From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id A3F62C05027 for ; Mon, 20 Feb 2023 15:54:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231597AbjBTPxr (ORCPT ); Mon, 20 Feb 2023 10:53:47 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48730 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231898AbjBTPxg (ORCPT ); Mon, 20 Feb 2023 10:53:36 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2CEDFCC10 for ; Mon, 20 Feb 2023 07:53:35 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id DAAE5B80D3D for ; Mon, 20 Feb 2023 15:53:33 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 13B2FC433D2; Mon, 20 Feb 2023 15:53:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1676908412; bh=q+UVYAvOaKZ6rZqbBNYvveBTTXN21i0MHtTIbAuaZpk=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=lR09TSNkGgYv6pu7RULT1Zz3+OmsbCIoNTVNVZyX2foLFHw9Drn9v6q0Tp1lbMUAM qCDSqe36uqeS5OF+j2nWNoqB8QfErP40SiEvXuV1644x/DGih07R9MtQ0J5oPiT58E nrHhPr9CX+mdMBrySoxSAQZTWBd+hJ5Hmyub6wEr1bzVqJXrIAcbhc4jgXoPiUn/CV mepLTTlzV4r4N24lWIXnGvvfPJRA0vHR0kvDaJpTXQqK30fL/N5AaZtQUsM0ZvrZQA wN2NeWUyN4yalD6BwUi6qCYe94J7F2iwD27y/AgvW5HIhVqZdU+c7nCQyA/hQ6gNxB aAKOlH4nxkR2A== Date: Mon, 20 Feb 2023 15:53:26 +0000 From: Mark Brown To: Ard Biesheuvel Cc: Mark Rutland , Will Deacon , linux-efi@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Catalin Marinas , Kees Cook , Peter Zijlstra , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen Subject: Re: [PATCH v2 2/3] efi: arm64: Wire up BTI annotation in memory attributes table Message-ID: References: <20230206124938.272988-1-ardb@kernel.org> <20230206124938.272988-3-ardb@kernel.org> <20230208130007.GA13529@willie-the-truck> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="5WpvdvFpmWSYyolJ" Content-Disposition: inline In-Reply-To: X-Cookie: Adapt. Enjoy. Survive. Precedence: bulk List-ID: X-Mailing-List: linux-efi@vger.kernel.org --5WpvdvFpmWSYyolJ Content-Type: text/plain; charset=us-ascii Content-Disposition: inline On Wed, Feb 08, 2023 at 03:36:40PM +0100, Ard Biesheuvel wrote: > OTOH, what is the penalty for setting the GP attribute and using the > translation table on a core that does not implement BTI? The concern with doing that for Linux was what would happen if someone implemented a system with mixed BTI/no BTI support and then a task got preempted and moved between the two, you might end up with PSTATE.BTYPE incorrectly set and trigger a spurious fault. That shouldn't be an issue for EFI runtime services. --5WpvdvFpmWSYyolJ Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAABCgAdFiEEreZoqmdXGLWf4p/qJNaLcl1Uh9AFAmPzl3UACgkQJNaLcl1U h9DULQf/W0cn39PdHYc9sdljFWeJ7LRx3yvPMxJ8y2zgfUJtLtJjOVUy9btE3o8D mTepWDY6AQwhxlj3wGa3T11dKw1/f8OKnw1s9PiNCYCDMU9D8gRssCMf02X+FPQI bFX+lYkl/MvC6CG+5sbdn8LWKqIOShEDkHuAYu8CPiUr4vuy5rgJN0XdUcNeYsul Bl6ERMhjSKyJUtGZVK/8U1sfi9gU582K8ZJjAYdHjxKmo9lxMpA6Leo5UbBVi432 bN+2tgdhiw6LXrGjN4sfRcsLn1BMng3YJPSiJbKqJgo8OQJDHj0wk+CMhyUpax9w RmJJPxXTKizu8hnEHdM64QlkG9JE3g== =GcCt -----END PGP SIGNATURE----- --5WpvdvFpmWSYyolJ--