Re: [BUG?] ppc64le: fentry BPF not triggered after live patch (v6.14)

[Hari Bathini]

On 04/04/25 12:03 am, Song Liu wrote:
> On Thu, Apr 3, 2025 at 8:30 AM Naveen N Rao <naveen@xxxxxxxxxx> wrote:
> [...]
> > 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@xxxxxxxxxx/

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.

Thanks
Hari