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

Ren, Qiaowei
2014-10-27T01:43:00Z

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?

Thanks,
Qiaowei