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 #endif
  61
  62 #ifdef CONFIG_X86_32
  63         if (!user_mode_vm(regs)) {
  64                 crash_fixup_ss_esp(&fixed_regs, regs);
  65                 regs = &fixed_regs;
  66         }
  67 #endif
  68         crash_save_cpu(regs, cpu);
  69
  70         /*
  71          * VMCLEAR VMCSs loaded on all cpus if needed.
  72          */
  73         cpu_crash_vmclear_loaded_vmcss();
  74
  75         /* Disable VMX or SVM if needed.
  76          *
  77          * We need to disable virtualization on all CPUs.
  78          * Having VMX or SVM enabled on any CPU may break rebooting
  79          * after the kdump kernel has finished its task.
  80          */
  81         cpu_emergency_vmxoff();
  82         cpu_emergency_svm_disable();
  83
  84         disable_local_APIC();
  85 }
  86
  87 static void kdump_nmi_shootdown_cpus(void)
  88 {
  89         in_crash_kexec = 1;
  90         nmi_shootdown_cpus(kdump_nmi_callback);
  91
  92         disable_local_APIC();
  93 }
  94
  95 #else
  96 static void kdump_nmi_shootdown_cpus(void)
  97 {
  98         /* There are no cpus to shootdown */
  99 }
 100 #endif
 101
 102 void native_machine_crash_shutdown(struct pt_regs *regs)
 103 {
 104         /* This function is only called after the system
 105          * has panicked or is otherwise in a critical state.
 106          * The minimum amount of code to allow a kexec'd kernel
 107          * to run successfully needs to happen here.
 108          *
 109          * In practice this means shooting down the other cpus in
 110          * an SMP system.
 111          */
 112         /* The kernel is broken so disable interrupts */
 113         local_irq_disable();
 114
 115         kdump_nmi_shootdown_cpus();
 116
 117         /*
 118          * VMCLEAR VMCSs loaded on this cpu if needed.
 119          */
 120         cpu_crash_vmclear_loaded_vmcss();
 121
 122         /* Booting kdump kernel with VMX or SVM enabled won't work,
 123          * because (among other limitations) we can't disable paging
 124          * with the virt flags.
 125          */
 126         cpu_emergency_vmxoff();
 127         cpu_emergency_svm_disable();
 128
 129 #ifdef CONFIG_X86_IO_APIC
 130         /* Prevent crash_kexec() from deadlocking on ioapic_lock. */
 131         ioapic_zap_locks();
 132         disable_IO_APIC();
 133 #endif
 134         lapic_shutdown();
 135 #ifdef CONFIG_HPET_TIMER
 136         hpet_disable();
 137 #endif
 138         crash_save_cpu(regs, safe_smp_processor_id());
 139 }