s390/ctl_reg: use decoding unions in update_cr_regs

Add a decoding union for the bits in control registers 2 and use
'union ctlreg0' and 'union ctlreg2' in update_cr_regs to improve
readability.

Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Reviewed-by: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

3 files changed, 24 insertions, 21 deletions

diff --git a/arch/s390/kernel/machine_kexec.c b/arch/s390/kernel/machine_kexec.c
index 51e8c63705a9..e94421678b13 100644
--- a/arch/s390/kernel/machine_kexec.c
+++ b/arch/s390/kernel/machine_kexec.c
@@ -105,7 +105,7 @@ static void __do_machine_kdump(void *image)
 static noinline void __machine_kdump(void *image)
 {
 	struct mcesa *mcesa;
-	unsigned long cr2_old, cr2_new;
+	union ctlreg2 cr2_old, cr2_new;
 	int this_cpu, cpu;
 
 	lgr_info_log();
@@ -122,11 +122,12 @@ static noinline void __machine_kdump(void *image)
 	if (MACHINE_HAS_VX)
 		save_vx_regs((__vector128 *) mcesa->vector_save_area);
 	if (MACHINE_HAS_GS) {
-		__ctl_store(cr2_old, 2, 2);
-		cr2_new = cr2_old | (1UL << 4);
-		__ctl_load(cr2_new, 2, 2);
+		__ctl_store(cr2_old.val, 2, 2);
+		cr2_new = cr2_old;
+		cr2_new.gse = 1;
+		__ctl_load(cr2_new.val, 2, 2);
 		save_gs_cb((struct gs_cb *) mcesa->guarded_storage_save_area);
-		__ctl_load(cr2_old, 2, 2);
+		__ctl_load(cr2_old.val, 2, 2);
 	}
 	/*
 	 * To create a good backchain for this CPU in the dump store_status
diff --git a/arch/s390/kernel/nmi.c b/arch/s390/kernel/nmi.c
index 15e28eefe7e9..eb3e702cee30 100644
--- a/arch/s390/kernel/nmi.c
+++ b/arch/s390/kernel/nmi.c
@@ -107,6 +107,7 @@ EXPORT_SYMBOL_GPL(s390_handle_mcck);
  */
 static int notrace s390_validate_registers(union mci mci, int umode)
 {
+	union ctlreg2 cr2;
 	int kill_task;
 	u64 zero;
 	void *fpt_save_area;
@@ -231,7 +232,8 @@ static int notrace s390_validate_registers(union mci mci, int umode)
 		kill_task = 1;
 	}
 	/* Validate guarded storage registers */
-	if (MACHINE_HAS_GS && (S390_lowcore.cregs_save_area[2] & (1UL << 4))) {
+	cr2.val = S390_lowcore.cregs_save_area[2];
+	if (cr2.gse) {
 		if (!mci.gs)
 			/*
 			 * Guarded storage register can't be restored and
diff --git a/arch/s390/kernel/ptrace.c b/arch/s390/kernel/ptrace.c
index ea711f141bb8..ea637365d9ef 100644
--- a/arch/s390/kernel/ptrace.c
+++ b/arch/s390/kernel/ptrace.c
@@ -47,42 +47,42 @@ void update_cr_regs(struct task_struct *task)
 	struct pt_regs *regs = task_pt_regs(task);
 	struct thread_struct *thread = &task->thread;
 	struct per_regs old, new;
-	unsigned long cr0_old, cr0_new;
-	unsigned long cr2_old, cr2_new;
+	union ctlreg0 cr0_old, cr0_new;
+	union ctlreg2 cr2_old, cr2_new;
 	int cr0_changed, cr2_changed;
 
-	__ctl_store(cr0_old, 0, 0);
-	__ctl_store(cr2_old, 2, 2);
+	__ctl_store(cr0_old.val, 0, 0);
+	__ctl_store(cr2_old.val, 2, 2);
 	cr0_new = cr0_old;
 	cr2_new = cr2_old;
 	/* Take care of the enable/disable of transactional execution. */
 	if (MACHINE_HAS_TE) {
 		/* Set or clear transaction execution TXC bit 8. */
-		cr0_new |= (1UL << 55);
+		cr0_new.tcx = 1;
 		if (task->thread.per_flags & PER_FLAG_NO_TE)
-			cr0_new &= ~(1UL << 55);
+			cr0_new.tcx = 0;
 		/* Set or clear transaction execution TDC bits 62 and 63. */
-		cr2_new &= ~3UL;
+		cr2_new.tdc = 0;
 		if (task->thread.per_flags & PER_FLAG_TE_ABORT_RAND) {
 			if (task->thread.per_flags & PER_FLAG_TE_ABORT_RAND_TEND)
-				cr2_new |= 1UL;
+				cr2_new.tdc = 1;
 			else
-				cr2_new |= 2UL;
+				cr2_new.tdc = 2;
 		}
 	}
 	/* Take care of enable/disable of guarded storage. */
 	if (MACHINE_HAS_GS) {
-		cr2_new &= ~(1UL << 4);
+		cr2_new.gse = 0;
 		if (task->thread.gs_cb)
-			cr2_new |= (1UL << 4);
+			cr2_new.gse = 1;
 	}
 	/* Load control register 0/2 iff changed */
-	cr0_changed = cr0_new != cr0_old;
-	cr2_changed = cr2_new != cr2_old;
+	cr0_changed = cr0_new.val != cr0_old.val;
+	cr2_changed = cr2_new.val != cr2_old.val;
 	if (cr0_changed)
-		__ctl_load(cr0_new, 0, 0);
+		__ctl_load(cr0_new.val, 0, 0);
 	if (cr2_changed)
-		__ctl_load(cr2_new, 2, 2);
+		__ctl_load(cr2_new.val, 2, 2);
 	/* Copy user specified PER registers */
 	new.control = thread->per_user.control;
 	new.start = thread->per_user.start;