On Fri, Mar 22, 2024 at 6:37 AM Tao Chen <chen.dylane@xxxxxxxxx> wrote: > > Hi, Nakryiko, thank you for your reply. I try to familiarize with core > in libbpf, the debug info is really helpful for me. But i use the old > kernel btf, so origion debuginfo like: > struct task_struct___x: found target candidate [130] struct > task_struct in [vmlinux] the idea here is to not emit path to BTF (otherwise we normally should emit [/sys/kernel/btf/vmlinux], but rather distinguish whether it's a kernel BTF ([vmlinux]) or some kernel module BTF ([<module-name>]). In your case you are overriding vmlinux BTF by using btf_custom_path option (so you should know where to find it, if you need to debug something). It's still, conceptually, a [vmlinux], and I'd like to keep it this way. > I think it may be more clear, if we print btf name when we use old > kernel btf like: > struct task_struct___x: found target candidate [130] struct > task_struct in [/boot/***.btf] > The patch just solve debug info show for newbies above. > > 在 2024/3/22 上午2:52, Andrii Nakryiko 写道: > > On Thu, Mar 21, 2024 at 10:04 AM Tao Chen <chen.dylane@xxxxxxxxx> wrote: > >> > >> No logic changed, just add specific btf name when core info > >> print, maybe it seems more understandable. > >> > >> Signed-off-by: Tao Chen <chen.dylane@xxxxxxxxx> > >> --- > >> tools/lib/bpf/libbpf.c | 14 +++++++++----- > >> 1 file changed, 9 insertions(+), 5 deletions(-) > >> > > > > Can you elaborate on what problem you are trying to solve? > > Conceptually libbpf does look for types in vmlinux (meaning main > > kernel BTF), even if user overrides BTF location (presumably because > > of old kernel). So even when we emit "vmlinux" in logs, it seems > > correct. > > > > pw-bot: cr > > > > > >> diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c > >> index afd09571c482..b32154288b4a 100644 > >> --- a/tools/lib/bpf/libbpf.c > >> +++ b/tools/lib/bpf/libbpf.c > >> @@ -5653,7 +5653,8 @@ static int load_module_btfs(struct bpf_object *obj) > >> } > >> > >> static struct bpf_core_cand_list * > >> -bpf_core_find_cands(struct bpf_object *obj, const struct btf *local_btf, __u32 local_type_id) > >> +bpf_core_find_cands(struct bpf_object *obj, const struct btf *local_btf, __u32 local_type_id, > >> + const char *targ_btf_path) > >> { > >> struct bpf_core_cand local_cand = {}; > >> struct bpf_core_cand_list *cands; > >> @@ -5680,7 +5681,8 @@ bpf_core_find_cands(struct bpf_object *obj, const struct btf *local_btf, __u32 l > >> > >> /* Attempt to find target candidates in vmlinux BTF first */ > >> main_btf = obj->btf_vmlinux_override ?: obj->btf_vmlinux; > >> - err = bpf_core_add_cands(&local_cand, local_essent_len, main_btf, "vmlinux", 1, cands); > >> + err = bpf_core_add_cands(&local_cand, local_essent_len, main_btf, > >> + targ_btf_path ?: "vmlinux", 1, cands); > >> if (err) > >> goto err_out; > >> > >> @@ -5793,7 +5795,8 @@ static int bpf_core_resolve_relo(struct bpf_program *prog, > >> int relo_idx, > >> const struct btf *local_btf, > >> struct hashmap *cand_cache, > >> - struct bpf_core_relo_res *targ_res) > >> + struct bpf_core_relo_res *targ_res, > >> + const char *targ_btf_path) > >> { > >> struct bpf_core_spec specs_scratch[3] = {}; > >> struct bpf_core_cand_list *cands = NULL; > >> @@ -5813,7 +5816,7 @@ static int bpf_core_resolve_relo(struct bpf_program *prog, > >> > >> if (relo->kind != BPF_CORE_TYPE_ID_LOCAL && > >> !hashmap__find(cand_cache, local_id, &cands)) { > >> - cands = bpf_core_find_cands(prog->obj, local_btf, local_id); > >> + cands = bpf_core_find_cands(prog->obj, local_btf, local_id, targ_btf_path); > >> if (IS_ERR(cands)) { > >> pr_warn("prog '%s': relo #%d: target candidate search failed for [%d] %s %s: %ld\n", > >> prog_name, relo_idx, local_id, btf_kind_str(local_type), > >> @@ -5920,7 +5923,8 @@ bpf_object__relocate_core(struct bpf_object *obj, const char *targ_btf_path) > >> if (prog->obj->gen_loader) > >> continue; > >> > >> - err = bpf_core_resolve_relo(prog, rec, i, obj->btf, cand_cache, &targ_res); > >> + err = bpf_core_resolve_relo(prog, rec, i, obj->btf, cand_cache, &targ_res, > >> + targ_btf_path); > >> if (err) { > >> pr_warn("prog '%s': relo #%d: failed to relocate: %d\n", > >> prog->name, i, err); > >> -- > >> 2.34.1 > >>