On Sat, 2024-06-15 at 17:29 -0700, Donglin Peng wrote: > I encountered an issue when building the test_progs using the repository[1]: > > $ clang --version > Ubuntu clang version 17.0.6 (++20231208085846+6009708b4367-1~exp1~20231208085949.74) > Target: x86_64-pc-linux-gnu > Thread model: posix > InstalledDir: /usr/bin > > $ pwd > /work/Qemu/x86_64/linux-6.10-rc2/tools/testing/selftests/bpf/ > > $ make test_progs V=1 > ... > /work/Qemu/x86_64/linux-6.10-rc2/tools/testing/selftests/bpf/tools/sbin/bpftool > gen object > /work/Qemu/x86_64/linux-6.10-rc2/tools/testing/selftests/bpf/ip_check_defrag.bpf.linked2.o > /work/Qemu/x86_64/linux-6.10-rc2/tools/testing/selftests/bpf/ip_check_defrag.bpf.linked1.o > libbpf: failed to find symbol for variable 'bpf_dynptr_slice' in section > '.ksyms' > Error: failed to link > '/work/Qemu/x86_64/linux-6.10-rc2/tools/testing/selftests/bpf/ip_check_defrag.bpf.linked1.o': > No such file or directory (2) > make: *** [Makefile:656: > /work/Qemu/x86_64/linux-6.10-rc2/tools/testing/selftests/bpf/ip_check_defrag.skel.h] > Error 254 > > After investigation, I found that the btf_types in the '.ksyms' section have 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 > ... > > To fix this, we can a add check for the kind. > > [1] https://github.com/eddyz87/bpf/tree/binsort-btf-dedup > Link: https://lore.kernel.org/all/4f551dc5fc792936ca364ce8324c0adea38162f1.camel@xxxxxxxxx/ > > Fixes: 8fd27bf69b86 ("libbpf: Add BPF static linker BTF and BTF.ext support") > Signed-off-by: Donglin Peng <dolinux.peng@xxxxxxxxx> > --- Good catch, thank you for narrowing this down. Acked-by: Eduard Zingerman <eddyz87@xxxxxxxxx> (Although, I agree with notes from Alan, having a comment would be good).
