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")));