pmap_change_prot
int pmap_change_prot(vm_offset_t, vm_size_t, vm_prot_t);
int pmap_change_prot(vm_offset_t va, vm_size_t size, vm_prot_t prot);
error = pmap_change_prot((vm_offset_t)ef->address +
error = pmap_change_prot(start, end - start, prot);