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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>
This commit is contained in:
Jiri Olsa 2021-10-08 11:13:32 +02:00 committed by Steven Rostedt (VMware)
parent 0c0593b45c
commit 130c080658
1 changed files with 53 additions and 1 deletions
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54
kernel/trace/trace_selftest.c
View File

@ -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)