[PATCH bpf-next v3 9/9] selftests/bpf: Test typeless module ksym resolution

[Samuel Wu <wusamuel@google.com>]

The module ksym tests use typed ksyms, which libbpf resolves through
BTF. Add a weak typeless module ksym to the ksyms test, to cover the
module path of KALLSYMS_QUERY_BY_NAME.

Signed-off-by: Samuel Wu <wusamuel@google.com>
---
 tools/testing/selftests/bpf/prog_tests/ksyms.c | 9 +++++++++
 tools/testing/selftests/bpf/progs/test_ksyms.c | 4 ++++
 2 files changed, 13 insertions(+)

diff --git a/tools/testing/selftests/bpf/prog_tests/ksyms.c b/tools/testing/selftests/bpf/prog_tests/ksyms.c
index dc7aab532fb1..801d38560473 100644
--- a/tools/testing/selftests/bpf/prog_tests/ksyms.c
+++ b/tools/testing/selftests/bpf/prog_tests/ksyms.c
@@ -11,6 +11,7 @@ void test_ksyms(void)
 	struct test_ksyms *skel;
 	struct test_ksyms__data *data;
 	__u64 link_fops_addr, per_cpu_start_addr;
+	__u64 testmod_ksym_addr = 0;
 	struct stat st;
 	__u64 btf_size;
 	int err;
@@ -27,6 +28,12 @@ void test_ksyms(void)
 	if (!ASSERT_NEQ(err, -ENOENT, "__per_cpu_start: ksym_find"))
 		return;
 
+	if (env.has_testmod &&
+	    !ASSERT_OK(kallsyms_find("bpf_testmod_ksym_percpu",
+				     &testmod_ksym_addr),
+		       "bpf_testmod_ksym_percpu: kallsyms_find"))
+		return;
+
 	if (!ASSERT_OK(stat(btf_path, &st), "stat_btf"))
 		return;
 	btf_size = st.st_size;
@@ -47,6 +54,8 @@ void test_ksyms(void)
 	ASSERT_EQ(data->out__bpf_link_fops1, 0, "bpf_link_fops1");
 	ASSERT_EQ(data->out__btf_size, btf_size, "btf_size");
 	ASSERT_EQ(data->out__per_cpu_start, per_cpu_start_addr, "__per_cpu_start");
+	ASSERT_EQ(data->out__bpf_testmod_ksym_percpu, testmod_ksym_addr,
+		  "bpf_testmod_ksym_percpu");
 
 cleanup:
 	test_ksyms__destroy(skel);
diff --git a/tools/testing/selftests/bpf/progs/test_ksyms.c b/tools/testing/selftests/bpf/progs/test_ksyms.c
index 6c9cbb5a3bdf..0506bb574c4a 100644
--- a/tools/testing/selftests/bpf/progs/test_ksyms.c
+++ b/tools/testing/selftests/bpf/progs/test_ksyms.c
@@ -9,6 +9,7 @@ __u64 out__bpf_link_fops = -1;
 __u64 out__bpf_link_fops1 = -1;
 __u64 out__btf_size = -1;
 __u64 out__per_cpu_start = -1;
+__u64 out__bpf_testmod_ksym_percpu = -1;
 
 extern const void bpf_link_fops __ksym;
 extern const void __start_BTF __ksym;
@@ -16,6 +17,8 @@ extern const void __stop_BTF __ksym;
 extern const void __per_cpu_start __ksym;
 /* non-existing symbol, weak, default to zero */
 extern const void bpf_link_fops1 __ksym __weak;
+/* module symbol, weak, zero if bpf_testmod is not loaded */
+extern const void bpf_testmod_ksym_percpu __ksym __weak;
 
 SEC("raw_tp/sys_enter")
 int handler(const void *ctx)
@@ -25,6 +28,7 @@ int handler(const void *ctx)
 	out__per_cpu_start = (__u64)&__per_cpu_start;
 
 	out__bpf_link_fops1 = (__u64)&bpf_link_fops1;
+	out__bpf_testmod_ksym_percpu = (__u64)&bpf_testmod_ksym_percpu;
 
 	return 0;
 }
-- 
2.56.0.679.gc527c65306-goog