lkml.org 
[lkml]   [2015]   [Nov]   [10]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [PATCH] x86/mm: fix regression with huge pages on PAE
    On Tue, Nov 10, 2015 at 01:34:29PM +0100, Borislav Petkov wrote:
    > On Tue, Nov 10, 2015 at 01:18:10AM +0200, Kirill A. Shutemov wrote:
    > > diff --git a/arch/x86/include/asm/pgtable_types.h b/arch/x86/include/asm/pgtable_types.h
    > > index dd5b0aa9dd2f..c1e797266ce9 100644
    > > --- a/arch/x86/include/asm/pgtable_types.h
    > > +++ b/arch/x86/include/asm/pgtable_types.h
    > > @@ -279,17 +279,14 @@ static inline pmdval_t native_pmd_val(pmd_t pmd)
    > > static inline pudval_t pud_pfn_mask(pud_t pud)
    > > {
    > > if (native_pud_val(pud) & _PAGE_PSE)
    > > - return PUD_PAGE_MASK & PHYSICAL_PAGE_MASK;
    > > + return ~((1ULL << PUD_SHIFT) - 1) & PHYSICAL_PAGE_MASK;
    >
    > In file included from ./arch/x86/include/asm/boot.h:5:0,
    > from ./arch/x86/boot/boot.h:26,
    > from arch/x86/realmode/rm/wakemain.c:2:
    > ./arch/x86/include/asm/pgtable_types.h: In function ‘pud_pfn_mask’:
    > ./arch/x86/include/asm/pgtable_types.h:282:10: warning: large integer implicitly truncated to unsigned type [-Woverflow]
    > return ~((1ULL << PUD_SHIFT) - 1) & PHYSICAL_PAGE_MASK;
    > ^
    > ./arch/x86/include/asm/pgtable_types.h: In function ‘pmd_pfn_mask’:
    > ./arch/x86/include/asm/pgtable_types.h:300:10: warning: large integer implicitly truncated to unsigned type [-Woverflow]
    > return ~((1ULL << PMD_SHIFT) - 1) & PHYSICAL_PAGE_MASK;
    > ^
    > In file included from ./arch/x86/include/asm/boot.h:5:0,
    > from arch/x86/realmode/rm/../../boot/boot.h:26,
    > from arch/x86/realmode/rm/../../boot/video-mode.c:18,
    > from arch/x86/realmode/rm/video-mode.c:1:
    > ./arch/x86/include/asm/pgtable_types.h: In function ‘pud_pfn_mask’:
    > ./arch/x86/include/asm/pgtable_types.h:282:10: warning: large integer implicitly truncated to unsigned type [-Woverflow]
    > return ~((1ULL << PUD_SHIFT) - 1) & PHYSICAL_PAGE_MASK;
    > ^
    > ...
    >
    > That's a 64-bit config.

    Oh.. pmdval_t/pudval_t is 'unsinged long' on 64 bit. But realmode code
    uses -m16 which makes 'unsigned long' 32-bit therefore truncation warning.

    These helpers not really used in realmode code. I see few ways out:

    - convert helpers to macros to avoid their translation;

    - wrap the code into not-for-realmode ifdef. (Do we have any?);

    - convert pudval_t/pmdval_t to u64 for 64-bit. I'm not sure what side
    effects would it have.

    Any opinions?

    --
    Kirill A. Shutemov


    \
     
     \ /
      Last update: 2015-11-10 15:01    [W:3.211 / U:0.460 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site