From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755765AbcA2CQm (ORCPT ); Thu, 28 Jan 2016 21:16:42 -0500 Received: from youngberry.canonical.com ([91.189.89.112]:60863 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752239AbcA2BU3 (ORCPT ); Thu, 28 Jan 2016 20:20:29 -0500 From: Kamal Mostafa To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: Will Deacon , Kamal Mostafa Subject: [PATCH 3.19.y-ckt 029/210] arm64: mdscr_el1: avoid exposing DCC to userspace Date: Thu, 28 Jan 2016 17:16:07 -0800 Message-Id: <1454030348-17736-30-git-send-email-kamal@canonical.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1454030348-17736-1-git-send-email-kamal@canonical.com> References: <1454030348-17736-1-git-send-email-kamal@canonical.com> X-Extended-Stable: 3.19 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.19.8-ckt14 -stable review patch. If anyone has any objections, please let me know. ---8<------------------------------------------------------------ From: Will Deacon commit d8d23fa0f27f3b2942a7bbc7378c7735324ed519 upstream. We don't want to expose the DCC to userspace, particularly as there is a kernel console driver for it. This patch resets mdscr_el1 to disable userspace access to the DCC registers on the cold boot path. Signed-off-by: Will Deacon Signed-off-by: Kamal Mostafa --- arch/arm64/mm/proc.S | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/arch/arm64/mm/proc.S b/arch/arm64/mm/proc.S index 4e778b1..bccdaf5 100644 --- a/arch/arm64/mm/proc.S +++ b/arch/arm64/mm/proc.S @@ -201,7 +201,8 @@ ENTRY(__cpu_setup) mov x0, #3 << 20 msr cpacr_el1, x0 // Enable FP/ASIMD - msr mdscr_el1, xzr // Reset mdscr_el1 + mov x0, #1 << 12 // Reset mdscr_el1 and disable + msr mdscr_el1, x0 // access to the DCC from EL0 /* * Memory region attributes for LPAE: * -- 1.9.1