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 <jo...@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


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