Re: [PATCH 3/3] objtool/x86: Fix NOP decode

Alexandre Chartre
2025-09-25T13:05:46Z

On 9/25/25 12:42, Peter Zijlstra wrote:
> On Thu, Sep 25, 2025 at 12:03:23PM +0200, Peter Zijlstra wrote:
>
>>>>>> case 0x90:
>>>>>> + if (prefix != 0xf3) /* REP NOP := PAUSE */
>>>>>> + insn->type = INSN_NOP;
>>>>>> break;
>
>>> What about 0x49 0x90, which is xchg (XCHG r8,rAX) ?
>
> I've made that:
>
> case 0x90:
> if (rex_b) /* XCHG %r8, %rax */
> break;
>
> if (prefix == 0xf3) /* REP NOP := PAUSE */
> break;
>
> insn->type = INSN_NOP;
> break;
>
>

Sounds good.

Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>

alex.