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/types.h>
  11 #include <linux/kernel.h>
  12 #include <linux/smp.h>
  13 #include <linux/reboot.h>
  14 #include <linux/kexec.h>
  15 #include <linux/delay.h>
  16 #include <linux/elf.h>
  17 #include <linux/elfcore.h>
  18 #include <linux/module.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/cpu.h>
  28 #include <asm/reboot.h>
  29 #include <asm/virtext.h>
  30
  31 int in_crash_kexec;
  32
  33 /*
  34  * This is used to VMCLEAR all VMCSs loaded on the
  35  * processor. And when loading kvm_intel module, the
  36  * callback function pointer will be assigned.
  37  *
  38  * protected by rcu.
  39  */
  40 crash_vmclear_fn __rcu *crash_vmclear_loaded_vmcss = NULL;
  41 EXPORT_SYMBOL_GPL(crash_vmclear_loaded_vmcss);
  42
  43 static inline void cpu_crash_vmclear_loaded_vmcss(void)
  44 {
  45         crash_vmclear_fn *do_vmclear_operation = NULL;
  46
  47         rcu_read_lock();
  48         do_vmclear_operation = rcu_dereference(crash_vmclear_loaded_vmcss);
  49         if (do_vmclear_operation)
  50                 do_vmclear_operation();
  51         rcu_read_unlock();
  52 }
  53
  54 #if defined(CONFIG_SMP) && defined(CONFIG_X86_LOCAL_APIC)
  55
  56 static void kdump_nmi_callback(int cpu, struct pt_regs *regs)
  57 {
  58 #ifdef CONFIG_X86_32
  59         struct pt_regs fixed_regs;
  60
  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
  68         /*
  69          * VMCLEAR VMCSs loaded on all cpus if needed.
  70          */
  71         cpu_crash_vmclear_loaded_vmcss();
  72
  73         /* Disable VMX or SVM if needed.
  74          *
  75          * We need to disable virtualization on all CPUs.
  76          * Having VMX or SVM enabled on any CPU may break rebooting
  77          * after the kdump kernel has finished its task.
  78          */
  79         cpu_emergency_vmxoff();
  80         cpu_emergency_svm_disable();
  81
  82         disable_local_APIC();
  83 }
  84
  85 static void kdump_nmi_shootdown_cpus(void)
  86 {
  87         in_crash_kexec = 1;
  88         nmi_shootdown_cpus(kdump_nmi_callback);
  89
  90         disable_local_APIC();
  91 }
  92
  93 #else
  94 static void kdump_nmi_shootdown_cpus(void)
  95 {
  96         /* There are no cpus to shootdown */
  97 }
  98 #endif
  99
 100 void native_machine_crash_shutdown(struct pt_regs *regs)
 101 {
 102         /* This function is only called after the system
 103          * has panicked or is otherwise in a critical state.
 104          * The minimum amount of code to allow a kexec'd kernel
 105          * to run successfully needs to happen here.
 106          *
 107          * In practice this means shooting down the other cpus in
 108          * an SMP system.
 109          */
 110         /* The kernel is broken so disable interrupts */
 111         local_irq_disable();
 112
 113         kdump_nmi_shootdown_cpus();
 114
 115         /*
 116          * VMCLEAR VMCSs loaded on this cpu if needed.
 117          */
 118         cpu_crash_vmclear_loaded_vmcss();
 119
 120         /* Booting kdump kernel with VMX or SVM enabled won't work,
 121          * because (among other limitations) we can't disable paging
 122          * with the virt flags.
 123          */
 124         cpu_emergency_vmxoff();
 125         cpu_emergency_svm_disable();
 126
 127 #ifdef CONFIG_X86_IO_APIC
 128         /* Prevent crash_kexec() from deadlocking on ioapic_lock. */
 129         ioapic_zap_locks();
 130         disable_IO_APIC();
 131 #endif
 132         lapic_shutdown();
 133 #ifdef CONFIG_HPET_TIMER
 134         hpet_disable();
 135 #endif
 136         crash_save_cpu(regs, safe_smp_processor_id());
 137 }