pthread_create.cpp revision a2db50d5d7fa67b297eddd1c0549f08ea4b6a950
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> 3205fc1d7050d5451aea08dc5f504d2670287b2d43Elliott Hughes#include <string.h> 334b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes#include <sys/mman.h> 347086ad6919feb2415c6027163f5c63323bcca27cElliott Hughes#include <unistd.h> 354b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes 364b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes#include "pthread_internal.h" 374b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes 3803eebcb6e8762e668a0d3af6bb303cccb88c5b81Christopher Ferris#include "private/bionic_macros.h" 398cf1b305670123aed7638d984ca39bfd22388440Yabin Cui#include "private/bionic_prctl.h" 404b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes#include "private/bionic_ssp.h" 414b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes#include "private/bionic_tls.h" 428f2a5a0b40fc82126c691d5c30131d908772aab7Elliott Hughes#include "private/libc_logging.h" 434b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes#include "private/ErrnoRestorer.h" 444b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes#include "private/ScopedPthreadMutexLocker.h" 454b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes 460d236aa3f1e6d31b0c729448ae9d3ed1cad23fb4Elliott Hughes// x86 uses segment descriptors rather than a direct pointer to TLS. 470d236aa3f1e6d31b0c729448ae9d3ed1cad23fb4Elliott Hughes#if __i386__ 480d236aa3f1e6d31b0c729448ae9d3ed1cad23fb4Elliott Hughes#include <asm/ldt.h> 490d236aa3f1e6d31b0c729448ae9d3ed1cad23fb4Elliott Hughesextern "C" __LIBC_HIDDEN__ void __init_user_desc(struct user_desc*, int, void*); 500d236aa3f1e6d31b0c729448ae9d3ed1cad23fb4Elliott Hughes#endif 510d236aa3f1e6d31b0c729448ae9d3ed1cad23fb4Elliott Hughes 52f2cea021ab2c6d7d7feeb40cca098aa132605876Elliott Hughesextern "C" int __isthreaded; 53f2cea021ab2c6d7d7feeb40cca098aa132605876Elliott Hughes 5470b24b1cc2a1a4436b1fea3f8b76616fdcb27224Elliott Hughes// This code is used both by each new pthread and the code that initializes the main thread. 55af8aebebb52d73ea38c604525a6a5857618861cfElliott Hughesvoid __init_tls(pthread_internal_t* thread) { 56ba8dfc2669d658dc340eb8f9c9b40ca074f05047Yabin Cui if (thread->mmap_size == 0) { 57ba8dfc2669d658dc340eb8f9c9b40ca074f05047Yabin Cui // If the TLS area was not allocated by mmap(), it may not have been cleared to zero. 58ba8dfc2669d658dc340eb8f9c9b40ca074f05047Yabin Cui // So assume the worst and zero the TLS area. 595e2bd719d7dd19afe55f8d4f24366c0230e0e6c7Yabin Cui memset(thread->tls, 0, sizeof(thread->tls)); 605e2bd719d7dd19afe55f8d4f24366c0230e0e6c7Yabin Cui memset(thread->key_data, 0, sizeof(thread->key_data)); 614b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes } 624b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes 634b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes // Slot 0 must point to itself. The x86 Linux kernel reads the TLS from %fs:0. 6440eabe24e4e3ae8ebe437f1f4e43cf39cbba2e9eElliott Hughes thread->tls[TLS_SLOT_SELF] = thread->tls; 6540eabe24e4e3ae8ebe437f1f4e43cf39cbba2e9eElliott Hughes thread->tls[TLS_SLOT_THREAD_ID] = thread; 664b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes // GCC looks in the TLS for the stack guard on x86, so copy it there from our global. 678b5df3920f2843c9cdf04160517c1e8b77c992f5Elliott Hughes thread->tls[TLS_SLOT_STACK_GUARD] = reinterpret_cast<void*>(__stack_chk_guard); 6870b24b1cc2a1a4436b1fea3f8b76616fdcb27224Elliott Hughes} 694b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes 7070b24b1cc2a1a4436b1fea3f8b76616fdcb27224Elliott Hughesvoid __init_alternate_signal_stack(pthread_internal_t* thread) { 7184114c8dd5b17efecf7988f263ce431208d7be5aElliott Hughes // Create and set an alternate signal stack. 7284114c8dd5b17efecf7988f263ce431208d7be5aElliott Hughes stack_t ss; 7340a521744825b6060960c296d5fb3da4c6593d94Elliott Hughes ss.ss_sp = mmap(NULL, SIGSTKSZ, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0); 7484114c8dd5b17efecf7988f263ce431208d7be5aElliott Hughes if (ss.ss_sp != MAP_FAILED) { 7584114c8dd5b17efecf7988f263ce431208d7be5aElliott Hughes ss.ss_size = SIGSTKSZ; 7684114c8dd5b17efecf7988f263ce431208d7be5aElliott Hughes ss.ss_flags = 0; 7784114c8dd5b17efecf7988f263ce431208d7be5aElliott Hughes sigaltstack(&ss, NULL); 7884114c8dd5b17efecf7988f263ce431208d7be5aElliott Hughes thread->alternate_signal_stack = ss.ss_sp; 798cf1b305670123aed7638d984ca39bfd22388440Yabin Cui 808cf1b305670123aed7638d984ca39bfd22388440Yabin Cui // We can only use const static allocated string for mapped region name, as Android kernel 818cf1b305670123aed7638d984ca39bfd22388440Yabin Cui // uses the string pointer directly when dumping /proc/pid/maps. 828cf1b305670123aed7638d984ca39bfd22388440Yabin Cui prctl(PR_SET_VMA, PR_SET_VMA_ANON_NAME, ss.ss_sp, ss.ss_size, "thread signal stack"); 8384114c8dd5b17efecf7988f263ce431208d7be5aElliott Hughes } 844b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes} 854b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes 86cef3faec0ea40fdfe58e425fd0be64f00de6a26dElliott Hughesint __init_thread(pthread_internal_t* thread, bool add_to_thread_list) { 874b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes int error = 0; 884b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes 8958cf31b50699ed9f523de38c8e943f3bbd1ced9eYabin Cui if (__predict_true((thread->attr.flags & PTHREAD_ATTR_FLAG_DETACHED) == 0)) { 9058cf31b50699ed9f523de38c8e943f3bbd1ced9eYabin Cui atomic_init(&thread->join_state, THREAD_NOT_JOINED); 9158cf31b50699ed9f523de38c8e943f3bbd1ced9eYabin Cui } else { 9258cf31b50699ed9f523de38c8e943f3bbd1ced9eYabin Cui atomic_init(&thread->join_state, THREAD_DETACHED); 9358cf31b50699ed9f523de38c8e943f3bbd1ced9eYabin Cui } 9458cf31b50699ed9f523de38c8e943f3bbd1ced9eYabin Cui 954b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes // Set the scheduling policy/priority of the thread. 964b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes if (thread->attr.sched_policy != SCHED_NORMAL) { 97c3f114037dbf028896310609fd28cf2b3da99c4dElliott Hughes sched_param param; 984b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes param.sched_priority = thread->attr.sched_priority; 9940eabe24e4e3ae8ebe437f1f4e43cf39cbba2e9eElliott Hughes if (sched_setscheduler(thread->tid, thread->attr.sched_policy, ¶m) == -1) { 10098624c374646a050556bdc402b55b792fefa7e55Elliott Hughes#if __LP64__ 10198624c374646a050556bdc402b55b792fefa7e55Elliott Hughes // For backwards compatibility reasons, we only report failures on 64-bit devices. 10298624c374646a050556bdc402b55b792fefa7e55Elliott Hughes error = errno; 10398624c374646a050556bdc402b55b792fefa7e55Elliott Hughes#endif 104b95cf0d23a1db3b7c37bd98b0c86196796c9b029Elliott Hughes __libc_format_log(ANDROID_LOG_WARN, "libc", 105b95cf0d23a1db3b7c37bd98b0c86196796c9b029Elliott Hughes "pthread_create sched_setscheduler call failed: %s", strerror(errno)); 1064b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes } 1074b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes } 1084b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes 1094b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes thread->cleanup_stack = NULL; 1104b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes 1114b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes if (add_to_thread_list) { 1124b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes _pthread_internal_add(thread); 1134b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes } 1144b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes 1154b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes return error; 1164b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes} 1174b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes 118ba8dfc2669d658dc340eb8f9c9b40ca074f05047Yabin Cuistatic void* __create_thread_mapped_space(size_t mmap_size, size_t stack_guard_size) { 1194b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes // Create a new private anonymous map. 1204b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes int prot = PROT_READ | PROT_WRITE; 1214b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes int flags = MAP_PRIVATE | MAP_ANONYMOUS | MAP_NORESERVE; 122ba8dfc2669d658dc340eb8f9c9b40ca074f05047Yabin Cui void* space = mmap(NULL, mmap_size, prot, flags, -1, 0); 123ba8dfc2669d658dc340eb8f9c9b40ca074f05047Yabin Cui if (space == MAP_FAILED) { 124b95cf0d23a1db3b7c37bd98b0c86196796c9b029Elliott Hughes __libc_format_log(ANDROID_LOG_WARN, 125b95cf0d23a1db3b7c37bd98b0c86196796c9b029Elliott Hughes "libc", 126ba8dfc2669d658dc340eb8f9c9b40ca074f05047Yabin Cui "pthread_create failed: couldn't allocate %zu-bytes mapped space: %s", 127ba8dfc2669d658dc340eb8f9c9b40ca074f05047Yabin Cui mmap_size, strerror(errno)); 1284b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes return NULL; 1294b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes } 1304b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes 131ba8dfc2669d658dc340eb8f9c9b40ca074f05047Yabin Cui // Stack is at the lower end of mapped space, stack guard region is at the lower end of stack. 132ba8dfc2669d658dc340eb8f9c9b40ca074f05047Yabin Cui // Set the stack guard region to PROT_NONE, so we can detect thread stack overflow. 133ba8dfc2669d658dc340eb8f9c9b40ca074f05047Yabin Cui if (mprotect(space, stack_guard_size, PROT_NONE) == -1) { 134b95cf0d23a1db3b7c37bd98b0c86196796c9b029Elliott Hughes __libc_format_log(ANDROID_LOG_WARN, "libc", 135ba8dfc2669d658dc340eb8f9c9b40ca074f05047Yabin Cui "pthread_create failed: couldn't mprotect PROT_NONE %zu-byte stack guard region: %s", 136ba8dfc2669d658dc340eb8f9c9b40ca074f05047Yabin Cui stack_guard_size, strerror(errno)); 137ba8dfc2669d658dc340eb8f9c9b40ca074f05047Yabin Cui munmap(space, mmap_size); 1384b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes return NULL; 1394b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes } 1404b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes 141ba8dfc2669d658dc340eb8f9c9b40ca074f05047Yabin Cui return space; 1424b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes} 1434b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes 1448cf1b305670123aed7638d984ca39bfd22388440Yabin Cuistatic int __allocate_thread(pthread_attr_t* attr, pthread_internal_t** threadp, void** child_stack) { 145ba8dfc2669d658dc340eb8f9c9b40ca074f05047Yabin Cui size_t mmap_size; 1466a7aaf46759db32c6ed0eb953a4a230dc96af0d9Yabin Cui uint8_t* stack_top; 1476a7aaf46759db32c6ed0eb953a4a230dc96af0d9Yabin Cui 1488cf1b305670123aed7638d984ca39bfd22388440Yabin Cui if (attr->stack_base == NULL) { 1498cf1b305670123aed7638d984ca39bfd22388440Yabin Cui // The caller didn't provide a stack, so allocate one. 1508cf1b305670123aed7638d984ca39bfd22388440Yabin Cui // Make sure the stack size and guard size are multiples of PAGE_SIZE. 151ba8dfc2669d658dc340eb8f9c9b40ca074f05047Yabin Cui mmap_size = BIONIC_ALIGN(attr->stack_size + sizeof(pthread_internal_t), PAGE_SIZE); 1528cf1b305670123aed7638d984ca39bfd22388440Yabin Cui attr->guard_size = BIONIC_ALIGN(attr->guard_size, PAGE_SIZE); 153ba8dfc2669d658dc340eb8f9c9b40ca074f05047Yabin Cui attr->stack_base = __create_thread_mapped_space(mmap_size, attr->guard_size); 1548cf1b305670123aed7638d984ca39bfd22388440Yabin Cui if (attr->stack_base == NULL) { 1558cf1b305670123aed7638d984ca39bfd22388440Yabin Cui return EAGAIN; 1568cf1b305670123aed7638d984ca39bfd22388440Yabin Cui } 157ba8dfc2669d658dc340eb8f9c9b40ca074f05047Yabin Cui stack_top = reinterpret_cast<uint8_t*>(attr->stack_base) + mmap_size; 1588cf1b305670123aed7638d984ca39bfd22388440Yabin Cui } else { 159ba8dfc2669d658dc340eb8f9c9b40ca074f05047Yabin Cui // Remember the mmap size is zero and we don't need to free it. 160ba8dfc2669d658dc340eb8f9c9b40ca074f05047Yabin Cui mmap_size = 0; 1616a7aaf46759db32c6ed0eb953a4a230dc96af0d9Yabin Cui stack_top = reinterpret_cast<uint8_t*>(attr->stack_base) + attr->stack_size; 1628cf1b305670123aed7638d984ca39bfd22388440Yabin Cui } 1638cf1b305670123aed7638d984ca39bfd22388440Yabin Cui 164ba8dfc2669d658dc340eb8f9c9b40ca074f05047Yabin Cui // Mapped space(or user allocated stack) is used for: 165a2db50d5d7fa67b297eddd1c0549f08ea4b6a950Yabin Cui // pthread_internal_t 166ba8dfc2669d658dc340eb8f9c9b40ca074f05047Yabin Cui // thread stack (including guard page) 167a2db50d5d7fa67b297eddd1c0549f08ea4b6a950Yabin Cui 168a2db50d5d7fa67b297eddd1c0549f08ea4b6a950Yabin Cui // To safely access the pthread_internal_t and thread stack, we need to find a 16-byte aligned boundary. 169a2db50d5d7fa67b297eddd1c0549f08ea4b6a950Yabin Cui stack_top = reinterpret_cast<uint8_t*>( 170a2db50d5d7fa67b297eddd1c0549f08ea4b6a950Yabin Cui (reinterpret_cast<uintptr_t>(stack_top) - sizeof(pthread_internal_t)) & ~0xf); 171a2db50d5d7fa67b297eddd1c0549f08ea4b6a950Yabin Cui 1728cf1b305670123aed7638d984ca39bfd22388440Yabin Cui pthread_internal_t* thread = reinterpret_cast<pthread_internal_t*>(stack_top); 173917d390510e442b9b030d54992ebf41cc1e7f853Yabin Cui attr->stack_size = stack_top - reinterpret_cast<uint8_t*>(attr->stack_base); 1748cf1b305670123aed7638d984ca39bfd22388440Yabin Cui 175ba8dfc2669d658dc340eb8f9c9b40ca074f05047Yabin Cui thread->mmap_size = mmap_size; 1768cf1b305670123aed7638d984ca39bfd22388440Yabin Cui thread->attr = *attr; 1778cf1b305670123aed7638d984ca39bfd22388440Yabin Cui __init_tls(thread); 1788cf1b305670123aed7638d984ca39bfd22388440Yabin Cui 1798cf1b305670123aed7638d984ca39bfd22388440Yabin Cui *threadp = thread; 1808cf1b305670123aed7638d984ca39bfd22388440Yabin Cui *child_stack = stack_top; 1818cf1b305670123aed7638d984ca39bfd22388440Yabin Cui return 0; 1828cf1b305670123aed7638d984ca39bfd22388440Yabin Cui} 1838cf1b305670123aed7638d984ca39bfd22388440Yabin Cui 184e48b68570d872ef7ece1d873c0ea298ea76393f3Elliott Hughesstatic int __pthread_start(void* arg) { 185e48b68570d872ef7ece1d873c0ea298ea76393f3Elliott Hughes pthread_internal_t* thread = reinterpret_cast<pthread_internal_t*>(arg); 186e48b68570d872ef7ece1d873c0ea298ea76393f3Elliott Hughes 187e48b68570d872ef7ece1d873c0ea298ea76393f3Elliott Hughes // Wait for our creating thread to release us. This lets it have time to 188e48b68570d872ef7ece1d873c0ea298ea76393f3Elliott Hughes // notify gdb about this thread before we start doing anything. 189e48b68570d872ef7ece1d873c0ea298ea76393f3Elliott Hughes // This also provides the memory barrier needed to ensure that all memory 190e48b68570d872ef7ece1d873c0ea298ea76393f3Elliott Hughes // accesses previously made by the creating thread are visible to us. 191b30aff405a220495941f1673b0a5e66c4fa8b84cElliott Hughes pthread_mutex_lock(&thread->startup_handshake_mutex); 192b30aff405a220495941f1673b0a5e66c4fa8b84cElliott Hughes pthread_mutex_destroy(&thread->startup_handshake_mutex); 193e48b68570d872ef7ece1d873c0ea298ea76393f3Elliott Hughes 194e48b68570d872ef7ece1d873c0ea298ea76393f3Elliott Hughes __init_alternate_signal_stack(thread); 195e48b68570d872ef7ece1d873c0ea298ea76393f3Elliott Hughes 196e48b68570d872ef7ece1d873c0ea298ea76393f3Elliott Hughes void* result = thread->start_routine(thread->start_routine_arg); 197e48b68570d872ef7ece1d873c0ea298ea76393f3Elliott Hughes pthread_exit(result); 198e48b68570d872ef7ece1d873c0ea298ea76393f3Elliott Hughes 199e48b68570d872ef7ece1d873c0ea298ea76393f3Elliott Hughes return 0; 200e48b68570d872ef7ece1d873c0ea298ea76393f3Elliott Hughes} 201e48b68570d872ef7ece1d873c0ea298ea76393f3Elliott Hughes 202cef3faec0ea40fdfe58e425fd0be64f00de6a26dElliott Hughes// A dummy start routine for pthread_create failures where we've created a thread but aren't 203cef3faec0ea40fdfe58e425fd0be64f00de6a26dElliott Hughes// going to run user code on it. We swap out the user's start routine for this and take advantage 204cef3faec0ea40fdfe58e425fd0be64f00de6a26dElliott Hughes// of the regular thread teardown to free up resources. 205cef3faec0ea40fdfe58e425fd0be64f00de6a26dElliott Hughesstatic void* __do_nothing(void*) { 206cef3faec0ea40fdfe58e425fd0be64f00de6a26dElliott Hughes return NULL; 207cef3faec0ea40fdfe58e425fd0be64f00de6a26dElliott Hughes} 208cef3faec0ea40fdfe58e425fd0be64f00de6a26dElliott Hughes 2094b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughesint pthread_create(pthread_t* thread_out, pthread_attr_t const* attr, 2104b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes void* (*start_routine)(void*), void* arg) { 2114b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes ErrnoRestorer errno_restorer; 2124b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes 213f2cea021ab2c6d7d7feeb40cca098aa132605876Elliott Hughes // Inform the rest of the C library that at least one thread was created. 2144b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes __isthreaded = 1; 2154b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes 2168cf1b305670123aed7638d984ca39bfd22388440Yabin Cui pthread_attr_t thread_attr; 2174b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes if (attr == NULL) { 2188cf1b305670123aed7638d984ca39bfd22388440Yabin Cui pthread_attr_init(&thread_attr); 2194b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes } else { 2208cf1b305670123aed7638d984ca39bfd22388440Yabin Cui thread_attr = *attr; 2214b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes attr = NULL; // Prevent misuse below. 2224b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes } 2234b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes 2248cf1b305670123aed7638d984ca39bfd22388440Yabin Cui pthread_internal_t* thread = NULL; 2258cf1b305670123aed7638d984ca39bfd22388440Yabin Cui void* child_stack = NULL; 2268cf1b305670123aed7638d984ca39bfd22388440Yabin Cui int result = __allocate_thread(&thread_attr, &thread, &child_stack); 2278cf1b305670123aed7638d984ca39bfd22388440Yabin Cui if (result != 0) { 2288cf1b305670123aed7638d984ca39bfd22388440Yabin Cui return result; 2294b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes } 2304b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes 23170b24b1cc2a1a4436b1fea3f8b76616fdcb27224Elliott Hughes // Create a mutex for the thread in TLS to wait on once it starts so we can keep 2324b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes // it from doing anything until after we notify the debugger about it 2334b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes // 2344b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes // This also provides the memory barrier we need to ensure that all 2354b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes // memory accesses previously performed by this thread are visible to 2364b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes // the new thread. 237b30aff405a220495941f1673b0a5e66c4fa8b84cElliott Hughes pthread_mutex_init(&thread->startup_handshake_mutex, NULL); 238b30aff405a220495941f1673b0a5e66c4fa8b84cElliott Hughes pthread_mutex_lock(&thread->startup_handshake_mutex); 2394b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes 24070b24b1cc2a1a4436b1fea3f8b76616fdcb27224Elliott Hughes thread->start_routine = start_routine; 24170b24b1cc2a1a4436b1fea3f8b76616fdcb27224Elliott Hughes thread->start_routine_arg = arg; 2424b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes 2437086ad6919feb2415c6027163f5c63323bcca27cElliott Hughes thread->set_cached_pid(getpid()); 2447086ad6919feb2415c6027163f5c63323bcca27cElliott Hughes 245877ec6d90418ff1d6597147d355a2229fdffae7eElliott Hughes int flags = CLONE_VM | CLONE_FS | CLONE_FILES | CLONE_SIGHAND | CLONE_THREAD | CLONE_SYSVSEM | 246877ec6d90418ff1d6597147d355a2229fdffae7eElliott Hughes CLONE_SETTLS | CLONE_PARENT_SETTID | CLONE_CHILD_CLEARTID; 2478cf1b305670123aed7638d984ca39bfd22388440Yabin Cui void* tls = reinterpret_cast<void*>(thread->tls); 24880906141f79be8be63fc915bfab467029b442ca1Elliott Hughes#if defined(__i386__) 24980906141f79be8be63fc915bfab467029b442ca1Elliott Hughes // On x86 (but not x86-64), CLONE_SETTLS takes a pointer to a struct user_desc rather than 2500d236aa3f1e6d31b0c729448ae9d3ed1cad23fb4Elliott Hughes // a pointer to the TLS itself. 2510d236aa3f1e6d31b0c729448ae9d3ed1cad23fb4Elliott Hughes user_desc tls_descriptor; 2520d236aa3f1e6d31b0c729448ae9d3ed1cad23fb4Elliott Hughes __init_user_desc(&tls_descriptor, false, tls); 2530d236aa3f1e6d31b0c729448ae9d3ed1cad23fb4Elliott Hughes tls = &tls_descriptor; 25480906141f79be8be63fc915bfab467029b442ca1Elliott Hughes#endif 2550d236aa3f1e6d31b0c729448ae9d3ed1cad23fb4Elliott Hughes int rc = clone(__pthread_start, child_stack, flags, thread, &(thread->tid), tls, &(thread->tid)); 256877ec6d90418ff1d6597147d355a2229fdffae7eElliott Hughes if (rc == -1) { 2574b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes int clone_errno = errno; 258877ec6d90418ff1d6597147d355a2229fdffae7eElliott Hughes // We don't have to unlock the mutex at all because clone(2) failed so there's no child waiting to 259877ec6d90418ff1d6597147d355a2229fdffae7eElliott Hughes // be unblocked, but we're about to unmap the memory the mutex is stored in, so this serves as a 260877ec6d90418ff1d6597147d355a2229fdffae7eElliott Hughes // reminder that you can't rewrite this function to use a ScopedPthreadMutexLocker. 261b30aff405a220495941f1673b0a5e66c4fa8b84cElliott Hughes pthread_mutex_unlock(&thread->startup_handshake_mutex); 262ba8dfc2669d658dc340eb8f9c9b40ca074f05047Yabin Cui if (thread->mmap_size != 0) { 263ba8dfc2669d658dc340eb8f9c9b40ca074f05047Yabin Cui munmap(thread->attr.stack_base, thread->mmap_size); 2644b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes } 265cfa089df23ff50fcd5ed3854c54991d30be5fc7eElliott Hughes __libc_format_log(ANDROID_LOG_WARN, "libc", "pthread_create failed: clone failed: %s", strerror(errno)); 2664b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes return clone_errno; 2674b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes } 2684b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes 269cef3faec0ea40fdfe58e425fd0be64f00de6a26dElliott Hughes int init_errno = __init_thread(thread, true); 2704b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes if (init_errno != 0) { 271cef3faec0ea40fdfe58e425fd0be64f00de6a26dElliott Hughes // Mark the thread detached and replace its start_routine with a no-op. 272cef3faec0ea40fdfe58e425fd0be64f00de6a26dElliott Hughes // Letting the thread run is the easiest way to clean up its resources. 27358cf31b50699ed9f523de38c8e943f3bbd1ced9eYabin Cui atomic_store(&thread->join_state, THREAD_DETACHED); 274cef3faec0ea40fdfe58e425fd0be64f00de6a26dElliott Hughes thread->start_routine = __do_nothing; 275b30aff405a220495941f1673b0a5e66c4fa8b84cElliott Hughes pthread_mutex_unlock(&thread->startup_handshake_mutex); 2764b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes return init_errno; 2774b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes } 2784b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes 279877ec6d90418ff1d6597147d355a2229fdffae7eElliott Hughes // Publish the pthread_t and unlock the mutex to let the new thread start running. 280877ec6d90418ff1d6597147d355a2229fdffae7eElliott Hughes *thread_out = reinterpret_cast<pthread_t>(thread); 281b30aff405a220495941f1673b0a5e66c4fa8b84cElliott Hughes pthread_mutex_unlock(&thread->startup_handshake_mutex); 2824b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes 2834b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes return 0; 2844b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes} 285