xref: /linux/drivers/firmware/efi/efi-pstore.c (revision bb1c928df78ee6e3665a0d013e74108cc9abf34b)
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 			      !pstore_cannot_block_path(record->reason),
262 			      record->size, record->psi->buf);
263 
264 	if (record->reason == KMSG_DUMP_OOPS)
265 		efivar_run_worker();
266 
267 	return ret;
268 };
269 
270 /*
271  * Clean up an entry with the same name
272  */
273 static int efi_pstore_erase_func(struct efivar_entry *entry, void *data)
274 {
275 	efi_char16_t *efi_name = data;
276 	efi_guid_t vendor = LINUX_EFI_CRASH_GUID;
277 	unsigned long ucs2_len = ucs2_strlen(efi_name);
278 
279 	if (efi_guidcmp(entry->var.VendorGuid, vendor))
280 		return 0;
281 
282 	if (ucs2_strncmp(entry->var.VariableName, efi_name, (size_t)ucs2_len))
283 		return 0;
284 
285 	if (entry->scanning) {
286 		/*
287 		 * Skip deletion because this entry will be deleted
288 		 * after scanning is completed.
289 		 */
290 		entry->deleting = true;
291 	} else
292 		list_del(&entry->list);
293 
294 	/* found */
295 	__efivar_entry_delete(entry);
296 
297 	return 1;
298 }
299 
300 static int efi_pstore_erase_name(const char *name)
301 {
302 	struct efivar_entry *entry = NULL;
303 	efi_char16_t efi_name[DUMP_NAME_LEN];
304 	int found, i;
305 
306 	for (i = 0; i < DUMP_NAME_LEN; i++) {
307 		efi_name[i] = name[i];
308 		if (name[i] == '\0')
309 			break;
310 	}
311 
312 	if (efivar_entry_iter_begin())
313 		return -EINTR;
314 
315 	found = __efivar_entry_iter(efi_pstore_erase_func, &efivar_sysfs_list,
316 				    efi_name, &entry);
317 	efivar_entry_iter_end();
318 
319 	if (found && !entry->scanning)
320 		efivar_unregister(entry);
321 
322 	return found ? 0 : -ENOENT;
323 }
324 
325 static int efi_pstore_erase(struct pstore_record *record)
326 {
327 	char name[DUMP_NAME_LEN];
328 	int ret;
329 
330 	snprintf(name, sizeof(name), "dump-type%u-%u-%d-%lu",
331 		 record->type, record->part, record->count,
332 		 record->time.tv_sec);
333 	ret = efi_pstore_erase_name(name);
334 	if (ret != -ENOENT)
335 		return ret;
336 
337 	snprintf(name, sizeof(name), "dump-type%u-%u-%lu",
338 		record->type, record->part, record->time.tv_sec);
339 	ret = efi_pstore_erase_name(name);
340 
341 	return ret;
342 }
343 
344 static struct pstore_info efi_pstore_info = {
345 	.owner		= THIS_MODULE,
346 	.name		= "efi",
347 	.flags		= PSTORE_FLAGS_DMESG,
348 	.open		= efi_pstore_open,
349 	.close		= efi_pstore_close,
350 	.read		= efi_pstore_read,
351 	.write		= efi_pstore_write,
352 	.erase		= efi_pstore_erase,
353 };
354 
355 static __init int efivars_pstore_init(void)
356 {
357 	if (!efi_enabled(EFI_RUNTIME_SERVICES))
358 		return 0;
359 
360 	if (!efivars_kobject())
361 		return 0;
362 
363 	if (efivars_pstore_disable)
364 		return 0;
365 
366 	efi_pstore_info.buf = kmalloc(4096, GFP_KERNEL);
367 	if (!efi_pstore_info.buf)
368 		return -ENOMEM;
369 
370 	efi_pstore_info.bufsize = 1024;
371 	spin_lock_init(&efi_pstore_info.buf_lock);
372 
373 	if (pstore_register(&efi_pstore_info)) {
374 		kfree(efi_pstore_info.buf);
375 		efi_pstore_info.buf = NULL;
376 		efi_pstore_info.bufsize = 0;
377 	}
378 
379 	return 0;
380 }
381 
382 static __exit void efivars_pstore_exit(void)
383 {
384 	if (!efi_pstore_info.bufsize)
385 		return;
386 
387 	pstore_unregister(&efi_pstore_info);
388 	kfree(efi_pstore_info.buf);
389 	efi_pstore_info.buf = NULL;
390 	efi_pstore_info.bufsize = 0;
391 }
392 
393 module_init(efivars_pstore_init);
394 module_exit(efivars_pstore_exit);
395 
396 MODULE_DESCRIPTION("EFI variable backend for pstore");
397 MODULE_LICENSE("GPL");
398 MODULE_ALIAS("platform:efivars");
399