From 33a19e0fd9b22364d295351ea1bda57b80e39e85 Mon Sep 17 00:00:00 2001
From: Brian Behlendorf <behlendorf1@llnl.gov>
Date: Wed, 11 Jul 2018 13:10:40 -0700
Subject: [PATCH] Fix kernel unaligned access on sparc64

Update the SA_COPY_DATA macro to check if architecture supports
efficient unaligned memory accesses at compile time.  Otherwise
fallback to using the sa_copy_data() function.

The kernel provided CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS is
used to determine availability in kernel space.  In user space
the x86_64, x86, powerpc, and sometimes arm architectures will
define the HAVE_EFFICIENT_UNALIGNED_ACCESS macro.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #7642
Closes #7684
---
 include/spl/sys/isa_defs.h        |  8 +++++++
 lib/libspl/include/sys/isa_defs.h |  7 +++++++
 module/icp/algs/modes/ccm.c       |  2 +-
 module/zfs/sa.c                   | 35 ++++++++++++++++++-------------
 4 files changed, 36 insertions(+), 16 deletions(-)

diff --git a/include/spl/sys/isa_defs.h b/include/spl/sys/isa_defs.h
index 089ae0f85e..1eb4002779 100644
--- a/include/spl/sys/isa_defs.h
+++ b/include/spl/sys/isa_defs.h
@@ -210,6 +210,14 @@
 
 #include <sys/byteorder.h>
 
+/*
+ * CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS will be defined by the Linux
+ * kernel for architectures which support efficient unaligned access.
+ */
+#if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)
+#define	HAVE_EFFICIENT_UNALIGNED_ACCESS
+#endif
+
 #if defined(__LITTLE_ENDIAN) && !defined(_LITTLE_ENDIAN)
 #define	_LITTLE_ENDIAN __LITTLE_ENDIAN
 #endif
diff --git a/lib/libspl/include/sys/isa_defs.h b/lib/libspl/include/sys/isa_defs.h
index a5bea0396e..7a90e077e8 100644
--- a/lib/libspl/include/sys/isa_defs.h
+++ b/lib/libspl/include/sys/isa_defs.h
@@ -55,6 +55,7 @@ extern "C" {
 #endif
 
 #define	_SUNOS_VTOC_16
+#define	HAVE_EFFICIENT_UNALIGNED_ACCESS
 
 /* i386 arch specific defines */
 #elif defined(__i386) || defined(__i386__)
@@ -76,6 +77,7 @@ extern "C" {
 #endif
 
 #define	_SUNOS_VTOC_16
+#define	HAVE_EFFICIENT_UNALIGNED_ACCESS
 
 /* powerpc arch specific defines */
 #elif defined(__powerpc) || defined(__powerpc__) || defined(__powerpc64__)
@@ -99,6 +101,7 @@ extern "C" {
 #endif
 
 #define	_SUNOS_VTOC_16
+#define	HAVE_EFFICIENT_UNALIGNED_ACCESS
 
 /* arm arch specific defines */
 #elif defined(__arm) || defined(__arm__) || defined(__aarch64__)
@@ -129,6 +132,10 @@ extern "C" {
 
 #define	_SUNOS_VTOC_16
 
+#if defined(__ARM_FEATURE_UNALIGNED)
+#define	HAVE_EFFICIENT_UNALIGNED_ACCESS
+#endif
+
 /* sparc arch specific defines */
 #elif defined(__sparc) || defined(__sparc__)
 
diff --git a/module/icp/algs/modes/ccm.c b/module/icp/algs/modes/ccm.c
index 22aeb0a6aa..fb41194f81 100644
--- a/module/icp/algs/modes/ccm.c
+++ b/module/icp/algs/modes/ccm.c
@@ -28,7 +28,7 @@
 #include <sys/crypto/common.h>
 #include <sys/crypto/impl.h>
 
-#if defined(__i386) || defined(__amd64)
+#ifdef HAVE_EFFICIENT_UNALIGNED_ACCESS
 #include <sys/byteorder.h>
 #define	UNALIGNED_POINTERS_PERMITTED
 #endif
diff --git a/module/zfs/sa.c b/module/zfs/sa.c
index 0ca33e80d7..caa91bc4c4 100644
--- a/module/zfs/sa.c
+++ b/module/zfs/sa.c
@@ -150,21 +150,26 @@ arc_byteswap_func_t sa_bswap_table[] = {
 	zfs_acl_byteswap,
 };
 
-#define	SA_COPY_DATA(f, s, t, l) \
-	{ \
-		if (f == NULL) { \
-			if (l == 8) { \
-				*(uint64_t *)t = *(uint64_t *)s; \
-			} else if (l == 16) { \
-				*(uint64_t *)t = *(uint64_t *)s; \
-				*(uint64_t *)((uintptr_t)t + 8) = \
-				    *(uint64_t *)((uintptr_t)s + 8); \
-			} else { \
-				bcopy(s, t, l); \
-			} \
-		} else \
-			sa_copy_data(f, s, t, l); \
-	}
+#ifdef HAVE_EFFICIENT_UNALIGNED_ACCESS
+#define	SA_COPY_DATA(f, s, t, l)				\
+do {								\
+	if (f == NULL) {					\
+		if (l == 8) {					\
+			*(uint64_t *)t = *(uint64_t *)s;	\
+		} else if (l == 16) {				\
+			*(uint64_t *)t = *(uint64_t *)s;	\
+			*(uint64_t *)((uintptr_t)t + 8) =	\
+			    *(uint64_t *)((uintptr_t)s + 8);	\
+		} else {					\
+			bcopy(s, t, l);				\
+		}						\
+	} else {						\
+		sa_copy_data(f, s, t, l);			\
+	}							\
+} while (0)
+#else
+#define	SA_COPY_DATA(f, s, t, l)	sa_copy_data(f, s, t, l)
+#endif
 
 /*
  * This table is fixed and cannot be changed.  Its purpose is to