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=-13.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT 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 19FF2C388F9 for ; Tue, 27 Oct 2020 21:51:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C0A862224E for ; Tue, 27 Oct 2020 21:51:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1603835497; bh=7xtHpE+jN4KpE9aM9q3M6jMkm03ttdE7SBSV+UdhCUQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=cQDhz6AdJw/1TKk8JXilC0IqOpEXCaN98BLE+dMF1jPaeYsBU2NWYZpPxrTR3i19H ES0E+LsOzQ3TRYdJJn1keYgYwvedF8G+Ma73tU1fbSvhrSRWWIue2xSZXyp8eppqQW It6nbjrpEy/Ugv9ZwDK1JT+OmqTxSI1/cKf1NF60= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S374487AbgJ0Vvh (ORCPT ); Tue, 27 Oct 2020 17:51:37 -0400 Received: from mail.kernel.org ([198.145.29.99]:43198 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730075AbgJ0Vvh (ORCPT ); Tue, 27 Oct 2020 17:51:37 -0400 Received: from localhost.localdomain (236.31.169.217.in-addr.arpa [217.169.31.236]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 5CC1B20829; Tue, 27 Oct 2020 21:51:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1603835496; bh=7xtHpE+jN4KpE9aM9q3M6jMkm03ttdE7SBSV+UdhCUQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=l/U0lij0fRys470mF3hwkMMbzObDJHRKi2dF5fW3IA/jbYB9alNaVzhhx/g/7o6cg bqIbnBe1A7JAGpgFfiIj6b5z/Kv+dMaHVEN4zTs8fceQxp4LBtoXHGGSPMr5p3qD9D f2ECqbFgp1/9T4F9tzZUUfDvDhUzvbLGLBgZ5fTY= From: Will Deacon To: linux-arm-kernel@lists.infradead.org Cc: linux-arch@vger.kernel.org, Will Deacon , Catalin Marinas , Marc Zyngier , Greg Kroah-Hartman , Peter Zijlstra , Morten Rasmussen , Qais Yousef , Suren Baghdasaryan , kernel-team@android.com Subject: [PATCH 5/6] arm64: Advertise CPUs capable of running 32-bit applcations in sysfs Date: Tue, 27 Oct 2020 21:51:17 +0000 Message-Id: <20201027215118.27003-6-will@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20201027215118.27003-1-will@kernel.org> References: <20201027215118.27003-1-will@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-arch@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. Signed-off-by: Will Deacon --- .../ABI/testing/sysfs-devices-system-cpu | 8 ++++++++ arch/arm64/kernel/cpufeature.c | 19 +++++++++++++++++++ 2 files changed, 27 insertions(+) diff --git a/Documentation/ABI/testing/sysfs-devices-system-cpu b/Documentation/ABI/testing/sysfs-devices-system-cpu index b555df825447..19893fb8e870 100644 --- a/Documentation/ABI/testing/sysfs-devices-system-cpu +++ b/Documentation/ABI/testing/sysfs-devices-system-cpu @@ -472,6 +472,14 @@ 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: October 2020 +Contact: Linux ARM Kernel Mailing list +Description: Identifies the subset of CPUs in the system that can execute + AArch32 (32-bit ARM) applications. 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 2e2219cbd54c..9f29d4d1ef7e 100644 --- a/arch/arm64/kernel/cpufeature.c +++ b/arch/arm64/kernel/cpufeature.c @@ -67,6 +67,7 @@ #include #include #include +#include #include #include #include @@ -1236,6 +1237,24 @@ bool system_has_mismatched_32bit_el0(void) return fld == ID_AA64PFR0_EL0_64BIT_ONLY; } +static ssize_t aarch32_el0_show(struct kobject *kobj, + struct kobj_attribute *attr, char *buf) +{ + const struct cpumask *mask = system_32bit_el0_cpumask(); + return sprintf(buf, "%*pbl\n", cpumask_pr_args(mask)); +} +static const struct kobj_attribute aarch32_el0_attr = __ATTR_RO(aarch32_el0); + +static int __init aarch32_el0_sysfs_init(void) +{ + if (!__allow_mismatched_32bit_el0) + return 0; + + return sysfs_create_file(&cpu_subsys.dev_root->kobj, + &aarch32_el0_attr.attr); +} +device_initcall(aarch32_el0_sysfs_init); + static bool has_32bit_el0(const struct arm64_cpu_capabilities *entry, int scope) { return has_cpuid_feature(entry, scope) || __allow_mismatched_32bit_el0; -- 2.29.0.rc2.309.g374f81d7ae-goog