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 X-Spam-Level: X-Spam-Status: No, score=-11.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=unavailable 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 3E0A3C433DB for ; Thu, 4 Feb 2021 19:54:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E033264F45 for ; Thu, 4 Feb 2021 19:54:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231686AbhBDTxu (ORCPT ); Thu, 4 Feb 2021 14:53:50 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38908 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239395AbhBDTvh (ORCPT ); Thu, 4 Feb 2021 14:51:37 -0500 Received: from mail-pg1-x532.google.com (mail-pg1-x532.google.com [IPv6:2607:f8b0:4864:20::532]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id EADE6C061797 for ; Thu, 4 Feb 2021 11:50:11 -0800 (PST) Received: by mail-pg1-x532.google.com with SMTP id z21so2866932pgj.4 for ; Thu, 04 Feb 2021 11:50:11 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=/xqrcr0spyydoAlLuc99uq3cskkQtgF/Uv01pgyq0ds=; b=Du7iFlDWFI6enawRDcehFsluT1W0OthyU+AXhyMr2mtTzw5vkuy1H9ceFkQ99qBJSj YRZMriPtX53oHb/EVc4MsIXCaJaAWcAnrhRVJuNdh31kUgip6KfbWaqBmyGFYUzIukx5 G+L+T8Il52MlwCw8EchSrWSoJXEI9rmSN/3Nw= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=/xqrcr0spyydoAlLuc99uq3cskkQtgF/Uv01pgyq0ds=; b=t248dYVuIaM1Xl/YLTlIZ5Vn6eW35K89JRkCsQeC0y1BNFvwKiiUy+Y5CCPmNVhduJ iYQs+lOH5thn093LdN5MDpbN7ssLoHhQY7bFm6eI3Byc0+eoXHAA3RTwttiFheo236os grDcgXDfBcDcJ+6AnNEB7kaySRFhtafuHON2Dqt7V7RNbTmC54PRaXKMNVBHyKNaxGy+ qXZzZkGsLzXtSaZWO6FtnceCtVBnAVJ1KDohNrxakptDJ9cwtu0wGqfFgeeL/RnwmbJO MRdqz/VuOdxy3eFgP6O26LENS7k1SpuuiwmnA/oXdpFrFIZTnCe8BbA6VErJK266+BBt srOw== X-Gm-Message-State: AOAM533WOgRPlZrX/KNNku5cuvsgbsoYtq5530zBdidF28KxjICW8EFD J5tkGJsoeI6bWn6Az7Nxow+e4g== X-Google-Smtp-Source: ABdhPJxtHH5uZ1Z7iC4WZebLw2vn0Wmq76brvfnWdJDqyjrAJu644mdWx5Auq5N/jwzL0m0zXveDdg== X-Received: by 2002:a62:ac06:0:b029:1cb:35bc:5e2c with SMTP id v6-20020a62ac060000b02901cb35bc5e2cmr894242pfe.42.1612468211577; Thu, 04 Feb 2021 11:50:11 -0800 (PST) Received: from www.outflux.net (smtp.outflux.net. [198.145.64.163]) by smtp.gmail.com with ESMTPSA id z16sm7448343pgj.51.2021.02.04.11.50.10 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 04 Feb 2021 11:50:10 -0800 (PST) Date: Thu, 4 Feb 2021 11:50:09 -0800 From: Kees Cook To: Yu-cheng Yu Cc: 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 , Mike Kravetz , Nadav Amit , Oleg Nesterov , Pavel Machek , Peter Zijlstra , Randy Dunlap , "Ravi V. Shankar" , Vedvyas Shanbhogue , Dave Martin , Weijiang Yang , Pengfei Xu Subject: Re: [PATCH v19 3/7] x86/cet/ibt: Handle signals for Indirect Branch Tracking Message-ID: <202102041150.3614663DA@keescook> References: <20210203225902.479-1-yu-cheng.yu@intel.com> <20210203225902.479-4-yu-cheng.yu@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210203225902.479-4-yu-cheng.yu@intel.com> Precedence: bulk List-ID: X-Mailing-List: linux-api@vger.kernel.org On Wed, Feb 03, 2021 at 02:58:58PM -0800, Yu-cheng Yu wrote: > When an indirect CALL/JMP instruction is executed and before it reaches > the target, it is in 'WAIT_ENDBR' status, which can be read from > MSR_IA32_U_CET. The status is part of a task's status before a signal is > raised and preserved in the signal frame. It is restored for sigreturn. > > IBT state machine is described in Intel SDM Vol. 1, Sec. 18.3. > > Signed-off-by: Yu-cheng Yu Reviewed-by: Kees Cook -- Kees Cook