93400371f7
Normally, platform-specific note types in the toolchain are prefixed with the platform name. Because we're exposing the NT_TYPE_MEMTAG and synthesizing the note in the toolchain in an upcoming patch (https://reviews.llvm.org/D118948), it's been requested that we change the name to include the platform prefix. While NT_TYPE_IDENT and NT_TYPE_KUSER aren't known about or synthesized by the toolchain, update those references as well for consistency. Bug: N/A Test: Build Android Change-Id: I7742e4917ae275d59d7984991664ea48028053a1
427 lines
16 KiB
C++
427 lines
16 KiB
C++
/*
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* Copyright (C) 2008 The Android Open Source Project
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* * Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* * Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
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* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
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* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include <android/api-level.h>
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#include <elf.h>
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#include <errno.h>
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#include <stddef.h>
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#include <stdint.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <sys/auxv.h>
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#include <sys/mman.h>
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#include "libc_init_common.h"
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#include "pthread_internal.h"
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#include "platform/bionic/macros.h"
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#include "platform/bionic/mte.h"
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#include "platform/bionic/page.h"
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#include "platform/bionic/reserved_signals.h"
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#include "private/KernelArgumentBlock.h"
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#include "private/bionic_asm.h"
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#include "private/bionic_asm_note.h"
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#include "private/bionic_call_ifunc_resolver.h"
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#include "private/bionic_elf_tls.h"
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#include "private/bionic_globals.h"
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#include "private/bionic_tls.h"
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#include "sys/system_properties.h"
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#if __has_feature(hwaddress_sanitizer)
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#include <sanitizer/hwasan_interface.h>
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#endif
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// Leave the variable uninitialized for the sake of the dynamic loader, which
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// links in this file. The loader will initialize this variable before
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// relocating itself.
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#if defined(__i386__)
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__LIBC_HIDDEN__ void* __libc_sysinfo;
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#endif
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extern "C" int __cxa_atexit(void (*)(void *), void *, void *);
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extern "C" const char* __gnu_basename(const char* path);
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static void call_array(init_func_t** list, int argc, char* argv[], char* envp[]) {
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// First element is -1, list is null-terminated
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while (*++list) {
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(*list)(argc, argv, envp);
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}
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}
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#if defined(__aarch64__) || defined(__x86_64__)
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extern __LIBC_HIDDEN__ __attribute__((weak)) ElfW(Rela) __rela_iplt_start[], __rela_iplt_end[];
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static void call_ifunc_resolvers() {
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if (__rela_iplt_start == nullptr || __rela_iplt_end == nullptr) {
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// These symbols are not emitted by gold. Gold has code to do so, but for
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// whatever reason it is not being run. In these cases ifuncs cannot be
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// resolved, so we do not support using ifuncs in static executables linked
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// with gold.
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//
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// Since they are weak, they will be non-null when linked with bfd/lld and
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// null when linked with gold.
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return;
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}
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for (ElfW(Rela) *r = __rela_iplt_start; r != __rela_iplt_end; ++r) {
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ElfW(Addr)* offset = reinterpret_cast<ElfW(Addr)*>(r->r_offset);
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ElfW(Addr) resolver = r->r_addend;
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*offset = __bionic_call_ifunc_resolver(resolver);
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}
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}
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#else
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extern __LIBC_HIDDEN__ __attribute__((weak)) ElfW(Rel) __rel_iplt_start[], __rel_iplt_end[];
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static void call_ifunc_resolvers() {
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if (__rel_iplt_start == nullptr || __rel_iplt_end == nullptr) {
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// These symbols are not emitted by gold. Gold has code to do so, but for
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// whatever reason it is not being run. In these cases ifuncs cannot be
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// resolved, so we do not support using ifuncs in static executables linked
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// with gold.
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//
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// Since they are weak, they will be non-null when linked with bfd/lld and
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// null when linked with gold.
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return;
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}
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for (ElfW(Rel) *r = __rel_iplt_start; r != __rel_iplt_end; ++r) {
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ElfW(Addr)* offset = reinterpret_cast<ElfW(Addr)*>(r->r_offset);
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ElfW(Addr) resolver = *offset;
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*offset = __bionic_call_ifunc_resolver(resolver);
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}
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}
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#endif
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static void apply_gnu_relro() {
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ElfW(Phdr)* phdr_start = reinterpret_cast<ElfW(Phdr)*>(getauxval(AT_PHDR));
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unsigned long int phdr_ct = getauxval(AT_PHNUM);
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for (ElfW(Phdr)* phdr = phdr_start; phdr < (phdr_start + phdr_ct); phdr++) {
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if (phdr->p_type != PT_GNU_RELRO) {
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continue;
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}
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ElfW(Addr) seg_page_start = PAGE_START(phdr->p_vaddr);
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ElfW(Addr) seg_page_end = PAGE_END(phdr->p_vaddr + phdr->p_memsz);
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// Check return value here? What do we do if we fail?
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mprotect(reinterpret_cast<void*>(seg_page_start), seg_page_end - seg_page_start, PROT_READ);
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}
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}
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static void layout_static_tls(KernelArgumentBlock& args) {
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StaticTlsLayout& layout = __libc_shared_globals()->static_tls_layout;
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layout.reserve_bionic_tls();
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const char* progname = args.argv[0];
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ElfW(Phdr)* phdr_start = reinterpret_cast<ElfW(Phdr)*>(getauxval(AT_PHDR));
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size_t phdr_ct = getauxval(AT_PHNUM);
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static TlsModule mod;
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TlsModules& modules = __libc_shared_globals()->tls_modules;
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if (__bionic_get_tls_segment(phdr_start, phdr_ct, 0, &mod.segment)) {
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if (!__bionic_check_tls_alignment(&mod.segment.alignment)) {
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async_safe_fatal("error: TLS segment alignment in \"%s\" is not a power of 2: %zu\n",
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progname, mod.segment.alignment);
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}
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mod.static_offset = layout.reserve_exe_segment_and_tcb(&mod.segment, progname);
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mod.first_generation = kTlsGenerationFirst;
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modules.module_count = 1;
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modules.static_module_count = 1;
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modules.module_table = &mod;
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} else {
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layout.reserve_exe_segment_and_tcb(nullptr, progname);
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}
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// Enable the fast path in __tls_get_addr.
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__libc_tls_generation_copy = modules.generation;
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layout.finish_layout();
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}
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// Get the presiding config string, in the following order of priority:
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// 1. Environment variables.
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// 2. System properties, in the order they're specified in sys_prop_names.
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// If neither of these options are specified, this function returns false.
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// Otherwise, it returns true, and the presiding options string is written to
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// the `options` buffer of size `size`. If this function returns true, `options`
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// is guaranteed to be null-terminated. `options_size` should be at least
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// PROP_VALUE_MAX.
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bool get_config_from_env_or_sysprops(const char* env_var_name, const char* const* sys_prop_names,
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size_t sys_prop_names_size, char* options,
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size_t options_size) {
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const char* env = getenv(env_var_name);
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if (env && *env != '\0') {
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strncpy(options, env, options_size);
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options[options_size - 1] = '\0'; // Ensure null-termination.
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return true;
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}
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for (size_t i = 0; i < sys_prop_names_size; ++i) {
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if (__system_property_get(sys_prop_names[i], options) && *options != '\0') return true;
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}
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return false;
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}
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#ifdef __aarch64__
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static bool __read_memtag_note(const ElfW(Nhdr)* note, const char* name, const char* desc,
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unsigned* result) {
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if (note->n_namesz != 8 || strncmp(name, "Android", 8) != 0) {
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return false;
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}
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if (note->n_type != NT_ANDROID_TYPE_MEMTAG) {
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return false;
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}
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if (note->n_descsz != 4) {
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async_safe_fatal("unrecognized android.memtag note: n_descsz = %d, expected 4", note->n_descsz);
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}
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*result = *reinterpret_cast<const ElfW(Word)*>(desc);
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return true;
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}
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static unsigned __get_memtag_note(const ElfW(Phdr)* phdr_start, size_t phdr_ct,
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const ElfW(Addr) load_bias) {
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for (size_t i = 0; i < phdr_ct; ++i) {
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const ElfW(Phdr)* phdr = &phdr_start[i];
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if (phdr->p_type != PT_NOTE) {
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continue;
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}
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ElfW(Addr) p = load_bias + phdr->p_vaddr;
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ElfW(Addr) note_end = load_bias + phdr->p_vaddr + phdr->p_memsz;
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while (p + sizeof(ElfW(Nhdr)) <= note_end) {
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const ElfW(Nhdr)* note = reinterpret_cast<const ElfW(Nhdr)*>(p);
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p += sizeof(ElfW(Nhdr));
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const char* name = reinterpret_cast<const char*>(p);
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p += align_up(note->n_namesz, 4);
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const char* desc = reinterpret_cast<const char*>(p);
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p += align_up(note->n_descsz, 4);
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if (p > note_end) {
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break;
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}
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unsigned ret;
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if (__read_memtag_note(note, name, desc, &ret)) {
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return ret;
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}
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}
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}
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return 0;
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}
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// Returns true if there's an environment setting (either sysprop or env var)
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// that should overwrite the ELF note, and places the equivalent heap tagging
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// level into *level.
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static bool get_environment_memtag_setting(HeapTaggingLevel* level) {
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static const char kMemtagPrognameSyspropPrefix[] = "arm64.memtag.process.";
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const char* progname = __libc_shared_globals()->init_progname;
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if (progname == nullptr) return false;
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const char* basename = __gnu_basename(progname);
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static constexpr size_t kOptionsSize = PROP_VALUE_MAX;
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char options_str[kOptionsSize];
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size_t sysprop_size = strlen(basename) + strlen(kMemtagPrognameSyspropPrefix) + 1;
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char* sysprop_name = static_cast<char*>(alloca(sysprop_size));
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async_safe_format_buffer(sysprop_name, sysprop_size, "%s%s", kMemtagPrognameSyspropPrefix,
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basename);
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if (!get_config_from_env_or_sysprops("MEMTAG_OPTIONS", &sysprop_name,
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/* sys_prop_names_size */ 1, options_str, kOptionsSize)) {
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return false;
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}
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if (strcmp("sync", options_str) == 0) {
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*level = M_HEAP_TAGGING_LEVEL_SYNC;
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} else if (strcmp("async", options_str) == 0) {
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*level = M_HEAP_TAGGING_LEVEL_ASYNC;
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} else if (strcmp("off", options_str) == 0) {
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*level = M_HEAP_TAGGING_LEVEL_TBI;
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} else {
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async_safe_format_log(
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ANDROID_LOG_ERROR, "libc",
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"unrecognized memtag level: \"%s\" (options are \"sync\", \"async\", or \"off\").",
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options_str);
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return false;
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}
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return true;
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}
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// Returns the initial heap tagging level. Note: This function will never return
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// M_HEAP_TAGGING_LEVEL_NONE, if MTE isn't enabled for this process we enable
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// M_HEAP_TAGGING_LEVEL_TBI.
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static HeapTaggingLevel __get_heap_tagging_level(const void* phdr_start, size_t phdr_ct,
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uintptr_t load_bias) {
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HeapTaggingLevel level;
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if (get_environment_memtag_setting(&level)) return level;
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unsigned note_val =
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__get_memtag_note(reinterpret_cast<const ElfW(Phdr)*>(phdr_start), phdr_ct, load_bias);
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if (note_val & ~(NT_MEMTAG_LEVEL_MASK | NT_MEMTAG_HEAP)) {
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async_safe_fatal("unrecognized android.memtag note: desc = %d", note_val);
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}
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if (!(note_val & NT_MEMTAG_HEAP)) return M_HEAP_TAGGING_LEVEL_TBI;
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unsigned memtag_level = note_val & NT_MEMTAG_LEVEL_MASK;
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switch (memtag_level) {
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case NT_MEMTAG_LEVEL_ASYNC:
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return M_HEAP_TAGGING_LEVEL_ASYNC;
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case NT_MEMTAG_LEVEL_DEFAULT:
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case NT_MEMTAG_LEVEL_SYNC:
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return M_HEAP_TAGGING_LEVEL_SYNC;
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default:
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async_safe_fatal("unrecognized android.memtag note: level = %d", memtag_level);
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}
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}
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// Figure out the desired memory tagging mode (sync/async, heap/globals/stack) for this executable.
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// This function is called from the linker before the main executable is relocated.
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__attribute__((no_sanitize("hwaddress", "memtag"))) void __libc_init_mte(const void* phdr_start,
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size_t phdr_ct,
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uintptr_t load_bias) {
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HeapTaggingLevel level = __get_heap_tagging_level(phdr_start, phdr_ct, load_bias);
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if (level == M_HEAP_TAGGING_LEVEL_SYNC || level == M_HEAP_TAGGING_LEVEL_ASYNC) {
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unsigned long prctl_arg = PR_TAGGED_ADDR_ENABLE | PR_MTE_TAG_SET_NONZERO;
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prctl_arg |= (level == M_HEAP_TAGGING_LEVEL_SYNC) ? PR_MTE_TCF_SYNC : PR_MTE_TCF_ASYNC;
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// When entering ASYNC mode, specify that we want to allow upgrading to SYNC by OR'ing in the
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// SYNC flag. But if the kernel doesn't support specifying multiple TCF modes, fall back to
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// specifying a single mode.
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if (prctl(PR_SET_TAGGED_ADDR_CTRL, prctl_arg | PR_MTE_TCF_SYNC, 0, 0, 0) == 0 ||
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prctl(PR_SET_TAGGED_ADDR_CTRL, prctl_arg, 0, 0, 0) == 0) {
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__libc_shared_globals()->initial_heap_tagging_level = level;
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return;
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}
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}
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// MTE was either not enabled, or wasn't supported on this device. Try and use
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// TBI.
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if (prctl(PR_SET_TAGGED_ADDR_CTRL, PR_TAGGED_ADDR_ENABLE, 0, 0, 0) == 0) {
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__libc_shared_globals()->initial_heap_tagging_level = M_HEAP_TAGGING_LEVEL_TBI;
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}
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}
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#else // __aarch64__
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void __libc_init_mte(const void*, size_t, uintptr_t) {}
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#endif // __aarch64__
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void __libc_init_profiling_handlers() {
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// The dynamic variant of this function is more interesting, but this
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// at least ensures that static binaries aren't killed by the kernel's
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// default disposition for these two real-time signals that would have
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// handlers installed if this was a dynamic binary.
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signal(BIONIC_SIGNAL_PROFILER, SIG_IGN);
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signal(BIONIC_SIGNAL_ART_PROFILER, SIG_IGN);
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}
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__noreturn static void __real_libc_init(void *raw_args,
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void (*onexit)(void) __unused,
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int (*slingshot)(int, char**, char**),
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structors_array_t const * const structors,
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bionic_tcb* temp_tcb) {
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BIONIC_STOP_UNWIND;
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// Initialize TLS early so system calls and errno work.
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KernelArgumentBlock args(raw_args);
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__libc_init_main_thread_early(args, temp_tcb);
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__libc_init_main_thread_late();
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__libc_init_globals();
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__libc_shared_globals()->init_progname = args.argv[0];
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__libc_init_AT_SECURE(args.envp);
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layout_static_tls(args);
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__libc_init_main_thread_final();
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__libc_init_common();
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__libc_init_mte(reinterpret_cast<ElfW(Phdr)*>(getauxval(AT_PHDR)), getauxval(AT_PHNUM),
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/*load_bias = */ 0);
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__libc_init_scudo();
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__libc_init_profiling_handlers();
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__libc_init_fork_handler();
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call_ifunc_resolvers();
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apply_gnu_relro();
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// Several Linux ABIs don't pass the onexit pointer, and the ones that
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// do never use it. Therefore, we ignore it.
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call_array(structors->preinit_array, args.argc, args.argv, args.envp);
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call_array(structors->init_array, args.argc, args.argv, args.envp);
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// The executable may have its own destructors listed in its .fini_array
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// so we need to ensure that these are called when the program exits
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// normally.
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if (structors->fini_array != nullptr) {
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__cxa_atexit(__libc_fini,structors->fini_array,nullptr);
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}
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exit(slingshot(args.argc, args.argv, args.envp));
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}
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extern "C" void __hwasan_init_static();
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// This __libc_init() is only used for static executables, and is called from crtbegin.c.
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//
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// The 'structors' parameter contains pointers to various initializer
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// arrays that must be run before the program's 'main' routine is launched.
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__attribute__((no_sanitize("hwaddress")))
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__noreturn void __libc_init(void* raw_args,
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void (*onexit)(void) __unused,
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int (*slingshot)(int, char**, char**),
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structors_array_t const * const structors) {
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bionic_tcb temp_tcb = {};
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#if __has_feature(hwaddress_sanitizer)
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// Install main thread TLS early. It will be initialized later in __libc_init_main_thread. For now
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// all we need is access to TLS_SLOT_SANITIZER.
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__set_tls(&temp_tcb.tls_slot(0));
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// Initialize HWASan enough to run instrumented code. This sets up TLS_SLOT_SANITIZER, among other
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// things.
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__hwasan_init_static();
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// We are ready to run HWASan-instrumented code, proceed with libc initialization...
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#endif
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__real_libc_init(raw_args, onexit, slingshot, structors, &temp_tcb);
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}
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static int g_target_sdk_version{__ANDROID_API__};
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extern "C" int android_get_application_target_sdk_version() {
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return g_target_sdk_version;
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}
|
|
|
|
extern "C" void android_set_application_target_sdk_version(int target) {
|
|
g_target_sdk_version = target;
|
|
__libc_set_target_sdk_version(target);
|
|
}
|
|
|
|
// This function is called in the dynamic linker before ifunc resolvers have run, so this file is
|
|
// compiled with -ffreestanding to avoid implicit string.h function calls. (It shouldn't strictly
|
|
// be necessary, though.)
|
|
__LIBC_HIDDEN__ libc_shared_globals* __libc_shared_globals() {
|
|
static libc_shared_globals globals;
|
|
return &globals;
|
|
}
|