You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
121 lines
3.2 KiB
121 lines
3.2 KiB
/*
|
|
* 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.
|
|
*/
|
|
|
|
#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>
|
|
#include "vextern.h"
|
|
|
|
#define gtod vdso_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;
|
|
}
|
|
|
|
/* Copy of the version in kernel/time.c which we cannot directly access */
|
|
notrace static void
|
|
vset_normalized_timespec(struct timespec *ts, long sec, long nsec)
|
|
{
|
|
while (nsec >= NSEC_PER_SEC) {
|
|
nsec -= NSEC_PER_SEC;
|
|
++sec;
|
|
}
|
|
while (nsec < 0) {
|
|
nsec += NSEC_PER_SEC;
|
|
--sec;
|
|
}
|
|
ts->tv_sec = sec;
|
|
ts->tv_nsec = nsec;
|
|
}
|
|
|
|
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)));
|
|
vset_normalized_timespec(ts, secs, ns);
|
|
return 0;
|
|
}
|
|
|
|
notrace int __vdso_clock_gettime(clockid_t clock, struct timespec *ts)
|
|
{
|
|
if (likely(gtod->sysctl_enabled && gtod->clock.vread))
|
|
switch (clock) {
|
|
case CLOCK_REALTIME:
|
|
return do_realtime(ts);
|
|
case CLOCK_MONOTONIC:
|
|
return do_monotonic(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)) {
|
|
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")));
|
|
|