On Tue, 14 Dec 2021 08:35:14 +0100
Christophe Leroy [off-list ref] wrote:

quoted

Will continue investigating.
  

trace_selftest_startup_function_graph() calls register_ftrace_direct() 
which returns -ENOSUPP because powerpc doesn't select 
CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS.

Should TEST_DIRECT_TRAMP depend on CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS ?

Yes, that should be:

#if defined(CONFIG_DYNAMIC_FTRACE) && \
    defined(CONFIG_HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS)
#define TEST_DIRECT_TRAMP
noinline __noclone static void trace_direct_tramp(void) { }
#endif


And make it test it with or without the args.

Thanks for finding this.

-- Steve