s390/ctlreg: return old register contents when changing bits

Change local_ctl_set_bit() and local_ctl_clear_bit() so they return the
previous value of the to be changed control register. This is useful if a
bit is only changed temporarily and the previous content needs to be
restored.
Reviewed-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>

arch/s390/include/asm/ctlreg.h

@@ -141,22 +141,26 @@ static __always_inline void local_ctl_store(unsigned int cr, struct ctlreg *reg)
 		: [cr] "i" (cr));
 }
 
-static __always_inline void local_ctl_set_bit(unsigned int cr, unsigned int bit)
+static __always_inline struct ctlreg local_ctl_set_bit(unsigned int cr, unsigned int bit)
 {
-	struct ctlreg reg;
+	struct ctlreg new, old;
 
-	local_ctl_store(cr, &reg);
-	reg.val |= 1UL << bit;
-	local_ctl_load(cr, &reg);
+	local_ctl_store(cr, &old);
+	new = old;
+	new.val |= 1UL << bit;
+	local_ctl_load(cr, &new);
+	return old;
 }
 
-static __always_inline void local_ctl_clear_bit(unsigned int cr, unsigned int bit)
+static __always_inline struct ctlreg local_ctl_clear_bit(unsigned int cr, unsigned int bit)
 {
-	struct ctlreg reg;
+	struct ctlreg new, old;
 
-	local_ctl_store(cr, &reg);
-	reg.val &= ~(1UL << bit);
-	local_ctl_load(cr, &reg);
+	local_ctl_store(cr, &old);
+	new = old;
+	new.val &= ~(1UL << bit);
+	local_ctl_load(cr, &new);
+	return old;
 }
 
 struct lowcore;