v4.19.13 snapshot.
diff --git a/arch/x86/include/asm/barrier.h b/arch/x86/include/asm/barrier.h
new file mode 100644
index 0000000..14de043
--- /dev/null
+++ b/arch/x86/include/asm/barrier.h
@@ -0,0 +1,88 @@
+/* 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_2("", "mfence", X86_FEATURE_MFENCE_RDTSC, \
+ "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() barrier()
+#define __smp_mb__after_atomic() barrier()
+
+#include <asm-generic/barrier.h>
+
+#endif /* _ASM_X86_BARRIER_H */