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 <linux/kdebug.h> 26 #include <asm/smp.h> 27 28 #ifdef CONFIG_X86_32 29 #include <mach_ipi.h> 30 #else 31 #include <asm/mach_apic.h> 32 #endif 33 34 /* This keeps a track of which one is crashing cpu. */ 35 static int crashing_cpu; 36 37 #if defined(CONFIG_SMP) && defined(CONFIG_X86_LOCAL_APIC) 38 static atomic_t waiting_for_crash_ipi; 39 40 static int crash_nmi_callback(struct notifier_block *self, 41 unsigned long val, void *data) 42 { 43 struct pt_regs *regs; 44 #ifdef CONFIG_X86_32 45 struct pt_regs fixed_regs; 46 #endif 47 int cpu; 48 49 if (val != DIE_NMI_IPI) 50 return NOTIFY_OK; 51 52 regs = ((struct die_args *)data)->regs; 53 cpu = raw_smp_processor_id(); 54 55 /* Don't do anything if this handler is invoked on crashing cpu. 56 * Otherwise, system will completely hang. Crashing cpu can get 57 * an NMI if system was initially booted with nmi_watchdog parameter. 58 */ 59 if (cpu == crashing_cpu) 60 return NOTIFY_STOP; 61 local_irq_disable(); 62 63 #ifdef CONFIG_X86_32 64 if (!user_mode_vm(regs)) { 65 crash_fixup_ss_esp(&fixed_regs, regs); 66 regs = &fixed_regs; 67 } 68 #endif 69 crash_save_cpu(regs, cpu); 70 disable_local_APIC(); 71 atomic_dec(&waiting_for_crash_ipi); 72 /* Assume hlt works */ 73 halt(); 74 for (;;) 75 cpu_relax(); 76 77 return 1; 78 } 79 80 static void smp_send_nmi_allbutself(void) 81 { 82 cpumask_t mask = cpu_online_map; 83 cpu_clear(safe_smp_processor_id(), mask); 84 if (!cpus_empty(mask)) 85 send_IPI_mask(mask, NMI_VECTOR); 86 } 87 88 static struct notifier_block crash_nmi_nb = { 89 .notifier_call = crash_nmi_callback, 90 }; 91 92 static void nmi_shootdown_cpus(void) 93 { 94 unsigned long msecs; 95 96 atomic_set(&waiting_for_crash_ipi, num_online_cpus() - 1); 97 /* Would it be better to replace the trap vector here? */ 98 if (register_die_notifier(&crash_nmi_nb)) 99 return; /* return what? */ 100 /* Ensure the new callback function is set before sending 101 * out the NMI 102 */ 103 wmb(); 104 105 smp_send_nmi_allbutself(); 106 107 msecs = 1000; /* Wait at most a second for the other cpus to stop */ 108 while ((atomic_read(&waiting_for_crash_ipi) > 0) && msecs) { 109 mdelay(1); 110 msecs--; 111 } 112 113 /* Leave the nmi callback set */ 114 disable_local_APIC(); 115 } 116 #else 117 static void nmi_shootdown_cpus(void) 118 { 119 /* There are no cpus to shootdown */ 120 } 121 #endif 122 123 void machine_crash_shutdown(struct pt_regs *regs) 124 { 125 /* This function is only called after the system 126 * has panicked or is otherwise in a critical state. 127 * The minimum amount of code to allow a kexec'd kernel 128 * to run successfully needs to happen here. 129 * 130 * In practice this means shooting down the other cpus in 131 * an SMP system. 132 */ 133 /* The kernel is broken so disable interrupts */ 134 local_irq_disable(); 135 136 /* Make a note of crashing cpu. Will be used in NMI callback.*/ 137 crashing_cpu = safe_smp_processor_id(); 138 nmi_shootdown_cpus(); 139 lapic_shutdown(); 140 #if defined(CONFIG_X86_IO_APIC) 141 disable_IO_APIC(); 142 #endif 143 crash_save_cpu(regs, safe_smp_processor_id()); 144 } 145