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, int 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_events(evlist, str, NULL))
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, -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, -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	int cpu, ret, i = 0;
65
66	cpus = perf_cpu_map__new(NULL);
67	if (!cpus)
68		return false;
69	cpu = cpus->map[0];
70	perf_cpu_map__put(cpus);
71
72	do {
73		ret = perf_do_probe_api(fn, cpu, try[i++]);
74		if (!ret)
75			return true;
76	} while (ret == -EAGAIN && try[i]);
77
78	return false;
79}
80
81static void perf_probe_sample_identifier(struct evsel *evsel)
82{
83	evsel->core.attr.sample_type |= PERF_SAMPLE_IDENTIFIER;
84}
85
86static void perf_probe_comm_exec(struct evsel *evsel)
87{
88	evsel->core.attr.comm_exec = 1;
89}
90
91static void perf_probe_context_switch(struct evsel *evsel)
92{
93	evsel->core.attr.context_switch = 1;
94}
95
96static void perf_probe_text_poke(struct evsel *evsel)
97{
98	evsel->core.attr.text_poke = 1;
99}
100
101bool perf_can_sample_identifier(void)
102{
103	return perf_probe_api(perf_probe_sample_identifier);
104}
105
106bool perf_can_comm_exec(void)
107{
108	return perf_probe_api(perf_probe_comm_exec);
109}
110
111bool perf_can_record_switch_events(void)
112{
113	return perf_probe_api(perf_probe_context_switch);
114}
115
116bool perf_can_record_text_poke_events(void)
117{
118	return perf_probe_api(perf_probe_text_poke);
119}
120
121bool perf_can_record_cpu_wide(void)
122{
123	struct perf_event_attr attr = {
124		.type = PERF_TYPE_SOFTWARE,
125		.config = PERF_COUNT_SW_CPU_CLOCK,
126		.exclude_kernel = 1,
127	};
128	struct perf_cpu_map *cpus;
129	int cpu, fd;
130
131	cpus = perf_cpu_map__new(NULL);
132	if (!cpus)
133		return false;
134	cpu = cpus->map[0];
135	perf_cpu_map__put(cpus);
136
137	fd = sys_perf_event_open(&attr, -1, cpu, -1, 0);
138	if (fd < 0)
139		return false;
140	close(fd);
141
142	return true;
143}
144
145/*
146 * Architectures are expected to know if AUX area sampling is supported by the
147 * hardware. Here we check for kernel support.
148 */
149bool perf_can_aux_sample(void)
150{
151	struct perf_event_attr attr = {
152		.size = sizeof(struct perf_event_attr),
153		.exclude_kernel = 1,
154		/*
155		 * Non-zero value causes the kernel to calculate the effective
156		 * attribute size up to that byte.
157		 */
158		.aux_sample_size = 1,
159	};
160	int fd;
161
162	fd = sys_perf_event_open(&attr, -1, 0, -1, 0);
163	/*
164	 * If the kernel attribute is big enough to contain aux_sample_size
165	 * then we assume that it is supported. We are relying on the kernel to
166	 * validate the attribute size before anything else that could be wrong.
167	 */
168	if (fd < 0 && errno == E2BIG)
169		return false;
170	if (fd >= 0)
171		close(fd);
172
173	return true;
174}
175