x86_64: Add missing mask operation to vdso
vdso vgetns() didn't mask the time source offset calculation, which
could lead to time problems with 32bit HPET. Add the masking.
Thanks to Chuck Ebbert for tracking this down.
Signed-off-by: Andi Kleen <ak@suse.de>
Cc: Chuck Ebbert <cebbert@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/arch/x86_64/vdso/vclock_gettime.c b/arch/x86_64/vdso/vclock_gettime.c
index 17f6a00..5b54cdf 100644
--- a/arch/x86_64/vdso/vclock_gettime.c
+++ b/arch/x86_64/vdso/vclock_gettime.c
@@ -34,10 +34,11 @@
static inline long vgetns(void)
{
+ long v;
cycles_t (*vread)(void);
vread = gtod->clock.vread;
- return ((vread() - gtod->clock.cycle_last) * gtod->clock.mult) >>
- gtod->clock.shift;
+ v = (vread() - gtod->clock.cycle_last) & gtod->clock.mask;
+ return (v * gtod->clock.mult) >> gtod->clock.shift;
}
static noinline int do_realtime(struct timespec *ts)