1/* SPDX-License-Identifier: GPL-2.0 */
2
3#include "perf-sys.h"
4#include "util/cloexec.h"
5#include "util/evlist.h"
6#include "util/evsel.h"
7#include "util/parse-events.h"
8#include "util/perf_api_probe.h"
9#include <perf/cpumap.h>
10#include <errno.h>
11
12typedef void (*setup_probe_fn_t)(struct evsel *evsel);
13
14static int perf_do_probe_api(setup_probe_fn_t fn, struct perf_cpu cpu, const char *str)
15{
16	struct evlist *evlist;
17	struct evsel *evsel;
18	unsigned long flags = perf_event_open_cloexec_flag();
19	int err = -EAGAIN, fd;
20	static pid_t pid = -1;
21
22	evlist = evlist__new();
23	if (!evlist)
24		return -ENOMEM;
25
26	if (parse_event(evlist, str))
27		goto out_delete;
28
29	evsel = evlist__first(evlist);
30
31	while (1) {
32		fd = sys_perf_event_open(&evsel->core.attr, pid, cpu.cpu, -1, flags);
33		if (fd < 0) {
34			if (pid == -1 && errno == EACCES) {
35				pid = 0;
36				continue;
37			}
38			goto out_delete;
39		}
40		break;
41	}
42	close(fd);
43
44	fn(evsel);
45
46	fd = sys_perf_event_open(&evsel->core.attr, pid, cpu.cpu, -1, flags);
47	if (fd < 0) {
48		if (errno == EINVAL)
49			err = -EINVAL;
50		goto out_delete;
51	}
52	close(fd);
53	err = 0;
54
55out_delete:
56	evlist__delete(evlist);
57	return err;
58}
59
60static bool perf_probe_api(setup_probe_fn_t fn)
61{
62	const char *try[] = {"cycles:u", "instructions:u", "cpu-clock:u", NULL};
63	struct perf_cpu_map *cpus;
64	struct perf_cpu cpu;
65	int ret, i = 0;
66
67	cpus = perf_cpu_map__new_online_cpus();
68	if (!cpus)
69		return false;
70	cpu = perf_cpu_map__cpu(cpus, 0);
71	perf_cpu_map__put(cpus);
72
73	do {
74		ret = perf_do_probe_api(fn, cpu, try[i++]);
75		if (!ret)
76			return true;
77	} while (ret == -EAGAIN && try[i]);
78
79	return false;
80}
81
82static void perf_probe_sample_identifier(struct evsel *evsel)
83{
84	evsel->core.attr.sample_type |= PERF_SAMPLE_IDENTIFIER;
85}
86
87static void perf_probe_comm_exec(struct evsel *evsel)
88{
89	evsel->core.attr.comm_exec = 1;
90}
91
92static void perf_probe_context_switch(struct evsel *evsel)
93{
94	evsel->core.attr.context_switch = 1;
95}
96
97static void perf_probe_text_poke(struct evsel *evsel)
98{
99	evsel->core.attr.text_poke = 1;
100}
101
102static void perf_probe_build_id(struct evsel *evsel)
103{
104	evsel->core.attr.build_id = 1;
105}
106
107static void perf_probe_cgroup(struct evsel *evsel)
108{
109	evsel->core.attr.cgroup = 1;
110}
111
112bool perf_can_sample_identifier(void)
113{
114	return perf_probe_api(perf_probe_sample_identifier);
115}
116
117bool perf_can_comm_exec(void)
118{
119	return perf_probe_api(perf_probe_comm_exec);
120}
121
122bool perf_can_record_switch_events(void)
123{
124	return perf_probe_api(perf_probe_context_switch);
125}
126
127bool perf_can_record_text_poke_events(void)
128{
129	return perf_probe_api(perf_probe_text_poke);
130}
131
132bool perf_can_record_cpu_wide(void)
133{
134	struct perf_event_attr attr = {
135		.type = PERF_TYPE_SOFTWARE,
136		.config = PERF_COUNT_SW_CPU_CLOCK,
137		.exclude_kernel = 1,
138	};
139	struct perf_cpu_map *cpus;
140	struct perf_cpu cpu;
141	int fd;
142
143	cpus = perf_cpu_map__new_online_cpus();
144	if (!cpus)
145		return false;
146
147	cpu = perf_cpu_map__cpu(cpus, 0);
148	perf_cpu_map__put(cpus);
149
150	fd = sys_perf_event_open(&attr, -1, cpu.cpu, -1, 0);
151	if (fd < 0)
152		return false;
153	close(fd);
154
155	return true;
156}
157
158/*
159 * Architectures are expected to know if AUX area sampling is supported by the
160 * hardware. Here we check for kernel support.
161 */
162bool perf_can_aux_sample(void)
163{
164	struct perf_event_attr attr = {
165		.size = sizeof(struct perf_event_attr),
166		.exclude_kernel = 1,
167		/*
168		 * Non-zero value causes the kernel to calculate the effective
169		 * attribute size up to that byte.
170		 */
171		.aux_sample_size = 1,
172	};
173	int fd;
174
175	fd = sys_perf_event_open(&attr, -1, 0, -1, 0);
176	/*
177	 * If the kernel attribute is big enough to contain aux_sample_size
178	 * then we assume that it is supported. We are relying on the kernel to
179	 * validate the attribute size before anything else that could be wrong.
180	 */
181	if (fd < 0 && errno == E2BIG)
182		return false;
183	if (fd >= 0)
184		close(fd);
185
186	return true;
187}
188
189bool perf_can_record_build_id(void)
190{
191	return perf_probe_api(perf_probe_build_id);
192}
193
194bool perf_can_record_cgroup(void)
195{
196	return perf_probe_api(perf_probe_cgroup);
197}
198