Re: [Xen-devel] [PATCH 2/5] xen/x86-64: clean up warnings aboutIST-usingtraps

[Jeremy Fitzhardinge]

Jan Beulich wrote:
> > else if (addr == (unsigned long)int3)
> > 		addr = (unsigned long)xen_int3;
> > -	else
> > -		WARN_ON(val->ist != 0);
> > +	else if (addr == (unsigned long)double_fault ||
> > +		 addr == (unsigned long)stack_segment) {
> >     
>
> I don't think you want to exclude handling stack faults: Ordinary memory
> references using rsp or rbp as the base register will cause these instead
> of general protection faults when the resulting effective address is non-
> canonical.
>   

So even usermode memory accesses?  Ew.  Well, we can run the trap 
handler on the normal kernel stack in that case.  I'll cook something up.

   J
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