selftests/ftrace: Use long for synthetic event probe test

On 32bit the trigger-synthetic-eprobe.tc selftest fails with the error:

hist:syscalls:sys_exit_openat: error: Param type doesn't match synthetic event field type
Command: hist:keys=common_pid:filename=$__arg__1,ret=ret:onmatch(syscalls.sys_enter_openat).trace(synth_open,$filename,$ret)
^
This is because the synth_open synthetic event is created with:

echo "$SYNTH u64 filename; s64 ret;" > synthetic_events

Which works fine on 64 bit, as filename is a pointer and the return is
also a long. But for 32 bit architectures, it doesn't work.

Use "unsigned long" and "long" instead so that it works for both 64 bit
and 32 bit architectures.

Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

selftests/ftrace: fix dynamic_events dependency check

commit 95c104c378dc ("tracing: Auto generate event name when creating a
group of events") changed the syntax in the ftrace README file which is
used by the selftests to check what features are support. Adjust the
string to make test_duplicates.tc and trigger-synthetic-eprobe.tc work
again.

Fixes: 95c104c378dc ("tracing: Auto generate event name when creating a group of events")
Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Acked-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

selftests/ftrace: Add selftest for testing eprobe events on synthetic events

Add a test to test event probes, by creating a synthetic event across
sys_enter_openat and sys_exit_openat that passes the filename pointer from
the enter of the system call to the exit, and then add an event probe to
the synthetic event to make sure that the file name is seen.

Link: https://lore.kernel.org/linux-kselftest/20210819152825.526931866@goodmis.org/
Link: https://lkml.kernel.org/r/20210820204742.463259900@goodmis.org

Cc: "Tzvetomir Stoyanov" <tz.stoyanov@gmail.com>
Cc: Tom Zanussi <zanussi@kernel.org>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Shuah Khan <skhan@linuxfoundation.org>
Cc: linux-kselftest@vger.kernel.org
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>