[PATCHv4 13/14] selftests/bpf: Add uprobe session single consumer test

[Jiri Olsa <jolsa@kernel.org>]

Testing that the session ret_handler bypass works on single
uprobe with multiple consumers, each with different session
ignore return value.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
---
 .../bpf/prog_tests/uprobe_multi_test.c        | 33 ++++++++++++++
 .../bpf/progs/uprobe_multi_session_single.c   | 44 +++++++++++++++++++
 2 files changed, 77 insertions(+)
 create mode 100644 tools/testing/selftests/bpf/progs/uprobe_multi_session_single.c

diff --git a/tools/testing/selftests/bpf/prog_tests/uprobe_multi_test.c b/tools/testing/selftests/bpf/prog_tests/uprobe_multi_test.c
index 210cdb620ee0..594aa8c06f58 100644
--- a/tools/testing/selftests/bpf/prog_tests/uprobe_multi_test.c
+++ b/tools/testing/selftests/bpf/prog_tests/uprobe_multi_test.c
@@ -7,6 +7,7 @@
 #include "uprobe_multi_bench.skel.h"
 #include "uprobe_multi_usdt.skel.h"
 #include "uprobe_multi_session.skel.h"
+#include "uprobe_multi_session_single.skel.h"
 #include "uprobe_multi_session_cookie.skel.h"
 #include "uprobe_multi_session_recursive.skel.h"
 #include "uprobe_multi_verifier.skel.h"
@@ -669,6 +670,36 @@ static void test_session_skel_api(void)
 	uprobe_multi_session__destroy(skel);
 }
 
+static void test_session_single_skel_api(void)
+{
+	struct uprobe_multi_session_single *skel = NULL;
+	LIBBPF_OPTS(bpf_kprobe_multi_opts, opts);
+	int err;
+
+	skel = uprobe_multi_session_single__open_and_load();
+	if (!ASSERT_OK_PTR(skel, "uprobe_multi_session_single__open_and_load"))
+		goto cleanup;
+
+	skel->bss->pid = getpid();
+
+	err = uprobe_multi_session_single__attach(skel);
+	if (!ASSERT_OK(err, "uprobe_multi_session_single__attach"))
+		goto cleanup;
+
+	uprobe_multi_func_1();
+
+	/*
+	 * We expect consumer 0 and 2 to trigger just entry handler (value 1)
+	 * and consumer 1 to hit both (value 2).
+	 */
+	ASSERT_EQ(skel->bss->uprobe_session_result[0], 1, "uprobe_session_result_0");
+	ASSERT_EQ(skel->bss->uprobe_session_result[1], 2, "uprobe_session_result_1");
+	ASSERT_EQ(skel->bss->uprobe_session_result[2], 1, "uprobe_session_result_2");
+
+cleanup:
+	uprobe_multi_session_single__destroy(skel);
+}
+
 static void test_session_cookie_skel_api(void)
 {
 	struct uprobe_multi_session_cookie *skel = NULL;
@@ -835,6 +866,8 @@ void test_uprobe_multi_test(void)
 		test_attach_api_fails();
 	if (test__start_subtest("session"))
 		test_session_skel_api();
+	if (test__start_subtest("session_single"))
+		test_session_single_skel_api();
 	if (test__start_subtest("session_cookie"))
 		test_session_cookie_skel_api();
 	if (test__start_subtest("session_cookie_recursive"))
diff --git a/tools/testing/selftests/bpf/progs/uprobe_multi_session_single.c b/tools/testing/selftests/bpf/progs/uprobe_multi_session_single.c
new file mode 100644
index 000000000000..1fa53d3785f6
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/uprobe_multi_session_single.c
@@ -0,0 +1,44 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/bpf.h>
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+#include <stdbool.h>
+#include "bpf_kfuncs.h"
+#include "bpf_misc.h"
+
+char _license[] SEC("license") = "GPL";
+
+__u64 uprobe_session_result[3] = {};
+int pid = 0;
+
+static int uprobe_multi_check(void *ctx, bool is_return, int idx)
+{
+	if (bpf_get_current_pid_tgid() >> 32 != pid)
+		return 1;
+
+	uprobe_session_result[idx]++;
+
+	/* only consumer 1 executes return probe */
+	if (idx == 0 || idx == 2)
+		return 1;
+
+	return 0;
+}
+
+SEC("uprobe.session//proc/self/exe:uprobe_multi_func_1")
+int uprobe_0(struct pt_regs *ctx)
+{
+	return uprobe_multi_check(ctx, bpf_session_is_return(), 0);
+}
+
+SEC("uprobe.session//proc/self/exe:uprobe_multi_func_1")
+int uprobe_1(struct pt_regs *ctx)
+{
+	return uprobe_multi_check(ctx, bpf_session_is_return(), 1);
+}
+
+SEC("uprobe.session//proc/self/exe:uprobe_multi_func_1")
+int uprobe_2(struct pt_regs *ctx)
+{
+	return uprobe_multi_check(ctx, bpf_session_is_return(), 2);
+}
-- 
2.46.0