From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on archive.lwn.net X-Spam-Level: X-Spam-Status: No, score=-6.0 required=5.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI,SPF_HELO_NONE,SPF_NONE autolearn=unavailable autolearn_force=no version=3.4.2 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by archive.lwn.net (Postfix) with ESMTP id 8517B7D923 for ; Thu, 6 Jun 2019 20:18:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726667AbfFFUSi (ORCPT ); Thu, 6 Jun 2019 16:18:38 -0400 Received: from mga14.intel.com ([192.55.52.115]:51127 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727765AbfFFURf (ORCPT ); Thu, 6 Jun 2019 16:17:35 -0400 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga001.fm.intel.com ([10.253.24.23]) by fmsmga103.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 06 Jun 2019 13:17:32 -0700 X-ExtLoop1: 1 Received: from yyu32-desk1.sc.intel.com ([143.183.136.147]) by fmsmga001.fm.intel.com with ESMTP; 06 Jun 2019 13:17:32 -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 Cc: Yu-cheng Yu Subject: [PATCH v7 12/14] x86/vsyscall/64: Fixup shadow stack and branch tracking for vsyscall Date: Thu, 6 Jun 2019 13:09:24 -0700 Message-Id: <20190606200926.4029-13-yu-cheng.yu@intel.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20190606200926.4029-1-yu-cheng.yu@intel.com> References: <20190606200926.4029-1-yu-cheng.yu@intel.com> Sender: linux-doc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-doc@vger.kernel.org When emulating a RET, also unwind the task's shadow stack and cancel the current branch tracking status. Signed-off-by: Yu-cheng Yu --- arch/x86/entry/vsyscall/vsyscall_64.c | 28 +++++++++++++++++++++++++++ 1 file changed, 28 insertions(+) diff --git a/arch/x86/entry/vsyscall/vsyscall_64.c b/arch/x86/entry/vsyscall/vsyscall_64.c index d9d81ad7a400..6869ef9d1e8b 100644 --- a/arch/x86/entry/vsyscall/vsyscall_64.c +++ b/arch/x86/entry/vsyscall/vsyscall_64.c @@ -38,6 +38,8 @@ #include #include #include +#include +#include #define CREATE_TRACE_POINTS #include "vsyscall_trace.h" @@ -92,6 +94,30 @@ static int addr_to_vsyscall_nr(unsigned long addr) return nr; } +void fixup_shstk(void) +{ +#ifdef CONFIG_X86_INTEL_SHADOW_STACK_USER + u64 r; + + if (current->thread.cet.shstk_enabled) { + rdmsrl(MSR_IA32_PL3_SSP, r); + wrmsrl(MSR_IA32_PL3_SSP, r + 8); + } +#endif +} + +void fixup_ibt(void) +{ +#ifdef CONFIG_X86_INTEL_BRANCH_TRACKING_USER + u64 r; + + if (current->thread.cet.ibt_enabled) { + rdmsrl(MSR_IA32_U_CET, r); + wrmsrl(MSR_IA32_U_CET, r & ~MSR_IA32_CET_WAIT_ENDBR); + } +#endif +} + static bool write_ok_or_segv(unsigned long ptr, size_t size) { /* @@ -265,6 +291,8 @@ bool emulate_vsyscall(struct pt_regs *regs, unsigned long address) /* Emulate a ret instruction. */ regs->ip = caller; regs->sp += 8; + fixup_shstk(); + fixup_ibt(); return true; sigsegv: -- 2.17.1