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 73EF9C5CFC0 for ; Mon, 18 Jun 2018 08:19:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2D9D320864 for ; Mon, 18 Jun 2018 08:19:42 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2D9D320864 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linuxfoundation.org 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 S935543AbeFRITk (ORCPT ); Mon, 18 Jun 2018 04:19:40 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:54916 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S935523AbeFRITi (ORCPT ); Mon, 18 Jun 2018 04:19:38 -0400 Received: from localhost (LFbn-1-12247-202.w90-92.abo.wanadoo.fr [90.92.61.202]) by mail.linuxfoundation.org (Postfix) with ESMTPSA id 530BBBAD; Mon, 18 Jun 2018 08:19:37 +0000 (UTC) From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Mark Rutland , Andrey Konovalov , Catalin Marinas , Will Deacon , Sasha Levin Subject: [PATCH 4.16 094/279] arm64: only advance singlestep for user instruction traps Date: Mon, 18 Jun 2018 10:11:19 +0200 Message-Id: <20180618080612.690971406@linuxfoundation.org> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20180618080608.851973560@linuxfoundation.org> References: <20180618080608.851973560@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 4.16-stable review patch. If anyone has any objections, please let me know. ------------------ From: Mark Rutland [ Upstream commit 9478f1927e6ef9ef5e1ad761af1c98aa8e40b7f5 ] Our arm64_skip_faulting_instruction() helper advances the userspace singlestep state machine, but this is also called by the kernel BRK handler, as used for WARN*(). Thus, if we happen to hit a WARN*() while the user singlestep state machine is in the active-no-pending state, we'll advance to the active-pending state without having executed a user instruction, and will take a step exception earlier than expected when we return to userspace. Let's fix this by only advancing the state machine when skipping a user instruction. Signed-off-by: Mark Rutland Cc: Andrey Konovalov Cc: Catalin Marinas Cc: Will Deacon Signed-off-by: Will Deacon Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- arch/arm64/kernel/traps.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) --- a/arch/arm64/kernel/traps.c +++ b/arch/arm64/kernel/traps.c @@ -243,7 +243,8 @@ void arm64_skip_faulting_instruction(str * If we were single stepping, we want to get the step exception after * we return from the trap. */ - user_fastforward_single_step(current); + if (user_mode(regs)) + user_fastforward_single_step(current); } static LIST_HEAD(undef_hook);