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