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
9 static void *volatile vdso_func;
10
11 #ifdef VDSO_CGT32_SYM
12 static void *volatile vdso_func_32;
cgt_time32_wrap(clockid_t clk,struct timespec * ts)13 static 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
cgt_init(clockid_t clk,struct timespec * ts)34 static 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
55 static void *volatile vdso_func = (void *)cgt_init;
56
57 #endif
58
__clock_gettime(clockid_t clk,struct timespec * ts)59 int __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
114 weak_alias(__clock_gettime, clock_gettime);
115