bfd/coff-i386.c

   1 /* BFD back-end for Intel 386 COFF files.
   2    Copyright 1990, 1991, 1992, 1993, 1994, 1995 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., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
  20
  21 #include "bfd.h"
  22 #include "sysdep.h"
  23 #include "libbfd.h"
  24 #include "obstack.h"
  25
  26 #include "coff/i386.h"
  27
  28 #include "coff/internal.h"
  29
  30 #ifdef COFF_WITH_PE
  31 #include "coff/pe.h"
  32 #endif
  33
  34 #include "libcoff.h"
  35
  36 static bfd_reloc_status_type coff_i386_reloc
  37   PARAMS ((bfd *, arelent *, asymbol *, PTR, asection *, bfd *, char **));
  38 static reloc_howto_type *coff_i386_rtype_to_howto
  39   PARAMS ((bfd *, asection *, struct internal_reloc *,
  40            struct coff_link_hash_entry *, struct internal_syment *,
  41
  42            bfd_vma *));
  43
  44 #define COFF_DEFAULT_SECTION_ALIGNMENT_POWER (2)
  45 /* The page size is a guess based on ELF.  */
  46
  47 #define COFF_PAGE_SIZE 0x1000
  48
  49 /* For some reason when using i386 COFF the value stored in the .text
  50    section for a reference to a common symbol is the value itself plus
  51    any desired offset.  Ian Taylor, Cygnus Support.  */
  52
  53 /* If we are producing relocateable output, we need to do some
  54    adjustments to the object file that are not done by the
  55    bfd_perform_relocation function.  This function is called by every
  56    reloc type to make any required adjustments.  */
  57
  58 static bfd_reloc_status_type
  59 coff_i386_reloc (abfd, reloc_entry, symbol, data, input_section, output_bfd,
  60                  error_message)
  61      bfd *abfd;
  62      arelent *reloc_entry;
  63      asymbol *symbol;
  64      PTR data;
  65      asection *input_section;
  66      bfd *output_bfd;
  67      char **error_message;
  68 {
  69   symvalue diff;
  70
  71   if (output_bfd == (bfd *) NULL)
  72     return bfd_reloc_continue;
  73
  74
  75   if (bfd_is_com_section (symbol->section))
  76     {
  77       /* We are relocating a common symbol.  The current value in the
  78          object file is ORIG + OFFSET, where ORIG is the value of the
  79          common symbol as seen by the object file when it was compiled
  80          (this may be zero if the symbol was undefined) and OFFSET is
  81          the offset into the common symbol (normally zero, but may be
  82          non-zero when referring to a field in a common structure).
  83          ORIG is the negative of reloc_entry->addend, which is set by
  84          the CALC_ADDEND macro below.  We want to replace the value in
  85          the object file with NEW + OFFSET, where NEW is the value of
  86          the common symbol which we are going to put in the final
  87          object file.  NEW is symbol->value.  */
  88       diff = symbol->value + reloc_entry->addend;
  89     }
  90   else
  91     {
  92       /* For some reason bfd_perform_relocation always effectively
  93          ignores the addend for a COFF target when producing
  94          relocateable output.  This seems to be always wrong for 386
  95          COFF, so we handle the addend here instead.  */
  96       diff = reloc_entry->addend;
  97     }
  98
  99
 100 #ifdef COFF_WITH_PE
 101   if (reloc_entry->howto->type == 7)
 102     {
 103 /*      diff -= coff_data(output_bfd)->link_info->pe_info.image_base.value;*/
 104       exit(1);
 105     }
 106 #endif
 107
 108 #define DOIT(x) \
 109   x = ((x & ~howto->dst_mask) | (((x & howto->src_mask) + diff) & howto->dst_mask))
 110
 111     if (diff != 0)
 112       {
 113         reloc_howto_type *howto = reloc_entry->howto;
 114         unsigned char *addr = (unsigned char *) data + reloc_entry->address;
 115
 116         switch (howto->size)
 117           {
 118           case 0:
 119             {
 120               char x = bfd_get_8 (abfd, addr);
 121               DOIT (x);
 122               bfd_put_8 (abfd, x, addr);
 123             }
 124             break;
 125
 126           case 1:
 127             {
 128               short x = bfd_get_16 (abfd, addr);
 129               DOIT (x);
 130               bfd_put_16 (abfd, x, addr);
 131             }
 132             break;
 133
 134           case 2:
 135             {
 136               long x = bfd_get_32 (abfd, addr);
 137               DOIT (x);
 138               bfd_put_32 (abfd, x, addr);
 139             }
 140             break;
 141
 142           default:
 143             abort ();
 144           }
 145       }
 146
 147   /* Now let bfd_perform_relocation finish everything up.  */
 148   return bfd_reloc_continue;
 149 }
 150
 151
 152
 153 #ifndef PCRELOFFSET
 154 #define PCRELOFFSET false
 155 #endif
 156
 157 static reloc_howto_type howto_table[] =
 158 {
 159   {0},
 160   {1},
 161   {2},
 162   {3},
 163   {4},
 164   {5},
 165   HOWTO (R_DIR32,               /* type */
 166          0,                     /* rightshift */
 167          2,                     /* size (0 = byte, 1 = short, 2 = long) */
 168          32,                    /* bitsize */
 169          false,                 /* pc_relative */
 170          0,                     /* bitpos */
 171          complain_overflow_bitfield, /* complain_on_overflow */
 172          coff_i386_reloc,       /* special_function */
 173          "dir32",               /* name */
 174          true,                  /* partial_inplace */
 175          0xffffffff,            /* src_mask */
 176          0xffffffff,            /* dst_mask */
 177          true),                /* pcrel_offset */
 178   /* {7}, */
 179   HOWTO (R_IMAGEBASE,            /* type */
 180          0,                     /* rightshift */
 181          2,                     /* size (0 = byte, 1 = short, 2 = long) */
 182          32,                    /* bitsize */
 183          false,                 /* pc_relative */
 184          0,                     /* bitpos */
 185          complain_overflow_bitfield, /* complain_on_overflow */
 186          coff_i386_reloc,       /* special_function */
 187          "rva32",                  /* name */
 188          true,                  /* partial_inplace */
 189          0xffffffff,            /* src_mask */
 190          0xffffffff,            /* dst_mask */
 191          false),                /* pcrel_offset */
 192   {010},
 193   {011},
 194   {012},
 195   {013},
 196   {014},
 197   {015},
 198   {016},
 199   HOWTO (R_RELBYTE,             /* type */
 200          0,                     /* rightshift */
 201          0,                     /* size (0 = byte, 1 = short, 2 = long) */
 202          8,                     /* bitsize */
 203          false,                 /* pc_relative */
 204          0,                     /* bitpos */
 205          complain_overflow_bitfield, /* complain_on_overflow */
 206          coff_i386_reloc,       /* special_function */
 207          "8",                   /* name */
 208          true,                  /* partial_inplace */
 209          0x000000ff,            /* src_mask */
 210          0x000000ff,            /* dst_mask */
 211          PCRELOFFSET),          /* pcrel_offset */
 212   HOWTO (R_RELWORD,             /* type */
 213          0,                     /* rightshift */
 214          1,                     /* size (0 = byte, 1 = short, 2 = long) */
 215          16,                    /* bitsize */
 216          false,                 /* pc_relative */
 217          0,                     /* bitpos */
 218          complain_overflow_bitfield, /* complain_on_overflow */
 219          coff_i386_reloc,       /* special_function */
 220          "16",                  /* name */
 221          true,                  /* partial_inplace */
 222          0x0000ffff,            /* src_mask */
 223          0x0000ffff,            /* dst_mask */
 224          PCRELOFFSET),          /* pcrel_offset */
 225   HOWTO (R_RELLONG,             /* type */
 226          0,                     /* rightshift */
 227          2,                     /* size (0 = byte, 1 = short, 2 = long) */
 228          32,                    /* bitsize */
 229          false,                 /* pc_relative */
 230          0,                     /* bitpos */
 231          complain_overflow_bitfield, /* complain_on_overflow */
 232          coff_i386_reloc,       /* special_function */
 233          "32",                  /* name */
 234          true,                  /* partial_inplace */
 235          0xffffffff,            /* src_mask */
 236          0xffffffff,            /* dst_mask */
 237          PCRELOFFSET),          /* pcrel_offset */
 238   HOWTO (R_PCRBYTE,             /* type */
 239          0,                     /* rightshift */
 240          0,                     /* size (0 = byte, 1 = short, 2 = long) */
 241          8,                     /* bitsize */
 242          true,                  /* pc_relative */
 243          0,                     /* bitpos */
 244          complain_overflow_signed, /* complain_on_overflow */
 245          coff_i386_reloc,       /* special_function */
 246          "DISP8",               /* name */
 247          true,                  /* partial_inplace */
 248          0x000000ff,            /* src_mask */
 249          0x000000ff,            /* dst_mask */
 250          PCRELOFFSET),          /* pcrel_offset */
 251   HOWTO (R_PCRWORD,             /* type */
 252          0,                     /* rightshift */
 253          1,                     /* size (0 = byte, 1 = short, 2 = long) */
 254          16,                    /* bitsize */
 255          true,                  /* pc_relative */
 256          0,                     /* bitpos */
 257          complain_overflow_signed, /* complain_on_overflow */
 258          coff_i386_reloc,       /* special_function */
 259          "DISP16",              /* name */
 260          true,                  /* partial_inplace */
 261          0x0000ffff,            /* src_mask */
 262          0x0000ffff,            /* dst_mask */
 263          PCRELOFFSET),          /* pcrel_offset */
 264   HOWTO (R_PCRLONG,             /* type */
 265          0,                     /* rightshift */
 266          2,                     /* size (0 = byte, 1 = short, 2 = long) */
 267          32,                    /* bitsize */
 268          true,                  /* pc_relative */
 269          0,                     /* bitpos */
 270          complain_overflow_signed, /* complain_on_overflow */
 271          coff_i386_reloc,       /* special_function */
 272          "DISP32",              /* name */
 273          true,                  /* partial_inplace */
 274          0xffffffff,            /* src_mask */
 275          0xffffffff,            /* dst_mask */
 276          PCRELOFFSET)           /* pcrel_offset */
 277 };
 278
 279 /* Turn a howto into a reloc  nunmber */
 280
 281 #define SELECT_RELOC(x,howto) { x.r_type = howto->type; }
 282 #define BADMAG(x) I386BADMAG(x)
 283 #define I386 1                  /* Customize coffcode.h */
 284
 285 #define RTYPE2HOWTO(cache_ptr, dst) \
 286             (cache_ptr)->howto = howto_table + (dst)->r_type;
 287
 288 /* On SCO Unix 3.2.2 the native assembler generates two .data
 289    sections.  We handle that by renaming the second one to .data2.  It
 290    does no harm to do this for any 386 COFF target.  */
 291 #define TWO_DATA_SECS
 292
 293 /* For 386 COFF a STYP_NOLOAD | STYP_BSS section is part of a shared
 294    library.  On some other COFF targets STYP_BSS is normally
 295    STYP_NOLOAD.  */
 296 #define BSS_NOLOAD_IS_SHARED_LIBRARY
 297
 298 /* Compute the addend of a reloc.  If the reloc is to a common symbol,
 299    the object file contains the value of the common symbol.  By the
 300    time this is called, the linker may be using a different symbol
 301    from a different object file with a different value.  Therefore, we
 302    hack wildly to locate the original symbol from this file so that we
 303    can make the correct adjustment.  This macro sets coffsym to the
 304    symbol from the original file, and uses it to set the addend value
 305    correctly.  If this is not a common symbol, the usual addend
 306    calculation is done, except that an additional tweak is needed for
 307    PC relative relocs.
 308    FIXME: This macro refers to symbols and asect; these are from the
 309    calling function, not the macro arguments.  */
 310
 311 #define CALC_ADDEND(abfd, ptr, reloc, cache_ptr)                \
 312   {                                                             \
 313     coff_symbol_type *coffsym = (coff_symbol_type *) NULL;      \
 314     if (ptr && bfd_asymbol_bfd (ptr) != abfd)                   \
 315       coffsym = (obj_symbols (abfd)                             \
 316                  + (cache_ptr->sym_ptr_ptr - symbols));         \
 317     else if (ptr)                                               \
 318       coffsym = coff_symbol_from (abfd, ptr);                   \
 319     if (coffsym != (coff_symbol_type *) NULL                    \
 320         && coffsym->native->u.syment.n_scnum == 0)              \
 321       cache_ptr->addend = - coffsym->native->u.syment.n_value;  \
 322     else if (ptr && bfd_asymbol_bfd (ptr) == abfd               \
 323              && ptr->section != (asection *) NULL)              \
 324       cache_ptr->addend = - (ptr->section->vma + ptr->value);   \
 325     else                                                        \
 326       cache_ptr->addend = 0;                                    \
 327     if (ptr && howto_table[reloc.r_type].pc_relative)           \
 328       cache_ptr->addend += asect->vma;                          \
 329   }
 330
 331 /* We use the special COFF backend linker.  */
 332 #define coff_relocate_section _bfd_coff_generic_relocate_section
 333
 334 static reloc_howto_type *
 335 coff_i386_rtype_to_howto (abfd, sec, rel, h, sym, addendp)
 336      bfd *abfd;
 337      asection *sec;
 338      struct internal_reloc *rel;
 339      struct coff_link_hash_entry *h;
 340      struct internal_syment *sym;
 341      bfd_vma *addendp;
 342 {
 343
 344   reloc_howto_type *howto;
 345
 346   howto = howto_table + rel->r_type;
 347
 348 #ifdef COFF_WITH_PE
 349   *addendp = 0;
 350 #endif
 351
 352   if (howto->pc_relative)
 353     *addendp += sec->vma;
 354
 355   if (sym != NULL && sym->n_scnum == 0 && sym->n_value != 0)
 356     {
 357       /* This is a common symbol.  The section contents include the
 358          size (sym->n_value) as an addend.  The relocate_section
 359          function will be adding in the final value of the symbol.  We
 360          need to subtract out the current size in order to get the
 361          correct result.  */
 362
 363       BFD_ASSERT (h != NULL);
 364
 365
 366 #ifndef COFF_WITH_PE
 367       /* I think we *do* want to bypass this.  If we don't, I have seen some data
 368          parameters get the wrong relcation address.  If I link two versions
 369          with and without this section bypassed and then do a binary comparison,
 370          the addresses which are different can be looked up in the map.  The
 371          case in which this section has been bypassed has addresses which correspond
 372          to values I can find in the map */
 373       *addendp -= sym->n_value;
 374 #endif
 375     }
 376
 377   /* If the output symbol is common (in which case this must be a
 378      relocateable link), we need to add in the final size of the
 379      common symbol.  */
 380   if (h != NULL && h->root.type == bfd_link_hash_common)
 381     *addendp += h->root.u.c.size;
 382
 383
 384 #ifdef COFF_WITH_PE
 385   if (howto->pc_relative)
 386     *addendp -= 4;
 387
 388   if (rel->r_type == R_IMAGEBASE)
 389     {
 390       *addendp -= pe_data(sec->output_section->owner)->pe_opthdr.ImageBase;
 391     }
 392 #endif
 393
 394   return howto;
 395 }
 396
 397 #define coff_rtype_to_howto coff_i386_rtype_to_howto
 398
 399 #include "coffcode.h"
 400
 401 static const bfd_target *
 402 i3coff_object_p(a)
 403      bfd *a;
 404 {
 405   return coff_object_p(a);
 406 }
 407
 408 const bfd_target
 409 #ifdef TARGET_SYM
 410   TARGET_SYM =
 411 #else
 412   i386coff_vec =
 413 #endif
 414 {
 415 #ifdef TARGET_NAME
 416   TARGET_NAME,
 417 #else
 418   "coff-i386",                  /* name */
 419 #endif
 420   bfd_target_coff_flavour,
 421   false,                        /* data byte order is little */
 422   false,                        /* header byte order is little */
 423
 424   (HAS_RELOC | EXEC_P |         /* object flags */
 425    HAS_LINENO | HAS_DEBUG |
 426    HAS_SYMS | HAS_LOCALS | WP_TEXT | D_PAGED),
 427
 428   (SEC_HAS_CONTENTS | SEC_ALLOC | SEC_LOAD | SEC_RELOC), /* section flags */
 429 #ifdef TARGET_UNDERSCORE
 430   TARGET_UNDERSCORE,            /* leading underscore */
 431 #else
 432   0,                            /* leading underscore */
 433 #endif
 434   '/',                          /* ar_pad_char */
 435   15,                           /* ar_max_namelen */
 436
 437   bfd_getl64, bfd_getl_signed_64, bfd_putl64,
 438      bfd_getl32, bfd_getl_signed_32, bfd_putl32,
 439      bfd_getl16, bfd_getl_signed_16, bfd_putl16, /* data */
 440   bfd_getl64, bfd_getl_signed_64, bfd_putl64,
 441      bfd_getl32, bfd_getl_signed_32, bfd_putl32,
 442      bfd_getl16, bfd_getl_signed_16, bfd_putl16, /* hdrs */
 443
 444 /* Note that we allow an object file to be treated as a core file as well. */
 445     {_bfd_dummy_target, i3coff_object_p, /* bfd_check_format */
 446        bfd_generic_archive_p, i3coff_object_p},
 447     {bfd_false, coff_mkobject, _bfd_generic_mkarchive, /* bfd_set_format */
 448        bfd_false},
 449     {bfd_false, coff_write_object_contents, /* bfd_write_contents */
 450        _bfd_write_archive_contents, bfd_false},
 451
 452      BFD_JUMP_TABLE_GENERIC (coff),
 453      BFD_JUMP_TABLE_COPY (coff),
 454      BFD_JUMP_TABLE_CORE (_bfd_nocore),
 455      BFD_JUMP_TABLE_ARCHIVE (_bfd_archive_coff),
 456      BFD_JUMP_TABLE_SYMBOLS (coff),
 457      BFD_JUMP_TABLE_RELOCS (coff),
 458      BFD_JUMP_TABLE_WRITE (coff),
 459      BFD_JUMP_TABLE_LINK (coff),
 460      BFD_JUMP_TABLE_DYNAMIC (_bfd_nodynamic),
 461
 462   COFF_SWAP_TABLE,
 463 };