From d82a532a611572d85fd2610ec41b5c9e222931b6 Mon Sep 17 00:00:00 2001 From: Yonghong Song Date: Wed, 30 Sep 2020 22:13:39 -0700 Subject: bpf: Fix "unresolved symbol" build error with resolve_btfids Michal reported a build failure likes below: BTFIDS vmlinux FAILED unresolved symbol tcp_timewait_sock make[1]: *** [/.../linux-5.9-rc7/Makefile:1176: vmlinux] Error 255 This error can be triggered when config has CONFIG_NET enabled but CONFIG_INET disabled. In this case, there is no user of istructs inet_timewait_sock and tcp_timewait_sock and hence vmlinux BTF types are not generated for these two structures. To fix the problem, let us force BTF generation for these two structures with BTF_TYPE_EMIT. Fixes: fce557bcef11 ("bpf: Make btf_sock_ids global") Reported-by: Michal Kubecek Signed-off-by: Yonghong Song Signed-off-by: Daniel Borkmann Acked-by: Martin KaFai Lau Link: https://lore.kernel.org/bpf/20201001051339.2549085-1-yhs@fb.com --- net/core/filter.c | 6 ++++++ 1 file changed, 6 insertions(+) (limited to 'net/core') diff --git a/net/core/filter.c b/net/core/filter.c index 21eaf3b182f2..b5f3faac5e3b 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -9558,6 +9558,12 @@ const struct bpf_func_proto bpf_skc_to_tcp_sock_proto = { BPF_CALL_1(bpf_skc_to_tcp_timewait_sock, struct sock *, sk) { + /* BTF types for tcp_timewait_sock and inet_timewait_sock are not + * generated if CONFIG_INET=n. Trigger an explicit generation here. + */ + BTF_TYPE_EMIT(struct inet_timewait_sock); + BTF_TYPE_EMIT(struct tcp_timewait_sock); + #ifdef CONFIG_INET if (sk && sk->sk_prot == &tcp_prot && sk->sk_state == TCP_TIME_WAIT) return (unsigned long)sk; -- cgit v1.2.3