summaryrefslogtreecommitdiffstats
path: root/drivers/firmware/efivars.c
blob: 4202a31704673a9b938de84be1a8b581e3427067 (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
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
/*
 * EFI Variables - efivars.c
 *
 * Copyright (C) 2001,2003,2004 Dell <Matt_Domsch@dell.com>
 * Copyright (C) 2004 Intel Corporation <matthew.e.tolentino@intel.com>
 *
 * This code takes all variables accessible from EFI runtime and
 *  exports them via sysfs
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 * Changelog:
 *
 *  17 May 2004 - Matt Domsch <Matt_Domsch@dell.com>
 *   remove check for efi_enabled in exit
 *   add MODULE_VERSION
 *
 *  26 Apr 2004 - Matt Domsch <Matt_Domsch@dell.com>
 *   minor bug fixes
 *
 *  21 Apr 2004 - Matt Tolentino <matthew.e.tolentino@intel.com)
 *   converted driver to export variable information via sysfs
 *   and moved to drivers/firmware directory
 *   bumped revision number to v0.07 to reflect conversion & move
 *
 *  10 Dec 2002 - Matt Domsch <Matt_Domsch@dell.com>
 *   fix locking per Peter Chubb's findings
 *
 *  25 Mar 2002 - Matt Domsch <Matt_Domsch@dell.com>
 *   move uuid_unparse() to include/asm-ia64/efi.h:efi_guid_unparse()
 *
 *  12 Feb 2002 - Matt Domsch <Matt_Domsch@dell.com>
 *   use list_for_each_safe when deleting vars.
 *   remove ifdef CONFIG_SMP around include <linux/smp.h>
 *   v0.04 release to linux-ia64@linuxia64.org
 *
 *  20 April 2001 - Matt Domsch <Matt_Domsch@dell.com>
 *   Moved vars from /proc/efi to /proc/efi/vars, and made
 *   efi.c own the /proc/efi directory.
 *   v0.03 release to linux-ia64@linuxia64.org
 *
 *  26 March 2001 - Matt Domsch <Matt_Domsch@dell.com>
 *   At the request of Stephane, moved ownership of /proc/efi
 *   to efi.c, and now efivars lives under /proc/efi/vars.
 *
 *  12 March 2001 - Matt Domsch <Matt_Domsch@dell.com>
 *   Feedback received from Stephane Eranian incorporated.
 *   efivar_write() checks copy_from_user() return value.
 *   efivar_read/write() returns proper errno.
 *   v0.02 release to linux-ia64@linuxia64.org
 *
 *  26 February 2001 - Matt Domsch <Matt_Domsch@dell.com>
 *   v0.01 release to linux-ia64@linuxia64.org
 */

#include <linux/capability.h>
#include <linux/types.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/string.h>
#include <linux/smp.h>
#include <linux/efi.h>
#include <linux/sysfs.h>
#include <linux/kobject.h>
#include <linux/device.h>
#include <linux/slab.h>
#include <linux/pstore.h>

#include <asm/uaccess.h>

#define EFIVARS_VERSION "0.08"
#define EFIVARS_DATE "2004-May-17"

MODULE_AUTHOR("Matt Domsch <Matt_Domsch@Dell.com>");
MODULE_DESCRIPTION("sysfs interface to EFI Variables");
MODULE_LICENSE("GPL");
MODULE_VERSION(EFIVARS_VERSION);

#define DUMP_NAME_LEN 52

/*
 * The maximum size of VariableName + Data = 1024
 * Therefore, it's reasonable to save that much
 * space in each part of the structure,
 * and we use a page for reading/writing.
 */

struct efi_variable {
	efi_char16_t  VariableName[1024/sizeof(efi_char16_t)];
	efi_guid_t    VendorGuid;
	unsigned long DataSize;
	__u8          Data[1024];
	efi_status_t  Status;
	__u32         Attributes;
} __attribute__((packed));


struct efivar_entry {
	struct efivars *efivars;
	struct efi_variable var;
	struct list_head list;
	struct kobject kobj;
};

struct efivar_attribute {
	struct attribute attr;
	ssize_t (*show) (struct efivar_entry *entry, char *buf);
	ssize_t (*store)(struct efivar_entry *entry, const char *buf, size_t count);
};


#define EFIVAR_ATTR(_name, _mode, _show, _store) \
struct efivar_attribute efivar_attr_##_name = { \
	.attr = {.name = __stringify(_name), .mode = _mode}, \
	.show = _show, \
	.store = _store, \
};

#define to_efivar_attr(_attr) container_of(_attr, struct efivar_attribute, attr)
#define to_efivar_entry(obj)  container_of(obj, struct efivar_entry, kobj)

/*
 * Prototype for sysfs creation function
 */
static int
efivar_create_sysfs_entry(struct efivars *efivars,
			  unsigned long variable_name_size,
			  efi_char16_t *variable_name,
			  efi_guid_t *vendor_guid);

/* Return the number of unicode characters in data */
static unsigned long
utf16_strnlen(efi_char16_t *s, size_t maxlength)
{
	unsigned long length = 0;

	while (*s++ != 0 && length < maxlength)
		length++;
	return length;
}

static unsigned long
utf16_strlen(efi_char16_t *s)
{
	return utf16_strnlen(s, ~0UL);
}

/*
 * Return the number of bytes is the length of this string
 * Note: this is NOT the same as the number of unicode characters
 */
static inline unsigned long
utf16_strsize(efi_char16_t *data, unsigned long maxlength)
{
	return utf16_strnlen(data, maxlength/sizeof(efi_char16_t)) * sizeof(efi_char16_t);
}

static efi_status_t
get_var_data_locked(struct efivars *efivars, struct efi_variable *var)
{
	efi_status_t status;

	var->DataSize = 1024;
	status = efivars->ops->get_variable(var->VariableName,
					    &var->VendorGuid,
					    &var->Attributes,
					    &var->DataSize,
					    var->Data);
	return status;
}

static efi_status_t
get_var_data(struct efivars *efivars, struct efi_variable *var)
{
	efi_status_t status;

	spin_lock(&efivars->lock);
	status = get_var_data_locked(efivars, var);
	spin_unlock(&efivars->lock);

	if (status != EFI_SUCCESS) {
		printk(KERN_WARNING "efivars: get_variable() failed 0x%lx!\n",
			status);
	}
	return status;
}

static ssize_t
efivar_guid_read(struct efivar_entry *entry, char *buf)
{
	struct efi_variable *var = &entry->var;
	char *str = buf;

	if (!entry || !buf)
		return 0;

	efi_guid_unparse(&var->VendorGuid, str);
	str += strlen(str);
	str += sprintf(str, "\n");

	return str - buf;
}

static ssize_t
efivar_attr_read(struct efivar_entry *entry, char *buf)
{
	struct efi_variable *var = &entry->var;
	char *str = buf;
	efi_status_t status;

	if (!entry || !buf)
		return -EINVAL;

	status = get_var_data(entry->efivars, var);
	if (status != EFI_SUCCESS)
		return -EIO;

	if (var->Attributes & 0x1)
		str += sprintf(str, "EFI_VARIABLE_NON_VOLATILE\n");
	if (var->Attributes & 0x2)
		str += sprintf(str, "EFI_VARIABLE_BOOTSERVICE_ACCESS\n");
	if (var->Attributes & 0x4)
		str += sprintf(str, "EFI_VARIABLE_RUNTIME_ACCESS\n");
	return str - buf;
}

static ssize_t
efivar_size_read(struct efivar_entry *entry, char *buf)
{
	struct efi_variable *var = &entry->var;
	char *str = buf;
	efi_status_t status;

	if (!entry || !buf)
		return -EINVAL;

	status = get_var_data(entry->efivars, var);
	if (status != EFI_SUCCESS)
		return -EIO;

	str += sprintf(str, "0x%lx\n", var->DataSize);
	return str - buf;
}

static ssize_t
efivar_data_read(struct efivar_entry *entry, char *buf)
{
	struct efi_variable *var = &entry->var;
	efi_status_t status;

	if (!entry || !buf)
		return -EINVAL;

	status = get_var_data(entry->efivars, var);
	if (status != EFI_SUCCESS)
		return -EIO;

	memcpy(buf, var->Data, var->DataSize);
	return var->DataSize;
}
/*
 * We allow each variable to be edited via rewriting the
 * entire efi variable structure.
 */
static ssize_t
efivar_store_raw(struct efivar_entry *entry, const char *buf, size_t count)
{
	struct efi_variable *new_var, *var = &entry->var;
	struct efivars *efivars = entry->efivars;
	efi_status_t status = EFI_NOT_FOUND;

	if (count != sizeof(struct efi_variable))
		return -EINVAL;

	new_var = (struct efi_variable *)buf;
	/*
	 * If only updating the variable data, then the name
	 * and guid should remain the same
	 */
	if (memcmp(new_var->VariableName, var->VariableName, sizeof(var->VariableName)) ||
		efi_guidcmp(new_var->VendorGuid, var->VendorGuid)) {
		printk(KERN_ERR "efivars: Cannot edit the wrong variable!\n");
		return -EINVAL;
	}

	if ((new_var->DataSize <= 0) || (new_var->Attributes == 0)){
		printk(KERN_ERR "efivars: DataSize & Attributes must be valid!\n");
		return -EINVAL;
	}

	spin_lock(&efivars->lock);
	status = efivars->ops->set_variable(new_var->VariableName,
					    &new_var->VendorGuid,
					    new_var->Attributes,
					    new_var->DataSize,
					    new_var->Data);

	spin_unlock(&efivars->lock);

	if (status != EFI_SUCCESS) {
		printk(KERN_WARNING "efivars: set_variable() failed: status=%lx\n",
			status);
		return -EIO;
	}

	memcpy(&entry->var, new_var, count);
	return count;
}

static ssize_t
efivar_show_raw(struct efivar_entry *entry, char *buf)
{
	struct efi_variable *var = &entry->var;
	efi_status_t status;

	if (!entry || !buf)
		return 0;

	status = get_var_data(entry->efivars, var);
	if (status != EFI_SUCCESS)
		return -EIO;

	memcpy(buf, var, sizeof(*var));
	return sizeof(*var);
}

/*
 * Generic read/write functions that call the specific functions of
 * the attributes...
 */
static ssize_t efivar_attr_show(struct kobject *kobj, struct attribute *attr,
				char *buf)
{
	struct efivar_entry *var = to_efivar_entry(kobj);
	struct efivar_attribute *efivar_attr = to_efivar_attr(attr);
	ssize_t ret = -EIO;

	if (!capable(CAP_SYS_ADMIN))
		return -EACCES;

	if (efivar_attr->show) {
		ret = efivar_attr->show(var, buf);
	}
	return ret;
}

static ssize_t efivar_attr_store(struct kobject *kobj, struct attribute *attr,
				const char *buf, size_t count)
{
	struct efivar_entry *var = to_efivar_entry(kobj);
	struct efivar_attribute *efivar_attr = to_efivar_attr(attr);
	ssize_t ret = -EIO;

	if (!capable(CAP_SYS_ADMIN))
		return -EACCES;

	if (efivar_attr->store)
		ret = efivar_attr->store(var, buf, count);

	return ret;
}

static const struct sysfs_ops efivar_attr_ops = {
	.show = efivar_attr_show,
	.store = efivar_attr_store,
};

static void efivar_release(struct kobject *kobj)
{
	struct efivar_entry *var = container_of(kobj, struct efivar_entry, kobj);
	kfree(var);
}

static EFIVAR_ATTR(guid, 0400, efivar_guid_read, NULL);
static EFIVAR_ATTR(attributes, 0400, efivar_attr_read, NULL);
static EFIVAR_ATTR(size, 0400, efivar_size_read, NULL);
static EFIVAR_ATTR(data, 0400, efivar_data_read, NULL);
static EFIVAR_ATTR(raw_var, 0600, efivar_show_raw, efivar_store_raw);

static struct attribute *def_attrs[] = {
	&efivar_attr_guid.attr,
	&efivar_attr_size.attr,
	&efivar_attr_attributes.attr,
	&efivar_attr_data.attr,
	&efivar_attr_raw_var.attr,
	NULL,
};

static struct kobj_type efivar_ktype = {
	.release = efivar_release,
	.sysfs_ops = &efivar_attr_ops,
	.default_attrs = def_attrs,
};

static struct pstore_info efi_pstore_info;

static inline void
efivar_unregister(struct efivar_entry *var)
{
	kobject_put(&var->kobj);
}

#ifdef CONFIG_PSTORE

static int efi_pstore_open(struct pstore_info *psi)
{
	struct efivars *efivars = psi->data;

	spin_lock(&efivars->lock);
	efivars->walk_entry = list_first_entry(&efivars->list,
					       struct efivar_entry, list);
	return 0;
}

static int efi_pstore_close(struct pstore_info *psi)
{
	struct efivars *efivars = psi->data;

	spin_unlock(&efivars->lock);
	return 0;
}

static ssize_t efi_pstore_read(u64 *id, enum pstore_type_id *type,
			       struct timespec *timespec, struct pstore_info *psi)
{
	efi_guid_t vendor = LINUX_EFI_CRASH_GUID;
	struct efivars *efivars = psi->data;
	char name[DUMP_NAME_LEN];
	int i;
	unsigned int part, size;
	unsigned long time;

	while (&efivars->walk_entry->list != &efivars->list) {
		if (!efi_guidcmp(efivars->walk_entry->var.VendorGuid,
				 vendor)) {
			for (i = 0; i < DUMP_NAME_LEN; i++) {
				name[i] = efivars->walk_entry->var.VariableName[i];
			}
			if (sscanf(name, "dump-type%u-%u-%lu", type, &part, &time) == 3) {
				*id = part;
				timespec->tv_sec = time;
				timespec->tv_nsec = 0;
				get_var_data_locked(efivars, &efivars->walk_entry->var);
				size = efivars->walk_entry->var.DataSize;
				memcpy(psi->buf, efivars->walk_entry->var.Data, size);
				efivars->walk_entry = list_entry(efivars->walk_entry->list.next,
					           struct efivar_entry, list);
				return size;
			}
		}
		efivars->walk_entry = list_entry(efivars->walk_entry->list.next,
						 struct efivar_entry, list);
	}
	return 0;
}

static u64 efi_pstore_write(enum pstore_type_id type, unsigned int part,
			    size_t size, struct pstore_info *psi)
{
	char name[DUMP_NAME_LEN];
	char stub_name[DUMP_NAME_LEN];
	efi_char16_t efi_name[DUMP_NAME_LEN];
	efi_guid_t vendor = LINUX_EFI_CRASH_GUID;
	struct efivars *efivars = psi->data;
	struct efivar_entry *entry, *found = NULL;
	int i;

	sprintf(stub_name, "dump-type%u-%u-", type, part);
	sprintf(name, "%s%lu", stub_name, get_seconds());

	spin_lock(&efivars->lock);

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

	/*
	 * Clean up any entries with the same name
	 */

	list_for_each_entry(entry, &efivars->list, list) {
		get_var_data_locked(efivars, &entry->var);

		for (i = 0; i < DUMP_NAME_LEN; i++) {
			if (efi_name[i] == 0) {
				found = entry;
				efivars->ops->set_variable(entry->var.VariableName,
							   &entry->var.VendorGuid,
							   EFI_VARIABLE_NON_VOLATILE | EFI_VARIABLE_BOOTSERVICE_ACCESS | EFI_VARIABLE_RUNTIME_ACCESS,
							   0, NULL);
				break;
			} else if (efi_name[i] != entry->var.VariableName[i]) {
				break;
			}
		}
	}

	if (found)
		list_del(&found->list);

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

	efivars->ops->set_variable(efi_name, &vendor,
				   EFI_VARIABLE_NON_VOLATILE | EFI_VARIABLE_BOOTSERVICE_ACCESS | EFI_VARIABLE_RUNTIME_ACCESS,
				   size, psi->buf);

	spin_unlock(&efivars->lock);

	if (found)
		efivar_unregister(found);

	if (size)
		efivar_create_sysfs_entry(efivars,
					  utf16_strsize(efi_name,
							DUMP_NAME_LEN * 2),
					  efi_name, &vendor);

	return part;
};

static int efi_pstore_erase(enum pstore_type_id type, u64 id,
			    struct pstore_info *psi)
{
	efi_pstore_write(type, id, 0, psi);

	return 0;
}
#else
static int efi_pstore_open(struct pstore_info *psi)
{
	return 0;
}

static int efi_pstore_close(struct pstore_info *psi)
{
	return 0;
}

static ssize_t efi_pstore_read(u64 *id, enum pstore_type_id *type,
			       struct timespec *time, struct pstore_info *psi)
{
	return -1;
}

static u64 efi_pstore_write(enum pstore_type_id type, int part, size_t size,
			    struct pstore_info *psi)
{
	return 0;
}

static int efi_pstore_erase(enum pstore_type_id type, u64 id,
			    struct pstore_info *psi)
{
	return 0;
}
#endif

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

static ssize_t efivar_create(struct file *filp, struct kobject *kobj,
			     struct bin_attribute *bin_attr,
			     char *buf, loff_t pos, size_t count)
{
	struct efi_variable *new_var = (struct efi_variable *)buf;
	struct efivars *efivars = bin_attr->private;
	struct efivar_entry *search_efivar, *n;
	unsigned long strsize1, strsize2;
	efi_status_t status = EFI_NOT_FOUND;
	int found = 0;

	if (!capable(CAP_SYS_ADMIN))
		return -EACCES;

	spin_lock(&efivars->lock);

	/*
	 * Does this variable already exist?
	 */
	list_for_each_entry_safe(search_efivar, n, &efivars->list, list) {
		strsize1 = utf16_strsize(search_efivar->var.VariableName, 1024);
		strsize2 = utf16_strsize(new_var->VariableName, 1024);
		if (strsize1 == strsize2 &&
			!memcmp(&(search_efivar->var.VariableName),
				new_var->VariableName, strsize1) &&
			!efi_guidcmp(search_efivar->var.VendorGuid,
				new_var->VendorGuid)) {
			found = 1;
			break;
		}
	}
	if (found) {
		spin_unlock(&efivars->lock);
		return -EINVAL;
	}

	/* now *really* create the variable via EFI */
	status = efivars->ops->set_variable(new_var->VariableName,
					    &new_var->VendorGuid,
					    new_var->Attributes,
					    new_var->DataSize,
					    new_var->Data);

	if (status != EFI_SUCCESS) {
		printk(KERN_WARNING "efivars: set_variable() failed: status=%lx\n",
			status);
		spin_unlock(&efivars->lock);
		return -EIO;
	}
	spin_unlock(&efivars->lock);

	/* Create the entry in sysfs.  Locking is not required here */
	status = efivar_create_sysfs_entry(efivars,
					   utf16_strsize(new_var->VariableName,
							 1024),
					   new_var->VariableName,
					   &new_var->VendorGuid);
	if (status) {
		printk(KERN_WARNING "efivars: variable created, but sysfs entry wasn't.\n");
	}
	return count;
}

static ssize_t efivar_delete(struct file *filp, struct kobject *kobj,
			     struct bin_attribute *bin_attr,
			     char *buf, loff_t pos, size_t count)
{
	struct efi_variable *del_var = (struct efi_variable *)buf;
	struct efivars *efivars = bin_attr->private;
	struct efivar_entry *search_efivar, *n;
	unsigned long strsize1, strsize2;
	efi_status_t status = EFI_NOT_FOUND;
	int found = 0;

	if (!capable(CAP_SYS_ADMIN))
		return -EACCES;

	spin_lock(&efivars->lock);

	/*
	 * Does this variable already exist?
	 */
	list_for_each_entry_safe(search_efivar, n, &efivars->list, list) {
		strsize1 = utf16_strsize(search_efivar->var.VariableName, 1024);
		strsize2 = utf16_strsize(del_var->VariableName, 1024);
		if (strsize1 == strsize2 &&
			!memcmp(&(search_efivar->var.VariableName),
				del_var->VariableName, strsize1) &&
			!efi_guidcmp(search_efivar->var.VendorGuid,
				del_var->VendorGuid)) {
			found = 1;
			break;
		}
	}
	if (!found) {
		spin_unlock(&efivars->lock);
		return -EINVAL;
	}
	/* force the Attributes/DataSize to 0 to ensure deletion */
	del_var->Attributes = 0;
	del_var->DataSize = 0;

	status = efivars->ops->set_variable(del_var->VariableName,
					    &del_var->VendorGuid,
					    del_var->Attributes,
					    del_var->DataSize,
					    del_var->Data);

	if (status != EFI_SUCCESS) {
		printk(KERN_WARNING "efivars: set_variable() failed: status=%lx\n",
			status);
		spin_unlock(&efivars->lock);
		return -EIO;
	}
	list_del(&search_efivar->list);
	/* We need to release this lock before unregistering. */
	spin_unlock(&efivars->lock);
	efivar_unregister(search_efivar);

	/* It's dead Jim.... */
	return count;
}

/*
 * Let's not leave out systab information that snuck into
 * the efivars driver
 */
static ssize_t systab_show(struct kobject *kobj,
			   struct kobj_attribute *attr, char *buf)
{
	char *str = buf;

	if (!kobj || !buf)
		return -EINVAL;

	if (efi.mps != EFI_INVALID_TABLE_ADDR)
		str += sprintf(str, "MPS=0x%lx\n", efi.mps);
	if (efi.acpi20 != EFI_INVALID_TABLE_ADDR)
		str += sprintf(str, "ACPI20=0x%lx\n", efi.acpi20);
	if (efi.acpi != EFI_INVALID_TABLE_ADDR)
		str += sprintf(str, "ACPI=0x%lx\n", efi.acpi);
	if (efi.smbios != EFI_INVALID_TABLE_ADDR)
		str += sprintf(str, "SMBIOS=0x%lx\n", efi.smbios);
	if (efi.hcdp != EFI_INVALID_TABLE_ADDR)
		str += sprintf(str, "HCDP=0x%lx\n", efi.hcdp);
	if (efi.boot_info != EFI_INVALID_TABLE_ADDR)
		str += sprintf(str, "BOOTINFO=0x%lx\n", efi.boot_info);
	if (efi.uga != EFI_INVALID_TABLE_ADDR)
		str += sprintf(str, "UGA=0x%lx\n", efi.uga);

	return str - buf;
}

static struct kobj_attribute efi_attr_systab =
			__ATTR(systab, 0400, systab_show, NULL);

static struct attribute *efi_subsys_attrs[] = {
	&efi_attr_systab.attr,
	NULL,	/* maybe more in the future? */
};

static struct attribute_group efi_subsys_attr_group = {
	.attrs = efi_subsys_attrs,
};

static struct kobject *efi_kobj;

/*
 * efivar_create_sysfs_entry()
 * Requires:
 *    variable_name_size = number of bytes required to hold
 *                         variable_name (not counting the NULL
 *                         character at the end.
 *    efivars->lock is not held on entry or exit.
 * Returns 1 on failure, 0 on success
 */
static int
efivar_create_sysfs_entry(struct efivars *efivars,
			  unsigned long variable_name_size,
			  efi_char16_t *variable_name,
			  efi_guid_t *vendor_guid)
{
	int i, short_name_size = variable_name_size / sizeof(efi_char16_t) + 38;
	char *short_name;
	struct efivar_entry *new_efivar;

	short_name = kzalloc(short_name_size + 1, GFP_KERNEL);
	new_efivar = kzalloc(sizeof(struct efivar_entry), GFP_KERNEL);

	if (!short_name || !new_efivar)  {
		kfree(short_name);
		kfree(new_efivar);
		return 1;
	}

	new_efivar->efivars = efivars;
	memcpy(new_efivar->var.VariableName, variable_name,
		variable_name_size);
	memcpy(&(new_efivar->var.VendorGuid), vendor_guid, sizeof(efi_guid_t));

	/* Convert Unicode to normal chars (assume top bits are 0),
	   ala UTF-8 */
	for (i=0; i < (int)(variable_name_size / sizeof(efi_char16_t)); i++) {
		short_name[i] = variable_name[i] & 0xFF;
	}
	/* This is ugly, but necessary to separate one vendor's
	   private variables from another's.         */

	*(short_name + strlen(short_name)) = '-';
	efi_guid_unparse(vendor_guid, short_name + strlen(short_name));

	new_efivar->kobj.kset = efivars->kset;
	i = kobject_init_and_add(&new_efivar->kobj, &efivar_ktype, NULL,
				 "%s", short_name);
	if (i) {
		kfree(short_name);
		kfree(new_efivar);
		return 1;
	}

	kobject_uevent(&new_efivar->kobj, KOBJ_ADD);
	kfree(short_name);
	short_name = NULL;

	spin_lock(&efivars->lock);
	list_add(&new_efivar->list, &efivars->list);
	spin_unlock(&efivars->lock);

	return 0;
}

static int
create_efivars_bin_attributes(struct efivars *efivars)
{
	struct bin_attribute *attr;
	int error;

	/* new_var */
	attr = kzalloc(sizeof(*attr), GFP_KERNEL);
	if (!attr)
		return -ENOMEM;

	attr->attr.name = "new_var";
	attr->attr.mode = 0200;
	attr->write = efivar_create;
	attr->private = efivars;
	efivars->new_var = attr;

	/* del_var */
	attr = kzalloc(sizeof(*attr), GFP_KERNEL);
	if (!attr) {
		error = -ENOMEM;
		goto out_free;
	}
	attr->attr.name = "del_var";
	attr->attr.mode = 0200;
	attr->write = efivar_delete;
	attr->private = efivars;
	efivars->del_var = attr;

	sysfs_bin_attr_init(efivars->new_var);
	sysfs_bin_attr_init(efivars->del_var);

	/* Register */
	error = sysfs_create_bin_file(&efivars->kset->kobj,
				      efivars->new_var);
	if (error) {
		printk(KERN_ERR "efivars: unable to create new_var sysfs file"
			" due to error %d\n", error);
		goto out_free;
	}
	error = sysfs_create_bin_file(&efivars->kset->kobj,
				      efivars->del_var);
	if (error) {
		printk(KERN_ERR "efivars: unable to create del_var sysfs file"
			" due to error %d\n", error);
		sysfs_remove_bin_file(&efivars->kset->kobj,
				      efivars->new_var);
		goto out_free;
	}

	return 0;
out_free:
	kfree(efivars->del_var);
	efivars->del_var = NULL;
	kfree(efivars->new_var);
	efivars->new_var = NULL;
	return error;
}

void unregister_efivars(struct efivars *efivars)
{
	struct efivar_entry *entry, *n;

	list_for_each_entry_safe(entry, n, &efivars->list, list) {
		spin_lock(&efivars->lock);
		list_del(&entry->list);
		spin_unlock(&efivars->lock);
		efivar_unregister(entry);
	}
	if (efivars->new_var)
		sysfs_remove_bin_file(&efivars->kset->kobj, efivars->new_var);
	if (efivars->del_var)
		sysfs_remove_bin_file(&efivars->kset->kobj, efivars->del_var);
	kfree(efivars->new_var);
	kfree(efivars->del_var);
	kset_unregister(efivars->kset);
}
EXPORT_SYMBOL_GPL(unregister_efivars);

int register_efivars(struct efivars *efivars,
		     const struct efivar_operations *ops,
		     struct kobject *parent_kobj)
{
	efi_status_t status = EFI_NOT_FOUND;
	efi_guid_t vendor_guid;
	efi_char16_t *variable_name;
	unsigned long variable_name_size = 1024;
	int error = 0;

	variable_name = kzalloc(variable_name_size, GFP_KERNEL);
	if (!variable_name) {
		printk(KERN_ERR "efivars: Memory allocation failed.\n");
		return -ENOMEM;
	}

	spin_lock_init(&efivars->lock);
	INIT_LIST_HEAD(&efivars->list);
	efivars->ops = ops;

	efivars->kset = kset_create_and_add("vars", NULL, parent_kobj);
	if (!efivars->kset) {
		printk(KERN_ERR "efivars: Subsystem registration failed.\n");
		error = -ENOMEM;
		goto out;
	}

	/*
	 * Per EFI spec, the maximum storage allocated for both
	 * the variable name and variable data is 1024 bytes.
	 */

	do {
		variable_name_size = 1024;

		status = ops->get_next_variable(&variable_name_size,
						variable_name,
						&vendor_guid);
		switch (status) {
		case EFI_SUCCESS:
			efivar_create_sysfs_entry(efivars,
						  variable_name_size,
						  variable_name,
						  &vendor_guid);
			break;
		case EFI_NOT_FOUND:
			break;
		default:
			printk(KERN_WARNING "efivars: get_next_variable: status=%lx\n",
				status);
			status = EFI_NOT_FOUND;
			break;
		}
	} while (status != EFI_NOT_FOUND);

	error = create_efivars_bin_attributes(efivars);
	if (error)
		unregister_efivars(efivars);

	efivars->efi_pstore_info = efi_pstore_info;

	efivars->efi_pstore_info.buf = kmalloc(4096, GFP_KERNEL);
	if (efivars->efi_pstore_info.buf) {
		efivars->efi_pstore_info.bufsize = 1024;
		efivars->efi_pstore_info.data = efivars;
		mutex_init(&efivars->efi_pstore_info.buf_mutex);
		pstore_register(&efivars->efi_pstore_info);
	}

out:
	kfree(variable_name);

	return error;
}
EXPORT_SYMBOL_GPL(register_efivars);

static struct efivars __efivars;
static struct efivar_operations ops;

/*
 * For now we register the efi subsystem with the firmware subsystem
 * and the vars subsystem with the efi subsystem.  In the future, it
 * might make sense to split off the efi subsystem into its own
 * driver, but for now only efivars will register with it, so just
 * include it here.
 */

static int __init
efivars_init(void)
{
	int error = 0;

	printk(KERN_INFO "EFI Variables Facility v%s %s\n", EFIVARS_VERSION,
	       EFIVARS_DATE);

	if (!efi_enabled)
		return 0;

	/* For now we'll register the efi directory at /sys/firmware/efi */
	efi_kobj = kobject_create_and_add("efi", firmware_kobj);
	if (!efi_kobj) {
		printk(KERN_ERR "efivars: Firmware registration failed.\n");
		return -ENOMEM;
	}

	ops.get_variable = efi.get_variable;
	ops.set_variable = efi.set_variable;
	ops.get_next_variable = efi.get_next_variable;
	error = register_efivars(&__efivars, &ops, efi_kobj);
	if (error)
		goto err_put;

	/* Don't forget the systab entry */
	error = sysfs_create_group(efi_kobj, &efi_subsys_attr_group);
	if (error) {
		printk(KERN_ERR
		       "efivars: Sysfs attribute export failed with error %d.\n",
		       error);
		goto err_unregister;
	}

	return 0;

err_unregister:
	unregister_efivars(&__efivars);
err_put:
	kobject_put(efi_kobj);
	return error;
}

static void __exit
efivars_exit(void)
{
	if (efi_enabled) {
		unregister_efivars(&__efivars);
		kobject_put(efi_kobj);
	}
}

module_init(efivars_init);
module_exit(efivars_exit);