x86: clean up differences between 64-bit and 32-bit

static int

__change_page_attr(unsigned long address, struct page *page, pgprot_t prot)

{

	pgprot_t ref_prot2, oldprot;

	struct page *kpte_page;

	int level, err = 0;

	pte_t *kpte;

	BUG_ON(PageHighMem(page));

repeat:

	kpte = lookup_address(address, &level);

	if (!kpte)

		return 0;

	kpte_page = virt_to_page(kpte);

	oldprot = pte_pgprot(*kpte);

	BUG_ON(PageLRU(kpte_page));

	BUG_ON(PageCompound(kpte_page));

	prot = canon_pgprot(prot);

	/*

	 * Better fail early if someone sets the kernel text to NX.

	 * Does not cover __inittext

	 */

	BUG_ON(address >= (unsigned long)&_text &&

		address < (unsigned long)&_etext &&

	       (pgprot_val(prot) & _PAGE_NX));

	if (level == 4) {

		set_pte_atomic(kpte, mk_pte(page, prot));

		set_pte_atomic(kpte, mk_pte(page, canon_pgprot(prot)));

	} else {

		err = split_large_page(kpte, address);

		if (!err)

			goto repeat;

	}

	return err;

}