1// SPDX-License-Identifier: GPL-2.0+
2(*
3 * Copyright (C) 2015 Jade Alglave <j.alglave@ucl.ac.uk>,
4 * Copyright (C) 2016 Luc Maranget <luc.maranget@inria.fr> for Inria
5 * Copyright (C) 2017 Alan Stern <stern@rowland.harvard.edu>,
6 *                    Andrea Parri <parri.andrea@gmail.com>
7 *
8 * An earlier version of this file appeared in the companion webpage for
9 * "Frightening small children and disconcerting grown-ups: Concurrency
10 * in the Linux kernel" by Alglave, Maranget, McKenney, Parri, and Stern,
11 * which appeared in ASPLOS 2018.
12 *)
13
14"Linux-kernel memory consistency model"
15
16enum Accesses = 'once (*READ_ONCE,WRITE_ONCE*) ||
17		'release (*smp_store_release*) ||
18		'acquire (*smp_load_acquire*) ||
19		'noreturn (* R of non-return RMW *)
20instructions R[{'once,'acquire,'noreturn}]
21instructions W[{'once,'release}]
22instructions RMW[{'once,'acquire,'release}]
23
24enum Barriers = 'wmb (*smp_wmb*) ||
25		'rmb (*smp_rmb*) ||
26		'mb (*smp_mb*) ||
27		'barrier (*barrier*) ||
28		'rcu-lock (*rcu_read_lock*)  ||
29		'rcu-unlock (*rcu_read_unlock*) ||
30		'sync-rcu (*synchronize_rcu*) ||
31		'before-atomic (*smp_mb__before_atomic*) ||
32		'after-atomic (*smp_mb__after_atomic*) ||
33		'after-spinlock (*smp_mb__after_spinlock*) ||
34		'after-unlock-lock (*smp_mb__after_unlock_lock*)
35instructions F[Barriers]
36
37(* SRCU *)
38enum SRCU = 'srcu-lock || 'srcu-unlock || 'sync-srcu
39instructions SRCU[SRCU]
40(* All srcu events *)
41let Srcu = Srcu-lock | Srcu-unlock | Sync-srcu
42
43(* Compute matching pairs of nested Rcu-lock and Rcu-unlock *)
44let rcu-rscs = let rec
45	    unmatched-locks = Rcu-lock \ domain(matched)
46	and unmatched-unlocks = Rcu-unlock \ range(matched)
47	and unmatched = unmatched-locks | unmatched-unlocks
48	and unmatched-po = [unmatched] ; po ; [unmatched]
49	and unmatched-locks-to-unlocks =
50		[unmatched-locks] ; po ; [unmatched-unlocks]
51	and matched = matched | (unmatched-locks-to-unlocks \
52		(unmatched-po ; unmatched-po))
53	in matched
54
55(* Validate nesting *)
56flag ~empty Rcu-lock \ domain(rcu-rscs) as unbalanced-rcu-locking
57flag ~empty Rcu-unlock \ range(rcu-rscs) as unbalanced-rcu-locking
58
59(* Compute matching pairs of nested Srcu-lock and Srcu-unlock *)
60let srcu-rscs = let rec
61	    unmatched-locks = Srcu-lock \ domain(matched)
62	and unmatched-unlocks = Srcu-unlock \ range(matched)
63	and unmatched = unmatched-locks | unmatched-unlocks
64	and unmatched-po = ([unmatched] ; po ; [unmatched]) & loc
65	and unmatched-locks-to-unlocks =
66		([unmatched-locks] ; po ; [unmatched-unlocks]) & loc
67	and matched = matched | (unmatched-locks-to-unlocks \
68		(unmatched-po ; unmatched-po))
69	in matched
70
71(* Validate nesting *)
72flag ~empty Srcu-lock \ domain(srcu-rscs) as unbalanced-srcu-locking
73flag ~empty Srcu-unlock \ range(srcu-rscs) as unbalanced-srcu-locking
74
75(* Check for use of synchronize_srcu() inside an RCU critical section *)
76flag ~empty rcu-rscs & (po ; [Sync-srcu] ; po) as invalid-sleep
77
78(* Validate SRCU dynamic match *)
79flag ~empty different-values(srcu-rscs) as srcu-bad-nesting
80
81(* Compute marked and plain memory accesses *)
82let Marked = (~M) | IW | Once | Release | Acquire | domain(rmw) | range(rmw) |
83		LKR | LKW | UL | LF | RL | RU
84let Plain = M \ Marked
85
86(* Redefine dependencies to include those carried through plain accesses *)
87let carry-dep = (data ; rfi)*
88let addr = carry-dep ; addr
89let ctrl = carry-dep ; ctrl
90let data = carry-dep ; data
91