1 /* bfdlink.h -- header file for BFD link routines 2 Copyright 1993, 94, 95, 96, 97, 1999 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 2 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., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */ 20 21 #ifndef BFDLINK_H 22 #define BFDLINK_H 23 24 /* Which symbols to strip during a link. */ 25 enum bfd_link_strip 26 { 27 strip_none, /* Don't strip any symbols. */ 28 strip_debugger, /* Strip debugging symbols. */ 29 strip_some, /* keep_hash is the list of symbols to keep. */ 30 strip_all /* Strip all symbols. */ 31 }; 32 33 /* Which local symbols to discard during a link. This is irrelevant 34 if strip_all is used. */ 35 enum bfd_link_discard 36 { 37 discard_none, /* Don't discard any locals. */ 38 discard_l, /* Discard local temporary symbols. */ 39 discard_all /* Discard all locals. */ 40 }; 41 42 /* These are the possible types of an entry in the BFD link hash 43 table. */ 44 45 enum bfd_link_hash_type 46 { 47 bfd_link_hash_new, /* Symbol is new. */ 48 bfd_link_hash_undefined, /* Symbol seen before, but undefined. */ 49 bfd_link_hash_undefweak, /* Symbol is weak and undefined. */ 50 bfd_link_hash_defined, /* Symbol is defined. */ 51 bfd_link_hash_defweak, /* Symbol is weak and defined. */ 52 bfd_link_hash_common, /* Symbol is common. */ 53 bfd_link_hash_indirect, /* Symbol is an indirect link. */ 54 bfd_link_hash_warning /* Like indirect, but warn if referenced. */ 55 }; 56 57 /* The linking routines use a hash table which uses this structure for 58 its elements. */ 59 60 struct bfd_link_hash_entry 61 { 62 /* Base hash table entry structure. */ 63 struct bfd_hash_entry root; 64 /* Type of this entry. */ 65 enum bfd_link_hash_type type; 66 67 /* Undefined and common symbols are kept in a linked list through 68 this field. This field is not in the union because that would 69 force us to remove entries from the list when we changed their 70 type, which would force the list to be doubly linked, which would 71 waste more memory. When an undefined or common symbol is 72 created, it should be added to this list, the head of which is in 73 the link hash table itself. As symbols are defined, they need 74 not be removed from the list; anything which reads the list must 75 doublecheck the symbol type. 76 77 Weak symbols are not kept on this list. 78 79 Defined and defweak symbols use this field as a reference marker. 80 If the field is not NULL, or this structure is the tail of the 81 undefined symbol list, the symbol has been referenced. If the 82 symbol is undefined and becomes defined, this field will 83 automatically be non-NULL since the symbol will have been on the 84 undefined symbol list. */ 85 struct bfd_link_hash_entry *next; 86 /* A union of information depending upon the type. */ 87 union 88 { 89 /* Nothing is kept for bfd_hash_new. */ 90 /* bfd_link_hash_undefined, bfd_link_hash_undefweak. */ 91 struct 92 { 93 bfd *abfd; /* BFD symbol was found in. */ 94 } undef; 95 /* bfd_link_hash_defined, bfd_link_hash_defweak. */ 96 struct 97 { 98 bfd_vma value; /* Symbol value. */ 99 asection *section; /* Symbol section. */ 100 } def; 101 /* bfd_link_hash_indirect, bfd_link_hash_warning. */ 102 struct 103 { 104 struct bfd_link_hash_entry *link; /* Real symbol. */ 105 const char *warning; /* Warning (bfd_link_hash_warning only). */ 106 } i; 107 /* bfd_link_hash_common. */ 108 struct 109 { 110 /* The linker needs to know three things about common 111 symbols: the size, the alignment, and the section in 112 which the symbol should be placed. We store the size 113 here, and we allocate a small structure to hold the 114 section and the alignment. The alignment is stored as a 115 power of two. We don't store all the information 116 directly because we don't want to increase the size of 117 the union; this structure is a major space user in the 118 linker. */ 119 bfd_size_type size; /* Common symbol size. */ 120 struct bfd_link_hash_common_entry 121 { 122 unsigned int alignment_power; /* Alignment. */ 123 asection *section; /* Symbol section. */ 124 } *p; 125 } c; 126 } u; 127 }; 128 129 /* This is the link hash table. It is a derived class of 130 bfd_hash_table. */ 131 132 struct bfd_link_hash_table 133 { 134 /* The hash table itself. */ 135 struct bfd_hash_table table; 136 /* The back end which created this hash table. This indicates the 137 type of the entries in the hash table, which is sometimes 138 important information when linking object files of different 139 types together. */ 140 const bfd_target *creator; 141 /* A linked list of undefined and common symbols, linked through the 142 next field in the bfd_link_hash_entry structure. */ 143 struct bfd_link_hash_entry *undefs; 144 /* Entries are added to the tail of the undefs list. */ 145 struct bfd_link_hash_entry *undefs_tail; 146 }; 147 148 /* Look up an entry in a link hash table. If FOLLOW is true, this 149 follows bfd_link_hash_indirect and bfd_link_hash_warning links to 150 the real symbol. */ 151 extern struct bfd_link_hash_entry *bfd_link_hash_lookup 152 PARAMS ((struct bfd_link_hash_table *, const char *, boolean create, 153 boolean copy, boolean follow)); 154 155 /* Look up an entry in the main linker hash table if the symbol might 156 be wrapped. This should only be used for references to an 157 undefined symbol, not for definitions of a symbol. */ 158 159 extern struct bfd_link_hash_entry *bfd_wrapped_link_hash_lookup 160 PARAMS ((bfd *, struct bfd_link_info *, const char *, boolean, boolean, 161 boolean)); 162 163 /* Traverse a link hash table. */ 164 extern void bfd_link_hash_traverse 165 PARAMS ((struct bfd_link_hash_table *, 166 boolean (*) (struct bfd_link_hash_entry *, PTR), 167 PTR)); 168 169 /* Add an entry to the undefs list. */ 170 extern void bfd_link_add_undef 171 PARAMS ((struct bfd_link_hash_table *, struct bfd_link_hash_entry *)); 172 173 /* This structure holds all the information needed to communicate 174 between BFD and the linker when doing a link. */ 175 176 struct bfd_link_info 177 { 178 /* Function callbacks. */ 179 const struct bfd_link_callbacks *callbacks; 180 /* true if BFD should generate a relocateable object file. */ 181 boolean relocateable; 182 /* true if BFD should generate a "task linked" object file, 183 similar to relocatable but also with globals converted to statics. */ 184 boolean task_link; 185 /* true if BFD should generate a shared object. */ 186 boolean shared; 187 /* true if BFD should pre-bind symbols in a shared object. */ 188 boolean symbolic; 189 /* true if shared objects should be linked directly, not shared. */ 190 boolean static_link; 191 /* true if the output file should be in a traditional format. This 192 is equivalent to the setting of the BFD_TRADITIONAL_FORMAT flag 193 on the output file, but may be checked when reading the input 194 files. */ 195 boolean traditional_format; 196 /* true if we want to produced optimized output files. This might 197 need much more time and therefore must be explicitly selected. */ 198 boolean optimize; 199 /* true if BFD should generate errors for undefined symbols 200 even if generating a shared object. */ 201 boolean no_undefined; 202 /* Which symbols to strip. */ 203 enum bfd_link_strip strip; 204 /* Which local symbols to discard. */ 205 enum bfd_link_discard discard; 206 /* true if symbols should be retained in memory, false if they 207 should be freed and reread. */ 208 boolean keep_memory; 209 /* The list of input BFD's involved in the link. These are chained 210 together via the link_next field. */ 211 bfd *input_bfds; 212 /* If a symbol should be created for each input BFD, this is section 213 where those symbols should be placed. It must be a section in 214 the output BFD. It may be NULL, in which case no such symbols 215 will be created. This is to support CREATE_OBJECT_SYMBOLS in the 216 linker command language. */ 217 asection *create_object_symbols_section; 218 /* Hash table handled by BFD. */ 219 struct bfd_link_hash_table *hash; 220 /* Hash table of symbols to keep. This is NULL unless strip is 221 strip_some. */ 222 struct bfd_hash_table *keep_hash; 223 /* true if every symbol should be reported back via the notice 224 callback. */ 225 boolean notice_all; 226 /* Hash table of symbols to report back via the notice callback. If 227 this is NULL, and notice_all is false, then no symbols are 228 reported back. */ 229 struct bfd_hash_table *notice_hash; 230 /* Hash table of symbols which are being wrapped (the --wrap linker 231 option). If this is NULL, no symbols are being wrapped. */ 232 struct bfd_hash_table *wrap_hash; 233 /* If a base output file is wanted, then this points to it */ 234 PTR base_file; 235 236 /* If non-zero, specifies that branches which are problematic for the 237 MPC860 C0 (or earlier) should be checked for and modified. It gives the 238 number of bytes that should be checked at the end of each text page. */ 239 int mpc860c0; 240 241 /* The function to call when the executable or shared object is 242 loaded. */ 243 const char *init_function; 244 /* The function to call when the executable or shared object is 245 unloaded. */ 246 const char *fini_function; 247 }; 248 249 /* This structures holds a set of callback functions. These are 250 called by the BFD linker routines. The first argument to each 251 callback function is the bfd_link_info structure being used. Each 252 function returns a boolean value. If the function returns false, 253 then the BFD function which called it will return with a failure 254 indication. */ 255 256 struct bfd_link_callbacks 257 { 258 /* A function which is called when an object is added from an 259 archive. ABFD is the archive element being added. NAME is the 260 name of the symbol which caused the archive element to be pulled 261 in. */ 262 boolean (*add_archive_element) PARAMS ((struct bfd_link_info *, 263 bfd *abfd, 264 const char *name)); 265 /* A function which is called when a symbol is found with multiple 266 definitions. NAME is the symbol which is defined multiple times. 267 OBFD is the old BFD, OSEC is the old section, OVAL is the old 268 value, NBFD is the new BFD, NSEC is the new section, and NVAL is 269 the new value. OBFD may be NULL. OSEC and NSEC may be 270 bfd_com_section or bfd_ind_section. */ 271 boolean (*multiple_definition) PARAMS ((struct bfd_link_info *, 272 const char *name, 273 bfd *obfd, 274 asection *osec, 275 bfd_vma oval, 276 bfd *nbfd, 277 asection *nsec, 278 bfd_vma nval)); 279 /* A function which is called when a common symbol is defined 280 multiple times. NAME is the symbol appearing multiple times. 281 OBFD is the BFD of the existing symbol; it may be NULL if this is 282 not known. OTYPE is the type of the existing symbol, which may 283 be bfd_link_hash_defined, bfd_link_hash_defweak, 284 bfd_link_hash_common, or bfd_link_hash_indirect. If OTYPE is 285 bfd_link_hash_common, OSIZE is the size of the existing symbol. 286 NBFD is the BFD of the new symbol. NTYPE is the type of the new 287 symbol, one of bfd_link_hash_defined, bfd_link_hash_common, or 288 bfd_link_hash_indirect. If NTYPE is bfd_link_hash_common, NSIZE 289 is the size of the new symbol. */ 290 boolean (*multiple_common) PARAMS ((struct bfd_link_info *, 291 const char *name, 292 bfd *obfd, 293 enum bfd_link_hash_type otype, 294 bfd_vma osize, 295 bfd *nbfd, 296 enum bfd_link_hash_type ntype, 297 bfd_vma nsize)); 298 /* A function which is called to add a symbol to a set. ENTRY is 299 the link hash table entry for the set itself (e.g., 300 __CTOR_LIST__). RELOC is the relocation to use for an entry in 301 the set when generating a relocateable file, and is also used to 302 get the size of the entry when generating an executable file. 303 ABFD, SEC and VALUE identify the value to add to the set. */ 304 boolean (*add_to_set) PARAMS ((struct bfd_link_info *, 305 struct bfd_link_hash_entry *entry, 306 bfd_reloc_code_real_type reloc, 307 bfd *abfd, asection *sec, bfd_vma value)); 308 /* A function which is called when the name of a g++ constructor or 309 destructor is found. This is only called by some object file 310 formats. CONSTRUCTOR is true for a constructor, false for a 311 destructor. This will use BFD_RELOC_CTOR when generating a 312 relocateable file. NAME is the name of the symbol found. ABFD, 313 SECTION and VALUE are the value of the symbol. */ 314 boolean (*constructor) PARAMS ((struct bfd_link_info *, 315 boolean constructor, 316 const char *name, bfd *abfd, asection *sec, 317 bfd_vma value)); 318 /* A function which is called to issue a linker warning. For 319 example, this is called when there is a reference to a warning 320 symbol. WARNING is the warning to be issued. SYMBOL is the name 321 of the symbol which triggered the warning; it may be NULL if 322 there is none. ABFD, SECTION and ADDRESS identify the location 323 which trigerred the warning; either ABFD or SECTION or both may 324 be NULL if the location is not known. */ 325 boolean (*warning) PARAMS ((struct bfd_link_info *, 326 const char *warning, const char *symbol, 327 bfd *abfd, asection *section, 328 bfd_vma address)); 329 /* A function which is called when a relocation is attempted against 330 an undefined symbol. NAME is the symbol which is undefined. 331 ABFD, SECTION and ADDRESS identify the location from which the 332 reference is made. FATAL indicates whether an undefined symbol is 333 a fatal error or not. In some cases SECTION may be NULL. */ 334 boolean (*undefined_symbol) PARAMS ((struct bfd_link_info *, 335 const char *name, bfd *abfd, 336 asection *section, 337 bfd_vma address, 338 boolean fatal)); 339 /* A function which is called when a reloc overflow occurs. NAME is 340 the name of the symbol or section the reloc is against, 341 RELOC_NAME is the name of the relocation, and ADDEND is any 342 addend that is used. ABFD, SECTION and ADDRESS identify the 343 location at which the overflow occurs; if this is the result of a 344 bfd_section_reloc_link_order or bfd_symbol_reloc_link_order, then 345 ABFD will be NULL. */ 346 boolean (*reloc_overflow) PARAMS ((struct bfd_link_info *, 347 const char *name, 348 const char *reloc_name, bfd_vma addend, 349 bfd *abfd, asection *section, 350 bfd_vma address)); 351 /* A function which is called when a dangerous reloc is performed. 352 The canonical example is an a29k IHCONST reloc which does not 353 follow an IHIHALF reloc. MESSAGE is an appropriate message. 354 ABFD, SECTION and ADDRESS identify the location at which the 355 problem occurred; if this is the result of a 356 bfd_section_reloc_link_order or bfd_symbol_reloc_link_order, then 357 ABFD will be NULL. */ 358 boolean (*reloc_dangerous) PARAMS ((struct bfd_link_info *, 359 const char *message, 360 bfd *abfd, asection *section, 361 bfd_vma address)); 362 /* A function which is called when a reloc is found to be attached 363 to a symbol which is not being written out. NAME is the name of 364 the symbol. ABFD, SECTION and ADDRESS identify the location of 365 the reloc; if this is the result of a 366 bfd_section_reloc_link_order or bfd_symbol_reloc_link_order, then 367 ABFD will be NULL. */ 368 boolean (*unattached_reloc) PARAMS ((struct bfd_link_info *, 369 const char *name, 370 bfd *abfd, asection *section, 371 bfd_vma address)); 372 /* A function which is called when a symbol in notice_hash is 373 defined or referenced. NAME is the symbol. ABFD, SECTION and 374 ADDRESS are the value of the symbol. If SECTION is 375 bfd_und_section, this is a reference. */ 376 boolean (*notice) PARAMS ((struct bfd_link_info *, const char *name, 377 bfd *abfd, asection *section, bfd_vma address)); 378 }; 379 380 /* The linker builds link_order structures which tell the code how to 381 include input data in the output file. */ 382 383 /* These are the types of link_order structures. */ 384 385 enum bfd_link_order_type 386 { 387 bfd_undefined_link_order, /* Undefined. */ 388 bfd_indirect_link_order, /* Built from a section. */ 389 bfd_fill_link_order, /* Fill with a 16 bit constant. */ 390 bfd_data_link_order, /* Set to explicit data. */ 391 bfd_section_reloc_link_order, /* Relocate against a section. */ 392 bfd_symbol_reloc_link_order /* Relocate against a symbol. */ 393 }; 394 395 /* This is the link_order structure itself. These form a chain 396 attached to the section whose contents they are describing. */ 397 398 struct bfd_link_order 399 { 400 /* Next link_order in chain. */ 401 struct bfd_link_order *next; 402 /* Type of link_order. */ 403 enum bfd_link_order_type type; 404 /* Offset within output section. */ 405 bfd_vma offset; 406 /* Size within output section. */ 407 bfd_size_type size; 408 /* Type specific information. */ 409 union 410 { 411 struct 412 { 413 /* Section to include. If this is used, then 414 section->output_section must be the section the 415 link_order is attached to, section->output_offset must 416 equal the link_order offset field, and section->_raw_size 417 must equal the link_order size field. Maybe these 418 restrictions should be relaxed someday. */ 419 asection *section; 420 } indirect; 421 struct 422 { 423 /* Value to fill with. */ 424 unsigned int value; 425 } fill; 426 struct 427 { 428 /* Data to put into file. The size field gives the number 429 of bytes which this field points to. */ 430 bfd_byte *contents; 431 } data; 432 struct 433 { 434 /* Description of reloc to generate. Used for 435 bfd_section_reloc_link_order and 436 bfd_symbol_reloc_link_order. */ 437 struct bfd_link_order_reloc *p; 438 } reloc; 439 } u; 440 }; 441 442 /* A linker order of type bfd_section_reloc_link_order or 443 bfd_symbol_reloc_link_order means to create a reloc against a 444 section or symbol, respectively. This is used to implement -Ur to 445 generate relocs for the constructor tables. The 446 bfd_link_order_reloc structure describes the reloc that BFD should 447 create. It is similar to a arelent, but I didn't use arelent 448 because the linker does not know anything about most symbols, and 449 any asymbol structure it creates will be partially meaningless. 450 This information could logically be in the bfd_link_order struct, 451 but I didn't want to waste the space since these types of relocs 452 are relatively rare. */ 453 454 struct bfd_link_order_reloc 455 { 456 /* Reloc type. */ 457 bfd_reloc_code_real_type reloc; 458 459 union 460 { 461 /* For type bfd_section_reloc_link_order, this is the section 462 the reloc should be against. This must be a section in the 463 output BFD, not any of the input BFDs. */ 464 asection *section; 465 /* For type bfd_symbol_reloc_link_order, this is the name of the 466 symbol the reloc should be against. */ 467 const char *name; 468 } u; 469 470 /* Addend to use. The object file should contain zero. The BFD 471 backend is responsible for filling in the contents of the object 472 file correctly. For some object file formats (e.g., COFF) the 473 addend must be stored into in the object file, and for some 474 (e.g., SPARC a.out) it is kept in the reloc. */ 475 bfd_vma addend; 476 }; 477 478 /* Allocate a new link_order for a section. */ 479 extern struct bfd_link_order *bfd_new_link_order PARAMS ((bfd *, asection *)); 480 481 /* These structures are used to describe version information for the 482 ELF linker. These structures could be manipulated entirely inside 483 BFD, but it would be a pain. Instead, the regular linker sets up 484 these structures, and then passes them into BFD. */ 485 486 /* Regular expressions for a version. */ 487 488 struct bfd_elf_version_expr 489 { 490 /* Next regular expression for this version. */ 491 struct bfd_elf_version_expr *next; 492 /* Regular expression. */ 493 const char *pattern; 494 /* Matching function. */ 495 int (*match) PARAMS((struct bfd_elf_version_expr *, const char *)); 496 }; 497 498 /* Version dependencies. */ 499 500 struct bfd_elf_version_deps 501 { 502 /* Next dependency for this version. */ 503 struct bfd_elf_version_deps *next; 504 /* The version which this version depends upon. */ 505 struct bfd_elf_version_tree *version_needed; 506 }; 507 508 /* A node in the version tree. */ 509 510 struct bfd_elf_version_tree 511 { 512 /* Next version. */ 513 struct bfd_elf_version_tree *next; 514 /* Name of this version. */ 515 const char *name; 516 /* Version number. */ 517 unsigned int vernum; 518 /* Regular expressions for global symbols in this version. */ 519 struct bfd_elf_version_expr *globals; 520 /* Regular expressions for local symbols in this version. */ 521 struct bfd_elf_version_expr *locals; 522 /* List of versions which this version depends upon. */ 523 struct bfd_elf_version_deps *deps; 524 /* Index of the version name. This is used within BFD. */ 525 unsigned int name_indx; 526 /* Whether this version tree was used. This is used within BFD. */ 527 int used; 528 }; 529 530 #endif 531