linux-kernel - Re: [BUG] Kprobes fails on 2.6.25-rc3-mm1 (x86) systems, if CONFIG_DEBUG

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Date:	Thu, 6 Mar 2008 07:55:51 -0500
From:	Mathieu Desnoyers <mathieu.desnoyers@...ymtl.ca>
To:	Srinivasa DS <srinivasa@...ibm.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org, ananth@...ibm.com,
	Jim Keniston <jkenisto@...ibm.com>, srikar@...ux.vnet.ibm.com,
	SystemTAP <systemtap@...rces.redhat.com>
Subject: Re: [BUG] Kprobes fails on 2.6.25-rc3-mm1 (x86) systems, if
	CONFIG_DEBUG_RODATA is set.

* Srinivasa DS (srinivasa@...ibm.com) wrote:
> Insertion of kprobe module causes oops on 2.6.25-rc3-mm1 (x86) systems if we 
> enable CONFIG_DEBUG_RODATA.  While registering the probe, memcpy() fails to 
> copy breakpoint instruction to the instruction address and generates the 
> oops.
> 
> BUG: unable to handle kernel paging request at ffffffff8047d1a7
> IP: [<ffffffff8047ff62>] text_poke+0xa/0x10
> PGD 203067 PUD 207063 PMD 7e191163 PTE 47d161
> Oops: 0003 [1] PREEMPT SMP
> ................................................
> 
> This is because, Mathieu's patch (http://lkml.org/lkml/2008/2/2/226) makes 
> entire text segment as READONLY, if we enable CONFIG_DEBUG_RODATA. 
> 
> So reverting this patch or new patch, which considers kprobes while deciding  
> boundary for setting readonly pages might solve the probelm.
> 

Hi,

Are you running under Xen, lguest, kvm.. ?

Mathieu

> Thanks
>  Srinivasa DS
>  LTC-IBM
>  
> 
> 
> 

-- 
Mathieu Desnoyers
Computer Engineering Ph.D. Student, Ecole Polytechnique de Montreal
OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F  BA06 3F25 A8FE 3BAE 9A68
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