Re: [PATCH v4 4/4] sparc64: Add support for ADI (Application Data Integrity)

[Khalid Aziz]

On 01/17/2017 12:42 PM, David Miller wrote:
> From: Khalid Aziz <khalid.aziz@xxxxxxxxxx>
> Date: Tue, 17 Jan 2017 12:32:46 -0700
>
> > On 01/16/2017 09:39 PM, David Miller wrote:
> > > From: Khalid Aziz <khalid.aziz@xxxxxxxxxx>
> > > Date: Wed, 11 Jan 2017 09:12:54 -0700
> > >
> > > > +		__asm__ __volatile__(
> > > > +			".word 0xa1438000\n\t"	/* rd  %mcdper, %l0 */
> > >
> > > Just use "rd %%asr14, %0" this way you don't have to play all of these
> > > fixed register games which kill the code generated by gcc.  If you
> > > forcefully clobber a windowed register like %l0 it means the function
> > > being emitted can never be a leaf function, tail calls are no longer
> > > allowed, etc.
> >
> > Hi David,
> >
> > "rd %%asr14, %0" should work but does not due to bugs in assembler -
> > <https://sourceware.org/ml/binutils/2016-03/msg00302.html>, and
> > <https://sourceware.org/ml/binutils/2016-03/msg00303.html>. These bugs
> > were fixed in binutils 2.27 but older assemblers will cause kernel
> > build to fail. Using byte coded equivalent is the safest option.
>
> Fair enough.
>
> Then please at least use %g1 or another usable global register to
> avoid at least some of the problems I mentioned.

Sure, I will do that. Thanks for the review and feedback.

--
Khalid