Allow copy relocations with pie links

[Alan Modra]

On Thu, May 08, 2014 at 04:29:20PM -0700, Cary Coutant wrote:
> >> I ran the i386 tests. David, Alan, Walt, and Doug, can you help test
> >> this patch on your respective targets?
> >
> > The change isn't appropriate for powerpc.  We don't have pc-relative
> > addressing modes, so must use the GOT in PIEs.
> 
>     case elfcpp::R_PPC64_REL64:
>     case elfcpp::R_POWERPC_REL32:
>       // Make a dynamic relocation if necessary.
>       if (gsym->needs_dynamic_reloc(Scan::get_reference_flags(r_type, target)))
>         {
>           if (gsym->may_need_copy_reloc())
>             {
>               target->copy_reloc(symtab, layout, object,
>                                  data_shndx, output_section, gsym,
>                                  reloc);
>             }
> 
> What should this code do, then? Add a COPY reloc only for
> position-dependent executables?

Yes.  If we're building a PIE then we should be using -fpic/PIC
compiled code and won't have the relocs that would hit this code.  If
we do try to build a PIE with non-PIC code, then we'll get dynamic
relocs in text.  Enabling copy relocs for PIEs would still give
us DT_TEXTREL.  (Of course, ppc64 gcc is PIC by default, so the
foregoing mostly applies to ppc32.)

-- 
Alan Modra
Australia Development Lab, IBM