linux-kernel - Re: [PATCH v2 33/35] arm64/mm: attempt speculative mm faults first

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: <Yfj2G3oOC6cZx0IL@kernel.org>
Date:   Tue, 1 Feb 2022 10:58:03 +0200
From:   Mike Rapoport <rppt@...nel.org>
To:     Michel Lespinasse <michel@...pinasse.org>
Cc:     Linux-MM <linux-mm@...ck.org>, linux-kernel@...r.kernel.org,
        Andrew Morton <akpm@...ux-foundation.org>, kernel-team@...com,
        Laurent Dufour <ldufour@...ux.ibm.com>,
        Jerome Glisse <jglisse@...gle.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Michal Hocko <mhocko@...e.com>,
        Vlastimil Babka <vbabka@...e.cz>,
        Davidlohr Bueso <dave@...olabs.net>,
        Matthew Wilcox <willy@...radead.org>,
        Liam Howlett <liam.howlett@...cle.com>,
        Rik van Riel <riel@...riel.com>,
        Paul McKenney <paulmck@...nel.org>,
        Song Liu <songliubraving@...com>,
        Suren Baghdasaryan <surenb@...gle.com>,
        Minchan Kim <minchan@...gle.com>,
        Joel Fernandes <joelaf@...gle.com>,
        David Rientjes <rientjes@...gle.com>,
        Axel Rasmussen <axelrasmussen@...gle.com>,
        Andy Lutomirski <luto@...nel.org>
Subject: Re: [PATCH v2 33/35] arm64/mm: attempt speculative mm faults first

On Mon, Jan 31, 2022 at 12:07:29AM -0800, Michel Lespinasse wrote:
> On Sun, Jan 30, 2022 at 11:13:26AM +0200, Mike Rapoport wrote:
> > The speculative page fault implementation here (and for PowerPC as well)
> > looks very similar to x86. Can we factor it our rather than copy 3 (or
> > more) times?
> 
> In each arch, the speculative code was written along the lines of the
> existing non-speculative code, so that behavior would be unchanged
> when speculation succeeds.
> 
> Now each arch's existing, non-speculative code paths are quite similar,
> but they do have small differences as to how they implement various
> permission checks, protection keys and the like. The same small
> differences end up being reflected in the new speculative code paths.
> 
> I agree it would be nice if this code could be unified between archs,
> but IMO this should start with the existing non-speculative code -
> I don't think it would make sense to try unifying the new speculative
> code while trying to follow the behavior of the non-unified old
> non-speculative code paths...

Then maybe this unification can be done as the ground work for the
speculative page fault handling?

-- 
Sincerely yours,
Mike.