#define _GNU_SOURCE
#include "pthread_impl.h"
#include "stdio_impl.h"
#include "libc.h"
#include <sys/mman.h>
#include <string.h>
#include <stddef.h>
void *__mmap(void *, size_t, int, int, int, off_t);
int __munmap(void *, size_t);
int __mprotect(void *, size_t, int);
static void dummy_0()
{
}
weak_alias(dummy_0, __acquire_ptc);
weak_alias(dummy_0, __release_ptc);
weak_alias(dummy_0, __pthread_tsd_run_dtors);
weak_alias(dummy_0, __do_orphaned_stdio_locks);
weak_alias(dummy_0, __dl_thread_cleanup);
_Noreturn void __pthread_exit(void *result)
{
pthread_t self = __pthread_self();
sigset_t set;
self->canceldisable = 1;
self->cancelasync = 0;
self->result = result;
while (self->cancelbuf) {
void (*f)(void *) = self->cancelbuf->__f;
void *x = self->cancelbuf->__x;
self->cancelbuf = self->cancelbuf->__next;
f(x);
}
__pthread_tsd_run_dtors();
__lock(self->exitlock);
/* Mark this thread dead before decrementing count */
__lock(self->killlock);
self->dead = 1;
/* Block all signals before decrementing the live thread count.
* This is important to ensure that dynamically allocated TLS
* is not under-allocated/over-committed, and possibly for other
* reasons as well. */
__block_all_sigs(&set);
/* Wait to unlock the kill lock, which governs functions like
* pthread_kill which target a thread id, until signals have
* been blocked. This precludes observation of the thread id
* as a live thread (with application code running in it) after
* the thread was reported dead by ESRCH being returned. */
__unlock(self->killlock);
/* It's impossible to determine whether this is "the last thread"
* until performing the atomic decrement, since multiple threads
* could exit at the same time. For the last thread, revert the
* decrement and unblock signals to give the atexit handlers and
* stdio cleanup code a consistent state. */
if (a_fetch_add(&libc.threads_minus_1, -1)==0) {
libc.threads_minus_1 = 0;
__restore_sigs(&set);
exit(0);
}
/* Process robust list in userspace to handle non-pshared mutexes
* and the detached thread case where the robust list head will
* be invalid when the kernel would process it. */
__vm_lock();
volatile void *volatile *rp;
while ((rp=self->robust_list.head) && rp != &self->robust_list.head) {
pthread_mutex_t *m = (void *)((char *)rp
- offsetof(pthread_mutex_t, _m_next));
int waiters = m->_m_waiters;
int priv = (m->_m_type & 128) ^ 128;
self->robust_list.pending = rp;
self->robust_list.head = *rp;
int cont = a_swap(&m->_m_lock, self->tid|0x40000000);
self->robust_list.pending = 0;
if (cont < 0 || waiters)
__wake(&m->_m_lock, 1, priv);
}
__vm_unlock();
__do_orphaned_stdio_locks();
__dl_thread_cleanup();
if (self->detached && self->map_base) {
/* Detached threads must avoid the kernel clear_child_tid
* feature, since the virtual address will have been
* unmapped and possibly already reused by a new mapping
* at the time the kernel would perform the write. In
* the case of threads that started out detached, the
* initial clone flags are correct, but if the thread was
* detached later (== 2), we need to clear it here. */
if (self->detached == 2) __syscall(SYS_set_tid_address, 0);
/* Robust list will no longer be valid, and was already
* processed above, so unregister it with the kernel. */
if (self->robust_list.off)
__syscall(SYS_set_robust_list, 0, 3*sizeof(long));
/* Since __unmapself bypasses the normal munmap code path,
* explicitly wait for vmlock holders first. */
__vm_wait();
/* The following call unmaps the thread's stack mapping
* and then exits without touching the stack. */
__unmapself(self->map_base, self->map_size);
}
for (;;) __syscall(SYS_exit, 0);
}
void __do_cleanup_push(struct __ptcb *cb)
{
struct pthread *self = __pthread_self();
cb->__next = self->cancelbuf;
self->cancelbuf = cb;
}
void __do_cleanup_pop(struct __ptcb *cb)
{
__pthread_self()->cancelbuf = cb->__next;
}
static int start(void *p)
{
pthread_t self = p;
if (self->startlock[0]) {
__wait(self->startlock, 0, 1, 1);
if (self->startlock[0]) {
self->detached = 2;
pthread_exit(0);
}
__restore_sigs(self->sigmask);
}
if (self->unblock_cancel)
__syscall(SYS_rt_sigprocmask, SIG_UNBLOCK,
SIGPT_SET, 0, _NSIG/8);
__pthread_exit(self->start(self->start_arg));
return 0;
}
static int start_c11(void *p)
{
pthread_t self = p;
int (*start)(void*) = (int(*)(void*)) self->start;
__pthread_exit((void *)(uintptr_t)start(self->start_arg));
return 0;
}
#define ROUND(x) (((x)+PAGE_SIZE-1)&-PAGE_SIZE)
/* pthread_key_create.c overrides this */
static volatile size_t dummy = 0;
weak_alias(dummy, __pthread_tsd_size);
static void *dummy_tsd[1] = { 0 };
weak_alias(dummy_tsd, __pthread_tsd_main);
volatile int __block_new_threads = 0;
static FILE *volatile dummy_file = 0;
weak_alias(dummy_file, __stdin_used);
weak_alias(dummy_file, __stdout_used);
weak_alias(dummy_file, __stderr_used);
static void init_file_lock(FILE *f)
{
if (f && f->lock<0) f->lock = 0;
}
void *__copy_tls(unsigned char *);
int __pthread_create(pthread_t *restrict res, const pthread_attr_t *restrict attrp, void *(*entry)(void *), void *restrict arg)
{
int ret, c11 = (attrp == __ATTRP_C11_THREAD);
size_t size, guard;
struct pthread *self, *new;
unsigned char *map = 0, *stack = 0, *tsd = 0, *stack_limit;
unsigned flags = CLONE_VM | CLONE_FS | CLONE_FILES | CLONE_SIGHAND
| CLONE_THREAD | CLONE_SYSVSEM | CLONE_SETTLS
| CLONE_PARENT_SETTID | CLONE_CHILD_CLEARTID | CLONE_DETACHED;
int do_sched = 0;
pthread_attr_t attr = {0};
if (!libc.can_do_threads) return ENOSYS;
self = __pthread_self();
if (!libc.threaded) {
for (FILE *f=*__ofl_lock(); f; f=f->next)
init_file_lock(f);
__ofl_unlock();
init_file_lock(__stdin_used);
init_file_lock(__stdout_used);
init_file_lock(__stderr_used);
__syscall(SYS_rt_sigprocmask, SIG_UNBLOCK, SIGPT_SET, 0, _NSIG/8);
self->tsd = (void **)__pthread_tsd_main;
libc.threaded = 1;
}
if (attrp && !c11) attr = *attrp;
__acquire_ptc();
if (__block_new_threads) __wait(&__block_new_threads, 0, 1, 1);
if (attr._a_stackaddr) {
size_t need = libc.tls_size + __pthread_tsd_size;
size = attr._a_stacksize + DEFAULT_STACK_SIZE;
stack = (void *)(attr._a_stackaddr & -16);
stack_limit = (void *)(attr._a_stackaddr - size);
/* Use application-provided stack for TLS only when
* it does not take more than ~12% or 2k of the
* application's stack space. */
if (need < size/8 && need < 2048) {
tsd = stack - __pthread_tsd_size;
stack = tsd - libc.tls_size;
memset(stack, 0, need);
} else {
size = ROUND(need);
guard = 0;
}
} else {
guard = ROUND(DEFAULT_GUARD_SIZE + attr._a_guardsize);
size = guard + ROUND(DEFAULT_STACK_SIZE + attr._a_stacksize
+ libc.tls_size + __pthread_tsd_size);
}
if (!tsd) {
if (guard) {
map = __mmap(0, size, PROT_NONE, MAP_PRIVATE|MAP_ANON, -1, 0);
if (map == MAP_FAILED) goto fail;
if (__mprotect(map+guard, size-guard, PROT_READ|PROT_WRITE)
&& errno != ENOSYS) {
__munmap(map, size);
goto fail;
}
} else {
map = __mmap(0, size, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANON, -1, 0);
if (map == MAP_FAILED) goto fail;
}
tsd = map + size - __pthread_tsd_size;
if (!stack) {
stack = tsd - libc.tls_size;
stack_limit = map + guard;
}
}
new = __copy_tls(tsd - libc.tls_size);
new->map_base = map;
new->map_size = size;
new->stack = stack;
new->stack_size = stack - stack_limit;
new->start = entry;
new->start_arg = arg;
new->self = new;
new->tsd = (void *)tsd;
new->locale = &libc.global_locale;
if (attr._a_detach) {
new->detached = 1;
flags -= CLONE_CHILD_CLEARTID;
}
if (attr._a_sched) {
do_sched = new->startlock[0] = 1;
__block_app_sigs(new->sigmask);
}
new->robust_list.head = &new->robust_list.head;
new->unblock_cancel = self->cancel;
new->CANARY = self->CANARY;
a_inc(&libc.threads_minus_1);
ret = __clone((c11 ? start_c11 : start), stack, flags, new, &new->tid, TP_ADJ(new), &new->tid);
__release_ptc();
if (do_sched) {
__restore_sigs(new->sigmask);
}
if (ret < 0) {
a_dec(&libc.threads_minus_1);
if (map) __munmap(map, size);
return EAGAIN;
}
if (do_sched) {
ret = __syscall(SYS_sched_setscheduler, new->tid,
attr._a_policy, &attr._a_prio);
a_store(new->startlock, ret<0 ? 2 : 0);
__wake(new->startlock, 1, 1);
if (ret < 0) return -ret;
}
*res = new;
return 0;
fail:
__release_ptc();
return EAGAIN;
}
weak_alias(__pthread_exit, pthread_exit);
weak_alias(__pthread_create, pthread_create);
