diff options
| author | Eric Paris <eparis@redhat.com> | 2010-10-16 01:34:14 +0400 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2010-10-16 01:42:24 +0400 |
| commit | 79b5dc0c64d88cda3da23b2e22a5cec0964372ac (patch) | |
| tree | dffaf45200c456b87c4939ce422aea8efff1cfc8 /include/linux | |
| parent | e3c6cf61815b0af0c697aeed4c6f11762f913002 (diff) | |
| download | linux-79b5dc0c64d88cda3da23b2e22a5cec0964372ac.tar.xz | |
types.h: define __aligned_u64 and expose to userspace
We currently have a kernel internal type called aligned_u64 which aligns
__u64's on 8 bytes boundaries even on systems which would normally align
them on 4 byte boundaries. This patch creates a new type __aligned_u64
which does the same thing but which is exposed to userspace rather than
being kernel internal.
[akpm: merge early as both the net and audit trees want this]
[akpm@linux-foundation.org: enhance the comment describing the reasons for using aligned_u64. Via Andreas and Andi.]
Based-on-patch-by: Andreas Gruenbacher <agruen@suse.de>
Signed-off-by: Eric Paris <eparis@redhat.com>
Cc: Jan Engelhardt <jengelh@medozas.de>
Cc: David Miller <davem@davemloft.net>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include/linux')
| -rw-r--r-- | include/linux/types.h | 15 |
1 files changed, 14 insertions, 1 deletions
diff --git a/include/linux/types.h b/include/linux/types.h index 01a082f56ef4..357dbc19606f 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; |