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Date: Wed, 5 Nov 2014 15:19:39 +0200
From: Konstantin Belousov <kostikbel@gmail.com>
To: Shawn Webb <lattera@gmail.com>
Subject: Re: PIE/PIC support on base
Message-ID: <20141105131939.GF53947@kib.kiev.ua>
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Cc: Baptiste Daroussin <bapt@FreeBSD.org>,
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On Wed, Nov 05, 2014 at 07:59:21AM -0500, Shawn Webb wrote:
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA512
> 
> 
> 
> On November 5, 2014 7:26:12 AM EST, Konstantin Belousov <kostikbel@gmail.com> wrote:
> >On Wed, Nov 05, 2014 at 12:48:55PM +0100, Baptiste Daroussin wrote:
> >> > Also, I strongly oppose compiling everything with PIC, even on
> >amd64.
> >> > I described somewhere else that using PIC code changes symbol
> >lookup
> >> > rules for binaries.  So despite not having performance impact, the
> >> > thing does impact runtime behaviour in subtle ways.  The most
> >affected
> >> > programs are those which support dynamic modules.
> >Please do not ignore this ^^^^^^ issue.
> >
> 
> Can you go into detail what those changes are?
PIE binary resolves its symbols through GOT/PLT.
In particular, it is possible to interpose the symbols.