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