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Re: [PATCH] PR ld/21402: Skip PIE indirect5 and indirect6 tests on i386
- From: Alan Modra <amodra at gmail dot com>
- To: "H.J. Lu" <hjl dot tools at gmail dot com>
- Cc: Binutils <binutils at sourceware dot org>
- Date: Mon, 24 Apr 2017 13:39:44 +0930
- Subject: Re: [PATCH] PR ld/21402: Skip PIE indirect5 and indirect6 tests on i386
- Authentication-results: sourceware.org; auth=none
- References: <20170420194144.GA12307@intel.com> <20170421010858.GC24006@bubble.grove.modra.org> <CAMe9rOq8vovS22M-ogDSF7rVg6Th-3iyXV1==kZDXyEU0sNjOw@mail.gmail.com>
On Fri, Apr 21, 2017 at 11:37:34AM -0700, H.J. Lu wrote:
> @@ -2863,10 +2867,14 @@ elf_i386_allocate_dynrelocs (struct elf_link_hash_entry *h, void *inf)
> int tls_type = elf_i386_hash_entry(h)->tls_type;
>
> /* Make sure this symbol is output as a dynamic symbol.
> - Undefined weak syms won't yet be marked as dynamic. */
> + Undefined weak syms won't yet be marked as dynamic.
> + PR ld/21402: If this symbol isn't undefined weak symbol,
> + don't make it dynamic in PIE. */
> if (h->dynindx == -1
> && !h->forced_local
> - && !resolved_to_zero)
> + && !resolved_to_zero
> + && (h->root.type == bfd_link_hash_undefweak
> + || !bfd_link_pie (info)))
> {
> if (! bfd_elf_link_record_dynamic_symbol (info, h))
> return FALSE;
This doesn't look correct to me. Sure, it fixes the particular
testcase, but why do you make non-pie non-undefweak symbols dynamic
here? I believe that only undefweak symbols should be made dynamic
here, and in all the other places in allocate_dynrelocs.
x86_64 too, but fixing allocate_dynrelocs for x86_64 causes no-plt-1e
to fail due to lack of a relative GOT dynamic reloc on
cmpq func@GOTPCREL(%rip), %rax
in no-plt-check1.S. Seems like x86_64 would need something like your
change to elf32-i386.c to emit relative GOT dynamic relocs in
relocate_section. (For powerpc I decided to only handle plt and copy
relocs in finish_dynamic_symbol. GOT dynamic relocs are all handled
in relocate_section as otherwise there is a lot of duplication and IMO
less comprehensible code.)
> @@ -3818,6 +3826,7 @@ elf_i386_relocate_section (bfd *output_bfd,
> bfd_vma st_size;
> asection *resolved_plt;
> bfd_boolean resolved_to_zero;
> + bfd_boolean relative_reloc;
>
> r_type = ELF32_R_TYPE (rel->r_info);
> if (r_type == R_386_GNU_VTINHERIT
> @@ -4268,6 +4277,7 @@ r_386_got32:
> if (htab->elf.sgot == NULL)
> abort ();
>
> + relative_reloc = FALSE;
> if (h != NULL)
> {
> bfd_boolean dyn;
> @@ -4301,6 +4311,17 @@ r_386_got32:
> bfd_put_32 (output_bfd, relocation,
> htab->elf.sgot->contents + off);
> h->got.offset |= 1;
> +
> + if (h->dynindx == -1
> + && !h->forced_local
> + && h->root.type != bfd_link_hash_undefweak
> + && bfd_link_pie (info))
> + {
> + /* PR ld/21402: If this symbol isn't dynamic
> + in PIE, generate R_386_RELATIVE here. */
> + eh->no_finish_dynamic_symbol = 1;
> + relative_reloc = TRUE;
> + }
> }
> }
> else
This also looks odd. Surely you need a relative reloc when pic, not
pie? It seems to me you need one any time you won't be calling
finish_dynamic_symbol (which is where x86 sets most dynamic GOT
relocs) and have a symbol that doesn't resolve to zero.
--
Alan Modra
Australia Development Lab, IBM