Message-ID: <4C395459.6080407@redhat.com>
Date: Sun, 11 Jul 2010 08:19:21 +0300
From: Avi Kivity <avi@redhat.com>
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To: Eric Dumazet <eric.dumazet@gmail.com>
CC: Felipe W Damasio <felipewd@gmail.com>, David Miller <davem@davemloft.net>,
       Patrick McHardy <kaber@trash.net>, linux-kernel@vger.kernel.org,
       netdev <netdev@vger.kernel.org>
Subject: Re: [PATCH] tproxy: nf_tproxy_assign_sock() can handle tw sockets
References: <AANLkTimn8A0cYZmwNZYitRkBHKKFe4HQ5GU626DLugkk@mail.gmail.com>	 <AANLkTil49m6Ul2bauiH4Pwn-6ykrYTFmSO6_SxqQgD_e@mail.gmail.com>	 <1278626921.2435.73.camel@edumazet-laptop>	 <AANLkTiliBClahTfb41M5BDi1etg5pgkqEz_VfGrn_mK4@mail.gmail.com>	 <1278695580.2696.55.camel@edumazet-laptop>	 <AANLkTil39xHOhcdAo4h_jWtx_UuYdFHGdQVAdwPMd7QJ@mail.gmail.com> <1278742649.2538.17.camel@edumazet-laptop>
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On 07/10/2010 09:17 AM, Eric Dumazet wrote:
>
> Strange thing with your crash report is CR2 value, with unexpected value
> of 000000000b388000 while RAX value is dce8dce85d415d41
>
> Faulting instruction is :
>
> 48 83 b8 b0 00 00 00 00   cmpq   $0x0,0xb0(%rax)
>
> So I would have expected CR2 being RAX+0xb0, but its not.
>    

Nothing strange about it.  You only get page faults and valid cr2 for 
canonical addresses (17 high order bits all equal).  In this case 
rax+0xb0 is not a canonical address, so you got a general protection 
fault instead, with cr2 unchanged.

-- 
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.

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