From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from desiato.infradead.org (desiato.infradead.org [90.155.92.199]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 3FB472E03E0 for ; Wed, 24 Sep 2025 10:58:21 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=90.155.92.199 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758711504; cv=none; b=Aj33SIohIwDxY+/vTPItC8C+8x5tsYrDOFEQyFNMaAHGyoqNMNfTKQYiBDuRUc+kNQNU8Y1jJ8hNSQxpja0EiI6gpP5CRAr2vDT8VcCOMYn0srk1h0bYsTdAl3RpQaVZgWJeZ+J3sZ2UNv28EgW8TQXRrdPtD2bpVzGyBfqDdsM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758711504; c=relaxed/simple; bh=QTQKsd0rJAu25JtP9BEINMY8HjthBF38FlsVhtWlBbw=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=KF+hat9/dGwcy+viXGDty3+kyQaBPPV0/vXONbSBxAzYKlzfrRKdH314R/ZUdgc3oiws6pYQk9qZxtRXdT+v1kMUc+x/KEOynwV35gEovJWDJg/eEbyh/eEkLC82ClLBFJy7m0tqH6E0FQJ+U2I6IeRlBbRVIPVtdck2odOIrjw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org; spf=none smtp.mailfrom=infradead.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b=UbNDbUyD; arc=none smtp.client-ip=90.155.92.199 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=infradead.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="UbNDbUyD" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=desiato.20200630; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=CopVAZ9NyzvWTDM1Dz1jnOFXdwEQjE6yBnOwr+IVlsY=; b=UbNDbUyDwTcjlHmbRiGQkf5ZCz z8LEADUDCyX0ppDnCG8IJvr6gXmxmFjwMITOXgS7tBK1xM7r5RbOWuO9WMJZgQPmOJaFWYJrbtTYs yB5Pwy0bz6OvR2DIVeZIjDDMNC731LVFqW3/J1Ldx61K3aeCVO2ANcEU/Fp/hZqDBzpmp9pc6Vu9X JFSv/CCiyqdOU9qBquYcVNN1yiB49iPJx0giZjc0XpyFcVFEa3C3ciG5pU333vTT2FiXSX7SvGaL8 7nNClTbZcLmDH9iGuKe8J3Z3W1mDEA3z8m5AxxsvgPHleoENDEfKAzxjfP3FEFQmzOiEJylsXPSb4 ZzPmsD9w==; Received: from 77-249-17-252.cable.dynamic.v4.ziggo.nl ([77.249.17.252] helo=noisy.programming.kicks-ass.net) by desiato.infradead.org with esmtpsa (Exim 4.98.2 #2 (Red Hat Linux)) id 1v1NCR-00000008ixW-0C9p; Wed, 24 Sep 2025 10:58:15 +0000 Received: by noisy.programming.kicks-ass.net (Postfix, from userid 1000) id C65F930033D; Wed, 24 Sep 2025 12:58:13 +0200 (CEST) Date: Wed, 24 Sep 2025 12:58:13 +0200 From: Peter Zijlstra To: Alexandre Chartre Cc: linux-kernel@vger.kernel.org, mingo@kernel.org, jpoimboe@kernel.org Subject: Re: [RFC PATCH v2 00/17] objtool: Function validation tracing Message-ID: <20250924105813.GI3419281@noisy.programming.kicks-ass.net> References: <20250619145659.1377970-1-alexandre.chartre@oracle.com> <20250924073649.GT4067720@noisy.programming.kicks-ass.net> <20250924074206.GW4068168@noisy.programming.kicks-ass.net> <20250924100847.GY4068168@noisy.programming.kicks-ass.net> <20250924101038.GZ4068168@noisy.programming.kicks-ass.net> <90abf24a-326a-4215-8e13-2e1a2e3194ea@oracle.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <90abf24a-326a-4215-8e13-2e1a2e3194ea@oracle.com> On Wed, Sep 24, 2025 at 12:52:35PM +0200, Alexandre Chartre wrote: > > On 9/24/25 12:10, Peter Zijlstra wrote: > > On Wed, Sep 24, 2025 at 12:08:47PM +0200, Peter Zijlstra wrote: > > > On Wed, Sep 24, 2025 at 09:42:06AM +0200, Peter Zijlstra wrote: > > > > > > > > > d051: perf_get_x86_pmu_capability+0x51 | xchg %ax,%ax > > > > > > That libopcode is 'funny', isn't that typically spelled "nop" ? > > > > Ooh, I see, it is "osp nop" and yeah binutils also seems to do that as > > "xchg %ax,%ax". > > Yes, "xchg %ax,%ax" is NOP2 (opcodes: 0x66 0x90), "nop" is NOP1 (0x90). > > That's one more improvement we can do: identify NOP instructions and > display them as NOP Right, I have just the function for that. Let me do a patch for you.