trace.c 73.4 KB
Newer Older
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
/*
 * ring buffer based function tracer
 *
 * Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com>
 * 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
 *  Copyright (C) 2004 William Lee Irwin III
 */
#include <linux/utsrelease.h>
#include <linux/kallsyms.h>
#include <linux/seq_file.h>
17
#include <linux/notifier.h>
18
#include <linux/debugfs.h>
19
#include <linux/pagemap.h>
20
21
22
23
24
25
#include <linux/hardirq.h>
#include <linux/linkage.h>
#include <linux/uaccess.h>
#include <linux/ftrace.h>
#include <linux/module.h>
#include <linux/percpu.h>
26
#include <linux/kdebug.h>
27
28
#include <linux/ctype.h>
#include <linux/init.h>
29
#include <linux/poll.h>
30
31
#include <linux/gfp.h>
#include <linux/fs.h>
32
#include <linux/kprobes.h>
Steven Rostedt's avatar
Steven Rostedt committed
33
#include <linux/writeback.h>
34
#include <linux/splice.h>
35

Ingo Molnar's avatar
Ingo Molnar committed
36
#include <linux/stacktrace.h>
37
#include <linux/ring_buffer.h>
38
#include <linux/irqflags.h>
Ingo Molnar's avatar
Ingo Molnar committed
39

40
#include "trace.h"
41
#include "trace_output.h"
42

43
44
#define TRACE_BUFFER_FLAGS	(RB_FL_OVERWRITE)

45
unsigned long __read_mostly	tracing_max_latency;
46
47
unsigned long __read_mostly	tracing_thresh;

48
49
/*
 * We need to change this state when a selftest is running.
50
51
52
53
54
 * A selftest will lurk into the ring-buffer to count the
 * entries inserted during the selftest although some concurrent
 * insertions into the ring-buffer such as ftrace_printk could occurred
 * at the same time, giving false positive or negative results.
 */
55
static bool __read_mostly tracing_selftest_running;
56

57
58
59
60
61
/*
 * If a tracer is running, we do not want to run SELFTEST.
 */
static bool __read_mostly tracing_selftest_disabled;

62
63
64
65
66
67
68
69
70
71
72
73
74
75
/* 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;
}
76
77
78
79
80
81
82
83
84

/*
 * 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.
 */
int tracing_disabled = 1;

85
86
87
88
89
90
91
92
93
94
95
96
97
98
static DEFINE_PER_CPU(local_t, ftrace_cpu_disabled);

static inline void ftrace_disable_cpu(void)
{
	preempt_disable();
	local_inc(&__get_cpu_var(ftrace_cpu_disabled));
}

static inline void ftrace_enable_cpu(void)
{
	local_dec(&__get_cpu_var(ftrace_cpu_disabled));
	preempt_enable();
}

99
static cpumask_var_t __read_mostly	tracing_buffer_mask;
100
101

#define for_each_tracing_cpu(cpu)	\
102
	for_each_cpu(cpu, tracing_buffer_mask)
103

104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
/*
 * 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
 * /proc/sys/kernel/ftrace_dump_on_oops to true.
 */
int ftrace_dump_on_oops;

119
120
121
122
123
static int tracing_set_tracer(const char *buf);

#define BOOTUP_TRACER_SIZE		100
static char bootup_tracer_buf[BOOTUP_TRACER_SIZE] __initdata;
static char *default_bootup_tracer;
124
125
126

static int __init set_ftrace(char *str)
{
127
128
	strncpy(bootup_tracer_buf, str, BOOTUP_TRACER_SIZE);
	default_bootup_tracer = bootup_tracer_buf;
129
130
	return 1;
}
131
__setup("ftrace=", set_ftrace);
132

133
134
135
136
137
138
static int __init set_ftrace_dump_on_oops(char *str)
{
	ftrace_dump_on_oops = 1;
	return 1;
}
__setup("ftrace_dump_on_oops", set_ftrace_dump_on_oops);
Steven Rostedt's avatar
Steven Rostedt committed
139

140
long
141
142
143
144
145
146
147
ns2usecs(cycle_t nsec)
{
	nsec += 500;
	do_div(nsec, 1000);
	return nsec;
}

Ingo Molnar's avatar
Ingo Molnar committed
148
cycle_t ftrace_now(int cpu)
149
{
150
151
152
	u64 ts = ring_buffer_time_stamp(cpu);
	ring_buffer_normalize_time_stamp(cpu, &ts);
	return ts;
153
154
}

Steven Rostedt's avatar
Steven Rostedt committed
155
156
157
158
159
160
161
162
163
164
165
166
/*
 * 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.
 */
167
168
169
170
static struct trace_array	global_trace;

static DEFINE_PER_CPU(struct trace_array_cpu, global_trace_cpu);

Steven Rostedt's avatar
Steven Rostedt committed
171
172
173
174
175
176
177
178
179
180
/*
 * The max_tr is used to snapshot the global_trace when a maximum
 * latency is reached. Some tracers will use this to store a maximum
 * trace while it continues examining live traces.
 *
 * The buffers for the max_tr are set up the same as the global_trace.
 * When a snapshot is taken, the link list of the max_tr is swapped
 * with the link list of the global_trace and the buffers are reset for
 * the global_trace so the tracing can continue.
 */
181
182
183
184
static struct trace_array	max_tr;

static DEFINE_PER_CPU(struct trace_array_cpu, max_data);

Steven Rostedt's avatar
Steven Rostedt committed
185
/* tracer_enabled is used to toggle activation of a tracer */
186
static int			tracer_enabled = 1;
Steven Rostedt's avatar
Steven Rostedt committed
187

188
189
190
191
192
193
194
195
196
197
198
199
200
/**
 * tracing_is_enabled - return tracer_enabled status
 *
 * This function is used by other tracers to know the status
 * of the tracer_enabled flag.  Tracers may use this function
 * to know if it should enable their features when starting
 * up. See irqsoff tracer for an example (start_irqsoff_tracer).
 */
int tracing_is_enabled(void)
{
	return tracer_enabled;
}

Steven Rostedt's avatar
Steven Rostedt committed
201
/*
202
203
204
 * 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.
205
206
207
208
209
 *
 * 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
210
 */
211
#define TRACE_BUF_SIZE_DEFAULT	1441792UL /* 16384 * 88 (sizeof(entry)) */
212

213
static unsigned long		trace_buf_size = TRACE_BUF_SIZE_DEFAULT;
214

Steven Rostedt's avatar
Steven Rostedt committed
215
/* trace_types holds a link list of available tracers. */
216
static struct tracer		*trace_types __read_mostly;
Steven Rostedt's avatar
Steven Rostedt committed
217
218

/* current_trace points to the tracer that is currently active */
219
static struct tracer		*current_trace __read_mostly;
Steven Rostedt's avatar
Steven Rostedt committed
220
221
222
223
224
225

/*
 * max_tracer_type_len is used to simplify the allocating of
 * buffers to read userspace tracer names. We keep track of
 * the longest tracer name registered.
 */
226
227
static int			max_tracer_type_len;

Steven Rostedt's avatar
Steven Rostedt committed
228
229
230
231
232
233
/*
 * trace_types_lock is used to protect the trace_types list.
 * This lock is also used to keep user access serialized.
 * Accesses from userspace will grab this lock while userspace
 * activities happen inside the kernel.
 */
234
static DEFINE_MUTEX(trace_types_lock);
Steven Rostedt's avatar
Steven Rostedt committed
235
236

/* trace_wait is a waitqueue for tasks blocked on trace_poll */
237
238
static DECLARE_WAIT_QUEUE_HEAD(trace_wait);

239
/* trace_flags holds trace_options default values */
240
unsigned long trace_flags = TRACE_ITER_PRINT_PARENT | TRACE_ITER_PRINTK |
241
	TRACE_ITER_ANNOTATE | TRACE_ITER_CONTEXT_INFO;
242

Steven Rostedt's avatar
Steven Rostedt committed
243
244
245
246
247
248
/**
 * trace_wake_up - wake up tasks waiting for trace input
 *
 * Simply wakes up any task that is blocked on the trace_wait
 * queue. These is used with trace_poll for tasks polling the trace.
 */
249
250
void trace_wake_up(void)
{
Ingo Molnar's avatar
Ingo Molnar committed
251
252
253
254
255
	/*
	 * The runqueue_is_locked() can fail, but this is the best we
	 * have for now:
	 */
	if (!(trace_flags & TRACE_ITER_BLOCK) && !runqueue_is_locked())
256
257
		wake_up(&trace_wait);
}
258

259
static int __init set_buf_size(char *str)
260
{
261
	unsigned long buf_size;
262
263
	int ret;

264
265
	if (!str)
		return 0;
266
	ret = strict_strtoul(str, 0, &buf_size);
267
	/* nr_entries can not be zero */
268
	if (ret < 0 || buf_size == 0)
269
		return 0;
270
	trace_buf_size = buf_size;
271
272
	return 1;
}
273
__setup("trace_buf_size=", set_buf_size);
274

Steven Rostedt's avatar
Steven Rostedt committed
275
276
277
278
279
unsigned long nsecs_to_usecs(unsigned long nsecs)
{
	return nsecs / 1000;
}

Steven Rostedt's avatar
Steven Rostedt committed
280
/* These must match the bit postions in trace_iterator_flags */
281
282
283
284
285
static const char *trace_options[] = {
	"print-parent",
	"sym-offset",
	"sym-addr",
	"verbose",
Ingo Molnar's avatar
Ingo Molnar committed
286
	"raw",
287
	"hex",
Ingo Molnar's avatar
Ingo Molnar committed
288
	"bin",
289
	"block",
Ingo Molnar's avatar
Ingo Molnar committed
290
	"stacktrace",
Ingo Molnar's avatar
Ingo Molnar committed
291
	"sched-tree",
292
	"ftrace_printk",
293
	"ftrace_preempt",
294
	"branch",
295
	"annotate",
296
	"userstacktrace",
297
	"sym-userobj",
298
	"printk-msg-only",
299
	"context-info",
300
301
302
	NULL
};

Steven Rostedt's avatar
Steven Rostedt committed
303
304
305
306
307
308
309
310
311
/*
 * 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.
 *
 * This is defined as a raw_spinlock_t in order to help
 * with performance when lockdep debugging is enabled.
 */
312
313
static raw_spinlock_t ftrace_max_lock =
	(raw_spinlock_t)__RAW_SPIN_LOCK_UNLOCKED;
314
315
316
317
318
319

/*
 * Copy the new maximum trace into the separate maximum-trace
 * structure. (this way the maximum trace is permanently saved,
 * for later retrieval via /debugfs/tracing/latency_trace)
 */
Ingo Molnar's avatar
Ingo Molnar committed
320
static void
321
322
323
324
325
326
327
328
329
330
331
332
__update_max_tr(struct trace_array *tr, struct task_struct *tsk, int cpu)
{
	struct trace_array_cpu *data = tr->data[cpu];

	max_tr.cpu = cpu;
	max_tr.time_start = data->preempt_timestamp;

	data = max_tr.data[cpu];
	data->saved_latency = tracing_max_latency;

	memcpy(data->comm, tsk->comm, TASK_COMM_LEN);
	data->pid = tsk->pid;
333
	data->uid = task_uid(tsk);
334
335
336
337
338
339
340
341
	data->nice = tsk->static_prio - 20 - MAX_RT_PRIO;
	data->policy = tsk->policy;
	data->rt_priority = tsk->rt_priority;

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

Ingo Molnar's avatar
Ingo Molnar committed
342
static void
343
344
345
trace_seq_reset(struct trace_seq *s)
{
	s->len = 0;
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
	s->readpos = 0;
}

ssize_t trace_seq_to_user(struct trace_seq *s, char __user *ubuf, size_t cnt)
{
	int len;
	int ret;

	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);
	if (ret)
		return -EFAULT;

	s->readpos += len;
	return cnt;
366
367
}

368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
ssize_t trace_seq_to_buffer(struct trace_seq *s, void *buf, size_t cnt)
{
	int len;
	void *ret;

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

	len = s->len - s->readpos;
	if (cnt > len)
		cnt = len;
	ret = memcpy(buf, s->buffer + s->readpos, cnt);
	if (!ret)
		return -EFAULT;

	s->readpos += len;
	return cnt;
}

Ingo Molnar's avatar
Ingo Molnar committed
387
static void
388
389
390
391
392
393
394
395
396
397
trace_print_seq(struct seq_file *m, struct trace_seq *s)
{
	int len = s->len >= PAGE_SIZE ? PAGE_SIZE - 1 : s->len;

	s->buffer[len] = 0;
	seq_puts(m, s->buffer);

	trace_seq_reset(s);
}

Steven Rostedt's avatar
Steven Rostedt committed
398
399
400
401
402
403
404
405
406
/**
 * 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
407
void
408
409
update_max_tr(struct trace_array *tr, struct task_struct *tsk, int cpu)
{
410
	struct ring_buffer *buf = tr->buffer;
411

412
	WARN_ON_ONCE(!irqs_disabled());
413
	__raw_spin_lock(&ftrace_max_lock);
414
415
416
417

	tr->buffer = max_tr.buffer;
	max_tr.buffer = buf;

418
	ftrace_disable_cpu();
419
	ring_buffer_reset(tr->buffer);
420
	ftrace_enable_cpu();
421
422

	__update_max_tr(tr, tsk, cpu);
423
	__raw_spin_unlock(&ftrace_max_lock);
424
425
426
427
428
429
430
}

/**
 * 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
431
432
 *
 * Flip the trace of a single CPU buffer between the @tr and the max_tr.
433
 */
Ingo Molnar's avatar
Ingo Molnar committed
434
void
435
436
update_max_tr_single(struct trace_array *tr, struct task_struct *tsk, int cpu)
{
437
	int ret;
438

439
	WARN_ON_ONCE(!irqs_disabled());
440
	__raw_spin_lock(&ftrace_max_lock);
441

442
443
	ftrace_disable_cpu();

444
445
446
	ring_buffer_reset(max_tr.buffer);
	ret = ring_buffer_swap_cpu(max_tr.buffer, tr->buffer, cpu);

447
448
	ftrace_enable_cpu();

449
	WARN_ON_ONCE(ret && ret != -EAGAIN);
450
451

	__update_max_tr(tr, tsk, cpu);
452
	__raw_spin_unlock(&ftrace_max_lock);
453
454
}

Steven Rostedt's avatar
Steven Rostedt committed
455
456
457
458
459
460
/**
 * register_tracer - register a tracer with the ftrace system.
 * @type - the plugin for the tracer
 *
 * Register a new plugin tracer.
 */
461
462
463
464
465
466
467
468
469
470
471
int register_tracer(struct tracer *type)
{
	struct tracer *t;
	int len;
	int ret = 0;

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

Ingo Molnar's avatar
Ingo Molnar committed
472
473
474
475
476
477
478
	/*
	 * When this gets called we hold the BKL which means that
	 * preemption is disabled. Various trace selftests however
	 * need to disable and enable preemption for successful tests.
	 * So we drop the BKL here and grab it after the tests again.
	 */
	unlock_kernel();
479
	mutex_lock(&trace_types_lock);
Ingo Molnar's avatar
Ingo Molnar committed
480

481
482
	tracing_selftest_running = true;

483
484
485
486
487
488
489
490
491
492
	for (t = trace_types; t; t = t->next) {
		if (strcmp(type->name, t->name) == 0) {
			/* already found */
			pr_info("Trace %s already registered\n",
				type->name);
			ret = -1;
			goto out;
		}
	}

493
494
495
496
497
498
499
500
	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;

Steven Rostedt's avatar
Steven Rostedt committed
501
#ifdef CONFIG_FTRACE_STARTUP_TEST
502
	if (type->selftest && !tracing_selftest_disabled) {
Steven Rostedt's avatar
Steven Rostedt committed
503
504
505
		struct tracer *saved_tracer = current_trace;
		struct trace_array *tr = &global_trace;
		int i;
506

Steven Rostedt's avatar
Steven Rostedt committed
507
508
509
510
511
512
513
		/*
		 * 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.
		 */
Ingo Molnar's avatar
Ingo Molnar committed
514
		for_each_tracing_cpu(i)
515
			tracing_reset(tr, i);
Ingo Molnar's avatar
Ingo Molnar committed
516

Steven Rostedt's avatar
Steven Rostedt committed
517
518
519
520
521
522
523
524
525
526
		current_trace = type;
		/* 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 */
		current_trace = saved_tracer;
		if (ret) {
			printk(KERN_CONT "FAILED!\n");
			goto out;
		}
Steven Rostedt's avatar
Steven Rostedt committed
527
		/* Only reset on passing, to avoid touching corrupted buffers */
Ingo Molnar's avatar
Ingo Molnar committed
528
		for_each_tracing_cpu(i)
529
			tracing_reset(tr, i);
Ingo Molnar's avatar
Ingo Molnar committed
530

Steven Rostedt's avatar
Steven Rostedt committed
531
532
533
534
		printk(KERN_CONT "PASSED\n");
	}
#endif

535
536
537
538
539
	type->next = trace_types;
	trace_types = type;
	len = strlen(type->name);
	if (len > max_tracer_type_len)
		max_tracer_type_len = len;
Steven Rostedt's avatar
Steven Rostedt committed
540

541
 out:
542
	tracing_selftest_running = false;
543
544
	mutex_unlock(&trace_types_lock);

Steven Rostedt's avatar
Steven Rostedt committed
545
546
547
548
549
550
551
552
553
554
555
556
	if (ret || !default_bootup_tracer)
		goto out_unlock;

	if (strncmp(default_bootup_tracer, type->name, BOOTUP_TRACER_SIZE))
		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. */
	tracing_selftest_disabled = 1;
557
#ifdef CONFIG_FTRACE_STARTUP_TEST
Steven Rostedt's avatar
Steven Rostedt committed
558
559
	printk(KERN_INFO "Disabling FTRACE selftests due to running tracer '%s'\n",
	       type->name);
560
561
#endif

Steven Rostedt's avatar
Steven Rostedt committed
562
 out_unlock:
563
	lock_kernel();
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
	return ret;
}

void unregister_tracer(struct tracer *type)
{
	struct tracer **t;
	int len;

	mutex_lock(&trace_types_lock);
	for (t = &trace_types; *t; t = &(*t)->next) {
		if (*t == type)
			goto found;
	}
	pr_info("Trace %s not registered\n", type->name);
	goto out;

 found:
	*t = (*t)->next;
582
583
584
585
586
587
588
589
590

	if (type == current_trace && tracer_enabled) {
		tracer_enabled = 0;
		tracing_stop();
		if (current_trace->stop)
			current_trace->stop(&global_trace);
		current_trace = &nop_trace;
	}

591
592
593
594
595
596
597
598
599
600
601
602
603
	if (strlen(type->name) != max_tracer_type_len)
		goto out;

	max_tracer_type_len = 0;
	for (t = &trace_types; *t; t = &(*t)->next) {
		len = strlen((*t)->name);
		if (len > max_tracer_type_len)
			max_tracer_type_len = len;
	}
 out:
	mutex_unlock(&trace_types_lock);
}

604
void tracing_reset(struct trace_array *tr, int cpu)
605
{
606
	ftrace_disable_cpu();
607
	ring_buffer_reset_cpu(tr->buffer, cpu);
608
	ftrace_enable_cpu();
609
610
}

611
612
613
614
615
616
617
618
619
620
void tracing_reset_online_cpus(struct trace_array *tr)
{
	int cpu;

	tr->time_start = ftrace_now(tr->cpu);

	for_each_online_cpu(cpu)
		tracing_reset(tr, cpu);
}

621
622
623
624
625
626
#define SAVED_CMDLINES 128
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;
static DEFINE_SPINLOCK(trace_cmdline_lock);
627
628
629

/* temporary disable recording */
atomic_t trace_record_cmdline_disabled __read_mostly;
630
631
632
633
634
635
636
637

static void trace_init_cmdlines(void)
{
	memset(&map_pid_to_cmdline, -1, sizeof(map_pid_to_cmdline));
	memset(&map_cmdline_to_pid, -1, sizeof(map_cmdline_to_pid));
	cmdline_idx = 0;
}

638
639
640
static int trace_stop_count;
static DEFINE_SPINLOCK(tracing_start_lock);

641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
/**
 * 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();
}

656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
/**
 * 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;

	spin_lock_irqsave(&tracing_start_lock, flags);
671
672
673
674
675
676
	if (--trace_stop_count) {
		if (trace_stop_count < 0) {
			/* Someone screwed up their debugging */
			WARN_ON_ONCE(1);
			trace_stop_count = 0;
		}
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
		goto out;
	}


	buffer = global_trace.buffer;
	if (buffer)
		ring_buffer_record_enable(buffer);

	buffer = max_tr.buffer;
	if (buffer)
		ring_buffer_record_enable(buffer);

	ftrace_start();
 out:
	spin_unlock_irqrestore(&tracing_start_lock, flags);
}

/**
 * tracing_stop - quick stop of the tracer
 *
 * Light weight way to stop tracing. Use in conjunction with
 * tracing_start.
 */
void tracing_stop(void)
{
	struct ring_buffer *buffer;
	unsigned long flags;

	ftrace_stop();
	spin_lock_irqsave(&tracing_start_lock, flags);
	if (trace_stop_count++)
		goto out;

	buffer = global_trace.buffer;
	if (buffer)
		ring_buffer_record_disable(buffer);

	buffer = max_tr.buffer;
	if (buffer)
		ring_buffer_record_disable(buffer);

 out:
	spin_unlock_irqrestore(&tracing_start_lock, flags);
}

Ingo Molnar's avatar
Ingo Molnar committed
722
void trace_stop_cmdline_recording(void);
723

Ingo Molnar's avatar
Ingo Molnar committed
724
static void trace_save_cmdline(struct task_struct *tsk)
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
{
	unsigned map;
	unsigned idx;

	if (!tsk->pid || unlikely(tsk->pid > PID_MAX_DEFAULT))
		return;

	/*
	 * It's not the end of the world if we don't get
	 * the lock, but we also don't want to spin
	 * nor do we want to disable interrupts,
	 * so if we miss here, then better luck next time.
	 */
	if (!spin_trylock(&trace_cmdline_lock))
		return;

	idx = map_pid_to_cmdline[tsk->pid];
	if (idx >= SAVED_CMDLINES) {
		idx = (cmdline_idx + 1) % SAVED_CMDLINES;

		map = map_cmdline_to_pid[idx];
		if (map <= PID_MAX_DEFAULT)
			map_pid_to_cmdline[map] = (unsigned)-1;

		map_pid_to_cmdline[tsk->pid] = idx;

		cmdline_idx = idx;
	}

	memcpy(&saved_cmdlines[idx], tsk->comm, TASK_COMM_LEN);

	spin_unlock(&trace_cmdline_lock);
}

759
char *trace_find_cmdline(int pid)
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
{
	char *cmdline = "<...>";
	unsigned map;

	if (!pid)
		return "<idle>";

	if (pid > PID_MAX_DEFAULT)
		goto out;

	map = map_pid_to_cmdline[pid];
	if (map >= SAVED_CMDLINES)
		goto out;

	cmdline = saved_cmdlines[map];

 out:
	return cmdline;
}

Ingo Molnar's avatar
Ingo Molnar committed
780
void tracing_record_cmdline(struct task_struct *tsk)
781
782
783
784
785
786
787
{
	if (atomic_read(&trace_record_cmdline_disabled))
		return;

	trace_save_cmdline(tsk);
}

788
void
789
790
tracing_generic_entry_update(struct trace_entry *entry, unsigned long flags,
			     int pc)
791
792
793
{
	struct task_struct *tsk = current;

794
795
	entry->preempt_count		= pc & 0xff;
	entry->pid			= (tsk) ? tsk->pid : 0;
796
	entry->tgid               	= (tsk) ? tsk->tgid : 0;
797
	entry->flags =
798
#ifdef CONFIG_TRACE_IRQFLAGS_SUPPORT
799
		(irqs_disabled_flags(flags) ? TRACE_FLAG_IRQS_OFF : 0) |
800
801
802
#else
		TRACE_FLAG_IRQS_NOSUPPORT |
#endif
803
804
805
806
807
		((pc & HARDIRQ_MASK) ? TRACE_FLAG_HARDIRQ : 0) |
		((pc & SOFTIRQ_MASK) ? TRACE_FLAG_SOFTIRQ : 0) |
		(need_resched() ? TRACE_FLAG_NEED_RESCHED : 0);
}

808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
struct ring_buffer_event *trace_buffer_lock_reserve(struct trace_array *tr,
						    unsigned char type,
						    unsigned long len,
						    unsigned long flags, int pc)
{
	struct ring_buffer_event *event;

	event = ring_buffer_lock_reserve(tr->buffer, len);
	if (event != NULL) {
		struct trace_entry *ent = ring_buffer_event_data(event);

		tracing_generic_entry_update(ent, flags, pc);
		ent->type = type;
	}

	return event;
}
static void ftrace_trace_stack(struct trace_array *tr,
			       unsigned long flags, int skip, int pc);
static void ftrace_trace_userstack(struct trace_array *tr,
				   unsigned long flags, int pc);

void trace_buffer_unlock_commit(struct trace_array *tr,
				struct ring_buffer_event *event,
				unsigned long flags, int pc)
{
	ring_buffer_unlock_commit(tr->buffer, event);

	ftrace_trace_stack(tr, flags, 6, pc);
	ftrace_trace_userstack(tr, flags, pc);
	trace_wake_up();
}

Ingo Molnar's avatar
Ingo Molnar committed
841
void
842
trace_function(struct trace_array *tr,
843
844
	       unsigned long ip, unsigned long parent_ip, unsigned long flags,
	       int pc)
845
{
846
	struct ring_buffer_event *event;
847
	struct ftrace_entry *entry;
848

849
850
851
852
	/* If we are reading the ring buffer, don't trace */
	if (unlikely(local_read(&__get_cpu_var(ftrace_cpu_disabled))))
		return;

853
854
	event = trace_buffer_lock_reserve(tr, TRACE_FN, sizeof(*entry),
					  flags, pc);
855
856
857
	if (!event)
		return;
	entry	= ring_buffer_event_data(event);
858
859
	entry->ip			= ip;
	entry->parent_ip		= parent_ip;
860
	ring_buffer_unlock_commit(tr->buffer, event);
861
862
}

863
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
864
865
866
867
868
869
870
871
872
873
874
static void __trace_graph_entry(struct trace_array *tr,
				struct ftrace_graph_ent *trace,
				unsigned long flags,
				int pc)
{
	struct ring_buffer_event *event;
	struct ftrace_graph_ent_entry *entry;

	if (unlikely(local_read(&__get_cpu_var(ftrace_cpu_disabled))))
		return;

875
876
	event = trace_buffer_lock_reserve(&global_trace, TRACE_GRAPH_ENT,
					  sizeof(*entry), flags, pc);
877
878
879
880
	if (!event)
		return;
	entry	= ring_buffer_event_data(event);
	entry->graph_ent			= *trace;
881
	ring_buffer_unlock_commit(global_trace.buffer, event);
882
883
884
}

static void __trace_graph_return(struct trace_array *tr,
885
				struct ftrace_graph_ret *trace,
886
887
888
889
				unsigned long flags,
				int pc)
{
	struct ring_buffer_event *event;
890
	struct ftrace_graph_ret_entry *entry;
891
892
893
894

	if (unlikely(local_read(&__get_cpu_var(ftrace_cpu_disabled))))
		return;

895
896
	event = trace_buffer_lock_reserve(&global_trace, TRACE_GRAPH_RET,
					  sizeof(*entry), flags, pc);
897
898
899
	if (!event)
		return;
	entry	= ring_buffer_event_data(event);
900
	entry->ret				= *trace;
901
	ring_buffer_unlock_commit(global_trace.buffer, event);
902
903
904
}
#endif

Ingo Molnar's avatar
Ingo Molnar committed
905
void
Ingo Molnar's avatar
Ingo Molnar committed
906
ftrace(struct trace_array *tr, struct trace_array_cpu *data,
907
908
       unsigned long ip, unsigned long parent_ip, unsigned long flags,
       int pc)
Ingo Molnar's avatar
Ingo Molnar committed
909
910
{
	if (likely(!atomic_read(&data->disabled)))
911
		trace_function(tr, ip, parent_ip, flags, pc);
Ingo Molnar's avatar
Ingo Molnar committed
912
913
}

914
915
916
static void __ftrace_trace_stack(struct trace_array *tr,
				 unsigned long flags,
				 int skip, int pc)
Ingo Molnar's avatar
Ingo Molnar committed
917
{
918
#ifdef CONFIG_STACKTRACE
919
	struct ring_buffer_event *event;
920
	struct stack_entry *entry;
Ingo Molnar's avatar
Ingo Molnar committed
921
922
	struct stack_trace trace;

923
924
	event = trace_buffer_lock_reserve(tr, TRACE_STACK,
					  sizeof(*entry), flags, pc);
925
926
927
	if (!event)
		return;
	entry	= ring_buffer_event_data(event);
928
	memset(&entry->caller, 0, sizeof(entry->caller));
Ingo Molnar's avatar
Ingo Molnar committed
929
930
931
932

	trace.nr_entries	= 0;
	trace.max_entries	= FTRACE_STACK_ENTRIES;
	trace.skip		= skip;
933
	trace.entries		= entry->caller;
Ingo Molnar's avatar
Ingo Molnar committed
934
935

	save_stack_trace(&trace);
936
	ring_buffer_unlock_commit(tr->buffer, event);
937
#endif
Ingo Molnar's avatar
Ingo Molnar committed
938
939
}

940
941
942
943
944
945
946
static void ftrace_trace_stack(struct trace_array *tr,
			       unsigned long flags,
			       int skip, int pc)
{
	if (!(trace_flags & TRACE_ITER_STACKTRACE))
		return;

947
	__ftrace_trace_stack(tr, flags, skip, pc);
948
949
}

950
951
void __trace_stack(struct trace_array *tr,
		   unsigned long flags,
952
		   int skip, int pc)
953
{
954
	__ftrace_trace_stack(tr, flags, skip, pc);
955
956
}

957
static void ftrace_trace_userstack(struct trace_array *tr,
958
				   unsigned long flags, int pc)
959
{
960
#ifdef CONFIG_STACKTRACE
961
	struct ring_buffer_event *event;
962
963
964
965
966
967
	struct userstack_entry *entry;
	struct stack_trace trace;

	if (!(trace_flags & TRACE_ITER_USERSTACKTRACE))
		return;

968
969
	event = trace_buffer_lock_reserve(tr, TRACE_USER_STACK,
					  sizeof(*entry), flags, pc);
970
971
972
973
974
975
976
977
978
979
980
981
	if (!event)
		return;
	entry	= ring_buffer_event_data(event);

	memset(&entry->caller, 0, sizeof(entry->caller));

	trace.nr_entries	= 0;
	trace.max_entries	= FTRACE_STACK_ENTRIES;
	trace.skip		= 0;
	trace.entries		= entry->caller;

	save_stack_trace_user(&trace);
982
	ring_buffer_unlock_commit(tr->buffer, event);
983
#endif
984
985
}

986
void __trace_userstack(struct trace_array *tr, unsigned long flags)
987
{
988
	ftrace_trace_userstack(tr, flags, preempt_count());
989
990
}

991
static void
992
ftrace_trace_special(void *__tr,
993
994
		     unsigned long arg1, unsigned long arg2, unsigned long arg3,
		     int pc)
Ingo Molnar's avatar
Ingo Molnar committed
995
{
996
	struct ring_buffer_event *event;
Ingo Molnar's avatar
Ingo Molnar committed
997
	struct trace_array *tr = __tr;
998
	struct special_entry *entry;
Ingo Molnar's avatar
Ingo Molnar committed
999

1000
1001
	event = trace_buffer_lock_reserve(tr, TRACE_SPECIAL,
					  sizeof(*entry), 0, pc);
1002
1003
1004
	if (!event)
		return;
	entry	= ring_buffer_event_data(event);
1005
1006
1007
	entry->arg1			= arg1;
	entry->arg2			= arg2;
	entry->arg3			= arg3;
1008
	trace_buffer_unlock_commit(tr, event, 0, pc);
Ingo Molnar's avatar
Ingo Molnar committed
1009
1010
}

1011
1012
1013
1014
void
__trace_special(void *__tr, void *__data,
		unsigned long arg1, unsigned long arg2, unsigned long arg3)
{
1015
	ftrace_trace_special(__tr, arg1, arg2, arg3, preempt_count());
1016
1017
}

Ingo Molnar's avatar
Ingo Molnar committed
1018
void
1019
tracing_sched_switch_trace(struct trace_array *tr,
Ingo Molnar's avatar
Ingo Molnar committed
1020
1021
			   struct task_struct *prev,
			   struct task_struct *next,
1022
			   unsigned long flags, int pc)
1023
{
1024
	struct ring_buffer_event *event;
1025
	struct ctx_switch_entry *entry;
1026

1027
1028
	event = trace_buffer_lock_reserve(tr, TRACE_CTX,
					  sizeof(*entry), flags, pc);
1029
1030
1031
	if (!event)
		return;
	entry	= ring_buffer_event_data(event);
1032
1033
1034
1035
1036
1037
1038
	entry->prev_pid			= prev->pid;
	entry->prev_prio		= prev->prio;
	entry->prev_state		= prev->state;
	entry->next_pid			= next->pid;
	entry->next_prio		= next->prio;
	entry->next_state		= next->state;
	entry->next_cpu	= task_cpu(next);
1039
	trace_buffer_unlock_commit(tr, event, flags, pc);
1040
1041
}

1042
1043
void
tracing_sched_wakeup_trace(struct trace_array *tr,
Ingo Molnar's avatar
Ingo Molnar committed
1044
1045
			   struct task_struct *wakee,
			   struct task_struct *curr,
1046
			   unsigned long flags, int pc)
1047
{
1048
	struct ring_buffer_event *event;
1049
	struct ctx_switch_entry *entry;
1050

1051
1052
	event = trace_buffer_lock_reserve(tr, TRACE_WAKE,
					  sizeof(*entry), flags, pc);
1053
1054
1055
	if (!event)
		return;
	entry	= ring_buffer_event_data(event);
1056
1057
1058
1059
1060
1061
1062
	entry->prev_pid			= curr->pid;
	entry->prev_prio		= curr->prio;
	entry->prev_state		= curr->state;
	entry->next_pid			= wakee->pid;
	entry->next_prio		= wakee->prio;
	entry->next_state		= wakee->state;
	entry->next_cpu			= task_cpu(wakee);
1063
	trace_buffer_unlock_commit(tr, event, flags, pc);
1064
1065
}

1066
1067
1068
1069
1070
void
ftrace_special(unsigned long arg1, unsigned long arg2, unsigned long arg3)
{
	struct trace_array *tr = &global_trace;
	struct trace_array_cpu *data;
1071
	unsigned long flags;
1072
	int cpu;
1073
	int pc;
1074

1075
	if (tracing_disabled)
1076
1077
		return;

1078
	pc = preempt_count();
1079
	local_irq_save(flags);
1080
1081
1082
	cpu = raw_smp_processor_id();
	data = tr->data[cpu];

1083
	if (likely(atomic_inc_return(&data->disabled) == 1))
1084
		ftrace_trace_special(tr, arg1, arg2, arg3, pc);
1085

1086
1087
	atomic_dec(&data->disabled);
	local_irq_restore(flags);
1088
1089
}

1090
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
1091
int trace_graph_entry(struct ftrace_graph_ent *trace)
1092
1093
1094
1095
1096
1097
1098
1099
{
	struct trace_array *tr = &global_trace;
	struct trace_array_cpu *data;
	unsigned long flags;
	long disabled;
	int cpu;
	int pc;

1100
1101
1102
	if (!ftrace_trace_task(current))
		return 0;

1103
1104
1105
	if (!ftrace_graph_addr(trace->func))
		return 0;

1106
	local_irq_save(flags);
1107
1108
1109
1110
1111
	cpu = raw_smp_processor_id();
	data = tr->data[cpu];
	disabled = atomic_inc_return(&data->disabled);
	if (likely(disabled == 1)) {
		pc = preempt_count();
1112
		__trace_graph_entry(tr, trace, flags, pc);
1113
	}
1114
1115
1116
	/* Only do the atomic if it is not already set */
	if (!test_tsk_trace_graph(current))
		set_tsk_trace_graph(current);
1117
	atomic_dec(&data->disabled);
1118
	local_irq_restore(flags);
1119
1120

	return 1;
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
}

void trace_graph_return(struct ftrace_graph_ret *trace)
{
	struct trace_array *tr = &global_trace;
	struct trace_array_cpu *data;
	unsigned long flags;
	long disabled;
	int cpu;
	int pc;

1132
	local_irq_save(flags);
1133
1134
1135
1136
1137
	cpu = raw_smp_processor_id();
	data = tr->data[cpu];
	disabled = atomic_inc_return(&data->disabled);
	if (likely(disabled == 1)) {
		pc = preempt_count();
1138
		__trace_graph_return(tr, trace, flags, pc);
1139
	}
1140
1141
	if (!trace->depth)
		clear_tsk_trace_graph(current);
1142
	atomic_dec(&data->disabled);
1143
	local_irq_restore(flags);
1144
}
1145
#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
1146

1147
1148
enum trace_file_type {
	TRACE_FILE_LAT_FMT	= 1,
1149
	TRACE_FILE_ANNOTATE	= 2,
1150
1151
};

1152
static void trace_iterator_increment(struct trace_iterator *iter)
1153
{
1154
1155
1156
	/* Don't allow ftrace to trace into the ring buffers */
	ftrace_disable_cpu();

1157
	iter->idx++;
1158
1159
1160
1161
	if (iter->buffer_iter[iter->cpu])
		ring_buffer_read(iter->buffer_iter[iter->cpu], NULL);

	ftrace_enable_cpu();
1162
1163
}

Ingo Molnar's avatar
Ingo Molnar committed
1164
static struct trace_entry *
1165
peek_next_entry(struct trace_iterator *iter, int cpu, u64 *ts)
1166
{
1167
1168
	struct ring_buffer_event *event;
	struct ring_buffer_iter *buf_iter = iter->buffer_iter[cpu];
1169

1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
	/* Don't allow ftrace to trace into the ring buffers */
	ftrace_disable_cpu();

	if (buf_iter)
		event = ring_buffer_iter_peek(buf_iter, ts);
	else
		event = ring_buffer_peek(iter->tr->buffer, cpu, ts);

	ftrace_enable_cpu();

1180
	return event ? ring_buffer_event_data(event) : NULL;
1181
}
1182

1183
static struct trace_entry *
1184
__find_next_entry(struct trace_iterator *iter, int *ent_cpu, u64 *ent_ts)
1185
{
1186
	struct ring_buffer *buffer = iter->tr->buffer;
1187
	struct trace_entry *ent, *next = NULL;
1188
	u64 next_ts = 0, ts;
1189
1190
1191
	int next_cpu = -1;
	int cpu;

1192
	for_each_tracing_cpu(cpu) {
1193

1194
1195
		if (ring_buffer_empty_cpu(buffer, cpu))
			continue;
1196

1197
		ent = peek_next_entry(iter, cpu, &ts);
1198

Ingo Molnar's avatar
Ingo Molnar committed
1199
1200
1201
		/*
		 * Pick the entry with the smallest timestamp:
		 */
1202
		if (ent && (!next || ts < next_ts)) {
1203
1204
			next = ent;
			next_cpu = cpu;
1205
			next_ts = ts;
1206
1207
1208
1209
1210
1211
		}
	}

	if (ent_cpu)
		*ent_cpu = next_cpu;

1212
1213
1214
	if (ent_ts)
		*ent_ts = next_ts;

1215
1216
1217
	return next;
}

1218
/* Find the next real entry, without updating the iterator itself */
1219
1220
struct trace_entry *trace_find_next_entry(struct trace_iterator *iter,
					  int *ent_cpu, u64 *ent_ts)
1221
{
1222
	return __find_next_entry(iter, ent_cpu, ent_ts);