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->detached && self->map_base) {
61 /* Detached threads must avoid the kernel clear_child_tid
62 * feature, since the virtual address will have been
63 * unmapped and possibly already reused by a new mapping
64 * at the time the kernel would perform the write. In
65 * the case of threads that started out detached, the
66 * initial clone flags are correct, but if the thread was
67 * detached later (== 2), we need to clear it here. */
68 if (self->detached == 2) __syscall(SYS_set_tid_address, 0);
70 /* The following call unmaps the thread's stack mapping
71 * and then exits without touching the stack. */
72 __unmapself(self->map_base, self->map_size);
75 for (;;) __syscall(SYS_exit, 0);
78 void __do_cleanup_push(struct __ptcb *cb)
80 struct pthread *self = pthread_self();
81 cb->__next = self->cancelbuf;
85 void __do_cleanup_pop(struct __ptcb *cb)
87 __pthread_self()->cancelbuf = cb->__next;
90 static int start(void *p)
93 if (self->startlock[0]) {
94 __wait(self->startlock, 0, 1, 1);
95 if (self->startlock[0]) {
99 __restore_sigs(self->sigmask);
101 if (self->unblock_cancel)
102 __syscall(SYS_rt_sigprocmask, SIG_UNBLOCK,
103 SIGPT_SET, 0, _NSIG/8);
104 pthread_exit(self->start(self->start_arg));
108 #define ROUND(x) (((x)+PAGE_SIZE-1)&-PAGE_SIZE)
110 /* pthread_key_create.c overrides this */
111 static const size_t dummy = 0;
112 weak_alias(dummy, __pthread_tsd_size);
114 static FILE *const dummy_file = 0;
115 weak_alias(dummy_file, __stdin_used);
116 weak_alias(dummy_file, __stdout_used);
117 weak_alias(dummy_file, __stderr_used);
119 static void init_file_lock(FILE *f)
121 if (f && f->lock<0) f->lock = 0;
124 void *__copy_tls(unsigned char *);
126 int pthread_create(pthread_t *restrict res, const pthread_attr_t *restrict attrp, void *(*entry)(void *), void *restrict arg)
130 struct pthread *self = pthread_self(), *new;
131 unsigned char *map = 0, *stack = 0, *tsd = 0, *stack_limit;
132 unsigned flags = CLONE_VM | CLONE_FS | CLONE_FILES | CLONE_SIGHAND
133 | CLONE_THREAD | CLONE_SYSVSEM | CLONE_SETTLS
134 | CLONE_PARENT_SETTID | CLONE_CHILD_CLEARTID | CLONE_DETACHED;
136 pthread_attr_t attr = {0};
138 if (!self) return ENOSYS;
139 if (!libc.threaded) {
140 for (FILE *f=libc.ofl_head; f; f=f->next)
142 init_file_lock(__stdin_used);
143 init_file_lock(__stdout_used);
144 init_file_lock(__stderr_used);
147 if (attrp) attr = *attrp;
151 if (attr._a_stackaddr) {
152 size_t need = libc.tls_size + __pthread_tsd_size;
153 size = attr._a_stacksize + DEFAULT_STACK_SIZE;
154 stack = (void *)(attr._a_stackaddr & -16);
155 stack_limit = (void *)(attr._a_stackaddr - size);
156 /* Use application-provided stack for TLS only when
157 * it does not take more than ~12% or 2k of the
158 * application's stack space. */
159 if (need < size/8 && need < 2048) {
160 tsd = stack - __pthread_tsd_size;
161 stack = tsd - libc.tls_size;
167 guard = ROUND(DEFAULT_GUARD_SIZE + attr._a_guardsize);
168 size = guard + ROUND(DEFAULT_STACK_SIZE + attr._a_stacksize
169 + libc.tls_size + __pthread_tsd_size);
174 map = mmap(0, size, PROT_NONE, MAP_PRIVATE|MAP_ANON, -1, 0);
175 if (map == MAP_FAILED) goto fail;
176 if (mprotect(map+guard, size-guard, PROT_READ|PROT_WRITE)) {
181 map = mmap(0, size, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANON, -1, 0);
182 if (map == MAP_FAILED) goto fail;
184 tsd = map + size - __pthread_tsd_size;
186 stack = tsd - libc.tls_size;
187 stack_limit = map + guard;
191 new = __copy_tls(tsd - libc.tls_size);
193 new->map_size = size;
195 new->stack_size = stack - stack_limit;
196 new->pid = self->pid;
197 new->errno_ptr = &new->errno_val;
199 new->start_arg = arg;
201 new->tsd = (void *)tsd;
202 if (attr._a_detach) {
204 flags -= CLONE_CHILD_CLEARTID;
207 do_sched = new->startlock[0] = 1;
208 __block_app_sigs(new->sigmask);
210 new->unblock_cancel = self->cancel;
211 new->canary = self->canary;
213 a_inc(&libc.threads_minus_1);
214 ret = __clone(start, stack, flags, new, &new->tid, TP_ADJ(new), &new->tid);
219 __restore_sigs(new->sigmask);
223 a_dec(&libc.threads_minus_1);
224 if (map) munmap(map, size);
229 ret = __syscall(SYS_sched_setscheduler, new->tid,
230 attr._a_policy, &attr._a_prio);
231 a_store(new->startlock, ret<0 ? 2 : 0);
232 __wake(new->startlock, 1, 1);
233 if (ret < 0) return -ret;