bfd/cf-m68klynx.c

   1 /* BFD back-end for Motorola M68K COFF LynxOS files.
   2    Copyright 1993, 1994, 1995, 1996 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 #define TARGET_SYM      m68klynx_coff_vec
  22 #define TARGET_NAME     "coff-m68k-lynx"
  23
  24 #define LYNXOS
  25
  26 #define COFF_LONG_FILENAMES
  27
  28 #define _bfd_m68kcoff_howto_table _bfd_m68klynx_howto_table
  29 #define _bfd_m68kcoff_rtype2howto _bfd_m68klynx_rtype2howto
  30 #define _bfd_m68kcoff_howto2rtype _bfd_m68klynx_howto2rtype
  31 #define _bfd_m68kcoff_reloc_type_lookup _bfd_m68klynx_reloc_type_lookup
  32
  33 #define LYNX_SPECIAL_FN _bfd_m68klynx_special_fn
  34
  35 #include "bfd.h"
  36 #include "sysdep.h"
  37
  38 #ifdef ANSI_PROTOTYPES
  39 struct internal_reloc;
  40 struct coff_link_hash_entry;
  41 struct internal_syment;
  42 #endif
  43
  44 static bfd_reloc_status_type _bfd_m68klynx_special_fn
  45   PARAMS ((bfd *, arelent *, asymbol *, PTR, asection *, bfd *, char **));
  46 static reloc_howto_type *coff_m68k_lynx_rtype_to_howto
  47   PARAMS ((bfd *, asection *, struct internal_reloc *,
  48            struct coff_link_hash_entry *, struct internal_syment *,
  49            bfd_vma *));
  50
  51 /* For some reason when using m68k COFF the value stored in the .text
  52    section for a reference to a common symbol is the value itself plus
  53    any desired offset.  (taken from work done by Ian Taylor, Cygnus Support,
  54    for I386 COFF).  */
  55
  56 /* If we are producing relocateable output, we need to do some
  57    adjustments to the object file that are not done by the
  58    bfd_perform_relocation function.  This function is called by every
  59    reloc type to make any required adjustments.  */
  60
  61 static bfd_reloc_status_type
  62 _bfd_m68klynx_special_fn (abfd, reloc_entry, symbol, data, input_section,
  63                           output_bfd, error_message)
  64      bfd *abfd;
  65      arelent *reloc_entry;
  66      asymbol *symbol;
  67      PTR data;
  68      asection *input_section;
  69      bfd *output_bfd;
  70      char **error_message;
  71 {
  72   symvalue diff;
  73
  74   if (output_bfd == (bfd *) NULL)
  75     return bfd_reloc_continue;
  76
  77   if (bfd_is_com_section (symbol->section))
  78     {
  79       /* We are relocating a common symbol.  The current value in the
  80          object file is ORIG + OFFSET, where ORIG is the value of the
  81          common symbol as seen by the object file when it was compiled
  82          (this may be zero if the symbol was undefined) and OFFSET is
  83          the offset into the common symbol (normally zero, but may be
  84          non-zero when referring to a field in a common structure).
  85          ORIG is the negative of reloc_entry->addend, which is set by
  86          the CALC_ADDEND macro below.  We want to replace the value in
  87          the object file with NEW + OFFSET, where NEW is the value of
  88          the common symbol which we are going to put in the final
  89          object file.  NEW is symbol->value.  */
  90       diff = symbol->value + reloc_entry->addend;
  91     }
  92   else
  93     {
  94       /* For some reason bfd_perform_relocation always effectively
  95          ignores the addend for a COFF target when producing
  96          relocateable output.  This seems to be always wrong for 386
  97          COFF, so we handle the addend here instead.  */
  98       diff = reloc_entry->addend;
  99     }
 100
 101 #define DOIT(x) \
 102   x = ((x & ~howto->dst_mask) | (((x & howto->src_mask) + diff) & howto->dst_mask))
 103
 104   if (diff != 0)
 105     {
 106       reloc_howto_type *howto = reloc_entry->howto;
 107       unsigned char *addr = (unsigned char *) data + reloc_entry->address;
 108
 109       switch (howto->size)
 110         {
 111         case 0:
 112           {
 113             char x = bfd_get_8 (abfd, addr);
 114             DOIT (x);
 115             bfd_put_8 (abfd, x, addr);
 116           }
 117           break;
 118
 119         case 1:
 120           {
 121             short x = bfd_get_16 (abfd, addr);
 122             DOIT (x);
 123             bfd_put_16 (abfd, x, addr);
 124           }
 125           break;
 126
 127         case 2:
 128           {
 129             long x = bfd_get_32 (abfd, addr);
 130             DOIT (x);
 131             bfd_put_32 (abfd, x, addr);
 132           }
 133           break;
 134
 135         default:
 136           abort ();
 137         }
 138     }
 139
 140   /* Now let bfd_perform_relocation finish everything up.  */
 141   return bfd_reloc_continue;
 142 }
 143 /* Compute the addend of a reloc.  If the reloc is to a common symbol,
 144    the object file contains the value of the common symbol.  By the
 145    time this is called, the linker may be using a different symbol
 146    from a different object file with a different value.  Therefore, we
 147    hack wildly to locate the original symbol from this file so that we
 148    can make the correct adjustment.  This macro sets coffsym to the
 149    symbol from the original file, and uses it to set the addend value
 150    correctly.  If this is not a common symbol, the usual addend
 151    calculation is done, except that an additional tweak is needed for
 152    PC relative relocs.
 153    FIXME: This macro refers to symbols and asect; these are from the
 154    calling function, not the macro arguments.  */
 155
 156 #define CALC_ADDEND(abfd, ptr, reloc, cache_ptr)                \
 157   {                                                             \
 158     coff_symbol_type *coffsym = (coff_symbol_type *) NULL;      \
 159     if (ptr && bfd_asymbol_bfd (ptr) != abfd)                   \
 160       coffsym = (obj_symbols (abfd)                             \
 161                  + (cache_ptr->sym_ptr_ptr - symbols));         \
 162     else if (ptr)                                               \
 163       coffsym = coff_symbol_from (abfd, ptr);                   \
 164     if (coffsym != (coff_symbol_type *) NULL                    \
 165         && coffsym->native->u.syment.n_scnum == 0)              \
 166       cache_ptr->addend = - coffsym->native->u.syment.n_value;  \
 167     else if (ptr && bfd_asymbol_bfd (ptr) == abfd               \
 168              && ptr->section != (asection *) NULL)              \
 169       cache_ptr->addend = - (ptr->section->vma + ptr->value);   \
 170     else                                                        \
 171       cache_ptr->addend = 0;                                    \
 172     if (ptr && (reloc.r_type == R_PCRBYTE                       \
 173                 || reloc.r_type == R_PCRWORD                    \
 174                 || reloc.r_type == R_PCRLONG))                  \
 175       cache_ptr->addend += asect->vma;                          \
 176   }
 177
 178 #define coff_rtype_to_howto coff_m68k_lynx_rtype_to_howto
 179
 180 #include "coff-m68k.c"
 181
 182 /* coff-m68k.c uses the special COFF backend linker.  We need to
 183    adjust common symbols.
 184
 185    We can't define this function until after we have included
 186    coff-m68k.c, because it uses RTYPE2HOWTO.  */
 187
 188 /*ARGSUSED*/
 189 static reloc_howto_type *
 190 coff_m68k_lynx_rtype_to_howto (abfd, sec, rel, h, sym, addendp)
 191      bfd *abfd;
 192      asection *sec;
 193      struct internal_reloc *rel;
 194      struct coff_link_hash_entry *h;
 195      struct internal_syment *sym;
 196      bfd_vma *addendp;
 197 {
 198   arelent relent;
 199   reloc_howto_type *howto;
 200
 201   RTYPE2HOWTO (&relent, rel);
 202
 203   howto = relent.howto;
 204
 205   if (howto->pc_relative)
 206     *addendp += sec->vma;
 207
 208   if (sym != NULL && sym->n_scnum == 0 && sym->n_value != 0)
 209     {
 210       /* This is a common symbol.  The section contents include the
 211          size (sym->n_value) as an addend.  The relocate_section
 212          function will be adding in the final value of the symbol.  We
 213          need to subtract out the current size in order to get the
 214          correct result.  */
 215       BFD_ASSERT (h != NULL);
 216       *addendp -= sym->n_value;
 217     }
 218
 219   /* If the output symbol is common (in which case this must be a
 220      relocateable link), we need to add in the final size of the
 221      common symbol.  */
 222   if (h != NULL && h->root.type == bfd_link_hash_common)
 223     *addendp += h->root.u.c.size;
 224
 225   return howto;
 226 }