2 files changed, 36 insertions, 1 deletions

diff --git a/arch/x86/vdso/vclock_gettime.c b/arch/x86/vdso/vclock_gettime.c
index 28b2c00bd1be..e6e9f90a8cd7 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.
@@ -160,3 +160,36 @@ 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)
+{
+        unsigned seq;
+        time_t result;
+        if (unlikely(!VVAR(vsyscall_gtod_data).sysctl_enabled))
+                return time_syscall(t);
+
+        do {
+                seq = read_seqbegin(&VVAR(vsyscall_gtod_data).lock);
+
+                result = VVAR(vsyscall_gtod_data).wall_time_sec;
+
+        } while (read_seqretry(&VVAR(vsyscall_gtod_data).lock, seq));
+
+        if (t)
+                *t = result;
+        return result;
+}
+int time(time_t *t)
+        __attribute__((weak, alias("__vdso_time")));
diff --git a/arch/x86/vdso/vdso.lds.S b/arch/x86/vdso/vdso.lds.S
index 81f250011f71..b96b2677cad8 100644
--- a/arch/x86/vdso/vdso.lds.S
+++ b/arch/x86/vdso/vdso.lds.S
@@ -23,6 +23,8 @@ VERSION {
                 __vdso_gettimeofday;
                 getcpu;
                 __vdso_getcpu;
+                time;
+                __vdso_time;
         local: *;
         };
 }