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)
 24static struct trace_array		*irqsoff_trace __read_mostly;
 25static int				tracer_enabled __read_mostly;
 26
 27static DEFINE_PER_CPU(int, tracing_cpu);
 28
 29static DEFINE_RAW_SPINLOCK(max_trace_lock);
 30
 31enum {
 32	TRACER_IRQS_OFF		= (1 << 1),
 33	TRACER_PREEMPT_OFF	= (1 << 2),
 34};
 35
 36static int trace_type __read_mostly;
 37
 38static int save_flags;
 39
 40static void stop_irqsoff_tracer(struct trace_array *tr, int graph);
 41static int start_irqsoff_tracer(struct trace_array *tr, int graph);
 42
 43#ifdef CONFIG_PREEMPT_TRACER
 44static inline int
 45preempt_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
 54static inline int
 55irq_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
 65static int irqsoff_display_graph(struct trace_array *tr, int set);
 66# define is_graph(tr) ((tr)->trace_flags & TRACE_ITER(DISPLAY_GRAPH))
 67#else
 68static 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 */
 83static __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 */
 99static 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 = local_inc_return(&(*data)->disabled);
127
128	if (likely(disabled == 1))
129		return 1;
130
131	local_dec(&(*data)->disabled);
132
133	return 0;
134}
135
136/*
137 * irqsoff uses its own tracer function to keep the overhead down:
138 */
139static void
140irqsoff_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, fregs);
154
155	local_dec(&data->disabled);
156}
157#endif /* CONFIG_FUNCTION_TRACER */
158
159#ifdef CONFIG_FUNCTION_GRAPH_TRACER
160static 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
178static int irqsoff_graph_entry(struct ftrace_graph_ent *trace,
179			       struct fgraph_ops *gops,
180			       struct ftrace_regs *fregs)
181{
182	struct trace_array *tr = irqsoff_trace;
183	struct trace_array_cpu *data;
184	unsigned long flags;
185	unsigned int trace_ctx;
186	u64 *calltime;
187	int ret = 0;
188
189	if (ftrace_graph_ignore_func(gops, trace))
190		return 0;
191	/*
192	 * Do not trace a function if it's filtered by set_graph_notrace.
193	 * Make the index of ret stack negative to indicate that it should
194	 * ignore further functions.  But it needs its own ret stack entry
195	 * to recover the original index in order to continue tracing after
196	 * returning from the function.
197	 */
198	if (ftrace_graph_notrace_addr(trace->func))
199		return 1;
200
201	if (!func_prolog_dec(tr, &data, &flags))
202		return 0;
203
204	calltime = fgraph_reserve_data(gops->idx, sizeof(*calltime));
205	if (calltime) {
206		*calltime = trace_clock_local();
207		trace_ctx = tracing_gen_ctx_flags(flags);
208		ret = __trace_graph_entry(tr, trace, trace_ctx);
209	}
210	local_dec(&data->disabled);
211
212	return ret;
213}
214
215static void irqsoff_graph_return(struct ftrace_graph_ret *trace,
216				 struct fgraph_ops *gops,
217				 struct ftrace_regs *fregs)
218{
219	struct trace_array *tr = irqsoff_trace;
220	struct trace_array_cpu *data;
221	unsigned long flags;
222	unsigned int trace_ctx;
223	u64 *calltime;
224	u64 rettime;
225	int size;
226
227	ftrace_graph_addr_finish(gops, trace);
228
229	if (!func_prolog_dec(tr, &data, &flags))
230		return;
231
232	rettime = trace_clock_local();
233	calltime = fgraph_retrieve_data(gops->idx, &size);
234	if (calltime) {
235		trace_ctx = tracing_gen_ctx_flags(flags);
236		__trace_graph_return(tr, trace, trace_ctx, *calltime, rettime);
237	}
238	local_dec(&data->disabled);
239}
240
241static struct fgraph_ops fgraph_ops = {
242	.entryfunc		= &irqsoff_graph_entry,
243	.retfunc		= &irqsoff_graph_return,
244};
245
246static void irqsoff_trace_open(struct trace_iterator *iter)
247{
248	if (is_graph(iter->tr))
249		graph_trace_open(iter);
250}
251
252static void irqsoff_trace_close(struct trace_iterator *iter)
253{
254	if (iter->private)
255		graph_trace_close(iter);
256}
257
258#define GRAPH_TRACER_FLAGS (TRACE_GRAPH_PRINT_CPU | \
259			    TRACE_GRAPH_PRINT_PROC | \
260			    TRACE_GRAPH_PRINT_REL_TIME | \
261			    TRACE_GRAPH_PRINT_DURATION)
262
263static enum print_line_t irqsoff_print_line(struct trace_iterator *iter)
264{
265	/*
266	 * In graph mode call the graph tracer output function,
267	 * otherwise go with the TRACE_FN event handler
268	 */
269	if (is_graph(iter->tr))
270		return print_graph_function_flags(iter, GRAPH_TRACER_FLAGS);
271
272	return TRACE_TYPE_UNHANDLED;
273}
274
275static void irqsoff_print_header(struct seq_file *s)
276{
277	struct trace_array *tr = irqsoff_trace;
278
279	if (is_graph(tr))
280		print_graph_headers_flags(s, GRAPH_TRACER_FLAGS);
281	else
282		trace_default_header(s);
283}
284
285static void
286__trace_function(struct trace_array *tr,
287		 unsigned long ip, unsigned long parent_ip,
288		 unsigned int trace_ctx)
289{
290	if (is_graph(tr))
291		trace_graph_function(tr, ip, parent_ip, trace_ctx);
292	else
293		trace_function(tr, ip, parent_ip, trace_ctx, NULL);
294}
295
296#else
297static inline void
298__trace_function(struct trace_array *tr,
299		 unsigned long ip, unsigned long parent_ip,
300		 unsigned int trace_ctx)
301{
302	return trace_function(tr, ip, parent_ip, trace_ctx, NULL);
303}
304
305static enum print_line_t irqsoff_print_line(struct trace_iterator *iter)
306{
307	return TRACE_TYPE_UNHANDLED;
308}
309
310static void irqsoff_trace_open(struct trace_iterator *iter) { }
311static void irqsoff_trace_close(struct trace_iterator *iter) { }
312
313#ifdef CONFIG_FUNCTION_TRACER
314static void irqsoff_print_header(struct seq_file *s)
315{
316	trace_default_header(s);
317}
318#else
319static void irqsoff_print_header(struct seq_file *s)
320{
321	trace_latency_header(s);
322}
323#endif /* CONFIG_FUNCTION_TRACER */
324#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
325
326/*
327 * Should this new latency be reported/recorded?
328 */
329static bool report_latency(struct trace_array *tr, u64 delta)
330{
331	if (tracing_thresh) {
332		if (delta < tracing_thresh)
333			return false;
334	} else {
335		if (delta <= tr->max_latency)
336			return false;
337	}
338	return true;
339}
340
341static void
342check_critical_timing(struct trace_array *tr,
343		      struct trace_array_cpu *data,
344		      unsigned long parent_ip,
345		      int cpu)
346{
347	u64 T0, T1, delta;
348	unsigned long flags;
349	unsigned int trace_ctx;
350
351	T0 = data->preempt_timestamp;
352	T1 = ftrace_now(cpu);
353	delta = T1-T0;
354
355	trace_ctx = tracing_gen_ctx();
356
357	if (!report_latency(tr, delta))
358		goto out;
359
360	raw_spin_lock_irqsave(&max_trace_lock, flags);
361
362	/* check if we are still the max latency */
363	if (!report_latency(tr, delta))
364		goto out_unlock;
365
366	__trace_function(tr, CALLER_ADDR0, parent_ip, trace_ctx);
367	/* Skip 5 functions to get to the irq/preempt enable function */
368	__trace_stack(tr, trace_ctx, 5);
369
370	if (data->critical_sequence != max_sequence)
371		goto out_unlock;
372
373	data->critical_end = parent_ip;
374
375	if (likely(!is_tracing_stopped())) {
376		tr->max_latency = delta;
377		update_max_tr_single(tr, current, cpu);
378	}
379
380	max_sequence++;
381
382out_unlock:
383	raw_spin_unlock_irqrestore(&max_trace_lock, flags);
384
385out:
386	data->critical_sequence = max_sequence;
387	data->preempt_timestamp = ftrace_now(cpu);
388	__trace_function(tr, CALLER_ADDR0, parent_ip, trace_ctx);
389}
390
391static nokprobe_inline void
392start_critical_timing(unsigned long ip, unsigned long parent_ip)
393{
394	int cpu;
395	struct trace_array *tr = irqsoff_trace;
396	struct trace_array_cpu *data;
397	long disabled;
398
399	if (!tracer_enabled || !tracing_is_enabled())
400		return;
401
402	cpu = raw_smp_processor_id();
403
404	if (per_cpu(tracing_cpu, cpu))
405		return;
406
407	data = per_cpu_ptr(tr->array_buffer.data, cpu);
408
409	if (unlikely(!data) || local_read(&data->disabled))
410		return;
411
412	disabled = local_inc_return(&data->disabled);
413
414	if (disabled == 1) {
415		data->critical_sequence = max_sequence;
416		data->preempt_timestamp = ftrace_now(cpu);
417		data->critical_start = parent_ip ? : ip;
418
419		__trace_function(tr, ip, parent_ip, tracing_gen_ctx());
420
421		per_cpu(tracing_cpu, cpu) = 1;
422	}
423
424	local_dec(&data->disabled);
425}
426
427static nokprobe_inline void
428stop_critical_timing(unsigned long ip, unsigned long parent_ip)
429{
430	int cpu;
431	struct trace_array *tr = irqsoff_trace;
432	struct trace_array_cpu *data;
433	unsigned int trace_ctx;
434	long disabled;
435
436	cpu = raw_smp_processor_id();
437	/* Always clear the tracing cpu on stopping the trace */
438	if (unlikely(per_cpu(tracing_cpu, cpu)))
439		per_cpu(tracing_cpu, cpu) = 0;
440	else
441		return;
442
443	if (!tracer_enabled || !tracing_is_enabled())
444		return;
445
446	data = per_cpu_ptr(tr->array_buffer.data, cpu);
447
448	if (unlikely(!data) ||
449	    !data->critical_start || local_read(&data->disabled))
450		return;
451
452	disabled = local_inc_return(&data->disabled);
453
454	if (disabled == 1) {
455		trace_ctx = tracing_gen_ctx();
456		__trace_function(tr, ip, parent_ip, trace_ctx);
457		check_critical_timing(tr, data, parent_ip ? : ip, cpu);
458		data->critical_start = 0;
459	}
460
461	local_dec(&data->disabled);
462}
463
464/* start and stop critical timings used to for stoppage (in idle) */
465void start_critical_timings(void)
466{
467	if (preempt_trace(preempt_count()) || irq_trace())
468		start_critical_timing(CALLER_ADDR0, CALLER_ADDR1);
469}
470EXPORT_SYMBOL_GPL(start_critical_timings);
471NOKPROBE_SYMBOL(start_critical_timings);
472
473void stop_critical_timings(void)
474{
475	if (preempt_trace(preempt_count()) || irq_trace())
476		stop_critical_timing(CALLER_ADDR0, CALLER_ADDR1);
477}
478EXPORT_SYMBOL_GPL(stop_critical_timings);
479NOKPROBE_SYMBOL(stop_critical_timings);
480
481#ifdef CONFIG_FUNCTION_TRACER
482static bool function_enabled;
483
484static int register_irqsoff_function(struct trace_array *tr, int graph, int set)
485{
486	int ret;
487
488	/* 'set' is set if TRACE_ITER(FUNCTION) is about to be set */
489	if (function_enabled || (!set && !(tr->trace_flags & TRACE_ITER(FUNCTION))))
490		return 0;
491
492	if (graph)
493		ret = register_ftrace_graph(&fgraph_ops);
494	else
495		ret = register_ftrace_function(tr->ops);
496
497	if (!ret)
498		function_enabled = true;
499
500	return ret;
501}
502
503static void unregister_irqsoff_function(struct trace_array *tr, int graph)
504{
505	if (!function_enabled)
506		return;
507
508	if (graph)
509		unregister_ftrace_graph(&fgraph_ops);
510	else
511		unregister_ftrace_function(tr->ops);
512
513	function_enabled = false;
514}
515
516static int irqsoff_function_set(struct trace_array *tr, u32 mask, int set)
517{
518	if (!(mask & TRACE_ITER(FUNCTION)))
519		return 0;
520
521	if (set)
522		register_irqsoff_function(tr, is_graph(tr), 1);
523	else
524		unregister_irqsoff_function(tr, is_graph(tr));
525	return 1;
526}
527#else
528static int register_irqsoff_function(struct trace_array *tr, int graph, int set)
529{
530	return 0;
531}
532static void unregister_irqsoff_function(struct trace_array *tr, int graph) { }
533static inline int irqsoff_function_set(struct trace_array *tr, u32 mask, int set)
534{
535	return 0;
536}
537#endif /* CONFIG_FUNCTION_TRACER */
538
539static int irqsoff_flag_changed(struct trace_array *tr, u64 mask, int set)
540{
541	struct tracer *tracer = tr->current_trace;
542
543	if (irqsoff_function_set(tr, mask, set))
544		return 0;
545
546#ifdef CONFIG_FUNCTION_GRAPH_TRACER
547	if (mask & TRACE_ITER(DISPLAY_GRAPH))
548		return irqsoff_display_graph(tr, set);
549#endif
550
551	return trace_keep_overwrite(tracer, mask, set);
552}
553
554static int start_irqsoff_tracer(struct trace_array *tr, int graph)
555{
556	int ret;
557
558	ret = register_irqsoff_function(tr, graph, 0);
559
560	if (!ret && tracing_is_enabled())
561		tracer_enabled = 1;
562	else
563		tracer_enabled = 0;
564
565	return ret;
566}
567
568static void stop_irqsoff_tracer(struct trace_array *tr, int graph)
569{
570	tracer_enabled = 0;
571
572	unregister_irqsoff_function(tr, graph);
573}
574
575static bool irqsoff_busy;
576
577static int __irqsoff_tracer_init(struct trace_array *tr)
578{
579	if (irqsoff_busy)
580		return -EBUSY;
581
582	save_flags = tr->trace_flags;
583
584	/* non overwrite screws up the latency tracers */
585	set_tracer_flag(tr, TRACE_ITER(OVERWRITE), 1);
586	set_tracer_flag(tr, TRACE_ITER(LATENCY_FMT), 1);
587	/* without pause, we will produce garbage if another latency occurs */
588	set_tracer_flag(tr, TRACE_ITER(PAUSE_ON_TRACE), 1);
589
590	tr->max_latency = 0;
591	irqsoff_trace = tr;
592	/* make sure that the tracer is visible */
593	smp_wmb();
594
595	ftrace_init_array_ops(tr, irqsoff_tracer_call);
596
597	/* Only toplevel instance supports graph tracing */
598	if (start_irqsoff_tracer(tr, (tr->flags & TRACE_ARRAY_FL_GLOBAL &&
599				      is_graph(tr))))
600		printk(KERN_ERR "failed to start irqsoff tracer\n");
601
602	irqsoff_busy = true;
603	return 0;
604}
605
606static void __irqsoff_tracer_reset(struct trace_array *tr)
607{
608	int lat_flag = save_flags & TRACE_ITER(LATENCY_FMT);
609	int overwrite_flag = save_flags & TRACE_ITER(OVERWRITE);
610	int pause_flag = save_flags & TRACE_ITER(PAUSE_ON_TRACE);
611
612	stop_irqsoff_tracer(tr, is_graph(tr));
613
614	set_tracer_flag(tr, TRACE_ITER(LATENCY_FMT), lat_flag);
615	set_tracer_flag(tr, TRACE_ITER(OVERWRITE), overwrite_flag);
616	set_tracer_flag(tr, TRACE_ITER(PAUSE_ON_TRACE), pause_flag);
617	ftrace_reset_array_ops(tr);
618
619	irqsoff_busy = false;
620}
621
622static void irqsoff_tracer_start(struct trace_array *tr)
623{
624	tracer_enabled = 1;
625}
626
627static void irqsoff_tracer_stop(struct trace_array *tr)
628{
629	tracer_enabled = 0;
630}
631
632#ifdef CONFIG_IRQSOFF_TRACER
633/*
634 * We are only interested in hardirq on/off events:
635 */
636void tracer_hardirqs_on(unsigned long a0, unsigned long a1)
637{
638	if (!preempt_trace(preempt_count()) && irq_trace())
639		stop_critical_timing(a0, a1);
640}
641NOKPROBE_SYMBOL(tracer_hardirqs_on);
642
643void tracer_hardirqs_off(unsigned long a0, unsigned long a1)
644{
645	if (!preempt_trace(preempt_count()) && irq_trace())
646		start_critical_timing(a0, a1);
647}
648NOKPROBE_SYMBOL(tracer_hardirqs_off);
649
650static int irqsoff_tracer_init(struct trace_array *tr)
651{
652	trace_type = TRACER_IRQS_OFF;
653
654	return __irqsoff_tracer_init(tr);
655}
656
657static void irqsoff_tracer_reset(struct trace_array *tr)
658{
659	__irqsoff_tracer_reset(tr);
660}
661
662static struct tracer irqsoff_tracer __read_mostly =
663{
664	.name		= "irqsoff",
665	.init		= irqsoff_tracer_init,
666	.reset		= irqsoff_tracer_reset,
667	.start		= irqsoff_tracer_start,
668	.stop		= irqsoff_tracer_stop,
669	.print_max	= true,
670	.print_header   = irqsoff_print_header,
671	.print_line     = irqsoff_print_line,
672	.flag_changed	= irqsoff_flag_changed,
673#ifdef CONFIG_FTRACE_SELFTEST
674	.selftest    = trace_selftest_startup_irqsoff,
675#endif
676	.open           = irqsoff_trace_open,
677	.close          = irqsoff_trace_close,
678	.allow_instances = true,
679	.use_max_tr	= true,
680};
681#endif /*  CONFIG_IRQSOFF_TRACER */
682
683#ifdef CONFIG_PREEMPT_TRACER
684void tracer_preempt_on(unsigned long a0, unsigned long a1)
685{
686	if (preempt_trace(preempt_count()) && !irq_trace())
687		stop_critical_timing(a0, a1);
688}
689
690void tracer_preempt_off(unsigned long a0, unsigned long a1)
691{
692	if (preempt_trace(preempt_count()) && !irq_trace())
693		start_critical_timing(a0, a1);
694}
695
696static int preemptoff_tracer_init(struct trace_array *tr)
697{
698	trace_type = TRACER_PREEMPT_OFF;
699
700	return __irqsoff_tracer_init(tr);
701}
702
703static void preemptoff_tracer_reset(struct trace_array *tr)
704{
705	__irqsoff_tracer_reset(tr);
706}
707
708static struct tracer preemptoff_tracer __read_mostly =
709{
710	.name		= "preemptoff",
711	.init		= preemptoff_tracer_init,
712	.reset		= preemptoff_tracer_reset,
713	.start		= irqsoff_tracer_start,
714	.stop		= irqsoff_tracer_stop,
715	.print_max	= true,
716	.print_header   = irqsoff_print_header,
717	.print_line     = irqsoff_print_line,
718	.flag_changed	= irqsoff_flag_changed,
719#ifdef CONFIG_FTRACE_SELFTEST
720	.selftest    = trace_selftest_startup_preemptoff,
721#endif
722	.open		= irqsoff_trace_open,
723	.close		= irqsoff_trace_close,
724	.allow_instances = true,
725	.use_max_tr	= true,
726};
727#endif /* CONFIG_PREEMPT_TRACER */
728
729#if defined(CONFIG_IRQSOFF_TRACER) && defined(CONFIG_PREEMPT_TRACER)
730
731static int preemptirqsoff_tracer_init(struct trace_array *tr)
732{
733	trace_type = TRACER_IRQS_OFF | TRACER_PREEMPT_OFF;
734
735	return __irqsoff_tracer_init(tr);
736}
737
738static void preemptirqsoff_tracer_reset(struct trace_array *tr)
739{
740	__irqsoff_tracer_reset(tr);
741}
742
743static struct tracer preemptirqsoff_tracer __read_mostly =
744{
745	.name		= "preemptirqsoff",
746	.init		= preemptirqsoff_tracer_init,
747	.reset		= preemptirqsoff_tracer_reset,
748	.start		= irqsoff_tracer_start,
749	.stop		= irqsoff_tracer_stop,
750	.print_max	= true,
751	.print_header   = irqsoff_print_header,
752	.print_line     = irqsoff_print_line,
753	.flag_changed	= irqsoff_flag_changed,
754#ifdef CONFIG_FTRACE_SELFTEST
755	.selftest    = trace_selftest_startup_preemptirqsoff,
756#endif
757	.open		= irqsoff_trace_open,
758	.close		= irqsoff_trace_close,
759	.allow_instances = true,
760	.use_max_tr	= true,
761};
762#endif
763
764__init static int init_irqsoff_tracer(void)
765{
766#ifdef CONFIG_IRQSOFF_TRACER
767	register_tracer(&irqsoff_tracer);
768#endif
769#ifdef CONFIG_PREEMPT_TRACER
770	register_tracer(&preemptoff_tracer);
771#endif
772#if defined(CONFIG_IRQSOFF_TRACER) && defined(CONFIG_PREEMPT_TRACER)
773	register_tracer(&preemptirqsoff_tracer);
774#endif
775
776	return 0;
777}
778core_initcall(init_irqsoff_tracer);
779#endif /* IRQSOFF_TRACER || PREEMPTOFF_TRACER */