1 /* 2 * Copyright (C) 2016 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 "linker_main.h" 30 31 #include "linker_debug.h" 32 #include "linker_cfi.h" 33 #include "linker_gdb_support.h" 34 #include "linker_globals.h" 35 #include "linker_phdr.h" 36 #include "linker_utils.h" 37 38 #include "private/bionic_globals.h" 39 #include "private/bionic_tls.h" 40 #include "private/KernelArgumentBlock.h" 41 42 #include "android-base/strings.h" 43 #include "android-base/stringprintf.h" 44 #ifdef __ANDROID__ 45 #include "debuggerd/handler.h" 46 #endif 47 48 #include <async_safe/log.h> 49 50 #include <vector> 51 52 extern void __libc_init_globals(KernelArgumentBlock&); 53 extern void __libc_init_AT_SECURE(KernelArgumentBlock&); 54 55 extern "C" void _start(); 56 57 static ElfW(Addr) get_elf_exec_load_bias(const ElfW(Ehdr)* elf); 58 59 // These should be preserved static to avoid emitting 60 // RELATIVE relocations for the part of the code running 61 // before linker links itself. 62 63 // TODO (dimtiry): remove somain, rename solist to solist_head 64 static soinfo* solist; 65 static soinfo* sonext; 66 static soinfo* somain; // main process, always the one after libdl_info 67 68 void solist_add_soinfo(soinfo* si) { 69 sonext->next = si; 70 sonext = si; 71 } 72 73 bool solist_remove_soinfo(soinfo* si) { 74 soinfo *prev = nullptr, *trav; 75 for (trav = solist; trav != nullptr; trav = trav->next) { 76 if (trav == si) { 77 break; 78 } 79 prev = trav; 80 } 81 82 if (trav == nullptr) { 83 // si was not in solist 84 PRINT("name \"%s\"@%p is not in solist!", si->get_realpath(), si); 85 return false; 86 } 87 88 // prev will never be null, because the first entry in solist is 89 // always the static libdl_info. 90 CHECK(prev != nullptr); 91 prev->next = si->next; 92 if (si == sonext) { 93 sonext = prev; 94 } 95 96 return true; 97 } 98 99 soinfo* solist_get_head() { 100 return solist; 101 } 102 103 soinfo* solist_get_somain() { 104 return somain; 105 } 106 107 int g_ld_debug_verbosity; 108 abort_msg_t* g_abort_message = nullptr; // For debuggerd. 109 110 static std::vector<std::string> g_ld_preload_names; 111 112 static std::vector<soinfo*> g_ld_preloads; 113 114 static void parse_path(const char* path, const char* delimiters, 115 std::vector<std::string>* resolved_paths) { 116 std::vector<std::string> paths; 117 split_path(path, delimiters, &paths); 118 resolve_paths(paths, resolved_paths); 119 } 120 121 static void parse_LD_LIBRARY_PATH(const char* path) { 122 std::vector<std::string> ld_libary_paths; 123 parse_path(path, ":", &ld_libary_paths); 124 g_default_namespace.set_ld_library_paths(std::move(ld_libary_paths)); 125 } 126 127 static void parse_LD_PRELOAD(const char* path) { 128 g_ld_preload_names.clear(); 129 if (path != nullptr) { 130 // We have historically supported ':' as well as ' ' in LD_PRELOAD. 131 g_ld_preload_names = android::base::Split(path, " :"); 132 std::remove_if(g_ld_preload_names.begin(), 133 g_ld_preload_names.end(), 134 [] (const std::string& s) { return s.empty(); }); 135 } 136 } 137 138 // An empty list of soinfos 139 static soinfo_list_t g_empty_list; 140 141 static void add_vdso(KernelArgumentBlock& args) { 142 ElfW(Ehdr)* ehdr_vdso = reinterpret_cast<ElfW(Ehdr)*>(args.getauxval(AT_SYSINFO_EHDR)); 143 if (ehdr_vdso == nullptr) { 144 return; 145 } 146 147 soinfo* si = soinfo_alloc(&g_default_namespace, "[vdso]", nullptr, 0, 0); 148 149 si->phdr = reinterpret_cast<ElfW(Phdr)*>(reinterpret_cast<char*>(ehdr_vdso) + ehdr_vdso->e_phoff); 150 si->phnum = ehdr_vdso->e_phnum; 151 si->base = reinterpret_cast<ElfW(Addr)>(ehdr_vdso); 152 si->size = phdr_table_get_load_size(si->phdr, si->phnum); 153 si->load_bias = get_elf_exec_load_bias(ehdr_vdso); 154 155 si->prelink_image(); 156 si->link_image(g_empty_list, soinfo_list_t::make_list(si), nullptr); 157 } 158 159 /* gdb expects the linker to be in the debug shared object list. 160 * Without this, gdb has trouble locating the linker's ".text" 161 * and ".plt" sections. Gdb could also potentially use this to 162 * relocate the offset of our exported 'rtld_db_dlactivity' symbol. 163 * Note that the linker shouldn't be on the soinfo list. 164 */ 165 static link_map linker_link_map; 166 167 static void init_linker_info_for_gdb(ElfW(Addr) linker_base, char* linker_path) { 168 linker_link_map.l_addr = linker_base; 169 linker_link_map.l_name = linker_path; 170 171 /* 172 * Set the dynamic field in the link map otherwise gdb will complain with 173 * the following: 174 * warning: .dynamic section for "/system/bin/linker" is not at the 175 * expected address (wrong library or version mismatch?) 176 */ 177 ElfW(Ehdr)* elf_hdr = reinterpret_cast<ElfW(Ehdr)*>(linker_base); 178 ElfW(Phdr)* phdr = reinterpret_cast<ElfW(Phdr)*>(linker_base + elf_hdr->e_phoff); 179 phdr_table_get_dynamic_section(phdr, elf_hdr->e_phnum, linker_base, 180 &linker_link_map.l_ld, nullptr); 181 182 } 183 184 extern "C" int __system_properties_init(void); 185 186 static const char* get_executable_path() { 187 static std::string executable_path; 188 if (executable_path.empty()) { 189 char path[PATH_MAX]; 190 ssize_t path_len = readlink("/proc/self/exe", path, sizeof(path)); 191 if (path_len == -1 || path_len >= static_cast<ssize_t>(sizeof(path))) { 192 async_safe_fatal("readlink('/proc/self/exe') failed: %s", strerror(errno)); 193 } 194 executable_path = std::string(path, path_len); 195 } 196 197 return executable_path.c_str(); 198 } 199 200 #if defined(__LP64__) 201 static char kLinkerPath[] = "/system/bin/linker64"; 202 #else 203 static char kLinkerPath[] = "/system/bin/linker"; 204 #endif 205 206 /* 207 * This code is called after the linker has linked itself and 208 * fixed it's own GOT. It is safe to make references to externs 209 * and other non-local data at this point. 210 */ 211 static ElfW(Addr) __linker_init_post_relocation(KernelArgumentBlock& args) { 212 ProtectedDataGuard guard; 213 214 #if TIMING 215 struct timeval t0, t1; 216 gettimeofday(&t0, 0); 217 #endif 218 219 // Sanitize the environment. 220 __libc_init_AT_SECURE(args); 221 222 // Initialize system properties 223 __system_properties_init(); // may use 'environ' 224 225 // Register the debuggerd signal handler. 226 #ifdef __ANDROID__ 227 debuggerd_callbacks_t callbacks = { 228 .get_abort_message = []() { 229 return g_abort_message; 230 }, 231 .post_dump = ¬ify_gdb_of_libraries, 232 }; 233 debuggerd_init(&callbacks); 234 #endif 235 236 g_linker_logger.ResetState(); 237 238 // Get a few environment variables. 239 const char* LD_DEBUG = getenv("LD_DEBUG"); 240 if (LD_DEBUG != nullptr) { 241 g_ld_debug_verbosity = atoi(LD_DEBUG); 242 } 243 244 #if defined(__LP64__) 245 INFO("[ Android dynamic linker (64-bit) ]"); 246 #else 247 INFO("[ Android dynamic linker (32-bit) ]"); 248 #endif 249 250 // These should have been sanitized by __libc_init_AT_SECURE, but the test 251 // doesn't cost us anything. 252 const char* ldpath_env = nullptr; 253 const char* ldpreload_env = nullptr; 254 if (!getauxval(AT_SECURE)) { 255 ldpath_env = getenv("LD_LIBRARY_PATH"); 256 if (ldpath_env != nullptr) { 257 INFO("[ LD_LIBRARY_PATH set to \"%s\" ]", ldpath_env); 258 } 259 ldpreload_env = getenv("LD_PRELOAD"); 260 if (ldpreload_env != nullptr) { 261 INFO("[ LD_PRELOAD set to \"%s\" ]", ldpreload_env); 262 } 263 } 264 265 struct stat file_stat; 266 // Stat "/proc/self/exe" instead of executable_path because 267 // the executable could be unlinked by this point and it should 268 // not cause a crash (see http://b/31084669) 269 if (TEMP_FAILURE_RETRY(stat("/proc/self/exe", &file_stat)) != 0) { 270 async_safe_fatal("unable to stat \"/proc/self/exe\": %s", strerror(errno)); 271 } 272 273 const char* executable_path = get_executable_path(); 274 soinfo* si = soinfo_alloc(&g_default_namespace, executable_path, &file_stat, 0, RTLD_GLOBAL); 275 if (si == nullptr) { 276 async_safe_fatal("Couldn't allocate soinfo: out of memory?"); 277 } 278 279 /* bootstrap the link map, the main exe always needs to be first */ 280 si->set_main_executable(); 281 link_map* map = &(si->link_map_head); 282 283 // Register the main executable and the linker upfront to have 284 // gdb aware of them before loading the rest of the dependency 285 // tree. 286 map->l_addr = 0; 287 map->l_name = const_cast<char*>(executable_path); 288 insert_link_map_into_debug_map(map); 289 insert_link_map_into_debug_map(&linker_link_map); 290 291 // Extract information passed from the kernel. 292 si->phdr = reinterpret_cast<ElfW(Phdr)*>(args.getauxval(AT_PHDR)); 293 si->phnum = args.getauxval(AT_PHNUM); 294 295 /* Compute the value of si->base. We can't rely on the fact that 296 * the first entry is the PHDR because this will not be true 297 * for certain executables (e.g. some in the NDK unit test suite) 298 */ 299 si->base = 0; 300 si->size = phdr_table_get_load_size(si->phdr, si->phnum); 301 si->load_bias = 0; 302 for (size_t i = 0; i < si->phnum; ++i) { 303 if (si->phdr[i].p_type == PT_PHDR) { 304 si->load_bias = reinterpret_cast<ElfW(Addr)>(si->phdr) - si->phdr[i].p_vaddr; 305 si->base = reinterpret_cast<ElfW(Addr)>(si->phdr) - si->phdr[i].p_offset; 306 break; 307 } 308 } 309 310 if (si->base == 0) { 311 async_safe_fatal("Could not find a PHDR: broken executable?"); 312 } 313 314 si->dynamic = nullptr; 315 316 ElfW(Ehdr)* elf_hdr = reinterpret_cast<ElfW(Ehdr)*>(si->base); 317 318 // We haven't supported non-PIE since Lollipop for security reasons. 319 if (elf_hdr->e_type != ET_DYN) { 320 // We don't use __libc_fatal here because we don't want a tombstone: it's 321 // been several years now but we still find ourselves on app compatibility 322 // investigations because some app's trying to launch an executable that 323 // hasn't worked in at least three years, and we've "helpfully" dropped a 324 // tombstone for them. The tombstone never provided any detail relevant to 325 // fixing the problem anyway, and the utility of drawing extra attention 326 // to the problem is non-existent at this late date. 327 async_safe_format_fd(STDERR_FILENO, 328 "\"%s\": error: Android 5.0 and later only support " 329 "position-independent executables (-fPIE).\n", 330 g_argv[0]); 331 exit(EXIT_FAILURE); 332 } 333 334 // Use LD_LIBRARY_PATH and LD_PRELOAD (but only if we aren't setuid/setgid). 335 parse_LD_LIBRARY_PATH(ldpath_env); 336 parse_LD_PRELOAD(ldpreload_env); 337 338 somain = si; 339 340 std::vector<android_namespace_t*> namespaces = init_default_namespaces(executable_path); 341 342 if (!si->prelink_image()) { 343 async_safe_fatal("CANNOT LINK EXECUTABLE \"%s\": %s", g_argv[0], linker_get_error_buffer()); 344 } 345 346 // add somain to global group 347 si->set_dt_flags_1(si->get_dt_flags_1() | DF_1_GLOBAL); 348 // ... and add it to all other linked namespaces 349 for (auto linked_ns : namespaces) { 350 if (linked_ns != &g_default_namespace) { 351 linked_ns->add_soinfo(somain); 352 somain->add_secondary_namespace(linked_ns); 353 } 354 } 355 356 // Load ld_preloads and dependencies. 357 std::vector<const char*> needed_library_name_list; 358 size_t ld_preloads_count = 0; 359 360 for (const auto& ld_preload_name : g_ld_preload_names) { 361 needed_library_name_list.push_back(ld_preload_name.c_str()); 362 ++ld_preloads_count; 363 } 364 365 for_each_dt_needed(si, [&](const char* name) { 366 needed_library_name_list.push_back(name); 367 }); 368 369 const char** needed_library_names = &needed_library_name_list[0]; 370 size_t needed_libraries_count = needed_library_name_list.size(); 371 372 // readers_map is shared across recursive calls to find_libraries so that we 373 // don't need to re-load elf headers. 374 std::unordered_map<const soinfo*, ElfReader> readers_map; 375 if (needed_libraries_count > 0 && 376 !find_libraries(&g_default_namespace, 377 si, 378 needed_library_names, 379 needed_libraries_count, 380 nullptr, 381 &g_ld_preloads, 382 ld_preloads_count, 383 RTLD_GLOBAL, 384 nullptr, 385 true /* add_as_children */, 386 true /* search_linked_namespaces */, 387 readers_map, 388 &namespaces)) { 389 async_safe_fatal("CANNOT LINK EXECUTABLE \"%s\": %s", g_argv[0], linker_get_error_buffer()); 390 } else if (needed_libraries_count == 0) { 391 if (!si->link_image(g_empty_list, soinfo_list_t::make_list(si), nullptr)) { 392 async_safe_fatal("CANNOT LINK EXECUTABLE \"%s\": %s", g_argv[0], linker_get_error_buffer()); 393 } 394 si->increment_ref_count(); 395 } 396 397 add_vdso(args); 398 399 if (!get_cfi_shadow()->InitialLinkDone(solist)) { 400 async_safe_fatal("CANNOT LINK EXECUTABLE \"%s\": %s", g_argv[0], linker_get_error_buffer()); 401 } 402 403 si->call_pre_init_constructors(); 404 405 /* After the prelink_image, the si->load_bias is initialized. 406 * For so lib, the map->l_addr will be updated in notify_gdb_of_load. 407 * We need to update this value for so exe here. So Unwind_Backtrace 408 * for some arch like x86 could work correctly within so exe. 409 */ 410 map->l_addr = si->load_bias; 411 si->call_constructors(); 412 413 #if TIMING 414 gettimeofday(&t1, nullptr); 415 PRINT("LINKER TIME: %s: %d microseconds", g_argv[0], (int) ( 416 (((long long)t1.tv_sec * 1000000LL) + (long long)t1.tv_usec) - 417 (((long long)t0.tv_sec * 1000000LL) + (long long)t0.tv_usec))); 418 #endif 419 #if STATS 420 PRINT("RELO STATS: %s: %d abs, %d rel, %d copy, %d symbol", g_argv[0], 421 linker_stats.count[kRelocAbsolute], 422 linker_stats.count[kRelocRelative], 423 linker_stats.count[kRelocCopy], 424 linker_stats.count[kRelocSymbol]); 425 #endif 426 #if COUNT_PAGES 427 { 428 unsigned n; 429 unsigned i; 430 unsigned count = 0; 431 for (n = 0; n < 4096; n++) { 432 if (bitmask[n]) { 433 unsigned x = bitmask[n]; 434 #if defined(__LP64__) 435 for (i = 0; i < 32; i++) { 436 #else 437 for (i = 0; i < 8; i++) { 438 #endif 439 if (x & 1) { 440 count++; 441 } 442 x >>= 1; 443 } 444 } 445 } 446 PRINT("PAGES MODIFIED: %s: %d (%dKB)", g_argv[0], count, count * 4); 447 } 448 #endif 449 450 #if TIMING || STATS || COUNT_PAGES 451 fflush(stdout); 452 #endif 453 454 ElfW(Addr) entry = args.getauxval(AT_ENTRY); 455 TRACE("[ Ready to execute \"%s\" @ %p ]", si->get_realpath(), reinterpret_cast<void*>(entry)); 456 return entry; 457 } 458 459 /* Compute the load-bias of an existing executable. This shall only 460 * be used to compute the load bias of an executable or shared library 461 * that was loaded by the kernel itself. 462 * 463 * Input: 464 * elf -> address of ELF header, assumed to be at the start of the file. 465 * Return: 466 * load bias, i.e. add the value of any p_vaddr in the file to get 467 * the corresponding address in memory. 468 */ 469 static ElfW(Addr) get_elf_exec_load_bias(const ElfW(Ehdr)* elf) { 470 ElfW(Addr) offset = elf->e_phoff; 471 const ElfW(Phdr)* phdr_table = 472 reinterpret_cast<const ElfW(Phdr)*>(reinterpret_cast<uintptr_t>(elf) + offset); 473 const ElfW(Phdr)* phdr_end = phdr_table + elf->e_phnum; 474 475 for (const ElfW(Phdr)* phdr = phdr_table; phdr < phdr_end; phdr++) { 476 if (phdr->p_type == PT_LOAD) { 477 return reinterpret_cast<ElfW(Addr)>(elf) + phdr->p_offset - phdr->p_vaddr; 478 } 479 } 480 return 0; 481 } 482 483 static void __linker_cannot_link(const char* argv0) { 484 async_safe_fatal("CANNOT LINK EXECUTABLE \"%s\": %s", argv0, linker_get_error_buffer()); 485 } 486 487 /* 488 * This is the entry point for the linker, called from begin.S. This 489 * method is responsible for fixing the linker's own relocations, and 490 * then calling __linker_init_post_relocation(). 491 * 492 * Because this method is called before the linker has fixed it's own 493 * relocations, any attempt to reference an extern variable, extern 494 * function, or other GOT reference will generate a segfault. 495 */ 496 extern "C" ElfW(Addr) __linker_init(void* raw_args) { 497 KernelArgumentBlock args(raw_args); 498 499 // AT_BASE is set to 0 in the case when linker is run by iself 500 // so in order to link the linker it needs to calcuate AT_BASE 501 // using information at hand. The trick below takes advantage 502 // of the fact that the value of linktime_addr before relocations 503 // are run is an offset and this can be used to calculate AT_BASE. 504 static uintptr_t linktime_addr = reinterpret_cast<uintptr_t>(&linktime_addr); 505 ElfW(Addr) linker_addr = reinterpret_cast<uintptr_t>(&linktime_addr) - linktime_addr; 506 507 #if defined(__clang_analyzer__) 508 // The analyzer assumes that linker_addr will always be null. Make it an 509 // unknown value so we don't have to mark N places with NOLINTs. 510 // 511 // (`+=`, rather than `=`, allows us to sidestep a potential "unused store" 512 // complaint) 513 linker_addr += reinterpret_cast<uintptr_t>(raw_args); 514 #endif 515 516 ElfW(Addr) entry_point = args.getauxval(AT_ENTRY); 517 ElfW(Ehdr)* elf_hdr = reinterpret_cast<ElfW(Ehdr)*>(linker_addr); 518 ElfW(Phdr)* phdr = reinterpret_cast<ElfW(Phdr)*>(linker_addr + elf_hdr->e_phoff); 519 520 soinfo linker_so(nullptr, nullptr, nullptr, 0, 0); 521 522 linker_so.base = linker_addr; 523 linker_so.size = phdr_table_get_load_size(phdr, elf_hdr->e_phnum); 524 linker_so.load_bias = get_elf_exec_load_bias(elf_hdr); 525 linker_so.dynamic = nullptr; 526 linker_so.phdr = phdr; 527 linker_so.phnum = elf_hdr->e_phnum; 528 linker_so.set_linker_flag(); 529 530 // Prelink the linker so we can access linker globals. 531 if (!linker_so.prelink_image()) __linker_cannot_link(args.argv[0]); 532 533 // This might not be obvious... The reasons why we pass g_empty_list 534 // in place of local_group here are (1) we do not really need it, because 535 // linker is built with DT_SYMBOLIC and therefore relocates its symbols against 536 // itself without having to look into local_group and (2) allocators 537 // are not yet initialized, and therefore we cannot use linked_list.push_* 538 // functions at this point. 539 if (!linker_so.link_image(g_empty_list, g_empty_list, nullptr)) __linker_cannot_link(args.argv[0]); 540 541 #if defined(__i386__) 542 // On x86, we can't make system calls before this point. 543 // We can't move this up because this needs to assign to a global. 544 // Note that until we call __libc_init_main_thread below we have 545 // no TLS, so you shouldn't make a system call that can fail, because 546 // it will SEGV when it tries to set errno. 547 __libc_init_sysinfo(args); 548 #endif 549 550 // Initialize the main thread (including TLS, so system calls really work). 551 __libc_init_main_thread(args); 552 553 // We didn't protect the linker's RELRO pages in link_image because we 554 // couldn't make system calls on x86 at that point, but we can now... 555 if (!linker_so.protect_relro()) __linker_cannot_link(args.argv[0]); 556 557 // Initialize the linker's static libc's globals 558 __libc_init_globals(args); 559 560 // store argc/argv/envp to use them for calling constructors 561 g_argc = args.argc; 562 g_argv = args.argv; 563 g_envp = args.envp; 564 565 // Initialize the linker's own global variables 566 linker_so.call_constructors(); 567 568 // If the linker is not acting as PT_INTERP entry_point is equal to 569 // _start. Which means that the linker is running as an executable and 570 // already linked by PT_INTERP. 571 // 572 // This happens when user tries to run 'adb shell /system/bin/linker' 573 // see also https://code.google.com/p/android/issues/detail?id=63174 574 if (reinterpret_cast<ElfW(Addr)>(&_start) == entry_point) { 575 async_safe_format_fd(STDOUT_FILENO, 576 "This is %s, the helper program for dynamic executables.\n", 577 args.argv[0]); 578 exit(0); 579 } 580 581 init_linker_info_for_gdb(linker_addr, kLinkerPath); 582 583 // Initialize static variables. Note that in order to 584 // get correct libdl_info we need to call constructors 585 // before get_libdl_info(). 586 sonext = solist = get_libdl_info(kLinkerPath, linker_link_map); 587 g_default_namespace.add_soinfo(solist); 588 589 // We have successfully fixed our own relocations. It's safe to run 590 // the main part of the linker now. 591 args.abort_message_ptr = &g_abort_message; 592 ElfW(Addr) start_address = __linker_init_post_relocation(args); 593 594 INFO("[ Jumping to _start (%p)... ]", reinterpret_cast<void*>(start_address)); 595 596 // Return the address that the calling assembly stub should jump to. 597 return start_address; 598 } 599