From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:44691 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752972AbcA0G4y (ORCPT ); Wed, 27 Jan 2016 01:56:54 -0500 Subject: Patch "arm64: mm: ensure that the zero page is visible to the page table walker" has been added to the 4.1-stable tree To: will.deacon@arm.com, gregkh@linuxfoundation.org Cc: , From: Date: Tue, 26 Jan 2016 22:54:53 -0800 Message-ID: <1453877693191117@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org List-ID: This is a note to let you know that I've just added the patch titled arm64: mm: ensure that the zero page is visible to the page table walker to the 4.1-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: arm64-mm-ensure-that-the-zero-page-is-visible-to-the-page-table-walker.patch and it can be found in the queue-4.1 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let know about it. >>From 32d6397805d00573ce1fa55f408ce2bca15b0ad3 Mon Sep 17 00:00:00 2001 From: Will Deacon Date: Thu, 10 Dec 2015 16:05:36 +0000 Subject: arm64: mm: ensure that the zero page is visible to the page table walker From: Will Deacon commit 32d6397805d00573ce1fa55f408ce2bca15b0ad3 upstream. In paging_init, we allocate the zero page, memset it to zero and then point TTBR0 to it in order to avoid speculative fetches through the identity mapping. In order to guarantee that the freshly zeroed page is indeed visible to the page table walker, we need to execute a dsb instruction prior to writing the TTBR. Signed-off-by: Will Deacon Signed-off-by: Greg Kroah-Hartman --- arch/arm64/mm/mmu.c | 3 +++ 1 file changed, 3 insertions(+) --- a/arch/arm64/mm/mmu.c +++ b/arch/arm64/mm/mmu.c @@ -450,6 +450,9 @@ void __init paging_init(void) empty_zero_page = virt_to_page(zero_page); + /* Ensure the zero page is visible to the page table walker */ + dsb(ishst); + /* * TTBR0 is only used for the identity mapping at this stage. Make it * point to zero page to avoid speculatively fetching new entries. Patches currently in stable-queue which might be from will.deacon@arm.com are queue-4.1/arm64-kernel-pause-unpause-function-graph-tracer-in-cpu_suspend.patch queue-4.1/arm64-mm-ensure-that-the-zero-page-is-visible-to-the-page-table-walker.patch queue-4.1/arm64-fix-building-without-config_uid16.patch queue-4.1/arm64-clear-out-any-singlestep-state-on-a-ptrace-detach-operation.patch queue-4.1/recordmcount-arm64-replace-the-ignored-mcount-call-into-nop.patch