mm: fix exec activate_mm vs TLB shootdown and lazy tlb switching race

[linux/fpc-iii.git] / arch / arm / kernel / smp.c

/*
 *  linux/arch/arm/kernel/smp.c
 *
 *  Copyright (C) 2002 ARM Limited, All Rights Reserved.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */
#include <linux/module.h>
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/spinlock.h>
#include <linux/sched/mm.h>
#include <linux/sched/hotplug.h>
#include <linux/sched/task_stack.h>
#include <linux/interrupt.h>
#include <linux/cache.h>
#include <linux/profile.h>
#include <linux/errno.h>
#include <linux/mm.h>
#include <linux/err.h>
#include <linux/cpu.h>
#include <linux/seq_file.h>
#include <linux/irq.h>
#include <linux/nmi.h>
#include <linux/percpu.h>
#include <linux/clockchips.h>
#include <linux/completion.h>
#include <linux/cpufreq.h>
#include <linux/irq_work.h>

#include <linux/atomic.h>
#include <asm/bugs.h>
#include <asm/smp.h>
#include <asm/cacheflush.h>
#include <asm/cpu.h>
#include <asm/cputype.h>
#include <asm/exception.h>
#include <asm/idmap.h>
#include <asm/topology.h>
#include <asm/mmu_context.h>
#include <asm/pgtable.h>
#include <asm/pgalloc.h>
#include <asm/procinfo.h>
#include <asm/processor.h>
#include <asm/sections.h>
#include <asm/tlbflush.h>
#include <asm/ptrace.h>
#include <asm/smp_plat.h>
#include <asm/virt.h>
#include <asm/mach/arch.h>
#include <asm/mpu.h>

#define CREATE_TRACE_POINTS
#include <trace/events/ipi.h>

/*
 * as from 2.5, kernels no longer have an init_tasks structure
 * so we need some other way of telling a new secondary core
 * where to place its SVC stack
 */
struct secondary_data secondary_data;

/*
 * control for which core is the next to come out of the secondary
 * boot "holding pen"
 */
volatile int pen_release = -1;

enum ipi_msg_type {
        IPI_WAKEUP,
        IPI_TIMER,
        IPI_RESCHEDULE,
        IPI_CALL_FUNC,
        IPI_CPU_STOP,
        IPI_IRQ_WORK,
        IPI_COMPLETION,
        /*
         * CPU_BACKTRACE is special and not included in NR_IPI
         * or tracable with trace_ipi_*
         */
        IPI_CPU_BACKTRACE,
        /*
         * SGI8-15 can be reserved by secure firmware, and thus may
         * not be usable by the kernel. Please keep the above limited
         * to at most 8 entries.
         */
};

static DECLARE_COMPLETION(cpu_running);

static struct smp_operations smp_ops __ro_after_init;

void __init smp_set_ops(const struct smp_operations *ops)
{
        if (ops)
                smp_ops = *ops;
};

static unsigned long get_arch_pgd(pgd_t *pgd)
{
#ifdef CONFIG_ARM_LPAE
        return __phys_to_pfn(virt_to_phys(pgd));
#else
        return virt_to_phys(pgd);
#endif
}

#if defined(CONFIG_BIG_LITTLE) && defined(CONFIG_HARDEN_BRANCH_PREDICTOR)
static int secondary_biglittle_prepare(unsigned int cpu)
{
        if (!cpu_vtable[cpu])
                cpu_vtable[cpu] = kzalloc(sizeof(*cpu_vtable[cpu]), GFP_KERNEL);

        return cpu_vtable[cpu] ? 0 : -ENOMEM;
}

static void secondary_biglittle_init(void)
{
        init_proc_vtable(lookup_processor(read_cpuid_id())->proc);
}
#else
static int secondary_biglittle_prepare(unsigned int cpu)
{
        return 0;
}

static void secondary_biglittle_init(void)
{
}
#endif

int __cpu_up(unsigned int cpu, struct task_struct *idle)
{
        int ret;

        if (!smp_ops.smp_boot_secondary)
                return -ENOSYS;

        ret = secondary_biglittle_prepare(cpu);
        if (ret)
                return ret;

        /*
         * We need to tell the secondary core where to find
         * its stack and the page tables.
         */
        secondary_data.stack = task_stack_page(idle) + THREAD_START_SP;
#ifdef CONFIG_ARM_MPU
        secondary_data.mpu_rgn_szr = mpu_rgn_info.rgns[MPU_RAM_REGION].drsr;
#endif

#ifdef CONFIG_MMU
        secondary_data.pgdir = virt_to_phys(idmap_pgd);
        secondary_data.swapper_pg_dir = get_arch_pgd(swapper_pg_dir);
#endif
        sync_cache_w(&secondary_data);

        /*
         * Now bring the CPU into our world.
         */
        ret = smp_ops.smp_boot_secondary(cpu, idle);
        if (ret == 0) {
                /*
                 * CPU was successfully started, wait for it
                 * to come online or time out.
                 */
                wait_for_completion_timeout(&cpu_running,
                                                 msecs_to_jiffies(1000));

                if (!cpu_online(cpu)) {
                        pr_crit("CPU%u: failed to come online\n", cpu);
                        ret = -EIO;
                }
        } else {
                pr_err("CPU%u: failed to boot: %d\n", cpu, ret);
        }


        memset(&secondary_data, 0, sizeof(secondary_data));
        return ret;
}

/* platform specific SMP operations */
void __init smp_init_cpus(void)
{
        if (smp_ops.smp_init_cpus)
                smp_ops.smp_init_cpus();
}

int platform_can_secondary_boot(void)
{
        return !!smp_ops.smp_boot_secondary;
}

int platform_can_cpu_hotplug(void)
{
#ifdef CONFIG_HOTPLUG_CPU
        if (smp_ops.cpu_kill)
                return 1;
#endif

        return 0;
}

#ifdef CONFIG_HOTPLUG_CPU
static int platform_cpu_kill(unsigned int cpu)
{
        if (smp_ops.cpu_kill)
                return smp_ops.cpu_kill(cpu);
        return 1;
}

static int platform_cpu_disable(unsigned int cpu)
{
        if (smp_ops.cpu_disable)
                return smp_ops.cpu_disable(cpu);

        return 0;
}

int platform_can_hotplug_cpu(unsigned int cpu)
{
        /* cpu_die must be specified to support hotplug */
        if (!smp_ops.cpu_die)
                return 0;

        if (smp_ops.cpu_can_disable)
                return smp_ops.cpu_can_disable(cpu);

        /*
         * By default, allow disabling all CPUs except the first one,
         * since this is special on a lot of platforms, e.g. because
         * of clock tick interrupts.
         */
        return cpu != 0;
}

/*
 * __cpu_disable runs on the processor to be shutdown.
 */
int __cpu_disable(void)
{
        unsigned int cpu = smp_processor_id();
        int ret;

        ret = platform_cpu_disable(cpu);
        if (ret)
                return ret;

        /*
         * Take this CPU offline.  Once we clear this, we can't return,
         * and we must not schedule until we're ready to give up the cpu.
         */
        set_cpu_online(cpu, false);

        /*
         * OK - migrate IRQs away from this CPU
         */
        irq_migrate_all_off_this_cpu();

        /*
         * Flush user cache and TLB mappings, and then remove this CPU
         * from the vm mask set of all processes.
         *
         * Caches are flushed to the Level of Unification Inner Shareable
         * to write-back dirty lines to unified caches shared by all CPUs.
         */
        flush_cache_louis();
        local_flush_tlb_all();

        clear_tasks_mm_cpumask(cpu);

        return 0;
}

static DECLARE_COMPLETION(cpu_died);

/*
 * called on the thread which is asking for a CPU to be shutdown -
 * waits until shutdown has completed, or it is timed out.
 */
void __cpu_die(unsigned int cpu)
{
        if (!wait_for_completion_timeout(&cpu_died, msecs_to_jiffies(5000))) {
                pr_err("CPU%u: cpu didn't die\n", cpu);
                return;
        }
        pr_debug("CPU%u: shutdown\n", cpu);

        /*
         * platform_cpu_kill() is generally expected to do the powering off
         * and/or cutting of clocks to the dying CPU.  Optionally, this may
         * be done by the CPU which is dying in preference to supporting
         * this call, but that means there is _no_ synchronisation between
         * the requesting CPU and the dying CPU actually losing power.
         */
        if (!platform_cpu_kill(cpu))
                pr_err("CPU%u: unable to kill\n", cpu);
}

/*
 * Called from the idle thread for the CPU which has been shutdown.
 *
 * Note that we disable IRQs here, but do not re-enable them
 * before returning to the caller. This is also the behaviour
 * of the other hotplug-cpu capable cores, so presumably coming
 * out of idle fixes this.
 */
void arch_cpu_idle_dead(void)
{
        unsigned int cpu = smp_processor_id();

        idle_task_exit();

        local_irq_disable();

        /*
         * Flush the data out of the L1 cache for this CPU.  This must be
         * before the completion to ensure that data is safely written out
         * before platform_cpu_kill() gets called - which may disable
         * *this* CPU and power down its cache.
         */
        flush_cache_louis();

        /*
         * Tell __cpu_die() that this CPU is now safe to dispose of.  Once
         * this returns, power and/or clocks can be removed at any point
         * from this CPU and its cache by platform_cpu_kill().
         */
        complete(&cpu_died);

        /*
         * Ensure that the cache lines associated with that completion are
         * written out.  This covers the case where _this_ CPU is doing the
         * powering down, to ensure that the completion is visible to the
         * CPU waiting for this one.
         */
        flush_cache_louis();

        /*
         * The actual CPU shutdown procedure is at least platform (if not
         * CPU) specific.  This may remove power, or it may simply spin.
         *
         * Platforms are generally expected *NOT* to return from this call,
         * although there are some which do because they have no way to
         * power down the CPU.  These platforms are the _only_ reason we
         * have a return path which uses the fragment of assembly below.
         *
         * The return path should not be used for platforms which can
         * power off the CPU.
         */
        if (smp_ops.cpu_die)
                smp_ops.cpu_die(cpu);

        pr_warn("CPU%u: smp_ops.cpu_die() returned, trying to resuscitate\n",
                cpu);

        /*
         * Do not return to the idle loop - jump back to the secondary
         * cpu initialisation.  There's some initialisation which needs
         * to be repeated to undo the effects of taking the CPU offline.
         */
        __asm__("mov    sp, %0\n"
        "       mov     fp, #0\n"
        "       b       secondary_start_kernel"
                :
                : "r" (task_stack_page(current) + THREAD_SIZE - 8));
}
#endif /* CONFIG_HOTPLUG_CPU */

/*
 * Called by both boot and secondaries to move global data into
 * per-processor storage.
 */
static void smp_store_cpu_info(unsigned int cpuid)
{
        struct cpuinfo_arm *cpu_info = &per_cpu(cpu_data, cpuid);

        cpu_info->loops_per_jiffy = loops_per_jiffy;
        cpu_info->cpuid = read_cpuid_id();

        store_cpu_topology(cpuid);
}

/*
 * This is the secondary CPU boot entry.  We're using this CPUs
 * idle thread stack, but a set of temporary page tables.
 */
asmlinkage void secondary_start_kernel(void)
{
        struct mm_struct *mm = &init_mm;
        unsigned int cpu;

        secondary_biglittle_init();

        /*
         * The identity mapping is uncached (strongly ordered), so
         * switch away from it before attempting any exclusive accesses.
         */
        cpu_switch_mm(mm->pgd, mm);
        local_flush_bp_all();
        enter_lazy_tlb(mm, current);
        local_flush_tlb_all();

        /*
         * All kernel threads share the same mm context; grab a
         * reference and switch to it.
         */
        cpu = smp_processor_id();
        mmgrab(mm);
        current->active_mm = mm;
        cpumask_set_cpu(cpu, mm_cpumask(mm));

        cpu_init();

        pr_debug("CPU%u: Booted secondary processor\n", cpu);

        preempt_disable();
        trace_hardirqs_off();

        /*
         * Give the platform a chance to do its own initialisation.
         */
        if (smp_ops.smp_secondary_init)
                smp_ops.smp_secondary_init(cpu);

        notify_cpu_starting(cpu);

        calibrate_delay();

        smp_store_cpu_info(cpu);

        /*
         * OK, now it's safe to let the boot CPU continue.  Wait for
         * the CPU migration code to notice that the CPU is online
         * before we continue - which happens after __cpu_up returns.
         */
        set_cpu_online(cpu, true);

        check_other_bugs();

        complete(&cpu_running);

        local_irq_enable();
        local_fiq_enable();
        local_abt_enable();

        /*
         * OK, it's off to the idle thread for us
         */
        cpu_startup_entry(CPUHP_AP_ONLINE_IDLE);
}

void __init smp_cpus_done(unsigned int max_cpus)
{
        int cpu;
        unsigned long bogosum = 0;

        for_each_online_cpu(cpu)
                bogosum += per_cpu(cpu_data, cpu).loops_per_jiffy;

        printk(KERN_INFO "SMP: Total of %d processors activated "
               "(%lu.%02lu BogoMIPS).\n",
               num_online_cpus(),
               bogosum / (500000/HZ),
               (bogosum / (5000/HZ)) % 100);

        hyp_mode_check();
}

void __init smp_prepare_boot_cpu(void)
{
        set_my_cpu_offset(per_cpu_offset(smp_processor_id()));
}

void __init smp_prepare_cpus(unsigned int max_cpus)
{
        unsigned int ncores = num_possible_cpus();

        init_cpu_topology();

        smp_store_cpu_info(smp_processor_id());

        /*
         * are we trying to boot more cores than exist?
         */
        if (max_cpus > ncores)
                max_cpus = ncores;
        if (ncores > 1 && max_cpus) {
                /*
                 * Initialise the present map, which describes the set of CPUs
                 * actually populated at the present time. A platform should
                 * re-initialize the map in the platforms smp_prepare_cpus()
                 * if present != possible (e.g. physical hotplug).
                 */
                init_cpu_present(cpu_possible_mask);

                /*
                 * Initialise the SCU if there are more than one CPU
                 * and let them know where to start.
                 */
                if (smp_ops.smp_prepare_cpus)
                        smp_ops.smp_prepare_cpus(max_cpus);
        }
}

static void (*__smp_cross_call)(const struct cpumask *, unsigned int);

void __init set_smp_cross_call(void (*fn)(const struct cpumask *, unsigned int))
{
        if (!__smp_cross_call)
                __smp_cross_call = fn;
}

static const char *ipi_types[NR_IPI] __tracepoint_string = {
#define S(x,s)  [x] = s
        S(IPI_WAKEUP, "CPU wakeup interrupts"),
        S(IPI_TIMER, "Timer broadcast interrupts"),
        S(IPI_RESCHEDULE, "Rescheduling interrupts"),
        S(IPI_CALL_FUNC, "Function call interrupts"),
        S(IPI_CPU_STOP, "CPU stop interrupts"),
        S(IPI_IRQ_WORK, "IRQ work interrupts"),
        S(IPI_COMPLETION, "completion interrupts"),
};

static void smp_cross_call(const struct cpumask *target, unsigned int ipinr)
{
        trace_ipi_raise_rcuidle(target, ipi_types[ipinr]);
        __smp_cross_call(target, ipinr);
}

void show_ipi_list(struct seq_file *p, int prec)
{
        unsigned int cpu, i;

        for (i = 0; i < NR_IPI; i++) {
                seq_printf(p, "%*s%u: ", prec - 1, "IPI", i);

                for_each_online_cpu(cpu)
                        seq_printf(p, "%10u ",
                                   __get_irq_stat(cpu, ipi_irqs[i]));

                seq_printf(p, " %s\n", ipi_types[i]);
        }
}

u64 smp_irq_stat_cpu(unsigned int cpu)
{
        u64 sum = 0;
        int i;

        for (i = 0; i < NR_IPI; i++)
                sum += __get_irq_stat(cpu, ipi_irqs[i]);

        return sum;
}

void arch_send_call_function_ipi_mask(const struct cpumask *mask)
{
        smp_cross_call(mask, IPI_CALL_FUNC);
}

void arch_send_wakeup_ipi_mask(const struct cpumask *mask)
{
        smp_cross_call(mask, IPI_WAKEUP);
}

void arch_send_call_function_single_ipi(int cpu)
{
        smp_cross_call(cpumask_of(cpu), IPI_CALL_FUNC);
}

#ifdef CONFIG_IRQ_WORK
void arch_irq_work_raise(void)
{
        if (arch_irq_work_has_interrupt())
                smp_cross_call(cpumask_of(smp_processor_id()), IPI_IRQ_WORK);
}
#endif

#ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
void tick_broadcast(const struct cpumask *mask)
{
        smp_cross_call(mask, IPI_TIMER);
}
#endif

static DEFINE_RAW_SPINLOCK(stop_lock);

/*
 * ipi_cpu_stop - handle IPI from smp_send_stop()
 */
static void ipi_cpu_stop(unsigned int cpu)
{
        if (system_state <= SYSTEM_RUNNING) {
                raw_spin_lock(&stop_lock);
                pr_crit("CPU%u: stopping\n", cpu);
                dump_stack();
                raw_spin_unlock(&stop_lock);
        }

        set_cpu_online(cpu, false);

        local_fiq_disable();
        local_irq_disable();

        while (1) {
                cpu_relax();
                wfe();
        }
}

static DEFINE_PER_CPU(struct completion *, cpu_completion);

int register_ipi_completion(struct completion *completion, int cpu)
{
        per_cpu(cpu_completion, cpu) = completion;
        return IPI_COMPLETION;
}

static void ipi_complete(unsigned int cpu)
{
        complete(per_cpu(cpu_completion, cpu));
}

/*
 * Main handler for inter-processor interrupts
 */
asmlinkage void __exception_irq_entry do_IPI(int ipinr, struct pt_regs *regs)
{
        handle_IPI(ipinr, regs);
}

void handle_IPI(int ipinr, struct pt_regs *regs)
{
        unsigned int cpu = smp_processor_id();
        struct pt_regs *old_regs = set_irq_regs(regs);

        if ((unsigned)ipinr < NR_IPI) {
                trace_ipi_entry_rcuidle(ipi_types[ipinr]);
                __inc_irq_stat(cpu, ipi_irqs[ipinr]);
        }

        switch (ipinr) {
        case IPI_WAKEUP:
                break;

#ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
        case IPI_TIMER:
                irq_enter();
                tick_receive_broadcast();
                irq_exit();
                break;
#endif

        case IPI_RESCHEDULE:
                scheduler_ipi();
                break;

        case IPI_CALL_FUNC:
                irq_enter();
                generic_smp_call_function_interrupt();
                irq_exit();
                break;

        case IPI_CPU_STOP:
                irq_enter();
                ipi_cpu_stop(cpu);
                irq_exit();
                break;

#ifdef CONFIG_IRQ_WORK
        case IPI_IRQ_WORK:
                irq_enter();
                irq_work_run();
                irq_exit();
                break;
#endif

        case IPI_COMPLETION:
                irq_enter();
                ipi_complete(cpu);
                irq_exit();
                break;

        case IPI_CPU_BACKTRACE:
                printk_nmi_enter();
                irq_enter();
                nmi_cpu_backtrace(regs);
                irq_exit();
                printk_nmi_exit();
                break;

        default:
                pr_crit("CPU%u: Unknown IPI message 0x%x\n",
                        cpu, ipinr);
                break;
        }

        if ((unsigned)ipinr < NR_IPI)
                trace_ipi_exit_rcuidle(ipi_types[ipinr]);
        set_irq_regs(old_regs);
}

void smp_send_reschedule(int cpu)
{
        smp_cross_call(cpumask_of(cpu), IPI_RESCHEDULE);
}

void smp_send_stop(void)
{
        unsigned long timeout;
        struct cpumask mask;

        cpumask_copy(&mask, cpu_online_mask);
        cpumask_clear_cpu(smp_processor_id(), &mask);
        if (!cpumask_empty(&mask))
                smp_cross_call(&mask, IPI_CPU_STOP);

        /* Wait up to one second for other CPUs to stop */
        timeout = USEC_PER_SEC;
        while (num_online_cpus() > 1 && timeout--)
                udelay(1);

        if (num_online_cpus() > 1)
                pr_warn("SMP: failed to stop secondary CPUs\n");
}

/* In case panic() and panic() called at the same time on CPU1 and CPU2,
 * and CPU 1 calls panic_smp_self_stop() before crash_smp_send_stop()
 * CPU1 can't receive the ipi irqs from CPU2, CPU1 will be always online,
 * kdump fails. So split out the panic_smp_self_stop() and add
 * set_cpu_online(smp_processor_id(), false).
 */
void panic_smp_self_stop(void)
{
        pr_debug("CPU %u will stop doing anything useful since another CPU has paniced\n",
                 smp_processor_id());
        set_cpu_online(smp_processor_id(), false);
        while (1)
                cpu_relax();
}

/*
 * not supported here
 */
int setup_profiling_timer(unsigned int multiplier)
{
        return -EINVAL;
}

#ifdef CONFIG_CPU_FREQ

static DEFINE_PER_CPU(unsigned long, l_p_j_ref);
static DEFINE_PER_CPU(unsigned long, l_p_j_ref_freq);
static unsigned long global_l_p_j_ref;
static unsigned long global_l_p_j_ref_freq;

static int cpufreq_callback(struct notifier_block *nb,
                                        unsigned long val, void *data)
{
        struct cpufreq_freqs *freq = data;
        int cpu = freq->cpu;

        if (freq->flags & CPUFREQ_CONST_LOOPS)
                return NOTIFY_OK;

        if (!per_cpu(l_p_j_ref, cpu)) {
                per_cpu(l_p_j_ref, cpu) =
                        per_cpu(cpu_data, cpu).loops_per_jiffy;
                per_cpu(l_p_j_ref_freq, cpu) = freq->old;
                if (!global_l_p_j_ref) {
                        global_l_p_j_ref = loops_per_jiffy;
                        global_l_p_j_ref_freq = freq->old;
                }
        }

        if ((val == CPUFREQ_PRECHANGE  && freq->old < freq->new) ||
            (val == CPUFREQ_POSTCHANGE && freq->old > freq->new)) {
                loops_per_jiffy = cpufreq_scale(global_l_p_j_ref,
                                                global_l_p_j_ref_freq,
                                                freq->new);
                per_cpu(cpu_data, cpu).loops_per_jiffy =
                        cpufreq_scale(per_cpu(l_p_j_ref, cpu),
                                        per_cpu(l_p_j_ref_freq, cpu),
                                        freq->new);
        }
        return NOTIFY_OK;
}

static struct notifier_block cpufreq_notifier = {
        .notifier_call  = cpufreq_callback,
};

static int __init register_cpufreq_notifier(void)
{
        return cpufreq_register_notifier(&cpufreq_notifier,
                                                CPUFREQ_TRANSITION_NOTIFIER);
}
core_initcall(register_cpufreq_notifier);

#endif

static void raise_nmi(cpumask_t *mask)
{
        __smp_cross_call(mask, IPI_CPU_BACKTRACE);
}

void arch_trigger_cpumask_backtrace(const cpumask_t *mask, bool exclude_self)
{
        nmi_trigger_cpumask_backtrace(mask, exclude_self, raise_nmi);
}