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crash.c

/*
 * Architecture specific (PPC64) functions for kexec based crash dumps.
 *
 * Copyright (C) 2005, IBM Corp.
 *
 * Created by: Haren Myneni
 *
 * This source code is licensed under the GNU General Public License,
 * Version 2.  See the file COPYING for more details.
 *
 */

#undef DEBUG

#include <linux/kernel.h>
#include <linux/smp.h>
#include <linux/reboot.h>
#include <linux/kexec.h>
#include <linux/bootmem.h>
#include <linux/crash_dump.h>
#include <linux/delay.h>
#include <linux/elf.h>
#include <linux/elfcore.h>
#include <linux/init.h>
#include <linux/irq.h>
#include <linux/types.h>
#include <linux/lmb.h>

#include <asm/processor.h>
#include <asm/machdep.h>
#include <asm/kexec.h>
#include <asm/kdump.h>
#include <asm/prom.h>
#include <asm/firmware.h>
#include <asm/smp.h>
#include <asm/system.h>
#include <asm/setjmp.h>

#ifdef DEBUG
#include <asm/udbg.h>
#define DBG(fmt...) udbg_printf(fmt)
#else
#define DBG(fmt...)
#endif

/* This keeps a track of which one is crashing cpu. */
int crashing_cpu = -1;
static cpumask_t cpus_in_crash = CPU_MASK_NONE;
cpumask_t cpus_in_sr = CPU_MASK_NONE;

#define CRASH_HANDLER_MAX 2
/* NULL terminated list of shutdown handles */
static crash_shutdown_t crash_shutdown_handles[CRASH_HANDLER_MAX+1];
static DEFINE_SPINLOCK(crash_handlers_lock);

#ifdef CONFIG_SMP
static atomic_t enter_on_soft_reset = ATOMIC_INIT(0);

void crash_ipi_callback(struct pt_regs *regs)
{
      int cpu = smp_processor_id();

      if (!cpu_online(cpu))
            return;

      hard_irq_disable();
      if (!cpu_isset(cpu, cpus_in_crash))
            crash_save_cpu(regs, cpu);
      cpu_set(cpu, cpus_in_crash);

      /*
       * Entered via soft-reset - could be the kdump
       * process is invoked using soft-reset or user activated
       * it if some CPU did not respond to an IPI.
       * For soft-reset, the secondary CPU can enter this func
       * twice. 1 - using IPI, and 2. soft-reset.
       * Tell the kexec CPU that entered via soft-reset and ready
       * to go down.
       */
      if (cpu_isset(cpu, cpus_in_sr)) {
            cpu_clear(cpu, cpus_in_sr);
            atomic_inc(&enter_on_soft_reset);
      }

      /*
       * Starting the kdump boot.
       * This barrier is needed to make sure that all CPUs are stopped.
       * If not, soft-reset will be invoked to bring other CPUs.
       */
      while (!cpu_isset(crashing_cpu, cpus_in_crash))
            cpu_relax();

      if (ppc_md.kexec_cpu_down)
            ppc_md.kexec_cpu_down(1, 1);

#ifdef CONFIG_PPC64
      kexec_smp_wait();
#else
      for (;;);   /* FIXME */
#endif

      /* NOTREACHED */
}

/*
 * Wait until all CPUs are entered via soft-reset.
 */
static void crash_soft_reset_check(int cpu)
{
      unsigned int ncpus = num_online_cpus() - 1;/* Excluding the panic cpu */

      cpu_clear(cpu, cpus_in_sr);
      while (atomic_read(&enter_on_soft_reset) != ncpus)
            cpu_relax();
}


static void crash_kexec_prepare_cpus(int cpu)
{
      unsigned int msecs;

      unsigned int ncpus = num_online_cpus() - 1;/* Excluding the panic cpu */

      crash_send_ipi(crash_ipi_callback);
      smp_wmb();

      /*
       * FIXME: Until we will have the way to stop other CPUSs reliabally,
       * the crash CPU will send an IPI and wait for other CPUs to
       * respond.
       * Delay of at least 10 seconds.
       */
      printk(KERN_EMERG "Sending IPI to other cpus...\n");
      msecs = 10000;
      while ((cpus_weight(cpus_in_crash) < ncpus) && (--msecs > 0)) {
            cpu_relax();
            mdelay(1);
      }

      /* Would it be better to replace the trap vector here? */

      /*
       * FIXME: In case if we do not get all CPUs, one possibility: ask the
       * user to do soft reset such that we get all.
       * Soft-reset will be used until better mechanism is implemented.
       */
      if (cpus_weight(cpus_in_crash) < ncpus) {
            printk(KERN_EMERG "done waiting: %d cpu(s) not responding\n",
                  ncpus - cpus_weight(cpus_in_crash));
            printk(KERN_EMERG "Activate soft-reset to stop other cpu(s)\n");
            cpus_in_sr = CPU_MASK_NONE;
            atomic_set(&enter_on_soft_reset, 0);
            while (cpus_weight(cpus_in_crash) < ncpus)
                  cpu_relax();
      }
      /*
       * Make sure all CPUs are entered via soft-reset if the kdump is
       * invoked using soft-reset.
       */
      if (cpu_isset(cpu, cpus_in_sr))
            crash_soft_reset_check(cpu);
      /* Leave the IPI callback set */
}

/*
 * This function will be called by secondary cpus or by kexec cpu
 * if soft-reset is activated to stop some CPUs.
 */
void crash_kexec_secondary(struct pt_regs *regs)
{
      int cpu = smp_processor_id();
      unsigned long flags;
      int msecs = 5;

      local_irq_save(flags);
      /* Wait 5ms if the kexec CPU is not entered yet. */
      while (crashing_cpu < 0) {
            if (--msecs < 0) {
                  /*
                   * Either kdump image is not loaded or
                   * kdump process is not started - Probably xmon
                   * exited using 'x'(exit and recover) or
                   * kexec_should_crash() failed for all running tasks.
                   */
                  cpu_clear(cpu, cpus_in_sr);
                  local_irq_restore(flags);
                  return;
            }
            mdelay(1);
            cpu_relax();
      }
      if (cpu == crashing_cpu) {
            /*
             * Panic CPU will enter this func only via soft-reset.
             * Wait until all secondary CPUs entered and
             * then start kexec boot.
             */
            crash_soft_reset_check(cpu);
            cpu_set(crashing_cpu, cpus_in_crash);
            if (ppc_md.kexec_cpu_down)
                  ppc_md.kexec_cpu_down(1, 0);
            machine_kexec(kexec_crash_image);
            /* NOTREACHED */
      }
      crash_ipi_callback(regs);
}

#else
static void crash_kexec_prepare_cpus(int cpu)
{
      /*
       * move the secondarys to us so that we can copy
       * the new kernel 0-0x100 safely
       *
       * do this if kexec in setup.c ?
       */
#ifdef CONFIG_PPC64
      smp_release_cpus();
#else
      /* FIXME */
#endif
}

void crash_kexec_secondary(struct pt_regs *regs)
{
      cpus_in_sr = CPU_MASK_NONE;
}
#endif
#ifdef CONFIG_SPU_BASE

#include <asm/spu.h>
#include <asm/spu_priv1.h>

struct crash_spu_info {
      struct spu *spu;
      u32 saved_spu_runcntl_RW;
      u32 saved_spu_status_R;
      u32 saved_spu_npc_RW;
      u64 saved_mfc_sr1_RW;
      u64 saved_mfc_dar;
      u64 saved_mfc_dsisr;
};

#define CRASH_NUM_SPUS  16    /* Enough for current hardware */
static struct crash_spu_info crash_spu_info[CRASH_NUM_SPUS];

static void crash_kexec_stop_spus(void)
{
      struct spu *spu;
      int i;
      u64 tmp;

      for (i = 0; i < CRASH_NUM_SPUS; i++) {
            if (!crash_spu_info[i].spu)
                  continue;

            spu = crash_spu_info[i].spu;

            crash_spu_info[i].saved_spu_runcntl_RW =
                  in_be32(&spu->problem->spu_runcntl_RW);
            crash_spu_info[i].saved_spu_status_R =
                  in_be32(&spu->problem->spu_status_R);
            crash_spu_info[i].saved_spu_npc_RW =
                  in_be32(&spu->problem->spu_npc_RW);

            crash_spu_info[i].saved_mfc_dar    = spu_mfc_dar_get(spu);
            crash_spu_info[i].saved_mfc_dsisr  = spu_mfc_dsisr_get(spu);
            tmp = spu_mfc_sr1_get(spu);
            crash_spu_info[i].saved_mfc_sr1_RW = tmp;

            tmp &= ~MFC_STATE1_MASTER_RUN_CONTROL_MASK;
            spu_mfc_sr1_set(spu, tmp);

            __delay(200);
      }
}

void crash_register_spus(struct list_head *list)
{
      struct spu *spu;

      list_for_each_entry(spu, list, full_list) {
            if (WARN_ON(spu->number >= CRASH_NUM_SPUS))
                  continue;

            crash_spu_info[spu->number].spu = spu;
      }
}

#else
static inline void crash_kexec_stop_spus(void)
{
}
#endif /* CONFIG_SPU_BASE */

/*
 * Register a function to be called on shutdown.  Only use this if you
 * can't reset your device in the second kernel.
 */
int crash_shutdown_register(crash_shutdown_t handler)
{
      unsigned int i, rc;

      spin_lock(&crash_handlers_lock);
      for (i = 0 ; i < CRASH_HANDLER_MAX; i++)
            if (!crash_shutdown_handles[i]) {
                  /* Insert handle at first empty entry */
                  crash_shutdown_handles[i] = handler;
                  rc = 0;
                  break;
            }

      if (i == CRASH_HANDLER_MAX) {
            printk(KERN_ERR "Crash shutdown handles full, "
                   "not registered.\n");
            rc = 1;
      }

      spin_unlock(&crash_handlers_lock);
      return rc;
}
EXPORT_SYMBOL(crash_shutdown_register);

int crash_shutdown_unregister(crash_shutdown_t handler)
{
      unsigned int i, rc;

      spin_lock(&crash_handlers_lock);
      for (i = 0 ; i < CRASH_HANDLER_MAX; i++)
            if (crash_shutdown_handles[i] == handler)
                  break;

      if (i == CRASH_HANDLER_MAX) {
            printk(KERN_ERR "Crash shutdown handle not found\n");
            rc = 1;
      } else {
            /* Shift handles down */
            for (; crash_shutdown_handles[i]; i++)
                  crash_shutdown_handles[i] =
                        crash_shutdown_handles[i+1];
            rc = 0;
      }

      spin_unlock(&crash_handlers_lock);
      return rc;
}
EXPORT_SYMBOL(crash_shutdown_unregister);

static unsigned long crash_shutdown_buf[JMP_BUF_LEN];

static int handle_fault(struct pt_regs *regs)
{
      longjmp(crash_shutdown_buf, 1);
      return 0;
}

void default_machine_crash_shutdown(struct pt_regs *regs)
{
      unsigned int i;
      int (*old_handler)(struct pt_regs *regs);


      /*
       * This function is only called after the system
       * has panicked or is otherwise in a critical state.
       * The minimum amount of code to allow a kexec'd kernel
       * to run successfully needs to happen here.
       *
       * In practice this means stopping other cpus in
       * an SMP system.
       * The kernel is broken so disable interrupts.
       */
      hard_irq_disable();

      for_each_irq(i) {
            struct irq_desc *desc = irq_desc + i;

            if (desc->status & IRQ_INPROGRESS)
                  desc->chip->eoi(i);

            if (!(desc->status & IRQ_DISABLED))
                  desc->chip->disable(i);
      }

      /*
       * Call registered shutdown routines savely.  Swap out
       * __debugger_fault_handler, and replace on exit.
       */
      old_handler = __debugger_fault_handler;
      __debugger_fault_handler = handle_fault;
      for (i = 0; crash_shutdown_handles[i]; i++) {
            if (setjmp(crash_shutdown_buf) == 0) {
                  /*
                   * Insert syncs and delay to ensure
                   * instructions in the dangerous region don't
                   * leak away from this protected region.
                   */
                  asm volatile("sync; isync");
                  /* dangerous region */
                  crash_shutdown_handles[i]();
                  asm volatile("sync; isync");
            }
      }
      __debugger_fault_handler = old_handler;

      /*
       * Make a note of crashing cpu. Will be used in machine_kexec
       * such that another IPI will not be sent.
       */
      crashing_cpu = smp_processor_id();
      crash_save_cpu(regs, crashing_cpu);
      crash_kexec_prepare_cpus(crashing_cpu);
      cpu_set(crashing_cpu, cpus_in_crash);
      crash_kexec_stop_spus();
      if (ppc_md.kexec_cpu_down)
            ppc_md.kexec_cpu_down(1, 0);
}

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