2 #include "pthread_impl.h"
3 #include "stdio_impl.h"
10 weak_alias(dummy_0, __acquire_ptc);
11 weak_alias(dummy_0, __release_ptc);
12 weak_alias(dummy_0, __pthread_tsd_run_dtors);
14 _Noreturn void pthread_exit(void *result)
16 pthread_t self = __pthread_self();
19 self->result = result;
21 while (self->cancelbuf) {
22 void (*f)(void *) = self->cancelbuf->__f;
23 void *x = self->cancelbuf->__x;
24 self->cancelbuf = self->cancelbuf->__next;
28 __pthread_tsd_run_dtors();
30 __lock(self->exitlock);
32 /* Mark this thread dead before decrementing count */
33 __lock(self->killlock);
36 /* Block all signals before decrementing the live thread count.
37 * This is important to ensure that dynamically allocated TLS
38 * is not under-allocated/over-committed, and possibly for other
40 __block_all_sigs(&set);
42 /* Wait to unlock the kill lock, which governs functions like
43 * pthread_kill which target a thread id, until signals have
44 * been blocked. This precludes observation of the thread id
45 * as a live thread (with application code running in it) after
46 * the thread was reported dead by ESRCH being returned. */
47 __unlock(self->killlock);
49 /* It's impossible to determine whether this is "the last thread"
50 * until performing the atomic decrement, since multiple threads
51 * could exit at the same time. For the last thread, revert the
52 * decrement and unblock signals to give the atexit handlers and
53 * stdio cleanup code a consistent state. */
54 if (a_fetch_add(&libc.threads_minus_1, -1)==0) {
55 libc.threads_minus_1 = 0;
60 if (self->locale != &libc.global_locale) {
61 a_dec(&libc.uselocale_cnt);
62 if (self->locale->ctype_utf8)
63 a_dec(&libc.bytelocale_cnt_minus_1);
66 if (self->detached && self->map_base) {
67 /* Detached threads must avoid the kernel clear_child_tid
68 * feature, since the virtual address will have been
69 * unmapped and possibly already reused by a new mapping
70 * at the time the kernel would perform the write. In
71 * the case of threads that started out detached, the
72 * initial clone flags are correct, but if the thread was
73 * detached later (== 2), we need to clear it here. */
74 if (self->detached == 2) __syscall(SYS_set_tid_address, 0);
76 /* The following call unmaps the thread's stack mapping
77 * and then exits without touching the stack. */
78 __unmapself(self->map_base, self->map_size);
81 for (;;) __syscall(SYS_exit, 0);
84 void __do_cleanup_push(struct __ptcb *cb)
86 if (!libc.has_thread_pointer) return;
87 struct pthread *self = __pthread_self();
88 cb->__next = self->cancelbuf;
92 void __do_cleanup_pop(struct __ptcb *cb)
94 if (!libc.has_thread_pointer) return;
95 __pthread_self()->cancelbuf = cb->__next;
98 static int start(void *p)
101 if (self->startlock[0]) {
102 __wait(self->startlock, 0, 1, 1);
103 if (self->startlock[0]) {
107 __restore_sigs(self->sigmask);
109 if (self->unblock_cancel)
110 __syscall(SYS_rt_sigprocmask, SIG_UNBLOCK,
111 SIGPT_SET, 0, _NSIG/8);
112 pthread_exit(self->start(self->start_arg));
116 #define ROUND(x) (((x)+PAGE_SIZE-1)&-PAGE_SIZE)
118 /* pthread_key_create.c overrides this */
119 static volatile size_t dummy = 0;
120 weak_alias(dummy, __pthread_tsd_size);
121 static void *dummy_tsd[1] = { 0 };
122 weak_alias(dummy_tsd, __pthread_tsd_main);
124 static FILE *volatile dummy_file = 0;
125 weak_alias(dummy_file, __stdin_used);
126 weak_alias(dummy_file, __stdout_used);
127 weak_alias(dummy_file, __stderr_used);
129 static void init_file_lock(FILE *f)
131 if (f && f->lock<0) f->lock = 0;
134 void *__copy_tls(unsigned char *);
136 int pthread_create(pthread_t *restrict res, const pthread_attr_t *restrict attrp, void *(*entry)(void *), void *restrict arg)
140 struct pthread *self, *new;
141 unsigned char *map = 0, *stack = 0, *tsd = 0, *stack_limit;
142 unsigned flags = CLONE_VM | CLONE_FS | CLONE_FILES | CLONE_SIGHAND
143 | CLONE_THREAD | CLONE_SYSVSEM | CLONE_SETTLS
144 | CLONE_PARENT_SETTID | CLONE_CHILD_CLEARTID | CLONE_DETACHED;
146 pthread_attr_t attr = {0};
148 if (!libc.can_do_threads) return ENOSYS;
149 self = __pthread_self();
150 if (!libc.threaded) {
151 for (FILE *f=libc.ofl_head; f; f=f->next)
153 init_file_lock(__stdin_used);
154 init_file_lock(__stdout_used);
155 init_file_lock(__stderr_used);
156 __syscall(SYS_rt_sigprocmask, SIG_UNBLOCK, SIGPT_SET, 0, _NSIG/8);
157 self->tsd = (void **)__pthread_tsd_main;
160 if (attrp) attr = *attrp;
164 if (attr._a_stackaddr) {
165 size_t need = libc.tls_size + __pthread_tsd_size;
166 size = attr._a_stacksize + DEFAULT_STACK_SIZE;
167 stack = (void *)(attr._a_stackaddr & -16);
168 stack_limit = (void *)(attr._a_stackaddr - size);
169 /* Use application-provided stack for TLS only when
170 * it does not take more than ~12% or 2k of the
171 * application's stack space. */
172 if (need < size/8 && need < 2048) {
173 tsd = stack - __pthread_tsd_size;
174 stack = tsd - libc.tls_size;
180 guard = ROUND(DEFAULT_GUARD_SIZE + attr._a_guardsize);
181 size = guard + ROUND(DEFAULT_STACK_SIZE + attr._a_stacksize
182 + libc.tls_size + __pthread_tsd_size);
187 map = mmap(0, size, PROT_NONE, MAP_PRIVATE|MAP_ANON, -1, 0);
188 if (map == MAP_FAILED) goto fail;
189 if (mprotect(map+guard, size-guard, PROT_READ|PROT_WRITE)) {
194 map = mmap(0, size, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANON, -1, 0);
195 if (map == MAP_FAILED) goto fail;
197 tsd = map + size - __pthread_tsd_size;
199 stack = tsd - libc.tls_size;
200 stack_limit = map + guard;
204 new = __copy_tls(tsd - libc.tls_size);
206 new->map_size = size;
208 new->stack_size = stack - stack_limit;
210 new->start_arg = arg;
212 new->tsd = (void *)tsd;
213 new->locale = &libc.global_locale;
214 if (attr._a_detach) {
216 flags -= CLONE_CHILD_CLEARTID;
219 do_sched = new->startlock[0] = 1;
220 __block_app_sigs(new->sigmask);
222 new->unblock_cancel = self->cancel;
223 new->canary = self->canary;
225 a_inc(&libc.threads_minus_1);
226 ret = __clone(start, stack, flags, new, &new->tid, TP_ADJ(new), &new->tid);
231 __restore_sigs(new->sigmask);
235 a_dec(&libc.threads_minus_1);
236 if (map) munmap(map, size);
241 ret = __syscall(SYS_sched_setscheduler, new->tid,
242 attr._a_policy, &attr._a_prio);
243 a_store(new->startlock, ret<0 ? 2 : 0);
244 __wake(new->startlock, 1, 1);
245 if (ret < 0) return -ret;