types.h: define __aligned_u64 and expose to userspace (79b5dc0c) · Commits · 戴 / test

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>

include/linux/types.h

+14 −1

Original line number	Diff line number	Diff line
		@@ -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;

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