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 #include <asm/uaccess.h>
  18
  19 #include "mce-internal.h"
  20
  21 /*
  22  * Grade an mce by severity. In general the most severe ones are processed
  23  * first. Since there are quite a lot of combinations test the bits in a
  24  * table-driven way. The rules are simply processed in order, first
  25  * match wins.
  26  *
  27  * Note this is only used for machine check exceptions, the corrected
  28  * errors use much simpler rules. The exceptions still check for the corrected
  29  * errors, but only to leave them alone for the CMCI handler (except for
  30  * panic situations)
  31  */
  32
  33 enum context { IN_KERNEL = 1, IN_USER = 2, IN_KERNEL_RECOV = 3 };
  34 enum ser { SER_REQUIRED = 1, NO_SER = 2 };
  35 enum exception { EXCP_CONTEXT = 1, NO_EXCP = 2 };
  36
  37 static struct severity {
  38         u64 mask;
  39         u64 result;
  40         unsigned char sev;
  41         unsigned char mcgmask;
  42         unsigned char mcgres;
  43         unsigned char ser;
  44         unsigned char context;
  45         unsigned char excp;
  46         unsigned char covered;
  47         char *msg;
  48 } severities[] = {
  49 #define MCESEV(s, m, c...) { .sev = MCE_ ## s ## _SEVERITY, .msg = m, ## c }
  50 #define  KERNEL         .context = IN_KERNEL
  51 #define  USER           .context = IN_USER
  52 #define  KERNEL_RECOV   .context = IN_KERNEL_RECOV
  53 #define  SER            .ser = SER_REQUIRED
  54 #define  NOSER          .ser = NO_SER
  55 #define  EXCP           .excp = EXCP_CONTEXT
  56 #define  NOEXCP         .excp = NO_EXCP
  57 #define  BITCLR(x)      .mask = x, .result = 0
  58 #define  BITSET(x)      .mask = x, .result = x
  59 #define  MCGMASK(x, y)  .mcgmask = x, .mcgres = y
  60 #define  MASK(x, y)     .mask = x, .result = y
  61 #define MCI_UC_S (MCI_STATUS_UC|MCI_STATUS_S)
  62 #define MCI_UC_SAR (MCI_STATUS_UC|MCI_STATUS_S|MCI_STATUS_AR)
  63 #define MCI_ADDR (MCI_STATUS_ADDRV|MCI_STATUS_MISCV)
  64
  65         MCESEV(
  66                 NO, "Invalid",
  67                 BITCLR(MCI_STATUS_VAL)
  68                 ),
  69         MCESEV(
  70                 NO, "Not enabled",
  71                 EXCP, BITCLR(MCI_STATUS_EN)
  72                 ),
  73         MCESEV(
  74                 PANIC, "Processor context corrupt",
  75                 BITSET(MCI_STATUS_PCC)
  76                 ),
  77         /* When MCIP is not set something is very confused */
  78         MCESEV(
  79                 PANIC, "MCIP not set in MCA handler",
  80                 EXCP, MCGMASK(MCG_STATUS_MCIP, 0)
  81                 ),
  82         /* Neither return not error IP -- no chance to recover -> PANIC */
  83         MCESEV(
  84                 PANIC, "Neither restart nor error IP",
  85                 EXCP, MCGMASK(MCG_STATUS_RIPV|MCG_STATUS_EIPV, 0)
  86                 ),
  87         MCESEV(
  88                 PANIC, "In kernel and no restart IP",
  89                 EXCP, KERNEL, MCGMASK(MCG_STATUS_RIPV, 0)
  90                 ),
  91         MCESEV(
  92                 PANIC, "In kernel and no restart IP",
  93                 EXCP, KERNEL_RECOV, MCGMASK(MCG_STATUS_RIPV, 0)
  94                 ),
  95         MCESEV(
  96                 DEFERRED, "Deferred error",
  97                 NOSER, MASK(MCI_STATUS_UC|MCI_STATUS_DEFERRED|MCI_STATUS_POISON, MCI_STATUS_DEFERRED)
  98                 ),
  99         MCESEV(
 100                 KEEP, "Corrected error",
 101                 NOSER, BITCLR(MCI_STATUS_UC)
 102                 ),
 103
 104         /* ignore OVER for UCNA */
 105         MCESEV(
 106                 UCNA, "Uncorrected no action required",
 107                 SER, MASK(MCI_UC_SAR, MCI_STATUS_UC)
 108                 ),
 109         MCESEV(
 110                 PANIC, "Illegal combination (UCNA with AR=1)",
 111                 SER,
 112                 MASK(MCI_STATUS_OVER|MCI_UC_SAR, MCI_STATUS_UC|MCI_STATUS_AR)
 113                 ),
 114         MCESEV(
 115                 KEEP, "Non signalled machine check",
 116                 SER, BITCLR(MCI_STATUS_S)
 117                 ),
 118
 119         MCESEV(
 120                 PANIC, "Action required with lost events",
 121                 SER, BITSET(MCI_STATUS_OVER|MCI_UC_SAR)
 122                 ),
 123
 124         /* known AR MCACODs: */
 125 #ifdef  CONFIG_MEMORY_FAILURE
 126         MCESEV(
 127                 KEEP, "Action required but unaffected thread is continuable",
 128                 SER, MASK(MCI_STATUS_OVER|MCI_UC_SAR|MCI_ADDR, MCI_UC_SAR|MCI_ADDR),
 129                 MCGMASK(MCG_STATUS_RIPV|MCG_STATUS_EIPV, MCG_STATUS_RIPV)
 130                 ),
 131         MCESEV(
 132                 AR, "Action required: data load in error recoverable area of kernel",
 133                 SER, MASK(MCI_STATUS_OVER|MCI_UC_SAR|MCI_ADDR|MCACOD, MCI_UC_SAR|MCI_ADDR|MCACOD_DATA),
 134                 KERNEL_RECOV
 135                 ),
 136         MCESEV(
 137                 AR, "Action required: data load error in a user process",
 138                 SER, MASK(MCI_STATUS_OVER|MCI_UC_SAR|MCI_ADDR|MCACOD, MCI_UC_SAR|MCI_ADDR|MCACOD_DATA),
 139                 USER
 140                 ),
 141         MCESEV(
 142                 AR, "Action required: instruction fetch error in a user process",
 143                 SER, MASK(MCI_STATUS_OVER|MCI_UC_SAR|MCI_ADDR|MCACOD, MCI_UC_SAR|MCI_ADDR|MCACOD_INSTR),
 144                 USER
 145                 ),
 146 #endif
 147         MCESEV(
 148                 PANIC, "Action required: unknown MCACOD",
 149                 SER, MASK(MCI_STATUS_OVER|MCI_UC_SAR, MCI_UC_SAR)
 150                 ),
 151
 152         /* known AO MCACODs: */
 153         MCESEV(
 154                 AO, "Action optional: memory scrubbing error",
 155                 SER, MASK(MCI_STATUS_OVER|MCI_UC_SAR|MCACOD_SCRUBMSK, MCI_UC_S|MCACOD_SCRUB)
 156                 ),
 157         MCESEV(
 158                 AO, "Action optional: last level cache writeback error",
 159                 SER, MASK(MCI_STATUS_OVER|MCI_UC_SAR|MCACOD, MCI_UC_S|MCACOD_L3WB)
 160                 ),
 161         MCESEV(
 162                 SOME, "Action optional: unknown MCACOD",
 163                 SER, MASK(MCI_STATUS_OVER|MCI_UC_SAR, MCI_UC_S)
 164                 ),
 165         MCESEV(
 166                 SOME, "Action optional with lost events",
 167                 SER, MASK(MCI_STATUS_OVER|MCI_UC_SAR, MCI_STATUS_OVER|MCI_UC_S)
 168                 ),
 169
 170         MCESEV(
 171                 PANIC, "Overflowed uncorrected",
 172                 BITSET(MCI_STATUS_OVER|MCI_STATUS_UC)
 173                 ),
 174         MCESEV(
 175                 UC, "Uncorrected",
 176                 BITSET(MCI_STATUS_UC)
 177                 ),
 178         MCESEV(
 179                 SOME, "No match",
 180                 BITSET(0)
 181                 )       /* always matches. keep at end */
 182 };
 183
 184 #define mc_recoverable(mcg) (((mcg) & (MCG_STATUS_RIPV|MCG_STATUS_EIPV)) == \
 185                                 (MCG_STATUS_RIPV|MCG_STATUS_EIPV))
 186
 187 /*
 188  * If mcgstatus indicated that ip/cs on the stack were
 189  * no good, then "m->cs" will be zero and we will have
 190  * to assume the worst case (IN_KERNEL) as we actually
 191  * have no idea what we were executing when the machine
 192  * check hit.
 193  * If we do have a good "m->cs" (or a faked one in the
 194  * case we were executing in VM86 mode) we can use it to
 195  * distinguish an exception taken in user from from one
 196  * taken in the kernel.
 197  */
 198 static int error_context(struct mce *m)
 199 {
 200         if ((m->cs & 3) == 3)
 201                 return IN_USER;
 202         if (mc_recoverable(m->mcgstatus) && ex_has_fault_handler(m->ip))
 203                 return IN_KERNEL_RECOV;
 204         return IN_KERNEL;
 205 }
 206
 207 /*
 208  * See AMD Error Scope Hierarchy table in a newer BKDG. For example
 209  * 49125_15h_Models_30h-3Fh_BKDG.pdf, section "RAS Features"
 210  */
 211 static int mce_severity_amd(struct mce *m, int tolerant, char **msg, bool is_excp)
 212 {
 213         enum context ctx = error_context(m);
 214
 215         /* Processor Context Corrupt, no need to fumble too much, die! */
 216         if (m->status & MCI_STATUS_PCC)
 217                 return MCE_PANIC_SEVERITY;
 218
 219         if (m->status & MCI_STATUS_UC) {
 220
 221                 /*
 222                  * On older systems where overflow_recov flag is not present, we
 223                  * should simply panic if an error overflow occurs. If
 224                  * overflow_recov flag is present and set, then software can try
 225                  * to at least kill process to prolong system operation.
 226                  */
 227                 if (mce_flags.overflow_recov) {
 228                         /* software can try to contain */
 229                         if (!(m->mcgstatus & MCG_STATUS_RIPV) && (ctx == IN_KERNEL))
 230                                 return MCE_PANIC_SEVERITY;
 231
 232                         /* kill current process */
 233                         return MCE_AR_SEVERITY;
 234                 } else {
 235                         /* at least one error was not logged */
 236                         if (m->status & MCI_STATUS_OVER)
 237                                 return MCE_PANIC_SEVERITY;
 238                 }
 239
 240                 /*
 241                  * For any other case, return MCE_UC_SEVERITY so that we log the
 242                  * error and exit #MC handler.
 243                  */
 244                 return MCE_UC_SEVERITY;
 245         }
 246
 247         /*
 248          * deferred error: poll handler catches these and adds to mce_ring so
 249          * memory-failure can take recovery actions.
 250          */
 251         if (m->status & MCI_STATUS_DEFERRED)
 252                 return MCE_DEFERRED_SEVERITY;
 253
 254         /*
 255          * corrected error: poll handler catches these and passes responsibility
 256          * of decoding the error to EDAC
 257          */
 258         return MCE_KEEP_SEVERITY;
 259 }
 260
 261 static int mce_severity_intel(struct mce *m, int tolerant, char **msg, bool is_excp)
 262 {
 263         enum exception excp = (is_excp ? EXCP_CONTEXT : NO_EXCP);
 264         enum context ctx = error_context(m);
 265         struct severity *s;
 266
 267         for (s = severities;; s++) {
 268                 if ((m->status & s->mask) != s->result)
 269                         continue;
 270                 if ((m->mcgstatus & s->mcgmask) != s->mcgres)
 271                         continue;
 272                 if (s->ser == SER_REQUIRED && !mca_cfg.ser)
 273                         continue;
 274                 if (s->ser == NO_SER && mca_cfg.ser)
 275                         continue;
 276                 if (s->context && ctx != s->context)
 277                         continue;
 278                 if (s->excp && excp != s->excp)
 279                         continue;
 280                 if (msg)
 281                         *msg = s->msg;
 282                 s->covered = 1;
 283                 if (s->sev >= MCE_UC_SEVERITY && ctx == IN_KERNEL) {
 284                         if (panic_on_oops || tolerant < 1)
 285                                 return MCE_PANIC_SEVERITY;
 286                 }
 287                 return s->sev;
 288         }
 289 }
 290
 291 /* Default to mce_severity_intel */
 292 int (*mce_severity)(struct mce *m, int tolerant, char **msg, bool is_excp) =
 293                     mce_severity_intel;
 294
 295 void __init mcheck_vendor_init_severity(void)
 296 {
 297         if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD)
 298                 mce_severity = mce_severity_amd;
 299 }
 300
 301 #ifdef CONFIG_DEBUG_FS
 302 static void *s_start(struct seq_file *f, loff_t *pos)
 303 {
 304         if (*pos >= ARRAY_SIZE(severities))
 305                 return NULL;
 306         return &severities[*pos];
 307 }
 308
 309 static void *s_next(struct seq_file *f, void *data, loff_t *pos)
 310 {
 311         if (++(*pos) >= ARRAY_SIZE(severities))
 312                 return NULL;
 313         return &severities[*pos];
 314 }
 315
 316 static void s_stop(struct seq_file *f, void *data)
 317 {
 318 }
 319
 320 static int s_show(struct seq_file *f, void *data)
 321 {
 322         struct severity *ser = data;
 323         seq_printf(f, "%d\t%s\n", ser->covered, ser->msg);
 324         return 0;
 325 }
 326
 327 static const struct seq_operations severities_seq_ops = {
 328         .start  = s_start,
 329         .next   = s_next,
 330         .stop   = s_stop,
 331         .show   = s_show,
 332 };
 333
 334 static int severities_coverage_open(struct inode *inode, struct file *file)
 335 {
 336         return seq_open(file, &severities_seq_ops);
 337 }
 338
 339 static ssize_t severities_coverage_write(struct file *file,
 340                                          const char __user *ubuf,
 341                                          size_t count, loff_t *ppos)
 342 {
 343         int i;
 344         for (i = 0; i < ARRAY_SIZE(severities); i++)
 345                 severities[i].covered = 0;
 346         return count;
 347 }
 348
 349 static const struct file_operations severities_coverage_fops = {
 350         .open           = severities_coverage_open,
 351         .release        = seq_release,
 352         .read           = seq_read,
 353         .write          = severities_coverage_write,
 354         .llseek         = seq_lseek,
 355 };
 356
 357 static int __init severities_debugfs_init(void)
 358 {
 359         struct dentry *dmce, *fsev;
 360
 361         dmce = mce_get_debugfs_dir();
 362         if (!dmce)
 363                 goto err_out;
 364
 365         fsev = debugfs_create_file("severities-coverage", 0444, dmce, NULL,
 366                                    &severities_coverage_fops);
 367         if (!fsev)
 368                 goto err_out;
 369
 370         return 0;
 371
 372 err_out:
 373         return -ENOMEM;
 374 }
 375 late_initcall(severities_debugfs_init);
 376 #endif /* CONFIG_DEBUG_FS */