Re: [RFC PATCH v2 18/27] x86/cet/shstk: Introduce WRUSS instruction

[Peter Zijlstra]

On Wed, Jul 11, 2018 at 07:58:09AM -0700, Yu-cheng Yu wrote:
> On Wed, 2018-07-11 at 11:45 +0200, Peter Zijlstra wrote:
> > On Tue, Jul 10, 2018 at 03:26:30PM -0700, Yu-cheng Yu wrote:
> > > 
> > > diff --git a/arch/x86/lib/x86-opcode-map.txt b/arch/x86/lib/x86-
> > > opcode-map.txt
> > > index e0b85930dd77..72bb7c48a7df 100644
> > > --- a/arch/x86/lib/x86-opcode-map.txt
> > > +++ b/arch/x86/lib/x86-opcode-map.txt
> > > @@ -789,7 +789,7 @@ f0: MOVBE Gy,My | MOVBE Gw,Mw (66) | CRC32
> > > Gd,Eb (F2) | CRC32 Gd,Eb (66&F2)
> > >  f1: MOVBE My,Gy | MOVBE Mw,Gw (66) | CRC32 Gd,Ey (F2) | CRC32
> > > Gd,Ew (66&F2)
> > >  f2: ANDN Gy,By,Ey (v)
> > >  f3: Grp17 (1A)
> > > -f5: BZHI Gy,Ey,By (v) | PEXT Gy,By,Ey (F3),(v) | PDEP Gy,By,Ey
> > > (F2),(v)
> > > +f5: BZHI Gy,Ey,By (v) | PEXT Gy,By,Ey (F3),(v) | PDEP Gy,By,Ey
> > > (F2),(v) | WRUSS Pq,Qq (66),REX.W
> > >  f6: ADCX Gy,Ey (66) | ADOX Gy,Ey (F3) | MULX By,Gy,rDX,Ey (F2),(v)
> > >  f7: BEXTR Gy,Ey,By (v) | SHLX Gy,Ey,By (66),(v) | SARX Gy,Ey,By
> > > (F3),(v) | SHRX Gy,Ey,By (F2),(v)
> > >  EndTable
> > Where are all the other instructions? ISTR that documentation patch
> > listing a whole bunch of new instructions, not just wuss.
> 
> Currently we only use WRUSS in the kernel code.  Do we want to add all
> instructions here?

Yes, since we also use the in-kernel decoder to decode random userspace
code.