thread_shstk
struct thread_shstk shstk;
struct thread_shstk *shstk = ¤t->thread.shstk;
memset(¤t->thread.shstk, 0, sizeof(struct thread_shstk));
struct thread_shstk *shstk = &tsk->thread.shstk;
struct thread_shstk *shstk = &tsk->thread.shstk;