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- /* SPDX-License-Identifier: GPL-2.0 */
- #include "perf-sys.h"
- #include "util/cloexec.h"
- #include "util/evlist.h"
- #include "util/evsel.h"
- #include "util/parse-events.h"
- #include "util/perf_api_probe.h"
- #include <perf/cpumap.h>
- #include <errno.h>
- typedef void (*setup_probe_fn_t)(struct evsel *evsel);
- static int perf_do_probe_api(setup_probe_fn_t fn, int cpu, const char *str)
- {
- struct evlist *evlist;
- struct evsel *evsel;
- unsigned long flags = perf_event_open_cloexec_flag();
- int err = -EAGAIN, fd;
- static pid_t pid = -1;
- evlist = evlist__new();
- if (!evlist)
- return -ENOMEM;
- if (parse_events(evlist, str, NULL))
- goto out_delete;
- evsel = evlist__first(evlist);
- while (1) {
- fd = sys_perf_event_open(&evsel->core.attr, pid, cpu, -1, flags);
- if (fd < 0) {
- if (pid == -1 && errno == EACCES) {
- pid = 0;
- continue;
- }
- goto out_delete;
- }
- break;
- }
- close(fd);
- fn(evsel);
- fd = sys_perf_event_open(&evsel->core.attr, pid, cpu, -1, flags);
- if (fd < 0) {
- if (errno == EINVAL)
- err = -EINVAL;
- goto out_delete;
- }
- close(fd);
- err = 0;
- out_delete:
- evlist__delete(evlist);
- return err;
- }
- static bool perf_probe_api(setup_probe_fn_t fn)
- {
- const char *try[] = {"cycles:u", "instructions:u", "cpu-clock:u", NULL};
- struct perf_cpu_map *cpus;
- int cpu, ret, i = 0;
- cpus = perf_cpu_map__new(NULL);
- if (!cpus)
- return false;
- cpu = cpus->map[0];
- perf_cpu_map__put(cpus);
- do {
- ret = perf_do_probe_api(fn, cpu, try[i++]);
- if (!ret)
- return true;
- } while (ret == -EAGAIN && try[i]);
- return false;
- }
- static void perf_probe_sample_identifier(struct evsel *evsel)
- {
- evsel->core.attr.sample_type |= PERF_SAMPLE_IDENTIFIER;
- }
- static void perf_probe_comm_exec(struct evsel *evsel)
- {
- evsel->core.attr.comm_exec = 1;
- }
- static void perf_probe_context_switch(struct evsel *evsel)
- {
- evsel->core.attr.context_switch = 1;
- }
- static void perf_probe_text_poke(struct evsel *evsel)
- {
- evsel->core.attr.text_poke = 1;
- }
- bool perf_can_sample_identifier(void)
- {
- return perf_probe_api(perf_probe_sample_identifier);
- }
- bool perf_can_comm_exec(void)
- {
- return perf_probe_api(perf_probe_comm_exec);
- }
- bool perf_can_record_switch_events(void)
- {
- return perf_probe_api(perf_probe_context_switch);
- }
- bool perf_can_record_text_poke_events(void)
- {
- return perf_probe_api(perf_probe_text_poke);
- }
- bool perf_can_record_cpu_wide(void)
- {
- struct perf_event_attr attr = {
- .type = PERF_TYPE_SOFTWARE,
- .config = PERF_COUNT_SW_CPU_CLOCK,
- .exclude_kernel = 1,
- };
- struct perf_cpu_map *cpus;
- int cpu, fd;
- cpus = perf_cpu_map__new(NULL);
- if (!cpus)
- return false;
- cpu = cpus->map[0];
- perf_cpu_map__put(cpus);
- fd = sys_perf_event_open(&attr, -1, cpu, -1, 0);
- if (fd < 0)
- return false;
- close(fd);
- return true;
- }
- /*
- * Architectures are expected to know if AUX area sampling is supported by the
- * hardware. Here we check for kernel support.
- */
- bool perf_can_aux_sample(void)
- {
- struct perf_event_attr attr = {
- .size = sizeof(struct perf_event_attr),
- .exclude_kernel = 1,
- /*
- * Non-zero value causes the kernel to calculate the effective
- * attribute size up to that byte.
- */
- .aux_sample_size = 1,
- };
- int fd;
- fd = sys_perf_event_open(&attr, -1, 0, -1, 0);
- /*
- * If the kernel attribute is big enough to contain aux_sample_size
- * then we assume that it is supported. We are relying on the kernel to
- * validate the attribute size before anything else that could be wrong.
- */
- if (fd < 0 && errno == E2BIG)
- return false;
- if (fd >= 0)
- close(fd);
- return true;
- }
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