/*
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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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#pragma once
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#include <pthread.h>
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#include <stdatomic.h>
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#if __has_feature(hwaddress_sanitizer)
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#include <sanitizer/hwasan_interface.h>
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#else
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#define __hwasan_thread_enter()
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#define __hwasan_thread_exit()
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#endif
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#include "private/bionic_elf_tls.h"
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#include "private/bionic_lock.h"
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#include "private/bionic_tls.h"
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// Has the thread been detached by a pthread_join or pthread_detach call?
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#define PTHREAD_ATTR_FLAG_DETACHED 0x00000001
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// Has the thread been joined by another thread?
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#define PTHREAD_ATTR_FLAG_JOINED 0x00000002
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// Used for pthread_attr_setinheritsched. We need two flags for this apparent
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// boolean because our historical behavior matches neither of the POSIX choices.
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#define PTHREAD_ATTR_FLAG_INHERIT 0x00000004
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#define PTHREAD_ATTR_FLAG_EXPLICIT 0x00000008
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enum ThreadJoinState {
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THREAD_NOT_JOINED,
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THREAD_EXITED_NOT_JOINED,
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THREAD_JOINED,
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THREAD_DETACHED
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};
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class thread_local_dtor;
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class pthread_internal_t {
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public:
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class pthread_internal_t* next;
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class pthread_internal_t* prev;
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pid_t tid;
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private:
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pid_t cached_pid_;
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public:
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pid_t invalidate_cached_pid() {
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pid_t old_value;
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get_cached_pid(&old_value);
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set_cached_pid(0);
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return old_value;
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}
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void set_cached_pid(pid_t value) {
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cached_pid_ = value;
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}
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bool get_cached_pid(pid_t* cached_pid) {
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*cached_pid = cached_pid_;
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return (*cached_pid != 0);
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}
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pthread_attr_t attr;
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_Atomic(ThreadJoinState) join_state;
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__pthread_cleanup_t* cleanup_stack;
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void* (*start_routine)(void*);
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void* start_routine_arg;
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void* return_value;
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void* alternate_signal_stack;
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// The start address of the shadow call stack's guard region (arm64 only).
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// This address is only used to deallocate the shadow call stack on thread
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// exit; the address of the stack itself is stored only in the x18 register.
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// Because the protection offered by SCS relies on the secrecy of the stack
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// address, storing the address here weakens the protection, but only
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// slightly, because it is relatively easy for an attacker to discover the
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// address of the guard region anyway (e.g. it can be discovered by reference
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// to other allocations), but not the stack itself, which is <0.1% of the size
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// of the guard region.
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//
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// There are at least two other options for discovering the start address of
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// the guard region on thread exit, but they are not as simple as storing in
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// TLS.
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// 1) Derive it from the value of the x18 register. This is only possible in
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// processes that do not contain legacy code that might clobber x18,
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// therefore each process must declare early during process startup whether
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// it might load legacy code.
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// 2) Mark the guard region as such using prctl(PR_SET_VMA_ANON_NAME) and
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// discover its address by reading /proc/self/maps. One issue with this is
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// that reading /proc/self/maps can race with allocations, so we may need
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// code to handle retries.
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void* shadow_call_stack_guard_region;
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Lock startup_handshake_lock;
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void* mmap_base;
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size_t mmap_size;
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thread_local_dtor* thread_local_dtors;
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/*
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* The dynamic linker implements dlerror(3), which makes it hard for us to implement this
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* per-thread buffer by simply using malloc(3) and free(3).
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*/
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char* current_dlerror;
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#define __BIONIC_DLERROR_BUFFER_SIZE 512
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char dlerror_buffer[__BIONIC_DLERROR_BUFFER_SIZE];
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bionic_tls* bionic_tls;
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int errno_value;
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};
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struct ThreadMapping {
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char* mmap_base;
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size_t mmap_size;
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char* static_tls;
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char* stack_base;
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char* stack_top;
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};
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__LIBC_HIDDEN__ void __init_tcb(bionic_tcb* tcb, pthread_internal_t* thread);
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__LIBC_HIDDEN__ void __init_tcb_stack_guard(bionic_tcb* tcb);
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__LIBC_HIDDEN__ void __init_tcb_dtv(bionic_tcb* tcb);
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__LIBC_HIDDEN__ void __init_bionic_tls_ptrs(bionic_tcb* tcb, bionic_tls* tls);
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__LIBC_HIDDEN__ bionic_tls* __allocate_temp_bionic_tls();
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__LIBC_HIDDEN__ void __free_temp_bionic_tls(bionic_tls* tls);
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__LIBC_HIDDEN__ void __init_additional_stacks(pthread_internal_t*);
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__LIBC_HIDDEN__ int __init_thread(pthread_internal_t* thread);
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__LIBC_HIDDEN__ ThreadMapping __allocate_thread_mapping(size_t stack_size, size_t stack_guard_size);
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__LIBC_HIDDEN__ pthread_t __pthread_internal_add(pthread_internal_t* thread);
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__LIBC_HIDDEN__ pthread_internal_t* __pthread_internal_find(pthread_t pthread_id, const char* caller);
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__LIBC_HIDDEN__ pid_t __pthread_internal_gettid(pthread_t pthread_id, const char* caller);
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__LIBC_HIDDEN__ void __pthread_internal_remove(pthread_internal_t* thread);
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__LIBC_HIDDEN__ void __pthread_internal_remove_and_free(pthread_internal_t* thread);
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static inline __always_inline bionic_tcb* __get_bionic_tcb() {
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return reinterpret_cast<bionic_tcb*>(&__get_tls()[MIN_TLS_SLOT]);
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}
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// Make __get_thread() inlined for performance reason. See http://b/19825434.
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static inline __always_inline pthread_internal_t* __get_thread() {
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return static_cast<pthread_internal_t*>(__get_tls()[TLS_SLOT_THREAD_ID]);
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}
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static inline __always_inline bionic_tls& __get_bionic_tls() {
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return *static_cast<bionic_tls*>(__get_tls()[TLS_SLOT_BIONIC_TLS]);
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}
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static inline __always_inline TlsDtv* __get_tcb_dtv(bionic_tcb* tcb) {
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uintptr_t dtv_slot = reinterpret_cast<uintptr_t>(tcb->tls_slot(TLS_SLOT_DTV));
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return reinterpret_cast<TlsDtv*>(dtv_slot - offsetof(TlsDtv, generation));
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}
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static inline void __set_tcb_dtv(bionic_tcb* tcb, TlsDtv* val) {
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tcb->tls_slot(TLS_SLOT_DTV) = &val->generation;
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}
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extern "C" __LIBC_HIDDEN__ int __set_tls(void* ptr);
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__LIBC_HIDDEN__ void pthread_key_clean_all(void);
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// Address space is precious on LP32, so use the minimum unit: one page.
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// On LP64, we could use more but there's no obvious advantage to doing
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// so, and the various media processes use RLIMIT_AS as a way to limit
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// the amount of allocation they'll do.
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#define PTHREAD_GUARD_SIZE PAGE_SIZE
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// SIGSTKSZ (8KiB) is not big enough.
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// An snprintf to a stack buffer of size PATH_MAX consumes ~7KiB of stack.
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// On 64-bit, logging uses more than 8KiB by itself, ucontext is comically
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// large on aarch64, and we have effectively infinite address space, so double
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// the signal stack size.
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#if defined(__LP64__)
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#define SIGNAL_STACK_SIZE_WITHOUT_GUARD (32 * 1024)
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#else
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#define SIGNAL_STACK_SIZE_WITHOUT_GUARD (16 * 1024)
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#endif
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// Traditionally we gave threads a 1MiB stack. When we started
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// allocating per-thread alternate signal stacks to ease debugging of
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// stack overflows, we subtracted the same amount we were using there
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// from the default thread stack size. This should keep memory usage
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// roughly constant.
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#define PTHREAD_STACK_SIZE_DEFAULT ((1 * 1024 * 1024) - SIGNAL_STACK_SIZE_WITHOUT_GUARD)
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// Leave room for a guard page in the internally created signal stacks.
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#define SIGNAL_STACK_SIZE (SIGNAL_STACK_SIZE_WITHOUT_GUARD + PTHREAD_GUARD_SIZE)
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// Needed by fork.
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__LIBC_HIDDEN__ extern void __bionic_atfork_run_prepare();
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__LIBC_HIDDEN__ extern void __bionic_atfork_run_child();
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__LIBC_HIDDEN__ extern void __bionic_atfork_run_parent();
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