[PATCH] ppc32: Allow adjust of pfn offset in pte

Allow the pfn to be offset by more than just PAGE_SHIFT in the pte.  Today,
PAGE_SHIFT tends to allow us to have 12-bits of flags in the pte.  In the
future if we have a larger pte we can allocate more bits for flags by
offsetting the pfn even further.

Signed-off-by: Kumar Gala <kumar.gala@freescale.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 7 insertions, 2 deletions

diff --git a/include/asm-ppc/pgtable.h b/include/asm-ppc/pgtable.h
index 2e88cd9feffe..e135b4aba9fc 100644
--- a/include/asm-ppc/pgtable.h
+++ b/include/asm-ppc/pgtable.h
@@ -431,10 +431,15 @@ extern unsigned long bad_call_to_PMD_PAGE_SIZE(void);
  * Conversions between PTE values and page frame numbers.
  */
 
-#define pte_pfn(x)              (pte_val(x) >> PAGE_SHIFT)
+/* in some case we want to additionaly adjust where the pfn is in the pte to
+ * allow room for more flags */
+#define PFN_SHIFT_OFFSET        (PAGE_SHIFT)
+
+#define pte_pfn(x)              (pte_val(x) >> PFN_SHIFT_OFFSET)
 #define pte_page(x)             pfn_to_page(pte_pfn(x))
 
-#define pfn_pte(pfn, prot)      __pte(((pte_t)(pfn) << PAGE_SHIFT) | pgprot_val(prot))
+#define pfn_pte(pfn, prot)      __pte(((pte_basic_t)(pfn) << PFN_SHIFT_OFFSET) |\
+                                        pgprot_val(prot))
 #define mk_pte(page, prot)      pfn_pte(page_to_pfn(page), prot)
 
 /*