resolve_btfids prints a warning when it finds an unresolved symbol, (id == 0) in id_patch. This can be the case for BTF sets that are empty (due to disabled config options), hence printing warnings for certain builds, most recently seen in [0]. The reason behind this is because id->cnt aliases id->id in btf_id struct, leading to empty set showing up as ID 0 when we get to id_patch, which triggers the warning. Since sets are an exception here, accomodate by reusing hole in btf_id for bool is_set member, setting it to true for BTF set when setting id->cnt, and use that to skip extraneous warning. [0]: https://lore.kernel.org/all/1b99ae14-abb4-d18f-cc6a-d7e523b25542@xxxxxxxxx Before: ; ./tools/bpf/resolve_btfids/resolve_btfids -v -b vmlinux net/ipv4/tcp_cubic.ko adding symbol tcp_cubic_kfunc_ids WARN: resolve_btfids: unresolved symbol tcp_cubic_kfunc_ids patching addr 0: ID 0 [tcp_cubic_kfunc_ids] sorting addr 4: cnt 0 [tcp_cubic_kfunc_ids] update ok for net/ipv4/tcp_cubic.ko After: ; ./tools/bpf/resolve_btfids/resolve_btfids -v -b vmlinux net/ipv4/tcp_cubic.ko adding symbol tcp_cubic_kfunc_ids patching addr 0: ID 0 [tcp_cubic_kfunc_ids] sorting addr 4: cnt 0 [tcp_cubic_kfunc_ids] update ok for net/ipv4/tcp_cubic.ko Cc: Jiri Olsa <jolsa@xxxxxxxxxx> Fixes: 0e32dfc80bae ("bpf: Enable TCP congestion control kfunc from modules") Reported-by: Pavel Skripkin <paskripkin@xxxxxxxxx> Signed-off-by: Kumar Kartikeya Dwivedi <memxor@xxxxxxxxx> --- tools/bpf/resolve_btfids/main.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/tools/bpf/resolve_btfids/main.c b/tools/bpf/resolve_btfids/main.c index a59cb0ee609c..73409e27be01 100644 --- a/tools/bpf/resolve_btfids/main.c +++ b/tools/bpf/resolve_btfids/main.c @@ -83,6 +83,7 @@ struct btf_id { int cnt; }; int addr_cnt; + bool is_set; Elf64_Addr addr[ADDR_CNT]; }; @@ -451,8 +452,10 @@ static int symbols_collect(struct object *obj) * in symbol's size, together with 'cnt' field hence * that - 1. */ - if (id) + if (id) { id->cnt = sym.st_size / sizeof(int) - 1; + id->is_set = true; + } } else { pr_err("FAILED unsupported prefix %s\n", prefix); return -1; @@ -568,9 +571,8 @@ static int id_patch(struct object *obj, struct btf_id *id) int *ptr = data->d_buf; int i; - if (!id->id) { + if (!id->id && !id->is_set) pr_err("WARN: resolve_btfids: unresolved symbol %s\n", id->name); - } for (i = 0; i < id->addr_cnt; i++) { unsigned long addr = id->addr[i]; -- 2.34.0
