From patchwork Tue Jan 15 17:45:28 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mark Rutland X-Patchwork-Id: 1979821 Return-Path: X-Original-To: patchwork-linux-arm@patchwork.kernel.org Delivered-To: patchwork-process-083081@patchwork2.kernel.org Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) by patchwork2.kernel.org (Postfix) with ESMTP id 74213DF264 for ; Tue, 15 Jan 2013 17:57:06 +0000 (UTC) Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.76 #1 (Red Hat Linux)) id 1TvAgk-0005Qt-Mw; Tue, 15 Jan 2013 17:52:43 +0000 Received: from service87.mimecast.com ([91.220.42.44]) by merlin.infradead.org with esmtp (Exim 4.76 #1 (Red Hat Linux)) id 1TvAei-0004DP-6Q for linux-arm-kernel@lists.infradead.org; Tue, 15 Jan 2013 17:50:37 +0000 Received: from cam-owa1.Emea.Arm.com (fw-tnat.cambridge.arm.com [217.140.96.21]) by service87.mimecast.com; Tue, 15 Jan 2013 17:50:33 +0000 Received: from localhost.localdomain ([10.1.255.212]) by cam-owa1.Emea.Arm.com with Microsoft SMTPSVC(6.0.3790.0); Tue, 15 Jan 2013 17:50:31 +0000 From: Mark Rutland To: linux-arm-kernel@lists.infradead.org Subject: [PATCHv4 11/14] arm64: arm_generic: prevent reading stale time Date: Tue, 15 Jan 2013 17:45:28 +0000 Message-Id: <1358271931-7761-12-git-send-email-mark.rutland@arm.com> X-Mailer: git-send-email 1.7.0.4 In-Reply-To: <1358271931-7761-1-git-send-email-mark.rutland@arm.com> References: <1358271931-7761-1-git-send-email-mark.rutland@arm.com> X-OriginalArrivalTime: 15 Jan 2013 17:50:31.0928 (UTC) FILETIME=[D02AE780:01CDF348] X-MC-Unique: 113011517503304401 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20130115_125037_292023_64EF7841 X-CRM114-Status: UNSURE ( 9.82 ) X-CRM114-Notice: Please train this message. X-Spam-Score: -2.6 (--) X-Spam-Report: SpamAssassin version 3.3.2 on merlin.infradead.org summary: Content analysis details: (-2.6 points) pts rule name description ---- ---------------------- -------------------------------------------------- -0.7 RCVD_IN_DNSWL_LOW RBL: Sender listed at http://www.dnswl.org/, low trust [91.220.42.44 listed in list.dnswl.org] -0.0 SPF_PASS SPF: sender matches SPF record -1.9 BAYES_00 BODY: Bayes spam probability is 0 to 1% [score: 0.0000] Cc: Mark Rutland , c.dall@virtualopensystems.com, Marc.Zyngier@arm.com, catalin.marinas@arm.com, sboyd@codeaurora.org, Will.Deacon@arm.com, santosh.shilimkar@ti.com X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Sender: linux-arm-kernel-bounces@lists.infradead.org Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org Currently arch_counter_get_cnt{p,v}ct can be speculated, allowing for stale time values to be read. This could be problematic for the delay loop and other sensitive functions, as the time delta could jump around unexpectedly. This patch adds isbs to arch_counter_get_cnt{p,v}ct, preventing this possibility. Signed-off-by: Mark Rutland --- arch/arm64/include/asm/arm_generic.h | 2 ++ 1 files changed, 2 insertions(+), 0 deletions(-) diff --git a/arch/arm64/include/asm/arm_generic.h b/arch/arm64/include/asm/arm_generic.h index df2aeb8..6ece2f1 100644 --- a/arch/arm64/include/asm/arm_generic.h +++ b/arch/arm64/include/asm/arm_generic.h @@ -83,6 +83,7 @@ static inline cycle_t arch_counter_get_cntpct(void) { cycle_t cval; + isb(); asm volatile("mrs %0, cntpct_el0" : "=r" (cval)); return cval; @@ -92,6 +93,7 @@ static inline cycle_t arch_counter_get_cntvct(void) { cycle_t cval; + isb(); asm volatile("mrs %0, cntvct_el0" : "=r" (cval)); return cval;