2 * trace irqs off critical timings
4 * Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com>
5 * Copyright (C) 2008 Ingo Molnar <mingo@redhat.com>
7 * From code in the latency_tracer, that is:
9 * Copyright (C) 2004-2006 Ingo Molnar
10 * Copyright (C) 2004 Nadia Yvette Chambers
12 #include <linux/kallsyms.h>
13 #include <linux/uaccess.h>
14 #include <linux/module.h>
15 #include <linux/ftrace.h>
19 static struct trace_array
*irqsoff_trace __read_mostly
;
20 static int tracer_enabled __read_mostly
;
22 static DEFINE_PER_CPU(int, tracing_cpu
);
24 static DEFINE_RAW_SPINLOCK(max_trace_lock
);
27 TRACER_IRQS_OFF
= (1 << 1),
28 TRACER_PREEMPT_OFF
= (1 << 2),
31 static int trace_type __read_mostly
;
33 static int save_flags
;
35 static void stop_irqsoff_tracer(struct trace_array
*tr
, int graph
);
36 static int start_irqsoff_tracer(struct trace_array
*tr
, int graph
);
38 #ifdef CONFIG_PREEMPT_TRACER
42 return ((trace_type
& TRACER_PREEMPT_OFF
) && preempt_count());
45 # define preempt_trace() (0)
48 #ifdef CONFIG_IRQSOFF_TRACER
52 return ((trace_type
& TRACER_IRQS_OFF
) &&
56 # define irq_trace() (0)
59 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
60 static int irqsoff_display_graph(struct trace_array
*tr
, int set
);
61 # define is_graph(tr) ((tr)->trace_flags & TRACE_ITER_DISPLAY_GRAPH)
63 static inline int irqsoff_display_graph(struct trace_array
*tr
, int set
)
67 # define is_graph(tr) false
71 * Sequence count - we record it when starting a measurement and
72 * skip the latency if the sequence has changed - some other section
73 * did a maximum and could disturb our measurement with serial console
74 * printouts, etc. Truly coinciding maximum latencies should be rare
75 * and what happens together happens separately as well, so this doesn't
76 * decrease the validity of the maximum found:
78 static __cacheline_aligned_in_smp
unsigned long max_sequence
;
80 #ifdef CONFIG_FUNCTION_TRACER
82 * Prologue for the preempt and irqs off function tracers.
84 * Returns 1 if it is OK to continue, and data->disabled is
86 * 0 if the trace is to be ignored, and data->disabled
89 * Note, this function is also used outside this ifdef but
90 * inside the #ifdef of the function graph tracer below.
91 * This is OK, since the function graph tracer is
92 * dependent on the function tracer.
94 static int func_prolog_dec(struct trace_array
*tr
,
95 struct trace_array_cpu
**data
,
102 * Does not matter if we preempt. We test the flags
103 * afterward, to see if irqs are disabled or not.
104 * If we preempt and get a false positive, the flags
107 cpu
= raw_smp_processor_id();
108 if (likely(!per_cpu(tracing_cpu
, cpu
)))
111 local_save_flags(*flags
);
113 * Slight chance to get a false positive on tracing_cpu,
114 * although I'm starting to think there isn't a chance.
115 * Leave this for now just to be paranoid.
117 if (!irqs_disabled_flags(*flags
) && !preempt_count())
120 *data
= per_cpu_ptr(tr
->trace_buffer
.data
, cpu
);
121 disabled
= atomic_inc_return(&(*data
)->disabled
);
123 if (likely(disabled
== 1))
126 atomic_dec(&(*data
)->disabled
);
132 * irqsoff uses its own tracer function to keep the overhead down:
135 irqsoff_tracer_call(unsigned long ip
, unsigned long parent_ip
,
136 struct ftrace_ops
*op
, struct pt_regs
*pt_regs
)
138 struct trace_array
*tr
= irqsoff_trace
;
139 struct trace_array_cpu
*data
;
142 if (!func_prolog_dec(tr
, &data
, &flags
))
145 trace_function(tr
, ip
, parent_ip
, flags
, preempt_count());
147 atomic_dec(&data
->disabled
);
149 #endif /* CONFIG_FUNCTION_TRACER */
151 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
152 static int irqsoff_display_graph(struct trace_array
*tr
, int set
)
156 if (!(is_graph(tr
) ^ set
))
159 stop_irqsoff_tracer(irqsoff_trace
, !set
);
161 for_each_possible_cpu(cpu
)
162 per_cpu(tracing_cpu
, cpu
) = 0;
165 tracing_reset_online_cpus(&irqsoff_trace
->trace_buffer
);
167 return start_irqsoff_tracer(irqsoff_trace
, set
);
170 static int irqsoff_graph_entry(struct ftrace_graph_ent
*trace
)
172 struct trace_array
*tr
= irqsoff_trace
;
173 struct trace_array_cpu
*data
;
178 if (ftrace_graph_ignore_func(trace
))
181 * Do not trace a function if it's filtered by set_graph_notrace.
182 * Make the index of ret stack negative to indicate that it should
183 * ignore further functions. But it needs its own ret stack entry
184 * to recover the original index in order to continue tracing after
185 * returning from the function.
187 if (ftrace_graph_notrace_addr(trace
->func
))
190 if (!func_prolog_dec(tr
, &data
, &flags
))
193 pc
= preempt_count();
194 ret
= __trace_graph_entry(tr
, trace
, flags
, pc
);
195 atomic_dec(&data
->disabled
);
200 static void irqsoff_graph_return(struct ftrace_graph_ret
*trace
)
202 struct trace_array
*tr
= irqsoff_trace
;
203 struct trace_array_cpu
*data
;
207 if (!func_prolog_dec(tr
, &data
, &flags
))
210 pc
= preempt_count();
211 __trace_graph_return(tr
, trace
, flags
, pc
);
212 atomic_dec(&data
->disabled
);
215 static void irqsoff_trace_open(struct trace_iterator
*iter
)
217 if (is_graph(iter
->tr
))
218 graph_trace_open(iter
);
222 static void irqsoff_trace_close(struct trace_iterator
*iter
)
225 graph_trace_close(iter
);
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)
233 static enum print_line_t
irqsoff_print_line(struct trace_iterator
*iter
)
236 * In graph mode call the graph tracer output function,
237 * otherwise go with the TRACE_FN event handler
239 if (is_graph(iter
->tr
))
240 return print_graph_function_flags(iter
, GRAPH_TRACER_FLAGS
);
242 return TRACE_TYPE_UNHANDLED
;
245 static void irqsoff_print_header(struct seq_file
*s
)
247 struct trace_array
*tr
= irqsoff_trace
;
250 print_graph_headers_flags(s
, GRAPH_TRACER_FLAGS
);
252 trace_default_header(s
);
256 __trace_function(struct trace_array
*tr
,
257 unsigned long ip
, unsigned long parent_ip
,
258 unsigned long flags
, int pc
)
261 trace_graph_function(tr
, ip
, parent_ip
, flags
, pc
);
263 trace_function(tr
, ip
, parent_ip
, flags
, pc
);
267 #define __trace_function trace_function
269 #ifdef CONFIG_FUNCTION_TRACER
270 static int irqsoff_graph_entry(struct ftrace_graph_ent
*trace
)
276 static enum print_line_t
irqsoff_print_line(struct trace_iterator
*iter
)
278 return TRACE_TYPE_UNHANDLED
;
281 static void irqsoff_trace_open(struct trace_iterator
*iter
) { }
282 static void irqsoff_trace_close(struct trace_iterator
*iter
) { }
284 #ifdef CONFIG_FUNCTION_TRACER
285 static void irqsoff_graph_return(struct ftrace_graph_ret
*trace
) { }
286 static void irqsoff_print_header(struct seq_file
*s
)
288 trace_default_header(s
);
291 static void irqsoff_print_header(struct seq_file
*s
)
293 trace_latency_header(s
);
295 #endif /* CONFIG_FUNCTION_TRACER */
296 #endif /* CONFIG_FUNCTION_GRAPH_TRACER */
299 * Should this new latency be reported/recorded?
301 static bool report_latency(struct trace_array
*tr
, cycle_t delta
)
303 if (tracing_thresh
) {
304 if (delta
< tracing_thresh
)
307 if (delta
<= tr
->max_latency
)
314 check_critical_timing(struct trace_array
*tr
,
315 struct trace_array_cpu
*data
,
316 unsigned long parent_ip
,
319 cycle_t T0
, T1
, delta
;
323 T0
= data
->preempt_timestamp
;
324 T1
= ftrace_now(cpu
);
327 local_save_flags(flags
);
329 pc
= preempt_count();
331 if (!report_latency(tr
, delta
))
334 raw_spin_lock_irqsave(&max_trace_lock
, flags
);
336 /* check if we are still the max latency */
337 if (!report_latency(tr
, delta
))
340 __trace_function(tr
, CALLER_ADDR0
, parent_ip
, flags
, pc
);
341 /* Skip 5 functions to get to the irq/preempt enable function */
342 __trace_stack(tr
, flags
, 5, pc
);
344 if (data
->critical_sequence
!= max_sequence
)
347 data
->critical_end
= parent_ip
;
349 if (likely(!is_tracing_stopped())) {
350 tr
->max_latency
= delta
;
351 update_max_tr_single(tr
, current
, cpu
);
357 raw_spin_unlock_irqrestore(&max_trace_lock
, flags
);
360 data
->critical_sequence
= max_sequence
;
361 data
->preempt_timestamp
= ftrace_now(cpu
);
362 __trace_function(tr
, CALLER_ADDR0
, parent_ip
, flags
, pc
);
366 start_critical_timing(unsigned long ip
, unsigned long parent_ip
)
369 struct trace_array
*tr
= irqsoff_trace
;
370 struct trace_array_cpu
*data
;
373 if (!tracer_enabled
|| !tracing_is_enabled())
376 cpu
= raw_smp_processor_id();
378 if (per_cpu(tracing_cpu
, cpu
))
381 data
= per_cpu_ptr(tr
->trace_buffer
.data
, cpu
);
383 if (unlikely(!data
) || atomic_read(&data
->disabled
))
386 atomic_inc(&data
->disabled
);
388 data
->critical_sequence
= max_sequence
;
389 data
->preempt_timestamp
= ftrace_now(cpu
);
390 data
->critical_start
= parent_ip
? : ip
;
392 local_save_flags(flags
);
394 __trace_function(tr
, ip
, parent_ip
, flags
, preempt_count());
396 per_cpu(tracing_cpu
, cpu
) = 1;
398 atomic_dec(&data
->disabled
);
402 stop_critical_timing(unsigned long ip
, unsigned long parent_ip
)
405 struct trace_array
*tr
= irqsoff_trace
;
406 struct trace_array_cpu
*data
;
409 cpu
= raw_smp_processor_id();
410 /* Always clear the tracing cpu on stopping the trace */
411 if (unlikely(per_cpu(tracing_cpu
, cpu
)))
412 per_cpu(tracing_cpu
, cpu
) = 0;
416 if (!tracer_enabled
|| !tracing_is_enabled())
419 data
= per_cpu_ptr(tr
->trace_buffer
.data
, cpu
);
421 if (unlikely(!data
) ||
422 !data
->critical_start
|| atomic_read(&data
->disabled
))
425 atomic_inc(&data
->disabled
);
427 local_save_flags(flags
);
428 __trace_function(tr
, ip
, parent_ip
, flags
, preempt_count());
429 check_critical_timing(tr
, data
, parent_ip
? : ip
, cpu
);
430 data
->critical_start
= 0;
431 atomic_dec(&data
->disabled
);
434 /* start and stop critical timings used to for stoppage (in idle) */
435 void start_critical_timings(void)
437 if (preempt_trace() || irq_trace())
438 start_critical_timing(CALLER_ADDR0
, CALLER_ADDR1
);
440 EXPORT_SYMBOL_GPL(start_critical_timings
);
442 void stop_critical_timings(void)
444 if (preempt_trace() || irq_trace())
445 stop_critical_timing(CALLER_ADDR0
, CALLER_ADDR1
);
447 EXPORT_SYMBOL_GPL(stop_critical_timings
);
449 #ifdef CONFIG_IRQSOFF_TRACER
450 #ifdef CONFIG_PROVE_LOCKING
451 void time_hardirqs_on(unsigned long a0
, unsigned long a1
)
453 if (!preempt_trace() && irq_trace())
454 stop_critical_timing(a0
, a1
);
457 void time_hardirqs_off(unsigned long a0
, unsigned long a1
)
459 if (!preempt_trace() && irq_trace())
460 start_critical_timing(a0
, a1
);
463 #else /* !CONFIG_PROVE_LOCKING */
469 void trace_softirqs_on(unsigned long ip
)
473 void trace_softirqs_off(unsigned long ip
)
477 inline void print_irqtrace_events(struct task_struct
*curr
)
482 * We are only interested in hardirq on/off events:
484 void trace_hardirqs_on(void)
486 if (!preempt_trace() && irq_trace())
487 stop_critical_timing(CALLER_ADDR0
, CALLER_ADDR1
);
489 EXPORT_SYMBOL(trace_hardirqs_on
);
491 void trace_hardirqs_off(void)
493 if (!preempt_trace() && irq_trace())
494 start_critical_timing(CALLER_ADDR0
, CALLER_ADDR1
);
496 EXPORT_SYMBOL(trace_hardirqs_off
);
498 __visible
void trace_hardirqs_on_caller(unsigned long caller_addr
)
500 if (!preempt_trace() && irq_trace())
501 stop_critical_timing(CALLER_ADDR0
, caller_addr
);
503 EXPORT_SYMBOL(trace_hardirqs_on_caller
);
505 __visible
void trace_hardirqs_off_caller(unsigned long caller_addr
)
507 if (!preempt_trace() && irq_trace())
508 start_critical_timing(CALLER_ADDR0
, caller_addr
);
510 EXPORT_SYMBOL(trace_hardirqs_off_caller
);
512 #endif /* CONFIG_PROVE_LOCKING */
513 #endif /* CONFIG_IRQSOFF_TRACER */
515 #ifdef CONFIG_PREEMPT_TRACER
516 void trace_preempt_on(unsigned long a0
, unsigned long a1
)
518 if (preempt_trace() && !irq_trace())
519 stop_critical_timing(a0
, a1
);
522 void trace_preempt_off(unsigned long a0
, unsigned long a1
)
524 if (preempt_trace() && !irq_trace())
525 start_critical_timing(a0
, a1
);
527 #endif /* CONFIG_PREEMPT_TRACER */
529 #ifdef CONFIG_FUNCTION_TRACER
530 static bool function_enabled
;
532 static int register_irqsoff_function(struct trace_array
*tr
, int graph
, int set
)
536 /* 'set' is set if TRACE_ITER_FUNCTION is about to be set */
537 if (function_enabled
|| (!set
&& !(tr
->trace_flags
& TRACE_ITER_FUNCTION
)))
541 ret
= register_ftrace_graph(&irqsoff_graph_return
,
542 &irqsoff_graph_entry
);
544 ret
= register_ftrace_function(tr
->ops
);
547 function_enabled
= true;
552 static void unregister_irqsoff_function(struct trace_array
*tr
, int graph
)
554 if (!function_enabled
)
558 unregister_ftrace_graph();
560 unregister_ftrace_function(tr
->ops
);
562 function_enabled
= false;
565 static int irqsoff_function_set(struct trace_array
*tr
, u32 mask
, int set
)
567 if (!(mask
& TRACE_ITER_FUNCTION
))
571 register_irqsoff_function(tr
, is_graph(tr
), 1);
573 unregister_irqsoff_function(tr
, is_graph(tr
));
577 static int register_irqsoff_function(struct trace_array
*tr
, int graph
, int set
)
581 static void unregister_irqsoff_function(struct trace_array
*tr
, int graph
) { }
582 static inline int irqsoff_function_set(struct trace_array
*tr
, u32 mask
, int set
)
586 #endif /* CONFIG_FUNCTION_TRACER */
588 static int irqsoff_flag_changed(struct trace_array
*tr
, u32 mask
, int set
)
590 struct tracer
*tracer
= tr
->current_trace
;
592 if (irqsoff_function_set(tr
, mask
, set
))
595 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
596 if (mask
& TRACE_ITER_DISPLAY_GRAPH
)
597 return irqsoff_display_graph(tr
, set
);
600 return trace_keep_overwrite(tracer
, mask
, set
);
603 static int start_irqsoff_tracer(struct trace_array
*tr
, int graph
)
607 ret
= register_irqsoff_function(tr
, graph
, 0);
609 if (!ret
&& tracing_is_enabled())
617 static void stop_irqsoff_tracer(struct trace_array
*tr
, int graph
)
621 unregister_irqsoff_function(tr
, graph
);
624 static bool irqsoff_busy
;
626 static int __irqsoff_tracer_init(struct trace_array
*tr
)
631 save_flags
= tr
->trace_flags
;
633 /* non overwrite screws up the latency tracers */
634 set_tracer_flag(tr
, TRACE_ITER_OVERWRITE
, 1);
635 set_tracer_flag(tr
, TRACE_ITER_LATENCY_FMT
, 1);
639 /* make sure that the tracer is visible */
642 ftrace_init_array_ops(tr
, irqsoff_tracer_call
);
644 /* Only toplevel instance supports graph tracing */
645 if (start_irqsoff_tracer(tr
, (tr
->flags
& TRACE_ARRAY_FL_GLOBAL
&&
647 printk(KERN_ERR
"failed to start irqsoff tracer\n");
653 static void irqsoff_tracer_reset(struct trace_array
*tr
)
655 int lat_flag
= save_flags
& TRACE_ITER_LATENCY_FMT
;
656 int overwrite_flag
= save_flags
& TRACE_ITER_OVERWRITE
;
658 stop_irqsoff_tracer(tr
, is_graph(tr
));
660 set_tracer_flag(tr
, TRACE_ITER_LATENCY_FMT
, lat_flag
);
661 set_tracer_flag(tr
, TRACE_ITER_OVERWRITE
, overwrite_flag
);
662 ftrace_reset_array_ops(tr
);
664 irqsoff_busy
= false;
667 static void irqsoff_tracer_start(struct trace_array
*tr
)
672 static void irqsoff_tracer_stop(struct trace_array
*tr
)
677 #ifdef CONFIG_IRQSOFF_TRACER
678 static int irqsoff_tracer_init(struct trace_array
*tr
)
680 trace_type
= TRACER_IRQS_OFF
;
682 return __irqsoff_tracer_init(tr
);
684 static struct tracer irqsoff_tracer __read_mostly
=
687 .init
= irqsoff_tracer_init
,
688 .reset
= irqsoff_tracer_reset
,
689 .start
= irqsoff_tracer_start
,
690 .stop
= irqsoff_tracer_stop
,
692 .print_header
= irqsoff_print_header
,
693 .print_line
= irqsoff_print_line
,
694 .flag_changed
= irqsoff_flag_changed
,
695 #ifdef CONFIG_FTRACE_SELFTEST
696 .selftest
= trace_selftest_startup_irqsoff
,
698 .open
= irqsoff_trace_open
,
699 .close
= irqsoff_trace_close
,
700 .allow_instances
= true,
703 # define register_irqsoff(trace) register_tracer(&trace)
705 # define register_irqsoff(trace) do { } while (0)
708 #ifdef CONFIG_PREEMPT_TRACER
709 static int preemptoff_tracer_init(struct trace_array
*tr
)
711 trace_type
= TRACER_PREEMPT_OFF
;
713 return __irqsoff_tracer_init(tr
);
716 static struct tracer preemptoff_tracer __read_mostly
=
718 .name
= "preemptoff",
719 .init
= preemptoff_tracer_init
,
720 .reset
= irqsoff_tracer_reset
,
721 .start
= irqsoff_tracer_start
,
722 .stop
= irqsoff_tracer_stop
,
724 .print_header
= irqsoff_print_header
,
725 .print_line
= irqsoff_print_line
,
726 .flag_changed
= irqsoff_flag_changed
,
727 #ifdef CONFIG_FTRACE_SELFTEST
728 .selftest
= trace_selftest_startup_preemptoff
,
730 .open
= irqsoff_trace_open
,
731 .close
= irqsoff_trace_close
,
732 .allow_instances
= true,
735 # define register_preemptoff(trace) register_tracer(&trace)
737 # define register_preemptoff(trace) do { } while (0)
740 #if defined(CONFIG_IRQSOFF_TRACER) && \
741 defined(CONFIG_PREEMPT_TRACER)
743 static int preemptirqsoff_tracer_init(struct trace_array
*tr
)
745 trace_type
= TRACER_IRQS_OFF
| TRACER_PREEMPT_OFF
;
747 return __irqsoff_tracer_init(tr
);
750 static struct tracer preemptirqsoff_tracer __read_mostly
=
752 .name
= "preemptirqsoff",
753 .init
= preemptirqsoff_tracer_init
,
754 .reset
= irqsoff_tracer_reset
,
755 .start
= irqsoff_tracer_start
,
756 .stop
= irqsoff_tracer_stop
,
758 .print_header
= irqsoff_print_header
,
759 .print_line
= irqsoff_print_line
,
760 .flag_changed
= irqsoff_flag_changed
,
761 #ifdef CONFIG_FTRACE_SELFTEST
762 .selftest
= trace_selftest_startup_preemptirqsoff
,
764 .open
= irqsoff_trace_open
,
765 .close
= irqsoff_trace_close
,
766 .allow_instances
= true,
770 # define register_preemptirqsoff(trace) register_tracer(&trace)
772 # define register_preemptirqsoff(trace) do { } while (0)
775 __init
static int init_irqsoff_tracer(void)
777 register_irqsoff(irqsoff_tracer
);
778 register_preemptoff(preemptoff_tracer
);
779 register_preemptirqsoff(preemptirqsoff_tracer
);
783 core_initcall(init_irqsoff_tracer
);