1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
|
#include <time.h>
#include <errno.h>
#include <stdint.h>
#include "syscall.h"
#include "atomic.h"
#ifdef VDSO_CGT_SYM
static void *volatile vdso_func;
static int cgt_init(clockid_t clk, struct timespec *ts)
{
void *p = __vdsosym(VDSO_CGT_VER, VDSO_CGT_SYM);
int (*f)(clockid_t, struct timespec *) =
(int (*)(clockid_t, struct timespec *))p;
a_cas_p(&vdso_func, (void *)cgt_init, p);
return f ? f(clk, ts) : -ENOSYS;
}
static void *volatile vdso_func = (void *)cgt_init;
#endif
int __clock_gettime(clockid_t clk, struct timespec *ts)
{
int r;
#ifdef VDSO_CGT_SYM
int (*f)(clockid_t, struct timespec *) =
(int (*)(clockid_t, struct timespec *))vdso_func;
if (f) {
r = f(clk, ts);
if (!r) return r;
if (r == -EINVAL) return __syscall_ret(r);
/* Fall through on errors other than EINVAL. Some buggy
* vdso implementations return ENOSYS for clocks they
* can't handle, rather than making the syscall. This
* also handles the case where cgt_init fails to find
* a vdso function to use. */
}
#endif
r = __syscall(SYS_clock_gettime, clk, ts);
if (r == -ENOSYS) {
if (clk == CLOCK_REALTIME) {
__syscall(SYS_gettimeofday, ts, 0);
ts->tv_nsec = (int)ts->tv_nsec * 1000;
return 0;
}
r = -EINVAL;
}
return __syscall_ret(r);
}
weak_alias(__clock_gettime, clock_gettime);
|
