linux-kernel - Re: [RFC PATCH 0/6] jump label v3

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: <4B0480C4.6080003@zytor.com>
Date:	Wed, 18 Nov 2009 15:18:28 -0800
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Roland McGrath <roland@...hat.com>
CC:	Jason Baron <jbaron@...hat.com>, linux-kernel@...r.kernel.org,
	mingo@...e.hu, mathieu.desnoyers@...ymtl.ca, tglx@...utronix.de,
	rostedt@...dmis.org, andi@...stfloor.org, rth@...hat.com,
	mhiramat@...hat.com
Subject: Re: [RFC PATCH 0/6] jump label v3

On 11/18/2009 03:07 PM, Roland McGrath wrote:
>> 67 66 8D 74 00 (lea si,[si+0]) should work as a 32-bit atomic NOP.  It's
>> not necessarily the fastest, though (I have no data on that.)
>> Similarly, 66 66 66 66 90 should also work.
> 
> We should get all the knowledge like that stored in places like the
> Kconfig.cpu comments near X86_P6_NOP and/or asm/nops.h macros and comments.
> 
> Let's have an ASM_ATOMIC_NOP5 macro in asm/nops.h?  I've lost track of the
> variants, and I'll leave that to you all who are close to the chip people.
> 
> I can't tell if it's the case that there will be kernel configurations
> where there is one known-safe choice but a different choice that's optimal
> if CPU model checks pass.  If so, we could compile in the safe choice and
> then mass-change to the optimal choice at boot time.  (i.e. like the
> alternatives support, but we don't really need to use that too since we
> already have another dedicated table of all the PC addresses to touch.)

Yes, I believe we do something like that already.
	
	-hpa
--
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/