gstage_pte_index
ptep = &ptep[gstage_pte_index(gstage, addr, current_level)];
pte_t *ptep = &next_ptep[gstage_pte_index(gstage, map->addr, current_level)];
ptep = &next_ptep[gstage_pte_index(gstage, map->addr, current_level)];
ptep = (pte_t *)&next_ptep[gstage_pte_index(gstage, addr, current_level)];
ptep = &ptep[gstage_pte_index(gstage, addr, current_level)];