bfd/reloc16.c

   1 /* 8 and 16 bit COFF relocation functions, for BFD.
   2    Copyright 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1998, 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 /* Most of this hacked by Steve Chamberlain <sac@cygnus.com>.  */
  23
  24 /* These routines are used by coff-h8300 and coff-z8k to do
  25    relocation.
  26
  27    FIXME: This code should be rewritten to support the new COFF
  28    linker.  Basically, they need to deal with COFF relocs rather than
  29    BFD generic relocs.  They should store the relocs in some location
  30    where coff_link_input_bfd can find them (and coff_link_input_bfd
  31    should be changed to use this location rather than rereading the
  32    file) (unless info->keep_memory is false, in which case they should
  33    free up the relocs after dealing with them).  */
  34
  35 #include "bfd.h"
  36 #include "sysdep.h"
  37 #include "libbfd.h"
  38 #include "bfdlink.h"
  39 #include "genlink.h"
  40 #include "coff/internal.h"
  41 #include "libcoff.h"
  42
  43 bfd_vma
  44 bfd_coff_reloc16_get_value (reloc, link_info, input_section)
  45      arelent *reloc;
  46      struct bfd_link_info *link_info;
  47      asection *input_section;
  48 {
  49   bfd_vma value;
  50   asymbol *symbol = *(reloc->sym_ptr_ptr);
  51   /* A symbol holds a pointer to a section, and an offset from the
  52      base of the section.  To relocate, we find where the section will
  53      live in the output and add that in.  */
  54
  55   if (bfd_is_und_section (symbol->section)
  56       || bfd_is_com_section (symbol->section))
  57     {
  58       struct bfd_link_hash_entry *h;
  59
  60       /* The symbol is undefined in this BFD.  Look it up in the
  61          global linker hash table.  FIXME: This should be changed when
  62          we convert this stuff to use a specific final_link function
  63          and change the interface to bfd_relax_section to not require
  64          the generic symbols.  */
  65       h = bfd_wrapped_link_hash_lookup (input_section->owner, link_info,
  66                                         bfd_asymbol_name (symbol),
  67                                         false, false, true);
  68       if (h != (struct bfd_link_hash_entry *) NULL
  69           && (h->type == bfd_link_hash_defined
  70               || h->type == bfd_link_hash_defweak))
  71         value = (h->u.def.value
  72                  + h->u.def.section->output_section->vma
  73                  + h->u.def.section->output_offset);
  74       else if (h != (struct bfd_link_hash_entry *) NULL
  75                && h->type == bfd_link_hash_common)
  76         value = h->u.c.size;
  77       else
  78         {
  79           if (!((*link_info->callbacks->undefined_symbol)
  80                 (link_info, bfd_asymbol_name (symbol),
  81                  input_section->owner, input_section, reloc->address,
  82                  true)))
  83             abort ();
  84           value = 0;
  85         }
  86     }
  87   else
  88     {
  89       value = symbol->value
  90         + symbol->section->output_offset
  91         + symbol->section->output_section->vma;
  92     }
  93
  94   /* Add the value contained in the relocation.  */
  95   value += reloc->addend;
  96
  97   return value;
  98 }
  99
 100 void
 101 bfd_perform_slip (abfd, slip, input_section, value)
 102      bfd *abfd;
 103      unsigned int slip;
 104      asection *input_section;
 105      bfd_vma value;
 106 {
 107   asymbol **s;
 108
 109   s = _bfd_generic_link_get_symbols (abfd);
 110   BFD_ASSERT (s != (asymbol **) NULL);
 111
 112   /* Find all symbols past this point, and make them know
 113      what's happened.  */
 114   while (*s)
 115     {
 116       asymbol *p = *s;
 117       if (p->section == input_section)
 118         {
 119           /* This was pointing into this section, so mangle it.  */
 120           if (p->value > value)
 121             {
 122               p->value -= slip;
 123               if (p->udata.p != NULL)
 124                 {
 125                   struct generic_link_hash_entry *h;
 126
 127                   h = (struct generic_link_hash_entry *) p->udata.p;
 128                   BFD_ASSERT (h->root.type == bfd_link_hash_defined
 129                               || h->root.type == bfd_link_hash_defweak);
 130                   h->root.u.def.value -= slip;
 131                   BFD_ASSERT (h->root.u.def.value == p->value);
 132                 }
 133             }
 134         }
 135       s++;
 136     }
 137 }
 138
 139 boolean
 140 bfd_coff_reloc16_relax_section (abfd, i, link_info, again)
 141      bfd *abfd;
 142      asection *i;
 143      struct bfd_link_info *link_info;
 144      boolean *again;
 145 {
 146   /* Get enough memory to hold the stuff.  */
 147   bfd *input_bfd = i->owner;
 148   asection *input_section = i;
 149   int *shrinks;
 150   int shrink = 0;
 151   long reloc_size = bfd_get_reloc_upper_bound (input_bfd, input_section);
 152   arelent **reloc_vector = NULL;
 153   long reloc_count;
 154
 155   /* We only do global relaxation once.  It is not safe to do it multiple
 156      times (see discussion of the "shrinks" array below).  */
 157   *again = false;
 158
 159   if (reloc_size < 0)
 160     return false;
 161
 162   reloc_vector = (arelent **) bfd_malloc (reloc_size);
 163   if (!reloc_vector && reloc_size > 0)
 164     return false;
 165
 166   /* Get the relocs and think about them.  */
 167   reloc_count =
 168     bfd_canonicalize_reloc (input_bfd, input_section, reloc_vector,
 169                             _bfd_generic_link_get_symbols (input_bfd));
 170   if (reloc_count < 0)
 171     {
 172       free (reloc_vector);
 173       return false;
 174     }
 175
 176   /* The reloc16.c and related relaxing code is very simple, the price
 177      for that simplicity is we can only call this function once for
 178      each section.
 179
 180      So, to get the best results within that limitation, we do multiple
 181      relaxing passes over each section here.  That involves keeping track
 182      of the "shrink" at each reloc in the section.  This allows us to
 183      accurately determine the relative location of two relocs within
 184      this section.
 185
 186      In theory, if we kept the "shrinks" array for each section for the
 187      entire link, we could use the generic relaxing code in the linker
 188      and get better results, particularly for jsr->bsr and 24->16 bit
 189      memory reference relaxations.  */
 190
 191   if (reloc_count > 0)
 192     {
 193       int another_pass = 0;
 194
 195       /* Allocate and initialize the shrinks array for this section.
 196          The last element is used as an accumlator of shrinks.  */
 197       shrinks = (int *) bfd_malloc ((reloc_count + 1) * sizeof (int));
 198       memset (shrinks, 0, (reloc_count + 1) * sizeof (int));
 199
 200       /* Loop until nothing changes in this section.  */
 201       do {
 202         arelent **parent;
 203         unsigned int i;
 204         long j;
 205
 206         another_pass = 0;
 207
 208         for (i = 0, parent = reloc_vector; *parent; parent++, i++)
 209           {
 210             /* Let the target/machine dependent code examine each reloc
 211                in this section and attempt to shrink it.  */
 212             shrink = bfd_coff_reloc16_estimate (abfd, input_section, *parent,
 213                                                 shrinks[i], link_info);
 214
 215             /* If it shrunk, note it in the shrinks array and set up for
 216                another pass.  */
 217             if (shrink != shrinks[i])
 218               {
 219                 another_pass = 1;
 220                 for (j = i + 1; j <= reloc_count; j++)
 221                   shrinks[j] += shrink - shrinks[i];
 222               }
 223           }
 224       }
 225       while (another_pass);
 226
 227       shrink = shrinks[reloc_count];
 228       free ((char *) shrinks);
 229     }
 230
 231   input_section->_cooked_size -= shrink;
 232   free ((char *) reloc_vector);
 233   return true;
 234 }
 235
 236 bfd_byte *
 237 bfd_coff_reloc16_get_relocated_section_contents(in_abfd,
 238                                                 link_info,
 239                                                 link_order,
 240                                                 data,
 241                                                 relocateable,
 242                                                 symbols)
 243      bfd *in_abfd;
 244      struct bfd_link_info *link_info;
 245      struct bfd_link_order *link_order;
 246      bfd_byte *data;
 247      boolean relocateable;
 248      asymbol **symbols;
 249 {
 250   /* Get enough memory to hold the stuff.  */
 251   bfd *input_bfd = link_order->u.indirect.section->owner;
 252   asection *input_section = link_order->u.indirect.section;
 253   long reloc_size = bfd_get_reloc_upper_bound (input_bfd, input_section);
 254   arelent **reloc_vector;
 255   long reloc_count;
 256
 257   if (reloc_size < 0)
 258     return NULL;
 259
 260   /* If producing relocateable output, don't bother to relax.  */
 261   if (relocateable)
 262     return bfd_generic_get_relocated_section_contents (in_abfd, link_info,
 263                                                        link_order,
 264                                                        data, relocateable,
 265                                                        symbols);
 266
 267   /* Read in the section.  */
 268   if (!bfd_get_section_contents(input_bfd,
 269                                 input_section,
 270                                 data,
 271                                 0,
 272                                 input_section->_raw_size))
 273     return NULL;
 274
 275   reloc_vector = (arelent **) bfd_malloc ((size_t) reloc_size);
 276   if (!reloc_vector && reloc_size != 0)
 277     return NULL;
 278
 279   reloc_count = bfd_canonicalize_reloc (input_bfd,
 280                                         input_section,
 281                                         reloc_vector,
 282                                         symbols);
 283   if (reloc_count < 0)
 284     {
 285       free (reloc_vector);
 286       return NULL;
 287     }
 288
 289   if (reloc_count > 0)
 290     {
 291       arelent **parent = reloc_vector;
 292       arelent *reloc;
 293       unsigned int dst_address = 0;
 294       unsigned int src_address = 0;
 295       unsigned int run;
 296       unsigned int idx;
 297
 298       /* Find how long a run we can do.  */
 299       while (dst_address < link_order->size)
 300         {
 301           reloc = *parent;
 302           if (reloc)
 303             {
 304               /* Note that the relaxing didn't tie up the addresses in the
 305                  relocation, so we use the original address to work out the
 306                  run of non-relocated data.  */
 307               run = reloc->address - src_address;
 308               parent++;
 309             }
 310           else
 311             {
 312               run = link_order->size - dst_address;
 313             }
 314
 315           /* Copy the bytes.  */
 316           for (idx = 0; idx < run; idx++)
 317             data[dst_address++] = data[src_address++];
 318
 319           /* Now do the relocation.  */
 320           if (reloc)
 321             {
 322               bfd_coff_reloc16_extra_cases (input_bfd, link_info, link_order,
 323                                             reloc, data, &src_address,
 324                                             &dst_address);
 325             }
 326         }
 327     }
 328   free ((char *) reloc_vector);
 329   return data;
 330 }