[PATCH bpf-next v8 4/4] selftests/bpf: Add libbpf_probe_bpf_kfunc API selftests

Tao Chen
2025-02-21T16:36:37Z

Add selftests for prog_kfunc feature probing. Thanks for
Eduard providing the libbpf_probe_func_many test case.

./test_progs -t libbpf_probe_kfuncs
#153 libbpf_probe_kfuncs:OK
Summary: 1/0 PASSED, 0 SKIPPED, 0 FAILED

./test_progs -t libbpf_probe_kfuncs_many
#154 libbpf_probe_kfuncs_many:OK
Summary: 1/0 PASSED, 0 SKIPPED, 0 FAILED

Cc: Tao Chen <dylane.chen@didiglobal.com>
Reviewed-by: Jiri Olsa <jolsa@kernel.org>
Co-developed-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Tao Chen <chen.dylane@linux.dev>
---
.../selftests/bpf/prog_tests/libbpf_probes.c | 173 ++++++++++++++++++
1 file changed, 173 insertions(+)

diff --git a/tools/testing/selftests/bpf/prog_tests/libbpf_probes.c b/tools/testing/selftests/bpf/prog_tests/libbpf_probes.c
index 4ed46ed58a7b..db408fd67add 100644
--- a/tools/testing/selftests/bpf/prog_tests/libbpf_probes.c
+++ b/tools/testing/selftests/bpf/prog_tests/libbpf_probes.c
@@ -126,3 +126,176 @@ void test_libbpf_probe_helpers(void)
ASSERT_EQ(res, d->supported, buf);
}
}
+
+static int module_btf_fd(char *module)
+{
+ int fd, err;
+ __u32 id = 0, len;
+ struct bpf_btf_info info;
+ char name[64];
+
+ while (true) {
+ err = bpf_btf_get_next_id(id, &id);
+ if (err)
+ return -1;
+
+ fd = bpf_btf_get_fd_by_id(id);
+ if (fd < 0) {
+ if (errno == ENOENT)
+ continue;
+ return -1;
+ }
+ len = sizeof(info);
+ memset(&info, 0, sizeof(info));
+ info.name = ptr_to_u64(name);
+ info.name_len = sizeof(name);
+ err = bpf_btf_get_info_by_fd(fd, &info, &len);
+ if (err) {
+ close(fd);
+ return -1;
+ }
+ /* find target module BTF */
+ if (!strcmp(name, module))
+ break;
+
+ close(fd);
+ }
+
+ return fd;
+}
+
+void test_libbpf_probe_kfuncs(void)
+{
+ int ret, kfunc_id, fd;
+ char *kfunc = "bpf_cpumask_create";
+ struct btf *vmlinux_btf = NULL;
+ struct btf *module_btf = NULL;
+
+ vmlinux_btf = btf__parse("/sys/kernel/btf/vmlinux", NULL);
+ if (!ASSERT_OK_PTR(vmlinux_btf, "btf_parse"))
+ return;
+
+ kfunc_id = btf__find_by_name_kind(vmlinux_btf, kfunc, BTF_KIND_FUNC);
+ if (!ASSERT_GT(kfunc_id, 0, kfunc))
+ goto cleanup;
+
+ /* prog BPF_PROG_TYPE_SYSCALL supports kfunc bpf_cpumask_create */
+ ret = libbpf_probe_bpf_kfunc(BPF_PROG_TYPE_SYSCALL, kfunc_id, -1, NULL);
+ if (!ASSERT_EQ(ret, 1, "kfunc in vmlinux support"))
+ goto cleanup;
+
+ /* prog BPF_PROG_TYPE_KPROBE does not support kfunc bpf_cpumask_create */
+ ret = libbpf_probe_bpf_kfunc(BPF_PROG_TYPE_KPROBE, kfunc_id, -1, NULL);
+ if (!ASSERT_EQ(ret, 0, "kfunc in vmlinux not suuport"))
+ goto cleanup;
+
+ ret = libbpf_probe_bpf_kfunc(BPF_PROG_TYPE_KPROBE, -1, -1, NULL);
+ if (!ASSERT_EQ(ret, 0, "invalid kfunc id:-1"))
+ goto cleanup;
+
+ ret = libbpf_probe_bpf_kfunc(100000, kfunc_id, -1, NULL);
+ if (!ASSERT_ERR(ret, "invalid prog type:100000"))
+ goto cleanup;
+
+ if (!env.has_testmod)
+ goto cleanup;
+
+ module_btf = btf__load_module_btf("bpf_testmod", vmlinux_btf);
+ if (!ASSERT_OK_PTR(module_btf, "load module BTF"))
+ goto cleanup;
+
+ kfunc_id = btf__find_by_name(module_btf, "bpf_kfunc_call_test1");
+ if (!ASSERT_GT(kfunc_id, 0, "func not found"))
+ goto cleanup;
+
+ fd = module_btf_fd("bpf_testmod");
+ if (!ASSERT_GE(fd, 0, "module BTF fd"))
+ goto cleanup;
+
+ /* prog BPF_PROG_TYPE_SYSCALL supports kfunc bpf_kfunc_call_test1 in bpf_testmod */
+ ret = libbpf_probe_bpf_kfunc(BPF_PROG_TYPE_SYSCALL, kfunc_id, fd, NULL);
+ if (!ASSERT_EQ(ret, 1, "kfunc in module BTF support"))
+ goto cleanup_fd;
+
+ /* prog BPF_PROG_TYPE_KPROBE does not support kfunc bpf_kfunc_call_test1
+ * in bpf_testmod
+ */
+ ret = libbpf_probe_bpf_kfunc(BPF_PROG_TYPE_KPROBE, kfunc_id, fd, NULL);
+ if (!ASSERT_EQ(ret, 0, "kfunc in module BTF not support"))
+ goto cleanup_fd;
+
+ ret = libbpf_probe_bpf_kfunc(BPF_PROG_TYPE_SYSCALL, -1, fd, NULL);
+ if (!ASSERT_EQ(ret, 0, "invalid kfunc id in module BTF"))
+ goto cleanup_fd;
+
+ ret = libbpf_probe_bpf_kfunc(BPF_PROG_TYPE_SYSCALL, kfunc_id, 100, NULL);
+ ASSERT_EQ(ret, 0, "invalid BTF fd in module BTF");
+
+cleanup_fd:
+ close(fd);
+cleanup:
+ btf__free(vmlinux_btf);
+ btf__free(module_btf);
+}
+
+static const struct {
+ const char *name;
+ int code;
+} program_types[] = {
+#define _T(n) { #n, BPF_PROG_TYPE_##n }
+ _T(KPROBE),
+ _T(XDP),
+ _T(SYSCALL),
+ _T(SCHED_CLS),
+ _T(SCHED_ACT),
+ _T(SK_SKB),
+ _T(SOCKET_FILTER),
+ _T(CGROUP_SKB),
+ _T(LWT_OUT),
+ _T(LWT_IN),
+ _T(LWT_XMIT),
+ _T(LWT_SEG6LOCAL),
+ _T(NETFILTER),
+ _T(CGROUP_SOCK_ADDR),
+ _T(SCHED_ACT)
+#undef _T
+};
+
+void test_libbpf_probe_kfuncs_many(void)
+{
+ int i, kfunc_id, ret, id;
+ const struct btf_type *t;
+ struct btf *btf = NULL;
+ const char *kfunc;
+ const char *tag;
+
+ btf = btf__parse("/sys/kernel/btf/vmlinux", NULL);
+ if (!ASSERT_OK_PTR(btf, "btf_parse"))
+ return;
+ for (id = 0; id < btf__type_cnt(btf); ++id) {
+ t = btf__type_by_id(btf, id);
+ if (!t)
+ continue;
+ if (!btf_is_decl_tag(t))
+ continue;
+ tag = btf__name_by_offset(btf, t->name_off);
+ if (strcmp(tag, "bpf_kfunc") != 0)
+ continue;
+ kfunc_id = t->type;
+ t = btf__type_by_id(btf, kfunc_id);
+ if (!btf_is_func(t))
+ continue;
+ kfunc = btf__name_by_offset(btf, t->name_off);
+ for (i = 0; i < ARRAY_SIZE(program_types); ++i) {
+ ret = libbpf_probe_bpf_kfunc(program_types[i].code,
+ kfunc_id, -1, NULL);
+ if (ret < 0) {
+ ASSERT_FAIL("kfunc:%s use prog type:%d",
+ kfunc, program_types[i].code);
+ goto cleanup;
+ }
+ }
+ }
+cleanup:
+ btf__free(btf);
+}
--
2.43.0