1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * trace irqs off critical timings
4 *
5 * Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com>
6 * Copyright (C) 2008 Ingo Molnar <mingo@redhat.com>
7 *
8 * From code in the latency_tracer, that is:
9 *
10 * Copyright (C) 2004-2006 Ingo Molnar
11 * Copyright (C) 2004 Nadia Yvette Chambers
12 */
13 #include <linux/kallsyms.h>
14 #include <linux/uaccess.h>
15 #include <linux/module.h>
16 #include <linux/ftrace.h>
17 #include <linux/kprobes.h>
18
19 #include "trace.h"
20
21 #include <trace/events/preemptirq.h>
22
23 #if defined(CONFIG_IRQSOFF_TRACER) || defined(CONFIG_PREEMPT_TRACER)
24 static struct trace_array *irqsoff_trace __read_mostly;
25 static int tracer_enabled __read_mostly;
26
27 static DEFINE_PER_CPU(int, tracing_cpu);
28
29 static DEFINE_RAW_SPINLOCK(max_trace_lock);
30
31 enum {
32 TRACER_IRQS_OFF = (1 << 1),
33 TRACER_PREEMPT_OFF = (1 << 2),
34 };
35
36 static int trace_type __read_mostly;
37
38 static int save_flags;
39
40 static void stop_irqsoff_tracer(struct trace_array *tr, int graph);
41 static int start_irqsoff_tracer(struct trace_array *tr, int graph);
42
43 #ifdef CONFIG_PREEMPT_TRACER
44 static inline int
45 preempt_trace(int pc)
46 {
47 return ((trace_type & TRACER_PREEMPT_OFF) && pc);
48 }
49 #else
50 # define preempt_trace(pc) (0)
51 #endif
52
53 #ifdef CONFIG_IRQSOFF_TRACER
54 static inline int
55 irq_trace(void)
56 {
57 return ((trace_type & TRACER_IRQS_OFF) &&
58 irqs_disabled());
59 }
60 #else
61 # define irq_trace() (0)
62 #endif
63
64 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
65 static int irqsoff_display_graph(struct trace_array *tr, int set);
66 # define is_graph(tr) ((tr)->trace_flags & TRACE_ITER_DISPLAY_GRAPH)
67 #else
68 static inline int irqsoff_display_graph(struct trace_array *tr, int set)
69 {
70 return -EINVAL;
71 }
72 # define is_graph(tr) false
73 #endif
74
75 /*
76 * Sequence count - we record it when starting a measurement and
77 * skip the latency if the sequence has changed - some other section
78 * did a maximum and could disturb our measurement with serial console
79 * printouts, etc. Truly coinciding maximum latencies should be rare
80 * and what happens together happens separately as well, so this doesn't
81 * decrease the validity of the maximum found:
82 */
83 static __cacheline_aligned_in_smp unsigned long max_sequence;
84
85 #ifdef CONFIG_FUNCTION_TRACER
86 /*
87 * Prologue for the preempt and irqs off function tracers.
88 *
89 * Returns 1 if it is OK to continue, and data->disabled is
90 * incremented.
91 * 0 if the trace is to be ignored, and data->disabled
92 * is kept the same.
93 *
94 * Note, this function is also used outside this ifdef but
95 * inside the #ifdef of the function graph tracer below.
96 * This is OK, since the function graph tracer is
97 * dependent on the function tracer.
98 */
99 static int func_prolog_dec(struct trace_array *tr,
100 struct trace_array_cpu **data,
101 unsigned long *flags)
102 {
103 long disabled;
104 int cpu;
105
106 /*
107 * Does not matter if we preempt. We test the flags
108 * afterward, to see if irqs are disabled or not.
109 * If we preempt and get a false positive, the flags
110 * test will fail.
111 */
112 cpu = raw_smp_processor_id();
113 if (likely(!per_cpu(tracing_cpu, cpu)))
114 return 0;
115
116 local_save_flags(*flags);
117 /*
118 * Slight chance to get a false positive on tracing_cpu,
119 * although I'm starting to think there isn't a chance.
120 * Leave this for now just to be paranoid.
121 */
122 if (!irqs_disabled_flags(*flags) && !preempt_count())
123 return 0;
124
125 *data = per_cpu_ptr(tr->array_buffer.data, cpu);
126 disabled = atomic_inc_return(&(*data)->disabled);
127
128 if (likely(disabled == 1))
129 return 1;
130
131 atomic_dec(&(*data)->disabled);
132
133 return 0;
134 }
135
136 /*
137 * irqsoff uses its own tracer function to keep the overhead down:
138 */
139 static void
140 irqsoff_tracer_call(unsigned long ip, unsigned long parent_ip,
141 struct ftrace_ops *op, struct ftrace_regs *fregs)
142 {
143 struct trace_array *tr = irqsoff_trace;
144 struct trace_array_cpu *data;
145 unsigned long flags;
146 unsigned int trace_ctx;
147
148 if (!func_prolog_dec(tr, &data, &flags))
149 return;
150
151 trace_ctx = tracing_gen_ctx_flags(flags);
152
153 trace_function(tr, ip, parent_ip, trace_ctx);
154
155 atomic_dec(&data->disabled);
156 }
157 #endif /* CONFIG_FUNCTION_TRACER */
158
159 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
160 static int irqsoff_display_graph(struct trace_array *tr, int set)
161 {
162 int cpu;
163
164 if (!(is_graph(tr) ^ set))
165 return 0;
166
167 stop_irqsoff_tracer(irqsoff_trace, !set);
168
169 for_each_possible_cpu(cpu)
170 per_cpu(tracing_cpu, cpu) = 0;
171
172 tr->max_latency = 0;
173 tracing_reset_online_cpus(&irqsoff_trace->array_buffer);
174
175 return start_irqsoff_tracer(irqsoff_trace, set);
176 }
177
178 static int irqsoff_graph_entry(struct ftrace_graph_ent *trace,
179 struct fgraph_ops *gops)
180 {
181 struct trace_array *tr = irqsoff_trace;
182 struct trace_array_cpu *data;
183 unsigned long flags;
184 unsigned int trace_ctx;
185 int ret;
186
187 if (ftrace_graph_ignore_func(gops, trace))
188 return 0;
189 /*
190 * Do not trace a function if it's filtered by set_graph_notrace.
191 * Make the index of ret stack negative to indicate that it should
192 * ignore further functions. But it needs its own ret stack entry
193 * to recover the original index in order to continue tracing after
194 * returning from the function.
195 */
196 if (ftrace_graph_notrace_addr(trace->func))
197 return 1;
198
199 if (!func_prolog_dec(tr, &data, &flags))
200 return 0;
201
202 trace_ctx = tracing_gen_ctx_flags(flags);
203 ret = __trace_graph_entry(tr, trace, trace_ctx);
204 atomic_dec(&data->disabled);
205
206 return ret;
207 }
208
209 static void irqsoff_graph_return(struct ftrace_graph_ret *trace,
210 struct fgraph_ops *gops)
211 {
212 struct trace_array *tr = irqsoff_trace;
213 struct trace_array_cpu *data;
214 unsigned long flags;
215 unsigned int trace_ctx;
216
217 ftrace_graph_addr_finish(gops, trace);
218
219 if (!func_prolog_dec(tr, &data, &flags))
220 return;
221
222 trace_ctx = tracing_gen_ctx_flags(flags);
223 __trace_graph_return(tr, trace, trace_ctx);
224 atomic_dec(&data->disabled);
225 }
226
227 static struct fgraph_ops fgraph_ops = {
228 .entryfunc = &irqsoff_graph_entry,
229 .retfunc = &irqsoff_graph_return,
230 };
231
232 static void irqsoff_trace_open(struct trace_iterator *iter)
233 {
234 if (is_graph(iter->tr))
235 graph_trace_open(iter);
236 else
237 iter->private = NULL;
238 }
239
240 static void irqsoff_trace_close(struct trace_iterator *iter)
241 {
242 if (iter->private)
243 graph_trace_close(iter);
244 }
245
246 #define GRAPH_TRACER_FLAGS (TRACE_GRAPH_PRINT_CPU | \
247 TRACE_GRAPH_PRINT_PROC | \
248 TRACE_GRAPH_PRINT_REL_TIME | \
249 TRACE_GRAPH_PRINT_DURATION)
250
251 static enum print_line_t irqsoff_print_line(struct trace_iterator *iter)
252 {
253 /*
254 * In graph mode call the graph tracer output function,
255 * otherwise go with the TRACE_FN event handler
256 */
257 if (is_graph(iter->tr))
258 return print_graph_function_flags(iter, GRAPH_TRACER_FLAGS);
259
260 return TRACE_TYPE_UNHANDLED;
261 }
262
263 static void irqsoff_print_header(struct seq_file *s)
264 {
265 struct trace_array *tr = irqsoff_trace;
266
267 if (is_graph(tr))
268 print_graph_headers_flags(s, GRAPH_TRACER_FLAGS);
269 else
270 trace_default_header(s);
271 }
272
273 static void
274 __trace_function(struct trace_array *tr,
275 unsigned long ip, unsigned long parent_ip,
276 unsigned int trace_ctx)
277 {
278 if (is_graph(tr))
279 trace_graph_function(tr, ip, parent_ip, trace_ctx);
280 else
281 trace_function(tr, ip, parent_ip, trace_ctx);
282 }
283
284 #else
285 #define __trace_function trace_function
286
287 static enum print_line_t irqsoff_print_line(struct trace_iterator *iter)
288 {
289 return TRACE_TYPE_UNHANDLED;
290 }
291
292 static void irqsoff_trace_open(struct trace_iterator *iter) { }
293 static void irqsoff_trace_close(struct trace_iterator *iter) { }
294
295 #ifdef CONFIG_FUNCTION_TRACER
296 static void irqsoff_print_header(struct seq_file *s)
297 {
298 trace_default_header(s);
299 }
300 #else
301 static void irqsoff_print_header(struct seq_file *s)
302 {
303 trace_latency_header(s);
304 }
305 #endif /* CONFIG_FUNCTION_TRACER */
306 #endif /* CONFIG_FUNCTION_GRAPH_TRACER */
307
308 /*
309 * Should this new latency be reported/recorded?
310 */
311 static bool report_latency(struct trace_array *tr, u64 delta)
312 {
313 if (tracing_thresh) {
314 if (delta < tracing_thresh)
315 return false;
316 } else {
317 if (delta <= tr->max_latency)
318 return false;
319 }
320 return true;
321 }
322
323 static void
324 check_critical_timing(struct trace_array *tr,
325 struct trace_array_cpu *data,
326 unsigned long parent_ip,
327 int cpu)
328 {
329 u64 T0, T1, delta;
330 unsigned long flags;
331 unsigned int trace_ctx;
332
333 T0 = data->preempt_timestamp;
334 T1 = ftrace_now(cpu);
335 delta = T1-T0;
336
337 trace_ctx = tracing_gen_ctx();
338
339 if (!report_latency(tr, delta))
340 goto out;
341
342 raw_spin_lock_irqsave(&max_trace_lock, flags);
343
344 /* check if we are still the max latency */
345 if (!report_latency(tr, delta))
346 goto out_unlock;
347
348 __trace_function(tr, CALLER_ADDR0, parent_ip, trace_ctx);
349 /* Skip 5 functions to get to the irq/preempt enable function */
350 __trace_stack(tr, trace_ctx, 5);
351
352 if (data->critical_sequence != max_sequence)
353 goto out_unlock;
354
355 data->critical_end = parent_ip;
356
357 if (likely(!is_tracing_stopped())) {
358 tr->max_latency = delta;
359 update_max_tr_single(tr, current, cpu);
360 }
361
362 max_sequence++;
363
364 out_unlock:
365 raw_spin_unlock_irqrestore(&max_trace_lock, flags);
366
367 out:
368 data->critical_sequence = max_sequence;
369 data->preempt_timestamp = ftrace_now(cpu);
370 __trace_function(tr, CALLER_ADDR0, parent_ip, trace_ctx);
371 }
372
373 static nokprobe_inline void
374 start_critical_timing(unsigned long ip, unsigned long parent_ip)
375 {
376 int cpu;
377 struct trace_array *tr = irqsoff_trace;
378 struct trace_array_cpu *data;
379
380 if (!tracer_enabled || !tracing_is_enabled())
381 return;
382
383 cpu = raw_smp_processor_id();
384
385 if (per_cpu(tracing_cpu, cpu))
386 return;
387
388 data = per_cpu_ptr(tr->array_buffer.data, cpu);
389
390 if (unlikely(!data) || atomic_read(&data->disabled))
391 return;
392
393 atomic_inc(&data->disabled);
394
395 data->critical_sequence = max_sequence;
396 data->preempt_timestamp = ftrace_now(cpu);
397 data->critical_start = parent_ip ? : ip;
398
399 __trace_function(tr, ip, parent_ip, tracing_gen_ctx());
400
401 per_cpu(tracing_cpu, cpu) = 1;
402
403 atomic_dec(&data->disabled);
404 }
405
406 static nokprobe_inline void
407 stop_critical_timing(unsigned long ip, unsigned long parent_ip)
408 {
409 int cpu;
410 struct trace_array *tr = irqsoff_trace;
411 struct trace_array_cpu *data;
412 unsigned int trace_ctx;
413
414 cpu = raw_smp_processor_id();
415 /* Always clear the tracing cpu on stopping the trace */
416 if (unlikely(per_cpu(tracing_cpu, cpu)))
417 per_cpu(tracing_cpu, cpu) = 0;
418 else
419 return;
420
421 if (!tracer_enabled || !tracing_is_enabled())
422 return;
423
424 data = per_cpu_ptr(tr->array_buffer.data, cpu);
425
426 if (unlikely(!data) ||
427 !data->critical_start || atomic_read(&data->disabled))
428 return;
429
430 atomic_inc(&data->disabled);
431
432 trace_ctx = tracing_gen_ctx();
433 __trace_function(tr, ip, parent_ip, trace_ctx);
434 check_critical_timing(tr, data, parent_ip ? : ip, cpu);
435 data->critical_start = 0;
436 atomic_dec(&data->disabled);
437 }
438
439 /* start and stop critical timings used to for stoppage (in idle) */
440 void start_critical_timings(void)
441 {
442 if (preempt_trace(preempt_count()) || irq_trace())
443 start_critical_timing(CALLER_ADDR0, CALLER_ADDR1);
444 }
445 EXPORT_SYMBOL_GPL(start_critical_timings);
446 NOKPROBE_SYMBOL(start_critical_timings);
447
448 void stop_critical_timings(void)
449 {
450 if (preempt_trace(preempt_count()) || irq_trace())
451 stop_critical_timing(CALLER_ADDR0, CALLER_ADDR1);
452 }
453 EXPORT_SYMBOL_GPL(stop_critical_timings);
454 NOKPROBE_SYMBOL(stop_critical_timings);
455
456 #ifdef CONFIG_FUNCTION_TRACER
457 static bool function_enabled;
458
459 static int register_irqsoff_function(struct trace_array *tr, int graph, int set)
460 {
461 int ret;
462
463 /* 'set' is set if TRACE_ITER_FUNCTION is about to be set */
464 if (function_enabled || (!set && !(tr->trace_flags & TRACE_ITER_FUNCTION)))
465 return 0;
466
467 if (graph)
468 ret = register_ftrace_graph(&fgraph_ops);
469 else
470 ret = register_ftrace_function(tr->ops);
471
472 if (!ret)
473 function_enabled = true;
474
475 return ret;
476 }
477
478 static void unregister_irqsoff_function(struct trace_array *tr, int graph)
479 {
480 if (!function_enabled)
481 return;
482
483 if (graph)
484 unregister_ftrace_graph(&fgraph_ops);
485 else
486 unregister_ftrace_function(tr->ops);
487
488 function_enabled = false;
489 }
490
491 static int irqsoff_function_set(struct trace_array *tr, u32 mask, int set)
492 {
493 if (!(mask & TRACE_ITER_FUNCTION))
494 return 0;
495
496 if (set)
497 register_irqsoff_function(tr, is_graph(tr), 1);
498 else
499 unregister_irqsoff_function(tr, is_graph(tr));
500 return 1;
501 }
502 #else
503 static int register_irqsoff_function(struct trace_array *tr, int graph, int set)
504 {
505 return 0;
506 }
507 static void unregister_irqsoff_function(struct trace_array *tr, int graph) { }
508 static inline int irqsoff_function_set(struct trace_array *tr, u32 mask, int set)
509 {
510 return 0;
511 }
512 #endif /* CONFIG_FUNCTION_TRACER */
513
514 static int irqsoff_flag_changed(struct trace_array *tr, u32 mask, int set)
515 {
516 struct tracer *tracer = tr->current_trace;
517
518 if (irqsoff_function_set(tr, mask, set))
519 return 0;
520
521 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
522 if (mask & TRACE_ITER_DISPLAY_GRAPH)
523 return irqsoff_display_graph(tr, set);
524 #endif
525
526 return trace_keep_overwrite(tracer, mask, set);
527 }
528
529 static int start_irqsoff_tracer(struct trace_array *tr, int graph)
530 {
531 int ret;
532
533 ret = register_irqsoff_function(tr, graph, 0);
534
535 if (!ret && tracing_is_enabled())
536 tracer_enabled = 1;
537 else
538 tracer_enabled = 0;
539
540 return ret;
541 }
542
543 static void stop_irqsoff_tracer(struct trace_array *tr, int graph)
544 {
545 tracer_enabled = 0;
546
547 unregister_irqsoff_function(tr, graph);
548 }
549
550 static bool irqsoff_busy;
551
552 static int __irqsoff_tracer_init(struct trace_array *tr)
553 {
554 if (irqsoff_busy)
555 return -EBUSY;
556
557 save_flags = tr->trace_flags;
558
559 /* non overwrite screws up the latency tracers */
560 set_tracer_flag(tr, TRACE_ITER_OVERWRITE, 1);
561 set_tracer_flag(tr, TRACE_ITER_LATENCY_FMT, 1);
562 /* without pause, we will produce garbage if another latency occurs */
563 set_tracer_flag(tr, TRACE_ITER_PAUSE_ON_TRACE, 1);
564
565 tr->max_latency = 0;
566 irqsoff_trace = tr;
567 /* make sure that the tracer is visible */
568 smp_wmb();
569
570 ftrace_init_array_ops(tr, irqsoff_tracer_call);
571
572 /* Only toplevel instance supports graph tracing */
573 if (start_irqsoff_tracer(tr, (tr->flags & TRACE_ARRAY_FL_GLOBAL &&
574 is_graph(tr))))
575 printk(KERN_ERR "failed to start irqsoff tracer\n");
576
577 irqsoff_busy = true;
578 return 0;
579 }
580
581 static void __irqsoff_tracer_reset(struct trace_array *tr)
582 {
583 int lat_flag = save_flags & TRACE_ITER_LATENCY_FMT;
584 int overwrite_flag = save_flags & TRACE_ITER_OVERWRITE;
585 int pause_flag = save_flags & TRACE_ITER_PAUSE_ON_TRACE;
586
587 stop_irqsoff_tracer(tr, is_graph(tr));
588
589 set_tracer_flag(tr, TRACE_ITER_LATENCY_FMT, lat_flag);
590 set_tracer_flag(tr, TRACE_ITER_OVERWRITE, overwrite_flag);
591 set_tracer_flag(tr, TRACE_ITER_PAUSE_ON_TRACE, pause_flag);
592 ftrace_reset_array_ops(tr);
593
594 irqsoff_busy = false;
595 }
596
597 static void irqsoff_tracer_start(struct trace_array *tr)
598 {
599 tracer_enabled = 1;
600 }
601
602 static void irqsoff_tracer_stop(struct trace_array *tr)
603 {
604 tracer_enabled = 0;
605 }
606
607 #ifdef CONFIG_IRQSOFF_TRACER
608 /*
609 * We are only interested in hardirq on/off events:
610 */
611 void tracer_hardirqs_on(unsigned long a0, unsigned long a1)
612 {
613 if (!preempt_trace(preempt_count()) && irq_trace())
614 stop_critical_timing(a0, a1);
615 }
616 NOKPROBE_SYMBOL(tracer_hardirqs_on);
617
618 void tracer_hardirqs_off(unsigned long a0, unsigned long a1)
619 {
620 if (!preempt_trace(preempt_count()) && irq_trace())
621 start_critical_timing(a0, a1);
622 }
623 NOKPROBE_SYMBOL(tracer_hardirqs_off);
624
625 static int irqsoff_tracer_init(struct trace_array *tr)
626 {
627 trace_type = TRACER_IRQS_OFF;
628
629 return __irqsoff_tracer_init(tr);
630 }
631
632 static void irqsoff_tracer_reset(struct trace_array *tr)
633 {
634 __irqsoff_tracer_reset(tr);
635 }
636
637 static struct tracer irqsoff_tracer __read_mostly =
638 {
639 .name = "irqsoff",
640 .init = irqsoff_tracer_init,
641 .reset = irqsoff_tracer_reset,
642 .start = irqsoff_tracer_start,
643 .stop = irqsoff_tracer_stop,
644 .print_max = true,
645 .print_header = irqsoff_print_header,
646 .print_line = irqsoff_print_line,
647 .flag_changed = irqsoff_flag_changed,
648 #ifdef CONFIG_FTRACE_SELFTEST
649 .selftest = trace_selftest_startup_irqsoff,
650 #endif
651 .open = irqsoff_trace_open,
652 .close = irqsoff_trace_close,
653 .allow_instances = true,
654 .use_max_tr = true,
655 };
656 #endif /* CONFIG_IRQSOFF_TRACER */
657
658 #ifdef CONFIG_PREEMPT_TRACER
659 void tracer_preempt_on(unsigned long a0, unsigned long a1)
660 {
661 if (preempt_trace(preempt_count()) && !irq_trace())
662 stop_critical_timing(a0, a1);
663 }
664
665 void tracer_preempt_off(unsigned long a0, unsigned long a1)
666 {
667 if (preempt_trace(preempt_count()) && !irq_trace())
668 start_critical_timing(a0, a1);
669 }
670
671 static int preemptoff_tracer_init(struct trace_array *tr)
672 {
673 trace_type = TRACER_PREEMPT_OFF;
674
675 return __irqsoff_tracer_init(tr);
676 }
677
678 static void preemptoff_tracer_reset(struct trace_array *tr)
679 {
680 __irqsoff_tracer_reset(tr);
681 }
682
683 static struct tracer preemptoff_tracer __read_mostly =
684 {
685 .name = "preemptoff",
686 .init = preemptoff_tracer_init,
687 .reset = preemptoff_tracer_reset,
688 .start = irqsoff_tracer_start,
689 .stop = irqsoff_tracer_stop,
690 .print_max = true,
691 .print_header = irqsoff_print_header,
692 .print_line = irqsoff_print_line,
693 .flag_changed = irqsoff_flag_changed,
694 #ifdef CONFIG_FTRACE_SELFTEST
695 .selftest = trace_selftest_startup_preemptoff,
696 #endif
697 .open = irqsoff_trace_open,
698 .close = irqsoff_trace_close,
699 .allow_instances = true,
700 .use_max_tr = true,
701 };
702 #endif /* CONFIG_PREEMPT_TRACER */
703
704 #if defined(CONFIG_IRQSOFF_TRACER) && defined(CONFIG_PREEMPT_TRACER)
705
706 static int preemptirqsoff_tracer_init(struct trace_array *tr)
707 {
708 trace_type = TRACER_IRQS_OFF | TRACER_PREEMPT_OFF;
709
710 return __irqsoff_tracer_init(tr);
711 }
712
713 static void preemptirqsoff_tracer_reset(struct trace_array *tr)
714 {
715 __irqsoff_tracer_reset(tr);
716 }
717
718 static struct tracer preemptirqsoff_tracer __read_mostly =
719 {
720 .name = "preemptirqsoff",
721 .init = preemptirqsoff_tracer_init,
722 .reset = preemptirqsoff_tracer_reset,
723 .start = irqsoff_tracer_start,
724 .stop = irqsoff_tracer_stop,
725 .print_max = true,
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_preemptirqsoff,
731 #endif
732 .open = irqsoff_trace_open,
733 .close = irqsoff_trace_close,
734 .allow_instances = true,
735 .use_max_tr = true,
736 };
737 #endif
738
739 __init static int init_irqsoff_tracer(void)
740 {
741 #ifdef CONFIG_IRQSOFF_TRACER
742 register_tracer(&irqsoff_tracer);
743 #endif
744 #ifdef CONFIG_PREEMPT_TRACER
745 register_tracer(&preemptoff_tracer);
746 #endif
747 #if defined(CONFIG_IRQSOFF_TRACER) && defined(CONFIG_PREEMPT_TRACER)
748 register_tracer(&preemptirqsoff_tracer);
749 #endif
750
751 return 0;
752 }
753 core_initcall(init_irqsoff_tracer);
754 #endif /* IRQSOFF_TRACER || PREEMPTOFF_TRACER */
755
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