Index: sys/arm64/include/xen/synch_bitops.h
===================================================================
--- /dev/null
+++ sys/arm64/include/xen/synch_bitops.h
@@ -0,0 +1,156 @@
+/*
+ * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
+ *
+ * Copyright (c) 2014 Julien Grall
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ *
+ * $FreeBSD$
+ */
+
+#ifndef __MACHINE_XEN_SYNCH_BITOPS_H__
+#define __MACHINE_XEN_SYNCH_BITOPS_H__
+
+#define synch_cmpxchg(ptr, old, new)				\
+    ((__typeof__(*(ptr)))__synch_cmpxchg((ptr),			\
+	(unsigned long)(old),					\
+	(unsigned long)(new),					\
+        sizeof(*(ptr))))
+
+static inline uint8_t
+__synch_cmpxchg_8(volatile uint8_t *ptr, uint8_t old, uint8_t new)
+{
+	uint8_t prev = *ptr;
+
+	/* atomic_cmpset_acq_* returns 0 on failure */
+	return (atomic_cmpset_acq_8(ptr, old, new) ? prev : new);
+}
+
+static inline uint16_t
+__synch_cmpxchg_16(volatile uint16_t *ptr, uint16_t old, uint16_t new)
+{
+	uint16_t prev = *ptr;
+
+	/* atomic_cmpset_acq_* returns 0 on failure */
+	return (atomic_cmpset_acq_16(ptr, old, new) ? prev : new);
+}
+
+static inline uint32_t
+__synch_cmpxchg_32(volatile uint32_t *ptr, uint32_t old, uint32_t new)
+{
+	uint32_t prev = *ptr;
+
+	/* atomic_cmpset_acq_* returns 0 on failure */
+	return (atomic_cmpset_acq_32(ptr, old, new) ? prev : new);
+}
+
+static inline uint64_t
+__synch_cmpxchg_64(volatile uint64_t *ptr, uint64_t old, uint64_t new)
+{
+	uint64_t prev = *ptr;
+
+	/* atomic_cmpset_acq_* returns 0 on failure */
+	return (atomic_cmpset_acq_64(ptr, old, new) ? prev : new);
+}
+
+/* Use to get a linker error if the size is not supported by __synch_cmpxchg */
+void
+__synch_bad_size(void);
+
+static inline unsigned long
+__synch_cmpxchg(volatile void *ptr, unsigned long old,
+    unsigned long new, int size)
+{
+	switch (size) {
+	case 1:
+		return __synch_cmpxchg_8(ptr, old, new);
+	case 2:
+		return __synch_cmpxchg_16(ptr, old, new);
+	case 4:
+		return __synch_cmpxchg_32(ptr, old, new);
+	case 8:
+		return __synch_cmpxchg_64(ptr, old, new);
+	default:
+		__synch_bad_size();
+		return old;
+	}
+}
+
+/*
+ * Based on ofed/include/linux/bitops.h
+ */
+#define NBPL (NBBY * sizeof(long))
+
+static inline bool
+synch_test_bit(u_int bit, volatile long *addr)
+{
+	unsigned long mask = 1UL << (bit % NBPL);
+
+	return !!(atomic_load_acq_long(&addr[bit / NBPL]) & mask);
+}
+
+static inline void
+synch_set_bit(u_int bit, volatile long *addr)
+{
+	atomic_set_long(&addr[bit / NBPL], 1UL << (bit % NBPL));
+}
+
+static inline void
+synch_clear_bit(u_int bit, volatile long *addr)
+{
+	atomic_clear_long(&addr[bit / NBPL], 1UL << (bit % NBPL));
+}
+
+static inline bool
+synch_test_and_clear_bit(u_int bit, long *addr)
+{
+	long val;
+
+	addr += bit / NBPL;
+	bit %= NBPL;
+	bit = (1UL << bit);
+	do {
+		val = *(volatile long *)addr;
+	} while (atomic_cmpset_long(addr, val, val & ~bit) == 0);
+
+	return !!(val & bit);
+}
+
+static inline bool
+synch_test_and_set_bit(u_int bit, long *addr)
+{
+	long val;
+
+	addr += bit / NBPL;
+	bit %= NBPL;
+	bit = (1UL << bit);
+	do {
+		val = *(volatile long *)addr;
+	} while (atomic_cmpset_long(addr, val, val | bit) == 0);
+
+	return !!(val & bit);
+}
+
+#undef NBPL
+
+#endif /* __MACHINE_XEN_SYNCH_BITOPS_H__ */
+