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-rw-r--r--tools/arch/ia64/include/asm/barrier.h46
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diff --git a/tools/arch/ia64/include/asm/barrier.h b/tools/arch/ia64/include/asm/barrier.h
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+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copied from the kernel sources to tools/:
+ *
+ * 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 <davidm@hpl.hp.com>
+ * Copyright (C) 1999 Asit Mallick <asit.k.mallick@intel.com>
+ * Copyright (C) 1999 Don Dugger <don.dugger@intel.com>
+ */
+#ifndef _TOOLS_LINUX_ASM_IA64_BARRIER_H
+#define _TOOLS_LINUX_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()
+
+#endif /* _TOOLS_LINUX_ASM_IA64_BARRIER_H */