On Thu, Dec 5, 2024 at 8:03 PM Eduard Zingerman <eddyz87@xxxxxxxxx> wrote:
>
> diff --git a/include/linux/bpf_verifier.h b/include/linux/bpf_verifier.h
> index f4290c179bee..48b7b2eeb7e2 100644
> --- a/include/linux/bpf_verifier.h
> +++ b/include/linux/bpf_verifier.h
> @@ -659,6 +659,7 @@ struct bpf_subprog_info {
> bool args_cached: 1;
> /* true if bpf_fastcall stack region is used by functions that can't be inlined */
> bool keep_fastcall_stack: 1;
> + bool changes_pkt_data: 1;
since freplace was brought up in the other thread.
Let's fix it all in one patch.
I think propagating changes_pkt_data flag into prog_aux and
into map->owner should do it.
The handling will be similar to existing xdp_has_frags.
Otherwise tail_call from static subprog will have the same issue.
xdp_has_frags compatibility requires equality. All progs either
have it or don't.
changes_pkt_data flag doesn't need to be that strict:
A prog with changes_pkt_data can be freplaced by prog without
and tailcall into prog without it.
But not the other way around.
