Commit | Line | Data |
---|---|---|
f6edb53c | 1 | #include <sched.h> |
57480d2c YD |
2 | #include "util.h" |
3 | #include "../perf.h" | |
4 | #include "cloexec.h" | |
5 | #include "asm/bug.h" | |
6e81c74c | 6 | #include "debug.h" |
57480d2c YD |
7 | |
8 | static unsigned long flag = PERF_FLAG_FD_CLOEXEC; | |
9 | ||
2b42b09b SD |
10 | #ifdef __GLIBC_PREREQ |
11 | #if !__GLIBC_PREREQ(2, 6) | |
e1e455f4 VL |
12 | int __weak sched_getcpu(void) |
13 | { | |
14 | errno = ENOSYS; | |
15 | return -1; | |
16 | } | |
2b42b09b SD |
17 | #endif |
18 | #endif | |
e1e455f4 | 19 | |
57480d2c YD |
20 | static int perf_flag_probe(void) |
21 | { | |
22 | /* use 'safest' configuration as used in perf_evsel__fallback() */ | |
23 | struct perf_event_attr attr = { | |
038fa0b9 | 24 | .type = PERF_TYPE_SOFTWARE, |
57480d2c | 25 | .config = PERF_COUNT_SW_CPU_CLOCK, |
a5b0153c | 26 | .exclude_kernel = 1, |
57480d2c YD |
27 | }; |
28 | int fd; | |
29 | int err; | |
f6edb53c AH |
30 | int cpu; |
31 | pid_t pid = -1; | |
6e81c74c | 32 | char sbuf[STRERR_BUFSIZE]; |
57480d2c | 33 | |
f6edb53c AH |
34 | cpu = sched_getcpu(); |
35 | if (cpu < 0) | |
36 | cpu = 0; | |
37 | ||
48536c91 AH |
38 | /* |
39 | * Using -1 for the pid is a workaround to avoid gratuitous jump label | |
40 | * changes. | |
41 | */ | |
f6edb53c AH |
42 | while (1) { |
43 | /* check cloexec flag */ | |
44 | fd = sys_perf_event_open(&attr, pid, cpu, -1, | |
45 | PERF_FLAG_FD_CLOEXEC); | |
46 | if (fd < 0 && pid == -1 && errno == EACCES) { | |
47 | pid = 0; | |
48 | continue; | |
49 | } | |
50 | break; | |
51 | } | |
57480d2c YD |
52 | err = errno; |
53 | ||
54 | if (fd >= 0) { | |
55 | close(fd); | |
56 | return 1; | |
57 | } | |
58 | ||
63914aca | 59 | WARN_ONCE(err != EINVAL && err != EBUSY, |
57480d2c | 60 | "perf_event_open(..., PERF_FLAG_FD_CLOEXEC) failed with unexpected error %d (%s)\n", |
6e81c74c | 61 | err, strerror_r(err, sbuf, sizeof(sbuf))); |
57480d2c YD |
62 | |
63 | /* not supported, confirm error related to PERF_FLAG_FD_CLOEXEC */ | |
48536c91 AH |
64 | while (1) { |
65 | fd = sys_perf_event_open(&attr, pid, cpu, -1, 0); | |
66 | if (fd < 0 && pid == -1 && errno == EACCES) { | |
67 | pid = 0; | |
68 | continue; | |
69 | } | |
70 | break; | |
71 | } | |
57480d2c YD |
72 | err = errno; |
73 | ||
48536c91 AH |
74 | if (fd >= 0) |
75 | close(fd); | |
76 | ||
63914aca | 77 | if (WARN_ONCE(fd < 0 && err != EBUSY, |
57480d2c | 78 | "perf_event_open(..., 0) failed unexpectedly with error %d (%s)\n", |
6e81c74c | 79 | err, strerror_r(err, sbuf, sizeof(sbuf)))) |
57480d2c YD |
80 | return -1; |
81 | ||
57480d2c YD |
82 | return 0; |
83 | } | |
84 | ||
85 | unsigned long perf_event_open_cloexec_flag(void) | |
86 | { | |
87 | static bool probed; | |
88 | ||
89 | if (!probed) { | |
90 | if (perf_flag_probe() <= 0) | |
91 | flag = 0; | |
92 | probed = true; | |
93 | } | |
94 | ||
95 | return flag; | |
96 | } |