reloc.c revision 1.45
1 /* $NetBSD: reloc.c,v 1.45 2001/12/14 00:53:06 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 #if defined(__alpha__) || defined(__i386__) || defined(__m68k__) 153 extern Elf_Addr _GLOBAL_OFFSET_TABLE_[]; 154 extern Elf_Dyn _DYNAMIC; 155 #endif 156 157 int 158 _rtld_relocate_nonplt_object(obj, rela, dodebug) 159 Obj_Entry *obj; 160 const Elf_Rela *rela; 161 bool dodebug; 162 { 163 Elf_Addr *where = (Elf_Addr *)(obj->relocbase + rela->r_offset); 164 const Elf_Sym *def; 165 const Obj_Entry *defobj; 166 #if defined(__alpha__) || defined(__arm__) || defined(__i386__) || \ 167 defined(__m68k__) || defined(__powerpc__) || defined(__vax__) 168 Elf_Addr tmp; 169 #endif 170 171 switch (ELF_R_TYPE(rela->r_info)) { 172 173 case R_TYPE(NONE): 174 break; 175 176 #if defined(__i386__) 177 case R_TYPE(GOT32): 178 179 def = _rtld_find_symdef(_rtld_objlist, rela->r_info, NULL, obj, 180 &defobj, false); 181 if (def == NULL) 182 return -1; 183 184 tmp = (Elf_Addr)(defobj->relocbase + def->st_value); 185 if (*where != tmp) 186 *where = tmp; 187 rdbg(dodebug, ("GOT32 %s in %s --> %p in %s", 188 defobj->strtab + def->st_name, obj->path, 189 (void *)*where, defobj->path)); 190 break; 191 192 case R_TYPE(PC32): 193 /* 194 * I don't think the dynamic linker should ever see this 195 * type of relocation. But the binutils-2.6 tools sometimes 196 * generate it. 197 */ 198 199 def = _rtld_find_symdef(_rtld_objlist, rela->r_info, NULL, obj, 200 &defobj, false); 201 if (def == NULL) 202 return -1; 203 204 *where += (Elf_Addr)(defobj->relocbase + def->st_value) - 205 (Elf_Addr)where; 206 rdbg(dodebug, ("PC32 %s in %s --> %p in %s", 207 defobj->strtab + def->st_name, obj->path, 208 (void *)*where, defobj->path)); 209 break; 210 211 case R_TYPE(32): 212 def = _rtld_find_symdef(_rtld_objlist, rela->r_info, NULL, obj, 213 &defobj, false); 214 if (def == NULL) 215 return -1; 216 217 *where += (Elf_Addr)(defobj->relocbase + def->st_value); 218 rdbg(dodebug, ("32 %s in %s --> %p in %s", 219 defobj->strtab + def->st_name, obj->path, 220 (void *)*where, defobj->path)); 221 break; 222 #endif /* __i386__ */ 223 224 #if defined(__m68k__) 225 case R_TYPE(GOT32): 226 def = _rtld_find_symdef(_rtld_objlist, rela->r_info, NULL, obj, 227 &defobj, false); 228 if (def == NULL) 229 return -1; 230 231 tmp = (Elf_Addr)(defobj->relocbase + def->st_value + 232 rela->r_addend); 233 if (*where != tmp) 234 *where = tmp; 235 rdbg(dodebug, ("GOT32 %s in %s --> %p in %s", 236 defobj->strtab + def->st_name, obj->path, 237 (void *)*where, defobj->path)); 238 break; 239 240 case R_TYPE(PC32): 241 def = _rtld_find_symdef(_rtld_objlist, rela->r_info, NULL, obj, 242 &defobj, false); 243 if (def == NULL) 244 return -1; 245 246 tmp = (Elf_Addr)(defobj->relocbase + def->st_value + 247 rela->r_addend) - (Elf_Addr)where; 248 if (*where != tmp) 249 *where = tmp; 250 rdbg(dodebug, ("PC32 %s in %s --> %p in %s", 251 defobj->strtab + def->st_name, obj->path, 252 (void *)*where, defobj->path)); 253 break; 254 255 case R_TYPE(32): 256 def = _rtld_find_symdef(_rtld_objlist, rela->r_info, NULL, obj, 257 &defobj, false); 258 if (def == NULL) 259 return -1; 260 261 tmp = (Elf_Addr)(defobj->relocbase + def->st_value + 262 rela->r_addend); 263 if (*where != tmp) 264 *where = tmp; 265 rdbg(dodebug, ("32 %s in %s --> %p in %s", 266 defobj->strtab + def->st_name, obj->path, 267 (void *)*where, defobj->path)); 268 break; 269 #endif /* __m68k__ */ 270 271 #if defined(__alpha__) 272 case R_TYPE(REFQUAD): 273 def = _rtld_find_symdef(_rtld_objlist, rela->r_info, NULL, obj, 274 &defobj, false); 275 if (def == NULL) 276 return -1; 277 278 tmp = (Elf_Addr)(defobj->relocbase + def->st_value) + 279 *where + rela->r_addend; 280 if (*where != tmp) 281 *where = tmp; 282 rdbg(dodebug, ("REFQUAD %s in %s --> %p in %s", 283 defobj->strtab + def->st_name, obj->path, 284 (void *)*where, defobj->path)); 285 break; 286 #endif /* __alpha__ */ 287 288 #if defined(__alpha__) || defined(__i386__) || defined(__m68k__) 289 case R_TYPE(GLOB_DAT): 290 def = _rtld_find_symdef(_rtld_objlist, rela->r_info, NULL, obj, 291 &defobj, false); 292 if (def == NULL) 293 return -1; 294 295 if (*where != (Elf_Addr)(defobj->relocbase + def->st_value)) 296 *where = (Elf_Addr)(defobj->relocbase + def->st_value); 297 rdbg(dodebug, ("GLOB_DAT %s in %s --> %p in %s", 298 defobj->strtab + def->st_name, obj->path, 299 (void *)*where, defobj->path)); 300 break; 301 302 case R_TYPE(RELATIVE): 303 if (!dodebug || 304 (caddr_t)where < (caddr_t)_GLOBAL_OFFSET_TABLE_ || 305 (caddr_t)where >= (caddr_t)&_DYNAMIC) { 306 *where += (Elf_Addr)obj->relocbase; 307 rdbg(dodebug, ("RELATIVE in %s --> %p", obj->path, 308 (void *)*where)); 309 } 310 else 311 rdbg(dodebug, ("RELATIVE in %s stays at %p", 312 obj->path, (void *)*where)); 313 break; 314 315 case R_TYPE(COPY): 316 /* 317 * These are deferred until all other relocations have 318 * been done. All we do here is make sure that the COPY 319 * relocation is not in a shared library. They are allowed 320 * only in executable files. 321 */ 322 if (!obj->mainprog) { 323 _rtld_error( 324 "%s: Unexpected R_COPY relocation in shared library", 325 obj->path); 326 return -1; 327 } 328 rdbg(dodebug, ("COPY (avoid in main)")); 329 break; 330 #endif /* __i386__ || __alpha__ || __m68k__ */ 331 332 #if defined(__mips__) 333 case R_TYPE(REL32): 334 /* 32-bit PC-relative reference */ 335 def = obj->symtab + ELF_R_SYM(rela->r_info); 336 337 if (ELFDEFNNAME(ST_BIND)(def->st_info) == STB_LOCAL && 338 (ELFDEFNNAME(ST_TYPE)(def->st_info) == STT_SECTION || 339 ELFDEFNNAME(ST_TYPE)(def->st_info) == STT_NOTYPE)) { 340 /* 341 * XXX: ABI DIFFERENCE! 342 * 343 * Old NetBSD binutils would generate shared libs 344 * with section-relative relocations being already 345 * adjusted for the start address of the section. 346 * 347 * New binutils, OTOH, generate shared libs with 348 * the same relocations being based at zero, so we 349 * need to add in the start address of the section. 350 * 351 * We assume that all section-relative relocs with 352 * contents less than the start of the section need 353 * to be adjusted; this should work with both old 354 * and new shlibs. 355 * 356 * --rkb, Oct 6, 2001 357 */ 358 if (def->st_info == STT_SECTION && 359 (*where < def->st_value)) 360 *where += (Elf_Addr) def->st_value; 361 362 *where += (Elf_Addr)obj->relocbase; 363 364 rdbg(dodebug, ("REL32 %s in %s --> %p in %s", 365 obj->strtab + def->st_name, obj->path, 366 (void *)*where, obj->path)); 367 } else { 368 /* XXX maybe do something re: bootstrapping? */ 369 def = _rtld_find_symdef(_rtld_objlist, rela->r_info, 370 NULL, obj, &defobj, false); 371 if (def == NULL) 372 return -1; 373 *where += (Elf_Addr)(defobj->relocbase + def->st_value); 374 rdbg(dodebug, ("REL32 %s in %s --> %p in %s", 375 defobj->strtab + def->st_name, obj->path, 376 (void *)*where, defobj->path)); 377 } 378 break; 379 380 #endif /* __mips__ */ 381 382 #if defined(__powerpc__) || defined(__vax__) 383 case R_TYPE(32): /* word32 S + A */ 384 case R_TYPE(GLOB_DAT): /* word32 S + A */ 385 def = _rtld_find_symdef(_rtld_objlist, rela->r_info, NULL, obj, 386 &defobj, false); 387 if (def == NULL) 388 return -1; 389 390 tmp = (Elf_Addr)(defobj->relocbase + def->st_value + 391 rela->r_addend); 392 393 if (*where != tmp) 394 *where = tmp; 395 rdbg(dodebug, ("32/GLOB_DAT %s in %s --> %p in %s", 396 defobj->strtab + def->st_name, obj->path, 397 (void *)*where, defobj->path)); 398 break; 399 400 case R_TYPE(COPY): 401 rdbg(dodebug, ("COPY")); 402 break; 403 404 case R_TYPE(JMP_SLOT): 405 rdbg(dodebug, ("JMP_SLOT")); 406 break; 407 408 case R_TYPE(RELATIVE): /* word32 B + A */ 409 tmp = (Elf_Addr)(obj->relocbase + rela->r_addend); 410 if (*where != tmp) 411 *where = tmp; 412 rdbg(dodebug, ("RELATIVE in %s --> %p", obj->path, 413 (void *)*where)); 414 break; 415 #endif /* __powerpc__ || __vax__ */ 416 417 #if defined(__powerpc__) 418 case R_TYPE(16_LO): /* #lo(S + A) */ 419 tmp = (Elf_Addr)(obj->relocbase + rela->r_addend); 420 if (*(Elf32_Half *)where != tmp) 421 *(Elf32_Half *)where = tmp; 422 rdbg(dodebug, ("16_LO in %s --> %p", obj->path, 423 (void *)*where)); 424 break; 425 426 case R_TYPE(16_HI): /* #hi(S + A) */ 427 tmp = (Elf_Addr)(obj->relocbase + rela->r_addend) >> 16; 428 if (*(Elf32_Half *)where != tmp) 429 *(Elf32_Half *)where = tmp; 430 rdbg(dodebug, ("16_HI in %s --> %p", obj->path, 431 (void *)*where)); 432 break; 433 434 case R_TYPE(16_HA): /* #ha(S + A) */ 435 tmp = (Elf_Addr)(obj->relocbase + rela->r_addend + 0x8000) 436 >> 16; 437 if (*(Elf32_Half *)where != tmp) 438 *(Elf32_Half *)where = tmp; 439 rdbg(dodebug, ("16_HA in %s --> %p", obj->path, 440 (void *)*where)); 441 break; 442 #endif /* __powerpc__ */ 443 444 #if defined(__arm__) 445 case R_TYPE(GLOB_DAT): /* word32 B + S */ 446 def = _rtld_find_symdef(_rtld_objlist, rela->r_info, NULL, obj, 447 &defobj, false); 448 if (def == NULL) 449 return -1; 450 *where = (Elf_Addr)(defobj->relocbase + def->st_value); 451 rdbg(dodebug, ("GLOB_DAT %s in %s --> %p @ %p in %s", 452 defobj->strtab + def->st_name, obj->path, 453 (void *)*where, where, defobj->path)); 454 break; 455 456 case R_TYPE(COPY): 457 rdbg(dodebug, ("COPY")); 458 break; 459 460 case R_TYPE(JUMP_SLOT): 461 rdbg(dodebug, ("JUMP_SLOT")); 462 break; 463 464 case R_TYPE(ABS32): /* word32 B + S + A */ 465 def = _rtld_find_symdef(_rtld_objlist, rela->r_info, NULL, obj, 466 &defobj, false); 467 if (def == NULL) 468 return -1; 469 *where += (Elf_Addr)defobj->relocbase + def->st_value; 470 rdbg(dodebug, ("ABS32 %s in %s --> %p @ %p in %s", 471 defobj->strtab + def->st_name, obj->path, 472 (void *)*where, where, defobj->path)); 473 break; 474 475 case R_TYPE(RELATIVE): /* word32 B + A */ 476 *where += (Elf_Addr)obj->relocbase; 477 rdbg(dodebug, ("RELATIVE in %s --> %p @ %p", obj->path, 478 (void *)*where, where)); 479 break; 480 481 case R_TYPE(PC24): { /* word32 S - P + A */ 482 Elf32_Sword addend; 483 484 /* 485 * Extract addend and sign-extend if needed. 486 */ 487 addend = *where; 488 if (addend & 0x00800000) 489 addend |= 0xff000000; 490 491 def = _rtld_find_symdef(_rtld_objlist, rela->r_info, NULL, obj, 492 &defobj, false); 493 if (def == NULL) 494 return -1; 495 tmp = (Elf_Addr)obj->relocbase + def->st_value 496 - (Elf_Addr)where + (addend << 2); 497 if ((tmp & 0xfe000000) != 0xfe000000 && (tmp & 0xfe000000) != 0) { 498 _rtld_error( 499 "%s: R_ARM_PC24 relocation @ %p to %s failed " 500 "(displacement %ld (%#lx) out of range)", 501 obj->path, where, defobj->strtab + def->st_name, 502 (long) tmp, (long) tmp); 503 return -1; 504 } 505 tmp >>= 2; 506 *where = (*where & 0xff000000) | (tmp & 0x00ffffff); 507 rdbg(dodebug, ("PC24 %s in %s --> %p @ %p in %s", 508 defobj->strtab + def->st_name, obj->path, 509 (void *)*where, where, defobj->path)); 510 break; 511 } 512 #endif 513 514 default: 515 def = _rtld_find_symdef(_rtld_objlist, rela->r_info, NULL, obj, 516 &defobj, true); 517 rdbg(dodebug, ("sym = %lu, type = %lu, offset = %p, " 518 "addend = %p, contents = %p, symbol = %s", 519 (u_long)ELF_R_SYM(rela->r_info), 520 (u_long)ELF_R_TYPE(rela->r_info), 521 (void *)rela->r_offset, (void *)rela->r_addend, 522 (void *)*where, 523 def ? defobj->strtab + def->st_name : "??")); 524 _rtld_error("%s: Unsupported relocation type %ld " 525 "in non-PLT relocations\n", 526 obj->path, (u_long) ELF_R_TYPE(rela->r_info)); 527 return -1; 528 } 529 return 0; 530 } 531 532 533 #if !defined(__powerpc__) 534 535 int 536 _rtld_relocate_plt_object(obj, rela, addrp, bind_now, dodebug) 537 Obj_Entry *obj; 538 const Elf_Rela *rela; 539 caddr_t *addrp; 540 bool bind_now; 541 bool dodebug; 542 { 543 Elf_Addr *where = (Elf_Addr *)(obj->relocbase + rela->r_offset); 544 Elf_Addr new_value; 545 546 /* Fully resolve procedure addresses now */ 547 548 #if defined(__alpha__) || defined(__arm__) || defined(__i386__) || \ 549 defined(__m68k__) || defined(__vax__) 550 if (bind_now || obj->pltgot == NULL) { 551 const Elf_Sym *def; 552 const Obj_Entry *defobj; 553 554 #if !defined(__arm__) 555 assert(ELF_R_TYPE(rela->r_info) == R_TYPE(JMP_SLOT)); 556 #else 557 assert(ELF_R_TYPE(rela->r_info) == R_TYPE(JUMP_SLOT)); 558 #endif 559 560 def = _rtld_find_symdef(_rtld_objlist, rela->r_info, NULL, obj, 561 &defobj, true); 562 if (def == NULL) 563 return -1; 564 565 new_value = (Elf_Addr)(defobj->relocbase + def->st_value); 566 #if defined(__vax__) 567 new_value += rela->r_addend; 568 #endif 569 rdbg(dodebug, ("bind now %d/fixup in %s --> old=%p new=%p", 570 (int)bind_now, 571 defobj->strtab + def->st_name, 572 (void *)*where, (void *)new_value)); 573 } else 574 #endif /* __alpha__ || __i386__ || __m68k__ || __vax__ */ 575 if (!obj->mainprog) { 576 /* Just relocate the GOT slots pointing into the PLT */ 577 new_value = *where + (Elf_Addr)(obj->relocbase); 578 rdbg(dodebug, ("fixup !main in %s --> %p", obj->path, 579 (void *)*where)); 580 } else { 581 return 0; 582 } 583 /* 584 * Since this page is probably copy-on-write, let's not write 585 * it unless we really really have to. 586 */ 587 if (*where != new_value) 588 *where = new_value; 589 if (addrp != NULL) { 590 *addrp = *(caddr_t *)(obj->relocbase + rela->r_offset); 591 #if defined(__vax__) 592 *addrp -= rela->r_addend; 593 #endif 594 } 595 return 0; 596 } 597 598 #endif /* __powerpc__ */ 599 600 #endif /* __sparc__ || __x86_64__ */ 601 602 caddr_t 603 _rtld_bind(obj, reloff) 604 Obj_Entry *obj; 605 Elf_Word reloff; 606 { 607 const Elf_Rela *rela; 608 Elf_Rela ourrela; 609 caddr_t addr; 610 611 if (obj->pltrel != NULL) { 612 const Elf_Rel *rel; 613 614 rel = (const Elf_Rel *)((caddr_t) obj->pltrel + reloff); 615 ourrela.r_info = rel->r_info; 616 ourrela.r_offset = rel->r_offset; 617 ourrela.r_addend = 0; 618 rela = &ourrela; 619 } else { 620 rela = (const Elf_Rela *)((caddr_t) obj->pltrela + reloff); 621 #ifdef __sparc64__ 622 if (ELF_R_TYPE(obj->pltrela->r_info) == R_TYPE(JMP_SLOT)) { 623 /* 624 * XXXX 625 * 626 * The first for PLT entries are reserved. There 627 * is some disagreement whether they should have 628 * associated relocation entries. Both the SPARC 629 * 32-bit and 64-bit ELF specifications say that 630 * they should have relocation entries, but the 631 * 32-bit SPARC binutils do not generate them, 632 * and now the 64-bit SPARC binutils have stopped 633 * generating them too. 634 * 635 * So, to provide binary compatibility, we will 636 * check the first entry, if it is reserved it 637 * should not be of the type JMP_SLOT. If it 638 * is JMP_SLOT, then the 4 reserved entries were 639 * not generated and our index is 4 entries too far. 640 */ 641 rela -= 4; 642 } 643 #endif 644 } 645 646 if (_rtld_relocate_plt_object(obj, rela, &addr, true, true) < 0) 647 _rtld_die(); 648 649 return addr; 650 } 651 652 /* 653 * Relocate newly-loaded shared objects. The argument is a pointer to 654 * the Obj_Entry for the first such object. All objects from the first 655 * to the end of the list of objects are relocated. Returns 0 on success, 656 * or -1 on failure. 657 */ 658 int 659 _rtld_relocate_objects(first, bind_now, dodebug) 660 Obj_Entry *first; 661 bool bind_now; 662 bool dodebug; 663 { 664 Obj_Entry *obj; 665 int ok = 1; 666 667 for (obj = first; obj != NULL; obj = obj->next) { 668 if (obj->nbuckets == 0 || obj->nchains == 0 || 669 obj->buckets == NULL || obj->symtab == NULL || 670 obj->strtab == NULL) { 671 _rtld_error("%s: Shared object has no run-time" 672 " symbol table", obj->path); 673 return -1; 674 } 675 rdbg(dodebug, (" relocating %s (%ld/%ld rel/rela, " 676 "%ld/%ld plt rel/rela)", 677 obj->path, 678 (long)(obj->rellim - obj->rel), 679 (long)(obj->relalim - obj->rela), 680 (long)(obj->pltrellim - obj->pltrel), 681 (long)(obj->pltrelalim - obj->pltrela))); 682 683 if (obj->textrel) { 684 /* 685 * There are relocations to the write-protected text 686 * segment. 687 */ 688 if (mprotect(obj->mapbase, obj->textsize, 689 PROT_READ | PROT_WRITE | PROT_EXEC) == -1) { 690 _rtld_error("%s: Cannot write-enable text " 691 "segment: %s", obj->path, xstrerror(errno)); 692 return -1; 693 } 694 } 695 if (obj->rel != NULL) { 696 /* Process the non-PLT relocations. */ 697 const Elf_Rel *rel; 698 for (rel = obj->rel; rel < obj->rellim; ++rel) { 699 Elf_Rela ourrela; 700 ourrela.r_info = rel->r_info; 701 ourrela.r_offset = rel->r_offset; 702 #if defined(__mips__) 703 /* rel->r_offset is not valid on mips? */ 704 if (ELF_R_TYPE(ourrela.r_info) == R_TYPE(NONE)) 705 ourrela.r_addend = 0; 706 else 707 #endif 708 ourrela.r_addend = 709 *(Elf_Word *)(obj->relocbase + 710 rel->r_offset); 711 712 if (_rtld_relocate_nonplt_object(obj, &ourrela, 713 dodebug) < 0) 714 ok = 0; 715 } 716 } 717 if (obj->rela != NULL) { 718 /* Process the non-PLT relocations. */ 719 const Elf_Rela *rela; 720 for (rela = obj->rela; rela < obj->relalim; ++rela) { 721 if (_rtld_relocate_nonplt_object(obj, rela, 722 dodebug) < 0) 723 ok = 0; 724 } 725 } 726 if (obj->textrel) { /* Re-protected the text segment. */ 727 if (mprotect(obj->mapbase, obj->textsize, 728 PROT_READ | PROT_EXEC) == -1) { 729 _rtld_error("%s: Cannot write-protect text " 730 "segment: %s", obj->path, xstrerror(errno)); 731 return -1; 732 } 733 } 734 /* Process the PLT relocations. */ 735 if (obj->pltrel != NULL) { 736 const Elf_Rel *rel; 737 for (rel = obj->pltrel; rel < obj->pltrellim; ++rel) { 738 Elf_Rela ourrela; 739 ourrela.r_info = rel->r_info; 740 ourrela.r_offset = rel->r_offset; 741 ourrela.r_addend = 742 *(Elf_Word *)(obj->relocbase + 743 rel->r_offset); 744 if (_rtld_relocate_plt_object(obj, &ourrela, 745 NULL, bind_now, dodebug) < 0) 746 ok = 0; 747 } 748 } 749 if (obj->pltrela != NULL) { 750 const Elf_Rela *rela; 751 for (rela = obj->pltrela; rela < obj->pltrelalim; 752 ++rela) { 753 if (_rtld_relocate_plt_object(obj, rela, 754 NULL, bind_now, dodebug) < 0) 755 ok = 0; 756 } 757 } 758 if (!ok) 759 return -1; 760 761 762 /* Set some sanity-checking numbers in the Obj_Entry. */ 763 obj->magic = RTLD_MAGIC; 764 obj->version = RTLD_VERSION; 765 766 /* Fill in the dynamic linker entry points. */ 767 obj->dlopen = _rtld_dlopen; 768 obj->dlsym = _rtld_dlsym; 769 obj->dlerror = _rtld_dlerror; 770 obj->dlclose = _rtld_dlclose; 771 obj->dladdr = _rtld_dladdr; 772 773 /* Set the special PLTGOT entries. */ 774 if (obj->pltgot != NULL) { 775 #if defined(__arm__) || defined(__i386__) || defined(__m68k__) || \ 776 defined(__x86_64__) 777 obj->pltgot[1] = (Elf_Addr) obj; 778 obj->pltgot[2] = (Elf_Addr) & _rtld_bind_start; 779 #endif 780 #if defined(__alpha__) 781 _rtld_setup_alpha_pltgot(obj, dodebug); 782 #endif 783 #if defined(__mips__) 784 _rtld_relocate_mips_got(obj); 785 786 obj->pltgot[0] = (Elf_Addr) & _rtld_bind_start; 787 /* XXX only if obj->pltgot[1] & 0x80000000 ?? */ 788 obj->pltgot[1] |= (Elf_Addr) obj; 789 #endif 790 #if defined(__powerpc__) 791 _rtld_setup_powerpc_plt(obj); 792 #endif 793 #if defined(__sparc__) 794 #if defined(__arch64__) || defined(__sparc_v9__) 795 /* 796 * On sparc64 we got troubles. 797 * 798 * Instructions are 4 bytes long. 799 * Elf[64]_Addr is 8 bytes long, so are our pltglot[] 800 * array entries. 801 * Each PLT entry jumps to PLT0 to enter the dynamic 802 * linker. 803 * Loading an arbitrary 64-bit pointer takes 6 804 * instructions and 2 registers. 805 * 806 * Somehow we need to issue a save to get a new stack 807 * frame, load the address of the dynamic linker, and 808 * jump there, in 8 instructions or less. 809 * 810 * Oh, we need to fill out both PLT0 and PLT1. 811 */ 812 { 813 Elf_Word *entry = (Elf_Word *)obj->pltgot; 814 extern void _rtld_install_plt __P((Elf_Word *, 815 Elf_Addr)); 816 extern void _rtld_bind_start_0 __P((long, 817 long)); 818 extern void _rtld_bind_start_1 __P((long, 819 long)); 820 821 /* Install in entries 0 and 1 */ 822 _rtld_install_plt(&entry[0], 823 (Elf_Addr)&_rtld_bind_start_0); 824 _rtld_install_plt(&entry[8], 825 (Elf_Addr)&_rtld_bind_start_1); 826 827 /* 828 * Install the object reference in first slot 829 * of entry 2. 830 */ 831 obj->pltgot[8] = (Elf_Addr) obj; 832 } 833 #else 834 /* 835 * PLTGOT is the PLT on the sparc. 836 * The first entry holds the call the dynamic linker. 837 * We construct a `call' sequence that transfers 838 * to `_rtld_bind_start()'. 839 * The second entry holds the object identification. 840 * Note: each PLT entry is three words long. 841 */ 842 #define SAVE 0x9de3bfc0 /* i.e. `save %sp,-64,%sp' */ 843 #define CALL 0x40000000 844 #define NOP 0x01000000 845 obj->pltgot[0] = SAVE; 846 obj->pltgot[1] = CALL | 847 ((Elf_Addr)&_rtld_bind_start - 848 (Elf_Addr)&obj->pltgot[1]) >> 2; 849 obj->pltgot[2] = NOP; 850 851 obj->pltgot[3] = (Elf_Addr) obj; 852 #endif /* __arch64__ */ 853 #endif /* __sparc__ */ 854 #if defined(__vax__) 855 obj->pltgot[1] = (Elf_Addr) obj; 856 obj->pltgot[2] = (Elf_Addr) & _rtld_bind_start; 857 #endif 858 } 859 } 860 861 return 0; 862 } 863
Indexes created Tue Sep 30 20:09:53 GMT 2025