x86, vdso, time: Cast tv_nsec to u64 for proper shifting in update_vsyscall()

With tk->wall_to_monotonic.tv_nsec being a 32-bit value on 32-bit
systems, (tk->wall_to_monotonic.tv_nsec << tk->shift) in update_vsyscall()
may lose upper bits or, worse, add them since compiler will do this:
	(u64)(tk->wall_to_monotonic.tv_nsec << tk->shift)
instead of
	((u64)tk->wall_to_monotonic.tv_nsec << tk->shift)

So if, for example, tv_nsec is 0x800000 and shift is 8 we will end up
with 0xffffffff80000000 instead of 0x80000000. And then we are stuck in
the subsequent 'while' loop.

We need an explicit cast.

Signed-off-by: Boris Ostrovsky <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Acked-by: Konrad Rzeszutek Wilk <[email protected]>
Cc: <[email protected]> # v3.14
Signed-off-by: H. Peter Anvin <[email protected]>

0 files changed, 0 insertions, 0 deletions