include/bfdlink.h

   1 /* bfdlink.h -- header file for BFD link routines
   2    Copyright (C) 1993-2023 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 enum notice_asneeded_action {
  46   notice_as_needed,
  47   notice_not_needed,
  48   notice_needed
  49 };
  50
  51 /* Whether to generate ELF common symbols with the STT_COMMON type
  52    during a relocatable link.  */
  53 enum bfd_link_elf_stt_common
  54 {
  55   unchanged,
  56   elf_stt_common,
  57   no_elf_stt_common
  58 };
  59
  60 /* Describes the type of hash table entry structure being used.
  61    Different hash table structure have different fields and so
  62    support different linking features.  */
  63 enum bfd_link_hash_table_type
  64   {
  65     bfd_link_generic_hash_table,
  66     bfd_link_elf_hash_table
  67   };
  68 \f
  69 /* These are the possible types of an entry in the BFD link hash
  70    table.  */
  71
  72 enum bfd_link_hash_type
  73 {
  74   bfd_link_hash_new,            /* Symbol is new.  */
  75   bfd_link_hash_undefined,      /* Symbol seen before, but undefined.  */
  76   bfd_link_hash_undefweak,      /* Symbol is weak and undefined.  */
  77   bfd_link_hash_defined,        /* Symbol is defined.  */
  78   bfd_link_hash_defweak,        /* Symbol is weak and defined.  */
  79   bfd_link_hash_common,         /* Symbol is common.  */
  80   bfd_link_hash_indirect,       /* Symbol is an indirect link.  */
  81   bfd_link_hash_warning         /* Like indirect, but warn if referenced.  */
  82 };
  83
  84 enum bfd_link_common_skip_ar_symbols
  85 {
  86   bfd_link_common_skip_none,
  87   bfd_link_common_skip_text,
  88   bfd_link_common_skip_data,
  89   bfd_link_common_skip_all
  90 };
  91
  92 struct bfd_link_hash_common_entry
  93   {
  94     unsigned int alignment_power;       /* Alignment.  */
  95     asection *section;          /* Symbol section.  */
  96   };
  97
  98 /* The linking routines use a hash table which uses this structure for
  99    its elements.  */
 100
 101 struct bfd_link_hash_entry
 102 {
 103   /* Base hash table entry structure.  */
 104   struct bfd_hash_entry root;
 105
 106   /* Type of this entry.  */
 107   ENUM_BITFIELD (bfd_link_hash_type) type : 8;
 108
 109   /* Symbol is referenced in a normal regular object file,
 110      as distinct from a LTO IR object file.  */
 111   unsigned int non_ir_ref_regular : 1;
 112
 113   /* Symbol is referenced in a normal dynamic object file,
 114      as distinct from a LTO IR object file.  */
 115   unsigned int non_ir_ref_dynamic : 1;
 116
 117   /* The symbol, SYM, is referenced by __real_SYM in an object file.  */
 118   unsigned int ref_real : 1;
 119
 120   /* Symbol is a built-in define.  These will be overridden by PROVIDE
 121      in a linker script.  */
 122   unsigned int linker_def : 1;
 123
 124   /* Symbol defined in a linker script.  */
 125   unsigned int ldscript_def : 1;
 126
 127   /* Symbol will be converted from absolute to section-relative.  Set for
 128      symbols defined by a script from "dot" (also SEGMENT_START or ORIGIN)
 129      outside of an output section statement.  */
 130   unsigned int rel_from_abs : 1;
 131
 132   /* A union of information depending upon the type.  */
 133   union
 134     {
 135       /* Nothing is kept for bfd_hash_new.  */
 136       /* bfd_link_hash_undefined, bfd_link_hash_undefweak.  */
 137       struct
 138         {
 139           /* Undefined and common symbols are kept in a linked list through
 140              this field.  This field is present in all of the union element
 141              so that we don't need to remove entries from the list when we
 142              change their type.  Removing entries would either require the
 143              list to be doubly linked, which would waste more memory, or
 144              require a traversal.  When an undefined or common symbol is
 145              created, it should be added to this list, the head of which is in
 146              the link hash table itself.  As symbols are defined, they need
 147              not be removed from the list; anything which reads the list must
 148              doublecheck the symbol type.
 149
 150              Weak symbols are not kept on this list.
 151
 152              Defined and defweak symbols use this field as a reference marker.
 153              If the field is not NULL, or this structure is the tail of the
 154              undefined symbol list, the symbol has been referenced.  If the
 155              symbol is undefined and becomes defined, this field will
 156              automatically be non-NULL since the symbol will have been on the
 157              undefined symbol list.  */
 158           struct bfd_link_hash_entry *next;
 159           /* BFD symbol was found in.  */
 160           bfd *abfd;
 161         } undef;
 162       /* bfd_link_hash_defined, bfd_link_hash_defweak.  */
 163       struct
 164         {
 165           struct bfd_link_hash_entry *next;
 166           /* Symbol section.  */
 167           asection *section;
 168           /* Symbol value.  */
 169           bfd_vma value;
 170         } def;
 171       /* bfd_link_hash_indirect, bfd_link_hash_warning.  */
 172       struct
 173         {
 174           struct bfd_link_hash_entry *next;
 175           /* Real symbol.  */
 176           struct bfd_link_hash_entry *link;
 177           /* Warning message (bfd_link_hash_warning only).  */
 178           const char *warning;
 179         } i;
 180       /* bfd_link_hash_common.  */
 181       struct
 182         {
 183           struct bfd_link_hash_entry *next;
 184           /* The linker needs to know three things about common
 185              symbols: the size, the alignment, and the section in
 186              which the symbol should be placed.  We store the size
 187              here, and we allocate a small structure to hold the
 188              section and the alignment.  The alignment is stored as a
 189              power of two.  We don't store all the information
 190              directly because we don't want to increase the size of
 191              the union; this structure is a major space user in the
 192              linker.  */
 193           struct bfd_link_hash_common_entry *p;
 194           /* Common symbol size.  */
 195           bfd_size_type size;
 196         } c;
 197     } u;
 198 };
 199
 200 /* This is the link hash table.  It is a derived class of
 201    bfd_hash_table.  */
 202
 203 struct bfd_link_hash_table
 204 {
 205   /* The hash table itself.  */
 206   struct bfd_hash_table table;
 207   /* A linked list of undefined and common symbols, linked through the
 208      next field in the bfd_link_hash_entry structure.  */
 209   struct bfd_link_hash_entry *undefs;
 210   /* Entries are added to the tail of the undefs list.  */
 211   struct bfd_link_hash_entry *undefs_tail;
 212   /* Function to free the hash table on closing BFD.  */
 213   void (*hash_table_free) (bfd *);
 214   /* The type of the link hash table.  */
 215   enum bfd_link_hash_table_type type;
 216 };
 217
 218 /* Look up an entry in a link hash table.  If FOLLOW is TRUE, this
 219    follows bfd_link_hash_indirect and bfd_link_hash_warning links to
 220    the real symbol.  */
 221 extern struct bfd_link_hash_entry *bfd_link_hash_lookup
 222   (struct bfd_link_hash_table *, const char *, bool create,
 223    bool copy, bool follow);
 224
 225 /* Look up an entry in the main linker hash table if the symbol might
 226    be wrapped.  This should only be used for references to an
 227    undefined symbol, not for definitions of a symbol.  */
 228
 229 extern struct bfd_link_hash_entry *bfd_wrapped_link_hash_lookup
 230   (bfd *, struct bfd_link_info *, const char *, bool, bool, bool);
 231
 232 /* If H is a wrapped symbol, ie. the symbol name starts with "__wrap_"
 233    and the remainder is found in wrap_hash, return the real symbol.  */
 234
 235 extern struct bfd_link_hash_entry *unwrap_hash_lookup
 236   (struct bfd_link_info *, bfd *, struct bfd_link_hash_entry *);
 237
 238 /* Traverse a link hash table.  */
 239 extern void bfd_link_hash_traverse
 240   (struct bfd_link_hash_table *,
 241     bool (*) (struct bfd_link_hash_entry *, void *),
 242     void *);
 243
 244 /* Add an entry to the undefs list.  */
 245 extern void bfd_link_add_undef
 246   (struct bfd_link_hash_table *, struct bfd_link_hash_entry *);
 247
 248 /* Remove symbols from the undefs list that don't belong there.  */
 249 extern void bfd_link_repair_undef_list
 250   (struct bfd_link_hash_table *table);
 251
 252 /* Read symbols and cache symbol pointer array in outsymbols.  */
 253 extern bool bfd_generic_link_read_symbols (bfd *);
 254
 255 /* Check the relocs in the BFD.  Called after all the input
 256    files have been loaded, and garbage collection has tagged
 257    any unneeded sections.  */
 258 extern bool bfd_link_check_relocs (bfd *,struct bfd_link_info *);
 259
 260 struct bfd_sym_chain
 261 {
 262   struct bfd_sym_chain *next;
 263   const char *name;
 264 };
 265 \f
 266 /* How to handle unresolved symbols.
 267    There are four possibilities which are enumerated below:  */
 268 enum report_method
 269 {
 270   /* This is the initial value when then link_info structure is created.
 271      It allows the various stages of the linker to determine whether they
 272      allowed to set the value.  */
 273   RM_NOT_YET_SET = 0,
 274   RM_IGNORE,
 275   RM_DIAGNOSE,
 276 };
 277
 278 /* How to handle DT_TEXTREL.  */
 279
 280 enum textrel_check_method
 281 {
 282   textrel_check_none,
 283   textrel_check_warning,
 284   textrel_check_error
 285 };
 286
 287 #define bfd_link_textrel_check(info) \
 288   (info->textrel_check != textrel_check_none)
 289
 290 typedef enum {with_flags, without_flags} flag_type;
 291
 292 /* A section flag list.  */
 293 struct flag_info_list
 294 {
 295   flag_type with;
 296   const char *name;
 297   bool valid;
 298   struct flag_info_list *next;
 299 };
 300
 301 /* Section flag info.  */
 302 struct flag_info
 303 {
 304   flagword only_with_flags;
 305   flagword not_with_flags;
 306   struct flag_info_list *flag_list;
 307   bool flags_initialized;
 308 };
 309
 310 struct bfd_elf_dynamic_list;
 311 struct bfd_elf_version_tree;
 312
 313 /* Types of output.  */
 314
 315 enum output_type
 316 {
 317   type_pde,
 318   type_pie,
 319   type_relocatable,
 320   type_dll,
 321 };
 322
 323 #define bfd_link_pde(info)         ((info)->type == type_pde)
 324 #define bfd_link_dll(info)         ((info)->type == type_dll)
 325 #define bfd_link_relocatable(info) ((info)->type == type_relocatable)
 326 #define bfd_link_pie(info)         ((info)->type == type_pie)
 327 #define bfd_link_executable(info)  (bfd_link_pde (info) || bfd_link_pie (info))
 328 #define bfd_link_pic(info)         (bfd_link_dll (info) || bfd_link_pie (info))
 329
 330 /* This structure holds all the information needed to communicate
 331    between BFD and the linker when doing a link.  */
 332
 333 struct bfd_link_info
 334 {
 335   /* Output type.  */
 336   ENUM_BITFIELD (output_type) type : 2;
 337
 338   /* TRUE if BFD should pre-bind symbols in a shared object.  */
 339   unsigned int symbolic: 1;
 340
 341   /* TRUE if BFD should export all symbols in the dynamic symbol table
 342      of an executable, rather than only those used.  */
 343   unsigned int export_dynamic: 1;
 344
 345   /* TRUE if a default symbol version should be created and used for
 346      exported symbols.  */
 347   unsigned int create_default_symver: 1;
 348
 349   /* TRUE if unreferenced sections should be removed.  */
 350   unsigned int gc_sections: 1;
 351
 352   /* TRUE if exported symbols should be kept during section gc.  */
 353   unsigned int gc_keep_exported: 1;
 354
 355   /* TRUE if every symbol should be reported back via the notice
 356      callback.  */
 357   unsigned int notice_all: 1;
 358
 359   /* TRUE if the LTO plugin is active.  */
 360   unsigned int lto_plugin_active: 1;
 361
 362   /* TRUE if all LTO IR symbols have been read.  */
 363   unsigned int lto_all_symbols_read : 1;
 364
 365   /* TRUE if global symbols in discarded sections should be stripped.  */
 366   unsigned int strip_discarded: 1;
 367
 368   /* TRUE if all data symbols should be dynamic.  */
 369   unsigned int dynamic_data: 1;
 370
 371   /* TRUE if section groups should be resolved.  */
 372   unsigned int resolve_section_groups: 1;
 373
 374   /* Set if output file is big-endian, or if that is unknown, from
 375      the command line or first input file endianness.  */
 376   unsigned int big_endian : 1;
 377
 378   /* Which symbols to strip.  */
 379   ENUM_BITFIELD (bfd_link_strip) strip : 2;
 380
 381   /* Which local symbols to discard.  */
 382   ENUM_BITFIELD (bfd_link_discard) discard : 2;
 383
 384   /* Whether to generate ELF common symbols with the STT_COMMON type.  */
 385   ENUM_BITFIELD (bfd_link_elf_stt_common) elf_stt_common : 2;
 386
 387   /* Criteria for skipping symbols when determining
 388      whether to include an object from an archive.  */
 389   ENUM_BITFIELD (bfd_link_common_skip_ar_symbols) common_skip_ar_symbols : 2;
 390
 391   /* What to do with unresolved symbols in an object file.
 392      When producing executables the default is GENERATE_ERROR.
 393      When producing shared libraries the default is IGNORE.  The
 394      assumption with shared libraries is that the reference will be
 395      resolved at load/execution time.  */
 396   ENUM_BITFIELD (report_method) unresolved_syms_in_objects : 2;
 397
 398   /* What to do with unresolved symbols in a shared library.
 399      The same defaults apply.  */
 400   ENUM_BITFIELD (report_method) unresolved_syms_in_shared_libs : 2;
 401
 402   /* TRUE if unresolved symbols are to be warned, rather than errored.  */
 403   unsigned int warn_unresolved_syms: 1;
 404
 405   /* TRUE if shared objects should be linked directly, not shared.  */
 406   unsigned int static_link: 1;
 407
 408   /* TRUE if symbols should be retained in memory, FALSE if they
 409      should be freed and reread.  */
 410   unsigned int keep_memory: 1;
 411
 412   /* TRUE if BFD should generate relocation information in the final
 413      executable.  */
 414   unsigned int emitrelocations: 1;
 415
 416   /* TRUE if PT_GNU_RELRO segment should be created.  */
 417   unsigned int relro: 1;
 418
 419   /* TRUE if DT_RELR should be enabled for compact relative
 420      relocations.  */
 421   unsigned int enable_dt_relr: 1;
 422
 423   /* TRUE if separate code segment should be created.  */
 424   unsigned int separate_code: 1;
 425
 426   /* Nonzero if .eh_frame_hdr section and PT_GNU_EH_FRAME ELF segment
 427      should be created.  1 for DWARF2 tables, 2 for compact tables.  */
 428   unsigned int eh_frame_hdr_type: 2;
 429
 430   /* What to do with DT_TEXTREL in output.  */
 431   ENUM_BITFIELD (textrel_check_method) textrel_check: 2;
 432
 433   /* TRUE if .hash section should be created.  */
 434   unsigned int emit_hash: 1;
 435
 436   /* TRUE if .gnu.hash section should be created.  */
 437   unsigned int emit_gnu_hash: 1;
 438
 439   /* If TRUE reduce memory overheads, at the expense of speed. This will
 440      cause map file generation to use an O(N^2) algorithm and disable
 441      caching ELF symbol buffer.  */
 442   unsigned int reduce_memory_overheads: 1;
 443
 444   /* TRUE if the output file should be in a traditional format.  This
 445      is equivalent to the setting of the BFD_TRADITIONAL_FORMAT flag
 446      on the output file, but may be checked when reading the input
 447      files.  */
 448   unsigned int traditional_format: 1;
 449
 450   /* TRUE if non-PLT relocs should be merged into one reloc section
 451      and sorted so that relocs against the same symbol come together.  */
 452   unsigned int combreloc: 1;
 453
 454   /* TRUE if a default symbol version should be created and used for
 455      imported symbols.  */
 456   unsigned int default_imported_symver: 1;
 457
 458   /* TRUE if the new ELF dynamic tags are enabled. */
 459   unsigned int new_dtags: 1;
 460
 461   /* FALSE if .eh_frame unwind info should be generated for PLT and other
 462      linker created sections, TRUE if it should be omitted.  */
 463   unsigned int no_ld_generated_unwind_info: 1;
 464
 465   /* TRUE if BFD should generate a "task linked" object file,
 466      similar to relocatable but also with globals converted to
 467      statics.  */
 468   unsigned int task_link: 1;
 469
 470   /* TRUE if ok to have multiple definitions, without warning.  */
 471   unsigned int allow_multiple_definition: 1;
 472
 473   /* TRUE if multiple definition of absolute symbols (eg. from -R) should
 474      be reported.  */
 475   unsigned int prohibit_multiple_definition_absolute: 1;
 476
 477   /* TRUE if multiple definitions should only warn.  */
 478   unsigned int warn_multiple_definition: 1;
 479
 480   /* TRUE if ok to have version with no definition.  */
 481   unsigned int allow_undefined_version: 1;
 482
 483   /* TRUE if some symbols have to be dynamic, controlled by
 484      --dynamic-list command line options.  */
 485   unsigned int dynamic: 1;
 486
 487   /* Set if the "-z execstack" option has been used to request that a
 488      PT_GNU_STACK segment should be created with PF_R, PF_W and PF_X
 489      flags set.
 490
 491      Note - if performing a relocatable link then a .note.GNU-stack
 492      section will be created instead, if one does not exist already.
 493      The section will have the SHF_EXECINSTR flag bit set.  */
 494   unsigned int execstack: 1;
 495
 496   /* Set if the "-z noexecstack" option has been used to request that a
 497      PT_GNU_STACK segment should be created with PF_R and PF_W flags.  Or
 498      a non-executable .note.GNU-stack section for relocateable links.
 499
 500      Note - this flag is not quite orthogonal to execstack, since both
 501      of these flags can be 0.  In this case a stack segment can still
 502      be created, but it will only have the PF_X flag bit set if one or
 503      more of the input files contains a .note.GNU-stack section with the
 504      SHF_EXECINSTR flag bit set, or if the default behaviour for the
 505      architecture is to create executable stacks.
 506
 507      The execstack and noexecstack flags should never both be 1.  */
 508   unsigned int noexecstack: 1;
 509
 510   /* Tri-state variable:
 511      0 => do not warn when creating an executable stack.
 512      1 => always warn when creating an executable stack (for any reason).
 513      2 => only warn when an executable stack has been requested an object
 514           file and execstack is 0 or noexecstack is 1.
 515      3 => not used.  */
 516   unsigned int warn_execstack: 2;
 517   /* TRUE if a warning generated because of warn_execstack should be instead
 518      be treated as an error.  */
 519   unsigned int error_execstack: 1;
 520
 521   /* TRUE if warnings should NOT be generated for TLS segments with eXecute
 522      permission or LOAD segments with RWX permissions.  */
 523   unsigned int no_warn_rwx_segments: 1;
 524   /* TRUE if the user gave either --warn-rwx-segments or
 525      --no-warn-rwx-segments on the linker command line.  */
 526   unsigned int user_warn_rwx_segments: 1;
 527   /* TRUE if warnings generated when no_warn_rwx_segements is 0 should
 528      instead be treated as errors.  */
 529   unsigned int warn_is_error_for_rwx_segments: 1;
 530
 531   /* TRUE if the stack can be made executable because of the absence of a
 532      .note.GNU-stack section in an input file.  Note - even if this field
 533      is set, some targets may choose to ignore the setting and not create
 534      an executable stack.  */
 535   unsigned int default_execstack : 1;
 536
 537   /* TRUE if we want to produced optimized output files.  This might
 538      need much more time and therefore must be explicitly selected.  */
 539   unsigned int optimize: 1;
 540
 541   /* TRUE if user should be informed of removed unreferenced sections.  */
 542   unsigned int print_gc_sections: 1;
 543
 544   /* TRUE if we should warn alternate ELF machine code.  */
 545   unsigned int warn_alternate_em: 1;
 546
 547   /* TRUE if the linker script contained an explicit PHDRS command.  */
 548   unsigned int user_phdrs: 1;
 549
 550   /* TRUE if program headers ought to be loaded.  */
 551   unsigned int load_phdrs: 1;
 552
 553   /* TRUE if we should check relocations after all input files have
 554      been opened.  */
 555   unsigned int check_relocs_after_open_input: 1;
 556
 557   /* TRUE if generation of .interp/PT_INTERP should be suppressed.  */
 558   unsigned int nointerp: 1;
 559
 560   /* TRUE if common symbols should be treated as undefined.  */
 561   unsigned int inhibit_common_definition : 1;
 562
 563   /* TRUE if "-Map map" is passed to linker.  */
 564   unsigned int has_map_file : 1;
 565
 566   /* TRUE if "--enable-non-contiguous-regions" is passed to the
 567      linker.  */
 568   unsigned int non_contiguous_regions : 1;
 569
 570   /* TRUE if "--enable-non-contiguous-regions-warnings" is passed to
 571      the linker.  */
 572   unsigned int non_contiguous_regions_warnings : 1;
 573
 574   /* TRUE if all symbol names should be unique.  */
 575   unsigned int unique_symbol : 1;
 576
 577   /* TRUE if maxpagesize is set on command-line.  */
 578   unsigned int maxpagesize_is_set : 1;
 579
 580   /* TRUE if commonpagesize is set on command-line.  */
 581   unsigned int commonpagesize_is_set : 1;
 582
 583   /* Char that may appear as the first char of a symbol, but should be
 584      skipped (like symbol_leading_char) when looking up symbols in
 585      wrap_hash.  Used by PowerPC Linux for 'dot' symbols.  */
 586   char wrap_char;
 587
 588   /* Separator between archive and filename in linker script filespecs.  */
 589   char path_separator;
 590
 591   /* Default stack size.  Zero means default (often zero itself), -1
 592      means explicitly zero-sized.  */
 593   bfd_signed_vma stacksize;
 594
 595   /* Enable or disable target specific optimizations.
 596
 597      Not all targets have optimizations to enable.
 598
 599      Normally these optimizations are disabled by default but some targets
 600      prefer to enable them by default.  So this field is a tri-state variable.
 601      The values are:
 602
 603      zero: Enable the optimizations (either from --relax being specified on
 604        the command line or the backend's before_allocation emulation function.
 605
 606      positive: The user has requested that these optimizations be disabled.
 607        (Via the --no-relax command line option).
 608
 609      negative: The optimizations are disabled.  (Set when initializing the
 610        args_type structure in ldmain.c:main.  */
 611   signed int disable_target_specific_optimizations;
 612
 613   /* Function callbacks.  */
 614   const struct bfd_link_callbacks *callbacks;
 615
 616   /* Hash table handled by BFD.  */
 617   struct bfd_link_hash_table *hash;
 618
 619   /* Hash table of symbols to keep.  This is NULL unless strip is
 620      strip_some.  */
 621   struct bfd_hash_table *keep_hash;
 622
 623   /* Hash table of symbols to report back via the notice callback.  If
 624      this is NULL, and notice_all is FALSE, then no symbols are
 625      reported back.  */
 626   struct bfd_hash_table *notice_hash;
 627
 628   /* Hash table of symbols which are being wrapped (the --wrap linker
 629      option).  If this is NULL, no symbols are being wrapped.  */
 630   struct bfd_hash_table *wrap_hash;
 631
 632   /* Hash table of symbols which may be left unresolved during
 633      a link.  If this is NULL, no symbols can be left unresolved.  */
 634   struct bfd_hash_table *ignore_hash;
 635
 636   /* The output BFD.  */
 637   bfd *output_bfd;
 638
 639   /* The import library generated.  */
 640   bfd *out_implib_bfd;
 641
 642   /* The list of input BFD's involved in the link.  These are chained
 643      together via the link.next field.  */
 644   bfd *input_bfds;
 645   bfd **input_bfds_tail;
 646
 647   /* If a symbol should be created for each input BFD, this is section
 648      where those symbols should be placed.  It must be a section in
 649      the output BFD.  It may be NULL, in which case no such symbols
 650      will be created.  This is to support CREATE_OBJECT_SYMBOLS in the
 651      linker command language.  */
 652   asection *create_object_symbols_section;
 653
 654   /* List of global symbol names that are starting points for marking
 655      sections against garbage collection.  */
 656   struct bfd_sym_chain *gc_sym_list;
 657
 658   /* If a base output file is wanted, then this points to it */
 659   void *base_file;
 660
 661   /* The function to call when the executable or shared object is
 662      loaded.  */
 663   const char *init_function;
 664
 665   /* The function to call when the executable or shared object is
 666      unloaded.  */
 667   const char *fini_function;
 668
 669   /* Number of relaxation passes.  Usually only one relaxation pass
 670      is needed.  But a backend can have as many relaxation passes as
 671      necessary.  During bfd_relax_section call, it is set to the
 672      current pass, starting from 0.  */
 673   int relax_pass;
 674
 675   /* Number of relaxation trips.  This number is incremented every
 676      time the relaxation pass is restarted due to a previous
 677      relaxation returning true in *AGAIN.  */
 678   int relax_trip;
 679
 680   /* > 0 to treat protected data defined in the shared library as
 681      reference external.  0 to treat it as internal.  -1 to let
 682      backend to decide.  */
 683   int extern_protected_data;
 684
 685   /* 1 to make undefined weak symbols dynamic when building a dynamic
 686      object.  0 to resolve undefined weak symbols to zero.  -1 to let
 687      the backend decide.  */
 688   int dynamic_undefined_weak;
 689
 690   /* Non-zero if auto-import thunks for DATA items in pei386 DLLs
 691      should be generated/linked against.  Set to 1 if this feature
 692      is explicitly requested by the user, -1 if enabled by default.  */
 693   int pei386_auto_import;
 694
 695   /* Non-zero if runtime relocs for DATA items with non-zero addends
 696      in pei386 DLLs should be generated.  Set to 1 if this feature
 697      is explicitly requested by the user, -1 if enabled by default.  */
 698   int pei386_runtime_pseudo_reloc;
 699
 700   /* How many spare .dynamic DT_NULL entries should be added?  */
 701   unsigned int spare_dynamic_tags;
 702
 703   /* GNU_PROPERTY_1_NEEDED_INDIRECT_EXTERN_ACCESS control:
 704        > 1: Turn on by -z indirect-extern-access or by backend.
 705       == 1: Turn on by an input.
 706          0: Turn off.
 707        < 0: Turn on if it is set on any inputs or let backend to
 708             decide.  */
 709   int indirect_extern_access;
 710
 711   /* Non-zero if executable should not contain copy relocs.
 712        > 1: Implied by indirect_extern_access.
 713       == 1: Turn on by -z nocopyreloc.
 714          0: Turn off.
 715     Setting this to non-zero may result in a non-sharable text
 716     segment.  */
 717   int nocopyreloc;
 718
 719   /* Pointer to the GNU_PROPERTY_1_NEEDED property in memory.  */
 720   bfd_byte *needed_1_p;
 721
 722   /* May be used to set DT_FLAGS for ELF. */
 723   bfd_vma flags;
 724
 725   /* May be used to set DT_FLAGS_1 for ELF. */
 726   bfd_vma flags_1;
 727
 728   /* May be used to set DT_GNU_FLAGS_1 for ELF. */
 729   bfd_vma gnu_flags_1;
 730
 731   /* TRUE if references to __start_/__stop_ synthesized symbols do not
 732      specially retain C identifier named sections.  */
 733   int start_stop_gc;
 734
 735   /* May be used to set ELF visibility for __start_* / __stop_.  */
 736   unsigned int start_stop_visibility;
 737
 738   /* The maximum page size for ELF.  */
 739   bfd_vma maxpagesize;
 740
 741   /* The common page size for ELF.  */
 742   bfd_vma commonpagesize;
 743
 744   /* Start and end of RELRO region.  */
 745   bfd_vma relro_start, relro_end;
 746
 747   /* List of symbols should be dynamic.  */
 748   struct bfd_elf_dynamic_list *dynamic_list;
 749
 750   /* The version information.  */
 751   struct bfd_elf_version_tree *version_info;
 752
 753   /* Size of cache.  Backend can use it to keep strace cache size.   */
 754   bfd_size_type cache_size;
 755
 756   /* The maximum cache size.  Backend can use cache_size and and
 757      max_cache_size to decide if keep_memory should be honored.  */
 758   bfd_size_type max_cache_size;
 759 };
 760
 761 /* Some forward-definitions used by some callbacks.  */
 762
 763 struct elf_strtab_hash;
 764 struct elf_internal_sym;
 765
 766 /* This structures holds a set of callback functions.  These are called
 767    by the BFD linker routines.  */
 768
 769 struct bfd_link_callbacks
 770 {
 771   /* A function which is called when an object is added from an
 772      archive.  ABFD is the archive element being added.  NAME is the
 773      name of the symbol which caused the archive element to be pulled
 774      in.  This function may set *SUBSBFD to point to an alternative
 775      BFD from which symbols should in fact be added in place of the
 776      original BFD's symbols.  Returns TRUE if the object should be
 777      added, FALSE if it should be skipped.  */
 778   bool (*add_archive_element)
 779     (struct bfd_link_info *, bfd *abfd, const char *name, bfd **subsbfd);
 780   /* A function which is called when a symbol is found with multiple
 781      definitions.  H is the symbol which is defined multiple times.
 782      NBFD is the new BFD, NSEC is the new section, and NVAL is the new
 783      value.  NSEC may be bfd_com_section or bfd_ind_section.  */
 784   void (*multiple_definition)
 785     (struct bfd_link_info *, struct bfd_link_hash_entry *h,
 786      bfd *nbfd, asection *nsec, bfd_vma nval);
 787   /* A function which is called when a common symbol is defined
 788      multiple times.  H is the symbol appearing multiple times.
 789      NBFD is the BFD of the new symbol.  NTYPE is the type of the new
 790      symbol, one of bfd_link_hash_defined, bfd_link_hash_common, or
 791      bfd_link_hash_indirect.  If NTYPE is bfd_link_hash_common, NSIZE
 792      is the size of the new symbol.  */
 793   void (*multiple_common)
 794     (struct bfd_link_info *, struct bfd_link_hash_entry *h,
 795      bfd *nbfd, enum bfd_link_hash_type ntype, bfd_vma nsize);
 796   /* A function which is called to add a symbol to a set.  ENTRY is
 797      the link hash table entry for the set itself (e.g.,
 798      __CTOR_LIST__).  RELOC is the relocation to use for an entry in
 799      the set when generating a relocatable file, and is also used to
 800      get the size of the entry when generating an executable file.
 801      ABFD, SEC and VALUE identify the value to add to the set.  */
 802   void (*add_to_set)
 803     (struct bfd_link_info *, struct bfd_link_hash_entry *entry,
 804      bfd_reloc_code_real_type reloc, bfd *abfd, asection *sec, bfd_vma value);
 805   /* A function which is called when the name of a g++ constructor or
 806      destructor is found.  This is only called by some object file
 807      formats.  CONSTRUCTOR is TRUE for a constructor, FALSE for a
 808      destructor.  This will use BFD_RELOC_CTOR when generating a
 809      relocatable file.  NAME is the name of the symbol found.  ABFD,
 810      SECTION and VALUE are the value of the symbol.  */
 811   void (*constructor)
 812     (struct bfd_link_info *, bool constructor, const char *name,
 813      bfd *abfd, asection *sec, bfd_vma value);
 814   /* A function which is called to issue a linker warning.  For
 815      example, this is called when there is a reference to a warning
 816      symbol.  WARNING is the warning to be issued.  SYMBOL is the name
 817      of the symbol which triggered the warning; it may be NULL if
 818      there is none.  ABFD, SECTION and ADDRESS identify the location
 819      which trigerred the warning; either ABFD or SECTION or both may
 820      be NULL if the location is not known.  */
 821   void (*warning)
 822     (struct bfd_link_info *, const char *warning, const char *symbol,
 823      bfd *abfd, asection *section, bfd_vma address);
 824   /* A function which is called when a relocation is attempted against
 825      an undefined symbol.  NAME is the symbol which is undefined.
 826      ABFD, SECTION and ADDRESS identify the location from which the
 827      reference is made. IS_FATAL indicates whether an undefined symbol is
 828      a fatal error or not. In some cases SECTION may be NULL.  */
 829   void (*undefined_symbol)
 830     (struct bfd_link_info *, const char *name, bfd *abfd,
 831      asection *section, bfd_vma address, bool is_fatal);
 832   /* A function which is called when a reloc overflow occurs. ENTRY is
 833      the link hash table entry for the symbol the reloc is against.
 834      NAME is the name of the local symbol or section the reloc is
 835      against, RELOC_NAME is the name of the relocation, and ADDEND is
 836      any addend that is used.  ABFD, SECTION and ADDRESS identify the
 837      location at which the overflow occurs; if this is the result of a
 838      bfd_section_reloc_link_order or bfd_symbol_reloc_link_order, then
 839      ABFD will be NULL.  */
 840   void (*reloc_overflow)
 841     (struct bfd_link_info *, struct bfd_link_hash_entry *entry,
 842      const char *name, const char *reloc_name, bfd_vma addend,
 843      bfd *abfd, asection *section, bfd_vma address);
 844   /* A function which is called when a dangerous reloc is performed.
 845      MESSAGE is an appropriate message.
 846      ABFD, SECTION and ADDRESS identify the location at which the
 847      problem occurred; if this is the result of a
 848      bfd_section_reloc_link_order or bfd_symbol_reloc_link_order, then
 849      ABFD will be NULL.  */
 850   void (*reloc_dangerous)
 851     (struct bfd_link_info *, const char *message,
 852      bfd *abfd, asection *section, bfd_vma address);
 853   /* A function which is called when a reloc is found to be attached
 854      to a symbol which is not being written out.  NAME is the name of
 855      the symbol.  ABFD, SECTION and ADDRESS identify the location of
 856      the reloc; if this is the result of a
 857      bfd_section_reloc_link_order or bfd_symbol_reloc_link_order, then
 858      ABFD will be NULL.  */
 859   void (*unattached_reloc)
 860     (struct bfd_link_info *, const char *name,
 861      bfd *abfd, asection *section, bfd_vma address);
 862   /* A function which is called when a symbol in notice_hash is
 863      defined or referenced.  H is the symbol, INH the indirect symbol
 864      if applicable.  ABFD, SECTION and ADDRESS are the (new) value of
 865      the symbol.  If SECTION is bfd_und_section, this is a reference.
 866      FLAGS are the symbol BSF_* flags.  */
 867   bool (*notice)
 868     (struct bfd_link_info *, struct bfd_link_hash_entry *h,
 869      struct bfd_link_hash_entry *inh,
 870      bfd *abfd, asection *section, bfd_vma address, flagword flags);
 871   /* Error or warning link info message.  */
 872   void (*einfo)
 873     (const char *fmt, ...);
 874   /* General link info message.  */
 875   void (*info)
 876     (const char *fmt, ...);
 877   /* Message to be printed in linker map file.  */
 878   void (*minfo)
 879     (const char *fmt, ...);
 880   /* This callback provides a chance for users of the BFD library to
 881      override its decision about whether to place two adjacent sections
 882      into the same segment.  */
 883   bool (*override_segment_assignment)
 884     (struct bfd_link_info *, bfd * abfd,
 885      asection * current_section, asection * previous_section,
 886      bool new_segment);
 887   /* This callback provides a chance for callers of the BFD to examine the
 888      ELF (dynamic) string table once it is complete.  */
 889   void (*examine_strtab)
 890     (struct elf_strtab_hash *symstrtab);
 891   /* This callback is called just before a symbol is swapped out, so that the
 892      CTF machinery can look up symbols during construction.  The name is
 893      already an external strtab offset at this point.  */
 894   void (*ctf_new_symbol)
 895     (int symidx, struct elf_internal_sym *sym);
 896   /* Likewise, for dynamic symbols.  */
 897   void (*ctf_new_dynsym)
 898     (int symidx, struct elf_internal_sym *sym);
 899   /* This callback should emit the CTF section into a non-loadable section in
 900      the output BFD named .ctf or a name beginning with ".ctf.".  */
 901   void (*emit_ctf)
 902     (void);
 903 };
 904 \f
 905 /* The linker builds link_order structures which tell the code how to
 906    include input data in the output file.  */
 907
 908 /* These are the types of link_order structures.  */
 909
 910 enum bfd_link_order_type
 911 {
 912   bfd_undefined_link_order,     /* Undefined.  */
 913   bfd_indirect_link_order,      /* Built from a section.  */
 914   bfd_data_link_order,          /* Set to explicit data.  */
 915   bfd_section_reloc_link_order, /* Relocate against a section.  */
 916   bfd_symbol_reloc_link_order   /* Relocate against a symbol.  */
 917 };
 918
 919 /* This is the link_order structure itself.  These form a chain
 920    attached to the output section whose contents they are describing.  */
 921
 922 struct bfd_link_order
 923 {
 924   /* Next link_order in chain.  */
 925   struct bfd_link_order *next;
 926   /* Type of link_order.  */
 927   enum bfd_link_order_type type;
 928   /* Offset within output section in bytes.  */
 929   bfd_vma offset;
 930   /* Size within output section in octets.  */
 931   bfd_size_type size;
 932   /* Type specific information.  */
 933   union
 934     {
 935       struct
 936         {
 937           /* Section to include.  If this is used, then
 938              section->output_section must be the section the
 939              link_order is attached to, section->output_offset must
 940              equal the link_order offset field, and section->size
 941              must equal the link_order size field.  Maybe these
 942              restrictions should be relaxed someday.  */
 943           asection *section;
 944         } indirect;
 945       struct
 946         {
 947           /* Size of contents, or zero when contents should be filled by
 948              the architecture-dependent fill function.
 949              A non-zero value allows filling of the output section
 950              with an arbitrary repeated pattern.  */
 951           unsigned int size;
 952           /* Data to put into file.  */
 953           bfd_byte *contents;
 954         } data;
 955       struct
 956         {
 957           /* Description of reloc to generate.  Used for
 958              bfd_section_reloc_link_order and
 959              bfd_symbol_reloc_link_order.  */
 960           struct bfd_link_order_reloc *p;
 961         } reloc;
 962     } u;
 963 };
 964
 965 /* A linker order of type bfd_section_reloc_link_order or
 966    bfd_symbol_reloc_link_order means to create a reloc against a
 967    section or symbol, respectively.  This is used to implement -Ur to
 968    generate relocs for the constructor tables.  The
 969    bfd_link_order_reloc structure describes the reloc that BFD should
 970    create.  It is similar to a arelent, but I didn't use arelent
 971    because the linker does not know anything about most symbols, and
 972    any asymbol structure it creates will be partially meaningless.
 973    This information could logically be in the bfd_link_order struct,
 974    but I didn't want to waste the space since these types of relocs
 975    are relatively rare.  */
 976
 977 struct bfd_link_order_reloc
 978 {
 979   /* Reloc type.  */
 980   bfd_reloc_code_real_type reloc;
 981
 982   union
 983     {
 984       /* For type bfd_section_reloc_link_order, this is the section
 985          the reloc should be against.  This must be a section in the
 986          output BFD, not any of the input BFDs.  */
 987       asection *section;
 988       /* For type bfd_symbol_reloc_link_order, this is the name of the
 989          symbol the reloc should be against.  */
 990       const char *name;
 991     } u;
 992
 993   /* Addend to use.  The object file should contain zero.  The BFD
 994      backend is responsible for filling in the contents of the object
 995      file correctly.  For some object file formats (e.g., COFF) the
 996      addend must be stored into in the object file, and for some
 997      (e.g., SPARC a.out) it is kept in the reloc.  */
 998   bfd_vma addend;
 999 };
1000
1001 /* Allocate a new link_order for a section.  */
1002 extern struct bfd_link_order *bfd_new_link_order (bfd *, asection *);
1003
1004 struct bfd_section_already_linked;
1005
1006 extern bool bfd_section_already_linked_table_init (void);
1007 extern void bfd_section_already_linked_table_free (void);
1008 extern bool _bfd_handle_already_linked
1009   (struct bfd_section *, struct bfd_section_already_linked *,
1010    struct bfd_link_info *);
1011
1012 extern struct bfd_section *_bfd_nearby_section
1013   (bfd *, struct bfd_section *, bfd_vma);
1014
1015 extern void _bfd_fix_excluded_sec_syms
1016   (bfd *, struct bfd_link_info *);
1017
1018 /* These structures are used to describe version information for the
1019    ELF linker.  These structures could be manipulated entirely inside
1020    BFD, but it would be a pain.  Instead, the regular linker sets up
1021    these structures, and then passes them into BFD.  */
1022
1023 /* Glob pattern for a version.  */
1024
1025 struct bfd_elf_version_expr
1026 {
1027   /* Next glob pattern for this version.  */
1028   struct bfd_elf_version_expr *next;
1029   /* Glob pattern.  */
1030   const char *pattern;
1031   /* Set if pattern is not a glob.  */
1032   unsigned int literal : 1;
1033   /* Defined by ".symver".  */
1034   unsigned int symver : 1;
1035   /* Defined by version script.  */
1036   unsigned int script : 1;
1037   /* Pattern type.  */
1038 #define BFD_ELF_VERSION_C_TYPE          1
1039 #define BFD_ELF_VERSION_CXX_TYPE        2
1040 #define BFD_ELF_VERSION_JAVA_TYPE       4
1041   unsigned int mask : 3;
1042 };
1043
1044 struct bfd_elf_version_expr_head
1045 {
1046   /* List of all patterns, both wildcards and non-wildcards.  */
1047   struct bfd_elf_version_expr *list;
1048   /* Hash table for non-wildcards.  */
1049   void *htab;
1050   /* Remaining patterns.  */
1051   struct bfd_elf_version_expr *remaining;
1052   /* What kind of pattern types are present in list (bitmask).  */
1053   unsigned int mask;
1054 };
1055
1056 /* Version dependencies.  */
1057
1058 struct bfd_elf_version_deps
1059 {
1060   /* Next dependency for this version.  */
1061   struct bfd_elf_version_deps *next;
1062   /* The version which this version depends upon.  */
1063   struct bfd_elf_version_tree *version_needed;
1064 };
1065
1066 /* A node in the version tree.  */
1067
1068 struct bfd_elf_version_tree
1069 {
1070   /* Next version.  */
1071   struct bfd_elf_version_tree *next;
1072   /* Name of this version.  */
1073   const char *name;
1074   /* Version number.  */
1075   unsigned int vernum;
1076   /* Regular expressions for global symbols in this version.  */
1077   struct bfd_elf_version_expr_head globals;
1078   /* Regular expressions for local symbols in this version.  */
1079   struct bfd_elf_version_expr_head locals;
1080   /* List of versions which this version depends upon.  */
1081   struct bfd_elf_version_deps *deps;
1082   /* Index of the version name.  This is used within BFD.  */
1083   unsigned int name_indx;
1084   /* Whether this version tree was used.  This is used within BFD.  */
1085   int used;
1086   /* Matching hook.  */
1087   struct bfd_elf_version_expr *(*match)
1088     (struct bfd_elf_version_expr_head *head,
1089      struct bfd_elf_version_expr *prev, const char *sym);
1090 };
1091
1092 struct bfd_elf_dynamic_list
1093 {
1094   struct bfd_elf_version_expr_head head;
1095   struct bfd_elf_version_expr *(*match)
1096     (struct bfd_elf_version_expr_head *head,
1097      struct bfd_elf_version_expr *prev, const char *sym);
1098 };
1099
1100 #endif