trace.c 150 KB
Newer Older
1
2
3
/*
 * ring buffer based function tracer
 *
4
 * Copyright (C) 2007-2012 Steven Rostedt <srostedt@redhat.com>
5
6
7
8
9
10
11
 * Copyright (C) 2008 Ingo Molnar <mingo@redhat.com>
 *
 * Originally taken from the RT patch by:
 *    Arnaldo Carvalho de Melo <acme@redhat.com>
 *
 * Based on code from the latency_tracer, that is:
 *  Copyright (C) 2004-2006 Ingo Molnar
12
 *  Copyright (C) 2004 Nadia Yvette Chambers
13
 */
14
#include <linux/ring_buffer.h>
15
#include <generated/utsrelease.h>
16
17
#include <linux/stacktrace.h>
#include <linux/writeback.h>
18
19
#include <linux/kallsyms.h>
#include <linux/seq_file.h>
20
#include <linux/notifier.h>
21
#include <linux/irqflags.h>
22
#include <linux/debugfs.h>
23
#include <linux/pagemap.h>
24
25
26
#include <linux/hardirq.h>
#include <linux/linkage.h>
#include <linux/uaccess.h>
27
#include <linux/kprobes.h>
28
29
30
#include <linux/ftrace.h>
#include <linux/module.h>
#include <linux/percpu.h>
31
#include <linux/splice.h>
32
#include <linux/kdebug.h>
33
#include <linux/string.h>
34
#include <linux/rwsem.h>
35
#include <linux/slab.h>
36
37
#include <linux/ctype.h>
#include <linux/init.h>
38
#include <linux/poll.h>
39
#include <linux/nmi.h>
40
#include <linux/fs.h>
41
#include <linux/sched/rt.h>
Ingo Molnar's avatar
Ingo Molnar committed
42

43
#include "trace.h"
44
#include "trace_output.h"
45

46
47
48
49
/*
 * On boot up, the ring buffer is set to the minimum size, so that
 * we do not waste memory on systems that are not using tracing.
 */
50
bool ring_buffer_expanded;
51

52
53
/*
 * We need to change this state when a selftest is running.
54
55
 * A selftest will lurk into the ring-buffer to count the
 * entries inserted during the selftest although some concurrent
56
 * insertions into the ring-buffer such as trace_printk could occurred
57
58
 * at the same time, giving false positive or negative results.
 */
59
static bool __read_mostly tracing_selftest_running;
60

61
62
63
/*
 * If a tracer is running, we do not want to run SELFTEST.
 */
64
bool __read_mostly tracing_selftest_disabled;
65

66
67
68
69
70
71
72
73
74
75
76
77
78
79
/* For tracers that don't implement custom flags */
static struct tracer_opt dummy_tracer_opt[] = {
	{ }
};

static struct tracer_flags dummy_tracer_flags = {
	.val = 0,
	.opts = dummy_tracer_opt
};

static int dummy_set_flag(u32 old_flags, u32 bit, int set)
{
	return 0;
}
80

81
82
83
84
85
86
87
/*
 * To prevent the comm cache from being overwritten when no
 * tracing is active, only save the comm when a trace event
 * occurred.
 */
static DEFINE_PER_CPU(bool, trace_cmdline_save);

88
89
90
91
92
93
/*
 * Kill all tracing for good (never come back).
 * It is initialized to 1 but will turn to zero if the initialization
 * of the tracer is successful. But that is the only place that sets
 * this back to zero.
 */
94
static int tracing_disabled = 1;
95

96
DEFINE_PER_CPU(int, ftrace_cpu_disabled);
97

98
cpumask_var_t __read_mostly	tracing_buffer_mask;
99

100
101
102
103
104
105
106
107
108
109
110
/*
 * ftrace_dump_on_oops - variable to dump ftrace buffer on oops
 *
 * If there is an oops (or kernel panic) and the ftrace_dump_on_oops
 * is set, then ftrace_dump is called. This will output the contents
 * of the ftrace buffers to the console.  This is very useful for
 * capturing traces that lead to crashes and outputing it to a
 * serial console.
 *
 * It is default off, but you can enable it with either specifying
 * "ftrace_dump_on_oops" in the kernel command line, or setting
111
112
113
 * /proc/sys/kernel/ftrace_dump_on_oops
 * Set 1 if you want to dump buffers of all CPUs
 * Set 2 if you want to dump the buffer of the CPU that triggered oops
114
 */
115
116

enum ftrace_dump_mode ftrace_dump_on_oops;
117

118
119
120
/* When set, tracing will stop when a WARN*() is hit */
int __disable_trace_on_warning;

121
122
static int tracing_set_tracer(const char *buf);

Li Zefan's avatar
Li Zefan committed
123
124
#define MAX_TRACER_SIZE		100
static char bootup_tracer_buf[MAX_TRACER_SIZE] __initdata;
125
static char *default_bootup_tracer;
126

127
128
static bool allocate_snapshot;

129
static int __init set_cmdline_ftrace(char *str)
130
{
131
	strlcpy(bootup_tracer_buf, str, MAX_TRACER_SIZE);
132
	default_bootup_tracer = bootup_tracer_buf;
133
	/* We are using ftrace early, expand it */
134
	ring_buffer_expanded = true;
135
136
	return 1;
}
137
__setup("ftrace=", set_cmdline_ftrace);
138

139
140
static int __init set_ftrace_dump_on_oops(char *str)
{
141
142
143
144
145
146
147
148
149
150
151
	if (*str++ != '=' || !*str) {
		ftrace_dump_on_oops = DUMP_ALL;
		return 1;
	}

	if (!strcmp("orig_cpu", str)) {
		ftrace_dump_on_oops = DUMP_ORIG;
                return 1;
        }

        return 0;
152
153
}
__setup("ftrace_dump_on_oops", set_ftrace_dump_on_oops);
Steven Rostedt's avatar
Steven Rostedt committed
154

155
156
157
158
159
160
161
static int __init stop_trace_on_warning(char *str)
{
	__disable_trace_on_warning = 1;
	return 1;
}
__setup("traceoff_on_warning=", stop_trace_on_warning);

162
static int __init boot_alloc_snapshot(char *str)
163
164
165
166
167
168
{
	allocate_snapshot = true;
	/* We also need the main ring buffer expanded */
	ring_buffer_expanded = true;
	return 1;
}
169
__setup("alloc_snapshot", boot_alloc_snapshot);
170

171
172
173
174
175
176

static char trace_boot_options_buf[MAX_TRACER_SIZE] __initdata;
static char *trace_boot_options __initdata;

static int __init set_trace_boot_options(char *str)
{
177
	strlcpy(trace_boot_options_buf, str, MAX_TRACER_SIZE);
178
179
180
181
182
	trace_boot_options = trace_boot_options_buf;
	return 0;
}
__setup("trace_options=", set_trace_boot_options);

183

184
unsigned long long ns2usecs(cycle_t nsec)
185
186
187
188
189
190
{
	nsec += 500;
	do_div(nsec, 1000);
	return nsec;
}

Steven Rostedt's avatar
Steven Rostedt committed
191
192
193
194
195
196
197
198
199
200
201
202
/*
 * The global_trace is the descriptor that holds the tracing
 * buffers for the live tracing. For each CPU, it contains
 * a link list of pages that will store trace entries. The
 * page descriptor of the pages in the memory is used to hold
 * the link list by linking the lru item in the page descriptor
 * to each of the pages in the buffer per CPU.
 *
 * For each active CPU there is a data field that holds the
 * pages for the buffer for that CPU. Each CPU has the same number
 * of pages allocated for its buffer.
 */
203
204
static struct trace_array	global_trace;

205
LIST_HEAD(ftrace_trace_arrays);
206

207
208
int filter_current_check_discard(struct ring_buffer *buffer,
				 struct ftrace_event_call *call, void *rec,
209
210
				 struct ring_buffer_event *event)
{
211
	return filter_check_discard(call, rec, buffer, event);
212
}
213
EXPORT_SYMBOL_GPL(filter_current_check_discard);
214

215
216
217
218
219
cycle_t ftrace_now(int cpu)
{
	u64 ts;

	/* Early boot up does not have a buffer yet */
220
	if (!global_trace.trace_buffer.buffer)
221
222
		return trace_clock_local();

223
224
	ts = ring_buffer_time_stamp(global_trace.trace_buffer.buffer, cpu);
	ring_buffer_normalize_time_stamp(global_trace.trace_buffer.buffer, cpu, &ts);
225
226
227

	return ts;
}
228

229
230
231
232
233
234
235
236
237
/**
 * tracing_is_enabled - Show if global_trace has been disabled
 *
 * Shows if the global trace has been enabled or not. It uses the
 * mirror flag "buffer_disabled" to be used in fast paths such as for
 * the irqsoff tracer. But it may be inaccurate due to races. If you
 * need to know the accurate state, use tracing_is_on() which is a little
 * slower, but accurate.
 */
238
239
int tracing_is_enabled(void)
{
240
241
242
243
244
245
246
	/*
	 * For quick access (irqsoff uses this in fast path), just
	 * return the mirror variable of the state of the ring buffer.
	 * It's a little racy, but we don't really care.
	 */
	smp_rmb();
	return !global_trace.buffer_disabled;
247
248
}

Steven Rostedt's avatar
Steven Rostedt committed
249
/*
250
251
252
 * trace_buf_size is the size in bytes that is allocated
 * for a buffer. Note, the number of bytes is always rounded
 * to page size.
253
254
255
256
257
 *
 * This number is purposely set to a low number of 16384.
 * If the dump on oops happens, it will be much appreciated
 * to not have to wait for all that output. Anyway this can be
 * boot time and run time configurable.
Steven Rostedt's avatar
Steven Rostedt committed
258
 */
259
#define TRACE_BUF_SIZE_DEFAULT	1441792UL /* 16384 * 88 (sizeof(entry)) */
260

261
static unsigned long		trace_buf_size = TRACE_BUF_SIZE_DEFAULT;
262

Steven Rostedt's avatar
Steven Rostedt committed
263
/* trace_types holds a link list of available tracers. */
264
static struct tracer		*trace_types __read_mostly;
Steven Rostedt's avatar
Steven Rostedt committed
265
266
267
268

/*
 * trace_types_lock is used to protect the trace_types list.
 */
269
static DEFINE_MUTEX(trace_types_lock);
Steven Rostedt's avatar
Steven Rostedt committed
270

271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
/*
 * serialize the access of the ring buffer
 *
 * ring buffer serializes readers, but it is low level protection.
 * The validity of the events (which returns by ring_buffer_peek() ..etc)
 * are not protected by ring buffer.
 *
 * The content of events may become garbage if we allow other process consumes
 * these events concurrently:
 *   A) the page of the consumed events may become a normal page
 *      (not reader page) in ring buffer, and this page will be rewrited
 *      by events producer.
 *   B) The page of the consumed events may become a page for splice_read,
 *      and this page will be returned to system.
 *
 * These primitives allow multi process access to different cpu ring buffer
 * concurrently.
 *
 * These primitives don't distinguish read-only and read-consume access.
 * Multi read-only access are also serialized.
 */

#ifdef CONFIG_SMP
static DECLARE_RWSEM(all_cpu_access_lock);
static DEFINE_PER_CPU(struct mutex, cpu_access_lock);

static inline void trace_access_lock(int cpu)
{
299
	if (cpu == RING_BUFFER_ALL_CPUS) {
300
301
302
303
304
		/* gain it for accessing the whole ring buffer. */
		down_write(&all_cpu_access_lock);
	} else {
		/* gain it for accessing a cpu ring buffer. */

305
		/* Firstly block other trace_access_lock(RING_BUFFER_ALL_CPUS). */
306
307
308
309
310
311
312
313
314
		down_read(&all_cpu_access_lock);

		/* Secondly block other access to this @cpu ring buffer. */
		mutex_lock(&per_cpu(cpu_access_lock, cpu));
	}
}

static inline void trace_access_unlock(int cpu)
{
315
	if (cpu == RING_BUFFER_ALL_CPUS) {
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
		up_write(&all_cpu_access_lock);
	} else {
		mutex_unlock(&per_cpu(cpu_access_lock, cpu));
		up_read(&all_cpu_access_lock);
	}
}

static inline void trace_access_lock_init(void)
{
	int cpu;

	for_each_possible_cpu(cpu)
		mutex_init(&per_cpu(cpu_access_lock, cpu));
}

#else

static DEFINE_MUTEX(access_lock);

static inline void trace_access_lock(int cpu)
{
	(void)cpu;
	mutex_lock(&access_lock);
}

static inline void trace_access_unlock(int cpu)
{
	(void)cpu;
	mutex_unlock(&access_lock);
}

static inline void trace_access_lock_init(void)
{
}

#endif

353
/* trace_flags holds trace_options default values */
354
unsigned long trace_flags = TRACE_ITER_PRINT_PARENT | TRACE_ITER_PRINTK |
355
	TRACE_ITER_ANNOTATE | TRACE_ITER_CONTEXT_INFO | TRACE_ITER_SLEEP_TIME |
356
	TRACE_ITER_GRAPH_TIME | TRACE_ITER_RECORD_CMD | TRACE_ITER_OVERWRITE |
357
	TRACE_ITER_IRQ_INFO | TRACE_ITER_MARKERS | TRACE_ITER_FUNCTION;
358

359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
void tracer_tracing_on(struct trace_array *tr)
{
	if (tr->trace_buffer.buffer)
		ring_buffer_record_on(tr->trace_buffer.buffer);
	/*
	 * This flag is looked at when buffers haven't been allocated
	 * yet, or by some tracers (like irqsoff), that just want to
	 * know if the ring buffer has been disabled, but it can handle
	 * races of where it gets disabled but we still do a record.
	 * As the check is in the fast path of the tracers, it is more
	 * important to be fast than accurate.
	 */
	tr->buffer_disabled = 0;
	/* Make the flag seen by readers */
	smp_wmb();
}

376
377
378
379
380
381
382
383
/**
 * tracing_on - enable tracing buffers
 *
 * This function enables tracing buffers that may have been
 * disabled with tracing_off.
 */
void tracing_on(void)
{
384
	tracer_tracing_on(&global_trace);
385
386
387
}
EXPORT_SYMBOL_GPL(tracing_on);

388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
/**
 * __trace_puts - write a constant string into the trace buffer.
 * @ip:	   The address of the caller
 * @str:   The constant string to write
 * @size:  The size of the string.
 */
int __trace_puts(unsigned long ip, const char *str, int size)
{
	struct ring_buffer_event *event;
	struct ring_buffer *buffer;
	struct print_entry *entry;
	unsigned long irq_flags;
	int alloc;

	alloc = sizeof(*entry) + size + 2; /* possible \n added */

	local_save_flags(irq_flags);
	buffer = global_trace.trace_buffer.buffer;
	event = trace_buffer_lock_reserve(buffer, TRACE_PRINT, alloc, 
					  irq_flags, preempt_count());
	if (!event)
		return 0;

	entry = ring_buffer_event_data(event);
	entry->ip = ip;

	memcpy(&entry->buf, str, size);

	/* Add a newline if necessary */
	if (entry->buf[size - 1] != '\n') {
		entry->buf[size] = '\n';
		entry->buf[size + 1] = '\0';
	} else
		entry->buf[size] = '\0';

	__buffer_unlock_commit(buffer, event);

	return size;
}
EXPORT_SYMBOL_GPL(__trace_puts);

/**
 * __trace_bputs - write the pointer to a constant string into trace buffer
 * @ip:	   The address of the caller
 * @str:   The constant string to write to the buffer to
 */
int __trace_bputs(unsigned long ip, const char *str)
{
	struct ring_buffer_event *event;
	struct ring_buffer *buffer;
	struct bputs_entry *entry;
	unsigned long irq_flags;
	int size = sizeof(struct bputs_entry);

	local_save_flags(irq_flags);
	buffer = global_trace.trace_buffer.buffer;
	event = trace_buffer_lock_reserve(buffer, TRACE_BPUTS, size,
					  irq_flags, preempt_count());
	if (!event)
		return 0;

	entry = ring_buffer_event_data(event);
	entry->ip			= ip;
	entry->str			= str;

	__buffer_unlock_commit(buffer, event);

	return 1;
}
EXPORT_SYMBOL_GPL(__trace_bputs);

459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
#ifdef CONFIG_TRACER_SNAPSHOT
/**
 * trace_snapshot - take a snapshot of the current buffer.
 *
 * This causes a swap between the snapshot buffer and the current live
 * tracing buffer. You can use this to take snapshots of the live
 * trace when some condition is triggered, but continue to trace.
 *
 * Note, make sure to allocate the snapshot with either
 * a tracing_snapshot_alloc(), or by doing it manually
 * with: echo 1 > /sys/kernel/debug/tracing/snapshot
 *
 * If the snapshot buffer is not allocated, it will stop tracing.
 * Basically making a permanent snapshot.
 */
void tracing_snapshot(void)
{
	struct trace_array *tr = &global_trace;
	struct tracer *tracer = tr->current_trace;
	unsigned long flags;

480
481
482
483
484
485
	if (in_nmi()) {
		internal_trace_puts("*** SNAPSHOT CALLED FROM NMI CONTEXT ***\n");
		internal_trace_puts("*** snapshot is being ignored        ***\n");
		return;
	}

486
	if (!tr->allocated_snapshot) {
487
488
		internal_trace_puts("*** SNAPSHOT NOT ALLOCATED ***\n");
		internal_trace_puts("*** stopping trace here!   ***\n");
489
490
491
492
493
494
		tracing_off();
		return;
	}

	/* Note, snapshot can not be used when the tracer uses it */
	if (tracer->use_max_tr) {
495
496
		internal_trace_puts("*** LATENCY TRACER ACTIVE ***\n");
		internal_trace_puts("*** Can not use snapshot (sorry) ***\n");
497
498
499
500
501
502
503
		return;
	}

	local_irq_save(flags);
	update_max_tr(tr, current, smp_processor_id());
	local_irq_restore(flags);
}
504
EXPORT_SYMBOL_GPL(tracing_snapshot);
505
506
507

static int resize_buffer_duplicate_size(struct trace_buffer *trace_buf,
					struct trace_buffer *size_buf, int cpu_id);
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
static void set_buffer_entries(struct trace_buffer *buf, unsigned long val);

static int alloc_snapshot(struct trace_array *tr)
{
	int ret;

	if (!tr->allocated_snapshot) {

		/* allocate spare buffer */
		ret = resize_buffer_duplicate_size(&tr->max_buffer,
				   &tr->trace_buffer, RING_BUFFER_ALL_CPUS);
		if (ret < 0)
			return ret;

		tr->allocated_snapshot = true;
	}

	return 0;
}

void free_snapshot(struct trace_array *tr)
{
	/*
	 * We don't free the ring buffer. instead, resize it because
	 * The max_tr ring buffer has some state (e.g. ring->clock) and
	 * we want preserve it.
	 */
	ring_buffer_resize(tr->max_buffer.buffer, 1, RING_BUFFER_ALL_CPUS);
	set_buffer_entries(&tr->max_buffer, 1);
	tracing_reset_online_cpus(&tr->max_buffer);
	tr->allocated_snapshot = false;
}
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556

/**
 * trace_snapshot_alloc - allocate and take a snapshot of the current buffer.
 *
 * This is similar to trace_snapshot(), but it will allocate the
 * snapshot buffer if it isn't already allocated. Use this only
 * where it is safe to sleep, as the allocation may sleep.
 *
 * This causes a swap between the snapshot buffer and the current live
 * tracing buffer. You can use this to take snapshots of the live
 * trace when some condition is triggered, but continue to trace.
 */
void tracing_snapshot_alloc(void)
{
	struct trace_array *tr = &global_trace;
	int ret;

557
558
559
	ret = alloc_snapshot(tr);
	if (WARN_ON(ret < 0))
		return;
560
561
562

	tracing_snapshot();
}
563
EXPORT_SYMBOL_GPL(tracing_snapshot_alloc);
564
565
566
567
568
#else
void tracing_snapshot(void)
{
	WARN_ONCE(1, "Snapshot feature not enabled, but internal snapshot used");
}
569
EXPORT_SYMBOL_GPL(tracing_snapshot);
570
571
572
573
574
void tracing_snapshot_alloc(void)
{
	/* Give warning */
	tracing_snapshot();
}
575
EXPORT_SYMBOL_GPL(tracing_snapshot_alloc);
576
577
#endif /* CONFIG_TRACER_SNAPSHOT */

578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
void tracer_tracing_off(struct trace_array *tr)
{
	if (tr->trace_buffer.buffer)
		ring_buffer_record_off(tr->trace_buffer.buffer);
	/*
	 * This flag is looked at when buffers haven't been allocated
	 * yet, or by some tracers (like irqsoff), that just want to
	 * know if the ring buffer has been disabled, but it can handle
	 * races of where it gets disabled but we still do a record.
	 * As the check is in the fast path of the tracers, it is more
	 * important to be fast than accurate.
	 */
	tr->buffer_disabled = 1;
	/* Make the flag seen by readers */
	smp_wmb();
}

595
596
597
598
599
600
601
602
603
604
/**
 * tracing_off - turn off tracing buffers
 *
 * This function stops the tracing buffers from recording data.
 * It does not disable any overhead the tracers themselves may
 * be causing. This function simply causes all recording to
 * the ring buffers to fail.
 */
void tracing_off(void)
{
605
	tracer_tracing_off(&global_trace);
606
607
608
}
EXPORT_SYMBOL_GPL(tracing_off);

609
610
611
612
613
614
void disable_trace_on_warning(void)
{
	if (__disable_trace_on_warning)
		tracing_off();
}

615
616
617
618
619
620
621
622
623
624
625
626
627
/**
 * tracer_tracing_is_on - show real state of ring buffer enabled
 * @tr : the trace array to know if ring buffer is enabled
 *
 * Shows real state of the ring buffer if it is enabled or not.
 */
int tracer_tracing_is_on(struct trace_array *tr)
{
	if (tr->trace_buffer.buffer)
		return ring_buffer_record_is_on(tr->trace_buffer.buffer);
	return !tr->buffer_disabled;
}

628
629
630
631
632
/**
 * tracing_is_on - show state of ring buffers enabled
 */
int tracing_is_on(void)
{
633
	return tracer_tracing_is_on(&global_trace);
634
635
636
}
EXPORT_SYMBOL_GPL(tracing_is_on);

637
static int __init set_buf_size(char *str)
638
{
639
	unsigned long buf_size;
640

641
642
	if (!str)
		return 0;
643
	buf_size = memparse(str, &str);
644
	/* nr_entries can not be zero */
645
	if (buf_size == 0)
646
		return 0;
647
	trace_buf_size = buf_size;
648
649
	return 1;
}
650
__setup("trace_buf_size=", set_buf_size);
651

652
653
static int __init set_tracing_thresh(char *str)
{
654
	unsigned long threshold;
655
656
657
658
	int ret;

	if (!str)
		return 0;
659
	ret = kstrtoul(str, 0, &threshold);
660
661
	if (ret < 0)
		return 0;
662
	tracing_thresh = threshold * 1000;
663
664
665
666
	return 1;
}
__setup("tracing_thresh=", set_tracing_thresh);

Steven Rostedt's avatar
Steven Rostedt committed
667
668
669
670
671
unsigned long nsecs_to_usecs(unsigned long nsecs)
{
	return nsecs / 1000;
}

Steven Rostedt's avatar
Steven Rostedt committed
672
/* These must match the bit postions in trace_iterator_flags */
673
674
675
676
677
static const char *trace_options[] = {
	"print-parent",
	"sym-offset",
	"sym-addr",
	"verbose",
Ingo Molnar's avatar
Ingo Molnar committed
678
	"raw",
679
	"hex",
Ingo Molnar's avatar
Ingo Molnar committed
680
	"bin",
681
	"block",
Ingo Molnar's avatar
Ingo Molnar committed
682
	"stacktrace",
683
	"trace_printk",
684
	"ftrace_preempt",
685
	"branch",
686
	"annotate",
687
	"userstacktrace",
688
	"sym-userobj",
689
	"printk-msg-only",
690
	"context-info",
691
	"latency-format",
692
	"sleep-time",
693
	"graph-time",
694
	"record-cmd",
695
	"overwrite",
696
	"disable_on_free",
697
	"irq-info",
698
	"markers",
699
	"function-trace",
700
701
702
	NULL
};

703
704
705
static struct {
	u64 (*func)(void);
	const char *name;
706
	int in_ns;		/* is this clock in nanoseconds? */
707
} trace_clocks[] = {
708
709
710
	{ trace_clock_local,	"local",	1 },
	{ trace_clock_global,	"global",	1 },
	{ trace_clock_counter,	"counter",	0 },
711
	{ trace_clock_jiffies,	"uptime",	1 },
712
	{ trace_clock,		"perf",		1 },
713
	ARCH_TRACE_CLOCKS
714
715
716
717
};

int trace_clock_id;

718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
/*
 * trace_parser_get_init - gets the buffer for trace parser
 */
int trace_parser_get_init(struct trace_parser *parser, int size)
{
	memset(parser, 0, sizeof(*parser));

	parser->buffer = kmalloc(size, GFP_KERNEL);
	if (!parser->buffer)
		return 1;

	parser->size = size;
	return 0;
}

/*
 * trace_parser_put - frees the buffer for trace parser
 */
void trace_parser_put(struct trace_parser *parser)
{
	kfree(parser->buffer);
}

/*
 * trace_get_user - reads the user input string separated by  space
 * (matched by isspace(ch))
 *
 * For each string found the 'struct trace_parser' is updated,
 * and the function returns.
 *
 * Returns number of bytes read.
 *
 * See kernel/trace/trace.h for 'struct trace_parser' details.
 */
int trace_get_user(struct trace_parser *parser, const char __user *ubuf,
	size_t cnt, loff_t *ppos)
{
	char ch;
	size_t read = 0;
	ssize_t ret;

	if (!*ppos)
		trace_parser_clear(parser);

	ret = get_user(ch, ubuf++);
	if (ret)
		goto out;

	read++;
	cnt--;

	/*
	 * The parser is not finished with the last write,
	 * continue reading the user input without skipping spaces.
	 */
	if (!parser->cont) {
		/* skip white space */
		while (cnt && isspace(ch)) {
			ret = get_user(ch, ubuf++);
			if (ret)
				goto out;
			read++;
			cnt--;
		}

		/* only spaces were written */
		if (isspace(ch)) {
			*ppos += read;
			ret = read;
			goto out;
		}

		parser->idx = 0;
	}

	/* read the non-space input */
	while (cnt && !isspace(ch)) {
795
		if (parser->idx < parser->size - 1)
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
			parser->buffer[parser->idx++] = ch;
		else {
			ret = -EINVAL;
			goto out;
		}
		ret = get_user(ch, ubuf++);
		if (ret)
			goto out;
		read++;
		cnt--;
	}

	/* We either got finished input or we have to wait for another call. */
	if (isspace(ch)) {
		parser->buffer[parser->idx] = 0;
		parser->cont = false;
	} else {
		parser->cont = true;
		parser->buffer[parser->idx++] = ch;
	}

	*ppos += read;
	ret = read;

out:
	return ret;
}

824
825
826
827
828
ssize_t trace_seq_to_user(struct trace_seq *s, char __user *ubuf, size_t cnt)
{
	int len;
	int ret;

829
830
831
	if (!cnt)
		return 0;

832
833
834
835
836
837
838
	if (s->len <= s->readpos)
		return -EBUSY;

	len = s->len - s->readpos;
	if (cnt > len)
		cnt = len;
	ret = copy_to_user(ubuf, s->buffer + s->readpos, cnt);
839
	if (ret == cnt)
840
841
		return -EFAULT;

842
843
	cnt -= ret;

844
	s->readpos += cnt;
845
	return cnt;
846
847
}

848
static ssize_t trace_seq_to_buffer(struct trace_seq *s, void *buf, size_t cnt)
849
850
851
852
853
854
855
856
857
{
	int len;

	if (s->len <= s->readpos)
		return -EBUSY;

	len = s->len - s->readpos;
	if (cnt > len)
		cnt = len;
858
	memcpy(buf, s->buffer + s->readpos, cnt);
859

860
	s->readpos += cnt;
861
862
863
	return cnt;
}

864
865
866
867
868
869
/*
 * ftrace_max_lock is used to protect the swapping of buffers
 * when taking a max snapshot. The buffers themselves are
 * protected by per_cpu spinlocks. But the action of the swap
 * needs its own lock.
 *
870
 * This is defined as a arch_spinlock_t in order to help
871
872
873
874
875
876
 * with performance when lockdep debugging is enabled.
 *
 * It is also used in other places outside the update_max_tr
 * so it needs to be defined outside of the
 * CONFIG_TRACER_MAX_TRACE.
 */
877
static arch_spinlock_t ftrace_max_lock =
878
	(arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
879

880
881
unsigned long __read_mostly	tracing_thresh;

882
883
884
885
886
887
888
889
890
891
892
#ifdef CONFIG_TRACER_MAX_TRACE
unsigned long __read_mostly	tracing_max_latency;

/*
 * Copy the new maximum trace into the separate maximum-trace
 * structure. (this way the maximum trace is permanently saved,
 * for later retrieval via /sys/kernel/debug/tracing/latency_trace)
 */
static void
__update_max_tr(struct trace_array *tr, struct task_struct *tsk, int cpu)
{
893
894
895
896
	struct trace_buffer *trace_buf = &tr->trace_buffer;
	struct trace_buffer *max_buf = &tr->max_buffer;
	struct trace_array_cpu *data = per_cpu_ptr(trace_buf->data, cpu);
	struct trace_array_cpu *max_data = per_cpu_ptr(max_buf->data, cpu);
897

898
899
	max_buf->cpu = cpu;
	max_buf->time_start = data->preempt_timestamp;
900

901
902
903
	max_data->saved_latency = tracing_max_latency;
	max_data->critical_start = data->critical_start;
	max_data->critical_end = data->critical_end;
904

905
	memcpy(max_data->comm, tsk->comm, TASK_COMM_LEN);
906
	max_data->pid = tsk->pid;
907
908
909
910
911
912
913
914
915
	/*
	 * If tsk == current, then use current_uid(), as that does not use
	 * RCU. The irq tracer can be called out of RCU scope.
	 */
	if (tsk == current)
		max_data->uid = current_uid();
	else
		max_data->uid = task_uid(tsk);

916
917
918
	max_data->nice = tsk->static_prio - 20 - MAX_RT_PRIO;
	max_data->policy = tsk->policy;
	max_data->rt_priority = tsk->rt_priority;
919
920
921
922
923

	/* record this tasks comm */
	tracing_record_cmdline(tsk);
}

Steven Rostedt's avatar
Steven Rostedt committed
924
925
926
927
928
929
930
931
932
/**
 * update_max_tr - snapshot all trace buffers from global_trace to max_tr
 * @tr: tracer
 * @tsk: the task with the latency
 * @cpu: The cpu that initiated the trace.
 *
 * Flip the buffers between the @tr and the max_tr and record information
 * about which task was the cause of this latency.
 */
Ingo Molnar's avatar
Ingo Molnar committed
933
void
934
935
update_max_tr(struct trace_array *tr, struct task_struct *tsk, int cpu)
{
936
	struct ring_buffer *buf;
937

938
	if (tr->stop_count)
939
940
		return;

941
	WARN_ON_ONCE(!irqs_disabled());
942

943
	if (!tr->allocated_snapshot) {
944
		/* Only the nop tracer should hit this when disabling */
945
		WARN_ON_ONCE(tr->current_trace != &nop_trace);
946
		return;
947
	}
948

949
	arch_spin_lock(&ftrace_max_lock);
950

951
952
953
	buf = tr->trace_buffer.buffer;
	tr->trace_buffer.buffer = tr->max_buffer.buffer;
	tr->max_buffer.buffer = buf;
954

955
	__update_max_tr(tr, tsk, cpu);
956
	arch_spin_unlock(&ftrace_max_lock);
957
958
959
960
961
962
963
}

/**
 * update_max_tr_single - only copy one trace over, and reset the rest
 * @tr - tracer
 * @tsk - task with the latency
 * @cpu - the cpu of the buffer to copy.
Steven Rostedt's avatar
Steven Rostedt committed
964
965
 *
 * Flip the trace of a single CPU buffer between the @tr and the max_tr.
966
 */
Ingo Molnar's avatar
Ingo Molnar committed
967
void
968
969
update_max_tr_single(struct trace_array *tr, struct task_struct *tsk, int cpu)
{
970
	int ret;
971

972
	if (tr->stop_count)
973
974
		return;

975
	WARN_ON_ONCE(!irqs_disabled());
Steven Rostedt's avatar
Steven Rostedt committed
976
	if (!tr->allocated_snapshot) {
977
		/* Only the nop tracer should hit this when disabling */
978
		WARN_ON_ONCE(tr->current_trace != &nop_trace);
979
		return;
980
	}
981

982
	arch_spin_lock(&ftrace_max_lock);
983

984
	ret = ring_buffer_swap_cpu(tr->max_buffer.buffer, tr->trace_buffer.buffer, cpu);
985

986
987
988
989
990
991
992
	if (ret == -EBUSY) {
		/*
		 * We failed to swap the buffer due to a commit taking
		 * place on this CPU. We fail to record, but we reset
		 * the max trace buffer (no one writes directly to it)
		 * and flag that it failed.
		 */
993
		trace_array_printk_buf(tr->max_buffer.buffer, _THIS_IP_,
994
995
996
997
			"Failed to swap buffers due to commit in progress\n");
	}

	WARN_ON_ONCE(ret && ret != -EAGAIN && ret != -EBUSY);
998
999

	__update_max_tr(tr, tsk, cpu);
1000
	arch_spin_unlock(&ftrace_max_lock);
1001
}
1002
#endif /* CONFIG_TRACER_MAX_TRACE */
1003

1004
1005
static void default_wait_pipe(struct trace_iterator *iter)
{
1006
1007
1008
	/* Iterators are static, they should be filled or empty */
	if (trace_buffer_iter(iter, iter->cpu_file))
		return;
1009

1010
	ring_buffer_wait(iter->trace_buffer->buffer, iter->cpu_file);
1011
1012
}

1013
1014
1015
1016
1017
1018
#ifdef CONFIG_FTRACE_STARTUP_TEST
static int run_tracer_selftest(struct tracer *type)
{
	struct trace_array *tr = &global_trace;
	struct tracer *saved_tracer = tr->current_trace;
	int ret;
1019

1020
1021
	if (!type->selftest || tracing_selftest_disabled)
		return 0;
1022
1023

	/*
1024
1025
1026
1027
1028
	 * Run a selftest on this tracer.
	 * Here we reset the trace buffer, and set the current
	 * tracer to be this tracer. The tracer can then run some
	 * internal tracing to verify that everything is in order.
	 * If we fail, we do not register this tracer.
1029
	 */
1030
	tracing_reset_online_cpus(&tr->trace_buffer);
1031

1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
	tr->current_trace = type;

#ifdef CONFIG_TRACER_MAX_TRACE
	if (type->use_max_tr) {
		/* If we expanded the buffers, make sure the max is expanded too */
		if (ring_buffer_expanded)
			ring_buffer_resize(tr->max_buffer.buffer, trace_buf_size,
					   RING_BUFFER_ALL_CPUS);
		tr->allocated_snapshot = true;
	}
#endif

	/* the test is responsible for initializing and enabling */
	pr_info("Testing tracer %s: ", type->name);
	ret = type->selftest(type, tr);
	/* the test is responsible for resetting too */
	tr->current_trace = saved_tracer;
	if (ret) {
		printk(KERN_CONT "FAILED!\n");
		/* Add the warning after printing 'FAILED' */
		WARN_ON(1);
		return -1;
	}
	/* Only reset on passing, to avoid touching corrupted buffers */
	tracing_reset_online_cpus(&tr->trace_buffer);

#ifdef CONFIG_TRACER_MAX_TRACE
	if (type->use_max_tr) {
		tr->allocated_snapshot = false;
1061

1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
		/* Shrink the max buffer again */
		if (ring_buffer_expanded)
			ring_buffer_resize(tr->max_buffer.buffer, 1,
					   RING_BUFFER_ALL_CPUS);
	}
#endif

	printk(KERN_CONT "PASSED\n");
	return 0;
}
#else
static inline int run_tracer_selftest(struct tracer *type)
{
	return 0;
1076
}
1077
#endif /* CONFIG_FTRACE_STARTUP_TEST */
1078

Steven Rostedt's avatar
Steven Rostedt committed
1079
1080
1081
1082
1083
1084
/**
 * register_tracer - register a tracer with the ftrace system.
 * @type - the plugin for the tracer
 *
 * Register a new plugin tracer.
 */
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
int register_tracer(struct tracer *type)
{
	struct tracer *t;
	int ret = 0;

	if (!type->name) {
		pr_info("Tracer must have a name\n");
		return -1;
	}

1095
	if (strlen(type->name) >= MAX_TRACER_SIZE) {
Li Zefan's avatar
Li Zefan committed
1096
1097
1098
1099
		pr_info("Tracer has a name longer than %d\n", MAX_TRACER_SIZE);
		return -1;
	}

1100
	mutex_lock(&trace_types_lock);
Ingo Molnar's avatar
Ingo Molnar committed
1101

1102
1103
	tracing_selftest_running = true;

1104
1105
1106
	for (t = trace_types; t; t = t->next) {
		if (strcmp(type->name, t->name) == 0) {
			/* already found */
Li Zefan's avatar
Li Zefan committed
1107
			pr_info("Tracer %s already registered\n",
1108
1109
1110
1111
1112
1113
				type->name);
			ret = -1;
			goto out;
		}
	}

1114
1115
1116
1117
1118
1119
1120
	if (!type->set_flag)
		type->set_flag = &dummy_set_flag;
	if (!type->flags)
		type->flags = &dummy_tracer_flags;
	else
		if (!type->flags->opts)
			type->flags->opts = dummy_tracer_opt;
1121
1122
1123
	if (!type->wait_pipe)
		type->wait_pipe = default_wait_pipe;

1124
1125
1126
	ret = run_tracer_selftest(type);
	if (ret < 0)
		goto out;
Steven Rostedt's avatar
Steven Rostedt committed
1127

1128
1129
	type->next = trace_types;
	trace_types = type;
Steven Rostedt's avatar
Steven Rostedt committed
1130

1131
 out:
1132
	tracing_selftest_running = false;
1133
1134
	mutex_unlock(&trace_types_lock);

Steven Rostedt's avatar
Steven Rostedt committed
1135
1136
1137
	if (ret || !default_bootup_tracer)
		goto out_unlock;

Li Zefan's avatar
Li Zefan committed
1138
	if (strncmp(default_bootup_tracer, type->name, MAX_TRACER_SIZE))
Steven Rostedt's avatar
Steven Rostedt committed
1139
1140
1141
1142
1143
1144
1145
		goto out_unlock;

	printk(KERN_INFO "Starting tracer '%s'\n", type->name);
	/* Do we want this tracer to start on bootup? */
	tracing_set_tracer(type->name);
	default_bootup_tracer = NULL;
	/* disable other selftests, since this will break it. */
1146
	tracing_selftest_disabled = true;
1147
#ifdef CONFIG_FTRACE_STARTUP_TEST
Steven Rostedt's avatar
Steven Rostedt committed
1148
1149
	printk(KERN_INFO "Disabling FTRACE selftests due to running tracer '%s'\n",
	       type->name);
1150
1151
#endif

Steven Rostedt's avatar
Steven Rostedt committed
1152
 out_unlock:
1153
1154
1155
	return ret;
}

1156
void tracing_reset(struct trace_buffer *buf, int cpu)
1157
{
1158
	struct ring_buffer *buffer = buf->buffer;
1159

1160
1161
1162
	if (!buffer)
		return;

1163
1164
1165
1166
	ring_buffer_record_disable(buffer);

	/* Make sure all commits have finished */
	synchronize_sched();
1167
	ring_buffer_reset_cpu(buffer, cpu);
1168
1169
1170
1171

	ring_buffer_record_enable(buffer);
}

1172
void tracing_reset_online_cpus(struct trace_buffer *buf)
1173
{
1174
	struct ring_buffer *buffer = buf->buffer;
1175
1176
	int cpu;

1177
1178
1179
	if (!buffer)
		return;

1180
1181
1182
1183
1184
	ring_buffer_record_disable(buffer);

	/* Make sure all commits have finished */
	synchronize_sched();

1185
	buf->time_start = ftrace_now(buf->cpu);
1186
1187

	for_each_online_cpu(cpu)
1188
		ring_buffer_reset_cpu(buffer, cpu);
1189
1190

	ring_buffer_record_enable(buffer);
1191
1192
}

1193
1194
void tracing_reset_current(int cpu)
{
1195
	tracing_reset(&global_trace.trace_buffer, cpu);
1196
1197
}

1198
void tracing_reset_all_online_cpus(void)
1199
{
1200
1201
1202
1203
	struct trace_array *tr;

	mutex_lock(&trace_types_lock);
	list_for_each_entry(tr, &ftrace_trace_arrays, list) {
1204
1205
1206
1207
		tracing_reset_online_cpus(&tr->trace_buffer);
#ifdef CONFIG_TRACER_MAX_TRACE
		tracing_reset_online_cpus(&tr->max_buffer);
#endif
1208
1209
	}
	mutex_unlock(&trace_types_lock);
1210
1211
}

1212
#define SAVED_CMDLINES 128
1213
#define NO_CMDLINE_MAP UINT_MAX
1214
1215
1216
1217
static unsigned map_pid_to_cmdline[PID_MAX_DEFAULT+1];
static unsigned map_cmdline_to_pid[SAVED_CMDLINES];
static char saved_cmdlines[SAVED_CMDLINES][TASK_COMM_LEN];
static int cmdline_idx;
1218
static arch_spinlock_t trace_cmdline_lock = __ARCH_SPIN_LOCK_UNLOCKED;
1219
1220

/* temporary disable recording */
1221
static atomic_t trace_record_cmdline_disabled __read_mostly;
1222
1223
1224

static void trace_init_cmdlines(void)
{
1225
1226
	memset(&map_pid_to_cmdline, NO_CMDLINE_MAP, sizeof(map_pid_to_cmdline));
	memset(&map_cmdline_to_pid, NO_CMDLINE_MAP, sizeof(map_cmdline_to_pid));
1227
1228
1229
	cmdline_idx = 0;
}

1230
1231
int is_tracing_stopped(void)
{
1232
	return global_trace.stop_count;
1233
1234
}

1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
/**
 * ftrace_off_permanent - disable all ftrace code permanently
 *
 * This should only be called when a serious anomally has
 * been detected.  This will turn off the function tracing,
 * ring buffers, and other tracing utilites. It takes no
 * locks and can be called from any context.
 */
void ftrace_off_permanent(void)
{
	tracing_disabled = 1;
	ftrace_stop();
	tracing_off_permanent();
}

1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
/**
 * tracing_start - quick start of the tracer
 *
 * If tracing is enabled but was stopped by tracing_stop,
 * this will start the tracer back up.
 */
void tracing_start(void)
{
	struct ring_buffer *buffer;
	unsigned long flags;

	if (tracing_disabled)
		return;

1264
1265
1266
	raw_spin_lock_irqsave(&global_trace.start_lock, flags);
	if (--global_trace.stop_count) {
		if (global_trace.stop_count < 0) {
1267
1268
			/* Someone screwed up their debugging */
			WARN_ON_ONCE(1);
1269
			global_trace.stop_count = 0;
1270
		}
1271
1272
1273
		goto out;
	}

1274
1275
	/* Prevent the buffers from switching */
	arch_spin_lock(&ftrace_max_lock);
1276

1277
	buffer = global_trace.trace_buffer.buffer;
1278
1279
1280
	if (buffer)
		ring_buffer_record_enable(buffer);

1281
1282
#ifdef CONFIG_TRACER_MAX_TRACE
	buffer = global_trace.max_buffer.buffer;
1283
1284
	if (buffer)
		ring_buffer_record_enable(buffer);
1285
#endif
1286

1287
1288
	arch_spin_unlock(&ftrace_max_lock);

1289
1290
	ftrace_start();
 out:
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309