243 lines
7.4 KiB
C
243 lines
7.4 KiB
C
/* IBM S/390-specific support for ELF 32 and 64 bit functions
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Copyright (C) 2000-2014 Free Software Foundation, Inc.
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Contributed by Andreas Krebbel.
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This file is part of BFD, the Binary File Descriptor library.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, MA
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02110-1301, USA. */
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/* Return TRUE if H is an IFUNC symbol. Simply checking for the
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symbol type might not be enough since it might get changed to
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STT_FUNC for pointer equality reasons. */
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static inline bfd_boolean
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s390_is_ifunc_symbol_p (struct elf_link_hash_entry *h)
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{
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struct elf_s390_link_hash_entry *eh = (struct elf_s390_link_hash_entry*)h;
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return h->type == STT_GNU_IFUNC || eh->ifunc_resolver_address != 0;
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}
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/* Create sections needed by STT_GNU_IFUNC symbol. */
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static bfd_boolean
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s390_elf_create_ifunc_sections (bfd *abfd, struct bfd_link_info *info)
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{
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flagword flags;
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asection *s;
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const struct elf_backend_data *bed = get_elf_backend_data (abfd);
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struct elf_link_hash_table *htab = elf_hash_table (info);
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if (htab->iplt != NULL)
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return TRUE;
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flags = bed->dynamic_sec_flags;
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if (info->shared)
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{
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s = bfd_make_section_with_flags (abfd, ".rela.ifunc",
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flags | SEC_READONLY);
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if (s == NULL
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|| ! bfd_set_section_alignment (abfd, s,
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bed->s->log_file_align))
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return FALSE;
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htab->irelifunc = s;
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}
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/* Create .iplt, .rel[a].iplt, and .igot.plt. */
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s = bfd_make_section_with_flags (abfd, ".iplt",
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flags | SEC_CODE | SEC_READONLY);
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if (s == NULL
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|| ! bfd_set_section_alignment (abfd, s, bed->plt_alignment))
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return FALSE;
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htab->iplt = s;
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s = bfd_make_section_with_flags (abfd, ".rela.iplt", flags | SEC_READONLY);
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if (s == NULL
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|| ! bfd_set_section_alignment (abfd, s,
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bed->s->log_file_align))
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return FALSE;
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htab->irelplt = s;
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s = bfd_make_section_with_flags (abfd, ".igot.plt", flags);
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if (s == NULL
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|| !bfd_set_section_alignment (abfd, s,
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bed->s->log_file_align))
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return FALSE;
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htab->igotplt = s;
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return TRUE;
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}
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/* Allocate space in .plt, .got and associated reloc sections for
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dynamic relocs against a STT_GNU_IFUNC symbol definition. */
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static bfd_boolean
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s390_elf_allocate_ifunc_dyn_relocs (struct bfd_link_info *info,
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struct elf_link_hash_entry *h,
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struct elf_dyn_relocs **head)
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{
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struct elf_dyn_relocs *p;
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struct elf_link_hash_table *htab;
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struct elf_s390_link_hash_entry *eh = (struct elf_s390_link_hash_entry*)h;
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htab = elf_hash_table (info);
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eh->ifunc_resolver_address = h->root.u.def.value;
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eh->ifunc_resolver_section = h->root.u.def.section;
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/* Support garbage collection against STT_GNU_IFUNC symbols. */
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if (h->plt.refcount <= 0 && h->got.refcount <= 0)
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{
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/* When building shared library, we need to handle the case
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where it is marked with regular reference, but not non-GOT
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reference. It may happen if we didn't see STT_GNU_IFUNC
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symbol at the time when checking relocations. */
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if (info->shared
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&& !h->non_got_ref
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&& h->ref_regular)
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for (p = *head; p != NULL; p = p->next)
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if (p->count)
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{
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h->non_got_ref = 1;
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goto keep;
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}
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h->got = htab->init_got_offset;
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h->plt = htab->init_plt_offset;
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*head = NULL;
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return TRUE;
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}
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/* Return and discard space for dynamic relocations against it if
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it is never referenced in a non-shared object. */
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if (!h->ref_regular)
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{
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if (h->plt.refcount > 0
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|| h->got.refcount > 0)
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abort ();
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h->got = htab->init_got_offset;
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h->plt = htab->init_plt_offset;
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*head = NULL;
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return TRUE;
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}
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keep:
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/* Without checking h->plt.refcount here we allocate a PLT slot.
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When setting plt.refcount in check_relocs it might not have been
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known that this will be an IFUNC symol. */
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h->plt.offset = htab->iplt->size;
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h->needs_plt = 1;
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htab->iplt->size += PLT_ENTRY_SIZE;
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htab->igotplt->size += GOT_ENTRY_SIZE;
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htab->irelplt->size += RELA_ENTRY_SIZE;
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htab->irelplt->reloc_count++;
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/* In order to make pointer equality work with IFUNC symbols defined
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in a non-PIE executable and referenced in a shared lib, we turn
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the symbol into a STT_FUNC symbol and make the symbol value to
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point to the IPLT slot. That way the referencing shared lib will
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always get the PLT slot address when resolving the respective
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R_390_GLOB_DAT/R_390_64 relocs on that symbol. */
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if (info->executable && !info->shared && h->def_regular && h->ref_dynamic)
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{
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h->root.u.def.section = htab->iplt;
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h->root.u.def.value = h->plt.offset;
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h->size = PLT_ENTRY_SIZE;
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h->type = STT_FUNC;
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}
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/* We need dynamic relocation for STT_GNU_IFUNC symbol only when
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there is a non-GOT reference in a shared object. */
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if (!info->shared || !h->non_got_ref)
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*head = NULL;
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/* Finally, allocate space. */
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p = *head;
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if (p != NULL)
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{
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bfd_size_type count = 0;
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do
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{
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count += p->count;
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p = p->next;
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}
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while (p != NULL);
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htab->irelifunc->size += count * RELA_ENTRY_SIZE;
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}
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/* Decide whether the got.iplt slot can be used. This has to be
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avoided if the values in the GOT slots could differ for pointer
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equality reasons. */
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if (h->got.refcount <= 0
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|| (info->shared
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&& (h->dynindx == -1 || h->forced_local))
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|| (info->executable && info->shared)
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|| htab->sgot == NULL)
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{
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/* Use .got.iplt. */
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h->got.offset = (bfd_vma) -1;
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}
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else
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{
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h->got.offset = htab->sgot->size;
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htab->sgot->size += GOT_ENTRY_SIZE;
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if (info->shared)
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htab->srelgot->size += RELA_ENTRY_SIZE;
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}
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return TRUE;
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}
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static bfd_boolean
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elf_s390_allocate_local_syminfo (bfd *abfd, Elf_Internal_Shdr *symtab_hdr)
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{
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bfd_size_type size;
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size = symtab_hdr->sh_info;
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size *= (sizeof (bfd_signed_vma) /* local got */
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+ sizeof (struct plt_entry) /* local plt */
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+ sizeof(char)); /* local tls type */
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elf_local_got_refcounts (abfd) = ((bfd_signed_vma *)
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bfd_zalloc (abfd, size));
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if (elf_local_got_refcounts (abfd) == NULL)
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return FALSE;
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elf_s390_local_plt (abfd)
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= (struct plt_entry*)(elf_local_got_refcounts (abfd)
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+ symtab_hdr->sh_info);
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elf_s390_local_got_tls_type (abfd)
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= (char *) (elf_s390_local_plt (abfd) + symtab_hdr->sh_info);
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return TRUE;
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}
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/* Pick ELFOSABI_GNU if IFUNC symbols are used. */
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static bfd_boolean
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elf_s390_add_symbol_hook (bfd *abfd,
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struct bfd_link_info *info,
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Elf_Internal_Sym *sym,
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const char **namep ATTRIBUTE_UNUSED,
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flagword *flagsp ATTRIBUTE_UNUSED,
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asection **secp ATTRIBUTE_UNUSED,
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bfd_vma *valp ATTRIBUTE_UNUSED)
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{
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if ((abfd->flags & DYNAMIC) == 0
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&& ELF_ST_TYPE (sym->st_info) == STT_GNU_IFUNC)
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elf_tdata (info->output_bfd)->has_gnu_symbols = TRUE;
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return TRUE;
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}
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