reloc.c revision 1.47
1 /* $NetBSD: reloc.c,v 1.47 2001/12/20 02:23:24 thorpej Exp $ */ 2 3 /* 4 * Copyright 1996 John D. Polstra. 5 * Copyright 1996 Matt Thomas <matt (at) 3am-software.com> 6 * All rights reserved. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 3. All advertising materials mentioning features or use of this software 17 * must display the following acknowledgement: 18 * This product includes software developed by John Polstra. 19 * 4. The name of the author may not be used to endorse or promote products 20 * derived from this software without specific prior written permission. 21 * 22 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 23 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 24 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 25 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 26 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 27 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 28 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 29 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 30 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 31 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 32 */ 33 34 /* 35 * Dynamic linker for ELF. 36 * 37 * John Polstra <jdp (at) polstra.com>. 38 */ 39 40 #include <err.h> 41 #include <errno.h> 42 #include <fcntl.h> 43 #include <stdarg.h> 44 #include <stdio.h> 45 #include <stdlib.h> 46 #include <string.h> 47 #include <unistd.h> 48 #include <sys/types.h> 49 #include <sys/mman.h> 50 #include <dirent.h> 51 52 #include "debug.h" 53 #include "rtld.h" 54 55 #ifndef RTLD_INHIBIT_COPY_RELOCS 56 static int _rtld_do_copy_relocation __P((const Obj_Entry *, const Elf_Rela *, 57 bool)); 58 59 /* 60 * XXX: These don't work for the alpha and i386; don't know about powerpc 61 * The alpha and the i386 avoid the problem by compiling everything PIC. 62 * These relocation are supposed to be writing the address of the 63 * function to be called on the bss.rel or bss.rela segment, but: 64 * - st_size == 0 65 * - on the i386 at least the call instruction is a direct call 66 * not an indirect call. 67 */ 68 static int 69 _rtld_do_copy_relocation(dstobj, rela, dodebug) 70 const Obj_Entry *dstobj; 71 const Elf_Rela *rela; 72 bool dodebug; 73 { 74 void *dstaddr = (void *)(dstobj->relocbase + rela->r_offset); 75 const Elf_Sym *dstsym = dstobj->symtab + ELF_R_SYM(rela->r_info); 76 const char *name = dstobj->strtab + dstsym->st_name; 77 unsigned long hash = _rtld_elf_hash(name); 78 size_t size = dstsym->st_size; 79 const void *srcaddr; 80 const Elf_Sym *srcsym = NULL; 81 Obj_Entry *srcobj; 82 83 for (srcobj = dstobj->next; srcobj != NULL; srcobj = srcobj->next) 84 if ((srcsym = _rtld_symlook_obj(name, hash, srcobj, 85 false)) != NULL) 86 break; 87 88 if (srcobj == NULL) { 89 _rtld_error("Undefined symbol \"%s\" referenced from COPY" 90 " relocation in %s", name, dstobj->path); 91 return (-1); 92 } 93 srcaddr = (const void *)(srcobj->relocbase + srcsym->st_value); 94 (void)memcpy(dstaddr, srcaddr, size); 95 rdbg(dodebug, ("COPY %s %s %s --> src=%p dst=%p *dst= %p size %ld", 96 dstobj->path, srcobj->path, name, (void *)srcaddr, 97 (void *)dstaddr, (void *)*(long *)dstaddr, (long)size)); 98 return (0); 99 } 100 #endif /* RTLD_INHIBIT_COPY_RELOCS */ 101 102 103 /* 104 * Process the special R_xxx_COPY relocations in the main program. These 105 * copy data from a shared object into a region in the main program's BSS 106 * segment. 107 * 108 * Returns 0 on success, -1 on failure. 109 */ 110 int 111 _rtld_do_copy_relocations(dstobj, dodebug) 112 const Obj_Entry *dstobj; 113 bool dodebug; 114 { 115 #ifndef RTLD_INHIBIT_COPY_RELOCS 116 117 /* COPY relocations are invalid elsewhere */ 118 assert(dstobj->mainprog); 119 120 if (dstobj->rel != NULL) { 121 const Elf_Rel *rel; 122 for (rel = dstobj->rel; rel < dstobj->rellim; ++rel) { 123 if (ELF_R_TYPE(rel->r_info) == R_TYPE(COPY)) { 124 Elf_Rela ourrela; 125 ourrela.r_info = rel->r_info; 126 ourrela.r_offset = rel->r_offset; 127 ourrela.r_addend = 0; 128 if (_rtld_do_copy_relocation(dstobj, 129 &ourrela, dodebug) < 0) 130 return (-1); 131 } 132 } 133 } 134 if (dstobj->rela != NULL) { 135 const Elf_Rela *rela; 136 for (rela = dstobj->rela; rela < dstobj->relalim; ++rela) { 137 if (ELF_R_TYPE(rela->r_info) == R_TYPE(COPY)) { 138 if (_rtld_do_copy_relocation(dstobj, rela, 139 dodebug) < 0) 140 return (-1); 141 } 142 } 143 } 144 #endif /* RTLD_INHIBIT_COPY_RELOCS */ 145 146 return (0); 147 } 148 149 150 #if !defined(__sparc__) && !defined(__x86_64__) 151 152 int 153 _rtld_relocate_nonplt_object(obj, rela, dodebug) 154 Obj_Entry *obj; 155 const Elf_Rela *rela; 156 bool dodebug; 157 { 158 Elf_Addr *where = (Elf_Addr *)(obj->relocbase + rela->r_offset); 159 const Elf_Sym *def; 160 const Obj_Entry *defobj; 161 #if defined(__alpha__) || defined(__arm__) || defined(__i386__) || \ 162 defined(__m68k__) || defined(__powerpc__) || defined(__vax__) 163 Elf_Addr tmp; 164 #endif 165 166 switch (ELF_R_TYPE(rela->r_info)) { 167 168 case R_TYPE(NONE): 169 break; 170 171 #if defined(__i386__) 172 case R_TYPE(GOT32): 173 174 def = _rtld_find_symdef(_rtld_objlist, rela->r_info, NULL, obj, 175 &defobj, false); 176 if (def == NULL) 177 return -1; 178 179 tmp = (Elf_Addr)(defobj->relocbase + def->st_value); 180 if (*where != tmp) 181 *where = tmp; 182 rdbg(dodebug, ("GOT32 %s in %s --> %p in %s", 183 defobj->strtab + def->st_name, obj->path, 184 (void *)*where, defobj->path)); 185 break; 186 187 case R_TYPE(PC32): 188 /* 189 * I don't think the dynamic linker should ever see this 190 * type of relocation. But the binutils-2.6 tools sometimes 191 * generate it. 192 */ 193 194 def = _rtld_find_symdef(_rtld_objlist, rela->r_info, NULL, obj, 195 &defobj, false); 196 if (def == NULL) 197 return -1; 198 199 *where += (Elf_Addr)(defobj->relocbase + def->st_value) - 200 (Elf_Addr)where; 201 rdbg(dodebug, ("PC32 %s in %s --> %p in %s", 202 defobj->strtab + def->st_name, obj->path, 203 (void *)*where, defobj->path)); 204 break; 205 206 case R_TYPE(32): 207 def = _rtld_find_symdef(_rtld_objlist, rela->r_info, NULL, obj, 208 &defobj, false); 209 if (def == NULL) 210 return -1; 211 212 *where += (Elf_Addr)(defobj->relocbase + def->st_value); 213 rdbg(dodebug, ("32 %s in %s --> %p in %s", 214 defobj->strtab + def->st_name, obj->path, 215 (void *)*where, defobj->path)); 216 break; 217 #endif /* __i386__ */ 218 219 #if defined(__m68k__) 220 case R_TYPE(GOT32): 221 def = _rtld_find_symdef(_rtld_objlist, rela->r_info, NULL, obj, 222 &defobj, false); 223 if (def == NULL) 224 return -1; 225 226 tmp = (Elf_Addr)(defobj->relocbase + def->st_value + 227 rela->r_addend); 228 if (*where != tmp) 229 *where = tmp; 230 rdbg(dodebug, ("GOT32 %s in %s --> %p in %s", 231 defobj->strtab + def->st_name, obj->path, 232 (void *)*where, defobj->path)); 233 break; 234 235 case R_TYPE(PC32): 236 def = _rtld_find_symdef(_rtld_objlist, rela->r_info, NULL, obj, 237 &defobj, false); 238 if (def == NULL) 239 return -1; 240 241 tmp = (Elf_Addr)(defobj->relocbase + def->st_value + 242 rela->r_addend) - (Elf_Addr)where; 243 if (*where != tmp) 244 *where = tmp; 245 rdbg(dodebug, ("PC32 %s in %s --> %p in %s", 246 defobj->strtab + def->st_name, obj->path, 247 (void *)*where, defobj->path)); 248 break; 249 250 case R_TYPE(32): 251 def = _rtld_find_symdef(_rtld_objlist, rela->r_info, NULL, obj, 252 &defobj, false); 253 if (def == NULL) 254 return -1; 255 256 tmp = (Elf_Addr)(defobj->relocbase + def->st_value + 257 rela->r_addend); 258 if (*where != tmp) 259 *where = tmp; 260 rdbg(dodebug, ("32 %s in %s --> %p in %s", 261 defobj->strtab + def->st_name, obj->path, 262 (void *)*where, defobj->path)); 263 break; 264 #endif /* __m68k__ */ 265 266 #if defined(__alpha__) 267 case R_TYPE(REFQUAD): 268 def = _rtld_find_symdef(_rtld_objlist, rela->r_info, NULL, obj, 269 &defobj, false); 270 if (def == NULL) 271 return -1; 272 273 tmp = (Elf_Addr)(defobj->relocbase + def->st_value) + 274 *where + rela->r_addend; 275 if (*where != tmp) 276 *where = tmp; 277 rdbg(dodebug, ("REFQUAD %s in %s --> %p in %s", 278 defobj->strtab + def->st_name, obj->path, 279 (void *)*where, defobj->path)); 280 break; 281 282 case R_TYPE(RELATIVE): 283 { 284 extern Elf_Addr _GLOBAL_OFFSET_TABLE_[]; 285 extern Elf_Addr _GOT_END_[]; 286 287 /* This is the ...iffy hueristic. */ 288 if (!dodebug || 289 (caddr_t)where < (caddr_t)_GLOBAL_OFFSET_TABLE_ || 290 (caddr_t)where >= (caddr_t)_GOT_END_) { 291 *where += (Elf_Addr)(obj->relocbase + rela->r_addend); 292 rdbg(dodebug, ("RELATIVE in %s --> %p", obj->path, 293 (void *)*where)); 294 } else 295 rdbg(dodebug, ("RELATIVE in %s stays at %p", 296 obj->path, (void *)*where)); 297 break; 298 } 299 #endif /* __alpha__ */ 300 301 #if defined(__alpha__) || defined(__i386__) || defined(__m68k__) 302 case R_TYPE(GLOB_DAT): 303 def = _rtld_find_symdef(_rtld_objlist, rela->r_info, NULL, obj, 304 &defobj, false); 305 if (def == NULL) 306 return -1; 307 308 tmp = (Elf_Addr)(defobj->relocbase + def->st_value) + 309 rela->r_addend; 310 if (*where != tmp) 311 *where = tmp; 312 rdbg(dodebug, ("GLOB_DAT %s in %s --> %p in %s", 313 defobj->strtab + def->st_name, obj->path, 314 (void *)*where, defobj->path)); 315 break; 316 317 #if !defined(__alpha__) 318 case R_TYPE(RELATIVE): 319 *where += (Elf_Addr)obj->relocbase; 320 rdbg(dodebug, ("RELATIVE in %s --> %p", obj->path, 321 (void *)*where)); 322 break; 323 #endif /* ! __alpha__ */ 324 325 case R_TYPE(COPY): 326 /* 327 * These are deferred until all other relocations have 328 * been done. All we do here is make sure that the COPY 329 * relocation is not in a shared library. They are allowed 330 * only in executable files. 331 */ 332 if (!obj->mainprog) { 333 _rtld_error( 334 "%s: Unexpected R_COPY relocation in shared library", 335 obj->path); 336 return -1; 337 } 338 rdbg(dodebug, ("COPY (avoid in main)")); 339 break; 340 #endif /* __i386__ || __alpha__ || __m68k__ */ 341 342 #if defined(__mips__) 343 case R_TYPE(REL32): 344 /* 32-bit PC-relative reference */ 345 def = obj->symtab + ELF_R_SYM(rela->r_info); 346 347 if (ELFDEFNNAME(ST_BIND)(def->st_info) == STB_LOCAL && 348 (ELFDEFNNAME(ST_TYPE)(def->st_info) == STT_SECTION || 349 ELFDEFNNAME(ST_TYPE)(def->st_info) == STT_NOTYPE)) { 350 /* 351 * XXX: ABI DIFFERENCE! 352 * 353 * Old NetBSD binutils would generate shared libs 354 * with section-relative relocations being already 355 * adjusted for the start address of the section. 356 * 357 * New binutils, OTOH, generate shared libs with 358 * the same relocations being based at zero, so we 359 * need to add in the start address of the section. 360 * 361 * We assume that all section-relative relocs with 362 * contents less than the start of the section need 363 * to be adjusted; this should work with both old 364 * and new shlibs. 365 * 366 * --rkb, Oct 6, 2001 367 */ 368 if (def->st_info == STT_SECTION && 369 (*where < def->st_value)) 370 *where += (Elf_Addr) def->st_value; 371 372 *where += (Elf_Addr)obj->relocbase; 373 374 rdbg(dodebug, ("REL32 %s in %s --> %p in %s", 375 obj->strtab + def->st_name, obj->path, 376 (void *)*where, obj->path)); 377 } else { 378 /* XXX maybe do something re: bootstrapping? */ 379 def = _rtld_find_symdef(_rtld_objlist, rela->r_info, 380 NULL, obj, &defobj, false); 381 if (def == NULL) 382 return -1; 383 *where += (Elf_Addr)(defobj->relocbase + def->st_value); 384 rdbg(dodebug, ("REL32 %s in %s --> %p in %s", 385 defobj->strtab + def->st_name, obj->path, 386 (void *)*where, defobj->path)); 387 } 388 break; 389 390 #endif /* __mips__ */ 391 392 #if defined(__powerpc__) || defined(__vax__) 393 case R_TYPE(32): /* word32 S + A */ 394 case R_TYPE(GLOB_DAT): /* word32 S + A */ 395 def = _rtld_find_symdef(_rtld_objlist, rela->r_info, NULL, obj, 396 &defobj, false); 397 if (def == NULL) 398 return -1; 399 400 tmp = (Elf_Addr)(defobj->relocbase + def->st_value + 401 rela->r_addend); 402 403 if (*where != tmp) 404 *where = tmp; 405 rdbg(dodebug, ("32/GLOB_DAT %s in %s --> %p in %s", 406 defobj->strtab + def->st_name, obj->path, 407 (void *)*where, defobj->path)); 408 break; 409 410 case R_TYPE(COPY): 411 rdbg(dodebug, ("COPY")); 412 break; 413 414 case R_TYPE(JMP_SLOT): 415 rdbg(dodebug, ("JMP_SLOT")); 416 break; 417 418 case R_TYPE(RELATIVE): /* word32 B + A */ 419 tmp = (Elf_Addr)(obj->relocbase + rela->r_addend); 420 if (*where != tmp) 421 *where = tmp; 422 rdbg(dodebug, ("RELATIVE in %s --> %p", obj->path, 423 (void *)*where)); 424 break; 425 #endif /* __powerpc__ || __vax__ */ 426 427 #if defined(__powerpc__) 428 case R_TYPE(16_LO): /* #lo(S + A) */ 429 tmp = (Elf_Addr)(obj->relocbase + rela->r_addend); 430 if (*(Elf32_Half *)where != tmp) 431 *(Elf32_Half *)where = tmp; 432 rdbg(dodebug, ("16_LO in %s --> %p", obj->path, 433 (void *)*where)); 434 break; 435 436 case R_TYPE(16_HI): /* #hi(S + A) */ 437 tmp = (Elf_Addr)(obj->relocbase + rela->r_addend) >> 16; 438 if (*(Elf32_Half *)where != tmp) 439 *(Elf32_Half *)where = tmp; 440 rdbg(dodebug, ("16_HI in %s --> %p", obj->path, 441 (void *)*where)); 442 break; 443 444 case R_TYPE(16_HA): /* #ha(S + A) */ 445 tmp = (Elf_Addr)(obj->relocbase + rela->r_addend + 0x8000) 446 >> 16; 447 if (*(Elf32_Half *)where != tmp) 448 *(Elf32_Half *)where = tmp; 449 rdbg(dodebug, ("16_HA in %s --> %p", obj->path, 450 (void *)*where)); 451 break; 452 #endif /* __powerpc__ */ 453 454 #if defined(__arm__) 455 case R_TYPE(GLOB_DAT): /* word32 B + S */ 456 def = _rtld_find_symdef(_rtld_objlist, rela->r_info, NULL, obj, 457 &defobj, false); 458 if (def == NULL) 459 return -1; 460 *where = (Elf_Addr)(defobj->relocbase + def->st_value); 461 rdbg(dodebug, ("GLOB_DAT %s in %s --> %p @ %p in %s", 462 defobj->strtab + def->st_name, obj->path, 463 (void *)*where, where, defobj->path)); 464 break; 465 466 case R_TYPE(COPY): 467 rdbg(dodebug, ("COPY")); 468 break; 469 470 case R_TYPE(JUMP_SLOT): 471 rdbg(dodebug, ("JUMP_SLOT")); 472 break; 473 474 case R_TYPE(ABS32): /* word32 B + S + A */ 475 def = _rtld_find_symdef(_rtld_objlist, rela->r_info, NULL, obj, 476 &defobj, false); 477 if (def == NULL) 478 return -1; 479 *where += (Elf_Addr)defobj->relocbase + def->st_value; 480 rdbg(dodebug, ("ABS32 %s in %s --> %p @ %p in %s", 481 defobj->strtab + def->st_name, obj->path, 482 (void *)*where, where, defobj->path)); 483 break; 484 485 case R_TYPE(RELATIVE): /* word32 B + A */ 486 *where += (Elf_Addr)obj->relocbase; 487 rdbg(dodebug, ("RELATIVE in %s --> %p @ %p", obj->path, 488 (void *)*where, where)); 489 break; 490 491 case R_TYPE(PC24): { /* word32 S - P + A */ 492 Elf32_Sword addend; 493 494 /* 495 * Extract addend and sign-extend if needed. 496 */ 497 addend = *where; 498 if (addend & 0x00800000) 499 addend |= 0xff000000; 500 501 def = _rtld_find_symdef(_rtld_objlist, rela->r_info, NULL, obj, 502 &defobj, false); 503 if (def == NULL) 504 return -1; 505 tmp = (Elf_Addr)obj->relocbase + def->st_value 506 - (Elf_Addr)where + (addend << 2); 507 if ((tmp & 0xfe000000) != 0xfe000000 && (tmp & 0xfe000000) != 0) { 508 _rtld_error( 509 "%s: R_ARM_PC24 relocation @ %p to %s failed " 510 "(displacement %ld (%#lx) out of range)", 511 obj->path, where, defobj->strtab + def->st_name, 512 (long) tmp, (long) tmp); 513 return -1; 514 } 515 tmp >>= 2; 516 *where = (*where & 0xff000000) | (tmp & 0x00ffffff); 517 rdbg(dodebug, ("PC24 %s in %s --> %p @ %p in %s", 518 defobj->strtab + def->st_name, obj->path, 519 (void *)*where, where, defobj->path)); 520 break; 521 } 522 #endif 523 524 default: 525 def = _rtld_find_symdef(_rtld_objlist, rela->r_info, NULL, obj, 526 &defobj, true); 527 rdbg(dodebug, ("sym = %lu, type = %lu, offset = %p, " 528 "addend = %p, contents = %p, symbol = %s", 529 (u_long)ELF_R_SYM(rela->r_info), 530 (u_long)ELF_R_TYPE(rela->r_info), 531 (void *)rela->r_offset, (void *)rela->r_addend, 532 (void *)*where, 533 def ? defobj->strtab + def->st_name : "??")); 534 _rtld_error("%s: Unsupported relocation type %ld " 535 "in non-PLT relocations\n", 536 obj->path, (u_long) ELF_R_TYPE(rela->r_info)); 537 return -1; 538 } 539 return 0; 540 } 541 542 543 #if !defined(__powerpc__) 544 545 int 546 _rtld_relocate_plt_object(obj, rela, addrp, bind_now, dodebug) 547 Obj_Entry *obj; 548 const Elf_Rela *rela; 549 caddr_t *addrp; 550 bool bind_now; 551 bool dodebug; 552 { 553 Elf_Addr *where = (Elf_Addr *)(obj->relocbase + rela->r_offset); 554 Elf_Addr new_value; 555 556 /* Fully resolve procedure addresses now */ 557 558 #if defined(__alpha__) || defined(__arm__) || defined(__i386__) || \ 559 defined(__m68k__) || defined(__vax__) 560 if (bind_now || obj->pltgot == NULL) { 561 const Elf_Sym *def; 562 const Obj_Entry *defobj; 563 564 #if !defined(__arm__) 565 assert(ELF_R_TYPE(rela->r_info) == R_TYPE(JMP_SLOT)); 566 #else 567 assert(ELF_R_TYPE(rela->r_info) == R_TYPE(JUMP_SLOT)); 568 #endif 569 570 def = _rtld_find_symdef(_rtld_objlist, rela->r_info, NULL, obj, 571 &defobj, true); 572 if (def == NULL) 573 return -1; 574 575 new_value = (Elf_Addr)(defobj->relocbase + def->st_value); 576 #if defined(__vax__) 577 new_value += rela->r_addend; 578 #endif 579 rdbg(dodebug, ("bind now %d/fixup in %s --> old=%p new=%p", 580 (int)bind_now, 581 defobj->strtab + def->st_name, 582 (void *)*where, (void *)new_value)); 583 } else 584 #endif /* __alpha__ || __i386__ || __m68k__ || __vax__ */ 585 if (!obj->mainprog) { 586 /* Just relocate the GOT slots pointing into the PLT */ 587 new_value = *where + (Elf_Addr)(obj->relocbase); 588 rdbg(dodebug, ("fixup !main in %s --> %p", obj->path, 589 (void *)*where)); 590 } else { 591 return 0; 592 } 593 /* 594 * Since this page is probably copy-on-write, let's not write 595 * it unless we really really have to. 596 */ 597 if (*where != new_value) 598 *where = new_value; 599 if (addrp != NULL) { 600 *addrp = *(caddr_t *)(obj->relocbase + rela->r_offset); 601 #if defined(__vax__) 602 *addrp -= rela->r_addend; 603 #endif 604 } 605 return 0; 606 } 607 608 #endif /* __powerpc__ */ 609 610 #endif /* __sparc__ || __x86_64__ */ 611 612 caddr_t 613 _rtld_bind(obj, reloff) 614 Obj_Entry *obj; 615 Elf_Word reloff; 616 { 617 const Elf_Rela *rela; 618 Elf_Rela ourrela; 619 caddr_t addr; 620 621 if (obj->pltrel != NULL) { 622 const Elf_Rel *rel; 623 624 rel = (const Elf_Rel *)((caddr_t) obj->pltrel + reloff); 625 ourrela.r_info = rel->r_info; 626 ourrela.r_offset = rel->r_offset; 627 ourrela.r_addend = 0; 628 rela = &ourrela; 629 } else { 630 rela = (const Elf_Rela *)((caddr_t) obj->pltrela + reloff); 631 #ifdef __sparc64__ 632 if (ELF_R_TYPE(obj->pltrela->r_info) == R_TYPE(JMP_SLOT)) { 633 /* 634 * XXXX 635 * 636 * The first for PLT entries are reserved. There 637 * is some disagreement whether they should have 638 * associated relocation entries. Both the SPARC 639 * 32-bit and 64-bit ELF specifications say that 640 * they should have relocation entries, but the 641 * 32-bit SPARC binutils do not generate them, 642 * and now the 64-bit SPARC binutils have stopped 643 * generating them too. 644 * 645 * So, to provide binary compatibility, we will 646 * check the first entry, if it is reserved it 647 * should not be of the type JMP_SLOT. If it 648 * is JMP_SLOT, then the 4 reserved entries were 649 * not generated and our index is 4 entries too far. 650 */ 651 rela -= 4; 652 } 653 #endif 654 } 655 656 if (_rtld_relocate_plt_object(obj, rela, &addr, true, true) < 0) 657 _rtld_die(); 658 659 return addr; 660 } 661 662 /* 663 * Relocate newly-loaded shared objects. The argument is a pointer to 664 * the Obj_Entry for the first such object. All objects from the first 665 * to the end of the list of objects are relocated. Returns 0 on success, 666 * or -1 on failure. 667 */ 668 int 669 _rtld_relocate_objects(first, bind_now, dodebug) 670 Obj_Entry *first; 671 bool bind_now; 672 bool dodebug; 673 { 674 Obj_Entry *obj; 675 int ok = 1; 676 677 for (obj = first; obj != NULL; obj = obj->next) { 678 if (obj->nbuckets == 0 || obj->nchains == 0 || 679 obj->buckets == NULL || obj->symtab == NULL || 680 obj->strtab == NULL) { 681 _rtld_error("%s: Shared object has no run-time" 682 " symbol table", obj->path); 683 return -1; 684 } 685 rdbg(dodebug, (" relocating %s (%ld/%ld rel/rela, " 686 "%ld/%ld plt rel/rela)", 687 obj->path, 688 (long)(obj->rellim - obj->rel), 689 (long)(obj->relalim - obj->rela), 690 (long)(obj->pltrellim - obj->pltrel), 691 (long)(obj->pltrelalim - obj->pltrela))); 692 693 if (obj->textrel) { 694 /* 695 * There are relocations to the write-protected text 696 * segment. 697 */ 698 if (mprotect(obj->mapbase, obj->textsize, 699 PROT_READ | PROT_WRITE | PROT_EXEC) == -1) { 700 _rtld_error("%s: Cannot write-enable text " 701 "segment: %s", obj->path, xstrerror(errno)); 702 return -1; 703 } 704 } 705 if (obj->rel != NULL) { 706 /* Process the non-PLT relocations. */ 707 const Elf_Rel *rel; 708 for (rel = obj->rel; rel < obj->rellim; ++rel) { 709 Elf_Rela ourrela; 710 ourrela.r_info = rel->r_info; 711 ourrela.r_offset = rel->r_offset; 712 #if defined(__mips__) 713 /* rel->r_offset is not valid on mips? */ 714 if (ELF_R_TYPE(ourrela.r_info) == R_TYPE(NONE)) 715 ourrela.r_addend = 0; 716 else 717 #endif 718 ourrela.r_addend = 719 *(Elf_Word *)(obj->relocbase + 720 rel->r_offset); 721 722 if (_rtld_relocate_nonplt_object(obj, &ourrela, 723 dodebug) < 0) 724 ok = 0; 725 } 726 } 727 if (obj->rela != NULL) { 728 /* Process the non-PLT relocations. */ 729 const Elf_Rela *rela; 730 for (rela = obj->rela; rela < obj->relalim; ++rela) { 731 if (_rtld_relocate_nonplt_object(obj, rela, 732 dodebug) < 0) 733 ok = 0; 734 } 735 } 736 if (obj->textrel) { /* Re-protected the text segment. */ 737 if (mprotect(obj->mapbase, obj->textsize, 738 PROT_READ | PROT_EXEC) == -1) { 739 _rtld_error("%s: Cannot write-protect text " 740 "segment: %s", obj->path, xstrerror(errno)); 741 return -1; 742 } 743 } 744 /* Process the PLT relocations. */ 745 if (obj->pltrel != NULL) { 746 const Elf_Rel *rel; 747 for (rel = obj->pltrel; rel < obj->pltrellim; ++rel) { 748 Elf_Rela ourrela; 749 ourrela.r_info = rel->r_info; 750 ourrela.r_offset = rel->r_offset; 751 ourrela.r_addend = 752 *(Elf_Word *)(obj->relocbase + 753 rel->r_offset); 754 if (_rtld_relocate_plt_object(obj, &ourrela, 755 NULL, bind_now, dodebug) < 0) 756 ok = 0; 757 } 758 } 759 if (obj->pltrela != NULL) { 760 const Elf_Rela *rela; 761 for (rela = obj->pltrela; rela < obj->pltrelalim; 762 ++rela) { 763 if (_rtld_relocate_plt_object(obj, rela, 764 NULL, bind_now, dodebug) < 0) 765 ok = 0; 766 } 767 } 768 if (!ok) 769 return -1; 770 771 772 /* Set some sanity-checking numbers in the Obj_Entry. */ 773 obj->magic = RTLD_MAGIC; 774 obj->version = RTLD_VERSION; 775 776 /* Fill in the dynamic linker entry points. */ 777 obj->dlopen = _rtld_dlopen; 778 obj->dlsym = _rtld_dlsym; 779 obj->dlerror = _rtld_dlerror; 780 obj->dlclose = _rtld_dlclose; 781 obj->dladdr = _rtld_dladdr; 782 783 /* Set the special PLTGOT entries. */ 784 if (obj->pltgot != NULL) { 785 #if defined(__arm__) || defined(__i386__) || defined(__m68k__) || \ 786 defined(__x86_64__) 787 obj->pltgot[1] = (Elf_Addr) obj; 788 obj->pltgot[2] = (Elf_Addr) & _rtld_bind_start; 789 #endif 790 #if defined(__alpha__) 791 _rtld_setup_alpha_pltgot(obj, dodebug); 792 #endif 793 #if defined(__mips__) 794 _rtld_relocate_mips_got(obj); 795 796 obj->pltgot[0] = (Elf_Addr) & _rtld_bind_start; 797 /* XXX only if obj->pltgot[1] & 0x80000000 ?? */ 798 obj->pltgot[1] |= (Elf_Addr) obj; 799 #endif 800 #if defined(__powerpc__) 801 _rtld_setup_powerpc_plt(obj); 802 #endif 803 #if defined(__sparc__) 804 #if defined(__arch64__) || defined(__sparc_v9__) 805 /* 806 * On sparc64 we got troubles. 807 * 808 * Instructions are 4 bytes long. 809 * Elf[64]_Addr is 8 bytes long, so are our pltglot[] 810 * array entries. 811 * Each PLT entry jumps to PLT0 to enter the dynamic 812 * linker. 813 * Loading an arbitrary 64-bit pointer takes 6 814 * instructions and 2 registers. 815 * 816 * Somehow we need to issue a save to get a new stack 817 * frame, load the address of the dynamic linker, and 818 * jump there, in 8 instructions or less. 819 * 820 * Oh, we need to fill out both PLT0 and PLT1. 821 */ 822 { 823 Elf_Word *entry = (Elf_Word *)obj->pltgot; 824 extern void _rtld_install_plt __P((Elf_Word *, 825 Elf_Addr)); 826 extern void _rtld_bind_start_0 __P((long, 827 long)); 828 extern void _rtld_bind_start_1 __P((long, 829 long)); 830 831 /* Install in entries 0 and 1 */ 832 _rtld_install_plt(&entry[0], 833 (Elf_Addr)&_rtld_bind_start_0); 834 _rtld_install_plt(&entry[8], 835 (Elf_Addr)&_rtld_bind_start_1); 836 837 /* 838 * Install the object reference in first slot 839 * of entry 2. 840 */ 841 obj->pltgot[8] = (Elf_Addr) obj; 842 } 843 #else 844 /* 845 * PLTGOT is the PLT on the sparc. 846 * The first entry holds the call the dynamic linker. 847 * We construct a `call' sequence that transfers 848 * to `_rtld_bind_start()'. 849 * The second entry holds the object identification. 850 * Note: each PLT entry is three words long. 851 */ 852 #define SAVE 0x9de3bfc0 /* i.e. `save %sp,-64,%sp' */ 853 #define CALL 0x40000000 854 #define NOP 0x01000000 855 obj->pltgot[0] = SAVE; 856 obj->pltgot[1] = CALL | 857 ((Elf_Addr)&_rtld_bind_start - 858 (Elf_Addr)&obj->pltgot[1]) >> 2; 859 obj->pltgot[2] = NOP; 860 861 obj->pltgot[3] = (Elf_Addr) obj; 862 #endif /* __arch64__ */ 863 #endif /* __sparc__ */ 864 #if defined(__vax__) 865 obj->pltgot[1] = (Elf_Addr) obj; 866 obj->pltgot[2] = (Elf_Addr) & _rtld_bind_start; 867 #endif 868 } 869 } 870 871 return 0; 872 } 873
Indexes created Tue Sep 30 17:09:57 GMT 2025