Ulrich Drepper | b08d5a8 | 2005-07-26 05:00:05 +0000 | [diff] [blame^] | 1 | /* Copyright (C) 2001, 2002, 2003, 2004, 2005 Red Hat, Inc. |
| 2 | Written by Ulrich Drepper <drepper@redhat.com>, 2001. |
| 3 | |
| 4 | This program is Open Source software; you can redistribute it and/or |
| 5 | modify it under the terms of the Open Software License version 1.0 as |
| 6 | published by the Open Source Initiative. |
| 7 | |
| 8 | You should have received a copy of the Open Software License along |
| 9 | with this program; if not, you may obtain a copy of the Open Software |
| 10 | License version 1.0 from http://www.opensource.org/licenses/osl.php or |
| 11 | by writing the Open Source Initiative c/o Lawrence Rosen, Esq., |
| 12 | 3001 King Ranch Road, Ukiah, CA 95482. */ |
| 13 | |
| 14 | #ifdef HAVE_CONFIG_H |
| 15 | # include <config.h> |
| 16 | #endif |
| 17 | |
| 18 | #include <assert.h> |
| 19 | #include <error.h> |
| 20 | #include <libintl.h> |
| 21 | #include <stdlib.h> |
| 22 | #include <string.h> |
| 23 | |
| 24 | // XXX For debugging |
| 25 | #include <stdio.h> |
| 26 | |
| 27 | #include <system.h> |
| 28 | #include "ld.h" |
| 29 | #include "list.h" |
| 30 | /* x86 is little endian. */ |
| 31 | #define UNALIGNED_ACCESS_CLASS LITTLE_ENDIAN |
| 32 | #include "unaligned.h" |
| 33 | #include "xelf.h" |
| 34 | |
| 35 | |
| 36 | /* The old callbacks. */ |
| 37 | static int (*old_open_outfile) (struct ld_state *, int, int, int); |
| 38 | |
| 39 | |
| 40 | static int |
| 41 | elf_i386_open_outfile (struct ld_state *statep, |
| 42 | int machine __attribute__ ((unused)), |
| 43 | int klass __attribute__ ((unused)), |
| 44 | int data __attribute__ ((unused))) |
| 45 | { |
| 46 | /* This backend only handles 32-bit object files. */ |
| 47 | /* XXX For now just use the generic backend. */ |
| 48 | return old_open_outfile (statep, EM_386, ELFCLASS32, ELFDATA2LSB); |
| 49 | } |
| 50 | |
| 51 | |
| 52 | /* Process relocations for the output in a relocatable file. This |
| 53 | only means adjusting offset and symbol indices. */ |
| 54 | static void |
| 55 | elf_i386_relocate_section (struct ld_state *statep __attribute__ ((unused)), |
| 56 | Elf_Scn *outscn, struct scninfo *firstp, |
| 57 | const Elf32_Word *dblindirect) |
| 58 | { |
| 59 | struct scninfo *runp; |
| 60 | Elf_Data *data; |
| 61 | |
| 62 | /* Iterate over all the input sections. Appropriate data buffers in the |
| 63 | output sections were already created. I get them iteratively, too. */ |
| 64 | runp = firstp; |
| 65 | data = NULL; |
| 66 | do |
| 67 | { |
| 68 | Elf_Data *reltgtdata; |
| 69 | Elf_Data *insymdata; |
| 70 | Elf_Data *inxndxdata = NULL; |
| 71 | size_t maxcnt; |
| 72 | size_t cnt; |
| 73 | const Elf32_Word *symindirect; |
| 74 | struct symbol **symref; |
| 75 | struct usedfiles *file = runp->fileinfo; |
| 76 | XElf_Shdr *shdr = &SCNINFO_SHDR (runp->shdr); |
| 77 | |
| 78 | /* Get the output section data buffer for this input section. */ |
| 79 | data = elf_getdata (outscn, data); |
| 80 | assert (data != NULL); |
| 81 | |
| 82 | /* Get the data for section in the input file this relocation |
| 83 | section is relocating. Since these buffers are reused in the |
| 84 | output modifying these buffers has the correct result. */ |
| 85 | reltgtdata = elf_getdata (file->scninfo[shdr->sh_info].scn, NULL); |
| 86 | |
| 87 | /* Get the data for the input section symbol table for this |
| 88 | relocation section. */ |
| 89 | insymdata = elf_getdata (file->scninfo[shdr->sh_link].scn, NULL); |
| 90 | assert (insymdata != NULL); |
| 91 | |
| 92 | /* And the extended section index table. */ |
| 93 | inxndxdata = runp->fileinfo->xndxdata; |
| 94 | |
| 95 | /* Number of relocations. */ |
| 96 | maxcnt = shdr->sh_size / shdr->sh_entsize; |
| 97 | |
| 98 | /* Array directing local symbol table offsets to output symbol |
| 99 | table offsets. */ |
| 100 | symindirect = file->symindirect; |
| 101 | |
| 102 | /* References to the symbol records. */ |
| 103 | symref = file->symref; |
| 104 | |
| 105 | /* Iterate over all the relocations in the section. */ |
| 106 | for (cnt = 0; cnt < maxcnt; ++cnt) |
| 107 | { |
| 108 | XElf_Rel_vardef (rel); |
| 109 | Elf32_Word si; |
| 110 | XElf_Sym_vardef (sym); |
| 111 | Elf32_Word xndx; |
| 112 | |
| 113 | /* Get the relocation data itself. x86 uses Rel |
| 114 | relocations. In case we have to handle Rela as well the |
| 115 | whole loop probably should be duplicated. */ |
| 116 | xelf_getrel (data, cnt, rel); |
| 117 | assert (rel != NULL); |
| 118 | |
| 119 | /* Compute the symbol index in the output file. */ |
| 120 | si = symindirect[XELF_R_SYM (rel->r_info)]; |
| 121 | if (si == 0) |
| 122 | { |
| 123 | /* This happens if the symbol is locally undefined or |
| 124 | superceded by some other definition. */ |
| 125 | assert (symref[XELF_R_SYM (rel->r_info)] != NULL); |
| 126 | si = symref[XELF_R_SYM (rel->r_info)]->outsymidx; |
| 127 | } |
| 128 | /* Take reordering performed to sort the symbol table into |
| 129 | account. */ |
| 130 | si = dblindirect[si]; |
| 131 | |
| 132 | /* Get the symbol table entry. */ |
| 133 | xelf_getsymshndx (insymdata, inxndxdata, XELF_R_SYM (rel->r_info), |
| 134 | sym, xndx); |
| 135 | if (sym->st_shndx != SHN_XINDEX) |
| 136 | xndx = sym->st_shndx; |
| 137 | assert (xndx < SHN_LORESERVE || xndx > SHN_HIRESERVE); |
| 138 | |
| 139 | /* We fortunately don't have to do much. The relocations |
| 140 | mostly get only updates of the offset. Only is a |
| 141 | relocation referred to a section do we have to do |
| 142 | something. In this case the reference to the sections |
| 143 | has no direct equivalent since the part the input section |
| 144 | contributes need not start at the same offset as in the |
| 145 | input file. Therefore we have to adjust the addend which |
| 146 | in the case of Rel relocations is in the target section |
| 147 | itself. */ |
| 148 | if (XELF_ST_TYPE (sym->st_info) == STT_SECTION) |
| 149 | { |
| 150 | Elf32_Word toadd; |
| 151 | |
| 152 | /* We expect here on R_386_32 relocations. */ |
| 153 | assert (XELF_R_TYPE (rel->r_info) == R_386_32); |
| 154 | |
| 155 | /* Avoid writing to the section memory if this is |
| 156 | effectively a no-op since it might save a |
| 157 | copy-on-write operation. */ |
| 158 | toadd = file->scninfo[xndx].offset; |
| 159 | if (toadd != 0) |
| 160 | add_4ubyte_unaligned (reltgtdata->d_buf + rel->r_offset, |
| 161 | toadd); |
| 162 | } |
| 163 | |
| 164 | /* Adjust the offset for the position of the input section |
| 165 | content in the output section. */ |
| 166 | rel->r_offset += file->scninfo[shdr->sh_info].offset; |
| 167 | |
| 168 | /* And finally adjust the index of the symbol in the output |
| 169 | symbol table. */ |
| 170 | rel->r_info = XELF_R_INFO (si, XELF_R_TYPE (rel->r_info)); |
| 171 | |
| 172 | /* Store the result. */ |
| 173 | (void) xelf_update_rel (data, cnt, rel); |
| 174 | } |
| 175 | |
| 176 | runp = runp->next; |
| 177 | } |
| 178 | while (runp != firstp); |
| 179 | } |
| 180 | |
| 181 | |
| 182 | /* Each PLT entry has 16 bytes. We need one entry as overhead for |
| 183 | the code to set up the call into the runtime relocation. */ |
| 184 | #define PLT_ENTRY_SIZE 16 |
| 185 | |
| 186 | static void |
| 187 | elf_i386_initialize_plt (struct ld_state *statep, Elf_Scn *scn) |
| 188 | { |
| 189 | Elf_Data *data; |
| 190 | XElf_Shdr_vardef (shdr); |
| 191 | |
| 192 | /* Change the entry size in the section header. */ |
| 193 | xelf_getshdr (scn, shdr); |
| 194 | assert (shdr != NULL); |
| 195 | shdr->sh_entsize = PLT_ENTRY_SIZE; |
| 196 | (void) xelf_update_shdr (scn, shdr); |
| 197 | |
| 198 | data = elf_newdata (scn); |
| 199 | if (data == NULL) |
| 200 | error (EXIT_FAILURE, 0, gettext ("cannot allocate PLT section: %s"), |
| 201 | elf_errmsg (-1)); |
| 202 | |
| 203 | /* We need one special PLT entry (performing the jump to the runtime |
| 204 | relocation routines) and one for each function we call in a DSO. */ |
| 205 | data->d_size = (1 + statep->nplt) * PLT_ENTRY_SIZE; |
| 206 | data->d_buf = xcalloc (1, data->d_size); |
| 207 | data->d_align = 8; |
| 208 | data->d_off = 0; |
| 209 | |
| 210 | statep->nplt_used = 1; |
| 211 | } |
| 212 | |
| 213 | |
| 214 | static void |
| 215 | elf_i386_initialize_pltrel (struct ld_state *statep, Elf_Scn *scn) |
| 216 | { |
| 217 | Elf_Data *data; |
| 218 | |
| 219 | data = elf_newdata (scn); |
| 220 | if (data == NULL) |
| 221 | error (EXIT_FAILURE, 0, gettext ("cannot allocate PLTREL section: %s"), |
| 222 | elf_errmsg (-1)); |
| 223 | |
| 224 | /* One relocation per PLT entry. */ |
| 225 | data->d_size = statep->nplt * sizeof (Elf32_Rel); |
| 226 | data->d_buf = xcalloc (1, data->d_size); |
| 227 | data->d_type = ELF_T_REL; |
| 228 | data->d_align = 4; |
| 229 | data->d_off = 0; |
| 230 | } |
| 231 | |
| 232 | |
| 233 | static void |
| 234 | elf_i386_initialize_got (struct ld_state *statep, Elf_Scn *scn) |
| 235 | { |
| 236 | Elf_Data *data; |
| 237 | |
| 238 | /* If we have no .plt we don't need the special entries we normally |
| 239 | create for it. The other contents is created later. */ |
| 240 | if (statep->ngot + statep->nplt == 0) |
| 241 | return; |
| 242 | |
| 243 | data = elf_newdata (scn); |
| 244 | if (data == NULL) |
| 245 | error (EXIT_FAILURE, 0, gettext ("cannot allocate GOT section: %s"), |
| 246 | elf_errmsg (-1)); |
| 247 | |
| 248 | /* We construct the .got section in pieces. Here we only add the data |
| 249 | structures which are used by the PLT. This includes three reserved |
| 250 | entries at the beginning (the first will contain a pointer to the |
| 251 | .dynamic section), and one word for each PLT entry. */ |
| 252 | data->d_size = (3 + statep->ngot + statep->nplt) * sizeof (Elf32_Addr); |
| 253 | data->d_buf = xcalloc (1, data->d_size); |
| 254 | data->d_align = sizeof (Elf32_Addr); |
| 255 | data->d_off = 0; |
| 256 | } |
| 257 | |
| 258 | |
| 259 | /* The first entry in an absolute procedure linkage table looks like |
| 260 | this. See the SVR4 ABI i386 supplement to see how this works. */ |
| 261 | static const unsigned char elf_i386_plt0_entry[PLT_ENTRY_SIZE] = |
| 262 | { |
| 263 | 0xff, 0x35, /* pushl contents of address */ |
| 264 | 0, 0, 0, 0, /* replaced with address of .got + 4. */ |
| 265 | 0xff, 0x25, /* jmp indirect */ |
| 266 | 0, 0, 0, 0, /* replaced with address of .got + 8. */ |
| 267 | 0, 0, 0, 0 /* pad out to 16 bytes. */ |
| 268 | }; |
| 269 | |
| 270 | /* Type describing the first PLT entry in non-PIC. */ |
| 271 | struct plt0_entry |
| 272 | { |
| 273 | /* First a 'push' of the second GOT entry. */ |
| 274 | unsigned char push_instr[2]; |
| 275 | uint32_t gotp4_addr; |
| 276 | /* Second, a 'jmp indirect' to the third GOT entry. */ |
| 277 | unsigned char jmp_instr[2]; |
| 278 | uint32_t gotp8_addr; |
| 279 | /* Padding. */ |
| 280 | unsigned char padding[4]; |
| 281 | } __attribute__ ((packed)); |
| 282 | |
| 283 | /* The first entry in a PIC procedure linkage table look like this. */ |
| 284 | static const unsigned char elf_i386_pic_plt0_entry[PLT_ENTRY_SIZE] = |
| 285 | { |
| 286 | 0xff, 0xb3, 4, 0, 0, 0, /* pushl 4(%ebx) */ |
| 287 | 0xff, 0xa3, 8, 0, 0, 0, /* jmp *8(%ebx) */ |
| 288 | 0, 0, 0, 0 /* pad out to 16 bytes. */ |
| 289 | }; |
| 290 | |
| 291 | /* Contents of all but the first PLT entry in executable. */ |
| 292 | static const unsigned char elf_i386_plt_entry[PLT_ENTRY_SIZE] = |
| 293 | { |
| 294 | 0xff, 0x25, /* jmp indirect */ |
| 295 | 0, 0, 0, 0, /* replaced with address of this symbol in .got. */ |
| 296 | 0x68, /* pushl immediate */ |
| 297 | 0, 0, 0, 0, /* replaced with offset into relocation table. */ |
| 298 | 0xe9, /* jmp relative */ |
| 299 | 0, 0, 0, 0 /* replaced with offset to start of .plt. */ |
| 300 | }; |
| 301 | |
| 302 | /* Contents of all but the first PLT entry in DSOs. */ |
| 303 | static const unsigned char elf_i386_pic_plt_entry[PLT_ENTRY_SIZE] = |
| 304 | { |
| 305 | 0xff, 0xa3, /* jmp *offset(%ebx) */ |
| 306 | 0, 0, 0, 0, /* replaced with offset of this symbol in .got. */ |
| 307 | 0x68, /* pushl immediate */ |
| 308 | 0, 0, 0, 0, /* replaced with offset into relocation table. */ |
| 309 | 0xe9, /* jmp relative */ |
| 310 | 0, 0, 0, 0 /* replaced with offset to start of .plt. */ |
| 311 | }; |
| 312 | |
| 313 | /* Type describing a PLT entry. */ |
| 314 | struct plt_entry |
| 315 | { |
| 316 | /* The first instruction is 'jmp indirect' or 'jmp *offset(%ebs)'. */ |
| 317 | unsigned char jmp_instr[2]; |
| 318 | uint32_t offset_got; |
| 319 | /* The second instruction is 'push immediate'. */ |
| 320 | unsigned char push_instr; |
| 321 | uint32_t push_imm; |
| 322 | /* Finally a 'jmp relative'. */ |
| 323 | unsigned char jmp_instr2; |
| 324 | uint32_t plt0_offset; |
| 325 | } __attribute__ ((packed)); |
| 326 | |
| 327 | |
| 328 | static void |
| 329 | elf_i386_finalize_plt (struct ld_state *statep, size_t nsym, |
| 330 | size_t nsym_dyn __attribute__ ((unused))) |
| 331 | { |
| 332 | Elf_Scn *scn; |
| 333 | XElf_Shdr_vardef (shdr); |
| 334 | Elf_Data *data; |
| 335 | Elf_Data *symdata = NULL; |
| 336 | Elf_Data *dynsymdata; |
| 337 | size_t cnt; |
| 338 | const bool build_dso = statep->file_type == dso_file_type; |
| 339 | |
| 340 | if (unlikely (statep->nplt + statep->ngot == 0)) |
| 341 | /* Nothing to be done. */ |
| 342 | return; |
| 343 | |
| 344 | /* Get the address of the got section. */ |
| 345 | scn = elf_getscn (statep->outelf, statep->gotscnidx); |
| 346 | xelf_getshdr (scn, shdr); |
| 347 | data = elf_getdata (scn, NULL); |
| 348 | assert (shdr != NULL && data != NULL); |
| 349 | Elf32_Addr gotaddr = shdr->sh_addr; |
| 350 | |
| 351 | /* Now create the initial values for the .got section. The first |
| 352 | word contains the address of the .dynamic section. */ |
| 353 | xelf_getshdr (elf_getscn (statep->outelf, statep->dynamicscnidx), shdr); |
| 354 | assert (shdr != NULL); |
| 355 | ((Elf32_Word *) data->d_buf)[0] = shdr->sh_addr; |
| 356 | |
| 357 | /* The second and third entry are left empty for use by the dynamic |
| 358 | linker. The following entries are pointers to the instructions |
| 359 | following the initial jmp instruction in the corresponding PLT |
| 360 | entry. Since the first PLT entry is special the first used one |
| 361 | has the index 1. */ |
| 362 | scn = elf_getscn (statep->outelf, statep->pltscnidx); |
| 363 | xelf_getshdr (scn, shdr); |
| 364 | assert (shdr != NULL); |
| 365 | |
| 366 | dynsymdata = elf_getdata (elf_getscn (statep->outelf, statep->dynsymscnidx), |
| 367 | NULL); |
| 368 | assert (dynsymdata != NULL); |
| 369 | |
| 370 | if (statep->symscnidx != 0) |
| 371 | { |
| 372 | symdata = elf_getdata (elf_getscn (statep->outelf, statep->symscnidx), |
| 373 | NULL); |
| 374 | assert (symdata != NULL); |
| 375 | } |
| 376 | |
| 377 | for (cnt = 0; cnt < statep->nplt; ++cnt) |
| 378 | { |
| 379 | assert ((4 + cnt) * sizeof (Elf32_Word) <= data->d_size); |
| 380 | |
| 381 | /* Address in the PLT. */ |
| 382 | Elf32_Addr pltentryaddr = shdr->sh_addr + (1 + cnt) * PLT_ENTRY_SIZE; |
| 383 | |
| 384 | /* Point the GOT entry at the PLT entry, after the initial jmp. */ |
| 385 | ((Elf32_Word *) data->d_buf)[3 + cnt] = pltentryaddr + 6; |
| 386 | |
| 387 | /* The value of the symbol is the address of the corresponding PLT |
| 388 | entry. Store the address, also for the normal symbol table if |
| 389 | this is necessary. */ |
| 390 | ((Elf32_Sym *) dynsymdata->d_buf)[1 + cnt].st_value = pltentryaddr; |
| 391 | |
| 392 | if (symdata != NULL) |
| 393 | ((Elf32_Sym *) symdata->d_buf)[nsym - statep->nplt + cnt].st_value |
| 394 | = pltentryaddr; |
| 395 | } |
| 396 | |
| 397 | /* Create the .plt section. */ |
| 398 | scn = elf_getscn (statep->outelf, statep->pltscnidx); |
| 399 | data = elf_getdata (scn, NULL); |
| 400 | assert (data != NULL); |
| 401 | |
| 402 | /* Create the first entry. */ |
| 403 | assert (data->d_size >= PLT_ENTRY_SIZE); |
| 404 | if (build_dso) |
| 405 | /* Copy the entry. It's complete, no relocation needed. */ |
| 406 | memcpy (data->d_buf, elf_i386_pic_plt0_entry, PLT_ENTRY_SIZE); |
| 407 | else |
| 408 | { |
| 409 | /* Copy the skeleton. */ |
| 410 | memcpy (data->d_buf, elf_i386_plt0_entry, PLT_ENTRY_SIZE); |
| 411 | |
| 412 | /* And fill in the addresses. */ |
| 413 | struct plt0_entry *addr = (struct plt0_entry *) data->d_buf; |
| 414 | addr->gotp4_addr = target_bswap_32 (gotaddr + 4); |
| 415 | addr->gotp8_addr = target_bswap_32 (gotaddr + 8); |
| 416 | } |
| 417 | |
| 418 | /* For DSOs we need GOT offsets, otherwise the GOT address. */ |
| 419 | Elf32_Addr gotaddr_off = build_dso ? 0 : gotaddr; |
| 420 | |
| 421 | /* Create the remaining entries. */ |
| 422 | const unsigned char *plt_template |
| 423 | = build_dso ? elf_i386_pic_plt_entry : elf_i386_plt_entry; |
| 424 | |
| 425 | for (cnt = 0; cnt < statep->nplt; ++cnt) |
| 426 | { |
| 427 | struct plt_entry *addr; |
| 428 | |
| 429 | /* Copy the template. */ |
| 430 | assert (data->d_size >= (2 + cnt) * PLT_ENTRY_SIZE); |
| 431 | addr = (struct plt_entry *) ((char *) data->d_buf |
| 432 | + (1 + cnt) * PLT_ENTRY_SIZE); |
| 433 | memcpy (addr, plt_template, PLT_ENTRY_SIZE); |
| 434 | |
| 435 | /* And once more, fill in the addresses. First the address of |
| 436 | this symbol in .got. */ |
| 437 | addr->offset_got = target_bswap_32 (gotaddr_off |
| 438 | + (3 + cnt) * sizeof (Elf32_Addr)); |
| 439 | /* Offset into relocation table. */ |
| 440 | addr->push_imm = target_bswap_32 (cnt * sizeof (Elf32_Rel)); |
| 441 | /* Offset to start of .plt. */ |
| 442 | addr->plt0_offset = target_bswap_32 (-(2 + cnt) * PLT_ENTRY_SIZE); |
| 443 | } |
| 444 | |
| 445 | /* Create the .rel.plt section data. It simply means relocations |
| 446 | addressing the corresponding entry in the .got section. The |
| 447 | section name is misleading. */ |
| 448 | scn = elf_getscn (statep->outelf, statep->pltrelscnidx); |
| 449 | xelf_getshdr (scn, shdr); |
| 450 | data = elf_getdata (scn, NULL); |
| 451 | assert (shdr != NULL && data != NULL); |
| 452 | |
| 453 | /* Update the sh_link to point to the section being modified. We |
| 454 | point it here (correctly) to the .got section. Some linkers |
| 455 | (e.g., the GNU binutils linker) point to the .plt section. This |
| 456 | is wrong since the .plt section isn't modified even though the |
| 457 | name .rel.plt suggests that this is correct. */ |
| 458 | shdr->sh_link = statep->dynsymscnidx; |
| 459 | shdr->sh_info = statep->gotscnidx; |
| 460 | (void) xelf_update_shdr (scn, shdr); |
| 461 | |
| 462 | for (cnt = 0; cnt < statep->nplt; ++cnt) |
| 463 | { |
| 464 | XElf_Rel_vardef (rel); |
| 465 | |
| 466 | assert ((1 + cnt) * sizeof (Elf32_Rel) <= data->d_size); |
| 467 | xelf_getrel_ptr (data, cnt, rel); |
| 468 | rel->r_offset = gotaddr + (3 + cnt) * sizeof (Elf32_Addr); |
| 469 | /* The symbol table entries for the functions from DSOs are at |
| 470 | the end of the symbol table. */ |
| 471 | rel->r_info = XELF_R_INFO (1 + cnt, R_386_JMP_SLOT); |
| 472 | (void) xelf_update_rel (data, cnt, rel); |
| 473 | } |
| 474 | } |
| 475 | |
| 476 | |
| 477 | static int |
| 478 | elf_i386_rel_type (struct ld_state *statep __attribute__ ((__unused__))) |
| 479 | { |
| 480 | /* ELF/i386 uses REL. */ |
| 481 | return DT_REL; |
| 482 | } |
| 483 | |
| 484 | |
| 485 | static void |
| 486 | elf_i386_count_relocations (struct ld_state *statep, struct scninfo *scninfo) |
| 487 | { |
| 488 | /* We go through the list of input sections and count those relocations |
| 489 | which are not handled by the linker. At the same time we have to |
| 490 | see how many GOT entries we need and how much .bss space is needed |
| 491 | for copy relocations. */ |
| 492 | Elf_Data *data = elf_getdata (scninfo->scn, NULL); |
| 493 | XElf_Shdr *shdr = &SCNINFO_SHDR (scninfo->shdr); |
| 494 | size_t maxcnt = shdr->sh_size / shdr->sh_entsize; |
| 495 | size_t relsize = 0; |
| 496 | size_t cnt; |
| 497 | struct symbol *sym; |
| 498 | |
| 499 | assert (shdr->sh_type == SHT_REL); |
| 500 | |
| 501 | for (cnt = 0; cnt < maxcnt; ++cnt) |
| 502 | { |
| 503 | XElf_Rel_vardef (rel); |
| 504 | |
| 505 | xelf_getrel (data, cnt, rel); |
| 506 | /* XXX Should we complain about failing accesses? */ |
| 507 | if (rel != NULL) |
| 508 | { |
| 509 | Elf32_Word r_sym = XELF_R_SYM (rel->r_info); |
| 510 | |
| 511 | switch (XELF_R_TYPE (rel->r_info)) |
| 512 | { |
| 513 | case R_386_GOT32: |
| 514 | if (! scninfo->fileinfo->symref[r_sym]->defined) |
| 515 | relsize += sizeof (Elf32_Rel); |
| 516 | |
| 517 | /* This relocation is not emitted in the output file but |
| 518 | requires a GOT entry. */ |
| 519 | ++statep->ngot; |
| 520 | ++statep->nrel_got; |
| 521 | |
| 522 | /* FALLTHROUGH */ |
| 523 | |
| 524 | case R_386_GOTOFF: |
| 525 | case R_386_GOTPC: |
| 526 | statep->need_got = true; |
| 527 | break; |
| 528 | |
| 529 | case R_386_32: |
| 530 | case R_386_PC32: |
| 531 | /* These relocations cause text relocations in DSOs. */ |
| 532 | if (linked_from_dso_p (scninfo, r_sym)) |
| 533 | { |
| 534 | if (statep->file_type == dso_file_type) |
| 535 | { |
| 536 | relsize += sizeof (Elf32_Rel); |
| 537 | statep->dt_flags |= DF_TEXTREL; |
| 538 | } |
| 539 | else |
| 540 | { |
| 541 | /* Non-function objects from a DSO need to get a |
| 542 | copy relocation. */ |
| 543 | sym = scninfo->fileinfo->symref[r_sym]; |
| 544 | |
| 545 | /* Only do this if we have not requested a copy |
| 546 | relocation already. */ |
| 547 | if (unlikely (sym->type != STT_FUNC) && ! sym->need_copy) |
| 548 | { |
| 549 | sym->need_copy = 1; |
| 550 | ++statep->ncopy; |
| 551 | relsize += sizeof (Elf32_Rel); |
| 552 | } |
| 553 | } |
| 554 | } |
| 555 | else if (statep->file_type == dso_file_type |
| 556 | && r_sym >= SCNINFO_SHDR (scninfo->fileinfo->scninfo[shdr->sh_link].shdr).sh_info |
| 557 | && scninfo->fileinfo->symref[r_sym]->outdynsymidx != 0 |
| 558 | && XELF_R_TYPE (rel->r_info) == R_386_32) |
| 559 | relsize += sizeof (Elf32_Rel); |
| 560 | break; |
| 561 | |
| 562 | case R_386_PLT32: |
| 563 | /* We might need a PLT entry. But we cannot say for sure |
| 564 | here since one of the symbols might turn up being |
| 565 | defined in the executable (if we create such a thing). |
| 566 | If a DSO is created we still might use a local |
| 567 | definition. |
| 568 | |
| 569 | If the symbol is not defined and we are not creating |
| 570 | a statically linked binary, then we need in any case |
| 571 | a PLT entry. */ |
| 572 | if (! scninfo->fileinfo->symref[r_sym]->defined) |
| 573 | { |
| 574 | assert (!statep->statically); |
| 575 | |
| 576 | sym = scninfo->fileinfo->symref[r_sym]; |
| 577 | sym->type = STT_FUNC; |
| 578 | sym->in_dso = 1; |
| 579 | sym->defined = 1; |
| 580 | |
| 581 | /* Remove from the list of unresolved symbols. */ |
| 582 | --statep->nunresolved; |
| 583 | if (! sym->weak) |
| 584 | --statep->nunresolved_nonweak; |
| 585 | CDBL_LIST_DEL (statep->unresolved, sym); |
| 586 | |
| 587 | /* Add to the list of symbols we expect from a DSO. */ |
| 588 | ++statep->nplt; |
| 589 | ++statep->nfrom_dso; |
| 590 | CDBL_LIST_ADD_REAR (statep->from_dso, sym); |
| 591 | } |
| 592 | break; |
| 593 | |
| 594 | case R_386_TLS_GD: |
| 595 | case R_386_TLS_LDM: |
| 596 | case R_386_TLS_GD_32: |
| 597 | case R_386_TLS_GD_PUSH: |
| 598 | case R_386_TLS_GD_CALL: |
| 599 | case R_386_TLS_GD_POP: |
| 600 | case R_386_TLS_LDM_32: |
| 601 | case R_386_TLS_LDM_PUSH: |
| 602 | case R_386_TLS_LDM_CALL: |
| 603 | case R_386_TLS_LDM_POP: |
| 604 | case R_386_TLS_LDO_32: |
| 605 | case R_386_TLS_IE_32: |
| 606 | case R_386_TLS_LE_32: |
| 607 | /* XXX */ |
| 608 | abort (); |
| 609 | break; |
| 610 | |
| 611 | case R_386_NONE: |
| 612 | /* Nothing to be done. */ |
| 613 | break; |
| 614 | |
| 615 | /* These relocation should never be generated by an |
| 616 | assembler. */ |
| 617 | case R_386_COPY: |
| 618 | case R_386_GLOB_DAT: |
| 619 | case R_386_JMP_SLOT: |
| 620 | case R_386_RELATIVE: |
| 621 | case R_386_TLS_DTPMOD32: |
| 622 | case R_386_TLS_DTPOFF32: |
| 623 | case R_386_TLS_TPOFF32: |
| 624 | /* Unknown relocation. */ |
| 625 | default: |
| 626 | abort (); |
| 627 | } |
| 628 | } |
| 629 | } |
| 630 | |
| 631 | scninfo->relsize = relsize; |
| 632 | } |
| 633 | |
| 634 | |
| 635 | static void |
| 636 | elf_i386_create_relocations (struct ld_state *statep, |
| 637 | const Elf32_Word *dblindirect __attribute__ ((unused))) |
| 638 | { |
| 639 | /* Get the address of the got section. */ |
| 640 | Elf_Scn *pltscn = elf_getscn (statep->outelf, statep->pltscnidx); |
| 641 | Elf32_Shdr *shdr = elf32_getshdr (pltscn); |
| 642 | assert (shdr != NULL); |
| 643 | Elf32_Addr pltaddr = shdr->sh_addr; |
| 644 | |
| 645 | Elf_Scn *gotscn = elf_getscn (statep->outelf, statep->gotscnidx); |
| 646 | shdr = elf32_getshdr (gotscn); |
| 647 | assert (shdr != NULL); |
| 648 | Elf32_Addr gotaddr = shdr->sh_addr; |
| 649 | |
| 650 | Elf_Scn *reldynscn = elf_getscn (statep->outelf, statep->reldynscnidx); |
| 651 | Elf_Data *reldyndata = elf_getdata (reldynscn, NULL); |
| 652 | |
| 653 | size_t nreldyn = 0; |
| 654 | #define ngot_used (3 + statep->nplt + nreldyn) |
| 655 | |
| 656 | struct scninfo *first = statep->rellist->next; |
| 657 | struct scninfo *runp = first; |
| 658 | do |
| 659 | { |
| 660 | XElf_Shdr *rshdr = &SCNINFO_SHDR (runp->shdr); |
| 661 | Elf_Data *reldata = elf_getdata (runp->scn, NULL); |
| 662 | int nrels = rshdr->sh_size / rshdr->sh_entsize; |
| 663 | |
| 664 | /* We will need the following vlaues a couple of times. Help |
| 665 | the compiler and improve readability. */ |
| 666 | struct symbol **symref = runp->fileinfo->symref; |
| 667 | struct scninfo *scninfo = runp->fileinfo->scninfo; |
| 668 | |
| 669 | /* This is the offset of the input section we are looking at in |
| 670 | the output file. */ |
| 671 | XElf_Addr inscnoffset = scninfo[rshdr->sh_info].offset; |
| 672 | |
| 673 | /* The target section. We use the data from the input file. */ |
| 674 | Elf_Data *data = elf_getdata (scninfo[rshdr->sh_info].scn, NULL); |
| 675 | |
| 676 | /* We cannot handle relocations against merge-able sections. */ |
| 677 | assert ((SCNINFO_SHDR (scninfo[rshdr->sh_link].shdr).sh_flags |
| 678 | & SHF_MERGE) == 0); |
| 679 | |
| 680 | /* Cache the access to the symbol table data. */ |
| 681 | Elf_Data *symdata = elf_getdata (scninfo[rshdr->sh_link].scn, NULL); |
| 682 | |
| 683 | int cnt; |
| 684 | for (cnt = 0; cnt < nrels; ++cnt) |
| 685 | { |
| 686 | XElf_Rel_vardef (rel); |
| 687 | XElf_Rel *rel2; |
| 688 | xelf_getrel (reldata, cnt, rel); |
| 689 | assert (rel != NULL); |
| 690 | XElf_Addr reladdr = inscnoffset + rel->r_offset; |
| 691 | XElf_Addr value; |
| 692 | |
| 693 | size_t idx = XELF_R_SYM (rel->r_info); |
| 694 | if (idx < runp->fileinfo->nlocalsymbols) |
| 695 | { |
| 696 | XElf_Sym_vardef (sym); |
| 697 | xelf_getsym (symdata, idx, sym); |
| 698 | |
| 699 | /* The value just depends on the position of the referenced |
| 700 | section in the output file and the addend. */ |
| 701 | value = scninfo[sym->st_shndx].offset + sym->st_value; |
| 702 | } |
| 703 | else if (symref[idx]->in_dso) |
| 704 | { |
| 705 | /* MERGE.VALUE contains the PLT index. We have to add 1 since |
| 706 | there is this one special PLT entry at the beginning. */ |
| 707 | assert (symref[idx]->merge.value != 0 |
| 708 | || symref[idx]->type != STT_FUNC); |
| 709 | value = pltaddr + symref[idx]->merge.value * PLT_ENTRY_SIZE; |
| 710 | } |
| 711 | else |
| 712 | value = symref[idx]->merge.value; |
| 713 | |
| 714 | /* Address of the relocated memory in the data buffer. */ |
| 715 | void *relloc = (char *) data->d_buf + rel->r_offset; |
| 716 | |
| 717 | switch (XELF_R_TYPE (rel->r_info)) |
| 718 | { |
| 719 | /* These three cases can be handled together since the |
| 720 | symbol associated with the R_386_GOTPC relocation is |
| 721 | _GLOBAL_OFFSET_TABLE_ which has a value corresponding |
| 722 | to the address of the GOT and the address of the PLT |
| 723 | entry required for R_386_PLT32 is computed above. */ |
| 724 | case R_386_PC32: |
| 725 | case R_386_GOTPC: |
| 726 | case R_386_PLT32: |
| 727 | value -= reladdr; |
| 728 | /* FALLTHROUGH */ |
| 729 | |
| 730 | case R_386_32: |
| 731 | if (linked_from_dso_p (scninfo, idx) |
| 732 | && statep->file_type != dso_file_type |
| 733 | && symref[idx]->type != STT_FUNC) |
| 734 | { |
| 735 | value = (ld_state.copy_section->offset |
| 736 | + symref[idx]->merge.value); |
| 737 | |
| 738 | if (unlikely (symref[idx]->need_copy)) |
| 739 | { |
| 740 | /* Add a relocation to initialize the GOT entry. */ |
| 741 | assert (symref[idx]->outdynsymidx != 0); |
| 742 | #if NATIVE_ELF != 0 |
| 743 | xelf_getrel_ptr (reldyndata, nreldyn, rel2); |
| 744 | #else |
| 745 | rel2 = &rel_mem; |
| 746 | #endif |
| 747 | rel2->r_offset = value; |
| 748 | rel2->r_info |
| 749 | = XELF_R_INFO (symref[idx]->outdynsymidx, R_386_COPY); |
| 750 | (void) xelf_update_rel (reldyndata, nreldyn, rel2); |
| 751 | ++nreldyn; |
| 752 | |
| 753 | /* Update the symbol table record for the new |
| 754 | address. */ |
| 755 | Elf32_Word symidx = symref[idx]->outdynsymidx; |
| 756 | Elf_Scn *symscn = elf_getscn (statep->outelf, |
| 757 | statep->dynsymscnidx); |
| 758 | Elf_Data *outsymdata = elf_getdata (symscn, NULL); |
| 759 | assert (outsymdata != NULL); |
| 760 | XElf_Sym_vardef (sym); |
| 761 | xelf_getsym (outsymdata, symidx, sym); |
| 762 | sym->st_value = value; |
| 763 | sym->st_shndx = statep->copy_section->outscnndx; |
| 764 | (void) xelf_update_sym (outsymdata, symidx, sym); |
| 765 | |
| 766 | symidx = symref[idx]->outsymidx; |
| 767 | if (symidx != 0) |
| 768 | { |
| 769 | symidx = statep->dblindirect[symidx]; |
| 770 | symscn = elf_getscn (statep->outelf, |
| 771 | statep->symscnidx); |
| 772 | outsymdata = elf_getdata (symscn, NULL); |
| 773 | assert (outsymdata != NULL); |
| 774 | xelf_getsym (outsymdata, symidx, sym); |
| 775 | sym->st_value = value; |
| 776 | sym->st_shndx = statep->copy_section->outscnndx; |
| 777 | (void) xelf_update_sym (outsymdata, symidx, sym); |
| 778 | } |
| 779 | |
| 780 | /* Remember that we set up the copy relocation. */ |
| 781 | symref[idx]->need_copy = 0; |
| 782 | } |
| 783 | } |
| 784 | else if (statep->file_type == dso_file_type |
| 785 | && idx >= SCNINFO_SHDR (scninfo[rshdr->sh_link].shdr).sh_info |
| 786 | && symref[idx]->outdynsymidx != 0) |
| 787 | { |
| 788 | #if NATIVE_ELF != 0 |
| 789 | xelf_getrel_ptr (reldyndata, nreldyn, rel2); |
| 790 | #else |
| 791 | rel2 = &rel_mem; |
| 792 | #endif |
| 793 | rel2->r_offset = value; |
| 794 | rel2->r_info |
| 795 | = XELF_R_INFO (symref[idx]->outdynsymidx, R_386_32); |
| 796 | (void) xelf_update_rel (reldyndata, nreldyn, rel2); |
| 797 | ++nreldyn; |
| 798 | |
| 799 | value = 0; |
| 800 | } |
| 801 | add_4ubyte_unaligned (relloc, value); |
| 802 | break; |
| 803 | |
| 804 | case R_386_GOT32: |
| 805 | store_4ubyte_unaligned (relloc, ngot_used * sizeof (Elf32_Addr)); |
| 806 | |
| 807 | /* Add a relocation to initialize the GOT entry. */ |
| 808 | #if NATIVE_ELF != 0 |
| 809 | xelf_getrel_ptr (reldyndata, nreldyn, rel2); |
| 810 | #else |
| 811 | rel2 = &rel_mem; |
| 812 | #endif |
| 813 | rel2->r_offset = gotaddr + ngot_used * sizeof (Elf32_Addr); |
| 814 | rel2->r_info |
| 815 | = XELF_R_INFO (symref[idx]->outdynsymidx, R_386_GLOB_DAT); |
| 816 | (void) xelf_update_rel (reldyndata, nreldyn, rel2); |
| 817 | ++nreldyn; |
| 818 | break; |
| 819 | |
| 820 | case R_386_GOTOFF: |
| 821 | add_4ubyte_unaligned (relloc, value - gotaddr); |
| 822 | break; |
| 823 | |
| 824 | case R_386_32PLT: |
| 825 | case R_386_TLS_TPOFF: |
| 826 | case R_386_TLS_IE: |
| 827 | case R_386_TLS_GOTIE: |
| 828 | case R_386_TLS_LE: |
| 829 | case R_386_TLS_GD: |
| 830 | case R_386_TLS_LDM: |
| 831 | case R_386_16: |
| 832 | case R_386_PC16: |
| 833 | case R_386_8: |
| 834 | case R_386_PC8: |
| 835 | case R_386_TLS_GD_32: |
| 836 | case R_386_TLS_GD_PUSH: |
| 837 | case R_386_TLS_GD_CALL: |
| 838 | case R_386_TLS_GD_POP: |
| 839 | case R_386_TLS_LDM_32: |
| 840 | case R_386_TLS_LDM_PUSH: |
| 841 | case R_386_TLS_LDM_CALL: |
| 842 | case R_386_TLS_LDM_POP: |
| 843 | case R_386_TLS_LDO_32: |
| 844 | case R_386_TLS_IE_32: |
| 845 | case R_386_TLS_LE_32: |
| 846 | // XXX For now fall through |
| 847 | printf("ignored relocation %d\n", (int) XELF_R_TYPE (rel->r_info)); |
| 848 | break; |
| 849 | |
| 850 | case R_386_NONE: |
| 851 | /* Nothing to do. */ |
| 852 | break; |
| 853 | |
| 854 | case R_386_COPY: |
| 855 | case R_386_JMP_SLOT: |
| 856 | case R_386_RELATIVE: |
| 857 | case R_386_GLOB_DAT: |
| 858 | case R_386_TLS_DTPMOD32: |
| 859 | case R_386_TLS_DTPOFF32: |
| 860 | case R_386_TLS_TPOFF32: |
| 861 | default: |
| 862 | /* Should not happen. */ |
| 863 | abort (); |
| 864 | } |
| 865 | } |
| 866 | } |
| 867 | while ((runp = runp->next) != first); |
| 868 | } |
| 869 | |
| 870 | |
| 871 | int |
| 872 | elf_i386_ld_init (struct ld_state *statep) |
| 873 | { |
| 874 | /* We have a few callbacks available. */ |
| 875 | old_open_outfile = statep->callbacks.open_outfile; |
| 876 | statep->callbacks.open_outfile = elf_i386_open_outfile; |
| 877 | |
| 878 | statep->callbacks.relocate_section = elf_i386_relocate_section; |
| 879 | |
| 880 | statep->callbacks.initialize_plt = elf_i386_initialize_plt; |
| 881 | statep->callbacks.initialize_pltrel = elf_i386_initialize_pltrel; |
| 882 | |
| 883 | statep->callbacks.initialize_got = elf_i386_initialize_got; |
| 884 | |
| 885 | statep->callbacks.finalize_plt = elf_i386_finalize_plt; |
| 886 | |
| 887 | statep->callbacks.rel_type = elf_i386_rel_type; |
| 888 | |
| 889 | statep->callbacks.count_relocations = elf_i386_count_relocations; |
| 890 | |
| 891 | statep->callbacks.create_relocations = elf_i386_create_relocations; |
| 892 | |
| 893 | return 0; |
| 894 | } |