libbpf: Do not resolve size on duplicate FUNCs

FUNCs do not have sizes, thus currently btf__resolve_size will fail
with -EINVAL. Add conditions so that we only update size when the BTF
object is not function or function prototype.

Signed-off-by: Eric Long <i@hack3r.moe>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20241002-libbpf-dup-extern-funcs-v4-1-560eb460ff90@hack3r.moe

diff --git a/tools/lib/bpf/linker.c b/tools/lib/bpf/linker.c
index 81dbbdd79a7c65a4b048b85e1dba99cb5f7cb56b..f83c1c29982c3d9d7f6775cd98a6f3387a4e9c50 100644 (file)
--- a/tools/lib/bpf/linker.c
+++ b/tools/lib/bpf/linker.c
@@ -2451,6 +2451,10 @@ static int linker_append_btf(struct bpf_linker *linker, struct src_obj *obj)
                        if (glob_sym && glob_sym->var_idx >= 0) {
                                __s64 sz;
 
+                               /* FUNCs don't have size, nothing to update */
+                               if (btf_is_func(t))
+                                       continue;
+
                                dst_var = &dst_sec->sec_vars[glob_sym->var_idx];
                                /* Because underlying BTF type might have
                                 * changed, so might its size have changed, so