From patchwork Tue Mar 16 15:13:16 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yu-cheng Yu X-Patchwork-Id: 12142437 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id C1E13C43381 for ; Tue, 16 Mar 2021 15:13:49 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 698A26508E for ; Tue, 16 Mar 2021 15:13:49 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 698A26508E Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=intel.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 938758D0010; Tue, 16 Mar 2021 11:13:43 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 90E7D8D0002; Tue, 16 Mar 2021 11:13:43 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 762178D0010; Tue, 16 Mar 2021 11:13:43 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0220.hostedemail.com [216.40.44.220]) by kanga.kvack.org (Postfix) with ESMTP id 4DEDE8D0002 for ; Tue, 16 Mar 2021 11:13:43 -0400 (EDT) Received: from smtpin02.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id 057421803A166 for ; Tue, 16 Mar 2021 15:13:43 +0000 (UTC) X-FDA: 77926081926.02.BF05872 Received: from mga01.intel.com (mga01.intel.com [192.55.52.88]) by imf07.hostedemail.com (Postfix) with ESMTP id F3E1CA001ABB for ; Tue, 16 Mar 2021 15:13:35 +0000 (UTC) IronPort-SDR: Va8a9BIz1RA9iQoM2SmM7IQSwfyafP9RZwostw/LAuw7gyr6QcuRic8vzVcIAz4f1Aikg6o4QN L3i4xEjc+IQA== X-IronPort-AV: E=McAfee;i="6000,8403,9924"; a="209213136" X-IronPort-AV: E=Sophos;i="5.81,251,1610438400"; d="scan'208";a="209213136" Received: from orsmga001.jf.intel.com ([10.7.209.18]) by fmsmga101.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 16 Mar 2021 08:13:30 -0700 IronPort-SDR: /RLryx7L59dd3UdJqntuQHMiDOCDuccNgP0d2n9LHTfD/E+xNf6CHs+k8KWgvc8tQfpqTo5rCR UxDz5dg8tdwg== X-IronPort-AV: E=Sophos;i="5.81,251,1610438400"; d="scan'208";a="449749003" Received: from yyu32-desk.sc.intel.com ([143.183.136.146]) by orsmga001-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 16 Mar 2021 08:13:29 -0700 From: Yu-cheng Yu To: 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" , Vedvyas Shanbhogue , Dave Martin , Weijiang Yang , Pengfei Xu , Haitao Huang Cc: Yu-cheng Yu , Jarkko Sakkinen Subject: [PATCH v23 6/9] x86/entry: Introduce ENDBR macro Date: Tue, 16 Mar 2021 08:13:16 -0700 Message-Id: <20210316151320.6123-7-yu-cheng.yu@intel.com> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20210316151320.6123-1-yu-cheng.yu@intel.com> References: <20210316151320.6123-1-yu-cheng.yu@intel.com> MIME-Version: 1.0 X-Stat-Signature: xs3hn51qmr17xz1fm7n41bnce9mtxphm X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: F3E1CA001ABB Received-SPF: none (intel.com>: No applicable sender policy available) receiver=imf07; identity=mailfrom; envelope-from=""; helo=mga01.intel.com; client-ip=192.55.52.88 X-HE-DKIM-Result: none/none X-HE-Tag: 1615907615-453509 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: ENDBR is a special new instruction for the Indirect Branch Tracking (IBT) component of CET. IBT prevents attacks by ensuring that (most) indirect branches and function calls may only land at ENDBR instructions. Branches that don't follow the rules will result in control flow (#CF) exceptions. ENDBR is a noop when IBT is unsupported or disabled. Most ENDBR instructions are inserted automatically by the compiler, but branch targets written in assembly must have ENDBR added manually. There are two ENDBR versions: one for 64-bit and the other for 32. Introduce a macro to eliminate ifdeffery at call sites. Signed-off-by: Yu-cheng Yu Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Dave Hansen Cc: Jarkko Sakkinen Cc: Peter Zijlstra --- arch/x86/entry/calling.h | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) diff --git a/arch/x86/entry/calling.h b/arch/x86/entry/calling.h index 07a9331d55e7..a63d33f7f069 100644 --- a/arch/x86/entry/calling.h +++ b/arch/x86/entry/calling.h @@ -392,3 +392,21 @@ For 32-bit we have the following conventions - kernel is built with .endm #endif /* CONFIG_SMP */ +/* + * ENDBR is an instruction for the Indirect Branch Tracking (IBT) component + * of CET. IBT prevents attacks by ensuring that (most) indirect branches + * function calls may only land at ENDBR instructions. Branches that don't + * follow the rules will result in control flow (#CF) exceptions. + * ENDBR is a noop when IBT is unsupported or disabled. Most ENDBR + * instructions are inserted automatically by the compiler, but branch + * targets written in assembly must have ENDBR added manually. + */ +.macro ENDBR +#ifdef CONFIG_X86_CET +#ifdef __i386__ + endbr32 +#else + endbr64 +#endif +#endif +.endm