ADDR_MAKE_CANONICAL
frame->pc = ADDR_MAKE_CANONICAL(tf->tf_elr);
frame.pc = ADDR_MAKE_CANONICAL(td->td_pcb->pcb_x[PCB_LR]);
fault_va = ADDR_MAKE_CANONICAL(far);
frame->pc = ADDR_MAKE_CANONICAL(((uintptr_t *)fp)[1] - 4);