Intel MPX (Skylake ISA) support?

[Carsten Mattner]

On Sun, Sep 14, 2014 at 11:00 AM, Konstantin Belousov
<kostikbel at gmail.com> wrote:
> On Sat, Sep 13, 2014 at 09:47:10PM +0200, Carsten Mattner wrote:
>> On Sat, Sep 13, 2014 at 6:20 PM, Konstantin Belousov
>> <kostikbel at gmail.com> wrote:
>> > On Sat, Sep 13, 2014 at 12:45:16PM +0200, Carsten Mattner wrote:
>> >> Are there any plans to include the necessary (kernel, libc) support for
>> >> Intel MPX (https://en.wikipedia.org/wiki/Intel_MPX)?
>> >
>> > I looked at this several times. The 319433 (Instructions Set Extensions
>> > prog reference) even at the current revision 20 still seems to not provide
>> > the complete documentation on the CPU side.  E.g., could you point me at
>> > the description of the save area for MPX ?  It is required since usermode
>> > bndcfg register can only be set by restoring from the XSAVE area.
>> >
>> > That said, I believe that most, if not all, of the needed kernel-side
>> > support is already there by the generic XSAVE code.
>> >
>> > I never see any specification of runtime services expected by the code
>> > generated by mpx-enabled gcc.
>>
>> Is https://lkml.org/lkml/2014/9/11/182 helpful?
>
> Not for me. I have zero interest in reverse-engineering Linux code
> for core CPU functionality. Intel usually provides high-quality
> documentation for the processors, and I hope that they will provide all
> needed information together with the hardware release.
>
> Another significant missing piece is the lack of description of the
> initial state and expectation of the runtime support in the ABI
> document. The ABI draft 0.3 from July 17, 2013, specially edited for
> MPX, only talks about argument passing conventions and dwarf, it seems.
>
> It is curious discussion about non-feasibility of implementing MPX
> translation tables in usermode.  Just for fun, I will try to do
> something purely in usermode (when/if hardware will be available).

More details I was able to find with links to hopefully descriptive
documentation. IIUC developers have been using a well known
Intel CPU simulator, but I'm in the dark there.

gcc: http://gcc.gnu.org/wiki/Intel%20MPX%20support%20in%20the%20GCC%20compiler

glibc:
https://sourceware.org/ml/libc-alpha/2014-03/msg00491.html
https://sourceware.org/ml/libc-alpha/2014-03/msg00543.html
https://sourceware.org/ml/libc-alpha/2014-03/msg00605.html