| // SPDX-License-Identifier: GPL-2.0+ |
| (* |
| * Copyright (C) 2016 Luc Maranget <luc.maranget@inria.fr> for Inria |
| * Copyright (C) 2017 Alan Stern <stern@rowland.harvard.edu> |
| *) |
| |
| (* |
| * Generate coherence orders and handle lock operations |
| * |
| * Warning: spin_is_locked() crashes herd7 versions strictly before 7.48. |
| * spin_is_locked() is functional from herd7 version 7.49. |
| *) |
| |
| include "cross.cat" |
| |
| (* |
| * The lock-related events generated by herd are as follows: |
| * |
| * LKR Lock-Read: the read part of a spin_lock() or successful |
| * spin_trylock() read-modify-write event pair |
| * LKW Lock-Write: the write part of a spin_lock() or successful |
| * spin_trylock() RMW event pair |
| * UL Unlock: a spin_unlock() event |
| * LF Lock-Fail: a failed spin_trylock() event |
| * RL Read-Locked: a spin_is_locked() event which returns True |
| * RU Read-Unlocked: a spin_is_locked() event which returns False |
| * |
| * LKR and LKW events always come paired, like all RMW event sequences. |
| * |
| * LKR, LF, RL, and RU are read events; LKR has Acquire ordering. |
| * LKW and UL are write events; UL has Release ordering. |
| * LKW, LF, RL, and RU have no ordering properties. |
| *) |
| |
| (* Backward compatibility *) |
| let RL = try RL with emptyset |
| let RU = try RU with emptyset |
| |
| (* Treat RL as a kind of LF: a read with no ordering properties *) |
| let LF = LF | RL |
| |
| (* There should be no ordinary R or W accesses to spinlocks *) |
| let ALL-LOCKS = LKR | LKW | UL | LF | RU |
| flag ~empty [M \ IW] ; loc ; [ALL-LOCKS] as mixed-lock-accesses |
| |
| (* Link Lock-Reads to their RMW-partner Lock-Writes *) |
| let lk-rmw = ([LKR] ; po-loc ; [LKW]) \ (po ; po) |
| let rmw = rmw | lk-rmw |
| |
| (* The litmus test is invalid if an LKR/LKW event is not part of an RMW pair *) |
| flag ~empty LKW \ range(lk-rmw) as unpaired-LKW |
| flag ~empty LKR \ domain(lk-rmw) as unpaired-LKR |
| |
| (* |
| * An LKR must always see an unlocked value; spin_lock() calls nested |
| * inside a critical section (for the same lock) always deadlock. |
| *) |
| empty ([LKW] ; po-loc ; [LKR]) \ (po-loc ; [UL] ; po-loc) as lock-nest |
| |
| (* The final value of a spinlock should not be tested *) |
| flag ~empty [FW] ; loc ; [ALL-LOCKS] as lock-final |
| |
| (* |
| * Put lock operations in their appropriate classes, but leave UL out of W |
| * until after the co relation has been generated. |
| *) |
| let R = R | LKR | LF | RU |
| let W = W | LKW |
| |
| let Release = Release | UL |
| let Acquire = Acquire | LKR |
| |
| (* Match LKW events to their corresponding UL events *) |
| let critical = ([LKW] ; po-loc ; [UL]) \ (po-loc ; [LKW | UL] ; po-loc) |
| |
| flag ~empty UL \ range(critical) as unmatched-unlock |
| |
| (* Allow up to one unmatched LKW per location; more must deadlock *) |
| let UNMATCHED-LKW = LKW \ domain(critical) |
| empty ([UNMATCHED-LKW] ; loc ; [UNMATCHED-LKW]) \ id as unmatched-locks |
| |
| (* rfi for LF events: link each LKW to the LF events in its critical section *) |
| let rfi-lf = ([LKW] ; po-loc ; [LF]) \ ([LKW] ; po-loc ; [UL] ; po-loc) |
| |
| (* rfe for LF events *) |
| let all-possible-rfe-lf = |
| (* |
| * Given an LF event r, compute the possible rfe edges for that event |
| * (all those starting from LKW events in other threads), |
| * and then convert that relation to a set of single-edge relations. |
| *) |
| let possible-rfe-lf r = |
| let pair-to-relation p = p ++ 0 |
| in map pair-to-relation ((LKW * {r}) & loc & ext) |
| (* Do this for each LF event r that isn't in rfi-lf *) |
| in map possible-rfe-lf (LF \ range(rfi-lf)) |
| |
| (* Generate all rf relations for LF events *) |
| with rfe-lf from cross(all-possible-rfe-lf) |
| let rf-lf = rfe-lf | rfi-lf |
| |
| (* |
| * RU, i.e., spin_is_locked() returning False, is slightly different. |
| * We rely on the memory model to rule out cases where spin_is_locked() |
| * within one of the lock's critical sections returns False. |
| *) |
| |
| (* rfi for RU events: an RU may read from the last po-previous UL *) |
| let rfi-ru = ([UL] ; po-loc ; [RU]) \ ([UL] ; po-loc ; [LKW] ; po-loc) |
| |
| (* rfe for RU events: an RU may read from an external UL or the initial write *) |
| let all-possible-rfe-ru = |
| let possible-rfe-ru r = |
| let pair-to-relation p = p ++ 0 |
| in map pair-to-relation (((UL | IW) * {r}) & loc & ext) |
| in map possible-rfe-ru RU |
| |
| (* Generate all rf relations for RU events *) |
| with rfe-ru from cross(all-possible-rfe-ru) |
| let rf-ru = rfe-ru | rfi-ru |
| |
| (* Final rf relation *) |
| let rf = rf | rf-lf | rf-ru |
| |
| (* Generate all co relations, including LKW events but not UL *) |
| let co0 = co0 | ([IW] ; loc ; [LKW]) | |
| (([LKW] ; loc ; [UNMATCHED-LKW]) \ [UNMATCHED-LKW]) |
| include "cos-opt.cat" |
| let W = W | UL |
| let M = R | W |
| |
| (* Merge UL events into co *) |
| let co = (co | critical | (critical^-1 ; co))+ |
| let coe = co & ext |
| let coi = co & int |
| |
| (* Merge LKR events into rf *) |
| let rf = rf | ([IW | UL] ; singlestep(co) ; lk-rmw^-1) |
| let rfe = rf & ext |
| let rfi = rf & int |
| |
| let fr = rf^-1 ; co |
| let fre = fr & ext |
| let fri = fr & int |
| |
| show co,rf,fr |