PG_X
if ((opte ^ npte) & PG_X)
if ((opte & PG_X) && (npte & PG_X) == 0 && va == pm->pm_hiexec) {
((prot & PROT_EXEC) ? PG_X : 0) |
protection_codes[PROT_EXEC] = PG_X; /* --x */
protection_codes[PROT_READ | PROT_EXEC] = PG_X; /* -rx */
protection_codes[PROT_WRITE | PROT_EXEC] = PG_RW|PG_X; /* w-x */
protection_codes[PROT_READ | PROT_WRITE | PROT_EXEC] = PG_RW|PG_X; /* wrx */
if (bits & PG_X)
bits |= PG_X;
bits &= ~PG_X;