Re: [PATCH v23 11/28] x86/mm: Update pte_modify for _PAGE_COW

Kirill A. Shutemov
2021-03-22T11:31:16Z

On Tue, Mar 16, 2021 at 08:10:37AM -0700, Yu-cheng Yu wrote:
> The read-only and Dirty PTE has been used to indicate copy-on-write pages.
> However, newer x86 processors also regard a read-only and Dirty PTE as a
> shadow stack page. In order to separate the two, the software-defined
> _PAGE_COW is created to replace _PAGE_DIRTY for the copy-on-write case, and
> pte_*() are updated.
>
> Pte_modify() changes a PTE to 'newprot', but it doesn't use the pte_*().
> Introduce fixup_dirty_pte(), which sets a dirty PTE, based on _PAGE_RW,
> to either _PAGE_DIRTY or _PAGE_COW.
>
> Apply the same changes to pmd_modify().
>
> Signed-off-by: Yu-cheng Yu <yu-cheng.yu@intel.com>

Reviewed-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>

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Kirill A. Shutemov