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https://github.com/Fishwaldo/Star64_linux.git
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c8b5f2c96d
The tools so far have been using the strerror_r() GNU variant, that returns a string, be it the buffer passed or something else. But that, besides being tricky in cases where we expect that the function using strerror_r() returns the error formatted in a provided buffer (we have to check if it returned something else and copy that instead), breaks the build on systems not using glibc, like Alpine Linux, where musl libc is used. So, introduce yet another wrapper, str_error_r(), that has the GNU interface, but uses the portable XSI variant of strerror_r(), so that users rest asured that the provided buffer is used and it is what is returned. Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: David Ahern <dsahern@gmail.com> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Wang Nan <wangnan0@huawei.com> Link: http://lkml.kernel.org/n/tip-d4t42fnf48ytlk8rjxs822tf@git.kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
96 lines
1.8 KiB
C
96 lines
1.8 KiB
C
#include <sched.h>
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#include "util.h"
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#include "../perf.h"
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#include "cloexec.h"
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#include "asm/bug.h"
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#include "debug.h"
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static unsigned long flag = PERF_FLAG_FD_CLOEXEC;
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#ifdef __GLIBC_PREREQ
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#if !__GLIBC_PREREQ(2, 6)
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int __weak sched_getcpu(void)
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{
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errno = ENOSYS;
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return -1;
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}
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#endif
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#endif
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static int perf_flag_probe(void)
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{
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/* use 'safest' configuration as used in perf_evsel__fallback() */
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struct perf_event_attr attr = {
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.type = PERF_TYPE_SOFTWARE,
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.config = PERF_COUNT_SW_CPU_CLOCK,
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.exclude_kernel = 1,
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};
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int fd;
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int err;
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int cpu;
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pid_t pid = -1;
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char sbuf[STRERR_BUFSIZE];
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cpu = sched_getcpu();
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if (cpu < 0)
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cpu = 0;
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/*
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* Using -1 for the pid is a workaround to avoid gratuitous jump label
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* changes.
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*/
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while (1) {
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/* check cloexec flag */
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fd = sys_perf_event_open(&attr, pid, cpu, -1,
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PERF_FLAG_FD_CLOEXEC);
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if (fd < 0 && pid == -1 && errno == EACCES) {
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pid = 0;
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continue;
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}
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break;
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}
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err = errno;
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if (fd >= 0) {
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close(fd);
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return 1;
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}
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WARN_ONCE(err != EINVAL && err != EBUSY,
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"perf_event_open(..., PERF_FLAG_FD_CLOEXEC) failed with unexpected error %d (%s)\n",
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err, str_error_r(err, sbuf, sizeof(sbuf)));
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/* not supported, confirm error related to PERF_FLAG_FD_CLOEXEC */
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while (1) {
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fd = sys_perf_event_open(&attr, pid, cpu, -1, 0);
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if (fd < 0 && pid == -1 && errno == EACCES) {
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pid = 0;
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continue;
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}
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break;
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}
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err = errno;
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if (fd >= 0)
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close(fd);
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if (WARN_ONCE(fd < 0 && err != EBUSY,
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"perf_event_open(..., 0) failed unexpectedly with error %d (%s)\n",
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err, str_error_r(err, sbuf, sizeof(sbuf))))
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return -1;
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return 0;
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}
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unsigned long perf_event_open_cloexec_flag(void)
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{
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static bool probed;
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if (!probed) {
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if (perf_flag_probe() <= 0)
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flag = 0;
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probed = true;
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}
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return flag;
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}
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