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RE: [Xen-ia64-devel] copy_from_user()

To: "Haavard Bjerke" <havard.bjerke@xxxxxxx>, "Dan Magenheimer" <dan.magenheimer@xxxxxx>
Subject: RE: [Xen-ia64-devel] copy_from_user()
From: "Tian, Kevin" <kevin.tian@xxxxxxxxx>
Date: Wed, 27 Apr 2005 10:48:15 +0800
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Thread-topic: [Xen-ia64-devel] copy_from_user()
Copy_from_user itself has clear syntax, which is just fuse of some early 
corrupted context. Suggestion is to:
        - Dump symbol of your guest linux kernel, and locate the exact 
instruction including type and register number
        - Set breakpoint at that instruction and re-execute from scratch
        - When br is hit, go through context save/restore path, to check 
whether anything goes wrong in the boundary
        - If everything works well on this emulation, you have to analyze guest 
code and locate where the current register value comes from, and change br 
again...

Also if you know exactly the place of internal data structure within HV related 
to that point, monitoring that area can help more. 

Just some vague idea and hope helps. :)
Thanks,
Kevin

>-----Original Message-----
>From: xen-ia64-devel-bounces@xxxxxxxxxxxxxxxxxxx
>[mailto:xen-ia64-devel-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of Haavard Bjerke
>Sent: Tuesday, April 26, 2005 11:56 PM
>To: Dan Magenheimer
>Cc: xen-ia64-devel@xxxxxxxxxxxxxxxxxxx
>Subject: [Xen-ia64-devel] copy_from_user()
>
>I'm trying to get the privcmd interface working so that I can interact with 
>the event
>channel through /proc/xen/privcmd. When dom0 tries to get parameters from the 
>user
>with copy_from_user(), Xen says:
>
>$$$$$ PANIC in domain 0 (k6=f0000000040b0000): ia64_do_page_fault: @
>0000000000000000???, iip=a0000001002c8)
>
>copy_from_user() seems to be a large and complex routine, so I'll just ask 
>first if
>someone knows from the top of their minds what's going on?
>
>Håvard
>
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