| Arnaldo Carvalho de Melo | 163e589 | 2015-05-07 18:03:14 -0300 | [diff] [blame] | 1 | /* |
| 2 | * Copied from the kernel sources to tools/: |
| 3 | * |
| 4 | * Memory barrier definitions. This is based on information published |
| 5 | * in the Processor Abstraction Layer and the System Abstraction Layer |
| 6 | * manual. |
| 7 | * |
| 8 | * Copyright (C) 1998-2003 Hewlett-Packard Co |
| 9 | * David Mosberger-Tang <davidm@hpl.hp.com> |
| 10 | * Copyright (C) 1999 Asit Mallick <asit.k.mallick@intel.com> |
| 11 | * Copyright (C) 1999 Don Dugger <don.dugger@intel.com> |
| 12 | */ |
| 13 | #ifndef _TOOLS_LINUX_ASM_IA64_BARRIER_H |
| 14 | #define _TOOLS_LINUX_ASM_IA64_BARRIER_H |
| 15 | |
| 16 | #include <linux/compiler.h> |
| 17 | |
| 18 | /* |
| 19 | * Macros to force memory ordering. In these descriptions, "previous" |
| 20 | * and "subsequent" refer to program order; "visible" means that all |
| 21 | * architecturally visible effects of a memory access have occurred |
| 22 | * (at a minimum, this means the memory has been read or written). |
| 23 | * |
| 24 | * wmb(): Guarantees that all preceding stores to memory- |
| 25 | * like regions are visible before any subsequent |
| 26 | * stores and that all following stores will be |
| 27 | * visible only after all previous stores. |
| 28 | * rmb(): Like wmb(), but for reads. |
| 29 | * mb(): wmb()/rmb() combo, i.e., all previous memory |
| 30 | * accesses are visible before all subsequent |
| 31 | * accesses and vice versa. This is also known as |
| 32 | * a "fence." |
| 33 | * |
| 34 | * Note: "mb()" and its variants cannot be used as a fence to order |
| 35 | * accesses to memory mapped I/O registers. For that, mf.a needs to |
| 36 | * be used. However, we don't want to always use mf.a because (a) |
| 37 | * it's (presumably) much slower than mf and (b) mf.a is supported for |
| 38 | * sequential memory pages only. |
| 39 | */ |
| 40 | |
| 41 | /* XXX From arch/ia64/include/uapi/asm/gcc_intrin.h */ |
| 42 | #define ia64_mf() asm volatile ("mf" ::: "memory") |
| 43 | |
| 44 | #define mb() ia64_mf() |
| 45 | #define rmb() mb() |
| 46 | #define wmb() mb() |
| 47 | |
| 48 | #endif /* _TOOLS_LINUX_ASM_IA64_BARRIER_H */ |