pthread_create.cpp revision 5e2bd719d7dd19afe55f8d4f24366c0230e0e6c7
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 894b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes // Set the scheduling policy/priority of the thread. 904b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes if (thread->attr.sched_policy != SCHED_NORMAL) { 91c3f114037dbf028896310609fd28cf2b3da99c4dElliott Hughes sched_param param; 924b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes param.sched_priority = thread->attr.sched_priority; 9340eabe24e4e3ae8ebe437f1f4e43cf39cbba2e9eElliott Hughes if (sched_setscheduler(thread->tid, thread->attr.sched_policy, ¶m) == -1) { 9498624c374646a050556bdc402b55b792fefa7e55Elliott Hughes#if __LP64__ 9598624c374646a050556bdc402b55b792fefa7e55Elliott Hughes // For backwards compatibility reasons, we only report failures on 64-bit devices. 9698624c374646a050556bdc402b55b792fefa7e55Elliott Hughes error = errno; 9798624c374646a050556bdc402b55b792fefa7e55Elliott Hughes#endif 98b95cf0d23a1db3b7c37bd98b0c86196796c9b029Elliott Hughes __libc_format_log(ANDROID_LOG_WARN, "libc", 99b95cf0d23a1db3b7c37bd98b0c86196796c9b029Elliott Hughes "pthread_create sched_setscheduler call failed: %s", strerror(errno)); 1004b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes } 1014b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes } 1024b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes 1034b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes thread->cleanup_stack = NULL; 1044b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes 1054b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes if (add_to_thread_list) { 1064b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes _pthread_internal_add(thread); 1074b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes } 1084b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes 1094b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes return error; 1104b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes} 1114b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes 112ba8dfc2669d658dc340eb8f9c9b40ca074f05047Yabin Cuistatic void* __create_thread_mapped_space(size_t mmap_size, size_t stack_guard_size) { 1134b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes // Create a new private anonymous map. 1144b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes int prot = PROT_READ | PROT_WRITE; 1154b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes int flags = MAP_PRIVATE | MAP_ANONYMOUS | MAP_NORESERVE; 116ba8dfc2669d658dc340eb8f9c9b40ca074f05047Yabin Cui void* space = mmap(NULL, mmap_size, prot, flags, -1, 0); 117ba8dfc2669d658dc340eb8f9c9b40ca074f05047Yabin Cui if (space == MAP_FAILED) { 118b95cf0d23a1db3b7c37bd98b0c86196796c9b029Elliott Hughes __libc_format_log(ANDROID_LOG_WARN, 119b95cf0d23a1db3b7c37bd98b0c86196796c9b029Elliott Hughes "libc", 120ba8dfc2669d658dc340eb8f9c9b40ca074f05047Yabin Cui "pthread_create failed: couldn't allocate %zu-bytes mapped space: %s", 121ba8dfc2669d658dc340eb8f9c9b40ca074f05047Yabin Cui mmap_size, strerror(errno)); 1224b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes return NULL; 1234b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes } 1244b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes 125ba8dfc2669d658dc340eb8f9c9b40ca074f05047Yabin Cui // Stack is at the lower end of mapped space, stack guard region is at the lower end of stack. 126ba8dfc2669d658dc340eb8f9c9b40ca074f05047Yabin Cui // Set the stack guard region to PROT_NONE, so we can detect thread stack overflow. 127ba8dfc2669d658dc340eb8f9c9b40ca074f05047Yabin Cui if (mprotect(space, stack_guard_size, PROT_NONE) == -1) { 128b95cf0d23a1db3b7c37bd98b0c86196796c9b029Elliott Hughes __libc_format_log(ANDROID_LOG_WARN, "libc", 129ba8dfc2669d658dc340eb8f9c9b40ca074f05047Yabin Cui "pthread_create failed: couldn't mprotect PROT_NONE %zu-byte stack guard region: %s", 130ba8dfc2669d658dc340eb8f9c9b40ca074f05047Yabin Cui stack_guard_size, strerror(errno)); 131ba8dfc2669d658dc340eb8f9c9b40ca074f05047Yabin Cui munmap(space, mmap_size); 1324b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes return NULL; 1334b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes } 1344b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes 135ba8dfc2669d658dc340eb8f9c9b40ca074f05047Yabin Cui return space; 1364b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes} 1374b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes 1388cf1b305670123aed7638d984ca39bfd22388440Yabin Cuistatic int __allocate_thread(pthread_attr_t* attr, pthread_internal_t** threadp, void** child_stack) { 139ba8dfc2669d658dc340eb8f9c9b40ca074f05047Yabin Cui size_t mmap_size; 1406a7aaf46759db32c6ed0eb953a4a230dc96af0d9Yabin Cui uint8_t* stack_top; 1416a7aaf46759db32c6ed0eb953a4a230dc96af0d9Yabin Cui 1428cf1b305670123aed7638d984ca39bfd22388440Yabin Cui if (attr->stack_base == NULL) { 1438cf1b305670123aed7638d984ca39bfd22388440Yabin Cui // The caller didn't provide a stack, so allocate one. 1448cf1b305670123aed7638d984ca39bfd22388440Yabin Cui // Make sure the stack size and guard size are multiples of PAGE_SIZE. 145ba8dfc2669d658dc340eb8f9c9b40ca074f05047Yabin Cui mmap_size = BIONIC_ALIGN(attr->stack_size + sizeof(pthread_internal_t), PAGE_SIZE); 1468cf1b305670123aed7638d984ca39bfd22388440Yabin Cui attr->guard_size = BIONIC_ALIGN(attr->guard_size, PAGE_SIZE); 147ba8dfc2669d658dc340eb8f9c9b40ca074f05047Yabin Cui attr->stack_base = __create_thread_mapped_space(mmap_size, attr->guard_size); 1488cf1b305670123aed7638d984ca39bfd22388440Yabin Cui if (attr->stack_base == NULL) { 1498cf1b305670123aed7638d984ca39bfd22388440Yabin Cui return EAGAIN; 1508cf1b305670123aed7638d984ca39bfd22388440Yabin Cui } 151ba8dfc2669d658dc340eb8f9c9b40ca074f05047Yabin Cui stack_top = reinterpret_cast<uint8_t*>(attr->stack_base) + mmap_size; 1528cf1b305670123aed7638d984ca39bfd22388440Yabin Cui } else { 153ba8dfc2669d658dc340eb8f9c9b40ca074f05047Yabin Cui // Remember the mmap size is zero and we don't need to free it. 154ba8dfc2669d658dc340eb8f9c9b40ca074f05047Yabin Cui mmap_size = 0; 1556a7aaf46759db32c6ed0eb953a4a230dc96af0d9Yabin Cui stack_top = reinterpret_cast<uint8_t*>(attr->stack_base) + attr->stack_size; 1568cf1b305670123aed7638d984ca39bfd22388440Yabin Cui } 1578cf1b305670123aed7638d984ca39bfd22388440Yabin Cui 158ba8dfc2669d658dc340eb8f9c9b40ca074f05047Yabin Cui // Mapped space(or user allocated stack) is used for: 1595e2bd719d7dd19afe55f8d4f24366c0230e0e6c7Yabin Cui // thread_internal_t 160ba8dfc2669d658dc340eb8f9c9b40ca074f05047Yabin Cui // thread stack (including guard page) 1618cf1b305670123aed7638d984ca39bfd22388440Yabin Cui stack_top -= sizeof(pthread_internal_t); 1628cf1b305670123aed7638d984ca39bfd22388440Yabin Cui pthread_internal_t* thread = reinterpret_cast<pthread_internal_t*>(stack_top); 163917d390510e442b9b030d54992ebf41cc1e7f853Yabin Cui attr->stack_size = stack_top - reinterpret_cast<uint8_t*>(attr->stack_base); 1648cf1b305670123aed7638d984ca39bfd22388440Yabin Cui 1658cf1b305670123aed7638d984ca39bfd22388440Yabin Cui // No need to check stack_top alignment. The size of pthread_internal_t is 16-bytes aligned, 1668cf1b305670123aed7638d984ca39bfd22388440Yabin Cui // and user allocated stack is guaranteed by pthread_attr_setstack. 1678cf1b305670123aed7638d984ca39bfd22388440Yabin Cui 168ba8dfc2669d658dc340eb8f9c9b40ca074f05047Yabin Cui thread->mmap_size = mmap_size; 1698cf1b305670123aed7638d984ca39bfd22388440Yabin Cui thread->attr = *attr; 1708cf1b305670123aed7638d984ca39bfd22388440Yabin Cui __init_tls(thread); 1718cf1b305670123aed7638d984ca39bfd22388440Yabin Cui 1728cf1b305670123aed7638d984ca39bfd22388440Yabin Cui *threadp = thread; 1738cf1b305670123aed7638d984ca39bfd22388440Yabin Cui *child_stack = stack_top; 1748cf1b305670123aed7638d984ca39bfd22388440Yabin Cui return 0; 1758cf1b305670123aed7638d984ca39bfd22388440Yabin Cui} 1768cf1b305670123aed7638d984ca39bfd22388440Yabin Cui 177e48b68570d872ef7ece1d873c0ea298ea76393f3Elliott Hughesstatic int __pthread_start(void* arg) { 178e48b68570d872ef7ece1d873c0ea298ea76393f3Elliott Hughes pthread_internal_t* thread = reinterpret_cast<pthread_internal_t*>(arg); 179e48b68570d872ef7ece1d873c0ea298ea76393f3Elliott Hughes 180e48b68570d872ef7ece1d873c0ea298ea76393f3Elliott Hughes // Wait for our creating thread to release us. This lets it have time to 181e48b68570d872ef7ece1d873c0ea298ea76393f3Elliott Hughes // notify gdb about this thread before we start doing anything. 182e48b68570d872ef7ece1d873c0ea298ea76393f3Elliott Hughes // This also provides the memory barrier needed to ensure that all memory 183e48b68570d872ef7ece1d873c0ea298ea76393f3Elliott Hughes // accesses previously made by the creating thread are visible to us. 184b30aff405a220495941f1673b0a5e66c4fa8b84cElliott Hughes pthread_mutex_lock(&thread->startup_handshake_mutex); 185b30aff405a220495941f1673b0a5e66c4fa8b84cElliott Hughes pthread_mutex_destroy(&thread->startup_handshake_mutex); 186e48b68570d872ef7ece1d873c0ea298ea76393f3Elliott Hughes 187e48b68570d872ef7ece1d873c0ea298ea76393f3Elliott Hughes __init_alternate_signal_stack(thread); 188e48b68570d872ef7ece1d873c0ea298ea76393f3Elliott Hughes 189e48b68570d872ef7ece1d873c0ea298ea76393f3Elliott Hughes void* result = thread->start_routine(thread->start_routine_arg); 190e48b68570d872ef7ece1d873c0ea298ea76393f3Elliott Hughes pthread_exit(result); 191e48b68570d872ef7ece1d873c0ea298ea76393f3Elliott Hughes 192e48b68570d872ef7ece1d873c0ea298ea76393f3Elliott Hughes return 0; 193e48b68570d872ef7ece1d873c0ea298ea76393f3Elliott Hughes} 194e48b68570d872ef7ece1d873c0ea298ea76393f3Elliott Hughes 195cef3faec0ea40fdfe58e425fd0be64f00de6a26dElliott Hughes// A dummy start routine for pthread_create failures where we've created a thread but aren't 196cef3faec0ea40fdfe58e425fd0be64f00de6a26dElliott Hughes// going to run user code on it. We swap out the user's start routine for this and take advantage 197cef3faec0ea40fdfe58e425fd0be64f00de6a26dElliott Hughes// of the regular thread teardown to free up resources. 198cef3faec0ea40fdfe58e425fd0be64f00de6a26dElliott Hughesstatic void* __do_nothing(void*) { 199cef3faec0ea40fdfe58e425fd0be64f00de6a26dElliott Hughes return NULL; 200cef3faec0ea40fdfe58e425fd0be64f00de6a26dElliott Hughes} 201cef3faec0ea40fdfe58e425fd0be64f00de6a26dElliott Hughes 2024b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughesint pthread_create(pthread_t* thread_out, pthread_attr_t const* attr, 2034b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes void* (*start_routine)(void*), void* arg) { 2044b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes ErrnoRestorer errno_restorer; 2054b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes 206f2cea021ab2c6d7d7feeb40cca098aa132605876Elliott Hughes // Inform the rest of the C library that at least one thread was created. 2074b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes __isthreaded = 1; 2084b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes 2098cf1b305670123aed7638d984ca39bfd22388440Yabin Cui pthread_attr_t thread_attr; 2104b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes if (attr == NULL) { 2118cf1b305670123aed7638d984ca39bfd22388440Yabin Cui pthread_attr_init(&thread_attr); 2124b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes } else { 2138cf1b305670123aed7638d984ca39bfd22388440Yabin Cui thread_attr = *attr; 2144b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes attr = NULL; // Prevent misuse below. 2154b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes } 2164b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes 2178cf1b305670123aed7638d984ca39bfd22388440Yabin Cui pthread_internal_t* thread = NULL; 2188cf1b305670123aed7638d984ca39bfd22388440Yabin Cui void* child_stack = NULL; 2198cf1b305670123aed7638d984ca39bfd22388440Yabin Cui int result = __allocate_thread(&thread_attr, &thread, &child_stack); 2208cf1b305670123aed7638d984ca39bfd22388440Yabin Cui if (result != 0) { 2218cf1b305670123aed7638d984ca39bfd22388440Yabin Cui return result; 2224b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes } 2234b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes 22470b24b1cc2a1a4436b1fea3f8b76616fdcb27224Elliott Hughes // Create a mutex for the thread in TLS to wait on once it starts so we can keep 2254b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes // it from doing anything until after we notify the debugger about it 2264b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes // 2274b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes // This also provides the memory barrier we need to ensure that all 2284b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes // memory accesses previously performed by this thread are visible to 2294b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes // the new thread. 230b30aff405a220495941f1673b0a5e66c4fa8b84cElliott Hughes pthread_mutex_init(&thread->startup_handshake_mutex, NULL); 231b30aff405a220495941f1673b0a5e66c4fa8b84cElliott Hughes pthread_mutex_lock(&thread->startup_handshake_mutex); 2324b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes 23370b24b1cc2a1a4436b1fea3f8b76616fdcb27224Elliott Hughes thread->start_routine = start_routine; 23470b24b1cc2a1a4436b1fea3f8b76616fdcb27224Elliott Hughes thread->start_routine_arg = arg; 2354b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes 2367086ad6919feb2415c6027163f5c63323bcca27cElliott Hughes thread->set_cached_pid(getpid()); 2377086ad6919feb2415c6027163f5c63323bcca27cElliott Hughes 238877ec6d90418ff1d6597147d355a2229fdffae7eElliott Hughes int flags = CLONE_VM | CLONE_FS | CLONE_FILES | CLONE_SIGHAND | CLONE_THREAD | CLONE_SYSVSEM | 239877ec6d90418ff1d6597147d355a2229fdffae7eElliott Hughes CLONE_SETTLS | CLONE_PARENT_SETTID | CLONE_CHILD_CLEARTID; 2408cf1b305670123aed7638d984ca39bfd22388440Yabin Cui void* tls = reinterpret_cast<void*>(thread->tls); 24180906141f79be8be63fc915bfab467029b442ca1Elliott Hughes#if defined(__i386__) 24280906141f79be8be63fc915bfab467029b442ca1Elliott Hughes // On x86 (but not x86-64), CLONE_SETTLS takes a pointer to a struct user_desc rather than 2430d236aa3f1e6d31b0c729448ae9d3ed1cad23fb4Elliott Hughes // a pointer to the TLS itself. 2440d236aa3f1e6d31b0c729448ae9d3ed1cad23fb4Elliott Hughes user_desc tls_descriptor; 2450d236aa3f1e6d31b0c729448ae9d3ed1cad23fb4Elliott Hughes __init_user_desc(&tls_descriptor, false, tls); 2460d236aa3f1e6d31b0c729448ae9d3ed1cad23fb4Elliott Hughes tls = &tls_descriptor; 24780906141f79be8be63fc915bfab467029b442ca1Elliott Hughes#endif 2480d236aa3f1e6d31b0c729448ae9d3ed1cad23fb4Elliott Hughes int rc = clone(__pthread_start, child_stack, flags, thread, &(thread->tid), tls, &(thread->tid)); 249877ec6d90418ff1d6597147d355a2229fdffae7eElliott Hughes if (rc == -1) { 2504b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes int clone_errno = errno; 251877ec6d90418ff1d6597147d355a2229fdffae7eElliott Hughes // We don't have to unlock the mutex at all because clone(2) failed so there's no child waiting to 252877ec6d90418ff1d6597147d355a2229fdffae7eElliott Hughes // be unblocked, but we're about to unmap the memory the mutex is stored in, so this serves as a 253877ec6d90418ff1d6597147d355a2229fdffae7eElliott Hughes // reminder that you can't rewrite this function to use a ScopedPthreadMutexLocker. 254b30aff405a220495941f1673b0a5e66c4fa8b84cElliott Hughes pthread_mutex_unlock(&thread->startup_handshake_mutex); 255ba8dfc2669d658dc340eb8f9c9b40ca074f05047Yabin Cui if (thread->mmap_size != 0) { 256ba8dfc2669d658dc340eb8f9c9b40ca074f05047Yabin Cui munmap(thread->attr.stack_base, thread->mmap_size); 2574b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes } 258cfa089df23ff50fcd5ed3854c54991d30be5fc7eElliott Hughes __libc_format_log(ANDROID_LOG_WARN, "libc", "pthread_create failed: clone failed: %s", strerror(errno)); 2594b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes return clone_errno; 2604b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes } 2614b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes 262cef3faec0ea40fdfe58e425fd0be64f00de6a26dElliott Hughes int init_errno = __init_thread(thread, true); 2634b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes if (init_errno != 0) { 264cef3faec0ea40fdfe58e425fd0be64f00de6a26dElliott Hughes // Mark the thread detached and replace its start_routine with a no-op. 265cef3faec0ea40fdfe58e425fd0be64f00de6a26dElliott Hughes // Letting the thread run is the easiest way to clean up its resources. 2664b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes thread->attr.flags |= PTHREAD_ATTR_FLAG_DETACHED; 267cef3faec0ea40fdfe58e425fd0be64f00de6a26dElliott Hughes thread->start_routine = __do_nothing; 268b30aff405a220495941f1673b0a5e66c4fa8b84cElliott Hughes pthread_mutex_unlock(&thread->startup_handshake_mutex); 2694b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes return init_errno; 2704b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes } 2714b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes 272877ec6d90418ff1d6597147d355a2229fdffae7eElliott Hughes // Publish the pthread_t and unlock the mutex to let the new thread start running. 273877ec6d90418ff1d6597147d355a2229fdffae7eElliott Hughes *thread_out = reinterpret_cast<pthread_t>(thread); 274b30aff405a220495941f1673b0a5e66c4fa8b84cElliott Hughes pthread_mutex_unlock(&thread->startup_handshake_mutex); 2754b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes 2764b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes return 0; 2774b4a8824289c48c823cd38bc63289d121aae3d67Elliott Hughes} 278