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}