From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757878Ab2IUTpq (ORCPT ); Fri, 21 Sep 2012 15:45:46 -0400 Received: from mga01.intel.com ([192.55.52.88]:27797 "EHLO mga01.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755411Ab2IUTnU (ORCPT ); Fri, 21 Sep 2012 15:43:20 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.80,464,1344236400"; d="scan'208";a="225202020" From: "H. Peter Anvin" To: Linux Kernel Mailing List , "H. Peter Anvin" , Ingo Molnar , Thomas Gleixner Cc: Linus Torvalds , Kees Cook , Linda Wang , Matt Fleming , "H. Peter Anvin" Subject: [PATCH 10/11] x86, smap: A page fault due to SMAP is an oops Date: Fri, 21 Sep 2012 12:43:14 -0700 Message-Id: <1348256595-29119-11-git-send-email-hpa@linux.intel.com> X-Mailer: git-send-email 1.7.6.5 In-Reply-To: <1348256595-29119-1-git-send-email-hpa@linux.intel.com> References: <1348256595-29119-1-git-send-email-hpa@linux.intel.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: "H. Peter Anvin" If we get a page fault due to SMAP, trigger an oops rather than spinning forever. Signed-off-by: H. Peter Anvin --- arch/x86/mm/fault.c | 18 ++++++++++++++++++ 1 files changed, 18 insertions(+), 0 deletions(-) diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c index 76dcd9d..f2fb75d 100644 --- a/arch/x86/mm/fault.c +++ b/arch/x86/mm/fault.c @@ -995,6 +995,17 @@ static int fault_in_kernel_space(unsigned long address) return address >= TASK_SIZE_MAX; } +static inline bool smap_violation(int error_code, struct pt_regs *regs) +{ + if (error_code & PF_USER) + return false; + + if (!user_mode_vm(regs) && (regs->flags & X86_EFLAGS_AC)) + return false; + + return true; +} + /* * This routine handles page faults. It determines the address, * and the problem, and then passes it off to one of the appropriate @@ -1088,6 +1099,13 @@ do_page_fault(struct pt_regs *regs, unsigned long error_code) if (unlikely(error_code & PF_RSVD)) pgtable_bad(regs, error_code, address); + if (static_cpu_has(X86_FEATURE_SMAP)) { + if (unlikely(smap_violation(error_code, regs))) { + bad_area_nosemaphore(regs, error_code, address); + return; + } + } + perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address); /* -- 1.7.6.5