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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3F60FC433F5 for ; Fri, 30 Sep 2022 19:16:55 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 6BA9E6B0074; Fri, 30 Sep 2022 15:16:54 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 669BD8D0001; Fri, 30 Sep 2022 15:16:54 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 5315F6B0078; Fri, 30 Sep 2022 15:16:54 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0011.hostedemail.com [216.40.44.11]) by kanga.kvack.org (Postfix) with ESMTP id 42BB56B0074 for ; Fri, 30 Sep 2022 15:16:54 -0400 (EDT) Received: from smtpin04.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay05.hostedemail.com (Postfix) with ESMTP id 0EE4340311 for ; Fri, 30 Sep 2022 19:16:54 +0000 (UTC) X-FDA: 79969709148.04.CC446B5 Received: from mga06.intel.com (mga06b.intel.com [134.134.136.31]) by imf25.hostedemail.com (Postfix) with ESMTP id 9DC45A0012 for ; Fri, 30 Sep 2022 19:16:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1664565412; x=1696101412; h=message-id:date:mime-version:subject:to:references:from: in-reply-to:content-transfer-encoding; bh=Kvg1hmWTB85MGkRfrUrnIZoG1lyvNoMRxkPltDY9hDY=; b=cx+dL0xEZSb1sjuB7UiPDbDYJvsozeBbclBO6QKcHVIwySpQEKi+auT/ dxn22wJcqxbHA9fzNeIXunwN1Y2lHGNhfUZS1DYbaEH/5Pwd1xg6iqdp1 76NQw+ZRGTcTrm7iQUQATywWtWPBYTvGs9AqEhFQP3XlcxjfnsAqsYtC/ IvPuKGr649ziMSDDhvwoPIMXkaNtdvowRaXA8sg0p2RjbzHJC2ZbnB+HQ Uwwnkt312s42EgVilKlNuh8xm4RRHZo5sfmP5hS44ZM5DVT2hEfq/SBz5 HSBWUk3WPGhaAnHrd3AUXM3CmtyKTZGq/HiYy4ZpTxRSNLxadsGLoeX1e A==; X-IronPort-AV: E=McAfee;i="6500,9779,10486"; a="364118352" X-IronPort-AV: E=Sophos;i="5.93,358,1654585200"; d="scan'208";a="364118352" Received: from fmsmga002.fm.intel.com ([10.253.24.26]) by orsmga104.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 30 Sep 2022 12:16:51 -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 ARC-Authentication-Results: i=1; imf25.hostedemail.com; dkim=none ("invalid DKIM record") header.d=intel.com header.s=Intel header.b=cx+dL0xE; spf=pass (imf25.hostedemail.com: domain of dave.hansen@intel.com designates 134.134.136.31 as permitted sender) smtp.mailfrom=dave.hansen@intel.com; dmarc=pass (policy=none) header.from=intel.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1664565413; a=rsa-sha256; cv=none; b=3rPd8I35vsO26CjQkvqZ0UmayP3tQapygRmMy559j+e9EuTF5peq/aND2xo+TS4uO0ZPP1 iGt8PoxOMX+I+ql5GEwvgzZWTuOKhkDsZh5c27hYFKP7yIG5GzJwJvtFz2wEQCU4xfAWN4 sqjWGvJ/IUDBf1hq5FhP8+7F1JYNME8= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1664565413; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=oeSPseNsm6qjfLesYg/prM2HdsfaMP+I+dU3tttSlXo=; b=FUeCzcXSftFKrmu9gNBlvStF5g/H6bDg4/V9ygkDzWGLuVpOPBJPzBP/dwPh4K3kJ0QXHS QGEYjf+mICzJHlJK2x50GPazHLm7YN0gjGXbo61jaI1U+UKYj6nYCw7AHEJI8cWLrEy5ds k4ijsQn/DuyALOL//7cPNmhQ+PYf3hw= X-Rspam-User: Authentication-Results: imf25.hostedemail.com; dkim=none ("invalid DKIM record") header.d=intel.com header.s=Intel header.b=cx+dL0xE; spf=pass (imf25.hostedemail.com: domain of dave.hansen@intel.com designates 134.134.136.31 as permitted sender) smtp.mailfrom=dave.hansen@intel.com; dmarc=pass (policy=none) header.from=intel.com X-Rspamd-Server: rspam10 X-Stat-Signature: fateotwxbaw4hy5jkihtx5ethf98pnct X-Rspamd-Queue-Id: 9DC45A0012 X-HE-Tag: 1664565412-43250 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: 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.