We were missing __volatile__ on some bits of asm in the segfault handlers.
On x86_64, this was messing up the move from %rdx to uc because that was
moved to after the GET_FAULTINFO_FROM_SC, which changed %rdx.

Also changed the other bit of asm and the one in the i386 handler to
prevent any similar occurrences.
Signed-off-by: NJeff Dike <jdike@addtoit.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>