sparc64: Fully support both performance counters.
[linux-2.6.git] / arch / x86 / vdso / vclock_gettime.c
1 /*
2  * Copyright 2006 Andi Kleen, SUSE Labs.
3  * Subject to the GNU Public License, v.2
4  *
5  * Fast user context implementation of clock_gettime and gettimeofday.
6  *
7  * The code should have no internal unresolved relocations.
8  * Check with readelf after changing.
9  * Also alternative() doesn't work.
10  */
11
12 /* Disable profiling for userspace code: */
13 #define DISABLE_BRANCH_PROFILING
14
15 #include <linux/kernel.h>
16 #include <linux/posix-timers.h>
17 #include <linux/time.h>
18 #include <linux/string.h>
19 #include <asm/vsyscall.h>
20 #include <asm/vgtod.h>
21 #include <asm/timex.h>
22 #include <asm/hpet.h>
23 #include <asm/unistd.h>
24 #include <asm/io.h>
25 #include "vextern.h"
26
27 #define gtod vdso_vsyscall_gtod_data
28
29 notrace static long vdso_fallback_gettime(long clock, struct timespec *ts)
30 {
31         long ret;
32         asm("syscall" : "=a" (ret) :
33             "0" (__NR_clock_gettime),"D" (clock), "S" (ts) : "memory");
34         return ret;
35 }
36
37 notrace static inline long vgetns(void)
38 {
39         long v;
40         cycles_t (*vread)(void);
41         vread = gtod->clock.vread;
42         v = (vread() - gtod->clock.cycle_last) & gtod->clock.mask;
43         return (v * gtod->clock.mult) >> gtod->clock.shift;
44 }
45
46 notrace static noinline int do_realtime(struct timespec *ts)
47 {
48         unsigned long seq, ns;
49         do {
50                 seq = read_seqbegin(&gtod->lock);
51                 ts->tv_sec = gtod->wall_time_sec;
52                 ts->tv_nsec = gtod->wall_time_nsec;
53                 ns = vgetns();
54         } while (unlikely(read_seqretry(&gtod->lock, seq)));
55         timespec_add_ns(ts, ns);
56         return 0;
57 }
58
59 /* Copy of the version in kernel/time.c which we cannot directly access */
60 notrace static void
61 vset_normalized_timespec(struct timespec *ts, long sec, long nsec)
62 {
63         while (nsec >= NSEC_PER_SEC) {
64                 nsec -= NSEC_PER_SEC;
65                 ++sec;
66         }
67         while (nsec < 0) {
68                 nsec += NSEC_PER_SEC;
69                 --sec;
70         }
71         ts->tv_sec = sec;
72         ts->tv_nsec = nsec;
73 }
74
75 notrace static noinline int do_monotonic(struct timespec *ts)
76 {
77         unsigned long seq, ns, secs;
78         do {
79                 seq = read_seqbegin(&gtod->lock);
80                 secs = gtod->wall_time_sec;
81                 ns = gtod->wall_time_nsec + vgetns();
82                 secs += gtod->wall_to_monotonic.tv_sec;
83                 ns += gtod->wall_to_monotonic.tv_nsec;
84         } while (unlikely(read_seqretry(&gtod->lock, seq)));
85         vset_normalized_timespec(ts, secs, ns);
86         return 0;
87 }
88
89 notrace static noinline int do_realtime_coarse(struct timespec *ts)
90 {
91         unsigned long seq;
92         do {
93                 seq = read_seqbegin(&gtod->lock);
94                 ts->tv_sec = gtod->wall_time_coarse.tv_sec;
95                 ts->tv_nsec = gtod->wall_time_coarse.tv_nsec;
96         } while (unlikely(read_seqretry(&gtod->lock, seq)));
97         return 0;
98 }
99
100 notrace static noinline int do_monotonic_coarse(struct timespec *ts)
101 {
102         unsigned long seq, ns, secs;
103         do {
104                 seq = read_seqbegin(&gtod->lock);
105                 secs = gtod->wall_time_coarse.tv_sec;
106                 ns = gtod->wall_time_coarse.tv_nsec;
107                 secs += gtod->wall_to_monotonic.tv_sec;
108                 ns += gtod->wall_to_monotonic.tv_nsec;
109         } while (unlikely(read_seqretry(&gtod->lock, seq)));
110         vset_normalized_timespec(ts, secs, ns);
111         return 0;
112 }
113
114 notrace int __vdso_clock_gettime(clockid_t clock, struct timespec *ts)
115 {
116         if (likely(gtod->sysctl_enabled))
117                 switch (clock) {
118                 case CLOCK_REALTIME:
119                         if (likely(gtod->clock.vread))
120                                 return do_realtime(ts);
121                         break;
122                 case CLOCK_MONOTONIC:
123                         if (likely(gtod->clock.vread))
124                                 return do_monotonic(ts);
125                         break;
126                 case CLOCK_REALTIME_COARSE:
127                         return do_realtime_coarse(ts);
128                 case CLOCK_MONOTONIC_COARSE:
129                         return do_monotonic_coarse(ts);
130                 }
131         return vdso_fallback_gettime(clock, ts);
132 }
133 int clock_gettime(clockid_t, struct timespec *)
134         __attribute__((weak, alias("__vdso_clock_gettime")));
135
136 notrace int __vdso_gettimeofday(struct timeval *tv, struct timezone *tz)
137 {
138         long ret;
139         if (likely(gtod->sysctl_enabled && gtod->clock.vread)) {
140                 if (likely(tv != NULL)) {
141                         BUILD_BUG_ON(offsetof(struct timeval, tv_usec) !=
142                                      offsetof(struct timespec, tv_nsec) ||
143                                      sizeof(*tv) != sizeof(struct timespec));
144                         do_realtime((struct timespec *)tv);
145                         tv->tv_usec /= 1000;
146                 }
147                 if (unlikely(tz != NULL)) {
148                         /* Avoid memcpy. Some old compilers fail to inline it */
149                         tz->tz_minuteswest = gtod->sys_tz.tz_minuteswest;
150                         tz->tz_dsttime = gtod->sys_tz.tz_dsttime;
151                 }
152                 return 0;
153         }
154         asm("syscall" : "=a" (ret) :
155             "0" (__NR_gettimeofday), "D" (tv), "S" (tz) : "memory");
156         return ret;
157 }
158 int gettimeofday(struct timeval *, struct timezone *)
159         __attribute__((weak, alias("__vdso_gettimeofday")));