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

Ren Qiaowei
2014-10-28T05:58:21Z

On 10/28/2014 04:36 AM, Thomas Gleixner wrote:
> 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?
>

Ok. I will go through it again. Thanks.

- Qiaowei