rv: Add runtime reactors interface

A runtime monitor can cause a reaction to the detection of an
exception on the model's execution. By default, the monitors have
tracing reactions, printing the monitor output via tracepoints.
But other reactions can be added (on-demand) via this interface.

The user interface resembles the kernel tracing interface and
presents these files:

"available_reactors"
  - Reading shows the available reactors, one per line.

   For example:
     # cat available_reactors
     nop
     panic
     printk

 "reacting_on"
   - It is an on/off general switch for reactors, disabling
   all reactions.

 "monitors/MONITOR/reactors"
   - List available reactors, with the select reaction for the given
   MONITOR inside []. The default one is the nop (no operation)
   reactor.
   - Writing the name of a reactor enables it to the given
   MONITOR.

   For example:
     # cat monitors/wip/reactors
     [nop]
     panic
     printk
     # echo panic > monitors/wip/reactors
     # cat monitors/wip/reactors
     nop
     [panic]
     printk

Link: https://lkml.kernel.org/r/1794eb994637457bdeaa6bad0b8263d2f7eece0c.1659052063.git.bristot@kernel.org

Cc: Wim Van Sebroeck <wim@linux-watchdog.org>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Marco Elver <elver@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: "Paul E. McKenney" <paulmck@kernel.org>
Cc: Shuah Khan <skhan@linuxfoundation.org>
Cc: Gabriele Paoloni <gpaoloni@redhat.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Clark Williams <williams@redhat.com>
Cc: Tao Zhou <tao.zhou@linux.dev>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: linux-doc@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-trace-devel@vger.kernel.org
Signed-off-by: Daniel Bristot de Oliveira <bristot@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

1 files changed, 17 insertions, 0 deletions

diff --git a/include/linux/rv.h b/include/linux/rv.h
index d8fa9e8be94a..dcce56987cf7 100644
--- a/include/linux/rv.h
+++ b/include/linux/rv.h
@@ -24,6 +24,14 @@
 union rv_task_monitor {
 };
 
+#ifdef CONFIG_RV_REACTORS
+struct rv_reactor {
+	const char		*name;
+	const char		*description;
+	void			(*react)(char *msg);
+};
+#endif
+
 struct rv_monitor {
 	const char		*name;
 	const char		*description;
@@ -31,6 +39,9 @@ struct rv_monitor {
 	int			(*enable)(void);
 	void			(*disable)(void);
 	void			(*reset)(void);
+#ifdef CONFIG_RV_REACTORS
+	void			(*react)(char *msg);
+#endif
 };
 
 bool rv_monitoring_on(void);
@@ -39,5 +50,11 @@ int rv_register_monitor(struct rv_monitor *monitor);
 int rv_get_task_monitor_slot(void);
 void rv_put_task_monitor_slot(int slot);
 
+#ifdef CONFIG_RV_REACTORS
+bool rv_reacting_on(void);
+int rv_unregister_reactor(struct rv_reactor *reactor);
+int rv_register_reactor(struct rv_reactor *reactor);
+#endif /* CONFIG_RV_REACTORS */
+
 #endif /* CONFIG_RV */
 #endif /* _LINUX_RV_H */