Re: [PATCH v28 16/32] x86/mm: Update maybe_mkwrite() for shadow stack

["Yu, Yu-cheng" <yu-cheng.yu@xxxxxxxxx>]

On 8/16/2021 10:03 AM, Borislav Petkov wrote:
> On Thu, Jul 22, 2021 at 01:52:03PM -0700, Yu-cheng Yu wrote:
> > diff --git a/arch/x86/mm/pgtable.c b/arch/x86/mm/pgtable.c
> > index 3364fe62b903..ba449d12ec32 100644
> > --- a/arch/x86/mm/pgtable.c
> > +++ b/arch/x86/mm/pgtable.c
> > @@ -610,6 +610,26 @@ int pmdp_clear_flush_young(struct vm_area_struct *vma,
> >   }
> >   #endif
> >   
> > +pte_t maybe_mkwrite(pte_t pte, struct vm_area_struct *vma)
> > +{
> > +	if (likely(vma->vm_flags & VM_WRITE))
> > +		pte = pte_mkwrite(pte);
> > +	else if (likely(vma->vm_flags & VM_SHADOW_STACK))
> > +		pte = pte_mkwrite_shstk(pte);
> > +	return pte;
> > +}
> > +
> > +#ifdef CONFIG_TRANSPARENT_HUGEPAGE
> > +pmd_t maybe_pmd_mkwrite(pmd_t pmd, struct vm_area_struct *vma)
> > +{
> > +	if (likely(vma->vm_flags & VM_WRITE))
> > +		pmd = pmd_mkwrite(pmd);
> > +	else if (likely(vma->vm_flags & VM_SHADOW_STACK))
> > +		pmd = pmd_mkwrite_shstk(pmd);
>
> What are all those likely()ies here for?

I will remove those.

Thanks,
Yu-cheng