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crash.c

/*
 * arch/ia64/kernel/crash.c
 *
 * Architecture specific (ia64) functions for kexec based crash dumps.
 *
 * Created by: Khalid Aziz <khalid.aziz@hp.com>
 * Copyright (C) 2005 Hewlett-Packard Development Company, L.P.
 * Copyright (C) 2005 Intel Corp    Zou Nan hai <nanhai.zou@intel.com>
 *
 */
#include <linux/smp.h>
#include <linux/delay.h>
#include <linux/crash_dump.h>
#include <linux/bootmem.h>
#include <linux/kexec.h>
#include <linux/elfcore.h>
#include <linux/sysctl.h>
#include <linux/init.h>
#include <linux/kdebug.h>

#include <asm/mca.h>

int kdump_status[NR_CPUS];
static atomic_t kdump_cpu_frozen;
atomic_t kdump_in_progress;
static int kdump_freeze_monarch;
static int kdump_on_init = 1;
static int kdump_on_fatal_mca = 1;

static inline Elf64_Word
*append_elf_note(Elf64_Word *buf, char *name, unsigned type, void *data,
            size_t data_len)
{
      struct elf_note *note = (struct elf_note *)buf;
      note->n_namesz = strlen(name) + 1;
      note->n_descsz = data_len;
      note->n_type   = type;
      buf += (sizeof(*note) + 3)/4;
      memcpy(buf, name, note->n_namesz);
      buf += (note->n_namesz + 3)/4;
      memcpy(buf, data, data_len);
      buf += (data_len + 3)/4;
      return buf;
}

static void
final_note(void *buf)
{
      memset(buf, 0, sizeof(struct elf_note));
}

extern void ia64_dump_cpu_regs(void *);

static DEFINE_PER_CPU(struct elf_prstatus, elf_prstatus);

void
crash_save_this_cpu(void)
{
      void *buf;
      unsigned long cfm, sof, sol;

      int cpu = smp_processor_id();
      struct elf_prstatus *prstatus = &per_cpu(elf_prstatus, cpu);

      elf_greg_t *dst = (elf_greg_t *)&(prstatus->pr_reg);
      memset(prstatus, 0, sizeof(*prstatus));
      prstatus->pr_pid = current->pid;

      ia64_dump_cpu_regs(dst);
      cfm = dst[43];
      sol = (cfm >> 7) & 0x7f;
      sof = cfm & 0x7f;
      dst[46] = (unsigned long)ia64_rse_skip_regs((unsigned long *)dst[46],
                  sof - sol);

      buf = (u64 *) per_cpu_ptr(crash_notes, cpu);
      if (!buf)
            return;
      buf = append_elf_note(buf, KEXEC_CORE_NOTE_NAME, NT_PRSTATUS, prstatus,
                  sizeof(*prstatus));
      final_note(buf);
}

#ifdef CONFIG_SMP
static int
kdump_wait_cpu_freeze(void)
{
      int cpu_num = num_online_cpus() - 1;
      int timeout = 1000;
      while(timeout-- > 0) {
            if (atomic_read(&kdump_cpu_frozen) == cpu_num)
                  return 0;
            udelay(1000);
      }
      return 1;
}
#endif

void
machine_crash_shutdown(struct pt_regs *pt)
{
      /* This function is only called after the system
       * has paniced 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 shooting down the other cpus in
       * an SMP system.
       */
      kexec_disable_iosapic();
#ifdef CONFIG_SMP
      /*
       * If kdump_on_init is set and an INIT is asserted here, kdump will
       * be started again via INIT monarch.
       */
      local_irq_disable();
      ia64_set_psr_mc();      /* mask MCA/INIT */
      if (atomic_inc_return(&kdump_in_progress) != 1)
            unw_init_running(kdump_cpu_freeze, NULL);

      /*
       * Now this cpu is ready for kdump.
       * Stop all others by IPI or INIT.  They could receive INIT from
       * outside and might be INIT monarch, but only thing they have to
       * do is falling into kdump_cpu_freeze().
       *
       * If an INIT is asserted here:
       * - All receivers might be slaves, since some of cpus could already
       *   be frozen and INIT might be masked on monarch.  In this case,
       *   all slaves will be frozen soon since kdump_in_progress will let
       *   them into DIE_INIT_SLAVE_LEAVE.
       * - One might be a monarch, but INIT rendezvous will fail since
       *   at least this cpu already have INIT masked so it never join
       *   to the rendezvous.  In this case, all slaves and monarch will
       *   be frozen soon with no wait since the INIT rendezvous is skipped
       *   by kdump_in_progress.
       */
      kdump_smp_send_stop();
      /* not all cpu response to IPI, send INIT to freeze them */
      if (kdump_wait_cpu_freeze()) {
            kdump_smp_send_init();
            /* wait again, don't go ahead if possible */
            kdump_wait_cpu_freeze();
      }
#endif
}

static void
machine_kdump_on_init(void)
{
      crash_save_vmcoreinfo();
      local_irq_disable();
      kexec_disable_iosapic();
      machine_kexec(ia64_kimage);
}

void
kdump_cpu_freeze(struct unw_frame_info *info, void *arg)
{
      int cpuid;

      local_irq_disable();
      cpuid = smp_processor_id();
      crash_save_this_cpu();
      current->thread.ksp = (__u64)info->sw - 16;

      ia64_set_psr_mc();      /* mask MCA/INIT and stop reentrance */

      atomic_inc(&kdump_cpu_frozen);
      kdump_status[cpuid] = 1;
      mb();
      for (;;)
            cpu_relax();
}

static int
kdump_init_notifier(struct notifier_block *self, unsigned long val, void *data)
{
      struct ia64_mca_notify_die *nd;
      struct die_args *args = data;

      if (atomic_read(&kdump_in_progress)) {
            switch (val) {
            case DIE_INIT_MONARCH_LEAVE:
                  if (!kdump_freeze_monarch)
                        break;
                  /* fall through */
            case DIE_INIT_SLAVE_LEAVE:
            case DIE_INIT_MONARCH_ENTER:
            case DIE_MCA_RENDZVOUS_LEAVE:
                  unw_init_running(kdump_cpu_freeze, NULL);
                  break;
            }
      }

      if (!kdump_on_init && !kdump_on_fatal_mca)
            return NOTIFY_DONE;

      if (!ia64_kimage) {
            if (val == DIE_INIT_MONARCH_LEAVE)
                  ia64_mca_printk(KERN_NOTICE
                              "%s: kdump not configured\n",
                              __func__);
            return NOTIFY_DONE;
      }

      if (val != DIE_INIT_MONARCH_LEAVE &&
          val != DIE_INIT_MONARCH_PROCESS &&
          val != DIE_MCA_MONARCH_LEAVE)
            return NOTIFY_DONE;

      nd = (struct ia64_mca_notify_die *)args->err;

      switch (val) {
      case DIE_INIT_MONARCH_PROCESS:
            /* Reason code 1 means machine check rendezvous*/
            if (kdump_on_init && (nd->sos->rv_rc != 1)) {
                  if (atomic_inc_return(&kdump_in_progress) != 1)
                        kdump_freeze_monarch = 1;
            }
            break;
      case DIE_INIT_MONARCH_LEAVE:
            /* Reason code 1 means machine check rendezvous*/
            if (kdump_on_init && (nd->sos->rv_rc != 1))
                  machine_kdump_on_init();
            break;
      case DIE_MCA_MONARCH_LEAVE:
            /* *(nd->data) indicate if MCA is recoverable */
            if (kdump_on_fatal_mca && !(*(nd->data))) {
                  if (atomic_inc_return(&kdump_in_progress) == 1)
                        machine_kdump_on_init();
                  /* We got fatal MCA while kdump!? No way!! */
            }
            break;
      }
      return NOTIFY_DONE;
}

#ifdef CONFIG_SYSCTL
static ctl_table kdump_ctl_table[] = {
      {
            .ctl_name = CTL_UNNUMBERED,
            .procname = "kdump_on_init",
            .data = &kdump_on_init,
            .maxlen = sizeof(int),
            .mode = 0644,
            .proc_handler = &proc_dointvec,
      },
      {
            .ctl_name = CTL_UNNUMBERED,
            .procname = "kdump_on_fatal_mca",
            .data = &kdump_on_fatal_mca,
            .maxlen = sizeof(int),
            .mode = 0644,
            .proc_handler = &proc_dointvec,
      },
      { .ctl_name = 0 }
};

static ctl_table sys_table[] = {
      {
        .ctl_name = CTL_KERN,
        .procname = "kernel",
        .mode = 0555,
        .child = kdump_ctl_table,
      },
      { .ctl_name = 0 }
};
#endif

static int
machine_crash_setup(void)
{
      /* be notified before default_monarch_init_process */
      static struct notifier_block kdump_init_notifier_nb = {
            .notifier_call = kdump_init_notifier,
            .priority = 1,
      };
      int ret;
      if((ret = register_die_notifier(&kdump_init_notifier_nb)) != 0)
            return ret;
#ifdef CONFIG_SYSCTL
      register_sysctl_table(sys_table);
#endif
      return 0;
}

__initcall(machine_crash_setup);


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