mm: add PHYS_PFN, use it in __phys_to_pfn()
__phys_to_pfn and __pfn_to_phys are symmetric, PHYS_PFN and PFN_PHYS are
semmetric:
- y = (phys_addr_t)x << PAGE_SHIFT
- y >> PAGE_SHIFT = (phys_add_t)x
- (unsigned long)(y >> PAGE_SHIFT) = x
[akpm@linux-foundation.org: use macro arg name `x']
[arnd@arndb.de: include linux/pfn.h for PHYS_PFN definition]
Signed-off-by: Chen Gang <gang.chen.5i5j@gmail.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/include/asm-generic/memory_model.h b/include/asm-generic/memory_model.h
index 4b4b056..5148150 100644
--- a/include/asm-generic/memory_model.h
+++ b/include/asm-generic/memory_model.h
@@ -1,6 +1,8 @@
#ifndef __ASM_MEMORY_MODEL_H
#define __ASM_MEMORY_MODEL_H
+#include <linux/pfn.h>
+
#ifndef __ASSEMBLY__
#if defined(CONFIG_FLATMEM)
@@ -72,7 +74,7 @@
/*
* Convert a physical address to a Page Frame Number and back
*/
-#define __phys_to_pfn(paddr) ((unsigned long)((paddr) >> PAGE_SHIFT))
+#define __phys_to_pfn(paddr) PHYS_PFN(paddr)
#define __pfn_to_phys(pfn) PFN_PHYS(pfn)
#define page_to_pfn __page_to_pfn