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>
16 #include <trace/events/hist.h>
20 static struct trace_array *irqsoff_trace __read_mostly;
21 static int tracer_enabled __read_mostly;
23 static DEFINE_PER_CPU(int, tracing_cpu);
25 static DEFINE_RAW_SPINLOCK(max_trace_lock);
28 TRACER_IRQS_OFF = (1 << 1),
29 TRACER_PREEMPT_OFF = (1 << 2),
32 static int trace_type __read_mostly;
34 static int save_flags;
36 static void stop_irqsoff_tracer(struct trace_array *tr, int graph);
37 static int start_irqsoff_tracer(struct trace_array *tr, int graph);
39 #ifdef CONFIG_PREEMPT_TRACER
43 return ((trace_type & TRACER_PREEMPT_OFF) && preempt_count());
46 # define preempt_trace() (0)
49 #ifdef CONFIG_IRQSOFF_TRACER
53 return ((trace_type & TRACER_IRQS_OFF) &&
57 # define irq_trace() (0)
60 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
61 static int irqsoff_display_graph(struct trace_array *tr, int set);
62 # define is_graph(tr) ((tr)->trace_flags & TRACE_ITER_DISPLAY_GRAPH)
64 static inline int irqsoff_display_graph(struct trace_array *tr, int set)
68 # define is_graph(tr) false
72 * Sequence count - we record it when starting a measurement and
73 * skip the latency if the sequence has changed - some other section
74 * did a maximum and could disturb our measurement with serial console
75 * printouts, etc. Truly coinciding maximum latencies should be rare
76 * and what happens together happens separately as well, so this doesn't
77 * decrease the validity of the maximum found:
79 static __cacheline_aligned_in_smp unsigned long max_sequence;
81 #ifdef CONFIG_FUNCTION_TRACER
83 * Prologue for the preempt and irqs off function tracers.
85 * Returns 1 if it is OK to continue, and data->disabled is
87 * 0 if the trace is to be ignored, and data->disabled
90 * Note, this function is also used outside this ifdef but
91 * inside the #ifdef of the function graph tracer below.
92 * This is OK, since the function graph tracer is
93 * dependent on the function tracer.
95 static int func_prolog_dec(struct trace_array *tr,
96 struct trace_array_cpu **data,
103 * Does not matter if we preempt. We test the flags
104 * afterward, to see if irqs are disabled or not.
105 * If we preempt and get a false positive, the flags
108 cpu = raw_smp_processor_id();
109 if (likely(!per_cpu(tracing_cpu, cpu)))
112 local_save_flags(*flags);
114 * Slight chance to get a false positive on tracing_cpu,
115 * although I'm starting to think there isn't a chance.
116 * Leave this for now just to be paranoid.
118 if (!irqs_disabled_flags(*flags) && !preempt_count())
121 *data = per_cpu_ptr(tr->trace_buffer.data, cpu);
122 disabled = atomic_inc_return(&(*data)->disabled);
124 if (likely(disabled == 1))
127 atomic_dec(&(*data)->disabled);
133 * irqsoff uses its own tracer function to keep the overhead down:
136 irqsoff_tracer_call(unsigned long ip, unsigned long parent_ip,
137 struct ftrace_ops *op, struct pt_regs *pt_regs)
139 struct trace_array *tr = irqsoff_trace;
140 struct trace_array_cpu *data;
143 if (!func_prolog_dec(tr, &data, &flags))
146 trace_function(tr, ip, parent_ip, flags, preempt_count());
148 atomic_dec(&data->disabled);
150 #endif /* CONFIG_FUNCTION_TRACER */
152 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
153 static int irqsoff_display_graph(struct trace_array *tr, int set)
157 if (!(is_graph(tr) ^ set))
160 stop_irqsoff_tracer(irqsoff_trace, !set);
162 for_each_possible_cpu(cpu)
163 per_cpu(tracing_cpu, cpu) = 0;
166 tracing_reset_online_cpus(&irqsoff_trace->trace_buffer);
168 return start_irqsoff_tracer(irqsoff_trace, set);
171 static int irqsoff_graph_entry(struct ftrace_graph_ent *trace)
173 struct trace_array *tr = irqsoff_trace;
174 struct trace_array_cpu *data;
179 if (!func_prolog_dec(tr, &data, &flags))
182 pc = preempt_count();
183 ret = __trace_graph_entry(tr, trace, flags, pc);
184 atomic_dec(&data->disabled);
189 static void irqsoff_graph_return(struct ftrace_graph_ret *trace)
191 struct trace_array *tr = irqsoff_trace;
192 struct trace_array_cpu *data;
196 if (!func_prolog_dec(tr, &data, &flags))
199 pc = preempt_count();
200 __trace_graph_return(tr, trace, flags, pc);
201 atomic_dec(&data->disabled);
204 static void irqsoff_trace_open(struct trace_iterator *iter)
206 if (is_graph(iter->tr))
207 graph_trace_open(iter);
211 static void irqsoff_trace_close(struct trace_iterator *iter)
214 graph_trace_close(iter);
217 #define GRAPH_TRACER_FLAGS (TRACE_GRAPH_PRINT_CPU | \
218 TRACE_GRAPH_PRINT_PROC | \
219 TRACE_GRAPH_PRINT_ABS_TIME | \
220 TRACE_GRAPH_PRINT_DURATION)
222 static enum print_line_t irqsoff_print_line(struct trace_iterator *iter)
225 * In graph mode call the graph tracer output function,
226 * otherwise go with the TRACE_FN event handler
228 if (is_graph(iter->tr))
229 return print_graph_function_flags(iter, GRAPH_TRACER_FLAGS);
231 return TRACE_TYPE_UNHANDLED;
234 static void irqsoff_print_header(struct seq_file *s)
236 struct trace_array *tr = irqsoff_trace;
239 print_graph_headers_flags(s, GRAPH_TRACER_FLAGS);
241 trace_default_header(s);
245 __trace_function(struct trace_array *tr,
246 unsigned long ip, unsigned long parent_ip,
247 unsigned long flags, int pc)
250 trace_graph_function(tr, ip, parent_ip, flags, pc);
252 trace_function(tr, ip, parent_ip, flags, pc);
256 #define __trace_function trace_function
258 #ifdef CONFIG_FUNCTION_TRACER
259 static int irqsoff_graph_entry(struct ftrace_graph_ent *trace)
265 static enum print_line_t irqsoff_print_line(struct trace_iterator *iter)
267 return TRACE_TYPE_UNHANDLED;
270 static void irqsoff_trace_open(struct trace_iterator *iter) { }
271 static void irqsoff_trace_close(struct trace_iterator *iter) { }
273 #ifdef CONFIG_FUNCTION_TRACER
274 static void irqsoff_graph_return(struct ftrace_graph_ret *trace) { }
275 static void irqsoff_print_header(struct seq_file *s)
277 trace_default_header(s);
280 static void irqsoff_print_header(struct seq_file *s)
282 trace_latency_header(s);
284 #endif /* CONFIG_FUNCTION_TRACER */
285 #endif /* CONFIG_FUNCTION_GRAPH_TRACER */
288 * Should this new latency be reported/recorded?
290 static bool report_latency(struct trace_array *tr, cycle_t delta)
292 if (tracing_thresh) {
293 if (delta < tracing_thresh)
296 if (delta <= tr->max_latency)
303 check_critical_timing(struct trace_array *tr,
304 struct trace_array_cpu *data,
305 unsigned long parent_ip,
308 cycle_t T0, T1, delta;
312 T0 = data->preempt_timestamp;
313 T1 = ftrace_now(cpu);
316 local_save_flags(flags);
318 pc = preempt_count();
320 if (!report_latency(tr, delta))
323 raw_spin_lock_irqsave(&max_trace_lock, flags);
325 /* check if we are still the max latency */
326 if (!report_latency(tr, delta))
329 __trace_function(tr, CALLER_ADDR0, parent_ip, flags, pc);
330 /* Skip 5 functions to get to the irq/preempt enable function */
331 __trace_stack(tr, flags, 5, pc);
333 if (data->critical_sequence != max_sequence)
336 data->critical_end = parent_ip;
338 if (likely(!is_tracing_stopped())) {
339 tr->max_latency = delta;
340 update_max_tr_single(tr, current, cpu);
346 raw_spin_unlock_irqrestore(&max_trace_lock, flags);
349 data->critical_sequence = max_sequence;
350 data->preempt_timestamp = ftrace_now(cpu);
351 __trace_function(tr, CALLER_ADDR0, parent_ip, flags, pc);
355 start_critical_timing(unsigned long ip, unsigned long parent_ip)
358 struct trace_array *tr = irqsoff_trace;
359 struct trace_array_cpu *data;
362 if (!tracer_enabled || !tracing_is_enabled())
365 cpu = raw_smp_processor_id();
367 if (per_cpu(tracing_cpu, cpu))
370 data = per_cpu_ptr(tr->trace_buffer.data, cpu);
372 if (unlikely(!data) || atomic_read(&data->disabled))
375 atomic_inc(&data->disabled);
377 data->critical_sequence = max_sequence;
378 data->preempt_timestamp = ftrace_now(cpu);
379 data->critical_start = parent_ip ? : ip;
381 local_save_flags(flags);
383 __trace_function(tr, ip, parent_ip, flags, preempt_count());
385 per_cpu(tracing_cpu, cpu) = 1;
387 atomic_dec(&data->disabled);
391 stop_critical_timing(unsigned long ip, unsigned long parent_ip)
394 struct trace_array *tr = irqsoff_trace;
395 struct trace_array_cpu *data;
398 cpu = raw_smp_processor_id();
399 /* Always clear the tracing cpu on stopping the trace */
400 if (unlikely(per_cpu(tracing_cpu, cpu)))
401 per_cpu(tracing_cpu, cpu) = 0;
405 if (!tracer_enabled || !tracing_is_enabled())
408 data = per_cpu_ptr(tr->trace_buffer.data, cpu);
410 if (unlikely(!data) ||
411 !data->critical_start || atomic_read(&data->disabled))
414 atomic_inc(&data->disabled);
416 local_save_flags(flags);
417 __trace_function(tr, ip, parent_ip, flags, preempt_count());
418 check_critical_timing(tr, data, parent_ip ? : ip, cpu);
419 data->critical_start = 0;
420 atomic_dec(&data->disabled);
423 /* start and stop critical timings used to for stoppage (in idle) */
424 void start_critical_timings(void)
426 if (preempt_trace() || irq_trace())
427 start_critical_timing(CALLER_ADDR0, CALLER_ADDR1);
428 trace_preemptirqsoff_hist_rcuidle(TRACE_START, 1);
430 EXPORT_SYMBOL_GPL(start_critical_timings);
432 void stop_critical_timings(void)
434 trace_preemptirqsoff_hist_rcuidle(TRACE_STOP, 0);
435 if (preempt_trace() || irq_trace())
436 stop_critical_timing(CALLER_ADDR0, CALLER_ADDR1);
438 EXPORT_SYMBOL_GPL(stop_critical_timings);
440 #ifdef CONFIG_IRQSOFF_TRACER
441 #ifdef CONFIG_PROVE_LOCKING
442 void time_hardirqs_on(unsigned long a0, unsigned long a1)
444 trace_preemptirqsoff_hist_rcuidle(IRQS_ON, 0);
445 if (!preempt_trace() && irq_trace())
446 stop_critical_timing(a0, a1);
449 void time_hardirqs_off(unsigned long a0, unsigned long a1)
451 if (!preempt_trace() && irq_trace())
452 start_critical_timing(a0, a1);
453 trace_preemptirqsoff_hist_rcuidle(IRQS_OFF, 1);
456 #else /* !CONFIG_PROVE_LOCKING */
462 void trace_softirqs_on(unsigned long ip)
466 void trace_softirqs_off(unsigned long ip)
470 inline void print_irqtrace_events(struct task_struct *curr)
475 * We are only interested in hardirq on/off events:
477 void trace_hardirqs_on(void)
479 trace_preemptirqsoff_hist(IRQS_ON, 0);
480 if (!preempt_trace() && irq_trace())
481 stop_critical_timing(CALLER_ADDR0, CALLER_ADDR1);
483 EXPORT_SYMBOL(trace_hardirqs_on);
485 void trace_hardirqs_off(void)
487 if (!preempt_trace() && irq_trace())
488 start_critical_timing(CALLER_ADDR0, CALLER_ADDR1);
489 trace_preemptirqsoff_hist(IRQS_OFF, 1);
491 EXPORT_SYMBOL(trace_hardirqs_off);
493 __visible void trace_hardirqs_on_caller(unsigned long caller_addr)
495 trace_preemptirqsoff_hist(IRQS_ON, 0);
496 if (!preempt_trace() && irq_trace())
497 stop_critical_timing(CALLER_ADDR0, caller_addr);
499 EXPORT_SYMBOL(trace_hardirqs_on_caller);
501 __visible void trace_hardirqs_off_caller(unsigned long caller_addr)
503 if (!preempt_trace() && irq_trace())
504 start_critical_timing(CALLER_ADDR0, caller_addr);
505 trace_preemptirqsoff_hist(IRQS_OFF, 1);
507 EXPORT_SYMBOL(trace_hardirqs_off_caller);
509 #endif /* CONFIG_PROVE_LOCKING */
510 #endif /* CONFIG_IRQSOFF_TRACER */
512 #ifdef CONFIG_PREEMPT_TRACER
513 void trace_preempt_on(unsigned long a0, unsigned long a1)
515 trace_preemptirqsoff_hist(PREEMPT_ON, 0);
516 if (preempt_trace() && !irq_trace())
517 stop_critical_timing(a0, a1);
520 void trace_preempt_off(unsigned long a0, unsigned long a1)
522 trace_preemptirqsoff_hist(PREEMPT_ON, 1);
523 if (preempt_trace() && !irq_trace())
524 start_critical_timing(a0, a1);
526 #endif /* CONFIG_PREEMPT_TRACER */
528 #ifdef CONFIG_FUNCTION_TRACER
529 static bool function_enabled;
531 static int register_irqsoff_function(struct trace_array *tr, int graph, int set)
535 /* 'set' is set if TRACE_ITER_FUNCTION is about to be set */
536 if (function_enabled || (!set && !(tr->trace_flags & TRACE_ITER_FUNCTION)))
540 ret = register_ftrace_graph(&irqsoff_graph_return,
541 &irqsoff_graph_entry);
543 ret = register_ftrace_function(tr->ops);
546 function_enabled = true;
551 static void unregister_irqsoff_function(struct trace_array *tr, int graph)
553 if (!function_enabled)
557 unregister_ftrace_graph();
559 unregister_ftrace_function(tr->ops);
561 function_enabled = false;
564 static int irqsoff_function_set(struct trace_array *tr, u32 mask, int set)
566 if (!(mask & TRACE_ITER_FUNCTION))
570 register_irqsoff_function(tr, is_graph(tr), 1);
572 unregister_irqsoff_function(tr, is_graph(tr));
576 static int register_irqsoff_function(struct trace_array *tr, int graph, int set)
580 static void unregister_irqsoff_function(struct trace_array *tr, int graph) { }
581 static inline int irqsoff_function_set(struct trace_array *tr, u32 mask, int set)
585 #endif /* CONFIG_FUNCTION_TRACER */
587 static int irqsoff_flag_changed(struct trace_array *tr, u32 mask, int set)
589 struct tracer *tracer = tr->current_trace;
591 if (irqsoff_function_set(tr, mask, set))
594 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
595 if (mask & TRACE_ITER_DISPLAY_GRAPH)
596 return irqsoff_display_graph(tr, set);
599 return trace_keep_overwrite(tracer, mask, set);
602 static int start_irqsoff_tracer(struct trace_array *tr, int graph)
606 ret = register_irqsoff_function(tr, graph, 0);
608 if (!ret && tracing_is_enabled())
616 static void stop_irqsoff_tracer(struct trace_array *tr, int graph)
620 unregister_irqsoff_function(tr, graph);
623 static bool irqsoff_busy;
625 static int __irqsoff_tracer_init(struct trace_array *tr)
630 save_flags = tr->trace_flags;
632 /* non overwrite screws up the latency tracers */
633 set_tracer_flag(tr, TRACE_ITER_OVERWRITE, 1);
634 set_tracer_flag(tr, TRACE_ITER_LATENCY_FMT, 1);
638 /* make sure that the tracer is visible */
640 tracing_reset_online_cpus(&tr->trace_buffer);
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);