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![Mathieu Desnoyers](/assets/img/avatar_default.png)
Provide core serializing membarrier command to support memory reclaim by JIT. Each architecture needs to explicitly opt into that support by documenting in their architecture code how they provide the core serializing instructions required when returning from the membarrier IPI, and after the scheduler has updated the curr->mm pointer (before going back to user-space). They should then select ARCH_HAS_MEMBARRIER_SYNC_CORE to enable support for that command on their architecture. Architectures selecting this feature need to either document that they issue core serializing instructions when returning to user-space, or implement their architecture-specific sync_core_before_usermode(). Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Acked-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Andrea Parri <parri.andrea@gmail.com> Cc: Andrew Hunter <ahh@google.com> Cc: Andy Lutomirski <luto@kernel.org> Cc: Avi Kivity <avi@scylladb.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Boqun Feng <boqun.feng@gmail.com> Cc: Dave Watson <davejwatson@fb.com> Cc: David Sehr <sehr@google.com> Cc: Greg Hackmann <ghackmann@google.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Maged Michael <maged.michael@gmail.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Russell King <linux@armlinux.org.uk> Cc: Will Deacon <will.deacon@arm.com> Cc: linux-api@vger.kernel.org Cc: linux-arch@vger.kernel.org Link: http://lkml.kernel.org/r/20180129202020.8515-9-mathieu.desnoyers@efficios.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
139 lines
7.7 KiB
C
139 lines
7.7 KiB
C
#ifndef _UAPI_LINUX_MEMBARRIER_H
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#define _UAPI_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 /* _UAPI_LINUX_MEMBARRIER_H */
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