LXR linux/arch/i386/kernel/crash.c

   1/*
   2 * Architecture specific (i386) functions for kexec based crash dumps.
   3 *
   4 * Created by: Hariprasad Nellitheertha (hari@in.ibm.com)
   5 *
   6 * Copyright (C) IBM Corporation, 2004. All rights reserved.
   7 *
   8 */
   9
  10#include <linux/init.h>
  11#include <linux/types.h>
  12#include <linux/kernel.h>
  13#include <linux/smp.h>
  14#include <linux/reboot.h>
  15#include <linux/kexec.h>
  16#include <linux/delay.h>
  17#include <linux/elf.h>
  18#include <linux/elfcore.h>
  19
  20#include <asm/processor.h>
  21#include <asm/hardirq.h>
  22#include <asm/nmi.h>
  23#include <asm/hw_irq.h>
  24#include <asm/apic.h>
  25#include <linux/kdebug.h>
  26#include <asm/smp.h>
  27
  28#include <mach_ipi.h>
  29
  30
  31/* This keeps a track of which one is crashing cpu. */
  32static int crashing_cpu;
  33
  34#if defined(CONFIG_SMP) && defined(CONFIG_X86_LOCAL_APIC)
  35static atomic_t waiting_for_crash_ipi;
  36
  37static int crash_nmi_callback(struct notifier_block *self,
  38                        unsigned long val, void *data)
  39{
  40        struct pt_regs *regs;
  41        struct pt_regs fixed_regs;
  42        int cpu;
  43
  44        if (val != DIE_NMI_IPI)
  45                return NOTIFY_OK;
  46
  47        regs = ((struct die_args *)data)->regs;
  48        cpu = raw_smp_processor_id();
  49
  50        /* Don't do anything if this handler is invoked on crashing cpu.
  51         * Otherwise, system will completely hang. Crashing cpu can get
  52         * an NMI if system was initially booted with nmi_watchdog parameter.
  53         */
  54        if (cpu == crashing_cpu)
  55                return NOTIFY_STOP;
  56        local_irq_disable();
  57
  58        if (!user_mode_vm(regs)) {
  59                crash_fixup_ss_esp(&fixed_regs, regs);
  60                regs = &fixed_regs;
  61        }
  62        crash_save_cpu(regs, cpu);
  63        disable_local_APIC();
  64        atomic_dec(&waiting_for_crash_ipi);
  65        /* Assume hlt works */
  66        halt();
  67        for (;;)
  68                cpu_relax();
  69
  70        return 1;
  71}
  72
  73static void smp_send_nmi_allbutself(void)
  74{
  75        cpumask_t mask = cpu_online_map;
  76        cpu_clear(safe_smp_processor_id(), mask);
  77        if (!cpus_empty(mask))
  78                send_IPI_mask(mask, NMI_VECTOR);
  79}
  80
  81static struct notifier_block crash_nmi_nb = {
  82        .notifier_call = crash_nmi_callback,
  83};
  84
  85static void nmi_shootdown_cpus(void)
  86{
  87        unsigned long msecs;
  88
  89        atomic_set(&waiting_for_crash_ipi, num_online_cpus() - 1);
  90        /* Would it be better to replace the trap vector here? */
  91        if (register_die_notifier(&crash_nmi_nb))
  92                return;         /* return what? */
  93        /* Ensure the new callback function is set before sending
  94         * out the NMI
  95         */
  96        wmb();
  97
  98        smp_send_nmi_allbutself();
  99
 100        msecs = 1000; /* Wait at most a second for the other cpus to stop */
 101        while ((atomic_read(&waiting_for_crash_ipi) > 0) && msecs) {
 102                mdelay(1);
 103                msecs--;
 104        }
 105
 106        /* Leave the nmi callback set */
 107        disable_local_APIC();
 108}
 109#else
 110static void nmi_shootdown_cpus(void)
 111{
 112        /* There are no cpus to shootdown */
 113}
 114#endif
 115
 116void machine_crash_shutdown(struct pt_regs *regs)
 117{
 118        /* This function is only called after the system
 119         * has panicked or is otherwise in a critical state.
 120         * The minimum amount of code to allow a kexec'd kernel
 121         * to run successfully needs to happen here.
 122         *
 123         * In practice this means shooting down the other cpus in
 124         * an SMP system.
 125         */
 126        /* The kernel is broken so disable interrupts */
 127        local_irq_disable();
 128
 129        /* Make a note of crashing cpu. Will be used in NMI callback.*/
 130        crashing_cpu = safe_smp_processor_id();
 131        nmi_shootdown_cpus();
 132        lapic_shutdown();
 133#if defined(CONFIG_X86_IO_APIC)
 134        disable_IO_APIC();
 135#endif
 136        crash_save_cpu(regs, safe_smp_processor_id());
 137}
 138