From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753817AbaKXNF2 (ORCPT ); Mon, 24 Nov 2014 08:05:28 -0500 Received: from e06smtp14.uk.ibm.com ([195.75.94.110]:38731 "EHLO e06smtp14.uk.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753541AbaKXNDm (ORCPT ); Mon, 24 Nov 2014 08:03:42 -0500 From: Christian Borntraeger To: linux-kernel@vger.kernel.org Cc: "linux-arch@vger.kernel.org, linux-mips@linux-mips.org, linux-x86_64@vger.kernel.org, linux-s390"@vger.kernel.org, Paolo Bonzini , paulmck@linux.vnet.ibm.com, mingo@kernel.org, torvalds@linux-foundation.org, Catalin Marinas , Will Deacon , Christian Borntraeger Subject: [PATCH/RFC 0/7] ACCESS_ONCE and non-scalar accesses Date: Mon, 24 Nov 2014 14:03:23 +0100 Message-Id: <1416834210-61738-1-git-send-email-borntraeger@de.ibm.com> X-Mailer: git-send-email 1.9.3 X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 14112413-0017-0000-0000-000001F464BB Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org As discussed on LKML http://marc.info/?i=54611D86.4040306%40de.ibm.com ACCESS_ONCE might fail with specific compiler for non-scalar accesses. Here is a set of patches to tackle that problem. (The first patch is already in kvm/next). The last patch will force ACCESS_ONCE to error-out if it is used on non-scalar accesses. I have cross-compiled the resulting kernel with defconfig for microblaze, m68k, alpha, s390,x86_64, i686, sparc, sparc64, mips, ia64, arm and arm64. So hopefully this patch set should be complete regarding the non-scalar accesses. (As Linus pointed out, accesses > word size are a problem on its own, but this patch set does not tackle this) The result is also available as 0d199efcfc9875b8de17bb4fe1d87a27bd39a172 on git://git.kernel.org/pub/scm/linux/kernel/git/borntraeger/linux.git ACCESS_ONCE Now: - It would be good to have the changes reviewed by component experts. - It would also be good if architecture maintainers could double check, that "kernel: Force ACCESS_ONCE to work only on scalar types" does not break anything beyond defconfig. - some comments about cc stable Thanks Christian ---------------------------------------------------------------- Christian Borntraeger (7): KVM: s390: Fix ipte locking mm: replace page table access via ACCESS_ONCE with barriers x86: Rework ACCESS_ONCE for spinlock code x86: Replace ACCESS_ONCE in gup with a barrier mips: Replace ACCESS_ONCE in gup with a barrier arm64: Replace ACCESS_ONCE for spinlock code with barriers kernel: Force ACCESS_ONCE to work only on scalar types arch/arm64/include/asm/spinlock.h | 7 +++++-- arch/mips/mm/gup.c | 6 ++++-- arch/s390/kvm/gaccess.c | 20 ++++++++++++++------ arch/x86/include/asm/spinlock.h | 14 +++++++++----- arch/x86/mm/gup.c | 7 +++++-- include/linux/compiler.h | 12 +++++++++++- mm/gup.c | 4 +++- mm/memory.c | 3 ++- mm/rmap.c | 3 ++- 9 files changed, 55 insertions(+), 21 deletions(-)