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[gdb.git] / bfd / reloc16.c
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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.
6 This file is part of BFD, the Binary File Descriptor library.
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.
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.
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. */
24 /* Most of this hacked by Steve Chamberlain <sac@cygnus.com>. */
26 /* These routines are used by coff-h8300 and coff-z8k to do
27 relocation.
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). */
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"
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;
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. */
57 if (bfd_is_und_section (symbol->section)
58 || bfd_is_com_section (symbol->section))
60 struct bfd_link_hash_entry *h;
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
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;
89 else
91 value = symbol->value
92 + symbol->section->output_offset
93 + symbol->section->output_section->vma;
96 /* Add the value contained in the relocation. */
97 value += reloc->addend;
99 return value;
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;
109 asymbol **s;
111 s = _bfd_generic_link_get_symbols (abfd);
112 BFD_ASSERT (s != (asymbol **) NULL);
114 /* Find all symbols past this point, and make them know
115 what's happened. */
116 while (*s)
118 asymbol *p = *s;
119 if (p->section == input_section)
121 /* This was pointing into this section, so mangle it. */
122 if (p->value > value)
124 p->value -= slip;
125 if (p->udata.p != NULL)
127 struct generic_link_hash_entry *h;
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);
137 s++;
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;
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;
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;
160 if (reloc_size < 0)
161 return FALSE;
163 reloc_vector = (arelent **) bfd_malloc ((bfd_size_type) reloc_size);
164 if (!reloc_vector && reloc_size > 0)
165 return FALSE;
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)
173 free (reloc_vector);
174 return FALSE;
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.
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.
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. */
192 if (reloc_count > 0)
194 int another_pass = 0;
195 bfd_size_type amt;
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);
203 /* Loop until nothing changes in this section. */
206 arelent **parent;
207 unsigned int i;
208 long j;
210 another_pass = 0;
212 for (i = 0, parent = reloc_vector; *parent; parent++, i++)
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);
219 /* If it shrunk, note it in the shrinks array and set up for
220 another pass. */
221 if (shrink != shrinks[i])
223 another_pass = 1;
224 for (j = i + 1; j <= reloc_count; j++)
225 shrinks[j] += shrink - shrinks[i];
229 while (another_pass);
231 shrink = shrinks[reloc_count];
232 free ((char *) shrinks);
235 input_section->rawsize = input_section->size;
236 input_section->size -= shrink;
237 free ((char *) reloc_vector);
238 return TRUE;
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;
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;
263 if (reloc_size < 0)
264 return NULL;
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);
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;
278 reloc_vector = (arelent **) bfd_malloc ((bfd_size_type) reloc_size);
279 if (!reloc_vector && reloc_size != 0)
280 return NULL;
282 reloc_count = bfd_canonicalize_reloc (input_bfd,
283 input_section,
284 reloc_vector,
285 symbols);
286 if (reloc_count < 0)
288 free (reloc_vector);
289 return NULL;
292 if (reloc_count > 0)
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;
301 /* Find how long a run we can do. */
302 while (dst_address < link_order->size)
304 reloc = *parent;
305 if (reloc)
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++;
313 else
315 run = link_order->size - dst_address;
318 /* Copy the bytes. */
319 for (idx = 0; idx < run; idx++)
320 data[dst_address++] = data[src_address++];
322 /* Now do the relocation. */
323 if (reloc)
325 bfd_coff_reloc16_extra_cases (input_bfd, link_info, link_order,
326 reloc, data, &src_address,
327 &dst_address);
331 free ((char *) reloc_vector);
332 return data;