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