linux-kernel - Re: race with page_referenced_one->ptep_test_and_clear

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, 04 Oct 2007 21:15:18 -0700
From:	Jeremy Fitzhardinge <jeremy@...p.org>
To:	Rik van Riel <riel@...hat.com>
CC:	Hugh Dickens <hugh@...itas.com>,
	David Rientjes <rientjes@...gle.com>,
	Zachary Amsden <zach@...are.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Rusty Russell <rusty@...tcorp.com.au>, Andi Kleen <ak@...e.de>,
	Keir Fraser <keir@...source.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: race with page_referenced_one->ptep_test_and_clear_young and
 pagetable setup/pulldown

Rik van Riel wrote:
> Either of these two would work.  Another alternative could be to
> let test_and_clear_pte_flags have an exception table entry, where
> we jump right to the next instruction if the instruction clearing
> the flag fails.
>
> That is the essentially variant you need for Xen, except the fast
> path is still exactly the same it is as when running on native
> hardware.
>   

Hm, that wouldn't end up clearing the bit.  You'd need a Xen-specific
exception handler to do that, which would turn the whole thing into
Xen-specific code, and you're back at adding a pv-op.

    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/