Re: Preventing preemption of 'protected' symbols in GNU ld 2.26 [aka should we revert the fix for 65248]

[Szabolcs Nagy <szabolcs.nagy@arm.com>]

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
>