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1/*
2 * thread-stack.c: Synthesize a thread's stack using call / return events
3 * Copyright (c) 2014, Intel Corporation.
4 *
5 * This program is free software; you can redistribute it and/or modify it
6 * under the terms and conditions of the GNU General Public License,
7 * version 2, as published by the Free Software Foundation.
8 *
9 * This program is distributed in the hope it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
12 * more details.
13 *
14 */
15
16#include <linux/rbtree.h>
17#include <linux/list.h>
18#include "thread.h"
19#include "event.h"
20#include "machine.h"
21#include "util.h"
22#include "debug.h"
23#include "symbol.h"
24#include "comm.h"
25#include "thread-stack.h"
26
27#define CALL_PATH_BLOCK_SHIFT 8
28#define CALL_PATH_BLOCK_SIZE (1 << CALL_PATH_BLOCK_SHIFT)
29#define CALL_PATH_BLOCK_MASK (CALL_PATH_BLOCK_SIZE - 1)
30
31struct call_path_block {
32 struct call_path cp[CALL_PATH_BLOCK_SIZE];
33 struct list_head node;
34};
35
36/**
37 * struct call_path_root - root of all call paths.
38 * @call_path: root call path
39 * @blocks: list of blocks to store call paths
40 * @next: next free space
41 * @sz: number of spaces
42 */
43struct call_path_root {
44 struct call_path call_path;
45 struct list_head blocks;
46 size_t next;
47 size_t sz;
48};
49
50/**
51 * struct call_return_processor - provides a call-back to consume call-return
52 * information.
53 * @cpr: call path root
54 * @process: call-back that accepts call/return information
55 * @data: anonymous data for call-back
56 */
57struct call_return_processor {
58 struct call_path_root *cpr;
59 int (*process)(struct call_return *cr, void *data);
60 void *data;
61};
62
63#define STACK_GROWTH 2048
64
65/**
66 * struct thread_stack_entry - thread stack entry.
67 * @ret_addr: return address
68 * @timestamp: timestamp (if known)
69 * @ref: external reference (e.g. db_id of sample)
70 * @branch_count: the branch count when the entry was created
71 * @cp: call path
72 * @no_call: a 'call' was not seen
73 */
74struct thread_stack_entry {
75 u64 ret_addr;
76 u64 timestamp;
77 u64 ref;
78 u64 branch_count;
79 struct call_path *cp;
80 bool no_call;
81};
82
83/**
84 * struct thread_stack - thread stack constructed from 'call' and 'return'
85 * branch samples.
86 * @stack: array that holds the stack
87 * @cnt: number of entries in the stack
88 * @sz: current maximum stack size
89 * @trace_nr: current trace number
90 * @branch_count: running branch count
91 * @kernel_start: kernel start address
92 * @last_time: last timestamp
93 * @crp: call/return processor
94 * @comm: current comm
95 */
96struct thread_stack {
97 struct thread_stack_entry *stack;
98 size_t cnt;
99 size_t sz;
100 u64 trace_nr;
101 u64 branch_count;
102 u64 kernel_start;
103 u64 last_time;
104 struct call_return_processor *crp;
105 struct comm *comm;
106};
107
108static int thread_stack__grow(struct thread_stack *ts)
109{
110 struct thread_stack_entry *new_stack;
111 size_t sz, new_sz;
112
113 new_sz = ts->sz + STACK_GROWTH;
114 sz = new_sz * sizeof(struct thread_stack_entry);
115
116 new_stack = realloc(ts->stack, sz);
117 if (!new_stack)
118 return -ENOMEM;
119
120 ts->stack = new_stack;
121 ts->sz = new_sz;
122
123 return 0;
124}
125
126static struct thread_stack *thread_stack__new(struct thread *thread,
127 struct call_return_processor *crp)
128{
129 struct thread_stack *ts;
130
131 ts = zalloc(sizeof(struct thread_stack));
132 if (!ts)
133 return NULL;
134
135 if (thread_stack__grow(ts)) {
136 free(ts);
137 return NULL;
138 }
139
140 if (thread->mg && thread->mg->machine)
141 ts->kernel_start = machine__kernel_start(thread->mg->machine);
142 else
143 ts->kernel_start = 1ULL << 63;
144 ts->crp = crp;
145
146 return ts;
147}
148
149static int thread_stack__push(struct thread_stack *ts, u64 ret_addr)
150{
151 int err = 0;
152
153 if (ts->cnt == ts->sz) {
154 err = thread_stack__grow(ts);
155 if (err) {
156 pr_warning("Out of memory: discarding thread stack\n");
157 ts->cnt = 0;
158 }
159 }
160
161 ts->stack[ts->cnt++].ret_addr = ret_addr;
162
163 return err;
164}
165
166static void thread_stack__pop(struct thread_stack *ts, u64 ret_addr)
167{
168 size_t i;
169
170 /*
171 * In some cases there may be functions which are not seen to return.
172 * For example when setjmp / longjmp has been used. Or the perf context
173 * switch in the kernel which doesn't stop and start tracing in exactly
174 * the same code path. When that happens the return address will be
175 * further down the stack. If the return address is not found at all,
176 * we assume the opposite (i.e. this is a return for a call that wasn't
177 * seen for some reason) and leave the stack alone.
178 */
179 for (i = ts->cnt; i; ) {
180 if (ts->stack[--i].ret_addr == ret_addr) {
181 ts->cnt = i;
182 return;
183 }
184 }
185}
186
187static bool thread_stack__in_kernel(struct thread_stack *ts)
188{
189 if (!ts->cnt)
190 return false;
191
192 return ts->stack[ts->cnt - 1].cp->in_kernel;
193}
194
195static int thread_stack__call_return(struct thread *thread,
196 struct thread_stack *ts, size_t idx,
197 u64 timestamp, u64 ref, bool no_return)
198{
199 struct call_return_processor *crp = ts->crp;
200 struct thread_stack_entry *tse;
201 struct call_return cr = {
202 .thread = thread,
203 .comm = ts->comm,
204 .db_id = 0,
205 };
206
207 tse = &ts->stack[idx];
208 cr.cp = tse->cp;
209 cr.call_time = tse->timestamp;
210 cr.return_time = timestamp;
211 cr.branch_count = ts->branch_count - tse->branch_count;
212 cr.call_ref = tse->ref;
213 cr.return_ref = ref;
214 if (tse->no_call)
215 cr.flags |= CALL_RETURN_NO_CALL;
216 if (no_return)
217 cr.flags |= CALL_RETURN_NO_RETURN;
218
219 return crp->process(&cr, crp->data);
220}
221
222static int __thread_stack__flush(struct thread *thread, struct thread_stack *ts)
223{
224 struct call_return_processor *crp = ts->crp;
225 int err;
226
227 if (!crp) {
228 ts->cnt = 0;
229 return 0;
230 }
231
232 while (ts->cnt) {
233 err = thread_stack__call_return(thread, ts, --ts->cnt,
234 ts->last_time, 0, true);
235 if (err) {
236 pr_err("Error flushing thread stack!\n");
237 ts->cnt = 0;
238 return err;
239 }
240 }
241
242 return 0;
243}
244
245int thread_stack__flush(struct thread *thread)
246{
247 if (thread->ts)
248 return __thread_stack__flush(thread, thread->ts);
249
250 return 0;
251}
252
253int thread_stack__event(struct thread *thread, u32 flags, u64 from_ip,
254 u64 to_ip, u16 insn_len, u64 trace_nr)
255{
256 if (!thread)
257 return -EINVAL;
258
259 if (!thread->ts) {
260 thread->ts = thread_stack__new(thread, NULL);
261 if (!thread->ts) {
262 pr_warning("Out of memory: no thread stack\n");
263 return -ENOMEM;
264 }
265 thread->ts->trace_nr = trace_nr;
266 }
267
268 /*
269 * When the trace is discontinuous, the trace_nr changes. In that case
270 * the stack might be completely invalid. Better to report nothing than
271 * to report something misleading, so flush the stack.
272 */
273 if (trace_nr != thread->ts->trace_nr) {
274 if (thread->ts->trace_nr)
275 __thread_stack__flush(thread, thread->ts);
276 thread->ts->trace_nr = trace_nr;
277 }
278
279 /* Stop here if thread_stack__process() is in use */
280 if (thread->ts->crp)
281 return 0;
282
283 if (flags & PERF_IP_FLAG_CALL) {
284 u64 ret_addr;
285
286 if (!to_ip)
287 return 0;
288 ret_addr = from_ip + insn_len;
289 if (ret_addr == to_ip)
290 return 0; /* Zero-length calls are excluded */
291 return thread_stack__push(thread->ts, ret_addr);
292 } else if (flags & PERF_IP_FLAG_RETURN) {
293 if (!from_ip)
294 return 0;
295 thread_stack__pop(thread->ts, to_ip);
296 }
297
298 return 0;
299}
300
301void thread_stack__set_trace_nr(struct thread *thread, u64 trace_nr)
302{
303 if (!thread || !thread->ts)
304 return;
305
306 if (trace_nr != thread->ts->trace_nr) {
307 if (thread->ts->trace_nr)
308 __thread_stack__flush(thread, thread->ts);
309 thread->ts->trace_nr = trace_nr;
310 }
311}
312
313void thread_stack__free(struct thread *thread)
314{
315 if (thread->ts) {
316 __thread_stack__flush(thread, thread->ts);
317 zfree(&thread->ts->stack);
318 zfree(&thread->ts);
319 }
320}
321
322void thread_stack__sample(struct thread *thread, struct ip_callchain *chain,
323 size_t sz, u64 ip)
324{
325 size_t i;
326
327 if (!thread || !thread->ts)
328 chain->nr = 1;
329 else
330 chain->nr = min(sz, thread->ts->cnt + 1);
331
332 chain->ips[0] = ip;
333
334 for (i = 1; i < chain->nr; i++)
335 chain->ips[i] = thread->ts->stack[thread->ts->cnt - i].ret_addr;
336}
337
338static void call_path__init(struct call_path *cp, struct call_path *parent,
339 struct symbol *sym, u64 ip, bool in_kernel)
340{
341 cp->parent = parent;
342 cp->sym = sym;
343 cp->ip = sym ? 0 : ip;
344 cp->db_id = 0;
345 cp->in_kernel = in_kernel;
346 RB_CLEAR_NODE(&cp->rb_node);
347 cp->children = RB_ROOT;
348}
349
350static struct call_path_root *call_path_root__new(void)
351{
352 struct call_path_root *cpr;
353
354 cpr = zalloc(sizeof(struct call_path_root));
355 if (!cpr)
356 return NULL;
357 call_path__init(&cpr->call_path, NULL, NULL, 0, false);
358 INIT_LIST_HEAD(&cpr->blocks);
359 return cpr;
360}
361
362static void call_path_root__free(struct call_path_root *cpr)
363{
364 struct call_path_block *pos, *n;
365
366 list_for_each_entry_safe(pos, n, &cpr->blocks, node) {
367 list_del(&pos->node);
368 free(pos);
369 }
370 free(cpr);
371}
372
373static struct call_path *call_path__new(struct call_path_root *cpr,
374 struct call_path *parent,
375 struct symbol *sym, u64 ip,
376 bool in_kernel)
377{
378 struct call_path_block *cpb;
379 struct call_path *cp;
380 size_t n;
381
382 if (cpr->next < cpr->sz) {
383 cpb = list_last_entry(&cpr->blocks, struct call_path_block,
384 node);
385 } else {
386 cpb = zalloc(sizeof(struct call_path_block));
387 if (!cpb)
388 return NULL;
389 list_add_tail(&cpb->node, &cpr->blocks);
390 cpr->sz += CALL_PATH_BLOCK_SIZE;
391 }
392
393 n = cpr->next++ & CALL_PATH_BLOCK_MASK;
394 cp = &cpb->cp[n];
395
396 call_path__init(cp, parent, sym, ip, in_kernel);
397
398 return cp;
399}
400
401static struct call_path *call_path__findnew(struct call_path_root *cpr,
402 struct call_path *parent,
403 struct symbol *sym, u64 ip, u64 ks)
404{
405 struct rb_node **p;
406 struct rb_node *node_parent = NULL;
407 struct call_path *cp;
408 bool in_kernel = ip >= ks;
409
410 if (sym)
411 ip = 0;
412
413 if (!parent)
414 return call_path__new(cpr, parent, sym, ip, in_kernel);
415
416 p = &parent->children.rb_node;
417 while (*p != NULL) {
418 node_parent = *p;
419 cp = rb_entry(node_parent, struct call_path, rb_node);
420
421 if (cp->sym == sym && cp->ip == ip)
422 return cp;
423
424 if (sym < cp->sym || (sym == cp->sym && ip < cp->ip))
425 p = &(*p)->rb_left;
426 else
427 p = &(*p)->rb_right;
428 }
429
430 cp = call_path__new(cpr, parent, sym, ip, in_kernel);
431 if (!cp)
432 return NULL;
433
434 rb_link_node(&cp->rb_node, node_parent, p);
435 rb_insert_color(&cp->rb_node, &parent->children);
436
437 return cp;
438}
439
440struct call_return_processor *
441call_return_processor__new(int (*process)(struct call_return *cr, void *data),
442 void *data)
443{
444 struct call_return_processor *crp;
445
446 crp = zalloc(sizeof(struct call_return_processor));
447 if (!crp)
448 return NULL;
449 crp->cpr = call_path_root__new();
450 if (!crp->cpr)
451 goto out_free;
452 crp->process = process;
453 crp->data = data;
454 return crp;
455
456out_free:
457 free(crp);
458 return NULL;
459}
460
461void call_return_processor__free(struct call_return_processor *crp)
462{
463 if (crp) {
464 call_path_root__free(crp->cpr);
465 free(crp);
466 }
467}
468
469static int thread_stack__push_cp(struct thread_stack *ts, u64 ret_addr,
470 u64 timestamp, u64 ref, struct call_path *cp,
471 bool no_call)
472{
473 struct thread_stack_entry *tse;
474 int err;
475
476 if (ts->cnt == ts->sz) {
477 err = thread_stack__grow(ts);
478 if (err)
479 return err;
480 }
481
482 tse = &ts->stack[ts->cnt++];
483 tse->ret_addr = ret_addr;
484 tse->timestamp = timestamp;
485 tse->ref = ref;
486 tse->branch_count = ts->branch_count;
487 tse->cp = cp;
488 tse->no_call = no_call;
489
490 return 0;
491}
492
493static int thread_stack__pop_cp(struct thread *thread, struct thread_stack *ts,
494 u64 ret_addr, u64 timestamp, u64 ref,
495 struct symbol *sym)
496{
497 int err;
498
499 if (!ts->cnt)
500 return 1;
501
502 if (ts->cnt == 1) {
503 struct thread_stack_entry *tse = &ts->stack[0];
504
505 if (tse->cp->sym == sym)
506 return thread_stack__call_return(thread, ts, --ts->cnt,
507 timestamp, ref, false);
508 }
509
510 if (ts->stack[ts->cnt - 1].ret_addr == ret_addr) {
511 return thread_stack__call_return(thread, ts, --ts->cnt,
512 timestamp, ref, false);
513 } else {
514 size_t i = ts->cnt - 1;
515
516 while (i--) {
517 if (ts->stack[i].ret_addr != ret_addr)
518 continue;
519 i += 1;
520 while (ts->cnt > i) {
521 err = thread_stack__call_return(thread, ts,
522 --ts->cnt,
523 timestamp, ref,
524 true);
525 if (err)
526 return err;
527 }
528 return thread_stack__call_return(thread, ts, --ts->cnt,
529 timestamp, ref, false);
530 }
531 }
532
533 return 1;
534}
535
536static int thread_stack__bottom(struct thread *thread, struct thread_stack *ts,
537 struct perf_sample *sample,
538 struct addr_location *from_al,
539 struct addr_location *to_al, u64 ref)
540{
541 struct call_path_root *cpr = ts->crp->cpr;
542 struct call_path *cp;
543 struct symbol *sym;
544 u64 ip;
545
546 if (sample->ip) {
547 ip = sample->ip;
548 sym = from_al->sym;
549 } else if (sample->addr) {
550 ip = sample->addr;
551 sym = to_al->sym;
552 } else {
553 return 0;
554 }
555
556 cp = call_path__findnew(cpr, &cpr->call_path, sym, ip,
557 ts->kernel_start);
558 if (!cp)
559 return -ENOMEM;
560
561 return thread_stack__push_cp(thread->ts, ip, sample->time, ref, cp,
562 true);
563}
564
565static int thread_stack__no_call_return(struct thread *thread,
566 struct thread_stack *ts,
567 struct perf_sample *sample,
568 struct addr_location *from_al,
569 struct addr_location *to_al, u64 ref)
570{
571 struct call_path_root *cpr = ts->crp->cpr;
572 struct call_path *cp, *parent;
573 u64 ks = ts->kernel_start;
574 int err;
575
576 if (sample->ip >= ks && sample->addr < ks) {
577 /* Return to userspace, so pop all kernel addresses */
578 while (thread_stack__in_kernel(ts)) {
579 err = thread_stack__call_return(thread, ts, --ts->cnt,
580 sample->time, ref,
581 true);
582 if (err)
583 return err;
584 }
585
586 /* If the stack is empty, push the userspace address */
587 if (!ts->cnt) {
588 cp = call_path__findnew(cpr, &cpr->call_path,
589 to_al->sym, sample->addr,
590 ts->kernel_start);
591 if (!cp)
592 return -ENOMEM;
593 return thread_stack__push_cp(ts, 0, sample->time, ref,
594 cp, true);
595 }
596 } else if (thread_stack__in_kernel(ts) && sample->ip < ks) {
597 /* Return to userspace, so pop all kernel addresses */
598 while (thread_stack__in_kernel(ts)) {
599 err = thread_stack__call_return(thread, ts, --ts->cnt,
600 sample->time, ref,
601 true);
602 if (err)
603 return err;
604 }
605 }
606
607 if (ts->cnt)
608 parent = ts->stack[ts->cnt - 1].cp;
609 else
610 parent = &cpr->call_path;
611
612 /* This 'return' had no 'call', so push and pop top of stack */
613 cp = call_path__findnew(cpr, parent, from_al->sym, sample->ip,
614 ts->kernel_start);
615 if (!cp)
616 return -ENOMEM;
617
618 err = thread_stack__push_cp(ts, sample->addr, sample->time, ref, cp,
619 true);
620 if (err)
621 return err;
622
623 return thread_stack__pop_cp(thread, ts, sample->addr, sample->time, ref,
624 to_al->sym);
625}
626
627static int thread_stack__trace_begin(struct thread *thread,
628 struct thread_stack *ts, u64 timestamp,
629 u64 ref)
630{
631 struct thread_stack_entry *tse;
632 int err;
633
634 if (!ts->cnt)
635 return 0;
636
637 /* Pop trace end */
638 tse = &ts->stack[ts->cnt - 1];
639 if (tse->cp->sym == NULL && tse->cp->ip == 0) {
640 err = thread_stack__call_return(thread, ts, --ts->cnt,
641 timestamp, ref, false);
642 if (err)
643 return err;
644 }
645
646 return 0;
647}
648
649static int thread_stack__trace_end(struct thread_stack *ts,
650 struct perf_sample *sample, u64 ref)
651{
652 struct call_path_root *cpr = ts->crp->cpr;
653 struct call_path *cp;
654 u64 ret_addr;
655
656 /* No point having 'trace end' on the bottom of the stack */
657 if (!ts->cnt || (ts->cnt == 1 && ts->stack[0].ref == ref))
658 return 0;
659
660 cp = call_path__findnew(cpr, ts->stack[ts->cnt - 1].cp, NULL, 0,
661 ts->kernel_start);
662 if (!cp)
663 return -ENOMEM;
664
665 ret_addr = sample->ip + sample->insn_len;
666
667 return thread_stack__push_cp(ts, ret_addr, sample->time, ref, cp,
668 false);
669}
670
671int thread_stack__process(struct thread *thread, struct comm *comm,
672 struct perf_sample *sample,
673 struct addr_location *from_al,
674 struct addr_location *to_al, u64 ref,
675 struct call_return_processor *crp)
676{
677 struct thread_stack *ts = thread->ts;
678 int err = 0;
679
680 if (ts) {
681 if (!ts->crp) {
682 /* Supersede thread_stack__event() */
683 thread_stack__free(thread);
684 thread->ts = thread_stack__new(thread, crp);
685 if (!thread->ts)
686 return -ENOMEM;
687 ts = thread->ts;
688 ts->comm = comm;
689 }
690 } else {
691 thread->ts = thread_stack__new(thread, crp);
692 if (!thread->ts)
693 return -ENOMEM;
694 ts = thread->ts;
695 ts->comm = comm;
696 }
697
698 /* Flush stack on exec */
699 if (ts->comm != comm && thread->pid_ == thread->tid) {
700 err = __thread_stack__flush(thread, ts);
701 if (err)
702 return err;
703 ts->comm = comm;
704 }
705
706 /* If the stack is empty, put the current symbol on the stack */
707 if (!ts->cnt) {
708 err = thread_stack__bottom(thread, ts, sample, from_al, to_al,
709 ref);
710 if (err)
711 return err;
712 }
713
714 ts->branch_count += 1;
715 ts->last_time = sample->time;
716
717 if (sample->flags & PERF_IP_FLAG_CALL) {
718 struct call_path_root *cpr = ts->crp->cpr;
719 struct call_path *cp;
720 u64 ret_addr;
721
722 if (!sample->ip || !sample->addr)
723 return 0;
724
725 ret_addr = sample->ip + sample->insn_len;
726 if (ret_addr == sample->addr)
727 return 0; /* Zero-length calls are excluded */
728
729 cp = call_path__findnew(cpr, ts->stack[ts->cnt - 1].cp,
730 to_al->sym, sample->addr,
731 ts->kernel_start);
732 if (!cp)
733 return -ENOMEM;
734 err = thread_stack__push_cp(ts, ret_addr, sample->time, ref,
735 cp, false);
736 } else if (sample->flags & PERF_IP_FLAG_RETURN) {
737 if (!sample->ip || !sample->addr)
738 return 0;
739
740 err = thread_stack__pop_cp(thread, ts, sample->addr,
741 sample->time, ref, from_al->sym);
742 if (err) {
743 if (err < 0)
744 return err;
745 err = thread_stack__no_call_return(thread, ts, sample,
746 from_al, to_al, ref);
747 }
748 } else if (sample->flags & PERF_IP_FLAG_TRACE_BEGIN) {
749 err = thread_stack__trace_begin(thread, ts, sample->time, ref);
750 } else if (sample->flags & PERF_IP_FLAG_TRACE_END) {
751 err = thread_stack__trace_end(ts, sample, ref);
752 }
753
754 return err;
755}
1/*
2 * thread-stack.c: Synthesize a thread's stack using call / return events
3 * Copyright (c) 2014, Intel Corporation.
4 *
5 * This program is free software; you can redistribute it and/or modify it
6 * under the terms and conditions of the GNU General Public License,
7 * version 2, as published by the Free Software Foundation.
8 *
9 * This program is distributed in the hope it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
12 * more details.
13 *
14 */
15
16#include <linux/rbtree.h>
17#include <linux/list.h>
18#include "thread.h"
19#include "event.h"
20#include "machine.h"
21#include "util.h"
22#include "debug.h"
23#include "symbol.h"
24#include "comm.h"
25#include "call-path.h"
26#include "thread-stack.h"
27
28#define STACK_GROWTH 2048
29
30/**
31 * struct thread_stack_entry - thread stack entry.
32 * @ret_addr: return address
33 * @timestamp: timestamp (if known)
34 * @ref: external reference (e.g. db_id of sample)
35 * @branch_count: the branch count when the entry was created
36 * @cp: call path
37 * @no_call: a 'call' was not seen
38 */
39struct thread_stack_entry {
40 u64 ret_addr;
41 u64 timestamp;
42 u64 ref;
43 u64 branch_count;
44 struct call_path *cp;
45 bool no_call;
46};
47
48/**
49 * struct thread_stack - thread stack constructed from 'call' and 'return'
50 * branch samples.
51 * @stack: array that holds the stack
52 * @cnt: number of entries in the stack
53 * @sz: current maximum stack size
54 * @trace_nr: current trace number
55 * @branch_count: running branch count
56 * @kernel_start: kernel start address
57 * @last_time: last timestamp
58 * @crp: call/return processor
59 * @comm: current comm
60 */
61struct thread_stack {
62 struct thread_stack_entry *stack;
63 size_t cnt;
64 size_t sz;
65 u64 trace_nr;
66 u64 branch_count;
67 u64 kernel_start;
68 u64 last_time;
69 struct call_return_processor *crp;
70 struct comm *comm;
71};
72
73static int thread_stack__grow(struct thread_stack *ts)
74{
75 struct thread_stack_entry *new_stack;
76 size_t sz, new_sz;
77
78 new_sz = ts->sz + STACK_GROWTH;
79 sz = new_sz * sizeof(struct thread_stack_entry);
80
81 new_stack = realloc(ts->stack, sz);
82 if (!new_stack)
83 return -ENOMEM;
84
85 ts->stack = new_stack;
86 ts->sz = new_sz;
87
88 return 0;
89}
90
91static struct thread_stack *thread_stack__new(struct thread *thread,
92 struct call_return_processor *crp)
93{
94 struct thread_stack *ts;
95
96 ts = zalloc(sizeof(struct thread_stack));
97 if (!ts)
98 return NULL;
99
100 if (thread_stack__grow(ts)) {
101 free(ts);
102 return NULL;
103 }
104
105 if (thread->mg && thread->mg->machine)
106 ts->kernel_start = machine__kernel_start(thread->mg->machine);
107 else
108 ts->kernel_start = 1ULL << 63;
109 ts->crp = crp;
110
111 return ts;
112}
113
114static int thread_stack__push(struct thread_stack *ts, u64 ret_addr)
115{
116 int err = 0;
117
118 if (ts->cnt == ts->sz) {
119 err = thread_stack__grow(ts);
120 if (err) {
121 pr_warning("Out of memory: discarding thread stack\n");
122 ts->cnt = 0;
123 }
124 }
125
126 ts->stack[ts->cnt++].ret_addr = ret_addr;
127
128 return err;
129}
130
131static void thread_stack__pop(struct thread_stack *ts, u64 ret_addr)
132{
133 size_t i;
134
135 /*
136 * In some cases there may be functions which are not seen to return.
137 * For example when setjmp / longjmp has been used. Or the perf context
138 * switch in the kernel which doesn't stop and start tracing in exactly
139 * the same code path. When that happens the return address will be
140 * further down the stack. If the return address is not found at all,
141 * we assume the opposite (i.e. this is a return for a call that wasn't
142 * seen for some reason) and leave the stack alone.
143 */
144 for (i = ts->cnt; i; ) {
145 if (ts->stack[--i].ret_addr == ret_addr) {
146 ts->cnt = i;
147 return;
148 }
149 }
150}
151
152static bool thread_stack__in_kernel(struct thread_stack *ts)
153{
154 if (!ts->cnt)
155 return false;
156
157 return ts->stack[ts->cnt - 1].cp->in_kernel;
158}
159
160static int thread_stack__call_return(struct thread *thread,
161 struct thread_stack *ts, size_t idx,
162 u64 timestamp, u64 ref, bool no_return)
163{
164 struct call_return_processor *crp = ts->crp;
165 struct thread_stack_entry *tse;
166 struct call_return cr = {
167 .thread = thread,
168 .comm = ts->comm,
169 .db_id = 0,
170 };
171
172 tse = &ts->stack[idx];
173 cr.cp = tse->cp;
174 cr.call_time = tse->timestamp;
175 cr.return_time = timestamp;
176 cr.branch_count = ts->branch_count - tse->branch_count;
177 cr.call_ref = tse->ref;
178 cr.return_ref = ref;
179 if (tse->no_call)
180 cr.flags |= CALL_RETURN_NO_CALL;
181 if (no_return)
182 cr.flags |= CALL_RETURN_NO_RETURN;
183
184 return crp->process(&cr, crp->data);
185}
186
187static int __thread_stack__flush(struct thread *thread, struct thread_stack *ts)
188{
189 struct call_return_processor *crp = ts->crp;
190 int err;
191
192 if (!crp) {
193 ts->cnt = 0;
194 return 0;
195 }
196
197 while (ts->cnt) {
198 err = thread_stack__call_return(thread, ts, --ts->cnt,
199 ts->last_time, 0, true);
200 if (err) {
201 pr_err("Error flushing thread stack!\n");
202 ts->cnt = 0;
203 return err;
204 }
205 }
206
207 return 0;
208}
209
210int thread_stack__flush(struct thread *thread)
211{
212 if (thread->ts)
213 return __thread_stack__flush(thread, thread->ts);
214
215 return 0;
216}
217
218int thread_stack__event(struct thread *thread, u32 flags, u64 from_ip,
219 u64 to_ip, u16 insn_len, u64 trace_nr)
220{
221 if (!thread)
222 return -EINVAL;
223
224 if (!thread->ts) {
225 thread->ts = thread_stack__new(thread, NULL);
226 if (!thread->ts) {
227 pr_warning("Out of memory: no thread stack\n");
228 return -ENOMEM;
229 }
230 thread->ts->trace_nr = trace_nr;
231 }
232
233 /*
234 * When the trace is discontinuous, the trace_nr changes. In that case
235 * the stack might be completely invalid. Better to report nothing than
236 * to report something misleading, so flush the stack.
237 */
238 if (trace_nr != thread->ts->trace_nr) {
239 if (thread->ts->trace_nr)
240 __thread_stack__flush(thread, thread->ts);
241 thread->ts->trace_nr = trace_nr;
242 }
243
244 /* Stop here if thread_stack__process() is in use */
245 if (thread->ts->crp)
246 return 0;
247
248 if (flags & PERF_IP_FLAG_CALL) {
249 u64 ret_addr;
250
251 if (!to_ip)
252 return 0;
253 ret_addr = from_ip + insn_len;
254 if (ret_addr == to_ip)
255 return 0; /* Zero-length calls are excluded */
256 return thread_stack__push(thread->ts, ret_addr);
257 } else if (flags & PERF_IP_FLAG_RETURN) {
258 if (!from_ip)
259 return 0;
260 thread_stack__pop(thread->ts, to_ip);
261 }
262
263 return 0;
264}
265
266void thread_stack__set_trace_nr(struct thread *thread, u64 trace_nr)
267{
268 if (!thread || !thread->ts)
269 return;
270
271 if (trace_nr != thread->ts->trace_nr) {
272 if (thread->ts->trace_nr)
273 __thread_stack__flush(thread, thread->ts);
274 thread->ts->trace_nr = trace_nr;
275 }
276}
277
278void thread_stack__free(struct thread *thread)
279{
280 if (thread->ts) {
281 __thread_stack__flush(thread, thread->ts);
282 zfree(&thread->ts->stack);
283 zfree(&thread->ts);
284 }
285}
286
287void thread_stack__sample(struct thread *thread, struct ip_callchain *chain,
288 size_t sz, u64 ip)
289{
290 size_t i;
291
292 if (!thread || !thread->ts)
293 chain->nr = 1;
294 else
295 chain->nr = min(sz, thread->ts->cnt + 1);
296
297 chain->ips[0] = ip;
298
299 for (i = 1; i < chain->nr; i++)
300 chain->ips[i] = thread->ts->stack[thread->ts->cnt - i].ret_addr;
301}
302
303struct call_return_processor *
304call_return_processor__new(int (*process)(struct call_return *cr, void *data),
305 void *data)
306{
307 struct call_return_processor *crp;
308
309 crp = zalloc(sizeof(struct call_return_processor));
310 if (!crp)
311 return NULL;
312 crp->cpr = call_path_root__new();
313 if (!crp->cpr)
314 goto out_free;
315 crp->process = process;
316 crp->data = data;
317 return crp;
318
319out_free:
320 free(crp);
321 return NULL;
322}
323
324void call_return_processor__free(struct call_return_processor *crp)
325{
326 if (crp) {
327 call_path_root__free(crp->cpr);
328 free(crp);
329 }
330}
331
332static int thread_stack__push_cp(struct thread_stack *ts, u64 ret_addr,
333 u64 timestamp, u64 ref, struct call_path *cp,
334 bool no_call)
335{
336 struct thread_stack_entry *tse;
337 int err;
338
339 if (ts->cnt == ts->sz) {
340 err = thread_stack__grow(ts);
341 if (err)
342 return err;
343 }
344
345 tse = &ts->stack[ts->cnt++];
346 tse->ret_addr = ret_addr;
347 tse->timestamp = timestamp;
348 tse->ref = ref;
349 tse->branch_count = ts->branch_count;
350 tse->cp = cp;
351 tse->no_call = no_call;
352
353 return 0;
354}
355
356static int thread_stack__pop_cp(struct thread *thread, struct thread_stack *ts,
357 u64 ret_addr, u64 timestamp, u64 ref,
358 struct symbol *sym)
359{
360 int err;
361
362 if (!ts->cnt)
363 return 1;
364
365 if (ts->cnt == 1) {
366 struct thread_stack_entry *tse = &ts->stack[0];
367
368 if (tse->cp->sym == sym)
369 return thread_stack__call_return(thread, ts, --ts->cnt,
370 timestamp, ref, false);
371 }
372
373 if (ts->stack[ts->cnt - 1].ret_addr == ret_addr) {
374 return thread_stack__call_return(thread, ts, --ts->cnt,
375 timestamp, ref, false);
376 } else {
377 size_t i = ts->cnt - 1;
378
379 while (i--) {
380 if (ts->stack[i].ret_addr != ret_addr)
381 continue;
382 i += 1;
383 while (ts->cnt > i) {
384 err = thread_stack__call_return(thread, ts,
385 --ts->cnt,
386 timestamp, ref,
387 true);
388 if (err)
389 return err;
390 }
391 return thread_stack__call_return(thread, ts, --ts->cnt,
392 timestamp, ref, false);
393 }
394 }
395
396 return 1;
397}
398
399static int thread_stack__bottom(struct thread *thread, struct thread_stack *ts,
400 struct perf_sample *sample,
401 struct addr_location *from_al,
402 struct addr_location *to_al, u64 ref)
403{
404 struct call_path_root *cpr = ts->crp->cpr;
405 struct call_path *cp;
406 struct symbol *sym;
407 u64 ip;
408
409 if (sample->ip) {
410 ip = sample->ip;
411 sym = from_al->sym;
412 } else if (sample->addr) {
413 ip = sample->addr;
414 sym = to_al->sym;
415 } else {
416 return 0;
417 }
418
419 cp = call_path__findnew(cpr, &cpr->call_path, sym, ip,
420 ts->kernel_start);
421 if (!cp)
422 return -ENOMEM;
423
424 return thread_stack__push_cp(thread->ts, ip, sample->time, ref, cp,
425 true);
426}
427
428static int thread_stack__no_call_return(struct thread *thread,
429 struct thread_stack *ts,
430 struct perf_sample *sample,
431 struct addr_location *from_al,
432 struct addr_location *to_al, u64 ref)
433{
434 struct call_path_root *cpr = ts->crp->cpr;
435 struct call_path *cp, *parent;
436 u64 ks = ts->kernel_start;
437 int err;
438
439 if (sample->ip >= ks && sample->addr < ks) {
440 /* Return to userspace, so pop all kernel addresses */
441 while (thread_stack__in_kernel(ts)) {
442 err = thread_stack__call_return(thread, ts, --ts->cnt,
443 sample->time, ref,
444 true);
445 if (err)
446 return err;
447 }
448
449 /* If the stack is empty, push the userspace address */
450 if (!ts->cnt) {
451 cp = call_path__findnew(cpr, &cpr->call_path,
452 to_al->sym, sample->addr,
453 ts->kernel_start);
454 if (!cp)
455 return -ENOMEM;
456 return thread_stack__push_cp(ts, 0, sample->time, ref,
457 cp, true);
458 }
459 } else if (thread_stack__in_kernel(ts) && sample->ip < ks) {
460 /* Return to userspace, so pop all kernel addresses */
461 while (thread_stack__in_kernel(ts)) {
462 err = thread_stack__call_return(thread, ts, --ts->cnt,
463 sample->time, ref,
464 true);
465 if (err)
466 return err;
467 }
468 }
469
470 if (ts->cnt)
471 parent = ts->stack[ts->cnt - 1].cp;
472 else
473 parent = &cpr->call_path;
474
475 /* This 'return' had no 'call', so push and pop top of stack */
476 cp = call_path__findnew(cpr, parent, from_al->sym, sample->ip,
477 ts->kernel_start);
478 if (!cp)
479 return -ENOMEM;
480
481 err = thread_stack__push_cp(ts, sample->addr, sample->time, ref, cp,
482 true);
483 if (err)
484 return err;
485
486 return thread_stack__pop_cp(thread, ts, sample->addr, sample->time, ref,
487 to_al->sym);
488}
489
490static int thread_stack__trace_begin(struct thread *thread,
491 struct thread_stack *ts, u64 timestamp,
492 u64 ref)
493{
494 struct thread_stack_entry *tse;
495 int err;
496
497 if (!ts->cnt)
498 return 0;
499
500 /* Pop trace end */
501 tse = &ts->stack[ts->cnt - 1];
502 if (tse->cp->sym == NULL && tse->cp->ip == 0) {
503 err = thread_stack__call_return(thread, ts, --ts->cnt,
504 timestamp, ref, false);
505 if (err)
506 return err;
507 }
508
509 return 0;
510}
511
512static int thread_stack__trace_end(struct thread_stack *ts,
513 struct perf_sample *sample, u64 ref)
514{
515 struct call_path_root *cpr = ts->crp->cpr;
516 struct call_path *cp;
517 u64 ret_addr;
518
519 /* No point having 'trace end' on the bottom of the stack */
520 if (!ts->cnt || (ts->cnt == 1 && ts->stack[0].ref == ref))
521 return 0;
522
523 cp = call_path__findnew(cpr, ts->stack[ts->cnt - 1].cp, NULL, 0,
524 ts->kernel_start);
525 if (!cp)
526 return -ENOMEM;
527
528 ret_addr = sample->ip + sample->insn_len;
529
530 return thread_stack__push_cp(ts, ret_addr, sample->time, ref, cp,
531 false);
532}
533
534int thread_stack__process(struct thread *thread, struct comm *comm,
535 struct perf_sample *sample,
536 struct addr_location *from_al,
537 struct addr_location *to_al, u64 ref,
538 struct call_return_processor *crp)
539{
540 struct thread_stack *ts = thread->ts;
541 int err = 0;
542
543 if (ts) {
544 if (!ts->crp) {
545 /* Supersede thread_stack__event() */
546 thread_stack__free(thread);
547 thread->ts = thread_stack__new(thread, crp);
548 if (!thread->ts)
549 return -ENOMEM;
550 ts = thread->ts;
551 ts->comm = comm;
552 }
553 } else {
554 thread->ts = thread_stack__new(thread, crp);
555 if (!thread->ts)
556 return -ENOMEM;
557 ts = thread->ts;
558 ts->comm = comm;
559 }
560
561 /* Flush stack on exec */
562 if (ts->comm != comm && thread->pid_ == thread->tid) {
563 err = __thread_stack__flush(thread, ts);
564 if (err)
565 return err;
566 ts->comm = comm;
567 }
568
569 /* If the stack is empty, put the current symbol on the stack */
570 if (!ts->cnt) {
571 err = thread_stack__bottom(thread, ts, sample, from_al, to_al,
572 ref);
573 if (err)
574 return err;
575 }
576
577 ts->branch_count += 1;
578 ts->last_time = sample->time;
579
580 if (sample->flags & PERF_IP_FLAG_CALL) {
581 struct call_path_root *cpr = ts->crp->cpr;
582 struct call_path *cp;
583 u64 ret_addr;
584
585 if (!sample->ip || !sample->addr)
586 return 0;
587
588 ret_addr = sample->ip + sample->insn_len;
589 if (ret_addr == sample->addr)
590 return 0; /* Zero-length calls are excluded */
591
592 cp = call_path__findnew(cpr, ts->stack[ts->cnt - 1].cp,
593 to_al->sym, sample->addr,
594 ts->kernel_start);
595 if (!cp)
596 return -ENOMEM;
597 err = thread_stack__push_cp(ts, ret_addr, sample->time, ref,
598 cp, false);
599 } else if (sample->flags & PERF_IP_FLAG_RETURN) {
600 if (!sample->ip || !sample->addr)
601 return 0;
602
603 err = thread_stack__pop_cp(thread, ts, sample->addr,
604 sample->time, ref, from_al->sym);
605 if (err) {
606 if (err < 0)
607 return err;
608 err = thread_stack__no_call_return(thread, ts, sample,
609 from_al, to_al, ref);
610 }
611 } else if (sample->flags & PERF_IP_FLAG_TRACE_BEGIN) {
612 err = thread_stack__trace_begin(thread, ts, sample->time, ref);
613 } else if (sample->flags & PERF_IP_FLAG_TRACE_END) {
614 err = thread_stack__trace_end(ts, sample, ref);
615 }
616
617 return err;
618}
619
620size_t thread_stack__depth(struct thread *thread)
621{
622 if (!thread->ts)
623 return 0;
624 return thread->ts->cnt;
625}