Fix hppa/ia64/microblaze executable stack default (bug 22156)

[Carlos O'Donell]

On 09/19/2017 07:46 AM, Joseph Myers wrote:
> As per https://gcc.gnu.org/ml/gcc-patches/2017-09/msg01220.html hppa,
> ia64 and microblaze default to non-executable stacks in the Linux
> kernel.  glibc however defines DEFAULT_STACK_PERMS to include PF_X for
> those architectures, meaning (a) elf/check-execstack fails and (b)
> (from code inspection, not tested, but this is why I think this is a
> user-visible bug) thread stacks are unnecessarily mapped with execute
> permission.  This patch fixes the DEFAULT_STACK_PERMS definitions in
> question.
> 
> Tested (compilation only) with build-many-glibcs.py for those
> configurations.  This fixes the check-execstack failure (hppa still
> has a check-textrel failure as the only remaining issue stopping that
> architecture having clean build-many-glibcs.py results; hopefully
> architecture maintainers can help resolve that).

I thought that PF_X was required for hppa because there was still code
generated by gcc for hppa that needed it? Otherwise *I* would have
removed it when I did the PT_GNU_STACK cleanups for all the arches.

Dave is the best positioned to answer this question.

-- 
Cheers,
Carlos.