| 1 | /* bfdlink.h -- header file for BFD link routines |
| 2 | Copyright 1993 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 locals with a certain prefix. */ |
| 39 | discard_all /* Discard all locals. */ |
| 40 | }; |
| 41 | \f |
| 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 | /* Traverse a link hash table. */ |
| 156 | extern void bfd_link_hash_traverse |
| 157 | PARAMS ((struct bfd_link_hash_table *, |
| 158 | boolean (*) (struct bfd_link_hash_entry *, PTR), |
| 159 | PTR)); |
| 160 | |
| 161 | /* Add an entry to the undefs list. */ |
| 162 | extern void bfd_link_add_undef |
| 163 | PARAMS ((struct bfd_link_hash_table *, struct bfd_link_hash_entry *)); |
| 164 | \f |
| 165 | /* This structure holds all the information needed to communicate |
| 166 | between BFD and the linker when doing a link. */ |
| 167 | |
| 168 | struct bfd_link_info |
| 169 | { |
| 170 | /* Function callbacks. */ |
| 171 | const struct bfd_link_callbacks *callbacks; |
| 172 | /* true if BFD should generate a relocateable object file. */ |
| 173 | boolean relocateable; |
| 174 | /* true if BFD should generate a shared object. */ |
| 175 | boolean shared; |
| 176 | /* Which symbols to strip. */ |
| 177 | enum bfd_link_strip strip; |
| 178 | /* Which local symbols to discard. */ |
| 179 | enum bfd_link_discard discard; |
| 180 | /* The local symbol prefix to discard if using discard_l. */ |
| 181 | unsigned int lprefix_len; |
| 182 | const char *lprefix; |
| 183 | /* true if symbols should be retained in memory, false if they |
| 184 | should be freed and reread. */ |
| 185 | boolean keep_memory; |
| 186 | /* The list of input BFD's involved in the link. These are chained |
| 187 | together via the link_next field. */ |
| 188 | bfd *input_bfds; |
| 189 | /* If a symbol should be created for each input BFD, this is section |
| 190 | where those symbols should be placed. It must be a section in |
| 191 | the output BFD. It may be NULL, in which case no such symbols |
| 192 | will be created. This is to support CREATE_OBJECT_SYMBOLS in the |
| 193 | linker command language. */ |
| 194 | asection *create_object_symbols_section; |
| 195 | /* Hash table handled by BFD. */ |
| 196 | struct bfd_link_hash_table *hash; |
| 197 | /* Hash table of symbols to keep. This is NULL unless strip is |
| 198 | strip_some. */ |
| 199 | struct bfd_hash_table *keep_hash; |
| 200 | /* Hash table of symbols to report back via notice_callback. If |
| 201 | this is NULL no symbols are reported back. */ |
| 202 | struct bfd_hash_table *notice_hash; |
| 203 | |
| 204 | |
| 205 | enum bfd_link_subsystem subsystem; |
| 206 | bfd_link_stack_heap stack_heap_parameters; |
| 207 | |
| 208 | /* If a base output file is wanted, then this points to it */ |
| 209 | PTR base_file; |
| 210 | }; |
| 211 | |
| 212 | /* This structures holds a set of callback functions. These are |
| 213 | called by the BFD linker routines. The first argument to each |
| 214 | callback function is the bfd_link_info structure being used. Each |
| 215 | function returns a boolean value. If the function returns false, |
| 216 | then the BFD function which called it will return with a failure |
| 217 | indication. */ |
| 218 | |
| 219 | struct bfd_link_callbacks |
| 220 | { |
| 221 | /* A function which is called when an object is added from an |
| 222 | archive. ABFD is the archive element being added. NAME is the |
| 223 | name of the symbol which caused the archive element to be pulled |
| 224 | in. */ |
| 225 | boolean (*add_archive_element) PARAMS ((struct bfd_link_info *, |
| 226 | bfd *abfd, |
| 227 | const char *name)); |
| 228 | /* A function which is called when a symbol is found with multiple |
| 229 | definitions. NAME is the symbol which is defined multiple times. |
| 230 | OBFD is the old BFD, OSEC is the old section, OVAL is the old |
| 231 | value, NBFD is the new BFD, NSEC is the new section, and NVAL is |
| 232 | the new value. OBFD may be NULL. OSEC and NSEC may be |
| 233 | bfd_com_section or bfd_ind_section. */ |
| 234 | boolean (*multiple_definition) PARAMS ((struct bfd_link_info *, |
| 235 | const char *name, |
| 236 | bfd *obfd, |
| 237 | asection *osec, |
| 238 | bfd_vma oval, |
| 239 | bfd *nbfd, |
| 240 | asection *nsec, |
| 241 | bfd_vma nval)); |
| 242 | /* A function which is called when a common symbol is defined |
| 243 | multiple times. NAME is the symbol appearing multiple times. |
| 244 | OBFD is the BFD of the existing symbol; it may be NULL if this is |
| 245 | not known. OTYPE is the type of the existing symbol, which may |
| 246 | be bfd_link_hash_defined, bfd_link_hash_defweak, |
| 247 | bfd_link_hash_common, or bfd_link_hash_indirect. If OTYPE is |
| 248 | bfd_link_hash_common, OSIZE is the size of the existing symbol. |
| 249 | NBFD is the BFD of the new symbol. NTYPE is the type of the new |
| 250 | symbol, one of bfd_link_hash_defined, bfd_link_hash_common, or |
| 251 | bfd_link_hash_indirect. If NTYPE is bfd_link_hash_common, NSIZE |
| 252 | is the size of the new symbol. */ |
| 253 | boolean (*multiple_common) PARAMS ((struct bfd_link_info *, |
| 254 | const char *name, |
| 255 | bfd *obfd, |
| 256 | enum bfd_link_hash_type otype, |
| 257 | bfd_vma osize, |
| 258 | bfd *nbfd, |
| 259 | enum bfd_link_hash_type ntype, |
| 260 | bfd_vma nsize)); |
| 261 | /* A function which is called to add a symbol to a set. ENTRY is |
| 262 | the link hash table entry for the set itself (e.g., |
| 263 | __CTOR_LIST__). RELOC is the relocation to use for an entry in |
| 264 | the set when generating a relocateable file, and is also used to |
| 265 | get the size of the entry when generating an executable file. |
| 266 | ABFD, SEC and VALUE identify the value to add to the set. */ |
| 267 | boolean (*add_to_set) PARAMS ((struct bfd_link_info *, |
| 268 | struct bfd_link_hash_entry *entry, |
| 269 | bfd_reloc_code_real_type reloc, |
| 270 | bfd *abfd, asection *sec, bfd_vma value)); |
| 271 | /* A function which is called when the name of a g++ constructor or |
| 272 | destructor is found. This is only called by some object file |
| 273 | formats. CONSTRUCTOR is true for a constructor, false for a |
| 274 | destructor. This will use BFD_RELOC_CTOR when generating a |
| 275 | relocateable file. NAME is the name of the symbol found. ABFD, |
| 276 | SECTION and VALUE are the value of the symbol. */ |
| 277 | boolean (*constructor) PARAMS ((struct bfd_link_info *, |
| 278 | boolean constructor, |
| 279 | const char *name, bfd *abfd, asection *sec, |
| 280 | bfd_vma value)); |
| 281 | /* A function which is called when there is a reference to a warning |
| 282 | symbol. WARNING is the warning to be issued. */ |
| 283 | boolean (*warning) PARAMS ((struct bfd_link_info *, |
| 284 | const char *warning)); |
| 285 | /* A function which is called when a relocation is attempted against |
| 286 | an undefined symbol. NAME is the symbol which is undefined. |
| 287 | ABFD, SECTION and ADDRESS identify the location from which the |
| 288 | reference is made. In some cases SECTION may be NULL. */ |
| 289 | boolean (*undefined_symbol) PARAMS ((struct bfd_link_info *, |
| 290 | const char *name, bfd *abfd, |
| 291 | asection *section, bfd_vma address)); |
| 292 | /* A function which is called when a reloc overflow occurs. NAME is |
| 293 | the name of the symbol or section the reloc is against, |
| 294 | RELOC_NAME is the name of the relocation, and ADDEND is any |
| 295 | addend that is used. ABFD, SECTION and ADDRESS identify the |
| 296 | location at which the overflow occurs; if this is the result of a |
| 297 | bfd_section_reloc_link_order or bfd_symbol_reloc_link_order, then |
| 298 | ABFD will be NULL. */ |
| 299 | boolean (*reloc_overflow) PARAMS ((struct bfd_link_info *, |
| 300 | const char *name, |
| 301 | const char *reloc_name, bfd_vma addend, |
| 302 | bfd *abfd, asection *section, |
| 303 | bfd_vma address)); |
| 304 | /* A function which is called when a dangerous reloc is performed. |
| 305 | The canonical example is an a29k IHCONST reloc which does not |
| 306 | follow an IHIHALF reloc. MESSAGE is an appropriate message. |
| 307 | ABFD, SECTION and ADDRESS identify the location at which the |
| 308 | problem occurred; if this is the result of a |
| 309 | bfd_section_reloc_link_order or bfd_symbol_reloc_link_order, then |
| 310 | ABFD will be NULL. */ |
| 311 | boolean (*reloc_dangerous) PARAMS ((struct bfd_link_info *, |
| 312 | const char *message, |
| 313 | bfd *abfd, asection *section, |
| 314 | bfd_vma address)); |
| 315 | /* A function which is called when a reloc is found to be attached |
| 316 | to a symbol which is not being written out. NAME is the name of |
| 317 | the symbol. ABFD, SECTION and ADDRESS identify the location of |
| 318 | the reloc; if this is the result of a |
| 319 | bfd_section_reloc_link_order or bfd_symbol_reloc_link_order, then |
| 320 | ABFD will be NULL. */ |
| 321 | boolean (*unattached_reloc) PARAMS ((struct bfd_link_info *, |
| 322 | const char *name, |
| 323 | bfd *abfd, asection *section, |
| 324 | bfd_vma address)); |
| 325 | /* A function which is called when a symbol in notice_hash is |
| 326 | defined or referenced. NAME is the symbol. ABFD, SECTION and |
| 327 | ADDRESS are the value of the symbol. If SECTION is |
| 328 | bfd_und_section, this is a reference. */ |
| 329 | boolean (*notice) PARAMS ((struct bfd_link_info *, const char *name, |
| 330 | bfd *abfd, asection *section, bfd_vma address)); |
| 331 | }; |
| 332 | \f |
| 333 | /* The linker builds link_order structures which tell the code how to |
| 334 | include input data in the output file. */ |
| 335 | |
| 336 | /* These are the types of link_order structures. */ |
| 337 | |
| 338 | enum bfd_link_order_type |
| 339 | { |
| 340 | bfd_undefined_link_order, /* Undefined. */ |
| 341 | bfd_indirect_link_order, /* Built from a section. */ |
| 342 | bfd_fill_link_order, /* Fill with a 16 bit constant. */ |
| 343 | bfd_data_link_order, /* Set to explicit data. */ |
| 344 | bfd_section_reloc_link_order, /* Relocate against a section. */ |
| 345 | bfd_symbol_reloc_link_order /* Relocate against a symbol. */ |
| 346 | }; |
| 347 | |
| 348 | /* This is the link_order structure itself. These form a chain |
| 349 | attached to the section whose contents they are describing. */ |
| 350 | |
| 351 | struct bfd_link_order |
| 352 | { |
| 353 | /* Next link_order in chain. */ |
| 354 | struct bfd_link_order *next; |
| 355 | /* Type of link_order. */ |
| 356 | enum bfd_link_order_type type; |
| 357 | /* Offset within output section. */ |
| 358 | bfd_vma offset; |
| 359 | /* Size within output section. */ |
| 360 | bfd_size_type size; |
| 361 | /* Type specific information. */ |
| 362 | union |
| 363 | { |
| 364 | struct |
| 365 | { |
| 366 | /* Section to include. If this is used, then |
| 367 | section->output_section must be the section the |
| 368 | link_order is attached to, section->output_offset must |
| 369 | equal the link_order offset field, and section->_raw_size |
| 370 | must equal the link_order size field. Maybe these |
| 371 | restrictions should be relaxed someday. */ |
| 372 | asection *section; |
| 373 | } indirect; |
| 374 | struct |
| 375 | { |
| 376 | /* Value to fill with. */ |
| 377 | unsigned int value; |
| 378 | } fill; |
| 379 | struct |
| 380 | { |
| 381 | /* Data to put into file. The size field gives the number |
| 382 | of bytes which this field points to. */ |
| 383 | bfd_byte *contents; |
| 384 | } data; |
| 385 | struct |
| 386 | { |
| 387 | /* Description of reloc to generate. Used for |
| 388 | bfd_section_reloc_link_order and |
| 389 | bfd_symbol_reloc_link_order. */ |
| 390 | struct bfd_link_order_reloc *p; |
| 391 | } reloc; |
| 392 | } u; |
| 393 | }; |
| 394 | |
| 395 | /* A linker order of type bfd_section_reloc_link_order or |
| 396 | bfd_symbol_reloc_link_order means to create a reloc against a |
| 397 | section or symbol, respectively. This is used to implement -Ur to |
| 398 | generate relocs for the constructor tables. The |
| 399 | bfd_link_order_reloc structure describes the reloc that BFD should |
| 400 | create. It is similar to a arelent, but I didn't use arelent |
| 401 | because the linker does not know anything about most symbols, and |
| 402 | any asymbol structure it creates will be partially meaningless. |
| 403 | This information could logically be in the bfd_link_order struct, |
| 404 | but I didn't want to waste the space since these types of relocs |
| 405 | are relatively rare. */ |
| 406 | |
| 407 | struct bfd_link_order_reloc |
| 408 | { |
| 409 | /* Reloc type. */ |
| 410 | bfd_reloc_code_real_type reloc; |
| 411 | |
| 412 | union |
| 413 | { |
| 414 | /* For type bfd_section_reloc_link_order, this is the section |
| 415 | the reloc should be against. This must be a section in the |
| 416 | output BFD, not any of the input BFDs. */ |
| 417 | asection *section; |
| 418 | /* For type bfd_symbol_reloc_link_order, this is the name of the |
| 419 | symbol the reloc should be against. */ |
| 420 | const char *name; |
| 421 | } u; |
| 422 | |
| 423 | /* Addend to use. The object file should contain zero. The BFD |
| 424 | backend is responsible for filling in the contents of the object |
| 425 | file correctly. For some object file formats (e.g., COFF) the |
| 426 | addend must be stored into in the object file, and for some |
| 427 | (e.g., SPARC a.out) it is kept in the reloc. */ |
| 428 | bfd_vma addend; |
| 429 | }; |
| 430 | |
| 431 | /* Allocate a new link_order for a section. */ |
| 432 | extern struct bfd_link_order *bfd_new_link_order PARAMS ((bfd *, asection *)); |
| 433 | |
| 434 | #endif |