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 void __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                 efivar_entry_iter_begin();
 136         } else if (turn_off_scanning)
 137                 entry->scanning = false;
 138 }
 139
 140 /**
 141  * efi_pstore_scan_sysfs_exit
 142  * @pos: scanning entry
 143  * @next: next entry
 144  * @head: list head
 145  * @stop: a flag checking if scanning will stop
 146  */
 147 static void efi_pstore_scan_sysfs_exit(struct efivar_entry *pos,
 148                                        struct efivar_entry *next,
 149                                        struct list_head *head, bool stop)
 150 {
 151         __efi_pstore_scan_sysfs_exit(pos, true);
 152         if (stop)
 153                 __efi_pstore_scan_sysfs_exit(next, &next->list != head);
 154 }
 155
 156 /**
 157  * efi_pstore_sysfs_entry_iter
 158  *
 159  * @data: function-specific data to pass to callback
 160  * @pos: entry to begin iterating from
 161  *
 162  * You MUST call efivar_enter_iter_begin() before this function, and
 163  * efivar_entry_iter_end() afterwards.
 164  *
 165  * It is possible to begin iteration from an arbitrary entry within
 166  * the list by passing @pos. @pos is updated on return to point to
 167  * the next entry of the last one passed to efi_pstore_read_func().
 168  * To begin iterating from the beginning of the list @pos must be %NULL.
 169  */
 170 static int efi_pstore_sysfs_entry_iter(void *data, struct efivar_entry **pos)
 171 {
 172         struct efivar_entry *entry, *n;
 173         struct list_head *head = &efivar_sysfs_list;
 174         int size = 0;
 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, data);
 181                         efi_pstore_scan_sysfs_exit(entry, n, head, size < 0);
 182                         if (size)
 183                                 break;
 184                 }
 185                 *pos = n;
 186                 return size;
 187         }
 188
 189         list_for_each_entry_safe_from((*pos), n, head, list) {
 190                 efi_pstore_scan_sysfs_enter((*pos), n, head);
 191
 192                 size = efi_pstore_read_func((*pos), data);
 193                 efi_pstore_scan_sysfs_exit((*pos), n, head, size < 0);
 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(u64 *id, enum pstore_type_id *type,
 215                                int *count, struct timespec *timespec,
 216                                char **buf, bool *compressed,
 217                                ssize_t *ecc_notice_size,
 218                                struct pstore_info *psi)
 219 {
 220         struct pstore_read_data data;
 221         ssize_t size;
 222
 223         data.id = id;
 224         data.type = type;
 225         data.count = count;
 226         data.timespec = timespec;
 227         data.compressed = compressed;
 228         data.ecc_notice_size = ecc_notice_size;
 229         data.buf = buf;
 230
 231         *data.buf = kzalloc(EFIVARS_DATA_SIZE_MAX, GFP_KERNEL);
 232         if (!*data.buf)
 233                 return -ENOMEM;
 234
 235         efivar_entry_iter_begin();
 236         size = efi_pstore_sysfs_entry_iter(&data,
 237                                            (struct efivar_entry **)&psi->data);
 238         efivar_entry_iter_end();
 239         if (size <= 0)
 240                 kfree(*data.buf);
 241         return size;
 242 }
 243
 244 static int efi_pstore_write(enum pstore_type_id type,
 245                 enum kmsg_dump_reason reason, u64 *id,
 246                 unsigned int part, int count, bool compressed, size_t size,
 247                 struct pstore_info *psi)
 248 {
 249         char name[DUMP_NAME_LEN];
 250         efi_char16_t efi_name[DUMP_NAME_LEN];
 251         efi_guid_t vendor = LINUX_EFI_CRASH_GUID;
 252         int i, ret = 0;
 253
 254         sprintf(name, "dump-type%u-%u-%d-%lu-%c", type, part, count,
 255                 get_seconds(), compressed ? 'C' : 'D');
 256
 257         for (i = 0; i < DUMP_NAME_LEN; i++)
 258                 efi_name[i] = name[i];
 259
 260         efivar_entry_set_safe(efi_name, vendor, PSTORE_EFI_ATTRIBUTES,
 261                               !pstore_cannot_block_path(reason),
 262                               size, psi->buf);
 263
 264         if (reason == KMSG_DUMP_OOPS)
 265                 efivar_run_worker();
 266
 267         *id = part;
 268         return ret;
 269 };
 270
 271 struct pstore_erase_data {
 272         u64 id;
 273         enum pstore_type_id type;
 274         int count;
 275         struct timespec time;
 276         efi_char16_t *name;
 277 };
 278
 279 /*
 280  * Clean up an entry with the same name
 281  */
 282 static int efi_pstore_erase_func(struct efivar_entry *entry, void *data)
 283 {
 284         struct pstore_erase_data *ed = data;
 285         efi_guid_t vendor = LINUX_EFI_CRASH_GUID;
 286         efi_char16_t efi_name_old[DUMP_NAME_LEN];
 287         efi_char16_t *efi_name = ed->name;
 288         unsigned long ucs2_len = ucs2_strlen(ed->name);
 289         char name_old[DUMP_NAME_LEN];
 290         int i;
 291
 292         if (efi_guidcmp(entry->var.VendorGuid, vendor))
 293                 return 0;
 294
 295         if (ucs2_strncmp(entry->var.VariableName,
 296                           efi_name, (size_t)ucs2_len)) {
 297                 /*
 298                  * Check if an old format, which doesn't support
 299                  * holding multiple logs, remains.
 300                  */
 301                 sprintf(name_old, "dump-type%u-%u-%lu", ed->type,
 302                         (unsigned int)ed->id, ed->time.tv_sec);
 303
 304                 for (i = 0; i < DUMP_NAME_LEN; i++)
 305                         efi_name_old[i] = name_old[i];
 306
 307                 if (ucs2_strncmp(entry->var.VariableName, efi_name_old,
 308                                   ucs2_strlen(efi_name_old)))
 309                         return 0;
 310         }
 311
 312         if (entry->scanning) {
 313                 /*
 314                  * Skip deletion because this entry will be deleted
 315                  * after scanning is completed.
 316                  */
 317                 entry->deleting = true;
 318         } else
 319                 list_del(&entry->list);
 320
 321         /* found */
 322         __efivar_entry_delete(entry);
 323
 324         return 1;
 325 }
 326
 327 static int efi_pstore_erase(enum pstore_type_id type, u64 id, int count,
 328                             struct timespec time, struct pstore_info *psi)
 329 {
 330         struct pstore_erase_data edata;
 331         struct efivar_entry *entry = NULL;
 332         char name[DUMP_NAME_LEN];
 333         efi_char16_t efi_name[DUMP_NAME_LEN];
 334         int found, i;
 335         unsigned int part;
 336
 337         do_div(id, 1000);
 338         part = do_div(id, 100);
 339         sprintf(name, "dump-type%u-%u-%d-%lu", type, part, count, time.tv_sec);
 340
 341         for (i = 0; i < DUMP_NAME_LEN; i++)
 342                 efi_name[i] = name[i];
 343
 344         edata.id = part;
 345         edata.type = type;
 346         edata.count = count;
 347         edata.time = time;
 348         edata.name = efi_name;
 349
 350         efivar_entry_iter_begin();
 351         found = __efivar_entry_iter(efi_pstore_erase_func, &efivar_sysfs_list, &edata, &entry);
 352
 353         if (found && !entry->scanning) {
 354                 efivar_entry_iter_end();
 355                 efivar_unregister(entry);
 356         } else
 357                 efivar_entry_iter_end();
 358
 359         return 0;
 360 }
 361
 362 static struct pstore_info efi_pstore_info = {
 363         .owner          = THIS_MODULE,
 364         .name           = "efi",
 365         .flags          = PSTORE_FLAGS_DMESG,
 366         .open           = efi_pstore_open,
 367         .close          = efi_pstore_close,
 368         .read           = efi_pstore_read,
 369         .write          = efi_pstore_write,
 370         .erase          = efi_pstore_erase,
 371 };
 372
 373 static __init int efivars_pstore_init(void)
 374 {
 375         if (!efi_enabled(EFI_RUNTIME_SERVICES))
 376                 return 0;
 377
 378         if (!efivars_kobject())
 379                 return 0;
 380
 381         if (efivars_pstore_disable)
 382                 return 0;
 383
 384         efi_pstore_info.buf = kmalloc(4096, GFP_KERNEL);
 385         if (!efi_pstore_info.buf)
 386                 return -ENOMEM;
 387
 388         efi_pstore_info.bufsize = 1024;
 389         spin_lock_init(&efi_pstore_info.buf_lock);
 390
 391         if (pstore_register(&efi_pstore_info)) {
 392                 kfree(efi_pstore_info.buf);
 393                 efi_pstore_info.buf = NULL;
 394                 efi_pstore_info.bufsize = 0;
 395         }
 396
 397         return 0;
 398 }
 399
 400 static __exit void efivars_pstore_exit(void)
 401 {
 402         if (!efi_pstore_info.bufsize)
 403                 return;
 404
 405         pstore_unregister(&efi_pstore_info);
 406         kfree(efi_pstore_info.buf);
 407         efi_pstore_info.buf = NULL;
 408         efi_pstore_info.bufsize = 0;
 409 }
 410
 411 module_init(efivars_pstore_init);
 412 module_exit(efivars_pstore_exit);
 413
 414 MODULE_DESCRIPTION("EFI variable backend for pstore");
 415 MODULE_LICENSE("GPL");
 416 MODULE_ALIAS("platform:efivars");