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 7873C31E0E1; Mon, 27 Oct 2025 20:59:13 +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=1761598753; cv=none; b=pek+iikVKneZ9598uwazCjqux2crAPxUCmXiwS5TYC+IjjBzJsXcWUFjtgUQP7/qwUGODM2dhb43AarPHjGClgQ906HxPs0moZ0Gox5GvylPNTfn+auyR3SejUx+ueFoHftJaI6nsXyQDylNF0bZnPY5xxVlrgZMAxFdbul47GM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761598753; c=relaxed/simple; bh=yprLLzu/23+hltQ8hDoRSGSE9VYBXZzoi6lRcgP6GUU=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=VgksaA3gZSPPTYUOLSwNTiwneSvAucNRxO14yQx+H+Ivk5tIJ5XWBSRETQUJyevxoln0rY0teRhihgbpB1dg/8mEHC9C1H1gRcV5UBLvcOKnylyWar30UJXKCLZDI4RXw6eiMbPnX3Uj8/bqk+Vr/G758Vcz5zKFlOVdgk+sxr0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=b1yBFjqe; 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="b1yBFjqe" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 16BB8C4CEF1; Mon, 27 Oct 2025 20:59:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1761598752; bh=yprLLzu/23+hltQ8hDoRSGSE9VYBXZzoi6lRcgP6GUU=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=b1yBFjqe7L7wiSakMaFxsykOaqlqtoXS31LKAHj3epXm3lgg8XIkT42EhxqZMwgO3 YE7454XpIAkuPSYsGIFN/QE3es/tu2qd9U+QkuR3owshZPsToFp83dDaCtkCVgoRzO 35KmyTDhGtTE2j+vKr6oONd4rMigXy3t7Mz/aWAaFUSWnkXbr3O2K/CfP3fGUjZjVR ocs11llI7nRErN6nMomsXTtegUW8LQSEQwpUWBFap/NFEJuaM5hZR/g+S8dZg0YoP4 kMd/jISG6W4xXr1WRJwsmFiTwkZDgYkTmhOkqHuSDGeAngmyCunnKdLx+yPfkVqrjL S34035HO3C3Gw== Date: Mon, 27 Oct 2025 13:59:06 -0700 From: Nathan Chancellor To: Sami Tolvanen Cc: Linus Walleij , Kees Cook , Alexander Lobakin , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Simon Horman , Nick Desaulniers , Bill Wendling , Justin Stitt , Russell King , Tony Nguyen , Michal Kubiak , linux-kernel@vger.kernel.org, llvm@lists.linux.dev, linux-arm-kernel@lists.infradead.org, netdev@vger.kernel.org, intel-wired-lan@lists.osuosl.org Subject: Re: [PATCH 2/3] ARM: Select ARCH_USES_CFI_GENERIC_LLVM_PASS Message-ID: <20251027205906.GC3183341@ax162> References: <20251025-idpf-fix-arm-kcfi-build-error-v1-0-ec57221153ae@kernel.org> <20251025-idpf-fix-arm-kcfi-build-error-v1-2-ec57221153ae@kernel.org> Precedence: bulk X-Mailing-List: netdev@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: Hi Sami, On Mon, Oct 27, 2025 at 08:53:49AM -0700, Sami Tolvanen wrote: > Instead of working around issues with the generic pass, would it make > more sense to just disable arm32 CFI with older Clang versions > entirely? Linus, any thoughts? That would certainly get to the heart of the problem. I have no real strong opinion about keeping these older versions working, especially since we have no idea how many people are actively using CONFIG_CFI on ARM. I will say that this particular issue is rather exceptional (i.e., I don't know how often this would really come up in the future) because this code is relying on the fact that these indirect calls will be made direct by the compiler and checking for it, which does not seem like it would be really common in the kernel otherwise. We would likely have to forbid future use of the generic pass as well. Cheers, Nathan