1 /* SPDX-License-Identifier: GPL-2.0 */ 2 #ifndef _ASM_X86_BARRIER_H 3 #define _ASM_X86_BARRIER_H 4 5 #include <asm/alternative.h> 6 #include <asm/nops.h> 7 8 /* 9 * Force strict CPU ordering. 10 * And yes, this might be required on UP too when we're talking 11 * to devices. 12 */ 13 14 #ifdef CONFIG_X86_32 15 #define mb() asm volatile(ALTERNATIVE("lock; addl $0,0(%%esp)", "mfence", \ 16 X86_FEATURE_XMM2) ::: "memory", "cc") 17 #define rmb() asm volatile(ALTERNATIVE("lock; addl $0,0(%%esp)", "lfence", \ 18 X86_FEATURE_XMM2) ::: "memory", "cc") 19 #define wmb() asm volatile(ALTERNATIVE("lock; addl $0,0(%%esp)", "sfence", \ 20 X86_FEATURE_XMM2) ::: "memory", "cc") 21 #else 22 #define mb() asm volatile("mfence":::"memory") 23 #define rmb() asm volatile("lfence":::"memory") 24 #define wmb() asm volatile("sfence" ::: "memory") 25 #endif 26 27 #ifdef CONFIG_X86_PPRO_FENCE 28 #define dma_rmb() rmb() 29 #else 30 #define dma_rmb() barrier() 31 #endif 32 #define dma_wmb() barrier() 33 34 #define __smp_mb() mb() 35 #define __smp_rmb() dma_rmb() 36 #define __smp_wmb() barrier() 37 #define __smp_store_mb(var, value) do { (void)xchg(&var, value); } while (0) 38 39 #if defined(CONFIG_X86_PPRO_FENCE) 40 41 /* 42 * For this option x86 doesn't have a strong TSO memory 43 * model and we should fall back to full barriers. 44 */ 45 46 #define __smp_store_release(p, v) \ 47 do { \ 48 compiletime_assert_atomic_type(*p); \ 49 __smp_mb(); \ 50 WRITE_ONCE(*p, v); \ 51 } while (0) 52 53 #define __smp_load_acquire(p) \ 54 ({ \ 55 typeof(*p) ___p1 = READ_ONCE(*p); \ 56 compiletime_assert_atomic_type(*p); \ 57 __smp_mb(); \ 58 ___p1; \ 59 }) 60 61 #else /* regular x86 TSO memory ordering */ 62 63 #define __smp_store_release(p, v) \ 64 do { \ 65 compiletime_assert_atomic_type(*p); \ 66 barrier(); \ 67 WRITE_ONCE(*p, v); \ 68 } while (0) 69 70 #define __smp_load_acquire(p) \ 71 ({ \ 72 typeof(*p) ___p1 = READ_ONCE(*p); \ 73 compiletime_assert_atomic_type(*p); \ 74 barrier(); \ 75 ___p1; \ 76 }) 77 78 #endif 79 80 /* Atomic operations are already serializing on x86 */ 81 #define __smp_mb__before_atomic() barrier() 82 #define __smp_mb__after_atomic() barrier() 83 84 #include <asm-generic/barrier.h> 85 86 #endif /* _ASM_X86_BARRIER_H */ 87