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
12 typedef void (*setup_probe_fn_t)(struct evsel *evsel);
13
perf_do_probe_api(setup_probe_fn_t fn,struct perf_cpu cpu,const char * str)14 static 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
55 out_delete:
56 evlist__delete(evlist);
57 return err;
58 }
59
perf_probe_api(setup_probe_fn_t fn)60 static 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
perf_probe_sample_identifier(struct evsel * evsel)82 static void perf_probe_sample_identifier(struct evsel *evsel)
83 {
84 evsel->core.attr.sample_type |= PERF_SAMPLE_IDENTIFIER;
85 }
86
perf_probe_comm_exec(struct evsel * evsel)87 static void perf_probe_comm_exec(struct evsel *evsel)
88 {
89 evsel->core.attr.comm_exec = 1;
90 }
91
perf_probe_context_switch(struct evsel * evsel)92 static void perf_probe_context_switch(struct evsel *evsel)
93 {
94 evsel->core.attr.context_switch = 1;
95 }
96
perf_probe_text_poke(struct evsel * evsel)97 static void perf_probe_text_poke(struct evsel *evsel)
98 {
99 evsel->core.attr.text_poke = 1;
100 }
101
perf_probe_build_id(struct evsel * evsel)102 static void perf_probe_build_id(struct evsel *evsel)
103 {
104 evsel->core.attr.build_id = 1;
105 }
106
perf_probe_cgroup(struct evsel * evsel)107 static void perf_probe_cgroup(struct evsel *evsel)
108 {
109 evsel->core.attr.cgroup = 1;
110 }
111
perf_can_sample_identifier(void)112 bool perf_can_sample_identifier(void)
113 {
114 return perf_probe_api(perf_probe_sample_identifier);
115 }
116
perf_can_comm_exec(void)117 bool perf_can_comm_exec(void)
118 {
119 return perf_probe_api(perf_probe_comm_exec);
120 }
121
perf_can_record_switch_events(void)122 bool perf_can_record_switch_events(void)
123 {
124 return perf_probe_api(perf_probe_context_switch);
125 }
126
perf_can_record_text_poke_events(void)127 bool perf_can_record_text_poke_events(void)
128 {
129 return perf_probe_api(perf_probe_text_poke);
130 }
131
perf_can_record_cpu_wide(void)132 bool 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 */
perf_can_aux_sample(void)162 bool 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
perf_can_record_build_id(void)189 bool perf_can_record_build_id(void)
190 {
191 return perf_probe_api(perf_probe_build_id);
192 }
193
perf_can_record_cgroup(void)194 bool perf_can_record_cgroup(void)
195 {
196 return perf_probe_api(perf_probe_cgroup);
197 }
198