[S390] kdump backend code

[deliverable/linux.git] / arch / s390 / kernel / smp.c

/*
 *  arch/s390/kernel/smp.c
 *
 *    Copyright IBM Corp. 1999, 2009
 *    Author(s): Denis Joseph Barrow (djbarrow@de.ibm.com,barrow_dj@yahoo.com),
 *               Martin Schwidefsky (schwidefsky@de.ibm.com)
 *               Heiko Carstens (heiko.carstens@de.ibm.com)
 *
 *  based on other smp stuff by
 *    (c) 1995 Alan Cox, CymruNET Ltd  <alan@cymru.net>
 *    (c) 1998 Ingo Molnar
 *
 * We work with logical cpu numbering everywhere we can. The only
 * functions using the real cpu address (got from STAP) are the sigp
 * functions. For all other functions we use the identity mapping.
 * That means that cpu_number_map[i] == i for every cpu. cpu_number_map is
 * used e.g. to find the idle task belonging to a logical cpu. Every array
 * in the kernel is sorted by the logical cpu number and not by the physical
 * one which is causing all the confusion with __cpu_logical_map and
 * cpu_number_map in other architectures.
 */

#define KMSG_COMPONENT "cpu"
#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt

#include <linux/workqueue.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/mm.h>
#include <linux/err.h>
#include <linux/spinlock.h>
#include <linux/kernel_stat.h>
#include <linux/delay.h>
#include <linux/cache.h>
#include <linux/interrupt.h>
#include <linux/irqflags.h>
#include <linux/cpu.h>
#include <linux/timex.h>
#include <linux/bootmem.h>
#include <linux/slab.h>
#include <linux/crash_dump.h>
#include <asm/asm-offsets.h>
#include <asm/ipl.h>
#include <asm/setup.h>
#include <asm/sigp.h>
#include <asm/pgalloc.h>
#include <asm/irq.h>
#include <asm/cpcmd.h>
#include <asm/tlbflush.h>
#include <asm/timer.h>
#include <asm/lowcore.h>
#include <asm/sclp.h>
#include <asm/cputime.h>
#include <asm/vdso.h>
#include <asm/cpu.h>
#include "entry.h"

/* logical cpu to cpu address */
unsigned short __cpu_logical_map[NR_CPUS];

static struct task_struct *current_set[NR_CPUS];

static u8 smp_cpu_type;
static int smp_use_sigp_detection;

enum s390_cpu_state {
        CPU_STATE_STANDBY,
        CPU_STATE_CONFIGURED,
};

DEFINE_MUTEX(smp_cpu_state_mutex);
int smp_cpu_polarization[NR_CPUS];
static int smp_cpu_state[NR_CPUS];
static int cpu_management;

static DEFINE_PER_CPU(struct cpu, cpu_devices);

static void smp_ext_bitcall(int, int);

static int raw_cpu_stopped(int cpu)
{
        u32 status;

        switch (raw_sigp_ps(&status, 0, cpu, sigp_sense)) {
        case sigp_status_stored:
                /* Check for stopped and check stop state */
                if (status & 0x50)
                        return 1;
                break;
        default:
                break;
        }
        return 0;
}

static inline int cpu_stopped(int cpu)
{
        return raw_cpu_stopped(cpu_logical_map(cpu));
}

/*
 * Ensure that PSW restart is done on an online CPU
 */
void smp_restart_with_online_cpu(void)
{
        int cpu;

        for_each_online_cpu(cpu) {
                if (stap() == __cpu_logical_map[cpu]) {
                        /* We are online: Enable DAT again and return */
                        __load_psw_mask(psw_kernel_bits & ~PSW_MASK_MCHECK);
                        return;
                }
        }
        /* We are not online: Do PSW restart on an online CPU */
        while (sigp(cpu, sigp_restart) == sigp_busy)
                cpu_relax();
        /* And stop ourself */
        while (raw_sigp(stap(), sigp_stop) == sigp_busy)
                cpu_relax();
        for (;;);
}

void smp_switch_to_ipl_cpu(void (*func)(void *), void *data)
{
        struct _lowcore *lc, *current_lc;
        struct stack_frame *sf;
        struct pt_regs *regs;
        unsigned long sp;

        if (smp_processor_id() == 0)
                func(data);
        __load_psw_mask(PSW_BASE_BITS | PSW_DEFAULT_KEY);
        /* Disable lowcore protection */
        __ctl_clear_bit(0, 28);
        current_lc = lowcore_ptr[smp_processor_id()];
        lc = lowcore_ptr[0];
        if (!lc)
                lc = current_lc;
        lc->restart_psw.mask = PSW_BASE_BITS | PSW_DEFAULT_KEY;
        lc->restart_psw.addr = PSW_ADDR_AMODE | (unsigned long) smp_restart_cpu;
        if (!cpu_online(0))
                smp_switch_to_cpu(func, data, 0, stap(), __cpu_logical_map[0]);
        while (sigp(0, sigp_stop_and_store_status) == sigp_busy)
                cpu_relax();
        sp = lc->panic_stack;
        sp -= sizeof(struct pt_regs);
        regs = (struct pt_regs *) sp;
        memcpy(&regs->gprs, &current_lc->gpregs_save_area, sizeof(regs->gprs));
        regs->psw = lc->psw_save_area;
        sp -= STACK_FRAME_OVERHEAD;
        sf = (struct stack_frame *) sp;
        sf->back_chain = regs->gprs[15];
        smp_switch_to_cpu(func, data, sp, stap(), __cpu_logical_map[0]);
}

void smp_send_stop(void)
{
        int cpu, rc;

        /* Disable all interrupts/machine checks */
        __load_psw_mask(psw_kernel_bits & ~PSW_MASK_MCHECK);
        trace_hardirqs_off();

        /* stop all processors */
        for_each_online_cpu(cpu) {
                if (cpu == smp_processor_id())
                        continue;
                do {
                        rc = sigp(cpu, sigp_stop);
                } while (rc == sigp_busy);

                while (!cpu_stopped(cpu))
                        cpu_relax();
        }
}

/*
 * This is the main routine where commands issued by other
 * cpus are handled.
 */

static void do_ext_call_interrupt(unsigned int ext_int_code,
                                  unsigned int param32, unsigned long param64)
{
        unsigned long bits;

        kstat_cpu(smp_processor_id()).irqs[EXTINT_IPI]++;
        /*
         * handle bit signal external calls
         */
        bits = xchg(&S390_lowcore.ext_call_fast, 0);

        if (test_bit(ec_schedule, &bits))
                scheduler_ipi();

        if (test_bit(ec_call_function, &bits))
                generic_smp_call_function_interrupt();

        if (test_bit(ec_call_function_single, &bits))
                generic_smp_call_function_single_interrupt();
}

/*
 * Send an external call sigp to another cpu and return without waiting
 * for its completion.
 */
static void smp_ext_bitcall(int cpu, int sig)
{
        /*
         * Set signaling bit in lowcore of target cpu and kick it
         */
        set_bit(sig, (unsigned long *) &lowcore_ptr[cpu]->ext_call_fast);
        while (sigp(cpu, sigp_emergency_signal) == sigp_busy)
                udelay(10);
}

void arch_send_call_function_ipi_mask(const struct cpumask *mask)
{
        int cpu;

        for_each_cpu(cpu, mask)
                smp_ext_bitcall(cpu, ec_call_function);
}

void arch_send_call_function_single_ipi(int cpu)
{
        smp_ext_bitcall(cpu, ec_call_function_single);
}

#ifndef CONFIG_64BIT
/*
 * this function sends a 'purge tlb' signal to another CPU.
 */
static void smp_ptlb_callback(void *info)
{
        __tlb_flush_local();
}

void smp_ptlb_all(void)
{
        on_each_cpu(smp_ptlb_callback, NULL, 1);
}
EXPORT_SYMBOL(smp_ptlb_all);
#endif /* ! CONFIG_64BIT */

/*
 * this function sends a 'reschedule' IPI to another CPU.
 * it goes straight through and wastes no time serializing
 * anything. Worst case is that we lose a reschedule ...
 */
void smp_send_reschedule(int cpu)
{
        smp_ext_bitcall(cpu, ec_schedule);
}

/*
 * parameter area for the set/clear control bit callbacks
 */
struct ec_creg_mask_parms {
        unsigned long orvals[16];
        unsigned long andvals[16];
};

/*
 * callback for setting/clearing control bits
 */
static void smp_ctl_bit_callback(void *info)
{
        struct ec_creg_mask_parms *pp = info;
        unsigned long cregs[16];
        int i;

        __ctl_store(cregs, 0, 15);
        for (i = 0; i <= 15; i++)
                cregs[i] = (cregs[i] & pp->andvals[i]) | pp->orvals[i];
        __ctl_load(cregs, 0, 15);
}

/*
 * Set a bit in a control register of all cpus
 */
void smp_ctl_set_bit(int cr, int bit)
{
        struct ec_creg_mask_parms parms;

        memset(&parms.orvals, 0, sizeof(parms.orvals));
        memset(&parms.andvals, 0xff, sizeof(parms.andvals));
        parms.orvals[cr] = 1UL << bit;
        on_each_cpu(smp_ctl_bit_callback, &parms, 1);
}
EXPORT_SYMBOL(smp_ctl_set_bit);

/*
 * Clear a bit in a control register of all cpus
 */
void smp_ctl_clear_bit(int cr, int bit)
{
        struct ec_creg_mask_parms parms;

        memset(&parms.orvals, 0, sizeof(parms.orvals));
        memset(&parms.andvals, 0xff, sizeof(parms.andvals));
        parms.andvals[cr] = ~(1UL << bit);
        on_each_cpu(smp_ctl_bit_callback, &parms, 1);
}
EXPORT_SYMBOL(smp_ctl_clear_bit);

#if defined(CONFIG_ZFCPDUMP) || defined(CONFIG_CRASH_DUMP)

static void __init smp_get_save_area(unsigned int cpu, unsigned int phy_cpu)
{
        if (ipl_info.type != IPL_TYPE_FCP_DUMP && !OLDMEM_BASE)
                return;
        if (is_kdump_kernel())
                return;
        if (cpu >= NR_CPUS) {
                pr_warning("CPU %i exceeds the maximum %i and is excluded from "
                           "the dump\n", cpu, NR_CPUS - 1);
                return;
        }
        zfcpdump_save_areas[cpu] = kmalloc(sizeof(struct save_area), GFP_KERNEL);
        while (raw_sigp(phy_cpu, sigp_stop_and_store_status) == sigp_busy)
                cpu_relax();
        memcpy_real(zfcpdump_save_areas[cpu],
                    (void *)(unsigned long) store_prefix() + SAVE_AREA_BASE,
                    sizeof(struct save_area));
}

struct save_area *zfcpdump_save_areas[NR_CPUS + 1];
EXPORT_SYMBOL_GPL(zfcpdump_save_areas);

#else

static inline void smp_get_save_area(unsigned int cpu, unsigned int phy_cpu) { }

#endif /* CONFIG_ZFCPDUMP */

static int cpu_known(int cpu_id)
{
        int cpu;

        for_each_present_cpu(cpu) {
                if (__cpu_logical_map[cpu] == cpu_id)
                        return 1;
        }
        return 0;
}

static int smp_rescan_cpus_sigp(cpumask_t avail)
{
        int cpu_id, logical_cpu;

        logical_cpu = cpumask_first(&avail);
        if (logical_cpu >= nr_cpu_ids)
                return 0;
        for (cpu_id = 0; cpu_id <= MAX_CPU_ADDRESS; cpu_id++) {
                if (cpu_known(cpu_id))
                        continue;
                __cpu_logical_map[logical_cpu] = cpu_id;
                smp_cpu_polarization[logical_cpu] = POLARIZATION_UNKNWN;
                if (!cpu_stopped(logical_cpu))
                        continue;
                set_cpu_present(logical_cpu, true);
                smp_cpu_state[logical_cpu] = CPU_STATE_CONFIGURED;
                logical_cpu = cpumask_next(logical_cpu, &avail);
                if (logical_cpu >= nr_cpu_ids)
                        break;
        }
        return 0;
}

static int smp_rescan_cpus_sclp(cpumask_t avail)
{
        struct sclp_cpu_info *info;
        int cpu_id, logical_cpu, cpu;
        int rc;

        logical_cpu = cpumask_first(&avail);
        if (logical_cpu >= nr_cpu_ids)
                return 0;
        info = kmalloc(sizeof(*info), GFP_KERNEL);
        if (!info)
                return -ENOMEM;
        rc = sclp_get_cpu_info(info);
        if (rc)
                goto out;
        for (cpu = 0; cpu < info->combined; cpu++) {
                if (info->has_cpu_type && info->cpu[cpu].type != smp_cpu_type)
                        continue;
                cpu_id = info->cpu[cpu].address;
                if (cpu_known(cpu_id))
                        continue;
                __cpu_logical_map[logical_cpu] = cpu_id;
                smp_cpu_polarization[logical_cpu] = POLARIZATION_UNKNWN;
                set_cpu_present(logical_cpu, true);
                if (cpu >= info->configured)
                        smp_cpu_state[logical_cpu] = CPU_STATE_STANDBY;
                else
                        smp_cpu_state[logical_cpu] = CPU_STATE_CONFIGURED;
                logical_cpu = cpumask_next(logical_cpu, &avail);
                if (logical_cpu >= nr_cpu_ids)
                        break;
        }
out:
        kfree(info);
        return rc;
}

static int __smp_rescan_cpus(void)
{
        cpumask_t avail;

        cpumask_xor(&avail, cpu_possible_mask, cpu_present_mask);
        if (smp_use_sigp_detection)
                return smp_rescan_cpus_sigp(avail);
        else
                return smp_rescan_cpus_sclp(avail);
}

static void __init smp_detect_cpus(void)
{
        unsigned int cpu, c_cpus, s_cpus;
        struct sclp_cpu_info *info;
        u16 boot_cpu_addr, cpu_addr;

        c_cpus = 1;
        s_cpus = 0;
        boot_cpu_addr = __cpu_logical_map[0];
        info = kmalloc(sizeof(*info), GFP_KERNEL);
        if (!info)
                panic("smp_detect_cpus failed to allocate memory\n");
#ifdef CONFIG_CRASH_DUMP
        if (OLDMEM_BASE && !is_kdump_kernel()) {
                struct save_area *save_area;

                save_area = kmalloc(sizeof(*save_area), GFP_KERNEL);
                if (!save_area)
                        panic("could not allocate memory for save area\n");
                copy_oldmem_page(1, (void *) save_area, sizeof(*save_area),
                                 0x200, 0);
                zfcpdump_save_areas[0] = save_area;
        }
#endif
        /* Use sigp detection algorithm if sclp doesn't work. */
        if (sclp_get_cpu_info(info)) {
                smp_use_sigp_detection = 1;
                for (cpu = 0; cpu <= MAX_CPU_ADDRESS; cpu++) {
                        if (cpu == boot_cpu_addr)
                                continue;
                        if (!raw_cpu_stopped(cpu))
                                continue;
                        smp_get_save_area(c_cpus, cpu);
                        c_cpus++;
                }
                goto out;
        }

        if (info->has_cpu_type) {
                for (cpu = 0; cpu < info->combined; cpu++) {
                        if (info->cpu[cpu].address == boot_cpu_addr) {
                                smp_cpu_type = info->cpu[cpu].type;
                                break;
                        }
                }
        }

        for (cpu = 0; cpu < info->combined; cpu++) {
                if (info->has_cpu_type && info->cpu[cpu].type != smp_cpu_type)
                        continue;
                cpu_addr = info->cpu[cpu].address;
                if (cpu_addr == boot_cpu_addr)
                        continue;
                if (!raw_cpu_stopped(cpu_addr)) {
                        s_cpus++;
                        continue;
                }
                smp_get_save_area(c_cpus, cpu_addr);
                c_cpus++;
        }
out:
        kfree(info);
        pr_info("%d configured CPUs, %d standby CPUs\n", c_cpus, s_cpus);
        get_online_cpus();
        __smp_rescan_cpus();
        put_online_cpus();
}

/*
 *      Activate a secondary processor.
 */
int __cpuinit start_secondary(void *cpuvoid)
{
        cpu_init();
        preempt_disable();
        init_cpu_timer();
        init_cpu_vtimer();
        pfault_init();

        notify_cpu_starting(smp_processor_id());
        ipi_call_lock();
        set_cpu_online(smp_processor_id(), true);
        ipi_call_unlock();
        __ctl_clear_bit(0, 28); /* Disable lowcore protection */
        S390_lowcore.restart_psw.mask = PSW_BASE_BITS | PSW_DEFAULT_KEY;
        S390_lowcore.restart_psw.addr =
                PSW_ADDR_AMODE | (unsigned long) psw_restart_int_handler;
        __ctl_set_bit(0, 28); /* Enable lowcore protection */
        /*
         * Wait until the cpu which brought this one up marked it
         * active before enabling interrupts.
         */
        while (!cpumask_test_cpu(smp_processor_id(), cpu_active_mask))
                cpu_relax();
        local_irq_enable();
        /* cpu_idle will call schedule for us */
        cpu_idle();
        return 0;
}

struct create_idle {
        struct work_struct work;
        struct task_struct *idle;
        struct completion done;
        int cpu;
};

static void __cpuinit smp_fork_idle(struct work_struct *work)
{
        struct create_idle *c_idle;

        c_idle = container_of(work, struct create_idle, work);
        c_idle->idle = fork_idle(c_idle->cpu);
        complete(&c_idle->done);
}

static int __cpuinit smp_alloc_lowcore(int cpu)
{
        unsigned long async_stack, panic_stack;
        struct _lowcore *lowcore;

        lowcore = (void *) __get_free_pages(GFP_KERNEL | GFP_DMA, LC_ORDER);
        if (!lowcore)
                return -ENOMEM;
        async_stack = __get_free_pages(GFP_KERNEL, ASYNC_ORDER);
        panic_stack = __get_free_page(GFP_KERNEL);
        if (!panic_stack || !async_stack)
                goto out;
        memcpy(lowcore, &S390_lowcore, 512);
        memset((char *)lowcore + 512, 0, sizeof(*lowcore) - 512);
        lowcore->async_stack = async_stack + ASYNC_SIZE;
        lowcore->panic_stack = panic_stack + PAGE_SIZE;
        lowcore->restart_psw.mask = PSW_BASE_BITS | PSW_DEFAULT_KEY;
        lowcore->restart_psw.addr =
                PSW_ADDR_AMODE | (unsigned long) restart_int_handler;
        if (user_mode != HOME_SPACE_MODE)
                lowcore->restart_psw.mask |= PSW_ASC_HOME;
#ifndef CONFIG_64BIT
        if (MACHINE_HAS_IEEE) {
                unsigned long save_area;

                save_area = get_zeroed_page(GFP_KERNEL);
                if (!save_area)
                        goto out;
                lowcore->extended_save_area_addr = (u32) save_area;
        }
#else
        if (vdso_alloc_per_cpu(cpu, lowcore))
                goto out;
#endif
        lowcore_ptr[cpu] = lowcore;
        return 0;

out:
        free_page(panic_stack);
        free_pages(async_stack, ASYNC_ORDER);
        free_pages((unsigned long) lowcore, LC_ORDER);
        return -ENOMEM;
}

static void smp_free_lowcore(int cpu)
{
        struct _lowcore *lowcore;

        lowcore = lowcore_ptr[cpu];
#ifndef CONFIG_64BIT
        if (MACHINE_HAS_IEEE)
                free_page((unsigned long) lowcore->extended_save_area_addr);
#else
        vdso_free_per_cpu(cpu, lowcore);
#endif
        free_page(lowcore->panic_stack - PAGE_SIZE);
        free_pages(lowcore->async_stack - ASYNC_SIZE, ASYNC_ORDER);
        free_pages((unsigned long) lowcore, LC_ORDER);
        lowcore_ptr[cpu] = NULL;
}

/* Upping and downing of CPUs */
int __cpuinit __cpu_up(unsigned int cpu)
{
        struct _lowcore *cpu_lowcore;
        struct create_idle c_idle;
        struct task_struct *idle;
        struct stack_frame *sf;
        u32 lowcore;
        int ccode;

        if (smp_cpu_state[cpu] != CPU_STATE_CONFIGURED)
                return -EIO;
        idle = current_set[cpu];
        if (!idle) {
                c_idle.done = COMPLETION_INITIALIZER_ONSTACK(c_idle.done);
                INIT_WORK_ONSTACK(&c_idle.work, smp_fork_idle);
                c_idle.cpu = cpu;
                schedule_work(&c_idle.work);
                wait_for_completion(&c_idle.done);
                if (IS_ERR(c_idle.idle))
                        return PTR_ERR(c_idle.idle);
                idle = c_idle.idle;
                current_set[cpu] = c_idle.idle;
        }
        init_idle(idle, cpu);
        if (smp_alloc_lowcore(cpu))
                return -ENOMEM;
        do {
                ccode = sigp(cpu, sigp_initial_cpu_reset);
                if (ccode == sigp_busy)
                        udelay(10);
                if (ccode == sigp_not_operational)
                        goto err_out;
        } while (ccode == sigp_busy);

        lowcore = (u32)(unsigned long)lowcore_ptr[cpu];
        while (sigp_p(lowcore, cpu, sigp_set_prefix) == sigp_busy)
                udelay(10);

        cpu_lowcore = lowcore_ptr[cpu];
        cpu_lowcore->kernel_stack = (unsigned long)
                task_stack_page(idle) + THREAD_SIZE;
        cpu_lowcore->thread_info = (unsigned long) task_thread_info(idle);
        sf = (struct stack_frame *) (cpu_lowcore->kernel_stack
                                     - sizeof(struct pt_regs)
                                     - sizeof(struct stack_frame));
        memset(sf, 0, sizeof(struct stack_frame));
        sf->gprs[9] = (unsigned long) sf;
        cpu_lowcore->save_area[15] = (unsigned long) sf;
        __ctl_store(cpu_lowcore->cregs_save_area, 0, 15);
        atomic_inc(&init_mm.context.attach_count);
        asm volatile(
                "       stam    0,15,0(%0)"
                : : "a" (&cpu_lowcore->access_regs_save_area) : "memory");
        cpu_lowcore->percpu_offset = __per_cpu_offset[cpu];
        cpu_lowcore->current_task = (unsigned long) idle;
        cpu_lowcore->cpu_nr = cpu;
        cpu_lowcore->kernel_asce = S390_lowcore.kernel_asce;
        cpu_lowcore->machine_flags = S390_lowcore.machine_flags;
        cpu_lowcore->ftrace_func = S390_lowcore.ftrace_func;
        memcpy(cpu_lowcore->stfle_fac_list, S390_lowcore.stfle_fac_list,
               MAX_FACILITY_BIT/8);
        eieio();

        while (sigp(cpu, sigp_restart) == sigp_busy)
                udelay(10);

        while (!cpu_online(cpu))
                cpu_relax();
        return 0;

err_out:
        smp_free_lowcore(cpu);
        return -EIO;
}

static int __init setup_possible_cpus(char *s)
{
        int pcpus, cpu;

        pcpus = simple_strtoul(s, NULL, 0);
        init_cpu_possible(cpumask_of(0));
        for (cpu = 1; cpu < pcpus && cpu < nr_cpu_ids; cpu++)
                set_cpu_possible(cpu, true);
        return 0;
}
early_param("possible_cpus", setup_possible_cpus);

#ifdef CONFIG_HOTPLUG_CPU

int __cpu_disable(void)
{
        struct ec_creg_mask_parms cr_parms;
        int cpu = smp_processor_id();

        set_cpu_online(cpu, false);

        /* Disable pfault pseudo page faults on this cpu. */
        pfault_fini();

        memset(&cr_parms.orvals, 0, sizeof(cr_parms.orvals));
        memset(&cr_parms.andvals, 0xff, sizeof(cr_parms.andvals));

        /* disable all external interrupts */
        cr_parms.orvals[0] = 0;
        cr_parms.andvals[0] = ~(1 << 15 | 1 << 14 | 1 << 13 | 1 << 11 |
                                1 << 10 | 1 <<  9 | 1 <<  6 | 1 <<  5 |
                                1 <<  4);
        /* disable all I/O interrupts */
        cr_parms.orvals[6] = 0;
        cr_parms.andvals[6] = ~(1 << 31 | 1 << 30 | 1 << 29 | 1 << 28 |
                                1 << 27 | 1 << 26 | 1 << 25 | 1 << 24);
        /* disable most machine checks */
        cr_parms.orvals[14] = 0;
        cr_parms.andvals[14] = ~(1 << 28 | 1 << 27 | 1 << 26 |
                                 1 << 25 | 1 << 24);

        smp_ctl_bit_callback(&cr_parms);

        return 0;
}

void __cpu_die(unsigned int cpu)
{
        /* Wait until target cpu is down */
        while (!cpu_stopped(cpu))
                cpu_relax();
        while (sigp_p(0, cpu, sigp_set_prefix) == sigp_busy)
                udelay(10);
        smp_free_lowcore(cpu);
        atomic_dec(&init_mm.context.attach_count);
}

void __noreturn cpu_die(void)
{
        idle_task_exit();
        while (sigp(smp_processor_id(), sigp_stop) == sigp_busy)
                cpu_relax();
        for (;;);
}

#endif /* CONFIG_HOTPLUG_CPU */

void __init smp_prepare_cpus(unsigned int max_cpus)
{
#ifndef CONFIG_64BIT
        unsigned long save_area = 0;
#endif
        unsigned long async_stack, panic_stack;
        struct _lowcore *lowcore;

        smp_detect_cpus();

        /* request the 0x1201 emergency signal external interrupt */
        if (register_external_interrupt(0x1201, do_ext_call_interrupt) != 0)
                panic("Couldn't request external interrupt 0x1201");

        /* Reallocate current lowcore, but keep its contents. */
        lowcore = (void *) __get_free_pages(GFP_KERNEL | GFP_DMA, LC_ORDER);
        panic_stack = __get_free_page(GFP_KERNEL);
        async_stack = __get_free_pages(GFP_KERNEL, ASYNC_ORDER);
        BUG_ON(!lowcore || !panic_stack || !async_stack);
#ifndef CONFIG_64BIT
        if (MACHINE_HAS_IEEE)
                save_area = get_zeroed_page(GFP_KERNEL);
#endif
        local_irq_disable();
        local_mcck_disable();
        lowcore_ptr[smp_processor_id()] = lowcore;
        *lowcore = S390_lowcore;
        lowcore->panic_stack = panic_stack + PAGE_SIZE;
        lowcore->async_stack = async_stack + ASYNC_SIZE;
#ifndef CONFIG_64BIT
        if (MACHINE_HAS_IEEE)
                lowcore->extended_save_area_addr = (u32) save_area;
#endif
        set_prefix((u32)(unsigned long) lowcore);
        local_mcck_enable();
        local_irq_enable();
#ifdef CONFIG_64BIT
        if (vdso_alloc_per_cpu(smp_processor_id(), &S390_lowcore))
                BUG();
#endif
}

void __init smp_prepare_boot_cpu(void)
{
        BUG_ON(smp_processor_id() != 0);

        current_thread_info()->cpu = 0;
        set_cpu_present(0, true);
        set_cpu_online(0, true);
        S390_lowcore.percpu_offset = __per_cpu_offset[0];
        current_set[0] = current;
        smp_cpu_state[0] = CPU_STATE_CONFIGURED;
        smp_cpu_polarization[0] = POLARIZATION_UNKNWN;
}

void __init smp_cpus_done(unsigned int max_cpus)
{
}

void __init smp_setup_processor_id(void)
{
        S390_lowcore.cpu_nr = 0;
        __cpu_logical_map[0] = stap();
}

/*
 * the frequency of the profiling timer can be changed
 * by writing a multiplier value into /proc/profile.
 *
 * usually you want to run this on all CPUs ;)
 */
int setup_profiling_timer(unsigned int multiplier)
{
        return 0;
}

#ifdef CONFIG_HOTPLUG_CPU
static ssize_t cpu_configure_show(struct sys_device *dev,
                                struct sysdev_attribute *attr, char *buf)
{
        ssize_t count;

        mutex_lock(&smp_cpu_state_mutex);
        count = sprintf(buf, "%d\n", smp_cpu_state[dev->id]);
        mutex_unlock(&smp_cpu_state_mutex);
        return count;
}

static ssize_t cpu_configure_store(struct sys_device *dev,
                                  struct sysdev_attribute *attr,
                                  const char *buf, size_t count)
{
        int cpu = dev->id;
        int val, rc;
        char delim;

        if (sscanf(buf, "%d %c", &val, &delim) != 1)
                return -EINVAL;
        if (val != 0 && val != 1)
                return -EINVAL;

        get_online_cpus();
        mutex_lock(&smp_cpu_state_mutex);
        rc = -EBUSY;
        /* disallow configuration changes of online cpus and cpu 0 */
        if (cpu_online(cpu) || cpu == 0)
                goto out;
        rc = 0;
        switch (val) {
        case 0:
                if (smp_cpu_state[cpu] == CPU_STATE_CONFIGURED) {
                        rc = sclp_cpu_deconfigure(__cpu_logical_map[cpu]);
                        if (!rc) {
                                smp_cpu_state[cpu] = CPU_STATE_STANDBY;
                                smp_cpu_polarization[cpu] = POLARIZATION_UNKNWN;
                        }
                }
                break;
        case 1:
                if (smp_cpu_state[cpu] == CPU_STATE_STANDBY) {
                        rc = sclp_cpu_configure(__cpu_logical_map[cpu]);
                        if (!rc) {
                                smp_cpu_state[cpu] = CPU_STATE_CONFIGURED;
                                smp_cpu_polarization[cpu] = POLARIZATION_UNKNWN;
                        }
                }
                break;
        default:
                break;
        }
out:
        mutex_unlock(&smp_cpu_state_mutex);
        put_online_cpus();
        return rc ? rc : count;
}
static SYSDEV_ATTR(configure, 0644, cpu_configure_show, cpu_configure_store);
#endif /* CONFIG_HOTPLUG_CPU */

static ssize_t cpu_polarization_show(struct sys_device *dev,
                                     struct sysdev_attribute *attr, char *buf)
{
        int cpu = dev->id;
        ssize_t count;

        mutex_lock(&smp_cpu_state_mutex);
        switch (smp_cpu_polarization[cpu]) {
        case POLARIZATION_HRZ:
                count = sprintf(buf, "horizontal\n");
                break;
        case POLARIZATION_VL:
                count = sprintf(buf, "vertical:low\n");
                break;
        case POLARIZATION_VM:
                count = sprintf(buf, "vertical:medium\n");
                break;
        case POLARIZATION_VH:
                count = sprintf(buf, "vertical:high\n");
                break;
        default:
                count = sprintf(buf, "unknown\n");
                break;
        }
        mutex_unlock(&smp_cpu_state_mutex);
        return count;
}
static SYSDEV_ATTR(polarization, 0444, cpu_polarization_show, NULL);

static ssize_t show_cpu_address(struct sys_device *dev,
                                struct sysdev_attribute *attr, char *buf)
{
        return sprintf(buf, "%d\n", __cpu_logical_map[dev->id]);
}
static SYSDEV_ATTR(address, 0444, show_cpu_address, NULL);


static struct attribute *cpu_common_attrs[] = {
#ifdef CONFIG_HOTPLUG_CPU
        &attr_configure.attr,
#endif
        &attr_address.attr,
        &attr_polarization.attr,
        NULL,
};

static struct attribute_group cpu_common_attr_group = {
        .attrs = cpu_common_attrs,
};

static ssize_t show_capability(struct sys_device *dev,
                                struct sysdev_attribute *attr, char *buf)
{
        unsigned int capability;
        int rc;

        rc = get_cpu_capability(&capability);
        if (rc)
                return rc;
        return sprintf(buf, "%u\n", capability);
}
static SYSDEV_ATTR(capability, 0444, show_capability, NULL);

static ssize_t show_idle_count(struct sys_device *dev,
                                struct sysdev_attribute *attr, char *buf)
{
        struct s390_idle_data *idle;
        unsigned long long idle_count;
        unsigned int sequence;

        idle = &per_cpu(s390_idle, dev->id);
repeat:
        sequence = idle->sequence;
        smp_rmb();
        if (sequence & 1)
                goto repeat;
        idle_count = idle->idle_count;
        if (idle->idle_enter)
                idle_count++;
        smp_rmb();
        if (idle->sequence != sequence)
                goto repeat;
        return sprintf(buf, "%llu\n", idle_count);
}
static SYSDEV_ATTR(idle_count, 0444, show_idle_count, NULL);

static ssize_t show_idle_time(struct sys_device *dev,
                                struct sysdev_attribute *attr, char *buf)
{
        struct s390_idle_data *idle;
        unsigned long long now, idle_time, idle_enter;
        unsigned int sequence;

        idle = &per_cpu(s390_idle, dev->id);
        now = get_clock();
repeat:
        sequence = idle->sequence;
        smp_rmb();
        if (sequence & 1)
                goto repeat;
        idle_time = idle->idle_time;
        idle_enter = idle->idle_enter;
        if (idle_enter != 0ULL && idle_enter < now)
                idle_time += now - idle_enter;
        smp_rmb();
        if (idle->sequence != sequence)
                goto repeat;
        return sprintf(buf, "%llu\n", idle_time >> 12);
}
static SYSDEV_ATTR(idle_time_us, 0444, show_idle_time, NULL);

static struct attribute *cpu_online_attrs[] = {
        &attr_capability.attr,
        &attr_idle_count.attr,
        &attr_idle_time_us.attr,
        NULL,
};

static struct attribute_group cpu_online_attr_group = {
        .attrs = cpu_online_attrs,
};

static int __cpuinit smp_cpu_notify(struct notifier_block *self,
                                    unsigned long action, void *hcpu)
{
        unsigned int cpu = (unsigned int)(long)hcpu;
        struct cpu *c = &per_cpu(cpu_devices, cpu);
        struct sys_device *s = &c->sysdev;
        struct s390_idle_data *idle;
        int err = 0;

        switch (action) {
        case CPU_ONLINE:
        case CPU_ONLINE_FROZEN:
                idle = &per_cpu(s390_idle, cpu);
                memset(idle, 0, sizeof(struct s390_idle_data));
                err = sysfs_create_group(&s->kobj, &cpu_online_attr_group);
                break;
        case CPU_DEAD:
        case CPU_DEAD_FROZEN:
                sysfs_remove_group(&s->kobj, &cpu_online_attr_group);
                break;
        }
        return notifier_from_errno(err);
}

static struct notifier_block __cpuinitdata smp_cpu_nb = {
        .notifier_call = smp_cpu_notify,
};

static int __devinit smp_add_present_cpu(int cpu)
{
        struct cpu *c = &per_cpu(cpu_devices, cpu);
        struct sys_device *s = &c->sysdev;
        int rc;

        c->hotpluggable = 1;
        rc = register_cpu(c, cpu);
        if (rc)
                goto out;
        rc = sysfs_create_group(&s->kobj, &cpu_common_attr_group);
        if (rc)
                goto out_cpu;
        if (!cpu_online(cpu))
                goto out;
        rc = sysfs_create_group(&s->kobj, &cpu_online_attr_group);
        if (!rc)
                return 0;
        sysfs_remove_group(&s->kobj, &cpu_common_attr_group);
out_cpu:
#ifdef CONFIG_HOTPLUG_CPU
        unregister_cpu(c);
#endif
out:
        return rc;
}

#ifdef CONFIG_HOTPLUG_CPU

int __ref smp_rescan_cpus(void)
{
        cpumask_t newcpus;
        int cpu;
        int rc;

        get_online_cpus();
        mutex_lock(&smp_cpu_state_mutex);
        cpumask_copy(&newcpus, cpu_present_mask);
        rc = __smp_rescan_cpus();
        if (rc)
                goto out;
        cpumask_andnot(&newcpus, cpu_present_mask, &newcpus);
        for_each_cpu(cpu, &newcpus) {
                rc = smp_add_present_cpu(cpu);
                if (rc)
                        set_cpu_present(cpu, false);
        }
        rc = 0;
out:
        mutex_unlock(&smp_cpu_state_mutex);
        put_online_cpus();
        if (!cpumask_empty(&newcpus))
                topology_schedule_update();
        return rc;
}

static ssize_t __ref rescan_store(struct sysdev_class *class,
                                  struct sysdev_class_attribute *attr,
                                  const char *buf,
                                  size_t count)
{
        int rc;

        rc = smp_rescan_cpus();
        return rc ? rc : count;
}
static SYSDEV_CLASS_ATTR(rescan, 0200, NULL, rescan_store);
#endif /* CONFIG_HOTPLUG_CPU */

static ssize_t dispatching_show(struct sysdev_class *class,
                                struct sysdev_class_attribute *attr,
                                char *buf)
{
        ssize_t count;

        mutex_lock(&smp_cpu_state_mutex);
        count = sprintf(buf, "%d\n", cpu_management);
        mutex_unlock(&smp_cpu_state_mutex);
        return count;
}

static ssize_t dispatching_store(struct sysdev_class *dev,
                                 struct sysdev_class_attribute *attr,
                                 const char *buf,
                                 size_t count)
{
        int val, rc;
        char delim;

        if (sscanf(buf, "%d %c", &val, &delim) != 1)
                return -EINVAL;
        if (val != 0 && val != 1)
                return -EINVAL;
        rc = 0;
        get_online_cpus();
        mutex_lock(&smp_cpu_state_mutex);
        if (cpu_management == val)
                goto out;
        rc = topology_set_cpu_management(val);
        if (!rc)
                cpu_management = val;
out:
        mutex_unlock(&smp_cpu_state_mutex);
        put_online_cpus();
        return rc ? rc : count;
}
static SYSDEV_CLASS_ATTR(dispatching, 0644, dispatching_show,
                         dispatching_store);

static int __init topology_init(void)
{
        int cpu;
        int rc;

        register_cpu_notifier(&smp_cpu_nb);

#ifdef CONFIG_HOTPLUG_CPU
        rc = sysdev_class_create_file(&cpu_sysdev_class, &attr_rescan);
        if (rc)
                return rc;
#endif
        rc = sysdev_class_create_file(&cpu_sysdev_class, &attr_dispatching);
        if (rc)
                return rc;
        for_each_present_cpu(cpu) {
                rc = smp_add_present_cpu(cpu);
                if (rc)
                        return rc;
        }
        return 0;
}
subsys_initcall(topology_init);