1 files changed, 47 insertions, 0 deletions
diff --git a/include/linux/overflow.h b/include/linux/overflow.h
index 1d3be1a2204c..0e33b5cbdb9f 100644
--- a/include/linux/overflow.h
+++ b/include/linux/overflow.h
@@ -128,6 +128,53 @@ static inline bool __must_check __must_check_overflow(bool overflow)
 	(*_d >> _to_shift) != _a);					\
 }))
 
+#define __overflows_type_constexpr(x, T) (			\
+	is_unsigned_type(typeof(x)) ?				\
+		(x) > type_max(typeof(T)) :			\
+	is_unsigned_type(typeof(T)) ?				\
+		(x) < 0 || (x) > type_max(typeof(T)) :		\
+	(x) < type_min(typeof(T)) || (x) > type_max(typeof(T)))
+
+#define __overflows_type(x, T)		({	\
+	typeof(T) v = 0;			\
+	check_add_overflow((x), v, &v);		\
+})
+
+/**
+ * overflows_type - helper for checking the overflows between value, variables,
+ *		    or data type
+ *
+ * @n: source constant value or variable to be checked
+ * @T: destination variable or data type proposed to store @x
+ *
+ * Compares the @x expression for whether or not it can safely fit in
+ * the storage of the type in @T. @x and @T can have different types.
+ * If @x is a constant expression, this will also resolve to a constant
+ * expression.
+ *
+ * Returns: true if overflow can occur, false otherwise.
+ */
+#define overflows_type(n, T)					\
+	__builtin_choose_expr(__is_constexpr(n),		\
+			      __overflows_type_constexpr(n, T),	\
+			      __overflows_type(n, T))
+
+/**
+ * castable_to_type - like __same_type(), but also allows for casted literals
+ *
+ * @n: variable or constant value
+ * @T: variable or data type
+ *
+ * Unlike the __same_type() macro, this allows a constant value as the
+ * first argument. If this value would not overflow into an assignment
+ * of the second argument's type, it returns true. Otherwise, this falls
+ * back to __same_type().
+ */
+#define castable_to_type(n, T)						\
+	__builtin_choose_expr(__is_constexpr(n),			\
+			      !__overflows_type_constexpr(n, T),	\
+			      __same_type(n, T))
+
 /**
  * size_mul() - Calculate size_t multiplication with saturation at SIZE_MAX
  * @factor1: first factor