tools/perf/util/sideband_evlist.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2
   3 #include "util/debug.h"
   4 #include "util/evlist.h"
   5 #include "util/evsel.h"
   6 #include "util/mmap.h"
   7 #include "util/perf_api_probe.h"
   8 #include <perf/mmap.h>
   9 #include <linux/perf_event.h>
  10 #include <limits.h>
  11 #include <pthread.h>
  12 #include <sched.h>
  13 #include <stdbool.h>
  14
  15 int evlist__add_sb_event(struct evlist *evlist, struct perf_event_attr *attr,
  16                          evsel__sb_cb_t cb, void *data)
  17 {
  18         struct evsel *evsel;
  19
  20         if (!attr->sample_id_all) {
  21                 pr_warning("enabling sample_id_all for all side band events\n");
  22                 attr->sample_id_all = 1;
  23         }
  24
  25         evsel = evsel__new_idx(attr, evlist->core.nr_entries);
  26         if (!evsel)
  27                 return -1;
  28
  29         evsel->side_band.cb = cb;
  30         evsel->side_band.data = data;
  31         evlist__add(evlist, evsel);
  32         return 0;
  33 }
  34
  35 static void *perf_evlist__poll_thread(void *arg)
  36 {
  37         struct evlist *evlist = arg;
  38         bool draining = false;
  39         int i, done = 0;
  40         /*
  41          * In order to read symbols from other namespaces perf to needs to call
  42          * setns(2).  This isn't permitted if the struct_fs has multiple users.
  43          * unshare(2) the fs so that we may continue to setns into namespaces
  44          * that we're observing when, for instance, reading the build-ids at
  45          * the end of a 'perf record' session.
  46          */
  47         unshare(CLONE_FS);
  48
  49         while (!done) {
  50                 bool got_data = false;
  51
  52                 if (evlist->thread.done)
  53                         draining = true;
  54
  55                 if (!draining)
  56                         evlist__poll(evlist, 1000);
  57
  58                 for (i = 0; i < evlist->core.nr_mmaps; i++) {
  59                         struct mmap *map = &evlist->mmap[i];
  60                         union perf_event *event;
  61
  62                         if (perf_mmap__read_init(&map->core))
  63                                 continue;
  64                         while ((event = perf_mmap__read_event(&map->core)) != NULL) {
  65                                 struct evsel *evsel = evlist__event2evsel(evlist, event);
  66
  67                                 if (evsel && evsel->side_band.cb)
  68                                         evsel->side_band.cb(event, evsel->side_band.data);
  69                                 else
  70                                         pr_warning("cannot locate proper evsel for the side band event\n");
  71
  72                                 perf_mmap__consume(&map->core);
  73                                 got_data = true;
  74                         }
  75                         perf_mmap__read_done(&map->core);
  76                 }
  77
  78                 if (draining && !got_data)
  79                         break;
  80         }
  81         return NULL;
  82 }
  83
  84 void evlist__set_cb(struct evlist *evlist, evsel__sb_cb_t cb, void *data)
  85 {
  86         struct evsel *evsel;
  87
  88         evlist__for_each_entry(evlist, evsel) {
  89                 evsel->core.attr.sample_id_all    = 1;
  90                 evsel->core.attr.watermark        = 1;
  91                 evsel->core.attr.wakeup_watermark = 1;
  92                 evsel->side_band.cb   = cb;
  93                 evsel->side_band.data = data;
  94       }
  95 }
  96
  97 int evlist__start_sb_thread(struct evlist *evlist, struct target *target)
  98 {
  99         struct evsel *counter;
 100
 101         if (!evlist)
 102                 return 0;
 103
 104         if (evlist__create_maps(evlist, target))
 105                 goto out_delete_evlist;
 106
 107         if (evlist->core.nr_entries > 1) {
 108                 bool can_sample_identifier = perf_can_sample_identifier();
 109
 110                 evlist__for_each_entry(evlist, counter)
 111                         evsel__set_sample_id(counter, can_sample_identifier);
 112
 113                 evlist__set_id_pos(evlist);
 114         }
 115
 116         evlist__for_each_entry(evlist, counter) {
 117                 if (evsel__open(counter, evlist->core.cpus, evlist->core.threads) < 0)
 118                         goto out_delete_evlist;
 119         }
 120
 121         if (evlist__mmap(evlist, UINT_MAX))
 122                 goto out_delete_evlist;
 123
 124         evlist__for_each_entry(evlist, counter) {
 125                 if (evsel__enable(counter))
 126                         goto out_delete_evlist;
 127         }
 128
 129         evlist->thread.done = 0;
 130         if (pthread_create(&evlist->thread.th, NULL, perf_evlist__poll_thread, evlist))
 131                 goto out_delete_evlist;
 132
 133         return 0;
 134
 135 out_delete_evlist:
 136         evlist__delete(evlist);
 137         evlist = NULL;
 138         return -1;
 139 }
 140
 141 void evlist__stop_sb_thread(struct evlist *evlist)
 142 {
 143         if (!evlist)
 144                 return;
 145         evlist->thread.done = 1;
 146         pthread_join(evlist->thread.th, NULL);
 147         evlist__delete(evlist);
 148 }