On 07/04/25 1:52 pm, Hari Bathini wrote:

On 04/04/25 12:03 am, Song Liu wrote:

quoted

On Thu, Apr 3, 2025 at 8:30 AM Naveen N Rao [off-list ref] wrote:
[...]

quoted

We haven't addressed this particular interaction in the powerpc support
for ftrace direct and BPF trampolines. Right now, live patching takes
priority so we call the livepatch'ed function and skip further ftrace
direct calls.

I'm curious if this works on arm64 with which we share support for
DYNAMIC_FTRACE_WITH_CALL_OPS.

We still need to land [1] for arm64 to support livepatch. In a quick test
with [1], livepatch and bpf trampoline works together. I haven't looked
into the arm64 JIT code, so I am not sure whether all the corner cases
are properly handled.

[1] https://lore.kernel.org/live-patching/20250320171559.3423224-1- 
song@kernel.org/

Thanks for checking this on arm64, Song.
As Naveen pointed out, with out of line trampoline
on ppc64le, there are a few things to sort out with
regard to livepatch & BPF Trampoline interaction. Will
try and take a stab at it soon.

Sorry, couldn't get to it sooner.
Posted the change that fixes livepatch & BPF trampoline
interaction in powerpc upstream now. Please take a look:

  
https://lore.kernel.org/all/20251002192755.86441-1-hbathini@linux.ibm.com/ (local)

- Hari