198 lines · c
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 the160 * 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 effective169 * 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_size178 * then we assume that it is supported. We are relying on the kernel to179 * 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