s390/smp: remove redundant pcpu::lowcore member

Per-CPU pointer to lowcore is stored in global lowcore_ptr[]
array and duplicated in struct pcpu::lowcore member. This
update removes the redundancy.
Signed-off-by: NAlexander Gordeev <agordeev@linux.ibm.com>
Reviewed-by: NHeiko Carstens <hca@linux.ibm.com>
Signed-off-by: NVasily Gorbik <gor@linux.ibm.com>

arch/s390/kernel/smp.c

@@ -74,7 +74,6 @@ enum {
 static DEFINE_PER_CPU(struct cpu *, cpu_device);
 
 struct pcpu {
-	struct lowcore *lowcore;	/* lowcore page(s) for the cpu */
 	unsigned long ec_mask;		/* bit mask for ec_xxx functions */
 	unsigned long ec_clk;		/* sigp timestamp for ec_xxx */
 	signed char state;		/* physical cpu state */
@@ -214,7 +213,6 @@ static int pcpu_alloc_lowcore(struct pcpu *pcpu, int cpu)
 	if (nmi_alloc_per_cpu(lc))
 		goto out;
 	lowcore_ptr[cpu] = lc;
-	pcpu->lowcore = lc;
 	pcpu_sigp_retry(pcpu, SIGP_SET_PREFIX, (u32)(unsigned long) lc);
 	return 0;
 
@@ -230,14 +228,15 @@ static void pcpu_free_lowcore(struct pcpu *pcpu)
 {
 	unsigned long async_stack, nodat_stack, mcck_stack;
 	struct lowcore *lc;
+	int cpu;
 
-	lc = pcpu->lowcore;
+	cpu = pcpu - pcpu_devices;
+	lc = lowcore_ptr[cpu];
 	nodat_stack = lc->nodat_stack - STACK_INIT_OFFSET;
 	async_stack = lc->async_stack - STACK_INIT_OFFSET;
 	mcck_stack = lc->mcck_stack - STACK_INIT_OFFSET;
 	pcpu_sigp_retry(pcpu, SIGP_SET_PREFIX, 0);
-	lowcore_ptr[pcpu - pcpu_devices] = NULL;
-	pcpu->lowcore = NULL;
+	lowcore_ptr[cpu] = NULL;
 	nmi_free_per_cpu(lc);
 	stack_free(async_stack);
 	stack_free(mcck_stack);
@@ -247,7 +246,7 @@ static void pcpu_free_lowcore(struct pcpu *pcpu)
 
 static void pcpu_prepare_secondary(struct pcpu *pcpu, int cpu)
 {
-	struct lowcore *lc = pcpu->lowcore;
+	struct lowcore *lc = lowcore_ptr[cpu];
 
 	cpumask_set_cpu(cpu, &init_mm.context.cpu_attach_mask);
 	cpumask_set_cpu(cpu, mm_cpumask(&init_mm));
@@ -269,8 +268,11 @@ static void pcpu_prepare_secondary(struct pcpu *pcpu, int cpu)
 
 static void pcpu_attach_task(struct pcpu *pcpu, struct task_struct *tsk)
 {
-	struct lowcore *lc = pcpu->lowcore;
+	struct lowcore *lc;
+	int cpu;
 
+	cpu = pcpu - pcpu_devices;
+	lc = lowcore_ptr[cpu];
 	lc->kernel_stack = (unsigned long) task_stack_page(tsk)
 		+ THREAD_SIZE - STACK_FRAME_OVERHEAD - sizeof(struct pt_regs);
 	lc->current_task = (unsigned long) tsk;
@@ -286,8 +288,11 @@ static void pcpu_attach_task(struct pcpu *pcpu, struct task_struct *tsk)
 
 static void pcpu_start_fn(struct pcpu *pcpu, void (*func)(void *), void *data)
 {
-	struct lowcore *lc = pcpu->lowcore;
+	struct lowcore *lc;
+	int cpu;
 
+	cpu = pcpu - pcpu_devices;
+	lc = lowcore_ptr[cpu];
 	lc->restart_stack = lc->nodat_stack;
 	lc->restart_fn = (unsigned long) func;
 	lc->restart_data = (unsigned long) data;
@@ -372,7 +377,7 @@ void smp_call_online_cpu(void (*func)(void *), void *data)
  */
 void smp_call_ipl_cpu(void (*func)(void *), void *data)
 {
-	struct lowcore *lc = pcpu_devices->lowcore;
+	struct lowcore *lc = lowcore_ptr[0];
 
 	if (pcpu_devices[0].address == stap())
 		lc = &S390_lowcore;
@@ -585,18 +590,21 @@ EXPORT_SYMBOL(smp_ctl_clear_bit);
 
 int smp_store_status(int cpu)
 {
-	struct pcpu *pcpu = pcpu_devices + cpu;
+	struct lowcore *lc;
+	struct pcpu *pcpu;
 	unsigned long pa;
 
-	pa = __pa(&pcpu->lowcore->floating_pt_save_area);
+	pcpu = pcpu_devices + cpu;
+	lc = lowcore_ptr[cpu];
+	pa = __pa(&lc->floating_pt_save_area);
 	if (__pcpu_sigp_relax(pcpu->address, SIGP_STORE_STATUS_AT_ADDRESS,
 			      pa) != SIGP_CC_ORDER_CODE_ACCEPTED)
 		return -EIO;
 	if (!MACHINE_HAS_VX && !MACHINE_HAS_GS)
 		return 0;
-	pa = __pa(pcpu->lowcore->mcesad & MCESA_ORIGIN_MASK);
+	pa = __pa(lc->mcesad & MCESA_ORIGIN_MASK);
 	if (MACHINE_HAS_GS)
-		pa |= pcpu->lowcore->mcesad & MCESA_LC_MASK;
+		pa |= lc->mcesad & MCESA_LC_MASK;
 	if (__pcpu_sigp_relax(pcpu->address, SIGP_STORE_ADDITIONAL_STATUS,
 			      pa) != SIGP_CC_ORDER_CODE_ACCEPTED)
 		return -EIO;
@@ -997,7 +1005,6 @@ void __init smp_prepare_boot_cpu(void)
 
 	WARN_ON(!cpu_present(0) || !cpu_online(0));
 	pcpu->state = CPU_STATE_CONFIGURED;
-	pcpu->lowcore = (struct lowcore *)(unsigned long) store_prefix();
 	S390_lowcore.percpu_offset = __per_cpu_offset[0];
 	smp_cpu_set_polarization(0, POLARIZATION_UNKNOWN);
 }
@@ -1264,7 +1271,6 @@ static int __init smp_reinit_ipl_cpu(void)
 	S390_lowcore.async_stack = async_stack + STACK_INIT_OFFSET;
 	S390_lowcore.mcck_stack = mcck_stack + STACK_INIT_OFFSET;
 	lowcore_ptr[0] = lc;
-	pcpu_devices[0].lowcore = lc;
 	local_mcck_enable();
 	local_irq_restore(flags);