2 #include "pthread_impl.h"
3 #include "stdio_impl.h"
8 void *__mmap(void *, size_t, int, int, int, off_t);
9 int __munmap(void *, size_t);
10 int __mprotect(void *, size_t, int);
15 weak_alias(dummy_0, __acquire_ptc);
16 weak_alias(dummy_0, __release_ptc);
17 weak_alias(dummy_0, __pthread_tsd_run_dtors);
18 weak_alias(dummy_0, __do_private_robust_list);
19 weak_alias(dummy_0, __do_orphaned_stdio_locks);
21 _Noreturn void __pthread_exit(void *result)
23 pthread_t self = __pthread_self();
26 self->canceldisable = 1;
27 self->cancelasync = 0;
28 self->result = result;
30 while (self->cancelbuf) {
31 void (*f)(void *) = self->cancelbuf->__f;
32 void *x = self->cancelbuf->__x;
33 self->cancelbuf = self->cancelbuf->__next;
37 __pthread_tsd_run_dtors();
39 __lock(self->exitlock);
41 /* Mark this thread dead before decrementing count */
42 __lock(self->killlock);
45 /* Block all signals before decrementing the live thread count.
46 * This is important to ensure that dynamically allocated TLS
47 * is not under-allocated/over-committed, and possibly for other
49 __block_all_sigs(&set);
51 /* Wait to unlock the kill lock, which governs functions like
52 * pthread_kill which target a thread id, until signals have
53 * been blocked. This precludes observation of the thread id
54 * as a live thread (with application code running in it) after
55 * the thread was reported dead by ESRCH being returned. */
56 __unlock(self->killlock);
58 /* It's impossible to determine whether this is "the last thread"
59 * until performing the atomic decrement, since multiple threads
60 * could exit at the same time. For the last thread, revert the
61 * decrement and unblock signals to give the atexit handlers and
62 * stdio cleanup code a consistent state. */
63 if (a_fetch_add(&libc.threads_minus_1, -1)==0) {
64 libc.threads_minus_1 = 0;
69 if (self->locale != &libc.global_locale) {
70 a_dec(&libc.uselocale_cnt);
71 if (self->locale->ctype_utf8)
72 a_dec(&libc.bytelocale_cnt_minus_1);
75 __do_private_robust_list();
76 __do_orphaned_stdio_locks();
78 if (self->detached && self->map_base) {
79 /* Detached threads must avoid the kernel clear_child_tid
80 * feature, since the virtual address will have been
81 * unmapped and possibly already reused by a new mapping
82 * at the time the kernel would perform the write. In
83 * the case of threads that started out detached, the
84 * initial clone flags are correct, but if the thread was
85 * detached later (== 2), we need to clear it here. */
86 if (self->detached == 2) __syscall(SYS_set_tid_address, 0);
88 /* The following call unmaps the thread's stack mapping
89 * and then exits without touching the stack. */
90 __unmapself(self->map_base, self->map_size);
93 for (;;) __syscall(SYS_exit, 0);
96 void __do_cleanup_push(struct __ptcb *cb)
98 if (!libc.has_thread_pointer) return;
99 struct pthread *self = __pthread_self();
100 cb->__next = self->cancelbuf;
101 self->cancelbuf = cb;
104 void __do_cleanup_pop(struct __ptcb *cb)
106 if (!libc.has_thread_pointer) return;
107 __pthread_self()->cancelbuf = cb->__next;
110 static int start(void *p)
113 if (self->startlock[0]) {
114 __wait(self->startlock, 0, 1, 1);
115 if (self->startlock[0]) {
119 __restore_sigs(self->sigmask);
121 if (self->unblock_cancel)
122 __syscall(SYS_rt_sigprocmask, SIG_UNBLOCK,
123 SIGPT_SET, 0, _NSIG/8);
124 __pthread_exit(self->start(self->start_arg));
128 static int start_c11(void *p)
131 int (*start)(void*) = (int(*)(void*)) self->start;
132 __pthread_exit((void *)(uintptr_t)start(self->start_arg));
136 #define ROUND(x) (((x)+PAGE_SIZE-1)&-PAGE_SIZE)
138 /* pthread_key_create.c overrides this */
139 static volatile size_t dummy = 0;
140 weak_alias(dummy, __pthread_tsd_size);
141 static void *dummy_tsd[1] = { 0 };
142 weak_alias(dummy_tsd, __pthread_tsd_main);
144 volatile int __block_new_threads = 0;
146 static FILE *volatile dummy_file = 0;
147 weak_alias(dummy_file, __stdin_used);
148 weak_alias(dummy_file, __stdout_used);
149 weak_alias(dummy_file, __stderr_used);
151 static void init_file_lock(FILE *f)
153 if (f && f->lock<0) f->lock = 0;
156 void *__copy_tls(unsigned char *);
158 int __pthread_create(pthread_t *restrict res, const pthread_attr_t *restrict attrp, void *(*entry)(void *), void *restrict arg)
160 int ret, c11 = (attrp == __ATTRP_C11_THREAD);
162 struct pthread *self, *new;
163 unsigned char *map = 0, *stack = 0, *tsd = 0, *stack_limit;
164 unsigned flags = CLONE_VM | CLONE_FS | CLONE_FILES | CLONE_SIGHAND
165 | CLONE_THREAD | CLONE_SYSVSEM | CLONE_SETTLS
166 | CLONE_PARENT_SETTID | CLONE_CHILD_CLEARTID | CLONE_DETACHED;
168 pthread_attr_t attr = {0};
170 if (!libc.can_do_threads) return ENOSYS;
171 self = __pthread_self();
172 if (!libc.threaded) {
173 for (FILE *f=libc.ofl_head; f; f=f->next)
175 init_file_lock(__stdin_used);
176 init_file_lock(__stdout_used);
177 init_file_lock(__stderr_used);
178 __syscall(SYS_rt_sigprocmask, SIG_UNBLOCK, SIGPT_SET, 0, _NSIG/8);
179 self->tsd = (void **)__pthread_tsd_main;
182 if (attrp && !c11) attr = *attrp;
185 if (__block_new_threads) __wait(&__block_new_threads, 0, 1, 1);
187 if (attr._a_stackaddr) {
188 size_t need = libc.tls_size + __pthread_tsd_size;
189 size = attr._a_stacksize + DEFAULT_STACK_SIZE;
190 stack = (void *)(attr._a_stackaddr & -16);
191 stack_limit = (void *)(attr._a_stackaddr - size);
192 /* Use application-provided stack for TLS only when
193 * it does not take more than ~12% or 2k of the
194 * application's stack space. */
195 if (need < size/8 && need < 2048) {
196 tsd = stack - __pthread_tsd_size;
197 stack = tsd - libc.tls_size;
198 memset(stack, 0, need);
204 guard = ROUND(DEFAULT_GUARD_SIZE + attr._a_guardsize);
205 size = guard + ROUND(DEFAULT_STACK_SIZE + attr._a_stacksize
206 + libc.tls_size + __pthread_tsd_size);
211 map = __mmap(0, size, PROT_NONE, MAP_PRIVATE|MAP_ANON, -1, 0);
212 if (map == MAP_FAILED) goto fail;
213 if (__mprotect(map+guard, size-guard, PROT_READ|PROT_WRITE)) {
218 map = __mmap(0, size, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANON, -1, 0);
219 if (map == MAP_FAILED) goto fail;
221 tsd = map + size - __pthread_tsd_size;
223 stack = tsd - libc.tls_size;
224 stack_limit = map + guard;
228 new = __copy_tls(tsd - libc.tls_size);
230 new->map_size = size;
232 new->stack_size = stack - stack_limit;
234 new->start_arg = arg;
236 new->tsd = (void *)tsd;
237 new->locale = &libc.global_locale;
238 if (attr._a_detach) {
240 flags -= CLONE_CHILD_CLEARTID;
243 do_sched = new->startlock[0] = 1;
244 __block_app_sigs(new->sigmask);
246 new->unblock_cancel = self->cancel;
247 new->canary = self->canary;
249 a_inc(&libc.threads_minus_1);
250 ret = __clone((c11 ? start_c11 : start), stack, flags, new, &new->tid, TP_ADJ(new), &new->tid);
255 __restore_sigs(new->sigmask);
259 a_dec(&libc.threads_minus_1);
260 if (map) __munmap(map, size);
265 ret = __syscall(SYS_sched_setscheduler, new->tid,
266 attr._a_policy, &attr._a_prio);
267 a_store(new->startlock, ret<0 ? 2 : 0);
268 __wake(new->startlock, 1, 1);
269 if (ret < 0) return -ret;
279 weak_alias(__pthread_exit, pthread_exit);
280 weak_alias(__pthread_create, pthread_create);