diff options
Diffstat (limited to 'src/thread/__rsyscall.c')
-rw-r--r-- | src/thread/__rsyscall.c | 114 |
1 files changed, 0 insertions, 114 deletions
diff --git a/src/thread/__rsyscall.c b/src/thread/__rsyscall.c deleted file mode 100644 index e885d9e7..00000000 --- a/src/thread/__rsyscall.c +++ /dev/null @@ -1,114 +0,0 @@ -#include "pthread_impl.h" - -/* "rsyscall" is a mechanism by which a thread can synchronously force all - * other threads to perform an arbitrary syscall. It is necessary to work - * around the non-conformant implementation of setuid() et al on Linux, - * which affect only the calling thread and not the whole process. This - * implementation performs some tricks with signal delivery to work around - * the fact that it does not keep any list of threads in userspace. */ - -static struct { - volatile int lock, hold, blocks, cnt; - unsigned long arg[6]; - int nr; - int err; - int init; -} rs; - -static void rsyscall_handler(int sig, siginfo_t *si, void *ctx) -{ - struct pthread *self = __pthread_self(); - long r; - - if (!rs.hold || rs.cnt == libc.threads_minus_1) return; - - /* Threads which have already decremented themselves from the - * thread count must not increment rs.cnt or otherwise act. */ - if (self->dead) { - sigfillset(&((ucontext_t *)ctx)->uc_sigmask); - return; - } - - r = __syscall(rs.nr, rs.arg[0], rs.arg[1], - rs.arg[2], rs.arg[3], rs.arg[4], rs.arg[5]); - if (r < 0) rs.err=-r; - - a_inc(&rs.cnt); - __wake(&rs.cnt, 1, 1); - while(rs.hold) - __wait(&rs.hold, 0, 1, 1); - a_dec(&rs.cnt); - if (!rs.cnt) __wake(&rs.cnt, 1, 1); -} - -int __rsyscall(int nr, long a, long b, long c, long d, long e, long f) -{ - int i, ret; - sigset_t set = { 0 }; - struct pthread *self; - - if (!libc.threads_minus_1) - return syscall(nr, a, b, c, d, e, f); - - self = __pthread_self(); - - LOCK(&rs.lock); - while ((i=rs.blocks)) - __wait(&rs.blocks, 0, i, 1); - - __syscall(SYS_rt_sigprocmask, SIG_BLOCK, (uint64_t[]){-1}, &set, 8); - - if (!rs.init) { - struct sigaction sa = { - .sa_flags = SA_SIGINFO | SA_RESTART, - .sa_sigaction = rsyscall_handler, - .sa_mask = set - }; - sigfillset(&sa.sa_mask); - sa.sa_sigaction = rsyscall_handler; - __libc_sigaction(SIGSYSCALL, &sa, 0); - rs.init = 1; - } - - rs.nr = nr; - rs.arg[0] = a; rs.arg[1] = b; - rs.arg[2] = c; rs.arg[3] = d; - rs.arg[4] = d; rs.arg[5] = f; - rs.err = 0; - rs.cnt = 0; - rs.hold = 1; - - /* Dispatch signals until all threads respond */ - for (i=libc.threads_minus_1; i; i--) - sigqueue(self->pid, SIGSYSCALL, (union sigval){0}); - while ((i=rs.cnt) < libc.threads_minus_1) { - sigqueue(self->pid, SIGSYSCALL, (union sigval){0}); - __wait(&rs.cnt, 0, i, 1); - } - - /* Handle any lingering signals with no-op */ - __syscall(SYS_rt_sigprocmask, SIG_SETMASK, &set, &set, 8); - - /* Resume other threads' signal handlers and wait for them */ - rs.hold = 0; - __wake(&rs.hold, -1, 0); - while((i=rs.cnt)) __wait(&rs.cnt, 0, i, 1); - - if (rs.err) errno = rs.err, ret = -1; - else ret = syscall(nr, a, b, c, d, e, f); - - UNLOCK(&rs.lock); - return ret; -} - -void __rsyscall_lock() -{ - a_inc(&rs.blocks); - while (rs.lock) __wait(&rs.lock, 0, 1, 1); -} - -void __rsyscall_unlock() -{ - a_dec(&rs.blocks); - if (rs.lock) __wake(&rs.blocks, 1, 1); -} |