bfd/coff-m68k.c

   1 /* BFD back-end for Motorola 68000 COFF binaries.
   2    Copyright 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1999, 2000
   3    Free Software Foundation, Inc.
   4    Written by Cygnus Support.
   5
   6 This file is part of BFD, the Binary File Descriptor library.
   7
   8 This program is free software; you can redistribute it and/or modify
   9 it under the terms of the GNU General Public License as published by
  10 the Free Software Foundation; either version 2 of the License, or
  11 (at your option) any later version.
  12
  13 This program is distributed in the hope that it will be useful,
  14 but WITHOUT ANY WARRANTY; without even the implied warranty of
  15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16 GNU General Public License for more details.
  17
  18 You should have received a copy of the GNU General Public License
  19 along with this program; if not, write to the Free Software
  20 Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
  21
  22 #include "bfd.h"
  23 #include "sysdep.h"
  24 #include "libbfd.h"
  25 #include "coff/m68k.h"
  26 #include "coff/internal.h"
  27 #include "libcoff.h"
  28
  29 /* This source file is compiled multiple times for various m68k COFF
  30    variants.  The following macros control its behaviour:
  31
  32    TARGET_SYM
  33      The C name of the BFD target vector.  The default is m68kcoff_vec.
  34    TARGET_NAME
  35      The user visible target name.  The default is "coff-m68k".
  36    NAMES_HAVE_UNDERSCORE
  37      Whether symbol names have an underscore.
  38    ONLY_DECLARE_RELOCS
  39      Only declare the relocation howto array.  Don't actually compile
  40      it.  The actual array will be picked up in another version of the
  41      file.
  42    STATIC_RELOCS
  43      Make the relocation howto array, and associated functions, static.
  44    COFF_COMMON_ADDEND
  45      If this is defined, then, for a relocation against a common
  46      symbol, the object file holds the value (the size) of the common
  47      symbol.  If this is not defined, then, for a relocation against a
  48      common symbol, the object file holds zero.  */
  49
  50 #define COFF_DEFAULT_SECTION_ALIGNMENT_POWER (2)
  51
  52 #ifndef COFF_PAGE_SIZE
  53 /* The page size is a guess based on ELF.  */
  54 #define COFF_PAGE_SIZE 0x2000
  55 #endif
  56
  57 #ifndef COFF_COMMON_ADDEND
  58 #define RELOC_SPECIAL_FN 0
  59 #else
  60 static bfd_reloc_status_type m68kcoff_common_addend_special_fn
  61   PARAMS ((bfd *, arelent *, asymbol *, PTR, asection *, bfd *, char **));
  62 static reloc_howto_type *m68kcoff_common_addend_rtype_to_howto
  63   PARAMS ((bfd *, asection *, struct internal_reloc *,
  64            struct coff_link_hash_entry *, struct internal_syment *,
  65            bfd_vma *));
  66 #define RELOC_SPECIAL_FN m68kcoff_common_addend_special_fn
  67 #endif
  68
  69 static boolean m68k_coff_is_local_label_name PARAMS ((bfd *, const char *));
  70
  71 /* On the delta, a symbol starting with L% is local.  We won't see
  72    such a symbol on other platforms, so it should be safe to always
  73    consider it local here.  */
  74
  75 static boolean
  76 m68k_coff_is_local_label_name (abfd, name)
  77      bfd *abfd;
  78      const char *name;
  79 {
  80   if (name[0] == 'L' && name[1] == '%')
  81     return true;
  82
  83   return _bfd_coff_is_local_label_name (abfd, name);
  84 }
  85
  86 #ifndef STATIC_RELOCS
  87 /* Clean up namespace.  */
  88 #define m68kcoff_howto_table    _bfd_m68kcoff_howto_table
  89 #define m68k_rtype2howto        _bfd_m68kcoff_rtype2howto
  90 #define m68k_howto2rtype        _bfd_m68kcoff_howto2rtype
  91 #define m68k_reloc_type_lookup  _bfd_m68kcoff_reloc_type_lookup
  92 #endif
  93
  94 #ifdef ONLY_DECLARE_RELOCS
  95 extern reloc_howto_type m68kcoff_howto_table[];
  96 #else
  97 #ifdef STATIC_RELOCS
  98 static
  99 #endif
 100 reloc_howto_type m68kcoff_howto_table[] =
 101 {
 102   HOWTO(R_RELBYTE,             0,  0,   8,  false, 0, complain_overflow_bitfield, RELOC_SPECIAL_FN, "8",        true, 0x000000ff,0x000000ff, false),
 103   HOWTO(R_RELWORD,             0,  1,   16, false, 0, complain_overflow_bitfield, RELOC_SPECIAL_FN, "16",       true, 0x0000ffff,0x0000ffff, false),
 104   HOWTO(R_RELLONG,             0,  2,   32, false, 0, complain_overflow_bitfield, RELOC_SPECIAL_FN, "32",       true, 0xffffffff,0xffffffff, false),
 105   HOWTO(R_PCRBYTE,             0,  0,   8,  true,  0, complain_overflow_signed, RELOC_SPECIAL_FN, "DISP8",    true, 0x000000ff,0x000000ff, false),
 106   HOWTO(R_PCRWORD,             0,  1,   16, true,  0, complain_overflow_signed, RELOC_SPECIAL_FN, "DISP16",   true, 0x0000ffff,0x0000ffff, false),
 107   HOWTO(R_PCRLONG,             0,  2,   32, true,  0, complain_overflow_signed, RELOC_SPECIAL_FN, "DISP32",   true, 0xffffffff,0xffffffff, false),
 108   HOWTO(R_RELLONG_NEG,         0,  -2,  32, false, 0, complain_overflow_bitfield, RELOC_SPECIAL_FN, "-32",      true, 0xffffffff,0xffffffff, false),
 109 };
 110 #endif /* not ONLY_DECLARE_RELOCS */
 111
 112 #ifndef BADMAG
 113 #define BADMAG(x) M68KBADMAG(x)
 114 #endif
 115 #define M68 1           /* Customize coffcode.h */
 116
 117 /* Turn a howto into a reloc number */
 118
 119 #ifdef ONLY_DECLARE_RELOCS
 120 extern void m68k_rtype2howto PARAMS ((arelent *internal, int relocentry));
 121 extern int m68k_howto2rtype PARAMS ((reloc_howto_type *));
 122 extern reloc_howto_type *m68k_reloc_type_lookup
 123   PARAMS ((bfd *, bfd_reloc_code_real_type));
 124 #else
 125 #ifdef STATIC_RELOCS
 126 static
 127 #endif
 128 void
 129 m68k_rtype2howto(internal, relocentry)
 130      arelent *internal;
 131      int relocentry;
 132 {
 133   switch (relocentry)
 134   {
 135    case R_RELBYTE:      internal->howto = m68kcoff_howto_table + 0; break;
 136    case R_RELWORD:      internal->howto = m68kcoff_howto_table + 1; break;
 137    case R_RELLONG:      internal->howto = m68kcoff_howto_table + 2; break;
 138    case R_PCRBYTE:      internal->howto = m68kcoff_howto_table + 3; break;
 139    case R_PCRWORD:      internal->howto = m68kcoff_howto_table + 4; break;
 140    case R_PCRLONG:      internal->howto = m68kcoff_howto_table + 5; break;
 141    case R_RELLONG_NEG:  internal->howto = m68kcoff_howto_table + 6; break;
 142   }
 143 }
 144
 145 #ifdef STATIC_RELOCS
 146 static
 147 #endif
 148 int
 149 m68k_howto2rtype (internal)
 150      reloc_howto_type *internal;
 151 {
 152   if (internal->pc_relative)
 153   {
 154     switch (internal->bitsize)
 155     {
 156      case 32: return R_PCRLONG;
 157      case 16: return R_PCRWORD;
 158      case 8: return R_PCRBYTE;
 159     }
 160   }
 161   else
 162   {
 163     switch (internal->bitsize)
 164      {
 165       case 32: return R_RELLONG;
 166       case 16: return R_RELWORD;
 167       case 8: return R_RELBYTE;
 168      }
 169   }
 170   return R_RELLONG;
 171 }
 172
 173 #ifdef STATIC_RELOCS
 174 static
 175 #endif
 176 reloc_howto_type *
 177 m68k_reloc_type_lookup (abfd, code)
 178      bfd *abfd ATTRIBUTE_UNUSED;
 179      bfd_reloc_code_real_type code;
 180 {
 181   switch (code)
 182     {
 183     default:                    return NULL;
 184     case BFD_RELOC_8:           return m68kcoff_howto_table + 0;
 185     case BFD_RELOC_16:          return m68kcoff_howto_table + 1;
 186     case BFD_RELOC_CTOR:
 187     case BFD_RELOC_32:          return m68kcoff_howto_table + 2;
 188     case BFD_RELOC_8_PCREL:     return m68kcoff_howto_table + 3;
 189     case BFD_RELOC_16_PCREL:    return m68kcoff_howto_table + 4;
 190     case BFD_RELOC_32_PCREL:    return m68kcoff_howto_table + 5;
 191       /* FIXME: There doesn't seem to be a code for R_RELLONG_NEG.  */
 192     }
 193   /*NOTREACHED*/
 194 }
 195
 196 #endif /* not ONLY_DECLARE_RELOCS */
 197
 198 #define RTYPE2HOWTO(internal, relocentry) \
 199   m68k_rtype2howto(internal, (relocentry)->r_type)
 200
 201 #define SELECT_RELOC(external, internal) \
 202   external.r_type = m68k_howto2rtype (internal)
 203
 204 #define coff_bfd_reloc_type_lookup m68k_reloc_type_lookup
 205
 206 #ifndef COFF_COMMON_ADDEND
 207 #ifndef coff_rtype_to_howto
 208
 209 #define coff_rtype_to_howto m68kcoff_rtype_to_howto
 210
 211 static reloc_howto_type *m68kcoff_rtype_to_howto
 212   PARAMS ((bfd *, asection *, struct internal_reloc *,
 213            struct coff_link_hash_entry *, struct internal_syment *,
 214            bfd_vma *));
 215
 216 static reloc_howto_type *
 217 m68kcoff_rtype_to_howto (abfd, sec, rel, h, sym, addendp)
 218      bfd *abfd ATTRIBUTE_UNUSED;
 219      asection *sec;
 220      struct internal_reloc *rel;
 221      struct coff_link_hash_entry *h ATTRIBUTE_UNUSED;
 222      struct internal_syment *sym ATTRIBUTE_UNUSED;
 223      bfd_vma *addendp;
 224 {
 225   arelent relent;
 226   reloc_howto_type *howto;
 227
 228   RTYPE2HOWTO (&relent, rel);
 229
 230   howto = relent.howto;
 231
 232   if (howto->pc_relative)
 233     *addendp += sec->vma;
 234
 235   return howto;
 236 }
 237
 238 #endif /* ! defined (coff_rtype_to_howto) */
 239 #endif /* ! defined (COFF_COMMON_ADDEND) */
 240 \f
 241 #ifdef COFF_COMMON_ADDEND
 242
 243 /* If COFF_COMMON_ADDEND is defined, then when using m68k COFF the
 244    value stored in the .text section for a reference to a common
 245    symbol is the value itself plus any desired offset.  (taken from
 246    work done by Ian Taylor, Cygnus Support, for I386 COFF).  */
 247
 248 /* If we are producing relocateable output, we need to do some
 249    adjustments to the object file that are not done by the
 250    bfd_perform_relocation function.  This function is called by every
 251    reloc type to make any required adjustments.  */
 252
 253 static bfd_reloc_status_type
 254 m68kcoff_common_addend_special_fn (abfd, reloc_entry, symbol, data,
 255                                    input_section, output_bfd, error_message)
 256      bfd *abfd;
 257      arelent *reloc_entry;
 258      asymbol *symbol;
 259      PTR data;
 260      asection *input_section ATTRIBUTE_UNUSED;
 261      bfd *output_bfd;
 262      char **error_message ATTRIBUTE_UNUSED;
 263 {
 264   symvalue diff;
 265
 266   if (output_bfd == (bfd *) NULL)
 267     return bfd_reloc_continue;
 268
 269   if (bfd_is_com_section (symbol->section))
 270     {
 271       /* We are relocating a common symbol.  The current value in the
 272          object file is ORIG + OFFSET, where ORIG is the value of the
 273          common symbol as seen by the object file when it was compiled
 274          (this may be zero if the symbol was undefined) and OFFSET is
 275          the offset into the common symbol (normally zero, but may be
 276          non-zero when referring to a field in a common structure).
 277          ORIG is the negative of reloc_entry->addend, which is set by
 278          the CALC_ADDEND macro below.  We want to replace the value in
 279          the object file with NEW + OFFSET, where NEW is the value of
 280          the common symbol which we are going to put in the final
 281          object file.  NEW is symbol->value.  */
 282       diff = symbol->value + reloc_entry->addend;
 283     }
 284   else
 285     {
 286       /* For some reason bfd_perform_relocation always effectively
 287          ignores the addend for a COFF target when producing
 288          relocateable output.  This seems to be always wrong for 386
 289          COFF, so we handle the addend here instead.  */
 290       diff = reloc_entry->addend;
 291     }
 292
 293 #define DOIT(x) \
 294   x = ((x & ~howto->dst_mask) | (((x & howto->src_mask) + diff) & howto->dst_mask))
 295
 296   if (diff != 0)
 297     {
 298       reloc_howto_type *howto = reloc_entry->howto;
 299       unsigned char *addr = (unsigned char *) data + reloc_entry->address;
 300
 301       switch (howto->size)
 302         {
 303         case 0:
 304           {
 305             char x = bfd_get_8 (abfd, addr);
 306             DOIT (x);
 307             bfd_put_8 (abfd, x, addr);
 308           }
 309           break;
 310
 311         case 1:
 312           {
 313             short x = bfd_get_16 (abfd, addr);
 314             DOIT (x);
 315             bfd_put_16 (abfd, x, addr);
 316           }
 317           break;
 318
 319         case 2:
 320           {
 321             long x = bfd_get_32 (abfd, addr);
 322             DOIT (x);
 323             bfd_put_32 (abfd, x, addr);
 324           }
 325           break;
 326
 327         default:
 328           abort ();
 329         }
 330     }
 331
 332   /* Now let bfd_perform_relocation finish everything up.  */
 333   return bfd_reloc_continue;
 334 }
 335
 336 /* Compute the addend of a reloc.  If the reloc is to a common symbol,
 337    the object file contains the value of the common symbol.  By the
 338    time this is called, the linker may be using a different symbol
 339    from a different object file with a different value.  Therefore, we
 340    hack wildly to locate the original symbol from this file so that we
 341    can make the correct adjustment.  This macro sets coffsym to the
 342    symbol from the original file, and uses it to set the addend value
 343    correctly.  If this is not a common symbol, the usual addend
 344    calculation is done, except that an additional tweak is needed for
 345    PC relative relocs.
 346    FIXME: This macro refers to symbols and asect; these are from the
 347    calling function, not the macro arguments.  */
 348
 349 #define CALC_ADDEND(abfd, ptr, reloc, cache_ptr)                \
 350   {                                                             \
 351     coff_symbol_type *coffsym = (coff_symbol_type *) NULL;      \
 352     if (ptr && bfd_asymbol_bfd (ptr) != abfd)                   \
 353       coffsym = (obj_symbols (abfd)                             \
 354                  + (cache_ptr->sym_ptr_ptr - symbols));         \
 355     else if (ptr)                                               \
 356       coffsym = coff_symbol_from (abfd, ptr);                   \
 357     if (coffsym != (coff_symbol_type *) NULL                    \
 358         && coffsym->native->u.syment.n_scnum == 0)              \
 359       cache_ptr->addend = - coffsym->native->u.syment.n_value;  \
 360     else if (ptr && bfd_asymbol_bfd (ptr) == abfd               \
 361              && ptr->section != (asection *) NULL)              \
 362       cache_ptr->addend = - (ptr->section->vma + ptr->value);   \
 363     else                                                        \
 364       cache_ptr->addend = 0;                                    \
 365     if (ptr && (reloc.r_type == R_PCRBYTE                       \
 366                 || reloc.r_type == R_PCRWORD                    \
 367                 || reloc.r_type == R_PCRLONG))                  \
 368       cache_ptr->addend += asect->vma;                          \
 369   }
 370
 371 #ifndef coff_rtype_to_howto
 372
 373 /* coff-m68k.c uses the special COFF backend linker.  We need to
 374    adjust common symbols.  */
 375
 376 static reloc_howto_type *
 377 m68kcoff_common_addend_rtype_to_howto (abfd, sec, rel, h, sym, addendp)
 378      bfd *abfd ATTRIBUTE_UNUSED;
 379      asection *sec;
 380      struct internal_reloc *rel;
 381      struct coff_link_hash_entry *h;
 382      struct internal_syment *sym;
 383      bfd_vma *addendp;
 384 {
 385   arelent relent;
 386   reloc_howto_type *howto;
 387
 388   RTYPE2HOWTO (&relent, rel);
 389
 390   howto = relent.howto;
 391
 392   if (howto->pc_relative)
 393     *addendp += sec->vma;
 394
 395   if (sym != NULL && sym->n_scnum == 0 && sym->n_value != 0)
 396     {
 397       /* This is a common symbol.  The section contents include the
 398          size (sym->n_value) as an addend.  The relocate_section
 399          function will be adding in the final value of the symbol.  We
 400          need to subtract out the current size in order to get the
 401          correct result.  */
 402       BFD_ASSERT (h != NULL);
 403       *addendp -= sym->n_value;
 404     }
 405
 406   /* If the output symbol is common (in which case this must be a
 407      relocateable link), we need to add in the final size of the
 408      common symbol.  */
 409   if (h != NULL && h->root.type == bfd_link_hash_common)
 410     *addendp += h->root.u.c.size;
 411
 412   return howto;
 413 }
 414
 415 #define coff_rtype_to_howto m68kcoff_common_addend_rtype_to_howto
 416
 417 #endif /* ! defined (coff_rtype_to_howto) */
 418
 419 #endif /* COFF_COMMON_ADDEND */
 420
 421 #if !defined ONLY_DECLARE_RELOCS && ! defined STATIC_RELOCS
 422 /* Given a .data section and a .emreloc in-memory section, store
 423    relocation information into the .emreloc section which can be
 424    used at runtime to relocate the section.  This is called by the
 425    linker when the --embedded-relocs switch is used.  This is called
 426    after the add_symbols entry point has been called for all the
 427    objects, and before the final_link entry point is called.  */
 428
 429 boolean
 430 bfd_m68k_coff_create_embedded_relocs (abfd, info, datasec, relsec, errmsg)
 431      bfd *abfd;
 432      struct bfd_link_info *info;
 433      asection *datasec;
 434      asection *relsec;
 435      char **errmsg;
 436 {
 437   char *extsyms;
 438   bfd_size_type symesz;
 439   struct internal_reloc *irel, *irelend;
 440   bfd_byte *p;
 441
 442   BFD_ASSERT (! info->relocateable);
 443
 444   *errmsg = NULL;
 445
 446   if (datasec->reloc_count == 0)
 447     return true;
 448
 449   extsyms = obj_coff_external_syms (abfd);
 450   symesz = bfd_coff_symesz (abfd);
 451
 452   irel = _bfd_coff_read_internal_relocs (abfd, datasec, true, NULL, false,
 453                                          NULL);
 454   irelend = irel + datasec->reloc_count;
 455
 456   relsec->contents = (bfd_byte *) bfd_alloc (abfd, datasec->reloc_count * 12);
 457   if (relsec->contents == NULL)
 458     return false;
 459
 460   p = relsec->contents;
 461
 462   for (; irel < irelend; irel++, p += 12)
 463     {
 464       asection *targetsec;
 465
 466       /* We are going to write a four byte longword into the runtime
 467        reloc section.  The longword will be the address in the data
 468        section which must be relocated.  It is followed by the name
 469        of the target section NUL-padded or truncated to 8
 470        characters.  */
 471
 472       /* We can only relocate absolute longword relocs at run time.  */
 473       if (irel->r_type != R_RELLONG)
 474         {
 475           *errmsg = _("unsupported reloc type");
 476           bfd_set_error (bfd_error_bad_value);
 477           return false;
 478         }
 479
 480       if (irel->r_symndx == -1)
 481         targetsec = bfd_abs_section_ptr;
 482       else
 483         {
 484           struct coff_link_hash_entry *h;
 485
 486           h = obj_coff_sym_hashes (abfd)[irel->r_symndx];
 487           if (h == NULL)
 488             {
 489               struct internal_syment isym;
 490
 491               bfd_coff_swap_sym_in (abfd, extsyms + symesz * irel->r_symndx,
 492                                     &isym);
 493               targetsec = coff_section_from_bfd_index (abfd, isym.n_scnum);
 494             }
 495           else if (h->root.type == bfd_link_hash_defined
 496                    || h->root.type == bfd_link_hash_defweak)
 497             targetsec = h->root.u.def.section;
 498           else
 499             targetsec = NULL;
 500         }
 501
 502       bfd_put_32 (abfd,
 503                   (irel->r_vaddr - datasec->vma + datasec->output_offset), p);
 504       memset (p + 4, 0, 8);
 505       if (targetsec != NULL)
 506         strncpy (p + 4, targetsec->output_section->name, 8);
 507     }
 508
 509   return true;
 510 }
 511 #endif /* neither ONLY_DECLARE_RELOCS not STATIC_RELOCS  */
 512 \f
 513 #define coff_bfd_is_local_label_name m68k_coff_is_local_label_name
 514
 515 #define coff_relocate_section _bfd_coff_generic_relocate_section
 516
 517 #include "coffcode.h"
 518
 519 #ifndef TARGET_SYM
 520 #define TARGET_SYM m68kcoff_vec
 521 #endif
 522
 523 #ifndef TARGET_NAME
 524 #define TARGET_NAME "coff-m68k"
 525 #endif
 526
 527 #ifdef NAMES_HAVE_UNDERSCORE
 528 CREATE_BIG_COFF_TARGET_VEC (TARGET_SYM, TARGET_NAME, D_PAGED, 0, '_', NULL)
 529 #else
 530 CREATE_BIG_COFF_TARGET_VEC (TARGET_SYM, TARGET_NAME, D_PAGED, 0, 0, NULL)
 531 #endif