bfd/reloc16.c

   1 /* 8 and 16 bit COFF relocation functions, for BFD.
   2    Copyright 1990, 91, 92, 93, 94, 95, 96, 97, 1998
   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 /*
  23 Most of this hacked by  Steve Chamberlain,
  24                         sac@cygnus.com
  25 */
  26
  27 /* These routines are used by coff-h8300 and coff-z8k to do
  28    relocation.
  29
  30    FIXME: This code should be rewritten to support the new COFF
  31    linker.  Basically, they need to deal with COFF relocs rather than
  32    BFD generic relocs.  They should store the relocs in some location
  33    where coff_link_input_bfd can find them (and coff_link_input_bfd
  34    should be changed to use this location rather than rereading the
  35    file) (unless info->keep_memory is false, in which case they should
  36    free up the relocs after dealing with them).  */
  37
  38 #include "bfd.h"
  39 #include "sysdep.h"
  40 #include "libbfd.h"
  41 #include "bfdlink.h"
  42 #include "genlink.h"
  43 #include "coff/internal.h"
  44 #include "libcoff.h"
  45
  46 bfd_vma
  47 bfd_coff_reloc16_get_value (reloc, link_info, input_section)
  48      arelent *reloc;
  49      struct bfd_link_info *link_info;
  50      asection *input_section;
  51 {
  52   bfd_vma value;
  53   asymbol *symbol = *(reloc->sym_ptr_ptr);
  54   /* A symbol holds a pointer to a section, and an offset from the
  55      base of the section.  To relocate, we find where the section will
  56      live in the output and add that in */
  57
  58   if (bfd_is_und_section (symbol->section)
  59       || bfd_is_com_section (symbol->section))
  60     {
  61       struct bfd_link_hash_entry *h;
  62
  63       /* The symbol is undefined in this BFD.  Look it up in the
  64          global linker hash table.  FIXME: This should be changed when
  65          we convert this stuff to use a specific final_link function
  66          and change the interface to bfd_relax_section to not require
  67          the generic symbols.  */
  68       h = bfd_wrapped_link_hash_lookup (input_section->owner, link_info,
  69                                         bfd_asymbol_name (symbol),
  70                                         false, false, true);
  71       if (h != (struct bfd_link_hash_entry *) NULL
  72           && (h->type == bfd_link_hash_defined
  73               || h->type == bfd_link_hash_defweak))
  74         value = (h->u.def.value
  75                  + h->u.def.section->output_section->vma
  76                  + h->u.def.section->output_offset);
  77       else if (h != (struct bfd_link_hash_entry *) NULL
  78                && h->type == bfd_link_hash_common)
  79         value = h->u.c.size;
  80       else
  81         {
  82           if (! ((*link_info->callbacks->undefined_symbol)
  83                  (link_info, bfd_asymbol_name (symbol),
  84                   input_section->owner, input_section, reloc->address)))
  85             abort ();
  86           value = 0;
  87         }
  88     }
  89   else
  90     {
  91       value = symbol->value +
  92         symbol->section->output_offset +
  93           symbol->section->output_section->vma;
  94     }
  95
  96   /* Add the value contained in the relocation */
  97   value += reloc->addend;
  98
  99   return value;
 100 }
 101
 102 void
 103 bfd_perform_slip(abfd, slip, input_section, value)
 104      bfd *abfd;
 105      unsigned int slip;
 106      asection *input_section;
 107      bfd_vma value;
 108 {
 109   asymbol **s;
 110
 111   s = _bfd_generic_link_get_symbols (abfd);
 112   BFD_ASSERT (s != (asymbol **) NULL);
 113
 114   /* Find all symbols past this point, and make them know
 115      what's happened */
 116   while (*s)
 117     {
 118       asymbol *p = *s;
 119       if (p->section == input_section)
 120         {
 121           /* This was pointing into this section, so mangle it */
 122           if (p->value > value)
 123             {
 124               p->value -= slip;
 125               if (p->udata.p != NULL)
 126                 {
 127                   struct generic_link_hash_entry *h;
 128
 129                   h = (struct generic_link_hash_entry *) p->udata.p;
 130                   BFD_ASSERT (h->root.type == bfd_link_hash_defined
 131                               || h->root.type == bfd_link_hash_defweak);
 132                   h->root.u.def.value -= slip;
 133                   BFD_ASSERT (h->root.u.def.value == p->value);
 134                 }
 135             }
 136         }
 137       s++;
 138     }
 139 }
 140
 141 boolean
 142 bfd_coff_reloc16_relax_section (abfd, i, link_info, again)
 143      bfd *abfd;
 144      asection *i;
 145      struct bfd_link_info *link_info;
 146      boolean *again;
 147 {
 148   /* Get enough memory to hold the stuff */
 149   bfd *input_bfd = i->owner;
 150   asection *input_section = i;
 151   int *shrinks;
 152   int shrink = 0;
 153   long reloc_size = bfd_get_reloc_upper_bound (input_bfd, input_section);
 154   arelent **reloc_vector = NULL;
 155   long reloc_count;
 156
 157   /* We only do global relaxation once.  It is not safe to do it multiple
 158      times (see discussion of the "shrinks" array below).  */
 159   *again = false;
 160
 161   if (reloc_size < 0)
 162     return false;
 163
 164   reloc_vector = (arelent **) bfd_malloc (reloc_size);
 165   if (!reloc_vector && reloc_size > 0)
 166     return false;
 167
 168   /* Get the relocs and think about them */
 169   reloc_count =
 170     bfd_canonicalize_reloc (input_bfd, input_section, reloc_vector,
 171                             _bfd_generic_link_get_symbols (input_bfd));
 172   if (reloc_count < 0)
 173     {
 174       free (reloc_vector);
 175       return false;
 176     }
 177
 178   /* The reloc16.c and related relaxing code is very simple, the price
 179      for that simplicity is we can only call this function once for
 180      each section.
 181
 182      So, to get the best results within that limitation, we do multiple
 183      relaxing passes over each section here.  That involves keeping track
 184      of the "shrink" at each reloc in the section.  This allows us to
 185      accurately determine the relative location of two relocs within
 186      this section.
 187
 188      In theory, if we kept the "shrinks" array for each section for the
 189      entire link, we could use the generic relaxing code in the linker
 190      and get better results, particularly for jsr->bsr and 24->16 bit
 191      memory reference relaxations.  */
 192
 193   if (reloc_count > 0)
 194     {
 195       int another_pass = 0;
 196
 197       /* Allocate and initialize the shrinks array for this section.  */
 198       shrinks = (int *) bfd_malloc (reloc_count * sizeof (int));
 199       memset (shrinks, 0, reloc_count * sizeof (int));
 200
 201       /* Loop until nothing changes in this section.  */
 202       do {
 203         arelent **parent;
 204         unsigned int i;
 205         long j;
 206
 207         another_pass = 0;
 208
 209         for (i = 0, parent = reloc_vector; *parent; parent++, i++)
 210           {
 211             /* Let the target/machine dependent code examine each reloc
 212                in this section and attempt to shrink it.  */
 213             shrink = bfd_coff_reloc16_estimate (abfd, input_section, *parent,
 214                                                 shrinks[i], link_info);
 215
 216             /* If it shrunk, note it in the shrinks array and set up for
 217                another pass.  */
 218             if (shrink != shrinks[i])
 219               {
 220                 another_pass = 1;
 221                 for (j = i + 1; j < reloc_count; j++)
 222                   shrinks[j] += shrink - shrinks[i];
 223               }
 224           }
 225
 226       } while (another_pass);
 227
 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
 276   reloc_vector = (arelent **) bfd_malloc((size_t) reloc_size);
 277   if (!reloc_vector && reloc_size != 0)
 278     return NULL;
 279
 280   reloc_count = bfd_canonicalize_reloc (input_bfd,
 281                                         input_section,
 282                                         reloc_vector,
 283                                         symbols);
 284   if (reloc_count < 0)
 285     {
 286       free (reloc_vector);
 287       return NULL;
 288     }
 289
 290   if (reloc_count > 0)
 291     {
 292       arelent **parent = reloc_vector;
 293       arelent *reloc ;
 294       unsigned int dst_address = 0;
 295       unsigned int src_address = 0;
 296       unsigned int run;
 297       unsigned int idx;
 298
 299       /* Find how long a run we can do */
 300       while (dst_address < link_order->size)
 301         {
 302           reloc = *parent;
 303           if (reloc)
 304             {
 305               /* Note that the relaxing didn't tie up the addresses in the
 306                  relocation, so we use the original address to work out the
 307                  run of non-relocated data */
 308               run = reloc->address - src_address;
 309               parent++;
 310             }
 311           else
 312             {
 313               run = link_order->size - dst_address;
 314             }
 315           /* Copy the bytes */
 316           for (idx = 0; idx < run; idx++)
 317             {
 318               data[dst_address++] = data[src_address++];
 319             }
 320
 321           /* Now do the relocation */
 322
 323           if (reloc)
 324             {
 325               bfd_coff_reloc16_extra_cases (input_bfd, link_info, link_order,
 326                                             reloc, data, &src_address,
 327                                             &dst_address);
 328             }
 329         }
 330     }
 331   free((char *)reloc_vector);
 332   return data;
 333 }
 334