Merge tag 'trace-v5.1' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux...
[sfrench/cifs-2.6.git] / kernel / trace / trace_irqsoff.c
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->trace_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 pt_regs *pt_regs)
142 {
143         struct trace_array *tr = irqsoff_trace;
144         struct trace_array_cpu *data;
145         unsigned long flags;
146
147         if (!func_prolog_dec(tr, &data, &flags))
148                 return;
149
150         trace_function(tr, ip, parent_ip, flags, preempt_count());
151
152         atomic_dec(&data->disabled);
153 }
154 #endif /* CONFIG_FUNCTION_TRACER */
155
156 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
157 static int irqsoff_display_graph(struct trace_array *tr, int set)
158 {
159         int cpu;
160
161         if (!(is_graph(tr) ^ set))
162                 return 0;
163
164         stop_irqsoff_tracer(irqsoff_trace, !set);
165
166         for_each_possible_cpu(cpu)
167                 per_cpu(tracing_cpu, cpu) = 0;
168
169         tr->max_latency = 0;
170         tracing_reset_online_cpus(&irqsoff_trace->trace_buffer);
171
172         return start_irqsoff_tracer(irqsoff_trace, set);
173 }
174
175 static int irqsoff_graph_entry(struct ftrace_graph_ent *trace)
176 {
177         struct trace_array *tr = irqsoff_trace;
178         struct trace_array_cpu *data;
179         unsigned long flags;
180         int ret;
181         int pc;
182
183         if (ftrace_graph_ignore_func(trace))
184                 return 0;
185         /*
186          * Do not trace a function if it's filtered by set_graph_notrace.
187          * Make the index of ret stack negative to indicate that it should
188          * ignore further functions.  But it needs its own ret stack entry
189          * to recover the original index in order to continue tracing after
190          * returning from the function.
191          */
192         if (ftrace_graph_notrace_addr(trace->func))
193                 return 1;
194
195         if (!func_prolog_dec(tr, &data, &flags))
196                 return 0;
197
198         pc = preempt_count();
199         ret = __trace_graph_entry(tr, trace, flags, pc);
200         atomic_dec(&data->disabled);
201
202         return ret;
203 }
204
205 static void irqsoff_graph_return(struct ftrace_graph_ret *trace)
206 {
207         struct trace_array *tr = irqsoff_trace;
208         struct trace_array_cpu *data;
209         unsigned long flags;
210         int pc;
211
212         ftrace_graph_addr_finish(trace);
213
214         if (!func_prolog_dec(tr, &data, &flags))
215                 return;
216
217         pc = preempt_count();
218         __trace_graph_return(tr, trace, flags, pc);
219         atomic_dec(&data->disabled);
220 }
221
222 static struct fgraph_ops fgraph_ops = {
223         .entryfunc              = &irqsoff_graph_entry,
224         .retfunc                = &irqsoff_graph_return,
225 };
226
227 static void irqsoff_trace_open(struct trace_iterator *iter)
228 {
229         if (is_graph(iter->tr))
230                 graph_trace_open(iter);
231
232 }
233
234 static void irqsoff_trace_close(struct trace_iterator *iter)
235 {
236         if (iter->private)
237                 graph_trace_close(iter);
238 }
239
240 #define GRAPH_TRACER_FLAGS (TRACE_GRAPH_PRINT_CPU | \
241                             TRACE_GRAPH_PRINT_PROC | \
242                             TRACE_GRAPH_PRINT_REL_TIME | \
243                             TRACE_GRAPH_PRINT_DURATION)
244
245 static enum print_line_t irqsoff_print_line(struct trace_iterator *iter)
246 {
247         /*
248          * In graph mode call the graph tracer output function,
249          * otherwise go with the TRACE_FN event handler
250          */
251         if (is_graph(iter->tr))
252                 return print_graph_function_flags(iter, GRAPH_TRACER_FLAGS);
253
254         return TRACE_TYPE_UNHANDLED;
255 }
256
257 static void irqsoff_print_header(struct seq_file *s)
258 {
259         struct trace_array *tr = irqsoff_trace;
260
261         if (is_graph(tr))
262                 print_graph_headers_flags(s, GRAPH_TRACER_FLAGS);
263         else
264                 trace_default_header(s);
265 }
266
267 static void
268 __trace_function(struct trace_array *tr,
269                  unsigned long ip, unsigned long parent_ip,
270                  unsigned long flags, int pc)
271 {
272         if (is_graph(tr))
273                 trace_graph_function(tr, ip, parent_ip, flags, pc);
274         else
275                 trace_function(tr, ip, parent_ip, flags, pc);
276 }
277
278 #else
279 #define __trace_function trace_function
280
281 static enum print_line_t irqsoff_print_line(struct trace_iterator *iter)
282 {
283         return TRACE_TYPE_UNHANDLED;
284 }
285
286 static void irqsoff_trace_open(struct trace_iterator *iter) { }
287 static void irqsoff_trace_close(struct trace_iterator *iter) { }
288
289 #ifdef CONFIG_FUNCTION_TRACER
290 static void irqsoff_print_header(struct seq_file *s)
291 {
292         trace_default_header(s);
293 }
294 #else
295 static void irqsoff_print_header(struct seq_file *s)
296 {
297         trace_latency_header(s);
298 }
299 #endif /* CONFIG_FUNCTION_TRACER */
300 #endif /* CONFIG_FUNCTION_GRAPH_TRACER */
301
302 /*
303  * Should this new latency be reported/recorded?
304  */
305 static bool report_latency(struct trace_array *tr, u64 delta)
306 {
307         if (tracing_thresh) {
308                 if (delta < tracing_thresh)
309                         return false;
310         } else {
311                 if (delta <= tr->max_latency)
312                         return false;
313         }
314         return true;
315 }
316
317 static void
318 check_critical_timing(struct trace_array *tr,
319                       struct trace_array_cpu *data,
320                       unsigned long parent_ip,
321                       int cpu)
322 {
323         u64 T0, T1, delta;
324         unsigned long flags;
325         int pc;
326
327         T0 = data->preempt_timestamp;
328         T1 = ftrace_now(cpu);
329         delta = T1-T0;
330
331         local_save_flags(flags);
332
333         pc = preempt_count();
334
335         if (!report_latency(tr, delta))
336                 goto out;
337
338         raw_spin_lock_irqsave(&max_trace_lock, flags);
339
340         /* check if we are still the max latency */
341         if (!report_latency(tr, delta))
342                 goto out_unlock;
343
344         __trace_function(tr, CALLER_ADDR0, parent_ip, flags, pc);
345         /* Skip 5 functions to get to the irq/preempt enable function */
346         __trace_stack(tr, flags, 5, pc);
347
348         if (data->critical_sequence != max_sequence)
349                 goto out_unlock;
350
351         data->critical_end = parent_ip;
352
353         if (likely(!is_tracing_stopped())) {
354                 tr->max_latency = delta;
355                 update_max_tr_single(tr, current, cpu);
356         }
357
358         max_sequence++;
359
360 out_unlock:
361         raw_spin_unlock_irqrestore(&max_trace_lock, flags);
362
363 out:
364         data->critical_sequence = max_sequence;
365         data->preempt_timestamp = ftrace_now(cpu);
366         __trace_function(tr, CALLER_ADDR0, parent_ip, flags, pc);
367 }
368
369 static nokprobe_inline void
370 start_critical_timing(unsigned long ip, unsigned long parent_ip, int pc)
371 {
372         int cpu;
373         struct trace_array *tr = irqsoff_trace;
374         struct trace_array_cpu *data;
375         unsigned long flags;
376
377         if (!tracer_enabled || !tracing_is_enabled())
378                 return;
379
380         cpu = raw_smp_processor_id();
381
382         if (per_cpu(tracing_cpu, cpu))
383                 return;
384
385         data = per_cpu_ptr(tr->trace_buffer.data, cpu);
386
387         if (unlikely(!data) || atomic_read(&data->disabled))
388                 return;
389
390         atomic_inc(&data->disabled);
391
392         data->critical_sequence = max_sequence;
393         data->preempt_timestamp = ftrace_now(cpu);
394         data->critical_start = parent_ip ? : ip;
395
396         local_save_flags(flags);
397
398         __trace_function(tr, ip, parent_ip, flags, pc);
399
400         per_cpu(tracing_cpu, cpu) = 1;
401
402         atomic_dec(&data->disabled);
403 }
404
405 static nokprobe_inline void
406 stop_critical_timing(unsigned long ip, unsigned long parent_ip, int pc)
407 {
408         int cpu;
409         struct trace_array *tr = irqsoff_trace;
410         struct trace_array_cpu *data;
411         unsigned long flags;
412
413         cpu = raw_smp_processor_id();
414         /* Always clear the tracing cpu on stopping the trace */
415         if (unlikely(per_cpu(tracing_cpu, cpu)))
416                 per_cpu(tracing_cpu, cpu) = 0;
417         else
418                 return;
419
420         if (!tracer_enabled || !tracing_is_enabled())
421                 return;
422
423         data = per_cpu_ptr(tr->trace_buffer.data, cpu);
424
425         if (unlikely(!data) ||
426             !data->critical_start || atomic_read(&data->disabled))
427                 return;
428
429         atomic_inc(&data->disabled);
430
431         local_save_flags(flags);
432         __trace_function(tr, ip, parent_ip, flags, pc);
433         check_critical_timing(tr, data, parent_ip ? : ip, cpu);
434         data->critical_start = 0;
435         atomic_dec(&data->disabled);
436 }
437
438 /* start and stop critical timings used to for stoppage (in idle) */
439 void start_critical_timings(void)
440 {
441         int pc = preempt_count();
442
443         if (preempt_trace(pc) || irq_trace())
444                 start_critical_timing(CALLER_ADDR0, CALLER_ADDR1, pc);
445 }
446 EXPORT_SYMBOL_GPL(start_critical_timings);
447 NOKPROBE_SYMBOL(start_critical_timings);
448
449 void stop_critical_timings(void)
450 {
451         int pc = preempt_count();
452
453         if (preempt_trace(pc) || irq_trace())
454                 stop_critical_timing(CALLER_ADDR0, CALLER_ADDR1, pc);
455 }
456 EXPORT_SYMBOL_GPL(stop_critical_timings);
457 NOKPROBE_SYMBOL(stop_critical_timings);
458
459 #ifdef CONFIG_FUNCTION_TRACER
460 static bool function_enabled;
461
462 static int register_irqsoff_function(struct trace_array *tr, int graph, int set)
463 {
464         int ret;
465
466         /* 'set' is set if TRACE_ITER_FUNCTION is about to be set */
467         if (function_enabled || (!set && !(tr->trace_flags & TRACE_ITER_FUNCTION)))
468                 return 0;
469
470         if (graph)
471                 ret = register_ftrace_graph(&fgraph_ops);
472         else
473                 ret = register_ftrace_function(tr->ops);
474
475         if (!ret)
476                 function_enabled = true;
477
478         return ret;
479 }
480
481 static void unregister_irqsoff_function(struct trace_array *tr, int graph)
482 {
483         if (!function_enabled)
484                 return;
485
486         if (graph)
487                 unregister_ftrace_graph(&fgraph_ops);
488         else
489                 unregister_ftrace_function(tr->ops);
490
491         function_enabled = false;
492 }
493
494 static int irqsoff_function_set(struct trace_array *tr, u32 mask, int set)
495 {
496         if (!(mask & TRACE_ITER_FUNCTION))
497                 return 0;
498
499         if (set)
500                 register_irqsoff_function(tr, is_graph(tr), 1);
501         else
502                 unregister_irqsoff_function(tr, is_graph(tr));
503         return 1;
504 }
505 #else
506 static int register_irqsoff_function(struct trace_array *tr, int graph, int set)
507 {
508         return 0;
509 }
510 static void unregister_irqsoff_function(struct trace_array *tr, int graph) { }
511 static inline int irqsoff_function_set(struct trace_array *tr, u32 mask, int set)
512 {
513         return 0;
514 }
515 #endif /* CONFIG_FUNCTION_TRACER */
516
517 static int irqsoff_flag_changed(struct trace_array *tr, u32 mask, int set)
518 {
519         struct tracer *tracer = tr->current_trace;
520
521         if (irqsoff_function_set(tr, mask, set))
522                 return 0;
523
524 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
525         if (mask & TRACE_ITER_DISPLAY_GRAPH)
526                 return irqsoff_display_graph(tr, set);
527 #endif
528
529         return trace_keep_overwrite(tracer, mask, set);
530 }
531
532 static int start_irqsoff_tracer(struct trace_array *tr, int graph)
533 {
534         int ret;
535
536         ret = register_irqsoff_function(tr, graph, 0);
537
538         if (!ret && tracing_is_enabled())
539                 tracer_enabled = 1;
540         else
541                 tracer_enabled = 0;
542
543         return ret;
544 }
545
546 static void stop_irqsoff_tracer(struct trace_array *tr, int graph)
547 {
548         tracer_enabled = 0;
549
550         unregister_irqsoff_function(tr, graph);
551 }
552
553 static bool irqsoff_busy;
554
555 static int __irqsoff_tracer_init(struct trace_array *tr)
556 {
557         if (irqsoff_busy)
558                 return -EBUSY;
559
560         save_flags = tr->trace_flags;
561
562         /* non overwrite screws up the latency tracers */
563         set_tracer_flag(tr, TRACE_ITER_OVERWRITE, 1);
564         set_tracer_flag(tr, TRACE_ITER_LATENCY_FMT, 1);
565
566         tr->max_latency = 0;
567         irqsoff_trace = tr;
568         /* make sure that the tracer is visible */
569         smp_wmb();
570
571         ftrace_init_array_ops(tr, irqsoff_tracer_call);
572
573         /* Only toplevel instance supports graph tracing */
574         if (start_irqsoff_tracer(tr, (tr->flags & TRACE_ARRAY_FL_GLOBAL &&
575                                       is_graph(tr))))
576                 printk(KERN_ERR "failed to start irqsoff tracer\n");
577
578         irqsoff_busy = true;
579         return 0;
580 }
581
582 static void __irqsoff_tracer_reset(struct trace_array *tr)
583 {
584         int lat_flag = save_flags & TRACE_ITER_LATENCY_FMT;
585         int overwrite_flag = save_flags & TRACE_ITER_OVERWRITE;
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         ftrace_reset_array_ops(tr);
592
593         irqsoff_busy = false;
594 }
595
596 static void irqsoff_tracer_start(struct trace_array *tr)
597 {
598         tracer_enabled = 1;
599 }
600
601 static void irqsoff_tracer_stop(struct trace_array *tr)
602 {
603         tracer_enabled = 0;
604 }
605
606 #ifdef CONFIG_IRQSOFF_TRACER
607 /*
608  * We are only interested in hardirq on/off events:
609  */
610 void tracer_hardirqs_on(unsigned long a0, unsigned long a1)
611 {
612         unsigned int pc = preempt_count();
613
614         if (!preempt_trace(pc) && irq_trace())
615                 stop_critical_timing(a0, a1, pc);
616 }
617 NOKPROBE_SYMBOL(tracer_hardirqs_on);
618
619 void tracer_hardirqs_off(unsigned long a0, unsigned long a1)
620 {
621         unsigned int pc = preempt_count();
622
623         if (!preempt_trace(pc) && irq_trace())
624                 start_critical_timing(a0, a1, pc);
625 }
626 NOKPROBE_SYMBOL(tracer_hardirqs_off);
627
628 static int irqsoff_tracer_init(struct trace_array *tr)
629 {
630         trace_type = TRACER_IRQS_OFF;
631
632         return __irqsoff_tracer_init(tr);
633 }
634
635 static void irqsoff_tracer_reset(struct trace_array *tr)
636 {
637         __irqsoff_tracer_reset(tr);
638 }
639
640 static struct tracer irqsoff_tracer __read_mostly =
641 {
642         .name           = "irqsoff",
643         .init           = irqsoff_tracer_init,
644         .reset          = irqsoff_tracer_reset,
645         .start          = irqsoff_tracer_start,
646         .stop           = irqsoff_tracer_stop,
647         .print_max      = true,
648         .print_header   = irqsoff_print_header,
649         .print_line     = irqsoff_print_line,
650         .flag_changed   = irqsoff_flag_changed,
651 #ifdef CONFIG_FTRACE_SELFTEST
652         .selftest    = trace_selftest_startup_irqsoff,
653 #endif
654         .open           = irqsoff_trace_open,
655         .close          = irqsoff_trace_close,
656         .allow_instances = true,
657         .use_max_tr     = true,
658 };
659 #endif /*  CONFIG_IRQSOFF_TRACER */
660
661 #ifdef CONFIG_PREEMPT_TRACER
662 void tracer_preempt_on(unsigned long a0, unsigned long a1)
663 {
664         int pc = preempt_count();
665
666         if (preempt_trace(pc) && !irq_trace())
667                 stop_critical_timing(a0, a1, pc);
668 }
669
670 void tracer_preempt_off(unsigned long a0, unsigned long a1)
671 {
672         int pc = preempt_count();
673
674         if (preempt_trace(pc) && !irq_trace())
675                 start_critical_timing(a0, a1, pc);
676 }
677
678 static int preemptoff_tracer_init(struct trace_array *tr)
679 {
680         trace_type = TRACER_PREEMPT_OFF;
681
682         return __irqsoff_tracer_init(tr);
683 }
684
685 static void preemptoff_tracer_reset(struct trace_array *tr)
686 {
687         __irqsoff_tracer_reset(tr);
688 }
689
690 static struct tracer preemptoff_tracer __read_mostly =
691 {
692         .name           = "preemptoff",
693         .init           = preemptoff_tracer_init,
694         .reset          = preemptoff_tracer_reset,
695         .start          = irqsoff_tracer_start,
696         .stop           = irqsoff_tracer_stop,
697         .print_max      = true,
698         .print_header   = irqsoff_print_header,
699         .print_line     = irqsoff_print_line,
700         .flag_changed   = irqsoff_flag_changed,
701 #ifdef CONFIG_FTRACE_SELFTEST
702         .selftest    = trace_selftest_startup_preemptoff,
703 #endif
704         .open           = irqsoff_trace_open,
705         .close          = irqsoff_trace_close,
706         .allow_instances = true,
707         .use_max_tr     = true,
708 };
709 #endif /* CONFIG_PREEMPT_TRACER */
710
711 #if defined(CONFIG_IRQSOFF_TRACER) && defined(CONFIG_PREEMPT_TRACER)
712
713 static int preemptirqsoff_tracer_init(struct trace_array *tr)
714 {
715         trace_type = TRACER_IRQS_OFF | TRACER_PREEMPT_OFF;
716
717         return __irqsoff_tracer_init(tr);
718 }
719
720 static void preemptirqsoff_tracer_reset(struct trace_array *tr)
721 {
722         __irqsoff_tracer_reset(tr);
723 }
724
725 static struct tracer preemptirqsoff_tracer __read_mostly =
726 {
727         .name           = "preemptirqsoff",
728         .init           = preemptirqsoff_tracer_init,
729         .reset          = preemptirqsoff_tracer_reset,
730         .start          = irqsoff_tracer_start,
731         .stop           = irqsoff_tracer_stop,
732         .print_max      = true,
733         .print_header   = irqsoff_print_header,
734         .print_line     = irqsoff_print_line,
735         .flag_changed   = irqsoff_flag_changed,
736 #ifdef CONFIG_FTRACE_SELFTEST
737         .selftest    = trace_selftest_startup_preemptirqsoff,
738 #endif
739         .open           = irqsoff_trace_open,
740         .close          = irqsoff_trace_close,
741         .allow_instances = true,
742         .use_max_tr     = true,
743 };
744 #endif
745
746 __init static int init_irqsoff_tracer(void)
747 {
748 #ifdef CONFIG_IRQSOFF_TRACER
749         register_tracer(&irqsoff_tracer);
750 #endif
751 #ifdef CONFIG_PREEMPT_TRACER
752         register_tracer(&preemptoff_tracer);
753 #endif
754 #if defined(CONFIG_IRQSOFF_TRACER) && defined(CONFIG_PREEMPT_TRACER)
755         register_tracer(&preemptirqsoff_tracer);
756 #endif
757
758         return 0;
759 }
760 core_initcall(init_irqsoff_tracer);
761 #endif /* IRQSOFF_TRACER || PREEMPTOFF_TRACER */