Index: head/sys/compat/linuxkpi/common/include/linux/bitfield.h
===================================================================
--- head/sys/compat/linuxkpi/common/include/linux/bitfield.h
+++ head/sys/compat/linuxkpi/common/include/linux/bitfield.h
@@ -0,0 +1,105 @@
+/*-
+ * SPDX-License-Identifier: BSD-2-Clause
+ *
+ * Copyright (c) 2020 The FreeBSD Foundation
+ *
+ * This software was developed by Björn Zeeb under sponsorship from
+ * the FreeBSD Foundation.
+ *
+ * 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	_LINUX_BITFIELD_H
+#define	_LINUX_BITFIELD_H
+
+#include <linux/types.h>
+#include <asm/byteorder.h>
+
+/* Use largest possible type. */
+static inline uint64_t ___lsb(uint64_t f) { return (f & -f); }
+static inline uint64_t ___bitmask(uint64_t f) { return (f / ___lsb(f)); }
+
+#define	_uX_get_bits(_n)						\
+	static __inline uint ## _n ## _t				\
+	u ## _n ## _get_bits(uint ## _n ## _t v, uint ## _n ## _t f)	\
+	{								\
+		return ((v & f) / ___lsb(f));				\
+	}
+
+_uX_get_bits(64)
+_uX_get_bits(32)
+_uX_get_bits(16)
+_uX_get_bits(8)
+
+#define	_leX_get_bits(_n)						\
+	static __inline uint ## _n ## _t				\
+	le ## _n ## _get_bits(__le ## _n v, uint ## _n ## _t f)		\
+	{								\
+		return ((le ## _n ## _to_cpu(v) & f) / ___lsb(f));	\
+	}
+
+_leX_get_bits(64)
+_leX_get_bits(32)
+_leX_get_bits(16)
+
+#define	_uX_encode_bits(_n)						\
+	static __inline uint ## _n ## _t				\
+	u ## _n ## _encode_bits(uint ## _n ## _t v, uint ## _n ## _t f)	\
+	{								\
+		return ((v & ___bitmask(f)) * ___lsb(f));		\
+	}
+
+_uX_encode_bits(64)
+_uX_encode_bits(32)
+_uX_encode_bits(16)
+_uX_encode_bits(8)
+
+#define	_leX_encode_bits(_n)						\
+	static __inline uint ## _n ## _t				\
+	le ## _n ## _encode_bits(__le ## _n v, uint ## _n ## _t f)\
+	{								\
+		return (cpu_to_le ## _n((v & ___bitmask(f)) * ___lsb(f))); \
+	}
+
+_leX_encode_bits(64)
+_leX_encode_bits(32)
+_leX_encode_bits(16)
+
+static __inline void
+le32p_replace_bits(uint32_t *p, uint32_t v, uint32_t f)
+{
+
+	*p = (*p & ~(cpu_to_le32(v))) | le32_encode_bits(v, f);
+	return;
+}
+
+#define	__bf_shf(x)	(__builtin_ffsll(x) - 1)
+
+#define	FIELD_PREP(_mask, _value)					\
+	(((typeof(_mask))(_value) << __bf_shf(_mask)) & (_mask))
+
+#define	FIELD_GET(_mask, _value)					\
+	((typeof(_mask))(((_value) & (_mask)) >> __bf_shf(_mask)))
+
+#endif	/* _LINUX_BITFIELD_H */