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 } 146