LXR linux/arch/x86/kernel/crash.c

   1/*
   2 * Architecture specific (i386/x86_64) 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 <asm/hpet.h>
  26#include <linux/kdebug.h>
  27#include <asm/smp.h>
  28#include <asm/reboot.h>
  29
  30#include <mach_ipi.h>
  31
  32/* This keeps a track of which one is crashing cpu. */
  33static int crashing_cpu;
  34
  35#if defined(CONFIG_SMP) && defined(CONFIG_X86_LOCAL_APIC)
  36static atomic_t waiting_for_crash_ipi;
  37
  38static int crash_nmi_callback(struct notifier_block *self,
  39                        unsigned long val, void *data)
  40{
  41        struct pt_regs *regs;
  42#ifdef CONFIG_X86_32
  43        struct pt_regs fixed_regs;
  44#endif
  45        int cpu;
  46
  47        if (val != DIE_NMI_IPI)
  48                return NOTIFY_OK;
  49
  50        regs = ((struct die_args *)data)->regs;
  51        cpu = raw_smp_processor_id();
  52
  53        /* Don't do anything if this handler is invoked on crashing cpu.
  54         * Otherwise, system will completely hang. Crashing cpu can get
  55         * an NMI if system was initially booted with nmi_watchdog parameter.
  56         */
  57        if (cpu == crashing_cpu)
  58                return NOTIFY_STOP;
  59        local_irq_disable();
  60
  61#ifdef CONFIG_X86_32
  62        if (!user_mode_vm(regs)) {
  63                crash_fixup_ss_esp(&fixed_regs, regs);
  64                regs = &fixed_regs;
  65        }
  66#endif
  67        crash_save_cpu(regs, cpu);
  68        disable_local_APIC();
  69        atomic_dec(&waiting_for_crash_ipi);
  70        /* Assume hlt works */
  71        halt();
  72        for (;;)
  73                cpu_relax();
  74
  75        return 1;
  76}
  77
  78static void smp_send_nmi_allbutself(void)
  79{
  80        cpumask_t mask = cpu_online_map;
  81        cpu_clear(safe_smp_processor_id(), mask);
  82        if (!cpus_empty(mask))
  83                send_IPI_mask(mask, NMI_VECTOR);
  84}
  85
  86static struct notifier_block crash_nmi_nb = {
  87        .notifier_call = crash_nmi_callback,
  88};
  89
  90static void nmi_shootdown_cpus(void)
  91{
  92        unsigned long msecs;
  93
  94        atomic_set(&waiting_for_crash_ipi, num_online_cpus() - 1);
  95        /* Would it be better to replace the trap vector here? */
  96        if (register_die_notifier(&crash_nmi_nb))
  97                return;         /* return what? */
  98        /* Ensure the new callback function is set before sending
  99         * out the NMI
 100         */
 101        wmb();
 102
 103        smp_send_nmi_allbutself();
 104
 105        msecs = 1000; /* Wait at most a second for the other cpus to stop */
 106        while ((atomic_read(&waiting_for_crash_ipi) > 0) && msecs) {
 107                mdelay(1);
 108                msecs--;
 109        }
 110
 111        /* Leave the nmi callback set */
 112        disable_local_APIC();
 113}
 114#else
 115static void nmi_shootdown_cpus(void)
 116{
 117        /* There are no cpus to shootdown */
 118}
 119#endif
 120
 121void native_machine_crash_shutdown(struct pt_regs *regs)
 122{
 123        /* This function is only called after the system
 124         * has panicked or is otherwise in a critical state.
 125         * The minimum amount of code to allow a kexec'd kernel
 126         * to run successfully needs to happen here.
 127         *
 128         * In practice this means shooting down the other cpus in
 129         * an SMP system.
 130         */
 131        /* The kernel is broken so disable interrupts */
 132        local_irq_disable();
 133
 134        /* Make a note of crashing cpu. Will be used in NMI callback.*/
 135        crashing_cpu = safe_smp_processor_id();
 136        nmi_shootdown_cpus();
 137        lapic_shutdown();
 138#if defined(CONFIG_X86_IO_APIC)
 139        disable_IO_APIC();
 140#endif
 141#ifdef CONFIG_HPET_TIMER
 142        hpet_disable();
 143#endif
 144        crash_save_cpu(regs, safe_smp_processor_id());
 145}
 146