[RFC bpf-next 10/10] selftests/bpf: Add uprobe session recursive test

Jiri Olsa
2024-06-04T20:04:35Z

Adding uprobe session test that verifies the cookie value is stored
properly when single uprobe-ed function is executed recursively.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
---
.../bpf/prog_tests/uprobe_multi_test.c | 57 +++++++++++++++++++
.../progs/uprobe_multi_session_recursive.c | 44 ++++++++++++++
2 files changed, 101 insertions(+)
create mode 100644 tools/testing/selftests/bpf/progs/uprobe_multi_session_recursive.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 34671253e130..cdd7c327e16d 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_usdt.skel.h"
#include "uprobe_multi_session.skel.h"
#include "uprobe_multi_session_cookie.skel.h"
+#include "uprobe_multi_session_recursive.skel.h"
#include "bpf/libbpf_internal.h"
#include "testing_helpers.h"

@@ -27,6 +28,12 @@ noinline void uprobe_multi_func_3(void)
asm volatile ("");
}

+noinline void uprobe_session_recursive(int i)
+{
+ if (i)
+ uprobe_session_recursive(i - 1);
+}
+
struct child {
int go[2];
int pid;
@@ -587,6 +594,54 @@ static void test_session_cookie_skel_api(void)
uprobe_multi_session_cookie__destroy(skel);
}

+static void test_session_recursive_skel_api(void)
+{
+ struct uprobe_multi_session_recursive *skel = NULL;
+ int i, err;
+
+ skel = uprobe_multi_session_recursive__open_and_load();
+ if (!ASSERT_OK_PTR(skel, "uprobe_multi_session_recursive__open_and_load"))
+ goto cleanup;
+
+ skel->bss->pid = getpid();
+
+ err = uprobe_multi_session_recursive__attach(skel);
+ if (!ASSERT_OK(err, "uprobe_multi_session_recursive__attach"))
+ goto cleanup;
+
+ for (i = 0; i < ARRAY_SIZE(skel->bss->test_uprobe_cookie_entry); i++)
+ skel->bss->test_uprobe_cookie_entry[i] = i + 1;
+
+ uprobe_session_recursive(5);
+
+ /*
+ * entry uprobe:
+ * uprobe_session_recursive(5) { *cookie = 1, return 0
+ * uprobe_session_recursive(4) { *cookie = 2, return 1
+ * uprobe_session_recursive(3) { *cookie = 3, return 0
+ * uprobe_session_recursive(2) { *cookie = 4, return 1
+ * uprobe_session_recursive(1) { *cookie = 5, return 0
+ * uprobe_session_recursive(0) { *cookie = 6, return 1
+ * return uprobe:
+ * } i = 0 not executed
+ * } i = 1 test_uprobe_cookie_return[0] = 5
+ * } i = 2 not executed
+ * } i = 3 test_uprobe_cookie_return[1] = 3
+ * } i = 4 not executed
+ * } i = 5 test_uprobe_cookie_return[2] = 1
+ */
+
+ ASSERT_EQ(skel->bss->idx_entry, 6, "idx_entry");
+ ASSERT_EQ(skel->bss->idx_return, 3, "idx_return");
+
+ ASSERT_EQ(skel->bss->test_uprobe_cookie_return[0], 5, "test_uprobe_cookie_return[0]");
+ ASSERT_EQ(skel->bss->test_uprobe_cookie_return[1], 3, "test_uprobe_cookie_return[1]");
+ ASSERT_EQ(skel->bss->test_uprobe_cookie_return[2], 1, "test_uprobe_cookie_return[2]");
+
+cleanup:
+ uprobe_multi_session_recursive__destroy(skel);
+}
+
static void test_bench_attach_uprobe(void)
{
long attach_start_ns = 0, attach_end_ns = 0;
@@ -681,4 +736,6 @@ void test_uprobe_multi_test(void)
test_session_error_multiple_instances();
if (test__start_subtest("session_cookie"))
test_session_cookie_skel_api();
+ if (test__start_subtest("session_cookie_recursive"))
+ test_session_recursive_skel_api();
}
diff --git a/tools/testing/selftests/bpf/progs/uprobe_multi_session_recursive.c b/tools/testing/selftests/bpf/progs/uprobe_multi_session_recursive.c
new file mode 100644
index 000000000000..7babc180c28f
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/uprobe_multi_session_recursive.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";
+
+int pid = 0;
+
+int idx_entry = 0;
+int idx_return = 0;
+
+__u64 test_uprobe_cookie_entry[6];
+__u64 test_uprobe_cookie_return[3];
+
+static int check_cookie(void)
+{
+ long *cookie = bpf_session_cookie();
+
+ if (bpf_session_is_return()) {
+ if (idx_return >= ARRAY_SIZE(test_uprobe_cookie_return))
+ return 1;
+ test_uprobe_cookie_return[idx_return++] = *cookie;
+ return 0;
+ }
+
+ if (idx_entry >= ARRAY_SIZE(test_uprobe_cookie_entry))
+ return 1;
+ *cookie = test_uprobe_cookie_entry[idx_entry];
+ return idx_entry++ % 2;
+}
+
+
+SEC("uprobe.session//proc/self/exe:uprobe_session_recursive")
+int uprobe_recursive(struct pt_regs *ctx)
+{
+ if (bpf_get_current_pid_tgid() >> 32 != pid)
+ return 1;
+
+ return check_cookie();
+}
--
2.45.1