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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED 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 0863FC433F5 for ; Mon, 3 Sep 2018 13:16:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A886F20652 for ; Mon, 3 Sep 2018 13:16:34 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A886F20652 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=zytor.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 S1726314AbeICRgj (ORCPT ); Mon, 3 Sep 2018 13:36:39 -0400 Received: from terminus.zytor.com ([198.137.202.136]:35761 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725969AbeICRgi (ORCPT ); Mon, 3 Sep 2018 13:36:38 -0400 Received: from terminus.zytor.com (localhost [127.0.0.1]) by terminus.zytor.com (8.15.2/8.15.2) with ESMTPS id w83DFuXk3313529 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NO); Mon, 3 Sep 2018 06:15:56 -0700 Received: (from tipbot@localhost) by terminus.zytor.com (8.15.2/8.15.2/Submit) id w83DFtGR3313526; Mon, 3 Sep 2018 06:15:55 -0700 Date: Mon, 3 Sep 2018 06:15:55 -0700 X-Authentication-Warning: terminus.zytor.com: tipbot set sender to tipbot@zytor.com using -f From: tip-bot for Jann Horn Message-ID: Cc: jannh@google.com, anil.s.keshavamurthy@intel.com, hpa@zytor.com, mingo@kernel.org, bp@alien8.de, viro@zeniv.linux.org.uk, linux-kernel@vger.kernel.org, mhiramat@kernel.org, tglx@linutronix.de, keescook@chromium.org, naveen.n.rao@linux.vnet.ibm.com, davem@davemloft.net, luto@kernel.org Reply-To: davem@davemloft.net, luto@kernel.org, naveen.n.rao@linux.vnet.ibm.com, keescook@chromium.org, tglx@linutronix.de, mhiramat@kernel.org, linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk, bp@alien8.de, mingo@kernel.org, hpa@zytor.com, jannh@google.com, anil.s.keshavamurthy@intel.com In-Reply-To: <20180828201421.157735-2-jannh@google.com> References: <20180828201421.157735-2-jannh@google.com> To: linux-tip-commits@vger.kernel.org Subject: [tip:x86/core] x86/kprobes: Refactor kprobes_fault() like kprobe_exceptions_notify() Git-Commit-ID: a980c0ef9f6d8c45445d6ed0f5836bb6941c8c91 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 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: a980c0ef9f6d8c45445d6ed0f5836bb6941c8c91 Gitweb: https://git.kernel.org/tip/a980c0ef9f6d8c45445d6ed0f5836bb6941c8c91 Author: Jann Horn AuthorDate: Tue, 28 Aug 2018 22:14:15 +0200 Committer: Thomas Gleixner CommitDate: Mon, 3 Sep 2018 15:12:08 +0200 x86/kprobes: Refactor kprobes_fault() like kprobe_exceptions_notify() This is an extension of commit b506a9d08bae ("x86: code clarification patch to Kprobes arch code"). As that commit explains, even though kprobe_running() can't be called with preemption enabled, preemption does not need to be disabled. If preemption is enabled, then this can't be originate from a kprobe. Also, use X86_TRAP_PF instead of 14. Signed-off-by: Jann Horn Signed-off-by: Thomas Gleixner Tested-by: Kees Cook Acked-by: Masami Hiramatsu Cc: Andy Lutomirski Cc: kernel-hardening@lists.openwall.com Cc: dvyukov@google.com Cc: "Naveen N. Rao" Cc: Anil S Keshavamurthy Cc: "David S. Miller" Cc: Alexander Viro Cc: linux-fsdevel@vger.kernel.org Cc: Borislav Petkov Link: https://lkml.kernel.org/r/20180828201421.157735-2-jannh@google.com --- arch/x86/mm/fault.c | 24 +++++++++++++----------- 1 file changed, 13 insertions(+), 11 deletions(-) diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c index 47bebfe6efa7..d99edb2d567b 100644 --- a/arch/x86/mm/fault.c +++ b/arch/x86/mm/fault.c @@ -44,17 +44,19 @@ kmmio_fault(struct pt_regs *regs, unsigned long addr) static nokprobe_inline int kprobes_fault(struct pt_regs *regs) { - int ret = 0; - - /* kprobe_running() needs smp_processor_id() */ - if (kprobes_built_in() && !user_mode(regs)) { - preempt_disable(); - if (kprobe_running() && kprobe_fault_handler(regs, 14)) - ret = 1; - preempt_enable(); - } - - return ret; + if (!kprobes_built_in()) + return 0; + if (user_mode(regs)) + return 0; + /* + * To be potentially processing a kprobe fault and to be allowed to call + * kprobe_running(), we have to be non-preemptible. + */ + if (preemptible()) + return 0; + if (!kprobe_running()) + return 0; + return kprobe_fault_handler(regs, X86_TRAP_PF); } /*