uaccess: Provide put/get_user_inline()

Provide convenience wrappers around scoped user access similar to
put/get_user(), which reduce the usage sites to:

if (!get_user_inline(val, ptr))
return -EFAULT;

Should only be used if there is a demonstrable performance benefit.

Signed-off-by: Thomas Gleixner <[e-mail]>
Signed-off-by: Peter Zijlstra (Intel) <[e-mail]>
Signed-off-by: Ingo Molnar <[e-mail]>
Reviewed-by: Mathieu Desnoyers <[e-mail]>
Link: https://patch.msgid.link/[e-mail]

include/linux/uaccess.h

···
 #define scoped_user_rw_access(uptr, elbl)				\
 	scoped_user_rw_access_size(uptr, sizeof(*(uptr)), elbl)
 
+/**
+ * get_user_inline - Read user data inlined
+ * @val:	The variable to store the value read from user memory
+ * @usrc:	Pointer to the user space memory to read from
+ *
+ * Return: 0 if successful, -EFAULT when faulted
+ *
+ * Inlined variant of get_user(). Only use when there is a demonstrable
+ * performance reason.
+ */
+#define get_user_inline(val, usrc)				\
+({								\
+	__label__ efault;					\
+	typeof(usrc) _tmpsrc = usrc;				\
+	int _ret = 0;						\
+								\
+	scoped_user_read_access(_tmpsrc, efault)		\
+		unsafe_get_user(val, _tmpsrc, efault);		\
+	if (0) {						\
+	efault:							\
+		_ret = -EFAULT;					\
+	}							\
+	_ret;							\
+})
+
+/**
+ * put_user_inline - Write to user memory inlined
+ * @val:	The value to write
+ * @udst:	Pointer to the user space memory to write to
+ *
+ * Return: 0 if successful, -EFAULT when faulted
+ *
+ * Inlined variant of put_user(). Only use when there is a demonstrable
+ * performance reason.
+ */
+#define put_user_inline(val, udst)				\
+({								\
+	__label__ efault;					\
+	typeof(udst) _tmpdst = udst;				\
+	int _ret = 0;						\
+								\
+	scoped_user_write_access(_tmpdst, efault)		\
+		unsafe_put_user(val, _tmpdst, efault);		\
+	if (0) {						\
+	efault:							\
+		_ret = -EFAULT;					\
+	}							\
+	_ret;							\
+})
+
 #ifdef CONFIG_HARDENED_USERCOPY
 void __noreturn usercopy_abort(const char *name, const char *detail,
 			       bool to_user, unsigned long offset,