[PATCHv2 perf/core 4/4] selftests/bpf: Add uprobe context ip register change test

[Jiri Olsa]

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 <jo...@kernel.org>
---
 .../testing/selftests/bpf/prog_tests/uprobe.c | 42 +++++++++++++++++++
 .../testing/selftests/bpf/progs/test_uprobe.c | 14 +++++++
 2 files changed, 56 insertions(+)

diff --git a/tools/testing/selftests/bpf/prog_tests/uprobe.c 
b/tools/testing/selftests/bpf/prog_tests/uprobe.c
index 19dd900df188..86404476c1da 100644
--- a/tools/testing/selftests/bpf/prog_tests/uprobe.c
+++ b/tools/testing/selftests/bpf/prog_tests/uprobe.c
@@ -190,10 +190,52 @@ static void regs_common(void)
        test_uprobe__destroy(skel);
 }
 
+static noinline unsigned long uprobe_regs_change_ip_1(void)
+{
+       return 0xc0ffee;
+}
+
+static noinline unsigned long uprobe_regs_change_ip_2(void)
+{
+       return 0xdeadbeef;
+}
+
+static void regs_ip(void)
+{
+       LIBBPF_OPTS(bpf_uprobe_opts, uprobe_opts);
+       struct test_uprobe *skel;
+       unsigned long ret;
+
+       skel = test_uprobe__open_and_load();
+       if (!ASSERT_OK_PTR(skel, "skel_open"))
+               return;
+
+       skel->bss->my_pid = getpid();
+       skel->bss->ip = (unsigned long) uprobe_regs_change_ip_2;
+
+       uprobe_opts.func_name = "uprobe_regs_change_ip_1";
+       skel->links.test_regs_change_ip = bpf_program__attach_uprobe_opts(
+                                               skel->progs.test_regs_change_ip,
+                                               -1,
+                                               "/proc/self/exe",
+                                               0 /* offset */,
+                                               &uprobe_opts);
+       if (!ASSERT_OK_PTR(skel->links.test_regs_change_ip, 
"bpf_program__attach_uprobe_opts"))
+               goto cleanup;
+
+       ret = uprobe_regs_change_ip_1();
+       ASSERT_EQ(ret, 0xdeadbeef, "ret");
+
+cleanup:
+       test_uprobe__destroy(skel);
+}
+
 static void test_uprobe_regs_change(void)
 {
        if (test__start_subtest("regs_change_common"))
                regs_common();
+       if (test__start_subtest("regs_change_ip"))
+               regs_ip();
 }
 #else
 static void test_uprobe_regs_change(void) { }
diff --git a/tools/testing/selftests/bpf/progs/test_uprobe.c 
b/tools/testing/selftests/bpf/progs/test_uprobe.c
index 9437bd76a437..12f4065fca20 100644
--- a/tools/testing/selftests/bpf/progs/test_uprobe.c
+++ b/tools/testing/selftests/bpf/progs/test_uprobe.c
@@ -82,4 +82,18 @@ int BPF_UPROBE(test_regs_change)
        ctx->si  = regs.si;
        return 0;
 }
+
+unsigned long ip;
+
+SEC("uprobe")
+int BPF_UPROBE(test_regs_change_ip)
+{
+       pid_t pid = bpf_get_current_pid_tgid() >> 32;
+
+       if (pid != my_pid)
+               return 0;
+
+       ctx->ip = ip;
+       return 0;
+}
 #endif
-- 
2.51.0