PAGE_ALIGN(): correctly handle 64-bit values on 32-bit architectures

On 32-bit architectures PAGE_ALIGN() truncates 64-bit values to the 32-bit
boundary. For example:

	u64 val = PAGE_ALIGN(size);

always returns a value < 4GB even if size is greater than 4GB.

The problem resides in PAGE_MASK definition (from include/asm-x86/page.h for
example):

#define PAGE_SHIFT      12
#define PAGE_SIZE       (_AC(1,UL) << PAGE_SHIFT)
#define PAGE_MASK       (~(PAGE_SIZE-1))
...
#define PAGE_ALIGN(addr)       (((addr)+PAGE_SIZE-1)&PAGE_MASK)

The "~" is performed on a 32-bit value, so everything in "and" with
PAGE_MASK greater than 4GB will be truncated to the 32-bit boundary.
Using the ALIGN() macro seems to be the right way, because it uses
typeof(addr) for the mask.

Also move the PAGE_ALIGN() definitions out of include/asm-*/page.h in
include/linux/mm.h.

See also lkml discussion: http://lkml.org/lkml/2008/6/11/237

[akpm@linux-foundation.org: fix drivers/media/video/uvc/uvc_queue.c]
[akpm@linux-foundation.org: fix v850]
[akpm@linux-foundation.org: fix powerpc]
[akpm@linux-foundation.org: fix arm]
[akpm@linux-foundation.org: fix mips]
[akpm@linux-foundation.org: fix drivers/media/video/pvrusb2/pvrusb2-dvb.c]
[akpm@linux-foundation.org: fix drivers/mtd/maps/uclinux.c]
[akpm@linux-foundation.org: fix powerpc]
Signed-off-by: Andrea Righi <righi.andrea@gmail.com>
Cc: <linux-arch@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 1 insertions, 4 deletions

diff --git a/include/asm-mips/page.h b/include/asm-mips/page.h
index 494f00ba9541..fe7a88ea066e 100644
--- a/include/asm-mips/page.h
+++ b/include/asm-mips/page.h
@@ -137,9 +137,6 @@ typedef struct { unsigned long pgprot; } pgprot_t;
 
 #endif /* !__ASSEMBLY__ */
 
-/* to align the pointer to the (next) page boundary */
-#define PAGE_ALIGN(addr)        (((addr) + PAGE_SIZE - 1) & PAGE_MASK)
-
 /*
  * __pa()/__va() should be used only during mem init.
  */
diff --git a/include/asm-mips/processor.h b/include/asm-mips/processor.h
index 58cbac5a64e4..a1e4453469f9 100644
--- a/include/asm-mips/processor.h
+++ b/include/asm-mips/processor.h
@@ -45,7 +45,7 @@ extern unsigned int vced_count, vcei_count;
  * This decides where the kernel will search for a free chunk of vm
  * space during mmap's.
  */
-#define TASK_UNMAPPED_BASE      (PAGE_ALIGN(TASK_SIZE / 3))
+#define TASK_UNMAPPED_BASE      ((TASK_SIZE / 3) & ~(PAGE_SIZE))
 #endif
 
 #ifdef CONFIG_64BIT