[PATCHv4 08/14] selftests/bpf: Add uprobe session test

Jiri Olsa
2024-09-17T08:52:12Z

Adding uprobe session test and testing that the entry program
return value controls execution of the return probe program.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
---
.../bpf/prog_tests/uprobe_multi_test.c | 47 ++++++++++++
.../bpf/progs/uprobe_multi_session.c | 71 +++++++++++++++++++
2 files changed, 118 insertions(+)
create mode 100644 tools/testing/selftests/bpf/progs/uprobe_multi_session.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 bf6ca8e3eb13..aaafd80623c5 100644
--- a/tools/testing/selftests/bpf/prog_tests/uprobe_multi_test.c
+++ b/tools/testing/selftests/bpf/prog_tests/uprobe_multi_test.c
@@ -6,6 +6,7 @@
#include "uprobe_multi.skel.h"
#include "uprobe_multi_bench.skel.h"
#include "uprobe_multi_usdt.skel.h"
+#include "uprobe_multi_session.skel.h"
#include "bpf/libbpf_internal.h"
#include "testing_helpers.h"
#include "../sdt.h"
@@ -615,6 +616,50 @@ static void test_link_api(void)
__test_link_api(child);
}

+static void test_session_skel_api(void)
+{
+ struct uprobe_multi_session *skel = NULL;
+ LIBBPF_OPTS(bpf_kprobe_multi_opts, opts);
+ struct bpf_link *link = NULL;
+ int err;
+
+ skel = uprobe_multi_session__open_and_load();
+ if (!ASSERT_OK_PTR(skel, "uprobe_multi_session__open_and_load"))
+ goto cleanup;
+
+ skel->bss->pid = getpid();
+ skel->bss->user_ptr = test_data;
+
+ err = uprobe_multi_session__attach(skel);
+ if (!ASSERT_OK(err, "uprobe_multi_session__attach"))
+ goto cleanup;
+
+ /* trigger all probes */
+ skel->bss->uprobe_multi_func_1_addr = (__u64) uprobe_multi_func_1;
+ skel->bss->uprobe_multi_func_2_addr = (__u64) uprobe_multi_func_2;
+ skel->bss->uprobe_multi_func_3_addr = (__u64) uprobe_multi_func_3;
+
+ uprobe_multi_func_1();
+ uprobe_multi_func_2();
+ uprobe_multi_func_3();
+
+ /*
+ * We expect 2 for uprobe_multi_func_2 because it runs both entry/return probe,
+ * uprobe_multi_func_[13] run just the entry probe. All expected numbers are
+ * doubled, because we run extra test for sleepable session.
+ */
+ ASSERT_EQ(skel->bss->uprobe_session_result[0], 2, "uprobe_multi_func_1_result");
+ ASSERT_EQ(skel->bss->uprobe_session_result[1], 4, "uprobe_multi_func_2_result");
+ ASSERT_EQ(skel->bss->uprobe_session_result[2], 2, "uprobe_multi_func_3_result");
+
+ /* We expect increase in 3 entry and 1 return session calls -> 4 */
+ ASSERT_EQ(skel->bss->uprobe_multi_sleep_result, 4, "uprobe_multi_sleep_result");
+
+cleanup:
+ bpf_link__destroy(link);
+ uprobe_multi_session__destroy(skel);
+}
+
static void test_bench_attach_uprobe(void)
{
long attach_start_ns = 0, attach_end_ns = 0;
@@ -703,4 +748,6 @@ void test_uprobe_multi_test(void)
test_bench_attach_usdt();
if (test__start_subtest("attach_api_fails"))
test_attach_api_fails();
+ if (test__start_subtest("session"))
+ test_session_skel_api();
}
diff --git a/tools/testing/selftests/bpf/progs/uprobe_multi_session.c b/tools/testing/selftests/bpf/progs/uprobe_multi_session.c
new file mode 100644
index 000000000000..30bff90b68dc
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/uprobe_multi_session.c
@@ -0,0 +1,71 @@
+// 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_multi_func_1_addr = 0;
+__u64 uprobe_multi_func_2_addr = 0;
+__u64 uprobe_multi_func_3_addr = 0;
+
+__u64 uprobe_session_result[3] = {};
+__u64 uprobe_multi_sleep_result = 0;
+
+void *user_ptr = 0;
+int pid = 0;
+
+static int uprobe_multi_check(void *ctx, bool is_return)
+{
+ const __u64 funcs[] = {
+ uprobe_multi_func_1_addr,
+ uprobe_multi_func_2_addr,
+ uprobe_multi_func_3_addr,
+ };
+ unsigned int i;
+ __u64 addr;
+
+ if (bpf_get_current_pid_tgid() >> 32 != pid)
+ return 1;
+
+ addr = bpf_get_func_ip(ctx);
+
+ for (i = 0; i < ARRAY_SIZE(funcs); i++) {
+ if (funcs[i] == addr) {
+ uprobe_session_result[i]++;
+ break;
+ }
+ }
+
+ /* only uprobe_multi_func_2 executes return probe */
+ if ((addr == uprobe_multi_func_1_addr) ||
+ (addr == uprobe_multi_func_3_addr))
+ return 1;
+
+ return 0;
+}
+
+SEC("uprobe.session//proc/self/exe:uprobe_multi_func_*")
+int uprobe(struct pt_regs *ctx)
+{
+ return uprobe_multi_check(ctx, bpf_session_is_return());
+}
+
+static __always_inline bool verify_sleepable_user_copy(void)
+{
+ char data[9];
+
+ bpf_copy_from_user(data, sizeof(data), user_ptr);
+ return bpf_strncmp(data, sizeof(data), "test_data") == 0;
+}
+
+SEC("uprobe.session.s//proc/self/exe:uprobe_multi_func_*")
+int uprobe_sleepable(struct pt_regs *ctx)
+{
+ if (verify_sleepable_user_copy())
+ uprobe_multi_sleep_result++;
+ return uprobe_multi_check(ctx, bpf_session_is_return());
+}
--
2.46.0