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 CB265C433FE for ; Wed, 9 Feb 2022 22:52:13 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 40C706B0074; Wed, 9 Feb 2022 17:52:13 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 394F46B0078; Wed, 9 Feb 2022 17:52:13 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 20F296B007B; Wed, 9 Feb 2022 17:52:13 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0211.hostedemail.com [216.40.44.211]) by kanga.kvack.org (Postfix) with ESMTP id 0F9F56B0074 for ; Wed, 9 Feb 2022 17:52:13 -0500 (EST) Received: from smtpin23.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id C8ADD181D860A for ; Wed, 9 Feb 2022 22:52:12 +0000 (UTC) X-FDA: 79124741304.23.32EC1B4 Received: from mga06.intel.com (mga06.intel.com [134.134.136.31]) by imf17.hostedemail.com (Postfix) with ESMTP id EC7B640005 for ; Wed, 9 Feb 2022 22:52:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1644447132; x=1675983132; h=message-id:date:mime-version:to:cc:references:from: subject:in-reply-to:content-transfer-encoding; bh=6ftK2HF3TDrt8ahBasUGsCpZEI46Bh6r6PK2GktLqXA=; b=POGYR3rdxWOx+xgLG0tPNIiGpmOcqOM/oA6R/LZBiJwmJS/0ck+dRQa3 6hN+ri0DYMCJRsF1dsSdkOgYdyOASVvElHn7W/PV2uBa/Lua2nXaBI4jk WFk7fhIBHAu1y41bPNm8vcCrgJ5hvU8TuqZJRB8x5R9nvtxM8ZQSZzlkx Ipnkjw0ERgLGI8S5pLBPj6okUejUwCT/5eJPZyBcjC7Iuiqjt5WwZ9E9y 7QkUVSWrAfu1SXkgz0da8FDcUG6qgoaZy2FnWoaVR17Tf7fsSLiRKmYYm UwI5HuXbaLSCOIcrPKqijr3fi4dJ2wRJZJhZv4i7Bf3fEAjbFNUvmw3eL g==; X-IronPort-AV: E=McAfee;i="6200,9189,10253"; a="310102435" X-IronPort-AV: E=Sophos;i="5.88,356,1635231600"; d="scan'208";a="310102435" Received: from orsmga005.jf.intel.com ([10.7.209.41]) by orsmga104.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 09 Feb 2022 14:52:10 -0800 X-IronPort-AV: E=Sophos;i="5.88,356,1635231600"; d="scan'208";a="701445964" Received: from sanvery-mobl.amr.corp.intel.com (HELO [10.212.232.139]) ([10.212.232.139]) by orsmga005-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 09 Feb 2022 14:52:09 -0800 Message-ID: <37426b64-2139-dc24-c7be-f3cefa4f0dd9@intel.com> Date: Wed, 9 Feb 2022 14:52:08 -0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.5.0 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> <20220130211838.8382-21-rick.p.edgecombe@intel.com> From: Dave Hansen Subject: Re: [PATCH 20/35] mm: Update can_follow_write_pte() for shadow stack In-Reply-To: <20220130211838.8382-21-rick.p.edgecombe@intel.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam11 X-Rspam-User: X-Stat-Signature: d7rbnatundyroehhweq4d3o8sgsy36c1 Authentication-Results: imf17.hostedemail.com; dkim=pass header.d=intel.com header.s=Intel header.b=POGYR3rd; dmarc=pass (policy=none) header.from=intel.com; spf=none (imf17.hostedemail.com: domain of dave.hansen@intel.com has no SPF policy when checking 134.134.136.31) smtp.mailfrom=dave.hansen@intel.com X-Rspamd-Queue-Id: EC7B640005 X-HE-Tag: 1644447131-796660 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 1/30/22 13:18, Rick Edgecombe wrote: > Like a writable data page, a shadow stack page is writable, and becomes > read-only during copy-on-write, but it is always dirty. One other thing... The language in these changelogs is a bit sloppy. For instance, what does "always dirty" mean here? pte_dirty()? Or strictly _PAGE_DIRTY? In other words, logically dirty, or literally "has *the* dirty bit set"?