linux-kernel - Re: Faking MMIO ops? Fooling a driver

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Date:	Thu, 16 Jun 2011 19:20:12 +0200
From:	Rafał Miłecki <zajec5@...il.com>
To:	linux-wireless@...r.kernel.org,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Cc:	Pekka Paalanen <pq@....fi>
Subject: Re: Faking MMIO ops? Fooling a driver

W dniu 16 czerwca 2011 16:44 użytkownik Rafał Miłecki
<zajec5@...il.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? :|

-- 
Rafał
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