int gtthread_create(gtthread_t *thread, gtthread_attr_t const * attr,
void *(*start_routine)(void *), void * arg)
{
//allocate memory for the thread and initialize to 0
gtthread_t* gt_thread = calloc(sizeof(*gt_thread),1);
if(gt_thread==NULL){
return -1;
}
//check the thread attribute object
if(attr==NULL){
*attr = default_gtthread_attr;
}
//create or retrieve a new stack for the thread if NULL
size_t stack_size = attr->stack_size;
uint8_t stack_base = attr->stack_base;
if(stack_base==NULL){
stack_base = malloc(stack_size);
if(stack_base==NULL){ //check for unsuccessful malloc
return -1;
}
}
stack_base = stack_base + stack_size;
int flags = CLONE_FILES | CLONE_FS | CLONE_VM | CLONE_SIGHAND |
CLONE_THREAD | CLONE_SYSVSEM | CLONE_DETACHED;
int tid = __pthread_clone((int(*)(void*))start_routine, stack_base, flags, arg);
if(tid<0){ //check for unsuccessful clone
return -1;
}
int init_errno = _init_thread(thread, tid, (pthread_attr_t*) attr, stack_base, 1);
return 0;
}
void __libc_init_common(uintptr_t *elfdata)
{
int argc = *elfdata;
char** argv = (char**)(elfdata + 1);
char** envp = argv + argc + 1;
pthread_attr_t thread_attr;
static pthread_internal_t thread;
static void* tls_area[BIONIC_TLS_SLOTS];
/* setup pthread runtime and maint thread descriptor */
unsigned stacktop = (__get_sp() & ~(PAGE_SIZE - 1)) + PAGE_SIZE;
unsigned stacksize = 128 * 1024;
unsigned stackbottom = stacktop - stacksize;
pthread_attr_init(&thread_attr);
pthread_attr_setstack(&thread_attr, (void*)stackbottom, stacksize);
_init_thread(&thread, gettid(), &thread_attr, (void*)stackbottom);
__init_tls(tls_area, &thread);
/* clear errno - requires TLS area */
errno = 0;
/* set program name */
__progname = argv[0] ? argv[0] : "<unknown>";
/* setup environment pointer */
environ = envp;
/* setup system properties - requires environment */
__system_properties_init();
}
/* Init TLS for the initial thread. Called by the linker _before_ libc is mapped
* in memory. Beware: all writes to libc globals from this function will
* apply to linker-private copies and will not be visible from libc later on.
*
* Note: this function creates a pthread_internal_t for the initial thread and
* stores the pointer in TLS, but does not add it to pthread's gThreadList. This
* has to be done later from libc itself (see __libc_init_common).
*
* This function also stores the elf_data argument in a specific TLS slot to be later
* picked up by the libc constructor.
*/
void __libc_init_tls(unsigned** elf_data) {
unsigned stack_top = (__get_sp() & ~(PAGE_SIZE - 1)) + PAGE_SIZE;
unsigned stack_size = 128 * 1024;
unsigned stack_bottom = stack_top - stack_size;
pthread_attr_t thread_attr;
pthread_attr_init(&thread_attr);
pthread_attr_setstack(&thread_attr, (void*) stack_bottom, stack_size);
static pthread_internal_t thread;
_init_thread(&thread, gettid(), &thread_attr, (void*) stack_bottom, false);
static void* tls_area[BIONIC_TLS_SLOTS];
__init_tls(tls_area, &thread);
tls_area[TLS_SLOT_BIONIC_PREINIT] = elf_data;
}
/* Init TLS for the initial thread. Called by the linker _before_ libc is mapped
* in memory. Beware: all writes to libc globals from this function will
* apply to linker-private copies and will not be visible from libc later on.
*
* Note: this function creates a pthread_internal_t for the initial thread and
* stores the pointer in TLS, but does not add it to pthread's gThreadList. This
* has to be done later from libc itself (see __libc_init_common).
*
* This function also stores a pointer to the kernel argument block in a TLS slot to be
* picked up by the libc constructor.
*/
void __libc_init_tls(KernelArgumentBlock& args) {
__libc_auxv = args.auxv;
uintptr_t stack_top = (__get_sp() & ~(PAGE_SIZE - 1)) + PAGE_SIZE;
size_t stack_size = get_main_thread_stack_size();
uintptr_t stack_bottom = stack_top - stack_size;
static void* tls[BIONIC_TLS_SLOTS];
static pthread_internal_t thread;
thread.tid = gettid();
thread.tls = tls;
pthread_attr_init(&thread.attr);
pthread_attr_setstack(&thread.attr, (void*) stack_bottom, stack_size);
_init_thread(&thread, false);
__init_tls(&thread);
tls[TLS_SLOT_BIONIC_PREINIT] = &args;
}
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<pthread_internal_t*>(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 is PAGE_SIZE aligned.
size_t stack_size = (thread->attr.stack_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(stack_size, thread->attr.guard_size);
if (thread->attr.stack_base == NULL) {
free(thread);
__libc_format_log(ANDROID_LOG_WARN, "libc", "pthread_create failed: couldn't allocate %zd-byte stack", stack_size);
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) + 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, 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;
}
