From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 881FFC04EB8 for ; Thu, 6 Dec 2018 22:19:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 56F552082B for ; Thu, 6 Dec 2018 22:19:34 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 56F552082B Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=intel.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726168AbeLFWTd (ORCPT ); Thu, 6 Dec 2018 17:19:33 -0500 Received: from mga06.intel.com ([134.134.136.31]:39981 "EHLO mga06.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725939AbeLFWTb (ORCPT ); Thu, 6 Dec 2018 17:19:31 -0500 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga008.jf.intel.com ([10.7.209.65]) by orsmga104.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 06 Dec 2018 14:19:28 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.56,324,1539673200"; d="scan'208";a="99313298" Received: from sjchrist-coffee.jf.intel.com ([10.54.74.154]) by orsmga008.jf.intel.com with ESMTP; 06 Dec 2018 14:19:28 -0800 From: Sean Christopherson To: Andy Lutomirski , Thomas Gleixner , Ingo Molnar , Borislav Petkov , x86@kernel.org, Dave Hansen , Peter Zijlstra Cc: "H. Peter Anvin" , linux-kernel@vger.kernel.org, Andy Lutomirski , Jarkko Sakkinen , Josh Triplett Subject: [RFC PATCH v2 2/4] x86/fault: Attempt to fixup unhandled #PF in vDSO before signaling Date: Thu, 6 Dec 2018 14:19:20 -0800 Message-Id: <20181206221922.31012-3-sean.j.christopherson@intel.com> X-Mailer: git-send-email 2.19.2 In-Reply-To: <20181206221922.31012-1-sean.j.christopherson@intel.com> References: <20181206221922.31012-1-sean.j.christopherson@intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Call fixup_vdso_exception() in the SIGSEGV and SIGBUS paths of the page fault handler immediately prior to signaling. If the fault is fixed, return cleanly and do not generate a signal. The goal of vDSO fixup is not to fixup all faults, nor is it to avoid all signals, but rather to report faults directly to userspace when the fault would otherwise directly result in a signal being sent to the process. For example, a page fault that points to valid user memory that happened to be swapped out should not trigger fixup, i.e. should not be reported to userspace. In the SIGSEGV flow, make sure to call fixup_vdso_exception() after the error code has been sanitized. Suggested-by: Andy Lutomirski Cc: Andy Lutomirski Cc: Jarkko Sakkinen Cc: Dave Hansen Cc: Josh Triplett Signed-off-by: Sean Christopherson --- arch/x86/mm/fault.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c index 2ff25ad33233..ff1cb10858d5 100644 --- a/arch/x86/mm/fault.c +++ b/arch/x86/mm/fault.c @@ -28,6 +28,7 @@ #include /* vma_pkey() */ #include /* efi_recover_from_page_fault()*/ #include /* store_idt(), ... */ +#include /* fixup_vdso_exception() */ #define CREATE_TRACE_POINTS #include @@ -928,6 +929,9 @@ __bad_area_nosemaphore(struct pt_regs *regs, unsigned long error_code, if (address >= TASK_SIZE_MAX) error_code |= X86_PF_PROT; + if (fixup_vdso_exception(regs, X86_TRAP_PF, error_code, address)) + return; + if (likely(show_unhandled_signals)) show_signal_msg(regs, error_code, address, tsk); @@ -1045,6 +1049,9 @@ do_sigbus(struct pt_regs *regs, unsigned long error_code, unsigned long address, if (is_prefetch(regs, error_code, address)) return; + if (fixup_vdso_exception(regs, X86_TRAP_PF, error_code, address)) + return; + set_signal_archinfo(address, error_code); #ifdef CONFIG_MEMORY_FAILURE -- 2.19.2