Hey Andi,
I've not been able to review the new vdso code very carefully yet, but
I noticed one thing right off: the offset calculation is not masked, so
its possible w/ counters less then 64bits wide to have wrapping issues.
It seems something like the following would be needed.
diff --git a/arch/x86_64/vdso/vclock_gettime.c b/arch/x86_64/vdso/vclock_gettime.c
index 17f6a00..9570f8e 100644
--- a/arch/x86_64/vdso/vclock_gettime.c
+++ b/arch/x86_64/vdso/vclock_gettime.c
@@ -36,8 +36,8 @@ static inline long vgetns(void)
{
cycles_t (*vread)(void);
vread = gtod->clock.vread;
- return ((vread() - gtod->clock.cycle_last) * gtod->clock.mult) >>
- gtod->clock.shift;
+ return (((vread() - gtod->clock.cycle_last) & gtod->clock.mask) *
+ gtod->clock.mult) >> gtod->clock.shift;
}
static noinline int do_realtime(struct timespec *ts)
Or am I just missing something?
thanks
-john
-
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