From 73b8341376c34b441238bfb2c856cb1044c86661 Mon Sep 17 00:00:00 2001
From: David Howells <dhowells@redhat.com>
Date: Fri, 8 Dec 2006 02:37:52 -0800
Subject: [PATCH] --- yaml --- r: 43629 b: refs/heads/master c:
 39d61db0edb34d60b83c5e0d62d0e906578cc707 h: refs/heads/master i:   43627:
 4edc14b0b25faeb55b6be63e819735c2f4fa016c v: v3

---
 [refs]                           |  2 +-
 trunk/include/asm-generic/page.h | 38 ++++++++++++++++++++++++++++----
 2 files changed, 35 insertions(+), 5 deletions(-)

diff --git a/[refs] b/[refs]
index 888209dcdb5c..688127830878 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 312a0c170945b49f319960afd2e492c05f9dd551
+refs/heads/master: 39d61db0edb34d60b83c5e0d62d0e906578cc707
diff --git a/trunk/include/asm-generic/page.h b/trunk/include/asm-generic/page.h
index a96b5d986b6e..b55052ce2330 100644
--- a/trunk/include/asm-generic/page.h
+++ b/trunk/include/asm-generic/page.h
@@ -4,21 +4,51 @@
 #ifdef __KERNEL__
 #ifndef __ASSEMBLY__
 
-#include <linux/compiler.h>
+#include <linux/log2.h>
 
-/* Pure 2^n version of get_order */
-static __inline__ __attribute_const__ int get_order(unsigned long size)
+/*
+ * non-const pure 2^n version of get_order
+ * - the arch may override these in asm/bitops.h if they can be implemented
+ *   more efficiently than using the arch log2 routines
+ * - we use the non-const log2() instead if the arch has defined one suitable
+ */
+#ifndef ARCH_HAS_GET_ORDER
+static inline __attribute__((const))
+int __get_order(unsigned long size, int page_shift)
 {
+#if BITS_PER_LONG == 32 && defined(ARCH_HAS_ILOG2_U32)
+	int order = __ilog2_u32(size) - page_shift;
+	return order >= 0 ? order : 0;
+#elif BITS_PER_LONG == 64 && defined(ARCH_HAS_ILOG2_U64)
+	int order = __ilog2_u64(size) - page_shift;
+	return order >= 0 ? order : 0;
+#else
 	int order;
 
-	size = (size - 1) >> (PAGE_SHIFT - 1);
+	size = (size - 1) >> (page_shift - 1);
 	order = -1;
 	do {
 		size >>= 1;
 		order++;
 	} while (size);
 	return order;
+#endif
 }
+#endif
+
+/**
+ * get_order - calculate log2(pages) to hold a block of the specified size
+ * @n - size
+ *
+ * calculate allocation order based on the current page size
+ * - this can be used to initialise global variables from constant data
+ */
+#define get_order(n)							\
+(									\
+	__builtin_constant_p(n) ?					\
+	((n < (1UL << PAGE_SHIFT)) ? 0 : ilog2(n) - PAGE_SHIFT) :	\
+	__get_order(n, PAGE_SHIFT)					\
+ )
 
 #endif	/* __ASSEMBLY__ */
 #endif	/* __KERNEL__ */