Re: [PATCH] search_one_table()

[Brian Gerst]

Per Persson wrote:
> 
> I found that gcc doesn't manage to do this rewrite itself. My micro-patch
> saves a few bytes. Also the code becomes a little bit cleaner (IMHO).
> 
> Probably the same change could (and should) be made for the other
> architectures too.
> 
> Per Persson
> [e-mail]
> 
> --- arch/i386/mm/extable.c.orig Mon Nov 12 00:13:52 2001
> +++ arch/i386/mm/extable.c      Tue Nov 13 17:39:42 2001
> @@ -19,7 +19,7 @@
>                 const struct exception_table_entry *mid;
>                 long diff;
> 
> -               mid = (last - first) / 2 + first;
> +               mid = (last + first) / 2
>                 diff = mid->insn - value;
>                  if (diff == 0)
>                          return mid->fixup;
> 

This change will not work because of lost high bits due to overflow. 
Remember that kernel addresses are in the 0xc0000000-0xffffffff range.

--

				Brian Gerst