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
35 static struct severity {
36 u64 mask;
37 u64 result;
38 unsigned char sev;
39 unsigned char mcgmask;
40 unsigned char mcgres;
41 unsigned char ser;
42 unsigned char context;
43 unsigned char covered;
44 char *msg;
45 } severities[] = {
46 #define MCESEV(s, m, c...) { .sev = MCE_ ## s ## _SEVERITY, .msg = m, ## c }
47 #define KERNEL .context = IN_KERNEL
48 #define USER .context = IN_USER
49 #define SER .ser = SER_REQUIRED
50 #define NOSER .ser = NO_SER
51 #define BITCLR(x) .mask = x, .result = 0
52 #define BITSET(x) .mask = x, .result = x
53 #define MCGMASK(x, y) .mcgmask = x, .mcgres = y
54 #define MASK(x, y) .mask = x, .result = y
55 #define MCI_UC_S (MCI_STATUS_UC|MCI_STATUS_S)
56 #define MCI_UC_SAR (MCI_STATUS_UC|MCI_STATUS_S|MCI_STATUS_AR)
57 #define MCI_ADDR (MCI_STATUS_ADDRV|MCI_STATUS_MISCV)
58 #define MCACOD 0xffff
59 /* Architecturally defined codes from SDM Vol. 3B Chapter 15 */
60 #define MCACOD_SCRUB 0x00C0 /* 0xC0-0xCF Memory Scrubbing */
61 #define MCACOD_SCRUBMSK 0xfff0
62 #define MCACOD_L3WB 0x017A /* L3 Explicit Writeback */
63 #define MCACOD_DATA 0x0134 /* Data Load */
64 #define MCACOD_INSTR 0x0150 /* Instruction Fetch */
65
66 MCESEV(
67 NO, "Invalid",
68 BITCLR(MCI_STATUS_VAL)
69 ),
70 MCESEV(
71 NO, "Not enabled",
72 BITCLR(MCI_STATUS_EN)
73 ),
74 MCESEV(
75 PANIC, "Processor context corrupt",
76 BITSET(MCI_STATUS_PCC)
77 ),
78 /* When MCIP is not set something is very confused */
79 MCESEV(
80 PANIC, "MCIP not set in MCA handler",
81 MCGMASK(MCG_STATUS_MCIP, 0)
82 ),
83 /* Neither return not error IP -- no chance to recover -> PANIC */
84 MCESEV(
85 PANIC, "Neither restart nor error IP",
86 MCGMASK(MCG_STATUS_RIPV|MCG_STATUS_EIPV, 0)
87 ),
88 MCESEV(
89 PANIC, "In kernel and no restart IP",
90 KERNEL, MCGMASK(MCG_STATUS_RIPV, 0)
91 ),
92 MCESEV(
93 KEEP, "Corrected error",
94 NOSER, BITCLR(MCI_STATUS_UC)
95 ),
96
97 /* ignore OVER for UCNA */
98 MCESEV(
99 KEEP, "Uncorrected no action required",
100 SER, MASK(MCI_UC_SAR, MCI_STATUS_UC)
101 ),
102 MCESEV(
103 PANIC, "Illegal combination (UCNA with AR=1)",
104 SER,
105 MASK(MCI_STATUS_OVER|MCI_UC_SAR, MCI_STATUS_UC|MCI_STATUS_AR)
106 ),
107 MCESEV(
108 KEEP, "Non signalled machine check",
109 SER, BITCLR(MCI_STATUS_S)
110 ),
111
112 MCESEV(
113 PANIC, "Action required with lost events",
114 SER, BITSET(MCI_STATUS_OVER|MCI_UC_SAR)
115 ),
116
117 /* known AR MCACODs: */
118 #ifdef CONFIG_MEMORY_FAILURE
119 MCESEV(
120 KEEP, "HT thread notices Action required: data load error",
121 SER, MASK(MCI_STATUS_OVER|MCI_UC_SAR|MCI_ADDR|MCACOD, MCI_UC_SAR|MCI_ADDR|MCACOD_DATA),
122 MCGMASK(MCG_STATUS_EIPV, 0)
123 ),
124 MCESEV(
125 AR, "Action required: data load error",
126 SER, MASK(MCI_STATUS_OVER|MCI_UC_SAR|MCI_ADDR|MCACOD, MCI_UC_SAR|MCI_ADDR|MCACOD_DATA),
127 USER
128 ),
129 #endif
130 MCESEV(
131 PANIC, "Action required: unknown MCACOD",
132 SER, MASK(MCI_STATUS_OVER|MCI_UC_SAR, MCI_UC_SAR)
133 ),
134
135 /* known AO MCACODs: */
136 MCESEV(
137 AO, "Action optional: memory scrubbing error",
138 SER, MASK(MCI_STATUS_OVER|MCI_UC_SAR|MCACOD_SCRUBMSK, MCI_UC_S|MCACOD_SCRUB)
139 ),
140 MCESEV(
141 AO, "Action optional: last level cache writeback error",
142 SER, MASK(MCI_STATUS_OVER|MCI_UC_SAR|MCACOD, MCI_UC_S|MCACOD_L3WB)
143 ),
144 MCESEV(
145 SOME, "Action optional: unknown MCACOD",
146 SER, MASK(MCI_STATUS_OVER|MCI_UC_SAR, MCI_UC_S)
147 ),
148 MCESEV(
149 SOME, "Action optional with lost events",
150 SER, MASK(MCI_STATUS_OVER|MCI_UC_SAR, MCI_STATUS_OVER|MCI_UC_S)
151 ),
152
153 MCESEV(
154 PANIC, "Overflowed uncorrected",
155 BITSET(MCI_STATUS_OVER|MCI_STATUS_UC)
156 ),
157 MCESEV(
158 UC, "Uncorrected",
159 BITSET(MCI_STATUS_UC)
160 ),
161 MCESEV(
162 SOME, "No match",
163 BITSET(0)
164 ) /* always matches. keep at end */
165 };
166
167 /*
168 * If mcgstatus indicated that ip/cs on the stack were
169 * no good, then "m->cs" will be zero and we will have
170 * to assume the worst case (IN_KERNEL) as we actually
171 * have no idea what we were executing when the machine
172 * check hit.
173 * If we do have a good "m->cs" (or a faked one in the
174 * case we were executing in VM86 mode) we can use it to
175 * distinguish an exception taken in user from from one
176 * taken in the kernel.
177 */
error_context(struct mce * m)178 static int error_context(struct mce *m)
179 {
180 return ((m->cs & 3) == 3) ? IN_USER : IN_KERNEL;
181 }
182
mce_severity(struct mce * m,int tolerant,char ** msg)183 int mce_severity(struct mce *m, int tolerant, char **msg)
184 {
185 enum context ctx = error_context(m);
186 struct severity *s;
187
188 for (s = severities;; s++) {
189 if ((m->status & s->mask) != s->result)
190 continue;
191 if ((m->mcgstatus & s->mcgmask) != s->mcgres)
192 continue;
193 if (s->ser == SER_REQUIRED && !mce_ser)
194 continue;
195 if (s->ser == NO_SER && mce_ser)
196 continue;
197 if (s->context && ctx != s->context)
198 continue;
199 if (msg)
200 *msg = s->msg;
201 s->covered = 1;
202 if (s->sev >= MCE_UC_SEVERITY && ctx == IN_KERNEL) {
203 if (panic_on_oops || tolerant < 1)
204 return MCE_PANIC_SEVERITY;
205 }
206 return s->sev;
207 }
208 }
209
210 #ifdef CONFIG_DEBUG_FS
s_start(struct seq_file * f,loff_t * pos)211 static void *s_start(struct seq_file *f, loff_t *pos)
212 {
213 if (*pos >= ARRAY_SIZE(severities))
214 return NULL;
215 return &severities[*pos];
216 }
217
s_next(struct seq_file * f,void * data,loff_t * pos)218 static void *s_next(struct seq_file *f, void *data, loff_t *pos)
219 {
220 if (++(*pos) >= ARRAY_SIZE(severities))
221 return NULL;
222 return &severities[*pos];
223 }
224
s_stop(struct seq_file * f,void * data)225 static void s_stop(struct seq_file *f, void *data)
226 {
227 }
228
s_show(struct seq_file * f,void * data)229 static int s_show(struct seq_file *f, void *data)
230 {
231 struct severity *ser = data;
232 seq_printf(f, "%d\t%s\n", ser->covered, ser->msg);
233 return 0;
234 }
235
236 static const struct seq_operations severities_seq_ops = {
237 .start = s_start,
238 .next = s_next,
239 .stop = s_stop,
240 .show = s_show,
241 };
242
severities_coverage_open(struct inode * inode,struct file * file)243 static int severities_coverage_open(struct inode *inode, struct file *file)
244 {
245 return seq_open(file, &severities_seq_ops);
246 }
247
severities_coverage_write(struct file * file,const char __user * ubuf,size_t count,loff_t * ppos)248 static ssize_t severities_coverage_write(struct file *file,
249 const char __user *ubuf,
250 size_t count, loff_t *ppos)
251 {
252 int i;
253 for (i = 0; i < ARRAY_SIZE(severities); i++)
254 severities[i].covered = 0;
255 return count;
256 }
257
258 static const struct file_operations severities_coverage_fops = {
259 .open = severities_coverage_open,
260 .release = seq_release,
261 .read = seq_read,
262 .write = severities_coverage_write,
263 .llseek = seq_lseek,
264 };
265
severities_debugfs_init(void)266 static int __init severities_debugfs_init(void)
267 {
268 struct dentry *dmce, *fsev;
269
270 dmce = mce_get_debugfs_dir();
271 if (!dmce)
272 goto err_out;
273
274 fsev = debugfs_create_file("severities-coverage", 0444, dmce, NULL,
275 &severities_coverage_fops);
276 if (!fsev)
277 goto err_out;
278
279 return 0;
280
281 err_out:
282 return -ENOMEM;
283 }
284 late_initcall(severities_debugfs_init);
285 #endif /* CONFIG_DEBUG_FS */
286