selftests/bpf: Add serial_test_kprobe_multi_bench_attach_kernel/module tests

Add bench test for module portion of the symbols as well.

  # ./test_progs -v -t kprobe_multi_bench_attach_module
  bpf_testmod.ko is already unloaded.
  Loading bpf_testmod.ko...
  Successfully loaded bpf_testmod.ko.
  test_kprobe_multi_bench_attach:PASS:get_syms 0 nsec
  test_kprobe_multi_bench_attach:PASS:kprobe_multi_empty__open_and_load 0 nsec
  test_kprobe_multi_bench_attach:PASS:bpf_program__attach_kprobe_multi_opts 0 nsec
  test_kprobe_multi_bench_attach: found 26620 functions
  test_kprobe_multi_bench_attach: attached in   0.182s
  test_kprobe_multi_bench_attach: detached in   0.082s
  #96      kprobe_multi_bench_attach_module:OK
  Summary: 1/0 PASSED, 0 SKIPPED, 0 FAILED
  Successfully unloaded bpf_testmod.ko.

It's useful for testing kprobe multi link modules resolving.
Acked-by: Song Liu <song@kernel.org>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Link: https://lore.kernel.org/r/20230116101009.23694-3-jolsa@kernel.orgSigned-off-by: Alexei Starovoitov <ast@kernel.org>

tools/testing/selftests/bpf/prog_tests/kprobe_multi_test.c

@@ -322,7 +322,7 @@ static bool symbol_equal(long key1, long key2, void *ctx __maybe_unused)
 	return strcmp((const char *) key1, (const char *) key2) == 0;
 }
 
-static int get_syms(char ***symsp, size_t *cntp)
+static int get_syms(char ***symsp, size_t *cntp, bool kernel)
 {
 	size_t cap = 0, cnt = 0, i;
 	char *name = NULL, **syms = NULL;
@@ -349,8 +349,9 @@ static int get_syms(char ***symsp, size_t *cntp)
 	}
 
 	while (fgets(buf, sizeof(buf), f)) {
-		/* skip modules */
-		if (strchr(buf, '['))
+		if (kernel && strchr(buf, '['))
+			continue;
+		if (!kernel && !strchr(buf, '['))
 			continue;
 
 		free(name);
@@ -404,7 +405,7 @@ static int get_syms(char ***symsp, size_t *cntp)
 	return err;
 }
 
-void serial_test_kprobe_multi_bench_attach(void)
+static void test_kprobe_multi_bench_attach(bool kernel)
 {
 	LIBBPF_OPTS(bpf_kprobe_multi_opts, opts);
 	struct kprobe_multi_empty *skel = NULL;
@@ -415,7 +416,7 @@ void serial_test_kprobe_multi_bench_attach(void)
 	char **syms = NULL;
 	size_t cnt = 0, i;
 
-	if (!ASSERT_OK(get_syms(&syms, &cnt), "get_syms"))
+	if (!ASSERT_OK(get_syms(&syms, &cnt, kernel), "get_syms"))
 		return;
 
 	skel = kprobe_multi_empty__open_and_load();
@@ -453,6 +454,14 @@ void serial_test_kprobe_multi_bench_attach(void)
 	}
 }
 
+void serial_test_kprobe_multi_bench_attach(void)
+{
+	if (test__start_subtest("kernel"))
+		test_kprobe_multi_bench_attach(true);
+	if (test__start_subtest("modules"))
+		test_kprobe_multi_bench_attach(false);
+}
+
 void test_kprobe_multi_test(void)
 {
 	if (!ASSERT_OK(load_kallsyms(), "load_kallsyms"))