1// SPDX-License-Identifier: GPL-2.0+ 2(* 3 * Copyright (C) 2016 Luc Maranget <luc.maranget@inria.fr> for Inria 4 * Copyright (C) 2017 Alan Stern <stern@rowland.harvard.edu> 5 *) 6 7(* 8 * Generate coherence orders and handle lock operations 9 *) 10 11include "cross.cat" 12 13(* 14 * The lock-related events generated by herd7 are as follows: 15 * 16 * LKR Lock-Read: the read part of a spin_lock() or successful 17 * spin_trylock() read-modify-write event pair 18 * LKW Lock-Write: the write part of a spin_lock() or successful 19 * spin_trylock() RMW event pair 20 * UL Unlock: a spin_unlock() event 21 * LF Lock-Fail: a failed spin_trylock() event 22 * RL Read-Locked: a spin_is_locked() event which returns True 23 * RU Read-Unlocked: a spin_is_locked() event which returns False 24 * 25 * LKR and LKW events always come paired, like all RMW event sequences. 26 * 27 * LKR, LF, RL, and RU are read events; LKR has Acquire ordering. 28 * LKW and UL are write events; UL has Release ordering. 29 * LKW, LF, RL, and RU have no ordering properties. 30 *) 31 32(* Backward compatibility *) 33let RL = try RL with emptyset 34let RU = try RU with emptyset 35 36(* Treat RL as a kind of LF: a read with no ordering properties *) 37let LF = LF | RL 38 39(* There should be no ordinary R or W accesses to spinlocks or SRCU structs *) 40let ALL-LOCKS = LKR | LKW | UL | LF | RU | Srcu-lock | Srcu-unlock | Sync-srcu 41flag ~empty [M \ IW \ ALL-LOCKS] ; loc ; [ALL-LOCKS] as mixed-lock-accesses 42 43(* Link Lock-Reads to their RMW-partner Lock-Writes *) 44let lk-rmw = ([LKR] ; po-loc ; [LKW]) \ (po ; po) 45let rmw = rmw | lk-rmw 46 47(* The litmus test is invalid if an LKR/LKW event is not part of an RMW pair *) 48flag ~empty LKW \ range(lk-rmw) as unpaired-LKW 49flag ~empty LKR \ domain(lk-rmw) as unpaired-LKR 50 51(* 52 * An LKR must always see an unlocked value; spin_lock() calls nested 53 * inside a critical section (for the same lock) always deadlock. 54 *) 55empty ([LKW] ; po-loc ; [LKR]) \ (po-loc ; [UL] ; po-loc) as lock-nest 56 57(* 58 * In the same way, spin_is_locked() inside a critical section must always 59 * return True (no RU events can be in a critical section for the same lock). 60 *) 61empty ([LKW] ; po-loc ; [RU]) \ (po-loc ; [UL] ; po-loc) as nested-is-locked 62 63(* The final value of a spinlock should not be tested *) 64flag ~empty [FW] ; loc ; [ALL-LOCKS] as lock-final 65 66(* 67 * Put lock operations in their appropriate classes, but leave UL out of W 68 * until after the co relation has been generated. 69 *) 70let R = R | LKR | LF | RU 71let W = W | LKW 72 73let Release = Release | UL 74let Acquire = Acquire | LKR 75 76(* Match LKW events to their corresponding UL events *) 77let critical = ([LKW] ; po-loc ; [UL]) \ (po-loc ; [LKW | UL] ; po-loc) 78 79flag ~empty UL \ range(critical) as unmatched-unlock 80 81(* Allow up to one unmatched LKW per location; more must deadlock *) 82let UNMATCHED-LKW = LKW \ domain(critical) 83empty ([UNMATCHED-LKW] ; loc ; [UNMATCHED-LKW]) \ id as unmatched-locks 84 85(* rfi for LF events: link each LKW to the LF events in its critical section *) 86let rfi-lf = ([LKW] ; po-loc ; [LF]) \ ([LKW] ; po-loc ; [UL] ; po-loc) 87 88(* Utility macro to convert a single pair to a single-edge relation *) 89let pair-to-relation p = p ++ 0 90 91(* 92 * If a given LF event e is outside a critical section, it cannot read 93 * internally but it may read from an LKW event in another thread. 94 * Compute the relation containing these possible edges. 95 *) 96let possible-rfe-noncrit-lf e = (LKW * {e}) & loc & ext 97 98(* Compute set of sets of possible rfe edges for LF events *) 99let all-possible-rfe-lf = 100 (* 101 * Convert the possible-rfe-noncrit-lf relation for e 102 * to a set of single edges 103 *) 104 let set-of-singleton-rfe-lf e = 105 map pair-to-relation (possible-rfe-noncrit-lf e) 106 (* Do this for each LF event e that isn't in rfi-lf *) 107 in map set-of-singleton-rfe-lf (LF \ range(rfi-lf)) 108 109(* Generate all rf relations for LF events *) 110with rfe-lf from cross(all-possible-rfe-lf) 111let rf-lf = rfe-lf | rfi-lf 112 113(* 114 * A given RU event e may read internally from the last po-previous UL, 115 * or it may read from a UL event in another thread or the initial write. 116 * Compute the relation containing these possible edges. 117 *) 118let possible-rf-ru e = (((UL * {e}) & po-loc) \ 119 ([UL] ; po-loc ; [UL] ; po-loc)) | 120 (((UL | IW) * {e}) & loc & ext) 121 122(* Compute set of sets of possible rf edges for RU events *) 123let all-possible-rf-ru = 124 (* Convert the possible-rf-ru relation for e to a set of single edges *) 125 let set-of-singleton-rf-ru e = 126 map pair-to-relation (possible-rf-ru e) 127 (* Do this for each RU event e *) 128 in map set-of-singleton-rf-ru RU 129 130(* Generate all rf relations for RU events *) 131with rf-ru from cross(all-possible-rf-ru) 132 133(* Final rf relation *) 134let rf = rf | rf-lf | rf-ru 135 136(* Generate all co relations, including LKW events but not UL *) 137let co0 = co0 | ([IW] ; loc ; [LKW]) | 138 (([LKW] ; loc ; [UNMATCHED-LKW]) \ [UNMATCHED-LKW]) 139include "cos-opt.cat" 140let W = W | UL 141let M = R | W 142 143(* Merge UL events into co *) 144let co = (co | critical | (critical^-1 ; co))+ 145let coe = co & ext 146let coi = co & int 147 148(* Merge LKR events into rf *) 149let rf = rf | ([IW | UL] ; singlestep(co) ; lk-rmw^-1) 150let rfe = rf & ext 151let rfi = rf & int 152 153let fr = rf^-1 ; co 154let fre = fr & ext 155let fri = fr & int 156 157show co,rf,fr 158