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
37extern "C" __noreturn void _exit_with_stack_teardown(void*, size_t);
38extern "C" __noreturn void __exit(int);
39extern "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
45void __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
53void __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
61void 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