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Commit | Line | Data |
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b2441318 | 1 | // SPDX-License-Identifier: GPL-2.0 |
a43783ae | 2 | #include <errno.h> |
f6edb53c | 3 | #include <sched.h> |
57480d2c YD |
4 | #include "util.h" |
5 | #include "../perf.h" | |
6 | #include "cloexec.h" | |
7 | #include "asm/bug.h" | |
6e81c74c | 8 | #include "debug.h" |
c7007e98 ACM |
9 | #include <unistd.h> |
10 | #include <asm/unistd.h> | |
11 | #include <sys/syscall.h> | |
57480d2c YD |
12 | |
13 | static unsigned long flag = PERF_FLAG_FD_CLOEXEC; | |
14 | ||
e1e455f4 VL |
15 | int __weak sched_getcpu(void) |
16 | { | |
c7007e98 ACM |
17 | #ifdef __NR_getcpu |
18 | unsigned cpu; | |
19 | int err = syscall(__NR_getcpu, &cpu, NULL, NULL); | |
20 | if (!err) | |
21 | return cpu; | |
22 | #else | |
e1e455f4 | 23 | errno = ENOSYS; |
c7007e98 | 24 | #endif |
e1e455f4 VL |
25 | return -1; |
26 | } | |
27 | ||
57480d2c YD |
28 | static int perf_flag_probe(void) |
29 | { | |
30 | /* use 'safest' configuration as used in perf_evsel__fallback() */ | |
31 | struct perf_event_attr attr = { | |
038fa0b9 | 32 | .type = PERF_TYPE_SOFTWARE, |
57480d2c | 33 | .config = PERF_COUNT_SW_CPU_CLOCK, |
a5b0153c | 34 | .exclude_kernel = 1, |
57480d2c YD |
35 | }; |
36 | int fd; | |
37 | int err; | |
f6edb53c AH |
38 | int cpu; |
39 | pid_t pid = -1; | |
6e81c74c | 40 | char sbuf[STRERR_BUFSIZE]; |
57480d2c | 41 | |
f6edb53c AH |
42 | cpu = sched_getcpu(); |
43 | if (cpu < 0) | |
44 | cpu = 0; | |
45 | ||
48536c91 AH |
46 | /* |
47 | * Using -1 for the pid is a workaround to avoid gratuitous jump label | |
48 | * changes. | |
49 | */ | |
f6edb53c AH |
50 | while (1) { |
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) { | |
55 | pid = 0; | |
56 | continue; | |
57 | } | |
58 | break; | |
59 | } | |
57480d2c YD |
60 | err = errno; |
61 | ||
62 | if (fd >= 0) { | |
63 | close(fd); | |
64 | return 1; | |
65 | } | |
66 | ||
63914aca | 67 | WARN_ONCE(err != EINVAL && err != EBUSY, |
57480d2c | 68 | "perf_event_open(..., PERF_FLAG_FD_CLOEXEC) failed with unexpected error %d (%s)\n", |
c8b5f2c9 | 69 | err, str_error_r(err, sbuf, sizeof(sbuf))); |
57480d2c YD |
70 | |
71 | /* not supported, confirm error related to PERF_FLAG_FD_CLOEXEC */ | |
48536c91 AH |
72 | while (1) { |
73 | fd = sys_perf_event_open(&attr, pid, cpu, -1, 0); | |
74 | if (fd < 0 && pid == -1 && errno == EACCES) { | |
75 | pid = 0; | |
76 | continue; | |
77 | } | |
78 | break; | |
79 | } | |
57480d2c YD |
80 | err = errno; |
81 | ||
48536c91 AH |
82 | if (fd >= 0) |
83 | close(fd); | |
84 | ||
63914aca | 85 | if (WARN_ONCE(fd < 0 && err != EBUSY, |
57480d2c | 86 | "perf_event_open(..., 0) failed unexpectedly with error %d (%s)\n", |
c8b5f2c9 | 87 | err, str_error_r(err, sbuf, sizeof(sbuf)))) |
57480d2c YD |
88 | return -1; |
89 | ||
57480d2c YD |
90 | return 0; |
91 | } | |
92 | ||
93 | unsigned long perf_event_open_cloexec_flag(void) | |
94 | { | |
95 | static bool probed; | |
96 | ||
97 | if (!probed) { | |
98 | if (perf_flag_probe() <= 0) | |
99 | flag = 0; | |
100 | probed = true; | |
101 | } | |
102 | ||
103 | return flag; | |
104 | } |