Prev: [PATCH v3 3/3] init: add support for root devices specified by partition UUID
Next: libata updates
From: Jeremy Fitzhardinge on 4 Aug 2010 14:40
On 07/26/2010 12:45 PM, Jeremy Fitzhardinge wrote:

Ping? I was about to send this to Linus, but I realized that I hadn't
got any x86 acks on it. Any comments/complaints?

Thanks,
J

>
> On x86, a huge pte is logically a pte, but structurally a pmd. Among
> other issues, pmds and ptes overload some flags for multiple uses (PAT
> vs PSE), so it is necessary to know which structural level a pagetable
> entry is in order interpret it properly.
>
> When huge pages are used within a paravirtualized system, it is therefore
> appropriate to use the pmd set of function to operate on them, so that
> the hypervisor can correctly validate the update.
>
> [ Add fix for 32-bit non-PAE with two-level pagetable - Jeremy ]
>
> Signed-off-by: Dave McCracken<dave.mccracken(a)oracle.com>
> Signed-off-by: Jeremy Fitzhardinge<jeremy.fitzhardinge(a)citrix.com>
>
> diff --git a/arch/x86/include/asm/hugetlb.h
> b/arch/x86/include/asm/hugetlb.h
> index 439a9ac..bf88684 100644
> --- a/arch/x86/include/asm/hugetlb.h
> +++ b/arch/x86/include/asm/hugetlb.h
> @@ -36,16 +36,28 @@ static inline void hugetlb_free_pgd_range(struct
> mmu_gather *tlb,
> free_pgd_range(tlb, addr, end, floor, ceiling);
> }
>
> +static inline pte_t huge_ptep_get(pte_t *ptep)
> +{
> + return *ptep;
> +}
> +
> static inline void set_huge_pte_at(struct mm_struct *mm, unsigned
> long addr,
> pte_t *ptep, pte_t pte)
> {
> - set_pte_at(mm, addr, ptep, pte);
> +#if PAGETABLE_LEVELS>= 3
> + set_pmd((pmd_t *)ptep, native_make_pmd(native_pte_val(pte)));
> +#else
> + set_pgd((pgd_t *)ptep, native_make_pgd(native_pte_val(pte)));
> +#endif
> }
>
> static inline pte_t huge_ptep_get_and_clear(struct mm_struct *mm,
> unsigned long addr, pte_t *ptep)
> {
> - return ptep_get_and_clear(mm, addr, ptep);
> + pte_t pte = huge_ptep_get(ptep);
> +
> + set_huge_pte_at(mm, addr, ptep, __pte(0));
> + return pte;
> }
>
> static inline void huge_ptep_clear_flush(struct vm_area_struct *vma,
> @@ -66,19 +78,25 @@ static inline pte_t huge_pte_wrprotect(pte_t pte)
> static inline void huge_ptep_set_wrprotect(struct mm_struct *mm,
> unsigned long addr, pte_t *ptep)
> {
> - ptep_set_wrprotect(mm, addr, ptep);
> + pte_t pte = huge_ptep_get(ptep);
> +
> + pte = pte_wrprotect(pte);
> + set_huge_pte_at(mm, addr, ptep, pte);
> }
>
> static inline int huge_ptep_set_access_flags(struct vm_area_struct *vma,
> unsigned long addr, pte_t *ptep,
> pte_t pte, int dirty)
> {
> - return ptep_set_access_flags(vma, addr, ptep, pte, dirty);
> -}
> + pte_t oldpte = huge_ptep_get(ptep);
> + int changed = !pte_same(oldpte, pte);
>
> -static inline pte_t huge_ptep_get(pte_t *ptep)
> -{
> - return *ptep;
> + if (changed&& dirty) {
> + set_huge_pte_at(vma->vm_mm, addr, ptep, pte);
> + flush_tlb_page(vma, addr);
> + }
> +
> + return changed;
> }
>
> static inline int arch_prepare_hugepage(struct page *page)
>
>
> --
> To unsubscribe from this list: send the line "unsubscribe
> linux-kernel" in
> the body of a message to majordomo(a)vger.kernel.org
> More majordomo info at http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at http://www.tux.org/lkml/
>

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo(a)vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
 | 
Pages: 1
Prev: [PATCH v3 3/3] init: add support for root devices specified by partition UUID
Next: libata updates