1 /* 2 * Copyright (C) 2010 The Android Open Source Project 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * * Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * * Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in 12 * the documentation and/or other materials provided with the 13 * distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 16 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 17 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 18 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 19 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, 20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, 21 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS 22 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED 23 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, 24 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT 25 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26 * SUCH DAMAGE. 27 */ 28 29 #define _GNU_SOURCE 1 30 #include <sched.h> 31 #include <stdlib.h> 32 #include <stdarg.h> 33 34 #include "pthread_internal.h" 35 36 extern "C" pid_t __bionic_clone(uint32_t flags, void* child_stack, int* parent_tid, void* tls, int* child_tid, int (*fn)(void*), void* arg); 37 extern "C" __noreturn void __exit(int status); 38 39 // Called from the __bionic_clone assembler to call the thread function then exit. 40 extern "C" __LIBC_HIDDEN__ void __start_thread(int (*fn)(void*), void* arg) { 41 int status = (*fn)(arg); 42 __exit(status); 43 } 44 45 int clone(int (*fn)(void*), void* child_stack, int flags, void* arg, ...) { 46 int* parent_tid = NULL; 47 void* new_tls = NULL; 48 int* child_tid = NULL; 49 50 // Extract any optional parameters required by the flags. 51 va_list args; 52 va_start(args, arg); 53 if ((flags & (CLONE_PARENT_SETTID|CLONE_SETTLS|CLONE_CHILD_SETTID|CLONE_CHILD_CLEARTID)) != 0) { 54 parent_tid = va_arg(args, int*); 55 } 56 if ((flags & (CLONE_SETTLS|CLONE_CHILD_SETTID|CLONE_CHILD_CLEARTID)) != 0) { 57 new_tls = va_arg(args, void*); 58 } 59 if ((flags & (CLONE_CHILD_SETTID|CLONE_CHILD_CLEARTID)) != 0) { 60 child_tid = va_arg(args, int*); 61 } 62 va_end(args); 63 64 // Align 'child_stack' to 16 bytes. 65 uintptr_t child_stack_addr = reinterpret_cast<uintptr_t>(child_stack); 66 child_stack_addr &= ~0xf; 67 child_stack = reinterpret_cast<void*>(child_stack_addr); 68 69 // Remember the parent pid and invalidate the cached value while we clone. 70 pthread_internal_t* self = __get_thread(); 71 pid_t parent_pid = self->invalidate_cached_pid(); 72 73 // Actually do the clone. 74 int clone_result = __bionic_clone(flags, child_stack, parent_tid, new_tls, child_tid, fn, arg); 75 76 // We're the parent, so put our known pid back in place. 77 // We leave the child without a cached pid, but: 78 // 1. pthread_create gives its children their own pthread_internal_t with the correct pid. 79 // 2. fork makes a clone system call directly. 80 // If any other cases become important, we could use a double trampoline like __pthread_start. 81 self->set_cached_pid(parent_pid); 82 return clone_result; 83 } 84
