Start of relro segment adjustment

[H.J. Lu]

On Wed, Apr 1, 2015 at 2:11 AM, Alan Modra <amodra@gmail.com> wrote:
> Adjusting the start of the relro segment in order to make it end
> exactly on a page boundary runs into difficulties when sections in the
> relro segment are aligned;  Adjusting the start by (next_page - end)
> sometimes results in more than that adjustment occurring at the end,
> overrunning the page boundary.  So when that occurs we try a new lower
> start position by masking the adjusted start with the maximum section
> alignment.  However, we didn't consider that this masked start address
> may in fact be before the initial relro base, which is silly since
> that can only increase padding at the relro end.
>
> I've also moved some calculations closer to where they are used, and
> comments closer to the relevant statements.
>
>         * ldlang.c (lang_size_sections): When alignment of sections
>         results in relro base adjustment being too large, don't go lower
>         than the initial value.
>         * ldexp.c (fold_binary <DATA_SEGMENT_RELRO_END>): Comment.
>         * scripttempl/elf.sc (DATA_SEGMENT_ALIGN): Omit SEGMENT_SIZE
>         alignment when SEGMENT_SIZE is the same as MAXPAGESIZE.
>

Thanks.

I checked in this testcase.


-- 
H.J.
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