drivers/firmware/efi/efi-pstore.c

   1 #include <linux/efi.h>
   2 #include <linux/module.h>
   3 #include <linux/pstore.h>
   4 #include <linux/slab.h>
   5 #include <linux/ucs2_string.h>
   6
   7 #define DUMP_NAME_LEN 52
   8
   9 static bool efivars_pstore_disable =
  10         IS_ENABLED(CONFIG_EFI_VARS_PSTORE_DEFAULT_DISABLE);
  11
  12 module_param_named(pstore_disable, efivars_pstore_disable, bool, 0644);
  13
  14 #define PSTORE_EFI_ATTRIBUTES \
  15         (EFI_VARIABLE_NON_VOLATILE | \
  16          EFI_VARIABLE_BOOTSERVICE_ACCESS | \
  17          EFI_VARIABLE_RUNTIME_ACCESS)
  18
  19 static int efi_pstore_open(struct pstore_info *psi)
  20 {
  21         psi->data = NULL;
  22         return 0;
  23 }
  24
  25 static int efi_pstore_close(struct pstore_info *psi)
  26 {
  27         psi->data = NULL;
  28         return 0;
  29 }
  30
  31 struct pstore_read_data {
  32         u64 *id;
  33         enum pstore_type_id *type;
  34         int *count;
  35         struct timespec *timespec;
  36         bool *compressed;
  37         ssize_t *ecc_notice_size;
  38         char **buf;
  39 };
  40
  41 static inline u64 generic_id(unsigned long timestamp,
  42                              unsigned int part, int count)
  43 {
  44         return ((u64) timestamp * 100 + part) * 1000 + count;
  45 }
  46
  47 static int efi_pstore_read_func(struct efivar_entry *entry, void *data)
  48 {
  49         efi_guid_t vendor = LINUX_EFI_CRASH_GUID;
  50         struct pstore_read_data *cb_data = data;
  51         char name[DUMP_NAME_LEN], data_type;
  52         int i;
  53         int cnt;
  54         unsigned int part;
  55         unsigned long time, size;
  56
  57         if (efi_guidcmp(entry->var.VendorGuid, vendor))
  58                 return 0;
  59
  60         for (i = 0; i < DUMP_NAME_LEN; i++)
  61                 name[i] = entry->var.VariableName[i];
  62
  63         if (sscanf(name, "dump-type%u-%u-%d-%lu-%c",
  64                    cb_data->type, &part, &cnt, &time, &data_type) == 5) {
  65                 *cb_data->id = generic_id(time, part, cnt);
  66                 *cb_data->count = cnt;
  67                 cb_data->timespec->tv_sec = time;
  68                 cb_data->timespec->tv_nsec = 0;
  69                 if (data_type == 'C')
  70                         *cb_data->compressed = true;
  71                 else
  72                         *cb_data->compressed = false;
  73                 *cb_data->ecc_notice_size = 0;
  74         } else if (sscanf(name, "dump-type%u-%u-%d-%lu",
  75                    cb_data->type, &part, &cnt, &time) == 4) {
  76                 *cb_data->id = generic_id(time, part, cnt);
  77                 *cb_data->count = cnt;
  78                 cb_data->timespec->tv_sec = time;
  79                 cb_data->timespec->tv_nsec = 0;
  80                 *cb_data->compressed = false;
  81                 *cb_data->ecc_notice_size = 0;
  82         } else if (sscanf(name, "dump-type%u-%u-%lu",
  83                           cb_data->type, &part, &time) == 3) {
  84                 /*
  85                  * Check if an old format,
  86                  * which doesn't support holding
  87                  * multiple logs, remains.
  88                  */
  89                 *cb_data->id = generic_id(time, part, 0);
  90                 *cb_data->count = 0;
  91                 cb_data->timespec->tv_sec = time;
  92                 cb_data->timespec->tv_nsec = 0;
  93                 *cb_data->compressed = false;
  94                 *cb_data->ecc_notice_size = 0;
  95         } else
  96                 return 0;
  97
  98         entry->var.DataSize = 1024;
  99         __efivar_entry_get(entry, &entry->var.Attributes,
 100                            &entry->var.DataSize, entry->var.Data);
 101         size = entry->var.DataSize;
 102         memcpy(*cb_data->buf, entry->var.Data,
 103                (size_t)min_t(unsigned long, EFIVARS_DATA_SIZE_MAX, size));
 104
 105         return size;
 106 }
 107
 108 /**
 109  * efi_pstore_scan_sysfs_enter
 110  * @pos: scanning entry
 111  * @next: next entry
 112  * @head: list head
 113  */
 114 static void efi_pstore_scan_sysfs_enter(struct efivar_entry *pos,
 115                                         struct efivar_entry *next,
 116                                         struct list_head *head)
 117 {
 118         pos->scanning = true;
 119         if (&next->list != head)
 120                 next->scanning = true;
 121 }
 122
 123 /**
 124  * __efi_pstore_scan_sysfs_exit
 125  * @entry: deleting entry
 126  * @turn_off_scanning: Check if a scanning flag should be turned off
 127  */
 128 static inline int __efi_pstore_scan_sysfs_exit(struct efivar_entry *entry,
 129                                                 bool turn_off_scanning)
 130 {
 131         if (entry->deleting) {
 132                 list_del(&entry->list);
 133                 efivar_entry_iter_end();
 134                 efivar_unregister(entry);
 135                 if (efivar_entry_iter_begin())
 136                         return -EINTR;
 137         } else if (turn_off_scanning)
 138                 entry->scanning = false;
 139
 140         return 0;
 141 }
 142
 143 /**
 144  * efi_pstore_scan_sysfs_exit
 145  * @pos: scanning entry
 146  * @next: next entry
 147  * @head: list head
 148  * @stop: a flag checking if scanning will stop
 149  */
 150 static int efi_pstore_scan_sysfs_exit(struct efivar_entry *pos,
 151                                        struct efivar_entry *next,
 152                                        struct list_head *head, bool stop)
 153 {
 154         int ret = __efi_pstore_scan_sysfs_exit(pos, true);
 155
 156         if (ret)
 157                 return ret;
 158
 159         if (stop)
 160                 ret = __efi_pstore_scan_sysfs_exit(next, &next->list != head);
 161         return ret;
 162 }
 163
 164 /**
 165  * efi_pstore_sysfs_entry_iter
 166  *
 167  * @data: function-specific data to pass to callback
 168  * @pos: entry to begin iterating from
 169  *
 170  * You MUST call efivar_enter_iter_begin() before this function, and
 171  * efivar_entry_iter_end() afterwards.
 172  *
 173  * It is possible to begin iteration from an arbitrary entry within
 174  * the list by passing @pos. @pos is updated on return to point to
 175  * the next entry of the last one passed to efi_pstore_read_func().
 176  * To begin iterating from the beginning of the list @pos must be %NULL.
 177  */
 178 static int efi_pstore_sysfs_entry_iter(void *data, struct efivar_entry **pos)
 179 {
 180         struct efivar_entry *entry, *n;
 181         struct list_head *head = &efivar_sysfs_list;
 182         int size = 0;
 183         int ret;
 184
 185         if (!*pos) {
 186                 list_for_each_entry_safe(entry, n, head, list) {
 187                         efi_pstore_scan_sysfs_enter(entry, n, head);
 188
 189                         size = efi_pstore_read_func(entry, data);
 190                         ret = efi_pstore_scan_sysfs_exit(entry, n, head,
 191                                                          size < 0);
 192                         if (ret)
 193                                 return ret;
 194                         if (size)
 195                                 break;
 196                 }
 197                 *pos = n;
 198                 return size;
 199         }
 200
 201         list_for_each_entry_safe_from((*pos), n, head, list) {
 202                 efi_pstore_scan_sysfs_enter((*pos), n, head);
 203
 204                 size = efi_pstore_read_func((*pos), data);
 205                 ret = efi_pstore_scan_sysfs_exit((*pos), n, head, size < 0);
 206                 if (ret)
 207                         return ret;
 208                 if (size)
 209                         break;
 210         }
 211         *pos = n;
 212         return size;
 213 }
 214
 215 /**
 216  * efi_pstore_read
 217  *
 218  * This function returns a size of NVRAM entry logged via efi_pstore_write().
 219  * The meaning and behavior of efi_pstore/pstore are as below.
 220  *
 221  * size > 0: Got data of an entry logged via efi_pstore_write() successfully,
 222  *           and pstore filesystem will continue reading subsequent entries.
 223  * size == 0: Entry was not logged via efi_pstore_write(),
 224  *            and efi_pstore driver will continue reading subsequent entries.
 225  * size < 0: Failed to get data of entry logging via efi_pstore_write(),
 226  *           and pstore will stop reading entry.
 227  */
 228 static ssize_t efi_pstore_read(u64 *id, enum pstore_type_id *type,
 229                                int *count, struct timespec *timespec,
 230                                char **buf, bool *compressed,
 231                                ssize_t *ecc_notice_size,
 232                                struct pstore_info *psi)
 233 {
 234         struct pstore_read_data data;
 235         ssize_t size;
 236
 237         data.id = id;
 238         data.type = type;
 239         data.count = count;
 240         data.timespec = timespec;
 241         data.compressed = compressed;
 242         data.ecc_notice_size = ecc_notice_size;
 243         data.buf = buf;
 244
 245         *data.buf = kzalloc(EFIVARS_DATA_SIZE_MAX, GFP_KERNEL);
 246         if (!*data.buf)
 247                 return -ENOMEM;
 248
 249         if (efivar_entry_iter_begin()) {
 250                 kfree(*data.buf);
 251                 return -EINTR;
 252         }
 253         size = efi_pstore_sysfs_entry_iter(&data,
 254                                            (struct efivar_entry **)&psi->data);
 255         efivar_entry_iter_end();
 256         if (size <= 0)
 257                 kfree(*data.buf);
 258         return size;
 259 }
 260
 261 static int efi_pstore_write(enum pstore_type_id type,
 262                 enum kmsg_dump_reason reason, u64 *id,
 263                 unsigned int part, int count, bool compressed, size_t size,
 264                 struct pstore_info *psi)
 265 {
 266         char name[DUMP_NAME_LEN];
 267         efi_char16_t efi_name[DUMP_NAME_LEN];
 268         efi_guid_t vendor = LINUX_EFI_CRASH_GUID;
 269         int i, ret = 0;
 270
 271         sprintf(name, "dump-type%u-%u-%d-%lu-%c", type, part, count,
 272                 get_seconds(), compressed ? 'C' : 'D');
 273
 274         for (i = 0; i < DUMP_NAME_LEN; i++)
 275                 efi_name[i] = name[i];
 276
 277         efivar_entry_set_safe(efi_name, vendor, PSTORE_EFI_ATTRIBUTES,
 278                               !pstore_cannot_block_path(reason),
 279                               size, psi->buf);
 280
 281         if (reason == KMSG_DUMP_OOPS)
 282                 efivar_run_worker();
 283
 284         *id = part;
 285         return ret;
 286 };
 287
 288 struct pstore_erase_data {
 289         u64 id;
 290         enum pstore_type_id type;
 291         int count;
 292         struct timespec time;
 293         efi_char16_t *name;
 294 };
 295
 296 /*
 297  * Clean up an entry with the same name
 298  */
 299 static int efi_pstore_erase_func(struct efivar_entry *entry, void *data)
 300 {
 301         struct pstore_erase_data *ed = data;
 302         efi_guid_t vendor = LINUX_EFI_CRASH_GUID;
 303         efi_char16_t efi_name_old[DUMP_NAME_LEN];
 304         efi_char16_t *efi_name = ed->name;
 305         unsigned long ucs2_len = ucs2_strlen(ed->name);
 306         char name_old[DUMP_NAME_LEN];
 307         int i;
 308
 309         if (efi_guidcmp(entry->var.VendorGuid, vendor))
 310                 return 0;
 311
 312         if (ucs2_strncmp(entry->var.VariableName,
 313                           efi_name, (size_t)ucs2_len)) {
 314                 /*
 315                  * Check if an old format, which doesn't support
 316                  * holding multiple logs, remains.
 317                  */
 318                 sprintf(name_old, "dump-type%u-%u-%lu", ed->type,
 319                         (unsigned int)ed->id, ed->time.tv_sec);
 320
 321                 for (i = 0; i < DUMP_NAME_LEN; i++)
 322                         efi_name_old[i] = name_old[i];
 323
 324                 if (ucs2_strncmp(entry->var.VariableName, efi_name_old,
 325                                   ucs2_strlen(efi_name_old)))
 326                         return 0;
 327         }
 328
 329         if (entry->scanning) {
 330                 /*
 331                  * Skip deletion because this entry will be deleted
 332                  * after scanning is completed.
 333                  */
 334                 entry->deleting = true;
 335         } else
 336                 list_del(&entry->list);
 337
 338         /* found */
 339         __efivar_entry_delete(entry);
 340
 341         return 1;
 342 }
 343
 344 static int efi_pstore_erase(enum pstore_type_id type, u64 id, int count,
 345                             struct timespec time, struct pstore_info *psi)
 346 {
 347         struct pstore_erase_data edata;
 348         struct efivar_entry *entry = NULL;
 349         char name[DUMP_NAME_LEN];
 350         efi_char16_t efi_name[DUMP_NAME_LEN];
 351         int found, i;
 352         unsigned int part;
 353
 354         do_div(id, 1000);
 355         part = do_div(id, 100);
 356         sprintf(name, "dump-type%u-%u-%d-%lu", type, part, count, time.tv_sec);
 357
 358         for (i = 0; i < DUMP_NAME_LEN; i++)
 359                 efi_name[i] = name[i];
 360
 361         edata.id = part;
 362         edata.type = type;
 363         edata.count = count;
 364         edata.time = time;
 365         edata.name = efi_name;
 366
 367         if (efivar_entry_iter_begin())
 368                 return -EINTR;
 369         found = __efivar_entry_iter(efi_pstore_erase_func, &efivar_sysfs_list, &edata, &entry);
 370
 371         if (found && !entry->scanning) {
 372                 efivar_entry_iter_end();
 373                 efivar_unregister(entry);
 374         } else
 375                 efivar_entry_iter_end();
 376
 377         return 0;
 378 }
 379
 380 static struct pstore_info efi_pstore_info = {
 381         .owner          = THIS_MODULE,
 382         .name           = "efi",
 383         .flags          = PSTORE_FLAGS_DMESG,
 384         .open           = efi_pstore_open,
 385         .close          = efi_pstore_close,
 386         .read           = efi_pstore_read,
 387         .write          = efi_pstore_write,
 388         .erase          = efi_pstore_erase,
 389 };
 390
 391 static __init int efivars_pstore_init(void)
 392 {
 393         if (!efi_enabled(EFI_RUNTIME_SERVICES))
 394                 return 0;
 395
 396         if (!efivars_kobject())
 397                 return 0;
 398
 399         if (efivars_pstore_disable)
 400                 return 0;
 401
 402         efi_pstore_info.buf = kmalloc(4096, GFP_KERNEL);
 403         if (!efi_pstore_info.buf)
 404                 return -ENOMEM;
 405
 406         efi_pstore_info.bufsize = 1024;
 407         spin_lock_init(&efi_pstore_info.buf_lock);
 408
 409         if (pstore_register(&efi_pstore_info)) {
 410                 kfree(efi_pstore_info.buf);
 411                 efi_pstore_info.buf = NULL;
 412                 efi_pstore_info.bufsize = 0;
 413         }
 414
 415         return 0;
 416 }
 417
 418 static __exit void efivars_pstore_exit(void)
 419 {
 420         if (!efi_pstore_info.bufsize)
 421                 return;
 422
 423         pstore_unregister(&efi_pstore_info);
 424         kfree(efi_pstore_info.buf);
 425         efi_pstore_info.buf = NULL;
 426         efi_pstore_info.bufsize = 0;
 427 }
 428
 429 module_init(efivars_pstore_init);
 430 module_exit(efivars_pstore_exit);
 431
 432 MODULE_DESCRIPTION("EFI variable backend for pstore");
 433 MODULE_LICENSE("GPL");
 434 MODULE_ALIAS("platform:efivars");