1 /* 2 * Copyright (C) 2008, 2009 The Android Open Source Project 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * * Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * * Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in 12 * the documentation and/or other materials provided with the 13 * distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 16 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 17 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 18 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 19 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, 20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, 21 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS 22 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED 23 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, 24 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT 25 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26 * SUCH DAMAGE. 27 */ 28 29 #include <dlfcn.h> 30 #include <errno.h> 31 #include <fcntl.h> 32 #include <inttypes.h> 33 #include <pthread.h> 34 #include <stdio.h> 35 #include <stdlib.h> 36 #include <string.h> 37 #include <sys/mman.h> 38 #include <sys/stat.h> 39 #include <unistd.h> 40 41 // Private C library headers. 42 #include "private/bionic_tls.h" 43 #include "private/KernelArgumentBlock.h" 44 #include "private/ScopedPthreadMutexLocker.h" 45 #include "private/ScopedFd.h" 46 47 #include "linker.h" 48 #include "linker_debug.h" 49 #include "linker_environ.h" 50 #include "linker_phdr.h" 51 #include "linker_allocator.h" 52 53 /* >>> IMPORTANT NOTE - READ ME BEFORE MODIFYING <<< 54 * 55 * Do NOT use malloc() and friends or pthread_*() code here. 56 * Don't use printf() either; it's caused mysterious memory 57 * corruption in the past. 58 * The linker runs before we bring up libc and it's easiest 59 * to make sure it does not depend on any complex libc features 60 * 61 * open issues / todo: 62 * 63 * - cleaner error reporting 64 * - after linking, set as much stuff as possible to READONLY 65 * and NOEXEC 66 */ 67 68 #if defined(__LP64__) 69 #define SEARCH_NAME(x) x 70 #else 71 // Nvidia drivers are relying on the bug: 72 // http://code.google.com/p/android/issues/detail?id=6670 73 // so we continue to use base-name lookup for lp32 74 static const char* get_base_name(const char* name) { 75 const char* bname = strrchr(name, '/'); 76 return bname ? bname + 1 : name; 77 } 78 #define SEARCH_NAME(x) get_base_name(x) 79 #endif 80 81 static bool soinfo_link_image(soinfo* si, const android_dlextinfo* extinfo); 82 static ElfW(Addr) get_elf_exec_load_bias(const ElfW(Ehdr)* elf); 83 84 static LinkerAllocator<soinfo> g_soinfo_allocator; 85 static LinkerAllocator<LinkedListEntry<soinfo>> g_soinfo_links_allocator; 86 87 static soinfo* solist; 88 static soinfo* sonext; 89 static soinfo* somain; /* main process, always the one after libdl_info */ 90 91 static const char* const kDefaultLdPaths[] = { 92 #if defined(__LP64__) 93 "/vendor/lib64", 94 "/system/lib64", 95 #else 96 "/vendor/lib", 97 "/system/lib", 98 #endif 99 NULL 100 }; 101 102 #define LDPATH_BUFSIZE (LDPATH_MAX*64) 103 #define LDPATH_MAX 8 104 105 #define LDPRELOAD_BUFSIZE (LDPRELOAD_MAX*64) 106 #define LDPRELOAD_MAX 8 107 108 static char g_ld_library_paths_buffer[LDPATH_BUFSIZE]; 109 static const char* g_ld_library_paths[LDPATH_MAX + 1]; 110 111 static char g_ld_preloads_buffer[LDPRELOAD_BUFSIZE]; 112 static const char* g_ld_preload_names[LDPRELOAD_MAX + 1]; 113 114 static soinfo* g_ld_preloads[LDPRELOAD_MAX + 1]; 115 116 __LIBC_HIDDEN__ int g_ld_debug_verbosity; 117 118 __LIBC_HIDDEN__ abort_msg_t* g_abort_message = NULL; // For debuggerd. 119 120 enum RelocationKind { 121 kRelocAbsolute = 0, 122 kRelocRelative, 123 kRelocCopy, 124 kRelocSymbol, 125 kRelocMax 126 }; 127 128 #if STATS 129 struct linker_stats_t { 130 int count[kRelocMax]; 131 }; 132 133 static linker_stats_t linker_stats; 134 135 static void count_relocation(RelocationKind kind) { 136 ++linker_stats.count[kind]; 137 } 138 #else 139 static void count_relocation(RelocationKind) { 140 } 141 #endif 142 143 #if COUNT_PAGES 144 static unsigned bitmask[4096]; 145 #if defined(__LP64__) 146 #define MARK(offset) \ 147 do { \ 148 if ((((offset) >> 12) >> 5) < 4096) \ 149 bitmask[((offset) >> 12) >> 5] |= (1 << (((offset) >> 12) & 31)); \ 150 } while (0) 151 #else 152 #define MARK(offset) \ 153 do { \ 154 bitmask[((offset) >> 12) >> 3] |= (1 << (((offset) >> 12) & 7)); \ 155 } while (0) 156 #endif 157 #else 158 #define MARK(x) do {} while (0) 159 #endif 160 161 // You shouldn't try to call memory-allocating functions in the dynamic linker. 162 // Guard against the most obvious ones. 163 #define DISALLOW_ALLOCATION(return_type, name, ...) \ 164 return_type name __VA_ARGS__ \ 165 { \ 166 __libc_fatal("ERROR: " #name " called from the dynamic linker!\n"); \ 167 } 168 DISALLOW_ALLOCATION(void*, malloc, (size_t u __unused)); 169 DISALLOW_ALLOCATION(void, free, (void* u __unused)); 170 DISALLOW_ALLOCATION(void*, realloc, (void* u1 __unused, size_t u2 __unused)); 171 DISALLOW_ALLOCATION(void*, calloc, (size_t u1 __unused, size_t u2 __unused)); 172 173 static char tmp_err_buf[768]; 174 static char __linker_dl_err_buf[768]; 175 176 char* linker_get_error_buffer() { 177 return &__linker_dl_err_buf[0]; 178 } 179 180 size_t linker_get_error_buffer_size() { 181 return sizeof(__linker_dl_err_buf); 182 } 183 184 /* 185 * This function is an empty stub where GDB locates a breakpoint to get notified 186 * about linker activity. 187 */ 188 extern "C" void __attribute__((noinline)) __attribute__((visibility("default"))) rtld_db_dlactivity(); 189 190 static pthread_mutex_t g__r_debug_mutex = PTHREAD_MUTEX_INITIALIZER; 191 static r_debug _r_debug = {1, NULL, reinterpret_cast<uintptr_t>(&rtld_db_dlactivity), r_debug::RT_CONSISTENT, 0}; 192 static link_map* r_debug_tail = 0; 193 194 static void insert_soinfo_into_debug_map(soinfo* info) { 195 // Copy the necessary fields into the debug structure. 196 link_map* map = &(info->link_map_head); 197 map->l_addr = info->load_bias; 198 map->l_name = reinterpret_cast<char*>(info->name); 199 map->l_ld = info->dynamic; 200 201 /* Stick the new library at the end of the list. 202 * gdb tends to care more about libc than it does 203 * about leaf libraries, and ordering it this way 204 * reduces the back-and-forth over the wire. 205 */ 206 if (r_debug_tail) { 207 r_debug_tail->l_next = map; 208 map->l_prev = r_debug_tail; 209 map->l_next = 0; 210 } else { 211 _r_debug.r_map = map; 212 map->l_prev = 0; 213 map->l_next = 0; 214 } 215 r_debug_tail = map; 216 } 217 218 static void remove_soinfo_from_debug_map(soinfo* info) { 219 link_map* map = &(info->link_map_head); 220 221 if (r_debug_tail == map) { 222 r_debug_tail = map->l_prev; 223 } 224 225 if (map->l_prev) { 226 map->l_prev->l_next = map->l_next; 227 } 228 if (map->l_next) { 229 map->l_next->l_prev = map->l_prev; 230 } 231 } 232 233 static void notify_gdb_of_load(soinfo* info) { 234 if (info->flags & FLAG_EXE) { 235 // GDB already knows about the main executable 236 return; 237 } 238 239 ScopedPthreadMutexLocker locker(&g__r_debug_mutex); 240 241 _r_debug.r_state = r_debug::RT_ADD; 242 rtld_db_dlactivity(); 243 244 insert_soinfo_into_debug_map(info); 245 246 _r_debug.r_state = r_debug::RT_CONSISTENT; 247 rtld_db_dlactivity(); 248 } 249 250 static void notify_gdb_of_unload(soinfo* info) { 251 if (info->flags & FLAG_EXE) { 252 // GDB already knows about the main executable 253 return; 254 } 255 256 ScopedPthreadMutexLocker locker(&g__r_debug_mutex); 257 258 _r_debug.r_state = r_debug::RT_DELETE; 259 rtld_db_dlactivity(); 260 261 remove_soinfo_from_debug_map(info); 262 263 _r_debug.r_state = r_debug::RT_CONSISTENT; 264 rtld_db_dlactivity(); 265 } 266 267 void notify_gdb_of_libraries() { 268 _r_debug.r_state = r_debug::RT_ADD; 269 rtld_db_dlactivity(); 270 _r_debug.r_state = r_debug::RT_CONSISTENT; 271 rtld_db_dlactivity(); 272 } 273 274 LinkedListEntry<soinfo>* SoinfoListAllocator::alloc() { 275 return g_soinfo_links_allocator.alloc(); 276 } 277 278 void SoinfoListAllocator::free(LinkedListEntry<soinfo>* entry) { 279 g_soinfo_links_allocator.free(entry); 280 } 281 282 static void protect_data(int protection) { 283 g_soinfo_allocator.protect_all(protection); 284 g_soinfo_links_allocator.protect_all(protection); 285 } 286 287 static soinfo* soinfo_alloc(const char* name, struct stat* file_stat) { 288 if (strlen(name) >= SOINFO_NAME_LEN) { 289 DL_ERR("library name \"%s\" too long", name); 290 return NULL; 291 } 292 293 soinfo* si = g_soinfo_allocator.alloc(); 294 295 // Initialize the new element. 296 memset(si, 0, sizeof(soinfo)); 297 strlcpy(si->name, name, sizeof(si->name)); 298 si->flags = FLAG_NEW_SOINFO; 299 300 if (file_stat != NULL) { 301 si->set_st_dev(file_stat->st_dev); 302 si->set_st_ino(file_stat->st_ino); 303 } 304 305 sonext->next = si; 306 sonext = si; 307 308 TRACE("name %s: allocated soinfo @ %p", name, si); 309 return si; 310 } 311 312 static void soinfo_free(soinfo* si) { 313 if (si == NULL) { 314 return; 315 } 316 317 if (si->base != 0 && si->size != 0) { 318 munmap(reinterpret_cast<void*>(si->base), si->size); 319 } 320 321 soinfo *prev = NULL, *trav; 322 323 TRACE("name %s: freeing soinfo @ %p", si->name, si); 324 325 for (trav = solist; trav != NULL; trav = trav->next) { 326 if (trav == si) 327 break; 328 prev = trav; 329 } 330 if (trav == NULL) { 331 /* si was not in solist */ 332 DL_ERR("name \"%s\" is not in solist!", si->name); 333 return; 334 } 335 336 // clear links to/from si 337 si->remove_all_links(); 338 339 /* prev will never be NULL, because the first entry in solist is 340 always the static libdl_info. 341 */ 342 prev->next = si->next; 343 if (si == sonext) { 344 sonext = prev; 345 } 346 347 g_soinfo_allocator.free(si); 348 } 349 350 351 static void parse_path(const char* path, const char* delimiters, 352 const char** array, char* buf, size_t buf_size, size_t max_count) { 353 if (path == NULL) { 354 return; 355 } 356 357 size_t len = strlcpy(buf, path, buf_size); 358 359 size_t i = 0; 360 char* buf_p = buf; 361 while (i < max_count && (array[i] = strsep(&buf_p, delimiters))) { 362 if (*array[i] != '\0') { 363 ++i; 364 } 365 } 366 367 // Forget the last path if we had to truncate; this occurs if the 2nd to 368 // last char isn't '\0' (i.e. wasn't originally a delimiter). 369 if (i > 0 && len >= buf_size && buf[buf_size - 2] != '\0') { 370 array[i - 1] = NULL; 371 } else { 372 array[i] = NULL; 373 } 374 } 375 376 static void parse_LD_LIBRARY_PATH(const char* path) { 377 parse_path(path, ":", g_ld_library_paths, 378 g_ld_library_paths_buffer, sizeof(g_ld_library_paths_buffer), LDPATH_MAX); 379 } 380 381 static void parse_LD_PRELOAD(const char* path) { 382 // We have historically supported ':' as well as ' ' in LD_PRELOAD. 383 parse_path(path, " :", g_ld_preload_names, 384 g_ld_preloads_buffer, sizeof(g_ld_preloads_buffer), LDPRELOAD_MAX); 385 } 386 387 #if defined(__arm__) 388 389 /* For a given PC, find the .so that it belongs to. 390 * Returns the base address of the .ARM.exidx section 391 * for that .so, and the number of 8-byte entries 392 * in that section (via *pcount). 393 * 394 * Intended to be called by libc's __gnu_Unwind_Find_exidx(). 395 * 396 * This function is exposed via dlfcn.cpp and libdl.so. 397 */ 398 _Unwind_Ptr dl_unwind_find_exidx(_Unwind_Ptr pc, int* pcount) { 399 unsigned addr = (unsigned)pc; 400 401 for (soinfo* si = solist; si != 0; si = si->next) { 402 if ((addr >= si->base) && (addr < (si->base + si->size))) { 403 *pcount = si->ARM_exidx_count; 404 return (_Unwind_Ptr)si->ARM_exidx; 405 } 406 } 407 *pcount = 0; 408 return NULL; 409 } 410 411 #endif 412 413 /* Here, we only have to provide a callback to iterate across all the 414 * loaded libraries. gcc_eh does the rest. */ 415 int dl_iterate_phdr(int (*cb)(dl_phdr_info* info, size_t size, void* data), void* data) { 416 int rv = 0; 417 for (soinfo* si = solist; si != NULL; si = si->next) { 418 dl_phdr_info dl_info; 419 dl_info.dlpi_addr = si->link_map_head.l_addr; 420 dl_info.dlpi_name = si->link_map_head.l_name; 421 dl_info.dlpi_phdr = si->phdr; 422 dl_info.dlpi_phnum = si->phnum; 423 rv = cb(&dl_info, sizeof(dl_phdr_info), data); 424 if (rv != 0) { 425 break; 426 } 427 } 428 return rv; 429 } 430 431 static ElfW(Sym)* soinfo_elf_lookup(soinfo* si, unsigned hash, const char* name) { 432 ElfW(Sym)* symtab = si->symtab; 433 const char* strtab = si->strtab; 434 435 TRACE_TYPE(LOOKUP, "SEARCH %s in %s@%p %x %zd", 436 name, si->name, reinterpret_cast<void*>(si->base), hash, hash % si->nbucket); 437 438 for (unsigned n = si->bucket[hash % si->nbucket]; n != 0; n = si->chain[n]) { 439 ElfW(Sym)* s = symtab + n; 440 if (strcmp(strtab + s->st_name, name)) continue; 441 442 /* only concern ourselves with global and weak symbol definitions */ 443 switch (ELF_ST_BIND(s->st_info)) { 444 case STB_GLOBAL: 445 case STB_WEAK: 446 if (s->st_shndx == SHN_UNDEF) { 447 continue; 448 } 449 450 TRACE_TYPE(LOOKUP, "FOUND %s in %s (%p) %zd", 451 name, si->name, reinterpret_cast<void*>(s->st_value), 452 static_cast<size_t>(s->st_size)); 453 return s; 454 case STB_LOCAL: 455 continue; 456 default: 457 __libc_fatal("ERROR: Unexpected ST_BIND value: %d for '%s' in '%s'", 458 ELF_ST_BIND(s->st_info), name, si->name); 459 } 460 } 461 462 TRACE_TYPE(LOOKUP, "NOT FOUND %s in %s@%p %x %zd", 463 name, si->name, reinterpret_cast<void*>(si->base), hash, hash % si->nbucket); 464 465 466 return NULL; 467 } 468 469 static unsigned elfhash(const char* _name) { 470 const unsigned char* name = reinterpret_cast<const unsigned char*>(_name); 471 unsigned h = 0, g; 472 473 while (*name) { 474 h = (h << 4) + *name++; 475 g = h & 0xf0000000; 476 h ^= g; 477 h ^= g >> 24; 478 } 479 return h; 480 } 481 482 static ElfW(Sym)* soinfo_do_lookup(soinfo* si, const char* name, soinfo** lsi, soinfo* needed[]) { 483 unsigned elf_hash = elfhash(name); 484 ElfW(Sym)* s = NULL; 485 486 if (si != NULL && somain != NULL) { 487 /* 488 * Local scope is executable scope. Just start looking into it right away 489 * for the shortcut. 490 */ 491 492 if (si == somain) { 493 s = soinfo_elf_lookup(si, elf_hash, name); 494 if (s != NULL) { 495 *lsi = si; 496 goto done; 497 } 498 499 /* Next, look for it in the preloads list */ 500 for (int i = 0; g_ld_preloads[i] != NULL; i++) { 501 s = soinfo_elf_lookup(g_ld_preloads[i], elf_hash, name); 502 if (s != NULL) { 503 *lsi = g_ld_preloads[i]; 504 goto done; 505 } 506 } 507 } else { 508 /* Order of symbol lookup is controlled by DT_SYMBOLIC flag */ 509 510 /* 511 * If this object was built with symbolic relocations disabled, the 512 * first place to look to resolve external references is the main 513 * executable. 514 */ 515 516 if (!si->has_DT_SYMBOLIC) { 517 DEBUG("%s: looking up %s in executable %s", 518 si->name, name, somain->name); 519 s = soinfo_elf_lookup(somain, elf_hash, name); 520 if (s != NULL) { 521 *lsi = somain; 522 goto done; 523 } 524 525 /* Next, look for it in the preloads list */ 526 for (int i = 0; g_ld_preloads[i] != NULL; i++) { 527 s = soinfo_elf_lookup(g_ld_preloads[i], elf_hash, name); 528 if (s != NULL) { 529 *lsi = g_ld_preloads[i]; 530 goto done; 531 } 532 } 533 } 534 535 /* Look for symbols in the local scope (the object who is 536 * searching). This happens with C++ templates on x86 for some 537 * reason. 538 * 539 * Notes on weak symbols: 540 * The ELF specs are ambiguous about treatment of weak definitions in 541 * dynamic linking. Some systems return the first definition found 542 * and some the first non-weak definition. This is system dependent. 543 * Here we return the first definition found for simplicity. */ 544 545 s = soinfo_elf_lookup(si, elf_hash, name); 546 if (s != NULL) { 547 *lsi = si; 548 goto done; 549 } 550 551 /* 552 * If this object was built with -Bsymbolic and symbol is not found 553 * in the local scope, try to find the symbol in the main executable. 554 */ 555 556 if (si->has_DT_SYMBOLIC) { 557 DEBUG("%s: looking up %s in executable %s after local scope", 558 si->name, name, somain->name); 559 s = soinfo_elf_lookup(somain, elf_hash, name); 560 if (s != NULL) { 561 *lsi = somain; 562 goto done; 563 } 564 565 /* Next, look for it in the preloads list */ 566 for (int i = 0; g_ld_preloads[i] != NULL; i++) { 567 s = soinfo_elf_lookup(g_ld_preloads[i], elf_hash, name); 568 if (s != NULL) { 569 *lsi = g_ld_preloads[i]; 570 goto done; 571 } 572 } 573 } 574 } 575 } 576 577 for (int i = 0; needed[i] != NULL; i++) { 578 DEBUG("%s: looking up %s in %s", 579 si->name, name, needed[i]->name); 580 s = soinfo_elf_lookup(needed[i], elf_hash, name); 581 if (s != NULL) { 582 *lsi = needed[i]; 583 goto done; 584 } 585 } 586 587 done: 588 if (s != NULL) { 589 TRACE_TYPE(LOOKUP, "si %s sym %s s->st_value = %p, " 590 "found in %s, base = %p, load bias = %p", 591 si->name, name, reinterpret_cast<void*>(s->st_value), 592 (*lsi)->name, reinterpret_cast<void*>((*lsi)->base), 593 reinterpret_cast<void*>((*lsi)->load_bias)); 594 return s; 595 } 596 597 return NULL; 598 } 599 600 // Another soinfo list allocator to use in dlsym. We don't reuse 601 // SoinfoListAllocator because it is write-protected most of the time. 602 static LinkerAllocator<LinkedListEntry<soinfo>> g_soinfo_list_allocator_rw; 603 class SoinfoListAllocatorRW { 604 public: 605 static LinkedListEntry<soinfo>* alloc() { 606 return g_soinfo_list_allocator_rw.alloc(); 607 } 608 609 static void free(LinkedListEntry<soinfo>* ptr) { 610 g_soinfo_list_allocator_rw.free(ptr); 611 } 612 }; 613 614 // This is used by dlsym(3). It performs symbol lookup only within the 615 // specified soinfo object and its dependencies in breadth first order. 616 ElfW(Sym)* dlsym_handle_lookup(soinfo* si, soinfo** found, const char* name) { 617 LinkedList<soinfo, SoinfoListAllocatorRW> visit_list; 618 LinkedList<soinfo, SoinfoListAllocatorRW> visited; 619 visit_list.push_back(si); 620 soinfo* current_soinfo; 621 while ((current_soinfo = visit_list.pop_front()) != nullptr) { 622 if (visited.contains(current_soinfo)) { 623 continue; 624 } 625 626 ElfW(Sym)* result = soinfo_elf_lookup(current_soinfo, elfhash(name), name); 627 628 if (result != nullptr) { 629 *found = current_soinfo; 630 visit_list.clear(); 631 visited.clear(); 632 return result; 633 } 634 visited.push_back(current_soinfo); 635 636 current_soinfo->get_children().for_each([&](soinfo* child) { 637 visit_list.push_back(child); 638 }); 639 } 640 641 visit_list.clear(); 642 visited.clear(); 643 return nullptr; 644 } 645 646 /* This is used by dlsym(3) to performs a global symbol lookup. If the 647 start value is null (for RTLD_DEFAULT), the search starts at the 648 beginning of the global solist. Otherwise the search starts at the 649 specified soinfo (for RTLD_NEXT). 650 */ 651 ElfW(Sym)* dlsym_linear_lookup(const char* name, soinfo** found, soinfo* start) { 652 unsigned elf_hash = elfhash(name); 653 654 if (start == NULL) { 655 start = solist; 656 } 657 658 ElfW(Sym)* s = NULL; 659 for (soinfo* si = start; (s == NULL) && (si != NULL); si = si->next) { 660 s = soinfo_elf_lookup(si, elf_hash, name); 661 if (s != NULL) { 662 *found = si; 663 break; 664 } 665 } 666 667 if (s != NULL) { 668 TRACE_TYPE(LOOKUP, "%s s->st_value = %p, found->base = %p", 669 name, reinterpret_cast<void*>(s->st_value), reinterpret_cast<void*>((*found)->base)); 670 } 671 672 return s; 673 } 674 675 soinfo* find_containing_library(const void* p) { 676 ElfW(Addr) address = reinterpret_cast<ElfW(Addr)>(p); 677 for (soinfo* si = solist; si != NULL; si = si->next) { 678 if (address >= si->base && address - si->base < si->size) { 679 return si; 680 } 681 } 682 return NULL; 683 } 684 685 ElfW(Sym)* dladdr_find_symbol(soinfo* si, const void* addr) { 686 ElfW(Addr) soaddr = reinterpret_cast<ElfW(Addr)>(addr) - si->base; 687 688 // Search the library's symbol table for any defined symbol which 689 // contains this address. 690 for (size_t i = 0; i < si->nchain; ++i) { 691 ElfW(Sym)* sym = &si->symtab[i]; 692 if (sym->st_shndx != SHN_UNDEF && 693 soaddr >= sym->st_value && 694 soaddr < sym->st_value + sym->st_size) { 695 return sym; 696 } 697 } 698 699 return NULL; 700 } 701 702 static int open_library_on_path(const char* name, const char* const paths[]) { 703 char buf[512]; 704 for (size_t i = 0; paths[i] != NULL; ++i) { 705 int n = __libc_format_buffer(buf, sizeof(buf), "%s/%s", paths[i], name); 706 if (n < 0 || n >= static_cast<int>(sizeof(buf))) { 707 PRINT("Warning: ignoring very long library path: %s/%s", paths[i], name); 708 continue; 709 } 710 int fd = TEMP_FAILURE_RETRY(open(buf, O_RDONLY | O_CLOEXEC)); 711 if (fd != -1) { 712 return fd; 713 } 714 } 715 return -1; 716 } 717 718 static int open_library(const char* name) { 719 TRACE("[ opening %s ]", name); 720 721 // If the name contains a slash, we should attempt to open it directly and not search the paths. 722 if (strchr(name, '/') != NULL) { 723 int fd = TEMP_FAILURE_RETRY(open(name, O_RDONLY | O_CLOEXEC)); 724 if (fd != -1) { 725 return fd; 726 } 727 // ...but nvidia binary blobs (at least) rely on this behavior, so fall through for now. 728 #if defined(__LP64__) 729 return -1; 730 #endif 731 } 732 733 // Otherwise we try LD_LIBRARY_PATH first, and fall back to the built-in well known paths. 734 int fd = open_library_on_path(name, g_ld_library_paths); 735 if (fd == -1) { 736 fd = open_library_on_path(name, kDefaultLdPaths); 737 } 738 return fd; 739 } 740 741 static soinfo* load_library(const char* name, int dlflags, const android_dlextinfo* extinfo) { 742 int fd = -1; 743 ScopedFd file_guard(-1); 744 745 if (extinfo != NULL && (extinfo->flags & ANDROID_DLEXT_USE_LIBRARY_FD) != 0) { 746 fd = extinfo->library_fd; 747 } else { 748 // Open the file. 749 fd = open_library(name); 750 if (fd == -1) { 751 DL_ERR("library \"%s\" not found", name); 752 return NULL; 753 } 754 755 file_guard.reset(fd); 756 } 757 758 ElfReader elf_reader(name, fd); 759 760 struct stat file_stat; 761 if (TEMP_FAILURE_RETRY(fstat(fd, &file_stat)) != 0) { 762 DL_ERR("unable to stat file for the library %s: %s", name, strerror(errno)); 763 return NULL; 764 } 765 766 // Check for symlink and other situations where 767 // file can have different names. 768 for (soinfo* si = solist; si != NULL; si = si->next) { 769 if (si->get_st_dev() != 0 && 770 si->get_st_ino() != 0 && 771 si->get_st_dev() == file_stat.st_dev && 772 si->get_st_ino() == file_stat.st_ino) { 773 TRACE("library \"%s\" is already loaded under different name/path \"%s\" - will return existing soinfo", name, si->name); 774 return si; 775 } 776 } 777 778 if ((dlflags & RTLD_NOLOAD) != 0) { 779 return NULL; 780 } 781 782 // Read the ELF header and load the segments. 783 if (!elf_reader.Load(extinfo)) { 784 return NULL; 785 } 786 787 soinfo* si = soinfo_alloc(SEARCH_NAME(name), &file_stat); 788 if (si == NULL) { 789 return NULL; 790 } 791 si->base = elf_reader.load_start(); 792 si->size = elf_reader.load_size(); 793 si->load_bias = elf_reader.load_bias(); 794 si->phnum = elf_reader.phdr_count(); 795 si->phdr = elf_reader.loaded_phdr(); 796 797 // At this point we know that whatever is loaded @ base is a valid ELF 798 // shared library whose segments are properly mapped in. 799 TRACE("[ load_library base=%p size=%zu name='%s' ]", 800 reinterpret_cast<void*>(si->base), si->size, si->name); 801 802 if (!soinfo_link_image(si, extinfo)) { 803 soinfo_free(si); 804 return NULL; 805 } 806 807 return si; 808 } 809 810 static soinfo *find_loaded_library_by_name(const char* name) { 811 const char* search_name = SEARCH_NAME(name); 812 for (soinfo* si = solist; si != NULL; si = si->next) { 813 if (!strcmp(search_name, si->name)) { 814 return si; 815 } 816 } 817 return NULL; 818 } 819 820 static soinfo* find_library_internal(const char* name, int dlflags, const android_dlextinfo* extinfo) { 821 if (name == NULL) { 822 return somain; 823 } 824 825 soinfo* si = find_loaded_library_by_name(name); 826 827 // Library might still be loaded, the accurate detection 828 // of this fact is done by load_library 829 if (si == NULL) { 830 TRACE("[ '%s' has not been found by name. Trying harder...]", name); 831 si = load_library(name, dlflags, extinfo); 832 } 833 834 if (si != NULL && (si->flags & FLAG_LINKED) == 0) { 835 DL_ERR("recursive link to \"%s\"", si->name); 836 return NULL; 837 } 838 839 return si; 840 } 841 842 static soinfo* find_library(const char* name, int dlflags, const android_dlextinfo* extinfo) { 843 soinfo* si = find_library_internal(name, dlflags, extinfo); 844 if (si != NULL) { 845 si->ref_count++; 846 } 847 return si; 848 } 849 850 static void soinfo_unload(soinfo* si) { 851 if (si->ref_count == 1) { 852 TRACE("unloading '%s'", si->name); 853 si->CallDestructors(); 854 855 if ((si->flags | FLAG_NEW_SOINFO) != 0) { 856 si->get_children().for_each([&] (soinfo* child) { 857 TRACE("%s needs to unload %s", si->name, child->name); 858 soinfo_unload(child); 859 }); 860 } else { 861 for (ElfW(Dyn)* d = si->dynamic; d->d_tag != DT_NULL; ++d) { 862 if (d->d_tag == DT_NEEDED) { 863 const char* library_name = si->strtab + d->d_un.d_val; 864 TRACE("%s needs to unload %s", si->name, library_name); 865 soinfo* needed = find_library(library_name, RTLD_NOLOAD, NULL); 866 if (needed != NULL) { 867 soinfo_unload(needed); 868 } else { 869 // Not found: for example if symlink was deleted between dlopen and dlclose 870 // Since we cannot really handle errors at this point - print and continue. 871 PRINT("warning: couldn't find %s needed by %s on unload.", library_name, si->name); 872 } 873 } 874 } 875 } 876 877 notify_gdb_of_unload(si); 878 si->ref_count = 0; 879 soinfo_free(si); 880 } else { 881 si->ref_count--; 882 TRACE("not unloading '%s', decrementing ref_count to %zd", si->name, si->ref_count); 883 } 884 } 885 886 void do_android_get_LD_LIBRARY_PATH(char* buffer, size_t buffer_size) { 887 // Use basic string manipulation calls to avoid snprintf. 888 // snprintf indirectly calls pthread_getspecific to get the size of a buffer. 889 // When debug malloc is enabled, this call returns 0. This in turn causes 890 // snprintf to do nothing, which causes libraries to fail to load. 891 // See b/17302493 for further details. 892 // Once the above bug is fixed, this code can be modified to use 893 // snprintf again. 894 size_t required_len = strlen(kDefaultLdPaths[0]) + strlen(kDefaultLdPaths[1]) + 2; 895 if (buffer_size < required_len) { 896 __libc_fatal("android_get_LD_LIBRARY_PATH failed, buffer too small: buffer len %zu, required len %zu", 897 buffer_size, required_len); 898 } 899 char* end = stpcpy(buffer, kDefaultLdPaths[0]); 900 *end = ':'; 901 strcpy(end + 1, kDefaultLdPaths[1]); 902 } 903 904 void do_android_update_LD_LIBRARY_PATH(const char* ld_library_path) { 905 if (!get_AT_SECURE()) { 906 parse_LD_LIBRARY_PATH(ld_library_path); 907 } 908 } 909 910 soinfo* do_dlopen(const char* name, int flags, const android_dlextinfo* extinfo) { 911 if ((flags & ~(RTLD_NOW|RTLD_LAZY|RTLD_LOCAL|RTLD_GLOBAL|RTLD_NOLOAD)) != 0) { 912 DL_ERR("invalid flags to dlopen: %x", flags); 913 return NULL; 914 } 915 if (extinfo != NULL && ((extinfo->flags & ~(ANDROID_DLEXT_VALID_FLAG_BITS)) != 0)) { 916 DL_ERR("invalid extended flags to android_dlopen_ext: %" PRIx64, extinfo->flags); 917 return NULL; 918 } 919 protect_data(PROT_READ | PROT_WRITE); 920 soinfo* si = find_library(name, flags, extinfo); 921 if (si != NULL) { 922 si->CallConstructors(); 923 } 924 protect_data(PROT_READ); 925 return si; 926 } 927 928 void do_dlclose(soinfo* si) { 929 protect_data(PROT_READ | PROT_WRITE); 930 soinfo_unload(si); 931 protect_data(PROT_READ); 932 } 933 934 #if defined(USE_RELA) 935 static int soinfo_relocate(soinfo* si, ElfW(Rela)* rela, unsigned count, soinfo* needed[]) { 936 ElfW(Sym)* s; 937 soinfo* lsi; 938 939 for (size_t idx = 0; idx < count; ++idx, ++rela) { 940 unsigned type = ELFW(R_TYPE)(rela->r_info); 941 unsigned sym = ELFW(R_SYM)(rela->r_info); 942 ElfW(Addr) reloc = static_cast<ElfW(Addr)>(rela->r_offset + si->load_bias); 943 ElfW(Addr) sym_addr = 0; 944 const char* sym_name = NULL; 945 946 DEBUG("Processing '%s' relocation at index %zd", si->name, idx); 947 if (type == 0) { // R_*_NONE 948 continue; 949 } 950 if (sym != 0) { 951 sym_name = reinterpret_cast<const char*>(si->strtab + si->symtab[sym].st_name); 952 s = soinfo_do_lookup(si, sym_name, &lsi, needed); 953 if (s == NULL) { 954 // We only allow an undefined symbol if this is a weak reference... 955 s = &si->symtab[sym]; 956 if (ELF_ST_BIND(s->st_info) != STB_WEAK) { 957 DL_ERR("cannot locate symbol \"%s\" referenced by \"%s\"...", sym_name, si->name); 958 return -1; 959 } 960 961 /* IHI0044C AAELF 4.5.1.1: 962 963 Libraries are not searched to resolve weak references. 964 It is not an error for a weak reference to remain unsatisfied. 965 966 During linking, the value of an undefined weak reference is: 967 - Zero if the relocation type is absolute 968 - The address of the place if the relocation is pc-relative 969 - The address of nominal base address if the relocation 970 type is base-relative. 971 */ 972 973 switch (type) { 974 #if defined(__aarch64__) 975 case R_AARCH64_JUMP_SLOT: 976 case R_AARCH64_GLOB_DAT: 977 case R_AARCH64_ABS64: 978 case R_AARCH64_ABS32: 979 case R_AARCH64_ABS16: 980 case R_AARCH64_RELATIVE: 981 /* 982 * The sym_addr was initialized to be zero above, or the relocation 983 * code below does not care about value of sym_addr. 984 * No need to do anything. 985 */ 986 break; 987 #elif defined(__x86_64__) 988 case R_X86_64_JUMP_SLOT: 989 case R_X86_64_GLOB_DAT: 990 case R_X86_64_32: 991 case R_X86_64_64: 992 case R_X86_64_RELATIVE: 993 // No need to do anything. 994 break; 995 case R_X86_64_PC32: 996 sym_addr = reloc; 997 break; 998 #endif 999 default: 1000 DL_ERR("unknown weak reloc type %d @ %p (%zu)", type, rela, idx); 1001 return -1; 1002 } 1003 } else { 1004 // We got a definition. 1005 sym_addr = static_cast<ElfW(Addr)>(s->st_value + lsi->load_bias); 1006 } 1007 count_relocation(kRelocSymbol); 1008 } else { 1009 s = NULL; 1010 } 1011 1012 switch (type) { 1013 #if defined(__aarch64__) 1014 case R_AARCH64_JUMP_SLOT: 1015 count_relocation(kRelocAbsolute); 1016 MARK(rela->r_offset); 1017 TRACE_TYPE(RELO, "RELO JMP_SLOT %16llx <- %16llx %s\n", 1018 reloc, (sym_addr + rela->r_addend), sym_name); 1019 *reinterpret_cast<ElfW(Addr)*>(reloc) = (sym_addr + rela->r_addend); 1020 break; 1021 case R_AARCH64_GLOB_DAT: 1022 count_relocation(kRelocAbsolute); 1023 MARK(rela->r_offset); 1024 TRACE_TYPE(RELO, "RELO GLOB_DAT %16llx <- %16llx %s\n", 1025 reloc, (sym_addr + rela->r_addend), sym_name); 1026 *reinterpret_cast<ElfW(Addr)*>(reloc) = (sym_addr + rela->r_addend); 1027 break; 1028 case R_AARCH64_ABS64: 1029 count_relocation(kRelocAbsolute); 1030 MARK(rela->r_offset); 1031 TRACE_TYPE(RELO, "RELO ABS64 %16llx <- %16llx %s\n", 1032 reloc, (sym_addr + rela->r_addend), sym_name); 1033 *reinterpret_cast<ElfW(Addr)*>(reloc) += (sym_addr + rela->r_addend); 1034 break; 1035 case R_AARCH64_ABS32: 1036 count_relocation(kRelocAbsolute); 1037 MARK(rela->r_offset); 1038 TRACE_TYPE(RELO, "RELO ABS32 %16llx <- %16llx %s\n", 1039 reloc, (sym_addr + rela->r_addend), sym_name); 1040 if ((static_cast<ElfW(Addr)>(INT32_MIN) <= (*reinterpret_cast<ElfW(Addr)*>(reloc) + (sym_addr + rela->r_addend))) && 1041 ((*reinterpret_cast<ElfW(Addr)*>(reloc) + (sym_addr + rela->r_addend)) <= static_cast<ElfW(Addr)>(UINT32_MAX))) { 1042 *reinterpret_cast<ElfW(Addr)*>(reloc) += (sym_addr + rela->r_addend); 1043 } else { 1044 DL_ERR("0x%016llx out of range 0x%016llx to 0x%016llx", 1045 (*reinterpret_cast<ElfW(Addr)*>(reloc) + (sym_addr + rela->r_addend)), 1046 static_cast<ElfW(Addr)>(INT32_MIN), 1047 static_cast<ElfW(Addr)>(UINT32_MAX)); 1048 return -1; 1049 } 1050 break; 1051 case R_AARCH64_ABS16: 1052 count_relocation(kRelocAbsolute); 1053 MARK(rela->r_offset); 1054 TRACE_TYPE(RELO, "RELO ABS16 %16llx <- %16llx %s\n", 1055 reloc, (sym_addr + rela->r_addend), sym_name); 1056 if ((static_cast<ElfW(Addr)>(INT16_MIN) <= (*reinterpret_cast<ElfW(Addr)*>(reloc) + (sym_addr + rela->r_addend))) && 1057 ((*reinterpret_cast<ElfW(Addr)*>(reloc) + (sym_addr + rela->r_addend)) <= static_cast<ElfW(Addr)>(UINT16_MAX))) { 1058 *reinterpret_cast<ElfW(Addr)*>(reloc) += (sym_addr + rela->r_addend); 1059 } else { 1060 DL_ERR("0x%016llx out of range 0x%016llx to 0x%016llx", 1061 (*reinterpret_cast<ElfW(Addr)*>(reloc) + (sym_addr + rela->r_addend)), 1062 static_cast<ElfW(Addr)>(INT16_MIN), 1063 static_cast<ElfW(Addr)>(UINT16_MAX)); 1064 return -1; 1065 } 1066 break; 1067 case R_AARCH64_PREL64: 1068 count_relocation(kRelocRelative); 1069 MARK(rela->r_offset); 1070 TRACE_TYPE(RELO, "RELO REL64 %16llx <- %16llx - %16llx %s\n", 1071 reloc, (sym_addr + rela->r_addend), rela->r_offset, sym_name); 1072 *reinterpret_cast<ElfW(Addr)*>(reloc) += (sym_addr + rela->r_addend) - rela->r_offset; 1073 break; 1074 case R_AARCH64_PREL32: 1075 count_relocation(kRelocRelative); 1076 MARK(rela->r_offset); 1077 TRACE_TYPE(RELO, "RELO REL32 %16llx <- %16llx - %16llx %s\n", 1078 reloc, (sym_addr + rela->r_addend), rela->r_offset, sym_name); 1079 if ((static_cast<ElfW(Addr)>(INT32_MIN) <= (*reinterpret_cast<ElfW(Addr)*>(reloc) + ((sym_addr + rela->r_addend) - rela->r_offset))) && 1080 ((*reinterpret_cast<ElfW(Addr)*>(reloc) + ((sym_addr + rela->r_addend) - rela->r_offset)) <= static_cast<ElfW(Addr)>(UINT32_MAX))) { 1081 *reinterpret_cast<ElfW(Addr)*>(reloc) += ((sym_addr + rela->r_addend) - rela->r_offset); 1082 } else { 1083 DL_ERR("0x%016llx out of range 0x%016llx to 0x%016llx", 1084 (*reinterpret_cast<ElfW(Addr)*>(reloc) + ((sym_addr + rela->r_addend) - rela->r_offset)), 1085 static_cast<ElfW(Addr)>(INT32_MIN), 1086 static_cast<ElfW(Addr)>(UINT32_MAX)); 1087 return -1; 1088 } 1089 break; 1090 case R_AARCH64_PREL16: 1091 count_relocation(kRelocRelative); 1092 MARK(rela->r_offset); 1093 TRACE_TYPE(RELO, "RELO REL16 %16llx <- %16llx - %16llx %s\n", 1094 reloc, (sym_addr + rela->r_addend), rela->r_offset, sym_name); 1095 if ((static_cast<ElfW(Addr)>(INT16_MIN) <= (*reinterpret_cast<ElfW(Addr)*>(reloc) + ((sym_addr + rela->r_addend) - rela->r_offset))) && 1096 ((*reinterpret_cast<ElfW(Addr)*>(reloc) + ((sym_addr + rela->r_addend) - rela->r_offset)) <= static_cast<ElfW(Addr)>(UINT16_MAX))) { 1097 *reinterpret_cast<ElfW(Addr)*>(reloc) += ((sym_addr + rela->r_addend) - rela->r_offset); 1098 } else { 1099 DL_ERR("0x%016llx out of range 0x%016llx to 0x%016llx", 1100 (*reinterpret_cast<ElfW(Addr)*>(reloc) + ((sym_addr + rela->r_addend) - rela->r_offset)), 1101 static_cast<ElfW(Addr)>(INT16_MIN), 1102 static_cast<ElfW(Addr)>(UINT16_MAX)); 1103 return -1; 1104 } 1105 break; 1106 1107 case R_AARCH64_RELATIVE: 1108 count_relocation(kRelocRelative); 1109 MARK(rela->r_offset); 1110 if (sym) { 1111 DL_ERR("odd RELATIVE form..."); 1112 return -1; 1113 } 1114 TRACE_TYPE(RELO, "RELO RELATIVE %16llx <- %16llx\n", 1115 reloc, (si->base + rela->r_addend)); 1116 *reinterpret_cast<ElfW(Addr)*>(reloc) = (si->base + rela->r_addend); 1117 break; 1118 1119 case R_AARCH64_COPY: 1120 /* 1121 * ET_EXEC is not supported so this should not happen. 1122 * 1123 * http://infocenter.arm.com/help/topic/com.arm.doc.ihi0044d/IHI0044D_aaelf.pdf 1124 * 1125 * Section 4.7.1.10 "Dynamic relocations" 1126 * R_AARCH64_COPY may only appear in executable objects where e_type is 1127 * set to ET_EXEC. 1128 */ 1129 DL_ERR("%s R_AARCH64_COPY relocations are not supported", si->name); 1130 return -1; 1131 case R_AARCH64_TLS_TPREL64: 1132 TRACE_TYPE(RELO, "RELO TLS_TPREL64 *** %16llx <- %16llx - %16llx\n", 1133 reloc, (sym_addr + rela->r_addend), rela->r_offset); 1134 break; 1135 case R_AARCH64_TLS_DTPREL32: 1136 TRACE_TYPE(RELO, "RELO TLS_DTPREL32 *** %16llx <- %16llx - %16llx\n", 1137 reloc, (sym_addr + rela->r_addend), rela->r_offset); 1138 break; 1139 #elif defined(__x86_64__) 1140 case R_X86_64_JUMP_SLOT: 1141 count_relocation(kRelocAbsolute); 1142 MARK(rela->r_offset); 1143 TRACE_TYPE(RELO, "RELO JMP_SLOT %08zx <- %08zx %s", static_cast<size_t>(reloc), 1144 static_cast<size_t>(sym_addr + rela->r_addend), sym_name); 1145 *reinterpret_cast<ElfW(Addr)*>(reloc) = sym_addr + rela->r_addend; 1146 break; 1147 case R_X86_64_GLOB_DAT: 1148 count_relocation(kRelocAbsolute); 1149 MARK(rela->r_offset); 1150 TRACE_TYPE(RELO, "RELO GLOB_DAT %08zx <- %08zx %s", static_cast<size_t>(reloc), 1151 static_cast<size_t>(sym_addr + rela->r_addend), sym_name); 1152 *reinterpret_cast<ElfW(Addr)*>(reloc) = sym_addr + rela->r_addend; 1153 break; 1154 case R_X86_64_RELATIVE: 1155 count_relocation(kRelocRelative); 1156 MARK(rela->r_offset); 1157 if (sym) { 1158 DL_ERR("odd RELATIVE form..."); 1159 return -1; 1160 } 1161 TRACE_TYPE(RELO, "RELO RELATIVE %08zx <- +%08zx", static_cast<size_t>(reloc), 1162 static_cast<size_t>(si->base)); 1163 *reinterpret_cast<ElfW(Addr)*>(reloc) = si->base + rela->r_addend; 1164 break; 1165 case R_X86_64_32: 1166 count_relocation(kRelocRelative); 1167 MARK(rela->r_offset); 1168 TRACE_TYPE(RELO, "RELO R_X86_64_32 %08zx <- +%08zx %s", static_cast<size_t>(reloc), 1169 static_cast<size_t>(sym_addr), sym_name); 1170 *reinterpret_cast<ElfW(Addr)*>(reloc) = sym_addr + rela->r_addend; 1171 break; 1172 case R_X86_64_64: 1173 count_relocation(kRelocRelative); 1174 MARK(rela->r_offset); 1175 TRACE_TYPE(RELO, "RELO R_X86_64_64 %08zx <- +%08zx %s", static_cast<size_t>(reloc), 1176 static_cast<size_t>(sym_addr), sym_name); 1177 *reinterpret_cast<ElfW(Addr)*>(reloc) = sym_addr + rela->r_addend; 1178 break; 1179 case R_X86_64_PC32: 1180 count_relocation(kRelocRelative); 1181 MARK(rela->r_offset); 1182 TRACE_TYPE(RELO, "RELO R_X86_64_PC32 %08zx <- +%08zx (%08zx - %08zx) %s", 1183 static_cast<size_t>(reloc), static_cast<size_t>(sym_addr - reloc), 1184 static_cast<size_t>(sym_addr), static_cast<size_t>(reloc), sym_name); 1185 *reinterpret_cast<ElfW(Addr)*>(reloc) = sym_addr + rela->r_addend - reloc; 1186 break; 1187 #endif 1188 1189 default: 1190 DL_ERR("unknown reloc type %d @ %p (%zu)", type, rela, idx); 1191 return -1; 1192 } 1193 } 1194 return 0; 1195 } 1196 1197 #else // REL, not RELA. 1198 1199 static int soinfo_relocate(soinfo* si, ElfW(Rel)* rel, unsigned count, soinfo* needed[]) { 1200 ElfW(Sym)* s; 1201 soinfo* lsi; 1202 1203 for (size_t idx = 0; idx < count; ++idx, ++rel) { 1204 unsigned type = ELFW(R_TYPE)(rel->r_info); 1205 // TODO: don't use unsigned for 'sym'. Use uint32_t or ElfW(Addr) instead. 1206 unsigned sym = ELFW(R_SYM)(rel->r_info); 1207 ElfW(Addr) reloc = static_cast<ElfW(Addr)>(rel->r_offset + si->load_bias); 1208 ElfW(Addr) sym_addr = 0; 1209 const char* sym_name = NULL; 1210 1211 DEBUG("Processing '%s' relocation at index %zd", si->name, idx); 1212 if (type == 0) { // R_*_NONE 1213 continue; 1214 } 1215 if (sym != 0) { 1216 sym_name = reinterpret_cast<const char*>(si->strtab + si->symtab[sym].st_name); 1217 s = soinfo_do_lookup(si, sym_name, &lsi, needed); 1218 if (s == NULL) { 1219 // We only allow an undefined symbol if this is a weak reference... 1220 s = &si->symtab[sym]; 1221 if (ELF_ST_BIND(s->st_info) != STB_WEAK) { 1222 DL_ERR("cannot locate symbol \"%s\" referenced by \"%s\"...", sym_name, si->name); 1223 return -1; 1224 } 1225 1226 /* IHI0044C AAELF 4.5.1.1: 1227 1228 Libraries are not searched to resolve weak references. 1229 It is not an error for a weak reference to remain 1230 unsatisfied. 1231 1232 During linking, the value of an undefined weak reference is: 1233 - Zero if the relocation type is absolute 1234 - The address of the place if the relocation is pc-relative 1235 - The address of nominal base address if the relocation 1236 type is base-relative. 1237 */ 1238 1239 switch (type) { 1240 #if defined(__arm__) 1241 case R_ARM_JUMP_SLOT: 1242 case R_ARM_GLOB_DAT: 1243 case R_ARM_ABS32: 1244 case R_ARM_RELATIVE: /* Don't care. */ 1245 // sym_addr was initialized to be zero above or relocation 1246 // code below does not care about value of sym_addr. 1247 // No need to do anything. 1248 break; 1249 #elif defined(__i386__) 1250 case R_386_JMP_SLOT: 1251 case R_386_GLOB_DAT: 1252 case R_386_32: 1253 case R_386_RELATIVE: /* Don't care. */ 1254 // sym_addr was initialized to be zero above or relocation 1255 // code below does not care about value of sym_addr. 1256 // No need to do anything. 1257 break; 1258 case R_386_PC32: 1259 sym_addr = reloc; 1260 break; 1261 #endif 1262 1263 #if defined(__arm__) 1264 case R_ARM_COPY: 1265 // Fall through. Can't really copy if weak symbol is not found at run-time. 1266 #endif 1267 default: 1268 DL_ERR("unknown weak reloc type %d @ %p (%zu)", type, rel, idx); 1269 return -1; 1270 } 1271 } else { 1272 // We got a definition. 1273 sym_addr = static_cast<ElfW(Addr)>(s->st_value + lsi->load_bias); 1274 } 1275 count_relocation(kRelocSymbol); 1276 } else { 1277 s = NULL; 1278 } 1279 1280 switch (type) { 1281 #if defined(__arm__) 1282 case R_ARM_JUMP_SLOT: 1283 count_relocation(kRelocAbsolute); 1284 MARK(rel->r_offset); 1285 TRACE_TYPE(RELO, "RELO JMP_SLOT %08x <- %08x %s", reloc, sym_addr, sym_name); 1286 *reinterpret_cast<ElfW(Addr)*>(reloc) = sym_addr; 1287 break; 1288 case R_ARM_GLOB_DAT: 1289 count_relocation(kRelocAbsolute); 1290 MARK(rel->r_offset); 1291 TRACE_TYPE(RELO, "RELO GLOB_DAT %08x <- %08x %s", reloc, sym_addr, sym_name); 1292 *reinterpret_cast<ElfW(Addr)*>(reloc) = sym_addr; 1293 break; 1294 case R_ARM_ABS32: 1295 count_relocation(kRelocAbsolute); 1296 MARK(rel->r_offset); 1297 TRACE_TYPE(RELO, "RELO ABS %08x <- %08x %s", reloc, sym_addr, sym_name); 1298 *reinterpret_cast<ElfW(Addr)*>(reloc) += sym_addr; 1299 break; 1300 case R_ARM_REL32: 1301 count_relocation(kRelocRelative); 1302 MARK(rel->r_offset); 1303 TRACE_TYPE(RELO, "RELO REL32 %08x <- %08x - %08x %s", 1304 reloc, sym_addr, rel->r_offset, sym_name); 1305 *reinterpret_cast<ElfW(Addr)*>(reloc) += sym_addr - rel->r_offset; 1306 break; 1307 case R_ARM_COPY: 1308 /* 1309 * ET_EXEC is not supported so this should not happen. 1310 * 1311 * http://infocenter.arm.com/help/topic/com.arm.doc.ihi0044d/IHI0044D_aaelf.pdf 1312 * 1313 * Section 4.7.1.10 "Dynamic relocations" 1314 * R_ARM_COPY may only appear in executable objects where e_type is 1315 * set to ET_EXEC. 1316 */ 1317 DL_ERR("%s R_ARM_COPY relocations are not supported", si->name); 1318 return -1; 1319 #elif defined(__i386__) 1320 case R_386_JMP_SLOT: 1321 count_relocation(kRelocAbsolute); 1322 MARK(rel->r_offset); 1323 TRACE_TYPE(RELO, "RELO JMP_SLOT %08x <- %08x %s", reloc, sym_addr, sym_name); 1324 *reinterpret_cast<ElfW(Addr)*>(reloc) = sym_addr; 1325 break; 1326 case R_386_GLOB_DAT: 1327 count_relocation(kRelocAbsolute); 1328 MARK(rel->r_offset); 1329 TRACE_TYPE(RELO, "RELO GLOB_DAT %08x <- %08x %s", reloc, sym_addr, sym_name); 1330 *reinterpret_cast<ElfW(Addr)*>(reloc) = sym_addr; 1331 break; 1332 case R_386_32: 1333 count_relocation(kRelocRelative); 1334 MARK(rel->r_offset); 1335 TRACE_TYPE(RELO, "RELO R_386_32 %08x <- +%08x %s", reloc, sym_addr, sym_name); 1336 *reinterpret_cast<ElfW(Addr)*>(reloc) += sym_addr; 1337 break; 1338 case R_386_PC32: 1339 count_relocation(kRelocRelative); 1340 MARK(rel->r_offset); 1341 TRACE_TYPE(RELO, "RELO R_386_PC32 %08x <- +%08x (%08x - %08x) %s", 1342 reloc, (sym_addr - reloc), sym_addr, reloc, sym_name); 1343 *reinterpret_cast<ElfW(Addr)*>(reloc) += (sym_addr - reloc); 1344 break; 1345 #elif defined(__mips__) 1346 case R_MIPS_REL32: 1347 #if defined(__LP64__) 1348 // MIPS Elf64_Rel entries contain compound relocations 1349 // We only handle the R_MIPS_NONE|R_MIPS_64|R_MIPS_REL32 case 1350 if (ELF64_R_TYPE2(rel->r_info) != R_MIPS_64 || 1351 ELF64_R_TYPE3(rel->r_info) != R_MIPS_NONE) { 1352 DL_ERR("Unexpected compound relocation type:%d type2:%d type3:%d @ %p (%zu)", 1353 type, (unsigned)ELF64_R_TYPE2(rel->r_info), 1354 (unsigned)ELF64_R_TYPE3(rel->r_info), rel, idx); 1355 return -1; 1356 } 1357 #endif 1358 count_relocation(kRelocAbsolute); 1359 MARK(rel->r_offset); 1360 TRACE_TYPE(RELO, "RELO REL32 %08zx <- %08zx %s", static_cast<size_t>(reloc), 1361 static_cast<size_t>(sym_addr), sym_name ? sym_name : "*SECTIONHDR*"); 1362 if (s) { 1363 *reinterpret_cast<ElfW(Addr)*>(reloc) += sym_addr; 1364 } else { 1365 *reinterpret_cast<ElfW(Addr)*>(reloc) += si->base; 1366 } 1367 break; 1368 #endif 1369 1370 #if defined(__arm__) 1371 case R_ARM_RELATIVE: 1372 #elif defined(__i386__) 1373 case R_386_RELATIVE: 1374 #endif 1375 count_relocation(kRelocRelative); 1376 MARK(rel->r_offset); 1377 if (sym) { 1378 DL_ERR("odd RELATIVE form..."); 1379 return -1; 1380 } 1381 TRACE_TYPE(RELO, "RELO RELATIVE %p <- +%p", 1382 reinterpret_cast<void*>(reloc), reinterpret_cast<void*>(si->base)); 1383 *reinterpret_cast<ElfW(Addr)*>(reloc) += si->base; 1384 break; 1385 1386 default: 1387 DL_ERR("unknown reloc type %d @ %p (%zu)", type, rel, idx); 1388 return -1; 1389 } 1390 } 1391 return 0; 1392 } 1393 #endif 1394 1395 #if defined(__mips__) 1396 static bool mips_relocate_got(soinfo* si, soinfo* needed[]) { 1397 ElfW(Addr)** got = si->plt_got; 1398 if (got == NULL) { 1399 return true; 1400 } 1401 unsigned local_gotno = si->mips_local_gotno; 1402 unsigned gotsym = si->mips_gotsym; 1403 unsigned symtabno = si->mips_symtabno; 1404 ElfW(Sym)* symtab = si->symtab; 1405 1406 // got[0] is the address of the lazy resolver function. 1407 // got[1] may be used for a GNU extension. 1408 // Set it to a recognizable address in case someone calls it (should be _rtld_bind_start). 1409 // FIXME: maybe this should be in a separate routine? 1410 if ((si->flags & FLAG_LINKER) == 0) { 1411 size_t g = 0; 1412 got[g++] = reinterpret_cast<ElfW(Addr)*>(0xdeadbeef); 1413 if (reinterpret_cast<intptr_t>(got[g]) < 0) { 1414 got[g++] = reinterpret_cast<ElfW(Addr)*>(0xdeadfeed); 1415 } 1416 // Relocate the local GOT entries. 1417 for (; g < local_gotno; g++) { 1418 got[g] = reinterpret_cast<ElfW(Addr)*>(reinterpret_cast<uintptr_t>(got[g]) + si->load_bias); 1419 } 1420 } 1421 1422 // Now for the global GOT entries... 1423 ElfW(Sym)* sym = symtab + gotsym; 1424 got = si->plt_got + local_gotno; 1425 for (size_t g = gotsym; g < symtabno; g++, sym++, got++) { 1426 // This is an undefined reference... try to locate it. 1427 const char* sym_name = si->strtab + sym->st_name; 1428 soinfo* lsi; 1429 ElfW(Sym)* s = soinfo_do_lookup(si, sym_name, &lsi, needed); 1430 if (s == NULL) { 1431 // We only allow an undefined symbol if this is a weak reference. 1432 s = &symtab[g]; 1433 if (ELF_ST_BIND(s->st_info) != STB_WEAK) { 1434 DL_ERR("cannot locate \"%s\"...", sym_name); 1435 return false; 1436 } 1437 *got = 0; 1438 } else { 1439 // FIXME: is this sufficient? 1440 // For reference see NetBSD link loader 1441 // http://cvsweb.netbsd.org/bsdweb.cgi/src/libexec/ld.elf_so/arch/mips/mips_reloc.c?rev=1.53&content-type=text/x-cvsweb-markup 1442 *got = reinterpret_cast<ElfW(Addr)*>(lsi->load_bias + s->st_value); 1443 } 1444 } 1445 return true; 1446 } 1447 #endif 1448 1449 void soinfo::CallArray(const char* array_name __unused, linker_function_t* functions, size_t count, bool reverse) { 1450 if (functions == NULL) { 1451 return; 1452 } 1453 1454 TRACE("[ Calling %s (size %zd) @ %p for '%s' ]", array_name, count, functions, name); 1455 1456 int begin = reverse ? (count - 1) : 0; 1457 int end = reverse ? -1 : count; 1458 int step = reverse ? -1 : 1; 1459 1460 for (int i = begin; i != end; i += step) { 1461 TRACE("[ %s[%d] == %p ]", array_name, i, functions[i]); 1462 CallFunction("function", functions[i]); 1463 } 1464 1465 TRACE("[ Done calling %s for '%s' ]", array_name, name); 1466 } 1467 1468 void soinfo::CallFunction(const char* function_name __unused, linker_function_t function) { 1469 if (function == NULL || reinterpret_cast<uintptr_t>(function) == static_cast<uintptr_t>(-1)) { 1470 return; 1471 } 1472 1473 TRACE("[ Calling %s @ %p for '%s' ]", function_name, function, name); 1474 function(); 1475 TRACE("[ Done calling %s @ %p for '%s' ]", function_name, function, name); 1476 1477 // The function may have called dlopen(3) or dlclose(3), so we need to ensure our data structures 1478 // are still writable. This happens with our debug malloc (see http://b/7941716). 1479 protect_data(PROT_READ | PROT_WRITE); 1480 } 1481 1482 void soinfo::CallPreInitConstructors() { 1483 // DT_PREINIT_ARRAY functions are called before any other constructors for executables, 1484 // but ignored in a shared library. 1485 CallArray("DT_PREINIT_ARRAY", preinit_array, preinit_array_count, false); 1486 } 1487 1488 void soinfo::CallConstructors() { 1489 if (constructors_called) { 1490 return; 1491 } 1492 1493 // We set constructors_called before actually calling the constructors, otherwise it doesn't 1494 // protect against recursive constructor calls. One simple example of constructor recursion 1495 // is the libc debug malloc, which is implemented in libc_malloc_debug_leak.so: 1496 // 1. The program depends on libc, so libc's constructor is called here. 1497 // 2. The libc constructor calls dlopen() to load libc_malloc_debug_leak.so. 1498 // 3. dlopen() calls the constructors on the newly created 1499 // soinfo for libc_malloc_debug_leak.so. 1500 // 4. The debug .so depends on libc, so CallConstructors is 1501 // called again with the libc soinfo. If it doesn't trigger the early- 1502 // out above, the libc constructor will be called again (recursively!). 1503 constructors_called = true; 1504 1505 if ((flags & FLAG_EXE) == 0 && preinit_array != NULL) { 1506 // The GNU dynamic linker silently ignores these, but we warn the developer. 1507 PRINT("\"%s\": ignoring %zd-entry DT_PREINIT_ARRAY in shared library!", 1508 name, preinit_array_count); 1509 } 1510 1511 get_children().for_each([] (soinfo* si) { 1512 si->CallConstructors(); 1513 }); 1514 1515 TRACE("\"%s\": calling constructors", name); 1516 1517 // DT_INIT should be called before DT_INIT_ARRAY if both are present. 1518 CallFunction("DT_INIT", init_func); 1519 CallArray("DT_INIT_ARRAY", init_array, init_array_count, false); 1520 } 1521 1522 void soinfo::CallDestructors() { 1523 TRACE("\"%s\": calling destructors", name); 1524 1525 // DT_FINI_ARRAY must be parsed in reverse order. 1526 CallArray("DT_FINI_ARRAY", fini_array, fini_array_count, true); 1527 1528 // DT_FINI should be called after DT_FINI_ARRAY if both are present. 1529 CallFunction("DT_FINI", fini_func); 1530 1531 // This is needed on second call to dlopen 1532 // after library has been unloaded with RTLD_NODELETE 1533 constructors_called = false; 1534 } 1535 1536 void soinfo::add_child(soinfo* child) { 1537 if ((this->flags & FLAG_NEW_SOINFO) == 0) { 1538 return; 1539 } 1540 1541 this->children.push_front(child); 1542 child->parents.push_front(this); 1543 } 1544 1545 void soinfo::remove_all_links() { 1546 if ((this->flags & FLAG_NEW_SOINFO) == 0) { 1547 return; 1548 } 1549 1550 // 1. Untie connected soinfos from 'this'. 1551 children.for_each([&] (soinfo* child) { 1552 child->parents.remove_if([&] (const soinfo* parent) { 1553 return parent == this; 1554 }); 1555 }); 1556 1557 parents.for_each([&] (soinfo* parent) { 1558 parent->children.for_each([&] (const soinfo* child) { 1559 return child == this; 1560 }); 1561 }); 1562 1563 // 2. Once everything untied - clear local lists. 1564 parents.clear(); 1565 children.clear(); 1566 } 1567 1568 void soinfo::set_st_dev(dev_t dev) { 1569 if ((this->flags & FLAG_NEW_SOINFO) == 0) { 1570 return; 1571 } 1572 1573 st_dev = dev; 1574 } 1575 1576 void soinfo::set_st_ino(ino_t ino) { 1577 if ((this->flags & FLAG_NEW_SOINFO) == 0) { 1578 return; 1579 } 1580 1581 st_ino = ino; 1582 } 1583 1584 dev_t soinfo::get_st_dev() { 1585 if ((this->flags & FLAG_NEW_SOINFO) == 0) { 1586 return 0; 1587 } 1588 1589 return st_dev; 1590 }; 1591 1592 ino_t soinfo::get_st_ino() { 1593 if ((this->flags & FLAG_NEW_SOINFO) == 0) { 1594 return 0; 1595 } 1596 1597 return st_ino; 1598 } 1599 1600 // This is a return on get_children() in case 1601 // 'this->flags' does not have FLAG_NEW_SOINFO set. 1602 static soinfo::soinfo_list_t g_empty_list; 1603 1604 soinfo::soinfo_list_t& soinfo::get_children() { 1605 if ((this->flags & FLAG_NEW_SOINFO) == 0) { 1606 return g_empty_list; 1607 } 1608 1609 return this->children; 1610 } 1611 1612 /* Force any of the closed stdin, stdout and stderr to be associated with 1613 /dev/null. */ 1614 static int nullify_closed_stdio() { 1615 int dev_null, i, status; 1616 int return_value = 0; 1617 1618 dev_null = TEMP_FAILURE_RETRY(open("/dev/null", O_RDWR)); 1619 if (dev_null < 0) { 1620 DL_ERR("cannot open /dev/null: %s", strerror(errno)); 1621 return -1; 1622 } 1623 TRACE("[ Opened /dev/null file-descriptor=%d]", dev_null); 1624 1625 /* If any of the stdio file descriptors is valid and not associated 1626 with /dev/null, dup /dev/null to it. */ 1627 for (i = 0; i < 3; i++) { 1628 /* If it is /dev/null already, we are done. */ 1629 if (i == dev_null) { 1630 continue; 1631 } 1632 1633 TRACE("[ Nullifying stdio file descriptor %d]", i); 1634 status = TEMP_FAILURE_RETRY(fcntl(i, F_GETFL)); 1635 1636 /* If file is opened, we are good. */ 1637 if (status != -1) { 1638 continue; 1639 } 1640 1641 /* The only error we allow is that the file descriptor does not 1642 exist, in which case we dup /dev/null to it. */ 1643 if (errno != EBADF) { 1644 DL_ERR("fcntl failed: %s", strerror(errno)); 1645 return_value = -1; 1646 continue; 1647 } 1648 1649 /* Try dupping /dev/null to this stdio file descriptor and 1650 repeat if there is a signal. Note that any errors in closing 1651 the stdio descriptor are lost. */ 1652 status = TEMP_FAILURE_RETRY(dup2(dev_null, i)); 1653 if (status < 0) { 1654 DL_ERR("dup2 failed: %s", strerror(errno)); 1655 return_value = -1; 1656 continue; 1657 } 1658 } 1659 1660 /* If /dev/null is not one of the stdio file descriptors, close it. */ 1661 if (dev_null > 2) { 1662 TRACE("[ Closing /dev/null file-descriptor=%d]", dev_null); 1663 status = TEMP_FAILURE_RETRY(close(dev_null)); 1664 if (status == -1) { 1665 DL_ERR("close failed: %s", strerror(errno)); 1666 return_value = -1; 1667 } 1668 } 1669 1670 return return_value; 1671 } 1672 1673 static bool soinfo_link_image(soinfo* si, const android_dlextinfo* extinfo) { 1674 /* "base" might wrap around UINT32_MAX. */ 1675 ElfW(Addr) base = si->load_bias; 1676 const ElfW(Phdr)* phdr = si->phdr; 1677 int phnum = si->phnum; 1678 bool relocating_linker = (si->flags & FLAG_LINKER) != 0; 1679 1680 /* We can't debug anything until the linker is relocated */ 1681 if (!relocating_linker) { 1682 INFO("[ linking %s ]", si->name); 1683 DEBUG("si->base = %p si->flags = 0x%08x", reinterpret_cast<void*>(si->base), si->flags); 1684 } 1685 1686 /* Extract dynamic section */ 1687 size_t dynamic_count; 1688 ElfW(Word) dynamic_flags; 1689 phdr_table_get_dynamic_section(phdr, phnum, base, &si->dynamic, 1690 &dynamic_count, &dynamic_flags); 1691 if (si->dynamic == NULL) { 1692 if (!relocating_linker) { 1693 DL_ERR("missing PT_DYNAMIC in \"%s\"", si->name); 1694 } 1695 return false; 1696 } else { 1697 if (!relocating_linker) { 1698 DEBUG("dynamic = %p", si->dynamic); 1699 } 1700 } 1701 1702 #if defined(__arm__) 1703 (void) phdr_table_get_arm_exidx(phdr, phnum, base, 1704 &si->ARM_exidx, &si->ARM_exidx_count); 1705 #endif 1706 1707 // Extract useful information from dynamic section. 1708 uint32_t needed_count = 0; 1709 for (ElfW(Dyn)* d = si->dynamic; d->d_tag != DT_NULL; ++d) { 1710 DEBUG("d = %p, d[0](tag) = %p d[1](val) = %p", 1711 d, reinterpret_cast<void*>(d->d_tag), reinterpret_cast<void*>(d->d_un.d_val)); 1712 switch (d->d_tag) { 1713 case DT_HASH: 1714 si->nbucket = reinterpret_cast<uint32_t*>(base + d->d_un.d_ptr)[0]; 1715 si->nchain = reinterpret_cast<uint32_t*>(base + d->d_un.d_ptr)[1]; 1716 si->bucket = reinterpret_cast<uint32_t*>(base + d->d_un.d_ptr + 8); 1717 si->chain = reinterpret_cast<uint32_t*>(base + d->d_un.d_ptr + 8 + si->nbucket * 4); 1718 break; 1719 case DT_STRTAB: 1720 si->strtab = reinterpret_cast<const char*>(base + d->d_un.d_ptr); 1721 break; 1722 case DT_SYMTAB: 1723 si->symtab = reinterpret_cast<ElfW(Sym)*>(base + d->d_un.d_ptr); 1724 break; 1725 #if !defined(__LP64__) 1726 case DT_PLTREL: 1727 if (d->d_un.d_val != DT_REL) { 1728 DL_ERR("unsupported DT_RELA in \"%s\"", si->name); 1729 return false; 1730 } 1731 break; 1732 #endif 1733 case DT_JMPREL: 1734 #if defined(USE_RELA) 1735 si->plt_rela = reinterpret_cast<ElfW(Rela)*>(base + d->d_un.d_ptr); 1736 #else 1737 si->plt_rel = reinterpret_cast<ElfW(Rel)*>(base + d->d_un.d_ptr); 1738 #endif 1739 break; 1740 case DT_PLTRELSZ: 1741 #if defined(USE_RELA) 1742 si->plt_rela_count = d->d_un.d_val / sizeof(ElfW(Rela)); 1743 #else 1744 si->plt_rel_count = d->d_un.d_val / sizeof(ElfW(Rel)); 1745 #endif 1746 break; 1747 #if defined(__mips__) 1748 case DT_PLTGOT: 1749 // Used by mips and mips64. 1750 si->plt_got = reinterpret_cast<ElfW(Addr)**>(base + d->d_un.d_ptr); 1751 break; 1752 #endif 1753 case DT_DEBUG: 1754 // Set the DT_DEBUG entry to the address of _r_debug for GDB 1755 // if the dynamic table is writable 1756 // FIXME: not working currently for N64 1757 // The flags for the LOAD and DYNAMIC program headers do not agree. 1758 // The LOAD section containng the dynamic table has been mapped as 1759 // read-only, but the DYNAMIC header claims it is writable. 1760 #if !(defined(__mips__) && defined(__LP64__)) 1761 if ((dynamic_flags & PF_W) != 0) { 1762 d->d_un.d_val = reinterpret_cast<uintptr_t>(&_r_debug); 1763 } 1764 break; 1765 #endif 1766 #if defined(USE_RELA) 1767 case DT_RELA: 1768 si->rela = reinterpret_cast<ElfW(Rela)*>(base + d->d_un.d_ptr); 1769 break; 1770 case DT_RELASZ: 1771 si->rela_count = d->d_un.d_val / sizeof(ElfW(Rela)); 1772 break; 1773 case DT_REL: 1774 DL_ERR("unsupported DT_REL in \"%s\"", si->name); 1775 return false; 1776 case DT_RELSZ: 1777 DL_ERR("unsupported DT_RELSZ in \"%s\"", si->name); 1778 return false; 1779 #else 1780 case DT_REL: 1781 si->rel = reinterpret_cast<ElfW(Rel)*>(base + d->d_un.d_ptr); 1782 break; 1783 case DT_RELSZ: 1784 si->rel_count = d->d_un.d_val / sizeof(ElfW(Rel)); 1785 break; 1786 case DT_RELA: 1787 DL_ERR("unsupported DT_RELA in \"%s\"", si->name); 1788 return false; 1789 #endif 1790 case DT_INIT: 1791 si->init_func = reinterpret_cast<linker_function_t>(base + d->d_un.d_ptr); 1792 DEBUG("%s constructors (DT_INIT) found at %p", si->name, si->init_func); 1793 break; 1794 case DT_FINI: 1795 si->fini_func = reinterpret_cast<linker_function_t>(base + d->d_un.d_ptr); 1796 DEBUG("%s destructors (DT_FINI) found at %p", si->name, si->fini_func); 1797 break; 1798 case DT_INIT_ARRAY: 1799 si->init_array = reinterpret_cast<linker_function_t*>(base + d->d_un.d_ptr); 1800 DEBUG("%s constructors (DT_INIT_ARRAY) found at %p", si->name, si->init_array); 1801 break; 1802 case DT_INIT_ARRAYSZ: 1803 si->init_array_count = ((unsigned)d->d_un.d_val) / sizeof(ElfW(Addr)); 1804 break; 1805 case DT_FINI_ARRAY: 1806 si->fini_array = reinterpret_cast<linker_function_t*>(base + d->d_un.d_ptr); 1807 DEBUG("%s destructors (DT_FINI_ARRAY) found at %p", si->name, si->fini_array); 1808 break; 1809 case DT_FINI_ARRAYSZ: 1810 si->fini_array_count = ((unsigned)d->d_un.d_val) / sizeof(ElfW(Addr)); 1811 break; 1812 case DT_PREINIT_ARRAY: 1813 si->preinit_array = reinterpret_cast<linker_function_t*>(base + d->d_un.d_ptr); 1814 DEBUG("%s constructors (DT_PREINIT_ARRAY) found at %p", si->name, si->preinit_array); 1815 break; 1816 case DT_PREINIT_ARRAYSZ: 1817 si->preinit_array_count = ((unsigned)d->d_un.d_val) / sizeof(ElfW(Addr)); 1818 break; 1819 case DT_TEXTREL: 1820 #if defined(__LP64__) 1821 DL_ERR("text relocations (DT_TEXTREL) found in 64-bit ELF file \"%s\"", si->name); 1822 return false; 1823 #else 1824 si->has_text_relocations = true; 1825 break; 1826 #endif 1827 case DT_SYMBOLIC: 1828 si->has_DT_SYMBOLIC = true; 1829 break; 1830 case DT_NEEDED: 1831 ++needed_count; 1832 break; 1833 case DT_FLAGS: 1834 if (d->d_un.d_val & DF_TEXTREL) { 1835 #if defined(__LP64__) 1836 DL_ERR("text relocations (DF_TEXTREL) found in 64-bit ELF file \"%s\"", si->name); 1837 return false; 1838 #else 1839 si->has_text_relocations = true; 1840 #endif 1841 } 1842 if (d->d_un.d_val & DF_SYMBOLIC) { 1843 si->has_DT_SYMBOLIC = true; 1844 } 1845 break; 1846 #if defined(__mips__) 1847 case DT_STRSZ: 1848 case DT_SYMENT: 1849 case DT_RELENT: 1850 break; 1851 case DT_MIPS_RLD_MAP: 1852 // Set the DT_MIPS_RLD_MAP entry to the address of _r_debug for GDB. 1853 { 1854 r_debug** dp = reinterpret_cast<r_debug**>(base + d->d_un.d_ptr); 1855 *dp = &_r_debug; 1856 } 1857 break; 1858 case DT_MIPS_RLD_VERSION: 1859 case DT_MIPS_FLAGS: 1860 case DT_MIPS_BASE_ADDRESS: 1861 case DT_MIPS_UNREFEXTNO: 1862 break; 1863 1864 case DT_MIPS_SYMTABNO: 1865 si->mips_symtabno = d->d_un.d_val; 1866 break; 1867 1868 case DT_MIPS_LOCAL_GOTNO: 1869 si->mips_local_gotno = d->d_un.d_val; 1870 break; 1871 1872 case DT_MIPS_GOTSYM: 1873 si->mips_gotsym = d->d_un.d_val; 1874 break; 1875 #endif 1876 1877 default: 1878 DEBUG("Unused DT entry: type %p arg %p", 1879 reinterpret_cast<void*>(d->d_tag), reinterpret_cast<void*>(d->d_un.d_val)); 1880 break; 1881 } 1882 } 1883 1884 DEBUG("si->base = %p, si->strtab = %p, si->symtab = %p", 1885 reinterpret_cast<void*>(si->base), si->strtab, si->symtab); 1886 1887 // Sanity checks. 1888 if (relocating_linker && needed_count != 0) { 1889 DL_ERR("linker cannot have DT_NEEDED dependencies on other libraries"); 1890 return false; 1891 } 1892 if (si->nbucket == 0) { 1893 DL_ERR("empty/missing DT_HASH in \"%s\" (built with --hash-style=gnu?)", si->name); 1894 return false; 1895 } 1896 if (si->strtab == 0) { 1897 DL_ERR("empty/missing DT_STRTAB in \"%s\"", si->name); 1898 return false; 1899 } 1900 if (si->symtab == 0) { 1901 DL_ERR("empty/missing DT_SYMTAB in \"%s\"", si->name); 1902 return false; 1903 } 1904 1905 // If this is the main executable, then load all of the libraries from LD_PRELOAD now. 1906 if (si->flags & FLAG_EXE) { 1907 memset(g_ld_preloads, 0, sizeof(g_ld_preloads)); 1908 size_t preload_count = 0; 1909 for (size_t i = 0; g_ld_preload_names[i] != NULL; i++) { 1910 soinfo* lsi = find_library(g_ld_preload_names[i], 0, NULL); 1911 if (lsi != NULL) { 1912 g_ld_preloads[preload_count++] = lsi; 1913 } else { 1914 // As with glibc, failure to load an LD_PRELOAD library is just a warning. 1915 DL_WARN("could not load library \"%s\" from LD_PRELOAD for \"%s\"; caused by %s", 1916 g_ld_preload_names[i], si->name, linker_get_error_buffer()); 1917 } 1918 } 1919 } 1920 1921 soinfo** needed = reinterpret_cast<soinfo**>(alloca((1 + needed_count) * sizeof(soinfo*))); 1922 soinfo** pneeded = needed; 1923 1924 for (ElfW(Dyn)* d = si->dynamic; d->d_tag != DT_NULL; ++d) { 1925 if (d->d_tag == DT_NEEDED) { 1926 const char* library_name = si->strtab + d->d_un.d_val; 1927 DEBUG("%s needs %s", si->name, library_name); 1928 soinfo* lsi = find_library(library_name, 0, NULL); 1929 if (lsi == NULL) { 1930 strlcpy(tmp_err_buf, linker_get_error_buffer(), sizeof(tmp_err_buf)); 1931 DL_ERR("could not load library \"%s\" needed by \"%s\"; caused by %s", 1932 library_name, si->name, tmp_err_buf); 1933 return false; 1934 } 1935 1936 si->add_child(lsi); 1937 *pneeded++ = lsi; 1938 } 1939 } 1940 *pneeded = NULL; 1941 1942 #if !defined(__LP64__) 1943 if (si->has_text_relocations) { 1944 // Make segments writable to allow text relocations to work properly. We will later call 1945 // phdr_table_protect_segments() after all of them are applied and all constructors are run. 1946 DL_WARN("%s has text relocations. This is wasting memory and prevents " 1947 "security hardening. Please fix.", si->name); 1948 if (phdr_table_unprotect_segments(si->phdr, si->phnum, si->load_bias) < 0) { 1949 DL_ERR("can't unprotect loadable segments for \"%s\": %s", 1950 si->name, strerror(errno)); 1951 return false; 1952 } 1953 } 1954 #endif 1955 1956 #if defined(USE_RELA) 1957 if (si->plt_rela != NULL) { 1958 DEBUG("[ relocating %s plt ]\n", si->name); 1959 if (soinfo_relocate(si, si->plt_rela, si->plt_rela_count, needed)) { 1960 return false; 1961 } 1962 } 1963 if (si->rela != NULL) { 1964 DEBUG("[ relocating %s ]\n", si->name); 1965 if (soinfo_relocate(si, si->rela, si->rela_count, needed)) { 1966 return false; 1967 } 1968 } 1969 #else 1970 if (si->plt_rel != NULL) { 1971 DEBUG("[ relocating %s plt ]", si->name); 1972 if (soinfo_relocate(si, si->plt_rel, si->plt_rel_count, needed)) { 1973 return false; 1974 } 1975 } 1976 if (si->rel != NULL) { 1977 DEBUG("[ relocating %s ]", si->name); 1978 if (soinfo_relocate(si, si->rel, si->rel_count, needed)) { 1979 return false; 1980 } 1981 } 1982 #endif 1983 1984 #if defined(__mips__) 1985 if (!mips_relocate_got(si, needed)) { 1986 return false; 1987 } 1988 #endif 1989 1990 si->flags |= FLAG_LINKED; 1991 DEBUG("[ finished linking %s ]", si->name); 1992 1993 #if !defined(__LP64__) 1994 if (si->has_text_relocations) { 1995 // All relocations are done, we can protect our segments back to read-only. 1996 if (phdr_table_protect_segments(si->phdr, si->phnum, si->load_bias) < 0) { 1997 DL_ERR("can't protect segments for \"%s\": %s", 1998 si->name, strerror(errno)); 1999 return false; 2000 } 2001 } 2002 #endif 2003 2004 /* We can also turn on GNU RELRO protection */ 2005 if (phdr_table_protect_gnu_relro(si->phdr, si->phnum, si->load_bias) < 0) { 2006 DL_ERR("can't enable GNU RELRO protection for \"%s\": %s", 2007 si->name, strerror(errno)); 2008 return false; 2009 } 2010 2011 /* Handle serializing/sharing the RELRO segment */ 2012 if (extinfo && (extinfo->flags & ANDROID_DLEXT_WRITE_RELRO)) { 2013 if (phdr_table_serialize_gnu_relro(si->phdr, si->phnum, si->load_bias, 2014 extinfo->relro_fd) < 0) { 2015 DL_ERR("failed serializing GNU RELRO section for \"%s\": %s", 2016 si->name, strerror(errno)); 2017 return false; 2018 } 2019 } else if (extinfo && (extinfo->flags & ANDROID_DLEXT_USE_RELRO)) { 2020 if (phdr_table_map_gnu_relro(si->phdr, si->phnum, si->load_bias, 2021 extinfo->relro_fd) < 0) { 2022 DL_ERR("failed mapping GNU RELRO section for \"%s\": %s", 2023 si->name, strerror(errno)); 2024 return false; 2025 } 2026 } 2027 2028 notify_gdb_of_load(si); 2029 return true; 2030 } 2031 2032 /* 2033 * This function add vdso to internal dso list. 2034 * It helps to stack unwinding through signal handlers. 2035 * Also, it makes bionic more like glibc. 2036 */ 2037 static void add_vdso(KernelArgumentBlock& args __unused) { 2038 #if defined(AT_SYSINFO_EHDR) 2039 ElfW(Ehdr)* ehdr_vdso = reinterpret_cast<ElfW(Ehdr)*>(args.getauxval(AT_SYSINFO_EHDR)); 2040 if (ehdr_vdso == NULL) { 2041 return; 2042 } 2043 2044 soinfo* si = soinfo_alloc("[vdso]", NULL); 2045 2046 si->phdr = reinterpret_cast<ElfW(Phdr)*>(reinterpret_cast<char*>(ehdr_vdso) + ehdr_vdso->e_phoff); 2047 si->phnum = ehdr_vdso->e_phnum; 2048 si->base = reinterpret_cast<ElfW(Addr)>(ehdr_vdso); 2049 si->size = phdr_table_get_load_size(si->phdr, si->phnum); 2050 si->load_bias = get_elf_exec_load_bias(ehdr_vdso); 2051 2052 soinfo_link_image(si, NULL); 2053 #endif 2054 } 2055 2056 /* 2057 * This is linker soinfo for GDB. See details below. 2058 */ 2059 static soinfo linker_soinfo_for_gdb; 2060 2061 /* gdb expects the linker to be in the debug shared object list. 2062 * Without this, gdb has trouble locating the linker's ".text" 2063 * and ".plt" sections. Gdb could also potentially use this to 2064 * relocate the offset of our exported 'rtld_db_dlactivity' symbol. 2065 * Don't use soinfo_alloc(), because the linker shouldn't 2066 * be on the soinfo list. 2067 */ 2068 static void init_linker_info_for_gdb(ElfW(Addr) linker_base) { 2069 #if defined(__LP64__) 2070 strlcpy(linker_soinfo_for_gdb.name, "/system/bin/linker64", sizeof(linker_soinfo_for_gdb.name)); 2071 #else 2072 strlcpy(linker_soinfo_for_gdb.name, "/system/bin/linker", sizeof(linker_soinfo_for_gdb.name)); 2073 #endif 2074 linker_soinfo_for_gdb.flags = FLAG_NEW_SOINFO; 2075 linker_soinfo_for_gdb.base = linker_base; 2076 2077 /* 2078 * Set the dynamic field in the link map otherwise gdb will complain with 2079 * the following: 2080 * warning: .dynamic section for "/system/bin/linker" is not at the 2081 * expected address (wrong library or version mismatch?) 2082 */ 2083 ElfW(Ehdr)* elf_hdr = reinterpret_cast<ElfW(Ehdr)*>(linker_base); 2084 ElfW(Phdr)* phdr = reinterpret_cast<ElfW(Phdr)*>(linker_base + elf_hdr->e_phoff); 2085 phdr_table_get_dynamic_section(phdr, elf_hdr->e_phnum, linker_base, 2086 &linker_soinfo_for_gdb.dynamic, NULL, NULL); 2087 insert_soinfo_into_debug_map(&linker_soinfo_for_gdb); 2088 } 2089 2090 /* 2091 * This code is called after the linker has linked itself and 2092 * fixed it's own GOT. It is safe to make references to externs 2093 * and other non-local data at this point. 2094 */ 2095 static ElfW(Addr) __linker_init_post_relocation(KernelArgumentBlock& args, ElfW(Addr) linker_base) { 2096 /* NOTE: we store the args pointer on a special location 2097 * of the temporary TLS area in order to pass it to 2098 * the C Library's runtime initializer. 2099 * 2100 * The initializer must clear the slot and reset the TLS 2101 * to point to a different location to ensure that no other 2102 * shared library constructor can access it. 2103 */ 2104 __libc_init_tls(args); 2105 2106 #if TIMING 2107 struct timeval t0, t1; 2108 gettimeofday(&t0, 0); 2109 #endif 2110 2111 // Initialize environment functions, and get to the ELF aux vectors table. 2112 linker_env_init(args); 2113 2114 // If this is a setuid/setgid program, close the security hole described in 2115 // ftp://ftp.freebsd.org/pub/FreeBSD/CERT/advisories/FreeBSD-SA-02:23.stdio.asc 2116 if (get_AT_SECURE()) { 2117 nullify_closed_stdio(); 2118 } 2119 2120 debuggerd_init(); 2121 2122 // Get a few environment variables. 2123 const char* LD_DEBUG = linker_env_get("LD_DEBUG"); 2124 if (LD_DEBUG != NULL) { 2125 g_ld_debug_verbosity = atoi(LD_DEBUG); 2126 } 2127 2128 // Normally, these are cleaned by linker_env_init, but the test 2129 // doesn't cost us anything. 2130 const char* ldpath_env = NULL; 2131 const char* ldpreload_env = NULL; 2132 if (!get_AT_SECURE()) { 2133 ldpath_env = linker_env_get("LD_LIBRARY_PATH"); 2134 ldpreload_env = linker_env_get("LD_PRELOAD"); 2135 } 2136 2137 INFO("[ android linker & debugger ]"); 2138 2139 soinfo* si = soinfo_alloc(args.argv[0], NULL); 2140 if (si == NULL) { 2141 exit(EXIT_FAILURE); 2142 } 2143 2144 /* bootstrap the link map, the main exe always needs to be first */ 2145 si->flags |= FLAG_EXE; 2146 link_map* map = &(si->link_map_head); 2147 2148 map->l_addr = 0; 2149 map->l_name = args.argv[0]; 2150 map->l_prev = NULL; 2151 map->l_next = NULL; 2152 2153 _r_debug.r_map = map; 2154 r_debug_tail = map; 2155 2156 init_linker_info_for_gdb(linker_base); 2157 2158 // Extract information passed from the kernel. 2159 si->phdr = reinterpret_cast<ElfW(Phdr)*>(args.getauxval(AT_PHDR)); 2160 si->phnum = args.getauxval(AT_PHNUM); 2161 si->entry = args.getauxval(AT_ENTRY); 2162 2163 /* Compute the value of si->base. We can't rely on the fact that 2164 * the first entry is the PHDR because this will not be true 2165 * for certain executables (e.g. some in the NDK unit test suite) 2166 */ 2167 si->base = 0; 2168 si->size = phdr_table_get_load_size(si->phdr, si->phnum); 2169 si->load_bias = 0; 2170 for (size_t i = 0; i < si->phnum; ++i) { 2171 if (si->phdr[i].p_type == PT_PHDR) { 2172 si->load_bias = reinterpret_cast<ElfW(Addr)>(si->phdr) - si->phdr[i].p_vaddr; 2173 si->base = reinterpret_cast<ElfW(Addr)>(si->phdr) - si->phdr[i].p_offset; 2174 break; 2175 } 2176 } 2177 si->dynamic = NULL; 2178 si->ref_count = 1; 2179 2180 ElfW(Ehdr)* elf_hdr = reinterpret_cast<ElfW(Ehdr)*>(si->base); 2181 if (elf_hdr->e_type != ET_DYN) { 2182 __libc_format_fd(2, "error: only position independent executables (PIE) are supported.\n"); 2183 exit(EXIT_FAILURE); 2184 } 2185 2186 // Use LD_LIBRARY_PATH and LD_PRELOAD (but only if we aren't setuid/setgid). 2187 parse_LD_LIBRARY_PATH(ldpath_env); 2188 parse_LD_PRELOAD(ldpreload_env); 2189 2190 somain = si; 2191 2192 if (!soinfo_link_image(si, NULL)) { 2193 __libc_format_fd(2, "CANNOT LINK EXECUTABLE: %s\n", linker_get_error_buffer()); 2194 exit(EXIT_FAILURE); 2195 } 2196 2197 add_vdso(args); 2198 2199 si->CallPreInitConstructors(); 2200 2201 for (size_t i = 0; g_ld_preloads[i] != NULL; ++i) { 2202 g_ld_preloads[i]->CallConstructors(); 2203 } 2204 2205 /* After the link_image, the si->load_bias is initialized. 2206 * For so lib, the map->l_addr will be updated in notify_gdb_of_load. 2207 * We need to update this value for so exe here. So Unwind_Backtrace 2208 * for some arch like x86 could work correctly within so exe. 2209 */ 2210 map->l_addr = si->load_bias; 2211 si->CallConstructors(); 2212 2213 #if TIMING 2214 gettimeofday(&t1, NULL); 2215 PRINT("LINKER TIME: %s: %d microseconds", args.argv[0], (int) ( 2216 (((long long)t1.tv_sec * 1000000LL) + (long long)t1.tv_usec) - 2217 (((long long)t0.tv_sec * 1000000LL) + (long long)t0.tv_usec))); 2218 #endif 2219 #if STATS 2220 PRINT("RELO STATS: %s: %d abs, %d rel, %d copy, %d symbol", args.argv[0], 2221 linker_stats.count[kRelocAbsolute], 2222 linker_stats.count[kRelocRelative], 2223 linker_stats.count[kRelocCopy], 2224 linker_stats.count[kRelocSymbol]); 2225 #endif 2226 #if COUNT_PAGES 2227 { 2228 unsigned n; 2229 unsigned i; 2230 unsigned count = 0; 2231 for (n = 0; n < 4096; n++) { 2232 if (bitmask[n]) { 2233 unsigned x = bitmask[n]; 2234 #if defined(__LP64__) 2235 for (i = 0; i < 32; i++) { 2236 #else 2237 for (i = 0; i < 8; i++) { 2238 #endif 2239 if (x & 1) { 2240 count++; 2241 } 2242 x >>= 1; 2243 } 2244 } 2245 } 2246 PRINT("PAGES MODIFIED: %s: %d (%dKB)", args.argv[0], count, count * 4); 2247 } 2248 #endif 2249 2250 #if TIMING || STATS || COUNT_PAGES 2251 fflush(stdout); 2252 #endif 2253 2254 TRACE("[ Ready to execute '%s' @ %p ]", si->name, reinterpret_cast<void*>(si->entry)); 2255 return si->entry; 2256 } 2257 2258 /* Compute the load-bias of an existing executable. This shall only 2259 * be used to compute the load bias of an executable or shared library 2260 * that was loaded by the kernel itself. 2261 * 2262 * Input: 2263 * elf -> address of ELF header, assumed to be at the start of the file. 2264 * Return: 2265 * load bias, i.e. add the value of any p_vaddr in the file to get 2266 * the corresponding address in memory. 2267 */ 2268 static ElfW(Addr) get_elf_exec_load_bias(const ElfW(Ehdr)* elf) { 2269 ElfW(Addr) offset = elf->e_phoff; 2270 const ElfW(Phdr)* phdr_table = reinterpret_cast<const ElfW(Phdr)*>(reinterpret_cast<uintptr_t>(elf) + offset); 2271 const ElfW(Phdr)* phdr_end = phdr_table + elf->e_phnum; 2272 2273 for (const ElfW(Phdr)* phdr = phdr_table; phdr < phdr_end; phdr++) { 2274 if (phdr->p_type == PT_LOAD) { 2275 return reinterpret_cast<ElfW(Addr)>(elf) + phdr->p_offset - phdr->p_vaddr; 2276 } 2277 } 2278 return 0; 2279 } 2280 2281 extern "C" void _start(); 2282 2283 /* 2284 * This is the entry point for the linker, called from begin.S. This 2285 * method is responsible for fixing the linker's own relocations, and 2286 * then calling __linker_init_post_relocation(). 2287 * 2288 * Because this method is called before the linker has fixed it's own 2289 * relocations, any attempt to reference an extern variable, extern 2290 * function, or other GOT reference will generate a segfault. 2291 */ 2292 extern "C" ElfW(Addr) __linker_init(void* raw_args) { 2293 // Initialize static variables. 2294 solist = get_libdl_info(); 2295 sonext = get_libdl_info(); 2296 2297 KernelArgumentBlock args(raw_args); 2298 2299 ElfW(Addr) linker_addr = args.getauxval(AT_BASE); 2300 ElfW(Addr) entry_point = args.getauxval(AT_ENTRY); 2301 ElfW(Ehdr)* elf_hdr = reinterpret_cast<ElfW(Ehdr)*>(linker_addr); 2302 ElfW(Phdr)* phdr = reinterpret_cast<ElfW(Phdr)*>(linker_addr + elf_hdr->e_phoff); 2303 2304 soinfo linker_so; 2305 memset(&linker_so, 0, sizeof(soinfo)); 2306 2307 // If the linker is not acting as PT_INTERP entry_point is equal to 2308 // _start. Which means that the linker is running as an executable and 2309 // already linked by PT_INTERP. 2310 // 2311 // This happens when user tries to run 'adb shell /system/bin/linker' 2312 // see also https://code.google.com/p/android/issues/detail?id=63174 2313 if (reinterpret_cast<ElfW(Addr)>(&_start) == entry_point) { 2314 __libc_fatal("This is %s, the helper program for shared library executables.\n", args.argv[0]); 2315 } 2316 2317 strcpy(linker_so.name, "[dynamic linker]"); 2318 linker_so.base = linker_addr; 2319 linker_so.size = phdr_table_get_load_size(phdr, elf_hdr->e_phnum); 2320 linker_so.load_bias = get_elf_exec_load_bias(elf_hdr); 2321 linker_so.dynamic = NULL; 2322 linker_so.phdr = phdr; 2323 linker_so.phnum = elf_hdr->e_phnum; 2324 linker_so.flags |= FLAG_LINKER; 2325 2326 if (!soinfo_link_image(&linker_so, NULL)) { 2327 // It would be nice to print an error message, but if the linker 2328 // can't link itself, there's no guarantee that we'll be able to 2329 // call write() (because it involves a GOT reference). We may as 2330 // well try though... 2331 const char* msg = "CANNOT LINK EXECUTABLE: "; 2332 write(2, msg, strlen(msg)); 2333 write(2, __linker_dl_err_buf, strlen(__linker_dl_err_buf)); 2334 write(2, "\n", 1); 2335 _exit(EXIT_FAILURE); 2336 } 2337 2338 // Initialize the linker's own global variables 2339 linker_so.CallConstructors(); 2340 2341 // We have successfully fixed our own relocations. It's safe to run 2342 // the main part of the linker now. 2343 args.abort_message_ptr = &g_abort_message; 2344 ElfW(Addr) start_address = __linker_init_post_relocation(args, linker_addr); 2345 2346 protect_data(PROT_READ); 2347 2348 // Return the address that the calling assembly stub should jump to. 2349 return start_address; 2350 } 2351