Re: [PATCH v2 bpf-next 07/20] bpf: Add x86-64 JIT support for PROBE_MEM32 pseudo instructions.

[Alexei Starovoitov <alexei.starovoitov@xxxxxxxxx>]

On Fri, Feb 9, 2024 at 10:49 PM Kumar Kartikeya Dwivedi
<memxor@xxxxxxxxx> wrote:
> > +               if (arena_vm_start)
> > +                       push_r12(&prog);
>
> I believe since this is done on entry for arena_vm_start, we need to
> do matching pop_r12 in
> emit_bpf_tail_call_indirect and emit_bpf_tail_call_direct before tail
> call, unless I'm missing something.
> Otherwise r12 may be bad after prog (push + set to arena_vm_start) ->
> tail call -> exit (no pop of r12 back from stack).

Good catch! Fixed.