arm64: Add contiguous page flag shifts and constants

Add the number of pages required to form a contiguous range,
as well as some supporting constants.
Signed-off-by: Jeremy Linton <jeremy.linton@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

arch/arm64/include/asm/page.h

@@ -20,14 +20,20 @@
 #define __ASM_PAGE_H
 
 /* PAGE_SHIFT determines the page size */
+/* CONT_SHIFT determines the number of pages which can be tracked together  */
 #ifdef CONFIG_ARM64_64K_PAGES
 #define PAGE_SHIFT		16
+#define CONT_SHIFT		5
 #else
 #define PAGE_SHIFT		12
+#define CONT_SHIFT		4
 #endif
-#define PAGE_SIZE		(_AC(1,UL) << PAGE_SHIFT)
+#define PAGE_SIZE		(_AC(1, UL) << PAGE_SHIFT)
 #define PAGE_MASK		(~(PAGE_SIZE-1))
 
+#define CONT_SIZE		(_AC(1, UL) << (CONT_SHIFT + PAGE_SHIFT))
+#define CONT_MASK		(~(CONT_SIZE-1))
+
 /*
  * The idmap and swapper page tables need some space reserved in the kernel
  * image. Both require pgd, pud (4 levels only) and pmd tables to (section)