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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.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/smp.h>
#include <linux/seq_file.h>
#include <linux/irq.h>

#include <asm/atomic.h>
#include <asm/cacheflush.h>
#include <asm/cpu.h>
#include <asm/mmu_context.h>
#include <asm/pgtable.h>
#include <asm/pgalloc.h>
#include <asm/processor.h>
#include <asm/tlbflush.h>
#include <asm/ptrace.h>

/*
 * bitmask of present and online CPUs.
 * The present bitmask indicates that the CPU is physically present.
 * The online bitmask indicates that the CPU is up and running.
 */
cpumask_t cpu_possible_map;
EXPORT_SYMBOL(cpu_possible_map);
cpumask_t cpu_online_map;
EXPORT_SYMBOL(cpu_online_map);

/*
 * 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;

/*
 * structures for inter-processor calls
 * - A collection of single bit ipi messages.
 */
struct ipi_data {
      spinlock_t lock;
      unsigned long ipi_count;
      unsigned long bits;
};

static DEFINE_PER_CPU(struct ipi_data, ipi_data) = {
      .lock = SPIN_LOCK_UNLOCKED,
};

enum ipi_msg_type {
      IPI_TIMER,
      IPI_RESCHEDULE,
      IPI_CALL_FUNC,
      IPI_CPU_STOP,
};

struct smp_call_struct {
      void (*func)(void *info);
      void *info;
      int wait;
      cpumask_t pending;
      cpumask_t unfinished;
};

static struct smp_call_struct * volatile smp_call_function_data;
static DEFINE_SPINLOCK(smp_call_function_lock);

int __cpuinit __cpu_up(unsigned int cpu)
{
      struct cpuinfo_arm *ci = &per_cpu(cpu_data, cpu);
      struct task_struct *idle = ci->idle;
      pgd_t *pgd;
      pmd_t *pmd;
      int ret;

      /*
       * Spawn a new process manually, if not already done.
       * Grab a pointer to its task struct so we can mess with it
       */
      if (!idle) {
            idle = fork_idle(cpu);
            if (IS_ERR(idle)) {
                  printk(KERN_ERR "CPU%u: fork() failed\n", cpu);
                  return PTR_ERR(idle);
            }
            ci->idle = idle;
      }

      /*
       * Allocate initial page tables to allow the new CPU to
       * enable the MMU safely.  This essentially means a set
       * of our "standard" page tables, with the addition of
       * a 1:1 mapping for the physical address of the kernel.
       */
      pgd = pgd_alloc(&init_mm);
      pmd = pmd_offset(pgd, PHYS_OFFSET);
      *pmd = __pmd((PHYS_OFFSET & PGDIR_MASK) |
                 PMD_TYPE_SECT | PMD_SECT_AP_WRITE);

      /*
       * 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;
      secondary_data.pgdir = virt_to_phys(pgd);
      wmb();

      /*
       * Now bring the CPU into our world.
       */
      ret = boot_secondary(cpu, idle);
      if (ret == 0) {
            unsigned long timeout;

            /*
             * CPU was successfully started, wait for it
             * to come online or time out.
             */
            timeout = jiffies + HZ;
            while (time_before(jiffies, timeout)) {
                  if (cpu_online(cpu))
                        break;

                  udelay(10);
                  barrier();
            }

            if (!cpu_online(cpu))
                  ret = -EIO;
      }

      secondary_data.stack = NULL;
      secondary_data.pgdir = 0;

      *pmd_offset(pgd, PHYS_OFFSET) = __pmd(0);
      pgd_free(&init_mm, pgd);

      if (ret) {
            printk(KERN_CRIT "CPU%u: processor failed to boot\n", cpu);

            /*
             * FIXME: We need to clean up the new idle thread. --rmk
             */
      }

      return ret;
}

#ifdef CONFIG_HOTPLUG_CPU
/*
 * __cpu_disable runs on the processor to be shutdown.
 */
int __cpuexit __cpu_disable(void)
{
      unsigned int cpu = smp_processor_id();
      struct task_struct *p;
      int ret;

      ret = mach_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.
       */
      cpu_clear(cpu, cpu_online_map);

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

      /*
       * Stop the local timer for this CPU.
       */
      local_timer_stop(cpu);

      /*
       * Flush user cache and TLB mappings, and then remove this CPU
       * from the vm mask set of all processes.
       */
      flush_cache_all();
      local_flush_tlb_all();

      read_lock(&tasklist_lock);
      for_each_process(p) {
            if (p->mm)
                  cpu_clear(cpu, p->mm->cpu_vm_mask);
      }
      read_unlock(&tasklist_lock);

      return 0;
}

/*
 * called on the thread which is asking for a CPU to be shutdown -
 * waits until shutdown has completed, or it is timed out.
 */
void __cpuexit __cpu_die(unsigned int cpu)
{
      if (!platform_cpu_kill(cpu))
            printk("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 __cpuexit cpu_die(void)
{
      unsigned int cpu = smp_processor_id();

      local_irq_disable();
      idle_task_exit();

      /*
       * actual CPU shutdown procedure is at least platform (if not
       * CPU) specific
       */
      platform_cpu_die(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"
      "     b     secondary_start_kernel"
            :
            : "r" (task_stack_page(current) + THREAD_SIZE - 8));
}
#endif /* CONFIG_HOTPLUG_CPU */

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

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

      /*
       * All kernel threads share the same mm context; grab a
       * reference and switch to it.
       */
      atomic_inc(&mm->mm_users);
      atomic_inc(&mm->mm_count);
      current->active_mm = mm;
      cpu_set(cpu, mm->cpu_vm_mask);
      cpu_switch_mm(mm->pgd, mm);
      enter_lazy_tlb(mm, current);
      local_flush_tlb_all();

      cpu_init();
      preempt_disable();

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

      /*
       * Enable local interrupts.
       */
      local_irq_enable();
      local_fiq_enable();

      /*
       * Setup local timer for this CPU.
       */
      local_timer_setup(cpu);

      calibrate_delay();

      smp_store_cpu_info(cpu);

      /*
       * OK, now it's safe to let the boot CPU continue
       */
      cpu_set(cpu, cpu_online_map);

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

/*
 * Called by both boot and secondaries to move global data into
 * per-processor storage.
 */
void __cpuinit 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;
}

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);
}

void __init smp_prepare_boot_cpu(void)
{
      unsigned int cpu = smp_processor_id();

      per_cpu(cpu_data, cpu).idle = current;
}

static void send_ipi_message(cpumask_t callmap, enum ipi_msg_type msg)
{
      unsigned long flags;
      unsigned int cpu;

      local_irq_save(flags);

      for_each_cpu_mask(cpu, callmap) {
            struct ipi_data *ipi = &per_cpu(ipi_data, cpu);

            spin_lock(&ipi->lock);
            ipi->bits |= 1 << msg;
            spin_unlock(&ipi->lock);
      }

      /*
       * Call the platform specific cross-CPU call function.
       */
      smp_cross_call(callmap);

      local_irq_restore(flags);
}

/*
 * You must not call this function with disabled interrupts, from a
 * hardware interrupt handler, nor from a bottom half handler.
 */
static int smp_call_function_on_cpu(void (*func)(void *info), void *info,
                            int retry, int wait, cpumask_t callmap)
{
      struct smp_call_struct data;
      unsigned long timeout;
      int ret = 0;

      data.func = func;
      data.info = info;
      data.wait = wait;

      cpu_clear(smp_processor_id(), callmap);
      if (cpus_empty(callmap))
            goto out;

      data.pending = callmap;
      if (wait)
            data.unfinished = callmap;

      /*
       * try to get the mutex on smp_call_function_data
       */
      spin_lock(&smp_call_function_lock);
      smp_call_function_data = &data;

      send_ipi_message(callmap, IPI_CALL_FUNC);

      timeout = jiffies + HZ;
      while (!cpus_empty(data.pending) && time_before(jiffies, timeout))
            barrier();

      /*
       * did we time out?
       */
      if (!cpus_empty(data.pending)) {
            /*
             * this may be causing our panic - report it
             */
            printk(KERN_CRIT
                   "CPU%u: smp_call_function timeout for %p(%p)\n"
                   "      callmap %lx pending %lx, %swait\n",
                   smp_processor_id(), func, info, *cpus_addr(callmap),
                   *cpus_addr(data.pending), wait ? "" : "no ");

            /*
             * TRACE
             */
            timeout = jiffies + (5 * HZ);
            while (!cpus_empty(data.pending) && time_before(jiffies, timeout))
                  barrier();

            if (cpus_empty(data.pending))
                  printk(KERN_CRIT "     RESOLVED\n");
            else
                  printk(KERN_CRIT "     STILL STUCK\n");
      }

      /*
       * whatever happened, we're done with the data, so release it
       */
      smp_call_function_data = NULL;
      spin_unlock(&smp_call_function_lock);

      if (!cpus_empty(data.pending)) {
            ret = -ETIMEDOUT;
            goto out;
      }

      if (wait)
            while (!cpus_empty(data.unfinished))
                  barrier();
 out:

      return 0;
}

int smp_call_function(void (*func)(void *info), void *info, int retry,
                      int wait)
{
      return smp_call_function_on_cpu(func, info, retry, wait,
                              cpu_online_map);
}
EXPORT_SYMBOL_GPL(smp_call_function);

int smp_call_function_single(int cpu, void (*func)(void *info), void *info,
                       int retry, int wait)
{
      /* prevent preemption and reschedule on another processor */
      int current_cpu = get_cpu();
      int ret = 0;

      if (cpu == current_cpu) {
            local_irq_disable();
            func(info);
            local_irq_enable();
      } else
            ret = smp_call_function_on_cpu(func, info, retry, wait,
                                     cpumask_of_cpu(cpu));

      put_cpu();

      return ret;
}
EXPORT_SYMBOL_GPL(smp_call_function_single);

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

      seq_puts(p, "IPI:");

      for_each_present_cpu(cpu)
            seq_printf(p, " %10lu", per_cpu(ipi_data, cpu).ipi_count);

      seq_putc(p, '\n');
}

void show_local_irqs(struct seq_file *p)
{
      unsigned int cpu;

      seq_printf(p, "LOC: ");

      for_each_present_cpu(cpu)
            seq_printf(p, "%10u ", irq_stat[cpu].local_timer_irqs);

      seq_putc(p, '\n');
}

static void ipi_timer(void)
{
      irq_enter();
      local_timer_interrupt();
      irq_exit();
}

#ifdef CONFIG_LOCAL_TIMERS
asmlinkage void __exception do_local_timer(struct pt_regs *regs)
{
      struct pt_regs *old_regs = set_irq_regs(regs);
      int cpu = smp_processor_id();

      if (local_timer_ack()) {
            irq_stat[cpu].local_timer_irqs++;
            ipi_timer();
      }

      set_irq_regs(old_regs);
}
#endif

/*
 * ipi_call_function - handle IPI from smp_call_function()
 *
 * Note that we copy data out of the cross-call structure and then
 * let the caller know that we're here and have done with their data
 */
static void ipi_call_function(unsigned int cpu)
{
      struct smp_call_struct *data = smp_call_function_data;
      void (*func)(void *info) = data->func;
      void *info = data->info;
      int wait = data->wait;

      cpu_clear(cpu, data->pending);

      func(info);

      if (wait)
            cpu_clear(cpu, data->unfinished);
}

static DEFINE_SPINLOCK(stop_lock);

/*
 * ipi_cpu_stop - handle IPI from smp_send_stop()
 */
static void ipi_cpu_stop(unsigned int cpu)
{
      spin_lock(&stop_lock);
      printk(KERN_CRIT "CPU%u: stopping\n", cpu);
      dump_stack();
      spin_unlock(&stop_lock);

      cpu_clear(cpu, cpu_online_map);

      local_fiq_disable();
      local_irq_disable();

      while (1)
            cpu_relax();
}

/*
 * Main handler for inter-processor interrupts
 *
 * For ARM, the ipimask now only identifies a single
 * category of IPI (Bit 1 IPIs have been replaced by a
 * different mechanism):
 *
 *  Bit 0 - Inter-processor function call
 */
asmlinkage void __exception do_IPI(struct pt_regs *regs)
{
      unsigned int cpu = smp_processor_id();
      struct ipi_data *ipi = &per_cpu(ipi_data, cpu);
      struct pt_regs *old_regs = set_irq_regs(regs);

      ipi->ipi_count++;

      for (;;) {
            unsigned long msgs;

            spin_lock(&ipi->lock);
            msgs = ipi->bits;
            ipi->bits = 0;
            spin_unlock(&ipi->lock);

            if (!msgs)
                  break;

            do {
                  unsigned nextmsg;

                  nextmsg = msgs & -msgs;
                  msgs &= ~nextmsg;
                  nextmsg = ffz(~nextmsg);

                  switch (nextmsg) {
                  case IPI_TIMER:
                        ipi_timer();
                        break;

                  case IPI_RESCHEDULE:
                        /*
                         * nothing more to do - eveything is
                         * done on the interrupt return path
                         */
                        break;

                  case IPI_CALL_FUNC:
                        ipi_call_function(cpu);
                        break;

                  case IPI_CPU_STOP:
                        ipi_cpu_stop(cpu);
                        break;

                  default:
                        printk(KERN_CRIT "CPU%u: Unknown IPI message 0x%x\n",
                               cpu, nextmsg);
                        break;
                  }
            } while (msgs);
      }

      set_irq_regs(old_regs);
}

void smp_send_reschedule(int cpu)
{
      send_ipi_message(cpumask_of_cpu(cpu), IPI_RESCHEDULE);
}

void smp_send_timer(void)
{
      cpumask_t mask = cpu_online_map;
      cpu_clear(smp_processor_id(), mask);
      send_ipi_message(mask, IPI_TIMER);
}

void smp_timer_broadcast(cpumask_t mask)
{
      send_ipi_message(mask, IPI_TIMER);
}

void smp_send_stop(void)
{
      cpumask_t mask = cpu_online_map;
      cpu_clear(smp_processor_id(), mask);
      send_ipi_message(mask, IPI_CPU_STOP);
}

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

static int
on_each_cpu_mask(void (*func)(void *), void *info, int retry, int wait,
             cpumask_t mask)
{
      int ret = 0;

      preempt_disable();

      ret = smp_call_function_on_cpu(func, info, retry, wait, mask);
      if (cpu_isset(smp_processor_id(), mask))
            func(info);

      preempt_enable();

      return ret;
}

/**********************************************************************/

/*
 * TLB operations
 */
struct tlb_args {
      struct vm_area_struct *ta_vma;
      unsigned long ta_start;
      unsigned long ta_end;
};

static inline void ipi_flush_tlb_all(void *ignored)
{
      local_flush_tlb_all();
}

static inline void ipi_flush_tlb_mm(void *arg)
{
      struct mm_struct *mm = (struct mm_struct *)arg;

      local_flush_tlb_mm(mm);
}

static inline void ipi_flush_tlb_page(void *arg)
{
      struct tlb_args *ta = (struct tlb_args *)arg;

      local_flush_tlb_page(ta->ta_vma, ta->ta_start);
}

static inline void ipi_flush_tlb_kernel_page(void *arg)
{
      struct tlb_args *ta = (struct tlb_args *)arg;

      local_flush_tlb_kernel_page(ta->ta_start);
}

static inline void ipi_flush_tlb_range(void *arg)
{
      struct tlb_args *ta = (struct tlb_args *)arg;

      local_flush_tlb_range(ta->ta_vma, ta->ta_start, ta->ta_end);
}

static inline void ipi_flush_tlb_kernel_range(void *arg)
{
      struct tlb_args *ta = (struct tlb_args *)arg;

      local_flush_tlb_kernel_range(ta->ta_start, ta->ta_end);
}

void flush_tlb_all(void)
{
      on_each_cpu(ipi_flush_tlb_all, NULL, 1, 1);
}

void flush_tlb_mm(struct mm_struct *mm)
{
      cpumask_t mask = mm->cpu_vm_mask;

      on_each_cpu_mask(ipi_flush_tlb_mm, mm, 1, 1, mask);
}

void flush_tlb_page(struct vm_area_struct *vma, unsigned long uaddr)
{
      cpumask_t mask = vma->vm_mm->cpu_vm_mask;
      struct tlb_args ta;

      ta.ta_vma = vma;
      ta.ta_start = uaddr;

      on_each_cpu_mask(ipi_flush_tlb_page, &ta, 1, 1, mask);
}

void flush_tlb_kernel_page(unsigned long kaddr)
{
      struct tlb_args ta;

      ta.ta_start = kaddr;

      on_each_cpu(ipi_flush_tlb_kernel_page, &ta, 1, 1);
}

void flush_tlb_range(struct vm_area_struct *vma,
                     unsigned long start, unsigned long end)
{
      cpumask_t mask = vma->vm_mm->cpu_vm_mask;
      struct tlb_args ta;

      ta.ta_vma = vma;
      ta.ta_start = start;
      ta.ta_end = end;

      on_each_cpu_mask(ipi_flush_tlb_range, &ta, 1, 1, mask);
}

void flush_tlb_kernel_range(unsigned long start, unsigned long end)
{
      struct tlb_args ta;

      ta.ta_start = start;
      ta.ta_end = end;

      on_each_cpu(ipi_flush_tlb_kernel_range, &ta, 1, 1);
}

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