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 ftrace_graph_addr_finish(trace);
209 if (!func_prolog_dec(tr, &data, &flags))
212 pc = preempt_count();
213 __trace_graph_return(tr, trace, flags, pc);
214 atomic_dec(&data->disabled);
217 static void irqsoff_trace_open(struct trace_iterator *iter)
219 if (is_graph(iter->tr))
220 graph_trace_open(iter);
224 static void irqsoff_trace_close(struct trace_iterator *iter)
227 graph_trace_close(iter);
230 #define GRAPH_TRACER_FLAGS (TRACE_GRAPH_PRINT_CPU | \
231 TRACE_GRAPH_PRINT_PROC | \
232 TRACE_GRAPH_PRINT_ABS_TIME | \
233 TRACE_GRAPH_PRINT_DURATION)
235 static enum print_line_t irqsoff_print_line(struct trace_iterator *iter)
238 * In graph mode call the graph tracer output function,
239 * otherwise go with the TRACE_FN event handler
241 if (is_graph(iter->tr))
242 return print_graph_function_flags(iter, GRAPH_TRACER_FLAGS);
244 return TRACE_TYPE_UNHANDLED;
247 static void irqsoff_print_header(struct seq_file *s)
249 struct trace_array *tr = irqsoff_trace;
252 print_graph_headers_flags(s, GRAPH_TRACER_FLAGS);
254 trace_default_header(s);
258 __trace_function(struct trace_array *tr,
259 unsigned long ip, unsigned long parent_ip,
260 unsigned long flags, int pc)
263 trace_graph_function(tr, ip, parent_ip, flags, pc);
265 trace_function(tr, ip, parent_ip, flags, pc);
269 #define __trace_function trace_function
271 #ifdef CONFIG_FUNCTION_TRACER
272 static int irqsoff_graph_entry(struct ftrace_graph_ent *trace)
278 static enum print_line_t irqsoff_print_line(struct trace_iterator *iter)
280 return TRACE_TYPE_UNHANDLED;
283 static void irqsoff_trace_open(struct trace_iterator *iter) { }
284 static void irqsoff_trace_close(struct trace_iterator *iter) { }
286 #ifdef CONFIG_FUNCTION_TRACER
287 static void irqsoff_graph_return(struct ftrace_graph_ret *trace) { }
288 static void irqsoff_print_header(struct seq_file *s)
290 trace_default_header(s);
293 static void irqsoff_print_header(struct seq_file *s)
295 trace_latency_header(s);
297 #endif /* CONFIG_FUNCTION_TRACER */
298 #endif /* CONFIG_FUNCTION_GRAPH_TRACER */
301 * Should this new latency be reported/recorded?
303 static bool report_latency(struct trace_array *tr, u64 delta)
305 if (tracing_thresh) {
306 if (delta < tracing_thresh)
309 if (delta <= tr->max_latency)
316 check_critical_timing(struct trace_array *tr,
317 struct trace_array_cpu *data,
318 unsigned long parent_ip,
325 T0 = data->preempt_timestamp;
326 T1 = ftrace_now(cpu);
329 local_save_flags(flags);
331 pc = preempt_count();
333 if (!report_latency(tr, delta))
336 raw_spin_lock_irqsave(&max_trace_lock, flags);
338 /* check if we are still the max latency */
339 if (!report_latency(tr, delta))
342 __trace_function(tr, CALLER_ADDR0, parent_ip, flags, pc);
343 /* Skip 5 functions to get to the irq/preempt enable function */
344 __trace_stack(tr, flags, 5, pc);
346 if (data->critical_sequence != max_sequence)
349 data->critical_end = parent_ip;
351 if (likely(!is_tracing_stopped())) {
352 tr->max_latency = delta;
353 update_max_tr_single(tr, current, cpu);
359 raw_spin_unlock_irqrestore(&max_trace_lock, flags);
362 data->critical_sequence = max_sequence;
363 data->preempt_timestamp = ftrace_now(cpu);
364 __trace_function(tr, CALLER_ADDR0, parent_ip, flags, pc);
368 start_critical_timing(unsigned long ip, unsigned long parent_ip)
371 struct trace_array *tr = irqsoff_trace;
372 struct trace_array_cpu *data;
375 if (!tracer_enabled || !tracing_is_enabled())
378 cpu = raw_smp_processor_id();
380 if (per_cpu(tracing_cpu, cpu))
383 data = per_cpu_ptr(tr->trace_buffer.data, cpu);
385 if (unlikely(!data) || atomic_read(&data->disabled))
388 atomic_inc(&data->disabled);
390 data->critical_sequence = max_sequence;
391 data->preempt_timestamp = ftrace_now(cpu);
392 data->critical_start = parent_ip ? : ip;
394 local_save_flags(flags);
396 __trace_function(tr, ip, parent_ip, flags, preempt_count());
398 per_cpu(tracing_cpu, cpu) = 1;
400 atomic_dec(&data->disabled);
404 stop_critical_timing(unsigned long ip, unsigned long parent_ip)
407 struct trace_array *tr = irqsoff_trace;
408 struct trace_array_cpu *data;
411 cpu = raw_smp_processor_id();
412 /* Always clear the tracing cpu on stopping the trace */
413 if (unlikely(per_cpu(tracing_cpu, cpu)))
414 per_cpu(tracing_cpu, cpu) = 0;
418 if (!tracer_enabled || !tracing_is_enabled())
421 data = per_cpu_ptr(tr->trace_buffer.data, cpu);
423 if (unlikely(!data) ||
424 !data->critical_start || atomic_read(&data->disabled))
427 atomic_inc(&data->disabled);
429 local_save_flags(flags);
430 __trace_function(tr, ip, parent_ip, flags, preempt_count());
431 check_critical_timing(tr, data, parent_ip ? : ip, cpu);
432 data->critical_start = 0;
433 atomic_dec(&data->disabled);
436 /* start and stop critical timings used to for stoppage (in idle) */
437 void start_critical_timings(void)
439 if (preempt_trace() || irq_trace())
440 start_critical_timing(CALLER_ADDR0, CALLER_ADDR1);
442 EXPORT_SYMBOL_GPL(start_critical_timings);
444 void stop_critical_timings(void)
446 if (preempt_trace() || irq_trace())
447 stop_critical_timing(CALLER_ADDR0, CALLER_ADDR1);
449 EXPORT_SYMBOL_GPL(stop_critical_timings);
451 #ifdef CONFIG_IRQSOFF_TRACER
452 #ifdef CONFIG_PROVE_LOCKING
453 void time_hardirqs_on(unsigned long a0, unsigned long a1)
455 if (!preempt_trace() && irq_trace())
456 stop_critical_timing(a0, a1);
459 void time_hardirqs_off(unsigned long a0, unsigned long a1)
461 if (!preempt_trace() && irq_trace())
462 start_critical_timing(a0, a1);
465 #else /* !CONFIG_PROVE_LOCKING */
471 void trace_softirqs_on(unsigned long ip)
475 void trace_softirqs_off(unsigned long ip)
479 inline void print_irqtrace_events(struct task_struct *curr)
484 * We are only interested in hardirq on/off events:
486 void trace_hardirqs_on(void)
488 if (!preempt_trace() && irq_trace())
489 stop_critical_timing(CALLER_ADDR0, CALLER_ADDR1);
491 EXPORT_SYMBOL(trace_hardirqs_on);
493 void trace_hardirqs_off(void)
495 if (!preempt_trace() && irq_trace())
496 start_critical_timing(CALLER_ADDR0, CALLER_ADDR1);
498 EXPORT_SYMBOL(trace_hardirqs_off);
500 __visible void trace_hardirqs_on_caller(unsigned long caller_addr)
502 if (!preempt_trace() && irq_trace())
503 stop_critical_timing(CALLER_ADDR0, caller_addr);
505 EXPORT_SYMBOL(trace_hardirqs_on_caller);
507 __visible void trace_hardirqs_off_caller(unsigned long caller_addr)
509 if (!preempt_trace() && irq_trace())
510 start_critical_timing(CALLER_ADDR0, caller_addr);
512 EXPORT_SYMBOL(trace_hardirqs_off_caller);
514 #endif /* CONFIG_PROVE_LOCKING */
515 #endif /* CONFIG_IRQSOFF_TRACER */
517 #ifdef CONFIG_PREEMPT_TRACER
518 void trace_preempt_on(unsigned long a0, unsigned long a1)
520 if (preempt_trace() && !irq_trace())
521 stop_critical_timing(a0, a1);
524 void trace_preempt_off(unsigned long a0, unsigned long a1)
526 if (preempt_trace() && !irq_trace())
527 start_critical_timing(a0, a1);
529 #endif /* CONFIG_PREEMPT_TRACER */
531 #ifdef CONFIG_FUNCTION_TRACER
532 static bool function_enabled;
534 static int register_irqsoff_function(struct trace_array *tr, int graph, int set)
538 /* 'set' is set if TRACE_ITER_FUNCTION is about to be set */
539 if (function_enabled || (!set && !(tr->trace_flags & TRACE_ITER_FUNCTION)))
543 ret = register_ftrace_graph(&irqsoff_graph_return,
544 &irqsoff_graph_entry);
546 ret = register_ftrace_function(tr->ops);
549 function_enabled = true;
554 static void unregister_irqsoff_function(struct trace_array *tr, int graph)
556 if (!function_enabled)
560 unregister_ftrace_graph();
562 unregister_ftrace_function(tr->ops);
564 function_enabled = false;
567 static int irqsoff_function_set(struct trace_array *tr, u32 mask, int set)
569 if (!(mask & TRACE_ITER_FUNCTION))
573 register_irqsoff_function(tr, is_graph(tr), 1);
575 unregister_irqsoff_function(tr, is_graph(tr));
579 static int register_irqsoff_function(struct trace_array *tr, int graph, int set)
583 static void unregister_irqsoff_function(struct trace_array *tr, int graph) { }
584 static inline int irqsoff_function_set(struct trace_array *tr, u32 mask, int set)
588 #endif /* CONFIG_FUNCTION_TRACER */
590 static int irqsoff_flag_changed(struct trace_array *tr, u32 mask, int set)
592 struct tracer *tracer = tr->current_trace;
594 if (irqsoff_function_set(tr, mask, set))
597 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
598 if (mask & TRACE_ITER_DISPLAY_GRAPH)
599 return irqsoff_display_graph(tr, set);
602 return trace_keep_overwrite(tracer, mask, set);
605 static int start_irqsoff_tracer(struct trace_array *tr, int graph)
609 ret = register_irqsoff_function(tr, graph, 0);
611 if (!ret && tracing_is_enabled())
619 static void stop_irqsoff_tracer(struct trace_array *tr, int graph)
623 unregister_irqsoff_function(tr, graph);
626 static bool irqsoff_busy;
628 static int __irqsoff_tracer_init(struct trace_array *tr)
633 save_flags = tr->trace_flags;
635 /* non overwrite screws up the latency tracers */
636 set_tracer_flag(tr, TRACE_ITER_OVERWRITE, 1);
637 set_tracer_flag(tr, TRACE_ITER_LATENCY_FMT, 1);
641 /* make sure that the tracer is visible */
644 ftrace_init_array_ops(tr, irqsoff_tracer_call);
646 /* Only toplevel instance supports graph tracing */
647 if (start_irqsoff_tracer(tr, (tr->flags & TRACE_ARRAY_FL_GLOBAL &&
649 printk(KERN_ERR "failed to start irqsoff tracer\n");
655 static void irqsoff_tracer_reset(struct trace_array *tr)
657 int lat_flag = save_flags & TRACE_ITER_LATENCY_FMT;
658 int overwrite_flag = save_flags & TRACE_ITER_OVERWRITE;
660 stop_irqsoff_tracer(tr, is_graph(tr));
662 set_tracer_flag(tr, TRACE_ITER_LATENCY_FMT, lat_flag);
663 set_tracer_flag(tr, TRACE_ITER_OVERWRITE, overwrite_flag);
664 ftrace_reset_array_ops(tr);
666 irqsoff_busy = false;
669 static void irqsoff_tracer_start(struct trace_array *tr)
674 static void irqsoff_tracer_stop(struct trace_array *tr)
679 #ifdef CONFIG_IRQSOFF_TRACER
680 static int irqsoff_tracer_init(struct trace_array *tr)
682 trace_type = TRACER_IRQS_OFF;
684 return __irqsoff_tracer_init(tr);
686 static struct tracer irqsoff_tracer __read_mostly =
689 .init = irqsoff_tracer_init,
690 .reset = irqsoff_tracer_reset,
691 .start = irqsoff_tracer_start,
692 .stop = irqsoff_tracer_stop,
694 .print_header = irqsoff_print_header,
695 .print_line = irqsoff_print_line,
696 .flag_changed = irqsoff_flag_changed,
697 #ifdef CONFIG_FTRACE_SELFTEST
698 .selftest = trace_selftest_startup_irqsoff,
700 .open = irqsoff_trace_open,
701 .close = irqsoff_trace_close,
702 .allow_instances = true,
705 # define register_irqsoff(trace) register_tracer(&trace)
707 # define register_irqsoff(trace) do { } while (0)
710 #ifdef CONFIG_PREEMPT_TRACER
711 static int preemptoff_tracer_init(struct trace_array *tr)
713 trace_type = TRACER_PREEMPT_OFF;
715 return __irqsoff_tracer_init(tr);
718 static struct tracer preemptoff_tracer __read_mostly =
720 .name = "preemptoff",
721 .init = preemptoff_tracer_init,
722 .reset = irqsoff_tracer_reset,
723 .start = irqsoff_tracer_start,
724 .stop = irqsoff_tracer_stop,
726 .print_header = irqsoff_print_header,
727 .print_line = irqsoff_print_line,
728 .flag_changed = irqsoff_flag_changed,
729 #ifdef CONFIG_FTRACE_SELFTEST
730 .selftest = trace_selftest_startup_preemptoff,
732 .open = irqsoff_trace_open,
733 .close = irqsoff_trace_close,
734 .allow_instances = true,
737 # define register_preemptoff(trace) register_tracer(&trace)
739 # define register_preemptoff(trace) do { } while (0)
742 #if defined(CONFIG_IRQSOFF_TRACER) && \
743 defined(CONFIG_PREEMPT_TRACER)
745 static int preemptirqsoff_tracer_init(struct trace_array *tr)
747 trace_type = TRACER_IRQS_OFF | TRACER_PREEMPT_OFF;
749 return __irqsoff_tracer_init(tr);
752 static struct tracer preemptirqsoff_tracer __read_mostly =
754 .name = "preemptirqsoff",
755 .init = preemptirqsoff_tracer_init,
756 .reset = irqsoff_tracer_reset,
757 .start = irqsoff_tracer_start,
758 .stop = irqsoff_tracer_stop,
760 .print_header = irqsoff_print_header,
761 .print_line = irqsoff_print_line,
762 .flag_changed = irqsoff_flag_changed,
763 #ifdef CONFIG_FTRACE_SELFTEST
764 .selftest = trace_selftest_startup_preemptirqsoff,
766 .open = irqsoff_trace_open,
767 .close = irqsoff_trace_close,
768 .allow_instances = true,
772 # define register_preemptirqsoff(trace) register_tracer(&trace)
774 # define register_preemptirqsoff(trace) do { } while (0)
777 __init static int init_irqsoff_tracer(void)
779 register_irqsoff(irqsoff_tracer);
780 register_preemptoff(preemptoff_tracer);
781 register_preemptirqsoff(preemptirqsoff_tracer);
785 core_initcall(init_irqsoff_tracer);