pte_prot_t
mm_mprotect(vaddr_t startva, size_t size, pte_prot_t prot)
pte_prot_t prot;
mm_enter_pa(paddr_t pa, vaddr_t va, pte_prot_t prot)
mm_reenter_pa(paddr_t pa, vaddr_t va, pte_prot_t prot)