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/preempt.h>
  21 #include <linux/smp.h>
  22 #include <linux/notifier.h>
  23 #include <linux/kdebug.h>
  24 #include <linux/cpu.h>
  25 #include <linux/sched.h>
  26 #include <linux/gfp.h>
  27 #include <asm/mce.h>
  28 #include <asm/apic.h>
  29 #include <asm/nmi.h>
  30
  31 /* Update fake mce registers on current CPU. */
  32 static void inject_mce(struct mce *m)
  33 {
  34         struct mce *i = &per_cpu(injectm, m->extcpu);
  35
  36         /* Make sure no one reads partially written injectm */
  37         i->finished = 0;
  38         mb();
  39         m->finished = 0;
  40         /* First set the fields after finished */
  41         i->extcpu = m->extcpu;
  42         mb();
  43         /* Now write record in order, finished last (except above) */
  44         memcpy(i, m, sizeof(struct mce));
  45         /* Finally activate it */
  46         mb();
  47         i->finished = 1;
  48 }
  49
  50 static void raise_poll(struct mce *m)
  51 {
  52         unsigned long flags;
  53         mce_banks_t b;
  54
  55         memset(&b, 0xff, sizeof(mce_banks_t));
  56         local_irq_save(flags);
  57         machine_check_poll(0, &b);
  58         local_irq_restore(flags);
  59         m->finished = 0;
  60 }
  61
  62 static void raise_exception(struct mce *m, struct pt_regs *pregs)
  63 {
  64         struct pt_regs regs;
  65         unsigned long flags;
  66
  67         if (!pregs) {
  68                 memset(&regs, 0, sizeof(struct pt_regs));
  69                 regs.ip = m->ip;
  70                 regs.cs = m->cs;
  71                 pregs = &regs;
  72         }
  73         /* in mcheck exeception handler, irq will be disabled */
  74         local_irq_save(flags);
  75         do_machine_check(pregs, 0);
  76         local_irq_restore(flags);
  77         m->finished = 0;
  78 }
  79
  80 static cpumask_var_t mce_inject_cpumask;
  81 static DEFINE_MUTEX(mce_inject_mutex);
  82
  83 static int mce_raise_notify(unsigned int cmd, struct pt_regs *regs)
  84 {
  85         int cpu = smp_processor_id();
  86         struct mce *m = this_cpu_ptr(&injectm);
  87         if (!cpumask_test_cpu(cpu, mce_inject_cpumask))
  88                 return NMI_DONE;
  89         cpumask_clear_cpu(cpu, mce_inject_cpumask);
  90         if (m->inject_flags & MCJ_EXCEPTION)
  91                 raise_exception(m, regs);
  92         else if (m->status)
  93                 raise_poll(m);
  94         return NMI_HANDLED;
  95 }
  96
  97 static void mce_irq_ipi(void *info)
  98 {
  99         int cpu = smp_processor_id();
 100         struct mce *m = this_cpu_ptr(&injectm);
 101
 102         if (cpumask_test_cpu(cpu, mce_inject_cpumask) &&
 103                         m->inject_flags & MCJ_EXCEPTION) {
 104                 cpumask_clear_cpu(cpu, mce_inject_cpumask);
 105                 raise_exception(m, NULL);
 106         }
 107 }
 108
 109 /* Inject mce on current CPU */
 110 static int raise_local(void)
 111 {
 112         struct mce *m = this_cpu_ptr(&injectm);
 113         int context = MCJ_CTX(m->inject_flags);
 114         int ret = 0;
 115         int cpu = m->extcpu;
 116
 117         if (m->inject_flags & MCJ_EXCEPTION) {
 118                 pr_info("Triggering MCE exception on CPU %d\n", cpu);
 119                 switch (context) {
 120                 case MCJ_CTX_IRQ:
 121                         /*
 122                          * Could do more to fake interrupts like
 123                          * calling irq_enter, but the necessary
 124                          * machinery isn't exported currently.
 125                          */
 126                         /*FALL THROUGH*/
 127                 case MCJ_CTX_PROCESS:
 128                         raise_exception(m, NULL);
 129                         break;
 130                 default:
 131                         pr_info("Invalid MCE context\n");
 132                         ret = -EINVAL;
 133                 }
 134                 pr_info("MCE exception done on CPU %d\n", cpu);
 135         } else if (m->status) {
 136                 pr_info("Starting machine check poll CPU %d\n", cpu);
 137                 raise_poll(m);
 138                 mce_notify_irq();
 139                 pr_info("Machine check poll done on CPU %d\n", cpu);
 140         } else
 141                 m->finished = 0;
 142
 143         return ret;
 144 }
 145
 146 static void raise_mce(struct mce *m)
 147 {
 148         int context = MCJ_CTX(m->inject_flags);
 149
 150         inject_mce(m);
 151
 152         if (context == MCJ_CTX_RANDOM)
 153                 return;
 154
 155         if (m->inject_flags & (MCJ_IRQ_BROADCAST | MCJ_NMI_BROADCAST)) {
 156                 unsigned long start;
 157                 int cpu;
 158
 159                 get_online_cpus();
 160                 cpumask_copy(mce_inject_cpumask, cpu_online_mask);
 161                 cpumask_clear_cpu(get_cpu(), mce_inject_cpumask);
 162                 for_each_online_cpu(cpu) {
 163                         struct mce *mcpu = &per_cpu(injectm, cpu);
 164                         if (!mcpu->finished ||
 165                             MCJ_CTX(mcpu->inject_flags) != MCJ_CTX_RANDOM)
 166                                 cpumask_clear_cpu(cpu, mce_inject_cpumask);
 167                 }
 168                 if (!cpumask_empty(mce_inject_cpumask)) {
 169                         if (m->inject_flags & MCJ_IRQ_BROADCAST) {
 170                                 /*
 171                                  * don't wait because mce_irq_ipi is necessary
 172                                  * to be sync with following raise_local
 173                                  */
 174                                 preempt_disable();
 175                                 smp_call_function_many(mce_inject_cpumask,
 176                                         mce_irq_ipi, NULL, 0);
 177                                 preempt_enable();
 178                         } else if (m->inject_flags & MCJ_NMI_BROADCAST)
 179                                 apic->send_IPI_mask(mce_inject_cpumask,
 180                                                 NMI_VECTOR);
 181                 }
 182                 start = jiffies;
 183                 while (!cpumask_empty(mce_inject_cpumask)) {
 184                         if (!time_before(jiffies, start + 2*HZ)) {
 185                                 pr_err("Timeout waiting for mce inject %lx\n",
 186                                         *cpumask_bits(mce_inject_cpumask));
 187                                 break;
 188                         }
 189                         cpu_relax();
 190                 }
 191                 raise_local();
 192                 put_cpu();
 193                 put_online_cpus();
 194         } else {
 195                 preempt_disable();
 196                 raise_local();
 197                 preempt_enable();
 198         }
 199 }
 200
 201 /* Error injection interface */
 202 static ssize_t mce_write(struct file *filp, const char __user *ubuf,
 203                          size_t usize, loff_t *off)
 204 {
 205         struct mce m;
 206
 207         if (!capable(CAP_SYS_ADMIN))
 208                 return -EPERM;
 209         /*
 210          * There are some cases where real MSR reads could slip
 211          * through.
 212          */
 213         if (!boot_cpu_has(X86_FEATURE_MCE) || !boot_cpu_has(X86_FEATURE_MCA))
 214                 return -EIO;
 215
 216         if ((unsigned long)usize > sizeof(struct mce))
 217                 usize = sizeof(struct mce);
 218         if (copy_from_user(&m, ubuf, usize))
 219                 return -EFAULT;
 220
 221         if (m.extcpu >= num_possible_cpus() || !cpu_online(m.extcpu))
 222                 return -EINVAL;
 223
 224         /*
 225          * Need to give user space some time to set everything up,
 226          * so do it a jiffie or two later everywhere.
 227          */
 228         schedule_timeout(2);
 229
 230         mutex_lock(&mce_inject_mutex);
 231         raise_mce(&m);
 232         mutex_unlock(&mce_inject_mutex);
 233         return usize;
 234 }
 235
 236 static int inject_init(void)
 237 {
 238         if (!alloc_cpumask_var(&mce_inject_cpumask, GFP_KERNEL))
 239                 return -ENOMEM;
 240         pr_info("Machine check injector initialized\n");
 241         register_mce_write_callback(mce_write);
 242         register_nmi_handler(NMI_LOCAL, mce_raise_notify, 0,
 243                                 "mce_notify");
 244         return 0;
 245 }
 246
 247 module_init(inject_init);
 248 /*
 249  * Cannot tolerate unloading currently because we cannot
 250  * guarantee all openers of mce_chrdev will get a reference to us.
 251  */
 252 MODULE_LICENSE("GPL");