Fix a bug that arch/x86_64/lib/copy_user:copy_user_generic will return a
wrong value when exception happens.

In the case the address is not 8-byte aligned (i.e.  go into
Lbad_alignment), if exception happens in Ls11, %rdx will be wrong number of
copied bytes, then copy_user_generic returns wrong value.  It also fixed a
bug of zeroing wrong number of bytes of destination at this situation.  (In
Lzero_rest)
Signed-off-by: Yanmin Zhang <yanmin.zhang@intel.com>
Signed-off-by: Nanhai Zou <nanhai.zou@intel.com>
Signed-off-by: Gordon Jin <gordon.jin@intel.com>
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>