--- /dev/null
+#ifndef _LINUX_MEMBARRIER_H
+#define _LINUX_MEMBARRIER_H
+
+/*
+ * linux/membarrier.h
+ *
+ * membarrier system call API
+ *
+ * Copyright (c) 2010, 2015 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+/**
+ * enum membarrier_cmd - membarrier system call command
+ * @MEMBARRIER_CMD_QUERY: Query the set of supported commands. It returns
+ * a bitmask of valid commands.
+ * @MEMBARRIER_CMD_GLOBAL: Execute a memory barrier on all running threads.
+ * Upon return from system call, the caller thread
+ * is ensured that all running threads have passed
+ * through a state where all memory accesses to
+ * user-space addresses match program order between
+ * entry to and return from the system call
+ * (non-running threads are de facto in such a
+ * state). This covers threads from all processes
+ * running on the system. This command returns 0.
+ * @MEMBARRIER_CMD_GLOBAL_EXPEDITED:
+ * Execute a memory barrier on all running threads
+ * of all processes which previously registered
+ * with MEMBARRIER_CMD_REGISTER_GLOBAL_EXPEDITED.
+ * Upon return from system call, the caller thread
+ * is ensured that all running threads have passed
+ * through a state where all memory accesses to
+ * user-space addresses match program order between
+ * entry to and return from the system call
+ * (non-running threads are de facto in such a
+ * state). This only covers threads from processes
+ * which registered with
+ * MEMBARRIER_CMD_REGISTER_GLOBAL_EXPEDITED.
+ * This command returns 0. Given that
+ * registration is about the intent to receive
+ * the barriers, it is valid to invoke
+ * MEMBARRIER_CMD_GLOBAL_EXPEDITED from a
+ * non-registered process.
+ * @MEMBARRIER_CMD_REGISTER_GLOBAL_EXPEDITED:
+ * Register the process intent to receive
+ * MEMBARRIER_CMD_GLOBAL_EXPEDITED memory
+ * barriers. Always returns 0.
+ * @MEMBARRIER_CMD_PRIVATE_EXPEDITED:
+ * Execute a memory barrier on each running
+ * thread belonging to the same process as the current
+ * thread. Upon return from system call, the
+ * caller thread is ensured that all its running
+ * threads siblings have passed through a state
+ * where all memory accesses to user-space
+ * addresses match program order between entry
+ * to and return from the system call
+ * (non-running threads are de facto in such a
+ * state). This only covers threads from the
+ * same process as the caller thread. This
+ * command returns 0 on success. The
+ * "expedited" commands complete faster than
+ * the non-expedited ones, they never block,
+ * but have the downside of causing extra
+ * overhead. A process needs to register its
+ * intent to use the private expedited command
+ * prior to using it, otherwise this command
+ * returns -EPERM.
+ * @MEMBARRIER_CMD_REGISTER_PRIVATE_EXPEDITED:
+ * Register the process intent to use
+ * MEMBARRIER_CMD_PRIVATE_EXPEDITED. Always
+ * returns 0.
+ * @MEMBARRIER_CMD_PRIVATE_EXPEDITED_SYNC_CORE:
+ * In addition to provide memory ordering
+ * guarantees described in
+ * MEMBARRIER_CMD_PRIVATE_EXPEDITED, ensure
+ * the caller thread, upon return from system
+ * call, that all its running threads siblings
+ * have executed a core serializing
+ * instruction. (architectures are required to
+ * guarantee that non-running threads issue
+ * core serializing instructions before they
+ * resume user-space execution). This only
+ * covers threads from the same process as the
+ * caller thread. This command returns 0 on
+ * success. The "expedited" commands complete
+ * faster than the non-expedited ones, they
+ * never block, but have the downside of
+ * causing extra overhead. If this command is
+ * not implemented by an architecture, -EINVAL
+ * is returned. A process needs to register its
+ * intent to use the private expedited sync
+ * core command prior to using it, otherwise
+ * this command returns -EPERM.
+ * @MEMBARRIER_CMD_REGISTER_PRIVATE_EXPEDITED_SYNC_CORE:
+ * Register the process intent to use
+ * MEMBARRIER_CMD_PRIVATE_EXPEDITED_SYNC_CORE.
+ * If this command is not implemented by an
+ * architecture, -EINVAL is returned.
+ * Returns 0 on success.
+ * @MEMBARRIER_CMD_SHARED:
+ * Alias to MEMBARRIER_CMD_GLOBAL. Provided for
+ * header backward compatibility.
+ *
+ * Command to be passed to the membarrier system call. The commands need to
+ * be a single bit each, except for MEMBARRIER_CMD_QUERY which is assigned to
+ * the value 0.
+ */
+enum membarrier_cmd {
+ MEMBARRIER_CMD_QUERY = 0,
+ MEMBARRIER_CMD_GLOBAL = (1 << 0),
+ MEMBARRIER_CMD_GLOBAL_EXPEDITED = (1 << 1),
+ MEMBARRIER_CMD_REGISTER_GLOBAL_EXPEDITED = (1 << 2),
+ MEMBARRIER_CMD_PRIVATE_EXPEDITED = (1 << 3),
+ MEMBARRIER_CMD_REGISTER_PRIVATE_EXPEDITED = (1 << 4),
+ MEMBARRIER_CMD_PRIVATE_EXPEDITED_SYNC_CORE = (1 << 5),
+ MEMBARRIER_CMD_REGISTER_PRIVATE_EXPEDITED_SYNC_CORE = (1 << 6),
+
+ /* Alias for header backward compatibility. */
+ MEMBARRIER_CMD_SHARED = MEMBARRIER_CMD_GLOBAL,
+};
+
+#endif /* _LINUX_MEMBARRIER_H */
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