xref: /linux/tools/perf/util/sideband_evlist.c (revision 4f2c0a4acffbec01079c28f839422e64ddeff004)
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 
evlist__add_sb_event(struct evlist * evlist,struct perf_event_attr * attr,evsel__sb_cb_t cb,void * data)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 
perf_evlist__poll_thread(void * arg)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 
evlist__set_cb(struct evlist * evlist,evsel__sb_cb_t cb,void * data)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 
evlist__start_sb_thread(struct evlist * evlist,struct target * target)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.user_requested_cpus,
118 				evlist->core.threads) < 0)
119 			goto out_delete_evlist;
120 	}
121 
122 	if (evlist__mmap(evlist, UINT_MAX))
123 		goto out_delete_evlist;
124 
125 	evlist__for_each_entry(evlist, counter) {
126 		if (evsel__enable(counter))
127 			goto out_delete_evlist;
128 	}
129 
130 	evlist->thread.done = 0;
131 	if (pthread_create(&evlist->thread.th, NULL, perf_evlist__poll_thread, evlist))
132 		goto out_delete_evlist;
133 
134 	return 0;
135 
136 out_delete_evlist:
137 	evlist__delete(evlist);
138 	evlist = NULL;
139 	return -1;
140 }
141 
evlist__stop_sb_thread(struct evlist * evlist)142 void evlist__stop_sb_thread(struct evlist *evlist)
143 {
144 	if (!evlist)
145 		return;
146 	evlist->thread.done = 1;
147 	pthread_join(evlist->thread.th, NULL);
148 	evlist__delete(evlist);
149 }
150