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 <sys/mman.h> 34 35 #include "pthread_internal.h" 36 37 extern "C" __noreturn void _exit_with_stack_teardown(void*, size_t); 38 extern "C" __noreturn void __exit(int); 39 extern "C" int __set_tid_address(int*); 40 41 /* CAVEAT: our implementation of pthread_cleanup_push/pop doesn't support C++ exceptions 42 * and thread cancelation 43 */ 44 45 void __pthread_cleanup_push(__pthread_cleanup_t* c, __pthread_cleanup_func_t routine, void* arg) { 46 pthread_internal_t* thread = __get_thread(); 47 c->__cleanup_routine = routine; 48 c->__cleanup_arg = arg; 49 c->__cleanup_prev = thread->cleanup_stack; 50 thread->cleanup_stack = c; 51 } 52 53 void __pthread_cleanup_pop(__pthread_cleanup_t* c, int execute) { 54 pthread_internal_t* thread = __get_thread(); 55 thread->cleanup_stack = c->__cleanup_prev; 56 if (execute) { 57 c->__cleanup_routine(c->__cleanup_arg); 58 } 59 } 60 61 void pthread_exit(void* return_value) { 62 pthread_internal_t* thread = __get_thread(); 63 thread->return_value = return_value; 64 65 // Call the cleanup handlers first. 66 while (thread->cleanup_stack) { 67 __pthread_cleanup_t* c = thread->cleanup_stack; 68 thread->cleanup_stack = c->__cleanup_prev; 69 c->__cleanup_routine(c->__cleanup_arg); 70 } 71 72 // Call the TLS destructors. It is important to do that before removing this 73 // thread from the global list. This will ensure that if someone else deletes 74 // a TLS key, the corresponding value will be set to NULL in this thread's TLS 75 // space (see pthread_key_delete). 76 pthread_key_clean_all(); 77 78 if (thread->alternate_signal_stack != NULL) { 79 // Tell the kernel to stop using the alternate signal stack. 80 stack_t ss; 81 ss.ss_sp = NULL; 82 ss.ss_flags = SS_DISABLE; 83 sigaltstack(&ss, NULL); 84 85 // Free it. 86 munmap(thread->alternate_signal_stack, SIGSTKSZ); 87 thread->alternate_signal_stack = NULL; 88 } 89 90 // Keep track of what we need to know about the stack before we lose the pthread_internal_t. 91 void* stack_base = thread->attr.stack_base; 92 size_t stack_size = thread->attr.stack_size; 93 bool user_allocated_stack = thread->user_allocated_stack(); 94 95 pthread_mutex_lock(&g_thread_list_lock); 96 if ((thread->attr.flags & PTHREAD_ATTR_FLAG_DETACHED) != 0) { 97 // The thread is detached, so we can free the pthread_internal_t. 98 // First make sure that the kernel does not try to clear the tid field 99 // because we'll have freed the memory before the thread actually exits. 100 __set_tid_address(NULL); 101 _pthread_internal_remove_locked(thread); 102 } else { 103 // Make sure that the pthread_internal_t doesn't have stale pointers to a stack that 104 // will be unmapped after the exit call below. 105 if (!user_allocated_stack) { 106 thread->attr.stack_base = NULL; 107 thread->attr.stack_size = 0; 108 thread->tls = NULL; 109 } 110 // pthread_join is responsible for destroying the pthread_internal_t for non-detached threads. 111 // The kernel will futex_wake on the pthread_internal_t::tid field to wake pthread_join. 112 } 113 pthread_mutex_unlock(&g_thread_list_lock); 114 115 // Perform a second key cleanup. When using jemalloc, a call to free from 116 // _pthread_internal_remove_locked causes the memory associated with a key 117 // to be reallocated. 118 // TODO: When b/16847284 is fixed this call can be removed. 119 pthread_key_clean_all(); 120 121 if (user_allocated_stack) { 122 // Cleaning up this thread's stack is the creator's responsibility, not ours. 123 __exit(0); 124 } else { 125 // We need to munmap the stack we're running on before calling exit. 126 // That's not something we can do in C. 127 128 // We don't want to take a signal after we've unmapped the stack. 129 // That's one last thing we can handle in C. 130 sigset_t mask; 131 sigfillset(&mask); 132 sigprocmask(SIG_SETMASK, &mask, NULL); 133 134 _exit_with_stack_teardown(stack_base, stack_size); 135 } 136 } 137
