On Mon, Oct 20, 2025 at 2:31 PM Andrey Grodzovsky <[email protected]> wrote: [...] > Song, I identified another issue in pre 6.6 kernel, building > ~/linux-6.5/samples/livepatch/livepatch-sample.c as ko, > before insmoding it, bpftrace fentry/fexit fires as expected, after > insmod, while no errors reported on attachments, > the hooks stop firing, both if attaching before insmod and if attaching > after insmod. If i rrmod the ko, existing hooks > resume working. > > ubuntu@ip-10-10-115-238:~$ cat /proc/version_signature > Ubuntu 6.5.0-1008.8-aws 6.5.3 > Source obtained to build the test module for the AWS kernel from the > related stable branch - > https://cdn.kernel.org/pub/linux/kernel/v6.x/linux-6.5.tar.xz > > Let me know what you think.
I tested various stable kernels. I got: With livepatch, fentry and fexit work on 6.3 kernels. On 6.4 and 6.5 kernels, the combination stops working since this commit: commit 60c8971899f3b34ad24857913c0784dab08962f0 Author: Florent Revest <[email protected]> Date: 2 years, 7 months ago ftrace: Make DIRECT_CALLS work WITH_ARGS and !WITH_REGS On 6.5 kernels, it got fixed by the following two commits: commit a8b9cf62ade1bf17261a979fc97e40c2d7842353 Author: Masami Hiramatsu (Google) <[email protected]> Date: 1 year, 9 months ago ftrace: Fix DIRECT_CALLS to use SAVE_REGS by default commit bdbddb109c75365d22ec4826f480c5e75869e1cb Author: Petr Pavlu <[email protected]> Date: 1 year, 8 months ago tracing: Fix HAVE_DYNAMIC_FTRACE_WITH_REGS ifdef I tried to cherry-pick 60c8971899f3b34ad24857913c0784dab08962f0 and a8b9cf62ade1bf17261a979fc97e40c2d7842353, on top of 6.5.13 kernel. Then, fentry and fexit both work with livepatch. Thanks, Song
