[PATCH 3/3] csu: Move static pie self relocation later [BZ #27072]

[H.J. Lu]

On Thu, Jan 7, 2021 at 4:46 AM Carlos O'Donell <carlos@redhat.com> wrote:
>
> On 1/7/21 7:36 AM, H.J. Lu via Libc-alpha wrote:
> > On Thu, Jan 7, 2021 at 3:04 AM Szabolcs Nagy via Libc-alpha
> > <libc-alpha@sourceware.org> wrote:
> >>
> >> On targets where hidden symbol access does not need RELATIVE
> >> relocs, move the static pie self relocation after tunables and
> >> cpu features are set up.  This allows processing IRELATIVE
> >> relocs with correct ifunc dispatch logic.
> >>
> >> Unfortunately it is hard to guarantee that there will be no
> >> dynamic relocations in the early start up code, so this is a
> >> bit fragile. Ideally the RELATIVE relocs would be processed as
> >> early as possible and IRELATIVE relocs after cpu features are
> >> setup, but in glibc it is hard to separate them into two steps.
> >
> > x86 linker places IRELATIVE relocations the last:
> >
> > https://sourceware.org/bugzilla/show_bug.cgi?id=13302
> >
> > Does your linker have this bug fixed?
>
> Agreed, this is something I asked about during the design of
> IFUNCs and I was told by Ulrich and others that IRELATIVE has
> to be placed in a group and after RELATIVE relocs.

Not just before RELATIVE.   IRELATIVE should be processed the
last before all other relocations.   See PR 13302 for other cases.

-- 
H.J.