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=-13.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 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 1C9FBC3A59E for ; Mon, 2 Sep 2019 14:27:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id F0D1721670 for ; Mon, 2 Sep 2019 14:27:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731379AbfIBO1q (ORCPT ); Mon, 2 Sep 2019 10:27:46 -0400 Received: from foss.arm.com ([217.140.110.172]:55702 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731482AbfIBO1q (ORCPT ); Mon, 2 Sep 2019 10:27:46 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id C67A4344; Mon, 2 Sep 2019 07:27:45 -0700 (PDT) Received: from lakrids.cambridge.arm.com (usa-sjc-imap-foss1.foss.arm.com [10.121.207.14]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 724073F59C; Mon, 2 Sep 2019 07:27:44 -0700 (PDT) Date: Mon, 2 Sep 2019 15:27:42 +0100 From: Mark Rutland To: Viresh Kumar Cc: stable@vger.kernel.org, Julien Thierry , linux-arm-kernel@lists.infradead.org, Catalin Marinas , Marc Zyngier , Will Deacon , Russell King , Vincent Guittot , mark.brown@arm.com Subject: Re: [PATCH ARM64 v4.4 V3 12/44] arm64: cpufeature: Test 'matches' pointer to find the end of the list Message-ID: <20190902142741.GB9922@lakrids.cambridge.arm.com> References: <617ad445043f040c5ab986b9620b2ba7847b561e.1567077734.git.viresh.kumar@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <617ad445043f040c5ab986b9620b2ba7847b561e.1567077734.git.viresh.kumar@linaro.org> User-Agent: Mutt/1.11.1+11 (2f07cb52) (2018-12-01) Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org On Thu, Aug 29, 2019 at 05:03:57PM +0530, Viresh Kumar wrote: > From: James Morse > > commit 644c2ae198412c956700e55a2acf80b2541f6aa5 upstream. > > CPU feature code uses the desc field as a test to find the end of the list, > this means every entry must have a description. This generates noise for > entries in the list that aren't really features, but combinations of them. > e.g. > > CPU features: detected feature: Privileged Access Never > > CPU features: detected feature: PAN and not UAO > > These combination features are needed for corner cases with alternatives, > where cpu features interact. > > Change all walkers of the arm64_features[] and arm64_hwcaps[] lists to test > 'matches' not 'desc', and only print 'desc' if it is non-NULL. > > Signed-off-by: James Morse > Reviewed-by : Suzuki K Poulose > Signed-off-by: Catalin Marinas > Signed-off-by: Viresh Kumar > --- > arch/arm64/kernel/cpufeature.c | 12 ++++++------ > 1 file changed, 6 insertions(+), 6 deletions(-) >From looking at my 4.9.y/{meltdown,spectre} banches on kernel.org [1,2], and chasing the history v4.4..v4.9, there are a number of patches I'd expect to have alongside this that I don't spot in this series: * e3661b128e53ee281e1e7c589a5b647890bd6d7c ("arm64: Allow a capability to be checked on a single CPU") * 8f4137588261d7504f4aa022dc9d1a1fd1940e8e ("arm64: Allow checking of a CPU-local erratum") * 67948af41f2e6818edeeba5182811c704d484949 ("arm64: capabilities: Handle duplicate entries for a capability") * edf298cfce47ab7279d03b5203ae2ef3a58e49db ("arm64: cpufeature: __this_cpu_has_cap() shouldn't stop early") ... which IIUC are necessary for big.LITTLE to work correctly. Have you verified this for big.LITTLE? Thanks, Mark. [1] https://git.kernel.org/pub/scm/linux/kernel/git/mark/linux.git/log/?h=stable/4.9.y/meltdown [2] https://git.kernel.org/pub/scm/linux/kernel/git/mark/linux.git/log/?h=stable/4.9.y/spectre > > diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c > index c1eddc07d996..bdb4cd9ffccf 100644 > --- a/arch/arm64/kernel/cpufeature.c > +++ b/arch/arm64/kernel/cpufeature.c > @@ -744,7 +744,7 @@ static void setup_cpu_hwcaps(void) > int i; > const struct arm64_cpu_capabilities *hwcaps = arm64_hwcaps; > > - for (i = 0; hwcaps[i].desc; i++) > + for (i = 0; hwcaps[i].matches; i++) > if (hwcaps[i].matches(&hwcaps[i])) > cap_set_hwcap(&hwcaps[i]); > } > @@ -754,11 +754,11 @@ void update_cpu_capabilities(const struct arm64_cpu_capabilities *caps, > { > int i; > > - for (i = 0; caps[i].desc; i++) { > + for (i = 0; caps[i].matches; i++) { > if (!caps[i].matches(&caps[i])) > continue; > > - if (!cpus_have_cap(caps[i].capability)) > + if (!cpus_have_cap(caps[i].capability) && caps[i].desc) > pr_info("%s %s\n", info, caps[i].desc); > cpus_set_cap(caps[i].capability); > } > @@ -772,7 +772,7 @@ static void enable_cpu_capabilities(const struct arm64_cpu_capabilities *caps) > { > int i; > > - for (i = 0; caps[i].desc; i++) > + for (i = 0; caps[i].matches; i++) > if (caps[i].enable && cpus_have_cap(caps[i].capability)) > /* > * Use stop_machine() as it schedules the work allowing > @@ -884,7 +884,7 @@ void verify_local_cpu_capabilities(void) > return; > > caps = arm64_features; > - for (i = 0; caps[i].desc; i++) { > + for (i = 0; caps[i].matches; i++) { > if (!cpus_have_cap(caps[i].capability) || !caps[i].sys_reg) > continue; > /* > @@ -897,7 +897,7 @@ void verify_local_cpu_capabilities(void) > caps[i].enable(NULL); > } > > - for (i = 0, caps = arm64_hwcaps; caps[i].desc; i++) { > + for (i = 0, caps = arm64_hwcaps; caps[i].matches; i++) { > if (!cpus_have_hwcap(&caps[i])) > continue; > if (!feature_matches(__raw_read_system_reg(caps[i].sys_reg), &caps[i])) > -- > 2.21.0.rc0.269.g1a574e7a288b >