// 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 *)(*******************) (* 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 (* Fences *)let R4rmb = R \ Noreturn	(* Reads for which rmb works *)let rmb = [R4rmb] ; fencerel(Rmb) ; [R4rmb]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]) |	([M] ; po ; [UL] ; (co | po) ; [LKW] ;		fencerel(After-unlock-lock) ; [M])let gp = po ; [Sync-rcu | Sync-srcu] ; po?let strong-fence = mb | gp let nonrw-fence = strong-fence | po-rel | acq-polet fence = nonrw-fence | wmb | rmblet barrier = fencerel(Barrier | Rmb | Wmb | Mb | Sync-rcu | Sync-srcu |		Before-atomic | After-atomic | Acquire | Release |		Rcu-lock | Rcu-unlock | Srcu-lock | Srcu-unlock) |	(po ; [Release]) | ([Acquire] ; 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) | (addr ; [Plain] ; wmb)let to-r = addr | (dep ; [Marked] ; rfi)let 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 ; [Marked])? ; rlet cumul-fence = [Marked] ; (A-cumul(strong-fence | po-rel) | wmb |	po-unlock-rf-lock-po) ; [Marked]let prop = [Marked] ; (overwrite & ext)? ; cumul-fence* ;	[Marked] ; rfe? ; [Marked] (* * Happens Before: Ordering from the passage of time. * No fences needed here for prop because relation confined to one process. *)let hb = [Marked] ; (ppo | rfe | ((prop \ id) & int)) ; [Marked]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* ; [Marked]acyclic pb as propagation (*******)(* RCU *)(*******) (* * Effects of read-side critical sections proceed from the rcu_read_unlock() * or srcu_read_unlock() backwards on the one hand, and from the * rcu_read_lock() or srcu_read_lock() forwards on the other hand. * * In the definition of rcu-fence below, the po term at the left-hand side * of each disjunct and the po? term at the right-hand end have been factored * out.  They have been moved into the definitions of rcu-link and rb. * This was necessary in order to apply the "& loc" tests correctly. *)let rcu-gp = [Sync-rcu]		(* Compare with gp *)let srcu-gp = [Sync-srcu]let rcu-rscsi = rcu-rscs^-1let srcu-rscsi = srcu-rscs^-1 (* * 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 = po? ; hb* ; pb* ; prop ; po (* * Any sequence containing at least as many grace periods as RCU read-side * critical sections (joined by rcu-link) induces order like a generalized * inter-CPU strong fence. * Likewise for SRCU grace periods and read-side critical sections, provided * the synchronize_srcu() and srcu_read_[un]lock() calls refer to the same * struct srcu_struct location. *)let rec rcu-order = rcu-gp | srcu-gp |	(rcu-gp ; rcu-link ; rcu-rscsi) |	((srcu-gp ; rcu-link ; srcu-rscsi) & loc) |	(rcu-rscsi ; rcu-link ; rcu-gp) |	((srcu-rscsi ; rcu-link ; srcu-gp) & loc) |	(rcu-gp ; rcu-link ; rcu-order ; rcu-link ; rcu-rscsi) |	((srcu-gp ; rcu-link ; rcu-order ; rcu-link ; srcu-rscsi) & loc) |	(rcu-rscsi ; rcu-link ; rcu-order ; rcu-link ; rcu-gp) |	((srcu-rscsi ; rcu-link ; rcu-order ; rcu-link ; srcu-gp) & loc) |	(rcu-order ; rcu-link ; rcu-order)let rcu-fence = po ; rcu-order ; po?let fence = fence | rcu-fencelet strong-fence = strong-fence | rcu-fence (* rb orders instructions just as pb does *)let rb = prop ; rcu-fence ; hb* ; pb* ; [Marked] 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 *) (*********************************)(* Plain accesses and data races *)(*********************************) (* Warn about plain writes and marked accesses in the same region *)let mixed-accesses = ([Plain & W] ; (po-loc \ barrier) ; [Marked]) |	([Marked] ; (po-loc \ barrier) ; [Plain & W])flag ~empty mixed-accesses as mixed-accesses (* Executes-before and visibility *)let xbstar = (hb | pb | rb)*let vis = cumul-fence* ; rfe? ; [Marked] ;	((strong-fence ; [Marked] ; xbstar) | (xbstar & int)) (* Boundaries for lifetimes of plain accesses *)let w-pre-bounded = [Marked] ; (addr | fence)?let r-pre-bounded = [Marked] ; (addr | nonrw-fence |	([R4rmb] ; fencerel(Rmb) ; [~Noreturn]))?let w-post-bounded = fence? ; [Marked]let r-post-bounded = (nonrw-fence | ([~Noreturn] ; fencerel(Rmb) ; [R4rmb]))? ;	[Marked] (* Visibility and executes-before for plain accesses *)let ww-vis = fence | (strong-fence ; xbstar ; w-pre-bounded) |	(w-post-bounded ; vis ; w-pre-bounded)let wr-vis = fence | (strong-fence ; xbstar ; r-pre-bounded) |	(w-post-bounded ; vis ; r-pre-bounded)let rw-xbstar = fence | (r-post-bounded ; xbstar ; w-pre-bounded) (* Potential races *)let pre-race = ext & ((Plain * M) | ((M \ IW) * Plain)) (* Coherence requirements for plain accesses *)let wr-incoh = pre-race & rf & rw-xbstar^-1let rw-incoh = pre-race & fr & wr-vis^-1let ww-incoh = pre-race & co & ww-vis^-1empty (wr-incoh | rw-incoh | ww-incoh) as plain-coherence (* Actual races *)let ww-nonrace = ww-vis & ((Marked * W) | rw-xbstar) & ((W * Marked) | wr-vis)let ww-race = (pre-race & co) \ ww-nonracelet wr-race = (pre-race & (co? ; rf)) \ wr-vislet rw-race = (pre-race & fr) \ rw-xbstar flag ~empty (ww-race | wr-race | rw-race) as data-race