W dniu 16 czerwca 2011 20:07 uÅytkownik Larry Finger
<Larry.Finger@xxxxxxxxxxxx> napisaÅ:
> On 06/16/2011 12:20 PM, RafaÅ MiÅecki wrote:
>>
>> W dniu 16 czerwca 2011 16:44 uÅytkownik RafaÅ MiÅecki
>> <zajec5@xxxxxxxxx> ÂnapisaÅ:
>>>
>>> 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:
>>> Âphy_read(0x0810) -> Â0x0000
>>> 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 â Tracers â 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.
Did you success with writing some special code? Following patch does
not seem to work for me:
diff --git a/include/asm-generic/io.h b/include/asm-generic/io.h
index e0ffa3d..448e4ff 100644
--- a/include/asm-generic/io.h
+++ b/include/asm-generic/io.h
@@ -23,6 +23,8 @@
#define mmiowb() do {} while (0)
#endif
+static int zajec = 0;
+
/*****************************************************************************/
/*
* readX/writeX() are used to access memory mapped devices. On some
@@ -40,6 +42,11 @@ static inline u8 __raw_readb(const volatile void
__iomem *addr)
#ifndef __raw_readw
static inline u16 __raw_readw(const volatile void __iomem *addr)
{
+ if (zajec++ < 10)
+ printk(KERN_INFO "[ZAJEC] %d\n", *addr);
+ if (*addr == 0xfaafc000)
+ printk(KERN_INFO "[ZAJEC] Bingo!\n");
+ //0x1381a8d8
return *(const volatile u16 __force *) addr;
}
#endif
Should I modify different readw? Path include/asm-generic/io.h sounds
sane to me, so I modified this one.
> 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?
This is for PHY type 7, AKA "HT".
--
RafaÅ
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