| 1 | /* VxWorks support for ELF |
| 2 | Copyright 2005, 2006, 2007, 2009, 2012 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 3 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, |
| 19 | MA 02111-1307, USA. */ |
| 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 | #include "elf/vxworks.h" |
| 29 | |
| 30 | /* Return true if symbol NAME, as defined by ABFD, is one of the special |
| 31 | __GOTT_BASE__ or __GOTT_INDEX__ symbols. */ |
| 32 | |
| 33 | static bfd_boolean |
| 34 | elf_vxworks_gott_symbol_p (bfd *abfd, const char *name) |
| 35 | { |
| 36 | char leading; |
| 37 | |
| 38 | leading = bfd_get_symbol_leading_char (abfd); |
| 39 | if (leading) |
| 40 | { |
| 41 | if (*name != leading) |
| 42 | return FALSE; |
| 43 | name++; |
| 44 | } |
| 45 | return (strcmp (name, "__GOTT_BASE__") == 0 |
| 46 | || strcmp (name, "__GOTT_INDEX__") == 0); |
| 47 | } |
| 48 | |
| 49 | /* Tweak magic VxWorks symbols as they are loaded. */ |
| 50 | bfd_boolean |
| 51 | elf_vxworks_add_symbol_hook (bfd *abfd, |
| 52 | struct bfd_link_info *info, |
| 53 | Elf_Internal_Sym *sym, |
| 54 | const char **namep, |
| 55 | flagword *flagsp, |
| 56 | asection **secp ATTRIBUTE_UNUSED, |
| 57 | bfd_vma *valp ATTRIBUTE_UNUSED) |
| 58 | { |
| 59 | /* Ideally these "magic" symbols would be exported by libc.so.1 |
| 60 | which would be found via a DT_NEEDED tag, and then handled |
| 61 | specially by the linker at runtime. Except shared libraries |
| 62 | don't even link to libc.so.1 by default... |
| 63 | If the symbol is imported from, or will be put in a shared library, |
| 64 | give the symbol weak binding to get the desired samantics. |
| 65 | This transformation will be undone in |
| 66 | elf_i386_vxworks_link_output_symbol_hook. */ |
| 67 | if ((info->shared || abfd->flags & DYNAMIC) |
| 68 | && elf_vxworks_gott_symbol_p (abfd, *namep)) |
| 69 | { |
| 70 | sym->st_info = ELF_ST_INFO (STB_WEAK, ELF_ST_TYPE (sym->st_info)); |
| 71 | *flagsp |= BSF_WEAK; |
| 72 | } |
| 73 | |
| 74 | return TRUE; |
| 75 | } |
| 76 | |
| 77 | /* Perform VxWorks-specific handling of the create_dynamic_sections hook. |
| 78 | When creating an executable, set *SRELPLT2_OUT to the .rel(a).plt.unloaded |
| 79 | section. */ |
| 80 | |
| 81 | bfd_boolean |
| 82 | elf_vxworks_create_dynamic_sections (bfd *dynobj, struct bfd_link_info *info, |
| 83 | asection **srelplt2_out) |
| 84 | { |
| 85 | struct elf_link_hash_table *htab; |
| 86 | const struct elf_backend_data *bed; |
| 87 | asection *s; |
| 88 | |
| 89 | htab = elf_hash_table (info); |
| 90 | bed = get_elf_backend_data (dynobj); |
| 91 | |
| 92 | if (!info->shared) |
| 93 | { |
| 94 | s = bfd_make_section_anyway_with_flags (dynobj, |
| 95 | bed->default_use_rela_p |
| 96 | ? ".rela.plt.unloaded" |
| 97 | : ".rel.plt.unloaded", |
| 98 | SEC_HAS_CONTENTS | SEC_IN_MEMORY |
| 99 | | SEC_READONLY |
| 100 | | SEC_LINKER_CREATED); |
| 101 | if (s == NULL |
| 102 | || !bfd_set_section_alignment (dynobj, s, bed->s->log_file_align)) |
| 103 | return FALSE; |
| 104 | |
| 105 | *srelplt2_out = s; |
| 106 | } |
| 107 | |
| 108 | /* Mark the GOT and PLT symbols as having relocations; they might |
| 109 | not, but we won't know for sure until we build the GOT in |
| 110 | finish_dynamic_symbol. Also make sure that the GOT symbol |
| 111 | is entered into the dynamic symbol table; the loader uses it |
| 112 | to initialize __GOTT_BASE__[__GOTT_INDEX__]. */ |
| 113 | if (htab->hgot) |
| 114 | { |
| 115 | htab->hgot->indx = -2; |
| 116 | htab->hgot->other &= ~ELF_ST_VISIBILITY (-1); |
| 117 | htab->hgot->forced_local = 0; |
| 118 | if (!bfd_elf_link_record_dynamic_symbol (info, htab->hgot)) |
| 119 | return FALSE; |
| 120 | } |
| 121 | if (htab->hplt) |
| 122 | { |
| 123 | htab->hplt->indx = -2; |
| 124 | htab->hplt->type = STT_FUNC; |
| 125 | } |
| 126 | |
| 127 | return TRUE; |
| 128 | } |
| 129 | |
| 130 | /* Tweak magic VxWorks symbols as they are written to the output file. */ |
| 131 | int |
| 132 | elf_vxworks_link_output_symbol_hook (struct bfd_link_info *info |
| 133 | ATTRIBUTE_UNUSED, |
| 134 | const char *name, |
| 135 | Elf_Internal_Sym *sym, |
| 136 | asection *input_sec ATTRIBUTE_UNUSED, |
| 137 | struct elf_link_hash_entry *h) |
| 138 | { |
| 139 | /* Reverse the effects of the hack in elf_vxworks_add_symbol_hook. */ |
| 140 | if (h |
| 141 | && h->root.type == bfd_link_hash_undefweak |
| 142 | && elf_vxworks_gott_symbol_p (h->root.u.undef.abfd, name)) |
| 143 | sym->st_info = ELF_ST_INFO (STB_GLOBAL, ELF_ST_TYPE (sym->st_info)); |
| 144 | |
| 145 | return 1; |
| 146 | } |
| 147 | |
| 148 | /* Copy relocations into the output file. Fixes up relocations against PLT |
| 149 | entries, then calls the generic routine. */ |
| 150 | |
| 151 | bfd_boolean |
| 152 | elf_vxworks_emit_relocs (bfd *output_bfd, |
| 153 | asection *input_section, |
| 154 | Elf_Internal_Shdr *input_rel_hdr, |
| 155 | Elf_Internal_Rela *internal_relocs, |
| 156 | struct elf_link_hash_entry **rel_hash) |
| 157 | { |
| 158 | const struct elf_backend_data *bed; |
| 159 | int j; |
| 160 | |
| 161 | bed = get_elf_backend_data (output_bfd); |
| 162 | |
| 163 | if (output_bfd->flags & (DYNAMIC|EXEC_P)) |
| 164 | { |
| 165 | Elf_Internal_Rela *irela; |
| 166 | Elf_Internal_Rela *irelaend; |
| 167 | struct elf_link_hash_entry **hash_ptr; |
| 168 | |
| 169 | for (irela = internal_relocs, |
| 170 | irelaend = irela + (NUM_SHDR_ENTRIES (input_rel_hdr) |
| 171 | * bed->s->int_rels_per_ext_rel), |
| 172 | hash_ptr = rel_hash; |
| 173 | irela < irelaend; |
| 174 | irela += bed->s->int_rels_per_ext_rel, |
| 175 | hash_ptr++) |
| 176 | { |
| 177 | if (*hash_ptr |
| 178 | && (*hash_ptr)->def_dynamic |
| 179 | && !(*hash_ptr)->def_regular |
| 180 | && ((*hash_ptr)->root.type == bfd_link_hash_defined |
| 181 | || (*hash_ptr)->root.type == bfd_link_hash_defweak) |
| 182 | && (*hash_ptr)->root.u.def.section->output_section != NULL) |
| 183 | { |
| 184 | /* This is a relocation from an executable or shared |
| 185 | library against a symbol in a different shared |
| 186 | library. We are creating a definition in the output |
| 187 | file but it does not come from any of our normal (.o) |
| 188 | files. ie. a PLT stub. Normally this would be a |
| 189 | relocation against against SHN_UNDEF with the VMA of |
| 190 | the PLT stub. This upsets the VxWorks loader. |
| 191 | Convert it to a section-relative relocation. This |
| 192 | gets some other symbols (for instance .dynbss), but |
| 193 | is conservatively correct. */ |
| 194 | for (j = 0; j < bed->s->int_rels_per_ext_rel; j++) |
| 195 | { |
| 196 | asection *sec = (*hash_ptr)->root.u.def.section; |
| 197 | int this_idx = sec->output_section->target_index; |
| 198 | |
| 199 | irela[j].r_info |
| 200 | = ELF32_R_INFO (this_idx, ELF32_R_TYPE (irela[j].r_info)); |
| 201 | irela[j].r_addend += (*hash_ptr)->root.u.def.value; |
| 202 | irela[j].r_addend += sec->output_offset; |
| 203 | } |
| 204 | /* Stop the generic routine adjusting this entry. */ |
| 205 | *hash_ptr = NULL; |
| 206 | } |
| 207 | } |
| 208 | } |
| 209 | return _bfd_elf_link_output_relocs (output_bfd, input_section, |
| 210 | input_rel_hdr, internal_relocs, |
| 211 | rel_hash); |
| 212 | } |
| 213 | |
| 214 | |
| 215 | /* Set the sh_link and sh_info fields on the static plt relocation secton. */ |
| 216 | |
| 217 | void |
| 218 | elf_vxworks_final_write_processing (bfd *abfd, |
| 219 | bfd_boolean linker ATTRIBUTE_UNUSED) |
| 220 | { |
| 221 | asection * sec; |
| 222 | struct bfd_elf_section_data *d; |
| 223 | |
| 224 | sec = bfd_get_section_by_name (abfd, ".rel.plt.unloaded"); |
| 225 | if (!sec) |
| 226 | sec = bfd_get_section_by_name (abfd, ".rela.plt.unloaded"); |
| 227 | if (!sec) |
| 228 | return; |
| 229 | d = elf_section_data (sec); |
| 230 | d->this_hdr.sh_link = elf_onesymtab (abfd); |
| 231 | sec = bfd_get_section_by_name (abfd, ".plt"); |
| 232 | if (sec) |
| 233 | d->this_hdr.sh_info = elf_section_data (sec)->this_idx; |
| 234 | } |
| 235 | |
| 236 | /* Add the dynamic entries required by VxWorks. These point to the |
| 237 | tls sections. */ |
| 238 | |
| 239 | bfd_boolean |
| 240 | elf_vxworks_add_dynamic_entries (bfd *output_bfd, struct bfd_link_info *info) |
| 241 | { |
| 242 | if (bfd_get_section_by_name (output_bfd, ".tls_data")) |
| 243 | { |
| 244 | if (!_bfd_elf_add_dynamic_entry (info, DT_VX_WRS_TLS_DATA_START, 0) |
| 245 | || !_bfd_elf_add_dynamic_entry (info, DT_VX_WRS_TLS_DATA_SIZE, 0) |
| 246 | || !_bfd_elf_add_dynamic_entry (info, DT_VX_WRS_TLS_DATA_ALIGN, 0)) |
| 247 | return FALSE; |
| 248 | } |
| 249 | if (bfd_get_section_by_name (output_bfd, ".tls_vars")) |
| 250 | { |
| 251 | if (!_bfd_elf_add_dynamic_entry (info, DT_VX_WRS_TLS_VARS_START, 0) |
| 252 | || !_bfd_elf_add_dynamic_entry (info, DT_VX_WRS_TLS_VARS_SIZE, 0)) |
| 253 | return FALSE; |
| 254 | } |
| 255 | return TRUE; |
| 256 | } |
| 257 | |
| 258 | /* If *DYN is one of the VxWorks-specific dynamic entries, then fill |
| 259 | in the value now and return TRUE. Otherwise return FALSE. */ |
| 260 | |
| 261 | bfd_boolean |
| 262 | elf_vxworks_finish_dynamic_entry (bfd *output_bfd, Elf_Internal_Dyn *dyn) |
| 263 | { |
| 264 | asection *sec; |
| 265 | |
| 266 | switch (dyn->d_tag) |
| 267 | { |
| 268 | default: |
| 269 | return FALSE; |
| 270 | |
| 271 | case DT_VX_WRS_TLS_DATA_START: |
| 272 | sec = bfd_get_section_by_name (output_bfd, ".tls_data"); |
| 273 | dyn->d_un.d_ptr = sec->vma; |
| 274 | break; |
| 275 | |
| 276 | case DT_VX_WRS_TLS_DATA_SIZE: |
| 277 | sec = bfd_get_section_by_name (output_bfd, ".tls_data"); |
| 278 | dyn->d_un.d_val = sec->size; |
| 279 | break; |
| 280 | |
| 281 | case DT_VX_WRS_TLS_DATA_ALIGN: |
| 282 | sec = bfd_get_section_by_name (output_bfd, ".tls_data"); |
| 283 | dyn->d_un.d_val |
| 284 | = (bfd_size_type)1 << bfd_get_section_alignment (output_bfd, |
| 285 | sec); |
| 286 | break; |
| 287 | |
| 288 | case DT_VX_WRS_TLS_VARS_START: |
| 289 | sec = bfd_get_section_by_name (output_bfd, ".tls_vars"); |
| 290 | dyn->d_un.d_ptr = sec->vma; |
| 291 | break; |
| 292 | |
| 293 | case DT_VX_WRS_TLS_VARS_SIZE: |
| 294 | sec = bfd_get_section_by_name (output_bfd, ".tls_vars"); |
| 295 | dyn->d_un.d_val = sec->size; |
| 296 | break; |
| 297 | } |
| 298 | return TRUE; |
| 299 | } |
| 300 | |
| 301 | |