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1#ifndef _UAPI_LINUX_MEMBARRIER_H2#define _UAPI_LINUX_MEMBARRIER_H3 4/*5 * linux/membarrier.h6 *7 * membarrier system call API8 *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 copy12 * of this software and associated documentation files (the "Software"), to deal13 * in the Software without restriction, including without limitation the rights14 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell15 * copies of the Software, and to permit persons to whom the Software is16 * furnished to do so, subject to the following conditions:17 *18 * The above copyright notice and this permission notice shall be included in19 * all copies or substantial portions of the Software.20 *21 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR22 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,23 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE24 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER25 * 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 THE27 * SOFTWARE.28 */29 30/**31 * enum membarrier_cmd - membarrier system call command32 * @MEMBARRIER_CMD_QUERY: Query the set of supported commands. It returns33 * a bitmask of valid commands.34 * @MEMBARRIER_CMD_GLOBAL: Execute a memory barrier on all running threads.35 * Upon return from system call, the caller thread36 * is ensured that all running threads have passed37 * through a state where all memory accesses to38 * user-space addresses match program order between39 * entry to and return from the system call40 * (non-running threads are de facto in such a41 * state). This covers threads from all processes42 * running on the system. This command returns 0.43 * @MEMBARRIER_CMD_GLOBAL_EXPEDITED:44 * Execute a memory barrier on all running threads45 * of all processes which previously registered46 * with MEMBARRIER_CMD_REGISTER_GLOBAL_EXPEDITED.47 * Upon return from system call, the caller thread48 * is ensured that all running threads have passed49 * through a state where all memory accesses to50 * user-space addresses match program order between51 * entry to and return from the system call52 * (non-running threads are de facto in such a53 * state). This only covers threads from processes54 * which registered with55 * MEMBARRIER_CMD_REGISTER_GLOBAL_EXPEDITED.56 * This command returns 0. Given that57 * registration is about the intent to receive58 * the barriers, it is valid to invoke59 * MEMBARRIER_CMD_GLOBAL_EXPEDITED from a60 * non-registered process.61 * @MEMBARRIER_CMD_REGISTER_GLOBAL_EXPEDITED:62 * Register the process intent to receive63 * MEMBARRIER_CMD_GLOBAL_EXPEDITED memory64 * barriers. Always returns 0.65 * @MEMBARRIER_CMD_PRIVATE_EXPEDITED:66 * Execute a memory barrier on each running67 * thread belonging to the same process as the current68 * thread. Upon return from system call, the69 * caller thread is ensured that all its running70 * threads siblings have passed through a state71 * where all memory accesses to user-space72 * addresses match program order between entry73 * to and return from the system call74 * (non-running threads are de facto in such a75 * state). This only covers threads from the76 * same process as the caller thread. This77 * command returns 0 on success. The78 * "expedited" commands complete faster than79 * the non-expedited ones, they never block,80 * but have the downside of causing extra81 * overhead. A process needs to register its82 * intent to use the private expedited command83 * prior to using it, otherwise this command84 * returns -EPERM.85 * @MEMBARRIER_CMD_REGISTER_PRIVATE_EXPEDITED:86 * Register the process intent to use87 * MEMBARRIER_CMD_PRIVATE_EXPEDITED. Always88 * returns 0.89 * @MEMBARRIER_CMD_PRIVATE_EXPEDITED_SYNC_CORE:90 * In addition to provide memory ordering91 * guarantees described in92 * MEMBARRIER_CMD_PRIVATE_EXPEDITED, ensure93 * the caller thread, upon return from system94 * call, that all its running threads siblings95 * have executed a core serializing96 * instruction. (architectures are required to97 * guarantee that non-running threads issue98 * core serializing instructions before they99 * resume user-space execution). This only100 * covers threads from the same process as the101 * caller thread. This command returns 0 on102 * success. The "expedited" commands complete103 * faster than the non-expedited ones, they104 * never block, but have the downside of105 * causing extra overhead. If this command is106 * not implemented by an architecture, -EINVAL107 * is returned. A process needs to register its108 * intent to use the private expedited sync109 * core command prior to using it, otherwise110 * this command returns -EPERM.111 * @MEMBARRIER_CMD_REGISTER_PRIVATE_EXPEDITED_SYNC_CORE:112 * Register the process intent to use113 * MEMBARRIER_CMD_PRIVATE_EXPEDITED_SYNC_CORE.114 * If this command is not implemented by an115 * architecture, -EINVAL is returned.116 * Returns 0 on success.117 * @MEMBARRIER_CMD_PRIVATE_EXPEDITED_RSEQ:118 * Ensure the caller thread, upon return from119 * system call, that all its running thread120 * siblings have any currently running rseq121 * critical sections restarted if @flags122 * parameter is 0; if @flags parameter is123 * MEMBARRIER_CMD_FLAG_CPU,124 * then this operation is performed only125 * on CPU indicated by @cpu_id. If this command is126 * not implemented by an architecture, -EINVAL127 * is returned. A process needs to register its128 * intent to use the private expedited rseq129 * command prior to using it, otherwise130 * this command returns -EPERM.131 * @MEMBARRIER_CMD_REGISTER_PRIVATE_EXPEDITED_RSEQ:132 * Register the process intent to use133 * MEMBARRIER_CMD_PRIVATE_EXPEDITED_RSEQ.134 * If this command is not implemented by an135 * architecture, -EINVAL is returned.136 * Returns 0 on success.137 * @MEMBARRIER_CMD_SHARED:138 * Alias to MEMBARRIER_CMD_GLOBAL. Provided for139 * header backward compatibility.140 * @MEMBARRIER_CMD_GET_REGISTRATIONS:141 * Returns a bitmask of previously issued142 * registration commands.143 *144 * Command to be passed to the membarrier system call. The commands need to145 * be a single bit each, except for MEMBARRIER_CMD_QUERY which is assigned to146 * the value 0.147 */148enum membarrier_cmd {149 MEMBARRIER_CMD_QUERY = 0,150 MEMBARRIER_CMD_GLOBAL = (1 << 0),151 MEMBARRIER_CMD_GLOBAL_EXPEDITED = (1 << 1),152 MEMBARRIER_CMD_REGISTER_GLOBAL_EXPEDITED = (1 << 2),153 MEMBARRIER_CMD_PRIVATE_EXPEDITED = (1 << 3),154 MEMBARRIER_CMD_REGISTER_PRIVATE_EXPEDITED = (1 << 4),155 MEMBARRIER_CMD_PRIVATE_EXPEDITED_SYNC_CORE = (1 << 5),156 MEMBARRIER_CMD_REGISTER_PRIVATE_EXPEDITED_SYNC_CORE = (1 << 6),157 MEMBARRIER_CMD_PRIVATE_EXPEDITED_RSEQ = (1 << 7),158 MEMBARRIER_CMD_REGISTER_PRIVATE_EXPEDITED_RSEQ = (1 << 8),159 MEMBARRIER_CMD_GET_REGISTRATIONS = (1 << 9),160 161 /* Alias for header backward compatibility. */162 MEMBARRIER_CMD_SHARED = MEMBARRIER_CMD_GLOBAL,163};164 165enum membarrier_cmd_flag {166 MEMBARRIER_CMD_FLAG_CPU = (1 << 0),167};168 169#endif /* _UAPI_LINUX_MEMBARRIER_H */170