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Date: Thu, 24 Mar 2016 16:42:00 -0000
Message-ID: <CAMe9rOphSdEp8mO7OpuEAVpUz-hT8eRb=6RJmaP1XWvDC_UNpQ@mail.gmail.com>
Subject: Re: Preventing preemption of 'protected' symbols in GNU ld 2.26
From: "H.J. Lu" <hjl.tools@gmail.com>
To: Cary Coutant <ccoutant@gmail.com>
Cc: Joe Groff <jgroff@apple.com>, Binutils <binutils@sourceware.org>
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On Thu, Mar 24, 2016 at 9:06 AM, Cary Coutant <ccoutant@gmail.com> wrote:
>> I disagree.  Protected means that it won't be preempted.  It
>> doesn't mean the address of protected symbol will be local.
>> With copy relocation, the run-time address of the protected
>> symbol can be in executable.  There are a couple run-time
>> tests in glibc to verify it.  See:
>>
>> https://sourceware.org/bugzilla/show_bug.cgi?id=17711
>
> No. You can't just redefine away the meaning of "must resolve to a
> definition in that component." A COPY relocation makes a new
> definition in the main program and that new definition pre-empts the
> one in the shared library. That breaks everything that the rule in the
> gABI was designed to allow.
>

What you are proposing is to disallow copy relocation against
protected symbol.  Am I correct?


-- 
H.J.