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