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Diffstat (limited to 'arch/x86/vdso/vclock_gettime.c')
-rw-r--r--arch/x86/vdso/vclock_gettime.c74
1 files changed, 53 insertions, 21 deletions
diff --git a/arch/x86/vdso/vclock_gettime.c b/arch/x86/vdso/vclock_gettime.c
index ee55754cc3c5..a724905fdae7 100644
--- a/arch/x86/vdso/vclock_gettime.c
+++ b/arch/x86/vdso/vclock_gettime.c
@@ -2,7 +2,7 @@
* Copyright 2006 Andi Kleen, SUSE Labs.
* Subject to the GNU Public License, v.2
*
- * Fast user context implementation of clock_gettime and gettimeofday.
+ * Fast user context implementation of clock_gettime, gettimeofday, and time.
*
* The code should have no internal unresolved relocations.
* Check with readelf after changing.
@@ -22,9 +22,8 @@
#include <asm/hpet.h>
#include <asm/unistd.h>
#include <asm/io.h>
-#include "vextern.h"
-#define gtod vdso_vsyscall_gtod_data
+#define gtod (&VVAR(vsyscall_gtod_data))
notrace static long vdso_fallback_gettime(long clock, struct timespec *ts)
{
@@ -56,22 +55,6 @@ notrace static noinline int do_realtime(struct timespec *ts)
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;
@@ -82,7 +65,17 @@ notrace static noinline int do_monotonic(struct timespec *ts)
secs += gtod->wall_to_monotonic.tv_sec;
ns += gtod->wall_to_monotonic.tv_nsec;
} while (unlikely(read_seqretry(&gtod->lock, seq)));
- vset_normalized_timespec(ts, secs, ns);
+
+ /* 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;
}
@@ -107,7 +100,17 @@ notrace static noinline int do_monotonic_coarse(struct timespec *ts)
secs += gtod->wall_to_monotonic.tv_sec;
ns += gtod->wall_to_monotonic.tv_nsec;
} while (unlikely(read_seqretry(&gtod->lock, seq)));
- vset_normalized_timespec(ts, secs, ns);
+
+ /* 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;
}
@@ -157,3 +160,32 @@ notrace int __vdso_gettimeofday(struct timeval *tv, struct timezone *tz)
}
int gettimeofday(struct timeval *, struct timezone *)
__attribute__((weak, alias("__vdso_gettimeofday")));
+
+/* This will break when the xtime seconds get inaccurate, but that is
+ * unlikely */
+
+static __always_inline long time_syscall(long *t)
+{
+ long secs;
+ asm volatile("syscall"
+ : "=a" (secs)
+ : "0" (__NR_time), "D" (t) : "cc", "r11", "cx", "memory");
+ return secs;
+}
+
+notrace time_t __vdso_time(time_t *t)
+{
+ time_t result;
+
+ if (unlikely(!VVAR(vsyscall_gtod_data).sysctl_enabled))
+ return time_syscall(t);
+
+ /* This is atomic on x86_64 so we don't need any locks. */
+ result = ACCESS_ONCE(VVAR(vsyscall_gtod_data).wall_time_sec);
+
+ if (t)
+ *t = result;
+ return result;
+}
+int time(time_t *t)
+ __attribute__((weak, alias("__vdso_time")));