2 * trace irqs off critical timings
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, u64 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,
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);