2 #include "pthread_impl.h"
3 #include "stdio_impl.h"
13 weak_alias(dummy_0, __acquire_ptc);
14 weak_alias(dummy_0, __release_ptc);
15 weak_alias(dummy_0, __pthread_tsd_run_dtors);
16 weak_alias(dummy_0, __do_orphaned_stdio_locks);
17 weak_alias(dummy_0, __dl_thread_cleanup);
18 weak_alias(dummy_0, __dl_prepare_for_threads);
22 if (!a_cas(&__thread_list_lock, 0, 1)) return;
24 a_cas(&__thread_list_lock, 1, 2);
25 __futexwait(&__thread_list_lock, 2, 0);
26 } while (a_cas(&__thread_list_lock, 0, 2));
29 void __tl_unlock(void)
31 if (a_swap(&__thread_list_lock, 0)==2)
32 __wake(&__thread_list_lock, 1, 0);
35 void __tl_sync(pthread_t td)
38 if (!__thread_list_lock) return;
39 a_cas(&__thread_list_lock, 1, 2);
40 __wait(&__thread_list_lock, 0, 2, 0);
41 __wake(&__thread_list_lock, 1, 0);
44 _Noreturn void __pthread_exit(void *result)
46 pthread_t self = __pthread_self();
49 self->canceldisable = 1;
50 self->cancelasync = 0;
51 self->result = result;
53 while (self->cancelbuf) {
54 void (*f)(void *) = self->cancelbuf->__f;
55 void *x = self->cancelbuf->__x;
56 self->cancelbuf = self->cancelbuf->__next;
60 __pthread_tsd_run_dtors();
62 /* Access to target the exiting thread with syscalls that use
63 * its kernel tid is controlled by killlock. For detached threads,
64 * any use past this point would have undefined behavior, but for
65 * joinable threads it's a valid usage that must be handled. */
68 /* The thread list lock must be AS-safe, and thus requires
69 * application signals to be blocked before it can be taken. */
70 __block_app_sigs(&set);
73 /* If this is the only thread in the list, don't proceed with
74 * termination of the thread, but restore the previous lock and
75 * signal state to prepare for exit to call atexit handlers. */
76 if (self->next == self) {
79 UNLOCK(self->killlock);
83 /* At this point we are committed to thread termination. Unlink
84 * the thread from the list. This change will not be visible
85 * until the lock is released, which only happens after SYS_exit
86 * has been called, via the exit futex address pointing at the lock. */
87 libc.threads_minus_1--;
88 self->next->prev = self->prev;
89 self->prev->next = self->next;
90 self->prev = self->next = self;
92 /* Process robust list in userspace to handle non-pshared mutexes
93 * and the detached thread case where the robust list head will
94 * be invalid when the kernel would process it. */
96 volatile void *volatile *rp;
97 while ((rp=self->robust_list.head) && rp != &self->robust_list.head) {
98 pthread_mutex_t *m = (void *)((char *)rp
99 - offsetof(pthread_mutex_t, _m_next));
100 int waiters = m->_m_waiters;
101 int priv = (m->_m_type & 128) ^ 128;
102 self->robust_list.pending = rp;
103 self->robust_list.head = *rp;
104 int cont = a_swap(&m->_m_lock, 0x40000000);
105 self->robust_list.pending = 0;
106 if (cont < 0 || waiters)
107 __wake(&m->_m_lock, 1, priv);
111 __do_orphaned_stdio_locks();
112 __dl_thread_cleanup();
114 /* This atomic potentially competes with a concurrent pthread_detach
115 * call; the loser is responsible for freeing thread resources. */
116 int state = a_cas(&self->detach_state, DT_JOINABLE, DT_EXITING);
118 if (state==DT_DETACHED && self->map_base) {
119 /* Detached threads must block even implementation-internal
120 * signals, since they will not have a stack in their last
121 * moments of existence. */
122 __block_all_sigs(&set);
124 /* Robust list will no longer be valid, and was already
125 * processed above, so unregister it with the kernel. */
126 if (self->robust_list.off)
127 __syscall(SYS_set_robust_list, 0, 3*sizeof(long));
129 /* Since __unmapself bypasses the normal munmap code path,
130 * explicitly wait for vmlock holders first. */
133 /* The following call unmaps the thread's stack mapping
134 * and then exits without touching the stack. */
135 __unmapself(self->map_base, self->map_size);
138 /* Wake any joiner. */
139 __wake(&self->detach_state, 1, 1);
141 /* After the kernel thread exits, its tid may be reused. Clear it
142 * to prevent inadvertent use and inform functions that would use
143 * it that it's no longer available. */
145 UNLOCK(self->killlock);
147 for (;;) __syscall(SYS_exit, 0);
150 void __do_cleanup_push(struct __ptcb *cb)
152 struct pthread *self = __pthread_self();
153 cb->__next = self->cancelbuf;
154 self->cancelbuf = cb;
157 void __do_cleanup_pop(struct __ptcb *cb)
159 __pthread_self()->cancelbuf = cb->__next;
163 void *(*start_func)(void *);
165 pthread_attr_t *attr;
167 unsigned long sig_mask[_NSIG/8/sizeof(long)];
170 static int start(void *p)
172 struct start_args *args = p;
174 pthread_t self = __pthread_self();
175 int ret = -__syscall(SYS_sched_setscheduler, self->tid,
176 args->attr->_a_policy, &args->attr->_a_prio);
177 if (a_swap(args->perr, ret)==-2)
178 __wake(args->perr, 1, 1);
180 self->detach_state = DT_DETACHED;
184 __syscall(SYS_rt_sigprocmask, SIG_SETMASK, &args->sig_mask, 0, _NSIG/8);
185 __pthread_exit(args->start_func(args->start_arg));
189 static int start_c11(void *p)
191 struct start_args *args = p;
192 int (*start)(void*) = (int(*)(void*)) args->start_func;
193 __pthread_exit((void *)(uintptr_t)start(args->start_arg));
197 #define ROUND(x) (((x)+PAGE_SIZE-1)&-PAGE_SIZE)
199 /* pthread_key_create.c overrides this */
200 static volatile size_t dummy = 0;
201 weak_alias(dummy, __pthread_tsd_size);
202 static void *dummy_tsd[1] = { 0 };
203 weak_alias(dummy_tsd, __pthread_tsd_main);
205 static FILE *volatile dummy_file = 0;
206 weak_alias(dummy_file, __stdin_used);
207 weak_alias(dummy_file, __stdout_used);
208 weak_alias(dummy_file, __stderr_used);
210 static void init_file_lock(FILE *f)
212 if (f && f->lock<0) f->lock = 0;
215 int __pthread_create(pthread_t *restrict res, const pthread_attr_t *restrict attrp, void *(*entry)(void *), void *restrict arg)
217 int ret, c11 = (attrp == __ATTRP_C11_THREAD);
219 struct pthread *self, *new;
220 unsigned char *map = 0, *stack = 0, *tsd = 0, *stack_limit;
221 unsigned flags = CLONE_VM | CLONE_FS | CLONE_FILES | CLONE_SIGHAND
222 | CLONE_THREAD | CLONE_SYSVSEM | CLONE_SETTLS
223 | CLONE_PARENT_SETTID | CLONE_CHILD_CLEARTID | CLONE_DETACHED;
224 pthread_attr_t attr = { 0 };
226 volatile int err = -1;
228 if (!libc.can_do_threads) return ENOSYS;
229 self = __pthread_self();
230 if (!libc.threaded) {
231 for (FILE *f=*__ofl_lock(); f; f=f->next)
234 init_file_lock(__stdin_used);
235 init_file_lock(__stdout_used);
236 init_file_lock(__stderr_used);
237 __syscall(SYS_rt_sigprocmask, SIG_UNBLOCK, SIGPT_SET, 0, _NSIG/8);
238 self->tsd = (void **)__pthread_tsd_main;
239 __dl_prepare_for_threads();
242 if (attrp && !c11) attr = *attrp;
246 attr._a_stacksize = __default_stacksize;
247 attr._a_guardsize = __default_guardsize;
250 if (attr._a_stackaddr) {
251 size_t need = libc.tls_size + __pthread_tsd_size;
252 size = attr._a_stacksize;
253 stack = (void *)(attr._a_stackaddr & -16);
254 stack_limit = (void *)(attr._a_stackaddr - size);
255 /* Use application-provided stack for TLS only when
256 * it does not take more than ~12% or 2k of the
257 * application's stack space. */
258 if (need < size/8 && need < 2048) {
259 tsd = stack - __pthread_tsd_size;
260 stack = tsd - libc.tls_size;
261 memset(stack, 0, need);
267 guard = ROUND(attr._a_guardsize);
268 size = guard + ROUND(attr._a_stacksize
269 + libc.tls_size + __pthread_tsd_size);
274 map = __mmap(0, size, PROT_NONE, MAP_PRIVATE|MAP_ANON, -1, 0);
275 if (map == MAP_FAILED) goto fail;
276 if (__mprotect(map+guard, size-guard, PROT_READ|PROT_WRITE)
277 && errno != ENOSYS) {
282 map = __mmap(0, size, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANON, -1, 0);
283 if (map == MAP_FAILED) goto fail;
285 tsd = map + size - __pthread_tsd_size;
287 stack = tsd - libc.tls_size;
288 stack_limit = map + guard;
292 new = __copy_tls(tsd - libc.tls_size);
294 new->map_size = size;
296 new->stack_size = stack - stack_limit;
297 new->guard_size = guard;
299 new->tsd = (void *)tsd;
300 new->locale = &libc.global_locale;
301 if (attr._a_detach) {
302 new->detach_state = DT_DETACHED;
304 new->detach_state = DT_JOINABLE;
306 new->robust_list.head = &new->robust_list.head;
307 new->CANARY = self->CANARY;
309 /* Setup argument structure for the new thread on its stack.
310 * It's safe to access from the caller only until the thread
311 * list is unlocked. */
312 stack -= (uintptr_t)stack % sizeof(uintptr_t);
313 stack -= sizeof(struct start_args);
314 struct start_args *args = (void *)stack;
315 args->start_func = entry;
316 args->start_arg = arg;
325 /* Application signals (but not the synccall signal) must be
326 * blocked before the thread list lock can be taken, to ensure
327 * that the lock is AS-safe. */
328 __block_app_sigs(&set);
330 /* Ensure SIGCANCEL is unblocked in new thread. This requires
331 * working with a copy of the set so we can restore the
332 * original mask in the calling thread. */
333 memcpy(&args->sig_mask, &set, sizeof args->sig_mask);
334 args->sig_mask[(SIGCANCEL-1)/8/sizeof(long)] &=
335 ~(1UL<<((SIGCANCEL-1)%(8*sizeof(long))));
338 libc.threads_minus_1++;
339 ret = __clone((c11 ? start_c11 : start), stack, flags, args, &new->tid, TP_ADJ(new), &__thread_list_lock);
341 /* If clone succeeded, new thread must be linked on the thread
342 * list before unlocking it, even if scheduling may still fail. */
344 new->next = self->next;
346 new->next->prev = new;
347 new->prev->next = new;
350 __restore_sigs(&set);
354 libc.threads_minus_1--;
355 if (map) __munmap(map, size);
360 if (a_cas(&err, -1, -2)==-1)
361 __wait(&err, 0, -2, 1);
373 weak_alias(__pthread_exit, pthread_exit);
374 weak_alias(__pthread_create, pthread_create);