Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752670AbdHSAam (ORCPT ); Fri, 18 Aug 2017 20:30:42 -0400 Received: from mga07.intel.com ([134.134.136.100]:14783 "EHLO mga07.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752314AbdHSA2y (ORCPT ); Fri, 18 Aug 2017 20:28:54 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.41,394,1498546800"; d="scan'208";a="1164119742" 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 , "Ravi V. Shankar" , Shuah Khan , linux-kernel@vger.kernel.org, x86@kernel.org, ricardo.neri@intel.com, Ricardo Neri , Fenghua Yu , Tony Luck Subject: [PATCH v8 26/28] x86/traps: Fixup general protection faults caused by UMIP Date: Fri, 18 Aug 2017 17:28:07 -0700 Message-Id: <20170819002809.111312-27-ricardo.neri-calderon@linux.intel.com> X-Mailer: git-send-email 2.13.0 In-Reply-To: <20170819002809.111312-1-ricardo.neri-calderon@linux.intel.com> References: <20170819002809.111312-1-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: 2521 Lines: 68 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 as follows: if running a 32-bit process, sgdt, sidt and smsw are emulated; str and sldt are not emulated. No emulation is done for 64-bit processes. 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: x86@kernel.org Reviewed-by: Andy Lutomirski Signed-off-by: Ricardo Neri --- arch/x86/kernel/traps.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c index bf54309b85da..1c1bb7992f70 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 @@ -526,6 +527,10 @@ 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 (static_cpu_has(X86_FEATURE_UMIP)) + 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); -- 2.13.0