linux-kernel - Re: [PATCH V4 03/20] rv/include: Add helper functions for deterministic automata

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Date:   Tue, 28 Jun 2022 13:48:33 -0400
From:   Steven Rostedt <rostedt@...dmis.org>
To:     Daniel Bristot de Oliveira <bristot@...nel.org>
Cc:     Wim Van Sebroeck <wim@...ux-watchdog.org>,
        Guenter Roeck <linux@...ck-us.net>,
        Jonathan Corbet <corbet@....net>,
        Ingo Molnar <mingo@...hat.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Peter Zijlstra <peterz@...radead.org>,
        Will Deacon <will@...nel.org>,
        Catalin Marinas <catalin.marinas@....com>,
        Marco Elver <elver@...gle.com>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        "Paul E. McKenney" <paulmck@...nel.org>,
        Shuah Khan <skhan@...uxfoundation.org>,
        Gabriele Paoloni <gpaoloni@...hat.com>,
        Juri Lelli <juri.lelli@...hat.com>,
        Clark Williams <williams@...hat.com>,
        linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-trace-devel@...r.kernel.org
Subject: Re: [PATCH V4 03/20] rv/include: Add helper functions for
 deterministic automata

On Thu, 16 Jun 2022 10:44:45 +0200
Daniel Bristot de Oliveira <bristot@...nel.org> wrote:

> 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 occurrence 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: Wim Van Sebroeck <wim@...ux-watchdog.org>
> Cc: Guenter Roeck <linux@...ck-us.net>
> Cc: Jonathan Corbet <corbet@....net>
> Cc: Steven Rostedt <rostedt@...dmis.org>
> Cc: Ingo Molnar <mingo@...hat.com>
> Cc: Thomas Gleixner <tglx@...utronix.de>
> Cc: Peter Zijlstra <peterz@...radead.org>
> Cc: Will Deacon <will@...nel.org>
> Cc: Catalin Marinas <catalin.marinas@....com>
> Cc: Marco Elver <elver@...gle.com>
> Cc: Dmitry Vyukov <dvyukov@...gle.com>
> Cc: "Paul E. McKenney" <paulmck@...nel.org>
> Cc: Shuah Khan <skhan@...uxfoundation.org>
> Cc: Gabriele Paoloni <gpaoloni@...hat.com>
> Cc: Juri Lelli <juri.lelli@...hat.com>
> Cc: Clark Williams <williams@...hat.com>
> Cc: linux-doc@...r.kernel.org
> Cc: linux-kernel@...r.kernel.org
> Cc: linux-trace-devel@...r.kernel.org
> Signed-off-by: Daniel Bristot de Oliveira <bristot@...nel.org>
> ---
>  include/rv/automata.h | 49 +++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 49 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..0c0aa54bd820
> --- /dev/null
> +++ b/include/rv/automata.h
> @@ -0,0 +1,49 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * Deterministic automata helper functions, to be used with the automata
> + * models in C generated by the dot2k tool.
> + *
> + * Copyright (C) 2019-2022 Daniel Bristot de Oliveira <bristot@...nel.org>

Copyright before the description.

> + */
> +

There should be comments here describing how the helper functions are used.

-- Steve

> +#define DECLARE_AUTOMATA_HELPERS(name, type)					\
> +										\
> +static inline void *model_get_model_##name(void)				\
> +{										\
> +	return (void *) &automaton_##name;					\
> +}										\
> +										\
> +static char *model_get_state_name_##name(enum states_##name state)		\
> +{										\
> +	return automaton_##name.state_names[state];				\
> +}										\
> +										\
> +static 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_##name))		\
> +		return -1;							\
> +										\
> +	if ((event < 0) || (event > event_max_##name))				\
> +		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_##name))				\
> +		return 0;							\
> +										\
> +	return !!automaton_##name.final_states[state];				\
> +}