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

From: Christian Borntraeger
Date: Fri Nov 19 2021 - 09:12:17 EST




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?