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 3FEC4C43217 for ; Mon, 7 Feb 2022 22:40:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S244753AbiBGWkG (ORCPT ); Mon, 7 Feb 2022 17:40:06 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55222 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S244667AbiBGWkD (ORCPT ); Mon, 7 Feb 2022 17:40:03 -0500 Received: from mga18.intel.com (mga18.intel.com [134.134.136.126]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5E021C0612A4; Mon, 7 Feb 2022 14:40:02 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1644273602; x=1675809602; h=message-id:date:mime-version:to:cc:references:from: subject:in-reply-to:content-transfer-encoding; bh=9YOiN21DFWOvsXWRc0EIImHeT95XLZnWE4OurJAm4GA=; b=SR8WqVVQz99gERWJTyxsNki2ow4mrUHdUweOUx7MR2pw/gLE5alEmvso yi0auCejG205DR6Rpib3/vfCnidH4DtIT4ZQpw6qYqfMa/EC9s+xwwQXx oO+4KA4gSBnGFk8W+QjkPSjqgwQQ++3RaieVJUoKx0WkdvJGC13dfmXSQ dGstVL92X2/ArEsX5ejtHi2blas834vX56X99PNoUULFKEMmV83V07s+o lV/jUIONI95eq6vF3Wj4hNLrSrECRHwWav1Bk0ESKB7tHr0mEFVyU8yWp NatH/C0/YVSwmN8l70Mr/PN3dhmzNy9TumRN5d7VKWjMFtdpmnYh64Nix w==; X-IronPort-AV: E=McAfee;i="6200,9189,10251"; a="232388972" X-IronPort-AV: E=Sophos;i="5.88,351,1635231600"; d="scan'208";a="232388972" Received: from orsmga007.jf.intel.com ([10.7.209.58]) by orsmga106.jf.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 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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.