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1 | #ifndef _ASM_UM_BARRIER_H_ |
2 | #define _ASM_UM_BARRIER_H_ | |
3 | ||
4 | #include <asm/asm.h> | |
5 | #include <asm/segment.h> | |
6 | #include <asm/cpufeature.h> | |
7 | #include <asm/cmpxchg.h> | |
8 | #include <asm/nops.h> | |
9 | ||
10 | #include <linux/kernel.h> | |
11 | #include <linux/irqflags.h> | |
12 | ||
13 | /* | |
14 | * Force strict CPU ordering. | |
15 | * And yes, this is required on UP too when we're talking | |
16 | * to devices. | |
17 | */ | |
18 | #ifdef CONFIG_X86_32 | |
19 | ||
20 | #define mb() alternative("lock; addl $0,0(%%esp)", "mfence", X86_FEATURE_XMM2) | |
21 | #define rmb() alternative("lock; addl $0,0(%%esp)", "lfence", X86_FEATURE_XMM2) | |
22 | #define wmb() alternative("lock; addl $0,0(%%esp)", "sfence", X86_FEATURE_XMM) | |
23 | ||
24 | #else /* CONFIG_X86_32 */ | |
25 | ||
26 | #define mb() asm volatile("mfence" : : : "memory") | |
27 | #define rmb() asm volatile("lfence" : : : "memory") | |
28 | #define wmb() asm volatile("sfence" : : : "memory") | |
29 | ||
30 | #endif /* CONFIG_X86_32 */ | |
31 | ||
32 | #define read_barrier_depends() do { } while (0) | |
33 | ||
34 | #ifdef CONFIG_SMP | |
35 | ||
36 | #define smp_mb() mb() | |
37 | #ifdef CONFIG_X86_PPRO_FENCE | |
38 | #define smp_rmb() rmb() | |
39 | #else /* CONFIG_X86_PPRO_FENCE */ | |
40 | #define smp_rmb() barrier() | |
41 | #endif /* CONFIG_X86_PPRO_FENCE */ | |
42 | ||
a3a85a76 | 43 | #define smp_wmb() barrier() |
a3a85a76 RW |
44 | |
45 | #define smp_read_barrier_depends() read_barrier_depends() | |
46 | #define set_mb(var, value) do { (void)xchg(&var, value); } while (0) | |
47 | ||
48 | #else /* CONFIG_SMP */ | |
49 | ||
50 | #define smp_mb() barrier() | |
51 | #define smp_rmb() barrier() | |
52 | #define smp_wmb() barrier() | |
53 | #define smp_read_barrier_depends() do { } while (0) | |
54 | #define set_mb(var, value) do { var = value; barrier(); } while (0) | |
55 | ||
56 | #endif /* CONFIG_SMP */ | |
57 | ||
58 | /* | |
59 | * Stop RDTSC speculation. This is needed when you need to use RDTSC | |
60 | * (or get_cycles or vread that possibly accesses the TSC) in a defined | |
61 | * code region. | |
62 | * | |
63 | * (Could use an alternative three way for this if there was one.) | |
64 | */ | |
65 | static inline void rdtsc_barrier(void) | |
66 | { | |
67 | alternative(ASM_NOP3, "mfence", X86_FEATURE_MFENCE_RDTSC); | |
68 | alternative(ASM_NOP3, "lfence", X86_FEATURE_LFENCE_RDTSC); | |
69 | } | |
70 | ||
71 | #endif |