1 /* 2 * Copyright (C) 2008 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 <pthread.h> 30 31 #include <signal.h> 32 #include <stdlib.h> 33 #include <string.h> 34 #include <sys/mman.h> 35 36 #include "private/bionic_constants.h" 37 #include "private/bionic_defs.h" 38 #include "private/ScopedSignalBlocker.h" 39 #include "pthread_internal.h" 40 41 extern "C" __noreturn void _exit_with_stack_teardown(void*, size_t); 42 extern "C" __noreturn void __exit(int); 43 extern "C" int __set_tid_address(int*); 44 extern "C" void __cxa_thread_finalize(); 45 46 /* CAVEAT: our implementation of pthread_cleanup_push/pop doesn't support C++ exceptions 47 * and thread cancelation 48 */ 49 50 __BIONIC_WEAK_FOR_NATIVE_BRIDGE 51 void __pthread_cleanup_push(__pthread_cleanup_t* c, __pthread_cleanup_func_t routine, void* arg) { 52 pthread_internal_t* thread = __get_thread(); 53 c->__cleanup_routine = routine; 54 c->__cleanup_arg = arg; 55 c->__cleanup_prev = thread->cleanup_stack; 56 thread->cleanup_stack = c; 57 } 58 59 __BIONIC_WEAK_FOR_NATIVE_BRIDGE 60 void __pthread_cleanup_pop(__pthread_cleanup_t* c, int execute) { 61 pthread_internal_t* thread = __get_thread(); 62 thread->cleanup_stack = c->__cleanup_prev; 63 if (execute) { 64 c->__cleanup_routine(c->__cleanup_arg); 65 } 66 } 67 68 __BIONIC_WEAK_FOR_NATIVE_BRIDGE 69 void pthread_exit(void* return_value) { 70 // Call dtors for thread_local objects first. 71 __cxa_thread_finalize(); 72 73 pthread_internal_t* thread = __get_thread(); 74 thread->return_value = return_value; 75 76 // Call the cleanup handlers. 77 while (thread->cleanup_stack) { 78 __pthread_cleanup_t* c = thread->cleanup_stack; 79 thread->cleanup_stack = c->__cleanup_prev; 80 c->__cleanup_routine(c->__cleanup_arg); 81 } 82 83 // Call the TLS destructors. It is important to do that before removing this 84 // thread from the global list. This will ensure that if someone else deletes 85 // a TLS key, the corresponding value will be set to NULL in this thread's TLS 86 // space (see pthread_key_delete). 87 pthread_key_clean_all(); 88 89 if (thread->alternate_signal_stack != nullptr) { 90 // Tell the kernel to stop using the alternate signal stack. 91 stack_t ss; 92 memset(&ss, 0, sizeof(ss)); 93 ss.ss_flags = SS_DISABLE; 94 sigaltstack(&ss, nullptr); 95 96 // Free it. 97 munmap(thread->alternate_signal_stack, SIGNAL_STACK_SIZE); 98 thread->alternate_signal_stack = nullptr; 99 } 100 101 ThreadJoinState old_state = THREAD_NOT_JOINED; 102 while (old_state == THREAD_NOT_JOINED && 103 !atomic_compare_exchange_weak(&thread->join_state, &old_state, THREAD_EXITED_NOT_JOINED)) { 104 } 105 106 // We don't want to take a signal after unmapping the stack, the shadow call 107 // stack, or dynamic TLS memory. 108 ScopedSignalBlocker ssb; 109 110 #ifdef __aarch64__ 111 // Free the shadow call stack and guard pages. 112 munmap(thread->shadow_call_stack_guard_region, SCS_GUARD_REGION_SIZE); 113 #endif 114 115 // Free the ELF TLS DTV and all dynamically-allocated ELF TLS memory. 116 __free_dynamic_tls(__get_bionic_tcb()); 117 118 if (old_state == THREAD_DETACHED) { 119 // The thread is detached, no one will use pthread_internal_t after pthread_exit. 120 // So we can free mapped space, which includes pthread_internal_t and thread stack. 121 // First make sure that the kernel does not try to clear the tid field 122 // because we'll have freed the memory before the thread actually exits. 123 __set_tid_address(nullptr); 124 125 // pthread_internal_t is freed below with stack, not here. 126 __pthread_internal_remove(thread); 127 128 if (thread->mmap_size != 0) { 129 // We need to free mapped space for detached threads when they exit. 130 // That's not something we can do in C. 131 __hwasan_thread_exit(); 132 _exit_with_stack_teardown(thread->mmap_base, thread->mmap_size); 133 } 134 } 135 136 // No need to free mapped space. Either there was no space mapped, or it is left for 137 // the pthread_join caller to clean up. 138 __hwasan_thread_exit(); 139 __exit(0); 140 } 141
