selftests/bpf: Add test for bpf_get_func_ip in kprobe+offset probe

Adding test for bpf_get_func_ip in kprobe+ofset probe.
Because of the offset value it's arch specific, enabling
the new test only for x86_64 architecture.
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210714094400.396467-9-jolsa@kernel.org

tools/testing/selftests/bpf/prog_tests/get_func_ip_test.c

@@ -8,10 +8,21 @@ void test_get_func_ip_test(void)
 	__u32 duration = 0, retval;
 	int err, prog_fd;
 
-	skel = get_func_ip_test__open_and_load();
-	if (!ASSERT_OK_PTR(skel, "get_func_ip_test__open_and_load"))
+	skel = get_func_ip_test__open();
+	if (!ASSERT_OK_PTR(skel, "get_func_ip_test__open"))
 		return;
 
+	/* test6 is x86_64 specifc because of the instruction
+	 * offset, disabling it for all other archs
+	 */
+#ifndef __x86_64__
+	bpf_program__set_autoload(skel->progs.test6, false);
+#endif
+
+	err = get_func_ip_test__load(skel);
+	if (!ASSERT_OK(err, "get_func_ip_test__load"))
+		goto cleanup;
+
 	err = get_func_ip_test__attach(skel);
 	if (!ASSERT_OK(err, "get_func_ip_test__attach"))
 		goto cleanup;
@@ -33,6 +44,9 @@ void test_get_func_ip_test(void)
 	ASSERT_EQ(skel->bss->test3_result, 1, "test3_result");
 	ASSERT_EQ(skel->bss->test4_result, 1, "test4_result");
 	ASSERT_EQ(skel->bss->test5_result, 1, "test5_result");
+#ifdef __x86_64__
+	ASSERT_EQ(skel->bss->test6_result, 1, "test6_result");
+#endif
 
 cleanup:
 	get_func_ip_test__destroy(skel);

tools/testing/selftests/bpf/progs/get_func_ip_test.c

@@ -10,6 +10,7 @@ extern const void bpf_fentry_test2 __ksym;
 extern const void bpf_fentry_test3 __ksym;
 extern const void bpf_fentry_test4 __ksym;
 extern const void bpf_modify_return_test __ksym;
+extern const void bpf_fentry_test6 __ksym;
 
 __u64 test1_result = 0;
 SEC("fentry/bpf_fentry_test1")
@@ -60,3 +61,13 @@ int BPF_PROG(test5, int a, int *b, int ret)
 	test5_result = (const void *) addr == &bpf_modify_return_test;
 	return ret;
 }
+
+__u64 test6_result = 0;
+SEC("kprobe/bpf_fentry_test6+0x5")
+int test6(struct pt_regs *ctx)
+{
+	__u64 addr = bpf_get_func_ip(ctx);
+
+	test6_result = (const void *) addr == &bpf_fentry_test6 + 5;
+	return 0;
+}