unaligned.h File Reference

#include <linux/compiler_types.h>

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Macros
#define	__get_unaligned_t(type, ptr)
#define	__put_unaligned_t(type, val, ptr)

Macro Definition Documentation

__get_unaligned_t

#define __get_unaligned_t	(		type,
			ptr
	)

Value:

    ({                  \
    type *__get_unaligned_ctrl_type __always_unused = NULL;     \
    __unqual_scalar_typeof(*__get_unaligned_ctrl_type) __get_unaligned_val; \
    __builtin_memcpy(&__get_unaligned_val, (void *)(ptr),       \
             sizeof(__get_unaligned_val));          \
    __get_unaligned_val;                        \
})

__get_unaligned_t - read an unaligned value from memory. @type: the type to load from the pointer. @ptr: the pointer to load from.

Use memcpy to affect an unaligned type sized load avoiding undefined behavior from approaches like type punning that require -fno-strict-aliasing in order to be correct. As type may be const, use __unqual_scalar_typeof to map to a non-const type - you can't memcpy into a const type. The __get_unaligned_ctrl_type gives __unqual_scalar_typeof its required expression rather than type, a pointer is used to avoid warnings about mixing the use of 0 and NULL. The void* cast silences ubsan warnings.

__put_unaligned_t

#define __put_unaligned_t	(		type,
			val,
			ptr
	)

Value:

    do {                \
    type __put_unaligned_val = (val);               \
    __builtin_memcpy((void *)(ptr), &__put_unaligned_val,       \
             sizeof(__put_unaligned_val));          \
} while (0)

__put_unaligned_t - write an unaligned value to memory. @type: the type of the value to store. @val: the value to store. @ptr: the pointer to store to.

Use memcpy to affect an unaligned type sized store avoiding undefined behavior from approaches like type punning that require -fno-strict-aliasing in order to be correct. The void* cast silences ubsan warnings.