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=-12.7 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT 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 437E6C43457 for ; Mon, 12 Oct 2020 15:46:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 137B520776 for ; Mon, 12 Oct 2020 15:46:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2390571AbgJLPqH (ORCPT ); Mon, 12 Oct 2020 11:46:07 -0400 Received: from mga07.intel.com ([134.134.136.100]:28365 "EHLO mga07.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2389540AbgJLPpw (ORCPT ); Mon, 12 Oct 2020 11:45:52 -0400 IronPort-SDR: kbiOaKC5vU/CTWeP9HTASalAvyUqioQbkNadgcM/v/zlfupa4H8UYozOP5oXpRWY8EP9eLP7oX GSwhyDyOmoLA== X-IronPort-AV: E=McAfee;i="6000,8403,9772"; a="229939275" X-IronPort-AV: E=Sophos;i="5.77,367,1596524400"; d="scan'208";a="229939275" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga005.jf.intel.com ([10.7.209.41]) by orsmga105.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 12 Oct 2020 08:45:52 -0700 IronPort-SDR: +ewMVzeoFtp7hZWuheQMK+NfvJHqiZ2L5PLnIo0TG52tI9roPU3/FZ2SIb9/1eHXUJalgwAv8R IlBuFr16OCVQ== X-IronPort-AV: E=Sophos;i="5.77,367,1596524400"; d="scan'208";a="530012635" Received: from yyu32-desk.sc.intel.com ([143.183.136.146]) by orsmga005-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 12 Oct 2020 08:45:51 -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 Cc: Yu-cheng Yu Subject: [PATCH v14 3/7] x86/cet/ibt: Handle signals for Indirect Branch Tracking Date: Mon, 12 Oct 2020 08:45:26 -0700 Message-Id: <20201012154530.28382-4-yu-cheng.yu@intel.com> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20201012154530.28382-1-yu-cheng.yu@intel.com> References: <20201012154530.28382-1-yu-cheng.yu@intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-api@vger.kernel.org An indirect CALL/JMP moves the indirect branch tracking (IBT) state machine to WAIT_ENDBR status until the instruction reaches an ENDBR opcode. If the CALL/JMP does not reach an ENDBR opcode, the processor raises a control- protection fault. WAIT_ENDBR status can be read from MSR_IA32_U_CET. WAIT_ENDBR is cleared for signal handling, and restored for sigreturn. IBT state machine is described in Intel SDM Vol. 1, Sec. 18.3. Signed-off-by: Yu-cheng Yu --- arch/x86/kernel/cet.c | 27 +++++++++++++++++++++++++-- arch/x86/kernel/fpu/signal.c | 8 +++++--- 2 files changed, 30 insertions(+), 5 deletions(-) diff --git a/arch/x86/kernel/cet.c b/arch/x86/kernel/cet.c index 1dcd16aa4f90..0edcbd70f408 100644 --- a/arch/x86/kernel/cet.c +++ b/arch/x86/kernel/cet.c @@ -295,6 +295,13 @@ void cet_restore_signal(struct sc_ext *sc_ext) msr_val |= CET_SHSTK_EN; } + if (cet->ibt_enabled) { + msr_val |= (CET_ENDBR_EN | CET_NO_TRACK_EN); + + if (sc_ext->wait_endbr) + msr_val |= CET_WAIT_ENDBR; + } + if (test_thread_flag(TIF_NEED_FPU_LOAD)) cet_user_state->user_cet = msr_val; else @@ -335,9 +342,25 @@ int cet_setup_signal(bool ia32, unsigned long rstor_addr, struct sc_ext *sc_ext) sc_ext->ssp = new_ssp; } - if (ssp) { + if (ssp || cet->ibt_enabled) { + start_update_msrs(); - wrmsrl(MSR_IA32_PL3_SSP, ssp); + + if (ssp) + wrmsrl(MSR_IA32_PL3_SSP, ssp); + + if (cet->ibt_enabled) { + u64 r; + + rdmsrl(MSR_IA32_U_CET, r); + + if (r & CET_WAIT_ENDBR) { + sc_ext->wait_endbr = 1; + r &= ~CET_WAIT_ENDBR; + wrmsrl(MSR_IA32_U_CET, r); + } + } + end_update_msrs(); } diff --git a/arch/x86/kernel/fpu/signal.c b/arch/x86/kernel/fpu/signal.c index c0c2141cb4b3..077853ef6f48 100644 --- a/arch/x86/kernel/fpu/signal.c +++ b/arch/x86/kernel/fpu/signal.c @@ -57,7 +57,8 @@ int save_cet_to_sigframe(int ia32, void __user *fp, unsigned long restorer) { int err = 0; - if (!current->thread.cet.shstk_size) + if (!current->thread.cet.shstk_size && + !current->thread.cet.ibt_enabled) return 0; if (fp) { @@ -89,7 +90,8 @@ static int get_cet_from_sigframe(int ia32, void __user *fp, struct sc_ext *ext) memset(ext, 0, sizeof(*ext)); - if (!current->thread.cet.shstk_size) + if (!current->thread.cet.shstk_size && + !current->thread.cet.ibt_enabled) return 0; if (fp) { @@ -577,7 +579,7 @@ static unsigned long fpu__alloc_sigcontext_ext(unsigned long sp) * sigcontext_ext is at: fpu + fpu_user_xstate_size + * FP_XSTATE_MAGIC2_SIZE, then aligned to 8. */ - if (cet->shstk_size) + if (cet->shstk_size || cet->ibt_enabled) sp -= (sizeof(struct sc_ext) + 8); return sp; -- 2.21.0