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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. */
inject_mce(struct mce * m)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 
raise_poll(struct mce * m)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 
raise_exception(struct mce * m,struct pt_regs * pregs)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 
mce_raise_notify(unsigned int cmd,struct pt_regs * regs)82 static int mce_raise_notify(unsigned int cmd, struct pt_regs *regs)
83 {
84 	int cpu = smp_processor_id();
85 	struct mce *m = &__get_cpu_var(injectm);
86 	if (!cpumask_test_cpu(cpu, mce_inject_cpumask))
87 		return NMI_DONE;
88 	cpumask_clear_cpu(cpu, mce_inject_cpumask);
89 	if (m->inject_flags & MCJ_EXCEPTION)
90 		raise_exception(m, regs);
91 	else if (m->status)
92 		raise_poll(m);
93 	return NMI_HANDLED;
94 }
95 
mce_irq_ipi(void * info)96 static void mce_irq_ipi(void *info)
97 {
98 	int cpu = smp_processor_id();
99 	struct mce *m = &__get_cpu_var(injectm);
100 
101 	if (cpumask_test_cpu(cpu, mce_inject_cpumask) &&
102 			m->inject_flags & MCJ_EXCEPTION) {
103 		cpumask_clear_cpu(cpu, mce_inject_cpumask);
104 		raise_exception(m, NULL);
105 	}
106 }
107 
108 /* Inject mce on current CPU */
raise_local(void)109 static int raise_local(void)
110 {
111 	struct mce *m = &__get_cpu_var(injectm);
112 	int context = MCJ_CTX(m->inject_flags);
113 	int ret = 0;
114 	int cpu = m->extcpu;
115 
116 	if (m->inject_flags & MCJ_EXCEPTION) {
117 		printk(KERN_INFO "Triggering MCE exception on CPU %d\n", cpu);
118 		switch (context) {
119 		case MCJ_CTX_IRQ:
120 			/*
121 			 * Could do more to fake interrupts like
122 			 * calling irq_enter, but the necessary
123 			 * machinery isn't exported currently.
124 			 */
125 			/*FALL THROUGH*/
126 		case MCJ_CTX_PROCESS:
127 			raise_exception(m, NULL);
128 			break;
129 		default:
130 			printk(KERN_INFO "Invalid MCE context\n");
131 			ret = -EINVAL;
132 		}
133 		printk(KERN_INFO "MCE exception done on CPU %d\n", cpu);
134 	} else if (m->status) {
135 		printk(KERN_INFO "Starting machine check poll CPU %d\n", cpu);
136 		raise_poll(m);
137 		mce_notify_irq();
138 		printk(KERN_INFO "Machine check poll done on CPU %d\n", cpu);
139 	} else
140 		m->finished = 0;
141 
142 	return ret;
143 }
144 
raise_mce(struct mce * m)145 static void raise_mce(struct mce *m)
146 {
147 	int context = MCJ_CTX(m->inject_flags);
148 
149 	inject_mce(m);
150 
151 	if (context == MCJ_CTX_RANDOM)
152 		return;
153 
154 #ifdef CONFIG_X86_LOCAL_APIC
155 	if (m->inject_flags & (MCJ_IRQ_BRAODCAST | 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_BRAODCAST) {
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 				printk(KERN_ERR
186 				"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 		raise_local();
198 }
199 
200 /* Error injection interface */
mce_write(struct file * filp,const char __user * ubuf,size_t usize,loff_t * off)201 static ssize_t mce_write(struct file *filp, const char __user *ubuf,
202 			 size_t usize, loff_t *off)
203 {
204 	struct mce m;
205 
206 	if (!capable(CAP_SYS_ADMIN))
207 		return -EPERM;
208 	/*
209 	 * There are some cases where real MSR reads could slip
210 	 * through.
211 	 */
212 	if (!boot_cpu_has(X86_FEATURE_MCE) || !boot_cpu_has(X86_FEATURE_MCA))
213 		return -EIO;
214 
215 	if ((unsigned long)usize > sizeof(struct mce))
216 		usize = sizeof(struct mce);
217 	if (copy_from_user(&m, ubuf, usize))
218 		return -EFAULT;
219 
220 	if (m.extcpu >= num_possible_cpus() || !cpu_online(m.extcpu))
221 		return -EINVAL;
222 
223 	/*
224 	 * Need to give user space some time to set everything up,
225 	 * so do it a jiffie or two later everywhere.
226 	 */
227 	schedule_timeout(2);
228 	raise_mce(&m);
229 	return usize;
230 }
231 
inject_init(void)232 static int inject_init(void)
233 {
234 	if (!alloc_cpumask_var(&mce_inject_cpumask, GFP_KERNEL))
235 		return -ENOMEM;
236 	printk(KERN_INFO "Machine check injector initialized\n");
237 	register_mce_write_callback(mce_write);
238 	register_nmi_handler(NMI_LOCAL, mce_raise_notify, 0,
239 				"mce_notify");
240 	return 0;
241 }
242 
243 module_init(inject_init);
244 /*
245  * Cannot tolerate unloading currently because we cannot
246  * guarantee all openers of mce_chrdev will get a reference to us.
247  */
248 MODULE_LICENSE("GPL");
249