[PATCH mm 1/2] mm: Define pte_index as macro for x86

[Arjun Roy <arjunroy.kdev@gmail.com>]

From: Arjun Roy <arjunroy@google.com>

pte_index() is either defined as a macro (e.g. sparc64) or as an
inlined function (e.g. x86). vm_insert_pages() depends on pte_index
but it is not defined on all platforms (e.g. m68k).

To fix compilation of vm_insert_pages() on architectures not providing
pte_index(), we perform the following fix:

0. For platforms where it is meaningful, and defined as a macro, no
   change is needed.
1. For platforms where it is meaningful and defined as an inlined
   function, and we want to use it with vm_insert_pages(), we define
   a degenerate macro of the form:  #define pte_index pte_index
2. vm_insert_pages() checks for the existence of a pte_index macro
   definition. If found, it implements a batched insert. If not found,
   it devolves to calling vm_insert_page() in a loop.

This patch implements step 1 for x86.

Signed-off-by: Arjun Roy <arjunroy@google.com>

---
 arch/x86/include/asm/pgtable.h | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h
index 7e118660bbd9..6658c04bce83 100644
--- a/arch/x86/include/asm/pgtable.h
+++ b/arch/x86/include/asm/pgtable.h
@@ -823,6 +823,9 @@ static inline unsigned long pmd_index(unsigned long address)
  */
 #define mk_pte(page, pgprot)   pfn_pte(page_to_pfn(page), (pgprot))
 
+/* Degenerative definition so we can test if pte_index is defined for arch. */
+#define pte_index pte_index
+
 /*
  * the pte page can be thought of an array like this: pte_t[PTRS_PER_PTE]
  *
-- 
2.25.1.481.gfbce0eb801-goog