libbpf: Fix CO-RE relocs against .text section (9c82a63c) · Commits · 戴 / test

bpf_object__find_program_by_title(), used by CO-RE relocation code, doesn't return .text "BPF program", if it is a function storage for sub-programs. Because of that, any CO-RE relocation in helper non-inlined functions will fail. Fix this by searching for .text-corresponding BPF program manually. Adjust one of bpf_iter selftest to exhibit this pattern. Fixes: ("libbpf: implement BPF CO-RE offset relocation algorithm") Reported-by:

Yonghong Song <yhs@fb.com> Signed-off-by:

Andrii Nakryiko <andriin@fb.com> Signed-off-by:

Yonghong Song <yhs@fb.com> Signed-off-by:

Alexei Starovoitov <ast@kernel.org> Acked-by:

Yonghong Song <yhs@fb.com> Link: https://lore.kernel.org/bpf/20200619230423.691274-1-andriin@fb.com

tools/lib/bpf/libbpf.c

+7 −1

Original line number	Diff line number	Diff line
		@@ -4818,7 +4818,13 @@ bpf_core_reloc_fields(struct bpf_object obj, const char targ_btf_path)
		err = -EINVAL;
		goto out;
		}
		prog = bpf_object__find_program_by_title(obj, sec_name);
		prog = NULL;
		for (i = 0; i < obj->nr_programs; i++) {
		if (!strcmp(obj->programs[i].section_name, sec_name)) {
		prog = &obj->programs[i];
		break;
		}
		}
		if (!prog) {
		pr_warn("failed to find program '%s' for CO-RE offset relocation\n",
		sec_name);

tools/testing/selftests/bpf/progs/bpf_iter_netlink.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -25,7 +25,7 @@ struct bpf_iter__netlink {
		struct netlink_sock *sk;
		} __attribute__((preserve_access_index));

		static inline struct inode SOCK_INODE(struct socket socket)
		static __attribute__((noinline)) struct inode SOCK_INODE(struct socket socket)
		{
		return &container_of(socket, struct socket_alloc, socket)->vfs_inode;
		}

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