1 /*- 2 * Copyright (c) 2014-2015 The FreeBSD Foundation 3 * All rights reserved. 4 * 5 * Portions of this software were developed by Andrew Turner 6 * under sponsorship from the FreeBSD Foundation. 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 * 17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 20 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 27 * SUCH DAMAGE. 28 */ 29 30 #include <sys/cdefs.h> 31 __FBSDID("$FreeBSD$"); 32 33 #include <sys/types.h> 34 35 #include <stdlib.h> 36 37 #include "debug.h" 38 #include "rtld.h" 39 #include "rtld_printf.h" 40 41 /* 42 * It is possible for the compiler to emit relocations for unaligned data. 43 * We handle this situation with these inlines. 44 */ 45 #define RELOC_ALIGNED_P(x) \ 46 (((uintptr_t)(x) & (sizeof(void *) - 1)) == 0) 47 48 /* 49 * This is not the correct prototype, but we only need it for 50 * a function pointer to a simple asm function. 51 */ 52 void *_rtld_tlsdesc_static(void *); 53 void *_rtld_tlsdesc_undef(void *); 54 void *_rtld_tlsdesc_dynamic(void *); 55 56 void _exit(int); 57 58 void 59 init_pltgot(Obj_Entry *obj) 60 { 61 62 if (obj->pltgot != NULL) { 63 obj->pltgot[1] = (Elf_Addr) obj; 64 obj->pltgot[2] = (Elf_Addr) &_rtld_bind_start; 65 } 66 } 67 68 int 69 do_copy_relocations(Obj_Entry *dstobj) 70 { 71 const Obj_Entry *srcobj, *defobj; 72 const Elf_Rela *relalim; 73 const Elf_Rela *rela; 74 const Elf_Sym *srcsym; 75 const Elf_Sym *dstsym; 76 const void *srcaddr; 77 const char *name; 78 void *dstaddr; 79 SymLook req; 80 size_t size; 81 int res; 82 83 /* 84 * COPY relocs are invalid outside of the main program 85 */ 86 assert(dstobj->mainprog); 87 88 relalim = (const Elf_Rela *)((const char *)dstobj->rela + 89 dstobj->relasize); 90 for (rela = dstobj->rela; rela < relalim; rela++) { 91 if (ELF_R_TYPE(rela->r_info) != R_AARCH64_COPY) 92 continue; 93 94 dstaddr = (void *)(dstobj->relocbase + rela->r_offset); 95 dstsym = dstobj->symtab + ELF_R_SYM(rela->r_info); 96 name = dstobj->strtab + dstsym->st_name; 97 size = dstsym->st_size; 98 99 symlook_init(&req, name); 100 req.ventry = fetch_ventry(dstobj, ELF_R_SYM(rela->r_info)); 101 req.flags = SYMLOOK_EARLY; 102 103 for (srcobj = globallist_next(dstobj); srcobj != NULL; 104 srcobj = globallist_next(srcobj)) { 105 res = symlook_obj(&req, srcobj); 106 if (res == 0) { 107 srcsym = req.sym_out; 108 defobj = req.defobj_out; 109 break; 110 } 111 } 112 if (srcobj == NULL) { 113 _rtld_error("Undefined symbol \"%s\" referenced from " 114 "COPY relocation in %s", name, dstobj->path); 115 return (-1); 116 } 117 118 srcaddr = (const void *)(defobj->relocbase + srcsym->st_value); 119 memcpy(dstaddr, srcaddr, size); 120 } 121 122 return (0); 123 } 124 125 struct tls_data { 126 Elf_Addr dtv_gen; 127 int tls_index; 128 Elf_Addr tls_offs; 129 }; 130 131 static Elf_Addr 132 reloc_tlsdesc_alloc(int tlsindex, Elf_Addr tlsoffs) 133 { 134 struct tls_data *tlsdesc; 135 136 tlsdesc = xmalloc(sizeof(struct tls_data)); 137 tlsdesc->dtv_gen = tls_dtv_generation; 138 tlsdesc->tls_index = tlsindex; 139 tlsdesc->tls_offs = tlsoffs; 140 141 return ((Elf_Addr)tlsdesc); 142 } 143 144 static void 145 reloc_tlsdesc(const Obj_Entry *obj, const Elf_Rela *rela, Elf_Addr *where, 146 int flags, RtldLockState *lockstate) 147 { 148 const Elf_Sym *def; 149 const Obj_Entry *defobj; 150 Elf_Addr offs; 151 152 153 offs = 0; 154 if (ELF_R_SYM(rela->r_info) != 0) { 155 def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj, flags, 156 NULL, lockstate); 157 if (def == NULL) 158 rtld_die(); 159 offs = def->st_value; 160 obj = defobj; 161 if (def->st_shndx == SHN_UNDEF) { 162 /* Weak undefined thread variable */ 163 where[0] = (Elf_Addr)_rtld_tlsdesc_undef; 164 where[1] = rela->r_addend; 165 return; 166 } 167 } 168 offs += rela->r_addend; 169 170 if (obj->tlsoffset != 0) { 171 /* Variable is in initialy allocated TLS segment */ 172 where[0] = (Elf_Addr)_rtld_tlsdesc_static; 173 where[1] = obj->tlsoffset + offs; 174 } else { 175 /* TLS offest is unknown at load time, use dynamic resolving */ 176 where[0] = (Elf_Addr)_rtld_tlsdesc_dynamic; 177 where[1] = reloc_tlsdesc_alloc(obj->tlsindex, offs); 178 } 179 } 180 181 /* 182 * Process the PLT relocations. 183 */ 184 int 185 reloc_plt(Obj_Entry *obj, int flags, RtldLockState *lockstate) 186 { 187 const Elf_Rela *relalim; 188 const Elf_Rela *rela; 189 190 relalim = (const Elf_Rela *)((const char *)obj->pltrela + 191 obj->pltrelasize); 192 for (rela = obj->pltrela; rela < relalim; rela++) { 193 Elf_Addr *where; 194 195 where = (Elf_Addr *)(obj->relocbase + rela->r_offset); 196 197 switch(ELF_R_TYPE(rela->r_info)) { 198 case R_AARCH64_JUMP_SLOT: 199 *where += (Elf_Addr)obj->relocbase; 200 break; 201 case R_AARCH64_TLSDESC: 202 reloc_tlsdesc(obj, rela, where, SYMLOOK_IN_PLT | flags, 203 lockstate); 204 break; 205 case R_AARCH64_IRELATIVE: 206 obj->irelative = true; 207 break; 208 case R_AARCH64_NONE: 209 break; 210 default: 211 _rtld_error("Unknown relocation type %u in PLT", 212 (unsigned int)ELF_R_TYPE(rela->r_info)); 213 return (-1); 214 } 215 } 216 217 return (0); 218 } 219 220 /* 221 * LD_BIND_NOW was set - force relocation for all jump slots 222 */ 223 int 224 reloc_jmpslots(Obj_Entry *obj, int flags, RtldLockState *lockstate) 225 { 226 const Obj_Entry *defobj; 227 const Elf_Rela *relalim; 228 const Elf_Rela *rela; 229 const Elf_Sym *def; 230 231 if (obj->jmpslots_done) 232 return (0); 233 234 relalim = (const Elf_Rela *)((const char *)obj->pltrela + 235 obj->pltrelasize); 236 for (rela = obj->pltrela; rela < relalim; rela++) { 237 Elf_Addr *where, target; 238 239 where = (Elf_Addr *)(obj->relocbase + rela->r_offset); 240 switch(ELF_R_TYPE(rela->r_info)) { 241 case R_AARCH64_JUMP_SLOT: 242 def = find_symdef(ELF_R_SYM(rela->r_info), obj, 243 &defobj, SYMLOOK_IN_PLT | flags, NULL, lockstate); 244 if (def == NULL) 245 return (-1); 246 if (ELF_ST_TYPE(def->st_info) == STT_GNU_IFUNC) { 247 obj->gnu_ifunc = true; 248 continue; 249 } 250 target = (Elf_Addr)(defobj->relocbase + def->st_value); 251 reloc_jmpslot(where, target, defobj, obj, 252 (const Elf_Rel *)rela); 253 break; 254 } 255 } 256 obj->jmpslots_done = true; 257 258 return (0); 259 } 260 261 static void 262 reloc_iresolve_one(Obj_Entry *obj, const Elf_Rela *rela, 263 RtldLockState *lockstate) 264 { 265 Elf_Addr *where, target, *ptr; 266 267 ptr = (Elf_Addr *)(obj->relocbase + rela->r_addend); 268 where = (Elf_Addr *)(obj->relocbase + rela->r_offset); 269 lock_release(rtld_bind_lock, lockstate); 270 target = call_ifunc_resolver(ptr); 271 wlock_acquire(rtld_bind_lock, lockstate); 272 *where = target; 273 } 274 275 int 276 reloc_iresolve(Obj_Entry *obj, struct Struct_RtldLockState *lockstate) 277 { 278 const Elf_Rela *relalim; 279 const Elf_Rela *rela; 280 281 if (!obj->irelative) 282 return (0); 283 obj->irelative = false; 284 relalim = (const Elf_Rela *)((const char *)obj->pltrela + 285 obj->pltrelasize); 286 for (rela = obj->pltrela; rela < relalim; rela++) { 287 if (ELF_R_TYPE(rela->r_info) == R_AARCH64_IRELATIVE) 288 reloc_iresolve_one(obj, rela, lockstate); 289 } 290 return (0); 291 } 292 293 int 294 reloc_iresolve_nonplt(Obj_Entry *obj, struct Struct_RtldLockState *lockstate) 295 { 296 const Elf_Rela *relalim; 297 const Elf_Rela *rela; 298 299 if (!obj->irelative_nonplt) 300 return (0); 301 obj->irelative_nonplt = false; 302 relalim = (const Elf_Rela *)((const char *)obj->rela + obj->relasize); 303 for (rela = obj->rela; rela < relalim; rela++) { 304 if (ELF_R_TYPE(rela->r_info) == R_AARCH64_IRELATIVE) 305 reloc_iresolve_one(obj, rela, lockstate); 306 } 307 return (0); 308 } 309 310 int 311 reloc_gnu_ifunc(Obj_Entry *obj, int flags, 312 struct Struct_RtldLockState *lockstate) 313 { 314 const Elf_Rela *relalim; 315 const Elf_Rela *rela; 316 Elf_Addr *where, target; 317 const Elf_Sym *def; 318 const Obj_Entry *defobj; 319 320 if (!obj->gnu_ifunc) 321 return (0); 322 relalim = (const Elf_Rela *)((const char *)obj->pltrela + obj->pltrelasize); 323 for (rela = obj->pltrela; rela < relalim; rela++) { 324 if (ELF_R_TYPE(rela->r_info) == R_AARCH64_JUMP_SLOT) { 325 where = (Elf_Addr *)(obj->relocbase + rela->r_offset); 326 def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj, 327 SYMLOOK_IN_PLT | flags, NULL, lockstate); 328 if (def == NULL) 329 return (-1); 330 if (ELF_ST_TYPE(def->st_info) != STT_GNU_IFUNC) 331 continue; 332 lock_release(rtld_bind_lock, lockstate); 333 target = (Elf_Addr)rtld_resolve_ifunc(defobj, def); 334 wlock_acquire(rtld_bind_lock, lockstate); 335 reloc_jmpslot(where, target, defobj, obj, 336 (const Elf_Rel *)rela); 337 } 338 } 339 obj->gnu_ifunc = false; 340 return (0); 341 } 342 343 Elf_Addr 344 reloc_jmpslot(Elf_Addr *where, Elf_Addr target, 345 const Obj_Entry *defobj __unused, const Obj_Entry *obj __unused, 346 const Elf_Rel *rel) 347 { 348 349 assert(ELF_R_TYPE(rel->r_info) == R_AARCH64_JUMP_SLOT || 350 ELF_R_TYPE(rel->r_info) == R_AARCH64_IRELATIVE); 351 352 if (*where != target && !ld_bind_not) 353 *where = target; 354 return (target); 355 } 356 357 void 358 ifunc_init(Elf_Auxinfo aux_info[__min_size(AT_COUNT)] __unused) 359 { 360 361 } 362 363 void 364 pre_init(void) 365 { 366 367 } 368 369 /* 370 * Process non-PLT relocations 371 */ 372 int 373 reloc_non_plt(Obj_Entry *obj, Obj_Entry *obj_rtld, int flags, 374 RtldLockState *lockstate) 375 { 376 const Obj_Entry *defobj; 377 const Elf_Rela *relalim; 378 const Elf_Rela *rela; 379 const Elf_Sym *def; 380 SymCache *cache; 381 Elf_Addr *where, symval; 382 383 /* 384 * The dynamic loader may be called from a thread, we have 385 * limited amounts of stack available so we cannot use alloca(). 386 */ 387 if (obj == obj_rtld) 388 cache = NULL; 389 else 390 cache = calloc(obj->dynsymcount, sizeof(SymCache)); 391 /* No need to check for NULL here */ 392 393 relalim = (const Elf_Rela *)((const char *)obj->rela + obj->relasize); 394 for (rela = obj->rela; rela < relalim; rela++) { 395 /* 396 * First, resolve symbol for relocations which 397 * reference symbols. 398 */ 399 switch (ELF_R_TYPE(rela->r_info)) { 400 case R_AARCH64_ABS64: 401 case R_AARCH64_GLOB_DAT: 402 case R_AARCH64_TLS_TPREL64: 403 case R_AARCH64_TLS_DTPREL64: 404 case R_AARCH64_TLS_DTPMOD64: 405 def = find_symdef(ELF_R_SYM(rela->r_info), obj, 406 &defobj, flags, cache, lockstate); 407 if (def == NULL) 408 return (-1); 409 /* 410 * If symbol is IFUNC, only perform relocation 411 * when caller allowed it by passing 412 * SYMLOOK_IFUNC flag. Skip the relocations 413 * otherwise. 414 * 415 * Also error out in case IFUNC relocations 416 * are specified for TLS, which cannot be 417 * usefully interpreted. 418 */ 419 if (ELF_ST_TYPE(def->st_info) == STT_GNU_IFUNC) { 420 switch (ELF_R_TYPE(rela->r_info)) { 421 case R_AARCH64_ABS64: 422 case R_AARCH64_GLOB_DAT: 423 if ((flags & SYMLOOK_IFUNC) == 0) { 424 obj->non_plt_gnu_ifunc = true; 425 continue; 426 } 427 symval = (Elf_Addr)rtld_resolve_ifunc( 428 defobj, def); 429 break; 430 default: 431 _rtld_error("%s: IFUNC for TLS reloc", 432 obj->path); 433 return (-1); 434 } 435 } else { 436 if ((flags & SYMLOOK_IFUNC) != 0) 437 continue; 438 symval = (Elf_Addr)defobj->relocbase + 439 def->st_value; 440 } 441 break; 442 default: 443 if ((flags & SYMLOOK_IFUNC) != 0) 444 continue; 445 } 446 447 where = (Elf_Addr *)(obj->relocbase + rela->r_offset); 448 449 switch (ELF_R_TYPE(rela->r_info)) { 450 case R_AARCH64_ABS64: 451 case R_AARCH64_GLOB_DAT: 452 *where = symval + rela->r_addend; 453 break; 454 case R_AARCH64_COPY: 455 /* 456 * These are deferred until all other relocations have 457 * been done. All we do here is make sure that the 458 * COPY relocation is not in a shared library. They 459 * are allowed only in executable files. 460 */ 461 if (!obj->mainprog) { 462 _rtld_error("%s: Unexpected R_AARCH64_COPY " 463 "relocation in shared library", obj->path); 464 return (-1); 465 } 466 break; 467 case R_AARCH64_TLSDESC: 468 reloc_tlsdesc(obj, rela, where, flags, lockstate); 469 break; 470 case R_AARCH64_TLS_TPREL64: 471 /* 472 * We lazily allocate offsets for static TLS as we 473 * see the first relocation that references the 474 * TLS block. This allows us to support (small 475 * amounts of) static TLS in dynamically loaded 476 * modules. If we run out of space, we generate an 477 * error. 478 */ 479 if (!defobj->tls_done) { 480 if (!allocate_tls_offset( 481 __DECONST(Obj_Entry *, defobj))) { 482 _rtld_error( 483 "%s: No space available for static " 484 "Thread Local Storage", obj->path); 485 return (-1); 486 } 487 } 488 /* Test weak undefined thread variable */ 489 if (def->st_shndx != SHN_UNDEF) { 490 *where = def->st_value + rela->r_addend + 491 defobj->tlsoffset; 492 } else { 493 /* 494 * XXX We should relocate undefined thread 495 * weak variable address to NULL, but how? 496 * Can we return error in this situation? 497 */ 498 rtld_printf("%s: Unable to relocate undefined " 499 "weak TLS variable\n", obj->path); 500 #if 0 501 return (-1); 502 #else 503 *where = def->st_value + rela->r_addend + 504 defobj->tlsoffset; 505 #endif 506 } 507 break; 508 509 /* 510 * !!! BEWARE !!! 511 * ARM ELF ABI defines TLS_DTPMOD64 as 1029, and TLS_DTPREL64 512 * as 1028. But actual bfd linker and the glibc RTLD linker 513 * treats TLS_DTPMOD64 as 1028 and TLS_DTPREL64 1029. 514 */ 515 case R_AARCH64_TLS_DTPREL64: /* efectively is TLS_DTPMOD64 */ 516 *where += (Elf_Addr)defobj->tlsindex; 517 break; 518 case R_AARCH64_TLS_DTPMOD64: /* efectively is TLS_DTPREL64 */ 519 *where += (Elf_Addr)(def->st_value + rela->r_addend); 520 break; 521 case R_AARCH64_RELATIVE: 522 *where = (Elf_Addr)(obj->relocbase + rela->r_addend); 523 break; 524 case R_AARCH64_NONE: 525 break; 526 case R_AARCH64_IRELATIVE: 527 obj->irelative_nonplt = true; 528 break; 529 default: 530 rtld_printf("%s: Unhandled relocation %lu\n", 531 obj->path, ELF_R_TYPE(rela->r_info)); 532 return (-1); 533 } 534 } 535 536 return (0); 537 } 538 539 void 540 allocate_initial_tls(Obj_Entry *objs) 541 { 542 Elf_Addr **tp; 543 544 /* 545 * Fix the size of the static TLS block by using the maximum 546 * offset allocated so far and adding a bit for dynamic modules to 547 * use. 548 */ 549 tls_static_space = tls_last_offset + tls_last_size + 550 RTLD_STATIC_TLS_EXTRA; 551 552 tp = (Elf_Addr **) allocate_tls(objs, NULL, TLS_TCB_SIZE, 16); 553 554 asm volatile("msr tpidr_el0, %0" : : "r"(tp)); 555 } 556 557 void * 558 __tls_get_addr(tls_index* ti) 559 { 560 char *p; 561 void *_tp; 562 563 __asm __volatile("mrs %0, tpidr_el0" : "=r" (_tp)); 564 p = tls_get_addr_common((Elf_Addr **)(_tp), ti->ti_module, ti->ti_offset); 565 566 return (p); 567 } 568