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 KERNEL .context = IN_KERNEL
47 #define USER .context = IN_USER
48 #define SER .ser = SER_REQUIRED
49 #define NOSER .ser = NO_SER
50 #define SEV(s) .sev = MCE_ ## s ## _SEVERITY
51 #define BITCLR(x, s, m, r...) { .mask = x, .result = 0, SEV(s), .msg = m, ## r }
52 #define BITSET(x, s, m, r...) { .mask = x, .result = x, SEV(s), .msg = m, ## r }
53 #define MCGMASK(x, res, s, m, r...) \
54 { .mcgmask = x, .mcgres = res, SEV(s), .msg = m, ## r }
55 #define MASK(x, y, s, m, r...) \
56 { .mask = x, .result = y, SEV(s), .msg = m, ## r }
57 #define MCI_UC_S (MCI_STATUS_UC|MCI_STATUS_S)
58 #define MCI_UC_SAR (MCI_STATUS_UC|MCI_STATUS_S|MCI_STATUS_AR)
59 #define MCACOD 0xffff
60
61 BITCLR(MCI_STATUS_VAL, NO, "Invalid"),
62 BITCLR(MCI_STATUS_EN, NO, "Not enabled"),
63 BITSET(MCI_STATUS_PCC, PANIC, "Processor context corrupt"),
64 /* When MCIP is not set something is very confused */
65 MCGMASK(MCG_STATUS_MCIP, 0, PANIC, "MCIP not set in MCA handler"),
66 /* Neither return not error IP -- no chance to recover -> PANIC */
67 MCGMASK(MCG_STATUS_RIPV|MCG_STATUS_EIPV, 0, PANIC,
68 "Neither restart nor error IP"),
69 MCGMASK(MCG_STATUS_RIPV, 0, PANIC, "In kernel and no restart IP",
70 KERNEL),
71 BITCLR(MCI_STATUS_UC, KEEP, "Corrected error", NOSER),
72 MASK(MCI_STATUS_OVER|MCI_STATUS_UC|MCI_STATUS_EN, MCI_STATUS_UC, SOME,
73 "Spurious not enabled", SER),
74
75 /* ignore OVER for UCNA */
76 MASK(MCI_UC_SAR, MCI_STATUS_UC, KEEP,
77 "Uncorrected no action required", SER),
78 MASK(MCI_STATUS_OVER|MCI_UC_SAR, MCI_STATUS_UC|MCI_STATUS_AR, PANIC,
79 "Illegal combination (UCNA with AR=1)", SER),
80 MASK(MCI_STATUS_S, 0, KEEP, "Non signalled machine check", SER),
81
82 /* AR add known MCACODs here */
83 MASK(MCI_STATUS_OVER|MCI_UC_SAR, MCI_STATUS_OVER|MCI_UC_SAR, PANIC,
84 "Action required with lost events", SER),
85 MASK(MCI_STATUS_OVER|MCI_UC_SAR|MCACOD, MCI_UC_SAR, PANIC,
86 "Action required; unknown MCACOD", SER),
87
88 /* known AO MCACODs: */
89 MASK(MCI_UC_SAR|MCI_STATUS_OVER|0xfff0, MCI_UC_S|0xc0, AO,
90 "Action optional: memory scrubbing error", SER),
91 MASK(MCI_UC_SAR|MCI_STATUS_OVER|MCACOD, MCI_UC_S|0x17a, AO,
92 "Action optional: last level cache writeback error", SER),
93
94 MASK(MCI_STATUS_OVER|MCI_UC_SAR, MCI_UC_S, SOME,
95 "Action optional unknown MCACOD", SER),
96 MASK(MCI_STATUS_OVER|MCI_UC_SAR, MCI_UC_S|MCI_STATUS_OVER, SOME,
97 "Action optional with lost events", SER),
98 BITSET(MCI_STATUS_UC|MCI_STATUS_OVER, PANIC, "Overflowed uncorrected"),
99 BITSET(MCI_STATUS_UC, UC, "Uncorrected"),
100 BITSET(0, SOME, "No match") /* always matches. keep at end */
101 };
102
103 /*
104 * If the EIPV bit is set, it means the saved IP is the
105 * instruction which caused the MCE.
106 */
107 static int error_context(struct mce *m)
108 {
109 if (m->mcgstatus & MCG_STATUS_EIPV)
110 return (m->ip && (m->cs & 3) == 3) ? IN_USER : IN_KERNEL;
111 /* Unknown, assume kernel */
112 return IN_KERNEL;
113 }
114
115 int mce_severity(struct mce *a, int tolerant, char **msg)
116 {
117 enum context ctx = error_context(a);
118 struct severity *s;
119
120 for (s = severities;; s++) {
121 if ((a->status & s->mask) != s->result)
122 continue;
123 if ((a->mcgstatus & s->mcgmask) != s->mcgres)
124 continue;
125 if (s->ser == SER_REQUIRED && !mce_ser)
126 continue;
127 if (s->ser == NO_SER && mce_ser)
128 continue;
129 if (s->context && ctx != s->context)
130 continue;
131 if (msg)
132 *msg = s->msg;
133 s->covered = 1;
134 if (s->sev >= MCE_UC_SEVERITY && ctx == IN_KERNEL) {
135 if (panic_on_oops || tolerant < 1)
136 return MCE_PANIC_SEVERITY;
137 }
138 return s->sev;
139 }
140 }
141
142 static void *s_start(struct seq_file *f, loff_t *pos)
143 {
144 if (*pos >= ARRAY_SIZE(severities))
145 return NULL;
146 return &severities[*pos];
147 }
148
149 static void *s_next(struct seq_file *f, void *data, loff_t *pos)
150 {
151 if (++(*pos) >= ARRAY_SIZE(severities))
152 return NULL;
153 return &severities[*pos];
154 }
155
156 static void s_stop(struct seq_file *f, void *data)
157 {
158 }
159
160 static int s_show(struct seq_file *f, void *data)
161 {
162 struct severity *ser = data;
163 seq_printf(f, "%d\t%s\n", ser->covered, ser->msg);
164 return 0;
165 }
166
167 static const struct seq_operations severities_seq_ops = {
168 .start = s_start,
169 .next = s_next,
170 .stop = s_stop,
171 .show = s_show,
172 };
173
174 static int severities_coverage_open(struct inode *inode, struct file *file)
175 {
176 return seq_open(file, &severities_seq_ops);
177 }
178
179 static ssize_t severities_coverage_write(struct file *file,
180 const char __user *ubuf,
181 size_t count, loff_t *ppos)
182 {
183 int i;
184 for (i = 0; i < ARRAY_SIZE(severities); i++)
185 severities[i].covered = 0;
186 return count;
187 }
188
189 static const struct file_operations severities_coverage_fops = {
190 .open = severities_coverage_open,
191 .release = seq_release,
192 .read = seq_read,
193 .write = severities_coverage_write,
194 };
195
196 static int __init severities_debugfs_init(void)
197 {
198 struct dentry *dmce = NULL, *fseverities_coverage = NULL;
199
200 dmce = debugfs_create_dir("mce", NULL);
201 if (dmce == NULL)
202 goto err_out;
203 fseverities_coverage = debugfs_create_file("severities-coverage",
204 0444, dmce, NULL,
205 &severities_coverage_fops);
206 if (fseverities_coverage == NULL)
207 goto err_out;
208
209 return 0;
210
211 err_out:
212 if (fseverities_coverage)
213 debugfs_remove(fseverities_coverage);
214 if (dmce)
215 debugfs_remove(dmce);
216 return -ENOMEM;
217 }
218 late_initcall(severities_debugfs_init);
219
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