2 Commits

Author	SHA1	Message	Date
Kumar Kartikeya Dwivedi	087cba799c	selftests/bpf: Add weak/typeless ksym test for light skeleton ... Also, avoid using CO-RE features, as lskel doesn't support CO-RE, yet. Include both light and libbpf skeleton in same file to test both of them together. In c48e51c8b07a ("bpf: selftests: Add selftests for module kfunc support"), I added support for generating both lskel and libbpf skel for a BPF object, however the name parameter for bpftool caused collisions when included in same file together. This meant that every test needed a separate file for a libbpf/light skeleton separation instead of subtests. Change that by appending a "_lskel" suffix to the name for files using light skeleton, and convert all existing users. Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20211028063501.2239335-7-memxor@gmail.com	2021-10-28 16:30:07 -07:00
Hao Luo	2211c825e7	libbpf: Support weak typed ksyms. ... Currently weak typeless ksyms have default value zero, when they don't exist in the kernel. However, weak typed ksyms are rejected by libbpf if they can not be resolved. This means that if a bpf object contains the declaration of a nonexistent weak typed ksym, it will be rejected even if there is no program that references the symbol. Nonexistent weak typed ksyms can also default to zero just like typeless ones. This allows programs that access weak typed ksyms to be accepted by verifier, if the accesses are guarded. For example, extern const int bpf_link_fops3 __ksym __weak; /* then in BPF program */ if (&bpf_link_fops3) { /* use bpf_link_fops3 */ } If actual use of nonexistent typed ksym is not guarded properly, verifier would see that register is not PTR_TO_BTF_ID and wouldn't allow to use it for direct memory reads or passing it to BPF helpers. Signed-off-by: Hao Luo <haoluo@google.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20210812003819.2439037-1-haoluo@google.com	2021-08-13 15:56:28 -07:00