1/*
2 * Originally from efivars.c,
3 *
4 * Copyright (C) 2001,2003,2004 Dell <Matt_Domsch@dell.com>
5 * Copyright (C) 2004 Intel Corporation <matthew.e.tolentino@intel.com>
6 *
7 * This code takes all variables accessible from EFI runtime and
8 *  exports them via sysfs
9 *
10 *  This program is free software; you can redistribute it and/or modify
11 *  it under the terms of the GNU General Public License as published by
12 *  the Free Software Foundation; either version 2 of the License, or
13 *  (at your option) any later version.
14 *
15 *  This program is distributed in the hope that it will be useful,
16 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
17 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
18 *  GNU General Public License for more details.
19 *
20 *  You should have received a copy of the GNU General Public License
21 *  along with this program; if not, write to the Free Software
22 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
23 *
24 * Changelog:
25 *
26 *  17 May 2004 - Matt Domsch <Matt_Domsch@dell.com>
27 *   remove check for efi_enabled in exit
28 *   add MODULE_VERSION
29 *
30 *  26 Apr 2004 - Matt Domsch <Matt_Domsch@dell.com>
31 *   minor bug fixes
32 *
33 *  21 Apr 2004 - Matt Tolentino <matthew.e.tolentino@intel.com)
34 *   converted driver to export variable information via sysfs
35 *   and moved to drivers/firmware directory
36 *   bumped revision number to v0.07 to reflect conversion & move
37 *
38 *  10 Dec 2002 - Matt Domsch <Matt_Domsch@dell.com>
39 *   fix locking per Peter Chubb's findings
40 *
41 *  25 Mar 2002 - Matt Domsch <Matt_Domsch@dell.com>
42 *   move uuid_unparse() to include/asm-ia64/efi.h:efi_guid_to_str()
43 *
44 *  12 Feb 2002 - Matt Domsch <Matt_Domsch@dell.com>
45 *   use list_for_each_safe when deleting vars.
46 *   remove ifdef CONFIG_SMP around include <linux/smp.h>
47 *   v0.04 release to linux-ia64@linuxia64.org
48 *
49 *  20 April 2001 - Matt Domsch <Matt_Domsch@dell.com>
50 *   Moved vars from /proc/efi to /proc/efi/vars, and made
51 *   efi.c own the /proc/efi directory.
52 *   v0.03 release to linux-ia64@linuxia64.org
53 *
54 *  26 March 2001 - Matt Domsch <Matt_Domsch@dell.com>
55 *   At the request of Stephane, moved ownership of /proc/efi
56 *   to efi.c, and now efivars lives under /proc/efi/vars.
57 *
58 *  12 March 2001 - Matt Domsch <Matt_Domsch@dell.com>
59 *   Feedback received from Stephane Eranian incorporated.
60 *   efivar_write() checks copy_from_user() return value.
61 *   efivar_read/write() returns proper errno.
62 *   v0.02 release to linux-ia64@linuxia64.org
63 *
64 *  26 February 2001 - Matt Domsch <Matt_Domsch@dell.com>
65 *   v0.01 release to linux-ia64@linuxia64.org
66 */
67
68#include <linux/efi.h>
69#include <linux/module.h>
70#include <linux/slab.h>
71#include <linux/ucs2_string.h>
72#include <linux/compat.h>
73
74#define EFIVARS_VERSION "0.08"
75#define EFIVARS_DATE "2004-May-17"
76
77MODULE_AUTHOR("Matt Domsch <Matt_Domsch@Dell.com>");
78MODULE_DESCRIPTION("sysfs interface to EFI Variables");
79MODULE_LICENSE("GPL");
80MODULE_VERSION(EFIVARS_VERSION);
81MODULE_ALIAS("platform:efivars");
82
83LIST_HEAD(efivar_sysfs_list);
84EXPORT_SYMBOL_GPL(efivar_sysfs_list);
85
86static struct kset *efivars_kset;
87
88static struct bin_attribute *efivars_new_var;
89static struct bin_attribute *efivars_del_var;
90
91struct compat_efi_variable {
92	efi_char16_t  VariableName[EFI_VAR_NAME_LEN/sizeof(efi_char16_t)];
93	efi_guid_t    VendorGuid;
94	__u32         DataSize;
95	__u8          Data[1024];
96	__u32         Status;
97	__u32         Attributes;
98} __packed;
99
100struct efivar_attribute {
101	struct attribute attr;
102	ssize_t (*show) (struct efivar_entry *entry, char *buf);
103	ssize_t (*store)(struct efivar_entry *entry, const char *buf, size_t count);
104};
105
106#define EFIVAR_ATTR(_name, _mode, _show, _store) \
107struct efivar_attribute efivar_attr_##_name = { \
108	.attr = {.name = __stringify(_name), .mode = _mode}, \
109	.show = _show, \
110	.store = _store, \
111};
112
113#define to_efivar_attr(_attr) container_of(_attr, struct efivar_attribute, attr)
114#define to_efivar_entry(obj)  container_of(obj, struct efivar_entry, kobj)
115
116/*
117 * Prototype for sysfs creation function
118 */
119static int
120efivar_create_sysfs_entry(struct efivar_entry *new_var);
121
122static ssize_t
123efivar_guid_read(struct efivar_entry *entry, char *buf)
124{
125	struct efi_variable *var = &entry->var;
126	char *str = buf;
127
128	if (!entry || !buf)
129		return 0;
130
131	efi_guid_to_str(&var->VendorGuid, str);
132	str += strlen(str);
133	str += sprintf(str, "\n");
134
135	return str - buf;
136}
137
138static ssize_t
139efivar_attr_read(struct efivar_entry *entry, char *buf)
140{
141	struct efi_variable *var = &entry->var;
142	char *str = buf;
143
144	if (!entry || !buf)
145		return -EINVAL;
146
147	var->DataSize = 1024;
148	if (efivar_entry_get(entry, &var->Attributes, &var->DataSize, var->Data))
149		return -EIO;
150
151	if (var->Attributes & EFI_VARIABLE_NON_VOLATILE)
152		str += sprintf(str, "EFI_VARIABLE_NON_VOLATILE\n");
153	if (var->Attributes & EFI_VARIABLE_BOOTSERVICE_ACCESS)
154		str += sprintf(str, "EFI_VARIABLE_BOOTSERVICE_ACCESS\n");
155	if (var->Attributes & EFI_VARIABLE_RUNTIME_ACCESS)
156		str += sprintf(str, "EFI_VARIABLE_RUNTIME_ACCESS\n");
157	if (var->Attributes & EFI_VARIABLE_HARDWARE_ERROR_RECORD)
158		str += sprintf(str, "EFI_VARIABLE_HARDWARE_ERROR_RECORD\n");
159	if (var->Attributes & EFI_VARIABLE_AUTHENTICATED_WRITE_ACCESS)
160		str += sprintf(str,
161			"EFI_VARIABLE_AUTHENTICATED_WRITE_ACCESS\n");
162	if (var->Attributes &
163			EFI_VARIABLE_TIME_BASED_AUTHENTICATED_WRITE_ACCESS)
164		str += sprintf(str,
165			"EFI_VARIABLE_TIME_BASED_AUTHENTICATED_WRITE_ACCESS\n");
166	if (var->Attributes & EFI_VARIABLE_APPEND_WRITE)
167		str += sprintf(str, "EFI_VARIABLE_APPEND_WRITE\n");
168	return str - buf;
169}
170
171static ssize_t
172efivar_size_read(struct efivar_entry *entry, char *buf)
173{
174	struct efi_variable *var = &entry->var;
175	char *str = buf;
176
177	if (!entry || !buf)
178		return -EINVAL;
179
180	var->DataSize = 1024;
181	if (efivar_entry_get(entry, &var->Attributes, &var->DataSize, var->Data))
182		return -EIO;
183
184	str += sprintf(str, "0x%lx\n", var->DataSize);
185	return str - buf;
186}
187
188static ssize_t
189efivar_data_read(struct efivar_entry *entry, char *buf)
190{
191	struct efi_variable *var = &entry->var;
192
193	if (!entry || !buf)
194		return -EINVAL;
195
196	var->DataSize = 1024;
197	if (efivar_entry_get(entry, &var->Attributes, &var->DataSize, var->Data))
198		return -EIO;
199
200	memcpy(buf, var->Data, var->DataSize);
201	return var->DataSize;
202}
203
204static inline int
205sanity_check(struct efi_variable *var, efi_char16_t *name, efi_guid_t vendor,
206	     unsigned long size, u32 attributes, u8 *data)
207{
208	/*
209	 * If only updating the variable data, then the name
210	 * and guid should remain the same
211	 */
212	if (memcmp(name, var->VariableName, sizeof(var->VariableName)) ||
213		efi_guidcmp(vendor, var->VendorGuid)) {
214		printk(KERN_ERR "efivars: Cannot edit the wrong variable!\n");
215		return -EINVAL;
216	}
217
218	if ((size <= 0) || (attributes == 0)){
219		printk(KERN_ERR "efivars: DataSize & Attributes must be valid!\n");
220		return -EINVAL;
221	}
222
223	if ((attributes & ~EFI_VARIABLE_MASK) != 0 ||
224	    efivar_validate(vendor, name, data, size) == false) {
225		printk(KERN_ERR "efivars: Malformed variable content\n");
226		return -EINVAL;
227	}
228
229	return 0;
230}
231
232static inline bool is_compat(void)
233{
234	if (IS_ENABLED(CONFIG_COMPAT) && is_compat_task())
235		return true;
236
237	return false;
238}
239
240static void
241copy_out_compat(struct efi_variable *dst, struct compat_efi_variable *src)
242{
243	memcpy(dst->VariableName, src->VariableName, EFI_VAR_NAME_LEN);
244	memcpy(dst->Data, src->Data, sizeof(src->Data));
245
246	dst->VendorGuid = src->VendorGuid;
247	dst->DataSize = src->DataSize;
248	dst->Attributes = src->Attributes;
249}
250
251/*
252 * We allow each variable to be edited via rewriting the
253 * entire efi variable structure.
254 */
255static ssize_t
256efivar_store_raw(struct efivar_entry *entry, const char *buf, size_t count)
257{
258	struct efi_variable *new_var, *var = &entry->var;
259	efi_char16_t *name;
260	unsigned long size;
261	efi_guid_t vendor;
262	u32 attributes;
263	u8 *data;
264	int err;
265
266	if (is_compat()) {
267		struct compat_efi_variable *compat;
268
269		if (count != sizeof(*compat))
270			return -EINVAL;
271
272		compat = (struct compat_efi_variable *)buf;
273		attributes = compat->Attributes;
274		vendor = compat->VendorGuid;
275		name = compat->VariableName;
276		size = compat->DataSize;
277		data = compat->Data;
278
279		err = sanity_check(var, name, vendor, size, attributes, data);
280		if (err)
281			return err;
282
283		copy_out_compat(&entry->var, compat);
284	} else {
285		if (count != sizeof(struct efi_variable))
286			return -EINVAL;
287
288		new_var = (struct efi_variable *)buf;
289
290		attributes = new_var->Attributes;
291		vendor = new_var->VendorGuid;
292		name = new_var->VariableName;
293		size = new_var->DataSize;
294		data = new_var->Data;
295
296		err = sanity_check(var, name, vendor, size, attributes, data);
297		if (err)
298			return err;
299
300		memcpy(&entry->var, new_var, count);
301	}
302
303	err = efivar_entry_set(entry, attributes, size, data, NULL);
304	if (err) {
305		printk(KERN_WARNING "efivars: set_variable() failed: status=%d\n", err);
306		return -EIO;
307	}
308
309	return count;
310}
311
312static ssize_t
313efivar_show_raw(struct efivar_entry *entry, char *buf)
314{
315	struct efi_variable *var = &entry->var;
316	struct compat_efi_variable *compat;
317	size_t size;
318
319	if (!entry || !buf)
320		return 0;
321
322	var->DataSize = 1024;
323	if (efivar_entry_get(entry, &entry->var.Attributes,
324			     &entry->var.DataSize, entry->var.Data))
325		return -EIO;
326
327	if (is_compat()) {
328		compat = (struct compat_efi_variable *)buf;
329
330		size = sizeof(*compat);
331		memcpy(compat->VariableName, var->VariableName,
332			EFI_VAR_NAME_LEN);
333		memcpy(compat->Data, var->Data, sizeof(compat->Data));
334
335		compat->VendorGuid = var->VendorGuid;
336		compat->DataSize = var->DataSize;
337		compat->Attributes = var->Attributes;
338	} else {
339		size = sizeof(*var);
340		memcpy(buf, var, size);
341	}
342
343	return size;
344}
345
346/*
347 * Generic read/write functions that call the specific functions of
348 * the attributes...
349 */
350static ssize_t efivar_attr_show(struct kobject *kobj, struct attribute *attr,
351				char *buf)
352{
353	struct efivar_entry *var = to_efivar_entry(kobj);
354	struct efivar_attribute *efivar_attr = to_efivar_attr(attr);
355	ssize_t ret = -EIO;
356
357	if (!capable(CAP_SYS_ADMIN))
358		return -EACCES;
359
360	if (efivar_attr->show) {
361		ret = efivar_attr->show(var, buf);
362	}
363	return ret;
364}
365
366static ssize_t efivar_attr_store(struct kobject *kobj, struct attribute *attr,
367				const char *buf, size_t count)
368{
369	struct efivar_entry *var = to_efivar_entry(kobj);
370	struct efivar_attribute *efivar_attr = to_efivar_attr(attr);
371	ssize_t ret = -EIO;
372
373	if (!capable(CAP_SYS_ADMIN))
374		return -EACCES;
375
376	if (efivar_attr->store)
377		ret = efivar_attr->store(var, buf, count);
378
379	return ret;
380}
381
382static const struct sysfs_ops efivar_attr_ops = {
383	.show = efivar_attr_show,
384	.store = efivar_attr_store,
385};
386
387static void efivar_release(struct kobject *kobj)
388{
389	struct efivar_entry *var = container_of(kobj, struct efivar_entry, kobj);
390	kfree(var);
391}
392
393static EFIVAR_ATTR(guid, 0400, efivar_guid_read, NULL);
394static EFIVAR_ATTR(attributes, 0400, efivar_attr_read, NULL);
395static EFIVAR_ATTR(size, 0400, efivar_size_read, NULL);
396static EFIVAR_ATTR(data, 0400, efivar_data_read, NULL);
397static EFIVAR_ATTR(raw_var, 0600, efivar_show_raw, efivar_store_raw);
398
399static struct attribute *def_attrs[] = {
400	&efivar_attr_guid.attr,
401	&efivar_attr_size.attr,
402	&efivar_attr_attributes.attr,
403	&efivar_attr_data.attr,
404	&efivar_attr_raw_var.attr,
405	NULL,
406};
407
408static struct kobj_type efivar_ktype = {
409	.release = efivar_release,
410	.sysfs_ops = &efivar_attr_ops,
411	.default_attrs = def_attrs,
412};
413
414static ssize_t efivar_create(struct file *filp, struct kobject *kobj,
415			     struct bin_attribute *bin_attr,
416			     char *buf, loff_t pos, size_t count)
417{
418	struct compat_efi_variable *compat = (struct compat_efi_variable *)buf;
419	struct efi_variable *new_var = (struct efi_variable *)buf;
420	struct efivar_entry *new_entry;
421	bool need_compat = is_compat();
422	efi_char16_t *name;
423	unsigned long size;
424	u32 attributes;
425	u8 *data;
426	int err;
427
428	if (!capable(CAP_SYS_ADMIN))
429		return -EACCES;
430
431	if (need_compat) {
432		if (count != sizeof(*compat))
433			return -EINVAL;
434
435		attributes = compat->Attributes;
436		name = compat->VariableName;
437		size = compat->DataSize;
438		data = compat->Data;
439	} else {
440		if (count != sizeof(*new_var))
441			return -EINVAL;
442
443		attributes = new_var->Attributes;
444		name = new_var->VariableName;
445		size = new_var->DataSize;
446		data = new_var->Data;
447	}
448
449	if ((attributes & ~EFI_VARIABLE_MASK) != 0 ||
450	    efivar_validate(new_var->VendorGuid, name, data,
451			    size) == false) {
452		printk(KERN_ERR "efivars: Malformed variable content\n");
453		return -EINVAL;
454	}
455
456	new_entry = kzalloc(sizeof(*new_entry), GFP_KERNEL);
457	if (!new_entry)
458		return -ENOMEM;
459
460	if (need_compat)
461		copy_out_compat(&new_entry->var, compat);
462	else
463		memcpy(&new_entry->var, new_var, sizeof(*new_var));
464
465	err = efivar_entry_set(new_entry, attributes, size,
466			       data, &efivar_sysfs_list);
467	if (err) {
468		if (err == -EEXIST)
469			err = -EINVAL;
470		goto out;
471	}
472
473	if (efivar_create_sysfs_entry(new_entry)) {
474		printk(KERN_WARNING "efivars: failed to create sysfs entry.\n");
475		kfree(new_entry);
476	}
477	return count;
478
479out:
480	kfree(new_entry);
481	return err;
482}
483
484static ssize_t efivar_delete(struct file *filp, struct kobject *kobj,
485			     struct bin_attribute *bin_attr,
486			     char *buf, loff_t pos, size_t count)
487{
488	struct efi_variable *del_var = (struct efi_variable *)buf;
489	struct compat_efi_variable *compat;
490	struct efivar_entry *entry;
491	efi_char16_t *name;
492	efi_guid_t vendor;
493	int err = 0;
494
495	if (!capable(CAP_SYS_ADMIN))
496		return -EACCES;
497
498	if (is_compat()) {
499		if (count != sizeof(*compat))
500			return -EINVAL;
501
502		compat = (struct compat_efi_variable *)buf;
503		name = compat->VariableName;
504		vendor = compat->VendorGuid;
505	} else {
506		if (count != sizeof(*del_var))
507			return -EINVAL;
508
509		name = del_var->VariableName;
510		vendor = del_var->VendorGuid;
511	}
512
513	efivar_entry_iter_begin();
514	entry = efivar_entry_find(name, vendor, &efivar_sysfs_list, true);
515	if (!entry)
516		err = -EINVAL;
517	else if (__efivar_entry_delete(entry))
518		err = -EIO;
519
520	if (err) {
521		efivar_entry_iter_end();
522		return err;
523	}
524
525	if (!entry->scanning) {
526		efivar_entry_iter_end();
527		efivar_unregister(entry);
528	} else
529		efivar_entry_iter_end();
530
531	/* It's dead Jim.... */
532	return count;
533}
534
535/**
536 * efivar_create_sysfs_entry - create a new entry in sysfs
537 * @new_var: efivar entry to create
538 *
539 * Returns 0 on success, negative error code on failure
540 */
541static int
542efivar_create_sysfs_entry(struct efivar_entry *new_var)
543{
544	int short_name_size;
545	char *short_name;
546	unsigned long utf8_name_size;
547	efi_char16_t *variable_name = new_var->var.VariableName;
548	int ret;
549
550	/*
551	 * Length of the variable bytes in UTF8, plus the '-' separator,
552	 * plus the GUID, plus trailing NUL
553	 */
554	utf8_name_size = ucs2_utf8size(variable_name);
555	short_name_size = utf8_name_size + 1 + EFI_VARIABLE_GUID_LEN + 1;
556
557	short_name = kmalloc(short_name_size, GFP_KERNEL);
558	if (!short_name)
559		return -ENOMEM;
560
561	ucs2_as_utf8(short_name, variable_name, short_name_size);
562
563	/* This is ugly, but necessary to separate one vendor's
564	   private variables from another's.         */
565	short_name[utf8_name_size] = '-';
566	efi_guid_to_str(&new_var->var.VendorGuid,
567			 short_name + utf8_name_size + 1);
568
569	new_var->kobj.kset = efivars_kset;
570
571	ret = kobject_init_and_add(&new_var->kobj, &efivar_ktype,
572				   NULL, "%s", short_name);
573	kfree(short_name);
574	if (ret)
575		return ret;
576
577	kobject_uevent(&new_var->kobj, KOBJ_ADD);
578	efivar_entry_add(new_var, &efivar_sysfs_list);
579
580	return 0;
581}
582
583static int
584create_efivars_bin_attributes(void)
585{
586	struct bin_attribute *attr;
587	int error;
588
589	/* new_var */
590	attr = kzalloc(sizeof(*attr), GFP_KERNEL);
591	if (!attr)
592		return -ENOMEM;
593
594	attr->attr.name = "new_var";
595	attr->attr.mode = 0200;
596	attr->write = efivar_create;
597	efivars_new_var = attr;
598
599	/* del_var */
600	attr = kzalloc(sizeof(*attr), GFP_KERNEL);
601	if (!attr) {
602		error = -ENOMEM;
603		goto out_free;
604	}
605	attr->attr.name = "del_var";
606	attr->attr.mode = 0200;
607	attr->write = efivar_delete;
608	efivars_del_var = attr;
609
610	sysfs_bin_attr_init(efivars_new_var);
611	sysfs_bin_attr_init(efivars_del_var);
612
613	/* Register */
614	error = sysfs_create_bin_file(&efivars_kset->kobj, efivars_new_var);
615	if (error) {
616		printk(KERN_ERR "efivars: unable to create new_var sysfs file"
617			" due to error %d\n", error);
618		goto out_free;
619	}
620
621	error = sysfs_create_bin_file(&efivars_kset->kobj, efivars_del_var);
622	if (error) {
623		printk(KERN_ERR "efivars: unable to create del_var sysfs file"
624			" due to error %d\n", error);
625		sysfs_remove_bin_file(&efivars_kset->kobj, efivars_new_var);
626		goto out_free;
627	}
628
629	return 0;
630out_free:
631	kfree(efivars_del_var);
632	efivars_del_var = NULL;
633	kfree(efivars_new_var);
634	efivars_new_var = NULL;
635	return error;
636}
637
638static int efivar_update_sysfs_entry(efi_char16_t *name, efi_guid_t vendor,
639				     unsigned long name_size, void *data)
640{
641	struct efivar_entry *entry = data;
642
643	if (efivar_entry_find(name, vendor, &efivar_sysfs_list, false))
644		return 0;
645
646	memcpy(entry->var.VariableName, name, name_size);
647	memcpy(&(entry->var.VendorGuid), &vendor, sizeof(efi_guid_t));
648
649	return 1;
650}
651
652static void efivar_update_sysfs_entries(struct work_struct *work)
653{
654	struct efivar_entry *entry;
655	int err;
656
657	/* Add new sysfs entries */
658	while (1) {
659		entry = kzalloc(sizeof(*entry), GFP_KERNEL);
660		if (!entry)
661			return;
662
663		err = efivar_init(efivar_update_sysfs_entry, entry,
664				  true, false, &efivar_sysfs_list);
665		if (!err)
666			break;
667
668		efivar_create_sysfs_entry(entry);
669	}
670
671	kfree(entry);
672}
673
674static int efivars_sysfs_callback(efi_char16_t *name, efi_guid_t vendor,
675				  unsigned long name_size, void *data)
676{
677	struct efivar_entry *entry;
678
679	entry = kzalloc(sizeof(*entry), GFP_KERNEL);
680	if (!entry)
681		return -ENOMEM;
682
683	memcpy(entry->var.VariableName, name, name_size);
684	memcpy(&(entry->var.VendorGuid), &vendor, sizeof(efi_guid_t));
685
686	efivar_create_sysfs_entry(entry);
687
688	return 0;
689}
690
691static int efivar_sysfs_destroy(struct efivar_entry *entry, void *data)
692{
693	efivar_entry_remove(entry);
694	efivar_unregister(entry);
695	return 0;
696}
697
698static void efivars_sysfs_exit(void)
699{
700	/* Remove all entries and destroy */
701	__efivar_entry_iter(efivar_sysfs_destroy, &efivar_sysfs_list, NULL, NULL);
702
703	if (efivars_new_var)
704		sysfs_remove_bin_file(&efivars_kset->kobj, efivars_new_var);
705	if (efivars_del_var)
706		sysfs_remove_bin_file(&efivars_kset->kobj, efivars_del_var);
707	kfree(efivars_new_var);
708	kfree(efivars_del_var);
709	kset_unregister(efivars_kset);
710}
711
712int efivars_sysfs_init(void)
713{
714	struct kobject *parent_kobj = efivars_kobject();
715	int error = 0;
716
717	if (!efi_enabled(EFI_RUNTIME_SERVICES))
718		return -ENODEV;
719
720	/* No efivars has been registered yet */
721	if (!parent_kobj)
722		return 0;
723
724	printk(KERN_INFO "EFI Variables Facility v%s %s\n", EFIVARS_VERSION,
725	       EFIVARS_DATE);
726
727	efivars_kset = kset_create_and_add("vars", NULL, parent_kobj);
728	if (!efivars_kset) {
729		printk(KERN_ERR "efivars: Subsystem registration failed.\n");
730		return -ENOMEM;
731	}
732
733	efivar_init(efivars_sysfs_callback, NULL, false,
734		    true, &efivar_sysfs_list);
735
736	error = create_efivars_bin_attributes();
737	if (error) {
738		efivars_sysfs_exit();
739		return error;
740	}
741
742	INIT_WORK(&efivar_work, efivar_update_sysfs_entries);
743
744	return 0;
745}
746EXPORT_SYMBOL_GPL(efivars_sysfs_init);
747
748module_init(efivars_sysfs_init);
749module_exit(efivars_sysfs_exit);
750