/* * Copyright (C) 2008 The Android Open Source Project * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * * Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * * Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in * the documentation and/or other materials provided with the * distribution. * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. */ #include #include #include #include "pthread_internal.h" #include "private/bionic_ssp.h" #include "private/bionic_tls.h" #include "private/libc_logging.h" #include "private/thread_private.h" #include "private/ErrnoRestorer.h" #include "private/ScopedPthreadMutexLocker.h" extern "C" int __pthread_clone(void* (*fn)(void*), void* child_stack, int flags, void* arg); #ifdef __i386__ #define ATTRIBUTES __attribute__((noinline)) __attribute__((fastcall)) #else #define ATTRIBUTES __attribute__((noinline)) #endif extern "C" void ATTRIBUTES _thread_created_hook(pid_t thread_id); static const int kPthreadInitFailed = 1; static pthread_mutex_t gPthreadStackCreationLock = PTHREAD_MUTEX_INITIALIZER; static pthread_mutex_t gDebuggerNotificationLock = PTHREAD_MUTEX_INITIALIZER; void __init_tls(pthread_internal_t* thread) { // Zero-initialize all the slots. for (size_t i = 0; i < BIONIC_TLS_SLOTS; ++i) { thread->tls[i] = NULL; } // Slot 0 must point to itself. The x86 Linux kernel reads the TLS from %fs:0. thread->tls[TLS_SLOT_SELF] = thread->tls; thread->tls[TLS_SLOT_THREAD_ID] = thread; // GCC looks in the TLS for the stack guard on x86, so copy it there from our global. thread->tls[TLS_SLOT_STACK_GUARD] = (void*) __stack_chk_guard; __set_tls(thread->tls); } // This trampoline is called from the assembly _pthread_clone() function. extern "C" void __thread_entry(void* (*func)(void*), void* arg, void** tls) { // Wait for our creating thread to release us. This lets it have time to // notify gdb about this thread before we start doing anything. // This also provides the memory barrier needed to ensure that all memory // accesses previously made by the creating thread are visible to us. pthread_mutex_t* start_mutex = (pthread_mutex_t*) &tls[TLS_SLOT_SELF]; pthread_mutex_lock(start_mutex); pthread_mutex_destroy(start_mutex); pthread_internal_t* thread = (pthread_internal_t*) tls[TLS_SLOT_THREAD_ID]; thread->tls = tls; __init_tls(thread); if ((thread->internal_flags & kPthreadInitFailed) != 0) { pthread_exit(NULL); } void* result = func(arg); pthread_exit(result); } __LIBC_ABI_PRIVATE__ int _init_thread(pthread_internal_t* thread, bool add_to_thread_list) { int error = 0; // Set the scheduling policy/priority of the thread. if (thread->attr.sched_policy != SCHED_NORMAL) { struct sched_param param; param.sched_priority = thread->attr.sched_priority; if (sched_setscheduler(thread->tid, thread->attr.sched_policy, ¶m) == -1) { // For backwards compatibility reasons, we just warn about failures here. // error = errno; __libc_format_log(ANDROID_LOG_WARN, "libc", "pthread_create sched_setscheduler call failed: %s", strerror(errno)); } } pthread_cond_init(&thread->join_cond, NULL); thread->cleanup_stack = NULL; if (add_to_thread_list) { _pthread_internal_add(thread); } return error; } static void* __create_thread_stack(pthread_internal_t* thread) { ScopedPthreadMutexLocker lock(&gPthreadStackCreationLock); // Create a new private anonymous map. int prot = PROT_READ | PROT_WRITE; int flags = MAP_PRIVATE | MAP_ANONYMOUS | MAP_NORESERVE; void* stack = mmap(NULL, thread->attr.stack_size, prot, flags, -1, 0); if (stack == MAP_FAILED) { __libc_format_log(ANDROID_LOG_WARN, "libc", "pthread_create failed: couldn't allocate %zd-byte stack: %s", thread->attr.stack_size, strerror(errno)); return NULL; } // Set the guard region at the end of the stack to PROT_NONE. if (mprotect(stack, thread->attr.guard_size, PROT_NONE) == -1) { __libc_format_log(ANDROID_LOG_WARN, "libc", "pthread_create failed: couldn't mprotect PROT_NONE %zd-byte stack guard region: %s", thread->attr.guard_size, strerror(errno)); munmap(stack, thread->attr.stack_size); return NULL; } return stack; } int pthread_create(pthread_t* thread_out, pthread_attr_t const* attr, void* (*start_routine)(void*), void* arg) { ErrnoRestorer errno_restorer; // Inform the rest of the C library that at least one thread // was created. This will enforce certain functions to acquire/release // locks (e.g. atexit()) to protect shared global structures. // This works because pthread_create() is not called by the C library // initialization routine that sets up the main thread's data structures. __isthreaded = 1; pthread_internal_t* thread = reinterpret_cast(calloc(sizeof(*thread), 1)); if (thread == NULL) { __libc_format_log(ANDROID_LOG_WARN, "libc", "pthread_create failed: couldn't allocate thread"); return EAGAIN; } thread->allocated_on_heap = true; if (attr == NULL) { pthread_attr_init(&thread->attr); } else { thread->attr = *attr; attr = NULL; // Prevent misuse below. } // Make sure the stack size and guard size are multiples of PAGE_SIZE. thread->attr.stack_size = (thread->attr.stack_size + (PAGE_SIZE-1)) & ~(PAGE_SIZE-1); thread->attr.guard_size = (thread->attr.guard_size + (PAGE_SIZE-1)) & ~(PAGE_SIZE-1); if (thread->attr.stack_base == NULL) { // The caller didn't provide a stack, so allocate one. thread->attr.stack_base = __create_thread_stack(thread); if (thread->attr.stack_base == NULL) { free(thread); return EAGAIN; } } else { // The caller did provide a stack, so remember we're not supposed to free it. thread->attr.flags |= PTHREAD_ATTR_FLAG_USER_STACK; } // Make room for TLS. void** tls = (void**)((uint8_t*)(thread->attr.stack_base) + thread->attr.stack_size - BIONIC_TLS_SLOTS * sizeof(void*)); // Create a mutex for the thread in TLS_SLOT_SELF to wait on once it starts so we can keep // it from doing anything until after we notify the debugger about it // // This also provides the memory barrier we need to ensure that all // memory accesses previously performed by this thread are visible to // the new thread. pthread_mutex_t* start_mutex = (pthread_mutex_t*) &tls[TLS_SLOT_SELF]; pthread_mutex_init(start_mutex, NULL); ScopedPthreadMutexLocker start_locker(start_mutex); tls[TLS_SLOT_THREAD_ID] = thread; int flags = CLONE_FILES | CLONE_FS | CLONE_VM | CLONE_SIGHAND | CLONE_THREAD | CLONE_SYSVSEM; int tid = __pthread_clone(start_routine, tls, flags, arg); if (tid < 0) { int clone_errno = errno; if ((thread->attr.flags & PTHREAD_ATTR_FLAG_USER_STACK) == 0) { munmap(thread->attr.stack_base, thread->attr.stack_size); } free(thread); __libc_format_log(ANDROID_LOG_WARN, "libc", "pthread_create failed: clone failed: %s", strerror(errno)); return clone_errno; } thread->tid = tid; int init_errno = _init_thread(thread, true); if (init_errno != 0) { // Mark the thread detached and let its __thread_entry run to // completion. (It'll just exit immediately, cleaning up its resources.) thread->internal_flags |= kPthreadInitFailed; thread->attr.flags |= PTHREAD_ATTR_FLAG_DETACHED; return init_errno; } // Notify any debuggers about the new thread. { ScopedPthreadMutexLocker debugger_locker(&gDebuggerNotificationLock); _thread_created_hook(thread->tid); } // Publish the pthread_t and let the thread run. *thread_out = (pthread_t) thread; return 0; }