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. */
  33 static int crashing_cpu;
  34
  35 #if defined(CONFIG_SMP) && defined(CONFIG_X86_LOCAL_APIC)
  36 static atomic_t waiting_for_crash_ipi;
  37
  38 static 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
  78 static 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
  86 static struct notifier_block crash_nmi_nb = {
  87         .notifier_call = crash_nmi_callback,
  88 };
  89
  90 static 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
 115 static void nmi_shootdown_cpus(void)
 116 {
 117         /* There are no cpus to shootdown */
 118 }
 119 #endif
 120
 121 void 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 }