BTF load error

[KfreeZ]

hi,
I am trying your code, but encounter an error like below:

+ sudo bpftool prog load bpf_sockops_v4.o /sys/fs/bpf/bpf_sockops
libbpf: Error loading BTF: Invalid argument(22)
libbpf: magic: 0xeb9f
version: 1
flags: 0x0
hdr_len: 24
type_off: 0
type_len: 952
str_off: 952
str_len: 1192
btf_total_size: 2168
[1] PTR (anon) type_id=2
[2] STRUCT bpf_sock_ops size=192 vlen=36
        op type_id=3 bits_offset=0
        (anon) type_id=5 bits_offset=32
        family type_id=3 bits_offset=160
        remote_ip4 type_id=3 bits_offset=192
        local_ip4 type_id=3 bits_offset=224
        remote_ip6 type_id=6 bits_offset=256
        local_ip6 type_id=6 bits_offset=384
        remote_port type_id=3 bits_offset=512
        local_port type_id=3 bits_offset=544
        is_fullsock type_id=3 bits_offset=576
        snd_cwnd type_id=3 bits_offset=608
        srtt_us type_id=3 bits_offset=640
        bpf_sock_ops_cb_flags type_id=3 bits_offset=672
        state type_id=3 bits_offset=704
        rtt_min type_id=3 bits_offset=736
        snd_ssthresh type_id=3 bits_offset=768
        rcv_nxt type_id=3 bits_offset=800
        snd_nxt type_id=3 bits_offset=832
        snd_una type_id=3 bits_offset=864
        mss_cache type_id=3 bits_offset=896
        ecn_flags type_id=3 bits_offset=928
        rate_delivered type_id=3 bits_offset=960
        rate_interval_us type_id=3 bits_offset=992
        packets_out type_id=3 bits_offset=1024
        retrans_out type_id=3 bits_offset=1056
        total_retrans type_id=3 bits_offset=1088
        segs_in type_id=3 bits_offset=1120
        data_segs_in type_id=3 bits_offset=1152
        segs_out type_id=3 bits_offset=1184
        data_segs_out type_id=3 bits_offset=1216
        lost_out type_id=3 bits_offset=1248
        sacked_out type_id=3 bits_offset=1280
        sk_txhash type_id=3 bits_offset=1312
        bytes_received type_id=8 bits_offset=1344
        bytes_acked type_id=8 bits_offset=1408
        (anon) type_id=10 bits_offset=1472
[3] TYPEDEF __u32 type_id=4
[4] INT unsigned int size=4 bits_offset=0 nr_bits=32 encoding=(none)
[5] UNION (anon) size=16 vlen=3
        args type_id=6 bits_offset=0
        reply type_id=3 bits_offset=0
        replylong type_id=6 bits_offset=0
[6] ARRAY (anon) type_id=3 index_type_id=7 nr_elems=4
[7] INT __ARRAY_SIZE_TYPE__ size=4 bits_offset=0 nr_bits=32 encoding=(none)
[8] TYPEDEF __u64 type_id=9
[9] INT long long unsigned int size=8 bits_offset=0 nr_bits=64 encoding=(none)
[10] UNION (anon) size=8 vlen=1
        sk type_id=11 bits_offset=0
[11] PTR (anon) type_id=26
[12] FUNC_PROTO (anon) return=13 args=(1 skops)
[13] INT int size=4 bits_offset=0 nr_bits=32 encoding=SIGNED
[14] FUNC bpf_sockops_v4 type_id=12 vlen != 0

libbpf: Error loading .BTF into kernel: -22.
libbpf: bad map relo against section 5
Error: failed to open object file

I have debugged for days, but still don't pass the BTF load, I have checked below conditions, can you help to see where is wrong? Thanks in advance.

[root@centos8-worker3 sockredir]# clang --version
clang version 11.0.0 (https://github.com/llvm/llvm-project.git 176249bd6732a8044d457092ed932768724a6f06)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /usr/local/bin


[root@centos8-worker3 sockredir]# llc --version
LLVM (http://llvm.org/):
  LLVM version 11.0.0
  DEBUG build with assertions.
  Default target: x86_64-unknown-linux-gnu
  Host CPU: cascadelake

[root@centos8-worker3 sockredir]# ip -V
ip utility, iproute2-5.8.0

[root@centos8-worker3 sockredir]# uname -r
4.18.0-193.19.1.el8_2.x86_64

// also tried built a new kernel 5.4.77, same result

the built object's sections is like below:

[root@centos8-worker3 sockredir]# readelf -S bpf_sockops_v4.o
There are 25 section headers, starting at offset 0x3200:

Section Headers:
  [Nr] Name              Type             Address           Offset
       Size              EntSize          Flags  Link  Info  Align
  [ 0]                   NULL             0000000000000000  00000000
       0000000000000000  0000000000000000           0     0     0
  [ 1] .strtab           STRTAB           0000000000000000  000030e1
       000000000000011f  0000000000000000           0     0     1
  [ 2] .text             PROGBITS         0000000000000000  00000040
       0000000000000000  0000000000000000  AX       0     0     4
  [ 3] "sockops"         PROGBITS         0000000000000000  00000040
       0000000000000268  0000000000000000  AX       0     0     8
  [ 4] .rel"sockops"     REL              0000000000000000  00002720
       0000000000000010  0000000000000010          24     3     8
  [ 5] "maps"            PROGBITS         0000000000000000  000002a8
       0000000000000014  0000000000000000  WA       0     0     4
  [ 6] "license"         PROGBITS         0000000000000000  000002bc
       0000000000000004  0000000000000000  WA       0     0     1
  [ 7] "version"         PROGBITS         0000000000000000  000002c0
       0000000000000004  0000000000000000  WA       0     0     4
  [ 8] .rodata.str1.1    PROGBITS         0000000000000000  000002c4
       0000000000000044  0000000000000001 AMS       0     0     1
  [ 9] .debug_loc        PROGBITS         0000000000000000  00000308
       00000000000000c2  0000000000000000           0     0     1
  [10] .debug_abbrev     PROGBITS         0000000000000000  000003ca
       00000000000001b4  0000000000000000           0     0     1
  [11] .debug_info       PROGBITS         0000000000000000  0000057e
       0000000000000649  0000000000000000           0     0     1
  [12] .rel.debug_info   REL              0000000000000000  00002730
       00000000000007c0  0000000000000010          24    11     8
  [13] .debug_ranges     PROGBITS         0000000000000000  00000bc7
       0000000000000030  0000000000000000           0     0     1
  [14] .debug_str        PROGBITS         0000000000000000  00000bf7
       0000000000000428  0000000000000001  MS       0     0     1
  [15] .BTF              PROGBITS         0000000000000000  0000101f
       0000000000000878  0000000000000000           0     0     1
  [16] .rel.BTF          REL              0000000000000000  00002ef0
       0000000000000030  0000000000000010          24    15     8
  [17] .BTF.ext          PROGBITS         0000000000000000  00001897
       00000000000001c0  0000000000000000           0     0     1
  [18] .rel.BTF.ext      REL              0000000000000000  00002f20
       0000000000000190  0000000000000010          24    17     8
  [19] .debug_frame      PROGBITS         0000000000000000  00001a58
       0000000000000028  0000000000000000           0     0     8
  [20] .rel.debug_frame  REL              0000000000000000  000030b0
       0000000000000020  0000000000000010          24    19     8
  [21] .debug_line       PROGBITS         0000000000000000  00001a80
       000000000000021a  0000000000000000           0     0     1
  [22] .rel.debug_line   REL              0000000000000000  000030d0
       0000000000000010  0000000000000010          24    21     8
  [23] .llvm_addrsig     LOOS+0xfff4c03   0000000000000000  000030e0
       0000000000000001  0000000000000000   E      24     0     1
  [24] .symtab           SYMTAB           0000000000000000  00001ca0
       0000000000000a80  0000000000000018           1   108     8
Key to Flags:
  W (write), A (alloc), X (execute), M (merge), S (strings), I (info),
  L (link order), O (extra OS processing required), G (group), T (TLS),
  C (compressed), x (unknown), o (OS specific), E (exclude),
  p (processor specific)

[KfreeZ]

I install all these things on an ubuntu20.10 and without bcc/libbpf, the code works well, close this issue