Only the low 32 bits of orig_ax are meaningful
for obtaining syscall number so we need to test
if sign extended bits are greater than 0.
Reported-by: Kir Kolyshkin <kir@openvz.org>
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Acked-by: Pavel Emelyanov <xemul@parallels.com>