Re: [PATCH] paravirt.h

[Zachary Amsden <zach@vmware.com>]

Andi Kleen wrote:
> On Wednesday 23 August 2006 11:01, Zachary Amsden wrote:
>   
>> Andi Kleen wrote:
>>     
>>>> Yes, after discussion with Rusty, it appears that beefing up 
>>>> stop_machine_run is the right way to go.  And it has benefits for 
>>>> non-paravirt code as well, such as allowing plug-in kprobes or oprofile 
>>>> extension modules to be loaded without having to deal with a debug 
>>>> exception or NMI during module load/unload.
>>>>     
>>>>         
>>> I'm still unclear where you think those debug exceptions will come from
>>>       
>> kprobes set in the stop_machine code - which is probably a really bad 
>> idea, but nothing today actively stops kprobes from doing that.
>>     
>
> kprobes don't cause any debug exceptions. You mean int3?
>
> Anyways this can be fixed by marking the stop machine code __kprobes
>
> -Andi
>   

I need to look at the kprobes code in more depth to answer completely.  
But in general, there could be a problem if DRs are set to fire on any 
EIP or memory address touched during the critical stop_machine region, 
or int3 breakpoints are set in that code or any code it calls.

Zach