2 #include "pthread_impl.h"
3 #include "stdio_impl.h"
9 void *__mmap(void *, size_t, int, int, int, off_t);
10 int __munmap(void *, size_t);
11 int __mprotect(void *, size_t, int);
16 weak_alias(dummy_0, __acquire_ptc);
17 weak_alias(dummy_0, __release_ptc);
18 weak_alias(dummy_0, __pthread_tsd_run_dtors);
19 weak_alias(dummy_0, __do_orphaned_stdio_locks);
20 weak_alias(dummy_0, __dl_thread_cleanup);
22 _Noreturn void __pthread_exit(void *result)
24 pthread_t self = __pthread_self();
27 self->canceldisable = 1;
28 self->cancelasync = 0;
29 self->result = result;
31 while (self->cancelbuf) {
32 void (*f)(void *) = self->cancelbuf->__f;
33 void *x = self->cancelbuf->__x;
34 self->cancelbuf = self->cancelbuf->__next;
38 __pthread_tsd_run_dtors();
40 __lock(self->exitlock);
42 /* Mark this thread dead before decrementing count */
43 __lock(self->killlock);
46 /* Block all signals before decrementing the live thread count.
47 * This is important to ensure that dynamically allocated TLS
48 * is not under-allocated/over-committed, and possibly for other
50 __block_all_sigs(&set);
52 /* Wait to unlock the kill lock, which governs functions like
53 * pthread_kill which target a thread id, until signals have
54 * been blocked. This precludes observation of the thread id
55 * as a live thread (with application code running in it) after
56 * the thread was reported dead by ESRCH being returned. */
57 __unlock(self->killlock);
59 /* It's impossible to determine whether this is "the last thread"
60 * until performing the atomic decrement, since multiple threads
61 * could exit at the same time. For the last thread, revert the
62 * decrement and unblock signals to give the atexit handlers and
63 * stdio cleanup code a consistent state. */
64 if (a_fetch_add(&libc.threads_minus_1, -1)==0) {
65 libc.threads_minus_1 = 0;
70 /* Process robust list in userspace to handle non-pshared mutexes
71 * and the detached thread case where the robust list head will
72 * be invalid when the kernel would process it. */
74 volatile void *volatile *rp;
75 while ((rp=self->robust_list.head) && rp != &self->robust_list.head) {
76 pthread_mutex_t *m = (void *)((char *)rp
77 - offsetof(pthread_mutex_t, _m_next));
78 int waiters = m->_m_waiters;
79 int priv = (m->_m_type & 128) ^ 128;
80 self->robust_list.pending = rp;
81 self->robust_list.head = *rp;
82 int cont = a_swap(&m->_m_lock, 0x40000000);
83 self->robust_list.pending = 0;
84 if (cont < 0 || waiters)
85 __wake(&m->_m_lock, 1, priv);
89 __do_orphaned_stdio_locks();
90 __dl_thread_cleanup();
92 if (self->detached && self->map_base) {
93 /* Detached threads must avoid the kernel clear_child_tid
94 * feature, since the virtual address will have been
95 * unmapped and possibly already reused by a new mapping
96 * at the time the kernel would perform the write. In
97 * the case of threads that started out detached, the
98 * initial clone flags are correct, but if the thread was
99 * detached later (== 2), we need to clear it here. */
100 if (self->detached == 2) __syscall(SYS_set_tid_address, 0);
102 /* Robust list will no longer be valid, and was already
103 * processed above, so unregister it with the kernel. */
104 if (self->robust_list.off)
105 __syscall(SYS_set_robust_list, 0, 3*sizeof(long));
107 /* Since __unmapself bypasses the normal munmap code path,
108 * explicitly wait for vmlock holders first. */
111 /* The following call unmaps the thread's stack mapping
112 * and then exits without touching the stack. */
113 __unmapself(self->map_base, self->map_size);
116 for (;;) __syscall(SYS_exit, 0);
119 void __do_cleanup_push(struct __ptcb *cb)
121 struct pthread *self = __pthread_self();
122 cb->__next = self->cancelbuf;
123 self->cancelbuf = cb;
126 void __do_cleanup_pop(struct __ptcb *cb)
128 __pthread_self()->cancelbuf = cb->__next;
131 static int start(void *p)
134 if (self->startlock[0]) {
135 __wait(self->startlock, 0, 1, 1);
136 if (self->startlock[0]) {
140 __restore_sigs(self->sigmask);
142 if (self->unblock_cancel)
143 __syscall(SYS_rt_sigprocmask, SIG_UNBLOCK,
144 SIGPT_SET, 0, _NSIG/8);
145 __pthread_exit(self->start(self->start_arg));
149 static int start_c11(void *p)
152 int (*start)(void*) = (int(*)(void*)) self->start;
153 __pthread_exit((void *)(uintptr_t)start(self->start_arg));
157 #define ROUND(x) (((x)+PAGE_SIZE-1)&-PAGE_SIZE)
159 /* pthread_key_create.c overrides this */
160 static volatile size_t dummy = 0;
161 weak_alias(dummy, __pthread_tsd_size);
162 static void *dummy_tsd[1] = { 0 };
163 weak_alias(dummy_tsd, __pthread_tsd_main);
165 volatile int __block_new_threads = 0;
166 size_t __default_stacksize = DEFAULT_STACK_SIZE;
167 size_t __default_guardsize = DEFAULT_GUARD_SIZE;
169 static FILE *volatile dummy_file = 0;
170 weak_alias(dummy_file, __stdin_used);
171 weak_alias(dummy_file, __stdout_used);
172 weak_alias(dummy_file, __stderr_used);
174 static void init_file_lock(FILE *f)
176 if (f && f->lock<0) f->lock = 0;
179 void *__copy_tls(unsigned char *);
181 int __pthread_create(pthread_t *restrict res, const pthread_attr_t *restrict attrp, void *(*entry)(void *), void *restrict arg)
183 int ret, c11 = (attrp == __ATTRP_C11_THREAD);
185 struct pthread *self, *new;
186 unsigned char *map = 0, *stack = 0, *tsd = 0, *stack_limit;
187 unsigned flags = CLONE_VM | CLONE_FS | CLONE_FILES | CLONE_SIGHAND
188 | CLONE_THREAD | CLONE_SYSVSEM | CLONE_SETTLS
189 | CLONE_PARENT_SETTID | CLONE_CHILD_CLEARTID | CLONE_DETACHED;
191 pthread_attr_t attr = { 0 };
193 if (!libc.can_do_threads) return ENOSYS;
194 self = __pthread_self();
195 if (!libc.threaded) {
196 for (FILE *f=*__ofl_lock(); f; f=f->next)
199 init_file_lock(__stdin_used);
200 init_file_lock(__stdout_used);
201 init_file_lock(__stderr_used);
202 __syscall(SYS_rt_sigprocmask, SIG_UNBLOCK, SIGPT_SET, 0, _NSIG/8);
203 self->tsd = (void **)__pthread_tsd_main;
206 if (attrp && !c11) attr = *attrp;
210 attr._a_stacksize = __default_stacksize;
211 attr._a_guardsize = __default_guardsize;
214 if (__block_new_threads) __wait(&__block_new_threads, 0, 1, 1);
216 if (attr._a_stackaddr) {
217 size_t need = libc.tls_size + __pthread_tsd_size;
218 size = attr._a_stacksize;
219 stack = (void *)(attr._a_stackaddr & -16);
220 stack_limit = (void *)(attr._a_stackaddr - size);
221 /* Use application-provided stack for TLS only when
222 * it does not take more than ~12% or 2k of the
223 * application's stack space. */
224 if (need < size/8 && need < 2048) {
225 tsd = stack - __pthread_tsd_size;
226 stack = tsd - libc.tls_size;
227 memset(stack, 0, need);
233 guard = ROUND(attr._a_guardsize);
234 size = guard + ROUND(attr._a_stacksize
235 + libc.tls_size + __pthread_tsd_size);
240 map = __mmap(0, size, PROT_NONE, MAP_PRIVATE|MAP_ANON, -1, 0);
241 if (map == MAP_FAILED) goto fail;
242 if (__mprotect(map+guard, size-guard, PROT_READ|PROT_WRITE)
243 && errno != ENOSYS) {
248 map = __mmap(0, size, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANON, -1, 0);
249 if (map == MAP_FAILED) goto fail;
251 tsd = map + size - __pthread_tsd_size;
253 stack = tsd - libc.tls_size;
254 stack_limit = map + guard;
258 new = __copy_tls(tsd - libc.tls_size);
260 new->map_size = size;
262 new->stack_size = stack - stack_limit;
264 new->start_arg = arg;
266 new->tsd = (void *)tsd;
267 new->locale = &libc.global_locale;
268 if (attr._a_detach) {
270 flags -= CLONE_CHILD_CLEARTID;
273 do_sched = new->startlock[0] = 1;
274 __block_app_sigs(new->sigmask);
276 new->robust_list.head = &new->robust_list.head;
277 new->unblock_cancel = self->cancel;
278 new->CANARY = self->CANARY;
280 a_inc(&libc.threads_minus_1);
281 ret = __clone((c11 ? start_c11 : start), stack, flags, new, &new->tid, TP_ADJ(new), &new->tid);
286 __restore_sigs(new->sigmask);
290 a_dec(&libc.threads_minus_1);
291 if (map) __munmap(map, size);
296 ret = __syscall(SYS_sched_setscheduler, new->tid,
297 attr._a_policy, &attr._a_prio);
298 a_store(new->startlock, ret<0 ? 2 : 0);
299 __wake(new->startlock, 1, 1);
300 if (ret < 0) return -ret;
310 weak_alias(__pthread_exit, pthread_exit);
311 weak_alias(__pthread_create, pthread_create);