Follow @Openwall on Twitter for new release announcements and other news
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date: Wed, 31 Oct 2018 13:38:37 -0700
From: Andy Lutomirski <luto@...capital.net>
To: Peter Zijlstra <peterz@...radead.org>
Cc: Igor Stoppa <igor.stoppa@...il.com>,
 Matthew Wilcox <willy@...radead.org>, Tycho Andersen <tycho@...ho.ws>,
 Kees Cook <keescook@...omium.org>, Mimi Zohar <zohar@...ux.vnet.ibm.com>,
 Dave Chinner <david@...morbit.com>, James Morris <jmorris@...ei.org>,
 Michal Hocko <mhocko@...nel.org>,
 Kernel Hardening <kernel-hardening@...ts.openwall.com>,
 linux-integrity <linux-integrity@...r.kernel.org>,
 linux-security-module <linux-security-module@...r.kernel.org>,
 Igor Stoppa <igor.stoppa@...wei.com>,
 Dave Hansen <dave.hansen@...ux.intel.com>,
 Jonathan Corbet <corbet@....net>, Laura Abbott <labbott@...hat.com>,
 Randy Dunlap <rdunlap@...radead.org>,
 Mike Rapoport <rppt@...ux.vnet.ibm.com>,
 "open list:DOCUMENTATION" <linux-doc@...r.kernel.org>,
 LKML <linux-kernel@...r.kernel.org>, Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH 10/17] prmem: documentation



> On Oct 31, 2018, at 3:11 AM, Peter Zijlstra <peterz@...radead.org> wrote:
> 
>> On Wed, Oct 31, 2018 at 12:15:46AM +0200, Igor Stoppa wrote:
>> On 30/10/2018 23:02, Andy Lutomirski wrote:
> 
>>> But I dislike allowing regular writes in the protected region. We
>>> really only need four write primitives:
>>> 
>>> 1. Just write one value.  Call at any time (except NMI).
>>> 
>>> 2. Just copy some bytes. Same as (1) but any number of bytes.
>>> 
>>> 3,4: Same as 1 and 2 but must be called inside a special rare write
>>> region. This is purely an optimization.
>> 
>> Atomic? RCU?
> 
> RCU can be done, that's not really a problem. Atomics otoh are a
> problem. Having pointers makes them just work.
> 
> Andy; I understand your reason for not wanting them, but I really don't
> want to duplicate everything. Is there something we can do with static
> analysis to make you more comfortable with the pointer thing?

I’m sure we could do something with static analysis, but I think seeing a real use case where all this fanciness makes sense would be good.

And I don’t know if s390 *can* have an efficient implementation that uses pointers. OTOH they have all kinds of magic stuff, so who knows?

Powered by blists - more mailing lists

Confused about mailing lists and their use? Read about mailing lists on Wikipedia and check out these guidelines on proper formatting of your messages.