1 #include "pthread_impl.h"
3 #ifdef __pthread_unwind_next
4 #undef __pthread_unwind_next
5 #define __pthread_unwind_next __pthread_unwind_next_3
8 void __pthread_unwind_next(struct __ptcb *cb)
10 int i, j, not_finished;
13 if (cb->__next) longjmp((void *)cb->__next->__jb, 1);
15 self = pthread_self();
17 LOCK(&self->exitlock);
19 not_finished = self->tsd_used;
20 for (j=0; not_finished && j<PTHREAD_DESTRUCTOR_ITERATIONS; j++) {
22 for (i=0; i<PTHREAD_KEYS_MAX; i++) {
23 if (self->tsd[i] && libc.tsd_keys[i]) {
24 void *tmp = self->tsd[i];
26 libc.tsd_keys[i](tmp);
32 /* Mark this thread dead before decrementing count */
35 if (!a_fetch_add(&libc.threads_minus_1, -1))
38 if (self->detached && self->map_base) {
39 syscall(__NR_rt_sigprocmask, SIG_BLOCK, (long)(uint64_t[1]){-1},0,8);
40 __unmapself(self->map_base, self->map_size);
46 static void docancel(struct pthread *self)
48 struct __ptcb cb = { .__next = self->cancelbuf };
49 self->canceldisable = 1;
50 self->cancelasync = 0;
51 __pthread_unwind_next(&cb);
54 static void cancel_handler(int sig, siginfo_t *si, void *ctx)
56 struct pthread *self = __pthread_self();
58 if (si->si_code == SI_TIMER && libc.sigtimer)
59 libc.sigtimer(sig, si, ctx);
62 if (self->canceldisable) return;
63 if (self->cancelasync || (self->cancelpoint==1 && PC_AT_SYS(ctx)))
67 static void cancelpt(int x)
69 struct pthread *self = __pthread_self();
70 if (self->canceldisable) return;
71 if ((self->cancelpoint+=x)==1 && x>=0 && self->cancel)
75 /* "rsyscall" is a mechanism by which a thread can synchronously force all
76 * other threads to perform an arbitrary syscall. It is necessary to work
77 * around the non-conformant implementation of setuid() et al on Linux,
78 * which affect only the calling thread and not the whole process. This
79 * implementation performs some tricks with signal delivery to work around
80 * the fact that it does not keep any list of threads in userspace. */
83 volatile int lock, hold, blocks, cnt;
89 static void rsyscall_handler(int sig, siginfo_t *si, void *ctx)
91 struct pthread *self = __pthread_self();
93 if (si->si_code > 0 || si->si_pid != self->pid ||
94 rs.cnt == libc.threads_minus_1) return;
96 /* Threads which have already decremented themselves from the
97 * thread count must not increment rs.cnt or otherwise act. */
99 __wait(&rs.hold, 0, 1, 1);
103 if (syscall(rs.nr, rs.arg[0], rs.arg[1], rs.arg[2],
104 rs.arg[3], rs.arg[4], rs.arg[5]) < 0 && !rs.err) rs.err=errno;
107 __wake(&rs.cnt, 1, 1);
109 __wait(&rs.hold, 0, 1, 1);
111 if (!rs.cnt) __wake(&rs.cnt, 1, 1);
114 static int rsyscall(int nr, long a, long b, long c, long d, long e, long f)
117 sigset_t set = { 0 };
118 struct pthread *self = __pthread_self();
119 sigaddset(&set, SIGSYSCALL);
122 while ((i=rs.blocks))
123 __wait(&rs.blocks, 0, i, 1);
125 __libc_sigprocmask(SIG_BLOCK, &set, 0);
128 rs.arg[0] = a; rs.arg[1] = b;
129 rs.arg[2] = c; rs.arg[3] = d;
130 rs.arg[4] = d; rs.arg[5] = f;
135 /* Dispatch signals until all threads respond */
136 for (i=libc.threads_minus_1; i; i--)
137 sigqueue(self->pid, SIGSYSCALL, (union sigval){0});
138 while ((i=rs.cnt) < libc.threads_minus_1) {
139 sigqueue(self->pid, SIGSYSCALL, (union sigval){0});
140 __wait(&rs.cnt, 0, i, 1);
143 /* Handle any lingering signals with no-op */
144 __libc_sigprocmask(SIG_UNBLOCK, &set, 0);
146 /* Resume other threads' signal handlers and wait for them */
148 __wake(&rs.hold, -1, 0);
149 while((i=rs.cnt)) __wait(&rs.cnt, 0, i, 1);
151 if (rs.err) errno = rs.err, ret = -1;
152 else ret = syscall(nr, a, b, c, d, e, f);
158 static void init_threads()
160 struct sigaction sa = { .sa_flags = SA_SIGINFO | SA_RESTART };
162 libc.lockfile = __lockfile;
163 libc.cancelpt = cancelpt;
164 libc.rsyscall = rsyscall;
165 sa.sa_sigaction = cancel_handler;
166 __libc_sigaction(SIGCANCEL, &sa, 0);
167 sigaddset(&sa.sa_mask, SIGSYSCALL);
168 sigaddset(&sa.sa_mask, SIGCANCEL);
169 sa.sa_sigaction = rsyscall_handler;
170 __libc_sigaction(SIGSYSCALL, &sa, 0);
171 sigprocmask(SIG_UNBLOCK, &sa.sa_mask, 0);
174 static int start(void *p)
176 struct pthread *self = p;
177 if (self->unblock_cancel) {
180 sigaddset(&set, SIGCANCEL);
181 __libc_sigprocmask(SIG_UNBLOCK, &set, 0);
183 pthread_exit(self->start(self->start_arg));
187 int __uniclone(void *, int (*)(), void *);
189 #define ROUND(x) (((x)+PAGE_SIZE-1)&-PAGE_SIZE)
191 /* pthread_key_create.c overrides this */
192 static const size_t dummy = 0;
193 weak_alias(dummy, __pthread_tsd_size);
195 int pthread_create(pthread_t *res, const pthread_attr_t *attr, void *(*entry)(void *), void *arg)
200 struct pthread *self = pthread_self(), *new;
201 unsigned char *map, *stack, *tsd;
202 static const pthread_attr_t default_attr;
204 if (!self) return errno = ENOSYS;
205 if (!init && ++init) init_threads();
207 if (!attr) attr = &default_attr;
208 guard = ROUND(attr->_a_guardsize + DEFAULT_GUARD_SIZE);
209 size = guard + ROUND(attr->_a_stacksize + DEFAULT_STACK_SIZE);
210 size += __pthread_tsd_size;
211 map = mmap(0, size, PROT_READ|PROT_WRITE|PROT_EXEC, MAP_PRIVATE|MAP_ANON, -1, 0);
212 if (!map) return EAGAIN;
213 if (guard) mprotect(map, guard, PROT_NONE);
215 tsd = map + size - __pthread_tsd_size;
216 new = (void *)(tsd - sizeof *new - PAGE_SIZE%sizeof *new);
218 new->map_size = size;
219 new->pid = self->pid;
220 new->errno_ptr = &new->errno_val;
222 new->start_arg = arg;
224 new->tsd = (void *)tsd;
225 new->detached = attr->_a_detach;
227 new->unblock_cancel = self->cancel;
228 new->result = PTHREAD_CANCELED;
229 memcpy(new->tlsdesc, self->tlsdesc, sizeof new->tlsdesc);
230 new->tlsdesc[1] = (uintptr_t)new;
231 stack = (void *)((uintptr_t)new-1 & ~(uintptr_t)15);
233 /* We must synchronize new thread creation with rsyscall
234 * delivery. This looks to be the least expensive way: */
236 while (rs.lock) __wait(&rs.lock, 0, 1, 1);
238 a_inc(&libc.threads_minus_1);
239 ret = __uniclone(stack, start, new);
242 if (rs.lock) __wake(&rs.blocks, 1, 1);
245 a_dec(&libc.threads_minus_1);
253 void pthread_exit(void *result)
255 struct pthread *self = pthread_self();
256 self->result = result;