X-Git-Url: https://git.efficios.com/?a=blobdiff_plain;f=include%2Fside%2Fmacros.h;h=20fa97e804f07d76aae19d2afe1fe765620e6812;hb=053076a034894718038e3478904f373da9a242f9;hp=aea7b9ca5e71c12de16afb752213572515cffff3;hpb=d0ee69ff824fa3a480c520896d0a69385306a204;p=libside.git

diff --git a/include/side/macros.h b/include/side/macros.h
index aea7b9c..20fa97e 100644
--- a/include/side/macros.h
+++ b/include/side/macros.h
@@ -72,13 +72,55 @@
 	sizeof(((_struct * )NULL)->_field)
 
 #if defined(__SIZEOF_LONG__)
-#define SIDE_BITS_PER_LONG	(__SIZEOF_LONG__ * 8)
+# define SIDE_BITS_PER_LONG	(__SIZEOF_LONG__ * 8)
 #elif defined(_LP64)
-#define SIDE_BITS_PER_LONG	64
+# define SIDE_BITS_PER_LONG	64
 #else
-#define SIDE_BITS_PER_LONG	32
+# define SIDE_BITS_PER_LONG	32
 #endif
 
 #define SIDE_PACKED	__attribute__((packed))
 
+/*
+ * The side_ptr macros allow defining a pointer type which is suitable
+ * for use by 32-bit and 64-bit kernels without compatibility code,
+ * while preserving information about the pointer type.
+ *
+ * Those pointers are stored as 64-bit integers, and the type of the
+ * actual pointer is kept alongside with the 64-bit pointer value in a
+ * 0-len array within a union.
+ *
+ * uintptr_t will fit within a uint64_t except on architectures with
+ * 128-bit pointers. This provides fixed-size pointers on architectures
+ * with pointer size of 64-bit or less. Architectures with larger
+ * pointer size will have to handle the ABI offset specifics explicitly.
+ */
+#if (__SIZEOF_POINTER__ <= 8)
+# define side_ptr_t(_type)					\
+	union {							\
+		uint64_t v;					\
+		_type *t[0];					\
+	}
+# define side_ptr_get(_field)					\
+	((__typeof__((_field).t[0]))(uintptr_t)(_field).v)
+# define side_ptr_set(_field, _ptr)				\
+	do {							\
+		(_field).v = (uint64_t)(uintptr_t)(_ptr);	\
+	} while (0)
+#else
+# define side_ptr_t(_type)					\
+	union {							\
+		uintptr_t v;					\
+		_type *t[0];					\
+	}
+# define side_ptr_get(_field)					\
+	((__typeof__((_field).t[0]))(_field).v)
+# define side_ptr_set(_field, _ptr)				\
+	do {							\
+		(_field).v = (uintptr_t)(_ptr);			\
+	} while (0)
+#endif
+
+#define SIDE_PTR_INIT(...)	{ .v = (uintptr_t) (__VA_ARGS__) }
+
 #endif /* _SIDE_MACROS_H */