bfd/coff-i386.c

   1 /* BFD back-end for Intel 386 COFF files.
   2    Copyright 1990, 1991, 1992, 1993, 1994 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 #include "bfd.h"
  22 #include "sysdep.h"
  23 #include "libbfd.h"
  24 #include "obstack.h"
  25 #include "coff/i386.h"
  26 #include "coff/internal.h"
  27 #include "libcoff.h"
  28
  29 static bfd_reloc_status_type coff_i386_reloc PARAMS ((bfd *abfd,
  30                                                       arelent *reloc_entry,
  31                                                       asymbol *symbol,
  32                                                       PTR data,
  33                                                       asection *input_section,
  34                                                       bfd *output_bfd,
  35                                                       char **error_message));
  36
  37 /* For some reason when using i386 COFF the value stored in the .text
  38    section for a reference to a common symbol is the value itself plus
  39    any desired offset.  Ian Taylor, Cygnus Support.  */
  40
  41 /* If we are producing relocateable output, we need to do some
  42    adjustments to the object file that are not done by the
  43    bfd_perform_relocation function.  This function is called by every
  44    reloc type to make any required adjustments.  */
  45
  46 static bfd_reloc_status_type
  47 coff_i386_reloc (abfd, reloc_entry, symbol, data, input_section, output_bfd,
  48                  error_message)
  49      bfd *abfd;
  50      arelent *reloc_entry;
  51      asymbol *symbol;
  52      PTR data;
  53      asection *input_section;
  54      bfd *output_bfd;
  55      char **error_message;
  56 {
  57   symvalue diff;
  58
  59   if (output_bfd == (bfd *) NULL)
  60     return bfd_reloc_continue;
  61
  62   if (bfd_is_com_section (symbol->section))
  63     {
  64       /* We are relocating a common symbol.  The current value in the
  65          object file is ORIG + OFFSET, where ORIG is the value of the
  66          common symbol as seen by the object file when it was compiled
  67          (this may be zero if the symbol was undefined) and OFFSET is
  68          the offset into the common symbol (normally zero, but may be
  69          non-zero when referring to a field in a common structure).
  70          ORIG is the negative of reloc_entry->addend, which is set by
  71          the CALC_ADDEND macro below.  We want to replace the value in
  72          the object file with NEW + OFFSET, where NEW is the value of
  73          the common symbol which we are going to put in the final
  74          object file.  NEW is symbol->value.  */
  75       diff = symbol->value + reloc_entry->addend;
  76     }
  77   else
  78     {
  79       /* For some reason bfd_perform_relocation always effectively
  80          ignores the addend for a COFF target when producing
  81          relocateable output.  This seems to be always wrong for 386
  82          COFF, so we handle the addend here instead.  */
  83       diff = reloc_entry->addend;
  84     }
  85
  86 #define DOIT(x) \
  87   x = ((x & ~howto->dst_mask) | (((x & howto->src_mask) + diff) & howto->dst_mask))
  88
  89   if (diff != 0)
  90     {
  91       const reloc_howto_type *howto = reloc_entry->howto;
  92       unsigned char *addr = (unsigned char *) data + reloc_entry->address;
  93
  94       switch (howto->size)
  95         {
  96         case 0:
  97           {
  98             char x = bfd_get_8 (abfd, addr);
  99             DOIT (x);
 100             bfd_put_8 (abfd, x, addr);
 101           }
 102           break;
 103
 104         case 1:
 105           {
 106             short x = bfd_get_16 (abfd, addr);
 107             DOIT (x);
 108             bfd_put_16 (abfd, x, addr);
 109           }
 110           break;
 111
 112         case 2:
 113           {
 114             long x = bfd_get_32 (abfd, addr);
 115             DOIT (x);
 116             bfd_put_32 (abfd, x, addr);
 117           }
 118           break;
 119
 120         default:
 121           abort ();
 122         }
 123     }
 124
 125   /* Now let bfd_perform_relocation finish everything up.  */
 126   return bfd_reloc_continue;
 127 }
 128
 129 static reloc_howto_type howto_table[] =
 130 {
 131   {0},
 132   {1},
 133   {2},
 134   {3},
 135   {4},
 136   {5},
 137   HOWTO (R_DIR32,               /* type */
 138          0,                     /* rightshift */
 139          2,                     /* size (0 = byte, 1 = short, 2 = long) */
 140          32,                    /* bitsize */
 141          false,                 /* pc_relative */
 142          0,                     /* bitpos */
 143          complain_overflow_bitfield, /* complain_on_overflow */
 144          coff_i386_reloc,       /* special_function */
 145          "dir32",               /* name */
 146          true,                  /* partial_inplace */
 147          0xffffffff,            /* src_mask */
 148          0xffffffff,            /* dst_mask */
 149          false),                /* pcrel_offset */
 150   {7},
 151   {010},
 152   {011},
 153   {012},
 154   {013},
 155   {014},
 156   {015},
 157   {016},
 158   HOWTO (R_RELBYTE,             /* type */
 159          0,                     /* rightshift */
 160          0,                     /* size (0 = byte, 1 = short, 2 = long) */
 161          8,                     /* bitsize */
 162          false,                 /* pc_relative */
 163          0,                     /* bitpos */
 164          complain_overflow_bitfield, /* complain_on_overflow */
 165          coff_i386_reloc,       /* special_function */
 166          "8",                   /* name */
 167          true,                  /* partial_inplace */
 168          0x000000ff,            /* src_mask */
 169          0x000000ff,            /* dst_mask */
 170          false),                /* pcrel_offset */
 171   HOWTO (R_RELWORD,             /* type */
 172          0,                     /* rightshift */
 173          1,                     /* size (0 = byte, 1 = short, 2 = long) */
 174          16,                    /* bitsize */
 175          false,                 /* pc_relative */
 176          0,                     /* bitpos */
 177          complain_overflow_bitfield, /* complain_on_overflow */
 178          coff_i386_reloc,       /* special_function */
 179          "16",                  /* name */
 180          true,                  /* partial_inplace */
 181          0x0000ffff,            /* src_mask */
 182          0x0000ffff,            /* dst_mask */
 183          false),                /* pcrel_offset */
 184   HOWTO (R_RELLONG,             /* type */
 185          0,                     /* rightshift */
 186          2,                     /* size (0 = byte, 1 = short, 2 = long) */
 187          32,                    /* bitsize */
 188          false,                 /* pc_relative */
 189          0,                     /* bitpos */
 190          complain_overflow_bitfield, /* complain_on_overflow */
 191          coff_i386_reloc,       /* special_function */
 192          "32",                  /* name */
 193          true,                  /* partial_inplace */
 194          0xffffffff,            /* src_mask */
 195          0xffffffff,            /* dst_mask */
 196          false),                /* pcrel_offset */
 197   HOWTO (R_PCRBYTE,             /* type */
 198          0,                     /* rightshift */
 199          0,                     /* size (0 = byte, 1 = short, 2 = long) */
 200          8,                     /* bitsize */
 201          true,                  /* pc_relative */
 202          0,                     /* bitpos */
 203          complain_overflow_signed, /* complain_on_overflow */
 204          coff_i386_reloc,       /* special_function */
 205          "DISP8",               /* name */
 206          true,                  /* partial_inplace */
 207          0x000000ff,            /* src_mask */
 208          0x000000ff,            /* dst_mask */
 209          false),                /* pcrel_offset */
 210   HOWTO (R_PCRWORD,             /* type */
 211          0,                     /* rightshift */
 212          1,                     /* size (0 = byte, 1 = short, 2 = long) */
 213          16,                    /* bitsize */
 214          true,                  /* pc_relative */
 215          0,                     /* bitpos */
 216          complain_overflow_signed, /* complain_on_overflow */
 217          coff_i386_reloc,       /* special_function */
 218          "DISP16",              /* name */
 219          true,                  /* partial_inplace */
 220          0x0000ffff,            /* src_mask */
 221          0x0000ffff,            /* dst_mask */
 222          false),                /* pcrel_offset */
 223   HOWTO (R_PCRLONG,             /* type */
 224          0,                     /* rightshift */
 225          2,                     /* size (0 = byte, 1 = short, 2 = long) */
 226          32,                    /* bitsize */
 227          true,                  /* pc_relative */
 228          0,                     /* bitpos */
 229          complain_overflow_signed, /* complain_on_overflow */
 230          coff_i386_reloc,       /* special_function */
 231          "DISP32",              /* name */
 232          true,                  /* partial_inplace */
 233          0xffffffff,            /* src_mask */
 234          0xffffffff,            /* dst_mask */
 235          false)                 /* pcrel_offset */
 236 };
 237
 238 /* Turn a howto into a reloc  nunmber */
 239
 240 #define SELECT_RELOC(x,howto) { x.r_type = howto->type; }
 241 #define BADMAG(x) I386BADMAG(x)
 242 #define I386 1                  /* Customize coffcode.h */
 243
 244 #define RTYPE2HOWTO(cache_ptr, dst) \
 245             cache_ptr->howto = howto_table + (dst)->r_type;
 246
 247 /* On SCO Unix 3.2.2 the native assembler generates two .data
 248    sections.  We handle that by renaming the second one to .data2.  It
 249    does no harm to do this for any 386 COFF target.  */
 250 #define TWO_DATA_SECS
 251
 252 /* For 386 COFF a STYP_NOLOAD | STYP_BSS section is part of a shared
 253    library.  On some other COFF targets STYP_BSS is normally
 254    STYP_NOLOAD.  */
 255 #define BSS_NOLOAD_IS_SHARED_LIBRARY
 256
 257 /* Compute the addend of a reloc.  If the reloc is to a common symbol,
 258    the object file contains the value of the common symbol.  By the
 259    time this is called, the linker may be using a different symbol
 260    from a different object file with a different value.  Therefore, we
 261    hack wildly to locate the original symbol from this file so that we
 262    can make the correct adjustment.  This macro sets coffsym to the
 263    symbol from the original file, and uses it to set the addend value
 264    correctly.  If this is not a common symbol, the usual addend
 265    calculation is done, except that an additional tweak is needed for
 266    PC relative relocs.
 267    FIXME: This macro refers to symbols and asect; these are from the
 268    calling function, not the macro arguments.  */
 269
 270 #define CALC_ADDEND(abfd, ptr, reloc, cache_ptr)                \
 271   {                                                             \
 272     coff_symbol_type *coffsym = (coff_symbol_type *) NULL;      \
 273     if (ptr && bfd_asymbol_bfd (ptr) != abfd)                   \
 274       coffsym = (obj_symbols (abfd)                             \
 275                  + (cache_ptr->sym_ptr_ptr - symbols));         \
 276     else if (ptr)                                               \
 277       coffsym = coff_symbol_from (abfd, ptr);                   \
 278     if (coffsym != (coff_symbol_type *) NULL                    \
 279         && coffsym->native->u.syment.n_scnum == 0)              \
 280       cache_ptr->addend = - coffsym->native->u.syment.n_value;  \
 281     else if (ptr && bfd_asymbol_bfd (ptr) == abfd               \
 282              && ptr->section != (asection *) NULL)              \
 283       cache_ptr->addend = - (ptr->section->vma + ptr->value);   \
 284     else                                                        \
 285       cache_ptr->addend = 0;                                    \
 286     if (ptr && howto_table[reloc.r_type].pc_relative)           \
 287       cache_ptr->addend += asect->vma;                          \
 288   }
 289
 290 #include "coffcode.h"
 291
 292 static bfd_target *
 293 i3coff_object_p(a)
 294      bfd *a;
 295 {
 296   return coff_object_p(a);
 297 }
 298
 299 bfd_target
 300 #ifdef TARGET_SYM
 301   TARGET_SYM =
 302 #else
 303   i386coff_vec =
 304 #endif
 305 {
 306 #ifdef TARGET_NAME
 307   TARGET_NAME,
 308 #else
 309   "coff-i386",                  /* name */
 310 #endif
 311   bfd_target_coff_flavour,
 312   false,                        /* data byte order is little */
 313   false,                        /* header byte order is little */
 314
 315   (HAS_RELOC | EXEC_P |         /* object flags */
 316    HAS_LINENO | HAS_DEBUG |
 317    HAS_SYMS | HAS_LOCALS | WP_TEXT),
 318
 319   (SEC_HAS_CONTENTS | SEC_ALLOC | SEC_LOAD | SEC_RELOC), /* section flags */
 320   0,                            /* leading underscore */
 321   '/',                          /* ar_pad_char */
 322   15,                           /* ar_max_namelen */
 323
 324   2,                            /* minimum alignment power */
 325   bfd_getl64, bfd_getl_signed_64, bfd_putl64,
 326      bfd_getl32, bfd_getl_signed_32, bfd_putl32,
 327      bfd_getl16, bfd_getl_signed_16, bfd_putl16, /* data */
 328   bfd_getl64, bfd_getl_signed_64, bfd_putl64,
 329      bfd_getl32, bfd_getl_signed_32, bfd_putl32,
 330      bfd_getl16, bfd_getl_signed_16, bfd_putl16, /* hdrs */
 331
 332 /* Note that we allow an object file to be treated as a core file as well. */
 333     {_bfd_dummy_target, i3coff_object_p, /* bfd_check_format */
 334        bfd_generic_archive_p, i3coff_object_p},
 335     {bfd_false, coff_mkobject, _bfd_generic_mkarchive, /* bfd_set_format */
 336        bfd_false},
 337     {bfd_false, coff_write_object_contents, /* bfd_write_contents */
 338        _bfd_write_archive_contents, bfd_false},
 339
 340      BFD_JUMP_TABLE_GENERIC (coff),
 341      BFD_JUMP_TABLE_COPY (coff),
 342      BFD_JUMP_TABLE_CORE (_bfd_nocore),
 343      BFD_JUMP_TABLE_ARCHIVE (_bfd_archive_coff),
 344      BFD_JUMP_TABLE_SYMBOLS (coff),
 345      BFD_JUMP_TABLE_RELOCS (coff),
 346      BFD_JUMP_TABLE_WRITE (coff),
 347      BFD_JUMP_TABLE_LINK (coff),
 348
 349   COFF_SWAP_TABLE,
 350 };