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1/*
2 * trace irqs off critical timings
3 *
4 * Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com>
5 * Copyright (C) 2008 Ingo Molnar <mingo@redhat.com>
6 *
7 * From code in the latency_tracer, that is:
8 *
9 * Copyright (C) 2004-2006 Ingo Molnar
10 * Copyright (C) 2004 Nadia Yvette Chambers
11 */
12#include <linux/kallsyms.h>
13#include <linux/uaccess.h>
14#include <linux/module.h>
15#include <linux/ftrace.h>
16
17#include "trace.h"
18
19static struct trace_array *irqsoff_trace __read_mostly;
20static int tracer_enabled __read_mostly;
21
22static DEFINE_PER_CPU(int, tracing_cpu);
23
24static DEFINE_RAW_SPINLOCK(max_trace_lock);
25
26enum {
27 TRACER_IRQS_OFF = (1 << 1),
28 TRACER_PREEMPT_OFF = (1 << 2),
29};
30
31static int trace_type __read_mostly;
32
33static int save_flags;
34
35static void stop_irqsoff_tracer(struct trace_array *tr, int graph);
36static int start_irqsoff_tracer(struct trace_array *tr, int graph);
37
38#ifdef CONFIG_PREEMPT_TRACER
39static inline int
40preempt_trace(void)
41{
42 return ((trace_type & TRACER_PREEMPT_OFF) && preempt_count());
43}
44#else
45# define preempt_trace() (0)
46#endif
47
48#ifdef CONFIG_IRQSOFF_TRACER
49static inline int
50irq_trace(void)
51{
52 return ((trace_type & TRACER_IRQS_OFF) &&
53 irqs_disabled());
54}
55#else
56# define irq_trace() (0)
57#endif
58
59#ifdef CONFIG_FUNCTION_GRAPH_TRACER
60static int irqsoff_display_graph(struct trace_array *tr, int set);
61# define is_graph(tr) ((tr)->trace_flags & TRACE_ITER_DISPLAY_GRAPH)
62#else
63static inline int irqsoff_display_graph(struct trace_array *tr, int set)
64{
65 return -EINVAL;
66}
67# define is_graph(tr) false
68#endif
69
70/*
71 * Sequence count - we record it when starting a measurement and
72 * skip the latency if the sequence has changed - some other section
73 * did a maximum and could disturb our measurement with serial console
74 * printouts, etc. Truly coinciding maximum latencies should be rare
75 * and what happens together happens separately as well, so this doesn't
76 * decrease the validity of the maximum found:
77 */
78static __cacheline_aligned_in_smp unsigned long max_sequence;
79
80#ifdef CONFIG_FUNCTION_TRACER
81/*
82 * Prologue for the preempt and irqs off function tracers.
83 *
84 * Returns 1 if it is OK to continue, and data->disabled is
85 * incremented.
86 * 0 if the trace is to be ignored, and data->disabled
87 * is kept the same.
88 *
89 * Note, this function is also used outside this ifdef but
90 * inside the #ifdef of the function graph tracer below.
91 * This is OK, since the function graph tracer is
92 * dependent on the function tracer.
93 */
94static int func_prolog_dec(struct trace_array *tr,
95 struct trace_array_cpu **data,
96 unsigned long *flags)
97{
98 long disabled;
99 int cpu;
100
101 /*
102 * Does not matter if we preempt. We test the flags
103 * afterward, to see if irqs are disabled or not.
104 * If we preempt and get a false positive, the flags
105 * test will fail.
106 */
107 cpu = raw_smp_processor_id();
108 if (likely(!per_cpu(tracing_cpu, cpu)))
109 return 0;
110
111 local_save_flags(*flags);
112 /*
113 * Slight chance to get a false positive on tracing_cpu,
114 * although I'm starting to think there isn't a chance.
115 * Leave this for now just to be paranoid.
116 */
117 if (!irqs_disabled_flags(*flags) && !preempt_count())
118 return 0;
119
120 *data = per_cpu_ptr(tr->trace_buffer.data, cpu);
121 disabled = atomic_inc_return(&(*data)->disabled);
122
123 if (likely(disabled == 1))
124 return 1;
125
126 atomic_dec(&(*data)->disabled);
127
128 return 0;
129}
130
131/*
132 * irqsoff uses its own tracer function to keep the overhead down:
133 */
134static void
135irqsoff_tracer_call(unsigned long ip, unsigned long parent_ip,
136 struct ftrace_ops *op, struct pt_regs *pt_regs)
137{
138 struct trace_array *tr = irqsoff_trace;
139 struct trace_array_cpu *data;
140 unsigned long flags;
141
142 if (!func_prolog_dec(tr, &data, &flags))
143 return;
144
145 trace_function(tr, ip, parent_ip, flags, preempt_count());
146
147 atomic_dec(&data->disabled);
148}
149#endif /* CONFIG_FUNCTION_TRACER */
150
151#ifdef CONFIG_FUNCTION_GRAPH_TRACER
152static int irqsoff_display_graph(struct trace_array *tr, int set)
153{
154 int cpu;
155
156 if (!(is_graph(tr) ^ set))
157 return 0;
158
159 stop_irqsoff_tracer(irqsoff_trace, !set);
160
161 for_each_possible_cpu(cpu)
162 per_cpu(tracing_cpu, cpu) = 0;
163
164 tr->max_latency = 0;
165 tracing_reset_online_cpus(&irqsoff_trace->trace_buffer);
166
167 return start_irqsoff_tracer(irqsoff_trace, set);
168}
169
170static int irqsoff_graph_entry(struct ftrace_graph_ent *trace)
171{
172 struct trace_array *tr = irqsoff_trace;
173 struct trace_array_cpu *data;
174 unsigned long flags;
175 int ret;
176 int pc;
177
178 if (!func_prolog_dec(tr, &data, &flags))
179 return 0;
180
181 pc = preempt_count();
182 ret = __trace_graph_entry(tr, trace, flags, pc);
183 atomic_dec(&data->disabled);
184
185 return ret;
186}
187
188static void irqsoff_graph_return(struct ftrace_graph_ret *trace)
189{
190 struct trace_array *tr = irqsoff_trace;
191 struct trace_array_cpu *data;
192 unsigned long flags;
193 int pc;
194
195 if (!func_prolog_dec(tr, &data, &flags))
196 return;
197
198 pc = preempt_count();
199 __trace_graph_return(tr, trace, flags, pc);
200 atomic_dec(&data->disabled);
201}
202
203static void irqsoff_trace_open(struct trace_iterator *iter)
204{
205 if (is_graph(iter->tr))
206 graph_trace_open(iter);
207
208}
209
210static void irqsoff_trace_close(struct trace_iterator *iter)
211{
212 if (iter->private)
213 graph_trace_close(iter);
214}
215
216#define GRAPH_TRACER_FLAGS (TRACE_GRAPH_PRINT_CPU | \
217 TRACE_GRAPH_PRINT_PROC | \
218 TRACE_GRAPH_PRINT_ABS_TIME | \
219 TRACE_GRAPH_PRINT_DURATION)
220
221static enum print_line_t irqsoff_print_line(struct trace_iterator *iter)
222{
223 /*
224 * In graph mode call the graph tracer output function,
225 * otherwise go with the TRACE_FN event handler
226 */
227 if (is_graph(iter->tr))
228 return print_graph_function_flags(iter, GRAPH_TRACER_FLAGS);
229
230 return TRACE_TYPE_UNHANDLED;
231}
232
233static void irqsoff_print_header(struct seq_file *s)
234{
235 struct trace_array *tr = irqsoff_trace;
236
237 if (is_graph(tr))
238 print_graph_headers_flags(s, GRAPH_TRACER_FLAGS);
239 else
240 trace_default_header(s);
241}
242
243static void
244__trace_function(struct trace_array *tr,
245 unsigned long ip, unsigned long parent_ip,
246 unsigned long flags, int pc)
247{
248 if (is_graph(tr))
249 trace_graph_function(tr, ip, parent_ip, flags, pc);
250 else
251 trace_function(tr, ip, parent_ip, flags, pc);
252}
253
254#else
255#define __trace_function trace_function
256
257#ifdef CONFIG_FUNCTION_TRACER
258static int irqsoff_graph_entry(struct ftrace_graph_ent *trace)
259{
260 return -1;
261}
262#endif
263
264static enum print_line_t irqsoff_print_line(struct trace_iterator *iter)
265{
266 return TRACE_TYPE_UNHANDLED;
267}
268
269static void irqsoff_trace_open(struct trace_iterator *iter) { }
270static void irqsoff_trace_close(struct trace_iterator *iter) { }
271
272#ifdef CONFIG_FUNCTION_TRACER
273static void irqsoff_graph_return(struct ftrace_graph_ret *trace) { }
274static void irqsoff_print_header(struct seq_file *s)
275{
276 trace_default_header(s);
277}
278#else
279static void irqsoff_print_header(struct seq_file *s)
280{
281 trace_latency_header(s);
282}
283#endif /* CONFIG_FUNCTION_TRACER */
284#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
285
286/*
287 * Should this new latency be reported/recorded?
288 */
289static bool report_latency(struct trace_array *tr, cycle_t delta)
290{
291 if (tracing_thresh) {
292 if (delta < tracing_thresh)
293 return false;
294 } else {
295 if (delta <= tr->max_latency)
296 return false;
297 }
298 return true;
299}
300
301static void
302check_critical_timing(struct trace_array *tr,
303 struct trace_array_cpu *data,
304 unsigned long parent_ip,
305 int cpu)
306{
307 cycle_t T0, T1, delta;
308 unsigned long flags;
309 int pc;
310
311 T0 = data->preempt_timestamp;
312 T1 = ftrace_now(cpu);
313 delta = T1-T0;
314
315 local_save_flags(flags);
316
317 pc = preempt_count();
318
319 if (!report_latency(tr, delta))
320 goto out;
321
322 raw_spin_lock_irqsave(&max_trace_lock, flags);
323
324 /* check if we are still the max latency */
325 if (!report_latency(tr, delta))
326 goto out_unlock;
327
328 __trace_function(tr, CALLER_ADDR0, parent_ip, flags, pc);
329 /* Skip 5 functions to get to the irq/preempt enable function */
330 __trace_stack(tr, flags, 5, pc);
331
332 if (data->critical_sequence != max_sequence)
333 goto out_unlock;
334
335 data->critical_end = parent_ip;
336
337 if (likely(!is_tracing_stopped())) {
338 tr->max_latency = delta;
339 update_max_tr_single(tr, current, cpu);
340 }
341
342 max_sequence++;
343
344out_unlock:
345 raw_spin_unlock_irqrestore(&max_trace_lock, flags);
346
347out:
348 data->critical_sequence = max_sequence;
349 data->preempt_timestamp = ftrace_now(cpu);
350 __trace_function(tr, CALLER_ADDR0, parent_ip, flags, pc);
351}
352
353static inline void
354start_critical_timing(unsigned long ip, unsigned long parent_ip)
355{
356 int cpu;
357 struct trace_array *tr = irqsoff_trace;
358 struct trace_array_cpu *data;
359 unsigned long flags;
360
361 if (!tracer_enabled || !tracing_is_enabled())
362 return;
363
364 cpu = raw_smp_processor_id();
365
366 if (per_cpu(tracing_cpu, cpu))
367 return;
368
369 data = per_cpu_ptr(tr->trace_buffer.data, cpu);
370
371 if (unlikely(!data) || atomic_read(&data->disabled))
372 return;
373
374 atomic_inc(&data->disabled);
375
376 data->critical_sequence = max_sequence;
377 data->preempt_timestamp = ftrace_now(cpu);
378 data->critical_start = parent_ip ? : ip;
379
380 local_save_flags(flags);
381
382 __trace_function(tr, ip, parent_ip, flags, preempt_count());
383
384 per_cpu(tracing_cpu, cpu) = 1;
385
386 atomic_dec(&data->disabled);
387}
388
389static inline void
390stop_critical_timing(unsigned long ip, unsigned long parent_ip)
391{
392 int cpu;
393 struct trace_array *tr = irqsoff_trace;
394 struct trace_array_cpu *data;
395 unsigned long flags;
396
397 cpu = raw_smp_processor_id();
398 /* Always clear the tracing cpu on stopping the trace */
399 if (unlikely(per_cpu(tracing_cpu, cpu)))
400 per_cpu(tracing_cpu, cpu) = 0;
401 else
402 return;
403
404 if (!tracer_enabled || !tracing_is_enabled())
405 return;
406
407 data = per_cpu_ptr(tr->trace_buffer.data, cpu);
408
409 if (unlikely(!data) ||
410 !data->critical_start || atomic_read(&data->disabled))
411 return;
412
413 atomic_inc(&data->disabled);
414
415 local_save_flags(flags);
416 __trace_function(tr, ip, parent_ip, flags, preempt_count());
417 check_critical_timing(tr, data, parent_ip ? : ip, cpu);
418 data->critical_start = 0;
419 atomic_dec(&data->disabled);
420}
421
422/* start and stop critical timings used to for stoppage (in idle) */
423void start_critical_timings(void)
424{
425 if (preempt_trace() || irq_trace())
426 start_critical_timing(CALLER_ADDR0, CALLER_ADDR1);
427}
428EXPORT_SYMBOL_GPL(start_critical_timings);
429
430void stop_critical_timings(void)
431{
432 if (preempt_trace() || irq_trace())
433 stop_critical_timing(CALLER_ADDR0, CALLER_ADDR1);
434}
435EXPORT_SYMBOL_GPL(stop_critical_timings);
436
437#ifdef CONFIG_IRQSOFF_TRACER
438#ifdef CONFIG_PROVE_LOCKING
439void time_hardirqs_on(unsigned long a0, unsigned long a1)
440{
441 if (!preempt_trace() && irq_trace())
442 stop_critical_timing(a0, a1);
443}
444
445void time_hardirqs_off(unsigned long a0, unsigned long a1)
446{
447 if (!preempt_trace() && irq_trace())
448 start_critical_timing(a0, a1);
449}
450
451#else /* !CONFIG_PROVE_LOCKING */
452
453/*
454 * Stubs:
455 */
456
457void trace_softirqs_on(unsigned long ip)
458{
459}
460
461void trace_softirqs_off(unsigned long ip)
462{
463}
464
465inline void print_irqtrace_events(struct task_struct *curr)
466{
467}
468
469/*
470 * We are only interested in hardirq on/off events:
471 */
472void trace_hardirqs_on(void)
473{
474 if (!preempt_trace() && irq_trace())
475 stop_critical_timing(CALLER_ADDR0, CALLER_ADDR1);
476}
477EXPORT_SYMBOL(trace_hardirqs_on);
478
479void trace_hardirqs_off(void)
480{
481 if (!preempt_trace() && irq_trace())
482 start_critical_timing(CALLER_ADDR0, CALLER_ADDR1);
483}
484EXPORT_SYMBOL(trace_hardirqs_off);
485
486__visible void trace_hardirqs_on_caller(unsigned long caller_addr)
487{
488 if (!preempt_trace() && irq_trace())
489 stop_critical_timing(CALLER_ADDR0, caller_addr);
490}
491EXPORT_SYMBOL(trace_hardirqs_on_caller);
492
493__visible void trace_hardirqs_off_caller(unsigned long caller_addr)
494{
495 if (!preempt_trace() && irq_trace())
496 start_critical_timing(CALLER_ADDR0, caller_addr);
497}
498EXPORT_SYMBOL(trace_hardirqs_off_caller);
499
500#endif /* CONFIG_PROVE_LOCKING */
501#endif /* CONFIG_IRQSOFF_TRACER */
502
503#ifdef CONFIG_PREEMPT_TRACER
504void trace_preempt_on(unsigned long a0, unsigned long a1)
505{
506 if (preempt_trace() && !irq_trace())
507 stop_critical_timing(a0, a1);
508}
509
510void trace_preempt_off(unsigned long a0, unsigned long a1)
511{
512 if (preempt_trace() && !irq_trace())
513 start_critical_timing(a0, a1);
514}
515#endif /* CONFIG_PREEMPT_TRACER */
516
517#ifdef CONFIG_FUNCTION_TRACER
518static bool function_enabled;
519
520static int register_irqsoff_function(struct trace_array *tr, int graph, int set)
521{
522 int ret;
523
524 /* 'set' is set if TRACE_ITER_FUNCTION is about to be set */
525 if (function_enabled || (!set && !(tr->trace_flags & TRACE_ITER_FUNCTION)))
526 return 0;
527
528 if (graph)
529 ret = register_ftrace_graph(&irqsoff_graph_return,
530 &irqsoff_graph_entry);
531 else
532 ret = register_ftrace_function(tr->ops);
533
534 if (!ret)
535 function_enabled = true;
536
537 return ret;
538}
539
540static void unregister_irqsoff_function(struct trace_array *tr, int graph)
541{
542 if (!function_enabled)
543 return;
544
545 if (graph)
546 unregister_ftrace_graph();
547 else
548 unregister_ftrace_function(tr->ops);
549
550 function_enabled = false;
551}
552
553static int irqsoff_function_set(struct trace_array *tr, u32 mask, int set)
554{
555 if (!(mask & TRACE_ITER_FUNCTION))
556 return 0;
557
558 if (set)
559 register_irqsoff_function(tr, is_graph(tr), 1);
560 else
561 unregister_irqsoff_function(tr, is_graph(tr));
562 return 1;
563}
564#else
565static int register_irqsoff_function(struct trace_array *tr, int graph, int set)
566{
567 return 0;
568}
569static void unregister_irqsoff_function(struct trace_array *tr, int graph) { }
570static inline int irqsoff_function_set(struct trace_array *tr, u32 mask, int set)
571{
572 return 0;
573}
574#endif /* CONFIG_FUNCTION_TRACER */
575
576static int irqsoff_flag_changed(struct trace_array *tr, u32 mask, int set)
577{
578 struct tracer *tracer = tr->current_trace;
579
580 if (irqsoff_function_set(tr, mask, set))
581 return 0;
582
583#ifdef CONFIG_FUNCTION_GRAPH_TRACER
584 if (mask & TRACE_ITER_DISPLAY_GRAPH)
585 return irqsoff_display_graph(tr, set);
586#endif
587
588 return trace_keep_overwrite(tracer, mask, set);
589}
590
591static int start_irqsoff_tracer(struct trace_array *tr, int graph)
592{
593 int ret;
594
595 ret = register_irqsoff_function(tr, graph, 0);
596
597 if (!ret && tracing_is_enabled())
598 tracer_enabled = 1;
599 else
600 tracer_enabled = 0;
601
602 return ret;
603}
604
605static void stop_irqsoff_tracer(struct trace_array *tr, int graph)
606{
607 tracer_enabled = 0;
608
609 unregister_irqsoff_function(tr, graph);
610}
611
612static bool irqsoff_busy;
613
614static int __irqsoff_tracer_init(struct trace_array *tr)
615{
616 if (irqsoff_busy)
617 return -EBUSY;
618
619 save_flags = tr->trace_flags;
620
621 /* non overwrite screws up the latency tracers */
622 set_tracer_flag(tr, TRACE_ITER_OVERWRITE, 1);
623 set_tracer_flag(tr, TRACE_ITER_LATENCY_FMT, 1);
624
625 tr->max_latency = 0;
626 irqsoff_trace = tr;
627 /* make sure that the tracer is visible */
628 smp_wmb();
629
630 ftrace_init_array_ops(tr, irqsoff_tracer_call);
631
632 /* Only toplevel instance supports graph tracing */
633 if (start_irqsoff_tracer(tr, (tr->flags & TRACE_ARRAY_FL_GLOBAL &&
634 is_graph(tr))))
635 printk(KERN_ERR "failed to start irqsoff tracer\n");
636
637 irqsoff_busy = true;
638 return 0;
639}
640
641static void irqsoff_tracer_reset(struct trace_array *tr)
642{
643 int lat_flag = save_flags & TRACE_ITER_LATENCY_FMT;
644 int overwrite_flag = save_flags & TRACE_ITER_OVERWRITE;
645
646 stop_irqsoff_tracer(tr, is_graph(tr));
647
648 set_tracer_flag(tr, TRACE_ITER_LATENCY_FMT, lat_flag);
649 set_tracer_flag(tr, TRACE_ITER_OVERWRITE, overwrite_flag);
650 ftrace_reset_array_ops(tr);
651
652 irqsoff_busy = false;
653}
654
655static void irqsoff_tracer_start(struct trace_array *tr)
656{
657 tracer_enabled = 1;
658}
659
660static void irqsoff_tracer_stop(struct trace_array *tr)
661{
662 tracer_enabled = 0;
663}
664
665#ifdef CONFIG_IRQSOFF_TRACER
666static int irqsoff_tracer_init(struct trace_array *tr)
667{
668 trace_type = TRACER_IRQS_OFF;
669
670 return __irqsoff_tracer_init(tr);
671}
672static struct tracer irqsoff_tracer __read_mostly =
673{
674 .name = "irqsoff",
675 .init = irqsoff_tracer_init,
676 .reset = irqsoff_tracer_reset,
677 .start = irqsoff_tracer_start,
678 .stop = irqsoff_tracer_stop,
679 .print_max = true,
680 .print_header = irqsoff_print_header,
681 .print_line = irqsoff_print_line,
682 .flag_changed = irqsoff_flag_changed,
683#ifdef CONFIG_FTRACE_SELFTEST
684 .selftest = trace_selftest_startup_irqsoff,
685#endif
686 .open = irqsoff_trace_open,
687 .close = irqsoff_trace_close,
688 .allow_instances = true,
689 .use_max_tr = true,
690};
691# define register_irqsoff(trace) register_tracer(&trace)
692#else
693# define register_irqsoff(trace) do { } while (0)
694#endif
695
696#ifdef CONFIG_PREEMPT_TRACER
697static int preemptoff_tracer_init(struct trace_array *tr)
698{
699 trace_type = TRACER_PREEMPT_OFF;
700
701 return __irqsoff_tracer_init(tr);
702}
703
704static struct tracer preemptoff_tracer __read_mostly =
705{
706 .name = "preemptoff",
707 .init = preemptoff_tracer_init,
708 .reset = irqsoff_tracer_reset,
709 .start = irqsoff_tracer_start,
710 .stop = irqsoff_tracer_stop,
711 .print_max = true,
712 .print_header = irqsoff_print_header,
713 .print_line = irqsoff_print_line,
714 .flag_changed = irqsoff_flag_changed,
715#ifdef CONFIG_FTRACE_SELFTEST
716 .selftest = trace_selftest_startup_preemptoff,
717#endif
718 .open = irqsoff_trace_open,
719 .close = irqsoff_trace_close,
720 .allow_instances = true,
721 .use_max_tr = true,
722};
723# define register_preemptoff(trace) register_tracer(&trace)
724#else
725# define register_preemptoff(trace) do { } while (0)
726#endif
727
728#if defined(CONFIG_IRQSOFF_TRACER) && \
729 defined(CONFIG_PREEMPT_TRACER)
730
731static int preemptirqsoff_tracer_init(struct trace_array *tr)
732{
733 trace_type = TRACER_IRQS_OFF | TRACER_PREEMPT_OFF;
734
735 return __irqsoff_tracer_init(tr);
736}
737
738static struct tracer preemptirqsoff_tracer __read_mostly =
739{
740 .name = "preemptirqsoff",
741 .init = preemptirqsoff_tracer_init,
742 .reset = irqsoff_tracer_reset,
743 .start = irqsoff_tracer_start,
744 .stop = irqsoff_tracer_stop,
745 .print_max = true,
746 .print_header = irqsoff_print_header,
747 .print_line = irqsoff_print_line,
748 .flag_changed = irqsoff_flag_changed,
749#ifdef CONFIG_FTRACE_SELFTEST
750 .selftest = trace_selftest_startup_preemptirqsoff,
751#endif
752 .open = irqsoff_trace_open,
753 .close = irqsoff_trace_close,
754 .allow_instances = true,
755 .use_max_tr = true,
756};
757
758# define register_preemptirqsoff(trace) register_tracer(&trace)
759#else
760# define register_preemptirqsoff(trace) do { } while (0)
761#endif
762
763__init static int init_irqsoff_tracer(void)
764{
765 register_irqsoff(irqsoff_tracer);
766 register_preemptoff(preemptoff_tracer);
767 register_preemptirqsoff(preemptirqsoff_tracer);
768
769 return 0;
770}
771core_initcall(init_irqsoff_tracer);
1/*
2 * trace irqs off critical timings
3 *
4 * Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com>
5 * Copyright (C) 2008 Ingo Molnar <mingo@redhat.com>
6 *
7 * From code in 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/kallsyms.h>
13#include <linux/debugfs.h>
14#include <linux/uaccess.h>
15#include <linux/module.h>
16#include <linux/ftrace.h>
17#include <linux/fs.h>
18
19#include "trace.h"
20
21static struct trace_array *irqsoff_trace __read_mostly;
22static int tracer_enabled __read_mostly;
23
24static DEFINE_PER_CPU(int, tracing_cpu);
25
26static DEFINE_RAW_SPINLOCK(max_trace_lock);
27
28enum {
29 TRACER_IRQS_OFF = (1 << 1),
30 TRACER_PREEMPT_OFF = (1 << 2),
31};
32
33static int trace_type __read_mostly;
34
35static int save_lat_flag;
36
37static void stop_irqsoff_tracer(struct trace_array *tr, int graph);
38static int start_irqsoff_tracer(struct trace_array *tr, int graph);
39
40#ifdef CONFIG_PREEMPT_TRACER
41static inline int
42preempt_trace(void)
43{
44 return ((trace_type & TRACER_PREEMPT_OFF) && preempt_count());
45}
46#else
47# define preempt_trace() (0)
48#endif
49
50#ifdef CONFIG_IRQSOFF_TRACER
51static inline int
52irq_trace(void)
53{
54 return ((trace_type & TRACER_IRQS_OFF) &&
55 irqs_disabled());
56}
57#else
58# define irq_trace() (0)
59#endif
60
61#define TRACE_DISPLAY_GRAPH 1
62
63static struct tracer_opt trace_opts[] = {
64#ifdef CONFIG_FUNCTION_GRAPH_TRACER
65 /* display latency trace as call graph */
66 { TRACER_OPT(display-graph, TRACE_DISPLAY_GRAPH) },
67#endif
68 { } /* Empty entry */
69};
70
71static struct tracer_flags tracer_flags = {
72 .val = 0,
73 .opts = trace_opts,
74};
75
76#define is_graph() (tracer_flags.val & TRACE_DISPLAY_GRAPH)
77
78/*
79 * Sequence count - we record it when starting a measurement and
80 * skip the latency if the sequence has changed - some other section
81 * did a maximum and could disturb our measurement with serial console
82 * printouts, etc. Truly coinciding maximum latencies should be rare
83 * and what happens together happens separately as well, so this doesn't
84 * decrease the validity of the maximum found:
85 */
86static __cacheline_aligned_in_smp unsigned long max_sequence;
87
88#ifdef CONFIG_FUNCTION_TRACER
89/*
90 * Prologue for the preempt and irqs off function tracers.
91 *
92 * Returns 1 if it is OK to continue, and data->disabled is
93 * incremented.
94 * 0 if the trace is to be ignored, and data->disabled
95 * is kept the same.
96 *
97 * Note, this function is also used outside this ifdef but
98 * inside the #ifdef of the function graph tracer below.
99 * This is OK, since the function graph tracer is
100 * dependent on the function tracer.
101 */
102static int func_prolog_dec(struct trace_array *tr,
103 struct trace_array_cpu **data,
104 unsigned long *flags)
105{
106 long disabled;
107 int cpu;
108
109 /*
110 * Does not matter if we preempt. We test the flags
111 * afterward, to see if irqs are disabled or not.
112 * If we preempt and get a false positive, the flags
113 * test will fail.
114 */
115 cpu = raw_smp_processor_id();
116 if (likely(!per_cpu(tracing_cpu, cpu)))
117 return 0;
118
119 local_save_flags(*flags);
120 /* slight chance to get a false positive on tracing_cpu */
121 if (!irqs_disabled_flags(*flags))
122 return 0;
123
124 *data = tr->data[cpu];
125 disabled = atomic_inc_return(&(*data)->disabled);
126
127 if (likely(disabled == 1))
128 return 1;
129
130 atomic_dec(&(*data)->disabled);
131
132 return 0;
133}
134
135/*
136 * irqsoff uses its own tracer function to keep the overhead down:
137 */
138static void
139irqsoff_tracer_call(unsigned long ip, unsigned long parent_ip)
140{
141 struct trace_array *tr = irqsoff_trace;
142 struct trace_array_cpu *data;
143 unsigned long flags;
144
145 if (!func_prolog_dec(tr, &data, &flags))
146 return;
147
148 trace_function(tr, ip, parent_ip, flags, preempt_count());
149
150 atomic_dec(&data->disabled);
151}
152
153static struct ftrace_ops trace_ops __read_mostly =
154{
155 .func = irqsoff_tracer_call,
156 .flags = FTRACE_OPS_FL_GLOBAL,
157};
158#endif /* CONFIG_FUNCTION_TRACER */
159
160#ifdef CONFIG_FUNCTION_GRAPH_TRACER
161static int irqsoff_set_flag(u32 old_flags, u32 bit, int set)
162{
163 int cpu;
164
165 if (!(bit & TRACE_DISPLAY_GRAPH))
166 return -EINVAL;
167
168 if (!(is_graph() ^ set))
169 return 0;
170
171 stop_irqsoff_tracer(irqsoff_trace, !set);
172
173 for_each_possible_cpu(cpu)
174 per_cpu(tracing_cpu, cpu) = 0;
175
176 tracing_max_latency = 0;
177 tracing_reset_online_cpus(irqsoff_trace);
178
179 return start_irqsoff_tracer(irqsoff_trace, set);
180}
181
182static int irqsoff_graph_entry(struct ftrace_graph_ent *trace)
183{
184 struct trace_array *tr = irqsoff_trace;
185 struct trace_array_cpu *data;
186 unsigned long flags;
187 int ret;
188 int pc;
189
190 if (!func_prolog_dec(tr, &data, &flags))
191 return 0;
192
193 pc = preempt_count();
194 ret = __trace_graph_entry(tr, trace, flags, pc);
195 atomic_dec(&data->disabled);
196
197 return ret;
198}
199
200static void irqsoff_graph_return(struct ftrace_graph_ret *trace)
201{
202 struct trace_array *tr = irqsoff_trace;
203 struct trace_array_cpu *data;
204 unsigned long flags;
205 int pc;
206
207 if (!func_prolog_dec(tr, &data, &flags))
208 return;
209
210 pc = preempt_count();
211 __trace_graph_return(tr, trace, flags, pc);
212 atomic_dec(&data->disabled);
213}
214
215static void irqsoff_trace_open(struct trace_iterator *iter)
216{
217 if (is_graph())
218 graph_trace_open(iter);
219
220}
221
222static void irqsoff_trace_close(struct trace_iterator *iter)
223{
224 if (iter->private)
225 graph_trace_close(iter);
226}
227
228#define GRAPH_TRACER_FLAGS (TRACE_GRAPH_PRINT_CPU | \
229 TRACE_GRAPH_PRINT_PROC | \
230 TRACE_GRAPH_PRINT_ABS_TIME | \
231 TRACE_GRAPH_PRINT_DURATION)
232
233static enum print_line_t irqsoff_print_line(struct trace_iterator *iter)
234{
235 /*
236 * In graph mode call the graph tracer output function,
237 * otherwise go with the TRACE_FN event handler
238 */
239 if (is_graph())
240 return print_graph_function_flags(iter, GRAPH_TRACER_FLAGS);
241
242 return TRACE_TYPE_UNHANDLED;
243}
244
245static void irqsoff_print_header(struct seq_file *s)
246{
247 if (is_graph())
248 print_graph_headers_flags(s, GRAPH_TRACER_FLAGS);
249 else
250 trace_default_header(s);
251}
252
253static void
254__trace_function(struct trace_array *tr,
255 unsigned long ip, unsigned long parent_ip,
256 unsigned long flags, int pc)
257{
258 if (is_graph())
259 trace_graph_function(tr, ip, parent_ip, flags, pc);
260 else
261 trace_function(tr, ip, parent_ip, flags, pc);
262}
263
264#else
265#define __trace_function trace_function
266
267static int irqsoff_set_flag(u32 old_flags, u32 bit, int set)
268{
269 return -EINVAL;
270}
271
272static int irqsoff_graph_entry(struct ftrace_graph_ent *trace)
273{
274 return -1;
275}
276
277static enum print_line_t irqsoff_print_line(struct trace_iterator *iter)
278{
279 return TRACE_TYPE_UNHANDLED;
280}
281
282static void irqsoff_graph_return(struct ftrace_graph_ret *trace) { }
283static void irqsoff_trace_open(struct trace_iterator *iter) { }
284static void irqsoff_trace_close(struct trace_iterator *iter) { }
285
286#ifdef CONFIG_FUNCTION_TRACER
287static void irqsoff_print_header(struct seq_file *s)
288{
289 trace_default_header(s);
290}
291#else
292static void irqsoff_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
315check_critical_timing(struct trace_array *tr,
316 struct trace_array_cpu *data,
317 unsigned long parent_ip,
318 int cpu)
319{
320 cycle_t T0, T1, delta;
321 unsigned long flags;
322 int pc;
323
324 T0 = data->preempt_timestamp;
325 T1 = ftrace_now(cpu);
326 delta = T1-T0;
327
328 local_save_flags(flags);
329
330 pc = preempt_count();
331
332 if (!report_latency(delta))
333 goto out;
334
335 raw_spin_lock_irqsave(&max_trace_lock, flags);
336
337 /* check if we are still the max latency */
338 if (!report_latency(delta))
339 goto out_unlock;
340
341 __trace_function(tr, CALLER_ADDR0, parent_ip, flags, pc);
342 /* Skip 5 functions to get to the irq/preempt enable function */
343 __trace_stack(tr, flags, 5, pc);
344
345 if (data->critical_sequence != max_sequence)
346 goto out_unlock;
347
348 data->critical_end = parent_ip;
349
350 if (likely(!is_tracing_stopped())) {
351 tracing_max_latency = delta;
352 update_max_tr_single(tr, current, cpu);
353 }
354
355 max_sequence++;
356
357out_unlock:
358 raw_spin_unlock_irqrestore(&max_trace_lock, flags);
359
360out:
361 data->critical_sequence = max_sequence;
362 data->preempt_timestamp = ftrace_now(cpu);
363 __trace_function(tr, CALLER_ADDR0, parent_ip, flags, pc);
364}
365
366static inline void
367start_critical_timing(unsigned long ip, unsigned long parent_ip)
368{
369 int cpu;
370 struct trace_array *tr = irqsoff_trace;
371 struct trace_array_cpu *data;
372 unsigned long flags;
373
374 if (likely(!tracer_enabled))
375 return;
376
377 cpu = raw_smp_processor_id();
378
379 if (per_cpu(tracing_cpu, cpu))
380 return;
381
382 data = tr->data[cpu];
383
384 if (unlikely(!data) || atomic_read(&data->disabled))
385 return;
386
387 atomic_inc(&data->disabled);
388
389 data->critical_sequence = max_sequence;
390 data->preempt_timestamp = ftrace_now(cpu);
391 data->critical_start = parent_ip ? : ip;
392
393 local_save_flags(flags);
394
395 __trace_function(tr, ip, parent_ip, flags, preempt_count());
396
397 per_cpu(tracing_cpu, cpu) = 1;
398
399 atomic_dec(&data->disabled);
400}
401
402static inline void
403stop_critical_timing(unsigned long ip, unsigned long parent_ip)
404{
405 int cpu;
406 struct trace_array *tr = irqsoff_trace;
407 struct trace_array_cpu *data;
408 unsigned long flags;
409
410 cpu = raw_smp_processor_id();
411 /* Always clear the tracing cpu on stopping the trace */
412 if (unlikely(per_cpu(tracing_cpu, cpu)))
413 per_cpu(tracing_cpu, cpu) = 0;
414 else
415 return;
416
417 if (!tracer_enabled)
418 return;
419
420 data = tr->data[cpu];
421
422 if (unlikely(!data) ||
423 !data->critical_start || atomic_read(&data->disabled))
424 return;
425
426 atomic_inc(&data->disabled);
427
428 local_save_flags(flags);
429 __trace_function(tr, ip, parent_ip, flags, preempt_count());
430 check_critical_timing(tr, data, parent_ip ? : ip, cpu);
431 data->critical_start = 0;
432 atomic_dec(&data->disabled);
433}
434
435/* start and stop critical timings used to for stoppage (in idle) */
436void start_critical_timings(void)
437{
438 if (preempt_trace() || irq_trace())
439 start_critical_timing(CALLER_ADDR0, CALLER_ADDR1);
440}
441EXPORT_SYMBOL_GPL(start_critical_timings);
442
443void stop_critical_timings(void)
444{
445 if (preempt_trace() || irq_trace())
446 stop_critical_timing(CALLER_ADDR0, CALLER_ADDR1);
447}
448EXPORT_SYMBOL_GPL(stop_critical_timings);
449
450#ifdef CONFIG_IRQSOFF_TRACER
451#ifdef CONFIG_PROVE_LOCKING
452void time_hardirqs_on(unsigned long a0, unsigned long a1)
453{
454 if (!preempt_trace() && irq_trace())
455 stop_critical_timing(a0, a1);
456}
457
458void time_hardirqs_off(unsigned long a0, unsigned long a1)
459{
460 if (!preempt_trace() && irq_trace())
461 start_critical_timing(a0, a1);
462}
463
464#else /* !CONFIG_PROVE_LOCKING */
465
466/*
467 * Stubs:
468 */
469
470void trace_softirqs_on(unsigned long ip)
471{
472}
473
474void trace_softirqs_off(unsigned long ip)
475{
476}
477
478inline void print_irqtrace_events(struct task_struct *curr)
479{
480}
481
482/*
483 * We are only interested in hardirq on/off events:
484 */
485void trace_hardirqs_on(void)
486{
487 if (!preempt_trace() && irq_trace())
488 stop_critical_timing(CALLER_ADDR0, CALLER_ADDR1);
489}
490EXPORT_SYMBOL(trace_hardirqs_on);
491
492void trace_hardirqs_off(void)
493{
494 if (!preempt_trace() && irq_trace())
495 start_critical_timing(CALLER_ADDR0, CALLER_ADDR1);
496}
497EXPORT_SYMBOL(trace_hardirqs_off);
498
499void trace_hardirqs_on_caller(unsigned long caller_addr)
500{
501 if (!preempt_trace() && irq_trace())
502 stop_critical_timing(CALLER_ADDR0, caller_addr);
503}
504EXPORT_SYMBOL(trace_hardirqs_on_caller);
505
506void trace_hardirqs_off_caller(unsigned long caller_addr)
507{
508 if (!preempt_trace() && irq_trace())
509 start_critical_timing(CALLER_ADDR0, caller_addr);
510}
511EXPORT_SYMBOL(trace_hardirqs_off_caller);
512
513#endif /* CONFIG_PROVE_LOCKING */
514#endif /* CONFIG_IRQSOFF_TRACER */
515
516#ifdef CONFIG_PREEMPT_TRACER
517void trace_preempt_on(unsigned long a0, unsigned long a1)
518{
519 if (preempt_trace() && !irq_trace())
520 stop_critical_timing(a0, a1);
521}
522
523void trace_preempt_off(unsigned long a0, unsigned long a1)
524{
525 if (preempt_trace() && !irq_trace())
526 start_critical_timing(a0, a1);
527}
528#endif /* CONFIG_PREEMPT_TRACER */
529
530static int start_irqsoff_tracer(struct trace_array *tr, int graph)
531{
532 int ret = 0;
533
534 if (!graph)
535 ret = register_ftrace_function(&trace_ops);
536 else
537 ret = register_ftrace_graph(&irqsoff_graph_return,
538 &irqsoff_graph_entry);
539
540 if (!ret && tracing_is_enabled())
541 tracer_enabled = 1;
542 else
543 tracer_enabled = 0;
544
545 return ret;
546}
547
548static void stop_irqsoff_tracer(struct trace_array *tr, int graph)
549{
550 tracer_enabled = 0;
551
552 if (!graph)
553 unregister_ftrace_function(&trace_ops);
554 else
555 unregister_ftrace_graph();
556}
557
558static void __irqsoff_tracer_init(struct trace_array *tr)
559{
560 save_lat_flag = trace_flags & TRACE_ITER_LATENCY_FMT;
561 trace_flags |= TRACE_ITER_LATENCY_FMT;
562
563 tracing_max_latency = 0;
564 irqsoff_trace = tr;
565 /* make sure that the tracer is visible */
566 smp_wmb();
567 tracing_reset_online_cpus(tr);
568
569 if (start_irqsoff_tracer(tr, is_graph()))
570 printk(KERN_ERR "failed to start irqsoff tracer\n");
571}
572
573static void irqsoff_tracer_reset(struct trace_array *tr)
574{
575 stop_irqsoff_tracer(tr, is_graph());
576
577 if (!save_lat_flag)
578 trace_flags &= ~TRACE_ITER_LATENCY_FMT;
579}
580
581static void irqsoff_tracer_start(struct trace_array *tr)
582{
583 tracer_enabled = 1;
584}
585
586static void irqsoff_tracer_stop(struct trace_array *tr)
587{
588 tracer_enabled = 0;
589}
590
591#ifdef CONFIG_IRQSOFF_TRACER
592static int irqsoff_tracer_init(struct trace_array *tr)
593{
594 trace_type = TRACER_IRQS_OFF;
595
596 __irqsoff_tracer_init(tr);
597 return 0;
598}
599static struct tracer irqsoff_tracer __read_mostly =
600{
601 .name = "irqsoff",
602 .init = irqsoff_tracer_init,
603 .reset = irqsoff_tracer_reset,
604 .start = irqsoff_tracer_start,
605 .stop = irqsoff_tracer_stop,
606 .print_max = 1,
607 .print_header = irqsoff_print_header,
608 .print_line = irqsoff_print_line,
609 .flags = &tracer_flags,
610 .set_flag = irqsoff_set_flag,
611#ifdef CONFIG_FTRACE_SELFTEST
612 .selftest = trace_selftest_startup_irqsoff,
613#endif
614 .open = irqsoff_trace_open,
615 .close = irqsoff_trace_close,
616 .use_max_tr = 1,
617};
618# define register_irqsoff(trace) register_tracer(&trace)
619#else
620# define register_irqsoff(trace) do { } while (0)
621#endif
622
623#ifdef CONFIG_PREEMPT_TRACER
624static int preemptoff_tracer_init(struct trace_array *tr)
625{
626 trace_type = TRACER_PREEMPT_OFF;
627
628 __irqsoff_tracer_init(tr);
629 return 0;
630}
631
632static struct tracer preemptoff_tracer __read_mostly =
633{
634 .name = "preemptoff",
635 .init = preemptoff_tracer_init,
636 .reset = irqsoff_tracer_reset,
637 .start = irqsoff_tracer_start,
638 .stop = irqsoff_tracer_stop,
639 .print_max = 1,
640 .print_header = irqsoff_print_header,
641 .print_line = irqsoff_print_line,
642 .flags = &tracer_flags,
643 .set_flag = irqsoff_set_flag,
644#ifdef CONFIG_FTRACE_SELFTEST
645 .selftest = trace_selftest_startup_preemptoff,
646#endif
647 .open = irqsoff_trace_open,
648 .close = irqsoff_trace_close,
649 .use_max_tr = 1,
650};
651# define register_preemptoff(trace) register_tracer(&trace)
652#else
653# define register_preemptoff(trace) do { } while (0)
654#endif
655
656#if defined(CONFIG_IRQSOFF_TRACER) && \
657 defined(CONFIG_PREEMPT_TRACER)
658
659static int preemptirqsoff_tracer_init(struct trace_array *tr)
660{
661 trace_type = TRACER_IRQS_OFF | TRACER_PREEMPT_OFF;
662
663 __irqsoff_tracer_init(tr);
664 return 0;
665}
666
667static struct tracer preemptirqsoff_tracer __read_mostly =
668{
669 .name = "preemptirqsoff",
670 .init = preemptirqsoff_tracer_init,
671 .reset = irqsoff_tracer_reset,
672 .start = irqsoff_tracer_start,
673 .stop = irqsoff_tracer_stop,
674 .print_max = 1,
675 .print_header = irqsoff_print_header,
676 .print_line = irqsoff_print_line,
677 .flags = &tracer_flags,
678 .set_flag = irqsoff_set_flag,
679#ifdef CONFIG_FTRACE_SELFTEST
680 .selftest = trace_selftest_startup_preemptirqsoff,
681#endif
682 .open = irqsoff_trace_open,
683 .close = irqsoff_trace_close,
684 .use_max_tr = 1,
685};
686
687# define register_preemptirqsoff(trace) register_tracer(&trace)
688#else
689# define register_preemptirqsoff(trace) do { } while (0)
690#endif
691
692__init static int init_irqsoff_tracer(void)
693{
694 register_irqsoff(irqsoff_tracer);
695 register_preemptoff(preemptoff_tracer);
696 register_preemptirqsoff(preemptirqsoff_tracer);
697
698 return 0;
699}
700device_initcall(init_irqsoff_tracer);