pthread_create.cpp revision 98624c374646a050556bdc402b55b792fefa7e55
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 <errno.h> 32#include <sys/mman.h> 33 34#include "pthread_internal.h" 35 36#include "private/bionic_ssp.h" 37#include "private/bionic_tls.h" 38#include "private/libc_logging.h" 39#include "private/thread_private.h" 40#include "private/ErrnoRestorer.h" 41#include "private/ScopedPthreadMutexLocker.h" 42 43extern "C" int __pthread_clone(void* (*fn)(void*), void* child_stack, int flags, void* arg); 44 45#ifdef __i386__ 46#define ATTRIBUTES __attribute__((noinline)) __attribute__((fastcall)) 47#else 48#define ATTRIBUTES __attribute__((noinline)) 49#endif 50 51extern "C" void ATTRIBUTES _thread_created_hook(pid_t thread_id); 52 53extern "C" int __set_tls(void* ptr); 54 55static pthread_mutex_t gPthreadStackCreationLock = PTHREAD_MUTEX_INITIALIZER; 56 57static pthread_mutex_t gDebuggerNotificationLock = PTHREAD_MUTEX_INITIALIZER; 58 59void __init_tls(pthread_internal_t* thread) { 60 // Zero-initialize all the slots. 61 for (size_t i = 0; i < BIONIC_TLS_SLOTS; ++i) { 62 thread->tls[i] = NULL; 63 } 64 65 // Slot 0 must point to itself. The x86 Linux kernel reads the TLS from %fs:0. 66 thread->tls[TLS_SLOT_SELF] = thread->tls; 67 thread->tls[TLS_SLOT_THREAD_ID] = thread; 68 // GCC looks in the TLS for the stack guard on x86, so copy it there from our global. 69 thread->tls[TLS_SLOT_STACK_GUARD] = (void*) __stack_chk_guard; 70 71 __set_tls(thread->tls); 72 73 // Create and set an alternate signal stack. 74 // This must happen after __set_tls, in case a system call fails and tries to set errno. 75 stack_t ss; 76 ss.ss_sp = mmap(NULL, SIGSTKSZ, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, 0, 0); 77 if (ss.ss_sp != MAP_FAILED) { 78 ss.ss_size = SIGSTKSZ; 79 ss.ss_flags = 0; 80 sigaltstack(&ss, NULL); 81 thread->alternate_signal_stack = ss.ss_sp; 82 } 83} 84 85__LIBC_ABI_PRIVATE__ 86int _init_thread(pthread_internal_t* thread, bool add_to_thread_list) { 87 int error = 0; 88 89 // Set the scheduling policy/priority of the thread. 90 if (thread->attr.sched_policy != SCHED_NORMAL) { 91 struct sched_param param; 92 param.sched_priority = thread->attr.sched_priority; 93 if (sched_setscheduler(thread->tid, thread->attr.sched_policy, ¶m) == -1) { 94#if __LP64__ 95 // For backwards compatibility reasons, we only report failures on 64-bit devices. 96 error = errno; 97#endif 98 __libc_format_log(ANDROID_LOG_WARN, "libc", 99 "pthread_create sched_setscheduler call failed: %s", strerror(errno)); 100 } 101 } 102 103 pthread_cond_init(&thread->join_cond, NULL); 104 thread->cleanup_stack = NULL; 105 106 if (add_to_thread_list) { 107 _pthread_internal_add(thread); 108 } 109 110 return error; 111} 112 113static void* __create_thread_stack(pthread_internal_t* thread) { 114 ScopedPthreadMutexLocker lock(&gPthreadStackCreationLock); 115 116 // Create a new private anonymous map. 117 int prot = PROT_READ | PROT_WRITE; 118 int flags = MAP_PRIVATE | MAP_ANONYMOUS | MAP_NORESERVE; 119 void* stack = mmap(NULL, thread->attr.stack_size, prot, flags, -1, 0); 120 if (stack == MAP_FAILED) { 121 __libc_format_log(ANDROID_LOG_WARN, 122 "libc", 123 "pthread_create failed: couldn't allocate %zd-byte stack: %s", 124 thread->attr.stack_size, strerror(errno)); 125 return NULL; 126 } 127 128 // Set the guard region at the end of the stack to PROT_NONE. 129 if (mprotect(stack, thread->attr.guard_size, PROT_NONE) == -1) { 130 __libc_format_log(ANDROID_LOG_WARN, "libc", 131 "pthread_create failed: couldn't mprotect PROT_NONE %zd-byte stack guard region: %s", 132 thread->attr.guard_size, strerror(errno)); 133 munmap(stack, thread->attr.stack_size); 134 return NULL; 135 } 136 137 return stack; 138} 139 140int pthread_create(pthread_t* thread_out, pthread_attr_t const* attr, 141 void* (*start_routine)(void*), void* arg) { 142 ErrnoRestorer errno_restorer; 143 144 // Inform the rest of the C library that at least one thread 145 // was created. This will enforce certain functions to acquire/release 146 // locks (e.g. atexit()) to protect shared global structures. 147 // This works because pthread_create() is not called by the C library 148 // initialization routine that sets up the main thread's data structures. 149 __isthreaded = 1; 150 151 pthread_internal_t* thread = reinterpret_cast<pthread_internal_t*>(calloc(sizeof(*thread), 1)); 152 if (thread == NULL) { 153 __libc_format_log(ANDROID_LOG_WARN, "libc", "pthread_create failed: couldn't allocate thread"); 154 return EAGAIN; 155 } 156 thread->allocated_on_heap = true; 157 158 if (attr == NULL) { 159 pthread_attr_init(&thread->attr); 160 } else { 161 thread->attr = *attr; 162 attr = NULL; // Prevent misuse below. 163 } 164 165 // Make sure the stack size and guard size are multiples of PAGE_SIZE. 166 thread->attr.stack_size = (thread->attr.stack_size + (PAGE_SIZE-1)) & ~(PAGE_SIZE-1); 167 thread->attr.guard_size = (thread->attr.guard_size + (PAGE_SIZE-1)) & ~(PAGE_SIZE-1); 168 169 if (thread->attr.stack_base == NULL) { 170 // The caller didn't provide a stack, so allocate one. 171 thread->attr.stack_base = __create_thread_stack(thread); 172 if (thread->attr.stack_base == NULL) { 173 free(thread); 174 return EAGAIN; 175 } 176 } else { 177 // The caller did provide a stack, so remember we're not supposed to free it. 178 thread->attr.flags |= PTHREAD_ATTR_FLAG_USER_STACK; 179 } 180 181 // Make room for the TLS area. 182 // The child stack is the same address, just growing in the opposite direction. 183 // At offsets >= 0, we have the TLS slots. 184 // At offsets < 0, we have the child stack. 185 void** tls = (void**)((uint8_t*)(thread->attr.stack_base) + thread->attr.stack_size - BIONIC_TLS_SLOTS * sizeof(void*)); 186 void* child_stack = tls; 187 188 // Create a mutex for the thread in TLS_SLOT_SELF to wait on once it starts so we can keep 189 // it from doing anything until after we notify the debugger about it 190 // 191 // This also provides the memory barrier we need to ensure that all 192 // memory accesses previously performed by this thread are visible to 193 // the new thread. 194 pthread_mutex_t* start_mutex = (pthread_mutex_t*) &tls[TLS_SLOT_SELF]; 195 pthread_mutex_init(start_mutex, NULL); 196 ScopedPthreadMutexLocker start_locker(start_mutex); 197 198 tls[TLS_SLOT_THREAD_ID] = thread; 199 200 int flags = CLONE_FILES | CLONE_FS | CLONE_VM | CLONE_SIGHAND | CLONE_THREAD | CLONE_SYSVSEM; 201 202 int tid = __pthread_clone(start_routine, child_stack, flags, arg); 203 if (tid < 0) { 204 int clone_errno = errno; 205 if ((thread->attr.flags & PTHREAD_ATTR_FLAG_USER_STACK) == 0) { 206 munmap(thread->attr.stack_base, thread->attr.stack_size); 207 } 208 free(thread); 209 __libc_format_log(ANDROID_LOG_WARN, "libc", "pthread_create failed: clone failed: %s", strerror(errno)); 210 return clone_errno; 211 } 212 213 thread->tid = tid; 214 215 int init_errno = _init_thread(thread, true); 216 if (init_errno != 0) { 217 // Mark the thread detached and let its __thread_entry run to 218 // completion. (It'll just exit immediately, cleaning up its resources.) 219 thread->internal_flags |= PTHREAD_INTERNAL_FLAG_THREAD_INIT_FAILED; 220 thread->attr.flags |= PTHREAD_ATTR_FLAG_DETACHED; 221 return init_errno; 222 } 223 224 // Notify any debuggers about the new thread. 225 { 226 ScopedPthreadMutexLocker debugger_locker(&gDebuggerNotificationLock); 227 _thread_created_hook(thread->tid); 228 } 229 230 // Publish the pthread_t and let the thread run. 231 *thread_out = (pthread_t) thread; 232 233 return 0; 234} 235