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=-6.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT 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 09880C3F2C6 for ; Tue, 3 Mar 2020 18:10:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D85372073B for ; Tue, 3 Mar 2020 18:10:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1583259030; bh=mwvdgSaAumLLSTH4CcBe04nOPmVj/nufXabgBS1mi6k=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=zRd0R4LDvtExecXHDlMPwutjVYRWizFp5stzXYrG2qoH9s1j6FU92o31YnB0PhEql rZDTYfctRVB/qnLnQT8s09orf6oru+iwVvoVe3JFq7w+F7ocVaOEZdjhsvp55WwW0O ybQBUR/qQNOnJGcoW9M353j3fn9SieVs2IzIHWjg= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731601AbgCCRuv (ORCPT ); Tue, 3 Mar 2020 12:50:51 -0500 Received: from mail.kernel.org ([198.145.29.99]:58526 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731565AbgCCRup (ORCPT ); Tue, 3 Mar 2020 12:50:45 -0500 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id D9BD2214D8; Tue, 3 Mar 2020 17:50:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1583257844; bh=mwvdgSaAumLLSTH4CcBe04nOPmVj/nufXabgBS1mi6k=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=t/7tfABG36EJEapjjFk9+LG7qwkVdaBm7ZvgnHCtE1WwS6PYpmojXCOicPhW2lP+X B+Gg+0VuBRbFPcd6J6KmxQLWsZ5kyXPi49Mxpkk4JMek5/5FfnZtA5iWKxUdakaP1n r3O/cwLgNSDWGc8nPBkNqN33RkTFdh+v22ZPBsBo= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Thomas Gleixner Subject: [PATCH 5.5 151/176] lib/vdso: Update coarse timekeeper unconditionally Date: Tue, 3 Mar 2020 18:43:35 +0100 Message-Id: <20200303174322.100950388@linuxfoundation.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20200303174304.593872177@linuxfoundation.org> References: <20200303174304.593872177@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Thomas Gleixner commit 9f24c540f7f8eb3a981528da9a9a636a5bdf5987 upstream. The low resolution parts of the VDSO, i.e.: clock_gettime(CLOCK_*_COARSE), clock_getres(), time() can be used even if there is no VDSO capable clocksource. But if an architecture opts out of the VDSO data update then this information becomes stale. This affects ARM when there is no architected timer available. The lack of update causes userspace to use stale data forever. Make the update of the low resolution parts unconditional and only skip the update of the high resolution parts if the architecture requests it. Fixes: 44f57d788e7d ("timekeeping: Provide a generic update_vsyscall() implementation") Signed-off-by: Thomas Gleixner Link: https://lore.kernel.org/r/20200114185946.765577901@linutronix.de Signed-off-by: Greg Kroah-Hartman --- kernel/time/vsyscall.c | 37 +++++++++++++++++-------------------- 1 file changed, 17 insertions(+), 20 deletions(-) --- a/kernel/time/vsyscall.c +++ b/kernel/time/vsyscall.c @@ -28,11 +28,6 @@ static inline void update_vdso_data(stru vdata[CS_RAW].mult = tk->tkr_raw.mult; vdata[CS_RAW].shift = tk->tkr_raw.shift; - /* CLOCK_REALTIME */ - vdso_ts = &vdata[CS_HRES_COARSE].basetime[CLOCK_REALTIME]; - vdso_ts->sec = tk->xtime_sec; - vdso_ts->nsec = tk->tkr_mono.xtime_nsec; - /* CLOCK_MONOTONIC */ vdso_ts = &vdata[CS_HRES_COARSE].basetime[CLOCK_MONOTONIC]; vdso_ts->sec = tk->xtime_sec + tk->wall_to_monotonic.tv_sec; @@ -70,12 +65,6 @@ static inline void update_vdso_data(stru vdso_ts = &vdata[CS_HRES_COARSE].basetime[CLOCK_TAI]; vdso_ts->sec = tk->xtime_sec + (s64)tk->tai_offset; vdso_ts->nsec = tk->tkr_mono.xtime_nsec; - - /* - * Read without the seqlock held by clock_getres(). - * Note: No need to have a second copy. - */ - WRITE_ONCE(vdata[CS_HRES_COARSE].hrtimer_res, hrtimer_resolution); } void update_vsyscall(struct timekeeper *tk) @@ -84,20 +73,17 @@ void update_vsyscall(struct timekeeper * struct vdso_timestamp *vdso_ts; u64 nsec; - if (!__arch_update_vdso_data()) { - /* - * Some architectures might want to skip the update of the - * data page. - */ - return; - } - /* copy vsyscall data */ vdso_write_begin(vdata); vdata[CS_HRES_COARSE].clock_mode = __arch_get_clock_mode(tk); vdata[CS_RAW].clock_mode = __arch_get_clock_mode(tk); + /* CLOCK_REALTIME also required for time() */ + vdso_ts = &vdata[CS_HRES_COARSE].basetime[CLOCK_REALTIME]; + vdso_ts->sec = tk->xtime_sec; + vdso_ts->nsec = tk->tkr_mono.xtime_nsec; + /* CLOCK_REALTIME_COARSE */ vdso_ts = &vdata[CS_HRES_COARSE].basetime[CLOCK_REALTIME_COARSE]; vdso_ts->sec = tk->xtime_sec; @@ -110,7 +96,18 @@ void update_vsyscall(struct timekeeper * nsec = nsec + tk->wall_to_monotonic.tv_nsec; vdso_ts->sec += __iter_div_u64_rem(nsec, NSEC_PER_SEC, &vdso_ts->nsec); - update_vdso_data(vdata, tk); + /* + * Read without the seqlock held by clock_getres(). + * Note: No need to have a second copy. + */ + WRITE_ONCE(vdata[CS_HRES_COARSE].hrtimer_res, hrtimer_resolution); + + /* + * Architectures can opt out of updating the high resolution part + * of the VDSO. + */ + if (__arch_update_vdso_data()) + update_vdso_data(vdata, tk); __arch_update_vsyscall(vdata, tk);