From patchwork Wed Jun 2 16:47:16 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Will Deacon X-Patchwork-Id: 12295379 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=-17.4 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_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 BC492C47083 for ; Wed, 2 Jun 2021 16:59:36 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (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 8D17861C83 for ; Wed, 2 Jun 2021 16:59:36 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 8D17861C83 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=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-Id:Date:Subject:Cc:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=kjinlUV/IW1xOnHxi5goqHP4qCNPwVJYjwWwMytLWek=; b=l+Vh/8Sa+S0TNl X9Lx/tPHuAxc7g0mZB4D8Y/8P35Sg2KO7E4EoLM9+9f5pR43EmObmBEgNK7AVU3sarTMFBDsMk2+w ssMIcn6q9GwYZs6bzsGRoWoT7nZCGDxstxCLyYRV/L3AL6bzth35jth63S6MEFpfgum39gNy8EQMd FM7Vxj6tUXmaD/o0gNuge1a1e71ZgbqVZvj9I15J5eWMttTzu4mHxIG6cszNDsSqeqzhvnm1u1RmR dD/86DoaPifDOdg0zs9QJYSLLXv/v3mRvu9O/RWUkLTl6cwsHjLIhsh92ACiXJxkrAx6gRyINdOhJ 6Oq/hlRhJNmphYwwnq/A==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1loUBX-005JO6-RK; Wed, 02 Jun 2021 16:57:40 +0000 Received: from mail.kernel.org ([198.145.29.99]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1loU2k-005FTy-Av for linux-arm-kernel@lists.infradead.org; Wed, 02 Jun 2021 16:48:35 +0000 Received: by mail.kernel.org (Postfix) with ESMTPSA id 9118261C1A; Wed, 2 Jun 2021 16:48:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1622652514; bh=x0QP/3o6xRJ/gC/T6Aypyq2owsN7PsaVjL0+LhRfv9A=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=aBnfLC8lVlr7fHXCOk8mA0nAY/vKDSF+BFWsimunyPFQGA+5mKZ6F4dgWi7zGHvnu DwylaewYl9cAatwBF4rvFQ6I6/vN6gYXGkEqknGS+EYwAuluMHSb8HLzE2jJohIZnl 0de3WtTvewghIQ+8CdgMRCEqPCLPQ/fM3iF3chVsCLr0Fox52NRahcu642ScVWWsBq 0FQ6eHTSobS3Q3H+jYa5+mjBLGCi998N8MQSZYdb+V8CDWvE9WMRJM+cEfQiSEaTBE 0gHV+Lb5RGqHOERkJNW1wmkmm3yssDuwrvtXJChDZhVQZDIL/HDe9QO1MNHtcJfi/a RNO7hNv6sIyPg== 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 , Johannes Weiner , Ingo Molnar , Juri Lelli , Vincent Guittot , "Rafael J. Wysocki" , Dietmar Eggemann , Daniel Bristot de Oliveira , Valentin Schneider , kernel-team@android.com Subject: [PATCH v8 16/19] arm64: Advertise CPUs capable of running 32-bit applications in sysfs Date: Wed, 2 Jun 2021 17:47:16 +0100 Message-Id: <20210602164719.31777-17-will@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20210602164719.31777-1-will@kernel.org> References: <20210602164719.31777-1-will@kernel.org> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210602_094834_447687_A3CEB48B X-CRM114-Status: GOOD ( 13.06 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.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 Reviewed-by: Catalin Marinas 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 b31d7a1eaed6..72efdc611b14 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))