Messages in this thread | | | Date | Fri, 14 Jun 2019 16:03:22 +0300 | From | "Kirill A. Shutemov" <> | Subject | Re: [PATCH, RFC 09/62] x86/mm: Preserve KeyID on pte_modify() and pgprot_modify() |
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On Fri, Jun 14, 2019 at 11:15:14AM +0200, Peter Zijlstra wrote: > On Wed, May 08, 2019 at 05:43:29PM +0300, Kirill A. Shutemov wrote: > > + * Cast PAGE_MASK to a signed type so that it is sign-extended if > > + * virtual addresses are 32-bits but physical addresses are larger > > + * (ie, 32-bit PAE). > > On 32bit, 'long' is still 32bit, did you want to cast to 'long long' > instead? Ideally we'd use pteval_t here, but I see that is unsigned.
It will be cased implecitly to unsigned long long by '& ((1ULL << __PHYSICAL_MASK_SHIFT) - 1)' and due to sign-extension it will get it right for PAE.
Just to be on safe side, I've re-checked that nothing changed for PAE by the patch using the test below. PTE_PFN_MASK and PTE_PFN_MASK_MAX are identical when compiled with -m32.
> > */ > > -#define _PAGE_CHG_MASK (PTE_PFN_MASK | _PAGE_PCD | _PAGE_PWT | \ > > +#define PTE_PFN_MASK_MAX \ > > + (((signed long)PAGE_MASK) & ((1ULL << __PHYSICAL_MASK_SHIFT) - 1)) > > +#define _PAGE_CHG_MASK (PTE_PFN_MASK_MAX | _PAGE_PCD | _PAGE_PWT | \ > > _PAGE_SPECIAL | _PAGE_ACCESSED | _PAGE_DIRTY | \ > > _PAGE_SOFT_DIRTY | _PAGE_DEVMAP) > > #define _HPAGE_CHG_MASK (_PAGE_CHG_MASK | _PAGE_PSE) >
#include <stdio.h>
typedef unsigned long long u64; typedef u64 pteval_t; typedef u64 phys_addr_t;
#define PAGE_SHIFT 12 #define PAGE_SIZE (1UL << PAGE_SHIFT) #define PAGE_MASK (~(PAGE_SIZE-1)) #define __PHYSICAL_MASK_SHIFT 52 #define __PHYSICAL_MASK ((phys_addr_t)((1ULL << __PHYSICAL_MASK_SHIFT) - 1)) #define PHYSICAL_PAGE_MASK (((signed long)PAGE_MASK) & __PHYSICAL_MASK) #define PTE_PFN_MASK ((pteval_t)PHYSICAL_PAGE_MASK) #define PTE_PFN_MASK_MAX (((signed long)PAGE_MASK) & ((1ULL << __PHYSICAL_MASK_SHIFT) - 1))
int main(void) { printf("PTE_PFN_MASK: %#llx\n", PTE_PFN_MASK); printf("PTE_PFN_MASK_MAX: %#llx\n", PTE_PFN_MASK_MAX);
return 0; } -- Kirill A. Shutemov
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