| Current File : //usr/include/linux/membarrier.h |
#ifndef _LINUX_MEMBARRIER_H
#define _LINUX_MEMBARRIER_H
/*
* linux/membarrier.h
*
* membarrier system call API
*
* Copyright (c) 2010, 2015 Mathieu Desnoyers <[email protected]>
*
* 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 */