diff mbox series

[bpf-next,2/2] selftests/bpf: add subprog to BPF object file with no entry programs

Message ID 20241010211731.4121837-2-andrii@kernel.org (mailing list archive)
State New
Delegated to: BPF
Headers show
Series [bpf-next,1/2] libbpf: never interpret subprogs in .text as entry programs | expand

Checks

Context Check Description
bpf/vmtest-bpf-next-PR success PR summary
netdev/series_format success Single patches do not need cover letters
netdev/tree_selection success Clearly marked for bpf-next
netdev/ynl success Generated files up to date; no warnings/errors; no diff in generated;
netdev/fixes_present success Fixes tag not required for -next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 5 this patch: 5
netdev/build_tools success Errors and warnings before: 0 (+1) this patch: 0 (+1)
netdev/cc_maintainers warning 12 maintainers not CCed: song@kernel.org shuah@kernel.org haoluo@google.com mykolal@fb.com yonghong.song@linux.dev john.fastabend@gmail.com sdf@fomichev.me martin.lau@linux.dev kpsingh@kernel.org linux-kselftest@vger.kernel.org eddyz87@gmail.com jolsa@kernel.org
netdev/build_clang success Errors and warnings before: 5 this patch: 5
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/deprecated_api success None detected
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success No Fixes tag
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Commit Message

Andrii Nakryiko Oct. 10, 2024, 9:17 p.m. UTC 
Add a subprogram to BPF object file that otherwise has no entry BPF
programs to validate that libbpf can still load this correctly.

Until this was fixed, user could expect this very confusing error message:

  libbpf: prog 'dangling_subprog': missing BPF prog type, check ELF section name '.text'
  libbpf: prog 'dangling_subprog': failed to load: -22
  libbpf: failed to load object 'struct_ops_detach'
  libbpf: failed to load BPF skeleton 'struct_ops_detach': -22

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
---
 tools/testing/selftests/bpf/progs/struct_ops_detach.c | 6 ++++++
 1 file changed, 6 insertions(+)

Comments

Andrii Nakryiko Oct. 10, 2024, 9:22 p.m. UTC | #1 
On Thu, Oct 10, 2024 at 2:17 PM Andrii Nakryiko <andrii@kernel.org> wrote:
>
> Add a subprogram to BPF object file that otherwise has no entry BPF
> programs to validate that libbpf can still load this correctly.
>
> Until this was fixed, user could expect this very confusing error message:
>
>   libbpf: prog 'dangling_subprog': missing BPF prog type, check ELF section name '.text'
>   libbpf: prog 'dangling_subprog': failed to load: -22
>   libbpf: failed to load object 'struct_ops_detach'
>   libbpf: failed to load BPF skeleton 'struct_ops_detach': -22
>
> Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
> ---
>  tools/testing/selftests/bpf/progs/struct_ops_detach.c | 6 ++++++
>  1 file changed, 6 insertions(+)
>
> diff --git a/tools/testing/selftests/bpf/progs/struct_ops_detach.c b/tools/testing/selftests/bpf/progs/struct_ops_detach.c
> index 56b787a89876..5222d58592a7 100644
> --- a/tools/testing/selftests/bpf/progs/struct_ops_detach.c
> +++ b/tools/testing/selftests/bpf/progs/struct_ops_detach.c
> @@ -6,5 +6,11 @@
>
>  char _license[] SEC("license") = "GPL";
>

argh, I had this comment here, which I missed to amend into this
patch, maybe whoever applies can just add it so I don't spam the
mailing list:

/* This subprogram validates that libbpf handles the situation in which BPF
 * object has subprograms in .text section, but has no entry BPF programs.
 * At some point that was causing issues due to legacy logic of treating such
 * subprogram as entry program (with unknown program type, which would fail).
 */
> +int dangling_subprog(void)
> +{
> +       /* do nothing, just be here */
> +       return 0;
> +}
> +
>  SEC(".struct_ops.link")
>  struct bpf_testmod_ops testmod_do_detach;
> --
> 2.43.5
>
diff mbox series

Patch

diff --git a/tools/testing/selftests/bpf/progs/struct_ops_detach.c b/tools/testing/selftests/bpf/progs/struct_ops_detach.c
index 56b787a89876..5222d58592a7 100644
--- a/tools/testing/selftests/bpf/progs/struct_ops_detach.c
+++ b/tools/testing/selftests/bpf/progs/struct_ops_detach.c
@@ -6,5 +6,11 @@ 
 
 char _license[] SEC("license") = "GPL";
 
+int dangling_subprog(void)
+{
+	/* do nothing, just be here */
+	return 0;
+}
+
 SEC(".struct_ops.link")
 struct bpf_testmod_ops testmod_do_detach;