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=-1.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,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 6AA25C282C2 for ; Wed, 13 Feb 2019 19:35:47 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 3FCC02146E for ; Wed, 13 Feb 2019 19:35:47 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="hMr9Cg9I" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 3FCC02146E Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linutronix.de Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:Message-ID: In-Reply-To:Subject:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=3c9YmKnMUiPztk21OXDwaRjo3Z9C9fmNDD2pTeHC+V8=; b=hMr9Cg9Ii0nnOk 6E71ADbwJKCeWKepSpElvwpkyAIFhLFyf3cWU4cp0EVZO/jJYXX7sw6oeqe2vWFcTyNg//4uzyfnU rF53wBug1RQ3qp+cLygiav+cotX9aO6JI851bqVUE9FZmHrnVBc+nEeSvT9V+3AEeI7RByR6tMf1i hnTCZ1Dj1EAeD+Nz6WC/SqWaGf+cMlWvbfiZk33lp52zOmZMxAxvSZeQorXcVG5s5+E/FPK/ixKp1 UkDJ5k7hyibiwEyv+PaBeU2hlM7pYv+8afz9rgie8Lc3qrK8cpBSH84KWH/KVmEV8+AgtSNX8eEMV jQiAUrvqmlpHcaHggHMA==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1gu0Js-0003BA-Ba; Wed, 13 Feb 2019 19:35:44 +0000 Received: from galois.linutronix.de ([2a01:7a0:2:106d:700::1]) by bombadil.infradead.org with esmtps (Exim 4.90_1 #2 (Red Hat Linux)) id 1gu0Jo-00039y-Kn for linux-arm-kernel@lists.infradead.org; Wed, 13 Feb 2019 19:35:42 +0000 Received: from p5492e0d8.dip0.t-ipconnect.de ([84.146.224.216] helo=nanos) by Galois.linutronix.de with esmtpsa (TLS1.2:DHE_RSA_AES_256_CBC_SHA256:256) (Exim 4.80) (envelope-from ) id 1gu0Jh-0004KL-ES; Wed, 13 Feb 2019 20:35:33 +0100 Date: Wed, 13 Feb 2019 20:35:32 +0100 (CET) From: Thomas Gleixner To: Will Deacon Subject: Re: [PATCH v2 06/28] kernel: Define gettimeofday vdso common code In-Reply-To: <20190213170413.GE6346@brain-police> Message-ID: References: <20181129170530.37789-1-vincenzo.frascino@arm.com> <20181129170530.37789-7-vincenzo.frascino@arm.com> <20181207175321.GA11430@edgewater-inn.cambridge.arm.com> <20190208173539.GD24375@fuggles.cambridge.arm.com> <20190213170413.GE6346@brain-police> User-Agent: Alpine 2.21 (DEB 202 2017-01-01) MIME-Version: 1.0 X-Linutronix-Spam-Score: -1.0 X-Linutronix-Spam-Level: - X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required, ALL_TRUSTED=-1, SHORTCIRCUIT=-0.0001 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190213_113540_826754_B63A506F X-CRM114-Status: GOOD ( 14.43 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-arch@vger.kernel.org, Arnd Bergmann , marc.zyngier@arm.com, Catalin Marinas , Daniel Lezcano , Russell King , Ralf Baechle , Mark Salyzyn , Paul Burton , Vincenzo Frascino , Peter Collingbourne , linux-arm-kernel@lists.infradead.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Wed, 13 Feb 2019, Will Deacon wrote: > On Fri, Feb 08, 2019 at 08:30:25PM +0100, Thomas Gleixner wrote: > > > > How is the in kernel ktime_get() correctness guaranteed then? > > Luck. > > I think we'll have to introduce a dummy dependent stack read into our > counter accessor so that it's ordered by the smp_rmb(). Example diff > below, which I'll roll into a proper patch series later on. Yikes. > static inline u64 arch_counter_get_cntpct(void) > { > + u64 cnt, tmp; > + > isb(); > - return arch_timer_reg_read_stable(cntpct_el0); > + cnt = arch_timer_reg_read_stable(cntpct_el0); > + > + /* > + * This insanity brought to you by speculative, out-of-order system > + * register reads, sequence locks and Thomas Gleixner. ROTFL _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel