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 338F2C433FE for ; Mon, 7 Feb 2022 22:40:06 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 773986B0073; Mon, 7 Feb 2022 17:40:05 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 723B86B0075; Mon, 7 Feb 2022 17:40:05 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 5EADE6B0078; Mon, 7 Feb 2022 17:40:05 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0159.hostedemail.com [216.40.44.159]) by kanga.kvack.org (Postfix) with ESMTP id 510F36B0073 for ; Mon, 7 Feb 2022 17:40:05 -0500 (EST) Received: from smtpin17.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id 12455181DB37D for ; Mon, 7 Feb 2022 22:40:05 +0000 (UTC) X-FDA: 79117453170.17.F61F95B Received: from mga01.intel.com (mga01.intel.com [192.55.52.88]) by imf23.hostedemail.com (Postfix) with ESMTP id 8AF2F140006 for ; Mon, 7 Feb 2022 22:40:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1644273603; x=1675809603; h=message-id:date:mime-version:to:cc:references:from: subject:in-reply-to:content-transfer-encoding; bh=9YOiN21DFWOvsXWRc0EIImHeT95XLZnWE4OurJAm4GA=; b=gc4YsTVFvol7VQeswyp+m2zQncuDD7Me0Jkr6sPStgESZB4Y1yKB4ke5 5cJ0ScjfhiyDNX5eDKG8Sf4Ufac8hJU+Cs7SKIu1bHdD4XRCzod4lPb0P qzZVhHXEcJ2LrXcXtGXyk5P7OABUvXdNSXoxEtz9XINMhYRkClOUYUsf8 1gHh+UhP1VM3uSjDcdaj23YTHAcuA7bYkOyF79G0AmGmbjLoHlvbqZSA7 R4UKN3nQEEBRAhRcRelZk0uyAFuY6KItr/0aNTjlvCP9qvUKL9gUgP1F8 qEQ7Ow0bepBW2T1ZleJIXu29/dVjVVThpZ9/DZEESL6yrMTVBvr7eWOVn Q==; X-IronPort-AV: E=McAfee;i="6200,9189,10251"; a="273347227" X-IronPort-AV: E=Sophos;i="5.88,351,1635231600"; d="scan'208";a="273347227" Received: from orsmga007.jf.intel.com ([10.7.209.58]) by fmsmga101.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 07 Feb 2022 14:40:01 -0800 X-IronPort-AV: E=Sophos;i="5.88,351,1635231600"; d="scan'208";a="525306836" Received: from hgrunes-mobl1.amr.corp.intel.com (HELO [10.251.3.57]) ([10.251.3.57]) by orsmga007-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 07 Feb 2022 14:40:00 -0800 Message-ID: <248ef880-025d-54ce-f3ce-fed0e50a0445@intel.com> Date: Mon, 7 Feb 2022 14:39:57 -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> <20220130211838.8382-3-rick.p.edgecombe@intel.com> From: Dave Hansen Subject: Re: [PATCH 02/35] x86/cet/shstk: Add Kconfig option for Shadow Stack In-Reply-To: <20220130211838.8382-3-rick.p.edgecombe@intel.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 8AF2F140006 X-Stat-Signature: sbrgzkwj9enpax4ycsirtrcso3j3yuap X-Rspam-User: nil Authentication-Results: imf23.hostedemail.com; dkim=pass header.d=intel.com header.s=Intel header.b=gc4YsTVF; spf=none (imf23.hostedemail.com: domain of dave.hansen@intel.com has no SPF policy when checking 192.55.52.88) smtp.mailfrom=dave.hansen@intel.com; dmarc=pass (policy=none) header.from=intel.com X-HE-Tag: 1644273603-234126 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: > +config X86_SHADOW_STACK > + prompt "Intel Shadow Stack" > + def_bool n > + depends on AS_WRUSS > + depends on ARCH_HAS_SHADOW_STACK > + select ARCH_USES_HIGH_VMA_FLAGS > + help > + Shadow Stack protection is a hardware feature that detects function > + return address corruption. This helps mitigate ROP attacks. > + Applications must be enabled to use it, and old userspace does not > + get protection "for free". > + Support for this feature is present on Tiger Lake family of > + processors released in 2020 or later. Enabling this feature > + increases kernel text size by 3.7 KB. I guess the "2020" comment is still OK. But, given that it's on AMD and a could of other Intel models, maybe we should just leave this at: CPUs supporting shadow stacks were first released in 2020. If we say anything. We mostly want folks to just go read the documentation if they needs more details.