arch/x86/kernel/cpu/mcheck/mce-inject.c

   1 /*
   2  * Machine check injection support.
   3  * Copyright 2008 Intel Corporation.
   4  *
   5  * This program is free software; you can redistribute it and/or
   6  * modify it under the terms of the GNU General Public License
   7  * as published by the Free Software Foundation; version 2
   8  * of the License.
   9  *
  10  * Authors:
  11  * Andi Kleen
  12  * Ying Huang
  13  */
  14 #include <linux/uaccess.h>
  15 #include <linux/module.h>
  16 #include <linux/timer.h>
  17 #include <linux/kernel.h>
  18 #include <linux/string.h>
  19 #include <linux/fs.h>
  20 #include <linux/smp.h>
  21 #include <linux/notifier.h>
  22 #include <linux/kdebug.h>
  23 #include <linux/cpu.h>
  24 #include <linux/sched.h>
  25 #include <linux/gfp.h>
  26 #include <asm/mce.h>
  27 #include <asm/apic.h>
  28
  29 /* Update fake mce registers on current CPU. */
  30 static void inject_mce(struct mce *m)
  31 {
  32         struct mce *i = &per_cpu(injectm, m->extcpu);
  33
  34         /* Make sure noone reads partially written injectm */
  35         i->finished = 0;
  36         mb();
  37         m->finished = 0;
  38         /* First set the fields after finished */
  39         i->extcpu = m->extcpu;
  40         mb();
  41         /* Now write record in order, finished last (except above) */
  42         memcpy(i, m, sizeof(struct mce));
  43         /* Finally activate it */
  44         mb();
  45         i->finished = 1;
  46 }
  47
  48 static void raise_poll(struct mce *m)
  49 {
  50         unsigned long flags;
  51         mce_banks_t b;
  52
  53         memset(&b, 0xff, sizeof(mce_banks_t));
  54         local_irq_save(flags);
  55         machine_check_poll(0, &b);
  56         local_irq_restore(flags);
  57         m->finished = 0;
  58 }
  59
  60 static void raise_exception(struct mce *m, struct pt_regs *pregs)
  61 {
  62         struct pt_regs regs;
  63         unsigned long flags;
  64
  65         if (!pregs) {
  66                 memset(&regs, 0, sizeof(struct pt_regs));
  67                 regs.ip = m->ip;
  68                 regs.cs = m->cs;
  69                 pregs = &regs;
  70         }
  71         /* in mcheck exeception handler, irq will be disabled */
  72         local_irq_save(flags);
  73         do_machine_check(pregs, 0);
  74         local_irq_restore(flags);
  75         m->finished = 0;
  76 }
  77
  78 static cpumask_var_t mce_inject_cpumask;
  79
  80 static int mce_raise_notify(struct notifier_block *self,
  81                             unsigned long val, void *data)
  82 {
  83         struct die_args *args = (struct die_args *)data;
  84         int cpu = smp_processor_id();
  85         struct mce *m = &__get_cpu_var(injectm);
  86         if (val != DIE_NMI_IPI || !cpumask_test_cpu(cpu, mce_inject_cpumask))
  87                 return NOTIFY_DONE;
  88         cpumask_clear_cpu(cpu, mce_inject_cpumask);
  89         if (m->inject_flags & MCJ_EXCEPTION)
  90                 raise_exception(m, args->regs);
  91         else if (m->status)
  92                 raise_poll(m);
  93         return NOTIFY_STOP;
  94 }
  95
  96 static struct notifier_block mce_raise_nb = {
  97         .notifier_call = mce_raise_notify,
  98         .priority = 1000,
  99 };
 100
 101 /* Inject mce on current CPU */
 102 static int raise_local(void)
 103 {
 104         struct mce *m = &__get_cpu_var(injectm);
 105         int context = MCJ_CTX(m->inject_flags);
 106         int ret = 0;
 107         int cpu = m->extcpu;
 108
 109         if (m->inject_flags & MCJ_EXCEPTION) {
 110                 printk(KERN_INFO "Triggering MCE exception on CPU %d\n", cpu);
 111                 switch (context) {
 112                 case MCJ_CTX_IRQ:
 113                         /*
 114                          * Could do more to fake interrupts like
 115                          * calling irq_enter, but the necessary
 116                          * machinery isn't exported currently.
 117                          */
 118                         /*FALL THROUGH*/
 119                 case MCJ_CTX_PROCESS:
 120                         raise_exception(m, NULL);
 121                         break;
 122                 default:
 123                         printk(KERN_INFO "Invalid MCE context\n");
 124                         ret = -EINVAL;
 125                 }
 126                 printk(KERN_INFO "MCE exception done on CPU %d\n", cpu);
 127         } else if (m->status) {
 128                 printk(KERN_INFO "Starting machine check poll CPU %d\n", cpu);
 129                 raise_poll(m);
 130                 mce_notify_irq();
 131                 printk(KERN_INFO "Machine check poll done on CPU %d\n", cpu);
 132         } else
 133                 m->finished = 0;
 134
 135         return ret;
 136 }
 137
 138 static void raise_mce(struct mce *m)
 139 {
 140         int context = MCJ_CTX(m->inject_flags);
 141
 142         inject_mce(m);
 143
 144         if (context == MCJ_CTX_RANDOM)
 145                 return;
 146
 147 #ifdef CONFIG_X86_LOCAL_APIC
 148         if (m->inject_flags & MCJ_NMI_BROADCAST) {
 149                 unsigned long start;
 150                 int cpu;
 151                 get_online_cpus();
 152                 cpumask_copy(mce_inject_cpumask, cpu_online_mask);
 153                 cpumask_clear_cpu(get_cpu(), mce_inject_cpumask);
 154                 for_each_online_cpu(cpu) {
 155                         struct mce *mcpu = &per_cpu(injectm, cpu);
 156                         if (!mcpu->finished ||
 157                             MCJ_CTX(mcpu->inject_flags) != MCJ_CTX_RANDOM)
 158                                 cpumask_clear_cpu(cpu, mce_inject_cpumask);
 159                 }
 160                 if (!cpumask_empty(mce_inject_cpumask))
 161                         apic->send_IPI_mask(mce_inject_cpumask, NMI_VECTOR);
 162                 start = jiffies;
 163                 while (!cpumask_empty(mce_inject_cpumask)) {
 164                         if (!time_before(jiffies, start + 2*HZ)) {
 165                                 printk(KERN_ERR
 166                                 "Timeout waiting for mce inject NMI %lx\n",
 167                                         *cpumask_bits(mce_inject_cpumask));
 168                                 break;
 169                         }
 170                         cpu_relax();
 171                 }
 172                 raise_local();
 173                 put_cpu();
 174                 put_online_cpus();
 175         } else
 176 #endif
 177                 raise_local();
 178 }
 179
 180 /* Error injection interface */
 181 static ssize_t mce_write(struct file *filp, const char __user *ubuf,
 182                          size_t usize, loff_t *off)
 183 {
 184         struct mce m;
 185
 186         if (!capable(CAP_SYS_ADMIN))
 187                 return -EPERM;
 188         /*
 189          * There are some cases where real MSR reads could slip
 190          * through.
 191          */
 192         if (!boot_cpu_has(X86_FEATURE_MCE) || !boot_cpu_has(X86_FEATURE_MCA))
 193                 return -EIO;
 194
 195         if ((unsigned long)usize > sizeof(struct mce))
 196                 usize = sizeof(struct mce);
 197         if (copy_from_user(&m, ubuf, usize))
 198                 return -EFAULT;
 199
 200         if (m.extcpu >= num_possible_cpus() || !cpu_online(m.extcpu))
 201                 return -EINVAL;
 202
 203         /*
 204          * Need to give user space some time to set everything up,
 205          * so do it a jiffie or two later everywhere.
 206          */
 207         schedule_timeout(2);
 208         raise_mce(&m);
 209         return usize;
 210 }
 211
 212 static int inject_init(void)
 213 {
 214         if (!alloc_cpumask_var(&mce_inject_cpumask, GFP_KERNEL))
 215                 return -ENOMEM;
 216         printk(KERN_INFO "Machine check injector initialized\n");
 217         mce_chrdev_ops.write = mce_write;
 218         register_die_notifier(&mce_raise_nb);
 219         return 0;
 220 }
 221
 222 module_init(inject_init);
 223 /*
 224  * Cannot tolerate unloading currently because we cannot
 225  * guarantee all openers of mce_chrdev will get a reference to us.
 226  */
 227 MODULE_LICENSE("GPL");