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=-19.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT 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 AB37AC433ED for ; Tue, 18 May 2021 09:48:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 87791613D1 for ; Tue, 18 May 2021 09:48:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1348097AbhERJtP (ORCPT ); Tue, 18 May 2021 05:49:15 -0400 Received: from mail.kernel.org ([198.145.29.99]:49848 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1348090AbhERJtN (ORCPT ); Tue, 18 May 2021 05:49:13 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 7460E613C8; Tue, 18 May 2021 09:47:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1621331275; bh=k5KbCUN0F2YlNMUf2xfvaa60/l+3klPfLthUfAzmzGA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=IUh4fN2yCR5HduaVygauxlNzp5jizxbUnEaUdzEo1k9g8pVcD0mg1gChO3grPPfS3 7xyJoUy1xX6PebVXgM4JgUFgWwbAR+anDJagqO2iXeGou2OKQ5kR87kAzk4O8PuuAt iDTmVXug7o5AbFjurqVgN3ohJ8Zr1Eyre91fQHrLA8dLl/l0kNlqHoZlIOQphMyojX 6YfAah9AqPPsc/KPZmu+UrPAfhXnHaWaYnTp7GApF6LJ3UxUTqiFzEstcqv5njR41E 91bMYM2M/OxQGfy3u6X12L7dw65enYb7fICh1NpBrx9wUnZQAk3rEenjtS1sS9vdOH 2vQ19b/57LRfQ== From: Will Deacon To: linux-arm-kernel@lists.infradead.org Cc: linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org, Will Deacon , Catalin Marinas , Marc Zyngier , Greg Kroah-Hartman , Peter Zijlstra , Morten Rasmussen , Qais Yousef , Suren Baghdasaryan , Quentin Perret , Tejun Heo , Li Zefan , Johannes Weiner , Ingo Molnar , Juri Lelli , Vincent Guittot , "Rafael J. Wysocki" , kernel-team@android.com Subject: [PATCH v6 05/21] arm64: Advertise CPUs capable of running 32-bit applications in sysfs Date: Tue, 18 May 2021 10:47:09 +0100 Message-Id: <20210518094725.7701-6-will@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20210518094725.7701-1-will@kernel.org> References: <20210518094725.7701-1-will@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Since 32-bit applications will be killed if they are caught trying to execute on a 64-bit-only CPU in a mismatched system, advertise the set of 32-bit capable CPUs to userspace in sysfs. Reviewed-by: Greg Kroah-Hartman Signed-off-by: Will Deacon --- .../ABI/testing/sysfs-devices-system-cpu | 9 +++++++++ arch/arm64/kernel/cpufeature.c | 19 +++++++++++++++++++ 2 files changed, 28 insertions(+) diff --git a/Documentation/ABI/testing/sysfs-devices-system-cpu b/Documentation/ABI/testing/sysfs-devices-system-cpu index fe13baa53c59..899377b2715a 100644 --- a/Documentation/ABI/testing/sysfs-devices-system-cpu +++ b/Documentation/ABI/testing/sysfs-devices-system-cpu @@ -494,6 +494,15 @@ Description: AArch64 CPU registers 'identification' directory exposes the CPU ID registers for identifying model and revision of the CPU. +What: /sys/devices/system/cpu/aarch32_el0 +Date: May 2021 +Contact: Linux ARM Kernel Mailing list +Description: Identifies the subset of CPUs in the system that can execute + AArch32 (32-bit ARM) applications. If present, the same format as + /sys/devices/system/cpu/{offline,online,possible,present} is used. + If absent, then all or none of the CPUs can execute AArch32 + applications and execve() will behave accordingly. + What: /sys/devices/system/cpu/cpu#/cpu_capacity Date: December 2016 Contact: Linux kernel mailing list diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c index 4194a47de62d..959442f76ed7 100644 --- a/arch/arm64/kernel/cpufeature.c +++ b/arch/arm64/kernel/cpufeature.c @@ -67,6 +67,7 @@ #include #include #include +#include #include #include #include @@ -1297,6 +1298,24 @@ const struct cpumask *system_32bit_el0_cpumask(void) return cpu_possible_mask; } +static ssize_t aarch32_el0_show(struct device *dev, + struct device_attribute *attr, char *buf) +{ + const struct cpumask *mask = system_32bit_el0_cpumask(); + + return sysfs_emit(buf, "%*pbl\n", cpumask_pr_args(mask)); +} +static const DEVICE_ATTR_RO(aarch32_el0); + +static int __init aarch32_el0_sysfs_init(void) +{ + if (!allow_mismatched_32bit_el0) + return 0; + + return device_create_file(cpu_subsys.dev_root, &dev_attr_aarch32_el0); +} +device_initcall(aarch32_el0_sysfs_init); + static bool has_32bit_el0(const struct arm64_cpu_capabilities *entry, int scope) { if (!has_cpuid_feature(entry, scope)) -- 2.31.1.751.gd2f1c929bd-goog