Preventing preemption of 'protected' symbols in GNU ld 2.26

[Jeff Law]

On 03/30/2016 06:40 PM, Cary Coutant wrote:
>> It would help me immensely on the GCC side if things if you and Alan could
>> easily summarize correct behavior and the impact if we were to just revert
>> HJ's change.  A testcase would be amazingly helpful too.
>
> It looks like it's not just the one change. There's this patch:
>
>     https://gcc.gnu.org/ml/gcc-patches/2015-07/msg01871.html
>
> which took the idea that protected can still be pre-empted by a COPY
> relocation and extended it to three more targets that use COPY
> relocations.
>
> I wonder how many other patches have been based on the same misunderstanding?
The patches around BZ65780 may be tangled in this mess as well.    And 
it bled into the s390 & darwin ports as well.

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65780

Alan, could you take a peek at 65780 -- you're better versed than I in 
this stuff.  Essentially the question that needs to be answered is if we 
roll back 65280, do we need to also roll back 65780?

jeff