arch/x86/kernel/cpu/mcheck/mce-severity.c

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