2 files changed, 11 insertions, 0 deletions

diff --git a/include/linux/clocksource.h b/include/linux/clocksource.h
index 830a250ecf94..daa4940cc0f1 100644
--- a/include/linux/clocksource.h
+++ b/include/linux/clocksource.h
@@ -47,6 +47,7 @@ struct clocksource;
  * @mult:               cycle to nanosecond multiplier
  * @shift:              cycle to nanosecond divisor (power of two)
  * @flags:              flags describing special properties
+ * @vread:              vsyscall based read
  * @cycle_interval:     Used internally by timekeeping core, please ignore.
  * @xtime_interval:     Used internally by timekeeping core, please ignore.
  */
@@ -59,6 +60,7 @@ struct clocksource {
         u32 mult;
         u32 shift;
         unsigned long flags;
+        cycle_t (*vread)(void);
 
         /* timekeeping specific data, ignore */
         cycle_t cycle_last, cycle_interval;
@@ -197,4 +199,12 @@ extern int clocksource_register(struct clocksource*);
 extern struct clocksource* clocksource_get_next(void);
 extern void clocksource_change_rating(struct clocksource *cs, int rating);
 
+#ifdef CONFIG_GENERIC_TIME_VSYSCALL
+extern void update_vsyscall(struct timespec *ts, struct clocksource *c);
+#else
+static inline void update_vsyscall(struct timespec *ts, struct clocksource *c)
+{
+}
+#endif
+
 #endif /* _LINUX_CLOCKSOURCE_H */
diff --git a/kernel/timer.c b/kernel/timer.c
index c3c67f3c0190..cb1b86a9c52f 100644
--- a/kernel/timer.c
+++ b/kernel/timer.c
@@ -1174,6 +1174,7 @@ static void update_wall_time(void)
 
         /* check to see if there is a new clocksource to use */
         change_clocksource();
+        update_vsyscall(&xtime, clock);
 }
 
 /*