From: Larry Finger <Larry.Finger@lwfinger.net>
To: "Rafał Miłecki" <zajec5@gmail.com>
Cc: linux-wireless@vger.kernel.org,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Pekka Paalanen <pq@iki.fi>
Subject: Re: Faking MMIO ops? Fooling a driver
Date: Thu, 16 Jun 2011 13:07:46 -0500 [thread overview]
Message-ID: <4DFA4672.5080307@lwfinger.net> (raw)
In-Reply-To: <BANLkTinUxRGkXeOtBSKi51n3Q_rZEp1gUg@mail.gmail.com>
On 06/16/2011 12:20 PM, Rafał Miłecki wrote:
> W dniu 16 czerwca 2011 16:44 użytkownik Rafał Miłecki
> <zajec5@gmail.com> napisał:
>> I analyze MMIO dumps of closed source driver and found such a place:
>> W 2 3855.911536 9 0xb06003fc 0x810 0x0 0
>> R 2 3855.911540 9 0xb06003fe 0x0 0x0 0
>> W 2 3855.911541 9 0xb06003fe 0x0 0x0 0
>>
>> After translation:
>> phy_read(0x0810) -> 0x0000
>> phy_write(0x0810)<- 0x0000
>>
>> So it's quite obvious, the driver is reading PHY register, masking it
>> and writing masked value. Unfortunately from just looking at such
>> place we can not guess the mask driver uses.
>>
>> I'd like to fake value read from 0xb06003fe to be 0xFFFF.
>> Is there some ready method for doing such a trick?
>>
>> Dump comes from Kernel hacking → Tracers → MMIO and ndiswrapper.
>
> I can see values in MMIO trace struct are filled in
> arch/x86/mm/mmio-mod.c in "pre" and "post". However still no idea how
> to hack the returned value.
>
> Should I try hacking read[bwl] instead? :|
Probably. I do not see any way to trace and modify the results for a particular
address without special code.
FYI, my reference driver for reverse engineering has no instance of a
read/modify/write for PHY register 0x810. Is the code in question for a PHY type
> 6?
Larry
next prev parent reply other threads:[~2011-06-16 18:07 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-06-16 14:44 Faking MMIO ops? Fooling a driver Rafał Miłecki
2011-06-16 17:20 ` Rafał Miłecki
2011-06-16 18:07 ` Larry Finger [this message]
2011-06-16 19:19 ` Rafał Miłecki
2011-06-16 19:34 ` Pekka Paalanen
2011-06-16 21:47 ` Rafał Miłecki
2011-06-16 21:53 ` Rafał Miłecki
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