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

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  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 #ifdef CONFIG_X86_LOCAL_APIC
156         if (m->inject_flags & (MCJ_IRQ_BROADCAST | MCJ_NMI_BROADCAST)) {
157                 unsigned long start;
158                 int cpu;
159 
160                 get_online_cpus();
161                 cpumask_copy(mce_inject_cpumask, cpu_online_mask);
162                 cpumask_clear_cpu(get_cpu(), mce_inject_cpumask);
163                 for_each_online_cpu(cpu) {
164                         struct mce *mcpu = &per_cpu(injectm, cpu);
165                         if (!mcpu->finished ||
166                             MCJ_CTX(mcpu->inject_flags) != MCJ_CTX_RANDOM)
167                                 cpumask_clear_cpu(cpu, mce_inject_cpumask);
168                 }
169                 if (!cpumask_empty(mce_inject_cpumask)) {
170                         if (m->inject_flags & MCJ_IRQ_BROADCAST) {
171                                 /*
172                                  * don't wait because mce_irq_ipi is necessary
173                                  * to be sync with following raise_local
174                                  */
175                                 preempt_disable();
176                                 smp_call_function_many(mce_inject_cpumask,
177                                         mce_irq_ipi, NULL, 0);
178                                 preempt_enable();
179                         } else if (m->inject_flags & MCJ_NMI_BROADCAST)
180                                 apic->send_IPI_mask(mce_inject_cpumask,
181                                                 NMI_VECTOR);
182                 }
183                 start = jiffies;
184                 while (!cpumask_empty(mce_inject_cpumask)) {
185                         if (!time_before(jiffies, start + 2*HZ)) {
186                                 pr_err("Timeout waiting for mce inject %lx\n",
187                                         *cpumask_bits(mce_inject_cpumask));
188                                 break;
189                         }
190                         cpu_relax();
191                 }
192                 raise_local();
193                 put_cpu();
194                 put_online_cpus();
195         } else
196 #endif
197         {
198                 preempt_disable();
199                 raise_local();
200                 preempt_enable();
201         }
202 }
203 
204 /* Error injection interface */
205 static ssize_t mce_write(struct file *filp, const char __user *ubuf,
206                          size_t usize, loff_t *off)
207 {
208         struct mce m;
209 
210         if (!capable(CAP_SYS_ADMIN))
211                 return -EPERM;
212         /*
213          * There are some cases where real MSR reads could slip
214          * through.
215          */
216         if (!boot_cpu_has(X86_FEATURE_MCE) || !boot_cpu_has(X86_FEATURE_MCA))
217                 return -EIO;
218 
219         if ((unsigned long)usize > sizeof(struct mce))
220                 usize = sizeof(struct mce);
221         if (copy_from_user(&m, ubuf, usize))
222                 return -EFAULT;
223 
224         if (m.extcpu >= num_possible_cpus() || !cpu_online(m.extcpu))
225                 return -EINVAL;
226 
227         /*
228          * Need to give user space some time to set everything up,
229          * so do it a jiffie or two later everywhere.
230          */
231         schedule_timeout(2);
232 
233         mutex_lock(&mce_inject_mutex);
234         raise_mce(&m);
235         mutex_unlock(&mce_inject_mutex);
236         return usize;
237 }
238 
239 static int inject_init(void)
240 {
241         if (!alloc_cpumask_var(&mce_inject_cpumask, GFP_KERNEL))
242                 return -ENOMEM;
243         pr_info("Machine check injector initialized\n");
244         register_mce_write_callback(mce_write);
245         register_nmi_handler(NMI_LOCAL, mce_raise_notify, 0,
246                                 "mce_notify");
247         return 0;
248 }
249 
250 module_init(inject_init);
251 /*
252  * Cannot tolerate unloading currently because we cannot
253  * guarantee all openers of mce_chrdev will get a reference to us.
254  */
255 MODULE_LICENSE("GPL");
256 

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