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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 | ||
15553dcb | 7 | (* |
fd0359db | 8 | * Generate coherence orders and handle lock operations |
15553dcb | 9 | * |
fd0359db AS |
10 | * Warning: spin_is_locked() crashes herd7 versions strictly before 7.48. |
11 | * spin_is_locked() is functional from herd7 version 7.49. | |
15553dcb | 12 | *) |
fd0359db | 13 | |
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14 | include "cross.cat" |
15 | ||
fd0359db AS |
16 | (* |
17 | * The lock-related events generated by herd are as follows: | |
18 | * | |
19 | * LKR Lock-Read: the read part of a spin_lock() or successful | |
20 | * spin_trylock() read-modify-write event pair | |
21 | * LKW Lock-Write: the write part of a spin_lock() or successful | |
22 | * spin_trylock() RMW event pair | |
23 | * UL Unlock: a spin_unlock() event | |
24 | * LF Lock-Fail: a failed spin_trylock() event | |
25 | * RL Read-Locked: a spin_is_locked() event which returns True | |
26 | * RU Read-Unlocked: a spin_is_locked() event which returns False | |
27 | * | |
28 | * LKR and LKW events always come paired, like all RMW event sequences. | |
29 | * | |
30 | * LKR, LF, RL, and RU are read events; LKR has Acquire ordering. | |
31 | * LKW and UL are write events; UL has Release ordering. | |
32 | * LKW, LF, RL, and RU have no ordering properties. | |
33 | *) | |
34 | ||
30b795df AS |
35 | (* Backward compatibility *) |
36 | let RL = try RL with emptyset | |
37 | let RU = try RU with emptyset | |
38 | ||
39 | (* Treat RL as a kind of LF: a read with no ordering properties *) | |
40 | let LF = LF | RL | |
41 | ||
42 | (* There should be no ordinary R or W accesses to spinlocks *) | |
43 | let ALL-LOCKS = LKR | LKW | UL | LF | RU | |
44 | flag ~empty [M \ IW] ; loc ; [ALL-LOCKS] as mixed-lock-accesses | |
45 | ||
fd0359db | 46 | (* Link Lock-Reads to their RMW-partner Lock-Writes *) |
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47 | let lk-rmw = ([LKR] ; po-loc ; [LKW]) \ (po ; po) |
48 | let rmw = rmw | lk-rmw | |
49 | ||
cee0321a AS |
50 | (* The litmus test is invalid if an LKR/LKW event is not part of an RMW pair *) |
51 | flag ~empty LKW \ range(lk-rmw) as unpaired-LKW | |
52 | flag ~empty LKR \ domain(lk-rmw) as unpaired-LKR | |
53 | ||
1c27b644 | 54 | (* |
cee0321a | 55 | * An LKR must always see an unlocked value; spin_lock() calls nested |
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56 | * inside a critical section (for the same lock) always deadlock. |
57 | *) | |
cee0321a | 58 | empty ([LKW] ; po-loc ; [LKR]) \ (po-loc ; [UL] ; po-loc) as lock-nest |
1c27b644 | 59 | |
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60 | (* The final value of a spinlock should not be tested *) |
61 | flag ~empty [FW] ; loc ; [ALL-LOCKS] as lock-final | |
62 | ||
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63 | (* |
64 | * Put lock operations in their appropriate classes, but leave UL out of W | |
65 | * until after the co relation has been generated. | |
66 | *) | |
8559183c | 67 | let R = R | LKR | LF | RU |
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68 | let W = W | LKW |
69 | ||
70 | let Release = Release | UL | |
71 | let Acquire = Acquire | LKR | |
72 | ||
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73 | (* Match LKW events to their corresponding UL events *) |
74 | let critical = ([LKW] ; po-loc ; [UL]) \ (po-loc ; [LKW | UL] ; po-loc) | |
75 | ||
76 | flag ~empty UL \ range(critical) as unmatched-unlock | |
77 | ||
78 | (* Allow up to one unmatched LKW per location; more must deadlock *) | |
79 | let UNMATCHED-LKW = LKW \ domain(critical) | |
80 | empty ([UNMATCHED-LKW] ; loc ; [UNMATCHED-LKW]) \ id as unmatched-locks | |
81 | ||
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82 | (* rfi for LF events: link each LKW to the LF events in its critical section *) |
83 | let rfi-lf = ([LKW] ; po-loc ; [LF]) \ ([LKW] ; po-loc ; [UL] ; po-loc) | |
84 | ||
85 | (* rfe for LF events *) | |
86 | let all-possible-rfe-lf = | |
05604e7e AP |
87 | (* |
88 | * Given an LF event r, compute the possible rfe edges for that event | |
89 | * (all those starting from LKW events in other threads), | |
90 | * and then convert that relation to a set of single-edge relations. | |
91 | *) | |
92 | let possible-rfe-lf r = | |
93 | let pair-to-relation p = p ++ 0 | |
94 | in map pair-to-relation ((LKW * {r}) & loc & ext) | |
95 | (* Do this for each LF event r that isn't in rfi-lf *) | |
96 | in map possible-rfe-lf (LF \ range(rfi-lf)) | |
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97 | |
98 | (* Generate all rf relations for LF events *) | |
99 | with rfe-lf from cross(all-possible-rfe-lf) | |
15553dcb LM |
100 | let rf-lf = rfe-lf | rfi-lf |
101 | ||
fd0359db AS |
102 | (* |
103 | * RU, i.e., spin_is_locked() returning False, is slightly different. | |
104 | * We rely on the memory model to rule out cases where spin_is_locked() | |
105 | * within one of the lock's critical sections returns False. | |
106 | *) | |
15553dcb | 107 | |
fd0359db | 108 | (* rfi for RU events: an RU may read from the last po-previous UL *) |
15553dcb LM |
109 | let rfi-ru = ([UL] ; po-loc ; [RU]) \ ([UL] ; po-loc ; [LKW] ; po-loc) |
110 | ||
fd0359db | 111 | (* rfe for RU events: an RU may read from an external UL or the initial write *) |
15553dcb | 112 | let all-possible-rfe-ru = |
05604e7e AP |
113 | let possible-rfe-ru r = |
114 | let pair-to-relation p = p ++ 0 | |
115 | in map pair-to-relation (((UL | IW) * {r}) & loc & ext) | |
116 | in map possible-rfe-ru RU | |
15553dcb | 117 | |
fd0359db | 118 | (* Generate all rf relations for RU events *) |
15553dcb LM |
119 | with rfe-ru from cross(all-possible-rfe-ru) |
120 | let rf-ru = rfe-ru | rfi-ru | |
121 | ||
122 | (* Final rf relation *) | |
8559183c | 123 | let rf = rf | rf-lf | rf-ru |
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124 | |
125 | (* Generate all co relations, including LKW events but not UL *) | |
126 | let co0 = co0 | ([IW] ; loc ; [LKW]) | | |
127 | (([LKW] ; loc ; [UNMATCHED-LKW]) \ [UNMATCHED-LKW]) | |
128 | include "cos-opt.cat" | |
129 | let W = W | UL | |
130 | let M = R | W | |
131 | ||
132 | (* Merge UL events into co *) | |
133 | let co = (co | critical | (critical^-1 ; co))+ | |
134 | let coe = co & ext | |
135 | let coi = co & int | |
136 | ||
137 | (* Merge LKR events into rf *) | |
138 | let rf = rf | ([IW | UL] ; singlestep(co) ; lk-rmw^-1) | |
139 | let rfe = rf & ext | |
140 | let rfi = rf & int | |
141 | ||
142 | let fr = rf^-1 ; co | |
143 | let fre = fr & ext | |
144 | let fri = fr & int | |
145 | ||
146 | show co,rf,fr |