pthread_create.cpp revision 6a7aaf46759db32c6ed0eb953a4a230dc96af0d9
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) { 5540a521744825b6060960c296d5fb3da4c6593d94Elliott Hughes if (thread->user_allocated_stack()) { 5640a521744825b6060960c296d5fb3da4c6593d94Elliott Hughes // We don't know where the user got their stack, so assume the worst and zero the TLS area. 5740a521744825b6060960c296d5fb3da4c6593d94Elliott Hughes memset(&thread->tls[0], 0, BIONIC_TLS_SLOTS * sizeof(void*)); 584b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes } 594b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes 604b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes // Slot 0 must point to itself. The x86 Linux kernel reads the TLS from %fs:0. 6140eabe24e4e3ae8ebe437f1f4e43cf39cbba2e9eElliott Hughes thread->tls[TLS_SLOT_SELF] = thread->tls; 6240eabe24e4e3ae8ebe437f1f4e43cf39cbba2e9eElliott Hughes thread->tls[TLS_SLOT_THREAD_ID] = thread; 634b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes // GCC looks in the TLS for the stack guard on x86, so copy it there from our global. 6440eabe24e4e3ae8ebe437f1f4e43cf39cbba2e9eElliott Hughes thread->tls[TLS_SLOT_STACK_GUARD] = (void*) __stack_chk_guard; 6570b24b1cc2a1a4436b1fea3f8b76616fdcb27224Elliott Hughes} 664b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes 6770b24b1cc2a1a4436b1fea3f8b76616fdcb27224Elliott Hughesvoid __init_alternate_signal_stack(pthread_internal_t* thread) { 6884114c8dd5b17efecf7988f263ce431208d7be5aElliott Hughes // Create and set an alternate signal stack. 6984114c8dd5b17efecf7988f263ce431208d7be5aElliott Hughes stack_t ss; 7040a521744825b6060960c296d5fb3da4c6593d94Elliott Hughes ss.ss_sp = mmap(NULL, SIGSTKSZ, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0); 7184114c8dd5b17efecf7988f263ce431208d7be5aElliott Hughes if (ss.ss_sp != MAP_FAILED) { 7284114c8dd5b17efecf7988f263ce431208d7be5aElliott Hughes ss.ss_size = SIGSTKSZ; 7384114c8dd5b17efecf7988f263ce431208d7be5aElliott Hughes ss.ss_flags = 0; 7484114c8dd5b17efecf7988f263ce431208d7be5aElliott Hughes sigaltstack(&ss, NULL); 7584114c8dd5b17efecf7988f263ce431208d7be5aElliott Hughes thread->alternate_signal_stack = ss.ss_sp; 768cf1b305670123aed7638d984ca39bfd22388440Yabin Cui 778cf1b305670123aed7638d984ca39bfd22388440Yabin Cui // We can only use const static allocated string for mapped region name, as Android kernel 788cf1b305670123aed7638d984ca39bfd22388440Yabin Cui // uses the string pointer directly when dumping /proc/pid/maps. 798cf1b305670123aed7638d984ca39bfd22388440Yabin Cui prctl(PR_SET_VMA, PR_SET_VMA_ANON_NAME, ss.ss_sp, ss.ss_size, "thread signal stack"); 8084114c8dd5b17efecf7988f263ce431208d7be5aElliott Hughes } 814b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes} 824b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes 83cef3faec0ea40fdfe58e425fd0be64f00de6a26dElliott Hughesint __init_thread(pthread_internal_t* thread, bool add_to_thread_list) { 844b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes int error = 0; 854b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes 864b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes // Set the scheduling policy/priority of the thread. 874b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes if (thread->attr.sched_policy != SCHED_NORMAL) { 88c3f114037dbf028896310609fd28cf2b3da99c4dElliott Hughes sched_param param; 894b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes param.sched_priority = thread->attr.sched_priority; 9040eabe24e4e3ae8ebe437f1f4e43cf39cbba2e9eElliott Hughes if (sched_setscheduler(thread->tid, thread->attr.sched_policy, ¶m) == -1) { 9198624c374646a050556bdc402b55b792fefa7e55Elliott Hughes#if __LP64__ 9298624c374646a050556bdc402b55b792fefa7e55Elliott Hughes // For backwards compatibility reasons, we only report failures on 64-bit devices. 9398624c374646a050556bdc402b55b792fefa7e55Elliott Hughes error = errno; 9498624c374646a050556bdc402b55b792fefa7e55Elliott Hughes#endif 95b95cf0d23a1db3b7c37bd98b0c86196796c9b029Elliott Hughes __libc_format_log(ANDROID_LOG_WARN, "libc", 96b95cf0d23a1db3b7c37bd98b0c86196796c9b029Elliott Hughes "pthread_create sched_setscheduler call failed: %s", strerror(errno)); 974b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes } 984b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes } 994b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes 1004b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes thread->cleanup_stack = NULL; 1014b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes 1024b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes if (add_to_thread_list) { 1034b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes _pthread_internal_add(thread); 1044b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes } 1054b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes 1064b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes return error; 1074b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes} 1084b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes 1096a7aaf46759db32c6ed0eb953a4a230dc96af0d9Yabin Cuistatic void* __create_thread_stack(size_t stack_size, size_t guard_size) { 1104b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes // Create a new private anonymous map. 1114b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes int prot = PROT_READ | PROT_WRITE; 1124b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes int flags = MAP_PRIVATE | MAP_ANONYMOUS | MAP_NORESERVE; 1136a7aaf46759db32c6ed0eb953a4a230dc96af0d9Yabin Cui void* stack = mmap(NULL, stack_size, prot, flags, -1, 0); 1144b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes if (stack == MAP_FAILED) { 115b95cf0d23a1db3b7c37bd98b0c86196796c9b029Elliott Hughes __libc_format_log(ANDROID_LOG_WARN, 116b95cf0d23a1db3b7c37bd98b0c86196796c9b029Elliott Hughes "libc", 117b95cf0d23a1db3b7c37bd98b0c86196796c9b029Elliott Hughes "pthread_create failed: couldn't allocate %zd-byte stack: %s", 1186a7aaf46759db32c6ed0eb953a4a230dc96af0d9Yabin Cui stack_size, strerror(errno)); 1194b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes return NULL; 1204b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes } 1214b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes 1224b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes // Set the guard region at the end of the stack to PROT_NONE. 1236a7aaf46759db32c6ed0eb953a4a230dc96af0d9Yabin Cui if (mprotect(stack, guard_size, PROT_NONE) == -1) { 124b95cf0d23a1db3b7c37bd98b0c86196796c9b029Elliott Hughes __libc_format_log(ANDROID_LOG_WARN, "libc", 125b95cf0d23a1db3b7c37bd98b0c86196796c9b029Elliott Hughes "pthread_create failed: couldn't mprotect PROT_NONE %zd-byte stack guard region: %s", 1266a7aaf46759db32c6ed0eb953a4a230dc96af0d9Yabin Cui guard_size, strerror(errno)); 1276a7aaf46759db32c6ed0eb953a4a230dc96af0d9Yabin Cui munmap(stack, stack_size); 1284b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes return NULL; 1294b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes } 1304b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes 1314b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes return stack; 1324b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes} 1334b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes 1348cf1b305670123aed7638d984ca39bfd22388440Yabin Cuistatic int __allocate_thread(pthread_attr_t* attr, pthread_internal_t** threadp, void** child_stack) { 1356a7aaf46759db32c6ed0eb953a4a230dc96af0d9Yabin Cui size_t allocate_stack_size; 1366a7aaf46759db32c6ed0eb953a4a230dc96af0d9Yabin Cui uint8_t* stack_top; 1376a7aaf46759db32c6ed0eb953a4a230dc96af0d9Yabin Cui 1388cf1b305670123aed7638d984ca39bfd22388440Yabin Cui if (attr->stack_base == NULL) { 1398cf1b305670123aed7638d984ca39bfd22388440Yabin Cui // The caller didn't provide a stack, so allocate one. 1408cf1b305670123aed7638d984ca39bfd22388440Yabin Cui // Make sure the stack size and guard size are multiples of PAGE_SIZE. 1416a7aaf46759db32c6ed0eb953a4a230dc96af0d9Yabin Cui allocate_stack_size = BIONIC_ALIGN(attr->stack_size + sizeof(pthread_internal_t), PAGE_SIZE); 1428cf1b305670123aed7638d984ca39bfd22388440Yabin Cui attr->guard_size = BIONIC_ALIGN(attr->guard_size, PAGE_SIZE); 1436a7aaf46759db32c6ed0eb953a4a230dc96af0d9Yabin Cui attr->stack_base = __create_thread_stack(allocate_stack_size, attr->guard_size); 1448cf1b305670123aed7638d984ca39bfd22388440Yabin Cui if (attr->stack_base == NULL) { 1458cf1b305670123aed7638d984ca39bfd22388440Yabin Cui return EAGAIN; 1468cf1b305670123aed7638d984ca39bfd22388440Yabin Cui } 1476a7aaf46759db32c6ed0eb953a4a230dc96af0d9Yabin Cui stack_top = reinterpret_cast<uint8_t*>(attr->stack_base) + allocate_stack_size; 1488cf1b305670123aed7638d984ca39bfd22388440Yabin Cui } else { 1498cf1b305670123aed7638d984ca39bfd22388440Yabin Cui // The caller did provide a stack, so remember we're not supposed to free it. 1508cf1b305670123aed7638d984ca39bfd22388440Yabin Cui attr->flags |= PTHREAD_ATTR_FLAG_USER_ALLOCATED_STACK; 1516a7aaf46759db32c6ed0eb953a4a230dc96af0d9Yabin Cui allocate_stack_size = 0; 1526a7aaf46759db32c6ed0eb953a4a230dc96af0d9Yabin Cui stack_top = reinterpret_cast<uint8_t*>(attr->stack_base) + attr->stack_size; 1538cf1b305670123aed7638d984ca39bfd22388440Yabin Cui } 1548cf1b305670123aed7638d984ca39bfd22388440Yabin Cui 1558cf1b305670123aed7638d984ca39bfd22388440Yabin Cui // Thread stack is used for two sections: 1568cf1b305670123aed7638d984ca39bfd22388440Yabin Cui // pthread_internal_t. 1578cf1b305670123aed7638d984ca39bfd22388440Yabin Cui // regular stack, from top to down. 1588cf1b305670123aed7638d984ca39bfd22388440Yabin Cui stack_top -= sizeof(pthread_internal_t); 1598cf1b305670123aed7638d984ca39bfd22388440Yabin Cui pthread_internal_t* thread = reinterpret_cast<pthread_internal_t*>(stack_top); 1608cf1b305670123aed7638d984ca39bfd22388440Yabin Cui 1618cf1b305670123aed7638d984ca39bfd22388440Yabin Cui // No need to check stack_top alignment. The size of pthread_internal_t is 16-bytes aligned, 1628cf1b305670123aed7638d984ca39bfd22388440Yabin Cui // and user allocated stack is guaranteed by pthread_attr_setstack. 1638cf1b305670123aed7638d984ca39bfd22388440Yabin Cui 1646a7aaf46759db32c6ed0eb953a4a230dc96af0d9Yabin Cui thread->allocated_stack_size = allocate_stack_size; 1658cf1b305670123aed7638d984ca39bfd22388440Yabin Cui thread->attr = *attr; 1668cf1b305670123aed7638d984ca39bfd22388440Yabin Cui __init_tls(thread); 1678cf1b305670123aed7638d984ca39bfd22388440Yabin Cui 1688cf1b305670123aed7638d984ca39bfd22388440Yabin Cui *threadp = thread; 1698cf1b305670123aed7638d984ca39bfd22388440Yabin Cui *child_stack = stack_top; 1708cf1b305670123aed7638d984ca39bfd22388440Yabin Cui return 0; 1718cf1b305670123aed7638d984ca39bfd22388440Yabin Cui} 1728cf1b305670123aed7638d984ca39bfd22388440Yabin Cui 173e48b68570d872ef7ece1d873c0ea298ea76393f3Elliott Hughesstatic int __pthread_start(void* arg) { 174e48b68570d872ef7ece1d873c0ea298ea76393f3Elliott Hughes pthread_internal_t* thread = reinterpret_cast<pthread_internal_t*>(arg); 175e48b68570d872ef7ece1d873c0ea298ea76393f3Elliott Hughes 176e48b68570d872ef7ece1d873c0ea298ea76393f3Elliott Hughes // Wait for our creating thread to release us. This lets it have time to 177e48b68570d872ef7ece1d873c0ea298ea76393f3Elliott Hughes // notify gdb about this thread before we start doing anything. 178e48b68570d872ef7ece1d873c0ea298ea76393f3Elliott Hughes // This also provides the memory barrier needed to ensure that all memory 179e48b68570d872ef7ece1d873c0ea298ea76393f3Elliott Hughes // accesses previously made by the creating thread are visible to us. 180b30aff405a220495941f1673b0a5e66c4fa8b84cElliott Hughes pthread_mutex_lock(&thread->startup_handshake_mutex); 181b30aff405a220495941f1673b0a5e66c4fa8b84cElliott Hughes pthread_mutex_destroy(&thread->startup_handshake_mutex); 182e48b68570d872ef7ece1d873c0ea298ea76393f3Elliott Hughes 183e48b68570d872ef7ece1d873c0ea298ea76393f3Elliott Hughes __init_alternate_signal_stack(thread); 184e48b68570d872ef7ece1d873c0ea298ea76393f3Elliott Hughes 185e48b68570d872ef7ece1d873c0ea298ea76393f3Elliott Hughes void* result = thread->start_routine(thread->start_routine_arg); 186e48b68570d872ef7ece1d873c0ea298ea76393f3Elliott Hughes pthread_exit(result); 187e48b68570d872ef7ece1d873c0ea298ea76393f3Elliott Hughes 188e48b68570d872ef7ece1d873c0ea298ea76393f3Elliott Hughes return 0; 189e48b68570d872ef7ece1d873c0ea298ea76393f3Elliott Hughes} 190e48b68570d872ef7ece1d873c0ea298ea76393f3Elliott Hughes 191cef3faec0ea40fdfe58e425fd0be64f00de6a26dElliott Hughes// A dummy start routine for pthread_create failures where we've created a thread but aren't 192cef3faec0ea40fdfe58e425fd0be64f00de6a26dElliott Hughes// going to run user code on it. We swap out the user's start routine for this and take advantage 193cef3faec0ea40fdfe58e425fd0be64f00de6a26dElliott Hughes// of the regular thread teardown to free up resources. 194cef3faec0ea40fdfe58e425fd0be64f00de6a26dElliott Hughesstatic void* __do_nothing(void*) { 195cef3faec0ea40fdfe58e425fd0be64f00de6a26dElliott Hughes return NULL; 196cef3faec0ea40fdfe58e425fd0be64f00de6a26dElliott Hughes} 197cef3faec0ea40fdfe58e425fd0be64f00de6a26dElliott Hughes 1984b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughesint pthread_create(pthread_t* thread_out, pthread_attr_t const* attr, 1994b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes void* (*start_routine)(void*), void* arg) { 2004b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes ErrnoRestorer errno_restorer; 2014b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes 202f2cea021ab2c6d7d7feeb40cca098aa132605876Elliott Hughes // Inform the rest of the C library that at least one thread was created. 2034b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes __isthreaded = 1; 2044b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes 2058cf1b305670123aed7638d984ca39bfd22388440Yabin Cui pthread_attr_t thread_attr; 2064b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes if (attr == NULL) { 2078cf1b305670123aed7638d984ca39bfd22388440Yabin Cui pthread_attr_init(&thread_attr); 2084b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes } else { 2098cf1b305670123aed7638d984ca39bfd22388440Yabin Cui thread_attr = *attr; 2104b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes attr = NULL; // Prevent misuse below. 2114b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes } 2124b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes 2138cf1b305670123aed7638d984ca39bfd22388440Yabin Cui pthread_internal_t* thread = NULL; 2148cf1b305670123aed7638d984ca39bfd22388440Yabin Cui void* child_stack = NULL; 2158cf1b305670123aed7638d984ca39bfd22388440Yabin Cui int result = __allocate_thread(&thread_attr, &thread, &child_stack); 2168cf1b305670123aed7638d984ca39bfd22388440Yabin Cui if (result != 0) { 2178cf1b305670123aed7638d984ca39bfd22388440Yabin Cui return result; 2184b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes } 2194b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes 22070b24b1cc2a1a4436b1fea3f8b76616fdcb27224Elliott Hughes // Create a mutex for the thread in TLS to wait on once it starts so we can keep 2214b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes // it from doing anything until after we notify the debugger about it 2224b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes // 2234b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes // This also provides the memory barrier we need to ensure that all 2244b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes // memory accesses previously performed by this thread are visible to 2254b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes // the new thread. 226b30aff405a220495941f1673b0a5e66c4fa8b84cElliott Hughes pthread_mutex_init(&thread->startup_handshake_mutex, NULL); 227b30aff405a220495941f1673b0a5e66c4fa8b84cElliott Hughes pthread_mutex_lock(&thread->startup_handshake_mutex); 2284b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes 22970b24b1cc2a1a4436b1fea3f8b76616fdcb27224Elliott Hughes thread->start_routine = start_routine; 23070b24b1cc2a1a4436b1fea3f8b76616fdcb27224Elliott Hughes thread->start_routine_arg = arg; 2314b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes 2327086ad6919feb2415c6027163f5c63323bcca27cElliott Hughes thread->set_cached_pid(getpid()); 2337086ad6919feb2415c6027163f5c63323bcca27cElliott Hughes 234877ec6d90418ff1d6597147d355a2229fdffae7eElliott Hughes int flags = CLONE_VM | CLONE_FS | CLONE_FILES | CLONE_SIGHAND | CLONE_THREAD | CLONE_SYSVSEM | 235877ec6d90418ff1d6597147d355a2229fdffae7eElliott Hughes CLONE_SETTLS | CLONE_PARENT_SETTID | CLONE_CHILD_CLEARTID; 2368cf1b305670123aed7638d984ca39bfd22388440Yabin Cui void* tls = reinterpret_cast<void*>(thread->tls); 23780906141f79be8be63fc915bfab467029b442ca1Elliott Hughes#if defined(__i386__) 23880906141f79be8be63fc915bfab467029b442ca1Elliott Hughes // On x86 (but not x86-64), CLONE_SETTLS takes a pointer to a struct user_desc rather than 2390d236aa3f1e6d31b0c729448ae9d3ed1cad23fb4Elliott Hughes // a pointer to the TLS itself. 2400d236aa3f1e6d31b0c729448ae9d3ed1cad23fb4Elliott Hughes user_desc tls_descriptor; 2410d236aa3f1e6d31b0c729448ae9d3ed1cad23fb4Elliott Hughes __init_user_desc(&tls_descriptor, false, tls); 2420d236aa3f1e6d31b0c729448ae9d3ed1cad23fb4Elliott Hughes tls = &tls_descriptor; 24380906141f79be8be63fc915bfab467029b442ca1Elliott Hughes#endif 2440d236aa3f1e6d31b0c729448ae9d3ed1cad23fb4Elliott Hughes int rc = clone(__pthread_start, child_stack, flags, thread, &(thread->tid), tls, &(thread->tid)); 245877ec6d90418ff1d6597147d355a2229fdffae7eElliott Hughes if (rc == -1) { 2464b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes int clone_errno = errno; 247877ec6d90418ff1d6597147d355a2229fdffae7eElliott Hughes // We don't have to unlock the mutex at all because clone(2) failed so there's no child waiting to 248877ec6d90418ff1d6597147d355a2229fdffae7eElliott Hughes // be unblocked, but we're about to unmap the memory the mutex is stored in, so this serves as a 249877ec6d90418ff1d6597147d355a2229fdffae7eElliott Hughes // reminder that you can't rewrite this function to use a ScopedPthreadMutexLocker. 250b30aff405a220495941f1673b0a5e66c4fa8b84cElliott Hughes pthread_mutex_unlock(&thread->startup_handshake_mutex); 25140a521744825b6060960c296d5fb3da4c6593d94Elliott Hughes if (!thread->user_allocated_stack()) { 2526a7aaf46759db32c6ed0eb953a4a230dc96af0d9Yabin Cui munmap(thread->attr.stack_base, thread->allocated_stack_size); 2534b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes } 254cfa089df23ff50fcd5ed3854c54991d30be5fc7eElliott Hughes __libc_format_log(ANDROID_LOG_WARN, "libc", "pthread_create failed: clone failed: %s", strerror(errno)); 2554b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes return clone_errno; 2564b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes } 2574b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes 258cef3faec0ea40fdfe58e425fd0be64f00de6a26dElliott Hughes int init_errno = __init_thread(thread, true); 2594b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes if (init_errno != 0) { 260cef3faec0ea40fdfe58e425fd0be64f00de6a26dElliott Hughes // Mark the thread detached and replace its start_routine with a no-op. 261cef3faec0ea40fdfe58e425fd0be64f00de6a26dElliott Hughes // Letting the thread run is the easiest way to clean up its resources. 2624b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes thread->attr.flags |= PTHREAD_ATTR_FLAG_DETACHED; 263cef3faec0ea40fdfe58e425fd0be64f00de6a26dElliott Hughes thread->start_routine = __do_nothing; 264b30aff405a220495941f1673b0a5e66c4fa8b84cElliott Hughes pthread_mutex_unlock(&thread->startup_handshake_mutex); 2654b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes return init_errno; 2664b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes } 2674b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes 268877ec6d90418ff1d6597147d355a2229fdffae7eElliott Hughes // Publish the pthread_t and unlock the mutex to let the new thread start running. 269877ec6d90418ff1d6597147d355a2229fdffae7eElliott Hughes *thread_out = reinterpret_cast<pthread_t>(thread); 270b30aff405a220495941f1673b0a5e66c4fa8b84cElliott Hughes pthread_mutex_unlock(&thread->startup_handshake_mutex); 2714b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes 2724b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes return 0; 2734b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes} 274