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 /* States for startlock:
135 * 0 = no need for start sync
136 * 1 = waiting for parent to do work
137 * 2 = failure in parent, child must abort
138 * 3 = success in parent, child must restore sigmask */
139 if (self->startlock[0]) {
140 __wait(self->startlock, 0, 1, 1);
141 if (self->startlock[0] == 2) {
145 __restore_sigs(self->sigmask);
147 if (self->unblock_cancel)
148 __syscall(SYS_rt_sigprocmask, SIG_UNBLOCK,
149 SIGPT_SET, 0, _NSIG/8);
150 __pthread_exit(self->start(self->start_arg));
154 static int start_c11(void *p)
157 int (*start)(void*) = (int(*)(void*)) self->start;
158 __pthread_exit((void *)(uintptr_t)start(self->start_arg));
162 #define ROUND(x) (((x)+PAGE_SIZE-1)&-PAGE_SIZE)
164 /* pthread_key_create.c overrides this */
165 static volatile size_t dummy = 0;
166 weak_alias(dummy, __pthread_tsd_size);
167 static void *dummy_tsd[1] = { 0 };
168 weak_alias(dummy_tsd, __pthread_tsd_main);
170 volatile int __block_new_threads = 0;
171 size_t __default_stacksize = DEFAULT_STACK_SIZE;
172 size_t __default_guardsize = DEFAULT_GUARD_SIZE;
174 static FILE *volatile dummy_file = 0;
175 weak_alias(dummy_file, __stdin_used);
176 weak_alias(dummy_file, __stdout_used);
177 weak_alias(dummy_file, __stderr_used);
179 static void init_file_lock(FILE *f)
181 if (f && f->lock<0) f->lock = 0;
184 void *__copy_tls(unsigned char *);
186 int __pthread_create(pthread_t *restrict res, const pthread_attr_t *restrict attrp, void *(*entry)(void *), void *restrict arg)
188 int ret, c11 = (attrp == __ATTRP_C11_THREAD);
190 struct pthread *self, *new;
191 unsigned char *map = 0, *stack = 0, *tsd = 0, *stack_limit;
192 unsigned flags = CLONE_VM | CLONE_FS | CLONE_FILES | CLONE_SIGHAND
193 | CLONE_THREAD | CLONE_SYSVSEM | CLONE_SETTLS
194 | CLONE_PARENT_SETTID | CLONE_CHILD_CLEARTID | CLONE_DETACHED;
196 pthread_attr_t attr = { 0 };
198 if (!libc.can_do_threads) return ENOSYS;
199 self = __pthread_self();
200 if (!libc.threaded) {
201 for (FILE *f=*__ofl_lock(); f; f=f->next)
204 init_file_lock(__stdin_used);
205 init_file_lock(__stdout_used);
206 init_file_lock(__stderr_used);
207 __syscall(SYS_rt_sigprocmask, SIG_UNBLOCK, SIGPT_SET, 0, _NSIG/8);
208 self->tsd = (void **)__pthread_tsd_main;
211 if (attrp && !c11) attr = *attrp;
215 attr._a_stacksize = __default_stacksize;
216 attr._a_guardsize = __default_guardsize;
219 if (__block_new_threads) __wait(&__block_new_threads, 0, 1, 1);
221 if (attr._a_stackaddr) {
222 size_t need = libc.tls_size + __pthread_tsd_size;
223 size = attr._a_stacksize;
224 stack = (void *)(attr._a_stackaddr & -16);
225 stack_limit = (void *)(attr._a_stackaddr - size);
226 /* Use application-provided stack for TLS only when
227 * it does not take more than ~12% or 2k of the
228 * application's stack space. */
229 if (need < size/8 && need < 2048) {
230 tsd = stack - __pthread_tsd_size;
231 stack = tsd - libc.tls_size;
232 memset(stack, 0, need);
238 guard = ROUND(attr._a_guardsize);
239 size = guard + ROUND(attr._a_stacksize
240 + libc.tls_size + __pthread_tsd_size);
245 map = __mmap(0, size, PROT_NONE, MAP_PRIVATE|MAP_ANON, -1, 0);
246 if (map == MAP_FAILED) goto fail;
247 if (__mprotect(map+guard, size-guard, PROT_READ|PROT_WRITE)
248 && errno != ENOSYS) {
253 map = __mmap(0, size, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANON, -1, 0);
254 if (map == MAP_FAILED) goto fail;
256 tsd = map + size - __pthread_tsd_size;
258 stack = tsd - libc.tls_size;
259 stack_limit = map + guard;
263 new = __copy_tls(tsd - libc.tls_size);
265 new->map_size = size;
267 new->stack_size = stack - stack_limit;
269 new->start_arg = arg;
271 new->tsd = (void *)tsd;
272 new->locale = &libc.global_locale;
273 if (attr._a_detach) {
275 flags -= CLONE_CHILD_CLEARTID;
278 do_sched = new->startlock[0] = 1;
279 __block_app_sigs(new->sigmask);
281 new->robust_list.head = &new->robust_list.head;
282 new->unblock_cancel = self->cancel;
283 new->CANARY = self->CANARY;
285 a_inc(&libc.threads_minus_1);
286 ret = __clone((c11 ? start_c11 : start), stack, flags, new, &new->tid, TP_ADJ(new), &new->tid);
291 __restore_sigs(new->sigmask);
295 a_dec(&libc.threads_minus_1);
296 if (map) __munmap(map, size);
301 ret = __syscall(SYS_sched_setscheduler, new->tid,
302 attr._a_policy, &attr._a_prio);
303 a_store(new->startlock, ret<0 ? 2 : 3);
304 __wake(new->startlock, 1, 1);
305 if (ret < 0) return -ret;
315 weak_alias(__pthread_exit, pthread_exit);
316 weak_alias(__pthread_create, pthread_create);