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=-9.9 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, NICE_REPLY_A,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 autolearn=unavailable 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 6EF65C43461 for ; Tue, 8 Sep 2020 05:15:50 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (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 01935208C7 for ; Tue, 8 Sep 2020 05:15:49 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="vuil00LB" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 01935208C7 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+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=merlin.20170209; h=Sender:Content-Transfer-Encoding: Content-Type:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:Date:Message-ID:From: References:To:Subject:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=z0YAHajB2X/5Mjaku1VQhYrPgLGhPi1+RClwGkCiK84=; b=vuil00LBdH+h4VV3nxgXBPcQF +zJyoyxk+UsR1DMENwVOll3dNhvmWSEqawDSxwL64PIFzVyeLv40xTXqJsuAfu2YMMvLGuFCbgOgn fdYyis8RdnT7y3MXrzBZ3TvyxMKK4Rwqm7VM1ikthIadJWc3jWV7cj22ux9kRwUTdXxTK9fkXKELV DcA9gXGDQQn6WQ7kHbXNiW3QS+BVEijMSpTLrUgtTmWUbb2aLflqZBr/FN4oUUycpBq6zsaRcmc/k oXgHcs+XkVub6IzZVMTFdEpN2RTnXIzNas5f9TrLGGWJlpYGHjE1a4BR9XK/2nxdZekIY1EnDj9Gy RHpFGDXYg==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1kFVxA-0004Jq-Eh; Tue, 08 Sep 2020 05:14:00 +0000 Received: from foss.arm.com ([217.140.110.172]) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1kFVx6-0004J7-Mw for linux-arm-kernel@lists.infradead.org; Tue, 08 Sep 2020 05:13:58 +0000 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 C727731B; Mon, 7 Sep 2020 22:13:53 -0700 (PDT) Received: from [10.163.71.211] (unknown [10.163.71.211]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id BE6303F73C; Mon, 7 Sep 2020 22:13:49 -0700 (PDT) Subject: Re: [PATCH V3] arm64/cpuinfo: Define HWCAP name arrays per their actual bit definitions To: Will Deacon References: <1597665863-564-1-git-send-email-anshuman.khandual@arm.com> <20200907121611.GA12237@willie-the-truck> From: Anshuman Khandual Message-ID: Date: Tue, 8 Sep 2020 10:43:12 +0530 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <20200907121611.GA12237@willie-the-truck> Content-Language: en-US X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200908_011356_895821_FCB9808F X-CRM114-Status: GOOD ( 30.14 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Mark Rutland , Suzuki K Poulose , catalin.marinas@arm.com, linux-kernel@vger.kernel.org, Ard Biesheuvel , Mark Brown , Dave Martin , 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+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 09/07/2020 05:46 PM, Will Deacon wrote: > On Mon, Aug 17, 2020 at 05:34:23PM +0530, Anshuman Khandual wrote: >> HWCAP name arrays (hwcap_str, compat_hwcap_str, compat_hwcap2_str) that are >> scanned for /proc/cpuinfo are detached from their bit definitions making it >> vulnerable and difficult to correlate. It is also bit problematic because >> during /proc/cpuinfo dump these arrays get traversed sequentially assuming >> they reflect and match actual HWCAP bit sequence, to test various features >> for a given CPU. This redefines name arrays per their HWCAP bit definitions >> . It also warns after detecting any feature which is not expected on arm64. >> >> Cc: Catalin Marinas >> Cc: Will Deacon >> Cc: Mark Brown >> Cc: Dave Martin >> Cc: Ard Biesheuvel >> Cc: Mark Rutland >> Cc: Suzuki K Poulose >> Cc: linux-arm-kernel@lists.infradead.org >> Cc: linux-kernel@vger.kernel.org >> Signed-off-by: Anshuman Khandual >> --- >> This applies on 5.9-rc1 >> >> Mark, since the patch has changed I have dropped your Acked-by: tag. Are you >> happy to give a new one ? >> >> Changes in V3: >> >> - Moved name arrays to (arch/arm64/kernel/cpuinfo.c) to prevent a build warning >> - Replaced string values with NULL for all compat features not possible on arm64 >> - Changed compat_hwcap_str[] iteration on size as some NULL values are expected >> - Warn once after detecting any feature on arm64 that is not expected >> >> Changes in V2: (https://patchwork.kernel.org/patch/11533755/) >> >> - Defined COMPAT_KERNEL_HWCAP[2] and updated the name arrays per Mark >> - Updated the commit message as required >> >> Changes in V1: (https://patchwork.kernel.org/patch/11532945/) >> >> arch/arm64/include/asm/hwcap.h | 9 +++ >> arch/arm64/kernel/cpuinfo.c | 172 ++++++++++++++++++++++------------------- >> 2 files changed, 100 insertions(+), 81 deletions(-) > > [...] > >> + [KERNEL_HWCAP_FP] = "fp", >> + [KERNEL_HWCAP_ASIMD] = "asimd", >> + [KERNEL_HWCAP_EVTSTRM] = "evtstrm", >> + [KERNEL_HWCAP_AES] = "aes", > > It would be nice if the cap and the string were generated by the same > macro, along the lines of: > > #define KERNEL_HWCAP(c) [KERNEL_HWCAP_##c] = #c, > > Does making the constants mixed case break anything, or is it just really > churny to do? Currently all existing HWCAP feature strings are lower case, above change will make them into upper case instead. I could not find a method to force convert #c into lower case constant strings in the macro definition. Would not changing the HWCAP string case here, break user interface ? > >> @@ -166,9 +167,18 @@ static int c_show(struct seq_file *m, void *v) >> seq_puts(m, "Features\t:"); >> if (compat) { >> #ifdef CONFIG_COMPAT >> - for (j = 0; compat_hwcap_str[j]; j++) >> - if (compat_elf_hwcap & (1 << j)) >> + for (j = 0; j < ARRAY_SIZE(compat_hwcap_str); j++) { >> + if (compat_elf_hwcap & (1 << j)) { >> + /* >> + * Warn once if any feature should not >> + * have been present on arm64 platform. >> + */ >> + if (WARN_ON_ONCE(!compat_hwcap_str[j])) >> + continue; >> + >> seq_printf(m, " %s", compat_hwcap_str[j]); >> + } >> + } >> >> for (j = 0; compat_hwcap2_str[j]; j++) > > Hmm, I find this pretty confusing now as compat_hwcap_str is not NULL > terminated and must be traversed with a loop bounded by ARRAY_SIZE(...), Right. Thats because unlike before, it can now have some intermediate NULL entries. Hence NULL sentinel based traversal wont be possible any more. > whereas compat_hwcap2_str *is* NULL terminated and is traversed until you > hit the sentinel. > > I think hwcap_str, compat_hwcap_str and compat_hwcap2_str should be > identical in this regard. Sure, will make the traversal based on ARRAY_SIZE() for all three arrays here, to make that uniform. > > Will > _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel