LinuxKPI: Implement smp_*mb barriers with atomic_thread_fence_*

for x86 and move them to asm/barrier.h

MFC after:	1 week
Reviewed by:	bz, hselasky, manu
Differential Revision:	https://reviews.freebsd.org/D33296

(cherry picked from commit 2fb5be7978c27505c02b667a21ce3a79f72e2091)

3 files changed, 59 insertions, 1 deletions

diff --git a/sys/compat/linuxkpi/common/include/asm/barrier.h b/sys/compat/linuxkpi/common/include/asm/barrier.h
new file mode 100644
index 000000000000..10aa24a7ae8b
--- /dev/null
+++ b/sys/compat/linuxkpi/common/include/asm/barrier.h
@@ -0,0 +1,58 @@
+/*-
+ * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
+ *
+ * Copyright (c) 2021 Vladimir Kondratyev <wulf@FreeBSD.org>
+ *
+ * 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 unmodified, 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 ``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 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.
+ */
+
+#ifndef _ASM_BARRIER_H_
+#define	_ASM_BARRIER_H_
+
+#include <sys/types.h>
+#include <machine/atomic.h>
+
+#include <asm/atomic.h>
+#include <linux/compiler.h>
+
+/* TODO: Check other archs for atomic_thread_fence_* useability */
+#if defined(__amd64__) || defined(__i386__)
+#define	smp_mb()	atomic_thread_fence_seq_cst()
+#define	smp_wmb()	atomic_thread_fence_rel()
+#define	smp_rmb()	atomic_thread_fence_acq()
+#define	smp_store_mb(x, v)	do { (void)xchg(&(x), v); } while (0)
+#endif
+
+#ifndef	smp_mb
+#define	smp_mb()	mb()
+#endif
+#ifndef	smp_wmb
+#define	smp_wmb()	wmb()
+#endif
+#ifndef	smp_rmb
+#define	smp_rmb()	rmb()
+#endif
+#ifndef	smp_store_mb
+#define	smp_store_mb(x, v)	do { WRITE_ONCE(x, v); smp_mb(); } while (0)
+#endif
+
+#endif	/* _ASM_BARRIER_H_ */
diff --git a/sys/compat/linuxkpi/common/include/linux/atomic.h b/sys/compat/linuxkpi/common/include/linux/atomic.h
index f8aa5c9276e7..969af384e3ba 100644
--- a/sys/compat/linuxkpi/common/include/linux/atomic.h
+++ b/sys/compat/linuxkpi/common/include/linux/atomic.h
@@ -32,5 +32,6 @@
 #include <asm/atomic.h>
 #include <asm/atomic64.h>
 #include <asm/atomic-long.h>
+#include <asm/barrier.h>
 
 #endif /* _LINUX_ATOMIC_H_ */
diff --git a/sys/compat/linuxkpi/common/include/linux/compiler.h b/sys/compat/linuxkpi/common/include/linux/compiler.h
index e641b1b096c3..c4c189c2505f 100644
--- a/sys/compat/linuxkpi/common/include/linux/compiler.h
+++ b/sys/compat/linuxkpi/common/include/linux/compiler.h
@@ -80,7 +80,6 @@
 #define	__printf(a,b)			__printflike(a,b)
 
 #define	barrier()			__asm__ __volatile__("": : :"memory")
-#define	smp_mb()			mb()
 
 #define	lower_32_bits(n)		((u32)(n))
 #define	upper_32_bits(n)		((u32)(((n) >> 16) >> 16))