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, 2007 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 3 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,
  21    MA 02110-1301, USA.  */
  22
  23
  24 /* Most of this hacked by Steve Chamberlain <sac@cygnus.com>.  */
  25
  26 /* These routines are used by coff-h8300 and coff-z8k to do
  27    relocation.
  28
  29    FIXME: This code should be rewritten to support the new COFF
  30    linker.  Basically, they need to deal with COFF relocs rather than
  31    BFD generic relocs.  They should store the relocs in some location
  32    where coff_link_input_bfd can find them (and coff_link_input_bfd
  33    should be changed to use this location rather than rereading the
  34    file) (unless info->keep_memory is FALSE, in which case they should
  35    free up the relocs after dealing with them).  */
  36
  37 #include "sysdep.h"
  38 #include "bfd.h"
  39 #include "libbfd.h"
  40 #include "bfdlink.h"
  41 #include "genlink.h"
  42 #include "coff/internal.h"
  43 #include "libcoff.h"
  44
  45 bfd_vma
  46 bfd_coff_reloc16_get_value (reloc, link_info, input_section)
  47      arelent *reloc;
  48      struct bfd_link_info *link_info;
  49      asection *input_section;
  50 {
  51   bfd_vma value;
  52   asymbol *symbol = *(reloc->sym_ptr_ptr);
  53   /* A symbol holds a pointer to a section, and an offset from the
  54      base of the section.  To relocate, we find where the section will
  55      live in the output and add that in.  */
  56
  57   if (bfd_is_und_section (symbol->section)
  58       || bfd_is_com_section (symbol->section))
  59     {
  60       struct bfd_link_hash_entry *h;
  61
  62       /* The symbol is undefined in this BFD.  Look it up in the
  63          global linker hash table.  FIXME: This should be changed when
  64          we convert this stuff to use a specific final_link function
  65          and change the interface to bfd_relax_section to not require
  66          the generic symbols.  */
  67       h = bfd_wrapped_link_hash_lookup (input_section->owner, link_info,
  68                                         bfd_asymbol_name (symbol),
  69                                         FALSE, FALSE, TRUE);
  70       if (h != (struct bfd_link_hash_entry *) NULL
  71           && (h->type == bfd_link_hash_defined
  72               || h->type == bfd_link_hash_defweak))
  73         value = (h->u.def.value
  74                  + h->u.def.section->output_section->vma
  75                  + h->u.def.section->output_offset);
  76       else if (h != (struct bfd_link_hash_entry *) NULL
  77                && h->type == bfd_link_hash_common)
  78         value = h->u.c.size;
  79       else if (h != (struct bfd_link_hash_entry *) NULL
  80                && h->type == bfd_link_hash_undefweak)
  81         /* This is a GNU extension.  */
  82         value = 0;
  83       else
  84         {
  85           if (!((*link_info->callbacks->undefined_symbol)
  86                 (link_info, bfd_asymbol_name (symbol),
  87                  input_section->owner, input_section, reloc->address,
  88                  TRUE)))
  89             abort ();
  90           value = 0;
  91         }
  92     }
  93   else
  94     {
  95       value = symbol->value
  96         + symbol->section->output_offset
  97         + symbol->section->output_section->vma;
  98     }
  99
 100   /* Add the value contained in the relocation.  */
 101   value += reloc->addend;
 102
 103   return value;
 104 }
 105
 106 void
 107 bfd_perform_slip (abfd, slip, input_section, value)
 108      bfd *abfd;
 109      unsigned int slip;
 110      asection *input_section;
 111      bfd_vma value;
 112 {
 113   asymbol **s;
 114
 115   s = _bfd_generic_link_get_symbols (abfd);
 116   BFD_ASSERT (s != (asymbol **) NULL);
 117
 118   /* Find all symbols past this point, and make them know
 119      what's happened.  */
 120   while (*s)
 121     {
 122       asymbol *p = *s;
 123       if (p->section == input_section)
 124         {
 125           /* This was pointing into this section, so mangle it.  */
 126           if (p->value > value)
 127             {
 128               p->value -= slip;
 129               if (p->udata.p != NULL)
 130                 {
 131                   struct generic_link_hash_entry *h;
 132
 133                   h = (struct generic_link_hash_entry *) p->udata.p;
 134                   BFD_ASSERT (h->root.type == bfd_link_hash_defined
 135                               || h->root.type == bfd_link_hash_defweak);
 136                   h->root.u.def.value -= slip;
 137                   BFD_ASSERT (h->root.u.def.value == p->value);
 138                 }
 139             }
 140         }
 141       s++;
 142     }
 143 }
 144
 145 bfd_boolean
 146 bfd_coff_reloc16_relax_section (abfd, input_section, link_info, again)
 147      bfd *abfd;
 148      asection *input_section;
 149      struct bfd_link_info *link_info;
 150      bfd_boolean *again;
 151 {
 152   /* Get enough memory to hold the stuff.  */
 153   bfd *input_bfd = input_section->owner;
 154   unsigned *shrinks;
 155   unsigned shrink = 0;
 156   long reloc_size = bfd_get_reloc_upper_bound (input_bfd, input_section);
 157   arelent **reloc_vector = NULL;
 158   long reloc_count;
 159
 160   /* We only do global relaxation once.  It is not safe to do it multiple
 161      times (see discussion of the "shrinks" array below).  */
 162   *again = FALSE;
 163
 164   if (reloc_size < 0)
 165     return FALSE;
 166
 167   reloc_vector = (arelent **) bfd_malloc ((bfd_size_type) reloc_size);
 168   if (!reloc_vector && reloc_size > 0)
 169     return FALSE;
 170
 171   /* Get the relocs and think about them.  */
 172   reloc_count =
 173     bfd_canonicalize_reloc (input_bfd, input_section, reloc_vector,
 174                             _bfd_generic_link_get_symbols (input_bfd));
 175   if (reloc_count < 0)
 176     {
 177       free (reloc_vector);
 178       return FALSE;
 179     }
 180
 181   /* The reloc16.c and related relaxing code is very simple, the price
 182      for that simplicity is we can only call this function once for
 183      each section.
 184
 185      So, to get the best results within that limitation, we do multiple
 186      relaxing passes over each section here.  That involves keeping track
 187      of the "shrink" at each reloc in the section.  This allows us to
 188      accurately determine the relative location of two relocs within
 189      this section.
 190
 191      In theory, if we kept the "shrinks" array for each section for the
 192      entire link, we could use the generic relaxing code in the linker
 193      and get better results, particularly for jsr->bsr and 24->16 bit
 194      memory reference relaxations.  */
 195
 196   if (reloc_count > 0)
 197     {
 198       int another_pass = 0;
 199       bfd_size_type amt;
 200
 201       /* Allocate and initialize the shrinks array for this section.
 202          The last element is used as an accumulator of shrinks.  */
 203       amt = reloc_count + 1;
 204       amt *= sizeof (unsigned);
 205       shrinks = (unsigned *) bfd_zmalloc (amt);
 206
 207       /* Loop until nothing changes in this section.  */
 208       do
 209         {
 210           arelent **parent;
 211           unsigned int i;
 212           long j;
 213
 214           another_pass = 0;
 215
 216           for (i = 0, parent = reloc_vector; *parent; parent++, i++)
 217             {
 218               /* Let the target/machine dependent code examine each reloc
 219                  in this section and attempt to shrink it.  */
 220               shrink = bfd_coff_reloc16_estimate (abfd, input_section, *parent,
 221                                                   shrinks[i], link_info);
 222
 223               /* If it shrunk, note it in the shrinks array and set up for
 224                  another pass.  */
 225               if (shrink != shrinks[i])
 226                 {
 227                   another_pass = 1;
 228                   for (j = i + 1; j <= reloc_count; j++)
 229                     shrinks[j] += shrink - shrinks[i];
 230                 }
 231             }
 232         }
 233       while (another_pass);
 234
 235       shrink = shrinks[reloc_count];
 236       free ((char *) shrinks);
 237     }
 238
 239   input_section->rawsize = input_section->size;
 240   input_section->size -= shrink;
 241   free ((char *) reloc_vector);
 242   return TRUE;
 243 }
 244
 245 bfd_byte *
 246 bfd_coff_reloc16_get_relocated_section_contents (in_abfd,
 247                                                  link_info,
 248                                                  link_order,
 249                                                  data,
 250                                                  relocatable,
 251                                                  symbols)
 252      bfd *in_abfd;
 253      struct bfd_link_info *link_info;
 254      struct bfd_link_order *link_order;
 255      bfd_byte *data;
 256      bfd_boolean relocatable;
 257      asymbol **symbols;
 258 {
 259   /* Get enough memory to hold the stuff.  */
 260   bfd *input_bfd = link_order->u.indirect.section->owner;
 261   asection *input_section = link_order->u.indirect.section;
 262   long reloc_size = bfd_get_reloc_upper_bound (input_bfd, input_section);
 263   arelent **reloc_vector;
 264   long reloc_count;
 265   bfd_size_type sz;
 266
 267   if (reloc_size < 0)
 268     return NULL;
 269
 270   /* If producing relocatable output, don't bother to relax.  */
 271   if (relocatable)
 272     return bfd_generic_get_relocated_section_contents (in_abfd, link_info,
 273                                                        link_order,
 274                                                        data, relocatable,
 275                                                        symbols);
 276
 277   /* Read in the section.  */
 278   sz = input_section->rawsize ? input_section->rawsize : input_section->size;
 279   if (!bfd_get_section_contents (input_bfd, input_section, data, 0, sz))
 280     return NULL;
 281
 282   reloc_vector = (arelent **) bfd_malloc ((bfd_size_type) reloc_size);
 283   if (!reloc_vector && reloc_size != 0)
 284     return NULL;
 285
 286   reloc_count = bfd_canonicalize_reloc (input_bfd,
 287                                         input_section,
 288                                         reloc_vector,
 289                                         symbols);
 290   if (reloc_count < 0)
 291     {
 292       free (reloc_vector);
 293       return NULL;
 294     }
 295
 296   if (reloc_count > 0)
 297     {
 298       arelent **parent = reloc_vector;
 299       arelent *reloc;
 300       unsigned int dst_address = 0;
 301       unsigned int src_address = 0;
 302       unsigned int run;
 303       unsigned int idx;
 304
 305       /* Find how long a run we can do.  */
 306       while (dst_address < link_order->size)
 307         {
 308           reloc = *parent;
 309           if (reloc)
 310             {
 311               /* Note that the relaxing didn't tie up the addresses in the
 312                  relocation, so we use the original address to work out the
 313                  run of non-relocated data.  */
 314               run = reloc->address - src_address;
 315               parent++;
 316             }
 317           else
 318             {
 319               run = link_order->size - dst_address;
 320             }
 321
 322           /* Copy the bytes.  */
 323           for (idx = 0; idx < run; idx++)
 324             data[dst_address++] = data[src_address++];
 325
 326           /* Now do the relocation.  */
 327           if (reloc)
 328             {
 329               bfd_coff_reloc16_extra_cases (input_bfd, link_info, link_order,
 330                                             reloc, data, &src_address,
 331                                             &dst_address);
 332             }
 333         }
 334     }
 335   free ((char *) reloc_vector);
 336   return data;
 337 }