PG_EXEC
kp[prot] |= PG_EXEC | PG_KRE;
up[prot] |= PG_EXEC | PG_KRE | PG_URE;
#define pmap_pte_exec(pte) (*(pte) & PG_EXEC)
#define PG_PROT (ALPHA_PTE_PROT | PG_EXEC | PG_FOE)