linux/include/asm-generic/unaligned.h
Arnd Bergmann 803f4e1eab asm-generic: simplify asm/unaligned.h
The get_unaligned()/put_unaligned() implementations are much more complex
than necessary, now that all architectures use the same code.

Move everything into one file and use a much more compact way to express
the same logic.

I've compared the binary output using gcc-11 across defconfig builds for
all architectures and found this patch to make no difference, except for
a single function on powerpc that needs two additional register moves
because of random differences in register allocation.

There are a handful of callers of the low-level __get_unaligned_cpu32,
so leave that in place for the time being even though the common code
no longer uses it.

This adds a warning for any caller of get_unaligned()/put_unaligned()
that passes in a single-byte pointer, but I've sent patches for all
instances that show up in x86 and randconfig builds. It would be nice
to change the arguments of the endian-specific accessors to take the
matching __be16/__be32/__be64/__le16/__le32/__le64 arguments instead of
a void pointer, but that requires more changes to the rest of the kernel.

This new version does allow aggregate types into get_unaligned(), which
was not the original goal but might come in handy.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
2021-05-17 13:30:29 +02:00

130 lines
2.8 KiB
C

/* SPDX-License-Identifier: GPL-2.0 */
#ifndef __ASM_GENERIC_UNALIGNED_H
#define __ASM_GENERIC_UNALIGNED_H
/*
* This is the most generic implementation of unaligned accesses
* and should work almost anywhere.
*/
#include <linux/unaligned/packed_struct.h>
#include <asm/byteorder.h>
#define __get_unaligned_t(type, ptr) ({ \
const struct { type x; } __packed *__pptr = (typeof(__pptr))(ptr); \
__pptr->x; \
})
#define __put_unaligned_t(type, val, ptr) do { \
struct { type x; } __packed *__pptr = (typeof(__pptr))(ptr); \
__pptr->x = (val); \
} while (0)
#define get_unaligned(ptr) __get_unaligned_t(typeof(*(ptr)), (ptr))
#define put_unaligned(val, ptr) __put_unaligned_t(typeof(*(ptr)), (val), (ptr))
static inline u16 get_unaligned_le16(const void *p)
{
return le16_to_cpu(__get_unaligned_t(__le16, p));
}
static inline u32 get_unaligned_le32(const void *p)
{
return le32_to_cpu(__get_unaligned_t(__le32, p));
}
static inline u64 get_unaligned_le64(const void *p)
{
return le64_to_cpu(__get_unaligned_t(__le64, p));
}
static inline void put_unaligned_le16(u16 val, void *p)
{
__put_unaligned_t(__le16, cpu_to_le16(val), p);
}
static inline void put_unaligned_le32(u32 val, void *p)
{
__put_unaligned_t(__le32, cpu_to_le32(val), p);
}
static inline void put_unaligned_le64(u64 val, void *p)
{
__put_unaligned_t(__le64, cpu_to_le64(val), p);
}
static inline u16 get_unaligned_be16(const void *p)
{
return be16_to_cpu(__get_unaligned_t(__be16, p));
}
static inline u32 get_unaligned_be32(const void *p)
{
return be32_to_cpu(__get_unaligned_t(__be32, p));
}
static inline u64 get_unaligned_be64(const void *p)
{
return be64_to_cpu(__get_unaligned_t(__be64, p));
}
static inline void put_unaligned_be16(u16 val, void *p)
{
__put_unaligned_t(__be16, cpu_to_be16(val), p);
}
static inline void put_unaligned_be32(u32 val, void *p)
{
__put_unaligned_t(__be32, cpu_to_be32(val), p);
}
static inline void put_unaligned_be64(u64 val, void *p)
{
__put_unaligned_t(__be64, cpu_to_be64(val), p);
}
static inline u32 __get_unaligned_be24(const u8 *p)
{
return p[0] << 16 | p[1] << 8 | p[2];
}
static inline u32 get_unaligned_be24(const void *p)
{
return __get_unaligned_be24(p);
}
static inline u32 __get_unaligned_le24(const u8 *p)
{
return p[0] | p[1] << 8 | p[2] << 16;
}
static inline u32 get_unaligned_le24(const void *p)
{
return __get_unaligned_le24(p);
}
static inline void __put_unaligned_be24(const u32 val, u8 *p)
{
*p++ = val >> 16;
*p++ = val >> 8;
*p++ = val;
}
static inline void put_unaligned_be24(const u32 val, void *p)
{
__put_unaligned_be24(val, p);
}
static inline void __put_unaligned_le24(const u32 val, u8 *p)
{
*p++ = val;
*p++ = val >> 8;
*p++ = val >> 16;
}
static inline void put_unaligned_le24(const u32 val, void *p)
{
__put_unaligned_le24(val, p);
}
#endif /* __ASM_GENERIC_UNALIGNED_H */