struct *task, int cpu)
360 {
361         if (task != wakeup_task)
362                 return;
363
364         wakeup_current_cpu = cpu;
365 }
366
367 static void notrace
368 probe_wakeup_sched_switch(void *ignore,
369                           struct task_struct *prev, struct task_struct *next)
370 {
371         struct trace_array_cpu *data;
372         cycle_t T0, T1, delta;
373         unsigned long flags;
374         long disabled;
375         int cpu;
376         int pc;
377
378         tracing_record_cmdline(prev);
379
380         if (unlikely(!tracer_enabled))
381                 return;
382
383         /*
384          * When we start a new trace, we set wakeup_task to NULL
385          * and then set tracer_enabled = 1. We want to make sure
386          * that another CPU does not see the tracer_enabled = 1
387          * and the wakeup_task with an older task, that might
388          * actually be the same as next.
389          */
390         smp_rmb();
391
392         if (next != wakeup_task)
393                 return;
394
395         pc = preempt_count();
396
397         /* disable local data, not wakeup_cpu data */
398         cpu = raw_smp_processor_id();
399         disabled = atomic_inc_return(&per_cpu_ptr(wakeup_trace->trace_buffer.data, cpu)->disabled);
400         if (likely(disabled != 1))
401                 goto out;
402
403         local_irq_save(flags);
404         arch_spin_lock(&wakeup_lock);
405
406         /* We could race with grabbing wakeup_lock */
407         if (unlikely(!tracer_enabled || next != wakeup_task))
408                 goto out_unlock;
409
410         /* The task we are waiting for is waking up */
411         data = per_cpu_ptr(wakeup_trace->trace_buffer.data, wakeup_cpu);
412
413         __trace_function(wakeup_trace, CALLER_ADDR0, CALLER_ADDR1, flags, pc);
414         tracing_sched_switch_trace(wakeup_trace, prev, next, flags, pc);
415
416         T0 = data->preempt_timestamp;
417         T1 = ftrace_now(cpu);
418         delta = T1-T0;
419
420         if (!report_latency(delta))
421                 goto out_unlock;
422
423         if (likely(!is_tracing_stopped())) {
424                 tracing_max_latency = delta;
425                 update_max_tr(wakeup_trace, wakeup_task, wakeup_cpu);
426         }
427
428 out_unlock:
429         __wakeup_reset(wakeup_trace);
430         arch_spin_unlock(&wakeup_lock);
431         local_irq_restore(flags);
432 out:
433         atomic_dec(&per_cpu_ptr(wakeup_trace->trace_buffer.data, cpu)->disabled);
434 }
435
436 static void __wakeup_reset(struct trace_array *tr)
437 {
438         wakeup_cpu = -1;
439         wakeup_prio = -1;
440
441         if (wakeup_task)
442                 put_task_struct(wakeup_task);
443
444         wakeup_task = NULL;
445 }
446
447 static void wakeup_reset(struct trace_array *tr)
448 {
449         unsigned long flags;
450
451         tracing_reset_online_cpus(&tr->trace_buffer);
452
453         local_irq_save(flags);
454         arch_spin_lock(&wakeup_lock);
455         __wakeup_reset(tr);
456         arch_spin_unlock(&wakeup_lock);
457         local_irq_restore(flags);
458 }
459
460 static void
461 probe_wakeup(void *ignore, struct task_struct *p, int success)
462 {
463         struct trace_array_cpu *data;
464         int cpu = smp_processor_id();
465         unsigned long flags;
466         long disabled;
467         int pc;
468
469         if (likely(!tracer_enabled))
470                 return;
471
472         tracing_record_cmdline(p);
473         tracing_record_cmdline(current);
474
475         if ((wakeup_rt && !rt_task(p)) ||
476                         p->prio >= wakeup_prio ||
477                         p->prio >= current->prio)
478                 return;
479
480         pc = preempt_count();
481         disabled = atomic_inc_return(&per_cpu_ptr(wakeup_trace->trace_buffer.data, cpu)->disabled);
482         if (unlikely(disabled != 1))
483                 goto out;
484
485         /* interrupts should be off from try_to_wake_up */
486         arch_spin_lock(&wakeup_lock);
487
488         /* check for races. */
489         if (!tracer_enabled || p->prio >= wakeup_prio)
490                 goto out_locked;
491
492         /* reset the trace */
493         __wakeup_reset(wakeup_trace);
494
495         wakeup_cpu = task_cpu(p);
496         wakeup_current_cpu = wakeup_cpu;
497         wakeup_prio = p->prio;
498
499         wakeup_task = p;
500         get_task_struct(wakeup_task);
501
502         local_save_flags(flags);
503
504         data = per_cpu_ptr(wakeup_trace->trace_buffer.data, wakeup_cpu);
505         data->preempt_timestamp = ftrace_now(cpu);
506         tracing_sched_wakeup_trace(wakeup_trace, p, current, flags, pc);
507
508         /*
509          * We must be careful in using CALLER_ADDR2. But since wake_up
510          * is not called by an assembly function  (where as schedule is)
511          * it should be safe to use it here.
512          */
513         __trace_function(wakeup_trace, CALLER_ADDR1, CALLER_ADDR2, flags, pc);
514
515 out_locked:
516         arch_spin_unlock(&wakeup_lock);
517 out:
518         atomic_dec(&per_cpu_ptr(wakeup_trace->trace_buffer.data, cpu)->disabled);
519 }
520
521 static void start_wakeup_tracer(struct trace_array *tr)
522 {
523         int ret;
524
525         ret = register_trace_sched_wakeup(probe_wakeup, NULL);
526         if (ret) {
527                 pr_info("wakeup trace: Couldn't activate tracepoint"
528                         " probe to kernel_sched_wakeup\n");
529                 return;
530         }
531
532         ret = register_trace_sched_wakeup_new(probe_wakeup, NULL);
533         if (ret) {
534                 pr_info("wakeup trace: Couldn't activate tracepoint"
535                         " probe to kernel_sched_wakeup_new\n");
536                 goto fail_deprobe;
537         }
538
539         ret = register_trace_sched_switch(probe_wakeup_sched_switch, NULL);
540         if (ret) {
541                 pr_info("sched trace: Couldn't activate tracepoint"
542                         " probe to kernel_sched_switch\n");
543                 goto fail_deprobe_wake_new;
544         }
545
546         ret = register_trace_sched_migrate_task(probe_wakeup_migrate_task, NULL);
547         if (ret) {
548                 pr_info("wakeup trace: Couldn't activate tracepoint"
549                         " probe to kernel_sched_migrate_task\n");
550                 return;
551         }
552
553         wakeup_reset(tr);
554
555         /*
556          * Don't let the tracer_enabled = 1 show up before
557          * the wakeup_task is reset. This may be overkill since
558          * wakeup_reset does a spin_unlock after setting the
559          * wakeup_task to NULL, but I want to be safe.
560          * This is a slow path anyway.
561          */
562         smp_wmb();
563
564         if (start_func_tracer(is_graph()))
565                 printk(KERN_ERR "failed to start wakeup tracer\n");
566
567         return;
568 fail_deprobe_wake_new:
569         unregister_trace_sched_wakeup_new(probe_wakeup, NULL);
570 fail_deprobe:
571         unregister_trace_sched_wakeup(probe_wakeup, NULL);
572 }
573
574 static void stop_wakeup_tracer(struct trace_array *tr)
575 {
576         tracer_enabled = 0;
577         stop_func_tracer(is_graph());
578         unregister_trace_sched_switch(probe_wakeup_sched_switch, NULL);
579         unregister_trace_sched_wakeup_new(probe_wakeup, NULL);
580         unregister_trace_sched_wakeup(probe_wakeup, NULL);
581         unregister_trace_sched_migrate_task(probe_wakeup_migrate_task, NULL);
582 }
583
584 static int __wakeup_tracer_init(struct trace_array *tr)
585 {
586         save_flags = trace_flags;
587
588         /* non overwrite screws up the latency tracers */
589         set_tracer_flag(tr, TRACE_ITER_OVERWRITE, 1);
590         set_tracer_flag(tr, TRACE_ITER_LATENCY_FMT, 1);
591
592         tracing_max_latency = 0;
593         wakeup_trace = tr;
594         start_wakeup_tracer(tr);
595         return 0;
596 }
597
598 static int wakeup_tracer_init(struct trace_array *tr)
599 {
600         wakeup_rt = 0;
601         return __wakeup_tracer_init(tr);
602 }
603
604 static int wakeup_rt_tracer_init(struct trace_array *tr)
605 {
606         wakeup_rt = 1;
607         return __wakeup_tracer_init(tr);
608 }
609
610 static void wakeup_tracer_reset(struct trace_array *tr)
611 {
612         int lat_flag = save_flags & TRACE_ITER_LATENCY_FMT;
613         int overwrite_flag = save_flags & TRACE_ITER_OVERWRITE;
614
615         stop_wakeup_tracer(tr);
616         /* make sure we put back any tasks we are tracing */
617         wakeup_reset(tr);
618
619         set_tracer_flag(tr, TRACE_ITER_LATENCY_FMT, lat_flag);
620         set_tracer_flag(tr, TRACE_ITER_OVERWRITE, overwrite_flag);
621 }
622
623 static void wakeup_tracer_start(struct trace_array *tr)
624 {
625         wakeup_reset(tr);
626         tracer_enabled = 1;
627 }
628
629 static void wakeup_tracer_stop(struct trace_array *tr)
630 {
631         tracer_enabled = 0;
632 }
633
634 static struct tracer wakeup_tracer __read_mostly =
635 {
636         .name           = "wakeup",
637         .init           = wakeup_tracer_init,
638         .reset          = wakeup_tracer_reset,
639         .start          = wakeup_tracer_start,
640         .stop           = wakeup_tracer_stop,
641         .print_max      = true,
642         .print_header   = wakeup_print_header,
643         .print_line     = wakeup_print_line,
644         .flags          = &tracer_flags,
645         .set_flag       = wakeup_set_flag,
646         .flag_changed   = wakeup_flag_changed,
647 #ifdef CONFIG_FTRACE_SELFTEST
648         .selftest    = trace_selftest_startup_wakeup,
649 #endif
650         .open           = wakeup_trace_open,
651         .close          = wakeup_trace_close,
652         .use_max_tr     = true,
653 };
654
655 static struct tracer wakeup_rt_tracer __read_mostly =
656 {
657         .name           = "wakeup_rt",
658         .init           = wakeup_rt_tracer_init,
659         .reset          = wakeup_tracer_reset,
660         .start          = wakeup_tracer_start,
661         .stop           = wakeup_tracer_stop,
662         .wait_pipe      = poll_wait_pipe,
663         .print_max      = true,
664         .print_header   = wakeup_print_header,
665         .print_line     = wakeup_print_line,
666         .flags          = &tracer_flags,
667         .set_flag       = wakeup_set_flag,
668         .flag_changed   = wakeup_flag_changed,
669 #ifdef CONFIG_FTRACE_SELFTEST
670         .selftest    = trace_selftest_startup_wakeup,
671 #endif
672         .open           = wakeup_trace_open,
673         .close          = wakeup_trace_close,
674         .use_max_tr     = true,
675 };
676
677 __init static int init_wakeup_tracer(void)
678 {
679         int ret;
680
681         ret = register_tracer(&wakeup_tracer);
682         if (ret)
683                 return ret;
684
685         ret = register_tracer(&wakeup_rt_tracer);
686         if (ret)
687                 return ret;
688
689         return 0;
690 }
691 core_initcall(init_wakeup_tracer);