PowerPC64 ELFv2 symbols defined in plt
In a non-pic executable, ELFv2 like other targets, needs to emit a plt entry even for non-call references to functions defined in shared libraries, and define the function on the plt code. * elf64-ppc.c (ppc64_elf_copy_indirect_symbol): Copy pointer_equality_needed flag. (ppc64_elf_check_relocs): For ELFv2 arrange to emit plt entries for references to functions in shared libraries on non-call relocs. (readonly_dynrelocs): Split into function of the same name and.. (maybe_set_textrel): ..this new function. Update call. (ppc64_elf_adjust_dynamic_symbol): Don't emit dynrelocs for ELFv2 in most cases if we have a plt entry. Use new readonly_relocs. (allocate_dynrelocs): For ELFv2, don't allocate dynreloc space for ifunc in static executables. (size_global_entry_stubs): New function. (ppc64_elf_size_dynamic_sections): Call size_global_entry_stubs. Save end of glink branch table. (ppc64_elf_hash_symbol): New function. (build_global_entry_stubs): New function. (ppc64_elf_build_stubs): Call build_global_entry_stubs. Adjust glink sizing. (ppc64_elf_relocate_section): Tidy plt16/32/64 reloc code. (ppc64_elf_finish_dynamic_symbol): For ELFv2, adjust symbols defined on plt code.
This commit is contained in:
parent
4115bfc683
commit
a345bc8d31
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@ -1,3 +1,28 @@
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2013-11-04 Alan Modra <amodra@gmail.com>
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* elf64-ppc.c (ppc64_elf_copy_indirect_symbol): Copy
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pointer_equality_needed flag.
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(ppc64_elf_check_relocs): For ELFv2 arrange to emit plt
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entries for references to functions in shared libraries on
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non-call relocs.
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(readonly_dynrelocs): Split into function of the same name and..
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(maybe_set_textrel): ..this new function. Update call.
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(ppc64_elf_adjust_dynamic_symbol): Don't emit dynrelocs for
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ELFv2 in most cases if we have a plt entry. Use new
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readonly_relocs.
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(allocate_dynrelocs): For ELFv2, don't allocate dynreloc space
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for ifunc in static executables.
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(size_global_entry_stubs): New function.
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(ppc64_elf_size_dynamic_sections): Call size_global_entry_stubs.
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Save end of glink branch table.
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(ppc64_elf_hash_symbol): New function.
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(build_global_entry_stubs): New function.
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(ppc64_elf_build_stubs): Call build_global_entry_stubs. Adjust
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glink sizing.
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(ppc64_elf_relocate_section): Tidy plt16/32/64 reloc code.
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(ppc64_elf_finish_dynamic_symbol): For ELFv2, adjust symbols
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defined on plt code.
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2013-11-02 Alan Modra <amodra@gmail.com>
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* opncls.c (_bfd_new_bfd): Don't init vars already zeroed.
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283
bfd/elf64-ppc.c
283
bfd/elf64-ppc.c
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@ -109,6 +109,7 @@ static bfd_vma opd_entry_value
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#define elf_backend_maybe_function_sym ppc64_elf_maybe_function_sym
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#define elf_backend_always_size_sections ppc64_elf_func_desc_adjust
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#define elf_backend_size_dynamic_sections ppc64_elf_size_dynamic_sections
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#define elf_backend_hash_symbol ppc64_elf_hash_symbol
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#define elf_backend_init_index_section _bfd_elf_init_2_index_sections
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#define elf_backend_action_discarded ppc64_elf_action_discarded
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#define elf_backend_relocate_section ppc64_elf_relocate_section
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@ -174,6 +175,9 @@ static bfd_vma opd_entry_value
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#define LD_R2_0R1 0xe8410000 /* ld %r2,0(%r1) */
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#define ADDIS_R12_R12 0x3d8c0000 /* addis %r12,%r12,xxx@ha */
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#define LD_R12_0R12 0xe98c0000 /* ld %r12,xxx@l(%r12) */
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/* glink call stub instructions. We enter with the index in R0. */
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#define GLINK_CALL_STUB_SIZE (16*4)
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/* 0: */
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@ -4623,6 +4627,7 @@ ppc64_elf_copy_indirect_symbol (struct bfd_link_info *info,
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edir->elf.ref_regular |= eind->elf.ref_regular;
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edir->elf.ref_regular_nonweak |= eind->elf.ref_regular_nonweak;
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edir->elf.needs_plt |= eind->elf.needs_plt;
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edir->elf.pointer_equality_needed |= eind->elf.pointer_equality_needed;
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/* Copy over any dynamic relocs we may have on the indirect sym. */
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if (eind->dyn_relocs != NULL)
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@ -5352,6 +5357,14 @@ ppc64_elf_check_relocs (bfd *abfd, struct bfd_link_info *info,
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if (!update_local_sym_info (abfd, symtab_hdr, r_symndx,
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rel->r_addend, tls_type))
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return FALSE;
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/* We may also need a plt entry if the symbol turns out to be
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an ifunc. */
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if (h != NULL && !info->shared && abiversion (abfd) == 2)
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{
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if (!update_plt_info (abfd, &h->plt.plist, rel->r_addend))
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return FALSE;
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}
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break;
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case R_PPC64_PLT16_HA:
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@ -5604,12 +5617,6 @@ ppc64_elf_check_relocs (bfd *abfd, struct bfd_link_info *info,
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}
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/* Fall through. */
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case R_PPC64_REL30:
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case R_PPC64_REL32:
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case R_PPC64_REL64:
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case R_PPC64_ADDR14:
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case R_PPC64_ADDR14_BRNTAKEN:
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case R_PPC64_ADDR14_BRTAKEN:
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case R_PPC64_ADDR16:
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case R_PPC64_ADDR16_DS:
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case R_PPC64_ADDR16_HA:
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case R_PPC64_ADDR16_HIGHESTA:
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case R_PPC64_ADDR16_LO:
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case R_PPC64_ADDR16_LO_DS:
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if (h != NULL && !info->shared && abiversion (abfd) == 2
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&& rel->r_addend == 0)
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{
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/* We may need a .plt entry if this reloc refers to a
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function in a shared lib. */
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if (!update_plt_info (abfd, &h->plt.plist, rel->r_addend))
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return FALSE;
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h->pointer_equality_needed = 1;
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}
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/* Fall through. */
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case R_PPC64_REL30:
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case R_PPC64_REL32:
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case R_PPC64_REL64:
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case R_PPC64_ADDR14:
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case R_PPC64_ADDR14_BRNTAKEN:
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case R_PPC64_ADDR14_BRTAKEN:
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case R_PPC64_ADDR24:
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case R_PPC64_ADDR32:
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case R_PPC64_UADDR16:
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@ -6850,6 +6874,25 @@ ppc64_elf_func_desc_adjust (bfd *obfd ATTRIBUTE_UNUSED,
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return TRUE;
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}
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/* Return true if we have dynamic relocs that apply to read-only sections. */
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static bfd_boolean
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readonly_dynrelocs (struct elf_link_hash_entry *h)
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{
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struct ppc_link_hash_entry *eh;
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struct elf_dyn_relocs *p;
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eh = (struct ppc_link_hash_entry *) h;
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for (p = eh->dyn_relocs; p != NULL; p = p->next)
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{
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asection *s = p->sec->output_section;
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if (s != NULL && (s->flags & SEC_READONLY) != 0)
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return TRUE;
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}
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return FALSE;
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}
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/* Adjust a symbol defined by a dynamic object and referenced by a
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regular object. The current definition is in some section of the
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dynamic object, but we're not including those sections. We have to
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h->plt.plist = NULL;
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h->needs_plt = 0;
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}
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else if (abiversion (info->output_bfd) == 2)
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{
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/* After adjust_dynamic_symbol, non_got_ref set in the
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non-shared case means that we have allocated space in
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.dynbss for the symbol and thus dyn_relocs for this
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symbol should be discarded.
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If we get here we know we are making a PLT entry for this
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symbol, and in an executable we'd normally resolve
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relocations against this symbol to the PLT entry. Allow
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dynamic relocs if the reference is weak, and the dynamic
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relocs will not cause text relocation. */
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if (!h->ref_regular_nonweak
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&& h->non_got_ref
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&& h->type != STT_GNU_IFUNC
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&& !readonly_dynrelocs (h))
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h->non_got_ref = 0;
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/* If making a plt entry, then we don't need copy relocs. */
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return TRUE;
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}
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}
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else
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h->plt.plist = NULL;
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@ -6921,27 +6984,13 @@ ppc64_elf_adjust_dynamic_symbol (struct bfd_link_info *info,
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if (!h->def_dynamic || !h->ref_regular || h->def_regular)
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return TRUE;
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if (ELIMINATE_COPY_RELOCS)
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{
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struct ppc_link_hash_entry * eh;
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struct elf_dyn_relocs *p;
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eh = (struct ppc_link_hash_entry *) h;
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for (p = eh->dyn_relocs; p != NULL; p = p->next)
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{
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s = p->sec->output_section;
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if (s != NULL && (s->flags & SEC_READONLY) != 0)
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break;
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}
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/* If we didn't find any dynamic relocs in read-only sections, then
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we'll be keeping the dynamic relocs and avoiding the copy reloc. */
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if (p == NULL)
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if (ELIMINATE_COPY_RELOCS && !readonly_dynrelocs (h))
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{
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h->non_got_ref = 0;
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return TRUE;
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}
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}
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if (h->plt.plist != NULL)
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{
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@ -9373,7 +9422,8 @@ allocate_dynrelocs (struct elf_link_hash_entry *h, void *inf)
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if (eh->dyn_relocs == NULL
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|| (!htab->elf.dynamic_sections_created
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&& h->type != STT_GNU_IFUNC))
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&& (h->type != STT_GNU_IFUNC
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|| !htab->opd_abi)))
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return TRUE;
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/* In the shared -Bsymbolic case, discard space allocated for
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return TRUE;
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}
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/* Find any dynamic relocs that apply to read-only sections. */
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/* Called via elf_link_hash_traverse from ppc64_elf_size_dynamic_sections
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to set up space for global entry stubs. These are put in glink,
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after the branch table. */
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static bfd_boolean
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readonly_dynrelocs (struct elf_link_hash_entry *h, void *inf)
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size_global_entry_stubs (struct elf_link_hash_entry *h, void *inf)
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{
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struct ppc_link_hash_entry *eh;
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struct elf_dyn_relocs *p;
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struct bfd_link_info *info;
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struct ppc_link_hash_table *htab;
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struct plt_entry *pent;
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asection *s;
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eh = (struct ppc_link_hash_entry *) h;
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for (p = eh->dyn_relocs; p != NULL; p = p->next)
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if (h->root.type == bfd_link_hash_indirect)
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return TRUE;
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if (!h->pointer_equality_needed)
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return TRUE;
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if (h->def_regular)
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return TRUE;
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info = inf;
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htab = ppc_hash_table (info);
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if (htab == NULL)
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return FALSE;
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s = htab->glink;
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for (pent = h->plt.plist; pent != NULL; pent = pent->next)
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if (pent->plt.offset != (bfd_vma) -1
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&& pent->addend == 0)
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{
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asection *s = p->sec->output_section;
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s->size = (s->size + 15) & -16;
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s->size += 16;
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break;
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}
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return TRUE;
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}
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if (s != NULL && (s->flags & SEC_READONLY) != 0)
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/* Set DF_TEXTREL if we find any dynamic relocs that apply to
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read-only sections. */
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static bfd_boolean
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maybe_set_textrel (struct elf_link_hash_entry *h, void *info)
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{
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struct bfd_link_info *info = inf;
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if (h->root.type == bfd_link_hash_indirect)
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return TRUE;
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info->flags |= DF_TEXTREL;
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if (readonly_dynrelocs (h))
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{
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((struct bfd_link_info *) info)->flags |= DF_TEXTREL;
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/* Not an error, just cut short the traversal. */
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return FALSE;
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}
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}
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return TRUE;
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}
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@ -9645,6 +9726,12 @@ ppc64_elf_size_dynamic_sections (bfd *output_bfd,
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/* Allocate global sym .plt and .got entries, and space for global
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sym dynamic relocs. */
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elf_link_hash_traverse (&htab->elf, allocate_dynrelocs, info);
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/* Stash the end of glink branch table. */
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if (htab->glink != NULL)
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htab->glink->rawsize = htab->glink->size;
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if (!htab->opd_abi && !info->shared)
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elf_link_hash_traverse (&htab->elf, size_global_entry_stubs, info);
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first_tlsld = NULL;
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for (ibfd = info->input_bfds; ibfd != NULL; ibfd = ibfd->link_next)
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@ -9842,7 +9929,7 @@ ppc64_elf_size_dynamic_sections (bfd *output_bfd,
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/* If any dynamic relocs apply to a read-only section,
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then we need a DT_TEXTREL entry. */
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if ((info->flags & DF_TEXTREL) == 0)
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elf_link_hash_traverse (&htab->elf, readonly_dynrelocs, info);
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elf_link_hash_traverse (&htab->elf, maybe_set_textrel, info);
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if ((info->flags & DF_TEXTREL) != 0)
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{
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@ -9856,6 +9943,19 @@ ppc64_elf_size_dynamic_sections (bfd *output_bfd,
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return TRUE;
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}
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/* Return TRUE if symbol should be hashed in the `.gnu.hash' section. */
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static bfd_boolean
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ppc64_elf_hash_symbol (struct elf_link_hash_entry *h)
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{
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if (h->plt.plist != NULL
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&& !h->def_regular
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&& !h->pointer_equality_needed)
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return FALSE;
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return _bfd_elf_hash_symbol (h);
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}
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/* Determine the type of stub needed, if any, for a call. */
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static inline enum ppc_stub_type
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@ -12254,6 +12354,79 @@ ppc64_elf_set_toc (struct bfd_link_info *info, bfd *obfd)
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return TOCstart;
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}
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/* Called via elf_link_hash_traverse from ppc64_elf_build_stubs to
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write out any global entry stubs. */
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static bfd_boolean
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build_global_entry_stubs (struct elf_link_hash_entry *h, void *inf)
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{
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struct bfd_link_info *info;
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struct ppc_link_hash_table *htab;
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struct plt_entry *pent;
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asection *s;
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if (h->root.type == bfd_link_hash_indirect)
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return TRUE;
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if (!h->pointer_equality_needed)
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return TRUE;
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if (h->def_regular)
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return TRUE;
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info = inf;
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htab = ppc_hash_table (info);
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if (htab == NULL)
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return FALSE;
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s = htab->glink;
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for (pent = h->plt.plist; pent != NULL; pent = pent->next)
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if (pent->plt.offset != (bfd_vma) -1
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&& pent->addend == 0)
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{
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bfd_byte *p;
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asection *plt;
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bfd_vma off;
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/* For ELFv2, if this symbol is not defined in a regular file
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and we are not generating a shared library or pie, then we
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need to define the symbol in the executable on a call stub.
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This is to avoid text relocations. */
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h->root.u.def.section = s;
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h->root.u.def.value = s->size;
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s->size += 16;
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p = s->contents + h->root.u.def.value;
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plt = htab->plt;
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if (!htab->elf.dynamic_sections_created
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|| h->dynindx == -1)
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plt = htab->iplt;
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off = pent->plt.offset + plt->output_offset + plt->output_section->vma;
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off -= h->root.u.def.value + s->output_offset + s->output_section->vma;
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if (off + 0x80008000 > 0xffffffff || (off & 3) != 0)
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{
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info->callbacks->einfo
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(_("%P: linkage table error against `%T'\n"),
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h->root.root.string);
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bfd_set_error (bfd_error_bad_value);
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htab->stub_error = TRUE;
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}
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if (PPC_HA (off) != 0)
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{
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bfd_put_32 (s->owner, ADDIS_R12_R12 | PPC_HA (off), p);
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p += 4;
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}
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bfd_put_32 (s->owner, LD_R12_0R12 | PPC_LO (off), p);
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p += 4;
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bfd_put_32 (s->owner, MTCTR_R12, p);
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p += 4;
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bfd_put_32 (s->owner, BCTR, p);
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break;
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}
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return TRUE;
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}
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/* Build all the stubs associated with the current output file.
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The stubs are kept in a hash table attached to the main linker
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hash table. This function is called via gldelf64ppc_finish. */
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@ -12389,7 +12562,7 @@ ppc64_elf_build_stubs (bfd_boolean emit_stub_syms,
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/* Build the .glink lazy link call stubs. */
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indx = 0;
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while (p < htab->glink->contents + htab->glink->size)
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while (p < htab->glink->contents + htab->glink->rawsize)
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{
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if (htab->opd_abi)
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{
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||||
|
@ -12412,7 +12585,13 @@ ppc64_elf_build_stubs (bfd_boolean emit_stub_syms,
|
|||
indx++;
|
||||
p += 4;
|
||||
}
|
||||
htab->glink->rawsize = p - htab->glink->contents;
|
||||
|
||||
/* Build .glink global entry stubs. */
|
||||
if (htab->glink->size > htab->glink->rawsize)
|
||||
{
|
||||
htab->glink->size = (htab->glink->rawsize + 15) & -16;
|
||||
elf_link_hash_traverse (&htab->elf, build_global_entry_stubs, info);
|
||||
}
|
||||
}
|
||||
|
||||
if (htab->brlt->size != 0)
|
||||
|
@ -12516,7 +12695,7 @@ ppc64_elf_build_stubs (bfd_boolean emit_stub_syms,
|
|||
bfd_put_32 (htab->elf.dynobj, val, p);
|
||||
p += 4;
|
||||
/* .glink size. */
|
||||
bfd_put_32 (htab->elf.dynobj, htab->glink->rawsize - 8, p);
|
||||
bfd_put_32 (htab->elf.dynobj, htab->glink->size - 8, p);
|
||||
p += 4;
|
||||
/* Augmentation. */
|
||||
p += 1;
|
||||
|
@ -12566,7 +12745,6 @@ ppc64_elf_build_stubs (bfd_boolean emit_stub_syms,
|
|||
}
|
||||
|
||||
if (stub_sec != NULL
|
||||
|| htab->glink->rawsize != htab->glink->size
|
||||
|| (htab->glink_eh_frame != NULL
|
||||
&& htab->glink_eh_frame->rawsize != htab->glink_eh_frame->size))
|
||||
{
|
||||
|
@ -13823,13 +14001,14 @@ ppc64_elf_relocate_section (bfd *output_bfd,
|
|||
{
|
||||
struct plt_entry *ent;
|
||||
for (ent = h->elf.plt.plist; ent != NULL; ent = ent->next)
|
||||
if (ent->addend == orig_rel.r_addend
|
||||
&& ent->plt.offset != (bfd_vma) -1)
|
||||
if (ent->plt.offset != (bfd_vma) -1
|
||||
&& ent->addend == orig_rel.r_addend)
|
||||
{
|
||||
relocation = (htab->plt->output_section->vma
|
||||
+ htab->plt->output_offset
|
||||
+ ent->plt.offset);
|
||||
unresolved_reloc = FALSE;
|
||||
break;
|
||||
}
|
||||
}
|
||||
break;
|
||||
|
@ -14539,6 +14718,30 @@ ppc64_elf_finish_dynamic_symbol (bfd *output_bfd,
|
|||
/ PLT_ENTRY_SIZE (htab) * sizeof (Elf64_External_Rela)));
|
||||
}
|
||||
bfd_elf64_swap_reloca_out (output_bfd, &rela, loc);
|
||||
|
||||
if (!htab->opd_abi)
|
||||
{
|
||||
if (!h->def_regular)
|
||||
{
|
||||
/* Mark the symbol as undefined, rather than as
|
||||
defined in glink. Leave the value if there were
|
||||
any relocations where pointer equality matters
|
||||
(this is a clue for the dynamic linker, to make
|
||||
function pointer comparisons work between an
|
||||
application and shared library), otherwise set it
|
||||
to zero. */
|
||||
sym->st_shndx = SHN_UNDEF;
|
||||
if (!h->pointer_equality_needed)
|
||||
sym->st_value = 0;
|
||||
else if (!h->ref_regular_nonweak)
|
||||
{
|
||||
/* This breaks function pointer comparisons, but
|
||||
that is better than breaking tests for a NULL
|
||||
function pointer. */
|
||||
sym->st_value = 0;
|
||||
}
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
if (h->needs_copy)
|
||||
|
|
Loading…
Reference in New Issue