linux-kernel - Re: [PATCH v7 1/3] mm/madvise: introduce clear_young_dirty

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date: Wed, 17 Apr 2024 17:01:18 +0800
From: Lance Yang <ioworker0@...il.com>
To: David Hildenbrand <david@...hat.com>
Cc: 21cnbao@...il.com, akpm@...ux-foundation.org, fengwei.yin@...el.com, 
	linux-kernel@...r.kernel.org, linux-mm@...ck.org, mhocko@...e.com, 
	minchan@...nel.org, peterx@...hat.com, ryan.roberts@....com, 
	shy828301@...il.com, songmuchun@...edance.com, wangkefeng.wang@...wei.com, 
	xiehuan09@...il.com, zokeefe@...gle.com
Subject: Re: [PATCH v7 1/3] mm/madvise: introduce clear_young_dirty_ptes()
 batch helper

On Wed, Apr 17, 2024 at 4:19 PM David Hildenbrand <david@...hat.com> wrote:
>
> On 17.04.24 07:04, Lance Yang wrote:
> > Hey David, Ryan,
> >
> > How about this change?
> >
> > static inline void clear_young_dirty_ptes(struct vm_area_struct *vma,
> >                                         unsigned long addr, pte_t *ptep,
> >                                         unsigned int nr, cydp_t flags)
> > {
> >       if (flags == CYDP_CLEAR_YOUNG) {
> >               for (;;) {
> >                       ptep_test_and_clear_young(vma, addr, ptep);
> >                       if (--nr == 0)
> >                               break;
> >                       ptep++;
> >                       addr += PAGE_SIZE;
> >               }
> >               return;
> >       }
> >
> >       pte_t pte;
> >
> >       for (;;) {
> >               pte = ptep_get_and_clear(vma->vm_mm, addr, ptep);
> >
> >               if (flags & CYDP_CLEAR_YOUNG)
> >                       pte = pte_mkold(pte);
> >               if (flags & CYDP_CLEAR_DIRTY)
> >                       pte = pte_mkclean(pte);
> >
> >               if (--nr == 0)
> >                       break;
> >               ptep++;
> >               addr += PAGE_SIZE;
> >       }
> > }
>
> Likely it might be best to just KIS for now and leave it as is. The
> compiler should optimize out based on flags already, that's what I ignored.

Got it. Let's keep it as is for now :)

Thanks,
Lance

>
> --
> Cheers,
>
> David / dhildenb
>