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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id A9B0DC4167D for ; Mon, 7 Feb 2022 11:37:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1358132AbiBGL2i (ORCPT ); Mon, 7 Feb 2022 06:28:38 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34574 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1383468AbiBGLWg (ORCPT ); Mon, 7 Feb 2022 06:22:36 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 19ADCC043181; Mon, 7 Feb 2022 03:22:34 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id D7F40B81028; Mon, 7 Feb 2022 11:22:32 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id D0634C004E1; Mon, 7 Feb 2022 11:22:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1644232951; bh=VMbaaDzs3K6lmluIUIPk3ffjNBsj3IfW/jyNMjzDMyo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Ip6G5Kzj7ntDVKr8jrf2RthG9RVfmUGTCAfTsOSfzhyvxuqu2RmxXMm0qE5OSsnVR BPtw5NKnl3L3eFjAzmpB2lwMFmf3UGPR+5et0Bvv2TvfBo2mcca8kFy4SF15mYZRgm XtzX3fQxUdIeDfzwJYNcxVroPQ89FTMFGN4XqEQU= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Yannick Vignon , "Russell King (Oracle)" , Jakub Kicinski Subject: [PATCH 5.10 43/74] net: stmmac: ensure PTP time register reads are consistent Date: Mon, 7 Feb 2022 12:06:41 +0100 Message-Id: <20220207103758.633267782@linuxfoundation.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220207103757.232676988@linuxfoundation.org> References: <20220207103757.232676988@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Yannick Vignon commit 80d4609008e6d696a279e39ae7458c916fcd44c1 upstream. Even if protected from preemption and interrupts, a small time window remains when the 2 register reads could return inconsistent values, each time the "seconds" register changes. This could lead to an about 1-second error in the reported time. Add logic to ensure the "seconds" and "nanoseconds" values are consistent. Fixes: 92ba6888510c ("stmmac: add the support for PTP hw clock driver") Signed-off-by: Yannick Vignon Reviewed-by: Russell King (Oracle) Link: https://lore.kernel.org/r/20220203160025.750632-1-yannick.vignon@oss.nxp.com Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman --- drivers/net/ethernet/stmicro/stmmac/stmmac_hwtstamp.c | 17 +++++++++++------ 1 file changed, 11 insertions(+), 6 deletions(-) --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_hwtstamp.c +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_hwtstamp.c @@ -142,15 +142,20 @@ static int adjust_systime(void __iomem * static void get_systime(void __iomem *ioaddr, u64 *systime) { - u64 ns; + u64 ns, sec0, sec1; - /* Get the TSSS value */ - ns = readl(ioaddr + PTP_STNSR); - /* Get the TSS and convert sec time value to nanosecond */ - ns += readl(ioaddr + PTP_STSR) * 1000000000ULL; + /* Get the TSS value */ + sec1 = readl_relaxed(ioaddr + PTP_STSR); + do { + sec0 = sec1; + /* Get the TSSS value */ + ns = readl_relaxed(ioaddr + PTP_STNSR); + /* Get the TSS value */ + sec1 = readl_relaxed(ioaddr + PTP_STSR); + } while (sec0 != sec1); if (systime) - *systime = ns; + *systime = ns + (sec1 * 1000000000ULL); } const struct stmmac_hwtimestamp stmmac_ptp = {