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  *
 159  * You MUST call efivar_enter_iter_begin() before this function, and
 160  * efivar_entry_iter_end() afterwards.
 161  *
 162  */
 163 static int efi_pstore_sysfs_entry_iter(struct pstore_record *record)
 164 {
 165         struct efivar_entry **pos = (struct efivar_entry **)&record->psi->data;
 166         struct efivar_entry *entry, *n;
 167         struct list_head *head = &efivar_sysfs_list;
 168         int size = 0;
 169         int ret;
 170
 171         if (!*pos) {
 172                 list_for_each_entry_safe(entry, n, head, list) {
 173                         efi_pstore_scan_sysfs_enter(entry, n, head);
 174
 175                         size = efi_pstore_read_func(entry, record);
 176                         ret = efi_pstore_scan_sysfs_exit(entry, n, head,
 177                                                          size < 0);
 178                         if (ret)
 179                                 return ret;
 180                         if (size)
 181                                 break;
 182                 }
 183                 *pos = n;
 184                 return size;
 185         }
 186
 187         list_for_each_entry_safe_from((*pos), n, head, list) {
 188                 efi_pstore_scan_sysfs_enter((*pos), n, head);
 189
 190                 size = efi_pstore_read_func((*pos), record);
 191                 ret = efi_pstore_scan_sysfs_exit((*pos), n, head, size < 0);
 192                 if (ret)
 193                         return ret;
 194                 if (size)
 195                         break;
 196         }
 197         *pos = n;
 198         return size;
 199 }
 200
 201 /**
 202  * efi_pstore_read
 203  *
 204  * This function returns a size of NVRAM entry logged via efi_pstore_write().
 205  * The meaning and behavior of efi_pstore/pstore are as below.
 206  *
 207  * size > 0: Got data of an entry logged via efi_pstore_write() successfully,
 208  *           and pstore filesystem will continue reading subsequent entries.
 209  * size == 0: Entry was not logged via efi_pstore_write(),
 210  *            and efi_pstore driver will continue reading subsequent entries.
 211  * size < 0: Failed to get data of entry logging via efi_pstore_write(),
 212  *           and pstore will stop reading entry.
 213  */
 214 static ssize_t efi_pstore_read(struct pstore_record *record)
 215 {
 216         ssize_t size;
 217
 218         record->buf = kzalloc(EFIVARS_DATA_SIZE_MAX, GFP_KERNEL);
 219         if (!record->buf)
 220                 return -ENOMEM;
 221
 222         if (efivar_entry_iter_begin()) {
 223                 size = -EINTR;
 224                 goto out;
 225         }
 226         size = efi_pstore_sysfs_entry_iter(record);
 227         efivar_entry_iter_end();
 228
 229 out:
 230         if (size <= 0) {
 231                 kfree(record->buf);
 232                 record->buf = NULL;
 233         }
 234         return size;
 235 }
 236
 237 static int efi_pstore_write(struct pstore_record *record)
 238 {
 239         char name[DUMP_NAME_LEN];
 240         efi_char16_t efi_name[DUMP_NAME_LEN];
 241         efi_guid_t vendor = LINUX_EFI_CRASH_GUID;
 242         int i, ret = 0;
 243
 244         snprintf(name, sizeof(name), "dump-type%u-%u-%d-%lu-%c",
 245                  record->type, record->part, record->count,
 246                  get_seconds(), record->compressed ? 'C' : 'D');
 247
 248         for (i = 0; i < DUMP_NAME_LEN; i++)
 249                 efi_name[i] = name[i];
 250
 251         ret = efivar_entry_set_safe(efi_name, vendor, PSTORE_EFI_ATTRIBUTES,
 252                               !pstore_cannot_block_path(record->reason),
 253                               record->size, record->psi->buf);
 254
 255         if (record->reason == KMSG_DUMP_OOPS)
 256                 efivar_run_worker();
 257
 258         record->id = record->part;
 259         return ret;
 260 };
 261
 262 struct pstore_erase_data {
 263         struct pstore_record *record;
 264         efi_char16_t *name;
 265 };
 266
 267 /*
 268  * Clean up an entry with the same name
 269  */
 270 static int efi_pstore_erase_func(struct efivar_entry *entry, void *data)
 271 {
 272         struct pstore_erase_data *ed = data;
 273         efi_guid_t vendor = LINUX_EFI_CRASH_GUID;
 274         efi_char16_t efi_name_old[DUMP_NAME_LEN];
 275         efi_char16_t *efi_name = ed->name;
 276         unsigned long ucs2_len = ucs2_strlen(ed->name);
 277         char name_old[DUMP_NAME_LEN];
 278         int i;
 279
 280         if (efi_guidcmp(entry->var.VendorGuid, vendor))
 281                 return 0;
 282
 283         if (ucs2_strncmp(entry->var.VariableName,
 284                           efi_name, (size_t)ucs2_len)) {
 285                 /*
 286                  * Check if an old format, which doesn't support
 287                  * holding multiple logs, remains.
 288                  */
 289                 snprintf(name_old, sizeof(name_old), "dump-type%u-%u-%lu",
 290                         ed->record->type, (unsigned int)ed->record->id,
 291                         ed->record->time.tv_sec);
 292
 293                 for (i = 0; i < DUMP_NAME_LEN; i++)
 294                         efi_name_old[i] = name_old[i];
 295
 296                 if (ucs2_strncmp(entry->var.VariableName, efi_name_old,
 297                                   ucs2_strlen(efi_name_old)))
 298                         return 0;
 299         }
 300
 301         if (entry->scanning) {
 302                 /*
 303                  * Skip deletion because this entry will be deleted
 304                  * after scanning is completed.
 305                  */
 306                 entry->deleting = true;
 307         } else
 308                 list_del(&entry->list);
 309
 310         /* found */
 311         __efivar_entry_delete(entry);
 312
 313         return 1;
 314 }
 315
 316 static int efi_pstore_erase(struct pstore_record *record)
 317 {
 318         struct pstore_erase_data edata;
 319         struct efivar_entry *entry = NULL;
 320         char name[DUMP_NAME_LEN];
 321         efi_char16_t efi_name[DUMP_NAME_LEN];
 322         int found, i;
 323         unsigned int part;
 324
 325         do_div(record->id, 1000);
 326         part = do_div(record->id, 100);
 327         snprintf(name, sizeof(name), "dump-type%u-%u-%d-%lu",
 328                  record->type, record->part, record->count,
 329                  record->time.tv_sec);
 330
 331         for (i = 0; i < DUMP_NAME_LEN; i++)
 332                 efi_name[i] = name[i];
 333
 334         edata.record = record;
 335         edata.name = efi_name;
 336
 337         if (efivar_entry_iter_begin())
 338                 return -EINTR;
 339         found = __efivar_entry_iter(efi_pstore_erase_func, &efivar_sysfs_list, &edata, &entry);
 340
 341         if (found && !entry->scanning) {
 342                 efivar_entry_iter_end();
 343                 efivar_unregister(entry);
 344         } else
 345                 efivar_entry_iter_end();
 346
 347         return 0;
 348 }
 349
 350 static struct pstore_info efi_pstore_info = {
 351         .owner          = THIS_MODULE,
 352         .name           = "efi",
 353         .flags          = PSTORE_FLAGS_DMESG,
 354         .open           = efi_pstore_open,
 355         .close          = efi_pstore_close,
 356         .read           = efi_pstore_read,
 357         .write          = efi_pstore_write,
 358         .erase          = efi_pstore_erase,
 359 };
 360
 361 static __init int efivars_pstore_init(void)
 362 {
 363         if (!efi_enabled(EFI_RUNTIME_SERVICES))
 364                 return 0;
 365
 366         if (!efivars_kobject())
 367                 return 0;
 368
 369         if (efivars_pstore_disable)
 370                 return 0;
 371
 372         efi_pstore_info.buf = kmalloc(4096, GFP_KERNEL);
 373         if (!efi_pstore_info.buf)
 374                 return -ENOMEM;
 375
 376         efi_pstore_info.bufsize = 1024;
 377         spin_lock_init(&efi_pstore_info.buf_lock);
 378
 379         if (pstore_register(&efi_pstore_info)) {
 380                 kfree(efi_pstore_info.buf);
 381                 efi_pstore_info.buf = NULL;
 382                 efi_pstore_info.bufsize = 0;
 383         }
 384
 385         return 0;
 386 }
 387
 388 static __exit void efivars_pstore_exit(void)
 389 {
 390         if (!efi_pstore_info.bufsize)
 391                 return;
 392
 393         pstore_unregister(&efi_pstore_info);
 394         kfree(efi_pstore_info.buf);
 395         efi_pstore_info.buf = NULL;
 396         efi_pstore_info.bufsize = 0;
 397 }
 398
 399 module_init(efivars_pstore_init);
 400 module_exit(efivars_pstore_exit);
 401
 402 MODULE_DESCRIPTION("EFI variable backend for pstore");
 403 MODULE_LICENSE("GPL");
 404 MODULE_ALIAS("platform:efivars");