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
  80         {
  81           if (!((*link_info->callbacks->undefined_symbol)
  82                 (link_info, bfd_asymbol_name (symbol),
  83                  input_section->owner, input_section, reloc->address,
  84                  TRUE)))
  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 bfd_boolean
 142 bfd_coff_reloc16_relax_section (abfd, input_section, link_info, again)
 143      bfd *abfd;
 144      asection *input_section;
 145      struct bfd_link_info *link_info;
 146      bfd_boolean *again;
 147 {
 148   /* Get enough memory to hold the stuff.  */
 149   bfd *input_bfd = input_section->owner;
 150   unsigned *shrinks;
 151   unsigned shrink = 0;
 152   long reloc_size = bfd_get_reloc_upper_bound (input_bfd, input_section);
 153   arelent **reloc_vector = NULL;
 154   long reloc_count;
 155
 156   /* We only do global relaxation once.  It is not safe to do it multiple
 157      times (see discussion of the "shrinks" array below).  */
 158   *again = FALSE;
 159
 160   if (reloc_size < 0)
 161     return FALSE;
 162
 163   reloc_vector = (arelent **) bfd_malloc ((bfd_size_type) reloc_size);
 164   if (!reloc_vector && reloc_size > 0)
 165     return FALSE;
 166
 167   /* Get the relocs and think about them.  */
 168   reloc_count =
 169     bfd_canonicalize_reloc (input_bfd, input_section, reloc_vector,
 170                             _bfd_generic_link_get_symbols (input_bfd));
 171   if (reloc_count < 0)
 172     {
 173       free (reloc_vector);
 174       return FALSE;
 175     }
 176
 177   /* The reloc16.c and related relaxing code is very simple, the price
 178      for that simplicity is we can only call this function once for
 179      each section.
 180
 181      So, to get the best results within that limitation, we do multiple
 182      relaxing passes over each section here.  That involves keeping track
 183      of the "shrink" at each reloc in the section.  This allows us to
 184      accurately determine the relative location of two relocs within
 185      this section.
 186
 187      In theory, if we kept the "shrinks" array for each section for the
 188      entire link, we could use the generic relaxing code in the linker
 189      and get better results, particularly for jsr->bsr and 24->16 bit
 190      memory reference relaxations.  */
 191
 192   if (reloc_count > 0)
 193     {
 194       int another_pass = 0;
 195       bfd_size_type amt;
 196
 197       /* Allocate and initialize the shrinks array for this section.
 198          The last element is used as an accumulator of shrinks.  */
 199       amt = reloc_count + 1;
 200       amt *= sizeof (unsigned);
 201       shrinks = (unsigned *) bfd_zmalloc (amt);
 202
 203       /* Loop until nothing changes in this section.  */
 204       do
 205         {
 206           arelent **parent;
 207           unsigned int i;
 208           long j;
 209
 210           another_pass = 0;
 211
 212           for (i = 0, parent = reloc_vector; *parent; parent++, i++)
 213             {
 214               /* Let the target/machine dependent code examine each reloc
 215                  in this section and attempt to shrink it.  */
 216               shrink = bfd_coff_reloc16_estimate (abfd, input_section, *parent,
 217                                                   shrinks[i], link_info);
 218
 219               /* If it shrunk, note it in the shrinks array and set up for
 220                  another pass.  */
 221               if (shrink != shrinks[i])
 222                 {
 223                   another_pass = 1;
 224                   for (j = i + 1; j <= reloc_count; j++)
 225                     shrinks[j] += shrink - shrinks[i];
 226                 }
 227             }
 228         }
 229       while (another_pass);
 230
 231       shrink = shrinks[reloc_count];
 232       free ((char *) shrinks);
 233     }
 234
 235   input_section->rawsize = input_section->size;
 236   input_section->size -= shrink;
 237   free ((char *) reloc_vector);
 238   return TRUE;
 239 }
 240
 241 bfd_byte *
 242 bfd_coff_reloc16_get_relocated_section_contents (in_abfd,
 243                                                  link_info,
 244                                                  link_order,
 245                                                  data,
 246                                                  relocatable,
 247                                                  symbols)
 248      bfd *in_abfd;
 249      struct bfd_link_info *link_info;
 250      struct bfd_link_order *link_order;
 251      bfd_byte *data;
 252      bfd_boolean relocatable;
 253      asymbol **symbols;
 254 {
 255   /* Get enough memory to hold the stuff.  */
 256   bfd *input_bfd = link_order->u.indirect.section->owner;
 257   asection *input_section = link_order->u.indirect.section;
 258   long reloc_size = bfd_get_reloc_upper_bound (input_bfd, input_section);
 259   arelent **reloc_vector;
 260   long reloc_count;
 261   bfd_size_type sz;
 262
 263   if (reloc_size < 0)
 264     return NULL;
 265
 266   /* If producing relocatable output, don't bother to relax.  */
 267   if (relocatable)
 268     return bfd_generic_get_relocated_section_contents (in_abfd, link_info,
 269                                                        link_order,
 270                                                        data, relocatable,
 271                                                        symbols);
 272
 273   /* Read in the section.  */
 274   sz = input_section->rawsize ? input_section->rawsize : input_section->size;
 275   if (!bfd_get_section_contents (input_bfd, input_section, data, 0, sz))
 276     return NULL;
 277
 278   reloc_vector = (arelent **) bfd_malloc ((bfd_size_type) reloc_size);
 279   if (!reloc_vector && reloc_size != 0)
 280     return NULL;
 281
 282   reloc_count = bfd_canonicalize_reloc (input_bfd,
 283                                         input_section,
 284                                         reloc_vector,
 285                                         symbols);
 286   if (reloc_count < 0)
 287     {
 288       free (reloc_vector);
 289       return NULL;
 290     }
 291
 292   if (reloc_count > 0)
 293     {
 294       arelent **parent = reloc_vector;
 295       arelent *reloc;
 296       unsigned int dst_address = 0;
 297       unsigned int src_address = 0;
 298       unsigned int run;
 299       unsigned int idx;
 300
 301       /* Find how long a run we can do.  */
 302       while (dst_address < link_order->size)
 303         {
 304           reloc = *parent;
 305           if (reloc)
 306             {
 307               /* Note that the relaxing didn't tie up the addresses in the
 308                  relocation, so we use the original address to work out the
 309                  run of non-relocated data.  */
 310               run = reloc->address - src_address;
 311               parent++;
 312             }
 313           else
 314             {
 315               run = link_order->size - dst_address;
 316             }
 317
 318           /* Copy the bytes.  */
 319           for (idx = 0; idx < run; idx++)
 320             data[dst_address++] = data[src_address++];
 321
 322           /* Now do the relocation.  */
 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 }