selftests/bpf: Fix get_func_ip offset test for CONFIG_X86_KERNEL_IBT

With CONFIG_X86_KERNEL_IBT enabled the test for kprobe with offset
won't work because of the extra endbr instruction.

As suggested by Andrii adding CONFIG_X86_KERNEL_IBT detection
and using appropriate offset value based on that.

Also removing test7 program, because it does the same as test6.
Suggested-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Link: https://lore.kernel.org/r/20220926153340.1621984-7-jolsa@kernel.orgSigned-off-by: Alexei Starovoitov <ast@kernel.org>

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

@@ -2,7 +2,7 @@
 #include <test_progs.h>
 #include "get_func_ip_test.skel.h"
 
-void test_get_func_ip_test(void)
+static void test_function_entry(void)
 {
 	struct get_func_ip_test *skel = NULL;
 	int err, prog_fd;
@@ -12,14 +12,6 @@ void test_get_func_ip_test(void)
 	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);
-	bpf_program__set_autoload(skel->progs.test7, false);
-#endif
-
 	err = get_func_ip_test__load(skel);
 	if (!ASSERT_OK(err, "get_func_ip_test__load"))
 		goto cleanup;
@@ -43,11 +35,56 @@ 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");
+
+cleanup:
+	get_func_ip_test__destroy(skel);
+}
+
+/* test6 is x86_64 specific because of the instruction
+ * offset, disabling it for all other archs
+ */
 #ifdef __x86_64__
+static void test_function_body(void)
+{
+	struct get_func_ip_test *skel = NULL;
+	LIBBPF_OPTS(bpf_test_run_opts, topts);
+	LIBBPF_OPTS(bpf_kprobe_opts, kopts);
+	struct bpf_link *link6 = NULL;
+	int err, prog_fd;
+
+	skel = get_func_ip_test__open();
+	if (!ASSERT_OK_PTR(skel, "get_func_ip_test__open"))
+		return;
+
+	bpf_program__set_autoload(skel->progs.test6, true);
+
+	err = get_func_ip_test__load(skel);
+	if (!ASSERT_OK(err, "get_func_ip_test__load"))
+		goto cleanup;
+
+	kopts.offset = skel->kconfig->CONFIG_X86_KERNEL_IBT ? 9 : 5;
+
+	link6 = bpf_program__attach_kprobe_opts(skel->progs.test6, "bpf_fentry_test6", &kopts);
+	if (!ASSERT_OK_PTR(link6, "link6"))
+		goto cleanup;
+
+	prog_fd = bpf_program__fd(skel->progs.test1);
+	err = bpf_prog_test_run_opts(prog_fd, &topts);
+	ASSERT_OK(err, "test_run");
+	ASSERT_EQ(topts.retval, 0, "test_run");
+
 	ASSERT_EQ(skel->bss->test6_result, 1, "test6_result");
-	ASSERT_EQ(skel->bss->test7_result, 1, "test7_result");
-#endif
 
 cleanup:
+	bpf_link__destroy(link6);
 	get_func_ip_test__destroy(skel);
 }
+#else
+#define test_function_body()
+#endif
+
+void test_get_func_ip_test(void)
+{
+	test_function_entry();
+	test_function_body();
+}

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

@@ -2,6 +2,7 @@
 #include <linux/bpf.h>
 #include <bpf/bpf_helpers.h>
 #include <bpf/bpf_tracing.h>
+#include <stdbool.h>
 
 char _license[] SEC("license") = "GPL";
 
@@ -13,6 +14,16 @@ extern const void bpf_modify_return_test __ksym;
 extern const void bpf_fentry_test6 __ksym;
 extern const void bpf_fentry_test7 __ksym;
 
+extern bool CONFIG_X86_KERNEL_IBT __kconfig __weak;
+
+/* This function is here to have CONFIG_X86_KERNEL_IBT
+ * used and added to object BTF.
+ */
+int unused(void)
+{
+	return CONFIG_X86_KERNEL_IBT ? 0 : 1;
+}
+
 __u64 test1_result = 0;
 SEC("fentry/bpf_fentry_test1")
 int BPF_PROG(test1, int a)
@@ -64,7 +75,7 @@ int BPF_PROG(test5, int a, int *b, int ret)
 }
 
 __u64 test6_result = 0;
-SEC("kprobe/bpf_fentry_test6+0x5")
+SEC("?kprobe")
 int test6(struct pt_regs *ctx)
 {
 	__u64 addr = bpf_get_func_ip(ctx);
@@ -72,13 +83,3 @@ int test6(struct pt_regs *ctx)
 	test6_result = (const void *) addr == 0;
 	return 0;
 }
-
-__u64 test7_result = 0;
-SEC("kprobe/bpf_fentry_test7+5")
-int test7(struct pt_regs *ctx)
-{
-	__u64 addr = bpf_get_func_ip(ctx);
-
-	test7_result = (const void *) addr == 0;
-	return 0;
-}