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1/*
2 * trace irqs off critical timings
3 *
4 * Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com>
5 * Copyright (C) 2008 Ingo Molnar <mingo@redhat.com>
6 *
7 * From code in the latency_tracer, that is:
8 *
9 * Copyright (C) 2004-2006 Ingo Molnar
10 * Copyright (C) 2004 Nadia Yvette Chambers
11 */
12#include <linux/kallsyms.h>
13#include <linux/debugfs.h>
14#include <linux/uaccess.h>
15#include <linux/module.h>
16#include <linux/ftrace.h>
17#include <linux/fs.h>
18
19#include "trace.h"
20
21static struct trace_array *irqsoff_trace __read_mostly;
22static int tracer_enabled __read_mostly;
23
24static DEFINE_PER_CPU(int, tracing_cpu);
25
26static DEFINE_RAW_SPINLOCK(max_trace_lock);
27
28enum {
29 TRACER_IRQS_OFF = (1 << 1),
30 TRACER_PREEMPT_OFF = (1 << 2),
31};
32
33static int trace_type __read_mostly;
34
35static int save_flags;
36static bool function_enabled;
37
38static void stop_irqsoff_tracer(struct trace_array *tr, int graph);
39static int start_irqsoff_tracer(struct trace_array *tr, int graph);
40
41#ifdef CONFIG_PREEMPT_TRACER
42static inline int
43preempt_trace(void)
44{
45 return ((trace_type & TRACER_PREEMPT_OFF) && preempt_count());
46}
47#else
48# define preempt_trace() (0)
49#endif
50
51#ifdef CONFIG_IRQSOFF_TRACER
52static inline int
53irq_trace(void)
54{
55 return ((trace_type & TRACER_IRQS_OFF) &&
56 irqs_disabled());
57}
58#else
59# define irq_trace() (0)
60#endif
61
62#define TRACE_DISPLAY_GRAPH 1
63
64static struct tracer_opt trace_opts[] = {
65#ifdef CONFIG_FUNCTION_GRAPH_TRACER
66 /* display latency trace as call graph */
67 { TRACER_OPT(display-graph, TRACE_DISPLAY_GRAPH) },
68#endif
69 { } /* Empty entry */
70};
71
72static struct tracer_flags tracer_flags = {
73 .val = 0,
74 .opts = trace_opts,
75};
76
77#define is_graph() (tracer_flags.val & TRACE_DISPLAY_GRAPH)
78
79/*
80 * Sequence count - we record it when starting a measurement and
81 * skip the latency if the sequence has changed - some other section
82 * did a maximum and could disturb our measurement with serial console
83 * printouts, etc. Truly coinciding maximum latencies should be rare
84 * and what happens together happens separately as well, so this doesn't
85 * decrease the validity of the maximum found:
86 */
87static __cacheline_aligned_in_smp unsigned long max_sequence;
88
89#ifdef CONFIG_FUNCTION_TRACER
90/*
91 * Prologue for the preempt and irqs off function tracers.
92 *
93 * Returns 1 if it is OK to continue, and data->disabled is
94 * incremented.
95 * 0 if the trace is to be ignored, and data->disabled
96 * is kept the same.
97 *
98 * Note, this function is also used outside this ifdef but
99 * inside the #ifdef of the function graph tracer below.
100 * This is OK, since the function graph tracer is
101 * dependent on the function tracer.
102 */
103static int func_prolog_dec(struct trace_array *tr,
104 struct trace_array_cpu **data,
105 unsigned long *flags)
106{
107 long disabled;
108 int cpu;
109
110 /*
111 * Does not matter if we preempt. We test the flags
112 * afterward, to see if irqs are disabled or not.
113 * If we preempt and get a false positive, the flags
114 * test will fail.
115 */
116 cpu = raw_smp_processor_id();
117 if (likely(!per_cpu(tracing_cpu, cpu)))
118 return 0;
119
120 local_save_flags(*flags);
121 /* slight chance to get a false positive on tracing_cpu */
122 if (!irqs_disabled_flags(*flags))
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 */
139static void
140irqsoff_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
155static struct ftrace_ops trace_ops __read_mostly =
156{
157 .func = irqsoff_tracer_call,
158 .flags = FTRACE_OPS_FL_GLOBAL | FTRACE_OPS_FL_RECURSION_SAFE,
159};
160#endif /* CONFIG_FUNCTION_TRACER */
161
162#ifdef CONFIG_FUNCTION_GRAPH_TRACER
163static int
164irqsoff_set_flag(struct trace_array *tr, u32 old_flags, u32 bit, int set)
165{
166 int cpu;
167
168 if (!(bit & TRACE_DISPLAY_GRAPH))
169 return -EINVAL;
170
171 if (!(is_graph() ^ set))
172 return 0;
173
174 stop_irqsoff_tracer(irqsoff_trace, !set);
175
176 for_each_possible_cpu(cpu)
177 per_cpu(tracing_cpu, cpu) = 0;
178
179 tracing_max_latency = 0;
180 tracing_reset_online_cpus(&irqsoff_trace->trace_buffer);
181
182 return start_irqsoff_tracer(irqsoff_trace, set);
183}
184
185static int irqsoff_graph_entry(struct ftrace_graph_ent *trace)
186{
187 struct trace_array *tr = irqsoff_trace;
188 struct trace_array_cpu *data;
189 unsigned long flags;
190 int ret;
191 int pc;
192
193 if (!func_prolog_dec(tr, &data, &flags))
194 return 0;
195
196 pc = preempt_count();
197 ret = __trace_graph_entry(tr, trace, flags, pc);
198 atomic_dec(&data->disabled);
199
200 return ret;
201}
202
203static void irqsoff_graph_return(struct ftrace_graph_ret *trace)
204{
205 struct trace_array *tr = irqsoff_trace;
206 struct trace_array_cpu *data;
207 unsigned long flags;
208 int pc;
209
210 if (!func_prolog_dec(tr, &data, &flags))
211 return;
212
213 pc = preempt_count();
214 __trace_graph_return(tr, trace, flags, pc);
215 atomic_dec(&data->disabled);
216}
217
218static void irqsoff_trace_open(struct trace_iterator *iter)
219{
220 if (is_graph())
221 graph_trace_open(iter);
222
223}
224
225static void irqsoff_trace_close(struct trace_iterator *iter)
226{
227 if (iter->private)
228 graph_trace_close(iter);
229}
230
231#define GRAPH_TRACER_FLAGS (TRACE_GRAPH_PRINT_CPU | \
232 TRACE_GRAPH_PRINT_PROC | \
233 TRACE_GRAPH_PRINT_ABS_TIME | \
234 TRACE_GRAPH_PRINT_DURATION)
235
236static enum print_line_t irqsoff_print_line(struct trace_iterator *iter)
237{
238 /*
239 * In graph mode call the graph tracer output function,
240 * otherwise go with the TRACE_FN event handler
241 */
242 if (is_graph())
243 return print_graph_function_flags(iter, GRAPH_TRACER_FLAGS);
244
245 return TRACE_TYPE_UNHANDLED;
246}
247
248static void irqsoff_print_header(struct seq_file *s)
249{
250 if (is_graph())
251 print_graph_headers_flags(s, GRAPH_TRACER_FLAGS);
252 else
253 trace_default_header(s);
254}
255
256static void
257__trace_function(struct trace_array *tr,
258 unsigned long ip, unsigned long parent_ip,
259 unsigned long flags, int pc)
260{
261 if (is_graph())
262 trace_graph_function(tr, ip, parent_ip, flags, pc);
263 else
264 trace_function(tr, ip, parent_ip, flags, pc);
265}
266
267#else
268#define __trace_function trace_function
269
270static int
271irqsoff_set_flag(struct trace_array *tr, u32 old_flags, u32 bit, int set)
272{
273 return -EINVAL;
274}
275
276static int irqsoff_graph_entry(struct ftrace_graph_ent *trace)
277{
278 return -1;
279}
280
281static enum print_line_t irqsoff_print_line(struct trace_iterator *iter)
282{
283 return TRACE_TYPE_UNHANDLED;
284}
285
286static void irqsoff_graph_return(struct ftrace_graph_ret *trace) { }
287static void irqsoff_trace_open(struct trace_iterator *iter) { }
288static void irqsoff_trace_close(struct trace_iterator *iter) { }
289
290#ifdef CONFIG_FUNCTION_TRACER
291static void irqsoff_print_header(struct seq_file *s)
292{
293 trace_default_header(s);
294}
295#else
296static void irqsoff_print_header(struct seq_file *s)
297{
298 trace_latency_header(s);
299}
300#endif /* CONFIG_FUNCTION_TRACER */
301#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
302
303/*
304 * Should this new latency be reported/recorded?
305 */
306static int report_latency(cycle_t delta)
307{
308 if (tracing_thresh) {
309 if (delta < tracing_thresh)
310 return 0;
311 } else {
312 if (delta <= tracing_max_latency)
313 return 0;
314 }
315 return 1;
316}
317
318static void
319check_critical_timing(struct trace_array *tr,
320 struct trace_array_cpu *data,
321 unsigned long parent_ip,
322 int cpu)
323{
324 cycle_t T0, T1, delta;
325 unsigned long flags;
326 int pc;
327
328 T0 = data->preempt_timestamp;
329 T1 = ftrace_now(cpu);
330 delta = T1-T0;
331
332 local_save_flags(flags);
333
334 pc = preempt_count();
335
336 if (!report_latency(delta))
337 goto out;
338
339 raw_spin_lock_irqsave(&max_trace_lock, flags);
340
341 /* check if we are still the max latency */
342 if (!report_latency(delta))
343 goto out_unlock;
344
345 __trace_function(tr, CALLER_ADDR0, parent_ip, flags, pc);
346 /* Skip 5 functions to get to the irq/preempt enable function */
347 __trace_stack(tr, flags, 5, pc);
348
349 if (data->critical_sequence != max_sequence)
350 goto out_unlock;
351
352 data->critical_end = parent_ip;
353
354 if (likely(!is_tracing_stopped())) {
355 tracing_max_latency = delta;
356 update_max_tr_single(tr, current, cpu);
357 }
358
359 max_sequence++;
360
361out_unlock:
362 raw_spin_unlock_irqrestore(&max_trace_lock, flags);
363
364out:
365 data->critical_sequence = max_sequence;
366 data->preempt_timestamp = ftrace_now(cpu);
367 __trace_function(tr, CALLER_ADDR0, parent_ip, flags, pc);
368}
369
370static inline void
371start_critical_timing(unsigned long ip, unsigned long parent_ip)
372{
373 int cpu;
374 struct trace_array *tr = irqsoff_trace;
375 struct trace_array_cpu *data;
376 unsigned long flags;
377
378 if (!tracer_enabled || !tracing_is_enabled())
379 return;
380
381 cpu = raw_smp_processor_id();
382
383 if (per_cpu(tracing_cpu, cpu))
384 return;
385
386 data = per_cpu_ptr(tr->trace_buffer.data, cpu);
387
388 if (unlikely(!data) || atomic_read(&data->disabled))
389 return;
390
391 atomic_inc(&data->disabled);
392
393 data->critical_sequence = max_sequence;
394 data->preempt_timestamp = ftrace_now(cpu);
395 data->critical_start = parent_ip ? : ip;
396
397 local_save_flags(flags);
398
399 __trace_function(tr, ip, parent_ip, flags, preempt_count());
400
401 per_cpu(tracing_cpu, cpu) = 1;
402
403 atomic_dec(&data->disabled);
404}
405
406static inline void
407stop_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 long flags;
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->trace_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 local_save_flags(flags);
433 __trace_function(tr, ip, parent_ip, flags, preempt_count());
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) */
440void start_critical_timings(void)
441{
442 if (preempt_trace() || irq_trace())
443 start_critical_timing(CALLER_ADDR0, CALLER_ADDR1);
444}
445EXPORT_SYMBOL_GPL(start_critical_timings);
446
447void stop_critical_timings(void)
448{
449 if (preempt_trace() || irq_trace())
450 stop_critical_timing(CALLER_ADDR0, CALLER_ADDR1);
451}
452EXPORT_SYMBOL_GPL(stop_critical_timings);
453
454#ifdef CONFIG_IRQSOFF_TRACER
455#ifdef CONFIG_PROVE_LOCKING
456void time_hardirqs_on(unsigned long a0, unsigned long a1)
457{
458 if (!preempt_trace() && irq_trace())
459 stop_critical_timing(a0, a1);
460}
461
462void time_hardirqs_off(unsigned long a0, unsigned long a1)
463{
464 if (!preempt_trace() && irq_trace())
465 start_critical_timing(a0, a1);
466}
467
468#else /* !CONFIG_PROVE_LOCKING */
469
470/*
471 * Stubs:
472 */
473
474void trace_softirqs_on(unsigned long ip)
475{
476}
477
478void trace_softirqs_off(unsigned long ip)
479{
480}
481
482inline void print_irqtrace_events(struct task_struct *curr)
483{
484}
485
486/*
487 * We are only interested in hardirq on/off events:
488 */
489void trace_hardirqs_on(void)
490{
491 if (!preempt_trace() && irq_trace())
492 stop_critical_timing(CALLER_ADDR0, CALLER_ADDR1);
493}
494EXPORT_SYMBOL(trace_hardirqs_on);
495
496void trace_hardirqs_off(void)
497{
498 if (!preempt_trace() && irq_trace())
499 start_critical_timing(CALLER_ADDR0, CALLER_ADDR1);
500}
501EXPORT_SYMBOL(trace_hardirqs_off);
502
503__visible void trace_hardirqs_on_caller(unsigned long caller_addr)
504{
505 if (!preempt_trace() && irq_trace())
506 stop_critical_timing(CALLER_ADDR0, caller_addr);
507}
508EXPORT_SYMBOL(trace_hardirqs_on_caller);
509
510__visible void trace_hardirqs_off_caller(unsigned long caller_addr)
511{
512 if (!preempt_trace() && irq_trace())
513 start_critical_timing(CALLER_ADDR0, caller_addr);
514}
515EXPORT_SYMBOL(trace_hardirqs_off_caller);
516
517#endif /* CONFIG_PROVE_LOCKING */
518#endif /* CONFIG_IRQSOFF_TRACER */
519
520#ifdef CONFIG_PREEMPT_TRACER
521void trace_preempt_on(unsigned long a0, unsigned long a1)
522{
523 if (preempt_trace() && !irq_trace())
524 stop_critical_timing(a0, a1);
525}
526
527void trace_preempt_off(unsigned long a0, unsigned long a1)
528{
529 if (preempt_trace() && !irq_trace())
530 start_critical_timing(a0, a1);
531}
532#endif /* CONFIG_PREEMPT_TRACER */
533
534static int register_irqsoff_function(int graph, int set)
535{
536 int ret;
537
538 /* 'set' is set if TRACE_ITER_FUNCTION is about to be set */
539 if (function_enabled || (!set && !(trace_flags & TRACE_ITER_FUNCTION)))
540 return 0;
541
542 if (graph)
543 ret = register_ftrace_graph(&irqsoff_graph_return,
544 &irqsoff_graph_entry);
545 else
546 ret = register_ftrace_function(&trace_ops);
547
548 if (!ret)
549 function_enabled = true;
550
551 return ret;
552}
553
554static void unregister_irqsoff_function(int graph)
555{
556 if (!function_enabled)
557 return;
558
559 if (graph)
560 unregister_ftrace_graph();
561 else
562 unregister_ftrace_function(&trace_ops);
563
564 function_enabled = false;
565}
566
567static void irqsoff_function_set(int set)
568{
569 if (set)
570 register_irqsoff_function(is_graph(), 1);
571 else
572 unregister_irqsoff_function(is_graph());
573}
574
575static int irqsoff_flag_changed(struct trace_array *tr, u32 mask, int set)
576{
577 struct tracer *tracer = tr->current_trace;
578
579 if (mask & TRACE_ITER_FUNCTION)
580 irqsoff_function_set(set);
581
582 return trace_keep_overwrite(tracer, mask, set);
583}
584
585static int start_irqsoff_tracer(struct trace_array *tr, int graph)
586{
587 int ret;
588
589 ret = register_irqsoff_function(graph, 0);
590
591 if (!ret && tracing_is_enabled())
592 tracer_enabled = 1;
593 else
594 tracer_enabled = 0;
595
596 return ret;
597}
598
599static void stop_irqsoff_tracer(struct trace_array *tr, int graph)
600{
601 tracer_enabled = 0;
602
603 unregister_irqsoff_function(graph);
604}
605
606static void __irqsoff_tracer_init(struct trace_array *tr)
607{
608 save_flags = trace_flags;
609
610 /* non overwrite screws up the latency tracers */
611 set_tracer_flag(tr, TRACE_ITER_OVERWRITE, 1);
612 set_tracer_flag(tr, TRACE_ITER_LATENCY_FMT, 1);
613
614 tracing_max_latency = 0;
615 irqsoff_trace = tr;
616 /* make sure that the tracer is visible */
617 smp_wmb();
618 tracing_reset_online_cpus(&tr->trace_buffer);
619
620 if (start_irqsoff_tracer(tr, is_graph()))
621 printk(KERN_ERR "failed to start irqsoff tracer\n");
622}
623
624static void irqsoff_tracer_reset(struct trace_array *tr)
625{
626 int lat_flag = save_flags & TRACE_ITER_LATENCY_FMT;
627 int overwrite_flag = save_flags & TRACE_ITER_OVERWRITE;
628
629 stop_irqsoff_tracer(tr, is_graph());
630
631 set_tracer_flag(tr, TRACE_ITER_LATENCY_FMT, lat_flag);
632 set_tracer_flag(tr, TRACE_ITER_OVERWRITE, overwrite_flag);
633}
634
635static void irqsoff_tracer_start(struct trace_array *tr)
636{
637 tracer_enabled = 1;
638}
639
640static void irqsoff_tracer_stop(struct trace_array *tr)
641{
642 tracer_enabled = 0;
643}
644
645#ifdef CONFIG_IRQSOFF_TRACER
646static int irqsoff_tracer_init(struct trace_array *tr)
647{
648 trace_type = TRACER_IRQS_OFF;
649
650 __irqsoff_tracer_init(tr);
651 return 0;
652}
653static struct tracer irqsoff_tracer __read_mostly =
654{
655 .name = "irqsoff",
656 .init = irqsoff_tracer_init,
657 .reset = irqsoff_tracer_reset,
658 .start = irqsoff_tracer_start,
659 .stop = irqsoff_tracer_stop,
660 .print_max = true,
661 .print_header = irqsoff_print_header,
662 .print_line = irqsoff_print_line,
663 .flags = &tracer_flags,
664 .set_flag = irqsoff_set_flag,
665 .flag_changed = irqsoff_flag_changed,
666#ifdef CONFIG_FTRACE_SELFTEST
667 .selftest = trace_selftest_startup_irqsoff,
668#endif
669 .open = irqsoff_trace_open,
670 .close = irqsoff_trace_close,
671 .use_max_tr = true,
672};
673# define register_irqsoff(trace) register_tracer(&trace)
674#else
675# define register_irqsoff(trace) do { } while (0)
676#endif
677
678#ifdef CONFIG_PREEMPT_TRACER
679static int preemptoff_tracer_init(struct trace_array *tr)
680{
681 trace_type = TRACER_PREEMPT_OFF;
682
683 __irqsoff_tracer_init(tr);
684 return 0;
685}
686
687static struct tracer preemptoff_tracer __read_mostly =
688{
689 .name = "preemptoff",
690 .init = preemptoff_tracer_init,
691 .reset = irqsoff_tracer_reset,
692 .start = irqsoff_tracer_start,
693 .stop = irqsoff_tracer_stop,
694 .print_max = true,
695 .print_header = irqsoff_print_header,
696 .print_line = irqsoff_print_line,
697 .flags = &tracer_flags,
698 .set_flag = irqsoff_set_flag,
699 .flag_changed = irqsoff_flag_changed,
700#ifdef CONFIG_FTRACE_SELFTEST
701 .selftest = trace_selftest_startup_preemptoff,
702#endif
703 .open = irqsoff_trace_open,
704 .close = irqsoff_trace_close,
705 .use_max_tr = true,
706};
707# define register_preemptoff(trace) register_tracer(&trace)
708#else
709# define register_preemptoff(trace) do { } while (0)
710#endif
711
712#if defined(CONFIG_IRQSOFF_TRACER) && \
713 defined(CONFIG_PREEMPT_TRACER)
714
715static int preemptirqsoff_tracer_init(struct trace_array *tr)
716{
717 trace_type = TRACER_IRQS_OFF | TRACER_PREEMPT_OFF;
718
719 __irqsoff_tracer_init(tr);
720 return 0;
721}
722
723static struct tracer preemptirqsoff_tracer __read_mostly =
724{
725 .name = "preemptirqsoff",
726 .init = preemptirqsoff_tracer_init,
727 .reset = irqsoff_tracer_reset,
728 .start = irqsoff_tracer_start,
729 .stop = irqsoff_tracer_stop,
730 .print_max = true,
731 .print_header = irqsoff_print_header,
732 .print_line = irqsoff_print_line,
733 .flags = &tracer_flags,
734 .set_flag = irqsoff_set_flag,
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 .use_max_tr = true,
742};
743
744# define register_preemptirqsoff(trace) register_tracer(&trace)
745#else
746# define register_preemptirqsoff(trace) do { } while (0)
747#endif
748
749__init static int init_irqsoff_tracer(void)
750{
751 register_irqsoff(irqsoff_tracer);
752 register_preemptoff(preemptoff_tracer);
753 register_preemptirqsoff(preemptirqsoff_tracer);
754
755 return 0;
756}
757core_initcall(init_irqsoff_tracer);
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 = 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 */
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);
154
155 atomic_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{
181 struct trace_array *tr = irqsoff_trace;
182 struct trace_array_cpu *data;
183 unsigned long flags;
184 unsigned int trace_ctx;
185 u64 *calltime;
186 int ret;
187
188 if (ftrace_graph_ignore_func(gops, trace))
189 return 0;
190 /*
191 * Do not trace a function if it's filtered by set_graph_notrace.
192 * Make the index of ret stack negative to indicate that it should
193 * ignore further functions. But it needs its own ret stack entry
194 * to recover the original index in order to continue tracing after
195 * returning from the function.
196 */
197 if (ftrace_graph_notrace_addr(trace->func))
198 return 1;
199
200 if (!func_prolog_dec(tr, &data, &flags))
201 return 0;
202
203 calltime = fgraph_reserve_data(gops->idx, sizeof(*calltime));
204 if (!calltime)
205 return 0;
206
207 *calltime = trace_clock_local();
208
209 trace_ctx = tracing_gen_ctx_flags(flags);
210 ret = __trace_graph_entry(tr, trace, trace_ctx);
211 atomic_dec(&data->disabled);
212
213 return ret;
214}
215
216static void irqsoff_graph_return(struct ftrace_graph_ret *trace,
217 struct fgraph_ops *gops)
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 int size;
225
226 ftrace_graph_addr_finish(gops, trace);
227
228 if (!func_prolog_dec(tr, &data, &flags))
229 return;
230
231 calltime = fgraph_retrieve_data(gops->idx, &size);
232 if (!calltime)
233 return;
234 trace->calltime = *calltime;
235
236 trace_ctx = tracing_gen_ctx_flags(flags);
237 __trace_graph_return(tr, trace, trace_ctx);
238 atomic_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 else
251 iter->private = NULL;
252}
253
254static void irqsoff_trace_close(struct trace_iterator *iter)
255{
256 if (iter->private)
257 graph_trace_close(iter);
258}
259
260#define GRAPH_TRACER_FLAGS (TRACE_GRAPH_PRINT_CPU | \
261 TRACE_GRAPH_PRINT_PROC | \
262 TRACE_GRAPH_PRINT_REL_TIME | \
263 TRACE_GRAPH_PRINT_DURATION)
264
265static enum print_line_t irqsoff_print_line(struct trace_iterator *iter)
266{
267 /*
268 * In graph mode call the graph tracer output function,
269 * otherwise go with the TRACE_FN event handler
270 */
271 if (is_graph(iter->tr))
272 return print_graph_function_flags(iter, GRAPH_TRACER_FLAGS);
273
274 return TRACE_TYPE_UNHANDLED;
275}
276
277static void irqsoff_print_header(struct seq_file *s)
278{
279 struct trace_array *tr = irqsoff_trace;
280
281 if (is_graph(tr))
282 print_graph_headers_flags(s, GRAPH_TRACER_FLAGS);
283 else
284 trace_default_header(s);
285}
286
287static void
288__trace_function(struct trace_array *tr,
289 unsigned long ip, unsigned long parent_ip,
290 unsigned int trace_ctx)
291{
292 if (is_graph(tr))
293 trace_graph_function(tr, ip, parent_ip, trace_ctx);
294 else
295 trace_function(tr, ip, parent_ip, trace_ctx);
296}
297
298#else
299#define __trace_function trace_function
300
301static enum print_line_t irqsoff_print_line(struct trace_iterator *iter)
302{
303 return TRACE_TYPE_UNHANDLED;
304}
305
306static void irqsoff_trace_open(struct trace_iterator *iter) { }
307static void irqsoff_trace_close(struct trace_iterator *iter) { }
308
309#ifdef CONFIG_FUNCTION_TRACER
310static void irqsoff_print_header(struct seq_file *s)
311{
312 trace_default_header(s);
313}
314#else
315static void irqsoff_print_header(struct seq_file *s)
316{
317 trace_latency_header(s);
318}
319#endif /* CONFIG_FUNCTION_TRACER */
320#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
321
322/*
323 * Should this new latency be reported/recorded?
324 */
325static bool report_latency(struct trace_array *tr, u64 delta)
326{
327 if (tracing_thresh) {
328 if (delta < tracing_thresh)
329 return false;
330 } else {
331 if (delta <= tr->max_latency)
332 return false;
333 }
334 return true;
335}
336
337static void
338check_critical_timing(struct trace_array *tr,
339 struct trace_array_cpu *data,
340 unsigned long parent_ip,
341 int cpu)
342{
343 u64 T0, T1, delta;
344 unsigned long flags;
345 unsigned int trace_ctx;
346
347 T0 = data->preempt_timestamp;
348 T1 = ftrace_now(cpu);
349 delta = T1-T0;
350
351 trace_ctx = tracing_gen_ctx();
352
353 if (!report_latency(tr, delta))
354 goto out;
355
356 raw_spin_lock_irqsave(&max_trace_lock, flags);
357
358 /* check if we are still the max latency */
359 if (!report_latency(tr, delta))
360 goto out_unlock;
361
362 __trace_function(tr, CALLER_ADDR0, parent_ip, trace_ctx);
363 /* Skip 5 functions to get to the irq/preempt enable function */
364 __trace_stack(tr, trace_ctx, 5);
365
366 if (data->critical_sequence != max_sequence)
367 goto out_unlock;
368
369 data->critical_end = parent_ip;
370
371 if (likely(!is_tracing_stopped())) {
372 tr->max_latency = delta;
373 update_max_tr_single(tr, current, cpu);
374 }
375
376 max_sequence++;
377
378out_unlock:
379 raw_spin_unlock_irqrestore(&max_trace_lock, flags);
380
381out:
382 data->critical_sequence = max_sequence;
383 data->preempt_timestamp = ftrace_now(cpu);
384 __trace_function(tr, CALLER_ADDR0, parent_ip, trace_ctx);
385}
386
387static nokprobe_inline void
388start_critical_timing(unsigned long ip, unsigned long parent_ip)
389{
390 int cpu;
391 struct trace_array *tr = irqsoff_trace;
392 struct trace_array_cpu *data;
393
394 if (!tracer_enabled || !tracing_is_enabled())
395 return;
396
397 cpu = raw_smp_processor_id();
398
399 if (per_cpu(tracing_cpu, cpu))
400 return;
401
402 data = per_cpu_ptr(tr->array_buffer.data, cpu);
403
404 if (unlikely(!data) || atomic_read(&data->disabled))
405 return;
406
407 atomic_inc(&data->disabled);
408
409 data->critical_sequence = max_sequence;
410 data->preempt_timestamp = ftrace_now(cpu);
411 data->critical_start = parent_ip ? : ip;
412
413 __trace_function(tr, ip, parent_ip, tracing_gen_ctx());
414
415 per_cpu(tracing_cpu, cpu) = 1;
416
417 atomic_dec(&data->disabled);
418}
419
420static nokprobe_inline void
421stop_critical_timing(unsigned long ip, unsigned long parent_ip)
422{
423 int cpu;
424 struct trace_array *tr = irqsoff_trace;
425 struct trace_array_cpu *data;
426 unsigned int trace_ctx;
427
428 cpu = raw_smp_processor_id();
429 /* Always clear the tracing cpu on stopping the trace */
430 if (unlikely(per_cpu(tracing_cpu, cpu)))
431 per_cpu(tracing_cpu, cpu) = 0;
432 else
433 return;
434
435 if (!tracer_enabled || !tracing_is_enabled())
436 return;
437
438 data = per_cpu_ptr(tr->array_buffer.data, cpu);
439
440 if (unlikely(!data) ||
441 !data->critical_start || atomic_read(&data->disabled))
442 return;
443
444 atomic_inc(&data->disabled);
445
446 trace_ctx = tracing_gen_ctx();
447 __trace_function(tr, ip, parent_ip, trace_ctx);
448 check_critical_timing(tr, data, parent_ip ? : ip, cpu);
449 data->critical_start = 0;
450 atomic_dec(&data->disabled);
451}
452
453/* start and stop critical timings used to for stoppage (in idle) */
454void start_critical_timings(void)
455{
456 if (preempt_trace(preempt_count()) || irq_trace())
457 start_critical_timing(CALLER_ADDR0, CALLER_ADDR1);
458}
459EXPORT_SYMBOL_GPL(start_critical_timings);
460NOKPROBE_SYMBOL(start_critical_timings);
461
462void stop_critical_timings(void)
463{
464 if (preempt_trace(preempt_count()) || irq_trace())
465 stop_critical_timing(CALLER_ADDR0, CALLER_ADDR1);
466}
467EXPORT_SYMBOL_GPL(stop_critical_timings);
468NOKPROBE_SYMBOL(stop_critical_timings);
469
470#ifdef CONFIG_FUNCTION_TRACER
471static bool function_enabled;
472
473static int register_irqsoff_function(struct trace_array *tr, int graph, int set)
474{
475 int ret;
476
477 /* 'set' is set if TRACE_ITER_FUNCTION is about to be set */
478 if (function_enabled || (!set && !(tr->trace_flags & TRACE_ITER_FUNCTION)))
479 return 0;
480
481 if (graph)
482 ret = register_ftrace_graph(&fgraph_ops);
483 else
484 ret = register_ftrace_function(tr->ops);
485
486 if (!ret)
487 function_enabled = true;
488
489 return ret;
490}
491
492static void unregister_irqsoff_function(struct trace_array *tr, int graph)
493{
494 if (!function_enabled)
495 return;
496
497 if (graph)
498 unregister_ftrace_graph(&fgraph_ops);
499 else
500 unregister_ftrace_function(tr->ops);
501
502 function_enabled = false;
503}
504
505static int irqsoff_function_set(struct trace_array *tr, u32 mask, int set)
506{
507 if (!(mask & TRACE_ITER_FUNCTION))
508 return 0;
509
510 if (set)
511 register_irqsoff_function(tr, is_graph(tr), 1);
512 else
513 unregister_irqsoff_function(tr, is_graph(tr));
514 return 1;
515}
516#else
517static int register_irqsoff_function(struct trace_array *tr, int graph, int set)
518{
519 return 0;
520}
521static void unregister_irqsoff_function(struct trace_array *tr, int graph) { }
522static inline int irqsoff_function_set(struct trace_array *tr, u32 mask, int set)
523{
524 return 0;
525}
526#endif /* CONFIG_FUNCTION_TRACER */
527
528static int irqsoff_flag_changed(struct trace_array *tr, u32 mask, int set)
529{
530 struct tracer *tracer = tr->current_trace;
531
532 if (irqsoff_function_set(tr, mask, set))
533 return 0;
534
535#ifdef CONFIG_FUNCTION_GRAPH_TRACER
536 if (mask & TRACE_ITER_DISPLAY_GRAPH)
537 return irqsoff_display_graph(tr, set);
538#endif
539
540 return trace_keep_overwrite(tracer, mask, set);
541}
542
543static int start_irqsoff_tracer(struct trace_array *tr, int graph)
544{
545 int ret;
546
547 ret = register_irqsoff_function(tr, graph, 0);
548
549 if (!ret && tracing_is_enabled())
550 tracer_enabled = 1;
551 else
552 tracer_enabled = 0;
553
554 return ret;
555}
556
557static void stop_irqsoff_tracer(struct trace_array *tr, int graph)
558{
559 tracer_enabled = 0;
560
561 unregister_irqsoff_function(tr, graph);
562}
563
564static bool irqsoff_busy;
565
566static int __irqsoff_tracer_init(struct trace_array *tr)
567{
568 if (irqsoff_busy)
569 return -EBUSY;
570
571 save_flags = tr->trace_flags;
572
573 /* non overwrite screws up the latency tracers */
574 set_tracer_flag(tr, TRACE_ITER_OVERWRITE, 1);
575 set_tracer_flag(tr, TRACE_ITER_LATENCY_FMT, 1);
576 /* without pause, we will produce garbage if another latency occurs */
577 set_tracer_flag(tr, TRACE_ITER_PAUSE_ON_TRACE, 1);
578
579 tr->max_latency = 0;
580 irqsoff_trace = tr;
581 /* make sure that the tracer is visible */
582 smp_wmb();
583
584 ftrace_init_array_ops(tr, irqsoff_tracer_call);
585
586 /* Only toplevel instance supports graph tracing */
587 if (start_irqsoff_tracer(tr, (tr->flags & TRACE_ARRAY_FL_GLOBAL &&
588 is_graph(tr))))
589 printk(KERN_ERR "failed to start irqsoff tracer\n");
590
591 irqsoff_busy = true;
592 return 0;
593}
594
595static void __irqsoff_tracer_reset(struct trace_array *tr)
596{
597 int lat_flag = save_flags & TRACE_ITER_LATENCY_FMT;
598 int overwrite_flag = save_flags & TRACE_ITER_OVERWRITE;
599 int pause_flag = save_flags & TRACE_ITER_PAUSE_ON_TRACE;
600
601 stop_irqsoff_tracer(tr, is_graph(tr));
602
603 set_tracer_flag(tr, TRACE_ITER_LATENCY_FMT, lat_flag);
604 set_tracer_flag(tr, TRACE_ITER_OVERWRITE, overwrite_flag);
605 set_tracer_flag(tr, TRACE_ITER_PAUSE_ON_TRACE, pause_flag);
606 ftrace_reset_array_ops(tr);
607
608 irqsoff_busy = false;
609}
610
611static void irqsoff_tracer_start(struct trace_array *tr)
612{
613 tracer_enabled = 1;
614}
615
616static void irqsoff_tracer_stop(struct trace_array *tr)
617{
618 tracer_enabled = 0;
619}
620
621#ifdef CONFIG_IRQSOFF_TRACER
622/*
623 * We are only interested in hardirq on/off events:
624 */
625void tracer_hardirqs_on(unsigned long a0, unsigned long a1)
626{
627 if (!preempt_trace(preempt_count()) && irq_trace())
628 stop_critical_timing(a0, a1);
629}
630NOKPROBE_SYMBOL(tracer_hardirqs_on);
631
632void tracer_hardirqs_off(unsigned long a0, unsigned long a1)
633{
634 if (!preempt_trace(preempt_count()) && irq_trace())
635 start_critical_timing(a0, a1);
636}
637NOKPROBE_SYMBOL(tracer_hardirqs_off);
638
639static int irqsoff_tracer_init(struct trace_array *tr)
640{
641 trace_type = TRACER_IRQS_OFF;
642
643 return __irqsoff_tracer_init(tr);
644}
645
646static void irqsoff_tracer_reset(struct trace_array *tr)
647{
648 __irqsoff_tracer_reset(tr);
649}
650
651static struct tracer irqsoff_tracer __read_mostly =
652{
653 .name = "irqsoff",
654 .init = irqsoff_tracer_init,
655 .reset = irqsoff_tracer_reset,
656 .start = irqsoff_tracer_start,
657 .stop = irqsoff_tracer_stop,
658 .print_max = true,
659 .print_header = irqsoff_print_header,
660 .print_line = irqsoff_print_line,
661 .flag_changed = irqsoff_flag_changed,
662#ifdef CONFIG_FTRACE_SELFTEST
663 .selftest = trace_selftest_startup_irqsoff,
664#endif
665 .open = irqsoff_trace_open,
666 .close = irqsoff_trace_close,
667 .allow_instances = true,
668 .use_max_tr = true,
669};
670#endif /* CONFIG_IRQSOFF_TRACER */
671
672#ifdef CONFIG_PREEMPT_TRACER
673void tracer_preempt_on(unsigned long a0, unsigned long a1)
674{
675 if (preempt_trace(preempt_count()) && !irq_trace())
676 stop_critical_timing(a0, a1);
677}
678
679void tracer_preempt_off(unsigned long a0, unsigned long a1)
680{
681 if (preempt_trace(preempt_count()) && !irq_trace())
682 start_critical_timing(a0, a1);
683}
684
685static int preemptoff_tracer_init(struct trace_array *tr)
686{
687 trace_type = TRACER_PREEMPT_OFF;
688
689 return __irqsoff_tracer_init(tr);
690}
691
692static void preemptoff_tracer_reset(struct trace_array *tr)
693{
694 __irqsoff_tracer_reset(tr);
695}
696
697static struct tracer preemptoff_tracer __read_mostly =
698{
699 .name = "preemptoff",
700 .init = preemptoff_tracer_init,
701 .reset = preemptoff_tracer_reset,
702 .start = irqsoff_tracer_start,
703 .stop = irqsoff_tracer_stop,
704 .print_max = true,
705 .print_header = irqsoff_print_header,
706 .print_line = irqsoff_print_line,
707 .flag_changed = irqsoff_flag_changed,
708#ifdef CONFIG_FTRACE_SELFTEST
709 .selftest = trace_selftest_startup_preemptoff,
710#endif
711 .open = irqsoff_trace_open,
712 .close = irqsoff_trace_close,
713 .allow_instances = true,
714 .use_max_tr = true,
715};
716#endif /* CONFIG_PREEMPT_TRACER */
717
718#if defined(CONFIG_IRQSOFF_TRACER) && defined(CONFIG_PREEMPT_TRACER)
719
720static int preemptirqsoff_tracer_init(struct trace_array *tr)
721{
722 trace_type = TRACER_IRQS_OFF | TRACER_PREEMPT_OFF;
723
724 return __irqsoff_tracer_init(tr);
725}
726
727static void preemptirqsoff_tracer_reset(struct trace_array *tr)
728{
729 __irqsoff_tracer_reset(tr);
730}
731
732static struct tracer preemptirqsoff_tracer __read_mostly =
733{
734 .name = "preemptirqsoff",
735 .init = preemptirqsoff_tracer_init,
736 .reset = preemptirqsoff_tracer_reset,
737 .start = irqsoff_tracer_start,
738 .stop = irqsoff_tracer_stop,
739 .print_max = true,
740 .print_header = irqsoff_print_header,
741 .print_line = irqsoff_print_line,
742 .flag_changed = irqsoff_flag_changed,
743#ifdef CONFIG_FTRACE_SELFTEST
744 .selftest = trace_selftest_startup_preemptirqsoff,
745#endif
746 .open = irqsoff_trace_open,
747 .close = irqsoff_trace_close,
748 .allow_instances = true,
749 .use_max_tr = true,
750};
751#endif
752
753__init static int init_irqsoff_tracer(void)
754{
755#ifdef CONFIG_IRQSOFF_TRACER
756 register_tracer(&irqsoff_tracer);
757#endif
758#ifdef CONFIG_PREEMPT_TRACER
759 register_tracer(&preemptoff_tracer);
760#endif
761#if defined(CONFIG_IRQSOFF_TRACER) && defined(CONFIG_PREEMPT_TRACER)
762 register_tracer(&preemptirqsoff_tracer);
763#endif
764
765 return 0;
766}
767core_initcall(init_irqsoff_tracer);
768#endif /* IRQSOFF_TRACER || PREEMPTOFF_TRACER */