This is the mail archive of the
binutils@sourceware.org
mailing list for the binutils project.
Re: fix frv eh_frame relaxation bug
On May 8, 2007, Alexandre Oliva <aoliva@redhat.com> wrote:
> elf-eh-frame.c removes CIEs that are redundant with previous CIEs, and
> this requires the relocation for __gxx_personality_v0 to be dropped as
> well.
> [...] so this should be good enough.
Famous last words ;-)
The rofixup count must be estimated correctly, and it's no use to make
room for relocations if you're not going to use them after all.
This patch adjusts the rofixup and dynreloc counts after eh_frame
compression, such that we allocate the right sizes, the symbol that
denotes the end of the ROFIXUP section ends up at the right place, and
neither the linker nor run-time crash because the count was wrong.
Index: bfd/ChangeLog
from Alexandre Oliva <aoliva@redhat.com>
* elf32-frv.c (_frvfdpic_check_discarded_relocs): New.
(frvfdpic_elf_discard_info): New.
(elf_backend_discard_info): Define for FDPIC.
Index: bfd/elf32-frv.c
===================================================================
RCS file: /cvs/src/src/bfd/elf32-frv.c,v
retrieving revision 1.53
diff -u -p -r1.53 elf32-frv.c
--- bfd/elf32-frv.c 8 May 2007 06:09:30 -0000 1.53
+++ bfd/elf32-frv.c 10 May 2007 05:13:36 -0000
@@ -5618,6 +5618,122 @@ elf32_frvfdpic_always_size_sections (bfd
return TRUE;
}
+/* Check whether any of the relocations was optimized away, and
+ subtract it from the relocation or fixup count. */
+static bfd_boolean
+_frvfdpic_check_discarded_relocs (bfd *abfd, asection *sec,
+ struct bfd_link_info *info,
+
+ bfd_boolean *changed)
+{
+ Elf_Internal_Shdr *symtab_hdr;
+ struct elf_link_hash_entry **sym_hashes, **sym_hashes_end;
+ Elf_Internal_Rela *rel, *erel;
+
+ if ((sec->flags & SEC_RELOC) == 0
+ || sec->reloc_count == 0)
+ return TRUE;
+
+ symtab_hdr = &elf_tdata (abfd)->symtab_hdr;
+ sym_hashes = elf_sym_hashes (abfd);
+ sym_hashes_end = sym_hashes + symtab_hdr->sh_size/sizeof(Elf32_External_Sym);
+ if (!elf_bad_symtab (abfd))
+ sym_hashes_end -= symtab_hdr->sh_info;
+
+ rel = elf_section_data (sec)->relocs;
+
+ /* Now examine each relocation. */
+ for (erel = rel + sec->reloc_count; rel < erel; rel++)
+ {
+ struct elf_link_hash_entry *h;
+ unsigned long r_symndx;
+ struct frvfdpic_relocs_info *picrel;
+ struct _frvfdpic_dynamic_got_info *dinfo;
+
+ if (ELF32_R_TYPE (rel->r_info) != R_FRV_32
+ && ELF32_R_TYPE (rel->r_info) != R_FRV_FUNCDESC)
+ continue;
+
+ if (_bfd_elf_section_offset (sec->output_section->owner,
+ info, sec, rel->r_offset)
+ != (bfd_vma)-1)
+ continue;
+
+ r_symndx = ELF32_R_SYM (rel->r_info);
+ if (r_symndx < symtab_hdr->sh_info)
+ h = NULL;
+ else
+ {
+ h = sym_hashes[r_symndx - symtab_hdr->sh_info];
+ while (h->root.type == bfd_link_hash_indirect
+ || h->root.type == bfd_link_hash_warning)
+ h = (struct elf_link_hash_entry *)h->root.u.i.link;
+ }
+
+ if (h != NULL)
+ picrel = frvfdpic_relocs_info_for_global (frvfdpic_relocs_info (info),
+ abfd, h,
+ rel->r_addend, NO_INSERT);
+ else
+ picrel = frvfdpic_relocs_info_for_local (frvfdpic_relocs_info (info),
+ abfd, r_symndx,
+ rel->r_addend, NO_INSERT);
+
+ if (! picrel)
+ return FALSE;
+
+ *changed = TRUE;
+ dinfo = frvfdpic_dynamic_got_plt_info (info);
+
+ _frvfdpic_count_relocs_fixups (picrel, dinfo, TRUE);
+ if (ELF32_R_TYPE (rel->r_info) == R_FRV_32)
+ picrel->relocs32--;
+ else /* we know (ELF32_R_TYPE (rel->r_info) == R_FRV_FUNCDESC) */
+ picrel->relocsfd--;
+ _frvfdpic_count_relocs_fixups (picrel, dinfo, FALSE);
+ }
+
+ return TRUE;
+}
+
+static bfd_boolean
+frvfdpic_elf_discard_info (bfd *ibfd,
+ struct elf_reloc_cookie *cookie ATTRIBUTE_UNUSED,
+ struct bfd_link_info *info)
+{
+ bfd_boolean changed = FALSE;
+ asection *s;
+ bfd *obfd = NULL;
+
+ /* Account for relaxation of .eh_frame section. */
+ for (s = ibfd->sections; s; s = s->next)
+ if (s->sec_info_type == ELF_INFO_TYPE_EH_FRAME)
+ {
+ if (!_frvfdpic_check_discarded_relocs (ibfd, s, info, &changed))
+ return FALSE;
+ obfd = s->output_section->owner;
+ }
+
+ if (changed)
+ {
+ struct _frvfdpic_dynamic_got_plt_info gpinfo;
+
+ memset (&gpinfo, 0, sizeof (gpinfo));
+ memcpy (&gpinfo.g, frvfdpic_dynamic_got_plt_info (info),
+ sizeof (gpinfo.g));
+
+ /* Clear GOT and PLT assignments. */
+ htab_traverse (frvfdpic_relocs_info (info),
+ _frvfdpic_reset_got_plt_entries,
+ NULL);
+
+ if (!_frvfdpic_size_got_plt (obfd, &gpinfo))
+ return FALSE;
+ }
+
+ return TRUE;
+}
+
/* Look for opportunities to relax TLS relocations. We can assume
we're linking the main executable or a static-tls library, since
otherwise we wouldn't have got here. */
@@ -6969,6 +7085,9 @@ elf32_frv_grok_psinfo (bfd *abfd, Elf_In
#define elf_backend_finish_dynamic_sections \
elf32_frvfdpic_finish_dynamic_sections
+#undef elf_backend_discard_info
+#define elf_backend_discard_info \
+ frvfdpic_elf_discard_info
#undef elf_backend_can_make_relative_eh_frame
#define elf_backend_can_make_relative_eh_frame \
frvfdpic_elf_use_relative_eh_frame
--
Alexandre Oliva http://www.lsd.ic.unicamp.br/~oliva/
FSF Latin America Board Member http://www.fsfla.org/
Red Hat Compiler Engineer aoliva@{redhat.com, gcc.gnu.org}
Free Software Evangelist oliva@{lsd.ic.unicamp.br, gnu.org}