Re: [RFC PATCH 1/1] arm64: implement live patching

On Mon, Jun 07, 2021 at 11:20:58AM +0100, Mark Rutland wrote:

On Fri, Jun 04, 2021 at 04:59:30PM -0700, Suraj Jitindar Singh wrote:

quoted

It's my understanding that the two pieces of work required to enable live
patching on arm are in flight upstream;
- Reliable stack traces as implemented by Madhavan T. Venkataraman [1]
- Objtool as implemented by Julien Thierry [2]

We also need to rework the arm64 patching code to not rely on any code
which may itself be patched. Currently there's a reasonable amount of
patching code that can either be patched directly, or can be
instrumented by code that can be patched.

I have some WIP patches for that at:

  https://git.kernel.org/pub/scm/linux/kernel/git/mark/linux.git/log/?h=arm64/patching/rework

... but there's still a lot to do, and it's not clear to me if there's
other stuff we need to rework to make patch-safe.

Do we have any infrastructure for testing LIVEPATCH?

Hi Mark,

If you're looking for a high level sanity check, there are livepatching
integration selftests in tools/testing/selftests/livepatch.  Let me know
if you have any questions about those.

Regards,

-- Joe