9 #include <asm/unistd.h>
10 #include <sys/syscall.h>
12 static unsigned long flag = PERF_FLAG_FD_CLOEXEC;
14 int __weak sched_getcpu(void)
18 int err = syscall(__NR_getcpu, &cpu, NULL, NULL);
27 static int perf_flag_probe(void)
29 /* use 'safest' configuration as used in perf_evsel__fallback() */
30 struct perf_event_attr attr = {
31 .type = PERF_TYPE_SOFTWARE,
32 .config = PERF_COUNT_SW_CPU_CLOCK,
39 char sbuf[STRERR_BUFSIZE];
46 * Using -1 for the pid is a workaround to avoid gratuitous jump label
50 /* check cloexec flag */
51 fd = sys_perf_event_open(&attr, pid, cpu, -1,
52 PERF_FLAG_FD_CLOEXEC);
53 if (fd < 0 && pid == -1 && errno == EACCES) {
66 WARN_ONCE(err != EINVAL && err != EBUSY,
67 "perf_event_open(..., PERF_FLAG_FD_CLOEXEC) failed with unexpected error %d (%s)\n",
68 err, str_error_r(err, sbuf, sizeof(sbuf)));
70 /* not supported, confirm error related to PERF_FLAG_FD_CLOEXEC */
72 fd = sys_perf_event_open(&attr, pid, cpu, -1, 0);
73 if (fd < 0 && pid == -1 && errno == EACCES) {
84 if (WARN_ONCE(fd < 0 && err != EBUSY,
85 "perf_event_open(..., 0) failed unexpectedly with error %d (%s)\n",
86 err, str_error_r(err, sbuf, sizeof(sbuf))))
92 unsigned long perf_event_open_cloexec_flag(void)
97 if (perf_flag_probe() <= 0)