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
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
|
/*
* Copyright 2006 Andi Kleen, SUSE Labs.
* Subject to the GNU Public License, v.2
*
* Fast user context implementation of clock_gettime and gettimeofday.
*
* The code should have no internal unresolved relocations.
* Check with readelf after changing.
* Also alternative() doesn't work.
*/
/* Disable profiling for userspace code: */
#define DISABLE_BRANCH_PROFILING
#include <linux/kernel.h>
#include <linux/posix-timers.h>
#include <linux/time.h>
#include <linux/string.h>
#include <asm/vsyscall.h>
#include <asm/vgtod.h>
#include <asm/timex.h>
#include <asm/hpet.h>
#include <asm/unistd.h>
#include <asm/io.h>
#define gtod (&VVAR(vsyscall_gtod_data))
notrace static long vdso_fallback_gettime(long clock, struct timespec *ts)
{
long ret;
asm("syscall" : "=a" (ret) :
"0" (__NR_clock_gettime),"D" (clock), "S" (ts) : "memory");
return ret;
}
notrace static inline long vgetns(void)
{
long v;
cycles_t (*vread)(void);
vread = gtod->clock.vread;
v = (vread() - gtod->clock.cycle_last) & gtod->clock.mask;
return (v * gtod->clock.mult) >> gtod->clock.shift;
}
notrace static noinline int do_realtime(struct timespec *ts)
{
unsigned long seq, ns;
do {
seq = read_seqbegin(>od->lock);
ts->tv_sec = gtod->wall_time_sec;
ts->tv_nsec = gtod->wall_time_nsec;
ns = vgetns();
} while (unlikely(read_seqretry(>od->lock, seq)));
timespec_add_ns(ts, ns);
return 0;
}
notrace static noinline int do_monotonic(struct timespec *ts)
{
unsigned long seq, ns, secs;
do {
seq = read_seqbegin(>od->lock);
secs = gtod->wall_time_sec;
ns = gtod->wall_time_nsec + vgetns();
secs += gtod->wall_to_monotonic.tv_sec;
ns += gtod->wall_to_monotonic.tv_nsec;
} while (unlikely(read_seqretry(>od->lock, seq)));
/* wall_time_nsec, vgetns(), and wall_to_monotonic.tv_nsec
* are all guaranteed to be nonnegative.
*/
while (ns >= NSEC_PER_SEC) {
ns -= NSEC_PER_SEC;
++secs;
}
ts->tv_sec = secs;
ts->tv_nsec = ns;
return 0;
}
notrace static noinline int do_realtime_coarse(struct timespec *ts)
{
unsigned long seq;
do {
seq = read_seqbegin(>od->lock);
ts->tv_sec = gtod->wall_time_coarse.tv_sec;
ts->tv_nsec = gtod->wall_time_coarse.tv_nsec;
} while (unlikely(read_seqretry(>od->lock, seq)));
return 0;
}
notrace static noinline int do_monotonic_coarse(struct timespec *ts)
{
unsigned long seq, ns, secs;
do {
seq = read_seqbegin(>od->lock);
secs = gtod->wall_time_coarse.tv_sec;
ns = gtod->wall_time_coarse.tv_nsec;
secs += gtod->wall_to_monotonic.tv_sec;
ns += gtod->wall_to_monotonic.tv_nsec;
} while (unlikely(read_seqretry(>od->lock, seq)));
/* wall_time_nsec and wall_to_monotonic.tv_nsec are
* guaranteed to be between 0 and NSEC_PER_SEC.
*/
if (ns >= NSEC_PER_SEC) {
ns -= NSEC_PER_SEC;
++secs;
}
ts->tv_sec = secs;
ts->tv_nsec = ns;
return 0;
}
notrace int __vdso_clock_gettime(clockid_t clock, struct timespec *ts)
{
if (likely(gtod->sysctl_enabled))
switch (clock) {
case CLOCK_REALTIME:
if (likely(gtod->clock.vread))
return do_realtime(ts);
break;
case CLOCK_MONOTONIC:
if (likely(gtod->clock.vread))
return do_monotonic(ts);
break;
case CLOCK_REALTIME_COARSE:
return do_realtime_coarse(ts);
case CLOCK_MONOTONIC_COARSE:
return do_monotonic_coarse(ts);
}
return vdso_fallback_gettime(clock, ts);
}
int clock_gettime(clockid_t, struct timespec *)
__attribute__((weak, alias("__vdso_clock_gettime")));
notrace int __vdso_gettimeofday(struct timeval *tv, struct timezone *tz)
{
long ret;
if (likely(gtod->sysctl_enabled && gtod->clock.vread)) {
if (likely(tv != NULL)) {
BUILD_BUG_ON(offsetof(struct timeval, tv_usec) !=
offsetof(struct timespec, tv_nsec) ||
sizeof(*tv) != sizeof(struct timespec));
do_realtime((struct timespec *)tv);
tv->tv_usec /= 1000;
}
if (unlikely(tz != NULL)) {
/* Avoid memcpy. Some old compilers fail to inline it */
tz->tz_minuteswest = gtod->sys_tz.tz_minuteswest;
tz->tz_dsttime = gtod->sys_tz.tz_dsttime;
}
return 0;
}
asm("syscall" : "=a" (ret) :
"0" (__NR_gettimeofday), "D" (tv), "S" (tz) : "memory");
return ret;
}
int gettimeofday(struct timeval *, struct timezone *)
__attribute__((weak, alias("__vdso_gettimeofday")));
|
