Trouble running bpf_iter tests

[Lorenz Bauer <lmb@xxxxxxxxxxxxxx>]

For some reason the initial e-mail wasn't plain text, apologies.

---------- Forwarded message ---------
From: Lorenz Bauer <lmb@xxxxxxxxxxxxxx>
Date: Mon, 1 Jun 2020 at 15:32
Subject: Trouble running bpf_iter tests
To: Yonghong Song <yhs@xxxxxx>, bpf <bpf@xxxxxxxxxxxxxxx>
Cc: kernel-team <kernel-team@xxxxxxxxxxxxxx>


Hi Yonghong,

I'm having trouble running the bpf_iter tests on bpf-next at 551f08b1d8eadbc.
On a freshly built kernel running in a VM I get the following:

    root@vm:/home/lorenz/dev/bpf-next/tools/testing/selftests/bpf#
./test_progs -t bpf_iter
510 bits_offset=640
    #3/1 btf_id_or_null:OK
    libbpf: failed to open system Kconfig
    libbpf: failed to load object 'bpf_iter_ipv6_route'
    libbpf: failed to load BPF skeleton 'bpf_iter_ipv6_route': -22
    test_ipv6_route:FAIL:bpf_iter_ipv6_route__open_and_load skeleton
open_and_load failed1510 bits_offset=1024
    #3/2 ipv6_route:FAIL
    libbpf: netlink is not found in vmlinux BTF
    libbpf: failed to load object 'bpf_iter_netlink'
    libbpf: failed to load BPF skeleton 'bpf_iter_netlink': -2
    test_netlink:FAIL:bpf_iter_netlink__open_and_load skeleton
open_and_load failed1510 bits_offset=1408
    #3/3 netlink:FAIL
    libbpf: bpf_map is not found in vmlinux BTF
    libbpf: failed to load object 'bpf_iter_bpf_map'
    libbpf: failed to load BPF skeleton 'bpf_iter_bpf_map': -2
    test_bpf_map:FAIL:bpf_iter_bpf_map__open_and_load skeleton
open_and_load failed
    #3/4 bpf_map:FAIL
    ....
    #3 bpf_iter:FAIL
    Summary: 0/1 PASSED, 0 SKIPPED, 12 FAILED

If I understand correctly, this is because there is no function
information for bpf_iter_bpf_map
present in my /sys/kernel/btf/vmlinux:

    # ./bpftool btf dump file /sys/kernel/btf/vmlinux format raw |
grep bpf_iter_bpf_map
    #

There is an entry in /proc/kallsyms however:

    # grep bpf_iter_bpf_map /proc/kallsyms
    ffffffff826b2f13 T bpf_iter_bpf_map

And other bpf_iter related symbols are available in BTF:

    # ./bpftool btf dump file /sys/kernel/btf/vmlinux format raw |
grep bpf_iter_
    [12602] TYPEDEF 'bpf_iter_init_seq_priv_t' type_id=9310
    [12603] TYPEDEF 'bpf_iter_fini_seq_priv_t' type_id=352
    [12604] STRUCT 'bpf_iter_reg' size=56 vlen=7
    [12608] STRUCT 'bpf_iter_meta' size=24 vlen=3
    [12609] STRUCT 'bpf_iter_target_info' size=32 vlen=3
    [12611] STRUCT 'bpf_iter_link' size=72 vlen=2
    [12613] STRUCT 'bpf_iter_priv_data' size=40 vlen=6
    [12617] STRUCT 'bpf_iter_seq_map_info' size=4 vlen=1
    [12620] STRUCT 'bpf_iter__bpf_map' size=16 vlen=2
    [12622] STRUCT 'bpf_iter_seq_task_common' size=8 vlen=1
    [12623] STRUCT 'bpf_iter_seq_task_info' size=16 vlen=2
    [12625] STRUCT 'bpf_iter__task' size=16 vlen=2
    [12626] STRUCT 'bpf_iter_seq_task_file_info' size=32 vlen=5
    [12628] STRUCT 'bpf_iter__task_file' size=32 vlen=4
    [25591] STRUCT 'bpf_iter__netlink' size=16 vlen=2
    [27509] STRUCT 'bpf_iter__ipv6_route' size=16 vlen=2

Can you help me make this work?

Thanks
Lorenz

-- 
Lorenz Bauer  |  Systems Engineer
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