[PATCH] time: Fix casting issue in timekeeping_forward_now

[Andreas Schwab <schwab@linux-m68k.org>]

arch_gettimeoffset returns a u32 value which when shifted by tk->shift can
overflow.  Cast it to u64 first.

Signed-off-by: Andreas Schwab <schwab@linux-m68k.org>
---
Found this by inspection, I don't know if any existing users of
ARCH_USES_GETTIMEOFFSET are affected.  In other words, this is untested,
but looks pretty obvious.

Can tk->shift be bigger than 30?  If so then the shifts in
update_wall_time need to be adjusted as well.

Andreas.

---
 kernel/time/timekeeping.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index e16af19..8776d66 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -276,7 +276,7 @@ static void timekeeping_forward_now(struct timekeeper *tk)
 	tk->xtime_nsec += cycle_delta * tk->mult;
 
 	/* If arch requires, add in gettimeoffset() */
-	tk->xtime_nsec += arch_gettimeoffset() << tk->shift;
+	tk->xtime_nsec += (u64)arch_gettimeoffset() << tk->shift;
 
 	tk_normalize_xtime(tk);
 
-- 
1.7.11.5

-- 
Andreas Schwab, schwab@linux-m68k.org
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