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Date: Mon, 08 Mar 2010 18:33:16 +0530
From: Sachin Sant <sachinp@in.ibm.com>
MIME-Version: 1.0
To: ananth@in.ibm.com
Subject: Re: [PowerPC] 2.6.33-git11 : Badness at kernel/kprobes.c:264
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	<20100308101152.GA2557@osiris.boeblingen.de.ibm.com>
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Cc: Linux/PPC Development <linuxppc-dev@ozlabs.org>,
	Heiko Carstens <heiko.carstens@de.ibm.com>,
	linux-kernel <linux-kernel@vger.kernel.org>, mhiramat@redhat.com
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Ananth N Mavinakayanahalli wrote:
>>> 2.6.33-git10(64ba99267...) was OK.
>>>
>>> This WARN_ON was introduced by commit 4610ee1d36...
>>>
>>> kprobes: Introduce generic insn_slot framework
>>>       
>> FWIW, same on s390...
>>     
>
> This patch should fix it:
>
> When freeing the instruction slot, the arithmetic to calculate the index
> of the slot in the page needs to account for the total size of the
> instruction on the various architectures.
>
> Calculate the index correctly when freeing the out-of-line execution slot.
>
> Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
>   
Thanks Ananth. Boots fine on my POWER6 box without any WAR_ON.

Regards
-Sachin

> ---
> Index: linux-8mar/kernel/kprobes.c
> ===================================================================
> --- linux-8mar.orig/kernel/kprobes.c	2010-03-08 17:10:33.000000000 +0530
> +++ linux-8mar/kernel/kprobes.c	2010-03-08 17:12:12.000000000 +0530
> @@ -259,7 +259,8 @@
>  	struct kprobe_insn_page *kip;
>
>  	list_for_each_entry(kip, &c->pages, list) {
> -		long idx = ((long)slot - (long)kip->insns) / c->insn_size;
> +		long idx = ((long)slot - (long)kip->insns) /
> +				(c->insn_size * sizeof(kprobe_opcode_t));
>  		if (idx >= 0 && idx < slots_per_page(c)) {
>  			WARN_ON(kip->slot_used[idx] != SLOT_USED);
>  			if (dirty) {
>
>
>
>   


-- 

---------------------------------
Sachin Sant
IBM Linux Technology Center
India Systems and Technology Labs
Bangalore, India
---------------------------------