159263d17c2d31926672454004748b3583fe6f78
[linux-flexiantxendom0-3.2.10.git] / tools / perf / util / evlist.c
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 "evlist.h"
15 #include "evsel.h"
16 #include <unistd.h>
17
18 #include "parse-events.h"
19
20 #include <sys/mman.h>
21
22 #include <linux/bitops.h>
23 #include <linux/hash.h>
24
25 #define FD(e, x, y) (*(int *)xyarray__entry(e->fd, x, y))
26 #define SID(e, x, y) xyarray__entry(e->sample_id, x, y)
27
28 void perf_evlist__init(struct perf_evlist *evlist, struct cpu_map *cpus,
29                        struct thread_map *threads)
30 {
31         int i;
32
33         for (i = 0; i < PERF_EVLIST__HLIST_SIZE; ++i)
34                 INIT_HLIST_HEAD(&evlist->heads[i]);
35         INIT_LIST_HEAD(&evlist->entries);
36         perf_evlist__set_maps(evlist, cpus, threads);
37         evlist->workload.pid = -1;
38 }
39
40 struct perf_evlist *perf_evlist__new(struct cpu_map *cpus,
41                                      struct thread_map *threads)
42 {
43         struct perf_evlist *evlist = zalloc(sizeof(*evlist));
44
45         if (evlist != NULL)
46                 perf_evlist__init(evlist, cpus, threads);
47
48         return evlist;
49 }
50
51 void perf_evlist__config_attrs(struct perf_evlist *evlist,
52                                struct perf_record_opts *opts)
53 {
54         struct perf_evsel *evsel;
55
56         if (evlist->cpus->map[0] < 0)
57                 opts->no_inherit = true;
58
59         list_for_each_entry(evsel, &evlist->entries, node) {
60                 perf_evsel__config(evsel, opts);
61
62                 if (evlist->nr_entries > 1)
63                         evsel->attr.sample_type |= PERF_SAMPLE_ID;
64         }
65 }
66
67 static void perf_evlist__purge(struct perf_evlist *evlist)
68 {
69         struct perf_evsel *pos, *n;
70
71         list_for_each_entry_safe(pos, n, &evlist->entries, node) {
72                 list_del_init(&pos->node);
73                 perf_evsel__delete(pos);
74         }
75
76         evlist->nr_entries = 0;
77 }
78
79 void perf_evlist__exit(struct perf_evlist *evlist)
80 {
81         free(evlist->mmap);
82         free(evlist->pollfd);
83         evlist->mmap = NULL;
84         evlist->pollfd = NULL;
85 }
86
87 void perf_evlist__delete(struct perf_evlist *evlist)
88 {
89         perf_evlist__purge(evlist);
90         perf_evlist__exit(evlist);
91         free(evlist);
92 }
93
94 void perf_evlist__add(struct perf_evlist *evlist, struct perf_evsel *entry)
95 {
96         list_add_tail(&entry->node, &evlist->entries);
97         ++evlist->nr_entries;
98 }
99
100 void perf_evlist__splice_list_tail(struct perf_evlist *evlist,
101                                    struct list_head *list,
102                                    int nr_entries)
103 {
104         list_splice_tail(list, &evlist->entries);
105         evlist->nr_entries += nr_entries;
106 }
107
108 int perf_evlist__add_default(struct perf_evlist *evlist)
109 {
110         struct perf_event_attr attr = {
111                 .type = PERF_TYPE_HARDWARE,
112                 .config = PERF_COUNT_HW_CPU_CYCLES,
113         };
114         struct perf_evsel *evsel;
115
116         event_attr_init(&attr);
117
118         evsel = perf_evsel__new(&attr, 0);
119         if (evsel == NULL)
120                 goto error;
121
122         /* use strdup() because free(evsel) assumes name is allocated */
123         evsel->name = strdup("cycles");
124         if (!evsel->name)
125                 goto error_free;
126
127         perf_evlist__add(evlist, evsel);
128         return 0;
129 error_free:
130         perf_evsel__delete(evsel);
131 error:
132         return -ENOMEM;
133 }
134
135 int perf_evlist__add_attrs(struct perf_evlist *evlist,
136                            struct perf_event_attr *attrs, size_t nr_attrs)
137 {
138         struct perf_evsel *evsel, *n;
139         LIST_HEAD(head);
140         size_t i;
141
142         for (i = 0; i < nr_attrs; i++) {
143                 evsel = perf_evsel__new(attrs + i, evlist->nr_entries + i);
144                 if (evsel == NULL)
145                         goto out_delete_partial_list;
146                 list_add_tail(&evsel->node, &head);
147         }
148
149         perf_evlist__splice_list_tail(evlist, &head, nr_attrs);
150
151         return 0;
152
153 out_delete_partial_list:
154         list_for_each_entry_safe(evsel, n, &head, node)
155                 perf_evsel__delete(evsel);
156         return -1;
157 }
158
159 static int trace_event__id(const char *evname)
160 {
161         char *filename, *colon;
162         int err = -1, fd;
163
164         if (asprintf(&filename, "%s/%s/id", tracing_events_path, evname) < 0)
165                 return -1;
166
167         colon = strrchr(filename, ':');
168         if (colon != NULL)
169                 *colon = '/';
170
171         fd = open(filename, O_RDONLY);
172         if (fd >= 0) {
173                 char id[16];
174                 if (read(fd, id, sizeof(id)) > 0)
175                         err = atoi(id);
176                 close(fd);
177         }
178
179         free(filename);
180         return err;
181 }
182
183 int perf_evlist__add_tracepoints(struct perf_evlist *evlist,
184                                  const char *tracepoints[],
185                                  size_t nr_tracepoints)
186 {
187         int err;
188         size_t i;
189         struct perf_event_attr *attrs = zalloc(nr_tracepoints * sizeof(*attrs));
190
191         if (attrs == NULL)
192                 return -1;
193
194         for (i = 0; i < nr_tracepoints; i++) {
195                 err = trace_event__id(tracepoints[i]);
196
197                 if (err < 0)
198                         goto out_free_attrs;
199
200                 attrs[i].type          = PERF_TYPE_TRACEPOINT;
201                 attrs[i].config        = err;
202                 attrs[i].sample_type   = (PERF_SAMPLE_RAW | PERF_SAMPLE_TIME |
203                                           PERF_SAMPLE_CPU);
204                 attrs[i].sample_period = 1;
205         }
206
207         err = perf_evlist__add_attrs(evlist, attrs, nr_tracepoints);
208 out_free_attrs:
209         free(attrs);
210         return err;
211 }
212
213 static struct perf_evsel *
214         perf_evlist__find_tracepoint_by_id(struct perf_evlist *evlist, int id)
215 {
216         struct perf_evsel *evsel;
217
218         list_for_each_entry(evsel, &evlist->entries, node) {
219                 if (evsel->attr.type   == PERF_TYPE_TRACEPOINT &&
220                     (int)evsel->attr.config == id)
221                         return evsel;
222         }
223
224         return NULL;
225 }
226
227 int perf_evlist__set_tracepoints_handlers(struct perf_evlist *evlist,
228                                           const struct perf_evsel_str_handler *assocs,
229                                           size_t nr_assocs)
230 {
231         struct perf_evsel *evsel;
232         int err;
233         size_t i;
234
235         for (i = 0; i < nr_assocs; i++) {
236                 err = trace_event__id(assocs[i].name);
237                 if (err < 0)
238                         goto out;
239
240                 evsel = perf_evlist__find_tracepoint_by_id(evlist, err);
241                 if (evsel == NULL)
242                         continue;
243
244                 err = -EEXIST;
245                 if (evsel->handler.func != NULL)
246                         goto out;
247                 evsel->handler.func = assocs[i].handler;
248         }
249
250         err = 0;
251 out:
252         return err;
253 }
254
255 void perf_evlist__disable(struct perf_evlist *evlist)
256 {
257         int cpu, thread;
258         struct perf_evsel *pos;
259
260         for (cpu = 0; cpu < evlist->cpus->nr; cpu++) {
261                 list_for_each_entry(pos, &evlist->entries, node) {
262                         for (thread = 0; thread < evlist->threads->nr; thread++)
263                                 ioctl(FD(pos, cpu, thread), PERF_EVENT_IOC_DISABLE);
264                 }
265         }
266 }
267
268 void perf_evlist__enable(struct perf_evlist *evlist)
269 {
270         int cpu, thread;
271         struct perf_evsel *pos;
272
273         for (cpu = 0; cpu < evlist->cpus->nr; cpu++) {
274                 list_for_each_entry(pos, &evlist->entries, node) {
275                         for (thread = 0; thread < evlist->threads->nr; thread++)
276                                 ioctl(FD(pos, cpu, thread), PERF_EVENT_IOC_ENABLE);
277                 }
278         }
279 }
280
281 static int perf_evlist__alloc_pollfd(struct perf_evlist *evlist)
282 {
283         int nfds = evlist->cpus->nr * evlist->threads->nr * evlist->nr_entries;
284         evlist->pollfd = malloc(sizeof(struct pollfd) * nfds);
285         return evlist->pollfd != NULL ? 0 : -ENOMEM;
286 }
287
288 void perf_evlist__add_pollfd(struct perf_evlist *evlist, int fd)
289 {
290         fcntl(fd, F_SETFL, O_NONBLOCK);
291         evlist->pollfd[evlist->nr_fds].fd = fd;
292         evlist->pollfd[evlist->nr_fds].events = POLLIN;
293         evlist->nr_fds++;
294 }
295
296 static void perf_evlist__id_hash(struct perf_evlist *evlist,
297                                  struct perf_evsel *evsel,
298                                  int cpu, int thread, u64 id)
299 {
300         int hash;
301         struct perf_sample_id *sid = SID(evsel, cpu, thread);
302
303         sid->id = id;
304         sid->evsel = evsel;
305         hash = hash_64(sid->id, PERF_EVLIST__HLIST_BITS);
306         hlist_add_head(&sid->node, &evlist->heads[hash]);
307 }
308
309 void perf_evlist__id_add(struct perf_evlist *evlist, struct perf_evsel *evsel,
310                          int cpu, int thread, u64 id)
311 {
312         perf_evlist__id_hash(evlist, evsel, cpu, thread, id);
313         evsel->id[evsel->ids++] = id;
314 }
315
316 static int perf_evlist__id_add_fd(struct perf_evlist *evlist,
317                                   struct perf_evsel *evsel,
318                                   int cpu, int thread, int fd)
319 {
320         u64 read_data[4] = { 0, };
321         int id_idx = 1; /* The first entry is the counter value */
322
323         if (!(evsel->attr.read_format & PERF_FORMAT_ID) ||
324             read(fd, &read_data, sizeof(read_data)) == -1)
325                 return -1;
326
327         if (evsel->attr.read_format & PERF_FORMAT_TOTAL_TIME_ENABLED)
328                 ++id_idx;
329         if (evsel->attr.read_format & PERF_FORMAT_TOTAL_TIME_RUNNING)
330                 ++id_idx;
331
332         perf_evlist__id_add(evlist, evsel, cpu, thread, read_data[id_idx]);
333         return 0;
334 }
335
336 struct perf_evsel *perf_evlist__id2evsel(struct perf_evlist *evlist, u64 id)
337 {
338         struct hlist_head *head;
339         struct hlist_node *pos;
340         struct perf_sample_id *sid;
341         int hash;
342
343         if (evlist->nr_entries == 1)
344                 return list_entry(evlist->entries.next, struct perf_evsel, node);
345
346         hash = hash_64(id, PERF_EVLIST__HLIST_BITS);
347         head = &evlist->heads[hash];
348
349         hlist_for_each_entry(sid, pos, head, node)
350                 if (sid->id == id)
351                         return sid->evsel;
352
353         if (!perf_evlist__sample_id_all(evlist))
354                 return list_entry(evlist->entries.next, struct perf_evsel, node);
355
356         return NULL;
357 }
358
359 union perf_event *perf_evlist__mmap_read(struct perf_evlist *evlist, int idx)
360 {
361         /* XXX Move this to perf.c, making it generally available */
362         unsigned int page_size = sysconf(_SC_PAGE_SIZE);
363         struct perf_mmap *md = &evlist->mmap[idx];
364         unsigned int head = perf_mmap__read_head(md);
365         unsigned int old = md->prev;
366         unsigned char *data = md->base + page_size;
367         union perf_event *event = NULL;
368
369         if (evlist->overwrite) {
370                 /*
371                  * If we're further behind than half the buffer, there's a chance
372                  * the writer will bite our tail and mess up the samples under us.
373                  *
374                  * If we somehow ended up ahead of the head, we got messed up.
375                  *
376                  * In either case, truncate and restart at head.
377                  */
378                 int diff = head - old;
379                 if (diff > md->mask / 2 || diff < 0) {
380                         fprintf(stderr, "WARNING: failed to keep up with mmap data.\n");
381
382                         /*
383                          * head points to a known good entry, start there.
384                          */
385                         old = head;
386                 }
387         }
388
389         if (old != head) {
390                 size_t size;
391
392                 event = (union perf_event *)&data[old & md->mask];
393                 size = event->header.size;
394
395                 /*
396                  * Event straddles the mmap boundary -- header should always
397                  * be inside due to u64 alignment of output.
398                  */
399                 if ((old & md->mask) + size != ((old + size) & md->mask)) {
400                         unsigned int offset = old;
401                         unsigned int len = min(sizeof(*event), size), cpy;
402                         void *dst = &evlist->event_copy;
403
404                         do {
405                                 cpy = min(md->mask + 1 - (offset & md->mask), len);
406                                 memcpy(dst, &data[offset & md->mask], cpy);
407                                 offset += cpy;
408                                 dst += cpy;
409                                 len -= cpy;
410                         } while (len);
411
412                         event = &evlist->event_copy;
413                 }
414
415                 old += size;
416         }
417
418         md->prev = old;
419
420         if (!evlist->overwrite)
421                 perf_mmap__write_tail(md, old);
422
423         return event;
424 }
425
426 void perf_evlist__munmap(struct perf_evlist *evlist)
427 {
428         int i;
429
430         for (i = 0; i < evlist->nr_mmaps; i++) {
431                 if (evlist->mmap[i].base != NULL) {
432                         munmap(evlist->mmap[i].base, evlist->mmap_len);
433                         evlist->mmap[i].base = NULL;
434                 }
435         }
436
437         free(evlist->mmap);
438         evlist->mmap = NULL;
439 }
440
441 static int perf_evlist__alloc_mmap(struct perf_evlist *evlist)
442 {
443         evlist->nr_mmaps = evlist->cpus->nr;
444         if (evlist->cpus->map[0] == -1)
445                 evlist->nr_mmaps = evlist->threads->nr;
446         evlist->mmap = zalloc(evlist->nr_mmaps * sizeof(struct perf_mmap));
447         return evlist->mmap != NULL ? 0 : -ENOMEM;
448 }
449
450 static int __perf_evlist__mmap(struct perf_evlist *evlist,
451                                int idx, int prot, int mask, int fd)
452 {
453         evlist->mmap[idx].prev = 0;
454         evlist->mmap[idx].mask = mask;
455         evlist->mmap[idx].base = mmap(NULL, evlist->mmap_len, prot,
456                                       MAP_SHARED, fd, 0);
457         if (evlist->mmap[idx].base == MAP_FAILED) {
458                 evlist->mmap[idx].base = NULL;
459                 return -1;
460         }
461
462         perf_evlist__add_pollfd(evlist, fd);
463         return 0;
464 }
465
466 static int perf_evlist__mmap_per_cpu(struct perf_evlist *evlist, int prot, int mask)
467 {
468         struct perf_evsel *evsel;
469         int cpu, thread;
470
471         for (cpu = 0; cpu < evlist->cpus->nr; cpu++) {
472                 int output = -1;
473
474                 for (thread = 0; thread < evlist->threads->nr; thread++) {
475                         list_for_each_entry(evsel, &evlist->entries, node) {
476                                 int fd = FD(evsel, cpu, thread);
477
478                                 if (output == -1) {
479                                         output = fd;
480                                         if (__perf_evlist__mmap(evlist, cpu,
481                                                                 prot, mask, output) < 0)
482                                                 goto out_unmap;
483                                 } else {
484                                         if (ioctl(fd, PERF_EVENT_IOC_SET_OUTPUT, output) != 0)
485                                                 goto out_unmap;
486                                 }
487
488                                 if ((evsel->attr.read_format & PERF_FORMAT_ID) &&
489                                     perf_evlist__id_add_fd(evlist, evsel, cpu, thread, fd) < 0)
490                                         goto out_unmap;
491                         }
492                 }
493         }
494
495         return 0;
496
497 out_unmap:
498         for (cpu = 0; cpu < evlist->cpus->nr; cpu++) {
499                 if (evlist->mmap[cpu].base != NULL) {
500                         munmap(evlist->mmap[cpu].base, evlist->mmap_len);
501                         evlist->mmap[cpu].base = NULL;
502                 }
503         }
504         return -1;
505 }
506
507 static int perf_evlist__mmap_per_thread(struct perf_evlist *evlist, int prot, int mask)
508 {
509         struct perf_evsel *evsel;
510         int thread;
511
512         for (thread = 0; thread < evlist->threads->nr; thread++) {
513                 int output = -1;
514
515                 list_for_each_entry(evsel, &evlist->entries, node) {
516                         int fd = FD(evsel, 0, thread);
517
518                         if (output == -1) {
519                                 output = fd;
520                                 if (__perf_evlist__mmap(evlist, thread,
521                                                         prot, mask, output) < 0)
522                                         goto out_unmap;
523                         } else {
524                                 if (ioctl(fd, PERF_EVENT_IOC_SET_OUTPUT, output) != 0)
525                                         goto out_unmap;
526                         }
527
528                         if ((evsel->attr.read_format & PERF_FORMAT_ID) &&
529                             perf_evlist__id_add_fd(evlist, evsel, 0, thread, fd) < 0)
530                                 goto out_unmap;
531                 }
532         }
533
534         return 0;
535
536 out_unmap:
537         for (thread = 0; thread < evlist->threads->nr; thread++) {
538                 if (evlist->mmap[thread].base != NULL) {
539                         munmap(evlist->mmap[thread].base, evlist->mmap_len);
540                         evlist->mmap[thread].base = NULL;
541                 }
542         }
543         return -1;
544 }
545
546 /** perf_evlist__mmap - Create per cpu maps to receive events
547  *
548  * @evlist - list of events
549  * @pages - map length in pages
550  * @overwrite - overwrite older events?
551  *
552  * If overwrite is false the user needs to signal event consuption using:
553  *
554  *      struct perf_mmap *m = &evlist->mmap[cpu];
555  *      unsigned int head = perf_mmap__read_head(m);
556  *
557  *      perf_mmap__write_tail(m, head)
558  *
559  * Using perf_evlist__read_on_cpu does this automatically.
560  */
561 int perf_evlist__mmap(struct perf_evlist *evlist, unsigned int pages,
562                       bool overwrite)
563 {
564         unsigned int page_size = sysconf(_SC_PAGE_SIZE);
565         struct perf_evsel *evsel;
566         const struct cpu_map *cpus = evlist->cpus;
567         const struct thread_map *threads = evlist->threads;
568         int prot = PROT_READ | (overwrite ? 0 : PROT_WRITE), mask;
569
570         /* 512 kiB: default amount of unprivileged mlocked memory */
571         if (pages == UINT_MAX)
572                 pages = (512 * 1024) / page_size;
573         else if (!is_power_of_2(pages))
574                 return -EINVAL;
575
576         mask = pages * page_size - 1;
577
578         if (evlist->mmap == NULL && perf_evlist__alloc_mmap(evlist) < 0)
579                 return -ENOMEM;
580
581         if (evlist->pollfd == NULL && perf_evlist__alloc_pollfd(evlist) < 0)
582                 return -ENOMEM;
583
584         evlist->overwrite = overwrite;
585         evlist->mmap_len = (pages + 1) * page_size;
586
587         list_for_each_entry(evsel, &evlist->entries, node) {
588                 if ((evsel->attr.read_format & PERF_FORMAT_ID) &&
589                     evsel->sample_id == NULL &&
590                     perf_evsel__alloc_id(evsel, cpus->nr, threads->nr) < 0)
591                         return -ENOMEM;
592         }
593
594         if (evlist->cpus->map[0] == -1)
595                 return perf_evlist__mmap_per_thread(evlist, prot, mask);
596
597         return perf_evlist__mmap_per_cpu(evlist, prot, mask);
598 }
599
600 int perf_evlist__create_maps(struct perf_evlist *evlist, const char *target_pid,
601                              const char *target_tid, uid_t uid, const char *cpu_list)
602 {
603         evlist->threads = thread_map__new_str(target_pid, target_tid, uid);
604
605         if (evlist->threads == NULL)
606                 return -1;
607
608         if (uid != UINT_MAX || (cpu_list == NULL && target_tid))
609                 evlist->cpus = cpu_map__dummy_new();
610         else
611                 evlist->cpus = cpu_map__new(cpu_list);
612
613         if (evlist->cpus == NULL)
614                 goto out_delete_threads;
615
616         return 0;
617
618 out_delete_threads:
619         thread_map__delete(evlist->threads);
620         return -1;
621 }
622
623 void perf_evlist__delete_maps(struct perf_evlist *evlist)
624 {
625         cpu_map__delete(evlist->cpus);
626         thread_map__delete(evlist->threads);
627         evlist->cpus    = NULL;
628         evlist->threads = NULL;
629 }
630
631 int perf_evlist__set_filters(struct perf_evlist *evlist)
632 {
633         const struct thread_map *threads = evlist->threads;
634         const struct cpu_map *cpus = evlist->cpus;
635         struct perf_evsel *evsel;
636         char *filter;
637         int thread;
638         int cpu;
639         int err;
640         int fd;
641
642         list_for_each_entry(evsel, &evlist->entries, node) {
643                 filter = evsel->filter;
644                 if (!filter)
645                         continue;
646                 for (cpu = 0; cpu < cpus->nr; cpu++) {
647                         for (thread = 0; thread < threads->nr; thread++) {
648                                 fd = FD(evsel, cpu, thread);
649                                 err = ioctl(fd, PERF_EVENT_IOC_SET_FILTER, filter);
650                                 if (err)
651                                         return err;
652                         }
653                 }
654         }
655
656         return 0;
657 }
658
659 bool perf_evlist__valid_sample_type(const struct perf_evlist *evlist)
660 {
661         struct perf_evsel *pos, *first;
662
663         pos = first = list_entry(evlist->entries.next, struct perf_evsel, node);
664
665         list_for_each_entry_continue(pos, &evlist->entries, node) {
666                 if (first->attr.sample_type != pos->attr.sample_type)
667                         return false;
668         }
669
670         return true;
671 }
672
673 u64 perf_evlist__sample_type(const struct perf_evlist *evlist)
674 {
675         struct perf_evsel *first;
676
677         first = list_entry(evlist->entries.next, struct perf_evsel, node);
678         return first->attr.sample_type;
679 }
680
681 u16 perf_evlist__id_hdr_size(const struct perf_evlist *evlist)
682 {
683         struct perf_evsel *first;
684         struct perf_sample *data;
685         u64 sample_type;
686         u16 size = 0;
687
688         first = list_entry(evlist->entries.next, struct perf_evsel, node);
689
690         if (!first->attr.sample_id_all)
691                 goto out;
692
693         sample_type = first->attr.sample_type;
694
695         if (sample_type & PERF_SAMPLE_TID)
696                 size += sizeof(data->tid) * 2;
697
698        if (sample_type & PERF_SAMPLE_TIME)
699                 size += sizeof(data->time);
700
701         if (sample_type & PERF_SAMPLE_ID)
702                 size += sizeof(data->id);
703
704         if (sample_type & PERF_SAMPLE_STREAM_ID)
705                 size += sizeof(data->stream_id);
706
707         if (sample_type & PERF_SAMPLE_CPU)
708                 size += sizeof(data->cpu) * 2;
709 out:
710         return size;
711 }
712
713 bool perf_evlist__valid_sample_id_all(const struct perf_evlist *evlist)
714 {
715         struct perf_evsel *pos, *first;
716
717         pos = first = list_entry(evlist->entries.next, struct perf_evsel, node);
718
719         list_for_each_entry_continue(pos, &evlist->entries, node) {
720                 if (first->attr.sample_id_all != pos->attr.sample_id_all)
721                         return false;
722         }
723
724         return true;
725 }
726
727 bool perf_evlist__sample_id_all(const struct perf_evlist *evlist)
728 {
729         struct perf_evsel *first;
730
731         first = list_entry(evlist->entries.next, struct perf_evsel, node);
732         return first->attr.sample_id_all;
733 }
734
735 void perf_evlist__set_selected(struct perf_evlist *evlist,
736                                struct perf_evsel *evsel)
737 {
738         evlist->selected = evsel;
739 }
740
741 int perf_evlist__open(struct perf_evlist *evlist, bool group)
742 {
743         struct perf_evsel *evsel, *first;
744         int err, ncpus, nthreads;
745
746         first = list_entry(evlist->entries.next, struct perf_evsel, node);
747
748         list_for_each_entry(evsel, &evlist->entries, node) {
749                 struct xyarray *group_fd = NULL;
750
751                 if (group && evsel != first)
752                         group_fd = first->fd;
753
754                 err = perf_evsel__open(evsel, evlist->cpus, evlist->threads,
755                                        group, group_fd);
756                 if (err < 0)
757                         goto out_err;
758         }
759
760         return 0;
761 out_err:
762         ncpus = evlist->cpus ? evlist->cpus->nr : 1;
763         nthreads = evlist->threads ? evlist->threads->nr : 1;
764
765         list_for_each_entry_reverse(evsel, &evlist->entries, node)
766                 perf_evsel__close(evsel, ncpus, nthreads);
767
768         errno = -err;
769         return err;
770 }
771
772 int perf_evlist__prepare_workload(struct perf_evlist *evlist,
773                                   struct perf_record_opts *opts,
774                                   const char *argv[])
775 {
776         int child_ready_pipe[2], go_pipe[2];
777         char bf;
778
779         if (pipe(child_ready_pipe) < 0) {
780                 perror("failed to create 'ready' pipe");
781                 return -1;
782         }
783
784         if (pipe(go_pipe) < 0) {
785                 perror("failed to create 'go' pipe");
786                 goto out_close_ready_pipe;
787         }
788
789         evlist->workload.pid = fork();
790         if (evlist->workload.pid < 0) {
791                 perror("failed to fork");
792                 goto out_close_pipes;
793         }
794
795         if (!evlist->workload.pid) {
796                 if (opts->pipe_output)
797                         dup2(2, 1);
798
799                 close(child_ready_pipe[0]);
800                 close(go_pipe[1]);
801                 fcntl(go_pipe[0], F_SETFD, FD_CLOEXEC);
802
803                 /*
804                  * Do a dummy execvp to get the PLT entry resolved,
805                  * so we avoid the resolver overhead on the real
806                  * execvp call.
807                  */
808                 execvp("", (char **)argv);
809
810                 /*
811                  * Tell the parent we're ready to go
812                  */
813                 close(child_ready_pipe[1]);
814
815                 /*
816                  * Wait until the parent tells us to go.
817                  */
818                 if (read(go_pipe[0], &bf, 1) == -1)
819                         perror("unable to read pipe");
820
821                 execvp(argv[0], (char **)argv);
822
823                 perror(argv[0]);
824                 kill(getppid(), SIGUSR1);
825                 exit(-1);
826         }
827
828         if (!opts->system_wide && !opts->target_tid && !opts->target_pid)
829                 evlist->threads->map[0] = evlist->workload.pid;
830
831         close(child_ready_pipe[1]);
832         close(go_pipe[0]);
833         /*
834          * wait for child to settle
835          */
836         if (read(child_ready_pipe[0], &bf, 1) == -1) {
837                 perror("unable to read pipe");
838                 goto out_close_pipes;
839         }
840
841         evlist->workload.cork_fd = go_pipe[1];
842         close(child_ready_pipe[0]);
843         return 0;
844
845 out_close_pipes:
846         close(go_pipe[0]);
847         close(go_pipe[1]);
848 out_close_ready_pipe:
849         close(child_ready_pipe[0]);
850         close(child_ready_pipe[1]);
851         return -1;
852 }
853
854 int perf_evlist__start_workload(struct perf_evlist *evlist)
855 {
856         if (evlist->workload.cork_fd > 0) {
857                 /*
858                  * Remove the cork, let it rip!
859                  */
860                 return close(evlist->workload.cork_fd);
861         }
862
863         return 0;
864 }