libbpf: Error loading BTF: Invalid argument(22)

[interduo]

./xdp-cpumap-tc/src/xdp_iphash_to_cpu --dev ens16f1 --wan
libbpf: Error loading BTF: Invalid argument(22)
libbpf: magic: 0xeb9f
version: 1
flags: 0x0
hdr_len: 24
type_off: 0
type_len: 504
str_off: 504
str_len: 1726
btf_total_size: 2254
[1] PTR (anon) type_id=2
[2] STRUCT xdp_md size=24 vlen=6
	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
	egress_ifindex type_id=3 bits_offset=160
[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
[8] STRUCT bpf_map_def size=24 vlen=6
	type type_id=4 bits_offset=0
	key_size type_id=4 bits_offset=32
	value_size type_id=4 bits_offset=64
	max_entries type_id=4 bits_offset=96
	map_flags type_id=4 bits_offset=128
	inner_map_idx type_id=4 bits_offset=160
[9] VAR map_ip_hash type_id=8 linkage=1
[10] VAR map_txq_config type_id=8 linkage=1
[11] VAR map_ifindex_type type_id=8 linkage=1
[12] VAR cpu_map type_id=8 linkage=1
[13] VAR cpus_available type_id=8 linkage=1
[14] INT char size=1 bits_offset=0 nr_bits=8 encoding=SIGNED
[15] ARRAY (anon) type_id=14 index_type_id=16 nr_elems=4
[16] INT __ARRAY_SIZE_TYPE__ size=4 bits_offset=0 nr_bits=32 encoding=(none)
[17] VAR _license type_id=15 linkage=1
[18] DATASEC license size=0 vlen=1 size == 0

libbpf: Error loading ELF section .BTF: -22. Ignored and continue.
TC workaround for mapname: map_ifindex_type map_fd:7

The solution found on stackoverflow is:
xdp-project/xdp-tutorial#38 (comment)

and

Try to compile with the following flags: -g -c -O2
With Clang 8.0 this (the -O2 flag) solved the problem.

Second solution:

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@xxxxxxxxxx/

Maybe libbpf should be also compiled from source? There are many changes from 0.5 to 0.8 (not only this warning).

[interduo]

I tested it - if I get libbfp0 from ubuntu 22.10 there is no such error. So I leave a decision for main boss what to do with this issue.

[rchac]

So with libbfp0 from ubuntu 22.10 it doesn't do this?

[interduo]

Unfortunetly no - and in version libbpf 0.8 there are more errors like:

libbpf: map 'map_txq_config' (legacy): legacy map definitions are deprecated, use BTF-defined maps instead
libbpf: Use of BPF_ANNOTATE_KV_PAIR is deprecated, use BTF-defined maps in .maps section instead
libbpf: map 'map_ifindex_type' (legacy): legacy map definitions are deprecated, use BTF-defined maps instead
libbpf: Use of BPF_ANNOTATE_KV_PAIR is deprecated, use BTF-defined maps in .maps section instead
libbpf: map 'map_ip_hash' (legacy): legacy map definitions are deprecated, use BTF-defined maps instead
libbpf: Use of BPF_ANNOTATE_KV_PAIR is deprecated, use BTF-defined maps in .maps section instead
libbpf: map 'map_txq_config' (legacy): legacy map definitions are deprecated, use BTF-defined maps instead
libbpf: Use of BPF_ANNOTATE_KV_PAIR is deprecated, use BTF-defined maps in .maps section instead
libbpf: map 'map_ifindex_type' (legacy): legacy map definitions are deprecated, use BTF-defined maps instead
libbpf: Use of BPF_ANNOTATE_KV_PAIR is deprecated, use BTF-defined maps in .maps section instead
libbpf: map 'map_ip_hash' (legacy): legacy map definitions are deprecated, use BTF-defined maps instead
libbpf: Use of BPF_ANNOTATE_KV_PAIR is deprecated, use BTF-defined maps in .maps section instead

Maybe something needs to be recompiled with libbpf0-dev 0.8 version?

[rchac]

Gotcha. Since the libbpf library is under xdp-cpumap-tc it may be necessary to make a change in xdp-cpumap-tc to avoid these errors with more modern libbpf versions.

[interduo]

You are right so I did: libbpf/libbpf#580

[interduo]

Look at libbpf github header:
Please use this Github repository for building and packaging libbpf and when using it in your projects through Git submodule.

[interduo]

@rchac maybe You should add libbfp1 as a dependancy in wiki instruction (newest LTS of ubuntu uses obsolette 0.5) ?
(You probbably need to recompile xdp-cpumap-tc with new lib and remove this package from system if is installed by default)

[rchac]

@rchac maybe You should add libbfp1 as a dependancy in wiki instruction (newest LTS of ubuntu uses obsolette 0.5) ?
(You probbably need to recompile xdp-cpumap-tc with new lib and remove this package from system if is installed by default)

Tried removing libbpf0 but it breaks the OS (many things depend on it apparently).

I thought xdp-cpumap-tc just loaded the libbpf version it includes in it's directory. But when I tried that, I couldn't get xdp redirect to actually work. How did you manage to get it working?

[interduo]

I do very dirty force upgrade using package libbpg1 from other ubuntu to test that and remove libbpf0.

[rchac]

I was able to figure it out. Installing 22.04 from scratch, and following the Wiki step-by-step works. I think it may have been that I installed libbpf from a bad package at some point a while ago on this particular machine. I use a mellanox card, and at one step during the ubuntu install it asks whether to install drivers for Mellanox/Intel. I chose yes this time. That may have helped. It should not be necessary to remove libbpf0.

[interduo]

This warning no more occurs with libbpf1.0 on master state.