selftests/ftrace: Use $FUNCTION_FORK to reference kernel fork function

Commit cad6967ac108 ("fork: introduce kernel_clone()") replaced "_do_fork()"
with "kernel_clone()". The ftrace selftests reference the fork function in
several of the tests. The rename will make the tests break, but if those
names are changed in the tests, they would then break on older kernels. The
same set of tests should pass older kernels if they have previously passed.
Obviously, a new test may not work on older kernels if the test was added
due to a bug or a new feature.

The setup of ftracetest will now create a $FUNCTION_FORK bash variable
that will contain "_do_fork" for older kernels and "kernel_clone" for newer
ones. It figures out the proper name by examining /proc/kallsyms.

Note, available_filter_functions could also be used, but because some tests
should be able to pass without function tracing enabled, it could not be
used.

Fixes: eea11285dab3 ("tracing: switch to kernel_clone()")
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

selftests/ftrace: Support ":tracer" suffix for requires

Add ":tracer" suffix support for the requires list, so that
the testcase can list up the required tracer (e.g. function)
to the requires list.

For example, if the testcase requires function_graph tracer,
it can write requires list as below instead of checking
available_tracers.

# requires: function_graph:tracer

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Reviewed-by: Tom Zanussi <zanussi@kernel.org>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

selftests/ftrace: Convert check_filter_file() with requires list

Since check_filter_file() is basically checking the filter
tracefs file, we can convert it into requires list.

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Reviewed-by: Tom Zanussi <zanussi@kernel.org>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

selftests/ftrace: Convert required interface checks into requires list

Convert the required tracefs interface checking code with
requires: list.

Fixed merge conflicts in trigger-hist.tc and trigger-trace-marker-hist.tc
Shuah Khan <skhan@linuxfoundation.org>

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Reviewed-by: Tom Zanussi <zanussi@kernel.org>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

selftests/ftrace: Check required filter files before running test

Without CONFIG_DYNAMIC_FTRACE, some tests get failure because required
filter files(set_ftrace_filter/available_filter_functions/stack_trace_filter)
are missing. So implement check_filter_file() and make all related tests
check required filter files by it.

BTW: set_ftrace_filter and available_filter_functions are introduced together
so just check either of them.

Signed-off-by: Xiao Yang <yangx.jy@cn.fujitsu.com>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

selftests/ftrace: Add test to test new set_ftrace_notrace_pid file

A new file was added to the tracing directory that will allow a user to
place a PID into it and the task associated to that PID will not be traced
by the function tracer. If the function-fork option is enabled, then neither
will the children of that task be traced by the function tracer.

Cc: linux-kselftest@vger.kernel.org
Cc: Shuah Khan <skhan@linuxfoundation.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>