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 20F67C433EF for ; Wed, 9 Feb 2022 21:55:57 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 7A9016B0073; Wed, 9 Feb 2022 16:55:57 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 72F566B0075; Wed, 9 Feb 2022 16:55:57 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 5AA3A6B0078; Wed, 9 Feb 2022 16:55:57 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0015.hostedemail.com [216.40.44.15]) by kanga.kvack.org (Postfix) with ESMTP id 454A96B0073 for ; Wed, 9 Feb 2022 16:55:57 -0500 (EST) Received: from smtpin18.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id 0990F987A6 for ; Wed, 9 Feb 2022 21:55:57 +0000 (UTC) X-FDA: 79124599554.18.3B256C7 Received: from mga09.intel.com (mga09.intel.com [134.134.136.24]) by imf31.hostedemail.com (Postfix) with ESMTP id 3920120005 for ; Wed, 9 Feb 2022 21:55:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1644443756; x=1675979756; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=cyA26yd1PlTgRBILEYh8lkKpW6JLK7FPHg1Hg2iCiiE=; b=cyTOT0nTOCLE0cZZwPP4mREDutdnuuBKCOYGChzZbLEdJSxoXo/TvVjH 8jHNJSrU1rxcMbgclquNyOPLHz0wUdEMPK14V8PkBwNdZeplJ42eOIaR9 IAr54sODmeWarVMuRrpSH/xwM5rUMDCaJdGkzj6JWJW28N5rMWTKmStqO 9mhbm9P9mg3cuQZ5Krhnt8o6T1pmixxn2Vxz53/gf5Y1HoNzQusHF7E8s A7gEskJC0PaCnZBGVt4FKwFyGllFpMmHefD2Tgtrn6h/XhdCzrB0dKdGM GuLX4GNp8ifdDg5BfHsXPBDAHr/ntYYRDwB1KhM8Qjz0djNUaBIxWJnvQ Q==; X-IronPort-AV: E=McAfee;i="6200,9189,10253"; a="249103729" X-IronPort-AV: E=Sophos;i="5.88,356,1635231600"; d="scan'208";a="249103729" Received: from fmsmga008.fm.intel.com ([10.253.24.58]) by orsmga102.jf.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 X-Rspamd-Queue-Id: 3920120005 X-Stat-Signature: i9i53zwm6qetszkfpi5kgd86xoro97xm X-Rspam-User: Authentication-Results: imf31.hostedemail.com; dkim=pass header.d=intel.com header.s=Intel header.b=cyTOT0nT; spf=none (imf31.hostedemail.com: domain of dave.hansen@intel.com has no SPF policy when checking 134.134.136.24) smtp.mailfrom=dave.hansen@intel.com; dmarc=pass (policy=none) header.from=intel.com X-Rspamd-Server: rspam05 X-HE-Tag: 1644443756-472859 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: > 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.