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=-8.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, 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 DAE5BC433DF for ; Tue, 26 May 2020 13:59:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C1F49208B3 for ; Tue, 26 May 2020 13:59:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731442AbgEZN73 (ORCPT ); Tue, 26 May 2020 09:59:29 -0400 Received: from foss.arm.com ([217.140.110.172]:51254 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728558AbgEZN72 (ORCPT ); Tue, 26 May 2020 09:59:28 -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 D719E1FB; Tue, 26 May 2020 06:59:27 -0700 (PDT) Received: from [10.37.8.5] (unknown [10.37.8.5]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 13CD43F6C4; Tue, 26 May 2020 06:59:25 -0700 (PDT) Subject: Re: [PATCH V2] arm64/cpufeature: Add get_arm64_ftr_reg_nowarn() To: anshuman.khandual@arm.com, linux-arm-kernel@lists.infradead.org Cc: mark.rutland@arm.com, catalin.marinas@arm.com, will@kernel.org, broonie@kernel.org, linux-kernel@vger.kernel.org References: <1590500353-28082-1-git-send-email-anshuman.khandual@arm.com> From: Suzuki K Poulose Message-ID: <0726a5b9-fff6-a15c-e705-db7abd4b1abd@arm.com> Date: Tue, 26 May 2020 15:04:14 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.7.0 MIME-Version: 1.0 In-Reply-To: <1590500353-28082-1-git-send-email-anshuman.khandual@arm.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 05/26/2020 02:39 PM, Anshuman Khandual wrote: > There is no way to proceed when requested register could not be searched in > arm64_ftr_reg[]. Requesting for a non present register would be an error as > well. Hence lets just WARN_ON() when search fails in get_arm64_ftr_reg() > rather than checking for return value and doing a BUG_ON() instead in some > individual callers. But there are also caller instances that dont error out > when register search fails. Add a new helper get_arm64_ftr_reg_nowarn() for > such cases. > > Cc: Catalin Marinas > Cc: Will Deacon > Cc: Suzuki K Poulose > Cc: Mark Brown > Cc: linux-arm-kernel@lists.infradead.org > Cc: linux-kernel@vger.kernel.org > Signed-off-by: Anshuman Khandual > --- > Changes in V2: > > - Added get_arm64_ftr_reg_nowarn() per Will > - read_sanitised_ftr_reg() returns 0 when register search fails per Catalin > > Changes in V1: (https://patchwork.kernel.org/patch/11559083/) > > arch/arm64/kernel/cpufeature.c | 42 +++++++++++++++++++++++----------- > 1 file changed, 29 insertions(+), 13 deletions(-) > > diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c > index bc5048f152c1..f4555b9d145c 100644 > --- a/arch/arm64/kernel/cpufeature.c > +++ b/arch/arm64/kernel/cpufeature.c > @@ -548,16 +548,16 @@ static int search_cmp_ftr_reg(const void *id, const void *regp) > } > ... > static u64 arm64_ftr_set_value(const struct arm64_ftr_bits *ftrp, s64 reg, > s64 ftr_val) > { > @@ -632,8 +654,6 @@ static void __init init_cpu_ftr_reg(u32 sys_reg, u64 new) > const struct arm64_ftr_bits *ftrp; > struct arm64_ftr_reg *reg = get_arm64_ftr_reg(sys_reg); > > - BUG_ON(!reg); > - > for (ftrp = reg->ftr_bits; ftrp->width; ftrp++) { > u64 ftr_mask = arm64_ftr_mask(ftrp); > s64 ftr_new = arm64_ftr_value(ftrp, new); > @@ -762,7 +782,6 @@ static int check_update_ftr_reg(u32 sys_id, int cpu, u64 val, u64 boot) > { > struct arm64_ftr_reg *regp = get_arm64_ftr_reg(sys_id); > > - BUG_ON(!regp); > update_cpu_ftr_reg(regp, val); > if ((boot & regp->strict_mask) == (val & regp->strict_mask)) > return 0; > @@ -776,9 +795,6 @@ static void relax_cpu_ftr_reg(u32 sys_id, int field) > const struct arm64_ftr_bits *ftrp; > struct arm64_ftr_reg *regp = get_arm64_ftr_reg(sys_id); > > - if (WARN_ON(!regp)) > - return; > - You need to return here, on !regp. Rest looks fine to me. Suzuki