1#include <time.h>
2#include <errno.h>
3#include <stdint.h>
4#include "syscall.h"
5#include "libc.h"
6#include "atomic.h"
7
8#ifdef VDSO_CGT_SYM
9
10void *__vdsosym(const char *, const char *);
11
12static void *volatile vdso_func;
13
14static int cgt_init(clockid_t clk, struct timespec *ts)
15{
16	void *p = __vdsosym(VDSO_CGT_VER, VDSO_CGT_SYM);
17	int (*f)(clockid_t, struct timespec *) =
18		(int (*)(clockid_t, struct timespec *))p;
19	a_cas_p(&vdso_func, (void *)cgt_init, p);
20	return f ? f(clk, ts) : -ENOSYS;
21}
22
23static void *volatile vdso_func = (void *)cgt_init;
24
25#endif
26
27int __clock_gettime(clockid_t clk, struct timespec *ts)
28{
29	int r;
30
31#ifdef VDSO_CGT_SYM
32	int (*f)(clockid_t, struct timespec *) =
33		(int (*)(clockid_t, struct timespec *))vdso_func;
34	if (f) {
35		r = f(clk, ts);
36		if (!r) return r;
37		if (r == -EINVAL) return __syscall_ret(r);
38		/* Fall through on errors other than EINVAL. Some buggy
39		 * vdso implementations return ENOSYS for clocks they
40		 * can't handle, rather than making the syscall. This
41		 * also handles the case where cgt_init fails to find
42		 * a vdso function to use. */
43	}
44#endif
45
46	r = __syscall(SYS_clock_gettime, clk, ts);
47	if (r == -ENOSYS) {
48		if (clk == CLOCK_REALTIME) {
49			__syscall(SYS_gettimeofday, ts, 0);
50			ts->tv_nsec = (int)ts->tv_nsec * 1000;
51			return 0;
52		}
53		r = -EINVAL;
54	}
55	return __syscall_ret(r);
56}
57
58weak_alias(__clock_gettime, clock_gettime);
59