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-rw-r--r--include/linux/types.h15
1 files changed, 14 insertions, 1 deletions
diff --git a/include/linux/types.h b/include/linux/types.h
index 01a082f56ef..357dbc19606 100644
--- a/include/linux/types.h
+++ b/include/linux/types.h
@@ -121,7 +121,15 @@ typedef __u64 u_int64_t;
typedef __s64 int64_t;
#endif
-/* this is a special 64bit data type that is 8-byte aligned */
+/*
+ * aligned_u64 should be used in defining kernel<->userspace ABIs to avoid
+ * common 32/64-bit compat problems.
+ * 64-bit values align to 4-byte boundaries on x86_32 (and possibly other
+ * architectures) and to 8-byte boundaries on 64-bit architetures. The new
+ * aligned_64 type enforces 8-byte alignment so that structs containing
+ * aligned_64 values have the same alignment on 32-bit and 64-bit architectures.
+ * No conversions are necessary between 32-bit user-space and a 64-bit kernel.
+ */
#define aligned_u64 __u64 __attribute__((aligned(8)))
#define aligned_be64 __be64 __attribute__((aligned(8)))
#define aligned_le64 __le64 __attribute__((aligned(8)))
@@ -178,6 +186,11 @@ typedef __u64 __bitwise __be64;
typedef __u16 __bitwise __sum16;
typedef __u32 __bitwise __wsum;
+/* this is a special 64bit data type that is 8-byte aligned */
+#define __aligned_u64 __u64 __attribute__((aligned(8)))
+#define __aligned_be64 __be64 __attribute__((aligned(8)))
+#define __aligned_le64 __le64 __attribute__((aligned(8)))
+
#ifdef __KERNEL__
typedef unsigned __bitwise__ gfp_t;
typedef unsigned __bitwise__ fmode_t;