| /* VxWorks support for ELF |
| Copyright (C) 2005-2024 Free Software Foundation, Inc. |
| |
| This file is part of BFD, the Binary File Descriptor library. |
| |
| This program is free software; you can redistribute it and/or modify |
| it under the terms of the GNU General Public License as published by |
| the Free Software Foundation; either version 3 of the License, or |
| (at your option) any later version. |
| |
| This program is distributed in the hope that it will be useful, |
| but WITHOUT ANY WARRANTY; without even the implied warranty of |
| MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| GNU General Public License for more details. |
| |
| You should have received a copy of the GNU General Public License |
| along with this program. If not, see <http://www.gnu.org/licenses/>. */ |
| |
| /* This file provides routines used by all VxWorks targets. */ |
| |
| #include "sysdep.h" |
| #include "bfd.h" |
| #include "libbfd.h" |
| #include "elf-bfd.h" |
| #include "elf-vxworks.h" |
| #include "elf/vxworks.h" |
| |
| /* Return true if symbol NAME, as defined by ABFD, is one of the special |
| __GOTT_BASE__ or __GOTT_INDEX__ symbols. */ |
| |
| static bool |
| elf_vxworks_gott_symbol_p (bfd *abfd, const char *name) |
| { |
| char leading; |
| |
| leading = bfd_get_symbol_leading_char (abfd); |
| if (leading) |
| { |
| if (*name != leading) |
| return false; |
| name++; |
| } |
| return (strcmp (name, "__GOTT_BASE__") == 0 |
| || strcmp (name, "__GOTT_INDEX__") == 0); |
| } |
| |
| /* Tweak magic VxWorks symbols as they are loaded. */ |
| bool |
| elf_vxworks_add_symbol_hook (bfd *abfd, |
| struct bfd_link_info *info, |
| Elf_Internal_Sym *sym, |
| const char **namep, |
| flagword *flagsp, |
| asection **secp ATTRIBUTE_UNUSED, |
| bfd_vma *valp ATTRIBUTE_UNUSED) |
| { |
| /* Ideally these "magic" symbols would be exported by libc.so.1 |
| which would be found via a DT_NEEDED tag, and then handled |
| specially by the linker at runtime. Except shared libraries |
| don't even link to libc.so.1 by default... |
| If the symbol is imported from, or will be put in a shared library, |
| give the symbol weak binding to get the desired samantics. |
| This transformation will be undone in |
| elf_i386_vxworks_link_output_symbol_hook. */ |
| if ((bfd_link_pic (info) || abfd->flags & DYNAMIC) |
| && elf_vxworks_gott_symbol_p (abfd, *namep)) |
| { |
| sym->st_info = ELF_ST_INFO (STB_WEAK, ELF_ST_TYPE (sym->st_info)); |
| *flagsp |= BSF_WEAK; |
| } |
| |
| return true; |
| } |
| |
| /* Perform VxWorks-specific handling of the create_dynamic_sections hook. |
| When creating an executable, set *SRELPLT2_OUT to the .rel(a).plt.unloaded |
| section. */ |
| |
| bool |
| elf_vxworks_create_dynamic_sections (bfd *dynobj, struct bfd_link_info *info, |
| asection **srelplt2_out) |
| { |
| struct elf_link_hash_table *htab; |
| const struct elf_backend_data *bed; |
| asection *s; |
| |
| htab = elf_hash_table (info); |
| bed = get_elf_backend_data (dynobj); |
| |
| if (!bfd_link_pic (info)) |
| { |
| s = bfd_make_section_anyway_with_flags (dynobj, |
| bed->default_use_rela_p |
| ? ".rela.plt.unloaded" |
| : ".rel.plt.unloaded", |
| SEC_HAS_CONTENTS | SEC_IN_MEMORY |
| | SEC_READONLY |
| | SEC_LINKER_CREATED); |
| if (s == NULL |
| || !bfd_set_section_alignment (s, bed->s->log_file_align)) |
| return false; |
| |
| *srelplt2_out = s; |
| } |
| |
| /* Mark the GOT and PLT symbols as having relocations; they might |
| not, but we won't know for sure until we build the GOT in |
| finish_dynamic_symbol. Also make sure that the GOT symbol |
| is entered into the dynamic symbol table; the loader uses it |
| to initialize __GOTT_BASE__[__GOTT_INDEX__]. */ |
| if (htab->hgot) |
| { |
| htab->hgot->indx = -2; |
| htab->hgot->other &= ~ELF_ST_VISIBILITY (-1); |
| htab->hgot->forced_local = 0; |
| if (!bfd_elf_link_record_dynamic_symbol (info, htab->hgot)) |
| return false; |
| } |
| if (htab->hplt) |
| { |
| htab->hplt->indx = -2; |
| htab->hplt->type = STT_FUNC; |
| } |
| |
| return true; |
| } |
| |
| /* Tweak magic VxWorks symbols as they are written to the output file. */ |
| int |
| elf_vxworks_link_output_symbol_hook (struct bfd_link_info *info |
| ATTRIBUTE_UNUSED, |
| const char *name, |
| Elf_Internal_Sym *sym, |
| asection *input_sec ATTRIBUTE_UNUSED, |
| struct elf_link_hash_entry *h) |
| { |
| /* Reverse the effects of the hack in elf_vxworks_add_symbol_hook. */ |
| if (h |
| && h->root.type == bfd_link_hash_undefweak |
| && elf_vxworks_gott_symbol_p (h->root.u.undef.abfd, name)) |
| sym->st_info = ELF_ST_INFO (STB_GLOBAL, ELF_ST_TYPE (sym->st_info)); |
| |
| return 1; |
| } |
| |
| /* Copy relocations into the output file. Fixes up relocations against PLT |
| entries, then calls the generic routine. */ |
| |
| bool |
| elf_vxworks_emit_relocs (bfd *output_bfd, |
| asection *input_section, |
| Elf_Internal_Shdr *input_rel_hdr, |
| Elf_Internal_Rela *internal_relocs, |
| struct elf_link_hash_entry **rel_hash) |
| { |
| const struct elf_backend_data *bed; |
| int j; |
| |
| bed = get_elf_backend_data (output_bfd); |
| |
| if (output_bfd->flags & (DYNAMIC|EXEC_P)) |
| { |
| Elf_Internal_Rela *irela; |
| Elf_Internal_Rela *irelaend; |
| struct elf_link_hash_entry **hash_ptr; |
| |
| for (irela = internal_relocs, |
| irelaend = irela + (NUM_SHDR_ENTRIES (input_rel_hdr) |
| * bed->s->int_rels_per_ext_rel), |
| hash_ptr = rel_hash; |
| irela < irelaend; |
| irela += bed->s->int_rels_per_ext_rel, |
| hash_ptr++) |
| { |
| if (*hash_ptr) |
| { |
| (*hash_ptr)->has_reloc = 1; |
| if ((*hash_ptr)->def_dynamic |
| && !(*hash_ptr)->def_regular |
| && ((*hash_ptr)->root.type == bfd_link_hash_defined |
| || (*hash_ptr)->root.type == bfd_link_hash_defweak) |
| && (*hash_ptr)->root.u.def.section->output_section != NULL) |
| { |
| /* This is a relocation from an executable or shared |
| library against a symbol in a different shared |
| library. We are creating a definition in the output |
| file but it does not come from any of our normal (.o) |
| files. ie. a PLT stub. Normally this would be a |
| relocation against SHN_UNDEF with the VMA of |
| the PLT stub. This upsets the VxWorks loader. |
| Convert it to a section-relative relocation. This |
| gets some other symbols (for instance .dynbss), but |
| is conservatively correct. */ |
| for (j = 0; j < bed->s->int_rels_per_ext_rel; j++) |
| { |
| asection *sec = (*hash_ptr)->root.u.def.section; |
| int this_idx = sec->output_section->target_index; |
| |
| irela[j].r_info |
| = ELF32_R_INFO (this_idx, |
| ELF32_R_TYPE (irela[j].r_info)); |
| irela[j].r_addend += (*hash_ptr)->root.u.def.value; |
| irela[j].r_addend += sec->output_offset; |
| } |
| /* Stop the generic routine adjusting this entry. */ |
| *hash_ptr = NULL; |
| } |
| } |
| } |
| } |
| return _bfd_elf_link_output_relocs (output_bfd, input_section, |
| input_rel_hdr, internal_relocs, |
| rel_hash); |
| } |
| |
| |
| /* Set the sh_link and sh_info fields on the static plt relocation secton. */ |
| |
| bool |
| elf_vxworks_final_write_processing (bfd *abfd) |
| { |
| asection * sec; |
| struct bfd_elf_section_data *d; |
| |
| sec = bfd_get_section_by_name (abfd, ".rel.plt.unloaded"); |
| if (!sec) |
| sec = bfd_get_section_by_name (abfd, ".rela.plt.unloaded"); |
| if (sec) |
| { |
| d = elf_section_data (sec); |
| d->this_hdr.sh_link = elf_onesymtab (abfd); |
| sec = bfd_get_section_by_name (abfd, ".plt"); |
| if (sec) |
| d->this_hdr.sh_info = elf_section_data (sec)->this_idx; |
| } |
| return _bfd_elf_final_write_processing (abfd); |
| } |
| |
| /* Add the dynamic entries required by VxWorks. These point to the |
| tls sections. */ |
| |
| bool |
| elf_vxworks_add_dynamic_entries (bfd *output_bfd, struct bfd_link_info *info) |
| { |
| if (bfd_get_section_by_name (output_bfd, ".tls_data")) |
| { |
| if (!_bfd_elf_add_dynamic_entry (info, DT_VX_WRS_TLS_DATA_START, 0) |
| || !_bfd_elf_add_dynamic_entry (info, DT_VX_WRS_TLS_DATA_SIZE, 0) |
| || !_bfd_elf_add_dynamic_entry (info, DT_VX_WRS_TLS_DATA_ALIGN, 0)) |
| return false; |
| } |
| if (bfd_get_section_by_name (output_bfd, ".tls_vars")) |
| { |
| if (!_bfd_elf_add_dynamic_entry (info, DT_VX_WRS_TLS_VARS_START, 0) |
| || !_bfd_elf_add_dynamic_entry (info, DT_VX_WRS_TLS_VARS_SIZE, 0)) |
| return false; |
| } |
| return true; |
| } |
| |
| /* If *DYN is one of the VxWorks-specific dynamic entries, then fill |
| in the value now and return TRUE. Otherwise return FALSE. */ |
| |
| bool |
| elf_vxworks_finish_dynamic_entry (bfd *output_bfd, Elf_Internal_Dyn *dyn) |
| { |
| asection *sec; |
| |
| switch (dyn->d_tag) |
| { |
| default: |
| return false; |
| |
| case DT_VX_WRS_TLS_DATA_START: |
| sec = bfd_get_section_by_name (output_bfd, ".tls_data"); |
| dyn->d_un.d_ptr = sec->vma; |
| break; |
| |
| case DT_VX_WRS_TLS_DATA_SIZE: |
| sec = bfd_get_section_by_name (output_bfd, ".tls_data"); |
| dyn->d_un.d_val = sec->size; |
| break; |
| |
| case DT_VX_WRS_TLS_DATA_ALIGN: |
| sec = bfd_get_section_by_name (output_bfd, ".tls_data"); |
| dyn->d_un.d_val = (bfd_size_type) 1 << bfd_section_alignment (sec); |
| break; |
| |
| case DT_VX_WRS_TLS_VARS_START: |
| sec = bfd_get_section_by_name (output_bfd, ".tls_vars"); |
| dyn->d_un.d_ptr = sec->vma; |
| break; |
| |
| case DT_VX_WRS_TLS_VARS_SIZE: |
| sec = bfd_get_section_by_name (output_bfd, ".tls_vars"); |
| dyn->d_un.d_val = sec->size; |
| break; |
| } |
| return true; |
| } |
| |
| /* Add dynamic tags. */ |
| |
| bool |
| _bfd_elf_maybe_vxworks_add_dynamic_tags (bfd *output_bfd, |
| struct bfd_link_info *info, |
| bool need_dynamic_reloc) |
| { |
| struct elf_link_hash_table *htab = elf_hash_table (info); |
| return (_bfd_elf_add_dynamic_tags (output_bfd, info, |
| need_dynamic_reloc) |
| && (!htab->dynamic_sections_created |
| || htab->target_os != is_vxworks |
| || elf_vxworks_add_dynamic_entries (output_bfd, info))); |
| } |