twx-linux/tools/lib
Donglin Peng cc5083d1f3 libbpf: Checking the btf_type kind when fixing variable offsets
I encountered an issue when building the test_progs from the repository [1]:

  $ pwd
  /work/Qemu/x86_64/linux-6.10-rc2/tools/testing/selftests/bpf/

  $ make test_progs V=1
  [...]
  ./tools/sbin/bpftool gen object ./ip_check_defrag.bpf.linked2.o ./ip_check_defrag.bpf.linked1.o
  libbpf: failed to find symbol for variable 'bpf_dynptr_slice' in section '.ksyms'
  Error: failed to link './ip_check_defrag.bpf.linked1.o': No such file or directory (2)
  [...]

Upon investigation, I discovered that the btf_types referenced in the '.ksyms'
section had a kind of BTF_KIND_FUNC instead of BTF_KIND_VAR:

  $ bpftool btf dump file ./ip_check_defrag.bpf.linked1.o
  [...]
  [2] DATASEC '.ksyms' size=0 vlen=2
        type_id=16 offset=0 size=0 (FUNC 'bpf_dynptr_from_skb')
        type_id=17 offset=0 size=0 (FUNC 'bpf_dynptr_slice')
  [...]
  [16] FUNC 'bpf_dynptr_from_skb' type_id=82 linkage=extern
  [17] FUNC 'bpf_dynptr_slice' type_id=85 linkage=extern
  [...]

For a detailed analysis, please refer to [2]. We can add a kind checking to
fix the issue.

  [1] https://github.com/eddyz87/bpf/tree/binsort-btf-dedup
  [2] https://lore.kernel.org/all/0c0ef20c-c05e-4db9-bad7-2cbc0d6dfae7@oracle.com/

Fixes: 8fd27bf69b86 ("libbpf: Add BPF static linker BTF and BTF.ext support")
Signed-off-by: Donglin Peng <dolinux.peng@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Alan Maguire <alan.maguire@oracle.com>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/bpf/20240619122355.426405-1-dolinux.peng@gmail.com
2024-06-21 20:00:17 +02:00
..
api tools api fs: Avoid reading whole file for a 1 byte bool 2023-11-30 19:25:19 -03:00
bpf libbpf: Checking the btf_type kind when fixing variable offsets 2024-06-21 20:00:17 +02:00
perf perf record: Fix comment misspellings 2024-04-26 22:13:10 -03:00
subcmd tools lib subcmd: Show parent options in help 2024-05-12 21:09:52 -03:00
symbol
thermal tools/lib/thermal: Fix include path for libnl3 in pkg-config file. 2023-02-15 17:29:40 +01:00
argv_split.c
bitmap.c
ctype.c
find_bit.c
hweight.c
list_sort.c
rbtree.c tools lib rbtree: pick some improvements from the kernel rbtree code 2024-05-08 08:41:27 -07:00
slab.c
str_error_r.c
string.c
vsprintf.c
zalloc.c