// 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 *) ||
'MB (*xchg(),cmpxchg(),...*)
instructions R[Accesses]
instructions W[Accesses]
instructions RMW[Accesses]
enum Barriers = 'wmb (*smp_wmb*) ||
'rmb (*smp_rmb*) ||
'MB (*smp_mb*) ||
'barrier (*barrier*) ||
'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*) ||
'after-unlock-lock (*smp_mb__after_unlock_lock*) ||
'after-srcu-read-unlock (*smp_mb__after_srcu_read_unlock*)
instructions F[Barriers]
(*
* Filter out syntactic annotations that do not provide the corresponding
* semantic ordering, such as Acquire on a store or Mb on a failed RMW.
*)
let FailedRMW = RMW \ (domain(rmw) | range(rmw))
let Acquire = ACQUIRE \ W \ FailedRMW
let Release = RELEASE \ R \ FailedRMW
let Mb = MB \ FailedRMW
let Noreturn = NORETURN \ W
(* SRCU *)
enum SRCU = 'srcu-lock || 'srcu-unlock || 'sync-srcu
instructions SRCU[SRCU]
(* All srcu events *)
let Srcu = Srcu-lock | Srcu-unlock | Sync-srcu
(* Compute matching pairs of nested Rcu-lock and Rcu-unlock *)
let rcu-rscs = 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(rcu-rscs) as unmatched-rcu-lock
flag ~empty Rcu-unlock \ range(rcu-rscs) as unmatched-rcu-unlock
(* Compute matching pairs of nested Srcu-lock and Srcu-unlock *)
let carry-srcu-data = (data ; [~ Srcu-unlock] ; rf)*
let srcu-rscs = ([Srcu-lock] ; carry-srcu-data ; data ; [Srcu-unlock]) & loc
(* Validate nesting *)
flag ~empty Srcu-lock \ domain(srcu-rscs) as unmatched-srcu-lock
flag ~empty Srcu-unlock \ range(srcu-rscs) as unmatched-srcu-unlock
flag ~empty (srcu-rscs^-1 ; srcu-rscs) \ id as multiple-srcu-matches
(* Check for use of synchronize_srcu() inside an RCU critical section *)
flag ~empty rcu-rscs & (po ; [Sync-srcu] ; po) as invalid-sleep
(* Validate SRCU dynamic match *)
flag ~empty different-values(srcu-rscs) as srcu-bad-value-match
(* Compute marked and plain memory accesses *)
let Marked = (~M) | IW | ONCE | RELEASE | ACQUIRE | MB | RMW |
LKR | LKW | UL | LF | RL | RU | Srcu-lock | Srcu-unlock
let Plain = M \ Marked
(* Redefine dependencies to include those carried through plain accesses *)
let carry-dep = (data ; [~ Srcu-unlock] ; rfi)*
let addr = carry-dep ; addr
let ctrl = carry-dep ; ctrl
let data = carry-dep ; data
flag ~empty (if "lkmmv2" then 0 else _)
as this-model-requires-variant-higher-than-lkmmv1
