Re: [PATCH v2 22/39] mm: Don't allow write GUPs to shadow stack memory

[Dave Hansen]

On 9/29/22 15:29, Rick Edgecombe wrote:
> @@ -1633,6 +1633,9 @@ static inline bool __pte_access_permitted(unsigned long pteval, bool write)
>  {
>  	unsigned long need_pte_bits = _PAGE_PRESENT|_PAGE_USER;
>  
> +	if (write && (pteval & (_PAGE_RW | _PAGE_DIRTY)) == _PAGE_DIRTY)
> +		return 0;

Do we not have a helper for this?  Seems a bit messy to open-code these
shadow-stack permissions.  Definitely at least needs a comment.