s390/early: move control registers setup in C code

Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

arch/s390/include/asm/ctl_reg.h

@@ -11,6 +11,7 @@
 #include <linux/bits.h>
 
 #define CR0_CLOCK_COMPARATOR_SIGN	BIT(63 - 10)
+#define CR0_LOW_ADDRESS_PROTECTION	BIT(63 - 35)
 #define CR0_EMERGENCY_SIGNAL_SUBMASK	BIT(63 - 49)
 #define CR0_EXTERNAL_CALL_SUBMASK	BIT(63 - 50)
 #define CR0_CLOCK_COMPARATOR_SUBMASK	BIT(63 - 52)

arch/s390/kernel/early.c

@@ -260,6 +260,17 @@ static inline void save_vector_registers(void)
 #endif
 }
 
+static inline void setup_control_registers(void)
+{
+	unsigned long reg;
+
+	__ctl_store(reg, 0, 0);
+	reg |= CR0_LOW_ADDRESS_PROTECTION;
+	reg |= CR0_EMERGENCY_SIGNAL_SUBMASK;
+	reg |= CR0_EXTERNAL_CALL_SUBMASK;
+	__ctl_load(reg, 0, 0);
+}
+
 static int __init disable_vector_extension(char *str)
 {
 	S390_lowcore.machine_flags &= ~MACHINE_FLAG_VX;
@@ -317,5 +328,6 @@ void __init startup_init(void)
 	save_vector_registers();
 	setup_topology();
 	sclp_early_detect();
+	setup_control_registers();
 	lockdep_on();
 }

arch/s390/kernel/head64.S

@@ -42,12 +42,6 @@ ENTRY(startup_continue)
 #
 	brasl	%r14,startup_init
 
-# check control registers
-	stctg	%c0,%c15,0(%r15)
-	oi	6(%r15),0x60		# enable sigp emergency & external call
-	oi	4(%r15),0x10		# switch on low address proctection
-	lctlg	%c0,%c15,0(%r15)
-
 	lam	0,15,.Laregs-.LPG1(%r13)	# load acrs needed by uaccess
 	brasl	%r14,start_kernel		# go to C code
 #