1#include <time.h>
  2#include <errno.h>
  3#include <stdint.h>
  4#include "syscall.h"
  5#include "atomic.h"
  6
  7#ifdef VDSO_CGT_SYM
  8
  9static void *volatile vdso_func;
 10
 11#ifdef VDSO_CGT32_SYM
 12static void *volatile vdso_func_32;
 13static int cgt_time32_wrap(clockid_t clk, struct timespec *ts)
 14{
 15	long ts32[2];
 16	int (*f)(clockid_t, long[2]) =
 17		(int (*)(clockid_t, long[2]))vdso_func_32;
 18	int r = f(clk, ts32);
 19	if (!r) {
 20		/* Fallback to syscalls if time32 overflowed. Maybe
 21		 * we lucked out and somehow migrated to a kernel with
 22		 * time64 syscalls available. */
 23		if (ts32[0] < 0) {
 24			a_cas_p(&vdso_func, (void *)cgt_time32_wrap, 0);
 25			return -ENOSYS;
 26		}
 27		ts->tv_sec = ts32[0];
 28		ts->tv_nsec = ts32[1];
 29	}
 30	return r;
 31}
 32#endif
 33
 34static int cgt_init(clockid_t clk, struct timespec *ts)
 35{
 36	void *p = __vdsosym(VDSO_CGT_VER, VDSO_CGT_SYM);
 37#ifdef VDSO_CGT32_SYM
 38	if (!p) {
 39		void *q = __vdsosym(VDSO_CGT32_VER, VDSO_CGT32_SYM);
 40		if (q) {
 41			a_cas_p(&vdso_func_32, 0, q);
 42			p = cgt_time32_wrap;
 43		}
 44	}
 45#ifdef VDSO_CGT_WORKAROUND
 46	if (!__vdsosym(VDSO_CGT32_VER, VDSO_CGT32_SYM)) p = 0;
 47#endif
 48#endif
 49	int (*f)(clockid_t, struct timespec *) =
 50		(int (*)(clockid_t, struct timespec *))p;
 51	a_cas_p(&vdso_func, (void *)cgt_init, p);
 52	return f ? f(clk, ts) : -ENOSYS;
 53}
 54
 55static void *volatile vdso_func = (void *)cgt_init;
 56
 57#endif
 58
 59int __clock_gettime(clockid_t clk, struct timespec *ts)
 60{
 61	int r;
 62
 63#ifdef VDSO_CGT_SYM
 64	int (*f)(clockid_t, struct timespec *) =
 65		(int (*)(clockid_t, struct timespec *))vdso_func;
 66	if (f) {
 67		r = f(clk, ts);
 68		if (!r) return r;
 69		if (r == -EINVAL) return __syscall_ret(r);
 70		/* Fall through on errors other than EINVAL. Some buggy
 71		 * vdso implementations return ENOSYS for clocks they
 72		 * can't handle, rather than making the syscall. This
 73		 * also handles the case where cgt_init fails to find
 74		 * a vdso function to use. */
 75	}
 76#endif
 77
 78#ifdef SYS_clock_gettime64
 79	r = -ENOSYS;
 80	if (sizeof(time_t) > 4)
 81		r = __syscall(SYS_clock_gettime64, clk, ts);
 82	if (SYS_clock_gettime == SYS_clock_gettime64 || r!=-ENOSYS)
 83		return __syscall_ret(r);
 84	long ts32[2];
 85	r = __syscall(SYS_clock_gettime, clk, ts32);
 86#ifdef SYS_gettimeofday
 87	if (r==-ENOSYS && clk==CLOCK_REALTIME) {
 88		r = __syscall(SYS_gettimeofday, ts32, 0);
 89		ts32[1] *= 1000;
 90	}
 91#endif
 92	if (!r) {
 93		ts->tv_sec = ts32[0];
 94		ts->tv_nsec = ts32[1];
 95		return r;
 96	}
 97	return __syscall_ret(r);
 98#else
 99	r = __syscall(SYS_clock_gettime, clk, ts);
100#ifdef SYS_gettimeofday
101	if (r == -ENOSYS) {
102		if (clk == CLOCK_REALTIME) {
103			__syscall(SYS_gettimeofday, ts, 0);
104			ts->tv_nsec = (int)ts->tv_nsec * 1000;
105			return 0;
106		}
107		r = -EINVAL;
108	}
109#endif
110	return __syscall_ret(r);
111#endif
112}
113
114weak_alias(__clock_gettime, clock_gettime);