ftracetest: Add kprobes on ftrace testcase

Add a kprobes on ftrace testcase. The testcase verifies that
- enabling and disabling function tracing works on a function which
  already contains a dynamic kprobe
- adding and removing a dynamic kprobe works on a function which is
  already enabled for function tracing

Link: http://lkml.kernel.org/p/1413802323-5297-2-git-send-email-heiko.carstens@de.ibm.comAcked-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

tools/testing/selftests/ftrace/test.d/kprobe/kprobe_ftrace.tc

+#!/bin/sh
+# description: Kprobe dynamic event with function tracer
+
+[ -f kprobe_events ] || exit_unsupported # this is configurable
+grep function available_tracers || exit_unsupported # this is configurable
+
+# prepare
+echo nop > current_tracer
+echo do_fork > set_ftrace_filter
+echo 0 > events/enable
+echo > kprobe_events
+echo 'p:testprobe do_fork' > kprobe_events
+
+# kprobe on / ftrace off
+echo 1 > events/kprobes/testprobe/enable
+echo > trace
+( echo "forked")
+grep testprobe trace
+! grep 'do_fork <-' trace
+
+# kprobe on / ftrace on
+echo function > current_tracer
+echo > trace
+( echo "forked")
+grep testprobe trace
+grep 'do_fork <-' trace
+
+# kprobe off / ftrace on
+echo 0 > events/kprobes/testprobe/enable
+echo > trace
+( echo "forked")
+! grep testprobe trace
+grep 'do_fork <-' trace
+
+# kprobe on / ftrace on
+echo 1 > events/kprobes/testprobe/enable
+echo function > current_tracer
+echo > trace
+( echo "forked")
+grep testprobe trace
+grep 'do_fork <-' trace
+
+# kprobe on / ftrace off
+echo nop > current_tracer
+echo > trace
+( echo "forked")
+grep testprobe trace
+! grep 'do_fork <-' trace
+
+# cleanup
+echo nop > current_tracer
+echo > set_ftrace_filter
+echo 0 > events/kprobes/testprobe/enable
+echo > kprobe_events
+echo > trace