linux-kernel - Re: [PATCH 1 of 4] mm: add a ptep_modify

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: <4859E8AF.30306@goop.org>
Date:	Wed, 18 Jun 2008 22:03:43 -0700
From:	Jeremy Fitzhardinge <jeremy@...p.org>
To:	benh@...nel.crashing.org
CC:	Linus Torvalds <torvalds@...ux-foundation.org>,
	xen-devel <xen-devel@...ts.xensource.com>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	kvm-devel <kvm-devel@...ts.sourceforge.net>, x86@...nel.org,
	LKML <linux-kernel@...r.kernel.org>,
	Virtualization Mailing List <virtualization@...ts.osdl.org>,
	Hugh Dickins <hugh@...itas.com>, Ingo Molnar <mingo@...e.hu>,
	Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH 1 of 4] mm: add a ptep_modify_prot transaction	abstraction

Benjamin Herrenschmidt wrote:
> On Wed, 2008-06-18 at 17:24 -0700, Linus Torvalds wrote:
>   
>> On Wed, 18 Jun 2008, Jeremy Fitzhardinge wrote:
>>     
>>> Along the lines of:
>>>       
>> Hell no. There's a reason we have a special set_wrprotect() thing. We can 
>> do it more efficiently on native hardware by just clearing the bit 
>> atomically. No need to do the cmpxchg games.
>>     
>
> But we can't batch ... 
>   

Which architecture are you interested in?  If it isn't x86, you can 
probably get anything past Linus ;)

I'll do some measurements to see what effect the batchable 
ptep_set_wrprotect() has on native.  If it's significant, I'll propose 
making it conditional on CONFIG_PARAVIRT.

    J
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/