aboutsummaryrefslogtreecommitdiff
path: root/drivers/firmware/efi/efi-pstore.c
blob: 4b9dc836dcf956e86c3800398946d40b0d1cf6dc (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
#include <linux/efi.h>
#include <linux/module.h>
#include <linux/pstore.h>
#include <linux/slab.h>
#include <linux/ucs2_string.h>

#define DUMP_NAME_LEN 52

static bool efivars_pstore_disable =
	IS_ENABLED(CONFIG_EFI_VARS_PSTORE_DEFAULT_DISABLE);

module_param_named(pstore_disable, efivars_pstore_disable, bool, 0644);

#define PSTORE_EFI_ATTRIBUTES \
	(EFI_VARIABLE_NON_VOLATILE | \
	 EFI_VARIABLE_BOOTSERVICE_ACCESS | \
	 EFI_VARIABLE_RUNTIME_ACCESS)

static int efi_pstore_open(struct pstore_info *psi)
{
	psi->data = NULL;
	return 0;
}

static int efi_pstore_close(struct pstore_info *psi)
{
	psi->data = NULL;
	return 0;
}

struct pstore_read_data {
	u64 *id;
	enum pstore_type_id *type;
	int *count;
	struct timespec *timespec;
	bool *compressed;
	char **buf;
};

static inline u64 generic_id(unsigned long timestamp,
			     unsigned int part, int count)
{
	return (timestamp * 100 + part) * 1000 + count;
}

static int efi_pstore_read_func(struct efivar_entry *entry, void *data)
{
	efi_guid_t vendor = LINUX_EFI_CRASH_GUID;
	struct pstore_read_data *cb_data = data;
	char name[DUMP_NAME_LEN], data_type;
	int i;
	int cnt;
	unsigned int part;
	unsigned long time, size;

	if (efi_guidcmp(entry->var.VendorGuid, vendor))
		return 0;

	for (i = 0; i < DUMP_NAME_LEN; i++)
		name[i] = entry->var.VariableName[i];

	if (sscanf(name, "dump-type%u-%u-%d-%lu-%c",
		   cb_data->type, &part, &cnt, &time, &data_type) == 5) {
		*cb_data->id = generic_id(time, part, cnt);
		*cb_data->count = cnt;
		cb_data->timespec->tv_sec = time;
		cb_data->timespec->tv_nsec = 0;
		if (data_type == 'C')
			*cb_data->compressed = true;
		else
			*cb_data->compressed = false;
	} else if (sscanf(name, "dump-type%u-%u-%d-%lu",
		   cb_data->type, &part, &cnt, &time) == 4) {
		*cb_data->id = generic_id(time, part, cnt);
		*cb_data->count = cnt;
		cb_data->timespec->tv_sec = time;
		cb_data->timespec->tv_nsec = 0;
		*cb_data->compressed = false;
	} else if (sscanf(name, "dump-type%u-%u-%lu",
			  cb_data->type, &part, &time) == 3) {
		/*
		 * Check if an old format,
		 * which doesn't support holding
		 * multiple logs, remains.
		 */
		*cb_data->id = generic_id(time, part, 0);
		*cb_data->count = 0;
		cb_data->timespec->tv_sec = time;
		cb_data->timespec->tv_nsec = 0;
		*cb_data->compressed = false;
	} else
		return 0;

	entry->var.DataSize = 1024;
	__efivar_entry_get(entry, &entry->var.Attributes,
			   &entry->var.DataSize, entry->var.Data);
	size = entry->var.DataSize;
	memcpy(*cb_data->buf, entry->var.Data,
	       (size_t)min_t(unsigned long, EFIVARS_DATA_SIZE_MAX, size));

	return size;
}

/**
 * efi_pstore_scan_sysfs_enter
 * @entry: scanning entry
 * @next: next entry
 * @head: list head
 */
static void efi_pstore_scan_sysfs_enter(struct efivar_entry *pos,
					struct efivar_entry *next,
					struct list_head *head)
{
	pos->scanning = true;
	if (&next->list != head)
		next->scanning = true;
}

/**
 * __efi_pstore_scan_sysfs_exit
 * @entry: deleting entry
 * @turn_off_scanning: Check if a scanning flag should be turned off
 */
static inline void __efi_pstore_scan_sysfs_exit(struct efivar_entry *entry,
						bool turn_off_scanning)
{
	if (entry->deleting) {
		list_del(&entry->list);
		efivar_entry_iter_end();
		efivar_unregister(entry);
		efivar_entry_iter_begin();
	} else if (turn_off_scanning)
		entry->scanning = false;
}

/**
 * efi_pstore_scan_sysfs_exit
 * @pos: scanning entry
 * @next: next entry
 * @head: list head
 * @stop: a flag checking if scanning will stop
 */
static void efi_pstore_scan_sysfs_exit(struct efivar_entry *pos,
				       struct efivar_entry *next,
				       struct list_head *head, bool stop)
{
	__efi_pstore_scan_sysfs_exit(pos, true);
	if (stop)
		__efi_pstore_scan_sysfs_exit(next, &next->list != head);
}

/**
 * efi_pstore_sysfs_entry_iter
 *
 * @data: function-specific data to pass to callback
 * @pos: entry to begin iterating from
 *
 * You MUST call efivar_enter_iter_begin() before this function, and
 * efivar_entry_iter_end() afterwards.
 *
 * It is possible to begin iteration from an arbitrary entry within
 * the list by passing @pos. @pos is updated on return to point to
 * the next entry of the last one passed to efi_pstore_read_func().
 * To begin iterating from the beginning of the list @pos must be %NULL.
 */
static int efi_pstore_sysfs_entry_iter(void *data, struct efivar_entry **pos)
{
	struct efivar_entry *entry, *n;
	struct list_head *head = &efivar_sysfs_list;
	int size = 0;

	if (!*pos) {
		list_for_each_entry_safe(entry, n, head, list) {
			efi_pstore_scan_sysfs_enter(entry, n, head);

			size = efi_pstore_read_func(entry, data);
			efi_pstore_scan_sysfs_exit(entry, n, head, size < 0);
			if (size)
				break;
		}
		*pos = n;
		return size;
	}

	list_for_each_entry_safe_from((*pos), n, head, list) {
		efi_pstore_scan_sysfs_enter((*pos), n, head);

		size = efi_pstore_read_func((*pos), data);
		efi_pstore_scan_sysfs_exit((*pos), n, head, size < 0);
		if (size)
			break;
	}
	*pos = n;
	return size;
}

/**
 * efi_pstore_read
 *
 * This function returns a size of NVRAM entry logged via efi_pstore_write().
 * The meaning and behavior of efi_pstore/pstore are as below.
 *
 * size > 0: Got data of an entry logged via efi_pstore_write() successfully,
 *           and pstore filesystem will continue reading subsequent entries.
 * size == 0: Entry was not logged via efi_pstore_write(),
 *            and efi_pstore driver will continue reading subsequent entries.
 * size < 0: Failed to get data of entry logging via efi_pstore_write(),
 *           and pstore will stop reading entry.
 */
static ssize_t efi_pstore_read(u64 *id, enum pstore_type_id *type,
			       int *count, struct timespec *timespec,
			       char **buf, bool *compressed,
			       struct pstore_info *psi)
{
	struct pstore_read_data data;
	ssize_t size;

	data.id = id;
	data.type = type;
	data.count = count;
	data.timespec = timespec;
	data.compressed = compressed;
	data.buf = buf;

	*data.buf = kzalloc(EFIVARS_DATA_SIZE_MAX, GFP_KERNEL);
	if (!*data.buf)
		return -ENOMEM;

	efivar_entry_iter_begin();
	size = efi_pstore_sysfs_entry_iter(&data,
					   (struct efivar_entry **)&psi->data);
	efivar_entry_iter_end();
	if (size <= 0)
		kfree(*data.buf);
	return size;
}

static int efi_pstore_write(enum pstore_type_id type,
		enum kmsg_dump_reason reason, u64 *id,
		unsigned int part, int count, bool compressed, size_t size,
		struct pstore_info *psi)
{
	char name[DUMP_NAME_LEN];
	efi_char16_t efi_name[DUMP_NAME_LEN];
	efi_guid_t vendor = LINUX_EFI_CRASH_GUID;
	int i, ret = 0;

	sprintf(name, "dump-type%u-%u-%d-%lu-%c", type, part, count,
		get_seconds(), compressed ? 'C' : 'D');

	for (i = 0; i < DUMP_NAME_LEN; i++)
		efi_name[i] = name[i];

	efivar_entry_set_safe(efi_name, vendor, PSTORE_EFI_ATTRIBUTES,
			      !pstore_cannot_block_path(reason),
			      size, psi->buf);

	if (reason == KMSG_DUMP_OOPS)
		efivar_run_worker();

	*id = part;
	return ret;
};

struct pstore_erase_data {
	u64 id;
	enum pstore_type_id type;
	int count;
	struct timespec time;
	efi_char16_t *name;
};

/*
 * Clean up an entry with the same name
 */
static int efi_pstore_erase_func(struct efivar_entry *entry, void *data)
{
	struct pstore_erase_data *ed = data;
	efi_guid_t vendor = LINUX_EFI_CRASH_GUID;
	efi_char16_t efi_name_old[DUMP_NAME_LEN];
	efi_char16_t *efi_name = ed->name;
	unsigned long ucs2_len = ucs2_strlen(ed->name);
	char name_old[DUMP_NAME_LEN];
	int i;

	if (efi_guidcmp(entry->var.VendorGuid, vendor))
		return 0;

	if (ucs2_strncmp(entry->var.VariableName,
			  efi_name, (size_t)ucs2_len)) {
		/*
		 * Check if an old format, which doesn't support
		 * holding multiple logs, remains.
		 */
		sprintf(name_old, "dump-type%u-%u-%lu", ed->type,
			(unsigned int)ed->id, ed->time.tv_sec);

		for (i = 0; i < DUMP_NAME_LEN; i++)
			efi_name_old[i] = name_old[i];

		if (ucs2_strncmp(entry->var.VariableName, efi_name_old,
				  ucs2_strlen(efi_name_old)))
			return 0;
	}

	if (entry->scanning) {
		/*
		 * Skip deletion because this entry will be deleted
		 * after scanning is completed.
		 */
		entry->deleting = true;
	} else
		list_del(&entry->list);

	/* found */
	__efivar_entry_delete(entry);

	return 1;
}

static int efi_pstore_erase(enum pstore_type_id type, u64 id, int count,
			    struct timespec time, struct pstore_info *psi)
{
	struct pstore_erase_data edata;
	struct efivar_entry *entry = NULL;
	char name[DUMP_NAME_LEN];
	efi_char16_t efi_name[DUMP_NAME_LEN];
	int found, i;
	unsigned int part;

	do_div(id, 1000);
	part = do_div(id, 100);
	sprintf(name, "dump-type%u-%u-%d-%lu", type, part, count, time.tv_sec);

	for (i = 0; i < DUMP_NAME_LEN; i++)
		efi_name[i] = name[i];

	edata.id = part;
	edata.type = type;
	edata.count = count;
	edata.time = time;
	edata.name = efi_name;

	efivar_entry_iter_begin();
	found = __efivar_entry_iter(efi_pstore_erase_func, &efivar_sysfs_list, &edata, &entry);

	if (found && !entry->scanning) {
		efivar_entry_iter_end();
		efivar_unregister(entry);
	} else
		efivar_entry_iter_end();

	return 0;
}

static struct pstore_info efi_pstore_info = {
	.owner		= THIS_MODULE,
	.name		= "efi",
	.flags		= PSTORE_FLAGS_FRAGILE,
	.open		= efi_pstore_open,
	.close		= efi_pstore_close,
	.read		= efi_pstore_read,
	.write		= efi_pstore_write,
	.erase		= efi_pstore_erase,
};

static __init int efivars_pstore_init(void)
{
	if (!efi_enabled(EFI_RUNTIME_SERVICES))
		return 0;

	if (!efivars_kobject())
		return 0;

	if (efivars_pstore_disable)
		return 0;

	efi_pstore_info.buf = kmalloc(4096, GFP_KERNEL);
	if (!efi_pstore_info.buf)
		return -ENOMEM;

	efi_pstore_info.bufsize = 1024;
	spin_lock_init(&efi_pstore_info.buf_lock);

	if (pstore_register(&efi_pstore_info)) {
		kfree(efi_pstore_info.buf);
		efi_pstore_info.buf = NULL;
		efi_pstore_info.bufsize = 0;
	}

	return 0;
}

static __exit void efivars_pstore_exit(void)
{
}

module_init(efivars_pstore_init);
module_exit(efivars_pstore_exit);

MODULE_DESCRIPTION("EFI variable backend for pstore");
MODULE_LICENSE("GPL");