xref: /linux/tools/perf/util/evlist.c (revision 0d456bad36d42d16022be045c8a53ddbb59ee478)
1 /*
2  * Copyright (C) 2011, Red Hat Inc, Arnaldo Carvalho de Melo <acme@redhat.com>
3  *
4  * Parts came from builtin-{top,stat,record}.c, see those files for further
5  * copyright notes.
6  *
7  * Released under the GPL v2. (and only v2, not any later version)
8  */
9 #include "util.h"
10 #include "debugfs.h"
11 #include <poll.h>
12 #include "cpumap.h"
13 #include "thread_map.h"
14 #include "target.h"
15 #include "evlist.h"
16 #include "evsel.h"
17 #include <unistd.h>
18 
19 #include "parse-events.h"
20 
21 #include <sys/mman.h>
22 
23 #include <linux/bitops.h>
24 #include <linux/hash.h>
25 
26 #define FD(e, x, y) (*(int *)xyarray__entry(e->fd, x, y))
27 #define SID(e, x, y) xyarray__entry(e->sample_id, x, y)
28 
29 void perf_evlist__init(struct perf_evlist *evlist, struct cpu_map *cpus,
30 		       struct thread_map *threads)
31 {
32 	int i;
33 
34 	for (i = 0; i < PERF_EVLIST__HLIST_SIZE; ++i)
35 		INIT_HLIST_HEAD(&evlist->heads[i]);
36 	INIT_LIST_HEAD(&evlist->entries);
37 	perf_evlist__set_maps(evlist, cpus, threads);
38 	evlist->workload.pid = -1;
39 }
40 
41 struct perf_evlist *perf_evlist__new(struct cpu_map *cpus,
42 				     struct thread_map *threads)
43 {
44 	struct perf_evlist *evlist = zalloc(sizeof(*evlist));
45 
46 	if (evlist != NULL)
47 		perf_evlist__init(evlist, cpus, threads);
48 
49 	return evlist;
50 }
51 
52 void perf_evlist__config_attrs(struct perf_evlist *evlist,
53 			       struct perf_record_opts *opts)
54 {
55 	struct perf_evsel *evsel;
56 
57 	if (evlist->cpus->map[0] < 0)
58 		opts->no_inherit = true;
59 
60 	list_for_each_entry(evsel, &evlist->entries, node) {
61 		perf_evsel__config(evsel, opts);
62 
63 		if (evlist->nr_entries > 1)
64 			evsel->attr.sample_type |= PERF_SAMPLE_ID;
65 	}
66 }
67 
68 static void perf_evlist__purge(struct perf_evlist *evlist)
69 {
70 	struct perf_evsel *pos, *n;
71 
72 	list_for_each_entry_safe(pos, n, &evlist->entries, node) {
73 		list_del_init(&pos->node);
74 		perf_evsel__delete(pos);
75 	}
76 
77 	evlist->nr_entries = 0;
78 }
79 
80 void perf_evlist__exit(struct perf_evlist *evlist)
81 {
82 	free(evlist->mmap);
83 	free(evlist->pollfd);
84 	evlist->mmap = NULL;
85 	evlist->pollfd = NULL;
86 }
87 
88 void perf_evlist__delete(struct perf_evlist *evlist)
89 {
90 	perf_evlist__purge(evlist);
91 	perf_evlist__exit(evlist);
92 	free(evlist);
93 }
94 
95 void perf_evlist__add(struct perf_evlist *evlist, struct perf_evsel *entry)
96 {
97 	list_add_tail(&entry->node, &evlist->entries);
98 	++evlist->nr_entries;
99 }
100 
101 void perf_evlist__splice_list_tail(struct perf_evlist *evlist,
102 				   struct list_head *list,
103 				   int nr_entries)
104 {
105 	list_splice_tail(list, &evlist->entries);
106 	evlist->nr_entries += nr_entries;
107 }
108 
109 void __perf_evlist__set_leader(struct list_head *list)
110 {
111 	struct perf_evsel *evsel, *leader;
112 
113 	leader = list_entry(list->next, struct perf_evsel, node);
114 	leader->leader = NULL;
115 
116 	list_for_each_entry(evsel, list, node) {
117 		if (evsel != leader)
118 			evsel->leader = leader;
119 	}
120 }
121 
122 void perf_evlist__set_leader(struct perf_evlist *evlist)
123 {
124 	if (evlist->nr_entries)
125 		__perf_evlist__set_leader(&evlist->entries);
126 }
127 
128 int perf_evlist__add_default(struct perf_evlist *evlist)
129 {
130 	struct perf_event_attr attr = {
131 		.type = PERF_TYPE_HARDWARE,
132 		.config = PERF_COUNT_HW_CPU_CYCLES,
133 	};
134 	struct perf_evsel *evsel;
135 
136 	event_attr_init(&attr);
137 
138 	evsel = perf_evsel__new(&attr, 0);
139 	if (evsel == NULL)
140 		goto error;
141 
142 	/* use strdup() because free(evsel) assumes name is allocated */
143 	evsel->name = strdup("cycles");
144 	if (!evsel->name)
145 		goto error_free;
146 
147 	perf_evlist__add(evlist, evsel);
148 	return 0;
149 error_free:
150 	perf_evsel__delete(evsel);
151 error:
152 	return -ENOMEM;
153 }
154 
155 static int perf_evlist__add_attrs(struct perf_evlist *evlist,
156 				  struct perf_event_attr *attrs, size_t nr_attrs)
157 {
158 	struct perf_evsel *evsel, *n;
159 	LIST_HEAD(head);
160 	size_t i;
161 
162 	for (i = 0; i < nr_attrs; i++) {
163 		evsel = perf_evsel__new(attrs + i, evlist->nr_entries + i);
164 		if (evsel == NULL)
165 			goto out_delete_partial_list;
166 		list_add_tail(&evsel->node, &head);
167 	}
168 
169 	perf_evlist__splice_list_tail(evlist, &head, nr_attrs);
170 
171 	return 0;
172 
173 out_delete_partial_list:
174 	list_for_each_entry_safe(evsel, n, &head, node)
175 		perf_evsel__delete(evsel);
176 	return -1;
177 }
178 
179 int __perf_evlist__add_default_attrs(struct perf_evlist *evlist,
180 				     struct perf_event_attr *attrs, size_t nr_attrs)
181 {
182 	size_t i;
183 
184 	for (i = 0; i < nr_attrs; i++)
185 		event_attr_init(attrs + i);
186 
187 	return perf_evlist__add_attrs(evlist, attrs, nr_attrs);
188 }
189 
190 struct perf_evsel *
191 perf_evlist__find_tracepoint_by_id(struct perf_evlist *evlist, int id)
192 {
193 	struct perf_evsel *evsel;
194 
195 	list_for_each_entry(evsel, &evlist->entries, node) {
196 		if (evsel->attr.type   == PERF_TYPE_TRACEPOINT &&
197 		    (int)evsel->attr.config == id)
198 			return evsel;
199 	}
200 
201 	return NULL;
202 }
203 
204 int perf_evlist__add_newtp(struct perf_evlist *evlist,
205 			   const char *sys, const char *name, void *handler)
206 {
207 	struct perf_evsel *evsel;
208 
209 	evsel = perf_evsel__newtp(sys, name, evlist->nr_entries);
210 	if (evsel == NULL)
211 		return -1;
212 
213 	evsel->handler.func = handler;
214 	perf_evlist__add(evlist, evsel);
215 	return 0;
216 }
217 
218 void perf_evlist__disable(struct perf_evlist *evlist)
219 {
220 	int cpu, thread;
221 	struct perf_evsel *pos;
222 
223 	for (cpu = 0; cpu < evlist->cpus->nr; cpu++) {
224 		list_for_each_entry(pos, &evlist->entries, node) {
225 			if (perf_evsel__is_group_member(pos))
226 				continue;
227 			for (thread = 0; thread < evlist->threads->nr; thread++)
228 				ioctl(FD(pos, cpu, thread),
229 				      PERF_EVENT_IOC_DISABLE, 0);
230 		}
231 	}
232 }
233 
234 void perf_evlist__enable(struct perf_evlist *evlist)
235 {
236 	int cpu, thread;
237 	struct perf_evsel *pos;
238 
239 	for (cpu = 0; cpu < cpu_map__nr(evlist->cpus); cpu++) {
240 		list_for_each_entry(pos, &evlist->entries, node) {
241 			if (perf_evsel__is_group_member(pos))
242 				continue;
243 			for (thread = 0; thread < evlist->threads->nr; thread++)
244 				ioctl(FD(pos, cpu, thread),
245 				      PERF_EVENT_IOC_ENABLE, 0);
246 		}
247 	}
248 }
249 
250 static int perf_evlist__alloc_pollfd(struct perf_evlist *evlist)
251 {
252 	int nfds = cpu_map__nr(evlist->cpus) * evlist->threads->nr * evlist->nr_entries;
253 	evlist->pollfd = malloc(sizeof(struct pollfd) * nfds);
254 	return evlist->pollfd != NULL ? 0 : -ENOMEM;
255 }
256 
257 void perf_evlist__add_pollfd(struct perf_evlist *evlist, int fd)
258 {
259 	fcntl(fd, F_SETFL, O_NONBLOCK);
260 	evlist->pollfd[evlist->nr_fds].fd = fd;
261 	evlist->pollfd[evlist->nr_fds].events = POLLIN;
262 	evlist->nr_fds++;
263 }
264 
265 static void perf_evlist__id_hash(struct perf_evlist *evlist,
266 				 struct perf_evsel *evsel,
267 				 int cpu, int thread, u64 id)
268 {
269 	int hash;
270 	struct perf_sample_id *sid = SID(evsel, cpu, thread);
271 
272 	sid->id = id;
273 	sid->evsel = evsel;
274 	hash = hash_64(sid->id, PERF_EVLIST__HLIST_BITS);
275 	hlist_add_head(&sid->node, &evlist->heads[hash]);
276 }
277 
278 void perf_evlist__id_add(struct perf_evlist *evlist, struct perf_evsel *evsel,
279 			 int cpu, int thread, u64 id)
280 {
281 	perf_evlist__id_hash(evlist, evsel, cpu, thread, id);
282 	evsel->id[evsel->ids++] = id;
283 }
284 
285 static int perf_evlist__id_add_fd(struct perf_evlist *evlist,
286 				  struct perf_evsel *evsel,
287 				  int cpu, int thread, int fd)
288 {
289 	u64 read_data[4] = { 0, };
290 	int id_idx = 1; /* The first entry is the counter value */
291 
292 	if (!(evsel->attr.read_format & PERF_FORMAT_ID) ||
293 	    read(fd, &read_data, sizeof(read_data)) == -1)
294 		return -1;
295 
296 	if (evsel->attr.read_format & PERF_FORMAT_TOTAL_TIME_ENABLED)
297 		++id_idx;
298 	if (evsel->attr.read_format & PERF_FORMAT_TOTAL_TIME_RUNNING)
299 		++id_idx;
300 
301 	perf_evlist__id_add(evlist, evsel, cpu, thread, read_data[id_idx]);
302 	return 0;
303 }
304 
305 struct perf_evsel *perf_evlist__id2evsel(struct perf_evlist *evlist, u64 id)
306 {
307 	struct hlist_head *head;
308 	struct hlist_node *pos;
309 	struct perf_sample_id *sid;
310 	int hash;
311 
312 	if (evlist->nr_entries == 1)
313 		return perf_evlist__first(evlist);
314 
315 	hash = hash_64(id, PERF_EVLIST__HLIST_BITS);
316 	head = &evlist->heads[hash];
317 
318 	hlist_for_each_entry(sid, pos, head, node)
319 		if (sid->id == id)
320 			return sid->evsel;
321 
322 	if (!perf_evlist__sample_id_all(evlist))
323 		return perf_evlist__first(evlist);
324 
325 	return NULL;
326 }
327 
328 union perf_event *perf_evlist__mmap_read(struct perf_evlist *evlist, int idx)
329 {
330 	struct perf_mmap *md = &evlist->mmap[idx];
331 	unsigned int head = perf_mmap__read_head(md);
332 	unsigned int old = md->prev;
333 	unsigned char *data = md->base + page_size;
334 	union perf_event *event = NULL;
335 
336 	if (evlist->overwrite) {
337 		/*
338 		 * If we're further behind than half the buffer, there's a chance
339 		 * the writer will bite our tail and mess up the samples under us.
340 		 *
341 		 * If we somehow ended up ahead of the head, we got messed up.
342 		 *
343 		 * In either case, truncate and restart at head.
344 		 */
345 		int diff = head - old;
346 		if (diff > md->mask / 2 || diff < 0) {
347 			fprintf(stderr, "WARNING: failed to keep up with mmap data.\n");
348 
349 			/*
350 			 * head points to a known good entry, start there.
351 			 */
352 			old = head;
353 		}
354 	}
355 
356 	if (old != head) {
357 		size_t size;
358 
359 		event = (union perf_event *)&data[old & md->mask];
360 		size = event->header.size;
361 
362 		/*
363 		 * Event straddles the mmap boundary -- header should always
364 		 * be inside due to u64 alignment of output.
365 		 */
366 		if ((old & md->mask) + size != ((old + size) & md->mask)) {
367 			unsigned int offset = old;
368 			unsigned int len = min(sizeof(*event), size), cpy;
369 			void *dst = &evlist->event_copy;
370 
371 			do {
372 				cpy = min(md->mask + 1 - (offset & md->mask), len);
373 				memcpy(dst, &data[offset & md->mask], cpy);
374 				offset += cpy;
375 				dst += cpy;
376 				len -= cpy;
377 			} while (len);
378 
379 			event = &evlist->event_copy;
380 		}
381 
382 		old += size;
383 	}
384 
385 	md->prev = old;
386 
387 	if (!evlist->overwrite)
388 		perf_mmap__write_tail(md, old);
389 
390 	return event;
391 }
392 
393 void perf_evlist__munmap(struct perf_evlist *evlist)
394 {
395 	int i;
396 
397 	for (i = 0; i < evlist->nr_mmaps; i++) {
398 		if (evlist->mmap[i].base != NULL) {
399 			munmap(evlist->mmap[i].base, evlist->mmap_len);
400 			evlist->mmap[i].base = NULL;
401 		}
402 	}
403 
404 	free(evlist->mmap);
405 	evlist->mmap = NULL;
406 }
407 
408 static int perf_evlist__alloc_mmap(struct perf_evlist *evlist)
409 {
410 	evlist->nr_mmaps = cpu_map__nr(evlist->cpus);
411 	if (cpu_map__all(evlist->cpus))
412 		evlist->nr_mmaps = evlist->threads->nr;
413 	evlist->mmap = zalloc(evlist->nr_mmaps * sizeof(struct perf_mmap));
414 	return evlist->mmap != NULL ? 0 : -ENOMEM;
415 }
416 
417 static int __perf_evlist__mmap(struct perf_evlist *evlist,
418 			       int idx, int prot, int mask, int fd)
419 {
420 	evlist->mmap[idx].prev = 0;
421 	evlist->mmap[idx].mask = mask;
422 	evlist->mmap[idx].base = mmap(NULL, evlist->mmap_len, prot,
423 				      MAP_SHARED, fd, 0);
424 	if (evlist->mmap[idx].base == MAP_FAILED) {
425 		evlist->mmap[idx].base = NULL;
426 		return -1;
427 	}
428 
429 	perf_evlist__add_pollfd(evlist, fd);
430 	return 0;
431 }
432 
433 static int perf_evlist__mmap_per_cpu(struct perf_evlist *evlist, int prot, int mask)
434 {
435 	struct perf_evsel *evsel;
436 	int cpu, thread;
437 
438 	for (cpu = 0; cpu < evlist->cpus->nr; cpu++) {
439 		int output = -1;
440 
441 		for (thread = 0; thread < evlist->threads->nr; thread++) {
442 			list_for_each_entry(evsel, &evlist->entries, node) {
443 				int fd = FD(evsel, cpu, thread);
444 
445 				if (output == -1) {
446 					output = fd;
447 					if (__perf_evlist__mmap(evlist, cpu,
448 								prot, mask, output) < 0)
449 						goto out_unmap;
450 				} else {
451 					if (ioctl(fd, PERF_EVENT_IOC_SET_OUTPUT, output) != 0)
452 						goto out_unmap;
453 				}
454 
455 				if ((evsel->attr.read_format & PERF_FORMAT_ID) &&
456 				    perf_evlist__id_add_fd(evlist, evsel, cpu, thread, fd) < 0)
457 					goto out_unmap;
458 			}
459 		}
460 	}
461 
462 	return 0;
463 
464 out_unmap:
465 	for (cpu = 0; cpu < evlist->cpus->nr; cpu++) {
466 		if (evlist->mmap[cpu].base != NULL) {
467 			munmap(evlist->mmap[cpu].base, evlist->mmap_len);
468 			evlist->mmap[cpu].base = NULL;
469 		}
470 	}
471 	return -1;
472 }
473 
474 static int perf_evlist__mmap_per_thread(struct perf_evlist *evlist, int prot, int mask)
475 {
476 	struct perf_evsel *evsel;
477 	int thread;
478 
479 	for (thread = 0; thread < evlist->threads->nr; thread++) {
480 		int output = -1;
481 
482 		list_for_each_entry(evsel, &evlist->entries, node) {
483 			int fd = FD(evsel, 0, thread);
484 
485 			if (output == -1) {
486 				output = fd;
487 				if (__perf_evlist__mmap(evlist, thread,
488 							prot, mask, output) < 0)
489 					goto out_unmap;
490 			} else {
491 				if (ioctl(fd, PERF_EVENT_IOC_SET_OUTPUT, output) != 0)
492 					goto out_unmap;
493 			}
494 
495 			if ((evsel->attr.read_format & PERF_FORMAT_ID) &&
496 			    perf_evlist__id_add_fd(evlist, evsel, 0, thread, fd) < 0)
497 				goto out_unmap;
498 		}
499 	}
500 
501 	return 0;
502 
503 out_unmap:
504 	for (thread = 0; thread < evlist->threads->nr; thread++) {
505 		if (evlist->mmap[thread].base != NULL) {
506 			munmap(evlist->mmap[thread].base, evlist->mmap_len);
507 			evlist->mmap[thread].base = NULL;
508 		}
509 	}
510 	return -1;
511 }
512 
513 /** perf_evlist__mmap - Create per cpu maps to receive events
514  *
515  * @evlist - list of events
516  * @pages - map length in pages
517  * @overwrite - overwrite older events?
518  *
519  * If overwrite is false the user needs to signal event consuption using:
520  *
521  *	struct perf_mmap *m = &evlist->mmap[cpu];
522  *	unsigned int head = perf_mmap__read_head(m);
523  *
524  *	perf_mmap__write_tail(m, head)
525  *
526  * Using perf_evlist__read_on_cpu does this automatically.
527  */
528 int perf_evlist__mmap(struct perf_evlist *evlist, unsigned int pages,
529 		      bool overwrite)
530 {
531 	struct perf_evsel *evsel;
532 	const struct cpu_map *cpus = evlist->cpus;
533 	const struct thread_map *threads = evlist->threads;
534 	int prot = PROT_READ | (overwrite ? 0 : PROT_WRITE), mask;
535 
536         /* 512 kiB: default amount of unprivileged mlocked memory */
537         if (pages == UINT_MAX)
538                 pages = (512 * 1024) / page_size;
539 	else if (!is_power_of_2(pages))
540 		return -EINVAL;
541 
542 	mask = pages * page_size - 1;
543 
544 	if (evlist->mmap == NULL && perf_evlist__alloc_mmap(evlist) < 0)
545 		return -ENOMEM;
546 
547 	if (evlist->pollfd == NULL && perf_evlist__alloc_pollfd(evlist) < 0)
548 		return -ENOMEM;
549 
550 	evlist->overwrite = overwrite;
551 	evlist->mmap_len = (pages + 1) * page_size;
552 
553 	list_for_each_entry(evsel, &evlist->entries, node) {
554 		if ((evsel->attr.read_format & PERF_FORMAT_ID) &&
555 		    evsel->sample_id == NULL &&
556 		    perf_evsel__alloc_id(evsel, cpu_map__nr(cpus), threads->nr) < 0)
557 			return -ENOMEM;
558 	}
559 
560 	if (cpu_map__all(cpus))
561 		return perf_evlist__mmap_per_thread(evlist, prot, mask);
562 
563 	return perf_evlist__mmap_per_cpu(evlist, prot, mask);
564 }
565 
566 int perf_evlist__create_maps(struct perf_evlist *evlist,
567 			     struct perf_target *target)
568 {
569 	evlist->threads = thread_map__new_str(target->pid, target->tid,
570 					      target->uid);
571 
572 	if (evlist->threads == NULL)
573 		return -1;
574 
575 	if (perf_target__has_task(target))
576 		evlist->cpus = cpu_map__dummy_new();
577 	else if (!perf_target__has_cpu(target) && !target->uses_mmap)
578 		evlist->cpus = cpu_map__dummy_new();
579 	else
580 		evlist->cpus = cpu_map__new(target->cpu_list);
581 
582 	if (evlist->cpus == NULL)
583 		goto out_delete_threads;
584 
585 	return 0;
586 
587 out_delete_threads:
588 	thread_map__delete(evlist->threads);
589 	return -1;
590 }
591 
592 void perf_evlist__delete_maps(struct perf_evlist *evlist)
593 {
594 	cpu_map__delete(evlist->cpus);
595 	thread_map__delete(evlist->threads);
596 	evlist->cpus	= NULL;
597 	evlist->threads = NULL;
598 }
599 
600 int perf_evlist__apply_filters(struct perf_evlist *evlist)
601 {
602 	struct perf_evsel *evsel;
603 	int err = 0;
604 	const int ncpus = cpu_map__nr(evlist->cpus),
605 		  nthreads = evlist->threads->nr;
606 
607 	list_for_each_entry(evsel, &evlist->entries, node) {
608 		if (evsel->filter == NULL)
609 			continue;
610 
611 		err = perf_evsel__set_filter(evsel, ncpus, nthreads, evsel->filter);
612 		if (err)
613 			break;
614 	}
615 
616 	return err;
617 }
618 
619 int perf_evlist__set_filter(struct perf_evlist *evlist, const char *filter)
620 {
621 	struct perf_evsel *evsel;
622 	int err = 0;
623 	const int ncpus = cpu_map__nr(evlist->cpus),
624 		  nthreads = evlist->threads->nr;
625 
626 	list_for_each_entry(evsel, &evlist->entries, node) {
627 		err = perf_evsel__set_filter(evsel, ncpus, nthreads, filter);
628 		if (err)
629 			break;
630 	}
631 
632 	return err;
633 }
634 
635 bool perf_evlist__valid_sample_type(struct perf_evlist *evlist)
636 {
637 	struct perf_evsel *first = perf_evlist__first(evlist), *pos = first;
638 
639 	list_for_each_entry_continue(pos, &evlist->entries, node) {
640 		if (first->attr.sample_type != pos->attr.sample_type)
641 			return false;
642 	}
643 
644 	return true;
645 }
646 
647 u64 perf_evlist__sample_type(struct perf_evlist *evlist)
648 {
649 	struct perf_evsel *first = perf_evlist__first(evlist);
650 	return first->attr.sample_type;
651 }
652 
653 u16 perf_evlist__id_hdr_size(struct perf_evlist *evlist)
654 {
655 	struct perf_evsel *first = perf_evlist__first(evlist);
656 	struct perf_sample *data;
657 	u64 sample_type;
658 	u16 size = 0;
659 
660 	if (!first->attr.sample_id_all)
661 		goto out;
662 
663 	sample_type = first->attr.sample_type;
664 
665 	if (sample_type & PERF_SAMPLE_TID)
666 		size += sizeof(data->tid) * 2;
667 
668        if (sample_type & PERF_SAMPLE_TIME)
669 		size += sizeof(data->time);
670 
671 	if (sample_type & PERF_SAMPLE_ID)
672 		size += sizeof(data->id);
673 
674 	if (sample_type & PERF_SAMPLE_STREAM_ID)
675 		size += sizeof(data->stream_id);
676 
677 	if (sample_type & PERF_SAMPLE_CPU)
678 		size += sizeof(data->cpu) * 2;
679 out:
680 	return size;
681 }
682 
683 bool perf_evlist__valid_sample_id_all(struct perf_evlist *evlist)
684 {
685 	struct perf_evsel *first = perf_evlist__first(evlist), *pos = first;
686 
687 	list_for_each_entry_continue(pos, &evlist->entries, node) {
688 		if (first->attr.sample_id_all != pos->attr.sample_id_all)
689 			return false;
690 	}
691 
692 	return true;
693 }
694 
695 bool perf_evlist__sample_id_all(struct perf_evlist *evlist)
696 {
697 	struct perf_evsel *first = perf_evlist__first(evlist);
698 	return first->attr.sample_id_all;
699 }
700 
701 void perf_evlist__set_selected(struct perf_evlist *evlist,
702 			       struct perf_evsel *evsel)
703 {
704 	evlist->selected = evsel;
705 }
706 
707 int perf_evlist__open(struct perf_evlist *evlist)
708 {
709 	struct perf_evsel *evsel;
710 	int err, ncpus, nthreads;
711 
712 	list_for_each_entry(evsel, &evlist->entries, node) {
713 		err = perf_evsel__open(evsel, evlist->cpus, evlist->threads);
714 		if (err < 0)
715 			goto out_err;
716 	}
717 
718 	return 0;
719 out_err:
720 	ncpus = evlist->cpus ? evlist->cpus->nr : 1;
721 	nthreads = evlist->threads ? evlist->threads->nr : 1;
722 
723 	list_for_each_entry_reverse(evsel, &evlist->entries, node)
724 		perf_evsel__close(evsel, ncpus, nthreads);
725 
726 	errno = -err;
727 	return err;
728 }
729 
730 int perf_evlist__prepare_workload(struct perf_evlist *evlist,
731 				  struct perf_record_opts *opts,
732 				  const char *argv[])
733 {
734 	int child_ready_pipe[2], go_pipe[2];
735 	char bf;
736 
737 	if (pipe(child_ready_pipe) < 0) {
738 		perror("failed to create 'ready' pipe");
739 		return -1;
740 	}
741 
742 	if (pipe(go_pipe) < 0) {
743 		perror("failed to create 'go' pipe");
744 		goto out_close_ready_pipe;
745 	}
746 
747 	evlist->workload.pid = fork();
748 	if (evlist->workload.pid < 0) {
749 		perror("failed to fork");
750 		goto out_close_pipes;
751 	}
752 
753 	if (!evlist->workload.pid) {
754 		if (opts->pipe_output)
755 			dup2(2, 1);
756 
757 		close(child_ready_pipe[0]);
758 		close(go_pipe[1]);
759 		fcntl(go_pipe[0], F_SETFD, FD_CLOEXEC);
760 
761 		/*
762 		 * Do a dummy execvp to get the PLT entry resolved,
763 		 * so we avoid the resolver overhead on the real
764 		 * execvp call.
765 		 */
766 		execvp("", (char **)argv);
767 
768 		/*
769 		 * Tell the parent we're ready to go
770 		 */
771 		close(child_ready_pipe[1]);
772 
773 		/*
774 		 * Wait until the parent tells us to go.
775 		 */
776 		if (read(go_pipe[0], &bf, 1) == -1)
777 			perror("unable to read pipe");
778 
779 		execvp(argv[0], (char **)argv);
780 
781 		perror(argv[0]);
782 		kill(getppid(), SIGUSR1);
783 		exit(-1);
784 	}
785 
786 	if (perf_target__none(&opts->target))
787 		evlist->threads->map[0] = evlist->workload.pid;
788 
789 	close(child_ready_pipe[1]);
790 	close(go_pipe[0]);
791 	/*
792 	 * wait for child to settle
793 	 */
794 	if (read(child_ready_pipe[0], &bf, 1) == -1) {
795 		perror("unable to read pipe");
796 		goto out_close_pipes;
797 	}
798 
799 	evlist->workload.cork_fd = go_pipe[1];
800 	close(child_ready_pipe[0]);
801 	return 0;
802 
803 out_close_pipes:
804 	close(go_pipe[0]);
805 	close(go_pipe[1]);
806 out_close_ready_pipe:
807 	close(child_ready_pipe[0]);
808 	close(child_ready_pipe[1]);
809 	return -1;
810 }
811 
812 int perf_evlist__start_workload(struct perf_evlist *evlist)
813 {
814 	if (evlist->workload.cork_fd > 0) {
815 		/*
816 		 * Remove the cork, let it rip!
817 		 */
818 		return close(evlist->workload.cork_fd);
819 	}
820 
821 	return 0;
822 }
823 
824 int perf_evlist__parse_sample(struct perf_evlist *evlist, union perf_event *event,
825 			      struct perf_sample *sample)
826 {
827 	struct perf_evsel *evsel = perf_evlist__first(evlist);
828 	return perf_evsel__parse_sample(evsel, event, sample);
829 }
830 
831 size_t perf_evlist__fprintf(struct perf_evlist *evlist, FILE *fp)
832 {
833 	struct perf_evsel *evsel;
834 	size_t printed = 0;
835 
836 	list_for_each_entry(evsel, &evlist->entries, node) {
837 		printed += fprintf(fp, "%s%s", evsel->idx ? ", " : "",
838 				   perf_evsel__name(evsel));
839 	}
840 
841 	return printed + fprintf(fp, "\n");;
842 }
843