linux-kernel - Re: [PATCHv2 1/3] x86/mm: Provide pmdp

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]

Message-ID: <20170621104016.GB10220@e104818-lin.cambridge.arm.com>
Date:   Wed, 21 Jun 2017 11:40:17 +0100
From:   Catalin Marinas <catalin.marinas@....com>
To:     "Kirill A. Shutemov" <kirill@...temov.name>
Cc:     "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Vlastimil Babka <vbabka@...e.cz>,
        Vineet Gupta <vgupta@...opsys.com>,
        Russell King <linux@...linux.org.uk>,
        Will Deacon <will.deacon@....com>,
        Ralf Baechle <ralf@...ux-mips.org>,
        "David S. Miller" <davem@...emloft.net>,
        "Aneesh Kumar K . V" <aneesh.kumar@...ux.vnet.ibm.com>,
        Martin Schwidefsky <schwidefsky@...ibm.com>,
        Heiko Carstens <heiko.carstens@...ibm.com>,
        Andrea Arcangeli <aarcange@...hat.com>,
        linux-arch@...r.kernel.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, Ingo Molnar <mingo@...nel.org>,
        "H . Peter Anvin" <hpa@...or.com>,
        Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCHv2 1/3] x86/mm: Provide pmdp_establish() helper

On Wed, Jun 21, 2017 at 12:53:03PM +0300, Kirill A. Shutemov wrote:
> On Tue, Jun 20, 2017 at 04:54:38PM +0100, Catalin Marinas wrote:
> > For arm64, I don't see the point of a cmpxchg, so something like below
> > would do (it needs proper testing though):
> 
> Right. cmpxchg is required for x86 PAE, as it has sizeof(pmd_t) >
> sizeof(long). We don't have 8-byte xchg() there.
> 
> Thanks, for the patch. I assume, I can use your signed-off-by, right?

Yes. And maybe some text (well, I just copied yours):

---------------8<--------------
arm64: Provide pmdp_establish() helper

We need an atomic way to setup pmd page table entry, avoiding races with
CPU setting dirty/accessed bits. This is required to implement
pmdp_invalidate() that doesn't lose these bits.

Signed-off-by: Catalin Marinas <catalin.marinas@....com>
---------------8<--------------

> Any chance you could help me with arm too?

I'll have a look.

-- 
Catalin