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/51b0bf425a281e226dfeba7401d2115d6091f84e.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, 541 insertions, 0 deletions

diff --git a/include/rv/da_monitor.h b/include/rv/da_monitor.h
new file mode 100644
index 000000000000..001bc298289f
--- /dev/null
+++ b/include/rv/da_monitor.h
@@ -0,0 +1,541 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2019-2022 Red Hat, Inc. Daniel Bristot de Oliveira <bristot@kernel.org>
+ *
+ * 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)