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This is another step how to help maintaining more livepatches. One big help was the atomic replace and cumulative livepatches. These livepatches replace the already installed ones. Therefore it should be enough when each cumulative livepatch is consistent. The problems might come with shadow variables and callbacks. They might change the system behavior or state so that it is no longer safe to go back and use an older livepatch or the original kernel code. Also, a new livepatch must be able to detect changes which were made by the already installed livepatches. This is where the livepatch system state tracking gets useful. It allows to: - find whether a system state has already been modified by previous livepatches - store data needed to manipulate and restore the system state The information about the manipulated system states is stored in an array of struct klp_state. It can be searched by two new functions klp_get_state() and klp_get_prev_state(). The dependencies are going to be solved by a version field added later. The only important information is that it will be allowed to modify the same state by more non-cumulative livepatches. It is similar to allowing to modify the same function several times. The livepatch author is responsible for preventing incompatible changes. Link: http://lkml.kernel.org/r/20191030154313.13263-3-pmladek@suse.com To: Jiri Kosina <jikos@kernel.org> Cc: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com> Cc: Nicolai Stange <nstange@suse.de> Cc: live-patching@vger.kernel.org Cc: linux-kernel@vger.kernel.org Acked-by: Miroslav Benes <mbenes@suse.cz> Acked-by: Joe Lawrence <joe.lawrence@redhat.com> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Signed-off-by: Petr Mladek <pmladek@suse.com>
5 lines
143 B
Makefile
5 lines
143 B
Makefile
# SPDX-License-Identifier: GPL-2.0-only
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obj-$(CONFIG_LIVEPATCH) += livepatch.o
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livepatch-objs := core.o patch.o shadow.o state.o transition.o
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