linux-kernel - Re: [tip:x86/mm] x86, mm: NX protection for kernel data

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Date:	Tue, 2 Mar 2010 13:03:14 -0500
From:	Siarhei Liakh <sliakh.lkml@...il.com>
To:	castet.matthieu@...e.fr
Cc:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [tip:x86/mm] x86, mm: NX protection for kernel data

On Tue, Mar 2, 2010 at 12:51 PM, Siarhei Liakh <sliakh.lkml@...il.com> wrote:
>>> At this point I need some help and guidance on how to track down what
>>> exactly happens there, as I am not very familiar with what goes into
>>> .data and why are we trying to execute it.
>> Can't you add debug printk in the fault handler before any exception processing
>>
>> Something like that.
>
> That does not really give any additional information. The message does
> not show up in the output and the stack trace says that we are somehow
> ended up in doublefault_fn.

Forgot to add one more thing: it looks like fault on instruction
prefetch is already taken care of in fault handlers and should
generate an appropriate message. The way I interpret the fact that
doublefault_fn is the one that prints out a message, is that main
fault handler is somehow dependent on .data being executable.... (but
this is pure speculation on my part at this point)...
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