efi-pstore.c 11 KB

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  1. // SPDX-License-Identifier: GPL-2.0+
  2. #include <linux/efi.h>
  3. #include <linux/module.h>
  4. #include <linux/pstore.h>
  5. #include <linux/slab.h>
  6. #include <linux/ucs2_string.h>
  7. #define DUMP_NAME_LEN 66
  8. #define EFIVARS_DATA_SIZE_MAX 1024
  9. static bool efivars_pstore_disable =
  10. IS_ENABLED(CONFIG_EFI_VARS_PSTORE_DEFAULT_DISABLE);
  11. module_param_named(pstore_disable, efivars_pstore_disable, bool, 0644);
  12. #define PSTORE_EFI_ATTRIBUTES \
  13. (EFI_VARIABLE_NON_VOLATILE | \
  14. EFI_VARIABLE_BOOTSERVICE_ACCESS | \
  15. EFI_VARIABLE_RUNTIME_ACCESS)
  16. static LIST_HEAD(efi_pstore_list);
  17. static DECLARE_WORK(efivar_work, NULL);
  18. static int efi_pstore_open(struct pstore_info *psi)
  19. {
  20. psi->data = NULL;
  21. return 0;
  22. }
  23. static int efi_pstore_close(struct pstore_info *psi)
  24. {
  25. psi->data = NULL;
  26. return 0;
  27. }
  28. static inline u64 generic_id(u64 timestamp, unsigned int part, int count)
  29. {
  30. return (timestamp * 100 + part) * 1000 + count;
  31. }
  32. static int efi_pstore_read_func(struct efivar_entry *entry,
  33. struct pstore_record *record)
  34. {
  35. efi_guid_t vendor = LINUX_EFI_CRASH_GUID;
  36. char name[DUMP_NAME_LEN], data_type;
  37. int i;
  38. int cnt;
  39. unsigned int part;
  40. unsigned long size;
  41. u64 time;
  42. if (efi_guidcmp(entry->var.VendorGuid, vendor))
  43. return 0;
  44. for (i = 0; i < DUMP_NAME_LEN; i++)
  45. name[i] = entry->var.VariableName[i];
  46. if (sscanf(name, "dump-type%u-%u-%d-%llu-%c",
  47. &record->type, &part, &cnt, &time, &data_type) == 5) {
  48. record->id = generic_id(time, part, cnt);
  49. record->part = part;
  50. record->count = cnt;
  51. record->time.tv_sec = time;
  52. record->time.tv_nsec = 0;
  53. if (data_type == 'C')
  54. record->compressed = true;
  55. else
  56. record->compressed = false;
  57. record->ecc_notice_size = 0;
  58. } else if (sscanf(name, "dump-type%u-%u-%d-%llu",
  59. &record->type, &part, &cnt, &time) == 4) {
  60. record->id = generic_id(time, part, cnt);
  61. record->part = part;
  62. record->count = cnt;
  63. record->time.tv_sec = time;
  64. record->time.tv_nsec = 0;
  65. record->compressed = false;
  66. record->ecc_notice_size = 0;
  67. } else if (sscanf(name, "dump-type%u-%u-%llu",
  68. &record->type, &part, &time) == 3) {
  69. /*
  70. * Check if an old format,
  71. * which doesn't support holding
  72. * multiple logs, remains.
  73. */
  74. record->id = generic_id(time, part, 0);
  75. record->part = part;
  76. record->count = 0;
  77. record->time.tv_sec = time;
  78. record->time.tv_nsec = 0;
  79. record->compressed = false;
  80. record->ecc_notice_size = 0;
  81. } else
  82. return 0;
  83. entry->var.DataSize = 1024;
  84. __efivar_entry_get(entry, &entry->var.Attributes,
  85. &entry->var.DataSize, entry->var.Data);
  86. size = entry->var.DataSize;
  87. memcpy(record->buf, entry->var.Data,
  88. (size_t)min_t(unsigned long, EFIVARS_DATA_SIZE_MAX, size));
  89. return size;
  90. }
  91. /**
  92. * efi_pstore_scan_sysfs_enter
  93. * @pos: scanning entry
  94. * @next: next entry
  95. * @head: list head
  96. */
  97. static void efi_pstore_scan_sysfs_enter(struct efivar_entry *pos,
  98. struct efivar_entry *next,
  99. struct list_head *head)
  100. {
  101. pos->scanning = true;
  102. if (&next->list != head)
  103. next->scanning = true;
  104. }
  105. /**
  106. * __efi_pstore_scan_sysfs_exit
  107. * @entry: deleting entry
  108. * @turn_off_scanning: Check if a scanning flag should be turned off
  109. */
  110. static inline int __efi_pstore_scan_sysfs_exit(struct efivar_entry *entry,
  111. bool turn_off_scanning)
  112. {
  113. if (entry->deleting) {
  114. list_del(&entry->list);
  115. efivar_entry_iter_end();
  116. kfree(entry);
  117. if (efivar_entry_iter_begin())
  118. return -EINTR;
  119. } else if (turn_off_scanning)
  120. entry->scanning = false;
  121. return 0;
  122. }
  123. /**
  124. * efi_pstore_scan_sysfs_exit
  125. * @pos: scanning entry
  126. * @next: next entry
  127. * @head: list head
  128. * @stop: a flag checking if scanning will stop
  129. */
  130. static int efi_pstore_scan_sysfs_exit(struct efivar_entry *pos,
  131. struct efivar_entry *next,
  132. struct list_head *head, bool stop)
  133. {
  134. int ret = __efi_pstore_scan_sysfs_exit(pos, true);
  135. if (ret)
  136. return ret;
  137. if (stop)
  138. ret = __efi_pstore_scan_sysfs_exit(next, &next->list != head);
  139. return ret;
  140. }
  141. /**
  142. * efi_pstore_sysfs_entry_iter
  143. *
  144. * @record: pstore record to pass to callback
  145. *
  146. * You MUST call efivar_entry_iter_begin() before this function, and
  147. * efivar_entry_iter_end() afterwards.
  148. *
  149. */
  150. static int efi_pstore_sysfs_entry_iter(struct pstore_record *record)
  151. {
  152. struct efivar_entry **pos = (struct efivar_entry **)&record->psi->data;
  153. struct efivar_entry *entry, *n;
  154. struct list_head *head = &efi_pstore_list;
  155. int size = 0;
  156. int ret;
  157. if (!*pos) {
  158. list_for_each_entry_safe(entry, n, head, list) {
  159. efi_pstore_scan_sysfs_enter(entry, n, head);
  160. size = efi_pstore_read_func(entry, record);
  161. ret = efi_pstore_scan_sysfs_exit(entry, n, head,
  162. size < 0);
  163. if (ret)
  164. return ret;
  165. if (size)
  166. break;
  167. }
  168. *pos = n;
  169. return size;
  170. }
  171. list_for_each_entry_safe_from((*pos), n, head, list) {
  172. efi_pstore_scan_sysfs_enter((*pos), n, head);
  173. size = efi_pstore_read_func((*pos), record);
  174. ret = efi_pstore_scan_sysfs_exit((*pos), n, head, size < 0);
  175. if (ret)
  176. return ret;
  177. if (size)
  178. break;
  179. }
  180. *pos = n;
  181. return size;
  182. }
  183. /**
  184. * efi_pstore_read
  185. *
  186. * This function returns a size of NVRAM entry logged via efi_pstore_write().
  187. * The meaning and behavior of efi_pstore/pstore are as below.
  188. *
  189. * size > 0: Got data of an entry logged via efi_pstore_write() successfully,
  190. * and pstore filesystem will continue reading subsequent entries.
  191. * size == 0: Entry was not logged via efi_pstore_write(),
  192. * and efi_pstore driver will continue reading subsequent entries.
  193. * size < 0: Failed to get data of entry logging via efi_pstore_write(),
  194. * and pstore will stop reading entry.
  195. */
  196. static ssize_t efi_pstore_read(struct pstore_record *record)
  197. {
  198. ssize_t size;
  199. record->buf = kzalloc(EFIVARS_DATA_SIZE_MAX, GFP_KERNEL);
  200. if (!record->buf)
  201. return -ENOMEM;
  202. if (efivar_entry_iter_begin()) {
  203. size = -EINTR;
  204. goto out;
  205. }
  206. size = efi_pstore_sysfs_entry_iter(record);
  207. efivar_entry_iter_end();
  208. out:
  209. if (size <= 0) {
  210. kfree(record->buf);
  211. record->buf = NULL;
  212. }
  213. return size;
  214. }
  215. static int efi_pstore_write(struct pstore_record *record)
  216. {
  217. char name[DUMP_NAME_LEN];
  218. efi_char16_t efi_name[DUMP_NAME_LEN];
  219. efi_guid_t vendor = LINUX_EFI_CRASH_GUID;
  220. int i, ret = 0;
  221. record->id = generic_id(record->time.tv_sec, record->part,
  222. record->count);
  223. /* Since we copy the entire length of name, make sure it is wiped. */
  224. memset(name, 0, sizeof(name));
  225. snprintf(name, sizeof(name), "dump-type%u-%u-%d-%lld-%c",
  226. record->type, record->part, record->count,
  227. (long long)record->time.tv_sec,
  228. record->compressed ? 'C' : 'D');
  229. for (i = 0; i < DUMP_NAME_LEN; i++)
  230. efi_name[i] = name[i];
  231. ret = efivar_entry_set_safe(efi_name, vendor, PSTORE_EFI_ATTRIBUTES,
  232. preemptible(), record->size, record->psi->buf);
  233. if (record->reason == KMSG_DUMP_OOPS && try_module_get(THIS_MODULE))
  234. if (!schedule_work(&efivar_work))
  235. module_put(THIS_MODULE);
  236. return ret;
  237. };
  238. /*
  239. * Clean up an entry with the same name
  240. */
  241. static int efi_pstore_erase_func(struct efivar_entry *entry, void *data)
  242. {
  243. efi_char16_t *efi_name = data;
  244. efi_guid_t vendor = LINUX_EFI_CRASH_GUID;
  245. unsigned long ucs2_len = ucs2_strlen(efi_name);
  246. if (efi_guidcmp(entry->var.VendorGuid, vendor))
  247. return 0;
  248. if (ucs2_strncmp(entry->var.VariableName, efi_name, (size_t)ucs2_len))
  249. return 0;
  250. if (entry->scanning) {
  251. /*
  252. * Skip deletion because this entry will be deleted
  253. * after scanning is completed.
  254. */
  255. entry->deleting = true;
  256. } else
  257. list_del(&entry->list);
  258. /* found */
  259. __efivar_entry_delete(entry);
  260. return 1;
  261. }
  262. static int efi_pstore_erase_name(const char *name)
  263. {
  264. struct efivar_entry *entry = NULL;
  265. efi_char16_t efi_name[DUMP_NAME_LEN];
  266. int found, i;
  267. for (i = 0; i < DUMP_NAME_LEN; i++) {
  268. efi_name[i] = name[i];
  269. if (name[i] == '\0')
  270. break;
  271. }
  272. if (efivar_entry_iter_begin())
  273. return -EINTR;
  274. found = __efivar_entry_iter(efi_pstore_erase_func, &efi_pstore_list,
  275. efi_name, &entry);
  276. efivar_entry_iter_end();
  277. if (found && !entry->scanning)
  278. kfree(entry);
  279. return found ? 0 : -ENOENT;
  280. }
  281. static int efi_pstore_erase(struct pstore_record *record)
  282. {
  283. char name[DUMP_NAME_LEN];
  284. int ret;
  285. snprintf(name, sizeof(name), "dump-type%u-%u-%d-%lld",
  286. record->type, record->part, record->count,
  287. (long long)record->time.tv_sec);
  288. ret = efi_pstore_erase_name(name);
  289. if (ret != -ENOENT)
  290. return ret;
  291. snprintf(name, sizeof(name), "dump-type%u-%u-%lld",
  292. record->type, record->part, (long long)record->time.tv_sec);
  293. ret = efi_pstore_erase_name(name);
  294. return ret;
  295. }
  296. static struct pstore_info efi_pstore_info = {
  297. .owner = THIS_MODULE,
  298. .name = "efi",
  299. .flags = PSTORE_FLAGS_DMESG,
  300. .open = efi_pstore_open,
  301. .close = efi_pstore_close,
  302. .read = efi_pstore_read,
  303. .write = efi_pstore_write,
  304. .erase = efi_pstore_erase,
  305. };
  306. static int efi_pstore_callback(efi_char16_t *name, efi_guid_t vendor,
  307. unsigned long name_size, void *data)
  308. {
  309. struct efivar_entry *entry;
  310. int ret;
  311. entry = kzalloc(sizeof(*entry), GFP_KERNEL);
  312. if (!entry)
  313. return -ENOMEM;
  314. memcpy(entry->var.VariableName, name, name_size);
  315. entry->var.VendorGuid = vendor;
  316. ret = efivar_entry_add(entry, &efi_pstore_list);
  317. if (ret)
  318. kfree(entry);
  319. return ret;
  320. }
  321. static int efi_pstore_update_entry(efi_char16_t *name, efi_guid_t vendor,
  322. unsigned long name_size, void *data)
  323. {
  324. struct efivar_entry *entry = data;
  325. if (efivar_entry_find(name, vendor, &efi_pstore_list, false))
  326. return 0;
  327. memcpy(entry->var.VariableName, name, name_size);
  328. memcpy(&(entry->var.VendorGuid), &vendor, sizeof(efi_guid_t));
  329. return 1;
  330. }
  331. static void efi_pstore_update_entries(struct work_struct *work)
  332. {
  333. struct efivar_entry *entry;
  334. int err;
  335. /* Add new sysfs entries */
  336. while (1) {
  337. entry = kzalloc(sizeof(*entry), GFP_KERNEL);
  338. if (!entry)
  339. return;
  340. err = efivar_init(efi_pstore_update_entry, entry,
  341. false, &efi_pstore_list);
  342. if (!err)
  343. break;
  344. efivar_entry_add(entry, &efi_pstore_list);
  345. }
  346. kfree(entry);
  347. module_put(THIS_MODULE);
  348. }
  349. static __init int efivars_pstore_init(void)
  350. {
  351. int ret;
  352. if (!efivars_kobject() || !efivar_supports_writes())
  353. return 0;
  354. if (efivars_pstore_disable)
  355. return 0;
  356. ret = efivar_init(efi_pstore_callback, NULL, true, &efi_pstore_list);
  357. if (ret)
  358. return ret;
  359. efi_pstore_info.buf = kmalloc(4096, GFP_KERNEL);
  360. if (!efi_pstore_info.buf)
  361. return -ENOMEM;
  362. efi_pstore_info.bufsize = 1024;
  363. if (pstore_register(&efi_pstore_info)) {
  364. kfree(efi_pstore_info.buf);
  365. efi_pstore_info.buf = NULL;
  366. efi_pstore_info.bufsize = 0;
  367. }
  368. INIT_WORK(&efivar_work, efi_pstore_update_entries);
  369. return 0;
  370. }
  371. static __exit void efivars_pstore_exit(void)
  372. {
  373. if (!efi_pstore_info.bufsize)
  374. return;
  375. pstore_unregister(&efi_pstore_info);
  376. kfree(efi_pstore_info.buf);
  377. efi_pstore_info.buf = NULL;
  378. efi_pstore_info.bufsize = 0;
  379. }
  380. module_init(efivars_pstore_init);
  381. module_exit(efivars_pstore_exit);
  382. MODULE_DESCRIPTION("EFI variable backend for pstore");
  383. MODULE_LICENSE("GPL");
  384. MODULE_ALIAS("platform:efivars");