aboutsummaryrefslogtreecommitdiff
path: root/tools/perf/util/thread-stack.c
blob: 61a4286a74dc9f86c333036013d5abe914b81b3f (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
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
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
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
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
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
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
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
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
/*
 * thread-stack.c: Synthesize a thread's stack using call / return events
 * Copyright (c) 2014, Intel Corporation.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 * more details.
 *
 */

#include <linux/rbtree.h>
#include <linux/list.h>
#include <errno.h>
#include "thread.h"
#include "event.h"
#include "machine.h"
#include "util.h"
#include "debug.h"
#include "symbol.h"
#include "comm.h"
#include "call-path.h"
#include "thread-stack.h"

#define STACK_GROWTH 2048

/**
 * struct thread_stack_entry - thread stack entry.
 * @ret_addr: return address
 * @timestamp: timestamp (if known)
 * @ref: external reference (e.g. db_id of sample)
 * @branch_count: the branch count when the entry was created
 * @cp: call path
 * @no_call: a 'call' was not seen
 * @trace_end: a 'call' but trace ended
 */
struct thread_stack_entry {
	u64 ret_addr;
	u64 timestamp;
	u64 ref;
	u64 branch_count;
	struct call_path *cp;
	bool no_call;
	bool trace_end;
};

/**
 * struct thread_stack - thread stack constructed from 'call' and 'return'
 *                       branch samples.
 * @stack: array that holds the stack
 * @cnt: number of entries in the stack
 * @sz: current maximum stack size
 * @trace_nr: current trace number
 * @branch_count: running branch count
 * @kernel_start: kernel start address
 * @last_time: last timestamp
 * @crp: call/return processor
 * @comm: current comm
 */
struct thread_stack {
	struct thread_stack_entry *stack;
	size_t cnt;
	size_t sz;
	u64 trace_nr;
	u64 branch_count;
	u64 kernel_start;
	u64 last_time;
	struct call_return_processor *crp;
	struct comm *comm;
};

static int thread_stack__grow(struct thread_stack *ts)
{
	struct thread_stack_entry *new_stack;
	size_t sz, new_sz;

	new_sz = ts->sz + STACK_GROWTH;
	sz = new_sz * sizeof(struct thread_stack_entry);

	new_stack = realloc(ts->stack, sz);
	if (!new_stack)
		return -ENOMEM;

	ts->stack = new_stack;
	ts->sz = new_sz;

	return 0;
}

static struct thread_stack *thread_stack__new(struct thread *thread,
					      struct call_return_processor *crp)
{
	struct thread_stack *ts;

	ts = zalloc(sizeof(struct thread_stack));
	if (!ts)
		return NULL;

	if (thread_stack__grow(ts)) {
		free(ts);
		return NULL;
	}

	if (thread->mg && thread->mg->machine)
		ts->kernel_start = machine__kernel_start(thread->mg->machine);
	else
		ts->kernel_start = 1ULL << 63;
	ts->crp = crp;

	return ts;
}

static int thread_stack__push(struct thread_stack *ts, u64 ret_addr,
			      bool trace_end)
{
	int err = 0;

	if (ts->cnt == ts->sz) {
		err = thread_stack__grow(ts);
		if (err) {
			pr_warning("Out of memory: discarding thread stack\n");
			ts->cnt = 0;
		}
	}

	ts->stack[ts->cnt].trace_end = trace_end;
	ts->stack[ts->cnt++].ret_addr = ret_addr;

	return err;
}

static void thread_stack__pop(struct thread_stack *ts, u64 ret_addr)
{
	size_t i;

	/*
	 * In some cases there may be functions which are not seen to return.
	 * For example when setjmp / longjmp has been used.  Or the perf context
	 * switch in the kernel which doesn't stop and start tracing in exactly
	 * the same code path.  When that happens the return address will be
	 * further down the stack.  If the return address is not found at all,
	 * we assume the opposite (i.e. this is a return for a call that wasn't
	 * seen for some reason) and leave the stack alone.
	 */
	for (i = ts->cnt; i; ) {
		if (ts->stack[--i].ret_addr == ret_addr) {
			ts->cnt = i;
			return;
		}
	}
}

static void thread_stack__pop_trace_end(struct thread_stack *ts)
{
	size_t i;

	for (i = ts->cnt; i; ) {
		if (ts->stack[--i].trace_end)
			ts->cnt = i;
		else
			return;
	}
}

static bool thread_stack__in_kernel(struct thread_stack *ts)
{
	if (!ts->cnt)
		return false;

	return ts->stack[ts->cnt - 1].cp->in_kernel;
}

static int thread_stack__call_return(struct thread *thread,
				     struct thread_stack *ts, size_t idx,
				     u64 timestamp, u64 ref, bool no_return)
{
	struct call_return_processor *crp = ts->crp;
	struct thread_stack_entry *tse;
	struct call_return cr = {
		.thread = thread,
		.comm = ts->comm,
		.db_id = 0,
	};

	tse = &ts->stack[idx];
	cr.cp = tse->cp;
	cr.call_time = tse->timestamp;
	cr.return_time = timestamp;
	cr.branch_count = ts->branch_count - tse->branch_count;
	cr.call_ref = tse->ref;
	cr.return_ref = ref;
	if (tse->no_call)
		cr.flags |= CALL_RETURN_NO_CALL;
	if (no_return)
		cr.flags |= CALL_RETURN_NO_RETURN;

	return crp->process(&cr, crp->data);
}

static int __thread_stack__flush(struct thread *thread, struct thread_stack *ts)
{
	struct call_return_processor *crp = ts->crp;
	int err;

	if (!crp) {
		ts->cnt = 0;
		return 0;
	}

	while (ts->cnt) {
		err = thread_stack__call_return(thread, ts, --ts->cnt,
						ts->last_time, 0, true);
		if (err) {
			pr_err("Error flushing thread stack!\n");
			ts->cnt = 0;
			return err;
		}
	}

	return 0;
}

int thread_stack__flush(struct thread *thread)
{
	if (thread->ts)
		return __thread_stack__flush(thread, thread->ts);

	return 0;
}

int thread_stack__event(struct thread *thread, u32 flags, u64 from_ip,
			u64 to_ip, u16 insn_len, u64 trace_nr)
{
	if (!thread)
		return -EINVAL;

	if (!thread->ts) {
		thread->ts = thread_stack__new(thread, NULL);
		if (!thread->ts) {
			pr_warning("Out of memory: no thread stack\n");
			return -ENOMEM;
		}
		thread->ts->trace_nr = trace_nr;
	}

	/*
	 * When the trace is discontinuous, the trace_nr changes.  In that case
	 * the stack might be completely invalid.  Better to report nothing than
	 * to report something misleading, so flush the stack.
	 */
	if (trace_nr != thread->ts->trace_nr) {
		if (thread->ts->trace_nr)
			__thread_stack__flush(thread, thread->ts);
		thread->ts->trace_nr = trace_nr;
	}

	/* Stop here if thread_stack__process() is in use */
	if (thread->ts->crp)
		return 0;

	if (flags & PERF_IP_FLAG_CALL) {
		u64 ret_addr;

		if (!to_ip)
			return 0;
		ret_addr = from_ip + insn_len;
		if (ret_addr == to_ip)
			return 0; /* Zero-length calls are excluded */
		return thread_stack__push(thread->ts, ret_addr,
					  flags & PERF_IP_FLAG_TRACE_END);
	} else if (flags & PERF_IP_FLAG_TRACE_BEGIN) {
		/*
		 * If the caller did not change the trace number (which would
		 * have flushed the stack) then try to make sense of the stack.
		 * Possibly, tracing began after returning to the current
		 * address, so try to pop that. Also, do not expect a call made
		 * when the trace ended, to return, so pop that.
		 */
		thread_stack__pop(thread->ts, to_ip);
		thread_stack__pop_trace_end(thread->ts);
	} else if ((flags & PERF_IP_FLAG_RETURN) && from_ip) {
		thread_stack__pop(thread->ts, to_ip);
	}

	return 0;
}

void thread_stack__set_trace_nr(struct thread *thread, u64 trace_nr)
{
	if (!thread || !thread->ts)
		return;

	if (trace_nr != thread->ts->trace_nr) {
		if (thread->ts->trace_nr)
			__thread_stack__flush(thread, thread->ts);
		thread->ts->trace_nr = trace_nr;
	}
}

void thread_stack__free(struct thread *thread)
{
	if (thread->ts) {
		__thread_stack__flush(thread, thread->ts);
		zfree(&thread->ts->stack);
		zfree(&thread->ts);
	}
}

static inline u64 callchain_context(u64 ip, u64 kernel_start)
{
	return ip < kernel_start ? PERF_CONTEXT_USER : PERF_CONTEXT_KERNEL;
}

void thread_stack__sample(struct thread *thread, struct ip_callchain *chain,
			  size_t sz, u64 ip, u64 kernel_start)
{
	u64 context = callchain_context(ip, kernel_start);
	u64 last_context;
	size_t i, j;

	if (sz < 2) {
		chain->nr = 0;
		return;
	}

	chain->ips[0] = context;
	chain->ips[1] = ip;

	if (!thread || !thread->ts) {
		chain->nr = 2;
		return;
	}

	last_context = context;

	for (i = 2, j = 1; i < sz && j <= thread->ts->cnt; i++, j++) {
		ip = thread->ts->stack[thread->ts->cnt - j].ret_addr;
		context = callchain_context(ip, kernel_start);
		if (context != last_context) {
			if (i >= sz - 1)
				break;
			chain->ips[i++] = context;
			last_context = context;
		}
		chain->ips[i] = ip;
	}

	chain->nr = i;
}

struct call_return_processor *
call_return_processor__new(int (*process)(struct call_return *cr, void *data),
			   void *data)
{
	struct call_return_processor *crp;

	crp = zalloc(sizeof(struct call_return_processor));
	if (!crp)
		return NULL;
	crp->cpr = call_path_root__new();
	if (!crp->cpr)
		goto out_free;
	crp->process = process;
	crp->data = data;
	return crp;

out_free:
	free(crp);
	return NULL;
}

void call_return_processor__free(struct call_return_processor *crp)
{
	if (crp) {
		call_path_root__free(crp->cpr);
		free(crp);
	}
}

static int thread_stack__push_cp(struct thread_stack *ts, u64 ret_addr,
				 u64 timestamp, u64 ref, struct call_path *cp,
				 bool no_call, bool trace_end)
{
	struct thread_stack_entry *tse;
	int err;

	if (ts->cnt == ts->sz) {
		err = thread_stack__grow(ts);
		if (err)
			return err;
	}

	tse = &ts->stack[ts->cnt++];
	tse->ret_addr = ret_addr;
	tse->timestamp = timestamp;
	tse->ref = ref;
	tse->branch_count = ts->branch_count;
	tse->cp = cp;
	tse->no_call = no_call;
	tse->trace_end = trace_end;

	return 0;
}

static int thread_stack__pop_cp(struct thread *thread, struct thread_stack *ts,
				u64 ret_addr, u64 timestamp, u64 ref,
				struct symbol *sym)
{
	int err;

	if (!ts->cnt)
		return 1;

	if (ts->cnt == 1) {
		struct thread_stack_entry *tse = &ts->stack[0];

		if (tse->cp->sym == sym)
			return thread_stack__call_return(thread, ts, --ts->cnt,
							 timestamp, ref, false);
	}

	if (ts->stack[ts->cnt - 1].ret_addr == ret_addr) {
		return thread_stack__call_return(thread, ts, --ts->cnt,
						 timestamp, ref, false);
	} else {
		size_t i = ts->cnt - 1;

		while (i--) {
			if (ts->stack[i].ret_addr != ret_addr)
				continue;
			i += 1;
			while (ts->cnt > i) {
				err = thread_stack__call_return(thread, ts,
								--ts->cnt,
								timestamp, ref,
								true);
				if (err)
					return err;
			}
			return thread_stack__call_return(thread, ts, --ts->cnt,
							 timestamp, ref, false);
		}
	}

	return 1;
}

static int thread_stack__bottom(struct thread *thread, struct thread_stack *ts,
				struct perf_sample *sample,
				struct addr_location *from_al,
				struct addr_location *to_al, u64 ref)
{
	struct call_path_root *cpr = ts->crp->cpr;
	struct call_path *cp;
	struct symbol *sym;
	u64 ip;

	if (sample->ip) {
		ip = sample->ip;
		sym = from_al->sym;
	} else if (sample->addr) {
		ip = sample->addr;
		sym = to_al->sym;
	} else {
		return 0;
	}

	cp = call_path__findnew(cpr, &cpr->call_path, sym, ip,
				ts->kernel_start);
	if (!cp)
		return -ENOMEM;

	return thread_stack__push_cp(thread->ts, ip, sample->time, ref, cp,
				     true, false);
}

static int thread_stack__no_call_return(struct thread *thread,
					struct thread_stack *ts,
					struct perf_sample *sample,
					struct addr_location *from_al,
					struct addr_location *to_al, u64 ref)
{
	struct call_path_root *cpr = ts->crp->cpr;
	struct call_path *cp, *parent;
	u64 ks = ts->kernel_start;
	int err;

	if (sample->ip >= ks && sample->addr < ks) {
		/* Return to userspace, so pop all kernel addresses */
		while (thread_stack__in_kernel(ts)) {
			err = thread_stack__call_return(thread, ts, --ts->cnt,
							sample->time, ref,
							true);
			if (err)
				return err;
		}

		/* If the stack is empty, push the userspace address */
		if (!ts->cnt) {
			cp = call_path__findnew(cpr, &cpr->call_path,
						to_al->sym, sample->addr,
						ts->kernel_start);
			if (!cp)
				return -ENOMEM;
			return thread_stack__push_cp(ts, 0, sample->time, ref,
						     cp, true, false);
		}
	} else if (thread_stack__in_kernel(ts) && sample->ip < ks) {
		/* Return to userspace, so pop all kernel addresses */
		while (thread_stack__in_kernel(ts)) {
			err = thread_stack__call_return(thread, ts, --ts->cnt,
							sample->time, ref,
							true);
			if (err)
				return err;
		}
	}

	if (ts->cnt)
		parent = ts->stack[ts->cnt - 1].cp;
	else
		parent = &cpr->call_path;

	/* This 'return' had no 'call', so push and pop top of stack */
	cp = call_path__findnew(cpr, parent, from_al->sym, sample->ip,
				ts->kernel_start);
	if (!cp)
		return -ENOMEM;

	err = thread_stack__push_cp(ts, sample->addr, sample->time, ref, cp,
				    true, false);
	if (err)
		return err;

	return thread_stack__pop_cp(thread, ts, sample->addr, sample->time, ref,
				    to_al->sym);
}

static int thread_stack__trace_begin(struct thread *thread,
				     struct thread_stack *ts, u64 timestamp,
				     u64 ref)
{
	struct thread_stack_entry *tse;
	int err;

	if (!ts->cnt)
		return 0;

	/* Pop trace end */
	tse = &ts->stack[ts->cnt - 1];
	if (tse->trace_end) {
		err = thread_stack__call_return(thread, ts, --ts->cnt,
						timestamp, ref, false);
		if (err)
			return err;
	}

	return 0;
}

static int thread_stack__trace_end(struct thread_stack *ts,
				   struct perf_sample *sample, u64 ref)
{
	struct call_path_root *cpr = ts->crp->cpr;
	struct call_path *cp;
	u64 ret_addr;

	/* No point having 'trace end' on the bottom of the stack */
	if (!ts->cnt || (ts->cnt == 1 && ts->stack[0].ref == ref))
		return 0;

	cp = call_path__findnew(cpr, ts->stack[ts->cnt - 1].cp, NULL, 0,
				ts->kernel_start);
	if (!cp)
		return -ENOMEM;

	ret_addr = sample->ip + sample->insn_len;

	return thread_stack__push_cp(ts, ret_addr, sample->time, ref, cp,
				     false, true);
}

int thread_stack__process(struct thread *thread, struct comm *comm,
			  struct perf_sample *sample,
			  struct addr_location *from_al,
			  struct addr_location *to_al, u64 ref,
			  struct call_return_processor *crp)
{
	struct thread_stack *ts = thread->ts;
	int err = 0;

	if (ts) {
		if (!ts->crp) {
			/* Supersede thread_stack__event() */
			thread_stack__free(thread);
			thread->ts = thread_stack__new(thread, crp);
			if (!thread->ts)
				return -ENOMEM;
			ts = thread->ts;
			ts->comm = comm;
		}
	} else {
		thread->ts = thread_stack__new(thread, crp);
		if (!thread->ts)
			return -ENOMEM;
		ts = thread->ts;
		ts->comm = comm;
	}

	/* Flush stack on exec */
	if (ts->comm != comm && thread->pid_ == thread->tid) {
		err = __thread_stack__flush(thread, ts);
		if (err)
			return err;
		ts->comm = comm;
	}

	/* If the stack is empty, put the current symbol on the stack */
	if (!ts->cnt) {
		err = thread_stack__bottom(thread, ts, sample, from_al, to_al,
					   ref);
		if (err)
			return err;
	}

	ts->branch_count += 1;
	ts->last_time = sample->time;

	if (sample->flags & PERF_IP_FLAG_CALL) {
		bool trace_end = sample->flags & PERF_IP_FLAG_TRACE_END;
		struct call_path_root *cpr = ts->crp->cpr;
		struct call_path *cp;
		u64 ret_addr;

		if (!sample->ip || !sample->addr)
			return 0;

		ret_addr = sample->ip + sample->insn_len;
		if (ret_addr == sample->addr)
			return 0; /* Zero-length calls are excluded */

		cp = call_path__findnew(cpr, ts->stack[ts->cnt - 1].cp,
					to_al->sym, sample->addr,
					ts->kernel_start);
		if (!cp)
			return -ENOMEM;
		err = thread_stack__push_cp(ts, ret_addr, sample->time, ref,
					    cp, false, trace_end);
	} else if (sample->flags & PERF_IP_FLAG_RETURN) {
		if (!sample->ip || !sample->addr)
			return 0;

		err = thread_stack__pop_cp(thread, ts, sample->addr,
					   sample->time, ref, from_al->sym);
		if (err) {
			if (err < 0)
				return err;
			err = thread_stack__no_call_return(thread, ts, sample,
							   from_al, to_al, ref);
		}
	} else if (sample->flags & PERF_IP_FLAG_TRACE_BEGIN) {
		err = thread_stack__trace_begin(thread, ts, sample->time, ref);
	} else if (sample->flags & PERF_IP_FLAG_TRACE_END) {
		err = thread_stack__trace_end(ts, sample, ref);
	}

	return err;
}

size_t thread_stack__depth(struct thread *thread)
{
	if (!thread->ts)
		return 0;
	return thread->ts->cnt;
}