On Tue, Jan 30, 2024 at 9:30 PM Yonghong Song <yonghong.song@xxxxxxxxx> wrote:
>
>
> On 1/30/24 11:36 AM, Andrii Nakryiko wrote:
> > Seems like original commit adding split BTF support intended to add
> > btf__new_split() API, and even declared it in libbpf.map, but never
> > added (trivial) implementation. Fix this.
> >
> > Fixes: ba451366bf44 ("libbpf: Implement basic split BTF support")
> > Signed-off-by: Andrii Nakryiko <andrii@xxxxxxxxxx>
>
> The patch LGTM. We did some cross checking between libbpf.map
> and the implementation. What things are missing here to
> capture missed implementation or LIBBPF_API marking?
Yes, we still have it, and it does detect issues when API wasn't added
into libbpf.map.
I haven't investigated exactly why it didn't catch the issue when API
is in libbpf.map, but is not marked with LIBBPF_API, but I suspect
it's because existing check doesn't take into account visibility of
the symbol, so there is some room for improvement.
Similarly, not sure why it didn't detect that btf_ext__new_split()
wasn't even implemented, probably because we don't distinguish UNDEF
and FUNC symbols? So something to follow up on for sure.
>
> Acked-by: Yonghong Song <yonghong.song@xxxxxxxxx>
>
> > ---
> > tools/lib/bpf/btf.c | 5 +++++
> > tools/lib/bpf/libbpf.map | 3 ++-
> > 2 files changed, 7 insertions(+), 1 deletion(-)
> >
> > diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c
> > index 95db88b36cf3..845034d15420 100644
> > --- a/tools/lib/bpf/btf.c
> > +++ b/tools/lib/bpf/btf.c
> > @@ -1079,6 +1079,11 @@ struct btf *btf__new(const void *data, __u32 size)
> > return libbpf_ptr(btf_new(data, size, NULL));
> > }
> >
> > +struct btf *btf__new_split(const void *data, __u32 size, struct btf *base_btf)
> > +{
> > + return libbpf_ptr(btf_new(data, size, base_btf));
> > +}
> > +
> > static struct btf *btf_parse_elf(const char *path, struct btf *base_btf,
> > struct btf_ext **btf_ext)
> > {
> > diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map
> > index d9e1f57534fa..386964f572a8 100644
> > --- a/tools/lib/bpf/libbpf.map
> > +++ b/tools/lib/bpf/libbpf.map
> > @@ -245,7 +245,6 @@ LIBBPF_0.3.0 {
> > btf__parse_raw_split;
> > btf__parse_split;
> > btf__new_empty_split;
> > - btf__new_split;
> > ring_buffer__epoll_fd;
> > } LIBBPF_0.2.0;
> >
> > @@ -411,5 +410,7 @@ LIBBPF_1.3.0 {
> > } LIBBPF_1.2.0;
> >
> > LIBBPF_1.4.0 {
> > + global:
> > bpf_token_create;
> > + btf__new_split;
> > } LIBBPF_1.3.0;
