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                   true)))
  86             abort ();
  87           value = 0;
  88         }
  89     }
  90   else
  91     {
  92       value = symbol->value +
  93         symbol->section->output_offset +
  94           symbol->section->output_section->vma;
  95     }
  96
  97   /* Add the value contained in the relocation */
  98   value += reloc->addend;
  99
 100   return value;
 101 }
 102
 103 void
 104 bfd_perform_slip(abfd, slip, input_section, value)
 105      bfd *abfd;
 106      unsigned int slip;
 107      asection *input_section;
 108      bfd_vma value;
 109 {
 110   asymbol **s;
 111
 112   s = _bfd_generic_link_get_symbols (abfd);
 113   BFD_ASSERT (s != (asymbol **) NULL);
 114
 115   /* Find all symbols past this point, and make them know
 116      what's happened */
 117   while (*s)
 118     {
 119       asymbol *p = *s;
 120       if (p->section == input_section)
 121         {
 122           /* This was pointing into this section, so mangle it */
 123           if (p->value > value)
 124             {
 125               p->value -= slip;
 126               if (p->udata.p != NULL)
 127                 {
 128                   struct generic_link_hash_entry *h;
 129
 130                   h = (struct generic_link_hash_entry *) p->udata.p;
 131                   BFD_ASSERT (h->root.type == bfd_link_hash_defined
 132                               || h->root.type == bfd_link_hash_defweak);
 133                   h->root.u.def.value -= slip;
 134                   BFD_ASSERT (h->root.u.def.value == p->value);
 135                 }
 136             }
 137         }
 138       s++;
 139     }
 140 }
 141
 142 boolean
 143 bfd_coff_reloc16_relax_section (abfd, i, link_info, again)
 144      bfd *abfd;
 145      asection *i;
 146      struct bfd_link_info *link_info;
 147      boolean *again;
 148 {
 149   /* Get enough memory to hold the stuff */
 150   bfd *input_bfd = i->owner;
 151   asection *input_section = i;
 152   int *shrinks;
 153   int shrink = 0;
 154   long reloc_size = bfd_get_reloc_upper_bound (input_bfd, input_section);
 155   arelent **reloc_vector = NULL;
 156   long reloc_count;
 157
 158   /* We only do global relaxation once.  It is not safe to do it multiple
 159      times (see discussion of the "shrinks" array below).  */
 160   *again = false;
 161
 162   if (reloc_size < 0)
 163     return false;
 164
 165   reloc_vector = (arelent **) bfd_malloc (reloc_size);
 166   if (!reloc_vector && reloc_size > 0)
 167     return false;
 168
 169   /* Get the relocs and think about them */
 170   reloc_count =
 171     bfd_canonicalize_reloc (input_bfd, input_section, reloc_vector,
 172                             _bfd_generic_link_get_symbols (input_bfd));
 173   if (reloc_count < 0)
 174     {
 175       free (reloc_vector);
 176       return false;
 177     }
 178
 179   /* The reloc16.c and related relaxing code is very simple, the price
 180      for that simplicity is we can only call this function once for
 181      each section.
 182
 183      So, to get the best results within that limitation, we do multiple
 184      relaxing passes over each section here.  That involves keeping track
 185      of the "shrink" at each reloc in the section.  This allows us to
 186      accurately determine the relative location of two relocs within
 187      this section.
 188
 189      In theory, if we kept the "shrinks" array for each section for the
 190      entire link, we could use the generic relaxing code in the linker
 191      and get better results, particularly for jsr->bsr and 24->16 bit
 192      memory reference relaxations.  */
 193
 194   if (reloc_count > 0)
 195     {
 196       int another_pass = 0;
 197
 198       /* Allocate and initialize the shrinks array for this section.
 199          The last element is used as an accumlator of shrinks.  */
 200       shrinks = (int *) bfd_malloc ((reloc_count + 1) * sizeof (int));
 201       memset (shrinks, 0, (reloc_count + 1) * sizeof (int));
 202
 203       /* Loop until nothing changes in this section.  */
 204       do {
 205         arelent **parent;
 206         unsigned int i;
 207         long j;
 208
 209         another_pass = 0;
 210
 211         for (i = 0, parent = reloc_vector; *parent; parent++, i++)
 212           {
 213             /* Let the target/machine dependent code examine each reloc
 214                in this section and attempt to shrink it.  */
 215             shrink = bfd_coff_reloc16_estimate (abfd, input_section, *parent,
 216                                                 shrinks[i], link_info);
 217
 218             /* If it shrunk, note it in the shrinks array and set up for
 219                another pass.  */
 220             if (shrink != shrinks[i])
 221               {
 222                 another_pass = 1;
 223                 for (j = i + 1; j <= reloc_count; j++)
 224                   shrinks[j] += shrink - shrinks[i];
 225               }
 226           }
 227
 228       } while (another_pass);
 229
 230       shrink = shrinks[reloc_count];
 231       free((char *)shrinks);
 232     }
 233
 234   input_section->_cooked_size -= shrink;
 235   free((char *)reloc_vector);
 236   return true;
 237 }
 238
 239 bfd_byte *
 240 bfd_coff_reloc16_get_relocated_section_contents(in_abfd,
 241                                                 link_info,
 242                                                 link_order,
 243                                                 data,
 244                                                 relocateable,
 245                                                 symbols)
 246      bfd *in_abfd;
 247      struct bfd_link_info *link_info;
 248      struct bfd_link_order *link_order;
 249      bfd_byte *data;
 250      boolean relocateable;
 251      asymbol **symbols;
 252 {
 253   /* Get enough memory to hold the stuff */
 254   bfd *input_bfd = link_order->u.indirect.section->owner;
 255   asection *input_section = link_order->u.indirect.section;
 256   long reloc_size = bfd_get_reloc_upper_bound (input_bfd, input_section);
 257   arelent **reloc_vector;
 258   long reloc_count;
 259
 260   if (reloc_size < 0)
 261     return NULL;
 262
 263   /* If producing relocateable output, don't bother to relax.  */
 264   if (relocateable)
 265     return bfd_generic_get_relocated_section_contents (in_abfd, link_info,
 266                                                        link_order,
 267                                                        data, relocateable,
 268                                                        symbols);
 269
 270   /* read in the section */
 271   if (! bfd_get_section_contents(input_bfd,
 272                                  input_section,
 273                                  data,
 274                                  0,
 275                                  input_section->_raw_size))
 276     return NULL;
 277
 278
 279   reloc_vector = (arelent **) bfd_malloc((size_t) reloc_size);
 280   if (!reloc_vector && reloc_size != 0)
 281     return NULL;
 282
 283   reloc_count = bfd_canonicalize_reloc (input_bfd,
 284                                         input_section,
 285                                         reloc_vector,
 286                                         symbols);
 287   if (reloc_count < 0)
 288     {
 289       free (reloc_vector);
 290       return NULL;
 291     }
 292
 293   if (reloc_count > 0)
 294     {
 295       arelent **parent = reloc_vector;
 296       arelent *reloc ;
 297       unsigned int dst_address = 0;
 298       unsigned int src_address = 0;
 299       unsigned int run;
 300       unsigned int idx;
 301
 302       /* Find how long a run we can do */
 303       while (dst_address < link_order->size)
 304         {
 305           reloc = *parent;
 306           if (reloc)
 307             {
 308               /* Note that the relaxing didn't tie up the addresses in the
 309                  relocation, so we use the original address to work out the
 310                  run of non-relocated data */
 311               run = reloc->address - src_address;
 312               parent++;
 313             }
 314           else
 315             {
 316               run = link_order->size - dst_address;
 317             }
 318           /* Copy the bytes */
 319           for (idx = 0; idx < run; idx++)
 320             {
 321               data[dst_address++] = data[src_address++];
 322             }
 323
 324           /* Now do the relocation */
 325
 326           if (reloc)
 327             {
 328               bfd_coff_reloc16_extra_cases (input_bfd, link_info, link_order,
 329                                             reloc, data, &src_address,
 330                                             &dst_address);
 331             }
 332         }
 333     }
 334   free((char *)reloc_vector);
 335   return data;
 336 }
 337