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Diffstat (limited to 'tools/memory-model/linux-kernel.cat')
-rw-r--r-- | tools/memory-model/linux-kernel.cat | 203 |
1 files changed, 203 insertions, 0 deletions
diff --git a/tools/memory-model/linux-kernel.cat b/tools/memory-model/linux-kernel.cat new file mode 100644 index 000000000..2a9b4fe4a --- /dev/null +++ b/tools/memory-model/linux-kernel.cat @@ -0,0 +1,203 @@ +// 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-po +let fence = nonrw-fence | wmb | rmb +let 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 | fr +acyclic po-loc | com as coherence + +(* Atomic Read-Modify-Write *) +empty rmw & (fre ; coe) as atomic + +(**********************************) +(* Instruction execution ordering *) +(**********************************) + +(* Preserved Program Order *) +let dep = addr | data +let rwdep = (dep | ctrl) ; [W] +let overwrite = co | fr +let 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])? ; r +let 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^-1 +let 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-fence +let 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^-1 +let rw-incoh = pre-race & fr & wr-vis^-1 +let ww-incoh = pre-race & co & ww-vis^-1 +empty (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-nonrace +let wr-race = (pre-race & (co? ; rf)) \ wr-vis \ rw-xbstar^-1 +let rw-race = (pre-race & fr) \ rw-xbstar + +flag ~empty (ww-race | wr-race | rw-race) as data-race |