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 X-Spam-Level: X-Spam-Status: No, score=-8.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8B7E7C433E6 for ; Wed, 3 Feb 2021 13:06:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3088164F6C for ; Wed, 3 Feb 2021 13:06:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231274AbhBCNGZ (ORCPT ); Wed, 3 Feb 2021 08:06:25 -0500 Received: from mail.kernel.org ([198.145.29.99]:51372 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229500AbhBCNGY (ORCPT ); Wed, 3 Feb 2021 08:06:24 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 89FE964E38; Wed, 3 Feb 2021 13:05:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1612357542; bh=OSBHuUI8og5Vfp1FBOELDBA9lFmC6WOrg2hzohSc4Ko=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=bE3VV0lsArjMZgba11em/bAn62/vpuKCIk3rBNO0syg2HdcvQ7i/ApMC6sC5QKKCV WDQE7DA5yWLZxF8/CTMufJKH9eifbJslYZ7ZRHtuY1y5m3WuoiW+AfmhJQKoUOlKRq TSHLPkiWb1BPJxPlnX2BjP4m5ocPnsl2HsZGu/GSSQRtOU4SM4HflfziC8yYMeV6OO yzvFKIaHdXMBIzrmWVJsAClnGAqh5wJqScIOKN1GeDC2cprQg9Ynw2sqzJ+CgN6XUn aKS/0P//pyCfY/ymysil2/T1msQSjHlso2GZBNGlqp+mAEWEEII72CAcRf+sZlyyXH DBUEofTmHtYfw== Date: Wed, 3 Feb 2021 13:04:53 +0000 From: Mark Brown To: Josh Poimboeuf Cc: Nick Desaulniers , Julien Thierry , Ard Biesheuvel , Catalin Marinas , Kees Cook , Linux ARM , linux-efi , linux-hardening@vger.kernel.org, LKML , Mark Rutland , Masahiro Yamada , Michal Marek , Peter Zijlstra , raphael.gault@arm.com, Will Deacon , clang-built-linux , Bill Wendling , swine@google.com, yonghyun@google.com Subject: Re: [RFC PATCH 12/17] gcc-plugins: objtool: Add plugin to detect switch table on arm64 Message-ID: <20210203130453.GB4880@sirena.org.uk> References: <20210120173800.1660730-13-jthierry@redhat.com> <20210127221557.1119744-1-ndesaulniers@google.com> <20210127232651.rj3mo7c2oqh4ytsr@treble> <20210201214423.dhsma73k7ccscovm@treble> <671f1aa9-975e-1bda-6768-259adbdc24c8@redhat.com> <20210203001414.idjrcrki7wmhndre@treble> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="NMuMz9nt05w80d4+" Content-Disposition: inline In-Reply-To: <20210203001414.idjrcrki7wmhndre@treble> X-Cookie: Who was that masked man? User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: linux-efi@vger.kernel.org --NMuMz9nt05w80d4+ Content-Type: text/plain; charset=us-ascii Content-Disposition: inline On Tue, Feb 02, 2021 at 06:14:14PM -0600, Josh Poimboeuf wrote: > On Tue, Feb 02, 2021 at 03:01:22PM -0800, Nick Desaulniers wrote: > > I wonder if PAC or BTI also make this slightly more complex? PAC at > > least has implications for unwinders, IIUC. > What is PAC/BTI? PAC and BTI are ARM architecture extensions. PAC uses a tag in pointers to sign and verify them, presenting a barrier to ROP, and when BTI is active only specific instructions can be branched to. Since PAC modifies pointers when it is active the unwinder has to undo the tagging to understand what's being pointed to, that's already there. --NMuMz9nt05w80d4+ Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAABCgAdFiEEreZoqmdXGLWf4p/qJNaLcl1Uh9AFAmAan3UACgkQJNaLcl1U h9CR6Af/a+hTHn/OAxEoRg8U3FQ8sbGU1efy2c412xJU7ZqPnGW5l96P6lNt4mXY 85GyLjKkQYBjZkC4t20+ug13zhghrfPoQt6sN+8nBjswZiOPqd/Zpwsznos8Eut/ 8On39npKp4ur2GziLiDkTXZT77zknCoDVtH/gpEhAURL7mDcnhmesHIqEKcgbM9S 3WvuL6K8FFnXfECt09m1s6qP8jD9h/l4CV6dIhz/Ievk6hLOpX4ucTcJGVduTqjv qa5xuLBioxKOC5PHo0iob9HaJClu9F5vCyPj8RdTxsyJs0TO6pW299UemUoOj40T Dw4EtudvTIp662frrw8FTbvr930r3Q== =DA8Q -----END PGP SIGNATURE----- --NMuMz9nt05w80d4+--