Re: Setting kernel data breakpoints on x86

[Maneesh Soni <maneesh@in.ibm.com>]

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

Thanks
Maneesh

-- 
Maneesh Soni
Linux Technology Center, 
IBM India Software Labs,
Bangalore, India
email: maneesh@in.ibm.com
Phone: 91-80-25044990