1 // SPDX-License-Identifier: GPL-2.0
10 #include <asm/unistd.h>
11 #include <sys/syscall.h>
13 static unsigned long flag = PERF_FLAG_FD_CLOEXEC;
15 int __weak sched_getcpu(void)
19 int err = syscall(__NR_getcpu, &cpu, NULL, NULL);
28 static int perf_flag_probe(void)
30 /* use 'safest' configuration as used in perf_evsel__fallback() */
31 struct perf_event_attr attr = {
32 .type = PERF_TYPE_SOFTWARE,
33 .config = PERF_COUNT_SW_CPU_CLOCK,
40 char sbuf[STRERR_BUFSIZE];
47 * Using -1 for the pid is a workaround to avoid gratuitous jump label
51 /* check cloexec flag */
52 fd = sys_perf_event_open(&attr, pid, cpu, -1,
53 PERF_FLAG_FD_CLOEXEC);
54 if (fd < 0 && pid == -1 && errno == EACCES) {
67 WARN_ONCE(err != EINVAL && err != EBUSY,
68 "perf_event_open(..., PERF_FLAG_FD_CLOEXEC) failed with unexpected error %d (%s)\n",
69 err, str_error_r(err, sbuf, sizeof(sbuf)));
71 /* not supported, confirm error related to PERF_FLAG_FD_CLOEXEC */
73 fd = sys_perf_event_open(&attr, pid, cpu, -1, 0);
74 if (fd < 0 && pid == -1 && errno == EACCES) {
85 if (WARN_ONCE(fd < 0 && err != EBUSY,
86 "perf_event_open(..., 0) failed unexpectedly with error %d (%s)\n",
87 err, str_error_r(err, sbuf, sizeof(sbuf))))
93 unsigned long perf_event_open_cloexec_flag(void)
98 if (perf_flag_probe() <= 0)