SSTATUS_FS_CLEAN
p->p_addr->u_pcb.pcb_tf->tf_sstatus |= SSTATUS_FS_CLEAN;
__asm volatile ("csrs sstatus, %0" :: "r"(SSTATUS_FS_CLEAN));
(tf->tf_sstatus & SSTATUS_FS_MASK) == SSTATUS_FS_CLEAN)
p->p_addr->u_pcb.pcb_tf->tf_sstatus |= SSTATUS_FS_CLEAN;