The size of tlb_table is 4k on a 64-bit host.  For overwriting
memory at this size, cacheline tricks can help.

Signed-off-by: Richard Henderson <rth@twiddle.net>
Reviewed-by: Aurelien Jarno <aurelien@aurel32.net>
Signed-off-by: Andreas Färber <afaerber@suse.de>