From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752220AbaBMPyy (ORCPT ); Thu, 13 Feb 2014 10:54:54 -0500 Received: from terminus.zytor.com ([198.137.202.10]:40298 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752014AbaBMPyt (ORCPT ); Thu, 13 Feb 2014 10:54:49 -0500 Date: Thu, 13 Feb 2014 07:54:39 -0800 From: "tip-bot for H. Peter Anvin" Message-ID: Cc: linux-kernel@vger.kernel.org, hpa@zytor.com, mingo@kernel.org, tglx@linutronix.de, fengguang.wu@intel.com, hpa@linux.intel.com Reply-To: mingo@kernel.org, hpa@zytor.com, linux-kernel@vger.kernel.org, tglx@linutronix.de, hpa@linux.intel.com, fengguang.wu@intel.com In-Reply-To: <20140213124550.GA30497@localhost> References: <20140213124550.GA30497@localhost> To: linux-tip-commits@vger.kernel.org Subject: [tip:x86/urgent] x86, smap: smap_violation() is bogus if CONFIG_X86_SMAP is off Git-Commit-ID: f27d7759ad1ff48673831e598d6df4c76b2bcd06 X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.1 (terminus.zytor.com [127.0.0.1]); Thu, 13 Feb 2014 07:54:45 -0800 (PST) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: f27d7759ad1ff48673831e598d6df4c76b2bcd06 Gitweb: http://git.kernel.org/tip/f27d7759ad1ff48673831e598d6df4c76b2bcd06 Author: H. Peter Anvin AuthorDate: Thu, 13 Feb 2014 07:46:04 -0800 Committer: H. Peter Anvin CommitDate: Thu, 13 Feb 2014 07:50:45 -0800 x86, smap: smap_violation() is bogus if CONFIG_X86_SMAP is off If CONFIG_X86_SMAP is disabled, smap_violation() tests for conditions which are incorrect (as the AC flag doesn't matter), causing spurious faults. The dynamic disabling of SMAP (nosmap on the command line) is fine because it disables X86_FEATURE_SMAP, therefore causing the static_cpu_has() to return false. Found by Fengguang Wu's test system. Reported-by: Fengguang Wu Link: http://lkml.kernel.org/r/20140213124550.GA30497@localhost Signed-off-by: H. Peter Anvin Cc: # v3.7+ --- arch/x86/mm/fault.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c index 9d591c8..4b39bb7 100644 --- a/arch/x86/mm/fault.c +++ b/arch/x86/mm/fault.c @@ -1087,12 +1087,14 @@ __do_page_fault(struct pt_regs *regs, unsigned long error_code) if (unlikely(error_code & PF_RSVD)) pgtable_bad(regs, error_code, address); +#ifdef CONFIG_X86_SMAP if (static_cpu_has(X86_FEATURE_SMAP)) { if (unlikely(smap_violation(error_code, regs))) { bad_area_nosemaphore(regs, error_code, address); return; } } +#endif /* * If we're in an interrupt, have no user context or are running