bfd/reloc.c

   1 /* BFD support for handling relocation entries.
   2    Copyright (C) 1990, 1991, 1992, 1993 Free Software Foundation, Inc.
   3    Written by 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., 675 Mass Ave, Cambridge, MA 02139, USA.  */
  20
  21 /*
  22 SECTION
  23         Relocations
  24
  25         BFD maintains relocations in much the same was as it maintains
  26         symbols; they are left alone until required, then read in
  27         en-mass and traslated into an internal form. There is a common
  28         routine <<bfd_perform_relocation>> which acts upon the
  29         canonical form to do the actual fixup.
  30
  31         Note that relocations are maintained on a per section basis,
  32         whilst symbols are maintained on a per BFD basis.
  33
  34         All a back end has to do to fit the BFD interface is to create
  35         as many <<struct reloc_cache_entry>> as there are relocations
  36         in a particular section, and fill in the right bits:
  37
  38 @menu
  39 @* typedef arelent::
  40 @* howto manager::
  41 @end menu
  42
  43 */
  44 #include "bfd.h"
  45 #include "sysdep.h"
  46 #include "libbfd.h"
  47 #include "seclet.h"
  48 /*
  49 DOCDD
  50 INODE
  51         typedef arelent, howto manager, Relocations, Relocations
  52
  53 SUBSECTION
  54         typedef arelent
  55
  56         This is the structure of a relocation entry:
  57
  58 CODE_FRAGMENT
  59 .
  60 .typedef enum bfd_reloc_status
  61 .{
  62 .       {* No errors detected *}
  63 .  bfd_reloc_ok,
  64 .
  65 .       {* The relocation was performed, but there was an overflow. *}
  66 .  bfd_reloc_overflow,
  67 .
  68 .       {* The address to relocate was not within the section supplied. *}
  69 .  bfd_reloc_outofrange,
  70 .
  71 .       {* Used by special functions *}
  72 .  bfd_reloc_continue,
  73 .
  74 .       {* Unused *}
  75 .  bfd_reloc_notsupported,
  76 .
  77 .       {* Unsupported relocation size requested. *}
  78 .  bfd_reloc_other,
  79 .
  80 .       {* The symbol to relocate against was undefined. *}
  81 .  bfd_reloc_undefined,
  82 .
  83 .       {* The relocation was performed, but may not be ok - presently
  84 .          generated only when linking i960 coff files with i960 b.out
  85 .          symbols. *}
  86 .  bfd_reloc_dangerous
  87 . }
  88 . bfd_reloc_status_type;
  89 .
  90 .
  91 .typedef struct reloc_cache_entry
  92 .{
  93 .       {* A pointer into the canonical table of pointers  *}
  94 .  struct symbol_cache_entry **sym_ptr_ptr;
  95 .
  96 .       {* offset in section *}
  97 .  bfd_size_type address;
  98 .
  99 .       {* addend for relocation value *}
 100 .  bfd_vma addend;
 101 .
 102 .       {* Pointer to how to perform the required relocation *}
 103 .  CONST struct reloc_howto_struct *howto;
 104 .
 105 .} arelent;
 106
 107 */
 108
 109 /*
 110 DESCRIPTION
 111
 112         Here is a description of each of the fields within a relent:
 113
 114         o sym_ptr_ptr
 115
 116         The symbol table pointer points to a pointer to the symbol
 117         associated with the relocation request. This would naturally
 118         be the pointer into the table returned by the back end's
 119         get_symtab action. @xref{Symbols}. The symbol is referenced
 120         through a pointer to a pointer so that tools like the linker
 121         can fix up all the symbols of the same name by modifying only
 122         one pointer. The relocation routine looks in the symbol and
 123         uses the base of the section the symbol is attached to and the
 124         value of the symbol as the initial relocation offset. If the
 125         symbol pointer is zero, then the section provided is looked up.
 126
 127         o address
 128
 129         The address field gives the offset in bytes from the base of
 130         the section data which owns the relocation record to the first
 131         byte of relocatable information. The actual data relocated
 132         will be relative to this point - for example, a relocation
 133         type which modifies the bottom two bytes of a four byte word
 134         would not touch the first byte pointed to in a big endian
 135         world.
 136
 137         o addend
 138
 139         The addend is a value provided by the back end to be added (!)
 140         to the relocation offset. Its interpretation is dependent upon
 141         the howto. For example, on the 68k the code:
 142
 143
 144 |        char foo[];
 145 |        main()
 146 |                {
 147 |                return foo[0x12345678];
 148 |                }
 149
 150         Could be compiled into:
 151
 152 |        linkw fp,#-4
 153 |        moveb @@#12345678,d0
 154 |        extbl d0
 155 |        unlk fp
 156 |        rts
 157
 158
 159         This could create a reloc pointing to foo, but leave the
 160         offset in the data (something like)
 161
 162
 163 |RELOCATION RECORDS FOR [.text]:
 164 |offset   type      value
 165 |00000006 32        _foo
 166 |
 167 |00000000 4e56 fffc          ; linkw fp,#-4
 168 |00000004 1039 1234 5678     ; moveb @@#12345678,d0
 169 |0000000a 49c0               ; extbl d0
 170 |0000000c 4e5e               ; unlk fp
 171 |0000000e 4e75               ; rts
 172
 173
 174         Using coff and an 88k, some instructions don't have enough
 175         space in them to represent the full address range, and
 176         pointers have to be loaded in two parts. So you'd get something like:
 177
 178
 179 |        or.u     r13,r0,hi16(_foo+0x12345678)
 180 |        ld.b     r2,r13,lo16(_foo+0x12345678)
 181 |        jmp      r1
 182
 183
 184         This should create two relocs, both pointing to _foo, and with
 185         0x12340000 in their addend field. The data would consist of:
 186
 187
 188 |RELOCATION RECORDS FOR [.text]:
 189 |offset   type      value
 190 |00000002 HVRT16    _foo+0x12340000
 191 |00000006 LVRT16    _foo+0x12340000
 192
 193 |00000000 5da05678           ; or.u r13,r0,0x5678
 194 |00000004 1c4d5678           ; ld.b r2,r13,0x5678
 195 |00000008 f400c001           ; jmp r1
 196
 197
 198         The relocation routine digs out the value from the data, adds
 199         it to the addend to get the original offset and then adds the
 200         value of _foo. Note that all 32 bits have to be kept around
 201         somewhere, to cope with carry from bit 15 to bit 16.
 202
 203         One further example is the sparc and the a.out format. The
 204         sparc has a similar problem to the 88k, in that some
 205         instructions don't have room for an entire offset, but on the
 206         sparc the parts are created odd sized lumps. The designers of
 207         the a.out format chose not to use the data within the section
 208         for storing part of the offset; all the offset is kept within
 209         the reloc. Any thing in the data should be ignored.
 210
 211 |        save %sp,-112,%sp
 212 |        sethi %hi(_foo+0x12345678),%g2
 213 |        ldsb [%g2+%lo(_foo+0x12345678)],%i0
 214 |        ret
 215 |        restore
 216
 217         Both relocs contains a pointer to foo, and the offsets would
 218         contain junk.
 219
 220
 221 |RELOCATION RECORDS FOR [.text]:
 222 |offset   type      value
 223 |00000004 HI22      _foo+0x12345678
 224 |00000008 LO10      _foo+0x12345678
 225
 226 |00000000 9de3bf90     ; save %sp,-112,%sp
 227 |00000004 05000000     ; sethi %hi(_foo+0),%g2
 228 |00000008 f048a000     ; ldsb [%g2+%lo(_foo+0)],%i0
 229 |0000000c 81c7e008     ; ret
 230 |00000010 81e80000     ; restore
 231
 232
 233         o howto
 234
 235         The howto field can be imagined as a
 236         relocation instruction. It is a pointer to a struct which
 237         contains information on what to do with all the other
 238         information in the reloc record and data section. A back end
 239         would normally have a relocation instruction set and turn
 240         relocations into pointers to the correct structure on input -
 241         but it would be possible to create each howto field on demand.
 242
 243 */
 244
 245 /*
 246 SUBSUBSECTION
 247         <<enum complain_overflow>>
 248
 249         Indicates what sort of overflow checking should be done when
 250         performing a relocation.
 251
 252 CODE_FRAGMENT
 253 .
 254 .enum complain_overflow
 255 .{
 256 .       {* Do not complain on overflow. *}
 257 .  complain_overflow_dont,
 258 .
 259 .       {* Complain if the bitfield overflows, whether it is considered
 260 .          as signed or unsigned. *}
 261 .  complain_overflow_bitfield,
 262 .
 263 .       {* Complain if the value overflows when considered as signed
 264 .          number. *}
 265 .  complain_overflow_signed,
 266 .
 267 .       {* Complain if the value overflows when considered as an
 268 .          unsigned number. *}
 269 .  complain_overflow_unsigned
 270 .};
 271
 272 */
 273
 274 /*
 275 SUBSUBSECTION
 276         <<reloc_howto_type>>
 277
 278         The <<reloc_howto_type>> is a structure which contains all the
 279         information that BFD needs to know to tie up a back end's data.
 280
 281 CODE_FRAGMENT
 282 .struct symbol_cache_entry;             {* Forward declaration *}
 283 .
 284 .typedef CONST struct reloc_howto_struct
 285 .{
 286 .       {*  The type field has mainly a documetary use - the back end can
 287 .           to what it wants with it, though the normally the back end's
 288 .           external idea of what a reloc number would be would be stored
 289 .           in this field. For example, the a PC relative word relocation
 290 .           in a coff environment would have the type 023 - because that's
 291 .           what the outside world calls a R_PCRWORD reloc. *}
 292 .  unsigned int type;
 293 .
 294 .       {*  The value the final relocation is shifted right by. This drops
 295 .           unwanted data from the relocation.  *}
 296 .  unsigned int rightshift;
 297 .
 298 .       {*  The size of the item to be relocated.  This is *not* a
 299 .           power-of-two measure.
 300 .                0 : one byte
 301 .                1 : two bytes
 302 .                2 : four bytes
 303 .                3 : nothing done (unless special_function is nonzero)
 304 .                4 : eight bytes
 305 .               -2 : two bytes, result should be subtracted from the
 306 .                    data instead of added
 307 .           There is currently no trivial way to extract a "number of
 308 .           bytes" from a howto pointer.  *}
 309 .  int size;
 310 .
 311 .       {*  The number of bits in the item to be relocated.  This is used
 312 .           when doing overflow checking.  *}
 313 .  unsigned int bitsize;
 314 .
 315 .       {*  Notes that the relocation is relative to the location in the
 316 .           data section of the addend. The relocation function will
 317 .           subtract from the relocation value the address of the location
 318 .           being relocated. *}
 319 .  boolean pc_relative;
 320 .
 321 .       {*  The bit position of the reloc value in the destination.
 322 .           The relocated value is left shifted by this amount. *}
 323 .  unsigned int bitpos;
 324 .
 325 .       {* What type of overflow error should be checked for when
 326 .          relocating. *}
 327 .  enum complain_overflow complain_on_overflow;
 328 .
 329 .       {* If this field is non null, then the supplied function is
 330 .          called rather than the normal function. This allows really
 331 .          strange relocation methods to be accomodated (e.g., i960 callj
 332 .          instructions). *}
 333 .  bfd_reloc_status_type (*special_function)
 334 .                                   PARAMS ((bfd *abfd,
 335 .                                            arelent *reloc_entry,
 336 .                                            struct symbol_cache_entry *symbol,
 337 .                                            PTR data,
 338 .                                            asection *input_section,
 339 .                                            bfd *output_bfd));
 340 .
 341 .       {* The textual name of the relocation type. *}
 342 .  char *name;
 343 .
 344 .       {* When performing a partial link, some formats must modify the
 345 .          relocations rather than the data - this flag signals this.*}
 346 .  boolean partial_inplace;
 347 .
 348 .       {* The src_mask is used to select what parts of the read in data
 349 .          are to be used in the relocation sum.  E.g., if this was an 8 bit
 350 .          bit of data which we read and relocated, this would be
 351 .          0x000000ff. When we have relocs which have an addend, such as
 352 .          sun4 extended relocs, the value in the offset part of a
 353 .          relocating field is garbage so we never use it. In this case
 354 .          the mask would be 0x00000000. *}
 355 .  bfd_vma src_mask;
 356 .
 357 .       {* The dst_mask is what parts of the instruction are replaced
 358 .          into the instruction. In most cases src_mask == dst_mask,
 359 .          except in the above special case, where dst_mask would be
 360 .          0x000000ff, and src_mask would be 0x00000000.   *}
 361 .  bfd_vma dst_mask;
 362 .
 363 .       {* When some formats create PC relative instructions, they leave
 364 .          the value of the pc of the place being relocated in the offset
 365 .          slot of the instruction, so that a PC relative relocation can
 366 .          be made just by adding in an ordinary offset (e.g., sun3 a.out).
 367 .          Some formats leave the displacement part of an instruction
 368 .          empty (e.g., m88k bcs), this flag signals the fact.*}
 369 .  boolean pcrel_offset;
 370 .
 371 .} reloc_howto_type;
 372
 373 */
 374
 375 /*
 376 FUNCTION
 377         the HOWTO macro
 378
 379 DESCRIPTION
 380         The HOWTO define is horrible and will go away.
 381
 382
 383 .#define HOWTO(C, R,S,B, P, BI, O, SF, NAME, INPLACE, MASKSRC, MASKDST, PC) \
 384 .  {(unsigned)C,R,S,B, P, BI, O,SF,NAME,INPLACE,MASKSRC,MASKDST,PC}
 385
 386 DESCRIPTION
 387         And will be replaced with the totally magic way. But for the
 388         moment, we are compatible, so do it this way..
 389
 390
 391 .#define NEWHOWTO( FUNCTION, NAME,SIZE,REL,IN) HOWTO(0,0,SIZE,0,REL,0,complain_overflow_dont,FUNCTION, NAME,false,0,0,IN)
 392 .
 393 DESCRIPTION
 394         Helper routine to turn a symbol into a relocation value.
 395
 396 .#define HOWTO_PREPARE(relocation, symbol)      \
 397 .  {                                            \
 398 .  if (symbol != (asymbol *)NULL) {             \
 399 .    if (bfd_is_com_section (symbol->section)) { \
 400 .      relocation = 0;                          \
 401 .    }                                          \
 402 .    else {                                     \
 403 .      relocation = symbol->value;              \
 404 .    }                                          \
 405 .  }                                            \
 406 .}
 407
 408 */
 409
 410 /*
 411 TYPEDEF
 412         reloc_chain
 413
 414 DESCRIPTION
 415
 416         How relocs are tied together
 417
 418 .typedef unsigned char bfd_byte;
 419 .
 420 .typedef struct relent_chain {
 421 .  arelent relent;
 422 .  struct   relent_chain *next;
 423 .} arelent_chain;
 424
 425 */
 426
 427
 428
 429 /*
 430 FUNCTION
 431         bfd_perform_relocation
 432
 433 SYNOPSIS
 434         bfd_reloc_status_type
 435                 bfd_perform_relocation
 436                         (bfd * abfd,
 437                         arelent *reloc_entry,
 438                         PTR data,
 439                         asection *input_section,
 440                         bfd *output_bfd);
 441
 442 DESCRIPTION
 443         If an output_bfd is supplied to this function the generated
 444         image will be relocatable, the relocations are copied to the
 445         output file after they have been changed to reflect the new
 446         state of the world. There are two ways of reflecting the
 447         results of partial linkage in an output file; by modifying the
 448         output data in place, and by modifying the relocation record.
 449         Some native formats (e.g., basic a.out and basic coff) have no
 450         way of specifying an addend in the relocation type, so the
 451         addend has to go in the output data.  This is no big deal
 452         since in these formats the output data slot will always be big
 453         enough for the addend. Complex reloc types with addends were
 454         invented to solve just this problem.
 455
 456 */
 457
 458
 459 bfd_reloc_status_type
 460 DEFUN(bfd_perform_relocation,(abfd,
 461                               reloc_entry,
 462                               data,
 463                               input_section,
 464                               output_bfd),
 465       bfd *abfd AND
 466       arelent *reloc_entry AND
 467       PTR data AND
 468       asection *input_section AND
 469       bfd *output_bfd)
 470 {
 471   bfd_vma relocation;
 472   bfd_reloc_status_type flag = bfd_reloc_ok;
 473   bfd_size_type addr = reloc_entry->address ;
 474   bfd_vma output_base = 0;
 475   reloc_howto_type *howto = reloc_entry->howto;
 476   asection *reloc_target_output_section ;
 477
 478   asymbol *symbol;
 479
 480   symbol = *( reloc_entry->sym_ptr_ptr);
 481   if ((symbol->section == &bfd_abs_section)
 482       && output_bfd != (bfd *)NULL)
 483     {
 484       reloc_entry->address += input_section->output_offset;
 485       return bfd_reloc_ok;
 486     }
 487
 488   /* If we are not producing relocateable output, return an error if
 489      the symbol is not defined.  An undefined weak symbol is
 490      considered to have a value of zero (SVR4 ABI, p. 4-27).  */
 491   if (symbol->section == &bfd_und_section
 492       && (symbol->flags & BSF_WEAK) == 0
 493       && output_bfd == (bfd *) NULL)
 494     flag = bfd_reloc_undefined;
 495
 496   /* If there is a function supplied to handle this relocation type,
 497      call it.  It'll return `bfd_reloc_continue' if further processing
 498      can be done.  */
 499   if (howto->special_function)
 500     {
 501       bfd_reloc_status_type cont;
 502       cont = howto->special_function (abfd, reloc_entry, symbol, data,
 503                                       input_section, output_bfd);
 504       if (cont != bfd_reloc_continue)
 505         return cont;
 506     }
 507
 508   /* Is the address of the relocation really within the section?  */
 509   if (reloc_entry->address > input_section->_cooked_size)
 510     return bfd_reloc_outofrange;
 511
 512   /* Work out which section the relocation is targetted at and the
 513      initial relocation command value.  */
 514
 515   /* Get symbol value.  (Common symbols are special.)  */
 516   if (bfd_is_com_section (symbol->section))
 517     relocation = 0;
 518   else
 519     relocation = symbol->value;
 520
 521
 522   reloc_target_output_section = symbol->section->output_section;
 523
 524   /* Convert input-section-relative symbol value to absolute.  */
 525   if (output_bfd && howto->partial_inplace==false)
 526     output_base = 0;
 527   else
 528     output_base = reloc_target_output_section->vma;
 529
 530   relocation += output_base + symbol->section->output_offset;
 531
 532   /* Add in supplied addend.  */
 533   relocation += reloc_entry->addend;
 534
 535   if (howto->pc_relative == true)
 536     {
 537       /* Anything which started out as pc relative should end up that
 538          way too.
 539
 540          There are two ways we can see a pcrel instruction. Sometimes
 541          the pcrel displacement has been partially calculated, it
 542          includes the distance from the start of the section to the
 543          instruction in it (e.g., sun3), and sometimes the field is
 544          totally blank - e.g., m88kbcs.  */
 545
 546       relocation -=
 547         input_section->output_section->vma + input_section->output_offset;
 548
 549       if (howto->pcrel_offset == true)
 550         relocation -= reloc_entry->address;
 551     }
 552
 553   if (output_bfd!= (bfd *)NULL)
 554     {
 555       if ( howto->partial_inplace == false)
 556         {
 557           /* This is a partial relocation, and we want to apply the relocation
 558              to the reloc entry rather than the raw data. Modify the reloc
 559              inplace to reflect what we now know.  */
 560           reloc_entry->addend = relocation;
 561           reloc_entry->address +=  input_section->output_offset;
 562           return flag;
 563         }
 564       else
 565         {
 566           /* This is a partial relocation, but inplace, so modify the
 567              reloc record a bit.
 568
 569              If we've relocated with a symbol with a section, change
 570              into a ref to the section belonging to the symbol.  */
 571
 572           reloc_entry->address += input_section->output_offset;
 573
 574           /* WTF?? */
 575           if (abfd->xvec->flavour == bfd_target_coff_flavour)
 576             {
 577               relocation -= reloc_entry->addend;
 578               reloc_entry->addend = 0;
 579             }
 580           else
 581             {
 582               reloc_entry->addend = relocation;
 583             }
 584         }
 585     }
 586   else
 587     {
 588       reloc_entry->addend = 0;
 589     }
 590
 591   /* FIXME: This overflow checking is incomplete, because the value
 592      might have overflowed before we get here.  For a correct check we
 593      need to compute the value in a size larger than bitsize, but we
 594      can't reasonably do that for a reloc the same size as a host
 595      machine word.
 596      FIXME: We should also do overflow checking on the result after
 597      adding in the value contained in the object file.  */
 598   if (howto->complain_on_overflow != complain_overflow_dont)
 599     {
 600       bfd_vma check;
 601
 602       /* Get the value that will be used for the relocation, but
 603          starting at bit position zero.  */
 604       if (howto->rightshift > howto->bitpos)
 605         check = relocation >> (howto->rightshift - howto->bitpos);
 606       else
 607         check = relocation << (howto->bitpos - howto->rightshift);
 608       switch (howto->complain_on_overflow)
 609         {
 610         case complain_overflow_signed:
 611           {
 612             /* Assumes two's complement.  */
 613             bfd_signed_vma reloc_signed_max = (1 << (howto->bitsize - 1)) - 1;
 614             bfd_signed_vma reloc_signed_min = ~ reloc_signed_max;
 615
 616             /* The above right shift is incorrect for a signed value.
 617                Fix it up by forcing on the upper bits.  */
 618             if (howto->rightshift > howto->bitpos
 619                 && (bfd_signed_vma) relocation < 0)
 620               check |= ((bfd_vma) -1
 621                         &~ ((bfd_vma) -1
 622                             >> (howto->rightshift - howto->bitpos)));
 623             if ((bfd_signed_vma) check > reloc_signed_max
 624                 || (bfd_signed_vma) check < reloc_signed_min)
 625               flag = bfd_reloc_overflow;
 626           }
 627           break;
 628         case complain_overflow_unsigned:
 629           {
 630             /* Assumes two's complement.  This expression avoids
 631                overflow if howto->bitsize is the number of bits in
 632                bfd_vma.  */
 633             bfd_vma reloc_unsigned_max =
 634               (((1 << (howto->bitsize - 1)) - 1) << 1) | 1;
 635
 636             if ((bfd_vma) check > reloc_unsigned_max)
 637               flag = bfd_reloc_overflow;
 638           }
 639           break;
 640         case complain_overflow_bitfield:
 641           {
 642             /* Assumes two's complement.  This expression avoids
 643                overflow if howto->bitsize is the number of bits in
 644                bfd_vma.  */
 645             bfd_vma reloc_bits = (((1 << (howto->bitsize - 1)) - 1) << 1) | 1;
 646
 647             if (((bfd_vma) check &~ reloc_bits) != 0
 648                 && ((bfd_vma) check &~ reloc_bits) != (-1 &~ reloc_bits))
 649               {
 650                 /* The above right shift is incorrect for a signed
 651                    value.  See if turning on the upper bits fixes the
 652                    overflow.  */
 653                 if (howto->rightshift > howto->bitpos
 654                     && (bfd_signed_vma) relocation < 0)
 655                   {
 656                     check |= ((bfd_vma) -1
 657                               &~ ((bfd_vma) -1
 658                                   >> (howto->rightshift - howto->bitpos)));
 659                     if (((bfd_vma) check &~ reloc_bits) != (-1 &~ reloc_bits))
 660                       flag = bfd_reloc_overflow;
 661                   }
 662                 else
 663                   flag = bfd_reloc_overflow;
 664               }
 665           }
 666           break;
 667         default:
 668           abort ();
 669         }
 670     }
 671
 672   /*
 673     Either we are relocating all the way, or we don't want to apply
 674     the relocation to the reloc entry (probably because there isn't
 675     any room in the output format to describe addends to relocs)
 676     */
 677   relocation >>= howto->rightshift;
 678
 679   /* Shift everything up to where it's going to be used */
 680
 681   relocation <<= howto->bitpos;
 682
 683   /* Wait for the day when all have the mask in them */
 684
 685   /* What we do:
 686      i instruction to be left alone
 687      o offset within instruction
 688      r relocation offset to apply
 689      S src mask
 690      D dst mask
 691      N ~dst mask
 692      A part 1
 693      B part 2
 694      R result
 695
 696      Do this:
 697      i i i i i o o o o o        from bfd_get<size>
 698      and           S S S S S    to get the size offset we want
 699      +   r r r r r r r r r r  to get the final value to place
 700      and           D D D D D  to chop to right size
 701      -----------------------
 702      A A A A A
 703      And this:
 704      ...   i i i i i o o o o o  from bfd_get<size>
 705      and   N N N N N            get instruction
 706      -----------------------
 707      ...   B B B B B
 708
 709      And then:
 710      B B B B B
 711      or              A A A A A
 712      -----------------------
 713      R R R R R R R R R R        put into bfd_put<size>
 714      */
 715
 716 #define DOIT(x) \
 717   x = ( (x & ~howto->dst_mask) | (((x & howto->src_mask) +  relocation) & howto->dst_mask))
 718
 719    switch (howto->size)
 720      {
 721      case 0:
 722        {
 723          char x = bfd_get_8(abfd, (char *)data + addr);
 724          DOIT(x);
 725          bfd_put_8(abfd,x, (unsigned char *) data + addr);
 726        }
 727        break;
 728
 729      case 1:
 730        if (relocation)
 731          {
 732            short x = bfd_get_16(abfd, (bfd_byte *)data + addr);
 733            DOIT(x);
 734            bfd_put_16(abfd, x,   (unsigned char *)data + addr);
 735          }
 736        break;
 737      case 2:
 738        if (relocation)
 739          {
 740            long  x = bfd_get_32 (abfd, (bfd_byte *) data + addr);
 741            DOIT (x);
 742            bfd_put_32 (abfd, x, (bfd_byte *)data + addr);
 743          }
 744        break;
 745      case -2:
 746        {
 747          long  x = bfd_get_32(abfd, (bfd_byte *) data + addr);
 748          relocation = -relocation;
 749          DOIT(x);
 750          bfd_put_32(abfd,x,    (bfd_byte *)data + addr);
 751        }
 752        break;
 753
 754      case 3:
 755        /* Do nothing */
 756        break;
 757
 758      case 4:
 759 #ifdef BFD64
 760        if (relocation)
 761          {
 762            bfd_vma x = bfd_get_64 (abfd, (bfd_byte *) data + addr);
 763            DOIT (x);
 764            bfd_put_64 (abfd, x, (bfd_byte *) data + addr);
 765          }
 766 #else
 767        abort ();
 768 #endif
 769        break;
 770      default:
 771        return bfd_reloc_other;
 772      }
 773
 774   return flag;
 775 }
 776
 777
 778
 779 /*
 780 DOCDD
 781 INODE
 782         howto manager,  , typedef arelent, Relocations
 783
 784 SECTION
 785         The howto manager
 786
 787         When an application wants to create a relocation, but doesn't
 788         know what the target machine might call it, it can find out by
 789         using this bit of code.
 790
 791 */
 792
 793 /*
 794 TYPEDEF
 795         bfd_reloc_code_type
 796
 797 DESCRIPTION
 798         The insides of a reloc code.  The idea is that, eventually, there
 799         will be one enumerator for every type of relocation we ever do.
 800         Pass one of these values to <<bfd_reloc_type_lookup>>, and it'll
 801         return a howto pointer.
 802
 803         This does mean that the application must determine the correct
 804         enumerator value; you can't get a howto pointer from a random set
 805         of attributes.
 806
 807 CODE_FRAGMENT
 808 .
 809 .typedef enum bfd_reloc_code_real
 810 .{
 811 .  {* Basic absolute relocations *}
 812 .  BFD_RELOC_64,
 813 .  BFD_RELOC_32,
 814 .  BFD_RELOC_16,
 815 .  BFD_RELOC_8,
 816 .
 817 .  {* PC-relative relocations *}
 818 .  BFD_RELOC_64_PCREL,
 819 .  BFD_RELOC_32_PCREL,
 820 .  BFD_RELOC_24_PCREL,    {* used by i960 *}
 821 .  BFD_RELOC_16_PCREL,
 822 .  BFD_RELOC_8_PCREL,
 823 .
 824 .  {* Linkage-table relative *}
 825 .  BFD_RELOC_32_BASEREL,
 826 .  BFD_RELOC_16_BASEREL,
 827 .  BFD_RELOC_8_BASEREL,
 828 .
 829 .  {* The type of reloc used to build a contructor table - at the moment
 830 .     probably a 32 bit wide abs address, but the cpu can choose. *}
 831 .  BFD_RELOC_CTOR,
 832 .
 833 .  {* 8 bits wide, but used to form an address like 0xffnn *}
 834 .  BFD_RELOC_8_FFnn,
 835 .
 836 .  {* 32-bit pc-relative, shifted right 2 bits (i.e., 30-bit
 837 .     word displacement, e.g. for SPARC) *}
 838 .  BFD_RELOC_32_PCREL_S2,
 839 .
 840 .  {* High 22 bits of 32-bit value, placed into lower 22 bits of
 841 .     target word; simple reloc.  *}
 842 .  BFD_RELOC_HI22,
 843 .  {* Low 10 bits.  *}
 844 .  BFD_RELOC_LO10,
 845 .
 846 .  {* Reloc types used for i960/b.out.  *}
 847 .  BFD_RELOC_I960_CALLJ,
 848 .
 849 .  {* now for the sparc/elf codes *}
 850 .  BFD_RELOC_NONE,              {* actually used *}
 851 .  BFD_RELOC_SPARC_WDISP22,
 852 .  BFD_RELOC_SPARC22,
 853 .  BFD_RELOC_SPARC13,
 854 .  BFD_RELOC_SPARC_GOT10,
 855 .  BFD_RELOC_SPARC_GOT13,
 856 .  BFD_RELOC_SPARC_GOT22,
 857 .  BFD_RELOC_SPARC_PC10,
 858 .  BFD_RELOC_SPARC_PC22,
 859 .  BFD_RELOC_SPARC_WPLT30,
 860 .  BFD_RELOC_SPARC_COPY,
 861 .  BFD_RELOC_SPARC_GLOB_DAT,
 862 .  BFD_RELOC_SPARC_JMP_SLOT,
 863 .  BFD_RELOC_SPARC_RELATIVE,
 864 .  BFD_RELOC_SPARC_UA32,
 865 .
 866 .  {* these are a.out specific? *}
 867 .  BFD_RELOC_SPARC_BASE13,
 868 .  BFD_RELOC_SPARC_BASE22,
 869 .
 870 .  {* start-sanitize-v9 *}
 871 .  BFD_RELOC_SPARC_10,
 872 .  BFD_RELOC_SPARC_11,
 873 .#define  BFD_RELOC_SPARC_64 BFD_RELOC_64
 874 .  BFD_RELOC_SPARC_OLO10,
 875 .  BFD_RELOC_SPARC_HH22,
 876 .  BFD_RELOC_SPARC_HM10,
 877 .  BFD_RELOC_SPARC_LM22,
 878 .  BFD_RELOC_SPARC_PC_HH22,
 879 .  BFD_RELOC_SPARC_PC_HM10,
 880 .  BFD_RELOC_SPARC_PC_LM22,
 881 .  BFD_RELOC_SPARC_WDISP16,
 882 .  BFD_RELOC_SPARC_WDISP19,
 883 .  BFD_RELOC_SPARC_GLOB_JMP,
 884 .  BFD_RELOC_SPARC_LO7,
 885 .  {* end-sanitize-v9 *}
 886 .
 887 .  {* Bits 27..2 of the relocation address shifted right 2 bits;
 888 .     simple reloc otherwise.  *}
 889 .  BFD_RELOC_MIPS_JMP,
 890 .
 891 .  {* signed 16-bit pc-relative, shifted right 2 bits (e.g. for MIPS) *}
 892 .  BFD_RELOC_16_PCREL_S2,
 893 .
 894 .  {* High 16 bits of 32-bit value; simple reloc.  *}
 895 .  BFD_RELOC_HI16,
 896 .  {* High 16 bits of 32-bit value but the low 16 bits will be sign
 897 .     extended and added to form the final result.  If the low 16
 898 .     bits form a negative number, we need to add one to the high value
 899 .     to compensate for the borrow when the low bits are added.  *}
 900 .  BFD_RELOC_HI16_S,
 901 .  {* Low 16 bits.  *}
 902 .  BFD_RELOC_LO16,
 903 .
 904 .  {* 16 bit relocation relative to the global pointer.  *}
 905 .  BFD_RELOC_MIPS_GPREL,
 906 .
 907 .  {* These are, so far, specific to HPPA processors.  I'm not sure that some
 908 .     don't duplicate other reloc types, such as BFD_RELOC_32 and _32_PCREL.
 909 .     Also, many more were in the list I got that don't fit in well in the
 910 .     model BFD uses, so I've omitted them for now.  If we do make this reloc
 911 .     type get used for code that really does implement the funky reloc types,
 912 .     they'll have to be added to this list.  *}
 913 .  BFD_RELOC_HPPA_32,
 914 .  BFD_RELOC_HPPA_11,
 915 .  BFD_RELOC_HPPA_14,
 916 .  BFD_RELOC_HPPA_17,
 917 .
 918 .  BFD_RELOC_HPPA_L21,
 919 .  BFD_RELOC_HPPA_R11,
 920 .  BFD_RELOC_HPPA_R14,
 921 .  BFD_RELOC_HPPA_R17,
 922 .  BFD_RELOC_HPPA_LS21,
 923 .  BFD_RELOC_HPPA_RS11,
 924 .  BFD_RELOC_HPPA_RS14,
 925 .  BFD_RELOC_HPPA_RS17,
 926 .  BFD_RELOC_HPPA_LD21,
 927 .  BFD_RELOC_HPPA_RD11,
 928 .  BFD_RELOC_HPPA_RD14,
 929 .  BFD_RELOC_HPPA_RD17,
 930 .  BFD_RELOC_HPPA_LR21,
 931 .  BFD_RELOC_HPPA_RR14,
 932 .  BFD_RELOC_HPPA_RR17,
 933 .
 934 .  BFD_RELOC_HPPA_GOTOFF_11,
 935 .  BFD_RELOC_HPPA_GOTOFF_14,
 936 .  BFD_RELOC_HPPA_GOTOFF_L21,
 937 .  BFD_RELOC_HPPA_GOTOFF_R11,
 938 .  BFD_RELOC_HPPA_GOTOFF_R14,
 939 .  BFD_RELOC_HPPA_GOTOFF_LS21,
 940 .  BFD_RELOC_HPPA_GOTOFF_RS11,
 941 .  BFD_RELOC_HPPA_GOTOFF_RS14,
 942 .  BFD_RELOC_HPPA_GOTOFF_LD21,
 943 .  BFD_RELOC_HPPA_GOTOFF_RD11,
 944 .  BFD_RELOC_HPPA_GOTOFF_RD14,
 945 .  BFD_RELOC_HPPA_GOTOFF_LR21,
 946 .  BFD_RELOC_HPPA_GOTOFF_RR14,
 947 .
 948 .  BFD_RELOC_HPPA_DLT_32,
 949 .  BFD_RELOC_HPPA_DLT_11,
 950 .  BFD_RELOC_HPPA_DLT_14,
 951 .  BFD_RELOC_HPPA_DLT_L21,
 952 .  BFD_RELOC_HPPA_DLT_R11,
 953 .  BFD_RELOC_HPPA_DLT_R14,
 954 .
 955 .  BFD_RELOC_HPPA_ABS_CALL_11,
 956 .  BFD_RELOC_HPPA_ABS_CALL_14,
 957 .  BFD_RELOC_HPPA_ABS_CALL_17,
 958 .  BFD_RELOC_HPPA_ABS_CALL_L21,
 959 .  BFD_RELOC_HPPA_ABS_CALL_R11,
 960 .  BFD_RELOC_HPPA_ABS_CALL_R14,
 961 .  BFD_RELOC_HPPA_ABS_CALL_R17,
 962 .  BFD_RELOC_HPPA_ABS_CALL_LS21,
 963 .  BFD_RELOC_HPPA_ABS_CALL_RS11,
 964 .  BFD_RELOC_HPPA_ABS_CALL_RS14,
 965 .  BFD_RELOC_HPPA_ABS_CALL_RS17,
 966 .  BFD_RELOC_HPPA_ABS_CALL_LD21,
 967 .  BFD_RELOC_HPPA_ABS_CALL_RD11,
 968 .  BFD_RELOC_HPPA_ABS_CALL_RD14,
 969 .  BFD_RELOC_HPPA_ABS_CALL_RD17,
 970 .  BFD_RELOC_HPPA_ABS_CALL_LR21,
 971 .  BFD_RELOC_HPPA_ABS_CALL_RR14,
 972 .  BFD_RELOC_HPPA_ABS_CALL_RR17,
 973 .
 974 .  BFD_RELOC_HPPA_PCREL_CALL_11,
 975 .  BFD_RELOC_HPPA_PCREL_CALL_12,
 976 .  BFD_RELOC_HPPA_PCREL_CALL_14,
 977 .  BFD_RELOC_HPPA_PCREL_CALL_17,
 978 .  BFD_RELOC_HPPA_PCREL_CALL_L21,
 979 .  BFD_RELOC_HPPA_PCREL_CALL_R11,
 980 .  BFD_RELOC_HPPA_PCREL_CALL_R14,
 981 .  BFD_RELOC_HPPA_PCREL_CALL_R17,
 982 .  BFD_RELOC_HPPA_PCREL_CALL_LS21,
 983 .  BFD_RELOC_HPPA_PCREL_CALL_RS11,
 984 .  BFD_RELOC_HPPA_PCREL_CALL_RS14,
 985 .  BFD_RELOC_HPPA_PCREL_CALL_RS17,
 986 .  BFD_RELOC_HPPA_PCREL_CALL_LD21,
 987 .  BFD_RELOC_HPPA_PCREL_CALL_RD11,
 988 .  BFD_RELOC_HPPA_PCREL_CALL_RD14,
 989 .  BFD_RELOC_HPPA_PCREL_CALL_RD17,
 990 .  BFD_RELOC_HPPA_PCREL_CALL_LR21,
 991 .  BFD_RELOC_HPPA_PCREL_CALL_RR14,
 992 .  BFD_RELOC_HPPA_PCREL_CALL_RR17,
 993 .
 994 .  BFD_RELOC_HPPA_PLABEL_32,
 995 .  BFD_RELOC_HPPA_PLABEL_11,
 996 .  BFD_RELOC_HPPA_PLABEL_14,
 997 .  BFD_RELOC_HPPA_PLABEL_L21,
 998 .  BFD_RELOC_HPPA_PLABEL_R11,
 999 .  BFD_RELOC_HPPA_PLABEL_R14,
1000 .
1001 .  BFD_RELOC_HPPA_UNWIND_ENTRY,
1002 .  BFD_RELOC_HPPA_UNWIND_ENTRIES,
1003 .
1004 .  {* i386/elf relocations *}
1005 .  BFD_RELOC_386_GOT32,
1006 .  BFD_RELOC_386_PLT32,
1007 .  BFD_RELOC_386_COPY,
1008 .  BFD_RELOC_386_GLOB_DAT,
1009 .  BFD_RELOC_386_JUMP_SLOT,
1010 .  BFD_RELOC_386_RELATIVE,
1011 .  BFD_RELOC_386_GOTOFF,
1012 .  BFD_RELOC_386_GOTPC,
1013 .
1014 .  {* this must be the highest numeric value *}
1015 .  BFD_RELOC_UNUSED
1016 . } bfd_reloc_code_real_type;
1017 */
1018
1019
1020 /*
1021 SECTION
1022         bfd_reloc_type_lookup
1023
1024 SYNOPSIS
1025         CONST struct reloc_howto_struct *
1026         bfd_reloc_type_lookup (bfd *abfd, bfd_reloc_code_real_type code);
1027
1028 DESCRIPTION
1029         This routine returns a pointer to a howto struct which when
1030         invoked, will perform the supplied relocation on data from the
1031         architecture noted.
1032
1033 */
1034
1035
1036 CONST struct reloc_howto_struct *
1037 DEFUN(bfd_reloc_type_lookup,(abfd, code),
1038       bfd *abfd AND
1039       bfd_reloc_code_real_type code)
1040 {
1041   return BFD_SEND (abfd, reloc_type_lookup, (abfd, code));
1042 }
1043
1044 static reloc_howto_type bfd_howto_32 =
1045  HOWTO(0, 00,2,32,false,0,complain_overflow_bitfield,0,"VRT32", false,0xffffffff,0xffffffff,true);
1046
1047
1048 /*
1049 INTERNAL_FUNCTION
1050         bfd_default_reloc_type_lookup
1051
1052 SYNOPSIS
1053         CONST struct reloc_howto_struct *bfd_default_reloc_type_lookup
1054         (bfd *abfd AND
1055          bfd_reloc_code_real_type  code);
1056
1057 DESCRIPTION
1058         Provides a default relocation lookup routine for any architecture.
1059
1060
1061 */
1062
1063 CONST struct reloc_howto_struct *
1064 DEFUN(bfd_default_reloc_type_lookup, (abfd, code),
1065       bfd *abfd AND
1066       bfd_reloc_code_real_type code)
1067 {
1068   switch (code)
1069     {
1070     case BFD_RELOC_CTOR:
1071       /* The type of reloc used in a ctor, which will be as wide as the
1072          address - so either a 64, 32, or 16 bitter.  */
1073       switch (bfd_get_arch_info (abfd)->bits_per_address) {
1074       case 64:
1075         BFD_FAIL();
1076       case 32:
1077         return &bfd_howto_32;
1078       case 16:
1079         BFD_FAIL();
1080       default:
1081         BFD_FAIL();
1082       }
1083     default:
1084       BFD_FAIL();
1085     }
1086   return (CONST struct reloc_howto_struct *)NULL;
1087 }
1088
1089
1090 /*
1091 INTERNAL_FUNCTION
1092         bfd_generic_relax_section
1093
1094 SYNOPSIS
1095         boolean bfd_generic_relax_section
1096          (bfd *abfd,
1097           asection *section,
1098           asymbol **symbols);
1099
1100 DESCRIPTION
1101         Provides default handling for relaxing for back ends which
1102         don't do relaxing -- i.e., does nothing.
1103 */
1104
1105 boolean
1106 DEFUN(bfd_generic_relax_section,(abfd, section, symbols),
1107       bfd *abfd AND
1108       asection *section AND
1109       asymbol **symbols)
1110 {
1111
1112   return false;
1113
1114 }
1115
1116
1117 /*
1118 INTERNAL_FUNCTION
1119         bfd_generic_get_relocated_section_contents
1120
1121 SYNOPSIS
1122         bfd_byte *
1123            bfd_generic_get_relocated_section_contents (bfd *abfd,
1124              struct bfd_seclet *seclet,
1125              bfd_byte *data,
1126              boolean relocateable);
1127
1128 DESCRIPTION
1129         Provides default handling of relocation effort for back ends
1130         which can't be bothered to do it efficiently.
1131
1132 */
1133
1134 bfd_byte *
1135 DEFUN(bfd_generic_get_relocated_section_contents,(abfd,
1136                                                   seclet,
1137                                                   data,
1138                                                   relocateable),
1139       bfd *abfd AND
1140       struct bfd_seclet *seclet AND
1141       bfd_byte *data AND
1142       boolean relocateable)
1143 {
1144   extern bfd_error_vector_type bfd_error_vector;
1145
1146   /* Get enough memory to hold the stuff */
1147   bfd *input_bfd = seclet->u.indirect.section->owner;
1148   asection *input_section = seclet->u.indirect.section;
1149
1150
1151
1152   size_t reloc_size = bfd_get_reloc_upper_bound(input_bfd, input_section);
1153   arelent **reloc_vector = (arelent **) alloca(reloc_size);
1154
1155   /* read in the section */
1156   bfd_get_section_contents(input_bfd,
1157                            input_section,
1158                            data,
1159                            0,
1160                            input_section->_raw_size);
1161
1162 /* We're not relaxing the section, so just copy the size info */
1163   input_section->_cooked_size = input_section->_raw_size;
1164   input_section->reloc_done = true;
1165
1166
1167   if (bfd_canonicalize_reloc(input_bfd,
1168                              input_section,
1169                              reloc_vector,
1170                              seclet->u.indirect.symbols) )
1171   {
1172     arelent **parent;
1173     for (parent = reloc_vector;  * parent != (arelent *)NULL;
1174          parent++)
1175     {
1176       bfd_reloc_status_type r=
1177        bfd_perform_relocation(input_bfd,
1178                               *parent,
1179                               data,
1180                               input_section,
1181                               relocateable ? abfd : (bfd *) NULL);
1182
1183       if (relocateable)
1184         {
1185           asection *os = input_section->output_section;
1186
1187           /* A partial link, so keep the relocs */
1188           os->orelocation[os->reloc_count] = *parent;
1189           os->reloc_count++;
1190         }
1191
1192       if (r != bfd_reloc_ok)
1193       {
1194         switch (r)
1195         {
1196         case bfd_reloc_undefined:
1197           bfd_error_vector.undefined_symbol(*parent, seclet);
1198           break;
1199         case bfd_reloc_dangerous:
1200           bfd_error_vector.reloc_dangerous(*parent, seclet);
1201           break;
1202         case bfd_reloc_outofrange:
1203         case bfd_reloc_overflow:
1204           bfd_error_vector.reloc_value_truncated(*parent, seclet);
1205           break;
1206         default:
1207           abort();
1208           break;
1209         }
1210
1211       }
1212     }
1213   }
1214
1215
1216   return data;
1217
1218
1219 }