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