perf/util/sideband_evlist.c

0001 // SPDX-License-Identifier: GPL-2.0-only
0002
0003 #include "util/debug.h"
0004 #include "util/evlist.h"
0005 #include "util/evsel.h"
0006 #include "util/mmap.h"
0007 #include "util/perf_api_probe.h"
0008 #include <perf/mmap.h>
0009 #include <linux/perf_event.h>
0010 #include <limits.h>
0011 #include <pthread.h>
0012 #include <sched.h>
0013 #include <stdbool.h>
0014
0015 int evlist__add_sb_event(struct evlist *evlist, struct perf_event_attr *attr,
0016              evsel__sb_cb_t cb, void *data)
0017 {
0018     struct evsel *evsel;
0019
0020     if (!attr->sample_id_all) {
0021         pr_warning("enabling sample_id_all for all side band events\n");
0022         attr->sample_id_all = 1;
0023     }
0024
0025     evsel = evsel__new_idx(attr, evlist->core.nr_entries);
0026     if (!evsel)
0027         return -1;
0028
0029     evsel->side_band.cb = cb;
0030     evsel->side_band.data = data;
0031     evlist__add(evlist, evsel);
0032     return 0;
0033 }
0034
0035 static void *perf_evlist__poll_thread(void *arg)
0036 {
0037     struct evlist *evlist = arg;
0038     bool draining = false;
0039     int i, done = 0;
0040     /*
0041      * In order to read symbols from other namespaces perf to needs to call
0042      * setns(2).  This isn't permitted if the struct_fs has multiple users.
0043      * unshare(2) the fs so that we may continue to setns into namespaces
0044      * that we're observing when, for instance, reading the build-ids at
0045      * the end of a 'perf record' session.
0046      */
0047     unshare(CLONE_FS);
0048
0049     while (!done) {
0050         bool got_data = false;
0051
0052         if (evlist->thread.done)
0053             draining = true;
0054
0055         if (!draining)
0056             evlist__poll(evlist, 1000);
0057
0058         for (i = 0; i < evlist->core.nr_mmaps; i++) {
0059             struct mmap *map = &evlist->mmap[i];
0060             union perf_event *event;
0061
0062             if (perf_mmap__read_init(&map->core))
0063                 continue;
0064             while ((event = perf_mmap__read_event(&map->core)) != NULL) {
0065                 struct evsel *evsel = evlist__event2evsel(evlist, event);
0066
0067                 if (evsel && evsel->side_band.cb)
0068                     evsel->side_band.cb(event, evsel->side_band.data);
0069                 else
0070                     pr_warning("cannot locate proper evsel for the side band event\n");
0071
0072                 perf_mmap__consume(&map->core);
0073                 got_data = true;
0074             }
0075             perf_mmap__read_done(&map->core);
0076         }
0077
0078         if (draining && !got_data)
0079             break;
0080     }
0081     return NULL;
0082 }
0083
0084 void evlist__set_cb(struct evlist *evlist, evsel__sb_cb_t cb, void *data)
0085 {
0086     struct evsel *evsel;
0087
0088     evlist__for_each_entry(evlist, evsel) {
0089         evsel->core.attr.sample_id_all    = 1;
0090         evsel->core.attr.watermark        = 1;
0091         evsel->core.attr.wakeup_watermark = 1;
0092         evsel->side_band.cb   = cb;
0093         evsel->side_band.data = data;
0094       }
0095 }
0096
0097 int evlist__start_sb_thread(struct evlist *evlist, struct target *target)
0098 {
0099     struct evsel *counter;
0100
0101     if (!evlist)
0102         return 0;
0103
0104     if (evlist__create_maps(evlist, target))
0105         goto out_delete_evlist;
0106
0107     if (evlist->core.nr_entries > 1) {
0108         bool can_sample_identifier = perf_can_sample_identifier();
0109
0110         evlist__for_each_entry(evlist, counter)
0111             evsel__set_sample_id(counter, can_sample_identifier);
0112
0113         evlist__set_id_pos(evlist);
0114     }
0115
0116     evlist__for_each_entry(evlist, counter) {
0117         if (evsel__open(counter, evlist->core.user_requested_cpus,
0118                 evlist->core.threads) < 0)
0119             goto out_delete_evlist;
0120     }
0121
0122     if (evlist__mmap(evlist, UINT_MAX))
0123         goto out_delete_evlist;
0124
0125     evlist__for_each_entry(evlist, counter) {
0126         if (evsel__enable(counter))
0127             goto out_delete_evlist;
0128     }
0129
0130     evlist->thread.done = 0;
0131     if (pthread_create(&evlist->thread.th, NULL, perf_evlist__poll_thread, evlist))
0132         goto out_delete_evlist;
0133
0134     return 0;
0135
0136 out_delete_evlist:
0137     evlist__delete(evlist);
0138     evlist = NULL;
0139     return -1;
0140 }
0141
0142 void evlist__stop_sb_thread(struct evlist *evlist)
0143 {
0144     if (!evlist)
0145         return;
0146     evlist->thread.done = 1;
0147     pthread_join(evlist->thread.th, NULL);
0148     evlist__delete(evlist);
0149 }