bfd/reloc16.c

   1 /* 8 and 16 bit COFF relocation functions, for BFD.
   2    Copyright 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1998, 2000, 2001,
   3    2002, 2003, 2004 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., 51 Franklin Street - Fifth Floor, Boston, MA 02110-1301, 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 bfd_boolean
 140 bfd_coff_reloc16_relax_section (abfd, input_section, link_info, again)
 141      bfd *abfd;
 142      asection *input_section;
 143      struct bfd_link_info *link_info;
 144      bfd_boolean *again;
 145 {
 146   /* Get enough memory to hold the stuff.  */
 147   bfd *input_bfd = input_section->owner;
 148   unsigned *shrinks;
 149   unsigned shrink = 0;
 150   long reloc_size = bfd_get_reloc_upper_bound (input_bfd, input_section);
 151   arelent **reloc_vector = NULL;
 152   long reloc_count;
 153
 154   /* We only do global relaxation once.  It is not safe to do it multiple
 155      times (see discussion of the "shrinks" array below).  */
 156   *again = FALSE;
 157
 158   if (reloc_size < 0)
 159     return FALSE;
 160
 161   reloc_vector = (arelent **) bfd_malloc ((bfd_size_type) reloc_size);
 162   if (!reloc_vector && reloc_size > 0)
 163     return FALSE;
 164
 165   /* Get the relocs and think about them.  */
 166   reloc_count =
 167     bfd_canonicalize_reloc (input_bfd, input_section, reloc_vector,
 168                             _bfd_generic_link_get_symbols (input_bfd));
 169   if (reloc_count < 0)
 170     {
 171       free (reloc_vector);
 172       return FALSE;
 173     }
 174
 175   /* The reloc16.c and related relaxing code is very simple, the price
 176      for that simplicity is we can only call this function once for
 177      each section.
 178
 179      So, to get the best results within that limitation, we do multiple
 180      relaxing passes over each section here.  That involves keeping track
 181      of the "shrink" at each reloc in the section.  This allows us to
 182      accurately determine the relative location of two relocs within
 183      this section.
 184
 185      In theory, if we kept the "shrinks" array for each section for the
 186      entire link, we could use the generic relaxing code in the linker
 187      and get better results, particularly for jsr->bsr and 24->16 bit
 188      memory reference relaxations.  */
 189
 190   if (reloc_count > 0)
 191     {
 192       int another_pass = 0;
 193       bfd_size_type amt;
 194
 195       /* Allocate and initialize the shrinks array for this section.
 196          The last element is used as an accumulator of shrinks.  */
 197       amt = reloc_count + 1;
 198       amt *= sizeof (unsigned);
 199       shrinks = (unsigned *) bfd_zmalloc (amt);
 200
 201       /* Loop until nothing changes in this section.  */
 202       do
 203         {
 204           arelent **parent;
 205           unsigned int i;
 206           long j;
 207
 208           another_pass = 0;
 209
 210           for (i = 0, parent = reloc_vector; *parent; parent++, i++)
 211             {
 212               /* Let the target/machine dependent code examine each reloc
 213                  in this section and attempt to shrink it.  */
 214               shrink = bfd_coff_reloc16_estimate (abfd, input_section, *parent,
 215                                                   shrinks[i], link_info);
 216
 217               /* If it shrunk, note it in the shrinks array and set up for
 218                  another pass.  */
 219               if (shrink != shrinks[i])
 220                 {
 221                   another_pass = 1;
 222                   for (j = i + 1; j <= reloc_count; j++)
 223                     shrinks[j] += shrink - shrinks[i];
 224                 }
 225             }
 226         }
 227       while (another_pass);
 228
 229       shrink = shrinks[reloc_count];
 230       free ((char *) shrinks);
 231     }
 232
 233   input_section->rawsize = input_section->size;
 234   input_section->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                                                  relocatable,
 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      bfd_boolean relocatable;
 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   bfd_size_type sz;
 260
 261   if (reloc_size < 0)
 262     return NULL;
 263
 264   /* If producing relocatable output, don't bother to relax.  */
 265   if (relocatable)
 266     return bfd_generic_get_relocated_section_contents (in_abfd, link_info,
 267                                                        link_order,
 268                                                        data, relocatable,
 269                                                        symbols);
 270
 271   /* Read in the section.  */
 272   sz = input_section->rawsize ? input_section->rawsize : input_section->size;
 273   if (!bfd_get_section_contents (input_bfd, input_section, data, 0, sz))
 274     return NULL;
 275
 276   reloc_vector = (arelent **) bfd_malloc ((bfd_size_type) 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
 316           /* Copy the bytes.  */
 317           for (idx = 0; idx < run; idx++)
 318             data[dst_address++] = data[src_address++];
 319
 320           /* Now do the relocation.  */
 321           if (reloc)
 322             {
 323               bfd_coff_reloc16_extra_cases (input_bfd, link_info, link_order,
 324                                             reloc, data, &src_address,
 325                                             &dst_address);
 326             }
 327         }
 328     }
 329   free ((char *) reloc_vector);
 330   return data;
 331 }