xref: /openbmc/linux/tools/memory-model/linux-kernel.bell (revision af41db5e)

// SPDX-License-Identifier: GPL-2.0+
(*
 * Copyright (C) 2015 Jade Alglave <j.alglave@ucl.ac.uk>,
 * Copyright (C) 2016 Luc Maranget <luc.maranget@inria.fr> for Inria
 * Copyright (C) 2017 Alan Stern <stern@rowland.harvard.edu>,
 *                    Andrea Parri <parri.andrea@gmail.com>
 *
 * An earlier version of this file appeared in the companion webpage for
 * "Frightening small children and disconcerting grown-ups: Concurrency
 * in the Linux kernel" by Alglave, Maranget, McKenney, Parri, and Stern,
 * which appeared in ASPLOS 2018.
 *)

"Linux-kernel memory consistency model"

enum Accesses = 'once (*READ_ONCE,WRITE_ONCE*) ||
		'release (*smp_store_release*) ||
		'acquire (*smp_load_acquire*) ||
		'noreturn (* R of non-return RMW *)
instructions R[{'once,'acquire,'noreturn}]
instructions W[{'once,'release}]
instructions RMW[{'once,'acquire,'release}]

enum Barriers = 'wmb (*smp_wmb*) ||
		'rmb (*smp_rmb*) ||
		'mb (*smp_mb*) ||
		'rcu-lock (*rcu_read_lock*)  ||
		'rcu-unlock (*rcu_read_unlock*) ||
		'sync-rcu (*synchronize_rcu*) ||
		'before-atomic (*smp_mb__before_atomic*) ||
		'after-atomic (*smp_mb__after_atomic*) ||
		'after-spinlock (*smp_mb__after_spinlock*)
instructions F[Barriers]

(* Compute matching pairs of nested Rcu-lock and Rcu-unlock *)
let matched = let rec
	    unmatched-locks = Rcu-lock \ domain(matched)
	and unmatched-unlocks = Rcu-unlock \ range(matched)
	and unmatched = unmatched-locks | unmatched-unlocks
	and unmatched-po = [unmatched] ; po ; [unmatched]
	and unmatched-locks-to-unlocks =
		[unmatched-locks] ; po ; [unmatched-unlocks]
	and matched = matched | (unmatched-locks-to-unlocks \
		(unmatched-po ; unmatched-po))
	in matched

(* Validate nesting *)
flag ~empty Rcu-lock \ domain(matched) as unbalanced-rcu-locking
flag ~empty Rcu-unlock \ range(matched) as unbalanced-rcu-locking

(* Outermost level of nesting only *)
let crit = matched \ (po^-1 ; matched ; po^-1)