x86: user_regset user-copy helpers

This defines two new inlines in linux/regset.h, for use in arch_ptrace
implementations and the like.  These provide simplified wrappers for using
the user_regset interfaces to copy thread regset data into the caller's
user-space memory.  The inlines are trivial, but make the common uses in
places such as ptrace implementation much more concise, easier to read, and
less prone to code-copying errors.
Signed-off-by: NRoland McGrath <roland@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

include/linux/regset.h

@@ -318,5 +318,51 @@ static inline int user_regset_copyin_ignore(unsigned int *pos,
 	return 0;
 }
 
+/**
+ * copy_regset_to_user - fetch a thread's user_regset data into user memory
+ * @target:	thread to be examined
+ * @view:	&struct user_regset_view describing user thread machine state
+ * @setno:	index in @view->regsets
+ * @offset:	offset into the regset data, in bytes
+ * @size:	amount of data to copy, in bytes
+ * @data:	user-mode pointer to copy into
+ */
+static inline int copy_regset_to_user(struct task_struct *target,
+				      const struct user_regset_view *view,
+				      unsigned int setno,
+				      unsigned int offset, unsigned int size,
+				      void __user *data)
+{
+	const struct user_regset *regset = &view->regsets[setno];
+
+	if (!access_ok(VERIFY_WRITE, data, size))
+		return -EIO;
+
+	return regset->get(target, regset, offset, size, NULL, data);
+}
+
+/**
+ * copy_regset_from_user - store into thread's user_regset data from user memory
+ * @target:	thread to be examined
+ * @view:	&struct user_regset_view describing user thread machine state
+ * @setno:	index in @view->regsets
+ * @offset:	offset into the regset data, in bytes
+ * @size:	amount of data to copy, in bytes
+ * @data:	user-mode pointer to copy from
+ */
+static inline int copy_regset_from_user(struct task_struct *target,
+					const struct user_regset_view *view,
+					unsigned int setno,
+					unsigned int offset, unsigned int size,
+					const void __user *data)
+{
+	const struct user_regset *regset = &view->regsets[setno];
+
+	if (!access_ok(VERIFY_READ, data, size))
+		return -EIO;
+
+	return regset->set(target, regset, offset, size, NULL, data);
+}
+
 
 #endif	/* <linux/regset.h> */