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>

tracing: switch to kernel_clone()

The old _do_fork() helper is removed in favor of the new kernel_clone() helper.
The latter adheres to naming conventions for kernel internal syscall helpers.

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
Cc: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Cc: Alexandre Chartre <alexandre.chartre@oracle.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Xiao Yang <yangx.jy@cn.fujitsu.com>
Cc: Tom Zanussi <zanussi@kernel.org>
Cc: linux-doc@vger.kernel.org
Cc: linux-kselftest@vger.kernel.org
Link: https://lore.kernel.org/r/20200819104655.436656-11-christian.brauner@ubuntu.com

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

Add ":README" suffix support for the requires list, so that
the testcase can list up the required string for README file
to the requires list.

Note that the required string is treated as a fixed string,
instead of regular expression. Also, the testcase can specify
a string containing spaces with quotes. E.g.

# requires: "place: [<module>:]<symbol>":README

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: Add a testcase for kprobe multiprobe event

Add a testcase for kprobe event with multi-probe.

Link: http://lkml.kernel.org/r/156095692637.28024.17188971794698768977.stgit@devnote2

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>