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x86: fix pte_flags() to only return flags, fix lguest (updated)

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(Jeremy said:
	rusty: use PTE_MASK
	rusty: use PTE_MASK
	rusty: use PTE_MASK
 When I asked:
	jsgf: does that include the NX flag?
 He responded eloquently:
	rusty: use PTE_MASK
	rusty: use PTE_MASK
	yes, it's the official constant of masking flags out of ptes
)

Change a15af1c9ea 'x86/paravirt: add
pte_flags to just get pte flags' removed lguest's private pte_flags()
in favor of a generic one.

Unfortunately, the generic one doesn't filter out the non-flags bits:
this results in lguest creating corrupt shadow page tables and blowing
up host memory.

Since noone is supposed to use the pfn part of pte_flags(), it seems
safest to always do the filtering.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Acked-by: Jeremy Fitzhardinge <jeremy@goop.org>
Signed-off-and-morning-tea-spilled-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Rusty Russell 2008-07-22 15:40:46 +10:00 committed by Ingo Molnar
parent 988781dc3e
commit c2e3277f87
3 changed files with 10 additions and 2 deletions
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2
arch/x86/kernel/paravirt.c
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@ -443,7 +443,7 @@ struct pv_mmu_ops pv_mmu_ops = {
#endif /* PAGETABLE_LEVELS >= 3 */
.pte_val = native_pte_val,
.pte_flags = native_pte_val,
.pte_flags = native_pte_flags,
.pgd_val = native_pgd_val,
.make_pte = native_make_pte,

7
include/asm-x86/page.h
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@ -144,6 +144,11 @@ static inline pteval_t native_pte_val(pte_t pte)
return pte.pte;
}
static inline pteval_t native_pte_flags(pte_t pte)
{
return native_pte_val(pte) & ~PTE_MASK;
}
#define pgprot_val(x) ((x).pgprot)
#define __pgprot(x) ((pgprot_t) { (x) } )
@ -165,7 +170,7 @@ static inline pteval_t native_pte_val(pte_t pte)
#endif
#define pte_val(x) native_pte_val(x)
#define pte_flags(x) native_pte_val(x)
#define pte_flags(x) native_pte_flags(x)
#define __pte(x) native_make_pte(x)
#endif /* CONFIG_PARAVIRT */

3
include/asm-x86/paravirt.h
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@ -1088,6 +1088,9 @@ static inline pteval_t pte_flags(pte_t pte)
ret = PVOP_CALL1(pteval_t, pv_mmu_ops.pte_flags,
pte.pte);
#ifdef CONFIG_PARAVIRT_DEBUG
BUG_ON(ret & PTE_MASK);
#endif
return ret;
}