Re: [PATCH 1/2] test: Add IDT framework

[Sheng Yang <sheng@linux.intel.com>]

On Thursday 10 June 2010 17:49:16 Avi Kivity wrote:
> On 06/10/2010 06:31 AM, Sheng Yang wrote:
> > +
> > +#define EXCEPTION_REGION_BEGIN(r, lb) \
> > +    asm volatile("pushq $"lb"\n\t" \
> > +                 "mov $2, %0\n\t" \
> > +                 : "=r"(r))
> > +#define EXCEPTION_REGION_END(r, lb) \
> > +    asm volatile("popq %%rdx\n\t" \
> > +		 "mov $0, %0\n\t" \
> > +                 lb":\n\t": \
> > +                 "=r"(r) :: "%rdx")
> 
> These mess up the stack, no?  So if any intervening code uses %rsp based
> addressing, it will get incorrect information.

Yes, but I meant to only include instruction directly in the “region”, and support 
nobody should touch $rsp then. It's directly and simple enough.
> 
> I suggest using a special data section like the kernel.

Kind of more complex...
> 
> Also, most tests that use asm don't need an exception region, but will
> want to trap an exception on a single address.  So need a macro designed
> to be placed in asm in front of the faulting instruction.

Use region here is due to we don't know the size of instruction(or I don't know 
how to get it)... Use a label here seems the simplest way to get the address 
right.

--
regards
Yang, Sheng