Em Thu, Jun 17, 2021 at 11:48:47AM -0300, Arnaldo Carvalho de Melo escreveu: > Em Wed, Jun 16, 2021 at 03:36:54PM -0700, Andrii Nakryiko escreveu: > > On Wed, Jun 16, 2021 at 1:41 PM Arnaldo Carvalho de Melo <arnaldo.melo@xxxxxxxxx> wrote: > > > And if I use pahole's BTF loader I find the info about that function: > > > [acme@seventh linux]$ strace -e openat -o /tmp/bla pfunct -F btf tcp_cong_avoid_ai ; grep vmlinux /tmp/bla > > > void tcp_cong_avoid_ai(struct tcp_sock * tp, u32 w, u32 acked); > > > openat(AT_FDCWD, "/sys/kernel/btf/vmlinux", O_RDONLY) = 3 > > > So this should be unrelated to the breakage you noticed in the CI. > > > I'm trying to to reproduce the CI breakage by building the kernel and > > > running selftests after a reboot. > > > I suspect I'm missing something, can you see what it is? > > Oh, I didn't realize initially what it is. This is not kernel-related, > > you are right. You just need newer Clang. Can you please use nightly > > version or build from sources? Basically, your Clang is too old and it > > doesn't generate BTF information for extern functions in BPF code. > Oh well, I thought that that clang was new enough, the system being > Fedora rawhide: > [acme@seventh ~]$ clang -v |& head -1 > clang version 12.0.0 (https://github.com/llvm/llvm-project 87369c626114ae17f4c637635c119e6de0856a9a) > I'm now building the single-repo main... So I updated clang and now I'm stumbling on another one, again using pahole 1.21 + fixes, without any of my changes, is this a known issue? [root@seventh bpf]# pwd /mnt/linux/tools/testing/selftests/bpf [root@seventh bpf]# git log --oneline -5 94f0b2d4a1d0 (HEAD -> master, torvalds/master) proc: only require mm_struct for writing a33d62662d27 afs: Fix an IS_ERR() vs NULL check 009c9aa5be65 (tag: v5.13-rc6) Linux 5.13-rc6 e4e453434a19 Merge tag 'perf-tools-fixes-for-v5.13-2021-06-13' of git://git.kernel.org/pub/scm/linux/kernel/git/acme/linux 960f0716d80f Merge tag 'nfs-for-5.13-3' of git://git.linux-nfs.org/projects/trondmy/linux-nfs [root@seventh bpf]# [root@seventh bpf]# make run_tests <SNIP> GEN-SKEL [test_progs] atomic_bounds.skel.h GEN-SKEL [test_progs] atomics.skel.h GEN-SKEL [test_progs] bind4_prog.skel.h libbpf: elf: skipping unrecognized data section(6) .rodata.str1.1 GEN-SKEL [test_progs] bind6_prog.skel.h libbpf: elf: skipping unrecognized data section(6) .rodata.str1.1 GEN-SKEL [test_progs] bind_perm.skel.h GEN-SKEL [test_progs] bpf_cubic.skel.h libbpf: ELF relo #0 in section #15 has unexpected type 2 in /mnt/linux/tools/testing/selftests/bpf/bpf_cubic.o Error: failed to link '/mnt/linux/tools/testing/selftests/bpf/bpf_cubic.o': Unknown error -22 (-22) make: *** [Makefile:456: /mnt/linux/tools/testing/selftests/bpf/bpf_cubic.skel.h] Error 234 [root@seventh bpf]# clang -v |& head -2 clang version 13.0.0 (https://github.com/llvm/llvm-project dee2c76b4c46e71903e3d86ab7555a80d51d1288) Target: x86_64-unknown-linux-gnu [root@seventh bpf]# - Arnaldo > Would you consider a patch for libbpf that would turn this: > > > > > libbpf: failed to find BTF for extern 'tcp_cong_avoid_ai' [27] section: -2 > > > > Error: failed to open BPF object file: No such file or directory > > > > make: *** [Makefile:460: /mnt/linux/tools/testing/selftests/bpf/bpf_cubic.skel.h] Error 255 > > > > make: *** Deleting file '/mnt/linux/tools/testing/selftests/bpf/bpf_cubic.skel.h' > > > > make: Leaving directory '/mnt/linux/tools/testing/selftests/bpf' > > Into: > > libbpf: failed to find BTF for extern 'tcp_cong_avoid_ai' [27] section: -2 > HINT: Please update your clang/llvm toolchain to at least cset abcdef123456 > HINT: That is where clang started generating BTF information for extern functions in BPF code. > > ? > > :-)
