1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _ASM_UM_BARRIER_H_
3 #define _ASM_UM_BARRIER_H_
4
5 #include <asm/cpufeatures.h>
6 #include <asm/alternative.h>
7
8 /*
9 * Force strict CPU ordering.
10 * And yes, this is required on UP too when we're talking
11 * to devices.
12 */
13 #ifdef CONFIG_X86_32
14
15 #define mb() alternative("lock; addl $0,0(%%esp)", "mfence", X86_FEATURE_XMM2)
16 #define rmb() alternative("lock; addl $0,0(%%esp)", "lfence", X86_FEATURE_XMM2)
17 #define wmb() alternative("lock; addl $0,0(%%esp)", "sfence", X86_FEATURE_XMM)
18
19 #else /* CONFIG_X86_32 */
20
21 #define mb() asm volatile("mfence" : : : "memory")
22 #define rmb() asm volatile("lfence" : : : "memory")
23 #define wmb() asm volatile("sfence" : : : "memory")
24
25 #endif /* CONFIG_X86_32 */
26
27 #include <asm-generic/barrier.h>
28
29 #endif
30
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