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=-15.9 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI, 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 DF825C433E0 for ; Fri, 5 Feb 2021 16:36:40 +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 7BF4964EBF for ; Fri, 5 Feb 2021 16:36:40 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7BF4964EBF Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org 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:References:Message-ID: 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=yye0Ajy30w/U+RiQnjM8V3x6EPBOVapJylKcjdKcsvk=; b=BPPS1qDG/OBWwzZWNiRn1v/M+ fIwI3vuL1kerJ/uSfwL4V9clCVD/cP4dltKlzTWH9OB/VG6GnG2wYeVx+frD794GBeqP8LFvhiJR3 D3VxKA31XQii7Sy9cdev/TW+nWxtrlGs/OZdUNyZyqil4DhpTJBIPoNsbqtArmdGXapRODKuJ1DpE 9S+TSEMKTHjVu8MNaa7m+BJXsbEiSTemdekY4m/S8xwmLLohbotNDY4t7X7u+kVpYokinH4jnUoic oBjBxzQndZkRD5DozIFbmh5++/cQ9aHy2roxBcGiltVI4KVtuFCg2G3o5G0GsMmVKira4kGgiPtcN 8RyZpZj3Q==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1l844y-0006HB-Cs; Fri, 05 Feb 2021 16:35:32 +0000 Received: from mail.kernel.org ([198.145.29.99]) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1l844v-0006GA-V7 for linux-arm-kernel@lists.infradead.org; Fri, 05 Feb 2021 16:35:31 +0000 Received: by mail.kernel.org (Postfix) with ESMTPSA id 5406D64EA1; Fri, 5 Feb 2021 16:35:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1612542928; bh=u1co/FGUat5HAI0yiGhQV5noHY+wEidod999P0y8ViM=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=MsQqI2OprR5K8XBTnraMicQl74H5xko+0MMnyykPyvgI9YrKYFCMFR/RtXsed/BzW SXFgRKhNWXw95Eottebxi8Ys+xK+Un6T+rySi2SADXZkfJ17awPDHIum6UkEx2KPyt XV38tn5MTx/hI14KD2VQ115CqZ7ZM2O2BQ1UiGxg+303PJncao1khjzgecRuAD1s0f w9zp6SkM4B3keN4/XtsmmrgzhZskd8LXV9Q8Zd+8dHU6iH7Ec1kTLjBWKr7z0BQ/GK 4nKiMN7r+Yx8pK2Frh3LJSDnqhawCmXJAYzb/UUg8EqSneIZQtgoo4ywTiFGPX89WF lbdNOWOrgjWlw== Date: Fri, 5 Feb 2021 16:35:21 +0000 From: Will Deacon To: Marc Zyngier Subject: Re: [PATCH v6 12/21] arm64: cpufeature: Add an early command-line cpufeature override facility Message-ID: <20210205163521.GA22665@willie-the-truck> References: <20210201115637.3123740-1-maz@kernel.org> <20210201115637.3123740-13-maz@kernel.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20210201115637.3123740-13-maz@kernel.org> User-Agent: Mutt/1.10.1 (2018-07-13) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210205_113530_224539_3EC7F6BA X-CRM114-Status: GOOD ( 24.82 ) 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 , Jing Zhang , Prasad Sodagudi , Srinivas Ramana , Suzuki K Poulose , Catalin Marinas , linux-kernel@vger.kernel.org, Ard Biesheuvel , James Morse , Julien Thierry , Ajay Patil , kernel-team@android.com, David Brazdil , Alexandru Elisei , kvmarm@lists.cs.columbia.edu, 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 Mon, Feb 01, 2021 at 11:56:28AM +0000, Marc Zyngier wrote: > In order to be able to override CPU features at boot time, > let's add a command line parser that matches options of the > form "cpureg.feature=value", and store the corresponding > value into the override val/mask pair. > > No features are currently defined, so no expected change in > functionality. > > Signed-off-by: Marc Zyngier > Acked-by: David Brazdil > Reviewed-by: Catalin Marinas > --- > arch/arm64/kernel/Makefile | 2 +- > arch/arm64/kernel/head.S | 1 + > arch/arm64/kernel/idreg-override.c | 164 +++++++++++++++++++++++++++++ > 3 files changed, 166 insertions(+), 1 deletion(-) > create mode 100644 arch/arm64/kernel/idreg-override.c > > diff --git a/arch/arm64/kernel/Makefile b/arch/arm64/kernel/Makefile > index 86364ab6f13f..2262f0392857 100644 > --- a/arch/arm64/kernel/Makefile > +++ b/arch/arm64/kernel/Makefile > @@ -17,7 +17,7 @@ obj-y := debug-monitors.o entry.o irq.o fpsimd.o \ > return_address.o cpuinfo.o cpu_errata.o \ > cpufeature.o alternative.o cacheinfo.o \ > smp.o smp_spin_table.o topology.o smccc-call.o \ > - syscall.o proton-pack.o > + syscall.o proton-pack.o idreg-override.o > > targets += efi-entry.o > > diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S > index d74e5f84042e..3243e3ae9bd8 100644 > --- a/arch/arm64/kernel/head.S > +++ b/arch/arm64/kernel/head.S > @@ -435,6 +435,7 @@ SYM_FUNC_START_LOCAL(__primary_switched) > > mov x0, x21 // pass FDT address in x0 > bl early_fdt_map // Try mapping the FDT early > + bl init_feature_override > bl switch_to_vhe > #if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS) > bl kasan_early_init > diff --git a/arch/arm64/kernel/idreg-override.c b/arch/arm64/kernel/idreg-override.c > new file mode 100644 > index 000000000000..d8d0d3b25bc3 > --- /dev/null > +++ b/arch/arm64/kernel/idreg-override.c > @@ -0,0 +1,164 @@ > +// SPDX-License-Identifier: GPL-2.0 > +/* > + * Early cpufeature override framework > + * > + * Copyright (C) 2020 Google LLC > + * Author: Marc Zyngier > + */ > + > +#include > +#include > +#include > + > +#include > +#include > + > +#define FTR_DESC_NAME_LEN 20 > +#define FTR_DESC_FIELD_LEN 10 > + > +struct ftr_set_desc { > + char name[FTR_DESC_NAME_LEN]; > + struct arm64_ftr_override *override; > + struct { > + char name[FTR_DESC_FIELD_LEN]; > + u8 shift; > + } fields[]; > +}; > + > +static const struct ftr_set_desc * const regs[] __initconst = { > +}; > + > +static char *cmdline_contains_option(const char *cmdline, const char *option) > +{ > + char *str = strstr(cmdline, option); > + > + if ((str == cmdline || (str > cmdline && isspace(*(str - 1))))) > + return str; > + > + return NULL; > +} > + > +static int __init find_field(const char *cmdline, > + const struct ftr_set_desc *reg, int f, u64 *v) > +{ > + char opt[FTR_DESC_NAME_LEN + FTR_DESC_FIELD_LEN + 2], *str; > + size_t len; > + > + snprintf(opt, ARRAY_SIZE(opt), "%s.%s=", reg->name, reg->fields[f].name); > + > + str = cmdline_contains_option(cmdline, opt); > + if (!str) > + return -1; > + > + str += strlen(opt); > + len = strcspn(str, " "); I'm absolutely terrified of string parsing in C, but just wondering why you only ignore literal spaces here. I _think_ the full-fat cmdline parsing uses isspace() to delimit the options. Would it be possible to reuse any of the logic over in parse_args() to avoid having to roll this ourselves? Will _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel