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=-11.0 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 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 DB009C433B4 for ; Wed, 28 Apr 2021 20:31:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8F2E061445 for ; Wed, 28 Apr 2021 20:31:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240614AbhD1Uby (ORCPT ); Wed, 28 Apr 2021 16:31:54 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57904 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240381AbhD1Uby (ORCPT ); Wed, 28 Apr 2021 16:31:54 -0400 Received: from mail-pf1-x42f.google.com (mail-pf1-x42f.google.com [IPv6:2607:f8b0:4864:20::42f]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id F24D7C06138A for ; Wed, 28 Apr 2021 13:31:08 -0700 (PDT) Received: by mail-pf1-x42f.google.com with SMTP id v191so2762335pfc.8 for ; Wed, 28 Apr 2021 13:31:08 -0700 (PDT) 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=3hSpg15pn1DIdYpOUvqCiqtWYItHFsCiBWHhgVzIduI=; b=BkbeBwVw+8kNECD6Fty+KhB2F/UCVh05XwhcmlkxtMeFxAnK7zGdWcsac/9xp0+LIX QhDKeE0HJgN1UAjMxq9aw9nfBPmpRThrwcnkH4T+puZNHQ/z+cvGTjixSvIDru7sf04s rh4FBCLuTD4dbIHz7KjZ6We84KXuMRxzFeZgo= 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=3hSpg15pn1DIdYpOUvqCiqtWYItHFsCiBWHhgVzIduI=; b=JhXDfS2IpiWOsfm+tgZqFoapcq69d0mHCZm30Kl1lrDfq0EEUqyIZZFhUVoCjIFwfe CgldXw20xdvNLRtMULp8PQaVNOHNOBEZHAOqKAFc9i60rfo6CamSqWrzNm7/vV3paW6G T58zZJbXPi41YbR+rwRoM9DzVPyxJCdqvJqSRKEw5P9srcIQyUouo8uaQZECwHscyEk5 e6Gy4heafN8dc/e8U00CVSaOAXncYO0UG35UFCtMIT+o0TvcytOjVrgU4IrRdcOvu6E2 XCtGMjlNOyic2hn2GZWXTJVFMKssy4tuo5zHN0YHZa68g2cgiNgrRZVKgKIZ+Fj3kiL4 dm/A== X-Gm-Message-State: AOAM530kOnt6rc2ZvNwj26Sas3Z5AiInrAt0EkG2UwhZMRA3pmU2UGQV rj7FrP5df33USdSFpEhz/Yt1wA== X-Google-Smtp-Source: ABdhPJwCKd2mYh14iAXFwA+maLNCPvFw4QLlsMbajfD2OFtjkT8lLbxJACSI1jhHg7cX9+DygGbR1w== X-Received: by 2002:a63:6486:: with SMTP id y128mr10004830pgb.414.1619641868603; Wed, 28 Apr 2021 13:31:08 -0700 (PDT) Received: from www.outflux.net (smtp.outflux.net. [198.145.64.163]) by smtp.gmail.com with ESMTPSA id oj6sm5513649pjb.5.2021.04.28.13.31.07 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 28 Apr 2021 13:31:08 -0700 (PDT) Date: Wed, 28 Apr 2021 13:31:07 -0700 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 , Haitao Huang Subject: Re: [PATCH v26 3/9] x86/cet/ibt: Handle signals for Indirect Branch Tracking Message-ID: <202104281331.C09D5479E@keescook> References: <20210427204720.25007-1-yu-cheng.yu@intel.com> <20210427204720.25007-4-yu-cheng.yu@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210427204720.25007-4-yu-cheng.yu@intel.com> Precedence: bulk List-ID: X-Mailing-List: linux-api@vger.kernel.org On Tue, Apr 27, 2021 at 01:47:14PM -0700, 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