Re: [PATCH 1/N, MPX, x86_64] Intel MPX support in glibc for x86_64

["H.J. Lu" <hjl dot tools at gmail dot com>]

On Mon, Mar 17, 2014 at 11:09 AM, H.J. Lu <hjl.tools@gmail.com> wrote:
> On Mon, Mar 17, 2014 at 11:03 AM, Zamyatin, Igor
> <igor.zamyatin@intel.com> wrote:
>> Hi All!
>>
>> Attached patch is the first of the set of patches that add support for Intel MPX technology (see e.g. http://software.intel.com/sites/default/files/319433-015.pdf, Chapter 9) in Glibc for x86_64. Namely, this particular patch introduces bounds storing/restoring in _dl_runtime_resolve.
>>
>> Is it ok to install?
>>
>>
>> Thanks,
>> Igor
>>
>> 2014-03-13  Igor Zamyatin  <igor.zamyatin@intel.com>
>>
>>       * config.h.in (HAVE_MPX_SUPPORT): New #undef.
>>       * sysdeps/x86_64/configure.ac: Set HAVE_MPX_SUPPORT.
>>       * sysdeps/x86_64/configure: Regenerated.
>>       * sysdeps/x86_64/dl-trampoline.S (_dl_runtime_resolve): Add storing
>>       and restoring of Intel MPX bound registers before and after call
>>       of_dl_fixup.
>
> The reasons we need to save and restore bound registers in
> symbol lookup are
>
> 1.  Branches without BND prefix clear bound registers.
> 2.  x86-64 pass bounds in bound registers as specified in MPX
> psABI extension on hjl/mpx/master branch at
>
> https://github.com/hjl-tools/x86-64-psABI
> https://groups.google.com/forum/#!topic/x86-64-abi/KFsB0XTgWYc
>
> Binutils has been updated to create an alternate PLT to
> add BND prefix when branching to ld.so.
>

Are there any comments, feedbacks or objections?

Thanks.

-- 
H.J.