| 1 | /* VxWorks support for ELF |
| 2 | Copyright 2005, 2007 Free Software Foundation, Inc. |
| 3 | |
| 4 | This file is part of BFD, the Binary File Descriptor library. |
| 5 | |
| 6 | This program is free software; you can redistribute it and/or modify |
| 7 | it under the terms of the GNU General Public License as published by |
| 8 | the Free Software Foundation; either version 2 of the License, or |
| 9 | (at your option) any later version. |
| 10 | |
| 11 | This program is distributed in the hope that it will be useful, |
| 12 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 13 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 14 | GNU General Public License for more details. |
| 15 | |
| 16 | You should have received a copy of the GNU General Public License |
| 17 | along with this program; if not, write to the Free Software |
| 18 | Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. |
| 19 | */ |
| 20 | |
| 21 | /* This file provides routines used by all VxWorks targets. */ |
| 22 | |
| 23 | #include "sysdep.h" |
| 24 | #include "bfd.h" |
| 25 | #include "libbfd.h" |
| 26 | #include "elf-bfd.h" |
| 27 | #include "elf-vxworks.h" |
| 28 | |
| 29 | /* Return true if symbol NAME, as defined by ABFD, is one of the special |
| 30 | __GOTT_BASE__ or __GOTT_INDEX__ symbols. */ |
| 31 | |
| 32 | static bfd_boolean |
| 33 | elf_vxworks_gott_symbol_p (bfd *abfd, const char *name) |
| 34 | { |
| 35 | char leading; |
| 36 | |
| 37 | leading = bfd_get_symbol_leading_char (abfd); |
| 38 | if (leading) |
| 39 | { |
| 40 | if (*name != leading) |
| 41 | return FALSE; |
| 42 | name++; |
| 43 | } |
| 44 | return (strcmp (name, "__GOTT_BASE__") == 0 |
| 45 | || strcmp (name, "__GOTT_INDEX__") == 0); |
| 46 | } |
| 47 | |
| 48 | /* Tweak magic VxWorks symbols as they are loaded. */ |
| 49 | bfd_boolean |
| 50 | elf_vxworks_add_symbol_hook (bfd *abfd, |
| 51 | struct bfd_link_info *info, |
| 52 | Elf_Internal_Sym *sym, |
| 53 | const char **namep, |
| 54 | flagword *flagsp, |
| 55 | asection **secp ATTRIBUTE_UNUSED, |
| 56 | bfd_vma *valp ATTRIBUTE_UNUSED) |
| 57 | { |
| 58 | /* Ideally these "magic" symbols would be exported by libc.so.1 |
| 59 | which would be found via a DT_NEEDED tag, and then handled |
| 60 | specially by the linker at runtime. Except shared libraries |
| 61 | don't even link to libc.so.1 by default... |
| 62 | If the symbol is imported from, or will be put in a shared library, |
| 63 | give the symbol weak binding to get the desired samantics. |
| 64 | This transformation will be undone in |
| 65 | elf_i386_vxworks_link_output_symbol_hook. */ |
| 66 | if ((info->shared || abfd->flags & DYNAMIC) |
| 67 | && elf_vxworks_gott_symbol_p (abfd, *namep)) |
| 68 | { |
| 69 | sym->st_info = ELF_ST_INFO (STB_WEAK, ELF_ST_TYPE (sym->st_info)); |
| 70 | *flagsp |= BSF_WEAK; |
| 71 | } |
| 72 | |
| 73 | return TRUE; |
| 74 | } |
| 75 | |
| 76 | /* Perform VxWorks-specific handling of the create_dynamic_sections hook. |
| 77 | When creating an executable, set *SRELPLT2_OUT to the .rel(a).plt.unloaded |
| 78 | section. */ |
| 79 | |
| 80 | bfd_boolean |
| 81 | elf_vxworks_create_dynamic_sections (bfd *dynobj, struct bfd_link_info *info, |
| 82 | asection **srelplt2_out) |
| 83 | { |
| 84 | struct elf_link_hash_table *htab; |
| 85 | const struct elf_backend_data *bed; |
| 86 | asection *s; |
| 87 | |
| 88 | htab = elf_hash_table (info); |
| 89 | bed = get_elf_backend_data (dynobj); |
| 90 | |
| 91 | if (!info->shared) |
| 92 | { |
| 93 | s = bfd_make_section_with_flags (dynobj, |
| 94 | bed->default_use_rela_p |
| 95 | ? ".rela.plt.unloaded" |
| 96 | : ".rel.plt.unloaded", |
| 97 | SEC_HAS_CONTENTS | SEC_IN_MEMORY |
| 98 | | SEC_READONLY | SEC_LINKER_CREATED); |
| 99 | if (s == NULL |
| 100 | || !bfd_set_section_alignment (dynobj, s, bed->s->log_file_align)) |
| 101 | return FALSE; |
| 102 | |
| 103 | *srelplt2_out = s; |
| 104 | } |
| 105 | |
| 106 | /* Mark the GOT and PLT symbols as having relocations; they might |
| 107 | not, but we won't know for sure until we build the GOT in |
| 108 | finish_dynamic_symbol. Also make sure that the GOT symbol |
| 109 | is entered into the dynamic symbol table; the loader uses it |
| 110 | to initialize __GOTT_BASE__[__GOTT_INDEX__]. */ |
| 111 | if (htab->hgot) |
| 112 | { |
| 113 | htab->hgot->indx = -2; |
| 114 | htab->hgot->other &= ~ELF_ST_VISIBILITY (-1); |
| 115 | htab->hgot->forced_local = 0; |
| 116 | if (!bfd_elf_link_record_dynamic_symbol (info, htab->hgot)) |
| 117 | return FALSE; |
| 118 | } |
| 119 | if (htab->hplt) |
| 120 | { |
| 121 | htab->hplt->indx = -2; |
| 122 | htab->hplt->type = STT_FUNC; |
| 123 | } |
| 124 | |
| 125 | return TRUE; |
| 126 | } |
| 127 | |
| 128 | /* Tweak magic VxWorks symbols as they are written to the output file. */ |
| 129 | bfd_boolean |
| 130 | elf_vxworks_link_output_symbol_hook (struct bfd_link_info *info |
| 131 | ATTRIBUTE_UNUSED, |
| 132 | const char *name, |
| 133 | Elf_Internal_Sym *sym, |
| 134 | asection *input_sec ATTRIBUTE_UNUSED, |
| 135 | struct elf_link_hash_entry *h) |
| 136 | { |
| 137 | /* Reverse the effects of the hack in elf_vxworks_add_symbol_hook. */ |
| 138 | if (h |
| 139 | && h->root.type == bfd_link_hash_undefweak |
| 140 | && elf_vxworks_gott_symbol_p (h->root.u.undef.abfd, name)) |
| 141 | sym->st_info = ELF_ST_INFO (STB_GLOBAL, ELF_ST_TYPE (sym->st_info)); |
| 142 | |
| 143 | return TRUE; |
| 144 | } |
| 145 | |
| 146 | |
| 147 | /* Copy relocations into the output file. Fixes up relocations againt PLT |
| 148 | entries, then calls the generic routine. */ |
| 149 | |
| 150 | bfd_boolean |
| 151 | elf_vxworks_emit_relocs (bfd *output_bfd, |
| 152 | asection *input_section, |
| 153 | Elf_Internal_Shdr *input_rel_hdr, |
| 154 | Elf_Internal_Rela *internal_relocs, |
| 155 | struct elf_link_hash_entry **rel_hash) |
| 156 | { |
| 157 | const struct elf_backend_data *bed; |
| 158 | Elf_Internal_Rela *irela; |
| 159 | Elf_Internal_Rela *irelaend; |
| 160 | int j; |
| 161 | |
| 162 | bed = get_elf_backend_data (output_bfd); |
| 163 | |
| 164 | irela = internal_relocs; |
| 165 | irelaend = irela + (NUM_SHDR_ENTRIES (input_rel_hdr) |
| 166 | * bed->s->int_rels_per_ext_rel); |
| 167 | while (irela < irelaend) |
| 168 | { |
| 169 | if ((output_bfd->flags & (DYNAMIC|EXEC_P)) |
| 170 | && *rel_hash |
| 171 | && (*rel_hash)->def_dynamic |
| 172 | && !(*rel_hash)->def_regular |
| 173 | && ((*rel_hash)->root.type == bfd_link_hash_defined |
| 174 | || (*rel_hash)->root.type == bfd_link_hash_defweak) |
| 175 | && (*rel_hash)->root.u.def.section->output_section != NULL) |
| 176 | { |
| 177 | /* This is a relocation from an executable or shared library |
| 178 | against a symbol in a different shared library. We are |
| 179 | creating a definition in the output file but it does not come |
| 180 | from any of our normal (.o) files. ie. a PLT stub. |
| 181 | Normally this would be a relocation against against SHN_UNDEF |
| 182 | with the VMA of the PLT stub. This upsets the VxWorks loader. |
| 183 | Convert it to a section-relative relocation. |
| 184 | This gets some other symbols (for instance .dynbss), |
| 185 | but is conservatively correct. */ |
| 186 | for (j = 0; j < bed->s->int_rels_per_ext_rel; j++) |
| 187 | { |
| 188 | asection *sec = (*rel_hash)->root.u.def.section; |
| 189 | int this_idx = sec->output_section->target_index; |
| 190 | |
| 191 | irela[j].r_info = ELF32_R_INFO (this_idx, |
| 192 | ELF32_R_TYPE (irela[j].r_info)); |
| 193 | irela[j].r_addend += (*rel_hash)->root.u.def.value; |
| 194 | irela[j].r_addend += sec->output_offset; |
| 195 | } |
| 196 | /* Stop the generic routine adjusting this entry. */ |
| 197 | *rel_hash = NULL; |
| 198 | } |
| 199 | irela += bed->s->int_rels_per_ext_rel; |
| 200 | rel_hash++; |
| 201 | } |
| 202 | return _bfd_elf_link_output_relocs (output_bfd, input_section, |
| 203 | input_rel_hdr, internal_relocs, |
| 204 | rel_hash); |
| 205 | } |
| 206 | |
| 207 | |
| 208 | /* Set the sh_link and sh_info fields on the static plt relocation secton. */ |
| 209 | |
| 210 | void |
| 211 | elf_vxworks_final_write_processing (bfd *abfd, |
| 212 | bfd_boolean linker ATTRIBUTE_UNUSED) |
| 213 | { |
| 214 | asection * sec; |
| 215 | struct bfd_elf_section_data *d; |
| 216 | |
| 217 | sec = bfd_get_section_by_name (abfd, ".rel.plt.unloaded"); |
| 218 | if (!sec) |
| 219 | sec = bfd_get_section_by_name (abfd, ".rela.plt.unloaded"); |
| 220 | if (!sec) |
| 221 | return; |
| 222 | d = elf_section_data (sec); |
| 223 | d->this_hdr.sh_link = elf_tdata (abfd)->symtab_section; |
| 224 | sec = bfd_get_section_by_name (abfd, ".plt"); |
| 225 | if (sec) |
| 226 | d->this_hdr.sh_info = elf_section_data (sec)->this_idx; |
| 227 | } |