tracing: Add trampoline/graph selftest

Adding selftest for checking that direct trampoline can
co-exist together with graph tracer on same function.

This is supported for CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS
config option, which is defined only for x86_64 for now.

Link: https://lkml.kernel.org/r/20211008091336.33616-5-jolsa@kernel.org
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

diff --git a/kernel/trace/trace_selftest.c b/kernel/trace/trace_selftest.c
index 875b4f1..3404a24 100644 (file)
--- a/kernel/trace/trace_selftest.c
+++ b/kernel/trace/trace_selftest.c
@@ -784,6 +784,8 @@ static struct fgraph_ops fgraph_ops __initdata  = {
        .retfunc                = &trace_graph_return,
 };
 
+noinline __noclone static void trace_direct_tramp(void) { }
+
 /*
  * Pretty much the same than for the function tracer from which the selftest
  * has been borrowed.
@@ -794,6 +796,7 @@ trace_selftest_startup_function_graph(struct tracer *trace,
 {
        int ret;
        unsigned long count;
+       char *func_name __maybe_unused;
 
 #ifdef CONFIG_DYNAMIC_FTRACE
        if (ftrace_filter_param) {
@@ -842,8 +845,57 @@ trace_selftest_startup_function_graph(struct tracer *trace,
                goto out;
        }
 
-       /* Don't test dynamic tracing, the function tracer already did */
+#ifdef CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS
+       tracing_reset_online_cpus(&tr->array_buffer);
+       set_graph_array(tr);
+
+       /*
+        * Some archs *cough*PowerPC*cough* add characters to the
+        * start of the function names. We simply put a '*' to
+        * accommodate them.
+        */
+       func_name = "*" __stringify(DYN_FTRACE_TEST_NAME);
+       ftrace_set_global_filter(func_name, strlen(func_name), 1);
+
+       /*
+        * Register direct function together with graph tracer
+        * and make sure we get graph trace.
+        */
+       ret = register_ftrace_direct((unsigned long) DYN_FTRACE_TEST_NAME,
+                                    (unsigned long) trace_direct_tramp);
+       if (ret)
+               goto out;
+
+       ret = register_ftrace_graph(&fgraph_ops);
+       if (ret) {
+               warn_failed_init_tracer(trace, ret);
+               goto out;
+       }
+
+       DYN_FTRACE_TEST_NAME();
+
+       count = 0;
+
+       tracing_stop();
+       /* check the trace buffer */
+       ret = trace_test_buffer(&tr->array_buffer, &count);
+
+       unregister_ftrace_graph(&fgraph_ops);
+
+       ret = unregister_ftrace_direct((unsigned long) DYN_FTRACE_TEST_NAME,
+                                      (unsigned long) trace_direct_tramp);
+       if (ret)
+               goto out;
+
+       tracing_start();
 
+       if (!ret && !count) {
+               ret = -1;
+               goto out;
+       }
+#endif
+
+       /* Don't test dynamic tracing, the function tracer already did */
 out:
        /* Stop it if we failed */
        if (ret)