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Re: [PATCH] Reduce file size for PT_GNU_RELRO segment
- From: "H.J. Lu" <hjl dot tools at gmail dot com>
- To: Binutils <binutils at sourceware dot org>
- Date: Mon, 30 Mar 2015 06:00:20 -0700
- Subject: Re: [PATCH] Reduce file size for PT_GNU_RELRO segment
- Authentication-results: sourceware.org; auth=none
- References: <20150319130244 dot GA22592 at intel dot com> <20150326022246 dot GU26234 at bubble dot grove dot modra dot org> <CAMe9rOrVpthhMfZEXcMkKzmHcxymfQHKuTuZPi_y36=s6KJ9iA at mail dot gmail dot com> <20150328041540 dot GE26234 at bubble dot grove dot modra dot org> <CAMe9rOoVzbOvdE1_apgUbHtm0gG89d3_9qbnA8=Y3Qu9MznUPA at mail dot gmail dot com> <CAMe9rOp8sdCbOp0eVzRmwMhe_3c2K0EJ6fmnMMWyA01KYamzLw at mail dot gmail dot com> <20150329034858 dot GH26234 at bubble dot grove dot modra dot org> <CAMe9rOrJB7xNLn4FEq5+N8VbnfZuYxkM4tPNMQzOKapVheGOpQ at mail dot gmail dot com> <20150330123934 dot GJ26234 at bubble dot grove dot modra dot org>
On Mon, Mar 30, 2015 at 5:39 AM, Alan Modra <amodra@gmail.com> wrote:
> On Sun, Mar 29, 2015 at 06:58:45AM -0700, H.J. Lu wrote:
>> On Sat, Mar 28, 2015 at 8:48 PM, Alan Modra <amodra@gmail.com> wrote:
>> > lang_size_sections). I think it important that we keep the relro base
>> > alignment code all in one place.
>>
>> It is not about the base alignment. It is about setting the address of
>> the first section in PT_GNU_RELRO segment, given the addresses
>> of PT_GNU_RELRO segment. It is impossible to set address of the first
>> section in PT_GNU_RELRO segment from lang_size_sections.
>
> Look again at the code for exp_dataseg_relro_adjust. If you change
> expld.dataseg.base there you will change addresses of sections in the
> relro segment.
But I don't want to change expld.dataseg.base. I just want to
bump the address of the first section a bit. Currently I have
bfd_vma pad
= ((newdot - expld.dataseg.min_base)
% expld.dataseg.maxpagesize);
if (pad)
{
bfd_vma nextdot
= expld.dataseg.maxpagesize - pad;
nextdot = align_power (newdot + nextdot,
section_alignment);
if (((nextdot - newdot)
< expld.dataseg.pagesize)
&& pad > (expld.dataseg.maxpagesize
- expld.dataseg.pagesize))
newdot = nextdot;
}
I can keep the address increase, nextdot - newdot, even lower
than the page size.
--
H.J.