From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751624AbdFINDH (ORCPT ); Fri, 9 Jun 2017 09:03:07 -0400 Received: from mx2.suse.de ([195.135.220.15]:48227 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751578AbdFINDG (ORCPT ); Fri, 9 Jun 2017 09:03:06 -0400 Date: Fri, 9 Jun 2017 15:02:48 +0200 From: Borislav Petkov To: Ricardo Neri Cc: Ingo Molnar , Thomas Gleixner , "H. Peter Anvin" , Andy Lutomirski , Peter Zijlstra , Andrew Morton , Brian Gerst , Chris Metcalf , Dave Hansen , Paolo Bonzini , 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, Tony Luck Subject: Re: [PATCH v7 23/26] x86/traps: Fixup general protection faults caused by UMIP Message-ID: <20170609130248.h63fmhzpyn7xkeke@pd.tnic> References: <20170505181724.55000-1-ricardo.neri-calderon@linux.intel.com> <20170505181724.55000-24-ricardo.neri-calderon@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20170505181724.55000-24-ricardo.neri-calderon@linux.intel.com> User-Agent: NeoMutt/20170113 (1.7.2) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, May 05, 2017 at 11:17:21AM -0700, Ricardo Neri wrote: > 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 Please end function names with parentheses. > 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 > Reviewed-by: Andy Lutomirski > 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 3995d3a..cec548d 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 +527,9 @@ 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); > Almost definitely: if (static_cpu_has(X86_FEATURE_UMIP)) { if (... > + if (user_mode(regs) && fixup_umip_exception(regs)) > + return; We don't want to punish !UMIP machines. -- Regards/Gruss, Boris. SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nürnberg) --