From nobody Fri Sep 20 13:28:24 2024 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 80585C001B0 for ; Mon, 17 Jul 2023 09:09:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230147AbjGQJJE (ORCPT ); Mon, 17 Jul 2023 05:09:04 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59518 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229539AbjGQJJC (ORCPT ); Mon, 17 Jul 2023 05:09:02 -0400 Received: from mailgw02.mediatek.com (unknown [210.61.82.184]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5E87BE55; Mon, 17 Jul 2023 02:08:59 -0700 (PDT) X-UUID: 8c62ae36248111eeb20a276fd37b9834-20230717 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=mediatek.com; s=dk; h=Content-Type:MIME-Version:Message-ID:Date:Subject:CC:To:From; bh=Y8JNYfBYjIbnwh4BqD1zU+2zkjayx73cT2gySc48Rp0=; b=C6Lmqx2Ebz3E6OLm0d82Ea0sCKeD77YG90SCaChLf69dmilXMlpleVvNl3WzhwgMb4mh+EKIx5Wiq7khNqWYysTMaovtS1GCWu9mxqT/A+IyPNAL/7AAj0ig8cUZD88BkB2g+uD/Jbw2V/k7Hp1rk5XginR4mMsX+aRyBRS8MRQ=; X-CID-P-RULE: Release_Ham X-CID-O-INFO: VERSION:1.1.28,REQID:bdf29437-4978-4b75-8c87-58bba670043e,IP:0,U RL:0,TC:0,Content:0,EDM:0,RT:0,SF:100,FILE:0,BULK:0,RULE:Release_Ham,ACTIO N:release,TS:100 X-CID-INFO: VERSION:1.1.28,REQID:bdf29437-4978-4b75-8c87-58bba670043e,IP:0,URL :0,TC:0,Content:0,EDM:0,RT:0,SF:100,FILE:0,BULK:0,RULE:Spam_GS981B3D,ACTIO N:quarantine,TS:100 X-CID-META: VersionHash:176cd25,CLOUDID:36b1aedc-dc79-4898-9235-1134b97257a8,B ulkID:230717170853FD2V3QFP,BulkQuantity:0,Recheck:0,SF:28|17|19|48|38|29,T C:nil,Content:0,EDM:-3,IP:nil,URL:0,File:nil,Bulk:nil,QS:nil,BEC:nil,COL:0 ,OSI:0,OSA:0,AV:0,LES:1,SPR:NO,DKR:0,DKP:0 X-CID-BVR: 0 X-CID-BAS: 0,_,0,_ X-CID-FACTOR: TF_CID_SPAM_SNR,TF_CID_SPAM_SDM,TF_CID_SPAM_ASC,TF_CID_SPAM_FAS, TF_CID_SPAM_FSD X-UUID: 8c62ae36248111eeb20a276fd37b9834-20230717 Received: from mtkmbs10n1.mediatek.inc [(172.21.101.34)] by mailgw02.mediatek.com (envelope-from ) (Generic MTA with TLSv1.2 ECDHE-RSA-AES256-GCM-SHA384 256/256) with ESMTP id 445378854; Mon, 17 Jul 2023 17:08:51 +0800 Received: from mtkmbs11n2.mediatek.inc (172.21.101.187) by mtkmbs10n2.mediatek.inc (172.21.101.183) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1118.26; Mon, 17 Jul 2023 17:08:50 +0800 Received: from mtksdccf07.mediatek.inc (172.21.84.99) by mtkmbs11n2.mediatek.inc (172.21.101.73) with Microsoft SMTP Server id 15.2.1118.26 via Frontend Transport; Mon, 17 Jul 2023 17:08:50 +0800 From: To: Mark Rutland , Marc Zyngier , "Daniel Lezcano" , Thomas Gleixner , Matthias Brugger , AngeloGioacchino Del Regno CC: , , , , , , , , Subject: [PATCH] clocksource/drivers/arm_arch_timer: Disable timer before programming CVAL Date: Mon, 17 Jul 2023 17:07:34 +0800 Message-ID: <20230717090735.19370-1-walter.chang@mediatek.com> X-Mailer: git-send-email 2.18.0 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: Walter Chang Due to the fact that the use of `writeq_relaxed()` to program CVAL is not guaranteed to be atomic, it is necessary to disable the timer before programming CVAL. However, if the MMIO timer is already enabled and has not yet expired, there is a possibility of unexpected behavior occurring: when the CPU enters the idle state during this period, and if the CPU's local event is earlier than the broadcast event, the following process occurs: tick_broadcast_enter() tick_broadcast_oneshot_control(TICK_BROADCAST_ENTER) __tick_broadcast_oneshot_control() ___tick_broadcast_oneshot_control() tick_broadcast_set_event() clockevents_program_event() set_next_event_mem() During this process, the MMIO timer remains enabled while programming CVAL. To prevent such behavior, disable timer explicitly prior to programming CVAL. Fixes: 8b82c4f883a7 ("clocksource/drivers/arm_arch_timer: Move MMIO timer p= rogramming over to CVAL") Cc: stable@vger.kernel.org Signed-off-by: Walter Chang Acked-by: Marc Zyngier Reviewed-by: AngeloGioacchino Del Regno --- drivers/clocksource/arm_arch_timer.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm= _arch_timer.c index e733a2a1927a..7dd2c615bce2 100644 --- a/drivers/clocksource/arm_arch_timer.c +++ b/drivers/clocksource/arm_arch_timer.c @@ -792,6 +792,13 @@ static __always_inline void set_next_event_mem(const i= nt access, unsigned long e u64 cnt; =20 ctrl =3D arch_timer_reg_read(access, ARCH_TIMER_REG_CTRL, clk); + + /* Timer must be disabled before programming CVAL */ + if (ctrl & ARCH_TIMER_CTRL_ENABLE) { + ctrl &=3D ~ARCH_TIMER_CTRL_ENABLE; + arch_timer_reg_write(access, ARCH_TIMER_REG_CTRL, ctrl, clk); + } + ctrl |=3D ARCH_TIMER_CTRL_ENABLE; ctrl &=3D ~ARCH_TIMER_CTRL_IT_MASK; =20 --=20 2.18.0