rv/include: Add deterministic automata monitor definition via C macros

In Linux terms, the runtime verification monitors are encapsulated
inside the "RV monitor" abstraction. The "RV monitor" includes a set
of instances of the monitor (per-cpu monitor, per-task monitor, and
so on), the helper functions that glue the monitor to the system
reference model, and the trace output as a reaction for event parsing
and exceptions, as depicted below:

Linux +----- RV Monitor ----------------------------------+ Formal
Realm | | Realm
+-------------------+ +----------------+ +-----------------+
| Linux kernel | | Monitor | | Reference |
| Tracing | -> | Instance(s) | <- | Model |
| (instrumentation) | | (verification) | | (specification) |
+-------------------+ +----------------+ +-----------------+
| | |
| V |
| +----------+ |
| | Reaction | |
| +--+--+--+-+ |
| | | | |
| | | +-> trace output ? |
+------------------------|--|----------------------+
| +----> panic ?
+-------> <user-specified>

Add the rv/da_monitor.h, enabling automatic code generation for the
*Monitor Instance(s)* using C macros, and code to support it.

The benefits of the usage of macro for monitor synthesis are 3-fold as it:

- Reduces the code duplication;
- Facilitates the bug fix/improvement;
- Avoids the case of developers changing the core of the monitor code
to manipulate the model in a (let's say) non-standard way.

This initial implementation presents three different types of monitor
instances:

- DECLARE_DA_MON_GLOBAL(name, type)
- DECLARE_DA_MON_PER_CPU(name, type)
- DECLARE_DA_MON_PER_TASK(name, type)

The first declares the functions for a global deterministic automata monitor,
the second for monitors with per-cpu instances, and the third with per-task
instances.

Link: https://lkml.kernel.org/r/[e-mail]

Cc: Wim Van Sebroeck <[e-mail]>
Cc: Guenter Roeck <[e-mail]>
Cc: Jonathan Corbet <[e-mail]>
Cc: Ingo Molnar <[e-mail]>
Cc: Thomas Gleixner <[e-mail]>
Cc: Peter Zijlstra <[e-mail]>
Cc: Will Deacon <[e-mail]>
Cc: Catalin Marinas <[e-mail]>
Cc: Marco Elver <[e-mail]>
Cc: Dmitry Vyukov <[e-mail]>
Cc: "Paul E. McKenney" <[e-mail]>
Cc: Shuah Khan <[e-mail]>
Cc: Gabriele Paoloni <[e-mail]>
Cc: Juri Lelli <[e-mail]>
Cc: Clark Williams <[e-mail]>
Cc: Tao Zhou <[e-mail]>
Cc: Randy Dunlap <[e-mail]>
Cc: [e-mail]
Cc: [e-mail]
Cc: [e-mail]
Signed-off-by: Daniel Bristot de Oliveira <[e-mail]>
Signed-off-by: Steven Rostedt (Google) <[e-mail]>

include/linux/rv.h

···
 #ifndef _LINUX_RV_H
 #define _LINUX_RV_H
 
+#define MAX_DA_NAME_LEN	24
+
 #ifdef CONFIG_RV
+/*
+ * Deterministic automaton per-object variables.
+ */
+struct da_monitor {
+	bool		monitoring;
+	unsigned int	curr_state;
+};
 
 /*
  * Per-task RV monitors count. Nowadays fixed in RV_PER_TASK_MONITORS.
···
  * Futher monitor types are expected, so make this a union.
  */
 union rv_task_monitor {
+	struct da_monitor da_mon;
 };
 
 #ifdef CONFIG_RV_REACTORS

include/rv/da_monitor.h

···
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2019-2022 Red Hat, Inc. Daniel Bristot de Oliveira <[e-mail]>
+ *
+ * Deterministic automata (DA) monitor functions, to be used together
+ * with automata models in C generated by the dot2k tool.
+ *
+ * The dot2k tool is available at tools/verification/dot2k/
+ */
+
+#include <rv/automata.h>
+#include <linux/rv.h>
+#include <linux/bug.h>
+
+#ifdef CONFIG_RV_REACTORS
+
+#define DECLARE_RV_REACTING_HELPERS(name, type)							\
+static char REACT_MSG_##name[1024];								\
+												\
+static inline char *format_react_msg_##name(type curr_state, type event)			\
+{												\
+	snprintf(REACT_MSG_##name, 1024,							\
+		 "rv: monitor %s does not allow event %s on state %s\n",			\
+		 #name,										\
+		 model_get_event_name_##name(event),						\
+		 model_get_state_name_##name(curr_state));					\
+	return REACT_MSG_##name;								\
+}												\
+												\
+static void cond_react_##name(char *msg)							\
+{												\
+	if (rv_##name.react)									\
+		rv_##name.react(msg);								\
+}												\
+												\
+static bool rv_reacting_on_##name(void)								\
+{												\
+	return rv_reacting_on();								\
+}
+
+#else /* CONFIG_RV_REACTOR */
+
+#define DECLARE_RV_REACTING_HELPERS(name, type)							\
+static inline char *format_react_msg_##name(type curr_state, type event)			\
+{												\
+	return NULL;										\
+}												\
+												\
+static void cond_react_##name(char *msg)							\
+{												\
+	return;											\
+}												\
+												\
+static bool rv_reacting_on_##name(void)								\
+{												\
+	return 0;										\
+}
+#endif
+
+/*
+ * Generic helpers for all types of deterministic automata monitors.
+ */
+#define DECLARE_DA_MON_GENERIC_HELPERS(name, type)						\
+												\
+DECLARE_RV_REACTING_HELPERS(name, type)								\
+												\
+/*												\
+ * da_monitor_reset_##name - reset a monitor and setting it to init state			\
+ */												\
+static inline void da_monitor_reset_##name(struct da_monitor *da_mon)				\
+{												\
+	da_mon->monitoring = 0;									\
+	da_mon->curr_state = model_get_initial_state_##name();					\
+}												\
+												\
+/*												\
+ * da_monitor_curr_state_##name - return the current state					\
+ */												\
+static inline type da_monitor_curr_state_##name(struct da_monitor *da_mon)			\
+{												\
+	return da_mon->curr_state;								\
+}												\
+												\
+/*												\
+ * da_monitor_set_state_##name - set the new current state					\
+ */												\
+static inline void										\
+da_monitor_set_state_##name(struct da_monitor *da_mon, enum states_##name state)		\
+{												\
+	da_mon->curr_state = state;								\
+}												\
+												\
+/*												\
+ * da_monitor_start_##name - start monitoring							\
+ *												\
+ * The monitor will ignore all events until monitoring is set to true. This			\
+ * function needs to be called to tell the monitor to start monitoring.				\
+ */												\
+static inline void da_monitor_start_##name(struct da_monitor *da_mon)				\
+{												\
+	da_mon->curr_state = model_get_initial_state_##name();					\
+	da_mon->monitoring = 1;									\
+}												\
+												\
+/*												\
+ * da_monitoring_##name - returns true if the monitor is processing events			\
+ */												\
+static inline bool da_monitoring_##name(struct da_monitor *da_mon)				\
+{												\
+	return da_mon->monitoring;								\
+}												\
+												\
+/*												\
+ * da_monitor_enabled_##name - checks if the monitor is enabled					\
+ */												\
+static inline bool da_monitor_enabled_##name(void)						\
+{												\
+	/* global switch */									\
+	if (unlikely(!rv_monitoring_on()))							\
+		return 0;									\
+												\
+	/* monitor enabled */									\
+	if (unlikely(!rv_##name.enabled))							\
+		return 0;									\
+												\
+	return 1;										\
+}												\
+												\
+/*												\
+ * da_monitor_handling_event_##name - checks if the monitor is ready to handle events		\
+ */												\
+static inline bool da_monitor_handling_event_##name(struct da_monitor *da_mon)			\
+{												\
+												\
+	if (!da_monitor_enabled_##name())							\
+		return 0;									\
+												\
+	/* monitor is actually monitoring */							\
+	if (unlikely(!da_monitoring_##name(da_mon)))						\
+		return 0;									\
+												\
+	return 1;										\
+}
+
+/*
+ * Event handler for implicit monitors. Implicit monitor is the one which the
+ * handler does not need to specify which da_monitor to manipulate. Examples
+ * of implicit monitor are the per_cpu or the global ones.
+ */
+#define DECLARE_DA_MON_MODEL_HANDLER_IMPLICIT(name, type)					\
+												\
+static inline bool										\
+da_event_##name(struct da_monitor *da_mon, enum events_##name event)				\
+{												\
+	type curr_state = da_monitor_curr_state_##name(da_mon);					\
+	type next_state = model_get_next_state_##name(curr_state, event);			\
+												\
+	if (next_state != INVALID_STATE) {							\
+		da_monitor_set_state_##name(da_mon, next_state);				\
+												\
+		trace_event_##name(model_get_state_name_##name(curr_state),			\
+				   model_get_event_name_##name(event),				\
+				   model_get_state_name_##name(next_state),			\
+				   model_is_final_state_##name(next_state));			\
+												\
+		return true;									\
+	}											\
+												\
+	if (rv_reacting_on_##name())								\
+		cond_react_##name(format_react_msg_##name(curr_state, event));			\
+												\
+	trace_error_##name(model_get_state_name_##name(curr_state),				\
+			   model_get_event_name_##name(event));					\
+												\
+	return false;										\
+}												\
+
+/*
+ * Event handler for per_task monitors.
+ */
+#define DECLARE_DA_MON_MODEL_HANDLER_PER_TASK(name, type)					\
+												\
+static inline bool da_event_##name(struct da_monitor *da_mon, struct task_struct *tsk,		\
+				   enum events_##name event)					\
+{												\
+	type curr_state = da_monitor_curr_state_##name(da_mon);					\
+	type next_state = model_get_next_state_##name(curr_state, event);			\
+												\
+	if (next_state != INVALID_STATE) {							\
+		da_monitor_set_state_##name(da_mon, next_state);				\
+												\
+		trace_event_##name(tsk->pid,							\
+				   model_get_state_name_##name(curr_state),			\
+				   model_get_event_name_##name(event),				\
+				   model_get_state_name_##name(next_state),			\
+				   model_is_final_state_##name(next_state));			\
+												\
+		return true;									\
+	}											\
+												\
+	if (rv_reacting_on_##name())								\
+		cond_react_##name(format_react_msg_##name(curr_state, event));			\
+												\
+	trace_error_##name(tsk->pid,								\
+			   model_get_state_name_##name(curr_state),				\
+			   model_get_event_name_##name(event));					\
+												\
+	return false;										\
+}
+
+/*
+ * Functions to define, init and get a global monitor.
+ */
+#define DECLARE_DA_MON_INIT_GLOBAL(name, type)							\
+												\
+/*												\
+ * global monitor (a single variable)								\
+ */												\
+static struct da_monitor da_mon_##name;								\
+												\
+/*												\
+ * da_get_monitor_##name - return the global monitor address					\
+ */												\
+static struct da_monitor *da_get_monitor_##name(void)						\
+{												\
+	return &da_mon_##name;									\
+}												\
+												\
+/*												\
+ * da_monitor_reset_all_##name - reset the single monitor					\
+ */												\
+static void da_monitor_reset_all_##name(void)							\
+{												\
+	da_monitor_reset_##name(da_get_monitor_##name());					\
+}												\
+												\
+/*												\
+ * da_monitor_init_##name - initialize a monitor						\
+ */												\
+static inline int da_monitor_init_##name(void)							\
+{												\
+	da_monitor_reset_all_##name();								\
+	return 0;										\
+}												\
+												\
+/*												\
+ * da_monitor_destroy_##name - destroy the monitor						\
+ */												\
+static inline void da_monitor_destroy_##name(void)						\
+{												\
+	return;											\
+}
+
+/*
+ * Functions to define, init and get a per-cpu monitor.
+ */
+#define DECLARE_DA_MON_INIT_PER_CPU(name, type)							\
+												\
+/*												\
+ * per-cpu monitor variables									\
+ */												\
+DEFINE_PER_CPU(struct da_monitor, da_mon_##name);						\
+												\
+/*												\
+ * da_get_monitor_##name - return current CPU monitor address					\
+ */												\
+static struct da_monitor *da_get_monitor_##name(void)						\
+{												\
+	return this_cpu_ptr(&da_mon_##name);							\
+}												\
+												\
+/*												\
+ * da_monitor_reset_all_##name - reset all CPUs' monitor					\
+ */												\
+static void da_monitor_reset_all_##name(void)							\
+{												\
+	struct da_monitor *da_mon;								\
+	int cpu;										\
+	for_each_cpu(cpu, cpu_online_mask) {							\
+		da_mon = per_cpu_ptr(&da_mon_##name, cpu);					\
+		da_monitor_reset_##name(da_mon);						\
+	}											\
+}												\
+												\
+/*												\
+ * da_monitor_init_##name - initialize all CPUs' monitor					\
+ */												\
+static inline int da_monitor_init_##name(void)							\
+{												\
+	da_monitor_reset_all_##name();								\
+	return 0;										\
+}												\
+												\
+/*												\
+ * da_monitor_destroy_##name - destroy the monitor						\
+ */												\
+static inline void da_monitor_destroy_##name(void)						\
+{												\
+	return;											\
+}
+
+/*
+ * Functions to define, init and get a per-task monitor.
+ */
+#define DECLARE_DA_MON_INIT_PER_TASK(name, type)						\
+												\
+/*												\
+ * The per-task monitor is stored a vector in the task struct. This variable			\
+ * stores the position on the vector reserved for this monitor.					\
+ */												\
+static int task_mon_slot_##name = RV_PER_TASK_MONITOR_INIT;					\
+												\
+/*												\
+ * da_get_monitor_##name - return the monitor in the allocated slot for tsk 			\
+ */												\
+static inline struct da_monitor *da_get_monitor_##name(struct task_struct *tsk)			\
+{												\
+	return &tsk->rv[task_mon_slot_##name].da_mon;						\
+}												\
+												\
+static void da_monitor_reset_all_##name(void)							\
+{												\
+	struct task_struct *g, *p;								\
+												\
+	read_lock(&tasklist_lock);								\
+	for_each_process_thread(g, p)								\
+		da_monitor_reset_##name(da_get_monitor_##name(p));				\
+	read_unlock(&tasklist_lock);								\
+}												\
+												\
+/*												\
+ * da_monitor_init_##name - initialize the per-task monitor					\
+ *												\
+ * Try to allocate a slot in the task's vector of monitors. If there				\
+ * is an available slot, use it and reset all task's monitor.					\
+ */												\
+static int da_monitor_init_##name(void)								\
+{												\
+	int slot;										\
+												\
+	slot = rv_get_task_monitor_slot();							\
+	if (slot < 0 || slot >= RV_PER_TASK_MONITOR_INIT)					\
+		return slot;									\
+												\
+	task_mon_slot_##name = slot;								\
+												\
+	da_monitor_reset_all_##name();								\
+	return 0;										\
+}												\
+												\
+/*												\
+ * da_monitor_destroy_##name - return the allocated slot					\
+ */												\
+static inline void da_monitor_destroy_##name(void)						\
+{												\
+	if (task_mon_slot_##name == RV_PER_TASK_MONITOR_INIT) {					\
+		WARN_ONCE(1, "Disabling a disabled monitor: " #name);				\
+		return;										\
+	}											\
+	rv_put_task_monitor_slot(task_mon_slot_##name);						\
+	task_mon_slot_##name = RV_PER_TASK_MONITOR_INIT;					\
+	return;											\
+}
+
+/*
+ * Handle event for implicit monitor: da_get_monitor_##name() will figure out
+ * the monitor.
+ */
+#define DECLARE_DA_MON_MONITOR_HANDLER_IMPLICIT(name, type)					\
+												\
+static inline void __da_handle_event_##name(struct da_monitor *da_mon,				\
+					    enum events_##name event)				\
+{												\
+	bool retval;										\
+												\
+	retval = da_event_##name(da_mon, event);						\
+	if (!retval)										\
+		da_monitor_reset_##name(da_mon);						\
+}												\
+												\
+/*												\
+ * da_handle_event_##name - handle an event							\
+ */												\
+static inline void da_handle_event_##name(enum events_##name event)				\
+{												\
+	struct da_monitor *da_mon = da_get_monitor_##name();					\
+	bool retval;										\
+												\
+	retval = da_monitor_handling_event_##name(da_mon);					\
+	if (!retval)										\
+		return;										\
+												\
+	__da_handle_event_##name(da_mon, event);						\
+}												\
+												\
+/*												\
+ * da_handle_start_event_##name - start monitoring or handle event				\
+ *												\
+ * This function is used to notify the monitor that the system is returning			\
+ * to the initial state, so the monitor can start monitoring in the next event.			\
+ * Thus:											\
+ *												\
+ * If the monitor already started, handle the event.						\
+ * If the monitor did not start yet, start the monitor but skip the event.			\
+ */												\
+static inline bool da_handle_start_event_##name(enum events_##name event)			\
+{												\
+	struct da_monitor *da_mon;								\
+												\
+	if (!da_monitor_enabled_##name())							\
+		return 0;									\
+												\
+	da_mon = da_get_monitor_##name();							\
+												\
+	if (unlikely(!da_monitoring_##name(da_mon))) {						\
+		da_monitor_start_##name(da_mon);						\
+		return 0;									\
+	}											\
+												\
+	__da_handle_event_##name(da_mon, event);						\
+												\
+	return 1;										\
+}												\
+												\
+/*												\
+ * da_handle_start_run_event_##name - start monitoring and handle event				\
+ *												\
+ * This function is used to notify the monitor that the system is in the			\
+ * initial state, so the monitor can start monitoring and handling event.			\
+ */												\
+static inline bool da_handle_start_run_event_##name(enum events_##name event)			\
+{												\
+	struct da_monitor *da_mon;								\
+												\
+	if (!da_monitor_enabled_##name())							\
+		return 0;									\
+												\
+	da_mon = da_get_monitor_##name();							\
+												\
+	if (unlikely(!da_monitoring_##name(da_mon)))						\
+		da_monitor_start_##name(da_mon);						\
+												\
+	__da_handle_event_##name(da_mon, event);						\
+												\
+	return 1;										\
+}
+
+/*
+ * Handle event for per task.
+ */
+#define DECLARE_DA_MON_MONITOR_HANDLER_PER_TASK(name, type)					\
+												\
+static inline void										\
+__da_handle_event_##name(struct da_monitor *da_mon, struct task_struct *tsk,			\
+			 enum events_##name event)						\
+{												\
+	bool retval;										\
+												\
+	retval = da_event_##name(da_mon, tsk, event);						\
+	if (!retval)										\
+		da_monitor_reset_##name(da_mon);						\
+}												\
+												\
+/*												\
+ * da_handle_event_##name - handle an event							\
+ */												\
+static inline void										\
+da_handle_event_##name(struct task_struct *tsk, enum events_##name event)			\
+{												\
+	struct da_monitor *da_mon = da_get_monitor_##name(tsk);					\
+	bool retval;										\
+												\
+	retval = da_monitor_handling_event_##name(da_mon);					\
+	if (!retval)										\
+		return;										\
+												\
+	__da_handle_event_##name(da_mon, tsk, event);						\
+}												\
+												\
+/*												\
+ * da_handle_start_event_##name - start monitoring or handle event				\
+ *												\
+ * This function is used to notify the monitor that the system is returning			\
+ * to the initial state, so the monitor can start monitoring in the next event.			\
+ * Thus:											\
+ *												\
+ * If the monitor already started, handle the event.						\
+ * If the monitor did not start yet, start the monitor but skip the event.			\
+ */												\
+static inline bool										\
+da_handle_start_event_##name(struct task_struct *tsk, enum events_##name event)			\
+{												\
+	struct da_monitor *da_mon;								\
+												\
+	if (!da_monitor_enabled_##name())							\
+		return 0;									\
+												\
+	da_mon = da_get_monitor_##name(tsk);							\
+												\
+	if (unlikely(!da_monitoring_##name(da_mon))) {						\
+		da_monitor_start_##name(da_mon);						\
+		return 0;									\
+	}											\
+												\
+	__da_handle_event_##name(da_mon, tsk, event);						\
+												\
+	return 1;										\
+}
+
+/*
+ * Entry point for the global monitor.
+ */
+#define DECLARE_DA_MON_GLOBAL(name, type)							\
+												\
+DECLARE_AUTOMATA_HELPERS(name, type)								\
+DECLARE_DA_MON_GENERIC_HELPERS(name, type)							\
+DECLARE_DA_MON_MODEL_HANDLER_IMPLICIT(name, type)						\
+DECLARE_DA_MON_INIT_GLOBAL(name, type)								\
+DECLARE_DA_MON_MONITOR_HANDLER_IMPLICIT(name, type)
+
+/*
+ * Entry point for the per-cpu monitor.
+ */
+#define DECLARE_DA_MON_PER_CPU(name, type)							\
+												\
+DECLARE_AUTOMATA_HELPERS(name, type)								\
+DECLARE_DA_MON_GENERIC_HELPERS(name, type)							\
+DECLARE_DA_MON_MODEL_HANDLER_IMPLICIT(name, type)						\
+DECLARE_DA_MON_INIT_PER_CPU(name, type)								\
+DECLARE_DA_MON_MONITOR_HANDLER_IMPLICIT(name, type)
+
+/*
+ * Entry point for the per-task monitor.
+ */
+#define DECLARE_DA_MON_PER_TASK(name, type)							\
+												\
+DECLARE_AUTOMATA_HELPERS(name, type)								\
+DECLARE_DA_MON_GENERIC_HELPERS(name, type)							\
+DECLARE_DA_MON_MODEL_HANDLER_PER_TASK(name, type)						\
+DECLARE_DA_MON_INIT_PER_TASK(name, type)							\
+DECLARE_DA_MON_MONITOR_HANDLER_PER_TASK(name, type)

include/trace/events/rv.h

···
+/* SPDX-License-Identifier: GPL-2.0 */
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM rv
+
+#if !defined(_TRACE_RV_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_RV_H
+
+#include <linux/rv.h>
+#include <linux/tracepoint.h>
+
+#ifdef CONFIG_DA_MON_EVENTS_IMPLICIT
+DECLARE_EVENT_CLASS(event_da_monitor,
+
+	TP_PROTO(char *state, char *event, char *next_state, bool final_state),
+
+	TP_ARGS(state, event, next_state, final_state),
+
+	TP_STRUCT__entry(
+		__array(	char,	state,		MAX_DA_NAME_LEN	)
+		__array(	char,	event,		MAX_DA_NAME_LEN	)
+		__array(	char,	next_state,	MAX_DA_NAME_LEN	)
+		__field(	bool,	final_state			)
+	),
+
+	TP_fast_assign(
+		memcpy(__entry->state,		state,		MAX_DA_NAME_LEN);
+		memcpy(__entry->event,		event,		MAX_DA_NAME_LEN);
+		memcpy(__entry->next_state,	next_state,	MAX_DA_NAME_LEN);
+		__entry->final_state		= final_state;
+	),
+
+	TP_printk("%s x %s -> %s %s",
+		__entry->state,
+		__entry->event,
+		__entry->next_state,
+		__entry->final_state ? "(final)" : "")
+);
+
+DECLARE_EVENT_CLASS(error_da_monitor,
+
+	TP_PROTO(char *state, char *event),
+
+	TP_ARGS(state, event),
+
+	TP_STRUCT__entry(
+		__array(	char,	state,		MAX_DA_NAME_LEN	)
+		__array(	char,	event,		MAX_DA_NAME_LEN	)
+	),
+
+	TP_fast_assign(
+		memcpy(__entry->state,		state,		MAX_DA_NAME_LEN);
+		memcpy(__entry->event,		event,		MAX_DA_NAME_LEN);
+	),
+
+	TP_printk("event %s not expected in the state %s",
+		__entry->event,
+		__entry->state)
+);
+#endif /* CONFIG_DA_MON_EVENTS_IMPLICIT */
+
+#ifdef CONFIG_DA_MON_EVENTS_ID
+DECLARE_EVENT_CLASS(event_da_monitor_id,
+
+	TP_PROTO(int id, char *state, char *event, char *next_state, bool final_state),
+
+	TP_ARGS(id, state, event, next_state, final_state),
+
+	TP_STRUCT__entry(
+		__field(	int,	id				)
+		__array(	char,	state,		MAX_DA_NAME_LEN	)
+		__array(	char,	event,		MAX_DA_NAME_LEN	)
+		__array(	char,	next_state,	MAX_DA_NAME_LEN	)
+		__field(	bool,	final_state			)
+	),
+
+	TP_fast_assign(
+		memcpy(__entry->state,		state,		MAX_DA_NAME_LEN);
+		memcpy(__entry->event,		event,		MAX_DA_NAME_LEN);
+		memcpy(__entry->next_state,	next_state,	MAX_DA_NAME_LEN);
+		__entry->id			= id;
+		__entry->final_state		= final_state;
+	),
+
+	TP_printk("%d: %s x %s -> %s %s",
+		__entry->id,
+		__entry->state,
+		__entry->event,
+		__entry->next_state,
+		__entry->final_state ? "(final)" : "")
+);
+
+DECLARE_EVENT_CLASS(error_da_monitor_id,
+
+	TP_PROTO(int id, char *state, char *event),
+
+	TP_ARGS(id, state, event),
+
+	TP_STRUCT__entry(
+		__field(	int,	id				)
+		__array(	char,	state,		MAX_DA_NAME_LEN	)
+		__array(	char,	event,		MAX_DA_NAME_LEN	)
+	),
+
+	TP_fast_assign(
+		memcpy(__entry->state,		state,		MAX_DA_NAME_LEN);
+		memcpy(__entry->event,		event,		MAX_DA_NAME_LEN);
+		__entry->id			= id;
+	),
+
+	TP_printk("%d: event %s not expected in the state %s",
+		__entry->id,
+		__entry->event,
+		__entry->state)
+);
+#endif /* CONFIG_DA_MON_EVENTS_ID */
+#endif /* _TRACE_RV_H */
+
+/* This part ust be outside protection */
+#undef TRACE_INCLUDE_PATH
+#include <trace/define_trace.h>

kernel/fork.c

···
 	mutex_unlock(&oom_adj_mutex);
 }
 
+#ifdef CONFIG_RV
+static void rv_task_fork(struct task_struct *p)
+{
+	int i;
+
+	for (i = 0; i < RV_PER_TASK_MONITORS; i++)
+		p->rv[i].da_mon.monitoring = false;
+}
+#else
+#define rv_task_fork(p) do {} while (0)
+#endif
+
 /*
  * This creates a new process as a copy of the old one,
  * but does not actually start it yet.
···
 	 * before holding sighand lock.
 	 */
 	copy_seccomp(p);
+
+	rv_task_fork(p);
 
 	rseq_fork(p, clone_flags);
 

kernel/trace/rv/Kconfig

···
 # SPDX-License-Identifier: GPL-2.0-only
 #
+config DA_MON_EVENTS
+	bool
+
+config DA_MON_EVENTS_IMPLICIT
+	select DA_MON_EVENTS
+	bool
+
+config DA_MON_EVENTS_ID
+	select DA_MON_EVENTS
+	bool
+
 menuconfig RV
 	bool "Runtime Verification"
 	depends on TRACING

kernel/trace/rv/rv.c

···
 #include <linux/init.h>
 #include <linux/slab.h>
 
+#ifdef CONFIG_DA_MON_EVENTS
+#define CREATE_TRACE_POINTS
+#include <trace/events/rv.h>
+#endif
+
 #include "rv.h"
 
 DEFINE_MUTEX(rv_interface_lock);