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,int cpu,const char * str)14 static 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
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 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
perf_probe_sample_identifier(struct evsel * evsel)81 static void perf_probe_sample_identifier(struct evsel *evsel)
82 {
83 evsel->core.attr.sample_type |= PERF_SAMPLE_IDENTIFIER;
84 }
85
perf_probe_comm_exec(struct evsel * evsel)86 static void perf_probe_comm_exec(struct evsel *evsel)
87 {
88 evsel->core.attr.comm_exec = 1;
89 }
90
perf_probe_context_switch(struct evsel * evsel)91 static void perf_probe_context_switch(struct evsel *evsel)
92 {
93 evsel->core.attr.context_switch = 1;
94 }
95
perf_probe_text_poke(struct evsel * evsel)96 static void perf_probe_text_poke(struct evsel *evsel)
97 {
98 evsel->core.attr.text_poke = 1;
99 }
100
perf_probe_build_id(struct evsel * evsel)101 static void perf_probe_build_id(struct evsel *evsel)
102 {
103 evsel->core.attr.build_id = 1;
104 }
105
perf_can_sample_identifier(void)106 bool perf_can_sample_identifier(void)
107 {
108 return perf_probe_api(perf_probe_sample_identifier);
109 }
110
perf_can_comm_exec(void)111 bool perf_can_comm_exec(void)
112 {
113 return perf_probe_api(perf_probe_comm_exec);
114 }
115
perf_can_record_switch_events(void)116 bool perf_can_record_switch_events(void)
117 {
118 return perf_probe_api(perf_probe_context_switch);
119 }
120
perf_can_record_text_poke_events(void)121 bool perf_can_record_text_poke_events(void)
122 {
123 return perf_probe_api(perf_probe_text_poke);
124 }
125
perf_can_record_cpu_wide(void)126 bool perf_can_record_cpu_wide(void)
127 {
128 struct perf_event_attr attr = {
129 .type = PERF_TYPE_SOFTWARE,
130 .config = PERF_COUNT_SW_CPU_CLOCK,
131 .exclude_kernel = 1,
132 };
133 struct perf_cpu_map *cpus;
134 int cpu, fd;
135
136 cpus = perf_cpu_map__new(NULL);
137 if (!cpus)
138 return false;
139 cpu = cpus->map[0];
140 perf_cpu_map__put(cpus);
141
142 fd = sys_perf_event_open(&attr, -1, cpu, -1, 0);
143 if (fd < 0)
144 return false;
145 close(fd);
146
147 return true;
148 }
149
150 /*
151 * Architectures are expected to know if AUX area sampling is supported by the
152 * hardware. Here we check for kernel support.
153 */
perf_can_aux_sample(void)154 bool perf_can_aux_sample(void)
155 {
156 struct perf_event_attr attr = {
157 .size = sizeof(struct perf_event_attr),
158 .exclude_kernel = 1,
159 /*
160 * Non-zero value causes the kernel to calculate the effective
161 * attribute size up to that byte.
162 */
163 .aux_sample_size = 1,
164 };
165 int fd;
166
167 fd = sys_perf_event_open(&attr, -1, 0, -1, 0);
168 /*
169 * If the kernel attribute is big enough to contain aux_sample_size
170 * then we assume that it is supported. We are relying on the kernel to
171 * validate the attribute size before anything else that could be wrong.
172 */
173 if (fd < 0 && errno == E2BIG)
174 return false;
175 if (fd >= 0)
176 close(fd);
177
178 return true;
179 }
180
perf_can_record_build_id(void)181 bool perf_can_record_build_id(void)
182 {
183 return perf_probe_api(perf_probe_build_id);
184 }
185