[RFC -tip 0/4] x86: reduce fixup of uaccess

[Hiroshi Shimamoto <h-shimamoto@ct.jp.nec.com>]

This is my second try to reduce fixup code size for exceptions of uaccess.

This patch series reduces fixup code for exceptions of uaccess in signal.

I gave up to make direct jump to end of function when an exception occurs.
However, I thought fixup code could be reduced. The concept is that to add
uaccess_err in thread_info and set it to -EFAULT on exception, finally check
this value on the last of function.

Is this good to reduce code size?

The code size reductions are below;
$ size *signal*.o.*
   text	   data	    bss	    dec	    hex	filename
   4741	      0	      0	   4741	   1285	ia32_signal.o.new
   6006	      0	      0	   6006	   1776	ia32_signal.o.old
   3577	      0	      0	   3577	    df9	signal.o.new
   4540	      0	      0	   4540	   11bc	signal.o.old
   3855	      0	      0	   3855	    f0f	signal32.o.new
   4876	      0	      0	   4876	   130c	signal32.o.old

Thanks,
Hiroshi