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
32enum context { IN_KERNEL = 1, IN_USER = 2 };
33enum ser { SER_REQUIRED = 1, NO_SER = 2 };
34
35static 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 */
178static int error_context(struct mce *m)
179{
180	return ((m->cs & 3) == 3) ? IN_USER : IN_KERNEL;
181}
182
183int 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
211static 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
218static 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
225static void s_stop(struct seq_file *f, void *data)
226{
227}
228
229static 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
236static 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
243static int severities_coverage_open(struct inode *inode, struct file *file)
244{
245	return seq_open(file, &severities_seq_ops);
246}
247
248static 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
258static 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
266static 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
281err_out:
282	return -ENOMEM;
283}
284late_initcall(severities_debugfs_init);
285#endif /* CONFIG_DEBUG_FS */
286