Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933506AbdCHA4L (ORCPT ); Tue, 7 Mar 2017 19:56:11 -0500 Received: from mga14.intel.com ([192.55.52.115]:54209 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933223AbdCHA4H (ORCPT ); Tue, 7 Mar 2017 19:56:07 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.36,261,1486454400"; d="scan'208";a="1105982622" From: Ricardo Neri To: Ingo Molnar , Thomas Gleixner , "H. Peter Anvin" , Andy Lutomirski , Borislav Petkov Cc: Peter Zijlstra , Andrew Morton , Brian Gerst , Chris Metcalf , Dave Hansen , Paolo Bonzini , Liang Z Li , Masami Hiramatsu , Huang Rui , Jiri Slaby , Jonathan Corbet , "Michael S. Tsirkin" , Paul Gortmaker , Vlastimil Babka , Chen Yucong , Alexandre Julliard , Stas Sergeev , Fenghua Yu , "Ravi V. Shankar" , Shuah Khan , linux-kernel@vger.kernel.org, x86@kernel.org, linux-msdos@vger.kernel.org, wine-devel@winehq.org, Ricardo Neri , Tony Luck Subject: [v6 PATCH 19/21] x86/traps: Fixup general protection faults caused by UMIP Date: Tue, 7 Mar 2017 16:32:52 -0800 Message-Id: <20170308003254.27833-20-ricardo.neri-calderon@linux.intel.com> X-Mailer: git-send-email 2.9.3 In-Reply-To: <20170308003254.27833-1-ricardo.neri-calderon@linux.intel.com> References: <20170308003254.27833-1-ricardo.neri-calderon@linux.intel.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2375 Lines: 65 If the User-Mode Instruction Prevention CPU feature is available and enabled, a general protection fault will be issued if the instructions sgdt, sldt, sidt, str or smsw are executed from user-mode context (CPL > 0). If the fault was caused by any of the instructions protected by UMIP, fixup_umip_exception will emulate dummy results for these instructions. If emulation is successful, the result is passed to the user space program and no SIGSEGV signal is emitted. Please note that fixup_umip_exception also caters for the case when the fault originated while running in virtual-8086 mode. Cc: Andy Lutomirski Cc: Andrew Morton Cc: H. Peter Anvin Cc: Borislav Petkov Cc: Brian Gerst Cc: Chen Yucong Cc: Chris Metcalf Cc: Dave Hansen Cc: Fenghua Yu Cc: Huang Rui Cc: Jiri Slaby Cc: Jonathan Corbet Cc: Michael S. Tsirkin Cc: Paul Gortmaker Cc: Peter Zijlstra Cc: Ravi V. Shankar Cc: Shuah Khan Cc: Vlastimil Babka Cc: Tony Luck Cc: Paolo Bonzini Cc: Liang Z. Li Cc: Alexandre Julliard Cc: Stas Sergeev Cc: x86@kernel.org Cc: linux-msdos@vger.kernel.org Signed-off-by: Ricardo Neri --- arch/x86/kernel/traps.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c index 948443e..86efbcb 100644 --- a/arch/x86/kernel/traps.c +++ b/arch/x86/kernel/traps.c @@ -65,6 +65,7 @@ #include #include #include +#include #ifdef CONFIG_X86_64 #include @@ -492,6 +493,9 @@ do_general_protection(struct pt_regs *regs, long error_code) RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU"); cond_local_irq_enable(regs); + if (user_mode(regs) && fixup_umip_exception(regs)) + return; + if (v8086_mode(regs)) { local_irq_enable(); handle_vm86_fault((struct kernel_vm86_regs *) regs, error_code); -- 2.9.3