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 BB0E7C43217 for ; Fri, 30 Sep 2022 19:16:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231477AbiI3TQz (ORCPT ); Fri, 30 Sep 2022 15:16:55 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41594 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229531AbiI3TQw (ORCPT ); Fri, 30 Sep 2022 15:16:52 -0400 Received: from mga01.intel.com (mga01.intel.com [192.55.52.88]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7B21C178A0F; Fri, 30 Sep 2022 12:16:51 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1664565411; x=1696101411; h=message-id:date:mime-version:subject:to:references:from: in-reply-to:content-transfer-encoding; bh=Kvg1hmWTB85MGkRfrUrnIZoG1lyvNoMRxkPltDY9hDY=; b=f0+7LnnWGHbHp3JKFxkWhYftdonMaU5jGwf4NjcABEKRVTJQRdcwFbZB rIi9H6lxfFwRNrAH8KmIeOFwon6V2Cv3FWvx0knjHDPPCMfRF2lQpnfrB IAZRIlhJdxf0qsW/jdOLY1i5WAjjX5EIXWQRI4gDx10baGF0cMdXrhK5D uiFjrfPB9ECP47eEs9PvNdSYuEz/MAwPKPx6RYVr263gmdtceiNa5nfbe yU82F57hWCPtUuvfiIQ28Y9T77HDCkSi+ck6hIR6yP1Pv/rrHzjuu4NQk 8S3r5BYJtCJrnsfq41155S/Iq35LjdqDN2NpW/o/CQMAbMo/sk2wyKo+d A==; X-IronPort-AV: E=McAfee;i="6500,9779,10486"; a="328656818" X-IronPort-AV: E=Sophos;i="5.93,358,1654585200"; d="scan'208";a="328656818" Received: from fmsmga002.fm.intel.com ([10.253.24.26]) by fmsmga101.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 30 Sep 2022 12:16:50 -0700 X-IronPort-AV: E=McAfee;i="6500,9779,10486"; a="726978714" X-IronPort-AV: E=Sophos;i="5.93,358,1654585200"; d="scan'208";a="726978714" Received: from lzearing-mobl.amr.corp.intel.com (HELO [10.209.49.67]) ([10.209.49.67]) by fmsmga002-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 30 Sep 2022 12:16:48 -0700 Message-ID: <9fed0342-2d02-aaf2-ed66-20ff08bdfd0b@intel.com> Date: Fri, 30 Sep 2022 12:16:47 -0700 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.11.0 Subject: Re: [PATCH v2 22/39] mm: Don't allow write GUPs to 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" , Weijiang Yang , "Kirill A . Shutemov" , joao.moreira@intel.com, John Allen , kcc@google.com, eranian@google.com, rppt@kernel.org, jamorris@linux.microsoft.com, dethoma@microsoft.com References: <20220929222936.14584-1-rick.p.edgecombe@intel.com> <20220929222936.14584-23-rick.p.edgecombe@intel.com> From: Dave Hansen In-Reply-To: <20220929222936.14584-23-rick.p.edgecombe@intel.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 9/29/22 15:29, Rick Edgecombe wrote: > @@ -1633,6 +1633,9 @@ static inline bool __pte_access_permitted(unsigned long pteval, bool write) > { > unsigned long need_pte_bits = _PAGE_PRESENT|_PAGE_USER; > > + if (write && (pteval & (_PAGE_RW | _PAGE_DIRTY)) == _PAGE_DIRTY) > + return 0; Do we not have a helper for this? Seems a bit messy to open-code these shadow-stack permissions. Definitely at least needs a comment.