linux-kernel - Re: 4.4-rc5: ugly warn on: 5 W+X pages found

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Date:	Tue, 15 Dec 2015 15:08:37 +0100
From:	Pavel Machek <pavel@....cz>
To:	Arjan van de Ven <arjan@...ux.intel.com>
Cc:	Andy Lutomirski <luto@...capital.net>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Borislav Petkov <bp@...en8.de>,
	kernel list <linux-kernel@...r.kernel.org>,
	Stephen Smalley <sds@...ho.nsa.gov>,
	Brian Gerst <brgerst@...il.com>,
	Denys Vlasenko <dvlasenk@...hat.com>,
	Peter Anvin <hpa@...or.com>, Mike Galbraith <efault@....de>,
	Peter Zijlstra <peterz@...radead.org>,
	Thomas Gleixner <tglx@...utronix.de>
Subject: Re: 4.4-rc5: ugly warn on: 5 W+X pages found

On Tue 2015-12-15 05:26:00, Arjan van de Ven wrote:
> On 12/14/2015 11:56 PM, Pavel Machek wrote:
> >On Mon 2015-12-14 13:24:08, Arjan van de Ven wrote:
> >>
> >>>That's weird.  The only API to do that seems to be manually setting
> >>>kmap_prot to _PAGE_KERNEL_EXEC, and nothing does that.  (Why is
> >>>kmap_prot a variable on x86 at all?  It has exactly one writer, and
> >>>that's the code that initializes it in the first place.  Shouldn't we
> >>>#define kmap_prot _PAGE_KERNEL?
> >>
> >>iirc it changes based on runtime detection of NX capability
> >
> >Huh. Is it possible that core duo is so old that it has no NX?
> 
> really stupid question I guess, but is PAE on ?
> (64 bit pagetables are required for NX)
>

CONFIG_X86_PAE=y

pavel@duo:/data/l/linux$ cat /proc/cpuinfo  | grep pae
flags			     : fpu vme de pse tsc msr pae mce cx8 apic
sep mtrr pge mca cmov clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe
nx constant_tsc arch_perfmon bts aperfmperf pni monitor vmx est tm2
xtpr pdcm dtherm

But it still says:

address sizes	: 32 bits physical, 32 bits virtual

I thought pae would be 36bit virtual?

I'm attaching /proc/config.gz..
									Pavel

-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

Download attachment "config.gz" of type "application/gzip" (24398 bytes)