[RFC PATCH 03/16] rv/include: Add helper functions for deterministic automata

From: Daniel Bristot de Oliveira
Date: Wed May 19 2021 - 07:37:54 EST


Formally, a deterministic automaton, denoted by G, is defined as a
quintuple:

G = { X, E, f, x_0, X_m }

where:
- X is the set of states;
- E is the finite set of events;
- x_0 is the initial state;
- X_m (subset of X) is the set of marked states.
- f : X x E -> X $ is the transition function. It defines the
state transition in the occurrence of a event from E in
the state X. In the special case of deterministic automata,
the occurence of the event in E in a state in X has a
deterministic next state from X.

An automaton can also be represented using a graphical format of
vertices (nodes) and edges. The open-source tool Graphviz can produce
this graphic format using the (textual) DOT language as the source code.

The dot2c tool presented in this paper:

DE OLIVEIRA, Daniel Bristot; CUCINOTTA, Tommaso; DE OLIVEIRA, Romulo
Silva. Efficient formal verification for the Linux kernel. In:
International Conference on Software Engineering and Formal Methods.
Springer, Cham, 2019. p. 315-332.

Translates a deterministic automaton in the DOT format into a C
source code representation that to be used for monitoring.

This header file implements helper functions to facilitate the usage
of the C output from dot2c for monitoring.

Cc: Jonathan Corbet <corbet@xxxxxxx>
Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Mauro Carvalho Chehab <mchehab@xxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Will Deacon <will@xxxxxxxxxx>
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: "Paul E. McKenney" <paulmck@xxxxxxxxxx>
Cc: Joel Fernandes <joel@xxxxxxxxxxxxxxxxx>
Cc: Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxxxx>
Cc: Gabriele Paoloni <gabriele.paoloni@xxxxxxxxx>
Cc: Juri Lelli <juri.lelli@xxxxxxxxxx>
Cc: Clark Williams <williams@xxxxxxxxxx>
Cc: linux-doc@xxxxxxxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
Signed-off-by: Daniel Bristot de Oliveira <bristot@xxxxxxxxxx>
---
include/rv/automata.h | 52 +++++++++++++++++++++++++++++++++++++++++++
1 file changed, 52 insertions(+)
create mode 100644 include/rv/automata.h

diff --git a/include/rv/automata.h b/include/rv/automata.h
new file mode 100644
index 000000000000..b95941bf78ac
--- /dev/null
+++ b/include/rv/automata.h
@@ -0,0 +1,52 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Deterministic automata helper functions, to be used with the automata
+ * models in C generated by the dot2k tool.
+ *
+ * The dot2k tool is available at https://gitlab.com/linux-rv-tools/dot2/.
+ *
+ * Copyright (C) 2019-2021 Daniel Bristot de Oliveira <bristot@xxxxxxxxxx>
+ */
+
+#define DECLARE_AUTOMATA_HELPERS(name, type) \
+ \
+static inline void *model_get_model_##name(void) \
+{ \
+ return (void *) &automaton_##name; \
+} \
+ \
+char *model_get_state_name_##name(enum states_##name state) \
+{ \
+ return automaton_##name.state_names[state]; \
+} \
+ \
+char *model_get_event_name_##name(enum events_##name event) \
+{ \
+ return automaton_##name.event_names[event]; \
+} \
+ \
+static inline type model_get_init_state_##name(void) \
+{ \
+ return automaton_##name.initial_state; \
+} \
+ \
+static inline type \
+model_get_next_state_##name(enum states_##name curr_state, \
+ enum events_##name event) \
+{ \
+ if ((curr_state < 0) || (curr_state > state_max)) \
+ return -1; \
+ \
+ if ((event < 0) || (event > event_max)) \
+ return -1; \
+ \
+ return automaton_##name.function[curr_state][event]; \
+} \
+ \
+static inline bool model_is_final_state_##name(enum states_##name state) \
+{ \
+ if ((state < 0) || (state > state_max)) \
+ return 0; \
+ \
+ return !!automaton_##name.final_states[state]; \
+}
--
2.26.2