Re: [PATCH] s390/test_unwind: use raw opcode instead of invalid instruction

From: Heiko Carstens
Date: Fri Nov 19 2021 - 10:15:47 EST


On Fri, Nov 19, 2021 at 03:12:03PM +0100, Christian Borntraeger wrote:
> Am 19.11.21 um 12:09 schrieb Heiko Carstens:
> > On Fri, Nov 19, 2021 at 11:57:05AM +0100, Christian Borntraeger wrote:
> > > > > > > - " mvcl %%r1,%%r1\n"
> > > > > > > + " .insn e,0x0e11\n" /* mvcl %%r1,%%r1" */
> > > >
> > > > Sorry, I disagree with this. As you said above rr would be the correct
> > > > format for this instruction. If we go for the e format then we should
> > > > also use an instruction with e format.
> > > > Which in this case would simply be an illegal opcode, which would be
> > > > sufficient for what this code is good for: ".insn e,0x0000".
> > >
> > > Why not simply use .short then?
> >
> > .short bypasses all sanity checks while .insn does not, so I think
> > that should be preferred. But I don't care too much.
>
> Heiko,
> I am fine with ".insn e,0x0000" and the a changed comment that
> changes "specification exception" to "operation exception". Do you
> want Ilie to resend or simply fixup?

I'll simply change it. Let's don't spend more time on this.