Re: Setting kernel data breakpoints on x86

[Alan Stern <stern@rowland.harvard.edu>]

On Wed, 2 Nov 2005, Maneesh Soni wrote:

> On Tue, Nov 01, 2005 at 04:30:26PM -0500, Alan Stern wrote:
> > I'm trying to debug a rather difficult data-overwriting problem, and it 
> > would be a big help to be able to use a data breakpoint.
> > 
> > Is there any easy way of doing this?  I'd prefer not to use a kernel 
> > debugger, because the address of the breakpoint and the time when it's 
> > needed are determined dynamically.
> > 
> > Does anybody have a little lightweight procedure for setting one of the 
> > x86's debug registers to point to a particular location in kernel memory 
> > space?  I don't care if the whole system crashes when the debug exception 
> > occurs, just so long as I can get a stack trace and find out where the 
> > overwrite comes from.
> > 
> > 
> 
> Hi Alan
> 
> Probably watchpoint probes could be useful for this..
> 
> http://www.ussg.iu.edu/hypermail/linux/kernel/0508.3/1407.html
> 
> http://sourceware.org/ml/systemtap/2005-q3/msg00097.html

Hi Maneesh:

That's exactly what I was looking for.  Thanks!

Alan Stern

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