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Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293// 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;
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;}