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From: Peter Zijlstra <peterz@infradead.org>
To: Alexandre Chartre <alexandre.chartre@oracle.com>
Cc: jpoimboe@kernel.org, x86@kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 3/3] objtool/x86: Fix NOP decode
Date: Thu, 25 Sep 2025 12:42:51 +0200	[thread overview]
Message-ID: <20250925104251.GZ4067720@noisy.programming.kicks-ass.net> (raw)
In-Reply-To: <20250925100323.GY4067720@noisy.programming.kicks-ass.net>

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;



  reply	other threads:[~2025-09-25 10:42 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-09-24 13:45 [PATCH 0/3] objtool: Few x86 decoder updates Peter Zijlstra
2025-09-24 13:45 ` [PATCH 1/3] objtool/x86: Remove 0xea hack Peter Zijlstra
2025-09-25  9:55   ` Alexandre Chartre
2025-10-14 11:47   ` [tip: objtool/core] " tip-bot2 for Peter Zijlstra
2025-09-24 13:45 ` [PATCH 2/3] objtool/x86: Add UDB support Peter Zijlstra
2025-09-25  9:56   ` Alexandre Chartre
2025-10-14 11:47   ` [tip: objtool/core] " tip-bot2 for Peter Zijlstra
2025-09-24 13:45 ` [PATCH 3/3] objtool/x86: Fix NOP decode Peter Zijlstra
2025-09-24 17:34   ` Alexandre Chartre
2025-09-24 18:41     ` Peter Zijlstra
2025-09-25  9:55       ` Alexandre Chartre
2025-09-25 10:03         ` Peter Zijlstra
2025-09-25 10:42           ` Peter Zijlstra [this message]
2025-09-25 11:29             ` Andrew Cooper
2025-09-25 12:43               ` Peter Zijlstra
2025-09-25 13:04                 ` Alexandre Chartre
2025-09-25 14:11                 ` Peter Zijlstra
2025-09-25 13:05             ` Alexandre Chartre
2025-10-14 11:47   ` [tip: objtool/core] " tip-bot2 for Peter Zijlstra

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