semun
union semun semun;
union semun *semun_ptr = NULL;
semun = va_arg(ap, union semun);
semun_ptr = &semun;
syscallarg(union semun *) arg;
union semun arg, *uarg = SCARG(uap, arg);
if ((error = copyin(uarg, &arg, sizeof(union semun))))
int __semctl(int, int, int, union semun *);
syscallarg(union semun *) arg;
union semun arg;