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1 | #ifndef _UAPI_LINUX_MEMBARRIER_H |
2 | #define _UAPI_LINUX_MEMBARRIER_H | |
3 | ||
4 | /* | |
5 | * linux/membarrier.h | |
6 | * | |
7 | * membarrier system call API | |
8 | * | |
9 | * Copyright (c) 2010, 2015 Mathieu Desnoyers <mathieu.desnoyers@efficios.com> | |
10 | * | |
11 | * Permission is hereby granted, free of charge, to any person obtaining a copy | |
12 | * of this software and associated documentation files (the "Software"), to deal | |
13 | * in the Software without restriction, including without limitation the rights | |
14 | * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell | |
15 | * copies of the Software, and to permit persons to whom the Software is | |
16 | * furnished to do so, subject to the following conditions: | |
17 | * | |
18 | * The above copyright notice and this permission notice shall be included in | |
19 | * all copies or substantial portions of the Software. | |
20 | * | |
21 | * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR | |
22 | * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, | |
23 | * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE | |
24 | * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER | |
25 | * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, | |
26 | * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE | |
27 | * SOFTWARE. | |
28 | */ | |
29 | ||
30 | /** | |
31 | * enum membarrier_cmd - membarrier system call command | |
32 | * @MEMBARRIER_CMD_QUERY: Query the set of supported commands. It returns | |
33 | * a bitmask of valid commands. | |
c5f58bd5 | 34 | * @MEMBARRIER_CMD_GLOBAL: Execute a memory barrier on all running threads. |
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35 | * Upon return from system call, the caller thread |
36 | * is ensured that all running threads have passed | |
37 | * through a state where all memory accesses to | |
38 | * user-space addresses match program order between | |
39 | * entry to and return from the system call | |
40 | * (non-running threads are de facto in such a | |
41 | * state). This covers threads from all processes | |
42 | * running on the system. This command returns 0. | |
c5f58bd5 MD |
43 | * @MEMBARRIER_CMD_GLOBAL_EXPEDITED: |
44 | * Execute a memory barrier on all running threads | |
45 | * of all processes which previously registered | |
46 | * with MEMBARRIER_CMD_REGISTER_GLOBAL_EXPEDITED. | |
47 | * Upon return from system call, the caller thread | |
48 | * is ensured that all running threads have passed | |
49 | * through a state where all memory accesses to | |
50 | * user-space addresses match program order between | |
51 | * entry to and return from the system call | |
52 | * (non-running threads are de facto in such a | |
53 | * state). This only covers threads from processes | |
54 | * which registered with | |
55 | * MEMBARRIER_CMD_REGISTER_GLOBAL_EXPEDITED. | |
56 | * This command returns 0. Given that | |
57 | * registration is about the intent to receive | |
58 | * the barriers, it is valid to invoke | |
59 | * MEMBARRIER_CMD_GLOBAL_EXPEDITED from a | |
60 | * non-registered process. | |
61 | * @MEMBARRIER_CMD_REGISTER_GLOBAL_EXPEDITED: | |
62 | * Register the process intent to receive | |
63 | * MEMBARRIER_CMD_GLOBAL_EXPEDITED memory | |
64 | * barriers. Always returns 0. | |
22e4ebb9 MD |
65 | * @MEMBARRIER_CMD_PRIVATE_EXPEDITED: |
66 | * Execute a memory barrier on each running | |
67 | * thread belonging to the same process as the current | |
68 | * thread. Upon return from system call, the | |
69 | * caller thread is ensured that all its running | |
70 | * threads siblings have passed through a state | |
71 | * where all memory accesses to user-space | |
72 | * addresses match program order between entry | |
73 | * to and return from the system call | |
74 | * (non-running threads are de facto in such a | |
75 | * state). This only covers threads from the | |
70216e18 | 76 | * same process as the caller thread. This |
a961e409 MD |
77 | * command returns 0 on success. The |
78 | * "expedited" commands complete faster than | |
79 | * the non-expedited ones, they never block, | |
80 | * but have the downside of causing extra | |
81 | * overhead. A process needs to register its | |
82 | * intent to use the private expedited command | |
83 | * prior to using it, otherwise this command | |
84 | * returns -EPERM. | |
85 | * @MEMBARRIER_CMD_REGISTER_PRIVATE_EXPEDITED: | |
86 | * Register the process intent to use | |
87 | * MEMBARRIER_CMD_PRIVATE_EXPEDITED. Always | |
88 | * returns 0. | |
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89 | * @MEMBARRIER_CMD_PRIVATE_EXPEDITED_SYNC_CORE: |
90 | * In addition to provide memory ordering | |
91 | * guarantees described in | |
92 | * MEMBARRIER_CMD_PRIVATE_EXPEDITED, ensure | |
93 | * the caller thread, upon return from system | |
94 | * call, that all its running threads siblings | |
95 | * have executed a core serializing | |
96 | * instruction. (architectures are required to | |
97 | * guarantee that non-running threads issue | |
98 | * core serializing instructions before they | |
99 | * resume user-space execution). This only | |
100 | * covers threads from the same process as the | |
101 | * caller thread. This command returns 0 on | |
102 | * success. The "expedited" commands complete | |
103 | * faster than the non-expedited ones, they | |
104 | * never block, but have the downside of | |
105 | * causing extra overhead. If this command is | |
106 | * not implemented by an architecture, -EINVAL | |
107 | * is returned. A process needs to register its | |
108 | * intent to use the private expedited sync | |
109 | * core command prior to using it, otherwise | |
110 | * this command returns -EPERM. | |
111 | * @MEMBARRIER_CMD_REGISTER_PRIVATE_EXPEDITED_SYNC_CORE: | |
112 | * Register the process intent to use | |
113 | * MEMBARRIER_CMD_PRIVATE_EXPEDITED_SYNC_CORE. | |
114 | * If this command is not implemented by an | |
115 | * architecture, -EINVAL is returned. | |
116 | * Returns 0 on success. | |
c5f58bd5 MD |
117 | * @MEMBARRIER_CMD_SHARED: |
118 | * Alias to MEMBARRIER_CMD_GLOBAL. Provided for | |
119 | * header backward compatibility. | |
5b25b13a MD |
120 | * |
121 | * Command to be passed to the membarrier system call. The commands need to | |
122 | * be a single bit each, except for MEMBARRIER_CMD_QUERY which is assigned to | |
123 | * the value 0. | |
124 | */ | |
125 | enum membarrier_cmd { | |
c5f58bd5 MD |
126 | MEMBARRIER_CMD_QUERY = 0, |
127 | MEMBARRIER_CMD_GLOBAL = (1 << 0), | |
128 | MEMBARRIER_CMD_GLOBAL_EXPEDITED = (1 << 1), | |
129 | MEMBARRIER_CMD_REGISTER_GLOBAL_EXPEDITED = (1 << 2), | |
130 | MEMBARRIER_CMD_PRIVATE_EXPEDITED = (1 << 3), | |
131 | MEMBARRIER_CMD_REGISTER_PRIVATE_EXPEDITED = (1 << 4), | |
70216e18 MD |
132 | MEMBARRIER_CMD_PRIVATE_EXPEDITED_SYNC_CORE = (1 << 5), |
133 | MEMBARRIER_CMD_REGISTER_PRIVATE_EXPEDITED_SYNC_CORE = (1 << 6), | |
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134 | |
135 | /* Alias for header backward compatibility. */ | |
136 | MEMBARRIER_CMD_SHARED = MEMBARRIER_CMD_GLOBAL, | |
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137 | }; |
138 | ||
139 | #endif /* _UAPI_LINUX_MEMBARRIER_H */ |