Disable alignment faults on armv6, adjust various alignment-related macros

to match the new state of affairs.  The hardware we support has always been
able to do unaligned accesses, we've just never enabled it until now.

This brings FreeBSD into line with all the other major OSes, and should help
with the growing volume of 3rd-party software that assumes unaligned access
will just work on armv6 and armv7.

3 files changed, 16 insertions, 0 deletions

diff --git a/sys/arm/include/_align.h b/sys/arm/include/_align.h
index 0791e45..e382fe2 100644
--- a/sys/arm/include/_align.h
+++ b/sys/arm/include/_align.h
@@ -46,7 +46,11 @@
  * is sufficient for any data type, pointer or numeric.  The resulting type
  * is equivelent to arm's uintptr_t (but is purposely spelled "unsigned" here).
  */
+#if __ARM_ARCH >= 6
+#define	_ALIGNBYTES	(sizeof(int) - 1)
+#else
 #define	_ALIGNBYTES	(sizeof(long long) - 1)
+#endif
 #define	_ALIGN(p)	(((unsigned)(p) + _ALIGNBYTES) & ~_ALIGNBYTES)
 
 #endif /* !_ARM_INCLUDE__ALIGN_H_ */
diff --git a/sys/arm/include/_types.h b/sys/arm/include/_types.h
index b627963..267ea83 100644
--- a/sys/arm/include/_types.h
+++ b/sys/arm/include/_types.h
@@ -43,6 +43,10 @@
 #error this file needs sys/cdefs.h as a prerequisite
 #endif
 
+#if __ARM_ARCH >= 6
+#define __NO_STRICT_ALIGNMENT
+#endif
+
 /*
  * Basic types upon which most other types are built.
  */
diff --git a/sys/arm/include/param.h b/sys/arm/include/param.h
index e96fe4a..0ad5493 100644
--- a/sys/arm/include/param.h
+++ b/sys/arm/include/param.h
@@ -90,8 +90,16 @@
  * is valid to fetch data elements of type t from on this architecture.
  * This does not reflect the optimal alignment, just the possibility
  * (within reasonable limits).
+ *
+ * armv4 and v5 require alignment to the type's size.  armv6 and later require
+ * that an 8-byte type be aligned to at least a 4-byte boundary; access to
+ * smaller types can be unaligned.
  */
+#if __ARM_ARCH >= 6
+#define	ALIGNED_POINTER(p, t)	(((sizeof(t) != 8) || ((unsigned)(p) & 3) == 0))
+#else
 #define	ALIGNED_POINTER(p, t)	((((unsigned)(p)) & (sizeof(t)-1)) == 0)
+#endif
 
 /*
  * CACHE_LINE_SIZE is the compile-time maximum cache line size for an