s390/smp: reduce size of struct pcpu

Reduce the size of struct pcpu, since the pcpu_devices array consists
of NR_CPUS elements of type struct pcpu. For most machines this is just
a waste of memory.
So let's try to make it a bit smaller.
This saves 16k with performance_defconfig.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

diff --git a/arch/s390/kernel/smp.c b/arch/s390/kernel/smp.c
index a668993..db8f111 100644 (file)
--- a/arch/s390/kernel/smp.c
+++ b/arch/s390/kernel/smp.c
@@ -59,14 +59,13 @@ enum {
        CPU_STATE_CONFIGURED,
 };
 
+static DEFINE_PER_CPU(struct cpu *, cpu_device);
+
 struct pcpu {
-       struct cpu *cpu;
        struct _lowcore *lowcore;       /* lowcore page(s) for the cpu */
-       unsigned long async_stack;      /* async stack for the cpu */
-       unsigned long panic_stack;      /* panic stack for the cpu */
        unsigned long ec_mask;          /* bit mask for ec_xxx functions */
-       int state;                      /* physical cpu state */
-       int polarization;               /* physical polarization */
+       signed char state;              /* physical cpu state */
+       signed char polarization;       /* physical polarization */
        u16 address;                    /* physical cpu address */
 };
 
@@ -173,25 +172,30 @@ static void pcpu_ec_call(struct pcpu *pcpu, int ec_bit)
        pcpu_sigp_retry(pcpu, order, 0);
 }
 
+#define ASYNC_FRAME_OFFSET (ASYNC_SIZE - STACK_FRAME_OVERHEAD - __PT_SIZE)
+#define PANIC_FRAME_OFFSET (PAGE_SIZE - STACK_FRAME_OVERHEAD - __PT_SIZE)
+
 static int pcpu_alloc_lowcore(struct pcpu *pcpu, int cpu)
 {
+       unsigned long async_stack, panic_stack;
        struct _lowcore *lc;
 
        if (pcpu != &pcpu_devices[0]) {
                pcpu->lowcore = (struct _lowcore *)
                        __get_free_pages(GFP_KERNEL | GFP_DMA, LC_ORDER);
-               pcpu->async_stack = __get_free_pages(GFP_KERNEL, ASYNC_ORDER);
-               pcpu->panic_stack = __get_free_page(GFP_KERNEL);
-               if (!pcpu->lowcore || !pcpu->panic_stack || !pcpu->async_stack)
+               async_stack = __get_free_pages(GFP_KERNEL, ASYNC_ORDER);
+               panic_stack = __get_free_page(GFP_KERNEL);
+               if (!pcpu->lowcore || !panic_stack || !async_stack)
                        goto out;
+       } else {
+               async_stack = pcpu->lowcore->async_stack - ASYNC_FRAME_OFFSET;
+               panic_stack = pcpu->lowcore->panic_stack - PANIC_FRAME_OFFSET;
        }
        lc = pcpu->lowcore;
        memcpy(lc, &S390_lowcore, 512);
        memset((char *) lc + 512, 0, sizeof(*lc) - 512);
-       lc->async_stack = pcpu->async_stack + ASYNC_SIZE
-               - STACK_FRAME_OVERHEAD - sizeof(struct pt_regs);
-       lc->panic_stack = pcpu->panic_stack + PAGE_SIZE
-               - STACK_FRAME_OVERHEAD - sizeof(struct pt_regs);
+       lc->async_stack = async_stack + ASYNC_FRAME_OFFSET;
+       lc->panic_stack = panic_stack + PANIC_FRAME_OFFSET;
        lc->cpu_nr = cpu;
        lc->spinlock_lockval = arch_spin_lockval(cpu);
 #ifndef CONFIG_64BIT
@@ -212,8 +216,8 @@ static int pcpu_alloc_lowcore(struct pcpu *pcpu, int cpu)
        return 0;
 out:
        if (pcpu != &pcpu_devices[0]) {
-               free_page(pcpu->panic_stack);
-               free_pages(pcpu->async_stack, ASYNC_ORDER);
+               free_page(panic_stack);
+               free_pages(async_stack, ASYNC_ORDER);
                free_pages((unsigned long) pcpu->lowcore, LC_ORDER);
        }
        return -ENOMEM;
@@ -235,11 +239,11 @@ static void pcpu_free_lowcore(struct pcpu *pcpu)
 #else
        vdso_free_per_cpu(pcpu->lowcore);
 #endif
-       if (pcpu != &pcpu_devices[0]) {
-               free_page(pcpu->panic_stack);
-               free_pages(pcpu->async_stack, ASYNC_ORDER);
-               free_pages((unsigned long) pcpu->lowcore, LC_ORDER);
-       }
+       if (pcpu == &pcpu_devices[0])
+               return;
+       free_page(pcpu->lowcore->panic_stack-PANIC_FRAME_OFFSET);
+       free_pages(pcpu->lowcore->async_stack-ASYNC_FRAME_OFFSET, ASYNC_ORDER);
+       free_pages((unsigned long) pcpu->lowcore, LC_ORDER);
 }
 
 #endif /* CONFIG_HOTPLUG_CPU */
@@ -366,7 +370,8 @@ void smp_call_online_cpu(void (*func)(void *), void *data)
 void smp_call_ipl_cpu(void (*func)(void *), void *data)
 {
        pcpu_delegate(&pcpu_devices[0], func, data,
-                     pcpu_devices->panic_stack + PAGE_SIZE);
+                     pcpu_devices->lowcore->panic_stack -
+                     PANIC_FRAME_OFFSET + PAGE_SIZE);
 }
 
 int smp_find_processor_id(u16 address)
@@ -935,10 +940,6 @@ void __init smp_prepare_boot_cpu(void)
        pcpu->state = CPU_STATE_CONFIGURED;
        pcpu->address = stap();
        pcpu->lowcore = (struct _lowcore *)(unsigned long) store_prefix();
-       pcpu->async_stack = S390_lowcore.async_stack - ASYNC_SIZE
-               + STACK_FRAME_OVERHEAD + sizeof(struct pt_regs);
-       pcpu->panic_stack = S390_lowcore.panic_stack - PAGE_SIZE
-               + STACK_FRAME_OVERHEAD + sizeof(struct pt_regs);
        S390_lowcore.percpu_offset = __per_cpu_offset[0];
        smp_cpu_set_polarization(0, POLARIZATION_UNKNOWN);
        set_cpu_present(0, true);
@@ -1078,8 +1079,7 @@ static int smp_cpu_notify(struct notifier_block *self, unsigned long action,
                          void *hcpu)
 {
        unsigned int cpu = (unsigned int)(long)hcpu;
-       struct cpu *c = pcpu_devices[cpu].cpu;
-       struct device *s = &c->dev;
+       struct device *s = &per_cpu(cpu_device, cpu)->dev;
        int err = 0;
 
        switch (action & ~CPU_TASKS_FROZEN) {
@@ -1102,7 +1102,7 @@ static int smp_add_present_cpu(int cpu)
        c = kzalloc(sizeof(*c), GFP_KERNEL);
        if (!c)
                return -ENOMEM;
-       pcpu_devices[cpu].cpu = c;
+       per_cpu(cpu_device, cpu) = c;
        s = &c->dev;
        c->hotpluggable = 1;
        rc = register_cpu(c, cpu);