From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 07837255251; Tue, 4 Mar 2025 19:15:05 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1741115706; cv=none; b=EdfhHjsgD9qox0lmV7yFxww6/YOfsBbHfZikf0oEfO11rULxWDAXyJlQWLA7rG6hPabr0Tg3kgdgXQE6mdPazDfZpJQ9a62UKYsGTqMEMqtVnni8PbXLkS7IN1b9l+1VZ76VJaFSEE910jSm31rIH4YJ8uav/DFbB71pSIFVYjs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1741115706; c=relaxed/simple; bh=JJAJkxUJ1Ssn3V4i6mnrB10sKcPRACeB/DFOKNhD4xs=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=LyJsb9mVOFPSeYH92xmuAozREWP4dirgBrq+Wl0Klk/jYq/RS72zeXn4Pt29N2Emr2U+sk171pdO5XNehNpBHnTNuszfV8x09gAYCziW4nYi18vLiU543VQnYkSE/hsTx4XZAFX3dOVx22Mfifm5vWX2JdGKnXD7fpESuMsPTo4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Wd9JANeJ; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Wd9JANeJ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 85B85C4CEE5; Tue, 4 Mar 2025 19:15:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1741115705; bh=JJAJkxUJ1Ssn3V4i6mnrB10sKcPRACeB/DFOKNhD4xs=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=Wd9JANeJfOHYEK6EVPAw2D9d0oO9xu0TCn07i8JUGEwPwIzMrEo5kUUUM0JRxSgCe Ya3UwIMByvZ6Uh+tYsP68ftGLlEZ5Sb2oUUlEb2wleHZY8s8Pi7V+xko8gXaIKzaHz clG23v9FmTavanU2W+8MXoBWlc5e9ueafFP+tdJGVKSy+9lrjvfuaOAaalcU5GXcVD 7Hu53N+0GntPjjXh8ZtcVDqw6t5o60eAhQii5IMPK0chk/6rFPiJH05vFD5SPwMIbf 7al0iIOlOcya//ouNSpRt/9UXCO9EbsX118KNqgGFOyrqNAMIwu/5JCnXAgRtIZaxs DxmBf9AudKkRA== Date: Tue, 4 Mar 2025 20:15:00 +0100 From: Ingo Molnar To: Josh Poimboeuf Cc: Linus Torvalds , linux-kernel@vger.kernel.org, linux-tip-commits@vger.kernel.org, "Peter Zijlstra (Intel)" , Brian Gerst , "H. Peter Anvin" , x86@kernel.org Subject: Re: [tip: x86/asm] x86/asm: Make ASM_CALL_CONSTRAINT conditional on frame pointers Message-ID: References: <174099976188.10177.7153571701278544000.tip-bot2@tip-bot2> <20250304182132.fcn62i4ry5ndli7l@jpoimboe> 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: <20250304182132.fcn62i4ry5ndli7l@jpoimboe> * Josh Poimboeuf wrote: > On Tue, Mar 04, 2025 at 08:01:58AM -1000, Linus Torvalds wrote: > > On Tue, 4 Mar 2025 at 07:51, Linus Torvalds > > wrote: > > > > > > Put another way: the old code has years of testing and is > > > significantly simpler. The new code is new and untested and more > > > complicated and has already caused known new problems, never mind any > > > unknown ones. > > > > > > It really doesn't sound like a good trade-off to me. > > I'm utterly confused, what are these new problems you're referring to? > > And how specifically is this more fragile? > > AFAICT, there was one known bug before the patches. Now there are zero > known bugs. > > Of course, it's entirely possible the build bots will shake out new > objtool warnings over the next weeks. But as of now, I haven't seen > anything. In any case I've zapped these two commits from tip:x86/asm for the time being: x86/asm: Fix ASM_CALL_CONSTRAINT for Clang 19 + KCOV + KMSAN x86/asm: Make ASM_CALL_CONSTRAINT conditional on frame pointers Until there's consensus. I left the 3 preparatory patches, which make sense as standalone cleanups: KVM: VMX: Use named operands in inline asm x86/hyperv: Use named operands in inline asm x86/alternatives: Simplify alternative_call() interface Thanks, Ingo