tracing/filter: Swap entire filter of events
[linux-2.6.git] / kernel / trace / trace_irqsoff.c
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
21 static struct trace_array               *irqsoff_trace __read_mostly;
22 static int                              tracer_enabled __read_mostly;
23
24 static DEFINE_PER_CPU(int, tracing_cpu);
25
26 static DEFINE_SPINLOCK(max_trace_lock);
27
28 enum {
29         TRACER_IRQS_OFF         = (1 << 1),
30         TRACER_PREEMPT_OFF      = (1 << 2),
31 };
32
33 static int trace_type __read_mostly;
34
35 static int save_lat_flag;
36
37 static void stop_irqsoff_tracer(struct trace_array *tr, int graph);
38 static int start_irqsoff_tracer(struct trace_array *tr, int graph);
39
40 #ifdef CONFIG_PREEMPT_TRACER
41 static inline int
42 preempt_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
51 static inline int
52 irq_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
63 static 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
71 static 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 doesnt
84  * decrease the validity of the maximum found:
85  */
86 static __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  */
102 static 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  */
138 static void
139 irqsoff_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
153 static struct ftrace_ops trace_ops __read_mostly =
154 {
155         .func = irqsoff_tracer_call,
156 };
157 #endif /* CONFIG_FUNCTION_TRACER */
158
159 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
160 static int irqsoff_set_flag(u32 old_flags, u32 bit, int set)
161 {
162         int cpu;
163
164         if (!(bit & TRACE_DISPLAY_GRAPH))
165                 return -EINVAL;
166
167         if (!(is_graph() ^ set))
168                 return 0;
169
170         stop_irqsoff_tracer(irqsoff_trace, !set);
171
172         for_each_possible_cpu(cpu)
173                 per_cpu(tracing_cpu, cpu) = 0;
174
175         tracing_max_latency = 0;
176         tracing_reset_online_cpus(irqsoff_trace);
177
178         return start_irqsoff_tracer(irqsoff_trace, set);
179 }
180
181 static int irqsoff_graph_entry(struct ftrace_graph_ent *trace)
182 {
183         struct trace_array *tr = irqsoff_trace;
184         struct trace_array_cpu *data;
185         unsigned long flags;
186         int ret;
187         int pc;
188
189         if (!func_prolog_dec(tr, &data, &flags))
190                 return 0;
191
192         pc = preempt_count();
193         ret = __trace_graph_entry(tr, trace, flags, pc);
194         atomic_dec(&data->disabled);
195
196         return ret;
197 }
198
199 static void irqsoff_graph_return(struct ftrace_graph_ret *trace)
200 {
201         struct trace_array *tr = irqsoff_trace;
202         struct trace_array_cpu *data;
203         unsigned long flags;
204         int pc;
205
206         if (!func_prolog_dec(tr, &data, &flags))
207                 return;
208
209         pc = preempt_count();
210         __trace_graph_return(tr, trace, flags, pc);
211         atomic_dec(&data->disabled);
212 }
213
214 static void irqsoff_trace_open(struct trace_iterator *iter)
215 {
216         if (is_graph())
217                 graph_trace_open(iter);
218
219 }
220
221 static void irqsoff_trace_close(struct trace_iterator *iter)
222 {
223         if (iter->private)
224                 graph_trace_close(iter);
225 }
226
227 #define GRAPH_TRACER_FLAGS (TRACE_GRAPH_PRINT_CPU | \
228                             TRACE_GRAPH_PRINT_PROC)
229
230 static enum print_line_t irqsoff_print_line(struct trace_iterator *iter)
231 {
232         /*
233          * In graph mode call the graph tracer output function,
234          * otherwise go with the TRACE_FN event handler
235          */
236         if (is_graph())
237                 return print_graph_function_flags(iter, GRAPH_TRACER_FLAGS);
238
239         return TRACE_TYPE_UNHANDLED;
240 }
241
242 static void irqsoff_print_header(struct seq_file *s)
243 {
244         if (is_graph())
245                 print_graph_headers_flags(s, GRAPH_TRACER_FLAGS);
246         else
247                 trace_default_header(s);
248 }
249
250 static void
251 __trace_function(struct trace_array *tr,
252                  unsigned long ip, unsigned long parent_ip,
253                  unsigned long flags, int pc)
254 {
255         if (is_graph())
256                 trace_graph_function(tr, ip, parent_ip, flags, pc);
257         else
258                 trace_function(tr, ip, parent_ip, flags, pc);
259 }
260
261 #else
262 #define __trace_function trace_function
263
264 static int irqsoff_set_flag(u32 old_flags, u32 bit, int set)
265 {
266         return -EINVAL;
267 }
268
269 static int irqsoff_graph_entry(struct ftrace_graph_ent *trace)
270 {
271         return -1;
272 }
273
274 static enum print_line_t irqsoff_print_line(struct trace_iterator *iter)
275 {
276         return TRACE_TYPE_UNHANDLED;
277 }
278
279 static void irqsoff_graph_return(struct ftrace_graph_ret *trace) { }
280 static void irqsoff_print_header(struct seq_file *s) { }
281 static void irqsoff_trace_open(struct trace_iterator *iter) { }
282 static void irqsoff_trace_close(struct trace_iterator *iter) { }
283 #endif /* CONFIG_FUNCTION_GRAPH_TRACER */
284
285 /*
286  * Should this new latency be reported/recorded?
287  */
288 static int report_latency(cycle_t delta)
289 {
290         if (tracing_thresh) {
291                 if (delta < tracing_thresh)
292                         return 0;
293         } else {
294                 if (delta <= tracing_max_latency)
295                         return 0;
296         }
297         return 1;
298 }
299
300 static void
301 check_critical_timing(struct trace_array *tr,
302                       struct trace_array_cpu *data,
303                       unsigned long parent_ip,
304                       int cpu)
305 {
306         cycle_t T0, T1, delta;
307         unsigned long flags;
308         int pc;
309
310         T0 = data->preempt_timestamp;
311         T1 = ftrace_now(cpu);
312         delta = T1-T0;
313
314         local_save_flags(flags);
315
316         pc = preempt_count();
317
318         if (!report_latency(delta))
319                 goto out;
320
321         spin_lock_irqsave(&max_trace_lock, flags);
322
323         /* check if we are still the max latency */
324         if (!report_latency(delta))
325                 goto out_unlock;
326
327         __trace_function(tr, CALLER_ADDR0, parent_ip, flags, pc);
328         /* Skip 5 functions to get to the irq/preempt enable function */
329         __trace_stack(tr, flags, 5, pc);
330
331         if (data->critical_sequence != max_sequence)
332                 goto out_unlock;
333
334         data->critical_end = parent_ip;
335
336         if (likely(!is_tracing_stopped())) {
337                 tracing_max_latency = delta;
338                 update_max_tr_single(tr, current, cpu);
339         }
340
341         max_sequence++;
342
343 out_unlock:
344         spin_unlock_irqrestore(&max_trace_lock, flags);
345
346 out:
347         data->critical_sequence = max_sequence;
348         data->preempt_timestamp = ftrace_now(cpu);
349         __trace_function(tr, CALLER_ADDR0, parent_ip, flags, pc);
350 }
351
352 static inline void
353 start_critical_timing(unsigned long ip, unsigned long parent_ip)
354 {
355         int cpu;
356         struct trace_array *tr = irqsoff_trace;
357         struct trace_array_cpu *data;
358         unsigned long flags;
359
360         if (likely(!tracer_enabled))
361                 return;
362
363         cpu = raw_smp_processor_id();
364
365         if (per_cpu(tracing_cpu, cpu))
366                 return;
367
368         data = tr->data[cpu];
369
370         if (unlikely(!data) || atomic_read(&data->disabled))
371                 return;
372
373         atomic_inc(&data->disabled);
374
375         data->critical_sequence = max_sequence;
376         data->preempt_timestamp = ftrace_now(cpu);
377         data->critical_start = parent_ip ? : ip;
378
379         local_save_flags(flags);
380
381         __trace_function(tr, ip, parent_ip, flags, preempt_count());
382
383         per_cpu(tracing_cpu, cpu) = 1;
384
385         atomic_dec(&data->disabled);
386 }
387
388 static inline void
389 stop_critical_timing(unsigned long ip, unsigned long parent_ip)
390 {
391         int cpu;
392         struct trace_array *tr = irqsoff_trace;
393         struct trace_array_cpu *data;
394         unsigned long flags;
395
396         cpu = raw_smp_processor_id();
397         /* Always clear the tracing cpu on stopping the trace */
398         if (unlikely(per_cpu(tracing_cpu, cpu)))
399                 per_cpu(tracing_cpu, cpu) = 0;
400         else
401                 return;
402
403         if (!tracer_enabled)
404                 return;
405
406         data = tr->data[cpu];
407
408         if (unlikely(!data) ||
409             !data->critical_start || atomic_read(&data->disabled))
410                 return;
411
412         atomic_inc(&data->disabled);
413
414         local_save_flags(flags);
415         __trace_function(tr, ip, parent_ip, flags, preempt_count());
416         check_critical_timing(tr, data, parent_ip ? : ip, cpu);
417         data->critical_start = 0;
418         atomic_dec(&data->disabled);
419 }
420
421 /* start and stop critical timings used to for stoppage (in idle) */
422 void start_critical_timings(void)
423 {
424         if (preempt_trace() || irq_trace())
425                 start_critical_timing(CALLER_ADDR0, CALLER_ADDR1);
426 }
427 EXPORT_SYMBOL_GPL(start_critical_timings);
428
429 void stop_critical_timings(void)
430 {
431         if (preempt_trace() || irq_trace())
432                 stop_critical_timing(CALLER_ADDR0, CALLER_ADDR1);
433 }
434 EXPORT_SYMBOL_GPL(stop_critical_timings);
435
436 #ifdef CONFIG_IRQSOFF_TRACER
437 #ifdef CONFIG_PROVE_LOCKING
438 void time_hardirqs_on(unsigned long a0, unsigned long a1)
439 {
440         if (!preempt_trace() && irq_trace())
441                 stop_critical_timing(a0, a1);
442 }
443
444 void time_hardirqs_off(unsigned long a0, unsigned long a1)
445 {
446         if (!preempt_trace() && irq_trace())
447                 start_critical_timing(a0, a1);
448 }
449
450 #else /* !CONFIG_PROVE_LOCKING */
451
452 /*
453  * Stubs:
454  */
455
456 void trace_softirqs_on(unsigned long ip)
457 {
458 }
459
460 void trace_softirqs_off(unsigned long ip)
461 {
462 }
463
464 inline void print_irqtrace_events(struct task_struct *curr)
465 {
466 }
467
468 /*
469  * We are only interested in hardirq on/off events:
470  */
471 void trace_hardirqs_on(void)
472 {
473         if (!preempt_trace() && irq_trace())
474                 stop_critical_timing(CALLER_ADDR0, CALLER_ADDR1);
475 }
476 EXPORT_SYMBOL(trace_hardirqs_on);
477
478 void trace_hardirqs_off(void)
479 {
480         if (!preempt_trace() && irq_trace())
481                 start_critical_timing(CALLER_ADDR0, CALLER_ADDR1);
482 }
483 EXPORT_SYMBOL(trace_hardirqs_off);
484
485 void trace_hardirqs_on_caller(unsigned long caller_addr)
486 {
487         if (!preempt_trace() && irq_trace())
488                 stop_critical_timing(CALLER_ADDR0, caller_addr);
489 }
490 EXPORT_SYMBOL(trace_hardirqs_on_caller);
491
492 void trace_hardirqs_off_caller(unsigned long caller_addr)
493 {
494         if (!preempt_trace() && irq_trace())
495                 start_critical_timing(CALLER_ADDR0, caller_addr);
496 }
497 EXPORT_SYMBOL(trace_hardirqs_off_caller);
498
499 #endif /* CONFIG_PROVE_LOCKING */
500 #endif /*  CONFIG_IRQSOFF_TRACER */
501
502 #ifdef CONFIG_PREEMPT_TRACER
503 void trace_preempt_on(unsigned long a0, unsigned long a1)
504 {
505         if (preempt_trace())
506                 stop_critical_timing(a0, a1);
507 }
508
509 void trace_preempt_off(unsigned long a0, unsigned long a1)
510 {
511         if (preempt_trace())
512                 start_critical_timing(a0, a1);
513 }
514 #endif /* CONFIG_PREEMPT_TRACER */
515
516 static int start_irqsoff_tracer(struct trace_array *tr, int graph)
517 {
518         int ret = 0;
519
520         if (!graph)
521                 ret = register_ftrace_function(&trace_ops);
522         else
523                 ret = register_ftrace_graph(&irqsoff_graph_return,
524                                             &irqsoff_graph_entry);
525
526         if (!ret && tracing_is_enabled())
527                 tracer_enabled = 1;
528         else
529                 tracer_enabled = 0;
530
531         return ret;
532 }
533
534 static void stop_irqsoff_tracer(struct trace_array *tr, int graph)
535 {
536         tracer_enabled = 0;
537
538         if (!graph)
539                 unregister_ftrace_function(&trace_ops);
540         else
541                 unregister_ftrace_graph();
542 }
543
544 static void __irqsoff_tracer_init(struct trace_array *tr)
545 {
546         save_lat_flag = trace_flags & TRACE_ITER_LATENCY_FMT;
547         trace_flags |= TRACE_ITER_LATENCY_FMT;
548
549         tracing_max_latency = 0;
550         irqsoff_trace = tr;
551         /* make sure that the tracer is visible */
552         smp_wmb();
553         tracing_reset_online_cpus(tr);
554
555         if (start_irqsoff_tracer(tr, is_graph()))
556                 printk(KERN_ERR "failed to start irqsoff tracer\n");
557 }
558
559 static void irqsoff_tracer_reset(struct trace_array *tr)
560 {
561         stop_irqsoff_tracer(tr, is_graph());
562
563         if (!save_lat_flag)
564                 trace_flags &= ~TRACE_ITER_LATENCY_FMT;
565 }
566
567 static void irqsoff_tracer_start(struct trace_array *tr)
568 {
569         tracer_enabled = 1;
570 }
571
572 static void irqsoff_tracer_stop(struct trace_array *tr)
573 {
574         tracer_enabled = 0;
575 }
576
577 #ifdef CONFIG_IRQSOFF_TRACER
578 static int irqsoff_tracer_init(struct trace_array *tr)
579 {
580         trace_type = TRACER_IRQS_OFF;
581
582         __irqsoff_tracer_init(tr);
583         return 0;
584 }
585 static struct tracer irqsoff_tracer __read_mostly =
586 {
587         .name           = "irqsoff",
588         .init           = irqsoff_tracer_init,
589         .reset          = irqsoff_tracer_reset,
590         .start          = irqsoff_tracer_start,
591         .stop           = irqsoff_tracer_stop,
592         .print_max      = 1,
593         .print_header   = irqsoff_print_header,
594         .print_line     = irqsoff_print_line,
595         .flags          = &tracer_flags,
596         .set_flag       = irqsoff_set_flag,
597 #ifdef CONFIG_FTRACE_SELFTEST
598         .selftest    = trace_selftest_startup_irqsoff,
599 #endif
600         .open           = irqsoff_trace_open,
601         .close          = irqsoff_trace_close,
602         .use_max_tr     = 1,
603 };
604 # define register_irqsoff(trace) register_tracer(&trace)
605 #else
606 # define register_irqsoff(trace) do { } while (0)
607 #endif
608
609 #ifdef CONFIG_PREEMPT_TRACER
610 static int preemptoff_tracer_init(struct trace_array *tr)
611 {
612         trace_type = TRACER_PREEMPT_OFF;
613
614         __irqsoff_tracer_init(tr);
615         return 0;
616 }
617
618 static struct tracer preemptoff_tracer __read_mostly =
619 {
620         .name           = "preemptoff",
621         .init           = preemptoff_tracer_init,
622         .reset          = irqsoff_tracer_reset,
623         .start          = irqsoff_tracer_start,
624         .stop           = irqsoff_tracer_stop,
625         .print_max      = 1,
626         .print_header   = irqsoff_print_header,
627         .print_line     = irqsoff_print_line,
628         .flags          = &tracer_flags,
629         .set_flag       = irqsoff_set_flag,
630 #ifdef CONFIG_FTRACE_SELFTEST
631         .selftest    = trace_selftest_startup_preemptoff,
632 #endif
633         .open           = irqsoff_trace_open,
634         .close          = irqsoff_trace_close,
635         .use_max_tr     = 1,
636 };
637 # define register_preemptoff(trace) register_tracer(&trace)
638 #else
639 # define register_preemptoff(trace) do { } while (0)
640 #endif
641
642 #if defined(CONFIG_IRQSOFF_TRACER) && \
643         defined(CONFIG_PREEMPT_TRACER)
644
645 static int preemptirqsoff_tracer_init(struct trace_array *tr)
646 {
647         trace_type = TRACER_IRQS_OFF | TRACER_PREEMPT_OFF;
648
649         __irqsoff_tracer_init(tr);
650         return 0;
651 }
652
653 static struct tracer preemptirqsoff_tracer __read_mostly =
654 {
655         .name           = "preemptirqsoff",
656         .init           = preemptirqsoff_tracer_init,
657         .reset          = irqsoff_tracer_reset,
658         .start          = irqsoff_tracer_start,
659         .stop           = irqsoff_tracer_stop,
660         .print_max      = 1,
661         .print_header   = irqsoff_print_header,
662         .print_line     = irqsoff_print_line,
663         .flags          = &tracer_flags,
664         .set_flag       = irqsoff_set_flag,
665 #ifdef CONFIG_FTRACE_SELFTEST
666         .selftest    = trace_selftest_startup_preemptirqsoff,
667 #endif
668         .open           = irqsoff_trace_open,
669         .close          = irqsoff_trace_close,
670         .use_max_tr     = 1,
671 };
672
673 # define register_preemptirqsoff(trace) register_tracer(&trace)
674 #else
675 # define register_preemptirqsoff(trace) do { } while (0)
676 #endif
677
678 __init static int init_irqsoff_tracer(void)
679 {
680         register_irqsoff(irqsoff_tracer);
681         register_preemptoff(preemptoff_tracer);
682         register_preemptirqsoff(preemptirqsoff_tracer);
683
684         return 0;
685 }
686 device_initcall(init_irqsoff_tracer);