Re: [PATCH RESEND bpf-next v7 0/4] Add prog_kfunc feature probe

[Eduard Zingerman]

On Thu, 2025-02-20 at 17:07 -0800, Andrii Nakryiko wrote:
> On Tue, Feb 18, 2025 at 2:51 PM Eduard Zingerman <eddyz87@xxxxxxxxx> wrote:
> > 
> > On Mon, 2025-02-17 at 13:21 +0800, Tao Chen wrote:

[...]

> > I tried the test enumerating all kfuncs in BTF and doing
> > libbpf_probe_bpf_kfunc for BPF_PROG_TYPE_{KPROBE,XDP}.
> > (Source code at the end of the email).
> > 
> > The set of kfuncs returned for XDP looks correct.
> > The set of kfuncs returned for KPROBE contains a few incorrect entries:
> > - bpf_xdp_metadata_rx_hash
> > - bpf_xdp_metadata_rx_timestamp
> > - bpf_xdp_metadata_rx_vlan_tag
> > 
> > This is because of a different string reported by verifier for these
> > three functions.
> > 
> > Ideally, I'd write some script looking for
> > register_btf_kfunc_id_set(BPF_PROG_TYPE_***, kfunc_set)
> > calls in the kernel source code and extracting the prog type /
> > functions in the set, and comparing results of this script with
> > output of the test below for all program types.
> > But up to you if you'd like to do such rigorous verification or not.
> > 
> > Otherwise patch-set looks good to me, for all patch-set:
> > 
> > Reviewed-by: Eduard Zingerman <eddyz87@xxxxxxxxx>
> 
> Shouldn't we fix the issue with those bpf_xdp_metadata_* kfuncs? Do

I assume Tao would post a v8 with the fix.

> you have details on what different string verifier reports?

The string is "metadata kfuncs require device-bound program\n".

[...]