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/* SPDX-License-Identifier: GPL-2.0 */ #ifndef _ASM_X86_BARRIER_H #define _ASM_X86_BARRIER_H #include <asm/alternative.h> #include <asm/nops.h> /* * Force strict CPU ordering. * And yes, this might be required on UP too when we're talking * to devices. */ #ifdef CONFIG_X86_32 #define mb() asm volatile(ALTERNATIVE("lock; addl $0,-4(%%esp)", "mfence", \ X86_FEATURE_XMM2) ::: "memory", "cc") #define rmb() asm volatile(ALTERNATIVE("lock; addl $0,-4(%%esp)", "lfence", \ X86_FEATURE_XMM2) ::: "memory", "cc") #define wmb() asm volatile(ALTERNATIVE("lock; addl $0,-4(%%esp)", "sfence", \ X86_FEATURE_XMM2) ::: "memory", "cc") #else #define mb() asm volatile("mfence":::"memory") #define rmb() asm volatile("lfence":::"memory") #define wmb() asm volatile("sfence" ::: "memory") #endif /** * array_index_mask_nospec() - generate a mask that is ~0UL when the * bounds check succeeds and 0 otherwise * @index: array element index * @size: number of elements in array * * Returns: * 0 - (index < size) */ static inline unsigned long array_index_mask_nospec(unsigned long index, unsigned long size) { unsigned long mask; asm volatile ("cmp %1,%2; sbb %0,%0;" :"=r" (mask) :"g"(size),"r" (index) :"cc"); return mask; } /* Override the default implementation from linux/nospec.h. */ #define array_index_mask_nospec array_index_mask_nospec /* Prevent speculative execution past this barrier. */ #define barrier_nospec() alternative("", "lfence", X86_FEATURE_LFENCE_RDTSC) #define dma_rmb() barrier() #define dma_wmb() barrier() #ifdef CONFIG_X86_32 #define __smp_mb() asm volatile("lock; addl $0,-4(%%esp)" ::: "memory", "cc") #else #define __smp_mb() asm volatile("lock; addl $0,-4(%%rsp)" ::: "memory", "cc") #endif #define __smp_rmb() dma_rmb() #define __smp_wmb() barrier() #define __smp_store_mb(var, value) do { (void)xchg(&var, value); } while (0) #define __smp_store_release(p, v) \ do { \ compiletime_assert_atomic_type(*p); \ barrier(); \ WRITE_ONCE(*p, v); \ } while (0) #define __smp_load_acquire(p) \ ({ \ typeof(*p) ___p1 = READ_ONCE(*p); \ compiletime_assert_atomic_type(*p); \ barrier(); \ ___p1; \ }) /* Atomic operations are already serializing on x86 */ #define __smp_mb__before_atomic() do { } while (0) #define __smp_mb__after_atomic() do { } while (0) #include <asm-generic/barrier.h> /* * Make previous memory operations globally visible before * a WRMSR. * * MFENCE makes writes visible, but only affects load/store * instructions. WRMSR is unfortunately not a load/store * instruction and is unaffected by MFENCE. The LFENCE ensures * that the WRMSR is not reordered. * * Most WRMSRs are full serializing instructions themselves and * do not require this barrier. This is only required for the * IA32_TSC_DEADLINE and X2APIC MSRs. */ static inline void weak_wrmsr_fence(void) { asm volatile("mfence; lfence" : : : "memory"); } #endif /* _ASM_X86_BARRIER_H */
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