Messages in this thread | | | Date | Tue, 10 Nov 2015 15:53:03 +0200 | From | "Kirill A. Shutemov" <> | Subject | Re: [PATCH] x86/mm: fix regression with huge pages on PAE |
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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
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