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From: Ingo Molnar <mingo@kernel.org>
To: Jan Beulich <JBeulich@suse.com>
Cc: mingo@elte.hu, tglx@linutronix.de,
	Boris Ostrovsky <boris.ostrovsky@oracle.com>,
	Juergen Gross <jgross@suse.com>,
	linux-kernel@vger.kernel.org, hpa@zytor.com
Subject: Re: [PATCH RESEND] x86: consider effective protection attributes in W+X check
Date: Tue, 20 Feb 2018 09:32:11 +0100	[thread overview]
Message-ID: <20180220083211.s5wr5r7ocpzzizgp@gmail.com> (raw)
In-Reply-To: <5A8BE8C602000078001A9729@prv-mh.provo.novell.com>


* Jan Beulich <JBeulich@suse.com> wrote:

> >>> On 20.02.18 at 09:10, <mingo@kernel.org> wrote:
> > * Jan Beulich <JBeulich@suse.com> wrote:
> >> Using just the leaf page table entry flags would cause a false warning
> >> in case _PAGE_RW is clear or _PAGE_NX is set in a higher level entry.
> > 
> > Under what circumstances did you see false positive warnings?
> 
> As explained in the 2-patch series this was originally part of, there
> continues to be that W+X warning when running under Xen, as
> commit 2cc42bac1c ("x86-64/Xen: eliminate W+X mappings") has
> to make the necessary adjustment in L2 rather than L1 (the
> reason is explained there). I.e. _PAGE_RW is clear there in L1,
> but _PAGE_NX is set in L2.

This would make an excellent additional paragraph of the v2 changelog.

Thanks,

	Ingo

  reply	other threads:[~2018-02-20  8:32 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-02-20  7:41 Jan Beulich
2018-02-20  8:10 ` Ingo Molnar
2018-02-20  8:22   ` Jan Beulich
2018-02-20  8:32     ` Ingo Molnar [this message]
2018-02-20  8:37     ` Ingo Molnar
2018-02-20  8:43       ` Jan Beulich
2018-02-20 10:17         ` Ingo Molnar
2018-02-20 11:09           ` Jan Beulich

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