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Re: Preventing preemption of 'protected' symbols in GNU ld 2.26 [aka should we revert the fix for 65248]
- From: Richard Biener <richard dot guenther at gmail dot com>
- To: 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>
- Date: Tue, 19 Apr 2016 10:20:23 +0200
- Subject: Re: Preventing preemption of 'protected' symbols in GNU ld 2.26 [aka should we revert the fix for 65248]
- Authentication-results: sourceware.org; auth=none
- References: <6AAD87D2-90F9-4AD7-A195-AC91B76EA6AE at apple dot com> <CAMe9rOqNcYnm1YocG-m7XNDE0g68YQAGe=ULP-G98gaatpxSeA at mail dot gmail dot com> <CAJimCsHfT=cfb4kZysB2W_1HFfOq==TpP=wa47XPGB41MHmGyQ at mail dot gmail dot com> <56FB5061 dot 9010303 at redhat dot com> <20160330143421 dot GM15812 at bubble dot grove dot modra dot org> <571161D0 dot 10601 at redhat dot com> <CAMe9rOpt2Fd6RLtjr10wCHz9PVsXxtO9a0yvMR_DeHt1OK0ieg at mail dot gmail dot com> <CAFiYyc2PFQdiUj=UPY8HLv+PjwVaNpcvDW6Skp8JC4DR56MkBg at mail dot gmail dot com> <20160418144911 dot GG15088 at bubble dot grove dot modra dot org> <CAMe9rOog=FJ2Si-mUqHYoOsHVwVFcZavT4X7wQdRjRhbDDWRvQ at mail dot gmail dot com> <20160419050805 dot GI15088 at bubble dot grove dot modra dot org>
On Tue, Apr 19, 2016 at 7:08 AM, Alan Modra <firstname.lastname@example.org> 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 <email@example.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
> that shows the address problem (&x != x) with older gcc *or* older
> glibc, and shows the program behaviour problem with current
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?
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?
> Alan Modra
> Australia Development Lab, IBM