mm: add new arch_make_huge_pte() method for tile support

The tile support for multiple-size huge pages requires tagging
the hugetlb PTE with a "super" bit for PTEs that are multiples of
the basic size of a pagetable span.  To set that bit properly
we need to tweak the PTe in make_huge_pte() based on the vma.

This change provides the API for a subsequent tile-specific
change to use.
Reviewed-by: NHillf Danton <dhillf@gmail.com>
Signed-off-by: NChris Metcalf <cmetcalf@tilera.com>

include/linux/hugetlb.h

@@ -284,6 +284,14 @@ static inline unsigned int blocks_per_huge_page(struct hstate *h)
 
 #include <asm/hugetlb.h>
 
+#ifndef arch_make_huge_pte
+static inline pte_t arch_make_huge_pte(pte_t entry, struct vm_area_struct *vma,
+				       struct page *page, int writable)
+{
+	return entry;
+}
+#endif
+
 static inline struct hstate *page_hstate(struct page *page)
 {
 	return size_to_hstate(PAGE_SIZE << compound_order(page));

mm/hugetlb.c

@@ -2213,6 +2213,7 @@ static pte_t make_huge_pte(struct vm_area_struct *vma, struct page *page,
 	}
 	entry = pte_mkyoung(entry);
 	entry = pte_mkhuge(entry);
+	entry = arch_make_huge_pte(entry, vma, page, writable);
 
 	return entry;
 }