// SPDX-License-Identifier: GPL-2.0+ (* * Copyright (C) 2016 Luc Maranget for Inria * Copyright (C) 2017 Alan Stern *) (* * Generate coherence orders and handle lock operations *) include "cross.cat" (* * The lock-related events generated by herd7 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 or SRCU structs *) let ALL-LOCKS = LKR | LKW | UL | LF | RU | Srcu-lock | Srcu-unlock | Sync-srcu flag ~empty [M \ IW \ ALL-LOCKS] ; 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 (* * In the same way, spin_is_locked() inside a critical section must always * return True (no RU events can be in a critical section for the same lock). *) empty ([LKW] ; po-loc ; [RU]) \ (po-loc ; [UL] ; po-loc) as nested-is-locked (* 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) (* Utility macro to convert a single pair to a single-edge relation *) let pair-to-relation p = p ++ 0 (* * If a given LF event e is outside a critical section, it cannot read * internally but it may read from an LKW event in another thread. * Compute the relation containing these possible edges. *) let possible-rfe-noncrit-lf e = (LKW * {e}) & loc & ext (* Compute set of sets of possible rfe edges for LF events *) let all-possible-rfe-lf = (* * Convert the possible-rfe-noncrit-lf relation for e * to a set of single edges *) let set-of-singleton-rfe-lf e = map pair-to-relation (possible-rfe-noncrit-lf e) (* Do this for each LF event e that isn't in rfi-lf *) in map set-of-singleton-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 (* * A given RU event e may read internally from the last po-previous UL, * or it may read from a UL event in another thread or the initial write. * Compute the relation containing these possible edges. *) let possible-rf-ru e = (((UL * {e}) & po-loc) \ ([UL] ; po-loc ; [UL] ; po-loc)) | (((UL | IW) * {e}) & loc & ext) (* Compute set of sets of possible rf edges for RU events *) let all-possible-rf-ru = (* Convert the possible-rf-ru relation for e to a set of single edges *) let set-of-singleton-rf-ru e = map pair-to-relation (possible-rf-ru e) (* Do this for each RU event e *) in map set-of-singleton-rf-ru RU (* Generate all rf relations for RU events *) with rf-ru from cross(all-possible-rf-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