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