1 #include "pthread_impl.h"
3 void __pthread_unwind_next(struct __ptcb *cb)
5 int i, j, not_finished;
8 if (cb->__next) longjmp((void *)cb->__next->__jb, 1);
10 self = pthread_self();
11 if (self->cancel) self->result = PTHREAD_CANCELLED;
13 LOCK(&self->exitlock);
15 not_finished = self->tsd_used;
16 for (j=0; not_finished && j<PTHREAD_DESTRUCTOR_ITERATIONS; j++) {
18 for (i=0; i<PTHREAD_KEYS_MAX; i++) {
19 if (self->tsd[i] && libc.tsd_keys[i]) {
20 void *tmp = self->tsd[i];
22 libc.tsd_keys[i](tmp);
28 /* Mark this thread dead before decrementing count */
31 if (!a_fetch_add(&libc.threads_minus_1, -1))
34 if (self->detached && self->map_base) {
35 syscall(__NR_rt_sigprocmask, SIG_BLOCK, (long)(uint64_t[1]){-1},0,8);
36 __unmapself(self->map_base, self->map_size);
42 static void docancel(struct pthread *self)
44 struct __ptcb cb = { .__next = self->cancelbuf };
46 self->canceldisable = 1;
47 self->cancelasync = 0;
49 sigaddset(&set, SIGCANCEL);
50 __libc_sigprocmask(SIG_UNBLOCK, &set, 0);
51 __pthread_unwind_next(&cb);
54 static void cancel_handler(int sig, siginfo_t *si, void *ctx)
56 struct pthread *self = __pthread_self();
57 if (si->si_code > 0 || si->si_pid != self->pid) return;
59 if (self->canceldisable) return;
60 if (self->cancelasync || (self->cancelpoint==1 && PC_AT_SYS(ctx)))
64 static void cancelpt(int x)
66 struct pthread *self = __pthread_self();
67 if (self->canceldisable) return;
68 if ((self->cancelpoint+=x)==1 && x>=0 && self->cancel)
72 /* "rsyscall" is a mechanism by which a thread can synchronously force all
73 * other threads to perform an arbitrary syscall. It is necessary to work
74 * around the non-conformant implementation of setuid() et al on Linux,
75 * which affect only the calling thread and not the whole process. This
76 * implementation performs some tricks with signal delivery to work around
77 * the fact that it does not keep any list of threads in userspace. */
80 volatile int lock, hold, blocks, cnt;
86 static void rsyscall_handler(int sig, siginfo_t *si, void *ctx)
88 struct pthread *self = __pthread_self();
90 if (si->si_code > 0 || si->si_pid != self->pid ||
91 rs.cnt == libc.threads_minus_1) return;
93 /* Threads which have already decremented themselves from the
94 * thread count must not increment rs.cnt or otherwise act. */
96 __wait(&rs.hold, 0, 1, 1);
100 if (syscall(rs.nr, rs.arg[0], rs.arg[1], rs.arg[2],
101 rs.arg[3], rs.arg[4], rs.arg[5]) < 0 && !rs.err) rs.err=errno;
104 __wake(&rs.cnt, 1, 1);
106 __wait(&rs.hold, 0, 1, 1);
108 if (!rs.cnt) __wake(&rs.cnt, 1, 1);
111 static int rsyscall(int nr, long a, long b, long c, long d, long e, long f)
114 sigset_t set = { 0 };
115 struct pthread *self = __pthread_self();
116 sigaddset(&set, SIGSYSCALL);
119 while ((i=rs.blocks))
120 __wait(&rs.blocks, 0, i, 1);
122 __libc_sigprocmask(SIG_BLOCK, &set, 0);
125 rs.arg[0] = a; rs.arg[1] = b;
126 rs.arg[2] = c; rs.arg[3] = d;
127 rs.arg[4] = d; rs.arg[5] = f;
132 /* Dispatch signals until all threads respond */
133 for (i=libc.threads_minus_1; i; i--)
134 sigqueue(self->pid, SIGSYSCALL, (union sigval){0});
135 while ((i=rs.cnt) < libc.threads_minus_1) {
136 sigqueue(self->pid, SIGSYSCALL, (union sigval){0});
137 __wait(&rs.cnt, 0, i, 1);
140 /* Handle any lingering signals with no-op */
141 __libc_sigprocmask(SIG_UNBLOCK, &set, 0);
143 /* Resume other threads' signal handlers and wait for them */
145 __wake(&rs.hold, -1, 0);
146 while((i=rs.cnt)) __wait(&rs.cnt, 0, i, 1);
148 if (rs.err) errno = rs.err, ret = -1;
149 else ret = syscall(nr, a, b, c, d, e, f);
155 static void init_threads()
157 struct sigaction sa = { .sa_flags = SA_SIGINFO | SA_RESTART };
159 libc.lockfile = __lockfile;
160 libc.cancelpt = cancelpt;
161 libc.rsyscall = rsyscall;
162 sa.sa_sigaction = cancel_handler;
163 __libc_sigaction(SIGCANCEL, &sa, 0);
164 sigaddset(&sa.sa_mask, SIGSYSCALL);
165 sigaddset(&sa.sa_mask, SIGCANCEL);
166 sa.sa_sigaction = rsyscall_handler;
167 __libc_sigaction(SIGSYSCALL, &sa, 0);
168 sigprocmask(SIG_UNBLOCK, &sa.sa_mask, 0);
171 static int start(void *p)
173 struct pthread *self = p;
174 pthread_exit(self->start(self->start_arg));
178 int __uniclone(void *, int (*)(), void *);
180 #define ROUND(x) (((x)+PAGE_SIZE-1)&-PAGE_SIZE)
182 /* pthread_key_create.c overrides this */
183 static const size_t dummy = 0;
184 weak_alias(dummy, __pthread_tsd_size);
186 int pthread_create(pthread_t *res, const pthread_attr_t *attr, void *(*entry)(void *), void *arg)
191 struct pthread *self = pthread_self(), *new;
192 unsigned char *map, *stack, *tsd;
193 static const pthread_attr_t default_attr;
195 if (!self) return errno = ENOSYS;
196 if (!init && ++init) init_threads();
198 if (!attr) attr = &default_attr;
199 guard = ROUND(attr->_a_guardsize + DEFAULT_GUARD_SIZE);
200 size = guard + ROUND(attr->_a_stacksize + DEFAULT_STACK_SIZE);
201 size += __pthread_tsd_size;
202 map = mmap(0, size, PROT_READ|PROT_WRITE|PROT_EXEC, MAP_PRIVATE|MAP_ANON, -1, 0);
203 if (!map) return EAGAIN;
204 if (guard) mprotect(map, guard, PROT_NONE);
206 tsd = map + size - __pthread_tsd_size;
207 new = (void *)(tsd - sizeof *new - PAGE_SIZE%sizeof *new);
209 new->map_size = size;
210 new->pid = self->pid;
211 new->errno_ptr = &new->errno_val;
213 new->start_arg = arg;
215 new->tsd = (void *)tsd;
216 new->detached = attr->_a_detach;
218 memcpy(new->tlsdesc, self->tlsdesc, sizeof new->tlsdesc);
219 new->tlsdesc[1] = (uintptr_t)new;
220 stack = (void *)((uintptr_t)new-1 & ~(uintptr_t)15);
222 /* We must synchronize new thread creation with rsyscall
223 * delivery. This looks to be the least expensive way: */
225 while (rs.lock) __wait(&rs.lock, 0, 1, 1);
227 a_inc(&libc.threads_minus_1);
228 ret = __uniclone(stack, start, new);
231 if (rs.lock) __wake(&rs.blocks, 1, 1);
234 a_dec(&libc.threads_minus_1);
242 void pthread_exit(void *result)
244 struct pthread *self = pthread_self();
245 self->result = result;