time: Fix casting issue in tk_set_xtime and tk_xtime_add

commit 1e75fa8b (time: Condense timekeeper.xtime into xtime_sec)
introduced helper functions which apply a timespec to the core
internal timekeeper data. The internal storage type is u64. The
timespec tv_nsec value must be shifted before set or added to the
internal value. tv_nsec is a long, which is 32bit on a 32bit system,
so without casting tv_nsec to u64 we lose the bits which are shifted
over the 32bit boundary.

Add the proper typecasts.

Reported-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Tested-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Acked-by: Prarit Bhargava <prarit@redhat.com>
Link: http://lkml.kernel.org/r/1343074957-16541-1-git-send-email-john.stultz@linaro.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

kernel/time/timekeeping.c

@@ -108,13 +108,13 @@ static struct timespec tk_xtime(struct timekeeper *tk)
 static void tk_set_xtime(struct timekeeper *tk, const struct timespec *ts)
 {
 	tk->xtime_sec = ts->tv_sec;
-	tk->xtime_nsec = ts->tv_nsec << tk->shift;
+	tk->xtime_nsec = (u64)ts->tv_nsec << tk->shift;
 }
 
 static void tk_xtime_add(struct timekeeper *tk, const struct timespec *ts)
 {
 	tk->xtime_sec += ts->tv_sec;
-	tk->xtime_nsec += ts->tv_nsec << tk->shift;
+	tk->xtime_nsec += (u64)ts->tv_nsec << tk->shift;
 }
 
 /**