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(void *); 53 void *_rtld_tlsdesc_dynamic(void *); 54 55 void _exit(int); 56 57 void 58 init_pltgot(Obj_Entry *obj) 59 { 60 61 if (obj->pltgot != NULL) { 62 obj->pltgot[1] = (Elf_Addr) obj; 63 obj->pltgot[2] = (Elf_Addr) &_rtld_bind_start; 64 } 65 } 66 67 int 68 do_copy_relocations(Obj_Entry *dstobj) 69 { 70 const Obj_Entry *srcobj, *defobj; 71 const Elf_Rela *relalim; 72 const Elf_Rela *rela; 73 const Elf_Sym *srcsym; 74 const Elf_Sym *dstsym; 75 const void *srcaddr; 76 const char *name; 77 void *dstaddr; 78 SymLook req; 79 size_t size; 80 int res; 81 82 /* 83 * COPY relocs are invalid outside of the main program 84 */ 85 assert(dstobj->mainprog); 86 87 relalim = (const Elf_Rela *)((const char *)dstobj->rela + 88 dstobj->relasize); 89 for (rela = dstobj->rela; rela < relalim; rela++) { 90 if (ELF_R_TYPE(rela->r_info) != R_AARCH64_COPY) 91 continue; 92 93 dstaddr = (void *)(dstobj->relocbase + rela->r_offset); 94 dstsym = dstobj->symtab + ELF_R_SYM(rela->r_info); 95 name = dstobj->strtab + dstsym->st_name; 96 size = dstsym->st_size; 97 98 symlook_init(&req, name); 99 req.ventry = fetch_ventry(dstobj, ELF_R_SYM(rela->r_info)); 100 req.flags = SYMLOOK_EARLY; 101 102 for (srcobj = globallist_next(dstobj); srcobj != NULL; 103 srcobj = globallist_next(srcobj)) { 104 res = symlook_obj(&req, srcobj); 105 if (res == 0) { 106 srcsym = req.sym_out; 107 defobj = req.defobj_out; 108 break; 109 } 110 } 111 if (srcobj == NULL) { 112 _rtld_error( 113 "Undefined symbol \"%s\" referenced from COPY relocation in %s", 114 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 int64_t index; 127 Obj_Entry *obj; 128 const Elf_Rela *rela; 129 }; 130 131 int64_t rtld_tlsdesc_handle(struct tls_data *tlsdesc, int flags); 132 133 static struct tls_data * 134 reloc_tlsdesc_alloc(Obj_Entry *obj, const Elf_Rela *rela) 135 { 136 struct tls_data *tlsdesc; 137 138 tlsdesc = xmalloc(sizeof(struct tls_data)); 139 tlsdesc->index = -1; 140 tlsdesc->obj = obj; 141 tlsdesc->rela = rela; 142 143 return (tlsdesc); 144 } 145 146 /* 147 * Look up the symbol to find its tls index 148 */ 149 static int64_t 150 rtld_tlsdesc_handle_locked(struct tls_data *tlsdesc, int flags, 151 RtldLockState *lockstate) 152 { 153 const Elf_Rela *rela; 154 const Elf_Sym *def; 155 const Obj_Entry *defobj; 156 Obj_Entry *obj; 157 158 rela = tlsdesc->rela; 159 obj = tlsdesc->obj; 160 161 def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj, flags, NULL, 162 lockstate); 163 if (def == NULL) 164 rtld_die(); 165 166 tlsdesc->index = defobj->tlsoffset + def->st_value + rela->r_addend; 167 168 return (tlsdesc->index); 169 } 170 171 int64_t 172 rtld_tlsdesc_handle(struct tls_data *tlsdesc, int flags) 173 { 174 RtldLockState lockstate; 175 176 /* We have already found the index, return it */ 177 if (tlsdesc->index >= 0) 178 return (tlsdesc->index); 179 180 wlock_acquire(rtld_bind_lock, &lockstate); 181 /* tlsdesc->index may have been set by another thread */ 182 if (tlsdesc->index == -1) 183 rtld_tlsdesc_handle_locked(tlsdesc, flags, &lockstate); 184 lock_release(rtld_bind_lock, &lockstate); 185 186 return (tlsdesc->index); 187 } 188 189 static void 190 reloc_tlsdesc(Obj_Entry *obj, const Elf_Rela *rela, Elf_Addr *where) 191 { 192 if (ELF_R_SYM(rela->r_info) == 0) { 193 where[0] = (Elf_Addr)_rtld_tlsdesc; 194 where[1] = obj->tlsoffset + rela->r_addend; 195 } else { 196 where[0] = (Elf_Addr)_rtld_tlsdesc_dynamic; 197 where[1] = (Elf_Addr)reloc_tlsdesc_alloc(obj, rela); 198 } 199 } 200 201 /* 202 * Process the PLT relocations. 203 */ 204 int 205 reloc_plt(Obj_Entry *obj) 206 { 207 const Elf_Rela *relalim; 208 const Elf_Rela *rela; 209 210 relalim = (const Elf_Rela *)((const char *)obj->pltrela + obj->pltrelasize); 211 for (rela = obj->pltrela; rela < relalim; rela++) { 212 Elf_Addr *where; 213 214 where = (Elf_Addr *)(obj->relocbase + rela->r_offset); 215 216 switch(ELF_R_TYPE(rela->r_info)) { 217 case R_AARCH64_JUMP_SLOT: 218 *where += (Elf_Addr)obj->relocbase; 219 break; 220 case R_AARCH64_TLSDESC: 221 reloc_tlsdesc(obj, rela, where); 222 break; 223 case R_AARCH64_IRELATIVE: 224 obj->irelative = true; 225 break; 226 default: 227 _rtld_error("Unknown relocation type %u in PLT", 228 (unsigned int)ELF_R_TYPE(rela->r_info)); 229 return (-1); 230 } 231 } 232 233 return (0); 234 } 235 236 /* 237 * LD_BIND_NOW was set - force relocation for all jump slots 238 */ 239 int 240 reloc_jmpslots(Obj_Entry *obj, int flags, RtldLockState *lockstate) 241 { 242 const Obj_Entry *defobj; 243 const Elf_Rela *relalim; 244 const Elf_Rela *rela; 245 const Elf_Sym *def; 246 struct tls_data *tlsdesc; 247 248 relalim = (const Elf_Rela *)((const char *)obj->pltrela + obj->pltrelasize); 249 for (rela = obj->pltrela; rela < relalim; rela++) { 250 Elf_Addr *where, target; 251 252 where = (Elf_Addr *)(obj->relocbase + rela->r_offset); 253 switch(ELF_R_TYPE(rela->r_info)) { 254 case R_AARCH64_JUMP_SLOT: 255 def = find_symdef(ELF_R_SYM(rela->r_info), obj, 256 &defobj, SYMLOOK_IN_PLT | flags, NULL, lockstate); 257 if (def == NULL) 258 return (-1); 259 if (ELF_ST_TYPE(def->st_info) == STT_GNU_IFUNC) { 260 obj->gnu_ifunc = true; 261 continue; 262 } 263 target = (Elf_Addr)(defobj->relocbase + def->st_value); 264 reloc_jmpslot(where, target, defobj, obj, 265 (const Elf_Rel *)rela); 266 break; 267 case R_AARCH64_TLSDESC: 268 if (ELF_R_SYM(rela->r_info) != 0) { 269 tlsdesc = (struct tls_data *)where[1]; 270 if (tlsdesc->index == -1) 271 rtld_tlsdesc_handle_locked(tlsdesc, 272 SYMLOOK_IN_PLT | flags, lockstate); 273 } 274 break; 275 default: 276 _rtld_error("Unknown relocation type %x in jmpslot", 277 (unsigned int)ELF_R_TYPE(rela->r_info)); 278 return (-1); 279 } 280 } 281 282 return (0); 283 } 284 285 int 286 reloc_iresolve(Obj_Entry *obj, struct Struct_RtldLockState *lockstate) 287 { 288 const Elf_Rela *relalim; 289 const Elf_Rela *rela; 290 Elf_Addr *where, target, *ptr; 291 292 if (!obj->irelative) 293 return (0); 294 relalim = (const Elf_Rela *)((const char *)obj->pltrela + obj->pltrelasize); 295 for (rela = obj->pltrela; rela < relalim; rela++) { 296 if (ELF_R_TYPE(rela->r_info) == R_AARCH64_IRELATIVE) { 297 ptr = (Elf_Addr *)(obj->relocbase + rela->r_addend); 298 where = (Elf_Addr *)(obj->relocbase + rela->r_offset); 299 lock_release(rtld_bind_lock, lockstate); 300 target = call_ifunc_resolver(ptr); 301 wlock_acquire(rtld_bind_lock, lockstate); 302 *where = target; 303 } 304 } 305 obj->irelative = false; 306 return (0); 307 } 308 309 int 310 reloc_gnu_ifunc(Obj_Entry *obj, int flags, 311 struct Struct_RtldLockState *lockstate) 312 { 313 const Elf_Rela *relalim; 314 const Elf_Rela *rela; 315 Elf_Addr *where, target; 316 const Elf_Sym *def; 317 const Obj_Entry *defobj; 318 319 if (!obj->gnu_ifunc) 320 return (0); 321 relalim = (const Elf_Rela *)((const char *)obj->pltrela + obj->pltrelasize); 322 for (rela = obj->pltrela; rela < relalim; rela++) { 323 if (ELF_R_TYPE(rela->r_info) == R_AARCH64_JUMP_SLOT) { 324 where = (Elf_Addr *)(obj->relocbase + rela->r_offset); 325 def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj, 326 SYMLOOK_IN_PLT | flags, NULL, lockstate); 327 if (def == NULL) 328 return (-1); 329 if (ELF_ST_TYPE(def->st_info) != STT_GNU_IFUNC) 330 continue; 331 lock_release(rtld_bind_lock, lockstate); 332 target = (Elf_Addr)rtld_resolve_ifunc(defobj, def); 333 wlock_acquire(rtld_bind_lock, lockstate); 334 reloc_jmpslot(where, target, defobj, obj, 335 (const Elf_Rel *)rela); 336 } 337 } 338 obj->gnu_ifunc = false; 339 return (0); 340 } 341 342 Elf_Addr 343 reloc_jmpslot(Elf_Addr *where, Elf_Addr target, 344 const Obj_Entry *defobj __unused, const Obj_Entry *obj __unused, 345 const Elf_Rel *rel) 346 { 347 348 assert(ELF_R_TYPE(rel->r_info) == R_AARCH64_JUMP_SLOT || 349 ELF_R_TYPE(rel->r_info) == R_AARCH64_IRELATIVE); 350 351 if (*where != target && !ld_bind_not) 352 *where = target; 353 return (target); 354 } 355 356 void 357 ifunc_init(Elf_Auxinfo aux_info[__min_size(AT_COUNT)] __unused) 358 { 359 360 } 361 362 void 363 pre_init(void) 364 { 365 366 } 367 368 /* 369 * Process non-PLT relocations 370 */ 371 int 372 reloc_non_plt(Obj_Entry *obj, Obj_Entry *obj_rtld, int flags, 373 RtldLockState *lockstate) 374 { 375 const Obj_Entry *defobj; 376 const Elf_Rela *relalim; 377 const Elf_Rela *rela; 378 const Elf_Sym *def; 379 SymCache *cache; 380 Elf_Addr *where, symval; 381 382 /* 383 * The dynamic loader may be called from a thread, we have 384 * limited amounts of stack available so we cannot use alloca(). 385 */ 386 if (obj == obj_rtld) 387 cache = NULL; 388 else 389 cache = calloc(obj->dynsymcount, sizeof(SymCache)); 390 /* No need to check for NULL here */ 391 392 relalim = (const Elf_Rela *)((const char *)obj->rela + obj->relasize); 393 for (rela = obj->rela; rela < relalim; rela++) { 394 /* 395 * First, resolve symbol for relocations which 396 * reference symbols. 397 */ 398 switch (ELF_R_TYPE(rela->r_info)) { 399 case R_AARCH64_ABS64: 400 case R_AARCH64_GLOB_DAT: 401 case R_AARCH64_TLS_TPREL64: 402 def = find_symdef(ELF_R_SYM(rela->r_info), obj, 403 &defobj, flags, cache, lockstate); 404 if (def == NULL) 405 return (-1); 406 /* 407 * If symbol is IFUNC, only perform relocation 408 * when caller allowed it by passing 409 * SYMLOOK_IFUNC flag. Skip the relocations 410 * otherwise. 411 * 412 * Also error out in case IFUNC relocations 413 * are specified for TLS, which cannot be 414 * usefully interpreted. 415 */ 416 if (ELF_ST_TYPE(def->st_info) == STT_GNU_IFUNC) { 417 switch (ELF_R_TYPE(rela->r_info)) { 418 case R_AARCH64_ABS64: 419 case R_AARCH64_GLOB_DAT: 420 if ((flags & SYMLOOK_IFUNC) == 0) { 421 obj->non_plt_gnu_ifunc = true; 422 continue; 423 } 424 symval = (Elf_Addr)rtld_resolve_ifunc( 425 defobj, def); 426 break; 427 default: 428 _rtld_error("%s: IFUNC for TLS reloc", 429 obj->path); 430 return (-1); 431 } 432 } else { 433 if ((flags & SYMLOOK_IFUNC) != 0) 434 continue; 435 symval = (Elf_Addr)defobj->relocbase + 436 def->st_value; 437 } 438 break; 439 default: 440 if ((flags & SYMLOOK_IFUNC) != 0) 441 continue; 442 } 443 444 where = (Elf_Addr *)(obj->relocbase + rela->r_offset); 445 446 switch (ELF_R_TYPE(rela->r_info)) { 447 case R_AARCH64_ABS64: 448 case R_AARCH64_GLOB_DAT: 449 *where = symval + rela->r_addend; 450 break; 451 case R_AARCH64_COPY: 452 /* 453 * These are deferred until all other relocations have 454 * been done. All we do here is make sure that the 455 * COPY relocation is not in a shared library. They 456 * are allowed only in executable files. 457 */ 458 if (!obj->mainprog) { 459 _rtld_error("%s: Unexpected R_AARCH64_COPY " 460 "relocation in shared library", obj->path); 461 return (-1); 462 } 463 break; 464 case R_AARCH64_TLSDESC: 465 reloc_tlsdesc(obj, rela, where); 466 break; 467 case R_AARCH64_TLS_TPREL64: 468 /* 469 * We lazily allocate offsets for static TLS as we 470 * see the first relocation that references the 471 * TLS block. This allows us to support (small 472 * amounts of) static TLS in dynamically loaded 473 * modules. If we run out of space, we generate an 474 * error. 475 */ 476 if (!defobj->tls_done) { 477 if (!allocate_tls_offset( 478 __DECONST(Obj_Entry *, defobj))) { 479 _rtld_error( 480 "%s: No space available for static " 481 "Thread Local Storage", obj->path); 482 return (-1); 483 } 484 } 485 486 *where = def->st_value + rela->r_addend + 487 defobj->tlsoffset; 488 break; 489 case R_AARCH64_RELATIVE: 490 *where = (Elf_Addr)(obj->relocbase + rela->r_addend); 491 break; 492 default: 493 rtld_printf("%s: Unhandled relocation %lu\n", 494 obj->path, ELF_R_TYPE(rela->r_info)); 495 return (-1); 496 } 497 } 498 499 return (0); 500 } 501 502 void 503 allocate_initial_tls(Obj_Entry *objs) 504 { 505 Elf_Addr **tp; 506 507 /* 508 * Fix the size of the static TLS block by using the maximum 509 * offset allocated so far and adding a bit for dynamic modules to 510 * use. 511 */ 512 tls_static_space = tls_last_offset + tls_last_size + 513 RTLD_STATIC_TLS_EXTRA; 514 515 tp = (Elf_Addr **) allocate_tls(objs, NULL, TLS_TCB_SIZE, 16); 516 517 asm volatile("msr tpidr_el0, %0" : : "r"(tp)); 518 } 519