/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. */
 30static 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
 48static 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
 60static 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
 78static cpumask_var_t mce_inject_cpumask;
 79
 80static 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
 96static struct notifier_block mce_raise_nb = {
 97	.notifier_call = mce_raise_notify,
 98	.priority = 1000,
 99};
100
101/* Inject mce on current CPU */
102static 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
138static 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 */
181static 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
212static 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
222module_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 */
227MODULE_LICENSE("GPL");