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From: Thomas Gleixner <tglx@linutronix.de>
To: Andi Kleen <ak@suse.de>
Cc: mingo@elte.hu, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] [1/5] CPA: Split static_protections into required_static_prot and advised_static_prot
Date: Sat, 9 Feb 2008 15:56:02 +0100 (CET)	[thread overview]
Message-ID: <alpine.LFD.1.00.0802091525400.3145@apollo.tec.linutronix.de> (raw)
In-Reply-To: <20080208163612.D76421B41AA@basil.firstfloor.org>

On Fri, 8 Feb 2008, Andi Kleen wrote:
> There is a big difference between NX and RO. NX absolutely has to be cleared
> or the kernel will fail while RO just can be set, but does not need to.
> And for a large page area not setting NX if there is a area below 
> it that needs it is essential, while making it ro is optional again.

No, it's not optional. Making the PMD RO will write protect all 4k
PTEs below independent of their setting. So there is the same
restriction as we have with NX.

> This is needed for a followup patch who uses requred_static_prot() for large 
> pages where it is inconvenient to check all pages. 

> No behaviour change in this patch.
> 
> [Lines > 80 characters are changed in followup patch]

ROTFL.

	tglx

  reply	other threads:[~2008-02-09 14:56 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-02-08 16:36 [PATCH] [0/5] pageattr protection patchkit v2 for the latest kernel Andi Kleen
2008-02-08 16:36 ` [PATCH] [1/5] CPA: Split static_protections into required_static_prot and advised_static_prot Andi Kleen
2008-02-09 14:56   ` Thomas Gleixner [this message]
2008-02-09 15:13     ` Andi Kleen
2008-02-09 15:50       ` Thomas Gleixner
2008-02-09 16:39         ` Andi Kleen
2008-02-09 17:09           ` Thomas Gleixner
2008-02-10  9:39             ` Andi Kleen
2008-02-08 16:36 ` [PATCH] [2/5] Support range checking for required/advisory protections Andi Kleen
2008-02-08 16:36 ` [PATCH] [3/5] CPA: Make advised protection check truly advisory Andi Kleen
2008-02-09 15:38   ` Thomas Gleixner
2008-02-09 16:56     ` Andi Kleen
2008-02-09 17:38       ` Thomas Gleixner
2008-02-10  9:19         ` Andi Kleen
2008-02-10 16:50           ` Thomas Gleixner
2008-02-08 16:36 ` [PATCH] [4/5] Don't use inline for the protection checks Andi Kleen
2008-02-08 16:36 ` [PATCH] [5/5] Switch i386 early boot page table initialization over to use required_static_prot() Andi Kleen
  -- strict thread matches above, loose matches on Subject: below --
2008-02-08 13:27 [PATCH] [1/5] CPA: Split static_protections into required_static_prot and advised_static_prot Andi Kleen

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