| 1 | /* bfdlink.h -- header file for BFD link routines |
| 2 | Copyright (C) 1993-2018 Free Software Foundation, Inc. |
| 3 | Written by Steve Chamberlain and Ian Lance Taylor, Cygnus Support. |
| 4 | |
| 5 | This file is part of BFD, the Binary File Descriptor library. |
| 6 | |
| 7 | This program is free software; you can redistribute it and/or modify |
| 8 | it under the terms of the GNU General Public License as published by |
| 9 | the Free Software Foundation; either version 3 of the License, or |
| 10 | (at your option) any later version. |
| 11 | |
| 12 | This program is distributed in the hope that it will be useful, |
| 13 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 14 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 15 | GNU General Public License for more details. |
| 16 | |
| 17 | You should have received a copy of the GNU General Public License |
| 18 | along with this program; if not, write to the Free Software |
| 19 | Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, |
| 20 | MA 02110-1301, USA. */ |
| 21 | |
| 22 | #ifndef BFDLINK_H |
| 23 | #define BFDLINK_H |
| 24 | |
| 25 | /* Which symbols to strip during a link. */ |
| 26 | enum bfd_link_strip |
| 27 | { |
| 28 | strip_none, /* Don't strip any symbols. */ |
| 29 | strip_debugger, /* Strip debugging symbols. */ |
| 30 | strip_some, /* keep_hash is the list of symbols to keep. */ |
| 31 | strip_all /* Strip all symbols. */ |
| 32 | }; |
| 33 | |
| 34 | /* Which local symbols to discard during a link. This is irrelevant |
| 35 | if strip_all is used. */ |
| 36 | enum bfd_link_discard |
| 37 | { |
| 38 | discard_sec_merge, /* Discard local temporary symbols in SEC_MERGE |
| 39 | sections. */ |
| 40 | discard_none, /* Don't discard any locals. */ |
| 41 | discard_l, /* Discard local temporary symbols. */ |
| 42 | discard_all /* Discard all locals. */ |
| 43 | }; |
| 44 | |
| 45 | /* Whether to generate ELF common symbols with the STT_COMMON type |
| 46 | during a relocatable link. */ |
| 47 | enum bfd_link_elf_stt_common |
| 48 | { |
| 49 | unchanged, |
| 50 | elf_stt_common, |
| 51 | no_elf_stt_common |
| 52 | }; |
| 53 | |
| 54 | /* Describes the type of hash table entry structure being used. |
| 55 | Different hash table structure have different fields and so |
| 56 | support different linking features. */ |
| 57 | enum bfd_link_hash_table_type |
| 58 | { |
| 59 | bfd_link_generic_hash_table, |
| 60 | bfd_link_elf_hash_table |
| 61 | }; |
| 62 | \f |
| 63 | /* These are the possible types of an entry in the BFD link hash |
| 64 | table. */ |
| 65 | |
| 66 | enum bfd_link_hash_type |
| 67 | { |
| 68 | bfd_link_hash_new, /* Symbol is new. */ |
| 69 | bfd_link_hash_undefined, /* Symbol seen before, but undefined. */ |
| 70 | bfd_link_hash_undefweak, /* Symbol is weak and undefined. */ |
| 71 | bfd_link_hash_defined, /* Symbol is defined. */ |
| 72 | bfd_link_hash_defweak, /* Symbol is weak and defined. */ |
| 73 | bfd_link_hash_common, /* Symbol is common. */ |
| 74 | bfd_link_hash_indirect, /* Symbol is an indirect link. */ |
| 75 | bfd_link_hash_warning /* Like indirect, but warn if referenced. */ |
| 76 | }; |
| 77 | |
| 78 | enum bfd_link_common_skip_ar_symbols |
| 79 | { |
| 80 | bfd_link_common_skip_none, |
| 81 | bfd_link_common_skip_text, |
| 82 | bfd_link_common_skip_data, |
| 83 | bfd_link_common_skip_all |
| 84 | }; |
| 85 | |
| 86 | struct bfd_link_hash_common_entry |
| 87 | { |
| 88 | unsigned int alignment_power; /* Alignment. */ |
| 89 | asection *section; /* Symbol section. */ |
| 90 | }; |
| 91 | |
| 92 | /* The linking routines use a hash table which uses this structure for |
| 93 | its elements. */ |
| 94 | |
| 95 | struct bfd_link_hash_entry |
| 96 | { |
| 97 | /* Base hash table entry structure. */ |
| 98 | struct bfd_hash_entry root; |
| 99 | |
| 100 | /* Type of this entry. */ |
| 101 | ENUM_BITFIELD (bfd_link_hash_type) type : 8; |
| 102 | |
| 103 | /* Symbol is referenced in a normal regular object file, |
| 104 | as distinct from a LTO IR object file. */ |
| 105 | unsigned int non_ir_ref_regular : 1; |
| 106 | |
| 107 | /* Symbol is referenced in a normal dynamic object file, |
| 108 | as distinct from a LTO IR object file. */ |
| 109 | unsigned int non_ir_ref_dynamic : 1; |
| 110 | |
| 111 | /* Symbol is a built-in define. These will be overridden by PROVIDE |
| 112 | in a linker script. */ |
| 113 | unsigned int linker_def : 1; |
| 114 | |
| 115 | /* Symbol defined in a linker script. */ |
| 116 | unsigned int ldscript_def : 1; |
| 117 | |
| 118 | /* A union of information depending upon the type. */ |
| 119 | union |
| 120 | { |
| 121 | /* Nothing is kept for bfd_hash_new. */ |
| 122 | /* bfd_link_hash_undefined, bfd_link_hash_undefweak. */ |
| 123 | struct |
| 124 | { |
| 125 | /* Undefined and common symbols are kept in a linked list through |
| 126 | this field. This field is present in all of the union element |
| 127 | so that we don't need to remove entries from the list when we |
| 128 | change their type. Removing entries would either require the |
| 129 | list to be doubly linked, which would waste more memory, or |
| 130 | require a traversal. When an undefined or common symbol is |
| 131 | created, it should be added to this list, the head of which is in |
| 132 | the link hash table itself. As symbols are defined, they need |
| 133 | not be removed from the list; anything which reads the list must |
| 134 | doublecheck the symbol type. |
| 135 | |
| 136 | Weak symbols are not kept on this list. |
| 137 | |
| 138 | Defined and defweak symbols use this field as a reference marker. |
| 139 | If the field is not NULL, or this structure is the tail of the |
| 140 | undefined symbol list, the symbol has been referenced. If the |
| 141 | symbol is undefined and becomes defined, this field will |
| 142 | automatically be non-NULL since the symbol will have been on the |
| 143 | undefined symbol list. */ |
| 144 | struct bfd_link_hash_entry *next; |
| 145 | /* BFD symbol was found in. */ |
| 146 | bfd *abfd; |
| 147 | } undef; |
| 148 | /* bfd_link_hash_defined, bfd_link_hash_defweak. */ |
| 149 | struct |
| 150 | { |
| 151 | struct bfd_link_hash_entry *next; |
| 152 | /* Symbol section. */ |
| 153 | asection *section; |
| 154 | /* Symbol value. */ |
| 155 | bfd_vma value; |
| 156 | } def; |
| 157 | /* bfd_link_hash_indirect, bfd_link_hash_warning. */ |
| 158 | struct |
| 159 | { |
| 160 | struct bfd_link_hash_entry *next; |
| 161 | /* Real symbol. */ |
| 162 | struct bfd_link_hash_entry *link; |
| 163 | /* Warning message (bfd_link_hash_warning only). */ |
| 164 | const char *warning; |
| 165 | } i; |
| 166 | /* bfd_link_hash_common. */ |
| 167 | struct |
| 168 | { |
| 169 | struct bfd_link_hash_entry *next; |
| 170 | /* The linker needs to know three things about common |
| 171 | symbols: the size, the alignment, and the section in |
| 172 | which the symbol should be placed. We store the size |
| 173 | here, and we allocate a small structure to hold the |
| 174 | section and the alignment. The alignment is stored as a |
| 175 | power of two. We don't store all the information |
| 176 | directly because we don't want to increase the size of |
| 177 | the union; this structure is a major space user in the |
| 178 | linker. */ |
| 179 | struct bfd_link_hash_common_entry *p; |
| 180 | /* Common symbol size. */ |
| 181 | bfd_size_type size; |
| 182 | } c; |
| 183 | } u; |
| 184 | }; |
| 185 | |
| 186 | /* This is the link hash table. It is a derived class of |
| 187 | bfd_hash_table. */ |
| 188 | |
| 189 | struct bfd_link_hash_table |
| 190 | { |
| 191 | /* The hash table itself. */ |
| 192 | struct bfd_hash_table table; |
| 193 | /* A linked list of undefined and common symbols, linked through the |
| 194 | next field in the bfd_link_hash_entry structure. */ |
| 195 | struct bfd_link_hash_entry *undefs; |
| 196 | /* Entries are added to the tail of the undefs list. */ |
| 197 | struct bfd_link_hash_entry *undefs_tail; |
| 198 | /* Function to free the hash table on closing BFD. */ |
| 199 | void (*hash_table_free) (bfd *); |
| 200 | /* The type of the link hash table. */ |
| 201 | enum bfd_link_hash_table_type type; |
| 202 | }; |
| 203 | |
| 204 | /* Look up an entry in a link hash table. If FOLLOW is TRUE, this |
| 205 | follows bfd_link_hash_indirect and bfd_link_hash_warning links to |
| 206 | the real symbol. */ |
| 207 | extern struct bfd_link_hash_entry *bfd_link_hash_lookup |
| 208 | (struct bfd_link_hash_table *, const char *, bfd_boolean create, |
| 209 | bfd_boolean copy, bfd_boolean follow); |
| 210 | |
| 211 | /* Look up an entry in the main linker hash table if the symbol might |
| 212 | be wrapped. This should only be used for references to an |
| 213 | undefined symbol, not for definitions of a symbol. */ |
| 214 | |
| 215 | extern struct bfd_link_hash_entry *bfd_wrapped_link_hash_lookup |
| 216 | (bfd *, struct bfd_link_info *, const char *, bfd_boolean, |
| 217 | bfd_boolean, bfd_boolean); |
| 218 | |
| 219 | /* If H is a wrapped symbol, ie. the symbol name starts with "__wrap_" |
| 220 | and the remainder is found in wrap_hash, return the real symbol. */ |
| 221 | |
| 222 | extern struct bfd_link_hash_entry *unwrap_hash_lookup |
| 223 | (struct bfd_link_info *, bfd *, struct bfd_link_hash_entry *); |
| 224 | |
| 225 | /* Traverse a link hash table. */ |
| 226 | extern void bfd_link_hash_traverse |
| 227 | (struct bfd_link_hash_table *, |
| 228 | bfd_boolean (*) (struct bfd_link_hash_entry *, void *), |
| 229 | void *); |
| 230 | |
| 231 | /* Add an entry to the undefs list. */ |
| 232 | extern void bfd_link_add_undef |
| 233 | (struct bfd_link_hash_table *, struct bfd_link_hash_entry *); |
| 234 | |
| 235 | /* Remove symbols from the undefs list that don't belong there. */ |
| 236 | extern void bfd_link_repair_undef_list |
| 237 | (struct bfd_link_hash_table *table); |
| 238 | |
| 239 | /* Read symbols and cache symbol pointer array in outsymbols. */ |
| 240 | extern bfd_boolean bfd_generic_link_read_symbols (bfd *); |
| 241 | |
| 242 | /* Check the relocs in the BFD. Called after all the input |
| 243 | files have been loaded, and garbage collection has tagged |
| 244 | any unneeded sections. */ |
| 245 | extern bfd_boolean bfd_link_check_relocs (bfd *,struct bfd_link_info *); |
| 246 | |
| 247 | struct bfd_sym_chain |
| 248 | { |
| 249 | struct bfd_sym_chain *next; |
| 250 | const char *name; |
| 251 | }; |
| 252 | \f |
| 253 | /* How to handle unresolved symbols. |
| 254 | There are four possibilities which are enumerated below: */ |
| 255 | enum report_method |
| 256 | { |
| 257 | /* This is the initial value when then link_info structure is created. |
| 258 | It allows the various stages of the linker to determine whether they |
| 259 | allowed to set the value. */ |
| 260 | RM_NOT_YET_SET = 0, |
| 261 | RM_IGNORE, |
| 262 | RM_GENERATE_WARNING, |
| 263 | RM_GENERATE_ERROR |
| 264 | }; |
| 265 | |
| 266 | typedef enum {with_flags, without_flags} flag_type; |
| 267 | |
| 268 | /* A section flag list. */ |
| 269 | struct flag_info_list |
| 270 | { |
| 271 | flag_type with; |
| 272 | const char *name; |
| 273 | bfd_boolean valid; |
| 274 | struct flag_info_list *next; |
| 275 | }; |
| 276 | |
| 277 | /* Section flag info. */ |
| 278 | struct flag_info |
| 279 | { |
| 280 | flagword only_with_flags; |
| 281 | flagword not_with_flags; |
| 282 | struct flag_info_list *flag_list; |
| 283 | bfd_boolean flags_initialized; |
| 284 | }; |
| 285 | |
| 286 | struct bfd_elf_dynamic_list; |
| 287 | struct bfd_elf_version_tree; |
| 288 | |
| 289 | /* Types of output. */ |
| 290 | |
| 291 | enum output_type |
| 292 | { |
| 293 | type_pde, |
| 294 | type_pie, |
| 295 | type_relocatable, |
| 296 | type_dll, |
| 297 | }; |
| 298 | |
| 299 | #define bfd_link_pde(info) ((info)->type == type_pde) |
| 300 | #define bfd_link_dll(info) ((info)->type == type_dll) |
| 301 | #define bfd_link_relocatable(info) ((info)->type == type_relocatable) |
| 302 | #define bfd_link_pie(info) ((info)->type == type_pie) |
| 303 | #define bfd_link_executable(info) (bfd_link_pde (info) || bfd_link_pie (info)) |
| 304 | #define bfd_link_pic(info) (bfd_link_dll (info) || bfd_link_pie (info)) |
| 305 | |
| 306 | /* This structure holds all the information needed to communicate |
| 307 | between BFD and the linker when doing a link. */ |
| 308 | |
| 309 | struct bfd_link_info |
| 310 | { |
| 311 | /* Output type. */ |
| 312 | ENUM_BITFIELD (output_type) type : 2; |
| 313 | |
| 314 | /* TRUE if BFD should pre-bind symbols in a shared object. */ |
| 315 | unsigned int symbolic: 1; |
| 316 | |
| 317 | /* TRUE if executable should not contain copy relocs. |
| 318 | Setting this true may result in a non-sharable text segment. */ |
| 319 | unsigned int nocopyreloc: 1; |
| 320 | |
| 321 | /* TRUE if BFD should export all symbols in the dynamic symbol table |
| 322 | of an executable, rather than only those used. */ |
| 323 | unsigned int export_dynamic: 1; |
| 324 | |
| 325 | /* TRUE if a default symbol version should be created and used for |
| 326 | exported symbols. */ |
| 327 | unsigned int create_default_symver: 1; |
| 328 | |
| 329 | /* TRUE if unreferenced sections should be removed. */ |
| 330 | unsigned int gc_sections: 1; |
| 331 | |
| 332 | /* TRUE if exported symbols should be kept during section gc. */ |
| 333 | unsigned int gc_keep_exported: 1; |
| 334 | |
| 335 | /* TRUE if every symbol should be reported back via the notice |
| 336 | callback. */ |
| 337 | unsigned int notice_all: 1; |
| 338 | |
| 339 | /* TRUE if the LTO plugin is active. */ |
| 340 | unsigned int lto_plugin_active: 1; |
| 341 | |
| 342 | /* TRUE if global symbols in discarded sections should be stripped. */ |
| 343 | unsigned int strip_discarded: 1; |
| 344 | |
| 345 | /* TRUE if all data symbols should be dynamic. */ |
| 346 | unsigned int dynamic_data: 1; |
| 347 | |
| 348 | /* TRUE if section groups should be resolved. */ |
| 349 | unsigned int resolve_section_groups: 1; |
| 350 | |
| 351 | /* Which symbols to strip. */ |
| 352 | ENUM_BITFIELD (bfd_link_strip) strip : 2; |
| 353 | |
| 354 | /* Which local symbols to discard. */ |
| 355 | ENUM_BITFIELD (bfd_link_discard) discard : 2; |
| 356 | |
| 357 | /* Whether to generate ELF common symbols with the STT_COMMON type. */ |
| 358 | ENUM_BITFIELD (bfd_link_elf_stt_common) elf_stt_common : 2; |
| 359 | |
| 360 | /* Criteria for skipping symbols when determining |
| 361 | whether to include an object from an archive. */ |
| 362 | ENUM_BITFIELD (bfd_link_common_skip_ar_symbols) common_skip_ar_symbols : 2; |
| 363 | |
| 364 | /* What to do with unresolved symbols in an object file. |
| 365 | When producing executables the default is GENERATE_ERROR. |
| 366 | When producing shared libraries the default is IGNORE. The |
| 367 | assumption with shared libraries is that the reference will be |
| 368 | resolved at load/execution time. */ |
| 369 | ENUM_BITFIELD (report_method) unresolved_syms_in_objects : 2; |
| 370 | |
| 371 | /* What to do with unresolved symbols in a shared library. |
| 372 | The same defaults apply. */ |
| 373 | ENUM_BITFIELD (report_method) unresolved_syms_in_shared_libs : 2; |
| 374 | |
| 375 | /* TRUE if shared objects should be linked directly, not shared. */ |
| 376 | unsigned int static_link: 1; |
| 377 | |
| 378 | /* TRUE if symbols should be retained in memory, FALSE if they |
| 379 | should be freed and reread. */ |
| 380 | unsigned int keep_memory: 1; |
| 381 | |
| 382 | /* TRUE if BFD should generate relocation information in the final |
| 383 | executable. */ |
| 384 | unsigned int emitrelocations: 1; |
| 385 | |
| 386 | /* TRUE if PT_GNU_RELRO segment should be created. */ |
| 387 | unsigned int relro: 1; |
| 388 | |
| 389 | /* TRUE if separate code segment should be created. */ |
| 390 | unsigned int separate_code: 1; |
| 391 | |
| 392 | /* Nonzero if .eh_frame_hdr section and PT_GNU_EH_FRAME ELF segment |
| 393 | should be created. 1 for DWARF2 tables, 2 for compact tables. */ |
| 394 | unsigned int eh_frame_hdr_type: 2; |
| 395 | |
| 396 | /* TRUE if we should warn when adding a DT_TEXTREL to a shared object. */ |
| 397 | unsigned int warn_shared_textrel: 1; |
| 398 | |
| 399 | /* TRUE if we should error when adding a DT_TEXTREL. */ |
| 400 | unsigned int error_textrel: 1; |
| 401 | |
| 402 | /* TRUE if .hash section should be created. */ |
| 403 | unsigned int emit_hash: 1; |
| 404 | |
| 405 | /* TRUE if .gnu.hash section should be created. */ |
| 406 | unsigned int emit_gnu_hash: 1; |
| 407 | |
| 408 | /* If TRUE reduce memory overheads, at the expense of speed. This will |
| 409 | cause map file generation to use an O(N^2) algorithm and disable |
| 410 | caching ELF symbol buffer. */ |
| 411 | unsigned int reduce_memory_overheads: 1; |
| 412 | |
| 413 | /* TRUE if the output file should be in a traditional format. This |
| 414 | is equivalent to the setting of the BFD_TRADITIONAL_FORMAT flag |
| 415 | on the output file, but may be checked when reading the input |
| 416 | files. */ |
| 417 | unsigned int traditional_format: 1; |
| 418 | |
| 419 | /* TRUE if non-PLT relocs should be merged into one reloc section |
| 420 | and sorted so that relocs against the same symbol come together. */ |
| 421 | unsigned int combreloc: 1; |
| 422 | |
| 423 | /* TRUE if a default symbol version should be created and used for |
| 424 | imported symbols. */ |
| 425 | unsigned int default_imported_symver: 1; |
| 426 | |
| 427 | /* TRUE if the new ELF dynamic tags are enabled. */ |
| 428 | unsigned int new_dtags: 1; |
| 429 | |
| 430 | /* FALSE if .eh_frame unwind info should be generated for PLT and other |
| 431 | linker created sections, TRUE if it should be omitted. */ |
| 432 | unsigned int no_ld_generated_unwind_info: 1; |
| 433 | |
| 434 | /* TRUE if BFD should generate a "task linked" object file, |
| 435 | similar to relocatable but also with globals converted to |
| 436 | statics. */ |
| 437 | unsigned int task_link: 1; |
| 438 | |
| 439 | /* TRUE if ok to have multiple definition. */ |
| 440 | unsigned int allow_multiple_definition: 1; |
| 441 | |
| 442 | /* TRUE if ok to have prohibit multiple definition of absolute symbols. */ |
| 443 | unsigned int prohibit_multiple_definition_absolute: 1; |
| 444 | |
| 445 | /* TRUE if ok to have version with no definition. */ |
| 446 | unsigned int allow_undefined_version: 1; |
| 447 | |
| 448 | /* TRUE if some symbols have to be dynamic, controlled by |
| 449 | --dynamic-list command line options. */ |
| 450 | unsigned int dynamic: 1; |
| 451 | |
| 452 | /* TRUE if PT_GNU_STACK segment should be created with PF_R|PF_W|PF_X |
| 453 | flags. */ |
| 454 | unsigned int execstack: 1; |
| 455 | |
| 456 | /* TRUE if PT_GNU_STACK segment should be created with PF_R|PF_W |
| 457 | flags. */ |
| 458 | unsigned int noexecstack: 1; |
| 459 | |
| 460 | /* TRUE if we want to produced optimized output files. This might |
| 461 | need much more time and therefore must be explicitly selected. */ |
| 462 | unsigned int optimize: 1; |
| 463 | |
| 464 | /* TRUE if user should be informed of removed unreferenced sections. */ |
| 465 | unsigned int print_gc_sections: 1; |
| 466 | |
| 467 | /* TRUE if we should warn alternate ELF machine code. */ |
| 468 | unsigned int warn_alternate_em: 1; |
| 469 | |
| 470 | /* TRUE if the linker script contained an explicit PHDRS command. */ |
| 471 | unsigned int user_phdrs: 1; |
| 472 | |
| 473 | /* TRUE if we should check relocations after all input files have |
| 474 | been opened. */ |
| 475 | unsigned int check_relocs_after_open_input: 1; |
| 476 | |
| 477 | /* TRUE if BND prefix in PLT entries is always generated. */ |
| 478 | unsigned int bndplt: 1; |
| 479 | |
| 480 | /* TRUE if IBT-enabled PLT entries should be generated. */ |
| 481 | unsigned int ibtplt: 1; |
| 482 | |
| 483 | /* TRUE if GNU_PROPERTY_X86_FEATURE_1_IBT should be generated. */ |
| 484 | unsigned int ibt: 1; |
| 485 | |
| 486 | /* TRUE if GNU_PROPERTY_X86_FEATURE_1_SHSTK should be generated. */ |
| 487 | unsigned int shstk: 1; |
| 488 | |
| 489 | /* TRUE if generation of .interp/PT_INTERP should be suppressed. */ |
| 490 | unsigned int nointerp: 1; |
| 491 | |
| 492 | /* TRUE if we shouldn't check relocation overflow. */ |
| 493 | unsigned int no_reloc_overflow_check: 1; |
| 494 | |
| 495 | /* TRUE if generate a 1-byte NOP as suffix for x86 call instruction. */ |
| 496 | unsigned int call_nop_as_suffix : 1; |
| 497 | |
| 498 | /* TRUE if common symbols should be treated as undefined. */ |
| 499 | unsigned int inhibit_common_definition : 1; |
| 500 | |
| 501 | /* The 1-byte NOP for x86 call instruction. */ |
| 502 | char call_nop_byte; |
| 503 | |
| 504 | /* Char that may appear as the first char of a symbol, but should be |
| 505 | skipped (like symbol_leading_char) when looking up symbols in |
| 506 | wrap_hash. Used by PowerPC Linux for 'dot' symbols. */ |
| 507 | char wrap_char; |
| 508 | |
| 509 | /* Separator between archive and filename in linker script filespecs. */ |
| 510 | char path_separator; |
| 511 | |
| 512 | /* Compress DWARF debug sections. */ |
| 513 | enum compressed_debug_section_type compress_debug; |
| 514 | |
| 515 | /* Default stack size. Zero means default (often zero itself), -1 |
| 516 | means explicitly zero-sized. */ |
| 517 | bfd_signed_vma stacksize; |
| 518 | |
| 519 | /* Enable or disable target specific optimizations. |
| 520 | |
| 521 | Not all targets have optimizations to enable. |
| 522 | |
| 523 | Normally these optimizations are disabled by default but some targets |
| 524 | prefer to enable them by default. So this field is a tri-state variable. |
| 525 | The values are: |
| 526 | |
| 527 | zero: Enable the optimizations (either from --relax being specified on |
| 528 | the command line or the backend's before_allocation emulation function. |
| 529 | |
| 530 | positive: The user has requested that these optimizations be disabled. |
| 531 | (Via the --no-relax command line option). |
| 532 | |
| 533 | negative: The optimizations are disabled. (Set when initializing the |
| 534 | args_type structure in ldmain.c:main. */ |
| 535 | signed int disable_target_specific_optimizations; |
| 536 | |
| 537 | /* Function callbacks. */ |
| 538 | const struct bfd_link_callbacks *callbacks; |
| 539 | |
| 540 | /* Hash table handled by BFD. */ |
| 541 | struct bfd_link_hash_table *hash; |
| 542 | |
| 543 | /* Hash table of symbols to keep. This is NULL unless strip is |
| 544 | strip_some. */ |
| 545 | struct bfd_hash_table *keep_hash; |
| 546 | |
| 547 | /* Hash table of symbols to report back via the notice callback. If |
| 548 | this is NULL, and notice_all is FALSE, then no symbols are |
| 549 | reported back. */ |
| 550 | struct bfd_hash_table *notice_hash; |
| 551 | |
| 552 | /* Hash table of symbols which are being wrapped (the --wrap linker |
| 553 | option). If this is NULL, no symbols are being wrapped. */ |
| 554 | struct bfd_hash_table *wrap_hash; |
| 555 | |
| 556 | /* Hash table of symbols which may be left unresolved during |
| 557 | a link. If this is NULL, no symbols can be left unresolved. */ |
| 558 | struct bfd_hash_table *ignore_hash; |
| 559 | |
| 560 | /* The output BFD. */ |
| 561 | bfd *output_bfd; |
| 562 | |
| 563 | /* The import library generated. */ |
| 564 | bfd *out_implib_bfd; |
| 565 | |
| 566 | /* The list of input BFD's involved in the link. These are chained |
| 567 | together via the link.next field. */ |
| 568 | bfd *input_bfds; |
| 569 | bfd **input_bfds_tail; |
| 570 | |
| 571 | /* If a symbol should be created for each input BFD, this is section |
| 572 | where those symbols should be placed. It must be a section in |
| 573 | the output BFD. It may be NULL, in which case no such symbols |
| 574 | will be created. This is to support CREATE_OBJECT_SYMBOLS in the |
| 575 | linker command language. */ |
| 576 | asection *create_object_symbols_section; |
| 577 | |
| 578 | /* List of global symbol names that are starting points for marking |
| 579 | sections against garbage collection. */ |
| 580 | struct bfd_sym_chain *gc_sym_list; |
| 581 | |
| 582 | /* If a base output file is wanted, then this points to it */ |
| 583 | void *base_file; |
| 584 | |
| 585 | /* The function to call when the executable or shared object is |
| 586 | loaded. */ |
| 587 | const char *init_function; |
| 588 | |
| 589 | /* The function to call when the executable or shared object is |
| 590 | unloaded. */ |
| 591 | const char *fini_function; |
| 592 | |
| 593 | /* Number of relaxation passes. Usually only one relaxation pass |
| 594 | is needed. But a backend can have as many relaxation passes as |
| 595 | necessary. During bfd_relax_section call, it is set to the |
| 596 | current pass, starting from 0. */ |
| 597 | int relax_pass; |
| 598 | |
| 599 | /* Number of relaxation trips. This number is incremented every |
| 600 | time the relaxation pass is restarted due to a previous |
| 601 | relaxation returning true in *AGAIN. */ |
| 602 | int relax_trip; |
| 603 | |
| 604 | /* > 0 to treat protected data defined in the shared library as |
| 605 | reference external. 0 to treat it as internal. -1 to let |
| 606 | backend to decide. */ |
| 607 | int extern_protected_data; |
| 608 | |
| 609 | /* 1 to make undefined weak symbols dynamic when building a dynamic |
| 610 | object. 0 to resolve undefined weak symbols to zero. -1 to let |
| 611 | the backend decide. */ |
| 612 | int dynamic_undefined_weak; |
| 613 | |
| 614 | /* Non-zero if auto-import thunks for DATA items in pei386 DLLs |
| 615 | should be generated/linked against. Set to 1 if this feature |
| 616 | is explicitly requested by the user, -1 if enabled by default. */ |
| 617 | int pei386_auto_import; |
| 618 | |
| 619 | /* Non-zero if runtime relocs for DATA items with non-zero addends |
| 620 | in pei386 DLLs should be generated. Set to 1 if this feature |
| 621 | is explicitly requested by the user, -1 if enabled by default. */ |
| 622 | int pei386_runtime_pseudo_reloc; |
| 623 | |
| 624 | /* How many spare .dynamic DT_NULL entries should be added? */ |
| 625 | unsigned int spare_dynamic_tags; |
| 626 | |
| 627 | /* May be used to set DT_FLAGS for ELF. */ |
| 628 | bfd_vma flags; |
| 629 | |
| 630 | /* May be used to set DT_FLAGS_1 for ELF. */ |
| 631 | bfd_vma flags_1; |
| 632 | |
| 633 | /* Start and end of RELRO region. */ |
| 634 | bfd_vma relro_start, relro_end; |
| 635 | |
| 636 | /* List of symbols should be dynamic. */ |
| 637 | struct bfd_elf_dynamic_list *dynamic_list; |
| 638 | |
| 639 | /* The version information. */ |
| 640 | struct bfd_elf_version_tree *version_info; |
| 641 | }; |
| 642 | |
| 643 | /* This structures holds a set of callback functions. These are called |
| 644 | by the BFD linker routines. */ |
| 645 | |
| 646 | struct bfd_link_callbacks |
| 647 | { |
| 648 | /* A function which is called when an object is added from an |
| 649 | archive. ABFD is the archive element being added. NAME is the |
| 650 | name of the symbol which caused the archive element to be pulled |
| 651 | in. This function may set *SUBSBFD to point to an alternative |
| 652 | BFD from which symbols should in fact be added in place of the |
| 653 | original BFD's symbols. Returns TRUE if the object should be |
| 654 | added, FALSE if it should be skipped. */ |
| 655 | bfd_boolean (*add_archive_element) |
| 656 | (struct bfd_link_info *, bfd *abfd, const char *name, bfd **subsbfd); |
| 657 | /* A function which is called when a symbol is found with multiple |
| 658 | definitions. H is the symbol which is defined multiple times. |
| 659 | NBFD is the new BFD, NSEC is the new section, and NVAL is the new |
| 660 | value. NSEC may be bfd_com_section or bfd_ind_section. */ |
| 661 | void (*multiple_definition) |
| 662 | (struct bfd_link_info *, struct bfd_link_hash_entry *h, |
| 663 | bfd *nbfd, asection *nsec, bfd_vma nval); |
| 664 | /* A function which is called when a common symbol is defined |
| 665 | multiple times. H is the symbol appearing multiple times. |
| 666 | NBFD is the BFD of the new symbol. NTYPE is the type of the new |
| 667 | symbol, one of bfd_link_hash_defined, bfd_link_hash_common, or |
| 668 | bfd_link_hash_indirect. If NTYPE is bfd_link_hash_common, NSIZE |
| 669 | is the size of the new symbol. */ |
| 670 | void (*multiple_common) |
| 671 | (struct bfd_link_info *, struct bfd_link_hash_entry *h, |
| 672 | bfd *nbfd, enum bfd_link_hash_type ntype, bfd_vma nsize); |
| 673 | /* A function which is called to add a symbol to a set. ENTRY is |
| 674 | the link hash table entry for the set itself (e.g., |
| 675 | __CTOR_LIST__). RELOC is the relocation to use for an entry in |
| 676 | the set when generating a relocatable file, and is also used to |
| 677 | get the size of the entry when generating an executable file. |
| 678 | ABFD, SEC and VALUE identify the value to add to the set. */ |
| 679 | void (*add_to_set) |
| 680 | (struct bfd_link_info *, struct bfd_link_hash_entry *entry, |
| 681 | bfd_reloc_code_real_type reloc, bfd *abfd, asection *sec, bfd_vma value); |
| 682 | /* A function which is called when the name of a g++ constructor or |
| 683 | destructor is found. This is only called by some object file |
| 684 | formats. CONSTRUCTOR is TRUE for a constructor, FALSE for a |
| 685 | destructor. This will use BFD_RELOC_CTOR when generating a |
| 686 | relocatable file. NAME is the name of the symbol found. ABFD, |
| 687 | SECTION and VALUE are the value of the symbol. */ |
| 688 | void (*constructor) |
| 689 | (struct bfd_link_info *, bfd_boolean constructor, const char *name, |
| 690 | bfd *abfd, asection *sec, bfd_vma value); |
| 691 | /* A function which is called to issue a linker warning. For |
| 692 | example, this is called when there is a reference to a warning |
| 693 | symbol. WARNING is the warning to be issued. SYMBOL is the name |
| 694 | of the symbol which triggered the warning; it may be NULL if |
| 695 | there is none. ABFD, SECTION and ADDRESS identify the location |
| 696 | which trigerred the warning; either ABFD or SECTION or both may |
| 697 | be NULL if the location is not known. */ |
| 698 | void (*warning) |
| 699 | (struct bfd_link_info *, const char *warning, const char *symbol, |
| 700 | bfd *abfd, asection *section, bfd_vma address); |
| 701 | /* A function which is called when a relocation is attempted against |
| 702 | an undefined symbol. NAME is the symbol which is undefined. |
| 703 | ABFD, SECTION and ADDRESS identify the location from which the |
| 704 | reference is made. IS_FATAL indicates whether an undefined symbol is |
| 705 | a fatal error or not. In some cases SECTION may be NULL. */ |
| 706 | void (*undefined_symbol) |
| 707 | (struct bfd_link_info *, const char *name, bfd *abfd, |
| 708 | asection *section, bfd_vma address, bfd_boolean is_fatal); |
| 709 | /* A function which is called when a reloc overflow occurs. ENTRY is |
| 710 | the link hash table entry for the symbol the reloc is against. |
| 711 | NAME is the name of the local symbol or section the reloc is |
| 712 | against, RELOC_NAME is the name of the relocation, and ADDEND is |
| 713 | any addend that is used. ABFD, SECTION and ADDRESS identify the |
| 714 | location at which the overflow occurs; if this is the result of a |
| 715 | bfd_section_reloc_link_order or bfd_symbol_reloc_link_order, then |
| 716 | ABFD will be NULL. */ |
| 717 | void (*reloc_overflow) |
| 718 | (struct bfd_link_info *, struct bfd_link_hash_entry *entry, |
| 719 | const char *name, const char *reloc_name, bfd_vma addend, |
| 720 | bfd *abfd, asection *section, bfd_vma address); |
| 721 | /* A function which is called when a dangerous reloc is performed. |
| 722 | MESSAGE is an appropriate message. |
| 723 | ABFD, SECTION and ADDRESS identify the location at which the |
| 724 | problem occurred; if this is the result of a |
| 725 | bfd_section_reloc_link_order or bfd_symbol_reloc_link_order, then |
| 726 | ABFD will be NULL. */ |
| 727 | void (*reloc_dangerous) |
| 728 | (struct bfd_link_info *, const char *message, |
| 729 | bfd *abfd, asection *section, bfd_vma address); |
| 730 | /* A function which is called when a reloc is found to be attached |
| 731 | to a symbol which is not being written out. NAME is the name of |
| 732 | the symbol. ABFD, SECTION and ADDRESS identify the location of |
| 733 | the reloc; if this is the result of a |
| 734 | bfd_section_reloc_link_order or bfd_symbol_reloc_link_order, then |
| 735 | ABFD will be NULL. */ |
| 736 | void (*unattached_reloc) |
| 737 | (struct bfd_link_info *, const char *name, |
| 738 | bfd *abfd, asection *section, bfd_vma address); |
| 739 | /* A function which is called when a symbol in notice_hash is |
| 740 | defined or referenced. H is the symbol, INH the indirect symbol |
| 741 | if applicable. ABFD, SECTION and ADDRESS are the (new) value of |
| 742 | the symbol. If SECTION is bfd_und_section, this is a reference. |
| 743 | FLAGS are the symbol BSF_* flags. */ |
| 744 | bfd_boolean (*notice) |
| 745 | (struct bfd_link_info *, struct bfd_link_hash_entry *h, |
| 746 | struct bfd_link_hash_entry *inh, |
| 747 | bfd *abfd, asection *section, bfd_vma address, flagword flags); |
| 748 | /* Error or warning link info message. */ |
| 749 | void (*einfo) |
| 750 | (const char *fmt, ...); |
| 751 | /* General link info message. */ |
| 752 | void (*info) |
| 753 | (const char *fmt, ...); |
| 754 | /* Message to be printed in linker map file. */ |
| 755 | void (*minfo) |
| 756 | (const char *fmt, ...); |
| 757 | /* This callback provides a chance for users of the BFD library to |
| 758 | override its decision about whether to place two adjacent sections |
| 759 | into the same segment. */ |
| 760 | bfd_boolean (*override_segment_assignment) |
| 761 | (struct bfd_link_info *, bfd * abfd, |
| 762 | asection * current_section, asection * previous_section, |
| 763 | bfd_boolean new_segment); |
| 764 | }; |
| 765 | \f |
| 766 | /* The linker builds link_order structures which tell the code how to |
| 767 | include input data in the output file. */ |
| 768 | |
| 769 | /* These are the types of link_order structures. */ |
| 770 | |
| 771 | enum bfd_link_order_type |
| 772 | { |
| 773 | bfd_undefined_link_order, /* Undefined. */ |
| 774 | bfd_indirect_link_order, /* Built from a section. */ |
| 775 | bfd_data_link_order, /* Set to explicit data. */ |
| 776 | bfd_section_reloc_link_order, /* Relocate against a section. */ |
| 777 | bfd_symbol_reloc_link_order /* Relocate against a symbol. */ |
| 778 | }; |
| 779 | |
| 780 | /* This is the link_order structure itself. These form a chain |
| 781 | attached to the output section whose contents they are describing. */ |
| 782 | |
| 783 | struct bfd_link_order |
| 784 | { |
| 785 | /* Next link_order in chain. */ |
| 786 | struct bfd_link_order *next; |
| 787 | /* Type of link_order. */ |
| 788 | enum bfd_link_order_type type; |
| 789 | /* Offset within output section. */ |
| 790 | bfd_vma offset; |
| 791 | /* Size within output section. */ |
| 792 | bfd_size_type size; |
| 793 | /* Type specific information. */ |
| 794 | union |
| 795 | { |
| 796 | struct |
| 797 | { |
| 798 | /* Section to include. If this is used, then |
| 799 | section->output_section must be the section the |
| 800 | link_order is attached to, section->output_offset must |
| 801 | equal the link_order offset field, and section->size |
| 802 | must equal the link_order size field. Maybe these |
| 803 | restrictions should be relaxed someday. */ |
| 804 | asection *section; |
| 805 | } indirect; |
| 806 | struct |
| 807 | { |
| 808 | /* Size of contents, or zero when contents should be filled by |
| 809 | the architecture-dependent fill function. |
| 810 | A non-zero value allows filling of the output section |
| 811 | with an arbitrary repeated pattern. */ |
| 812 | unsigned int size; |
| 813 | /* Data to put into file. */ |
| 814 | bfd_byte *contents; |
| 815 | } data; |
| 816 | struct |
| 817 | { |
| 818 | /* Description of reloc to generate. Used for |
| 819 | bfd_section_reloc_link_order and |
| 820 | bfd_symbol_reloc_link_order. */ |
| 821 | struct bfd_link_order_reloc *p; |
| 822 | } reloc; |
| 823 | } u; |
| 824 | }; |
| 825 | |
| 826 | /* A linker order of type bfd_section_reloc_link_order or |
| 827 | bfd_symbol_reloc_link_order means to create a reloc against a |
| 828 | section or symbol, respectively. This is used to implement -Ur to |
| 829 | generate relocs for the constructor tables. The |
| 830 | bfd_link_order_reloc structure describes the reloc that BFD should |
| 831 | create. It is similar to a arelent, but I didn't use arelent |
| 832 | because the linker does not know anything about most symbols, and |
| 833 | any asymbol structure it creates will be partially meaningless. |
| 834 | This information could logically be in the bfd_link_order struct, |
| 835 | but I didn't want to waste the space since these types of relocs |
| 836 | are relatively rare. */ |
| 837 | |
| 838 | struct bfd_link_order_reloc |
| 839 | { |
| 840 | /* Reloc type. */ |
| 841 | bfd_reloc_code_real_type reloc; |
| 842 | |
| 843 | union |
| 844 | { |
| 845 | /* For type bfd_section_reloc_link_order, this is the section |
| 846 | the reloc should be against. This must be a section in the |
| 847 | output BFD, not any of the input BFDs. */ |
| 848 | asection *section; |
| 849 | /* For type bfd_symbol_reloc_link_order, this is the name of the |
| 850 | symbol the reloc should be against. */ |
| 851 | const char *name; |
| 852 | } u; |
| 853 | |
| 854 | /* Addend to use. The object file should contain zero. The BFD |
| 855 | backend is responsible for filling in the contents of the object |
| 856 | file correctly. For some object file formats (e.g., COFF) the |
| 857 | addend must be stored into in the object file, and for some |
| 858 | (e.g., SPARC a.out) it is kept in the reloc. */ |
| 859 | bfd_vma addend; |
| 860 | }; |
| 861 | |
| 862 | /* Allocate a new link_order for a section. */ |
| 863 | extern struct bfd_link_order *bfd_new_link_order (bfd *, asection *); |
| 864 | |
| 865 | /* These structures are used to describe version information for the |
| 866 | ELF linker. These structures could be manipulated entirely inside |
| 867 | BFD, but it would be a pain. Instead, the regular linker sets up |
| 868 | these structures, and then passes them into BFD. */ |
| 869 | |
| 870 | /* Glob pattern for a version. */ |
| 871 | |
| 872 | struct bfd_elf_version_expr |
| 873 | { |
| 874 | /* Next glob pattern for this version. */ |
| 875 | struct bfd_elf_version_expr *next; |
| 876 | /* Glob pattern. */ |
| 877 | const char *pattern; |
| 878 | /* Set if pattern is not a glob. */ |
| 879 | unsigned int literal : 1; |
| 880 | /* Defined by ".symver". */ |
| 881 | unsigned int symver : 1; |
| 882 | /* Defined by version script. */ |
| 883 | unsigned int script : 1; |
| 884 | /* Pattern type. */ |
| 885 | #define BFD_ELF_VERSION_C_TYPE 1 |
| 886 | #define BFD_ELF_VERSION_CXX_TYPE 2 |
| 887 | #define BFD_ELF_VERSION_JAVA_TYPE 4 |
| 888 | unsigned int mask : 3; |
| 889 | }; |
| 890 | |
| 891 | struct bfd_elf_version_expr_head |
| 892 | { |
| 893 | /* List of all patterns, both wildcards and non-wildcards. */ |
| 894 | struct bfd_elf_version_expr *list; |
| 895 | /* Hash table for non-wildcards. */ |
| 896 | void *htab; |
| 897 | /* Remaining patterns. */ |
| 898 | struct bfd_elf_version_expr *remaining; |
| 899 | /* What kind of pattern types are present in list (bitmask). */ |
| 900 | unsigned int mask; |
| 901 | }; |
| 902 | |
| 903 | /* Version dependencies. */ |
| 904 | |
| 905 | struct bfd_elf_version_deps |
| 906 | { |
| 907 | /* Next dependency for this version. */ |
| 908 | struct bfd_elf_version_deps *next; |
| 909 | /* The version which this version depends upon. */ |
| 910 | struct bfd_elf_version_tree *version_needed; |
| 911 | }; |
| 912 | |
| 913 | /* A node in the version tree. */ |
| 914 | |
| 915 | struct bfd_elf_version_tree |
| 916 | { |
| 917 | /* Next version. */ |
| 918 | struct bfd_elf_version_tree *next; |
| 919 | /* Name of this version. */ |
| 920 | const char *name; |
| 921 | /* Version number. */ |
| 922 | unsigned int vernum; |
| 923 | /* Regular expressions for global symbols in this version. */ |
| 924 | struct bfd_elf_version_expr_head globals; |
| 925 | /* Regular expressions for local symbols in this version. */ |
| 926 | struct bfd_elf_version_expr_head locals; |
| 927 | /* List of versions which this version depends upon. */ |
| 928 | struct bfd_elf_version_deps *deps; |
| 929 | /* Index of the version name. This is used within BFD. */ |
| 930 | unsigned int name_indx; |
| 931 | /* Whether this version tree was used. This is used within BFD. */ |
| 932 | int used; |
| 933 | /* Matching hook. */ |
| 934 | struct bfd_elf_version_expr *(*match) |
| 935 | (struct bfd_elf_version_expr_head *head, |
| 936 | struct bfd_elf_version_expr *prev, const char *sym); |
| 937 | }; |
| 938 | |
| 939 | struct bfd_elf_dynamic_list |
| 940 | { |
| 941 | struct bfd_elf_version_expr_head head; |
| 942 | struct bfd_elf_version_expr *(*match) |
| 943 | (struct bfd_elf_version_expr_head *head, |
| 944 | struct bfd_elf_version_expr *prev, const char *sym); |
| 945 | }; |
| 946 | |
| 947 | #endif |