linux-kernel - Re: [PATCH] x86: use WRITE

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 for Android: free password hash cracker in your pocket

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

Message-ID: <20180906192852.GC4816@worktop.programming.kicks-ass.net>
Date:   Thu, 6 Sep 2018 21:28:52 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Dave Hansen <dave.hansen@...el.com>
Cc:     Nadav Amit <namit@...are.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        linux-kernel@...r.kernel.org, Ingo Molnar <mingo@...hat.com>,
        x86@...nel.org, Dave Hansen <dave.hansen@...ux.intel.com>,
        Nadav Amit <nadav.amit@...il.com>,
        Andi Kleen <ak@...ux.intel.com>,
        Josh Poimboeuf <jpoimboe@...hat.com>,
        Michal Hocko <mhocko@...e.com>,
        Vlastimil Babka <vbabka@...e.cz>,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        Andy Lutomirski <luto@...nel.org>
Subject: Re: [PATCH] x86: use WRITE_ONCE() when setting PTEs

On Thu, Sep 06, 2018 at 10:21:38AM -0700, Dave Hansen wrote:
> There's probably a massive number of things that would break if we
> assumed sane 64-bit writes can be observed piecemeal.

Do assume, it has been observed. WRITE_ONCE()/READ_ONCE() are _required_
if you cannot have load/store tearing.