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