// 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" (* * File "lock.cat" handles locks and is experimental. * It can be replaced by include "cos.cat" for tests that do not use locks. *) include "lock.cat" (*******************)(* Basic relations *)(*******************) (* Fences *)let rmb = [R \ Noreturn] ; fencerel(Rmb) ; [R \ Noreturn]let wmb = [W] ; fencerel(Wmb) ; [W]let mb = ([M] ; fencerel(Mb) ; [M]) |	([M] ; fencerel(Before-atomic) ; [RMW] ; po? ; [M]) |	([M] ; po? ; [RMW] ; fencerel(After-atomic) ; [M]) |	([M] ; po? ; [LKW] ; fencerel(After-spinlock) ; [M])let gp = po ; [Sync-rcu] ; po? let strong-fence = mb | gp (* Release Acquire *)let acq-po = [Acquire] ; po ; [M]let po-rel = [M] ; po ; [Release]let po-unlock-rf-lock-po = po ; [UL] ; rf ; [LKR] ; po (**********************************)(* Fundamental coherence ordering *)(**********************************) (* Sequential Consistency Per Variable *)let com = rf | co | fracyclic po-loc | com as coherence (* Atomic Read-Modify-Write *)empty rmw & (fre ; coe) as atomic (**********************************)(* Instruction execution ordering *)(**********************************) (* Preserved Program Order *)let dep = addr | datalet rwdep = (dep | ctrl) ; [W]let overwrite = co | frlet to-w = rwdep | (overwrite & int)let to-r = addr | (dep ; rfi)let fence = strong-fence | wmb | po-rel | rmb | acq-polet ppo = to-r | to-w | fence | (po-unlock-rf-lock-po & int) (* Propagation: Ordering from release operations and strong fences. *)let A-cumul(r) = rfe? ; rlet cumul-fence = A-cumul(strong-fence | po-rel) | wmb | po-unlock-rf-lock-polet prop = (overwrite & ext)? ; cumul-fence* ; rfe? (* * Happens Before: Ordering from the passage of time. * No fences needed here for prop because relation confined to one process. *)let hb = ppo | rfe | ((prop \ id) & int)acyclic hb as happens-before (****************************************)(* Write and fence propagation ordering *)(****************************************) (* Propagation: Each non-rf link needs a strong fence. *)let pb = prop ; strong-fence ; hb*acyclic pb as propagation (*******)(* RCU *)(*******) (* * Effect of read-side critical section proceeds from the rcu_read_lock() * onward on the one hand and from the rcu_read_unlock() backwards on the * other hand. *)let rscs = po ; crit^-1 ; po? (* * The synchronize_rcu() strong fence is special in that it can order not * one but two non-rf relations, but only in conjunction with an RCU * read-side critical section. *)let rcu-link = hb* ; pb* ; prop (* * Any sequence containing at least as many grace periods as RCU read-side * critical sections (joined by rcu-link) acts as a generalized strong fence. *)let rec rcu-fence = gp |	(gp ; rcu-link ; rscs) |	(rscs ; rcu-link ; gp) |	(gp ; rcu-link ; rcu-fence ; rcu-link ; rscs) |	(rscs ; rcu-link ; rcu-fence ; rcu-link ; gp) |	(rcu-fence ; rcu-link ; rcu-fence) (* rb orders instructions just as pb does *)let rb = prop ; rcu-fence ; hb* ; pb* irreflexive rb as rcu (* * The happens-before, propagation, and rcu constraints are all * expressions of temporal ordering.  They could be replaced by * a single constraint on an "executes-before" relation, xb: * * let xb = hb | pb | rb * acyclic xb as executes-before *)