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, 2005, 2007, 2008, 2009 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   if (link_info->relocatable)
 161     (*link_info->callbacks->einfo)
 162       (_("%P%F: --relax and -r may not be used together\n"));
 163
 164   /* We only do global relaxation once.  It is not safe to do it multiple
 165      times (see discussion of the "shrinks" array below).  */
 166   *again = FALSE;
 167
 168   if (reloc_size < 0)
 169     return FALSE;
 170
 171   reloc_vector = (arelent **) bfd_malloc ((bfd_size_type) reloc_size);
 172   if (!reloc_vector && reloc_size > 0)
 173     return FALSE;
 174
 175   /* Get the relocs and think about them.  */
 176   reloc_count =
 177     bfd_canonicalize_reloc (input_bfd, input_section, reloc_vector,
 178                             _bfd_generic_link_get_symbols (input_bfd));
 179   if (reloc_count < 0)
 180     {
 181       free (reloc_vector);
 182       return FALSE;
 183     }
 184
 185   /* The reloc16.c and related relaxing code is very simple, the price
 186      for that simplicity is we can only call this function once for
 187      each section.
 188
 189      So, to get the best results within that limitation, we do multiple
 190      relaxing passes over each section here.  That involves keeping track
 191      of the "shrink" at each reloc in the section.  This allows us to
 192      accurately determine the relative location of two relocs within
 193      this section.
 194
 195      In theory, if we kept the "shrinks" array for each section for the
 196      entire link, we could use the generic relaxing code in the linker
 197      and get better results, particularly for jsr->bsr and 24->16 bit
 198      memory reference relaxations.  */
 199
 200   if (reloc_count > 0)
 201     {
 202       int another_pass = 0;
 203       bfd_size_type amt;
 204
 205       /* Allocate and initialize the shrinks array for this section.
 206          The last element is used as an accumulator of shrinks.  */
 207       amt = reloc_count + 1;
 208       amt *= sizeof (unsigned);
 209       shrinks = (unsigned *) bfd_zmalloc (amt);
 210
 211       /* Loop until nothing changes in this section.  */
 212       do
 213         {
 214           arelent **parent;
 215           unsigned int i;
 216           long j;
 217
 218           another_pass = 0;
 219
 220           for (i = 0, parent = reloc_vector; *parent; parent++, i++)
 221             {
 222               /* Let the target/machine dependent code examine each reloc
 223                  in this section and attempt to shrink it.  */
 224               shrink = bfd_coff_reloc16_estimate (abfd, input_section, *parent,
 225                                                   shrinks[i], link_info);
 226
 227               /* If it shrunk, note it in the shrinks array and set up for
 228                  another pass.  */
 229               if (shrink != shrinks[i])
 230                 {
 231                   another_pass = 1;
 232                   for (j = i + 1; j <= reloc_count; j++)
 233                     shrinks[j] += shrink - shrinks[i];
 234                 }
 235             }
 236         }
 237       while (another_pass);
 238
 239       shrink = shrinks[reloc_count];
 240       free ((char *) shrinks);
 241     }
 242
 243   input_section->rawsize = input_section->size;
 244   input_section->size -= shrink;
 245   free ((char *) reloc_vector);
 246   return TRUE;
 247 }
 248
 249 bfd_byte *
 250 bfd_coff_reloc16_get_relocated_section_contents (in_abfd,
 251                                                  link_info,
 252                                                  link_order,
 253                                                  data,
 254                                                  relocatable,
 255                                                  symbols)
 256      bfd *in_abfd;
 257      struct bfd_link_info *link_info;
 258      struct bfd_link_order *link_order;
 259      bfd_byte *data;
 260      bfd_boolean relocatable;
 261      asymbol **symbols;
 262 {
 263   /* Get enough memory to hold the stuff.  */
 264   bfd *input_bfd = link_order->u.indirect.section->owner;
 265   asection *input_section = link_order->u.indirect.section;
 266   long reloc_size = bfd_get_reloc_upper_bound (input_bfd, input_section);
 267   arelent **reloc_vector;
 268   long reloc_count;
 269   bfd_size_type sz;
 270
 271   if (reloc_size < 0)
 272     return NULL;
 273
 274   /* If producing relocatable output, don't bother to relax.  */
 275   if (relocatable)
 276     return bfd_generic_get_relocated_section_contents (in_abfd, link_info,
 277                                                        link_order,
 278                                                        data, relocatable,
 279                                                        symbols);
 280
 281   /* Read in the section.  */
 282   sz = input_section->rawsize ? input_section->rawsize : input_section->size;
 283   if (!bfd_get_section_contents (input_bfd, input_section, data, 0, sz))
 284     return NULL;
 285
 286   reloc_vector = (arelent **) bfd_malloc ((bfd_size_type) reloc_size);
 287   if (!reloc_vector && reloc_size != 0)
 288     return NULL;
 289
 290   reloc_count = bfd_canonicalize_reloc (input_bfd,
 291                                         input_section,
 292                                         reloc_vector,
 293                                         symbols);
 294   if (reloc_count < 0)
 295     {
 296       free (reloc_vector);
 297       return NULL;
 298     }
 299
 300   if (reloc_count > 0)
 301     {
 302       arelent **parent = reloc_vector;
 303       arelent *reloc;
 304       unsigned int dst_address = 0;
 305       unsigned int src_address = 0;
 306       unsigned int run;
 307       unsigned int idx;
 308
 309       /* Find how long a run we can do.  */
 310       while (dst_address < link_order->size)
 311         {
 312           reloc = *parent;
 313           if (reloc)
 314             {
 315               /* Note that the relaxing didn't tie up the addresses in the
 316                  relocation, so we use the original address to work out the
 317                  run of non-relocated data.  */
 318               run = reloc->address - src_address;
 319               parent++;
 320             }
 321           else
 322             {
 323               run = link_order->size - dst_address;
 324             }
 325
 326           /* Copy the bytes.  */
 327           for (idx = 0; idx < run; idx++)
 328             data[dst_address++] = data[src_address++];
 329
 330           /* Now do the relocation.  */
 331           if (reloc)
 332             {
 333               bfd_coff_reloc16_extra_cases (input_bfd, link_info, link_order,
 334                                             reloc, data, &src_address,
 335                                             &dst_address);
 336             }
 337         }
 338     }
 339   free ((char *) reloc_vector);
 340   return data;
 341 }