linux-kernel - Re: [PATCH] i386: improve double fault handling

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]

Date:	Thu, 24 Jul 2008 09:24:25 -0400
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Jan Beulich <jbeulich@...ell.com>
CC:	Joerg Roedel <joro@...tes.org>, mingo@...e.hu,
	Andi Kleen <andi@...stfloor.org>, tglx@...utronix.de,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] i386: improve double fault handling

Jan Beulich wrote:
>>>> Joerg Roedel <joro@...tes.org> 23.07.08 23:43 >>>
>> On Fri, Jul 18, 2008 at 01:30:42PM +0100, Jan Beulich wrote:
>>> Make the double fault handler use CPU-specific stacks. Add some
>>> abstraction to simplify future change of other exception handlers to go
>>> through task gates.
>> What is the benefit of exception handlers going through task gates?
>> Hardware task switches are not very well supported in virtualization
>> (e.g. its has issues in KVM and is also not in Xen for a long time).
> 
> The main goal is to get to a different stack. While at present this is done
> only for the double fault, I think generally NMI and MCE should also do
> so, as they may be caused by a stack access (see x86-64, which runs
> them on IST stacks), and hence continuing to run on that same stack
> may not allow the exception to be handled.

NMI, MCE and #DF are the obvious candidates.

Now, keep in mind TSSes have to be prepared per-CPU, since they get 
marked "busy" when in use, so it's a bit of a nontrivial undertaking.

	-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/