312 lines
9.4 KiB
C
312 lines
9.4 KiB
C
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/* VxWorks support for ELF
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Copyright (C) 2005-2022 Free Software Foundation, Inc.
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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, see <http://www.gnu.org/licenses/>. */
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/* This file provides routines used by all VxWorks targets. */
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#include "sysdep.h"
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#include "bfd.h"
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#include "libbfd.h"
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#include "elf-bfd.h"
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#include "elf-vxworks.h"
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#include "elf/vxworks.h"
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/* Return true if symbol NAME, as defined by ABFD, is one of the special
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__GOTT_BASE__ or __GOTT_INDEX__ symbols. */
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static bool
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elf_vxworks_gott_symbol_p (bfd *abfd, const char *name)
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{
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char leading;
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leading = bfd_get_symbol_leading_char (abfd);
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if (leading)
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{
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if (*name != leading)
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return false;
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name++;
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}
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return (strcmp (name, "__GOTT_BASE__") == 0
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|| strcmp (name, "__GOTT_INDEX__") == 0);
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}
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/* Tweak magic VxWorks symbols as they are loaded. */
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bool
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elf_vxworks_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,
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flagword *flagsp,
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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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/* Ideally these "magic" symbols would be exported by libc.so.1
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which would be found via a DT_NEEDED tag, and then handled
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specially by the linker at runtime. Except shared libraries
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don't even link to libc.so.1 by default...
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If the symbol is imported from, or will be put in a shared library,
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give the symbol weak binding to get the desired samantics.
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This transformation will be undone in
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elf_i386_vxworks_link_output_symbol_hook. */
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if ((bfd_link_pic (info) || abfd->flags & DYNAMIC)
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&& elf_vxworks_gott_symbol_p (abfd, *namep))
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{
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sym->st_info = ELF_ST_INFO (STB_WEAK, ELF_ST_TYPE (sym->st_info));
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*flagsp |= BSF_WEAK;
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}
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return true;
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}
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/* Perform VxWorks-specific handling of the create_dynamic_sections hook.
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When creating an executable, set *SRELPLT2_OUT to the .rel(a).plt.unloaded
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section. */
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bool
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elf_vxworks_create_dynamic_sections (bfd *dynobj, struct bfd_link_info *info,
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asection **srelplt2_out)
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{
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struct elf_link_hash_table *htab;
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const struct elf_backend_data *bed;
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asection *s;
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htab = elf_hash_table (info);
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bed = get_elf_backend_data (dynobj);
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if (!bfd_link_pic (info))
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{
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s = bfd_make_section_anyway_with_flags (dynobj,
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bed->default_use_rela_p
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? ".rela.plt.unloaded"
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: ".rel.plt.unloaded",
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SEC_HAS_CONTENTS | SEC_IN_MEMORY
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| SEC_READONLY
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| SEC_LINKER_CREATED);
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if (s == NULL
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|| !bfd_set_section_alignment (s, bed->s->log_file_align))
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return false;
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*srelplt2_out = s;
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}
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/* Mark the GOT and PLT symbols as having relocations; they might
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not, but we won't know for sure until we build the GOT in
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finish_dynamic_symbol. Also make sure that the GOT symbol
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is entered into the dynamic symbol table; the loader uses it
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to initialize __GOTT_BASE__[__GOTT_INDEX__]. */
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if (htab->hgot)
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{
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htab->hgot->indx = -2;
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htab->hgot->other &= ~ELF_ST_VISIBILITY (-1);
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htab->hgot->forced_local = 0;
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if (!bfd_elf_link_record_dynamic_symbol (info, htab->hgot))
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return false;
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}
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if (htab->hplt)
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{
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htab->hplt->indx = -2;
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htab->hplt->type = STT_FUNC;
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}
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return true;
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}
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/* Tweak magic VxWorks symbols as they are written to the output file. */
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int
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elf_vxworks_link_output_symbol_hook (struct bfd_link_info *info
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ATTRIBUTE_UNUSED,
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const char *name,
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Elf_Internal_Sym *sym,
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asection *input_sec ATTRIBUTE_UNUSED,
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struct elf_link_hash_entry *h)
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{
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/* Reverse the effects of the hack in elf_vxworks_add_symbol_hook. */
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if (h
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&& h->root.type == bfd_link_hash_undefweak
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&& elf_vxworks_gott_symbol_p (h->root.u.undef.abfd, name))
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sym->st_info = ELF_ST_INFO (STB_GLOBAL, ELF_ST_TYPE (sym->st_info));
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return 1;
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}
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/* Copy relocations into the output file. Fixes up relocations against PLT
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entries, then calls the generic routine. */
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bool
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elf_vxworks_emit_relocs (bfd *output_bfd,
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asection *input_section,
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Elf_Internal_Shdr *input_rel_hdr,
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Elf_Internal_Rela *internal_relocs,
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struct elf_link_hash_entry **rel_hash)
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{
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const struct elf_backend_data *bed;
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int j;
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bed = get_elf_backend_data (output_bfd);
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if (output_bfd->flags & (DYNAMIC|EXEC_P))
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{
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Elf_Internal_Rela *irela;
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Elf_Internal_Rela *irelaend;
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struct elf_link_hash_entry **hash_ptr;
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for (irela = internal_relocs,
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irelaend = irela + (NUM_SHDR_ENTRIES (input_rel_hdr)
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* bed->s->int_rels_per_ext_rel),
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hash_ptr = rel_hash;
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irela < irelaend;
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irela += bed->s->int_rels_per_ext_rel,
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hash_ptr++)
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{
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if (*hash_ptr
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&& (*hash_ptr)->def_dynamic
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&& !(*hash_ptr)->def_regular
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&& ((*hash_ptr)->root.type == bfd_link_hash_defined
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|| (*hash_ptr)->root.type == bfd_link_hash_defweak)
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&& (*hash_ptr)->root.u.def.section->output_section != NULL)
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{
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/* This is a relocation from an executable or shared
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library against a symbol in a different shared
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library. We are creating a definition in the output
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file but it does not come from any of our normal (.o)
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files. ie. a PLT stub. Normally this would be a
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relocation against against SHN_UNDEF with the VMA of
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the PLT stub. This upsets the VxWorks loader.
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Convert it to a section-relative relocation. This
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gets some other symbols (for instance .dynbss), but
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is conservatively correct. */
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for (j = 0; j < bed->s->int_rels_per_ext_rel; j++)
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{
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asection *sec = (*hash_ptr)->root.u.def.section;
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int this_idx = sec->output_section->target_index;
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irela[j].r_info
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= ELF32_R_INFO (this_idx, ELF32_R_TYPE (irela[j].r_info));
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irela[j].r_addend += (*hash_ptr)->root.u.def.value;
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irela[j].r_addend += sec->output_offset;
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}
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/* Stop the generic routine adjusting this entry. */
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*hash_ptr = NULL;
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}
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}
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}
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return _bfd_elf_link_output_relocs (output_bfd, input_section,
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input_rel_hdr, internal_relocs,
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rel_hash);
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}
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/* Set the sh_link and sh_info fields on the static plt relocation secton. */
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bool
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elf_vxworks_final_write_processing (bfd *abfd)
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{
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asection * sec;
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struct bfd_elf_section_data *d;
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sec = bfd_get_section_by_name (abfd, ".rel.plt.unloaded");
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if (!sec)
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sec = bfd_get_section_by_name (abfd, ".rela.plt.unloaded");
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if (sec)
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{
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d = elf_section_data (sec);
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d->this_hdr.sh_link = elf_onesymtab (abfd);
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sec = bfd_get_section_by_name (abfd, ".plt");
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if (sec)
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d->this_hdr.sh_info = elf_section_data (sec)->this_idx;
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}
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return _bfd_elf_final_write_processing (abfd);
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}
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/* Add the dynamic entries required by VxWorks. These point to the
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tls sections. */
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bool
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elf_vxworks_add_dynamic_entries (bfd *output_bfd, struct bfd_link_info *info)
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{
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if (bfd_get_section_by_name (output_bfd, ".tls_data"))
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{
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if (!_bfd_elf_add_dynamic_entry (info, DT_VX_WRS_TLS_DATA_START, 0)
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|| !_bfd_elf_add_dynamic_entry (info, DT_VX_WRS_TLS_DATA_SIZE, 0)
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|| !_bfd_elf_add_dynamic_entry (info, DT_VX_WRS_TLS_DATA_ALIGN, 0))
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return false;
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}
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if (bfd_get_section_by_name (output_bfd, ".tls_vars"))
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{
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if (!_bfd_elf_add_dynamic_entry (info, DT_VX_WRS_TLS_VARS_START, 0)
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|| !_bfd_elf_add_dynamic_entry (info, DT_VX_WRS_TLS_VARS_SIZE, 0))
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return false;
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}
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return true;
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}
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/* If *DYN is one of the VxWorks-specific dynamic entries, then fill
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in the value now and return TRUE. Otherwise return FALSE. */
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bool
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elf_vxworks_finish_dynamic_entry (bfd *output_bfd, Elf_Internal_Dyn *dyn)
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{
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asection *sec;
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switch (dyn->d_tag)
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{
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default:
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return false;
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case DT_VX_WRS_TLS_DATA_START:
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sec = bfd_get_section_by_name (output_bfd, ".tls_data");
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dyn->d_un.d_ptr = sec->vma;
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break;
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case DT_VX_WRS_TLS_DATA_SIZE:
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sec = bfd_get_section_by_name (output_bfd, ".tls_data");
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dyn->d_un.d_val = sec->size;
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break;
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case DT_VX_WRS_TLS_DATA_ALIGN:
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sec = bfd_get_section_by_name (output_bfd, ".tls_data");
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dyn->d_un.d_val = (bfd_size_type) 1 << bfd_section_alignment (sec);
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break;
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case DT_VX_WRS_TLS_VARS_START:
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sec = bfd_get_section_by_name (output_bfd, ".tls_vars");
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dyn->d_un.d_ptr = sec->vma;
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break;
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case DT_VX_WRS_TLS_VARS_SIZE:
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sec = bfd_get_section_by_name (output_bfd, ".tls_vars");
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dyn->d_un.d_val = sec->size;
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break;
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}
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return true;
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}
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/* Add dynamic tags. */
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bool
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_bfd_elf_maybe_vxworks_add_dynamic_tags (bfd *output_bfd,
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struct bfd_link_info *info,
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bool need_dynamic_reloc)
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{
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struct elf_link_hash_table *htab = elf_hash_table (info);
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return (_bfd_elf_add_dynamic_tags (output_bfd, info,
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need_dynamic_reloc)
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&& (!htab->dynamic_sections_created
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|| htab->target_os != is_vxworks
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|| elf_vxworks_add_dynamic_entries (output_bfd, info)));
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}
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