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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-27 10:05:51 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-27 10:05:51 +0000 |
commit | 5d1646d90e1f2cceb9f0828f4b28318cd0ec7744 (patch) | |
tree | a94efe259b9009378be6d90eb30d2b019d95c194 /tools/perf/util/cloexec.c | |
parent | Initial commit. (diff) | |
download | linux-5d1646d90e1f2cceb9f0828f4b28318cd0ec7744.tar.xz linux-5d1646d90e1f2cceb9f0828f4b28318cd0ec7744.zip |
Adding upstream version 5.10.209.upstream/5.10.209upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'tools/perf/util/cloexec.c')
-rw-r--r-- | tools/perf/util/cloexec.c | 105 |
1 files changed, 105 insertions, 0 deletions
diff --git a/tools/perf/util/cloexec.c b/tools/perf/util/cloexec.c new file mode 100644 index 000000000..fa8248aad --- /dev/null +++ b/tools/perf/util/cloexec.c @@ -0,0 +1,105 @@ +// SPDX-License-Identifier: GPL-2.0 +#include <errno.h> +#include <sched.h> +#include "util.h" // for sched_getcpu() +#include "../perf-sys.h" +#include "cloexec.h" +#include "event.h" +#include "asm/bug.h" +#include "debug.h" +#include <unistd.h> +#include <sys/syscall.h> +#include <linux/string.h> + +static unsigned long flag = PERF_FLAG_FD_CLOEXEC; + +int __weak sched_getcpu(void) +{ +#ifdef __NR_getcpu + unsigned cpu; + int err = syscall(__NR_getcpu, &cpu, NULL, NULL); + if (!err) + return cpu; +#else + errno = ENOSYS; +#endif + return -1; +} + +static int perf_flag_probe(void) +{ + /* use 'safest' configuration as used in evsel__fallback() */ + struct perf_event_attr attr = { + .type = PERF_TYPE_SOFTWARE, + .config = PERF_COUNT_SW_CPU_CLOCK, + .exclude_kernel = 1, + }; + int fd; + int err; + int cpu; + pid_t pid = -1; + char sbuf[STRERR_BUFSIZE]; + + cpu = sched_getcpu(); + if (cpu < 0) + cpu = 0; + + /* + * Using -1 for the pid is a workaround to avoid gratuitous jump label + * changes. + */ + while (1) { + /* check cloexec flag */ + fd = sys_perf_event_open(&attr, pid, cpu, -1, + PERF_FLAG_FD_CLOEXEC); + if (fd < 0 && pid == -1 && errno == EACCES) { + pid = 0; + continue; + } + break; + } + err = errno; + + if (fd >= 0) { + close(fd); + return 1; + } + + WARN_ONCE(err != EINVAL && err != EBUSY && err != EACCES, + "perf_event_open(..., PERF_FLAG_FD_CLOEXEC) failed with unexpected error %d (%s)\n", + err, str_error_r(err, sbuf, sizeof(sbuf))); + + /* not supported, confirm error related to PERF_FLAG_FD_CLOEXEC */ + while (1) { + fd = sys_perf_event_open(&attr, pid, cpu, -1, 0); + if (fd < 0 && pid == -1 && errno == EACCES) { + pid = 0; + continue; + } + break; + } + err = errno; + + if (fd >= 0) + close(fd); + + if (WARN_ONCE(fd < 0 && err != EBUSY && err != EACCES, + "perf_event_open(..., 0) failed unexpectedly with error %d (%s)\n", + err, str_error_r(err, sbuf, sizeof(sbuf)))) + return -1; + + return 0; +} + +unsigned long perf_event_open_cloexec_flag(void) +{ + static bool probed; + + if (!probed) { + if (perf_flag_probe() <= 0) + flag = 0; + probed = true; + } + + return flag; +} |