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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 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_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_print_header(struct seq_file *s) { }
284static void irqsoff_trace_open(struct trace_iterator *iter) { }
285static void irqsoff_trace_close(struct trace_iterator *iter) { }
286#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
287
288/*
289 * Should this new latency be reported/recorded?
290 */
291static int report_latency(cycle_t delta)
292{
293 if (tracing_thresh) {
294 if (delta < tracing_thresh)
295 return 0;
296 } else {
297 if (delta <= tracing_max_latency)
298 return 0;
299 }
300 return 1;
301}
302
303static void
304check_critical_timing(struct trace_array *tr,
305 struct trace_array_cpu *data,
306 unsigned long parent_ip,
307 int cpu)
308{
309 cycle_t T0, T1, delta;
310 unsigned long flags;
311 int pc;
312
313 T0 = data->preempt_timestamp;
314 T1 = ftrace_now(cpu);
315 delta = T1-T0;
316
317 local_save_flags(flags);
318
319 pc = preempt_count();
320
321 if (!report_latency(delta))
322 goto out;
323
324 spin_lock_irqsave(&max_trace_lock, flags);
325
326 /* check if we are still the max latency */
327 if (!report_latency(delta))
328 goto out_unlock;
329
330 __trace_function(tr, CALLER_ADDR0, parent_ip, flags, pc);
331 /* Skip 5 functions to get to the irq/preempt enable function */
332 __trace_stack(tr, flags, 5, pc);
333
334 if (data->critical_sequence != max_sequence)
335 goto out_unlock;
336
337 data->critical_end = parent_ip;
338
339 if (likely(!is_tracing_stopped())) {
340 tracing_max_latency = delta;
341 update_max_tr_single(tr, current, cpu);
342 }
343
344 max_sequence++;
345
346out_unlock:
347 spin_unlock_irqrestore(&max_trace_lock, flags);
348
349out:
350 data->critical_sequence = max_sequence;
351 data->preempt_timestamp = ftrace_now(cpu);
352 __trace_function(tr, CALLER_ADDR0, parent_ip, flags, pc);
353}
354
355static inline void
356start_critical_timing(unsigned long ip, unsigned long parent_ip)
357{
358 int cpu;
359 struct trace_array *tr = irqsoff_trace;
360 struct trace_array_cpu *data;
361 unsigned long flags;
362
363 if (likely(!tracer_enabled))
364 return;
365
366 cpu = raw_smp_processor_id();
367
368 if (per_cpu(tracing_cpu, cpu))
369 return;
370
371 data = tr->data[cpu];
372
373 if (unlikely(!data) || atomic_read(&data->disabled))
374 return;
375
376 atomic_inc(&data->disabled);
377
378 data->critical_sequence = max_sequence;
379 data->preempt_timestamp = ftrace_now(cpu);
380 data->critical_start = parent_ip ? : ip;
381
382 local_save_flags(flags);
383
384 __trace_function(tr, ip, parent_ip, flags, preempt_count());
385
386 per_cpu(tracing_cpu, cpu) = 1;
387
388 atomic_dec(&data->disabled);
389}
390
391static inline void
392stop_critical_timing(unsigned long ip, unsigned long parent_ip)
393{
394 int cpu;
395 struct trace_array *tr = irqsoff_trace;
396 struct trace_array_cpu *data;
397 unsigned long flags;
398
399 cpu = raw_smp_processor_id();
400 /* Always clear the tracing cpu on stopping the trace */
401 if (unlikely(per_cpu(tracing_cpu, cpu)))
402 per_cpu(tracing_cpu, cpu) = 0;
403 else
404 return;
405
406 if (!tracer_enabled)
407 return;
408
409 data = tr->data[cpu];
410
411 if (unlikely(!data) ||
412 !data->critical_start || atomic_read(&data->disabled))
413 return;
414
415 atomic_inc(&data->disabled);
416
417 local_save_flags(flags);
418 __trace_function(tr, ip, parent_ip, flags, preempt_count());
419 check_critical_timing(tr, data, parent_ip ? : ip, cpu);
420 data->critical_start = 0;
421 atomic_dec(&data->disabled);
422}
423
424/* start and stop critical timings used to for stoppage (in idle) */
425void start_critical_timings(void)
426{
427 if (preempt_trace() || irq_trace())
428 start_critical_timing(CALLER_ADDR0, CALLER_ADDR1);
429}
430EXPORT_SYMBOL_GPL(start_critical_timings);
431
432void stop_critical_timings(void)
433{
434 if (preempt_trace() || irq_trace())
435 stop_critical_timing(CALLER_ADDR0, CALLER_ADDR1);
436}
437EXPORT_SYMBOL_GPL(stop_critical_timings);
438
439#ifdef CONFIG_IRQSOFF_TRACER
440#ifdef CONFIG_PROVE_LOCKING
441void time_hardirqs_on(unsigned long a0, unsigned long a1)
442{
443 if (!preempt_trace() && irq_trace())
444 stop_critical_timing(a0, a1);
445}
446
447void time_hardirqs_off(unsigned long a0, unsigned long a1)
448{
449 if (!preempt_trace() && irq_trace())
450 start_critical_timing(a0, a1);
451}
452
453#else /* !CONFIG_PROVE_LOCKING */
454
455/*
456 * Stubs:
457 */
458
459void trace_softirqs_on(unsigned long ip)
460{
461}
462
463void trace_softirqs_off(unsigned long ip)
464{
465}
466
467inline void print_irqtrace_events(struct task_struct *curr)
468{
469}
470
471/*
472 * We are only interested in hardirq on/off events:
473 */
474void trace_hardirqs_on(void)
475{
476 if (!preempt_trace() && irq_trace())
477 stop_critical_timing(CALLER_ADDR0, CALLER_ADDR1);
478}
479EXPORT_SYMBOL(trace_hardirqs_on);
480
481void trace_hardirqs_off(void)
482{
483 if (!preempt_trace() && irq_trace())
484 start_critical_timing(CALLER_ADDR0, CALLER_ADDR1);
485}
486EXPORT_SYMBOL(trace_hardirqs_off);
487
488void trace_hardirqs_on_caller(unsigned long caller_addr)
489{
490 if (!preempt_trace() && irq_trace())
491 stop_critical_timing(CALLER_ADDR0, caller_addr);
492}
493EXPORT_SYMBOL(trace_hardirqs_on_caller);
494
495void trace_hardirqs_off_caller(unsigned long caller_addr)
496{
497 if (!preempt_trace() && irq_trace())
498 start_critical_timing(CALLER_ADDR0, caller_addr);
499}
500EXPORT_SYMBOL(trace_hardirqs_off_caller);
501
502#endif /* CONFIG_PROVE_LOCKING */
503#endif /* CONFIG_IRQSOFF_TRACER */
504
505#ifdef CONFIG_PREEMPT_TRACER
506void trace_preempt_on(unsigned long a0, unsigned long a1)
507{
508 if (preempt_trace())
509 stop_critical_timing(a0, a1);
510}
511
512void trace_preempt_off(unsigned long a0, unsigned long a1)
513{
514 if (preempt_trace())
515 start_critical_timing(a0, a1);
516}
517#endif /* CONFIG_PREEMPT_TRACER */
518
519static int start_irqsoff_tracer(struct trace_array *tr, int graph)
520{
521 int ret = 0;
522
523 if (!graph)
524 ret = register_ftrace_function(&trace_ops);
525 else
526 ret = register_ftrace_graph(&irqsoff_graph_return,
527 &irqsoff_graph_entry);
528
529 if (!ret && tracing_is_enabled())
530 tracer_enabled = 1;
531 else
532 tracer_enabled = 0;
533
534 return ret;
535}
536
537static void stop_irqsoff_tracer(struct trace_array *tr, int graph)
538{
539 tracer_enabled = 0;
540
541 if (!graph)
542 unregister_ftrace_function(&trace_ops);
543 else
544 unregister_ftrace_graph();
545}
546
547static void __irqsoff_tracer_init(struct trace_array *tr)
548{
549 save_lat_flag = trace_flags & TRACE_ITER_LATENCY_FMT;
550 trace_flags |= TRACE_ITER_LATENCY_FMT;
551
552 tracing_max_latency = 0;
553 irqsoff_trace = tr;
554 /* make sure that the tracer is visible */
555 smp_wmb();
556 tracing_reset_online_cpus(tr);
557
558 if (start_irqsoff_tracer(tr, is_graph()))
559 printk(KERN_ERR "failed to start irqsoff tracer\n");
560}
561
562static void irqsoff_tracer_reset(struct trace_array *tr)
563{
564 stop_irqsoff_tracer(tr, is_graph());
565
566 if (!save_lat_flag)
567 trace_flags &= ~TRACE_ITER_LATENCY_FMT;
568}
569
570static void irqsoff_tracer_start(struct trace_array *tr)
571{
572 tracer_enabled = 1;
573}
574
575static void irqsoff_tracer_stop(struct trace_array *tr)
576{
577 tracer_enabled = 0;
578}
579
580#ifdef CONFIG_IRQSOFF_TRACER
581static int irqsoff_tracer_init(struct trace_array *tr)
582{
583 trace_type = TRACER_IRQS_OFF;
584
585 __irqsoff_tracer_init(tr);
586 return 0;
587}
588static struct tracer irqsoff_tracer __read_mostly =
589{
590 .name = "irqsoff",
591 .init = irqsoff_tracer_init,
592 .reset = irqsoff_tracer_reset,
593 .start = irqsoff_tracer_start,
594 .stop = irqsoff_tracer_stop,
595 .print_max = 1,
596 .print_header = irqsoff_print_header,
597 .print_line = irqsoff_print_line,
598 .flags = &tracer_flags,
599 .set_flag = irqsoff_set_flag,
600#ifdef CONFIG_FTRACE_SELFTEST
601 .selftest = trace_selftest_startup_irqsoff,
602#endif
603 .open = irqsoff_trace_open,
604 .close = irqsoff_trace_close,
605 .use_max_tr = 1,
606};
607# define register_irqsoff(trace) register_tracer(&trace)
608#else
609# define register_irqsoff(trace) do { } while (0)
610#endif
611
612#ifdef CONFIG_PREEMPT_TRACER
613static int preemptoff_tracer_init(struct trace_array *tr)
614{
615 trace_type = TRACER_PREEMPT_OFF;
616
617 __irqsoff_tracer_init(tr);
618 return 0;
619}
620
621static struct tracer preemptoff_tracer __read_mostly =
622{
623 .name = "preemptoff",
624 .init = preemptoff_tracer_init,
625 .reset = irqsoff_tracer_reset,
626 .start = irqsoff_tracer_start,
627 .stop = irqsoff_tracer_stop,
628 .print_max = 1,
629 .print_header = irqsoff_print_header,
630 .print_line = irqsoff_print_line,
631 .flags = &tracer_flags,
632 .set_flag = irqsoff_set_flag,
633#ifdef CONFIG_FTRACE_SELFTEST
634 .selftest = trace_selftest_startup_preemptoff,
635#endif
636 .open = irqsoff_trace_open,
637 .close = irqsoff_trace_close,
638 .use_max_tr = 1,
639};
640# define register_preemptoff(trace) register_tracer(&trace)
641#else
642# define register_preemptoff(trace) do { } while (0)
643#endif
644
645#if defined(CONFIG_IRQSOFF_TRACER) && \
646 defined(CONFIG_PREEMPT_TRACER)
647
648static int preemptirqsoff_tracer_init(struct trace_array *tr)
649{
650 trace_type = TRACER_IRQS_OFF | TRACER_PREEMPT_OFF;
651
652 __irqsoff_tracer_init(tr);
653 return 0;
654}
655
656static struct tracer preemptirqsoff_tracer __read_mostly =
657{
658 .name = "preemptirqsoff",
659 .init = preemptirqsoff_tracer_init,
660 .reset = irqsoff_tracer_reset,
661 .start = irqsoff_tracer_start,
662 .stop = irqsoff_tracer_stop,
663 .print_max = 1,
664 .print_header = irqsoff_print_header,
665 .print_line = irqsoff_print_line,
666 .flags = &tracer_flags,
667 .set_flag = irqsoff_set_flag,
668#ifdef CONFIG_FTRACE_SELFTEST
669 .selftest = trace_selftest_startup_preemptirqsoff,
670#endif
671 .open = irqsoff_trace_open,
672 .close = irqsoff_trace_close,
673 .use_max_tr = 1,
674};
675
676# define register_preemptirqsoff(trace) register_tracer(&trace)
677#else
678# define register_preemptirqsoff(trace) do { } while (0)
679#endif
680
681__init static int init_irqsoff_tracer(void)
682{
683 register_irqsoff(irqsoff_tracer);
684 register_preemptoff(preemptoff_tracer);
685 register_preemptirqsoff(preemptirqsoff_tracer);
686
687 return 0;
688}
689device_initcall(init_irqsoff_tracer);