1/* 2 * Architecture specific (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/irq.h> 15#include <linux/reboot.h> 16#include <linux/kexec.h> 17#include <linux/delay.h> 18#include <linux/elf.h> 19#include <linux/elfcore.h> 20#include <linux/kdebug.h> 21 22#include <asm/processor.h> 23#include <asm/hardirq.h> 24#include <asm/nmi.h> 25#include <asm/hw_irq.h> 26#include <asm/mach_apic.h> 27 28/* This keeps a track of which one is crashing cpu. */ 29static int crashing_cpu; 30 31#ifdef CONFIG_SMP 32static atomic_t waiting_for_crash_ipi; 33 34static int crash_nmi_callback(struct notifier_block *self, 35 unsigned long val, void *data) 36{ 37 struct pt_regs *regs; 38 int cpu; 39 40 if (val != DIE_NMI_IPI) 41 return NOTIFY_OK; 42 43 regs = ((struct die_args *)data)->regs; 44 cpu = raw_smp_processor_id(); 45 46 /* 47 * Don't do anything if this handler is invoked on crashing cpu. 48 * Otherwise, system will completely hang. Crashing cpu can get 49 * an NMI if system was initially booted with nmi_watchdog parameter. 50 */ 51 if (cpu == crashing_cpu) 52 return NOTIFY_STOP; 53 local_irq_disable(); 54 55 crash_save_cpu(regs, cpu); 56 disable_local_APIC(); 57 atomic_dec(&waiting_for_crash_ipi); 58 /* Assume hlt works */ 59 for(;;) 60 halt(); 61 62 return 1; 63} 64 65static void smp_send_nmi_allbutself(void) 66{ 67 send_IPI_allbutself(NMI_VECTOR); 68} 69 70/* 71 * This code is a best effort heuristic to get the 72 * other cpus to stop executing. So races with 73 * cpu hotplug shouldn't matter. 74 */ 75 76static struct notifier_block crash_nmi_nb = { 77 .notifier_call = crash_nmi_callback, 78}; 79 80static void nmi_shootdown_cpus(void) 81{ 82 unsigned long msecs; 83 84 atomic_set(&waiting_for_crash_ipi, num_online_cpus() - 1); 85 if (register_die_notifier(&crash_nmi_nb)) 86 return; /* return what? */ 87 88 /* 89 * Ensure the new callback function is set before sending 90 * out the NMI 91 */ 92 wmb(); 93 94 smp_send_nmi_allbutself(); 95 96 msecs = 1000; /* Wait at most a second for the other cpus to stop */ 97 while ((atomic_read(&waiting_for_crash_ipi) > 0) && msecs) { 98 mdelay(1); 99 msecs--; 100 } 101 /* Leave the nmi callback set */ 102 disable_local_APIC(); 103} 104#else 105static void nmi_shootdown_cpus(void) 106{ 107 /* There are no cpus to shootdown */ 108} 109#endif 110 111void machine_crash_shutdown(struct pt_regs *regs) 112{ 113 /* 114 * This function is only called after the system 115 * has panicked or is otherwise in a critical state. 116 * The minimum amount of code to allow a kexec'd kernel 117 * to run successfully needs to happen here. 118 * 119 * In practice this means shooting down the other cpus in 120 * an SMP system. 121 */ 122 /* The kernel is broken so disable interrupts */ 123 local_irq_disable(); 124 125 /* Make a note of crashing cpu. Will be used in NMI callback.*/ 126 crashing_cpu = smp_processor_id(); 127 nmi_shootdown_cpus(); 128 129 if(cpu_has_apic) 130 disable_local_APIC(); 131 132 disable_IO_APIC(); 133 134 crash_save_cpu(regs, smp_processor_id()); 135} 136