[PATCH perf/core 09/11] selftests/bpf: Add uprobe multi context ip register change test

[Jiri Olsa <jolsa@kernel.org>]

Adding test to check we can change the application execution
through instruction pointer change through uprobe program.

It's x86_64 specific test.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
---
 .../bpf/prog_tests/uprobe_multi_test.c        | 42 +++++++++++++++++++
 .../selftests/bpf/progs/uprobe_multi.c        | 14 +++++++
 2 files changed, 56 insertions(+)

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 012652b07399..4630a6c65c3c 100644
--- a/tools/testing/selftests/bpf/prog_tests/uprobe_multi_test.c
+++ b/tools/testing/selftests/bpf/prog_tests/uprobe_multi_test.c
@@ -1437,10 +1437,52 @@ static void unique_regs_common(void)
 	uprobe_multi__destroy(skel);
 }
 
+noinline static unsigned long uprobe_regs_change_ip_1(void)
+{
+	return 0xc0ffee;
+}
+
+noinline static unsigned long uprobe_regs_change_ip_2(void)
+{
+	return 0xdeadbeef;
+}
+
+static void unique_regs_ip(void)
+{
+	LIBBPF_OPTS(bpf_uprobe_multi_opts, opts,
+		.unique = true,
+	);
+	struct uprobe_multi *skel;
+	int ret;
+
+	skel = uprobe_multi__open_and_load();
+	if (!ASSERT_OK_PTR(skel, "skel_open"))
+		return;
+
+	skel->bss->pid = getpid();
+	skel->bss->ip = (unsigned long) uprobe_regs_change_ip_2;
+
+	skel->links.uprobe_change_ip = bpf_program__attach_uprobe_multi(
+						skel->progs.uprobe_change_ip,
+						-1, "/proc/self/exe",
+						"uprobe_regs_change_ip_1",
+						&opts);
+	if (!ASSERT_OK_PTR(skel->links.uprobe_change_ip, "bpf_program__attach_uprobe_multi"))
+		goto cleanup;
+
+	ret = uprobe_regs_change_ip_1();
+	ASSERT_EQ(ret, 0xdeadbeef, "ret");
+
+cleanup:
+	uprobe_multi__destroy(skel);
+}
+
 static void test_unique(void)
 {
 	if (test__start_subtest("unique_regs_common"))
 		unique_regs_common();
+	if (test__start_subtest("unique_regs_ip"))
+		unique_regs_ip();
 }
 #else
 static void test_unique(void) { }
diff --git a/tools/testing/selftests/bpf/progs/uprobe_multi.c b/tools/testing/selftests/bpf/progs/uprobe_multi.c
index f26f8b840985..563fd37ed77d 100644
--- a/tools/testing/selftests/bpf/progs/uprobe_multi.c
+++ b/tools/testing/selftests/bpf/progs/uprobe_multi.c
@@ -164,4 +164,18 @@ int BPF_UPROBE(uprobe_change_regs)
 	ctx->si  = regs.si;
 	return 0;
 }
+
+unsigned long ip;
+
+SEC("uprobe.unique")
+int BPF_UPROBE(uprobe_change_ip)
+{
+	pid_t cur_pid = bpf_get_current_pid_tgid() >> 32;
+
+	if (cur_pid != pid)
+		return 0;
+
+	ctx->ip = ip;
+	return 0;
+}
 #endif
-- 
2.51.0