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1 /*
2  * MCE grading rules.
3  * Copyright 2008, 2009 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  * Author: Andi Kleen
11  */
12 #include <linux/kernel.h>
13 #include <linux/seq_file.h>
14 #include <linux/init.h>
15 #include <linux/debugfs.h>
16 #include <asm/mce.h>
17 
18 #include "mce-internal.h"
19 
20 /*
21  * Grade an mce by severity. In general the most severe ones are processed
22  * first. Since there are quite a lot of combinations test the bits in a
23  * table-driven way. The rules are simply processed in order, first
24  * match wins.
25  *
26  * Note this is only used for machine check exceptions, the corrected
27  * errors use much simpler rules. The exceptions still check for the corrected
28  * errors, but only to leave them alone for the CMCI handler (except for
29  * panic situations)
30  */
31 
32 enum context { IN_KERNEL = 1, IN_USER = 2 };
33 enum ser { SER_REQUIRED = 1, NO_SER = 2 };
34 enum exception { EXCP_CONTEXT = 1, NO_EXCP = 2 };
35 
36 static struct severity {
37 	u64 mask;
38 	u64 result;
39 	unsigned char sev;
40 	unsigned char mcgmask;
41 	unsigned char mcgres;
42 	unsigned char ser;
43 	unsigned char context;
44 	unsigned char excp;
45 	unsigned char covered;
46 	char *msg;
47 } severities[] = {
48 #define MCESEV(s, m, c...) { .sev = MCE_ ## s ## _SEVERITY, .msg = m, ## c }
49 #define  KERNEL		.context = IN_KERNEL
50 #define  USER		.context = IN_USER
51 #define  SER		.ser = SER_REQUIRED
52 #define  NOSER		.ser = NO_SER
53 #define  EXCP		.excp = EXCP_CONTEXT
54 #define  NOEXCP		.excp = NO_EXCP
55 #define  BITCLR(x)	.mask = x, .result = 0
56 #define  BITSET(x)	.mask = x, .result = x
57 #define  MCGMASK(x, y)	.mcgmask = x, .mcgres = y
58 #define  MASK(x, y)	.mask = x, .result = y
59 #define MCI_UC_S (MCI_STATUS_UC|MCI_STATUS_S)
60 #define MCI_UC_SAR (MCI_STATUS_UC|MCI_STATUS_S|MCI_STATUS_AR)
61 #define	MCI_ADDR (MCI_STATUS_ADDRV|MCI_STATUS_MISCV)
62 
63 	MCESEV(
64 		NO, "Invalid",
65 		BITCLR(MCI_STATUS_VAL)
66 		),
67 	MCESEV(
68 		NO, "Not enabled",
69 		EXCP, BITCLR(MCI_STATUS_EN)
70 		),
71 	MCESEV(
72 		PANIC, "Processor context corrupt",
73 		BITSET(MCI_STATUS_PCC)
74 		),
75 	/* When MCIP is not set something is very confused */
76 	MCESEV(
77 		PANIC, "MCIP not set in MCA handler",
78 		EXCP, MCGMASK(MCG_STATUS_MCIP, 0)
79 		),
80 	/* Neither return not error IP -- no chance to recover -> PANIC */
81 	MCESEV(
82 		PANIC, "Neither restart nor error IP",
83 		EXCP, MCGMASK(MCG_STATUS_RIPV|MCG_STATUS_EIPV, 0)
84 		),
85 	MCESEV(
86 		PANIC, "In kernel and no restart IP",
87 		EXCP, KERNEL, MCGMASK(MCG_STATUS_RIPV, 0)
88 		),
89 	MCESEV(
90 		DEFERRED, "Deferred error",
91 		NOSER, MASK(MCI_STATUS_UC|MCI_STATUS_DEFERRED|MCI_STATUS_POISON, MCI_STATUS_DEFERRED)
92 		),
93 	MCESEV(
94 		KEEP, "Corrected error",
95 		NOSER, BITCLR(MCI_STATUS_UC)
96 		),
97 
98 	/* ignore OVER for UCNA */
99 	MCESEV(
100 		UCNA, "Uncorrected no action required",
101 		SER, MASK(MCI_UC_SAR, MCI_STATUS_UC)
102 		),
103 	MCESEV(
104 		PANIC, "Illegal combination (UCNA with AR=1)",
105 		SER,
106 		MASK(MCI_STATUS_OVER|MCI_UC_SAR, MCI_STATUS_UC|MCI_STATUS_AR)
107 		),
108 	MCESEV(
109 		KEEP, "Non signalled machine check",
110 		SER, BITCLR(MCI_STATUS_S)
111 		),
112 
113 	MCESEV(
114 		PANIC, "Action required with lost events",
115 		SER, BITSET(MCI_STATUS_OVER|MCI_UC_SAR)
116 		),
117 
118 	/* known AR MCACODs: */
119 #ifdef	CONFIG_MEMORY_FAILURE
120 	MCESEV(
121 		KEEP, "Action required but unaffected thread is continuable",
122 		SER, MASK(MCI_STATUS_OVER|MCI_UC_SAR|MCI_ADDR, MCI_UC_SAR|MCI_ADDR),
123 		MCGMASK(MCG_STATUS_RIPV|MCG_STATUS_EIPV, MCG_STATUS_RIPV)
124 		),
125 	MCESEV(
126 		AR, "Action required: data load error in a user process",
127 		SER, MASK(MCI_STATUS_OVER|MCI_UC_SAR|MCI_ADDR|MCACOD, MCI_UC_SAR|MCI_ADDR|MCACOD_DATA),
128 		USER
129 		),
130 	MCESEV(
131 		AR, "Action required: instruction fetch error in a user process",
132 		SER, MASK(MCI_STATUS_OVER|MCI_UC_SAR|MCI_ADDR|MCACOD, MCI_UC_SAR|MCI_ADDR|MCACOD_INSTR),
133 		USER
134 		),
135 #endif
136 	MCESEV(
137 		PANIC, "Action required: unknown MCACOD",
138 		SER, MASK(MCI_STATUS_OVER|MCI_UC_SAR, MCI_UC_SAR)
139 		),
140 
141 	/* known AO MCACODs: */
142 	MCESEV(
143 		AO, "Action optional: memory scrubbing error",
144 		SER, MASK(MCI_STATUS_OVER|MCI_UC_SAR|MCACOD_SCRUBMSK, MCI_UC_S|MCACOD_SCRUB)
145 		),
146 	MCESEV(
147 		AO, "Action optional: last level cache writeback error",
148 		SER, MASK(MCI_STATUS_OVER|MCI_UC_SAR|MCACOD, MCI_UC_S|MCACOD_L3WB)
149 		),
150 	MCESEV(
151 		SOME, "Action optional: unknown MCACOD",
152 		SER, MASK(MCI_STATUS_OVER|MCI_UC_SAR, MCI_UC_S)
153 		),
154 	MCESEV(
155 		SOME, "Action optional with lost events",
156 		SER, MASK(MCI_STATUS_OVER|MCI_UC_SAR, MCI_STATUS_OVER|MCI_UC_S)
157 		),
158 
159 	MCESEV(
160 		PANIC, "Overflowed uncorrected",
161 		BITSET(MCI_STATUS_OVER|MCI_STATUS_UC)
162 		),
163 	MCESEV(
164 		UC, "Uncorrected",
165 		BITSET(MCI_STATUS_UC)
166 		),
167 	MCESEV(
168 		SOME, "No match",
169 		BITSET(0)
170 		)	/* always matches. keep at end */
171 };
172 
173 /*
174  * If mcgstatus indicated that ip/cs on the stack were
175  * no good, then "m->cs" will be zero and we will have
176  * to assume the worst case (IN_KERNEL) as we actually
177  * have no idea what we were executing when the machine
178  * check hit.
179  * If we do have a good "m->cs" (or a faked one in the
180  * case we were executing in VM86 mode) we can use it to
181  * distinguish an exception taken in user from from one
182  * taken in the kernel.
183  */
error_context(struct mce * m)184 static int error_context(struct mce *m)
185 {
186 	return ((m->cs & 3) == 3) ? IN_USER : IN_KERNEL;
187 }
188 
mce_severity(struct mce * m,int tolerant,char ** msg,bool is_excp)189 int mce_severity(struct mce *m, int tolerant, char **msg, bool is_excp)
190 {
191 	enum exception excp = (is_excp ? EXCP_CONTEXT : NO_EXCP);
192 	enum context ctx = error_context(m);
193 	struct severity *s;
194 
195 	for (s = severities;; s++) {
196 		if ((m->status & s->mask) != s->result)
197 			continue;
198 		if ((m->mcgstatus & s->mcgmask) != s->mcgres)
199 			continue;
200 		if (s->ser == SER_REQUIRED && !mca_cfg.ser)
201 			continue;
202 		if (s->ser == NO_SER && mca_cfg.ser)
203 			continue;
204 		if (s->context && ctx != s->context)
205 			continue;
206 		if (s->excp && excp != s->excp)
207 			continue;
208 		if (msg)
209 			*msg = s->msg;
210 		s->covered = 1;
211 		if (s->sev >= MCE_UC_SEVERITY && ctx == IN_KERNEL) {
212 			if (panic_on_oops || tolerant < 1)
213 				return MCE_PANIC_SEVERITY;
214 		}
215 		return s->sev;
216 	}
217 }
218 
219 #ifdef CONFIG_DEBUG_FS
s_start(struct seq_file * f,loff_t * pos)220 static void *s_start(struct seq_file *f, loff_t *pos)
221 {
222 	if (*pos >= ARRAY_SIZE(severities))
223 		return NULL;
224 	return &severities[*pos];
225 }
226 
s_next(struct seq_file * f,void * data,loff_t * pos)227 static void *s_next(struct seq_file *f, void *data, loff_t *pos)
228 {
229 	if (++(*pos) >= ARRAY_SIZE(severities))
230 		return NULL;
231 	return &severities[*pos];
232 }
233 
s_stop(struct seq_file * f,void * data)234 static void s_stop(struct seq_file *f, void *data)
235 {
236 }
237 
s_show(struct seq_file * f,void * data)238 static int s_show(struct seq_file *f, void *data)
239 {
240 	struct severity *ser = data;
241 	seq_printf(f, "%d\t%s\n", ser->covered, ser->msg);
242 	return 0;
243 }
244 
245 static const struct seq_operations severities_seq_ops = {
246 	.start	= s_start,
247 	.next	= s_next,
248 	.stop	= s_stop,
249 	.show	= s_show,
250 };
251 
severities_coverage_open(struct inode * inode,struct file * file)252 static int severities_coverage_open(struct inode *inode, struct file *file)
253 {
254 	return seq_open(file, &severities_seq_ops);
255 }
256 
severities_coverage_write(struct file * file,const char __user * ubuf,size_t count,loff_t * ppos)257 static ssize_t severities_coverage_write(struct file *file,
258 					 const char __user *ubuf,
259 					 size_t count, loff_t *ppos)
260 {
261 	int i;
262 	for (i = 0; i < ARRAY_SIZE(severities); i++)
263 		severities[i].covered = 0;
264 	return count;
265 }
266 
267 static const struct file_operations severities_coverage_fops = {
268 	.open		= severities_coverage_open,
269 	.release	= seq_release,
270 	.read		= seq_read,
271 	.write		= severities_coverage_write,
272 	.llseek		= seq_lseek,
273 };
274 
severities_debugfs_init(void)275 static int __init severities_debugfs_init(void)
276 {
277 	struct dentry *dmce, *fsev;
278 
279 	dmce = mce_get_debugfs_dir();
280 	if (!dmce)
281 		goto err_out;
282 
283 	fsev = debugfs_create_file("severities-coverage", 0444, dmce, NULL,
284 				   &severities_coverage_fops);
285 	if (!fsev)
286 		goto err_out;
287 
288 	return 0;
289 
290 err_out:
291 	return -ENOMEM;
292 }
293 late_initcall(severities_debugfs_init);
294 #endif /* CONFIG_DEBUG_FS */
295