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=-5.6 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=no 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 01ABDC4363A for ; Tue, 20 Oct 2020 15:39:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 833A02224A for ; Tue, 20 Oct 2020 15:39:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1603208365; bh=WvtM8lVaUa9n6kZloXHDYcS2/S2PuIPyjBhGUcDqflY=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=CwdkYRWsGOTpyZY6lMpmrS/mI0t3cnTVrTK048/69Qo3e4UtU1no4HUpPt1Gas2dP wVKoB6RZa2I7F9dUvKhmZg0KOCYff2MdDUglW/9Vzf8JtveaL/P9xPwcyY/QMzj7qe Lv5S2qFtDg1tkxb9KP3+anaDJPzoSUokAo4l313c= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2436568AbgJTPjZ (ORCPT ); Tue, 20 Oct 2020 11:39:25 -0400 Received: from mail.kernel.org ([198.145.29.99]:52746 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2436565AbgJTPjY (ORCPT ); Tue, 20 Oct 2020 11:39:24 -0400 Received: from localhost (fw-tnat.cambridge.arm.com [217.140.96.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id C036E22247; Tue, 20 Oct 2020 15:39:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1603208364; bh=WvtM8lVaUa9n6kZloXHDYcS2/S2PuIPyjBhGUcDqflY=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=LPjk0IxpAocgXvARJKZOOuIGehhrmFemg8rN4u9fTXs2wwwyemw8hkA9kRoVLeIph x9zy9WVniBFdOd/Emr0Jq65uVh309hgoVspwKsB9nXq0vUPYhJ0Yq0l1l8yYyHlWXe zPAos9Mih8+/PEJYiMHT8Jwhl5x68Dj3KKloyXY4= Date: Tue, 20 Oct 2020 16:39:13 +0100 From: Mark Brown To: Josh Poimboeuf Cc: Mark Rutland , Miroslav Benes , Catalin Marinas , Will Deacon , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, live-patching@vger.kernel.org Subject: Re: [RFC PATCH 0/3] arm64: Implement reliable stack trace Message-ID: <20201020153913.GE9448@sirena.org.uk> References: <20201012172605.10715-1-broonie@kernel.org> <20201015141612.GC50416@C02TD0UTHF1T.local> <20201015154951.GD4390@sirena.org.uk> <20201015212931.mh4a5jt7pxqlzxsg@treble> <20201016121534.GC5274@sirena.org.uk> <20201019234155.q26jkm22fhnnztiw@treble> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="lteA1dqeVaWQ9QQl" Content-Disposition: inline In-Reply-To: <20201019234155.q26jkm22fhnnztiw@treble> X-Cookie: The people rule. User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: live-patching@vger.kernel.org --lteA1dqeVaWQ9QQl Content-Type: text/plain; charset=us-ascii Content-Disposition: inline On Mon, Oct 19, 2020 at 06:41:55PM -0500, Josh Poimboeuf wrote: > On Fri, Oct 16, 2020 at 01:15:34PM +0100, Mark Brown wrote: > > Ah, I'd have interpreted "defined thread entry point" as meaning > > expecting to find specific functions appering at the end of the stack > > rather than meaning positively identifying the end of the stack - for > > arm64 we use a NULL frame pointer to indicate this in all situations. > > In that case that's one bit that is already clear. > I think a NULL frame pointer isn't going to be robust enough. For > example NULL could easily be introduced by a corrupt stack, or by asm > frame pointer misuse. Is it just the particular poison value that you're concerned about here or are you looking for additional checks of some other kind? --lteA1dqeVaWQ9QQl Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAABCgAdFiEEreZoqmdXGLWf4p/qJNaLcl1Uh9AFAl+PBKAACgkQJNaLcl1U h9CmCQf9GADeXb4clrrWKiZ2FKpp7qztSVT7TN33f+79sG5oc8MkFcPkif5Mc6bk tpBrddZNh2aI+uGg3RGCYWBE5S9LM3zE7SSin+1YkZWQ7O7/X7XK2WjJUTJS9qqR HB781+Hf1SfbuO4Hss1fb/hDVPt4v0Qy907v9FKF3f8V9twBclG+rQhYFFMY9DmP yFN0MGtXsDxjLUqbx76qRhtuOgMtnGIOq+4vR9fvt71fwyPcJdnk8nV2GXA02wdj y5ZKT1gKOTozCnKj3yWMbvWCVqAQYRmTWwEPiRSrNmJ9smjxULVhs0nOzt4BcS5+ cs2VAofO7555YCEKG90qYd8obAj83A== =SRXS -----END PGP SIGNATURE----- --lteA1dqeVaWQ9QQl--