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Re: Preventing preemption of 'protected' symbols in GNU ld 2.26 [aka should we revert the fix for 65248]
- From: Szabolcs Nagy <szabolcs dot nagy at arm dot com>
- To: Richard Biener <richard dot guenther at gmail dot com>, Alan Modra <amodra at gmail dot com>
- Cc: "H.J. Lu" <hjl dot tools at gmail dot com>, Jeff Law <law at redhat dot com>, Cary Coutant <ccoutant at gmail dot com>, Joe Groff <jgroff at apple dot com>, Binutils <binutils at sourceware dot org>, GCC <gcc at gcc dot gnu dot org>, nd <nd at arm dot com>
- Date: Tue, 19 Apr 2016 10:52:47 +0100
- Subject: Re: Preventing preemption of 'protected' symbols in GNU ld 2.26 [aka should we revert the fix for 65248]
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On 19/04/16 09:20, Richard Biener wrote:
> On Tue, Apr 19, 2016 at 7:08 AM, Alan Modra <amodra@gmail.com> wrote:
>> On Mon, Apr 18, 2016 at 07:59:50AM -0700, H.J. Lu wrote:
>>> On Mon, Apr 18, 2016 at 7:49 AM, Alan Modra <amodra@gmail.com> wrote:
>>>> On Mon, Apr 18, 2016 at 11:01:48AM +0200, Richard Biener wrote:
>>>>> To summarize: there is currently no testcase for a wrong-code issue
>>>>> because there is no wrong-code issue.
>>
>> I've added a testcase at
>> https://sourceware.org/bugzilla/show_bug.cgi?id=19965#c3
>> that shows the address problem (&x != x) with older gcc *or* older
>> glibc, and shows the program behaviour problem with current
>> binutils+gcc+glibc.
>
> Thanks.
>
> So with all this it sounds that current protected visibility is just broken
> and we should forgo with it, making it equal to default visibility?
>
the test cases pass for me on musl libc,
it's just a glibc dynamic linker bug
that it does not handle extern protected
visibility correctly.
> At least I couldn't decipher a solution that solves all of the issues
> with protected visibility apart from trying to error at link-time
> (or runtime?) for the cases that are tricky (impossible?) to solve.
>
> glibc uses "protected visibility" via its using of local aliases, correct?
> But it doesn't use anything like that for data symbols?
>
> Richard.
>
>> --
>> Alan Modra
>> Australia Development Lab, IBM
>