RE: [PATCH v9 09/12] x86, mpx: decode MPX instruction to get bound violation information

Thomas Gleixner
2014-10-27T20:36:53Z

On Mon, 27 Oct 2014, Ren, Qiaowei wrote:
> On 2014-10-24, Thomas Gleixner wrote:
> > On Sun, 12 Oct 2014, Qiaowei Ren wrote:
> >
> >> This patch sets bound violation fields of siginfo struct in #BR
> >> exception handler by decoding the user instruction and constructing
> >> the faulting pointer.
> >>
> >> This patch does't use the generic decoder, and implements a limited
> >> special-purpose decoder to decode MPX instructions, simply because
> >> the generic decoder is very heavyweight not just in terms of
> >> performance but in terms of interface -- because it has to.
> >
> > My question still stands why using the existing decoder is an issue.
> > Performance is a complete non issue in case of a bounds violation and
> > the interface argument is just silly, really.
> >
>
> As hpa said, we only need to decode several mpx instructions
> including BNDCL/BNDCU, and general decoder looks like a little
> heavy. Peter, what do you think about it?

You're repeating yourself. Care to read the discussion about this from
the last round of review again?

Thanks,

tglx