1 /* 8 and 16 bit COFF relocation functions, for BFD. 2 Copyright (C) 1990-2014 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 (at) 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 44 bfd_vma 45 bfd_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 if (!((*link_info->callbacks->undefined_symbol) 84 (link_info, bfd_asymbol_name (symbol), 85 input_section->owner, input_section, reloc->address, 86 TRUE))) 87 abort (); 88 value = 0; 89 } 90 } 91 else 92 { 93 value = symbol->value 94 + symbol->section->output_offset 95 + symbol->section->output_section->vma; 96 } 97 98 /* Add the value contained in the relocation. */ 99 value += reloc->addend; 100 101 return value; 102 } 103 104 void 105 bfd_perform_slip (bfd *abfd, 106 unsigned int slip, 107 asection *input_section, 108 bfd_vma value) 109 { 110 asymbol **s; 111 112 s = _bfd_generic_link_get_symbols (abfd); 113 BFD_ASSERT (s != (asymbol **) NULL); 114 115 /* Find all symbols past this point, and make them know 116 what's happened. */ 117 while (*s) 118 { 119 asymbol *p = *s; 120 if (p->section == input_section) 121 { 122 /* This was pointing into this section, so mangle it. */ 123 if (p->value > value) 124 { 125 p->value -= slip; 126 if (p->udata.p != NULL) 127 { 128 struct generic_link_hash_entry *h; 129 130 h = (struct generic_link_hash_entry *) p->udata.p; 131 BFD_ASSERT (h->root.type == bfd_link_hash_defined 132 || h->root.type == bfd_link_hash_defweak); 133 h->root.u.def.value -= slip; 134 BFD_ASSERT (h->root.u.def.value == p->value); 135 } 136 } 137 } 138 s++; 139 } 140 } 141 142 bfd_boolean 143 bfd_coff_reloc16_relax_section (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 if (link_info->relocatable) 157 (*link_info->callbacks->einfo) 158 (_("%P%F: --relax and -r may not be used together\n")); 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 247 (bfd *in_abfd, 248 struct bfd_link_info *link_info, 249 struct bfd_link_order *link_order, 250 bfd_byte *data, 251 bfd_boolean relocatable, 252 asymbol **symbols) 253 { 254 /* Get enough memory to hold the stuff. */ 255 bfd *input_bfd = link_order->u.indirect.section->owner; 256 asection *input_section = link_order->u.indirect.section; 257 long reloc_size = bfd_get_reloc_upper_bound (input_bfd, input_section); 258 arelent **reloc_vector; 259 long reloc_count; 260 bfd_size_type sz; 261 262 if (reloc_size < 0) 263 return NULL; 264 265 /* If producing relocatable output, don't bother to relax. */ 266 if (relocatable) 267 return bfd_generic_get_relocated_section_contents (in_abfd, link_info, 268 link_order, 269 data, relocatable, 270 symbols); 271 272 /* Read in the section. */ 273 sz = input_section->rawsize ? input_section->rawsize : input_section->size; 274 if (!bfd_get_section_contents (input_bfd, input_section, data, 0, sz)) 275 return NULL; 276 277 reloc_vector = (arelent **) bfd_malloc ((bfd_size_type) reloc_size); 278 if (!reloc_vector && reloc_size != 0) 279 return NULL; 280 281 reloc_count = bfd_canonicalize_reloc (input_bfd, 282 input_section, 283 reloc_vector, 284 symbols); 285 if (reloc_count < 0) 286 { 287 free (reloc_vector); 288 return NULL; 289 } 290 291 if (reloc_count > 0) 292 { 293 arelent **parent = reloc_vector; 294 arelent *reloc; 295 unsigned int dst_address = 0; 296 unsigned int src_address = 0; 297 unsigned int run; 298 unsigned int idx; 299 300 /* Find how long a run we can do. */ 301 while (dst_address < link_order->size) 302 { 303 reloc = *parent; 304 if (reloc) 305 { 306 /* Note that the relaxing didn't tie up the addresses in the 307 relocation, so we use the original address to work out the 308 run of non-relocated data. */ 309 run = reloc->address - src_address; 310 parent++; 311 } 312 else 313 { 314 run = link_order->size - dst_address; 315 } 316 317 /* Copy the bytes. */ 318 for (idx = 0; idx < run; idx++) 319 data[dst_address++] = data[src_address++]; 320 321 /* Now do the relocation. */ 322 if (reloc) 323 { 324 bfd_coff_reloc16_extra_cases (input_bfd, link_info, link_order, 325 reloc, data, &src_address, 326 &dst_address); 327 } 328 } 329 } 330 free ((char *) reloc_vector); 331 return data; 332 } 333
