selftests/ftrace: Add selftest for testing duplicate eprobes and kprobes

Add a selftest that makes sure that eprobes and kprobes can not be created
with the same group and name as existing events.

Link: https://lore.kernel.org/linux-kselftest/20210819152825.715290342@goodmis.org/
Link: https://lkml.kernel.org/r/20210820204742.653288346@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>

tools/testing/selftests/ftrace/test.d/dynevent/test_duplicates.tc

+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0
+# description: Generic dynamic event - check if duplicate events are caught
+# requires: dynamic_events "e[:[<group>/]<event>] <attached-group>.<attached-event> [<args>]":README
+
+echo 0 > events/enable
+
+HAVE_KPROBES=0
+
+if [ -f kprobe_events ]; then
+	HAVE_KPROBES=1
+fi
+
+clear_dynamic_events
+
+# first create dynamic events for eprobes and kprobes.
+
+echo 'e:egroup/eevent syscalls/sys_enter_openat file=+0($filename):ustring' >> dynamic_events
+
+# Test eprobe for same eprobe, existing kprobe and existing event
+! echo 'e:egroup/eevent syscalls/sys_enter_openat file=+0($filename):ustring' >> dynamic_events
+! echo 'e:syscalls/sys_enter_open syscalls/sys_enter_openat file=+0($filename):ustring' >> dynamic_events
+
+if [ $HAVE_KPROBES -eq 1 ]; then
+    echo 'p:kgroup/kevent vfs_open file=+0($arg2)' >> dynamic_events
+    ! echo 'e:kgroup/kevent syscalls/sys_enter_openat file=+0($filename):ustring' >> dynamic_events
+
+# Test kprobe for same kprobe, existing eprobe and existing event
+    ! echo 'p:kgroup/kevent vfs_open file=+0($arg2)' >> dynamic_events
+    ! echo 'p:egroup/eevent vfs_open file=+0($arg2)' >> dynamic_events
+    ! echo 'p:syscalls/sys_enter_open vfs_open file=+0($arg2)' >> dynamic_events
+
+    echo '-:kgroup/kevent' >> dynamic_events
+fi
+
+echo '-:egroup/eevent' >> dynamic_events
+
+clear_trace