From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755783AbdGSReC (ORCPT ); Wed, 19 Jul 2017 13:34:02 -0400 Received: from mx0a-00190b01.pphosted.com ([67.231.149.131]:44304 "EHLO mx0a-00190b01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754738AbdGSReA (ORCPT ); Wed, 19 Jul 2017 13:34:00 -0400 From: Jason Baron To: linux-kernel@vger.kernel.org, live-patching@vger.kernel.org Cc: jpoimboe@redhat.com, jeyu@kernel.org, jikos@kernel.org, mbenes@suse.cz, pmladek@suse.com Subject: [PATCH 0/3] livepatch: introduce atomic replace Date: Wed, 19 Jul 2017 13:18:04 -0400 Message-Id: X-Mailer: git-send-email 1.9.1 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2017-07-19_12:,, signatures=0 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 spamscore=0 suspectscore=0 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1706020000 definitions=main-1707190274 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2017-07-19_12:,, signatures=0 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1011 lowpriorityscore=0 impostorscore=0 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1706020000 definitions=main-1707190274 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, In testing livepatch, I found that when doing cumulative patches, if a patched function is completed reverted by a subsequent patch (back to its original state) livepatch does not revert the funtion to its original state. Specifically, if patch A introduces a change to function 1, and patch B reverts the change to function 1 and introduces changes to say function 2 and 3 as well, the change that patch A introducd to function 1 is still present. This could be addressed by first completely removing patch A (disable and then rmmod) and then inserting patch B (insmod and enable), but this leaves an unpatched window. In discussing this issue with Josh on the kpatch mailing list, he mentioned that we could get 'atomic replace working properly', and that is the direction of this patchset: https://www.redhat.com/archives/kpatch/2017-June/msg00005.html Patches: 1) livepatch: Add klp_object and klp_func iterators Just a prep patch for the 'atomic revert' feature 2) livepatch: add atomic replace Core feature 3) livepatch: Add a sysctl livepatch_mode for atomic replace Introduces a knob for enabling atomic replace. I hate knobs and perhaps its possible to default to cumulative replace? Although I suspect there are workflows relying on the existing behavior - I'm not sure. It may be desirable to associate the knob with the patch itself as in the 'immediate' flag, such that we don't introduce a global sysctl that likely would also need to built-in, if there are patches in the initrd. Thanks, -Jason Jason Baron (3): livepatch: Add klp_object and klp_func iterators livepatch: add atomic replace livepatch: Add a sysctl livepatch_mode for atomic revert include/linux/livepatch.h | 118 ++++++++++++++++++++++++++++++-- kernel/livepatch/core.c | 154 ++++++++++++++++++++++++++++++++++++++++-- kernel/livepatch/core.h | 4 ++ kernel/livepatch/patch.c | 23 ++++--- kernel/livepatch/patch.h | 1 + kernel/livepatch/transition.c | 79 +++++++++++++++++++--- kernel/sysctl.c | 12 ++++ 7 files changed, 362 insertions(+), 29 deletions(-) -- 2.6.1