blob: f6769eb2bbf9b5ff8774017ac0eb332fcc7309d9 [file] [log] [blame]
* Memory barrier definitions. This is based on information published
* in the Processor Abstraction Layer and the System Abstraction Layer
* manual.
* Copyright (C) 1998-2003 Hewlett-Packard Co
* David Mosberger-Tang <>
* Copyright (C) 1999 Asit Mallick <>
* Copyright (C) 1999 Don Dugger <>
#ifndef _ASM_IA64_BARRIER_H
#define _ASM_IA64_BARRIER_H
#include <linux/compiler.h>
* Macros to force memory ordering. In these descriptions, "previous"
* and "subsequent" refer to program order; "visible" means that all
* architecturally visible effects of a memory access have occurred
* (at a minimum, this means the memory has been read or written).
* wmb(): Guarantees that all preceding stores to memory-
* like regions are visible before any subsequent
* stores and that all following stores will be
* visible only after all previous stores.
* rmb(): Like wmb(), but for reads.
* mb(): wmb()/rmb() combo, i.e., all previous memory
* accesses are visible before all subsequent
* accesses and vice versa. This is also known as
* a "fence."
* Note: "mb()" and its variants cannot be used as a fence to order
* accesses to memory mapped I/O registers. For that, mf.a needs to
* be used. However, we don't want to always use mf.a because (a)
* it's (presumably) much slower than mf and (b) mf.a is supported for
* sequential memory pages only.
#define mb() ia64_mf()
#define rmb() mb()
#define wmb() mb()
#define dma_rmb() mb()
#define dma_wmb() mb()
# define smp_mb() mb()
# define smp_mb() barrier()
#define smp_rmb() smp_mb()
#define smp_wmb() smp_mb()
#define read_barrier_depends() do { } while (0)
#define smp_read_barrier_depends() do { } while (0)
#define smp_mb__before_atomic() barrier()
#define smp_mb__after_atomic() barrier()
* IA64 GCC turns volatile stores into st.rel and volatile loads into ld.acq no
* need for asm trickery!
#define smp_store_release(p, v) \
do { \
compiletime_assert_atomic_type(*p); \
barrier(); \
ACCESS_ONCE(*p) = (v); \
} while (0)
#define smp_load_acquire(p) \
({ \
typeof(*p) ___p1 = ACCESS_ONCE(*p); \
compiletime_assert_atomic_type(*p); \
barrier(); \
___p1; \
* XXX check on this ---I suspect what Linus really wants here is
* acquire vs release semantics but we can't discuss this stuff with
* Linus just yet. Grrr...
#define set_mb(var, value) do { (var) = (value); mb(); } while (0)
* The group barrier in front of the rsm & ssm are necessary to ensure
* that none of the previous instructions in the same group are
* affected by the rsm/ssm.
#endif /* _ASM_IA64_BARRIER_H */