reloc.c revision 1.46
1 /* $NetBSD: reloc.c,v 1.46 2001/12/16 08:23:25 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 if (*where != (Elf_Addr)(defobj->relocbase + def->st_value)) 309 *where = (Elf_Addr)(defobj->relocbase + def->st_value); 310 rdbg(dodebug, ("GLOB_DAT %s in %s --> %p in %s", 311 defobj->strtab + def->st_name, obj->path, 312 (void *)*where, defobj->path)); 313 break; 314 315 #if !defined(__alpha__) 316 case R_TYPE(RELATIVE): 317 *where += (Elf_Addr)obj->relocbase; 318 rdbg(dodebug, ("RELATIVE in %s --> %p", obj->path, 319 (void *)*where)); 320 break; 321 #endif /* ! __alpha__ */ 322 323 case R_TYPE(COPY): 324 /* 325 * These are deferred until all other relocations have 326 * been done. All we do here is make sure that the COPY 327 * relocation is not in a shared library. They are allowed 328 * only in executable files. 329 */ 330 if (!obj->mainprog) { 331 _rtld_error( 332 "%s: Unexpected R_COPY relocation in shared library", 333 obj->path); 334 return -1; 335 } 336 rdbg(dodebug, ("COPY (avoid in main)")); 337 break; 338 #endif /* __i386__ || __alpha__ || __m68k__ */ 339 340 #if defined(__mips__) 341 case R_TYPE(REL32): 342 /* 32-bit PC-relative reference */ 343 def = obj->symtab + ELF_R_SYM(rela->r_info); 344 345 if (ELFDEFNNAME(ST_BIND)(def->st_info) == STB_LOCAL && 346 (ELFDEFNNAME(ST_TYPE)(def->st_info) == STT_SECTION || 347 ELFDEFNNAME(ST_TYPE)(def->st_info) == STT_NOTYPE)) { 348 /* 349 * XXX: ABI DIFFERENCE! 350 * 351 * Old NetBSD binutils would generate shared libs 352 * with section-relative relocations being already 353 * adjusted for the start address of the section. 354 * 355 * New binutils, OTOH, generate shared libs with 356 * the same relocations being based at zero, so we 357 * need to add in the start address of the section. 358 * 359 * We assume that all section-relative relocs with 360 * contents less than the start of the section need 361 * to be adjusted; this should work with both old 362 * and new shlibs. 363 * 364 * --rkb, Oct 6, 2001 365 */ 366 if (def->st_info == STT_SECTION && 367 (*where < def->st_value)) 368 *where += (Elf_Addr) def->st_value; 369 370 *where += (Elf_Addr)obj->relocbase; 371 372 rdbg(dodebug, ("REL32 %s in %s --> %p in %s", 373 obj->strtab + def->st_name, obj->path, 374 (void *)*where, obj->path)); 375 } else { 376 /* XXX maybe do something re: bootstrapping? */ 377 def = _rtld_find_symdef(_rtld_objlist, rela->r_info, 378 NULL, obj, &defobj, false); 379 if (def == NULL) 380 return -1; 381 *where += (Elf_Addr)(defobj->relocbase + def->st_value); 382 rdbg(dodebug, ("REL32 %s in %s --> %p in %s", 383 defobj->strtab + def->st_name, obj->path, 384 (void *)*where, defobj->path)); 385 } 386 break; 387 388 #endif /* __mips__ */ 389 390 #if defined(__powerpc__) || defined(__vax__) 391 case R_TYPE(32): /* word32 S + A */ 392 case R_TYPE(GLOB_DAT): /* word32 S + A */ 393 def = _rtld_find_symdef(_rtld_objlist, rela->r_info, NULL, obj, 394 &defobj, false); 395 if (def == NULL) 396 return -1; 397 398 tmp = (Elf_Addr)(defobj->relocbase + def->st_value + 399 rela->r_addend); 400 401 if (*where != tmp) 402 *where = tmp; 403 rdbg(dodebug, ("32/GLOB_DAT %s in %s --> %p in %s", 404 defobj->strtab + def->st_name, obj->path, 405 (void *)*where, defobj->path)); 406 break; 407 408 case R_TYPE(COPY): 409 rdbg(dodebug, ("COPY")); 410 break; 411 412 case R_TYPE(JMP_SLOT): 413 rdbg(dodebug, ("JMP_SLOT")); 414 break; 415 416 case R_TYPE(RELATIVE): /* word32 B + A */ 417 tmp = (Elf_Addr)(obj->relocbase + rela->r_addend); 418 if (*where != tmp) 419 *where = tmp; 420 rdbg(dodebug, ("RELATIVE in %s --> %p", obj->path, 421 (void *)*where)); 422 break; 423 #endif /* __powerpc__ || __vax__ */ 424 425 #if defined(__powerpc__) 426 case R_TYPE(16_LO): /* #lo(S + A) */ 427 tmp = (Elf_Addr)(obj->relocbase + rela->r_addend); 428 if (*(Elf32_Half *)where != tmp) 429 *(Elf32_Half *)where = tmp; 430 rdbg(dodebug, ("16_LO in %s --> %p", obj->path, 431 (void *)*where)); 432 break; 433 434 case R_TYPE(16_HI): /* #hi(S + A) */ 435 tmp = (Elf_Addr)(obj->relocbase + rela->r_addend) >> 16; 436 if (*(Elf32_Half *)where != tmp) 437 *(Elf32_Half *)where = tmp; 438 rdbg(dodebug, ("16_HI in %s --> %p", obj->path, 439 (void *)*where)); 440 break; 441 442 case R_TYPE(16_HA): /* #ha(S + A) */ 443 tmp = (Elf_Addr)(obj->relocbase + rela->r_addend + 0x8000) 444 >> 16; 445 if (*(Elf32_Half *)where != tmp) 446 *(Elf32_Half *)where = tmp; 447 rdbg(dodebug, ("16_HA in %s --> %p", obj->path, 448 (void *)*where)); 449 break; 450 #endif /* __powerpc__ */ 451 452 #if defined(__arm__) 453 case R_TYPE(GLOB_DAT): /* word32 B + S */ 454 def = _rtld_find_symdef(_rtld_objlist, rela->r_info, NULL, obj, 455 &defobj, false); 456 if (def == NULL) 457 return -1; 458 *where = (Elf_Addr)(defobj->relocbase + def->st_value); 459 rdbg(dodebug, ("GLOB_DAT %s in %s --> %p @ %p in %s", 460 defobj->strtab + def->st_name, obj->path, 461 (void *)*where, where, defobj->path)); 462 break; 463 464 case R_TYPE(COPY): 465 rdbg(dodebug, ("COPY")); 466 break; 467 468 case R_TYPE(JUMP_SLOT): 469 rdbg(dodebug, ("JUMP_SLOT")); 470 break; 471 472 case R_TYPE(ABS32): /* word32 B + S + A */ 473 def = _rtld_find_symdef(_rtld_objlist, rela->r_info, NULL, obj, 474 &defobj, false); 475 if (def == NULL) 476 return -1; 477 *where += (Elf_Addr)defobj->relocbase + def->st_value; 478 rdbg(dodebug, ("ABS32 %s in %s --> %p @ %p in %s", 479 defobj->strtab + def->st_name, obj->path, 480 (void *)*where, where, defobj->path)); 481 break; 482 483 case R_TYPE(RELATIVE): /* word32 B + A */ 484 *where += (Elf_Addr)obj->relocbase; 485 rdbg(dodebug, ("RELATIVE in %s --> %p @ %p", obj->path, 486 (void *)*where, where)); 487 break; 488 489 case R_TYPE(PC24): { /* word32 S - P + A */ 490 Elf32_Sword addend; 491 492 /* 493 * Extract addend and sign-extend if needed. 494 */ 495 addend = *where; 496 if (addend & 0x00800000) 497 addend |= 0xff000000; 498 499 def = _rtld_find_symdef(_rtld_objlist, rela->r_info, NULL, obj, 500 &defobj, false); 501 if (def == NULL) 502 return -1; 503 tmp = (Elf_Addr)obj->relocbase + def->st_value 504 - (Elf_Addr)where + (addend << 2); 505 if ((tmp & 0xfe000000) != 0xfe000000 && (tmp & 0xfe000000) != 0) { 506 _rtld_error( 507 "%s: R_ARM_PC24 relocation @ %p to %s failed " 508 "(displacement %ld (%#lx) out of range)", 509 obj->path, where, defobj->strtab + def->st_name, 510 (long) tmp, (long) tmp); 511 return -1; 512 } 513 tmp >>= 2; 514 *where = (*where & 0xff000000) | (tmp & 0x00ffffff); 515 rdbg(dodebug, ("PC24 %s in %s --> %p @ %p in %s", 516 defobj->strtab + def->st_name, obj->path, 517 (void *)*where, where, defobj->path)); 518 break; 519 } 520 #endif 521 522 default: 523 def = _rtld_find_symdef(_rtld_objlist, rela->r_info, NULL, obj, 524 &defobj, true); 525 rdbg(dodebug, ("sym = %lu, type = %lu, offset = %p, " 526 "addend = %p, contents = %p, symbol = %s", 527 (u_long)ELF_R_SYM(rela->r_info), 528 (u_long)ELF_R_TYPE(rela->r_info), 529 (void *)rela->r_offset, (void *)rela->r_addend, 530 (void *)*where, 531 def ? defobj->strtab + def->st_name : "??")); 532 _rtld_error("%s: Unsupported relocation type %ld " 533 "in non-PLT relocations\n", 534 obj->path, (u_long) ELF_R_TYPE(rela->r_info)); 535 return -1; 536 } 537 return 0; 538 } 539 540 541 #if !defined(__powerpc__) 542 543 int 544 _rtld_relocate_plt_object(obj, rela, addrp, bind_now, dodebug) 545 Obj_Entry *obj; 546 const Elf_Rela *rela; 547 caddr_t *addrp; 548 bool bind_now; 549 bool dodebug; 550 { 551 Elf_Addr *where = (Elf_Addr *)(obj->relocbase + rela->r_offset); 552 Elf_Addr new_value; 553 554 /* Fully resolve procedure addresses now */ 555 556 #if defined(__alpha__) || defined(__arm__) || defined(__i386__) || \ 557 defined(__m68k__) || defined(__vax__) 558 if (bind_now || obj->pltgot == NULL) { 559 const Elf_Sym *def; 560 const Obj_Entry *defobj; 561 562 #if !defined(__arm__) 563 assert(ELF_R_TYPE(rela->r_info) == R_TYPE(JMP_SLOT)); 564 #else 565 assert(ELF_R_TYPE(rela->r_info) == R_TYPE(JUMP_SLOT)); 566 #endif 567 568 def = _rtld_find_symdef(_rtld_objlist, rela->r_info, NULL, obj, 569 &defobj, true); 570 if (def == NULL) 571 return -1; 572 573 new_value = (Elf_Addr)(defobj->relocbase + def->st_value); 574 #if defined(__vax__) 575 new_value += rela->r_addend; 576 #endif 577 rdbg(dodebug, ("bind now %d/fixup in %s --> old=%p new=%p", 578 (int)bind_now, 579 defobj->strtab + def->st_name, 580 (void *)*where, (void *)new_value)); 581 } else 582 #endif /* __alpha__ || __i386__ || __m68k__ || __vax__ */ 583 if (!obj->mainprog) { 584 /* Just relocate the GOT slots pointing into the PLT */ 585 new_value = *where + (Elf_Addr)(obj->relocbase); 586 rdbg(dodebug, ("fixup !main in %s --> %p", obj->path, 587 (void *)*where)); 588 } else { 589 return 0; 590 } 591 /* 592 * Since this page is probably copy-on-write, let's not write 593 * it unless we really really have to. 594 */ 595 if (*where != new_value) 596 *where = new_value; 597 if (addrp != NULL) { 598 *addrp = *(caddr_t *)(obj->relocbase + rela->r_offset); 599 #if defined(__vax__) 600 *addrp -= rela->r_addend; 601 #endif 602 } 603 return 0; 604 } 605 606 #endif /* __powerpc__ */ 607 608 #endif /* __sparc__ || __x86_64__ */ 609 610 caddr_t 611 _rtld_bind(obj, reloff) 612 Obj_Entry *obj; 613 Elf_Word reloff; 614 { 615 const Elf_Rela *rela; 616 Elf_Rela ourrela; 617 caddr_t addr; 618 619 if (obj->pltrel != NULL) { 620 const Elf_Rel *rel; 621 622 rel = (const Elf_Rel *)((caddr_t) obj->pltrel + reloff); 623 ourrela.r_info = rel->r_info; 624 ourrela.r_offset = rel->r_offset; 625 ourrela.r_addend = 0; 626 rela = &ourrela; 627 } else { 628 rela = (const Elf_Rela *)((caddr_t) obj->pltrela + reloff); 629 #ifdef __sparc64__ 630 if (ELF_R_TYPE(obj->pltrela->r_info) == R_TYPE(JMP_SLOT)) { 631 /* 632 * XXXX 633 * 634 * The first for PLT entries are reserved. There 635 * is some disagreement whether they should have 636 * associated relocation entries. Both the SPARC 637 * 32-bit and 64-bit ELF specifications say that 638 * they should have relocation entries, but the 639 * 32-bit SPARC binutils do not generate them, 640 * and now the 64-bit SPARC binutils have stopped 641 * generating them too. 642 * 643 * So, to provide binary compatibility, we will 644 * check the first entry, if it is reserved it 645 * should not be of the type JMP_SLOT. If it 646 * is JMP_SLOT, then the 4 reserved entries were 647 * not generated and our index is 4 entries too far. 648 */ 649 rela -= 4; 650 } 651 #endif 652 } 653 654 if (_rtld_relocate_plt_object(obj, rela, &addr, true, true) < 0) 655 _rtld_die(); 656 657 return addr; 658 } 659 660 /* 661 * Relocate newly-loaded shared objects. The argument is a pointer to 662 * the Obj_Entry for the first such object. All objects from the first 663 * to the end of the list of objects are relocated. Returns 0 on success, 664 * or -1 on failure. 665 */ 666 int 667 _rtld_relocate_objects(first, bind_now, dodebug) 668 Obj_Entry *first; 669 bool bind_now; 670 bool dodebug; 671 { 672 Obj_Entry *obj; 673 int ok = 1; 674 675 for (obj = first; obj != NULL; obj = obj->next) { 676 if (obj->nbuckets == 0 || obj->nchains == 0 || 677 obj->buckets == NULL || obj->symtab == NULL || 678 obj->strtab == NULL) { 679 _rtld_error("%s: Shared object has no run-time" 680 " symbol table", obj->path); 681 return -1; 682 } 683 rdbg(dodebug, (" relocating %s (%ld/%ld rel/rela, " 684 "%ld/%ld plt rel/rela)", 685 obj->path, 686 (long)(obj->rellim - obj->rel), 687 (long)(obj->relalim - obj->rela), 688 (long)(obj->pltrellim - obj->pltrel), 689 (long)(obj->pltrelalim - obj->pltrela))); 690 691 if (obj->textrel) { 692 /* 693 * There are relocations to the write-protected text 694 * segment. 695 */ 696 if (mprotect(obj->mapbase, obj->textsize, 697 PROT_READ | PROT_WRITE | PROT_EXEC) == -1) { 698 _rtld_error("%s: Cannot write-enable text " 699 "segment: %s", obj->path, xstrerror(errno)); 700 return -1; 701 } 702 } 703 if (obj->rel != NULL) { 704 /* Process the non-PLT relocations. */ 705 const Elf_Rel *rel; 706 for (rel = obj->rel; rel < obj->rellim; ++rel) { 707 Elf_Rela ourrela; 708 ourrela.r_info = rel->r_info; 709 ourrela.r_offset = rel->r_offset; 710 #if defined(__mips__) 711 /* rel->r_offset is not valid on mips? */ 712 if (ELF_R_TYPE(ourrela.r_info) == R_TYPE(NONE)) 713 ourrela.r_addend = 0; 714 else 715 #endif 716 ourrela.r_addend = 717 *(Elf_Word *)(obj->relocbase + 718 rel->r_offset); 719 720 if (_rtld_relocate_nonplt_object(obj, &ourrela, 721 dodebug) < 0) 722 ok = 0; 723 } 724 } 725 if (obj->rela != NULL) { 726 /* Process the non-PLT relocations. */ 727 const Elf_Rela *rela; 728 for (rela = obj->rela; rela < obj->relalim; ++rela) { 729 if (_rtld_relocate_nonplt_object(obj, rela, 730 dodebug) < 0) 731 ok = 0; 732 } 733 } 734 if (obj->textrel) { /* Re-protected the text segment. */ 735 if (mprotect(obj->mapbase, obj->textsize, 736 PROT_READ | PROT_EXEC) == -1) { 737 _rtld_error("%s: Cannot write-protect text " 738 "segment: %s", obj->path, xstrerror(errno)); 739 return -1; 740 } 741 } 742 /* Process the PLT relocations. */ 743 if (obj->pltrel != NULL) { 744 const Elf_Rel *rel; 745 for (rel = obj->pltrel; rel < obj->pltrellim; ++rel) { 746 Elf_Rela ourrela; 747 ourrela.r_info = rel->r_info; 748 ourrela.r_offset = rel->r_offset; 749 ourrela.r_addend = 750 *(Elf_Word *)(obj->relocbase + 751 rel->r_offset); 752 if (_rtld_relocate_plt_object(obj, &ourrela, 753 NULL, bind_now, dodebug) < 0) 754 ok = 0; 755 } 756 } 757 if (obj->pltrela != NULL) { 758 const Elf_Rela *rela; 759 for (rela = obj->pltrela; rela < obj->pltrelalim; 760 ++rela) { 761 if (_rtld_relocate_plt_object(obj, rela, 762 NULL, bind_now, dodebug) < 0) 763 ok = 0; 764 } 765 } 766 if (!ok) 767 return -1; 768 769 770 /* Set some sanity-checking numbers in the Obj_Entry. */ 771 obj->magic = RTLD_MAGIC; 772 obj->version = RTLD_VERSION; 773 774 /* Fill in the dynamic linker entry points. */ 775 obj->dlopen = _rtld_dlopen; 776 obj->dlsym = _rtld_dlsym; 777 obj->dlerror = _rtld_dlerror; 778 obj->dlclose = _rtld_dlclose; 779 obj->dladdr = _rtld_dladdr; 780 781 /* Set the special PLTGOT entries. */ 782 if (obj->pltgot != NULL) { 783 #if defined(__arm__) || defined(__i386__) || defined(__m68k__) || \ 784 defined(__x86_64__) 785 obj->pltgot[1] = (Elf_Addr) obj; 786 obj->pltgot[2] = (Elf_Addr) & _rtld_bind_start; 787 #endif 788 #if defined(__alpha__) 789 _rtld_setup_alpha_pltgot(obj, dodebug); 790 #endif 791 #if defined(__mips__) 792 _rtld_relocate_mips_got(obj); 793 794 obj->pltgot[0] = (Elf_Addr) & _rtld_bind_start; 795 /* XXX only if obj->pltgot[1] & 0x80000000 ?? */ 796 obj->pltgot[1] |= (Elf_Addr) obj; 797 #endif 798 #if defined(__powerpc__) 799 _rtld_setup_powerpc_plt(obj); 800 #endif 801 #if defined(__sparc__) 802 #if defined(__arch64__) || defined(__sparc_v9__) 803 /* 804 * On sparc64 we got troubles. 805 * 806 * Instructions are 4 bytes long. 807 * Elf[64]_Addr is 8 bytes long, so are our pltglot[] 808 * array entries. 809 * Each PLT entry jumps to PLT0 to enter the dynamic 810 * linker. 811 * Loading an arbitrary 64-bit pointer takes 6 812 * instructions and 2 registers. 813 * 814 * Somehow we need to issue a save to get a new stack 815 * frame, load the address of the dynamic linker, and 816 * jump there, in 8 instructions or less. 817 * 818 * Oh, we need to fill out both PLT0 and PLT1. 819 */ 820 { 821 Elf_Word *entry = (Elf_Word *)obj->pltgot; 822 extern void _rtld_install_plt __P((Elf_Word *, 823 Elf_Addr)); 824 extern void _rtld_bind_start_0 __P((long, 825 long)); 826 extern void _rtld_bind_start_1 __P((long, 827 long)); 828 829 /* Install in entries 0 and 1 */ 830 _rtld_install_plt(&entry[0], 831 (Elf_Addr)&_rtld_bind_start_0); 832 _rtld_install_plt(&entry[8], 833 (Elf_Addr)&_rtld_bind_start_1); 834 835 /* 836 * Install the object reference in first slot 837 * of entry 2. 838 */ 839 obj->pltgot[8] = (Elf_Addr) obj; 840 } 841 #else 842 /* 843 * PLTGOT is the PLT on the sparc. 844 * The first entry holds the call the dynamic linker. 845 * We construct a `call' sequence that transfers 846 * to `_rtld_bind_start()'. 847 * The second entry holds the object identification. 848 * Note: each PLT entry is three words long. 849 */ 850 #define SAVE 0x9de3bfc0 /* i.e. `save %sp,-64,%sp' */ 851 #define CALL 0x40000000 852 #define NOP 0x01000000 853 obj->pltgot[0] = SAVE; 854 obj->pltgot[1] = CALL | 855 ((Elf_Addr)&_rtld_bind_start - 856 (Elf_Addr)&obj->pltgot[1]) >> 2; 857 obj->pltgot[2] = NOP; 858 859 obj->pltgot[3] = (Elf_Addr) obj; 860 #endif /* __arch64__ */ 861 #endif /* __sparc__ */ 862 #if defined(__vax__) 863 obj->pltgot[1] = (Elf_Addr) obj; 864 obj->pltgot[2] = (Elf_Addr) & _rtld_bind_start; 865 #endif 866 } 867 } 868 869 return 0; 870 } 871
Indexes created Tue Sep 30 20:09:53 GMT 2025