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=-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 56591C2BB4C for ; Tue, 16 Mar 2021 15:13:36 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id CF798650B1 for ; Tue, 16 Mar 2021 15:13:35 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org CF798650B1 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 6ED0E8D000B; Tue, 16 Mar 2021 11:13:35 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 69D5B8D0002; Tue, 16 Mar 2021 11:13:35 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 53E508D000B; Tue, 16 Mar 2021 11:13:35 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0008.hostedemail.com [216.40.44.8]) by kanga.kvack.org (Postfix) with ESMTP id 334368D0002 for ; Tue, 16 Mar 2021 11:13:35 -0400 (EDT) Received: from smtpin25.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id E122B1801D304 for ; Tue, 16 Mar 2021 15:13:34 +0000 (UTC) X-FDA: 77926081548.25.8538636 Received: from mga01.intel.com (mga01.intel.com [192.55.52.88]) by imf21.hostedemail.com (Postfix) with ESMTP id 92609E005F1F for ; Tue, 16 Mar 2021 15:13:30 +0000 (UTC) IronPort-SDR: B/SPow6n63q+SrrDTfClQu/QYGvidGIIUyFeOWZrQGPHfs9qwLQbIUVnWJsss9p3lPr07K225Y /kcN83CdTFlw== X-IronPort-AV: E=McAfee;i="6000,8403,9924"; a="209213117" X-IronPort-AV: E=Sophos;i="5.81,251,1610438400"; d="scan'208";a="209213117" 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 08:13:28 -0700 IronPort-SDR: +H1wZ8FltEIiGz1j4CNBJ9kEmdSVW9b8OoHvKqpQu7ZtE9/oV6+dkw606AXNdQjxhe4nsFEYLW YVLOwMA0NJIQ== X-IronPort-AV: E=Sophos;i="5.81,251,1610438400"; d="scan'208";a="449748983" 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 08:13:27 -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 Subject: [PATCH v23 3/9] x86/cet/ibt: Handle signals for Indirect Branch Tracking Date: Tue, 16 Mar 2021 08:13:13 -0700 Message-Id: <20210316151320.6123-4-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: y6cje6wqnpas4xqjqbnfemy4f7314isr X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 92609E005F1F Received-SPF: none (intel.com>: No applicable sender policy available) receiver=imf21; identity=mailfrom; envelope-from=""; helo=mga01.intel.com; client-ip=192.55.52.88 X-HE-DKIM-Result: none/none X-HE-Tag: 1615907610-190630 Content-Transfer-Encoding: quoted-printable 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: 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 --- arch/x86/kernel/cet.c | 26 ++++++++++++++++++++++++-- arch/x86/kernel/fpu/signal.c | 8 +++++--- 2 files changed, 29 insertions(+), 5 deletions(-) diff --git a/arch/x86/kernel/cet.c b/arch/x86/kernel/cet.c index 3361706ba950..34a26eb7f259 100644 --- a/arch/x86/kernel/cet.c +++ b/arch/x86/kernel/cet.c @@ -300,6 +300,13 @@ void cet_restore_signal(struct sc_ext *sc_ext) msr_val |=3D CET_SHSTK_EN; } =20 + if (cet->ibt_enabled) { + msr_val |=3D (CET_ENDBR_EN | CET_NO_TRACK_EN); + + if (sc_ext->wait_endbr) + msr_val |=3D CET_WAIT_ENDBR; + } + if (test_thread_flag(TIF_NEED_FPU_LOAD)) cet_user_state->user_cet =3D msr_val; else @@ -340,9 +347,24 @@ int cet_setup_signal(bool ia32, unsigned long rstor_= addr, struct sc_ext *sc_ext) sc_ext->ssp =3D new_ssp; } =20 - 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 =3D 1; + r &=3D ~CET_WAIT_ENDBR; + wrmsrl(MSR_IA32_U_CET, r); + } + } + end_update_msrs(); } =20 diff --git a/arch/x86/kernel/fpu/signal.c b/arch/x86/kernel/fpu/signal.c index 270e4649f435..b914d74c8ba6 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, uns= igned long restorer) { int err =3D 0; =20 - if (!current->thread.cet.shstk_size) + if (!current->thread.cet.shstk_size && + !current->thread.cet.ibt_enabled) return 0; =20 if (fp) { @@ -89,7 +90,8 @@ static int get_cet_from_sigframe(int ia32, void __user = *fp, struct sc_ext *ext) =20 memset(ext, 0, sizeof(*ext)); =20 - if (!current->thread.cet.shstk_size) + if (!current->thread.cet.shstk_size && + !current->thread.cet.ibt_enabled) return 0; =20 if (fp) { @@ -577,7 +579,7 @@ static unsigned long fpu__alloc_sigcontext_ext(unsign= ed 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 -=3D (sizeof(struct sc_ext) + 8); =20 return sp; --=20 2.21.0