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 591FAC433EF for ; Wed, 9 Feb 2022 21:56:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234113AbiBIVzx (ORCPT ); Wed, 9 Feb 2022 16:55:53 -0500 Received: from gmail-smtp-in.l.google.com ([23.128.96.19]:48916 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233832AbiBIVzw (ORCPT ); Wed, 9 Feb 2022 16:55:52 -0500 Received: from mga01.intel.com (mga01.intel.com [192.55.52.88]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 335EFDF8E3DC; Wed, 9 Feb 2022 13:55:55 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1644443755; x=1675979755; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=cyA26yd1PlTgRBILEYh8lkKpW6JLK7FPHg1Hg2iCiiE=; b=hUmdl/NXm598+NQ2gNvv0VzJoFxlUZElIyTunvyrues4zxSjl6pmW2EI Ab0rBLPFCW6y2lUDXuULbLSb/g78ASfQlqxFuwNEVfu0NrdgQNumqu/Sp BAsUtAMu8D8Xe4MUawMMArnNpV+7RNIJ3ydG/UAtIp6N6WAoQeQBvhu7N iTZ3QCGBPOpZFybGdBU6WUVGJazdJ3u7rBrxRn2oeDu92hU3awzrtDmBD CIJ8fs8Pma5gyy0NJfpJB5Gy65ATYRl5xdjyZZXjrh4+QtvYNC+fgCbOb iZcDBtH9oWbajObvo4qjpD5f8fBwhlgWsdh5eRi4b8FAN/Ol2ybsoGPcW w==; X-IronPort-AV: E=McAfee;i="6200,9189,10253"; a="273893745" X-IronPort-AV: E=Sophos;i="5.88,356,1635231600"; d="scan'208";a="273893745" Received: from fmsmga008.fm.intel.com ([10.253.24.58]) by fmsmga101.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 09 Feb 2022 13:55:55 -0800 X-IronPort-AV: E=Sophos;i="5.88,356,1635231600"; d="scan'208";a="585735193" Received: from sanvery-mobl.amr.corp.intel.com (HELO [10.212.232.139]) ([10.212.232.139]) by fmsmga008-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 09 Feb 2022 13:55:53 -0800 Message-ID: <123f9a29-ddcd-13e5-68a1-22c6d938d76c@intel.com> Date: Wed, 9 Feb 2022 13:55:52 -0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.5.0 Subject: Re: [PATCH 14/35] mm: Introduce VM_SHADOW_STACK for shadow stack memory Content-Language: en-US To: Rick Edgecombe , x86@kernel.org, "H . Peter Anvin" , Thomas Gleixner , Ingo Molnar , linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-mm@kvack.org, linux-arch@vger.kernel.org, linux-api@vger.kernel.org, Arnd Bergmann , Andy Lutomirski , Balbir Singh , Borislav Petkov , Cyrill Gorcunov , Dave Hansen , Eugene Syromiatnikov , Florian Weimer , "H . J . Lu" , Jann Horn , Jonathan Corbet , Kees Cook , Mike Kravetz , Nadav Amit , Oleg Nesterov , Pavel Machek , Peter Zijlstra , Randy Dunlap , "Ravi V . Shankar" , Dave Martin , Weijiang Yang , "Kirill A . Shutemov" , joao.moreira@intel.com, John Allen , kcc@google.com, eranian@google.com Cc: Yu-cheng Yu References: <20220130211838.8382-1-rick.p.edgecombe@intel.com> <20220130211838.8382-15-rick.p.edgecombe@intel.com> From: Dave Hansen In-Reply-To: <20220130211838.8382-15-rick.p.edgecombe@intel.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-api@vger.kernel.org On 1/30/22 13:18, Rick Edgecombe wrote: > A shadow stack PTE must be read-only and have _PAGE_DIRTY set. However, > read-only and Dirty PTEs also exist for copy-on-write (COW) pages. These > two cases are handled differently for page faults. Introduce > VM_SHADOW_STACK to track shadow stack VMAs. This is also a very appropriate place to remind folks that VM_WRITE is mutually exclusive with this flag. That's pretty important.