pthread_create.cpp revision ba8dfc2669d658dc340eb8f9c9b40ca074f05047
14b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes/* 24b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes * Copyright (C) 2008 The Android Open Source Project 34b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes * All rights reserved. 44b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes * 54b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes * Redistribution and use in source and binary forms, with or without 64b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes * modification, are permitted provided that the following conditions 74b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes * are met: 84b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes * * Redistributions of source code must retain the above copyright 94b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes * notice, this list of conditions and the following disclaimer. 104b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes * * Redistributions in binary form must reproduce the above copyright 114b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes * notice, this list of conditions and the following disclaimer in 124b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes * the documentation and/or other materials provided with the 134b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes * distribution. 144b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes * 154b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 164b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 174b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 184b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 194b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, 204b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, 214b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS 224b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED 234b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, 244b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT 254b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 264b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes * SUCH DAMAGE. 274b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes */ 284b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes 294b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes#include <pthread.h> 304b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes 314b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes#include <errno.h> 324b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes#include <sys/mman.h> 337086ad6919feb2415c6027163f5c63323bcca27cElliott Hughes#include <unistd.h> 344b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes 354b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes#include "pthread_internal.h" 364b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes 3703eebcb6e8762e668a0d3af6bb303cccb88c5b81Christopher Ferris#include "private/bionic_macros.h" 388cf1b305670123aed7638d984ca39bfd22388440Yabin Cui#include "private/bionic_prctl.h" 394b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes#include "private/bionic_ssp.h" 404b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes#include "private/bionic_tls.h" 418f2a5a0b40fc82126c691d5c30131d908772aab7Elliott Hughes#include "private/libc_logging.h" 424b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes#include "private/ErrnoRestorer.h" 434b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes#include "private/ScopedPthreadMutexLocker.h" 444b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes 450d236aa3f1e6d31b0c729448ae9d3ed1cad23fb4Elliott Hughes// x86 uses segment descriptors rather than a direct pointer to TLS. 460d236aa3f1e6d31b0c729448ae9d3ed1cad23fb4Elliott Hughes#if __i386__ 470d236aa3f1e6d31b0c729448ae9d3ed1cad23fb4Elliott Hughes#include <asm/ldt.h> 480d236aa3f1e6d31b0c729448ae9d3ed1cad23fb4Elliott Hughesextern "C" __LIBC_HIDDEN__ void __init_user_desc(struct user_desc*, int, void*); 490d236aa3f1e6d31b0c729448ae9d3ed1cad23fb4Elliott Hughes#endif 500d236aa3f1e6d31b0c729448ae9d3ed1cad23fb4Elliott Hughes 51f2cea021ab2c6d7d7feeb40cca098aa132605876Elliott Hughesextern "C" int __isthreaded; 52f2cea021ab2c6d7d7feeb40cca098aa132605876Elliott Hughes 5370b24b1cc2a1a4436b1fea3f8b76616fdcb27224Elliott Hughes// This code is used both by each new pthread and the code that initializes the main thread. 54af8aebebb52d73ea38c604525a6a5857618861cfElliott Hughesvoid __init_tls(pthread_internal_t* thread) { 55ba8dfc2669d658dc340eb8f9c9b40ca074f05047Yabin Cui if (thread->mmap_size == 0) { 56ba8dfc2669d658dc340eb8f9c9b40ca074f05047Yabin Cui // If the TLS area was not allocated by mmap(), it may not have been cleared to zero. 57ba8dfc2669d658dc340eb8f9c9b40ca074f05047Yabin Cui // So assume the worst and zero the TLS area. 5840a521744825b6060960c296d5fb3da4c6593d94Elliott Hughes memset(&thread->tls[0], 0, BIONIC_TLS_SLOTS * sizeof(void*)); 594b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes } 604b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes 614b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes // Slot 0 must point to itself. The x86 Linux kernel reads the TLS from %fs:0. 6240eabe24e4e3ae8ebe437f1f4e43cf39cbba2e9eElliott Hughes thread->tls[TLS_SLOT_SELF] = thread->tls; 6340eabe24e4e3ae8ebe437f1f4e43cf39cbba2e9eElliott Hughes thread->tls[TLS_SLOT_THREAD_ID] = thread; 644b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes // GCC looks in the TLS for the stack guard on x86, so copy it there from our global. 6540eabe24e4e3ae8ebe437f1f4e43cf39cbba2e9eElliott Hughes thread->tls[TLS_SLOT_STACK_GUARD] = (void*) __stack_chk_guard; 6670b24b1cc2a1a4436b1fea3f8b76616fdcb27224Elliott Hughes} 674b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes 6870b24b1cc2a1a4436b1fea3f8b76616fdcb27224Elliott Hughesvoid __init_alternate_signal_stack(pthread_internal_t* thread) { 6984114c8dd5b17efecf7988f263ce431208d7be5aElliott Hughes // Create and set an alternate signal stack. 7084114c8dd5b17efecf7988f263ce431208d7be5aElliott Hughes stack_t ss; 7140a521744825b6060960c296d5fb3da4c6593d94Elliott Hughes ss.ss_sp = mmap(NULL, SIGSTKSZ, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0); 7284114c8dd5b17efecf7988f263ce431208d7be5aElliott Hughes if (ss.ss_sp != MAP_FAILED) { 7384114c8dd5b17efecf7988f263ce431208d7be5aElliott Hughes ss.ss_size = SIGSTKSZ; 7484114c8dd5b17efecf7988f263ce431208d7be5aElliott Hughes ss.ss_flags = 0; 7584114c8dd5b17efecf7988f263ce431208d7be5aElliott Hughes sigaltstack(&ss, NULL); 7684114c8dd5b17efecf7988f263ce431208d7be5aElliott Hughes thread->alternate_signal_stack = ss.ss_sp; 778cf1b305670123aed7638d984ca39bfd22388440Yabin Cui 788cf1b305670123aed7638d984ca39bfd22388440Yabin Cui // We can only use const static allocated string for mapped region name, as Android kernel 798cf1b305670123aed7638d984ca39bfd22388440Yabin Cui // uses the string pointer directly when dumping /proc/pid/maps. 808cf1b305670123aed7638d984ca39bfd22388440Yabin Cui prctl(PR_SET_VMA, PR_SET_VMA_ANON_NAME, ss.ss_sp, ss.ss_size, "thread signal stack"); 8184114c8dd5b17efecf7988f263ce431208d7be5aElliott Hughes } 824b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes} 834b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes 84cef3faec0ea40fdfe58e425fd0be64f00de6a26dElliott Hughesint __init_thread(pthread_internal_t* thread, bool add_to_thread_list) { 854b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes int error = 0; 864b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes 874b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes // Set the scheduling policy/priority of the thread. 884b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes if (thread->attr.sched_policy != SCHED_NORMAL) { 89c3f114037dbf028896310609fd28cf2b3da99c4dElliott Hughes sched_param param; 904b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes param.sched_priority = thread->attr.sched_priority; 9140eabe24e4e3ae8ebe437f1f4e43cf39cbba2e9eElliott Hughes if (sched_setscheduler(thread->tid, thread->attr.sched_policy, ¶m) == -1) { 9298624c374646a050556bdc402b55b792fefa7e55Elliott Hughes#if __LP64__ 9398624c374646a050556bdc402b55b792fefa7e55Elliott Hughes // For backwards compatibility reasons, we only report failures on 64-bit devices. 9498624c374646a050556bdc402b55b792fefa7e55Elliott Hughes error = errno; 9598624c374646a050556bdc402b55b792fefa7e55Elliott Hughes#endif 96b95cf0d23a1db3b7c37bd98b0c86196796c9b029Elliott Hughes __libc_format_log(ANDROID_LOG_WARN, "libc", 97b95cf0d23a1db3b7c37bd98b0c86196796c9b029Elliott Hughes "pthread_create sched_setscheduler call failed: %s", strerror(errno)); 984b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes } 994b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes } 1004b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes 1014b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes thread->cleanup_stack = NULL; 1024b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes 1034b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes if (add_to_thread_list) { 1044b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes _pthread_internal_add(thread); 1054b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes } 1064b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes 1074b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes return error; 1084b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes} 1094b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes 110ba8dfc2669d658dc340eb8f9c9b40ca074f05047Yabin Cuistatic void* __create_thread_mapped_space(size_t mmap_size, size_t stack_guard_size) { 1114b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes // Create a new private anonymous map. 1124b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes int prot = PROT_READ | PROT_WRITE; 1134b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes int flags = MAP_PRIVATE | MAP_ANONYMOUS | MAP_NORESERVE; 114ba8dfc2669d658dc340eb8f9c9b40ca074f05047Yabin Cui void* space = mmap(NULL, mmap_size, prot, flags, -1, 0); 115ba8dfc2669d658dc340eb8f9c9b40ca074f05047Yabin Cui if (space == MAP_FAILED) { 116b95cf0d23a1db3b7c37bd98b0c86196796c9b029Elliott Hughes __libc_format_log(ANDROID_LOG_WARN, 117b95cf0d23a1db3b7c37bd98b0c86196796c9b029Elliott Hughes "libc", 118ba8dfc2669d658dc340eb8f9c9b40ca074f05047Yabin Cui "pthread_create failed: couldn't allocate %zu-bytes mapped space: %s", 119ba8dfc2669d658dc340eb8f9c9b40ca074f05047Yabin Cui mmap_size, strerror(errno)); 1204b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes return NULL; 1214b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes } 1224b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes 123ba8dfc2669d658dc340eb8f9c9b40ca074f05047Yabin Cui // Stack is at the lower end of mapped space, stack guard region is at the lower end of stack. 124ba8dfc2669d658dc340eb8f9c9b40ca074f05047Yabin Cui // Set the stack guard region to PROT_NONE, so we can detect thread stack overflow. 125ba8dfc2669d658dc340eb8f9c9b40ca074f05047Yabin Cui if (mprotect(space, stack_guard_size, PROT_NONE) == -1) { 126b95cf0d23a1db3b7c37bd98b0c86196796c9b029Elliott Hughes __libc_format_log(ANDROID_LOG_WARN, "libc", 127ba8dfc2669d658dc340eb8f9c9b40ca074f05047Yabin Cui "pthread_create failed: couldn't mprotect PROT_NONE %zu-byte stack guard region: %s", 128ba8dfc2669d658dc340eb8f9c9b40ca074f05047Yabin Cui stack_guard_size, strerror(errno)); 129ba8dfc2669d658dc340eb8f9c9b40ca074f05047Yabin Cui munmap(space, mmap_size); 1304b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes return NULL; 1314b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes } 1324b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes 133ba8dfc2669d658dc340eb8f9c9b40ca074f05047Yabin Cui return space; 1344b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes} 1354b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes 1368cf1b305670123aed7638d984ca39bfd22388440Yabin Cuistatic int __allocate_thread(pthread_attr_t* attr, pthread_internal_t** threadp, void** child_stack) { 137ba8dfc2669d658dc340eb8f9c9b40ca074f05047Yabin Cui size_t mmap_size; 1386a7aaf46759db32c6ed0eb953a4a230dc96af0d9Yabin Cui uint8_t* stack_top; 1396a7aaf46759db32c6ed0eb953a4a230dc96af0d9Yabin Cui 1408cf1b305670123aed7638d984ca39bfd22388440Yabin Cui if (attr->stack_base == NULL) { 1418cf1b305670123aed7638d984ca39bfd22388440Yabin Cui // The caller didn't provide a stack, so allocate one. 1428cf1b305670123aed7638d984ca39bfd22388440Yabin Cui // Make sure the stack size and guard size are multiples of PAGE_SIZE. 143ba8dfc2669d658dc340eb8f9c9b40ca074f05047Yabin Cui mmap_size = BIONIC_ALIGN(attr->stack_size + sizeof(pthread_internal_t), PAGE_SIZE); 1448cf1b305670123aed7638d984ca39bfd22388440Yabin Cui attr->guard_size = BIONIC_ALIGN(attr->guard_size, PAGE_SIZE); 145ba8dfc2669d658dc340eb8f9c9b40ca074f05047Yabin Cui attr->stack_base = __create_thread_mapped_space(mmap_size, attr->guard_size); 1468cf1b305670123aed7638d984ca39bfd22388440Yabin Cui if (attr->stack_base == NULL) { 1478cf1b305670123aed7638d984ca39bfd22388440Yabin Cui return EAGAIN; 1488cf1b305670123aed7638d984ca39bfd22388440Yabin Cui } 149ba8dfc2669d658dc340eb8f9c9b40ca074f05047Yabin Cui stack_top = reinterpret_cast<uint8_t*>(attr->stack_base) + mmap_size; 1508cf1b305670123aed7638d984ca39bfd22388440Yabin Cui } else { 151ba8dfc2669d658dc340eb8f9c9b40ca074f05047Yabin Cui // Remember the mmap size is zero and we don't need to free it. 152ba8dfc2669d658dc340eb8f9c9b40ca074f05047Yabin Cui mmap_size = 0; 1536a7aaf46759db32c6ed0eb953a4a230dc96af0d9Yabin Cui stack_top = reinterpret_cast<uint8_t*>(attr->stack_base) + attr->stack_size; 1548cf1b305670123aed7638d984ca39bfd22388440Yabin Cui } 1558cf1b305670123aed7638d984ca39bfd22388440Yabin Cui 156ba8dfc2669d658dc340eb8f9c9b40ca074f05047Yabin Cui // Mapped space(or user allocated stack) is used for: 157ba8dfc2669d658dc340eb8f9c9b40ca074f05047Yabin Cui // thread_internal_t (including tls array) 158ba8dfc2669d658dc340eb8f9c9b40ca074f05047Yabin Cui // thread stack (including guard page) 1598cf1b305670123aed7638d984ca39bfd22388440Yabin Cui stack_top -= sizeof(pthread_internal_t); 1608cf1b305670123aed7638d984ca39bfd22388440Yabin Cui pthread_internal_t* thread = reinterpret_cast<pthread_internal_t*>(stack_top); 1618cf1b305670123aed7638d984ca39bfd22388440Yabin Cui 1628cf1b305670123aed7638d984ca39bfd22388440Yabin Cui // No need to check stack_top alignment. The size of pthread_internal_t is 16-bytes aligned, 1638cf1b305670123aed7638d984ca39bfd22388440Yabin Cui // and user allocated stack is guaranteed by pthread_attr_setstack. 1648cf1b305670123aed7638d984ca39bfd22388440Yabin Cui 165ba8dfc2669d658dc340eb8f9c9b40ca074f05047Yabin Cui thread->mmap_size = mmap_size; 1668cf1b305670123aed7638d984ca39bfd22388440Yabin Cui thread->attr = *attr; 1678cf1b305670123aed7638d984ca39bfd22388440Yabin Cui __init_tls(thread); 1688cf1b305670123aed7638d984ca39bfd22388440Yabin Cui 1698cf1b305670123aed7638d984ca39bfd22388440Yabin Cui *threadp = thread; 1708cf1b305670123aed7638d984ca39bfd22388440Yabin Cui *child_stack = stack_top; 1718cf1b305670123aed7638d984ca39bfd22388440Yabin Cui return 0; 1728cf1b305670123aed7638d984ca39bfd22388440Yabin Cui} 1738cf1b305670123aed7638d984ca39bfd22388440Yabin Cui 174e48b68570d872ef7ece1d873c0ea298ea76393f3Elliott Hughesstatic int __pthread_start(void* arg) { 175e48b68570d872ef7ece1d873c0ea298ea76393f3Elliott Hughes pthread_internal_t* thread = reinterpret_cast<pthread_internal_t*>(arg); 176e48b68570d872ef7ece1d873c0ea298ea76393f3Elliott Hughes 177e48b68570d872ef7ece1d873c0ea298ea76393f3Elliott Hughes // Wait for our creating thread to release us. This lets it have time to 178e48b68570d872ef7ece1d873c0ea298ea76393f3Elliott Hughes // notify gdb about this thread before we start doing anything. 179e48b68570d872ef7ece1d873c0ea298ea76393f3Elliott Hughes // This also provides the memory barrier needed to ensure that all memory 180e48b68570d872ef7ece1d873c0ea298ea76393f3Elliott Hughes // accesses previously made by the creating thread are visible to us. 181b30aff405a220495941f1673b0a5e66c4fa8b84cElliott Hughes pthread_mutex_lock(&thread->startup_handshake_mutex); 182b30aff405a220495941f1673b0a5e66c4fa8b84cElliott Hughes pthread_mutex_destroy(&thread->startup_handshake_mutex); 183e48b68570d872ef7ece1d873c0ea298ea76393f3Elliott Hughes 184e48b68570d872ef7ece1d873c0ea298ea76393f3Elliott Hughes __init_alternate_signal_stack(thread); 185e48b68570d872ef7ece1d873c0ea298ea76393f3Elliott Hughes 186e48b68570d872ef7ece1d873c0ea298ea76393f3Elliott Hughes void* result = thread->start_routine(thread->start_routine_arg); 187e48b68570d872ef7ece1d873c0ea298ea76393f3Elliott Hughes pthread_exit(result); 188e48b68570d872ef7ece1d873c0ea298ea76393f3Elliott Hughes 189e48b68570d872ef7ece1d873c0ea298ea76393f3Elliott Hughes return 0; 190e48b68570d872ef7ece1d873c0ea298ea76393f3Elliott Hughes} 191e48b68570d872ef7ece1d873c0ea298ea76393f3Elliott Hughes 192cef3faec0ea40fdfe58e425fd0be64f00de6a26dElliott Hughes// A dummy start routine for pthread_create failures where we've created a thread but aren't 193cef3faec0ea40fdfe58e425fd0be64f00de6a26dElliott Hughes// going to run user code on it. We swap out the user's start routine for this and take advantage 194cef3faec0ea40fdfe58e425fd0be64f00de6a26dElliott Hughes// of the regular thread teardown to free up resources. 195cef3faec0ea40fdfe58e425fd0be64f00de6a26dElliott Hughesstatic void* __do_nothing(void*) { 196cef3faec0ea40fdfe58e425fd0be64f00de6a26dElliott Hughes return NULL; 197cef3faec0ea40fdfe58e425fd0be64f00de6a26dElliott Hughes} 198cef3faec0ea40fdfe58e425fd0be64f00de6a26dElliott Hughes 1994b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughesint pthread_create(pthread_t* thread_out, pthread_attr_t const* attr, 2004b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes void* (*start_routine)(void*), void* arg) { 2014b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes ErrnoRestorer errno_restorer; 2024b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes 203f2cea021ab2c6d7d7feeb40cca098aa132605876Elliott Hughes // Inform the rest of the C library that at least one thread was created. 2044b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes __isthreaded = 1; 2054b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes 2068cf1b305670123aed7638d984ca39bfd22388440Yabin Cui pthread_attr_t thread_attr; 2074b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes if (attr == NULL) { 2088cf1b305670123aed7638d984ca39bfd22388440Yabin Cui pthread_attr_init(&thread_attr); 2094b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes } else { 2108cf1b305670123aed7638d984ca39bfd22388440Yabin Cui thread_attr = *attr; 2114b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes attr = NULL; // Prevent misuse below. 2124b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes } 2134b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes 2148cf1b305670123aed7638d984ca39bfd22388440Yabin Cui pthread_internal_t* thread = NULL; 2158cf1b305670123aed7638d984ca39bfd22388440Yabin Cui void* child_stack = NULL; 2168cf1b305670123aed7638d984ca39bfd22388440Yabin Cui int result = __allocate_thread(&thread_attr, &thread, &child_stack); 2178cf1b305670123aed7638d984ca39bfd22388440Yabin Cui if (result != 0) { 2188cf1b305670123aed7638d984ca39bfd22388440Yabin Cui return result; 2194b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes } 2204b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes 22170b24b1cc2a1a4436b1fea3f8b76616fdcb27224Elliott Hughes // Create a mutex for the thread in TLS to wait on once it starts so we can keep 2224b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes // it from doing anything until after we notify the debugger about it 2234b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes // 2244b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes // This also provides the memory barrier we need to ensure that all 2254b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes // memory accesses previously performed by this thread are visible to 2264b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes // the new thread. 227b30aff405a220495941f1673b0a5e66c4fa8b84cElliott Hughes pthread_mutex_init(&thread->startup_handshake_mutex, NULL); 228b30aff405a220495941f1673b0a5e66c4fa8b84cElliott Hughes pthread_mutex_lock(&thread->startup_handshake_mutex); 2294b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes 23070b24b1cc2a1a4436b1fea3f8b76616fdcb27224Elliott Hughes thread->start_routine = start_routine; 23170b24b1cc2a1a4436b1fea3f8b76616fdcb27224Elliott Hughes thread->start_routine_arg = arg; 2324b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes 2337086ad6919feb2415c6027163f5c63323bcca27cElliott Hughes thread->set_cached_pid(getpid()); 2347086ad6919feb2415c6027163f5c63323bcca27cElliott Hughes 235877ec6d90418ff1d6597147d355a2229fdffae7eElliott Hughes int flags = CLONE_VM | CLONE_FS | CLONE_FILES | CLONE_SIGHAND | CLONE_THREAD | CLONE_SYSVSEM | 236877ec6d90418ff1d6597147d355a2229fdffae7eElliott Hughes CLONE_SETTLS | CLONE_PARENT_SETTID | CLONE_CHILD_CLEARTID; 2378cf1b305670123aed7638d984ca39bfd22388440Yabin Cui void* tls = reinterpret_cast<void*>(thread->tls); 23880906141f79be8be63fc915bfab467029b442ca1Elliott Hughes#if defined(__i386__) 23980906141f79be8be63fc915bfab467029b442ca1Elliott Hughes // On x86 (but not x86-64), CLONE_SETTLS takes a pointer to a struct user_desc rather than 2400d236aa3f1e6d31b0c729448ae9d3ed1cad23fb4Elliott Hughes // a pointer to the TLS itself. 2410d236aa3f1e6d31b0c729448ae9d3ed1cad23fb4Elliott Hughes user_desc tls_descriptor; 2420d236aa3f1e6d31b0c729448ae9d3ed1cad23fb4Elliott Hughes __init_user_desc(&tls_descriptor, false, tls); 2430d236aa3f1e6d31b0c729448ae9d3ed1cad23fb4Elliott Hughes tls = &tls_descriptor; 24480906141f79be8be63fc915bfab467029b442ca1Elliott Hughes#endif 2450d236aa3f1e6d31b0c729448ae9d3ed1cad23fb4Elliott Hughes int rc = clone(__pthread_start, child_stack, flags, thread, &(thread->tid), tls, &(thread->tid)); 246877ec6d90418ff1d6597147d355a2229fdffae7eElliott Hughes if (rc == -1) { 2474b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes int clone_errno = errno; 248877ec6d90418ff1d6597147d355a2229fdffae7eElliott Hughes // We don't have to unlock the mutex at all because clone(2) failed so there's no child waiting to 249877ec6d90418ff1d6597147d355a2229fdffae7eElliott Hughes // be unblocked, but we're about to unmap the memory the mutex is stored in, so this serves as a 250877ec6d90418ff1d6597147d355a2229fdffae7eElliott Hughes // reminder that you can't rewrite this function to use a ScopedPthreadMutexLocker. 251b30aff405a220495941f1673b0a5e66c4fa8b84cElliott Hughes pthread_mutex_unlock(&thread->startup_handshake_mutex); 252ba8dfc2669d658dc340eb8f9c9b40ca074f05047Yabin Cui if (thread->mmap_size != 0) { 253ba8dfc2669d658dc340eb8f9c9b40ca074f05047Yabin Cui munmap(thread->attr.stack_base, thread->mmap_size); 2544b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes } 255cfa089df23ff50fcd5ed3854c54991d30be5fc7eElliott Hughes __libc_format_log(ANDROID_LOG_WARN, "libc", "pthread_create failed: clone failed: %s", strerror(errno)); 2564b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes return clone_errno; 2574b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes } 2584b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes 259cef3faec0ea40fdfe58e425fd0be64f00de6a26dElliott Hughes int init_errno = __init_thread(thread, true); 2604b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes if (init_errno != 0) { 261cef3faec0ea40fdfe58e425fd0be64f00de6a26dElliott Hughes // Mark the thread detached and replace its start_routine with a no-op. 262cef3faec0ea40fdfe58e425fd0be64f00de6a26dElliott Hughes // Letting the thread run is the easiest way to clean up its resources. 2634b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes thread->attr.flags |= PTHREAD_ATTR_FLAG_DETACHED; 264cef3faec0ea40fdfe58e425fd0be64f00de6a26dElliott Hughes thread->start_routine = __do_nothing; 265b30aff405a220495941f1673b0a5e66c4fa8b84cElliott Hughes pthread_mutex_unlock(&thread->startup_handshake_mutex); 2664b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes return init_errno; 2674b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes } 2684b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes 269877ec6d90418ff1d6597147d355a2229fdffae7eElliott Hughes // Publish the pthread_t and unlock the mutex to let the new thread start running. 270877ec6d90418ff1d6597147d355a2229fdffae7eElliott Hughes *thread_out = reinterpret_cast<pthread_t>(thread); 271b30aff405a220495941f1673b0a5e66c4fa8b84cElliott Hughes pthread_mutex_unlock(&thread->startup_handshake_mutex); 2724b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes 2734b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes return 0; 2744b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes} 275