1 /* VxWorks support for ELF 2 Copyright 2005, 2006, 2007, 2009 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_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 | SEC_LINKER_CREATED); 100 if (s == NULL 101 || !bfd_set_section_alignment (dynobj, s, bed->s->log_file_align)) 102 return FALSE; 103 104 *srelplt2_out = s; 105 } 106 107 /* Mark the GOT and PLT symbols as having relocations; they might 108 not, but we won't know for sure until we build the GOT in 109 finish_dynamic_symbol. Also make sure that the GOT symbol 110 is entered into the dynamic symbol table; the loader uses it 111 to initialize __GOTT_BASE__[__GOTT_INDEX__]. */ 112 if (htab->hgot) 113 { 114 htab->hgot->indx = -2; 115 htab->hgot->other &= ~ELF_ST_VISIBILITY (-1); 116 htab->hgot->forced_local = 0; 117 if (!bfd_elf_link_record_dynamic_symbol (info, htab->hgot)) 118 return FALSE; 119 } 120 if (htab->hplt) 121 { 122 htab->hplt->indx = -2; 123 htab->hplt->type = STT_FUNC; 124 } 125 126 return TRUE; 127 } 128 129 /* Tweak magic VxWorks symbols as they are written to the output file. */ 130 int 131 elf_vxworks_link_output_symbol_hook (struct bfd_link_info *info 132 ATTRIBUTE_UNUSED, 133 const char *name, 134 Elf_Internal_Sym *sym, 135 asection *input_sec ATTRIBUTE_UNUSED, 136 struct elf_link_hash_entry *h) 137 { 138 /* Reverse the effects of the hack in elf_vxworks_add_symbol_hook. */ 139 if (h 140 && h->root.type == bfd_link_hash_undefweak 141 && elf_vxworks_gott_symbol_p (h->root.u.undef.abfd, name)) 142 sym->st_info = ELF_ST_INFO (STB_GLOBAL, ELF_ST_TYPE (sym->st_info)); 143 144 return 1; 145 } 146 147 /* Copy relocations into the output file. Fixes up relocations against 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 int j; 159 160 bed = get_elf_backend_data (output_bfd); 161 162 if (output_bfd->flags & (DYNAMIC|EXEC_P)) 163 { 164 Elf_Internal_Rela *irela; 165 Elf_Internal_Rela *irelaend; 166 struct elf_link_hash_entry **hash_ptr; 167 168 for (irela = internal_relocs, 169 irelaend = irela + (NUM_SHDR_ENTRIES (input_rel_hdr) 170 * bed->s->int_rels_per_ext_rel), 171 hash_ptr = rel_hash; 172 irela < irelaend; 173 irela += bed->s->int_rels_per_ext_rel, 174 hash_ptr++) 175 { 176 if (*hash_ptr 177 && (*hash_ptr)->def_dynamic 178 && !(*hash_ptr)->def_regular 179 && ((*hash_ptr)->root.type == bfd_link_hash_defined 180 || (*hash_ptr)->root.type == bfd_link_hash_defweak) 181 && (*hash_ptr)->root.u.def.section->output_section != NULL) 182 { 183 /* This is a relocation from an executable or shared 184 library against a symbol in a different shared 185 library. We are creating a definition in the output 186 file but it does not come from any of our normal (.o) 187 files. ie. a PLT stub. Normally this would be a 188 relocation against against SHN_UNDEF with the VMA of 189 the PLT stub. This upsets the VxWorks loader. 190 Convert it to a section-relative relocation. This 191 gets some other symbols (for instance .dynbss), but 192 is conservatively correct. */ 193 for (j = 0; j < bed->s->int_rels_per_ext_rel; j++) 194 { 195 asection *sec = (*hash_ptr)->root.u.def.section; 196 int this_idx = sec->output_section->target_index; 197 198 irela[j].r_info 199 = ELF32_R_INFO (this_idx, ELF32_R_TYPE (irela[j].r_info)); 200 irela[j].r_addend += (*hash_ptr)->root.u.def.value; 201 irela[j].r_addend += sec->output_offset; 202 } 203 /* Stop the generic routine adjusting this entry. */ 204 *hash_ptr = NULL; 205 } 206 } 207 } 208 return _bfd_elf_link_output_relocs (output_bfd, input_section, 209 input_rel_hdr, internal_relocs, 210 rel_hash); 211 } 212 213 214 /* Set the sh_link and sh_info fields on the static plt relocation secton. */ 215 216 void 217 elf_vxworks_final_write_processing (bfd *abfd, 218 bfd_boolean linker ATTRIBUTE_UNUSED) 219 { 220 asection * sec; 221 struct bfd_elf_section_data *d; 222 223 sec = bfd_get_section_by_name (abfd, ".rel.plt.unloaded"); 224 if (!sec) 225 sec = bfd_get_section_by_name (abfd, ".rela.plt.unloaded"); 226 if (!sec) 227 return; 228 d = elf_section_data (sec); 229 d->this_hdr.sh_link = elf_tdata (abfd)->symtab_section; 230 sec = bfd_get_section_by_name (abfd, ".plt"); 231 if (sec) 232 d->this_hdr.sh_info = elf_section_data (sec)->this_idx; 233 } 234 235 /* Add the dynamic entries required by VxWorks. These point to the 236 tls sections. */ 237 238 bfd_boolean 239 elf_vxworks_add_dynamic_entries (bfd *output_bfd, struct bfd_link_info *info) 240 { 241 if (bfd_get_section_by_name (output_bfd, ".tls_data")) 242 { 243 if (!_bfd_elf_add_dynamic_entry (info, DT_VX_WRS_TLS_DATA_START, 0) 244 || !_bfd_elf_add_dynamic_entry (info, DT_VX_WRS_TLS_DATA_SIZE, 0) 245 || !_bfd_elf_add_dynamic_entry (info, DT_VX_WRS_TLS_DATA_ALIGN, 0)) 246 return FALSE; 247 } 248 if (bfd_get_section_by_name (output_bfd, ".tls_vars")) 249 { 250 if (!_bfd_elf_add_dynamic_entry (info, DT_VX_WRS_TLS_VARS_START, 0) 251 || !_bfd_elf_add_dynamic_entry (info, DT_VX_WRS_TLS_VARS_SIZE, 0)) 252 return FALSE; 253 } 254 return TRUE; 255 } 256 257 /* If *DYN is one of the VxWorks-specific dynamic entries, then fill 258 in the value now and return TRUE. Otherwise return FALSE. */ 259 260 bfd_boolean 261 elf_vxworks_finish_dynamic_entry (bfd *output_bfd, Elf_Internal_Dyn *dyn) 262 { 263 asection *sec; 264 265 switch (dyn->d_tag) 266 { 267 default: 268 return FALSE; 269 270 case DT_VX_WRS_TLS_DATA_START: 271 sec = bfd_get_section_by_name (output_bfd, ".tls_data"); 272 dyn->d_un.d_ptr = sec->vma; 273 break; 274 275 case DT_VX_WRS_TLS_DATA_SIZE: 276 sec = bfd_get_section_by_name (output_bfd, ".tls_data"); 277 dyn->d_un.d_val = sec->size; 278 break; 279 280 case DT_VX_WRS_TLS_DATA_ALIGN: 281 sec = bfd_get_section_by_name (output_bfd, ".tls_data"); 282 dyn->d_un.d_val 283 = (bfd_size_type)1 << bfd_get_section_alignment (abfd, sec); 284 break; 285 286 case DT_VX_WRS_TLS_VARS_START: 287 sec = bfd_get_section_by_name (output_bfd, ".tls_vars"); 288 dyn->d_un.d_ptr = sec->vma; 289 break; 290 291 case DT_VX_WRS_TLS_VARS_SIZE: 292 sec = bfd_get_section_by_name (output_bfd, ".tls_vars"); 293 dyn->d_un.d_val = sec->size; 294 break; 295 } 296 return TRUE; 297 } 298 299 300