Re: [PATCH v23 15/28] x86/mm: Update maybe_mkwrite() for shadow stack

[Kirill A. Shutemov]

On Tue, Mar 16, 2021 at 08:10:41AM -0700, Yu-cheng Yu wrote:
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index a6c18c5752d6..af805ffde48e 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -997,6 +997,8 @@ static inline pte_t maybe_mkwrite(pte_t pte, struct vm_area_struct *vma)
>  {
>  	if (likely(vma->vm_flags & VM_WRITE))
>  		pte = pte_mkwrite(pte);
> +	else
> +		pte = arch_maybe_mkwrite(pte, vma);
>  	return pte;
>  }

I think it would be cleaner to allow arch code to override maybe_mkwrite()
and maybe_pmd_mkwrite() altogether. Wrap it into #ifndef maybe_mkwrite
here and provide VM_SHSTK-aware version from <asm/pgtable.h>.

-- 
 Kirill A. Shutemov