1/* 2 * Architecture specific (i386) 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 <linux/kdebug.h> 26#include <asm/smp.h> 27 28#include <mach_ipi.h> 29 30 31/* This keeps a track of which one is crashing cpu. */ 32static int crashing_cpu; 33 34#if defined(CONFIG_SMP) && defined(CONFIG_X86_LOCAL_APIC) 35static atomic_t waiting_for_crash_ipi; 36 37static int crash_nmi_callback(struct notifier_block *self, 38 unsigned long val, void *data) 39{ 40 struct pt_regs *regs; 41 struct pt_regs fixed_regs; 42 int cpu; 43 44 if (val != DIE_NMI_IPI) 45 return NOTIFY_OK; 46 47 regs = ((struct die_args *)data)->regs; 48 cpu = raw_smp_processor_id(); 49 50 /* Don't do anything if this handler is invoked on crashing cpu. 51 * Otherwise, system will completely hang. Crashing cpu can get 52 * an NMI if system was initially booted with nmi_watchdog parameter. 53 */ 54 if (cpu == crashing_cpu) 55 return NOTIFY_STOP; 56 local_irq_disable(); 57 58 if (!user_mode_vm(regs)) { 59 crash_fixup_ss_esp(&fixed_regs, regs); 60 regs = &fixed_regs; 61 } 62 crash_save_cpu(regs, cpu); 63 disable_local_APIC(); 64 atomic_dec(&waiting_for_crash_ipi); 65 /* Assume hlt works */ 66 halt(); 67 for (;;) 68 cpu_relax(); 69 70 return 1; 71} 72 73static void smp_send_nmi_allbutself(void) 74{ 75 cpumask_t mask = cpu_online_map; 76 cpu_clear(safe_smp_processor_id(), mask); 77 if (!cpus_empty(mask)) 78 send_IPI_mask(mask, NMI_VECTOR); 79} 80 81static struct notifier_block crash_nmi_nb = { 82 .notifier_call = crash_nmi_callback, 83}; 84 85static void nmi_shootdown_cpus(void) 86{ 87 unsigned long msecs; 88 89 atomic_set(&waiting_for_crash_ipi, num_online_cpus() - 1); 90 /* Would it be better to replace the trap vector here? */ 91 if (register_die_notifier(&crash_nmi_nb)) 92 return; /* return what? */ 93 /* Ensure the new callback function is set before sending 94 * out the NMI 95 */ 96 wmb(); 97 98 smp_send_nmi_allbutself(); 99 100 msecs = 1000; /* Wait at most a second for the other cpus to stop */ 101 while ((atomic_read(&waiting_for_crash_ipi) > 0) && msecs) { 102 mdelay(1); 103 msecs--; 104 } 105 106 /* Leave the nmi callback set */ 107 disable_local_APIC(); 108} 109#else 110static void nmi_shootdown_cpus(void) 111{ 112 /* There are no cpus to shootdown */ 113} 114#endif 115 116void machine_crash_shutdown(struct pt_regs *regs) 117{ 118 /* This function is only called after the system 119 * has panicked or is otherwise in a critical state. 120 * The minimum amount of code to allow a kexec'd kernel 121 * to run successfully needs to happen here. 122 * 123 * In practice this means shooting down the other cpus in 124 * an SMP system. 125 */ 126 /* The kernel is broken so disable interrupts */ 127 local_irq_disable(); 128 129 /* Make a note of crashing cpu. Will be used in NMI callback.*/ 130 crashing_cpu = safe_smp_processor_id(); 131 nmi_shootdown_cpus(); 132 lapic_shutdown(); 133#if defined(CONFIG_X86_IO_APIC) 134 disable_IO_APIC(); 135#endif 136 crash_save_cpu(regs, safe_smp_processor_id()); 137} 138