• A
    PAGE_ALIGN(): correctly handle 64-bit values on 32-bit architectures · 27ac792c
    Andrea Righi 提交于
    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: NAndrea Righi <righi.andrea@gmail.com>
    Cc: <linux-arch@vger.kernel.org>
    Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
    27ac792c
iso.c 13.0 KB