powerpc: Add pmd_pfn()

This is straightforward for everything except nohash64 where we
indirect through pmd_page().  There must be a better way to do this.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>

arch/powerpc/include/asm/book3s/32/pgtable.h

@@ -372,8 +372,8 @@ static inline void __ptep_set_access_flags(struct vm_area_struct *vma,
 #define __HAVE_ARCH_PTE_SAME
 #define pte_same(A,B)	(((pte_val(A) ^ pte_val(B)) & ~_PAGE_HASHPTE) == 0)
 
-#define pmd_page(pmd)		\
-	pfn_to_page(pmd_val(pmd) >> PAGE_SHIFT)
+#define pmd_pfn(pmd)		(pmd_val(pmd) >> PAGE_SHIFT)
+#define pmd_page(pmd)		pfn_to_page(pmd_pfn(pmd))
 
 /*
  * Encode and decode a swap entry.

arch/powerpc/include/asm/nohash/32/pgtable.h

@@ -349,15 +349,14 @@ static inline int pte_young(pte_t pte)
  * of the pte page.  -- paulus
  */
 #ifndef CONFIG_BOOKE
-#define pmd_page(pmd)		\
-	pfn_to_page(pmd_val(pmd) >> PAGE_SHIFT)
+#define pmd_pfn(pmd)		(pmd_val(pmd) >> PAGE_SHIFT)
 #else
 #define pmd_page_vaddr(pmd)	\
 	((unsigned long)(pmd_val(pmd) & ~(PTE_TABLE_SIZE - 1)))
-#define pmd_page(pmd)		\
-	pfn_to_page((__pa(pmd_val(pmd)) >> PAGE_SHIFT))
+#define pmd_pfn(pmd)		(__pa(pmd_val(pmd)) >> PAGE_SHIFT)
 #endif
 
+#define pmd_page(pmd)		pfn_to_page(pmd_pfn(pmd))
 /*
  * Encode and decode a swap entry.
  * Note that the bits we use in a PTE for representing a swap entry

arch/powerpc/include/asm/nohash/64/pgtable.h

@@ -142,6 +142,7 @@ static inline pte_t pmd_pte(pmd_t pmd)
 #define	pmd_present(pmd)	(!pmd_none(pmd))
 #define pmd_page_vaddr(pmd)	(pmd_val(pmd) & ~PMD_MASKED_BITS)
 extern struct page *pmd_page(pmd_t pmd);
+#define pmd_pfn(pmd)		(page_to_pfn(pmd_page(pmd)))
 
 static inline void pud_set(pud_t *pudp, unsigned long val)
 {