1/* 8 and 16 bit COFF relocation functions, for BFD. 2 Copyright (C) 1990-2017 Free Software Foundation, Inc. 3 Written by Cygnus Support. 4 5 This file is part of BFD, the Binary File Descriptor library. 6 7 This program is free software; you can redistribute it and/or modify 8 it under the terms of the GNU General Public License as published by 9 the Free Software Foundation; either version 3 of the License, or 10 (at your option) any later version. 11 12 This program is distributed in the hope that it will be useful, 13 but WITHOUT ANY WARRANTY; without even the implied warranty of 14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 15 GNU General Public License for more details. 16 17 You should have received a copy of the GNU General Public License 18 along with this program; if not, write to the Free Software 19 Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, 20 MA 02110-1301, USA. */ 21 22 23/* Most of this hacked by Steve Chamberlain <sac@cygnus.com>. */ 24 25/* These routines are used by coff-h8300 and coff-z8k to do 26 relocation. 27 28 FIXME: This code should be rewritten to support the new COFF 29 linker. Basically, they need to deal with COFF relocs rather than 30 BFD generic relocs. They should store the relocs in some location 31 where coff_link_input_bfd can find them (and coff_link_input_bfd 32 should be changed to use this location rather than rereading the 33 file) (unless info->keep_memory is FALSE, in which case they should 34 free up the relocs after dealing with them). */ 35 36#include "sysdep.h" 37#include "bfd.h" 38#include "libbfd.h" 39#include "bfdlink.h" 40#include "genlink.h" 41#include "coff/internal.h" 42#include "libcoff.h" 43 44bfd_vma 45bfd_coff_reloc16_get_value (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 if (h != (struct bfd_link_hash_entry *) NULL 78 && h->type == bfd_link_hash_undefweak) 79 /* This is a GNU extension. */ 80 value = 0; 81 else 82 { 83 (*link_info->callbacks->undefined_symbol) 84 (link_info, bfd_asymbol_name (symbol), 85 input_section->owner, input_section, reloc->address, TRUE); 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 102void 103bfd_perform_slip (bfd *abfd, 104 unsigned int slip, 105 asection *input_section, 106 bfd_vma value) 107{ 108 asymbol **s; 109 110 s = _bfd_generic_link_get_symbols (abfd); 111 BFD_ASSERT (s != (asymbol **) NULL); 112 113 /* Find all symbols past this point, and make them know 114 what's happened. */ 115 while (*s) 116 { 117 asymbol *p = *s; 118 if (p->section == input_section) 119 { 120 /* This was pointing into this section, so mangle it. */ 121 if (p->value > value) 122 { 123 p->value -= slip; 124 if (p->udata.p != NULL) 125 { 126 struct generic_link_hash_entry *h; 127 128 h = (struct generic_link_hash_entry *) p->udata.p; 129 BFD_ASSERT (h->root.type == bfd_link_hash_defined 130 || h->root.type == bfd_link_hash_defweak); 131 h->root.u.def.value -= slip; 132 BFD_ASSERT (h->root.u.def.value == p->value); 133 } 134 } 135 } 136 s++; 137 } 138} 139 140bfd_boolean 141bfd_coff_reloc16_relax_section (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 if (bfd_link_relocatable (link_info)) 155 (*link_info->callbacks->einfo) 156 (_("%P%F: --relax and -r may not be used together\n")); 157 158 /* We only do global relaxation once. It is not safe to do it multiple 159 times (see discussion of the "shrinks" array below). */ 160 *again = FALSE; 161 162 if (reloc_size < 0) 163 return FALSE; 164 165 reloc_vector = (arelent **) bfd_malloc ((bfd_size_type) reloc_size); 166 if (!reloc_vector && reloc_size > 0) 167 return FALSE; 168 169 /* Get the relocs and think about them. */ 170 reloc_count = 171 bfd_canonicalize_reloc (input_bfd, input_section, reloc_vector, 172 _bfd_generic_link_get_symbols (input_bfd)); 173 if (reloc_count < 0) 174 { 175 free (reloc_vector); 176 return FALSE; 177 } 178 179 /* The reloc16.c and related relaxing code is very simple, the price 180 for that simplicity is we can only call this function once for 181 each section. 182 183 So, to get the best results within that limitation, we do multiple 184 relaxing passes over each section here. That involves keeping track 185 of the "shrink" at each reloc in the section. This allows us to 186 accurately determine the relative location of two relocs within 187 this section. 188 189 In theory, if we kept the "shrinks" array for each section for the 190 entire link, we could use the generic relaxing code in the linker 191 and get better results, particularly for jsr->bsr and 24->16 bit 192 memory reference relaxations. */ 193 194 if (reloc_count > 0) 195 { 196 int another_pass = 0; 197 bfd_size_type amt; 198 199 /* Allocate and initialize the shrinks array for this section. 200 The last element is used as an accumulator of shrinks. */ 201 amt = reloc_count + 1; 202 amt *= sizeof (unsigned); 203 shrinks = (unsigned *) bfd_zmalloc (amt); 204 205 /* Loop until nothing changes in this section. */ 206 do 207 { 208 arelent **parent; 209 unsigned int i; 210 long j; 211 212 another_pass = 0; 213 214 for (i = 0, parent = reloc_vector; *parent; parent++, i++) 215 { 216 /* Let the target/machine dependent code examine each reloc 217 in this section and attempt to shrink it. */ 218 shrink = bfd_coff_reloc16_estimate (abfd, input_section, *parent, 219 shrinks[i], link_info); 220 221 /* If it shrunk, note it in the shrinks array and set up for 222 another pass. */ 223 if (shrink != shrinks[i]) 224 { 225 another_pass = 1; 226 for (j = i + 1; j <= reloc_count; j++) 227 shrinks[j] += shrink - shrinks[i]; 228 } 229 } 230 } 231 while (another_pass); 232 233 shrink = shrinks[reloc_count]; 234 free ((char *) shrinks); 235 } 236 237 input_section->rawsize = input_section->size; 238 input_section->size -= shrink; 239 free ((char *) reloc_vector); 240 return TRUE; 241} 242 243bfd_byte * 244bfd_coff_reloc16_get_relocated_section_contents 245 (bfd *in_abfd, 246 struct bfd_link_info *link_info, 247 struct bfd_link_order *link_order, 248 bfd_byte *data, 249 bfd_boolean relocatable, 250 asymbol **symbols) 251{ 252 /* Get enough memory to hold the stuff. */ 253 bfd *input_bfd = link_order->u.indirect.section->owner; 254 asection *input_section = link_order->u.indirect.section; 255 long reloc_size = bfd_get_reloc_upper_bound (input_bfd, input_section); 256 arelent **reloc_vector; 257 long reloc_count; 258 bfd_size_type sz; 259 260 if (reloc_size < 0) 261 return NULL; 262 263 /* If producing relocatable output, don't bother to relax. */ 264 if (relocatable) 265 return bfd_generic_get_relocated_section_contents (in_abfd, link_info, 266 link_order, 267 data, relocatable, 268 symbols); 269 270 /* Read in the section. */ 271 sz = input_section->rawsize ? input_section->rawsize : input_section->size; 272 if (!bfd_get_section_contents (input_bfd, input_section, data, 0, sz)) 273 return NULL; 274 275 reloc_vector = (arelent **) bfd_malloc ((bfd_size_type) reloc_size); 276 if (!reloc_vector && reloc_size != 0) 277 return NULL; 278 279 reloc_count = bfd_canonicalize_reloc (input_bfd, 280 input_section, 281 reloc_vector, 282 symbols); 283 if (reloc_count < 0) 284 { 285 free (reloc_vector); 286 return NULL; 287 } 288 289 if (reloc_count > 0) 290 { 291 arelent **parent = reloc_vector; 292 arelent *reloc; 293 unsigned int dst_address = 0; 294 unsigned int src_address = 0; 295 unsigned int run; 296 unsigned int idx; 297 298 /* Find how long a run we can do. */ 299 while (dst_address < link_order->size) 300 { 301 reloc = *parent; 302 if (reloc) 303 { 304 /* Note that the relaxing didn't tie up the addresses in the 305 relocation, so we use the original address to work out the 306 run of non-relocated data. */ 307 run = reloc->address - src_address; 308 parent++; 309 } 310 else 311 { 312 run = link_order->size - dst_address; 313 } 314 315 /* Copy the bytes. */ 316 for (idx = 0; idx < run; idx++) 317 data[dst_address++] = data[src_address++]; 318 319 /* Now do the relocation. */ 320 if (reloc) 321 { 322 bfd_coff_reloc16_extra_cases (input_bfd, link_info, link_order, 323 reloc, data, &src_address, 324 &dst_address); 325 } 326 } 327 } 328 free ((char *) reloc_vector); 329 return data; 330} 331