Re: xdp_iphash_to_cpu_cmdline: Error loading BTF: Invalid argument(22)

[Jesper Dangaard Brouer <brouer@redhat.com>]

On Thu, 24 Jun 2021 18:14:43 -0700
Y Song <ys114321@gmail.com> wrote:

> On Thu, Jun 24, 2021 at 1:45 PM Ethy H. Brito <ethy.brito@inexo.com.br> wrote:
> >
> > On Thu, 24 Jun 2021 22:16:37 +0200
> > Jesper Dangaard Brouer <brouer@redhat.com> wrote:
> >  
> > > On Thu, 24 Jun 2021 17:04:58 -0300
> > > "Ethy H. Brito" <ethy.brito@inexo.com.br> wrote:
> > >  
> > > > On Tue, 22 Jun 2021 17:22:16 -0300
> > > > "Ethy"  wrote:
> > > >  
> > > > > Hi
> > > > >
> > > > > Runing "# ./xdp_iphash_to_cpu --dev eth1 --all-cpus --wan" returns 2 loading errors:
> > > > >
> > > > > ----------------------8<----------------------------------
> > > > > libbpf: Error loading BTF: Invalid argument(22)
> > > > > libbpf: magic: 0xeb9f
> > > > > version: 1
> > > > > flags: 0x0
> > > > > hdr_len: 24
> > > > > type_off: 0
> > > > > type_len: 492
> > > > > str_off: 492
> > > > > str_len: 1724
> > > > > btf_total_size: 2240
> > > > > [1] PTR (anon) type_id=2
> > > > > [2] STRUCT xdp_md size=20 vlen=5
> > > > >   data type_id=3 bits_offset=0
> > > > >   data_end type_id=3 bits_offset=32
> > > > >   data_meta type_id=3 bits_offset=64
> > > > >   ingress_ifindex type_id=3 bits_offset=96
> > > > >   rx_queue_index type_id=3 bits_offset=128
> > > > > [3] TYPEDEF __u32 type_id=4
> > > > > [4] INT unsigned int size=4 bits_offset=0 nr_bits=32 encoding=(none)
> > > > > [5] FUNC_PROTO (anon) return=6 args=(1 ctx)
> > > > > [6] INT int size=4 bits_offset=0 nr_bits=32 encoding=SIGNED
> > > > > [7] FUNC xdp_program type_id=5 vlen != 0
> > > > >
> > > > > libbpf: Error loading ELF section .BTF: -22. Ignored and continue.  
> > >
> > > NOTICE above: "Ignored and continue".
> > >
> > > Thus, this is not a real *error*, instead this is just a (very) verbose
> > > *warning* that your system (kernel version? / compile options?) doesn't
> > > support BTF correctly.  The BTF info is not really needed by
> > > xdp-cpuma-tc, so you can safely ignore this "warning".  
> 
> FYI, the error is due to
>     [7] FUNC xdp_program type_id=5 vlen != 0
> I guess you may have an old libbpf. The new libbpf should do
> sanitization for this.
>   https://lore.kernel.org/bpf/20200110064124.1760511-2-ast@kernel.org/

Ah, thanks for pointing that out!  Guess it is my fault, that I've not
kept git-submodule for libbpf up-to-date in this git-repo.

With the recent interest for xdp-cpumap-tc[1], I will try find some
time to update libbpf and also fix other practical issues that have
been reported to me.

[1] https://github.com/xdp-project/xdp-cpumap-tc
-- 
Best regards,
  Jesper Dangaard Brouer
  MSc.CS, Principal Kernel Engineer at Red Hat
  LinkedIn: http://www.linkedin.com/in/brouer