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livepatch-build

livepatch-build is a tool for building LivePatch patches from source code patches. It takes as input, a Xen tree and a patch and outputs a .livepatch module containing containing the live patch.

Quick start

First checkout the code, and then run make to build it.

Here is an example of building a live patch for Xen for some XSA. First build Xen, install it on a host somewhere and reboot:

$ cp -r ~/src/xen ~/src/xenbuild
$ cd ~/src/xen/xen
$ make nconfig # Make sure to set CONFIG_LIVEPATCH=y
$ make
$ BUILDID=$(readelf -Wn xen-syms | awk '/Build ID:/ {print $3}')

Next, build a live patch, using a patch and the source, build ID, and .config from the original build:

$ cd ~/src/livepatch-build
$ ./livepatch-build -s ~/src/xenbuild -p ~/src/xsa.patch -o out \
    -c ~/src/xen/xen/.config --depends $BUILDID
Building LivePatch patch: xsa

Xen directory: /home/ross/src/xenbuild
Patch file: /home/ross/src/xsa.patch
Output directory: /home/ross/src/livepatch-build-tools/out
================================================

Testing patch file...
Perform full initial build with 4 CPU(s)...
Apply patch and build with 4 CPU(s)...
Unapply patch and build with 4 CPU(s)...
Extracting new and modified ELF sections...
Processing xen/arch/x86/x86_emulate.o
Creating patch module...
xsa.livepatch created successfully

$ ls -lh out/xsa.livepatch
-rwxrwxr-x. 1 ross ross 135K Jun 10 09:32 out/xsa.livepatch

Finally, copy the live patch to the host and load it:

$ scp out/xsa.livepatch myhost:
$ ssh myhost 'xen-livepatch load xsa.livepatch'
Uploading xsa.livepatch (135840 bytes)
Performing apply:. completed
$ ssh myhost 'xen-livepatch list'
 ID                                     | status
----------------------------------------+------------
xsa                                     | APPLIED

Project Status

Live patches can be built and applied for many changes, including most XSAs; however, there are still some cases which require changing the source patch to allow it to be built as a live patch.

This tool currently supports x86 only.

It is intended that some or all of this project will merge back into kpatch-build rather being maintained as a fork.

Contributing

Please send patches created with git-format-patch and an appropriate Signed-off-by: line to xen-devel@lists.xen.org, CCing the maintainers listed below.

Maintainers

License

LivePatch is under the GPLv2 license.

This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with this program. If not, see http://www.gnu.org/licenses/.

Credits

Most of this code is copied from kPatch. All credits to the kPatch authors.