Linux 4.2.1
[linux/fpc-iii.git] / drivers / firmware / efi / vars.c
blob70a0fb10517f94ea5b28bada280d9935f0693cc7
1 /*
2 * Originally from efivars.c
4 * Copyright (C) 2001,2003,2004 Dell <Matt_Domsch@dell.com>
5 * Copyright (C) 2004 Intel Corporation <matthew.e.tolentino@intel.com>
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License as published by
9 * the Free Software Foundation; either version 2 of the License, or
10 * (at your option) any later version.
12 * This program is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 * GNU General Public License for more details.
17 * You should have received a copy of the GNU General Public License
18 * along with this program; if not, write to the Free Software
19 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
22 #include <linux/capability.h>
23 #include <linux/types.h>
24 #include <linux/errno.h>
25 #include <linux/init.h>
26 #include <linux/mm.h>
27 #include <linux/module.h>
28 #include <linux/string.h>
29 #include <linux/smp.h>
30 #include <linux/efi.h>
31 #include <linux/sysfs.h>
32 #include <linux/device.h>
33 #include <linux/slab.h>
34 #include <linux/ctype.h>
35 #include <linux/ucs2_string.h>
37 /* Private pointer to registered efivars */
38 static struct efivars *__efivars;
40 static bool efivar_wq_enabled = true;
41 DECLARE_WORK(efivar_work, NULL);
42 EXPORT_SYMBOL_GPL(efivar_work);
44 static bool
45 validate_device_path(efi_char16_t *var_name, int match, u8 *buffer,
46 unsigned long len)
48 struct efi_generic_dev_path *node;
49 int offset = 0;
51 node = (struct efi_generic_dev_path *)buffer;
53 if (len < sizeof(*node))
54 return false;
56 while (offset <= len - sizeof(*node) &&
57 node->length >= sizeof(*node) &&
58 node->length <= len - offset) {
59 offset += node->length;
61 if ((node->type == EFI_DEV_END_PATH ||
62 node->type == EFI_DEV_END_PATH2) &&
63 node->sub_type == EFI_DEV_END_ENTIRE)
64 return true;
66 node = (struct efi_generic_dev_path *)(buffer + offset);
70 * If we're here then either node->length pointed past the end
71 * of the buffer or we reached the end of the buffer without
72 * finding a device path end node.
74 return false;
77 static bool
78 validate_boot_order(efi_char16_t *var_name, int match, u8 *buffer,
79 unsigned long len)
81 /* An array of 16-bit integers */
82 if ((len % 2) != 0)
83 return false;
85 return true;
88 static bool
89 validate_load_option(efi_char16_t *var_name, int match, u8 *buffer,
90 unsigned long len)
92 u16 filepathlength;
93 int i, desclength = 0, namelen;
95 namelen = ucs2_strnlen(var_name, EFI_VAR_NAME_LEN);
97 /* Either "Boot" or "Driver" followed by four digits of hex */
98 for (i = match; i < match+4; i++) {
99 if (var_name[i] > 127 ||
100 hex_to_bin(var_name[i] & 0xff) < 0)
101 return true;
104 /* Reject it if there's 4 digits of hex and then further content */
105 if (namelen > match + 4)
106 return false;
108 /* A valid entry must be at least 8 bytes */
109 if (len < 8)
110 return false;
112 filepathlength = buffer[4] | buffer[5] << 8;
115 * There's no stored length for the description, so it has to be
116 * found by hand
118 desclength = ucs2_strsize((efi_char16_t *)(buffer + 6), len - 6) + 2;
120 /* Each boot entry must have a descriptor */
121 if (!desclength)
122 return false;
125 * If the sum of the length of the description, the claimed filepath
126 * length and the original header are greater than the length of the
127 * variable, it's malformed
129 if ((desclength + filepathlength + 6) > len)
130 return false;
133 * And, finally, check the filepath
135 return validate_device_path(var_name, match, buffer + desclength + 6,
136 filepathlength);
139 static bool
140 validate_uint16(efi_char16_t *var_name, int match, u8 *buffer,
141 unsigned long len)
143 /* A single 16-bit integer */
144 if (len != 2)
145 return false;
147 return true;
150 static bool
151 validate_ascii_string(efi_char16_t *var_name, int match, u8 *buffer,
152 unsigned long len)
154 int i;
156 for (i = 0; i < len; i++) {
157 if (buffer[i] > 127)
158 return false;
160 if (buffer[i] == 0)
161 return true;
164 return false;
167 struct variable_validate {
168 char *name;
169 bool (*validate)(efi_char16_t *var_name, int match, u8 *data,
170 unsigned long len);
173 static const struct variable_validate variable_validate[] = {
174 { "BootNext", validate_uint16 },
175 { "BootOrder", validate_boot_order },
176 { "DriverOrder", validate_boot_order },
177 { "Boot*", validate_load_option },
178 { "Driver*", validate_load_option },
179 { "ConIn", validate_device_path },
180 { "ConInDev", validate_device_path },
181 { "ConOut", validate_device_path },
182 { "ConOutDev", validate_device_path },
183 { "ErrOut", validate_device_path },
184 { "ErrOutDev", validate_device_path },
185 { "Timeout", validate_uint16 },
186 { "Lang", validate_ascii_string },
187 { "PlatformLang", validate_ascii_string },
188 { "", NULL },
191 bool
192 efivar_validate(efi_char16_t *var_name, u8 *data, unsigned long len)
194 int i;
195 u16 *unicode_name = var_name;
197 for (i = 0; variable_validate[i].validate != NULL; i++) {
198 const char *name = variable_validate[i].name;
199 int match;
201 for (match = 0; ; match++) {
202 char c = name[match];
203 u16 u = unicode_name[match];
205 /* All special variables are plain ascii */
206 if (u > 127)
207 return true;
209 /* Wildcard in the matching name means we've matched */
210 if (c == '*')
211 return variable_validate[i].validate(var_name,
212 match, data, len);
214 /* Case sensitive match */
215 if (c != u)
216 break;
218 /* Reached the end of the string while matching */
219 if (!c)
220 return variable_validate[i].validate(var_name,
221 match, data, len);
225 return true;
227 EXPORT_SYMBOL_GPL(efivar_validate);
229 static efi_status_t
230 check_var_size(u32 attributes, unsigned long size)
232 const struct efivar_operations *fops = __efivars->ops;
234 if (!fops->query_variable_store)
235 return EFI_UNSUPPORTED;
237 return fops->query_variable_store(attributes, size);
240 static int efi_status_to_err(efi_status_t status)
242 int err;
244 switch (status) {
245 case EFI_SUCCESS:
246 err = 0;
247 break;
248 case EFI_INVALID_PARAMETER:
249 err = -EINVAL;
250 break;
251 case EFI_OUT_OF_RESOURCES:
252 err = -ENOSPC;
253 break;
254 case EFI_DEVICE_ERROR:
255 err = -EIO;
256 break;
257 case EFI_WRITE_PROTECTED:
258 err = -EROFS;
259 break;
260 case EFI_SECURITY_VIOLATION:
261 err = -EACCES;
262 break;
263 case EFI_NOT_FOUND:
264 err = -ENOENT;
265 break;
266 default:
267 err = -EINVAL;
270 return err;
273 static bool variable_is_present(efi_char16_t *variable_name, efi_guid_t *vendor,
274 struct list_head *head)
276 struct efivar_entry *entry, *n;
277 unsigned long strsize1, strsize2;
278 bool found = false;
280 strsize1 = ucs2_strsize(variable_name, 1024);
281 list_for_each_entry_safe(entry, n, head, list) {
282 strsize2 = ucs2_strsize(entry->var.VariableName, 1024);
283 if (strsize1 == strsize2 &&
284 !memcmp(variable_name, &(entry->var.VariableName),
285 strsize2) &&
286 !efi_guidcmp(entry->var.VendorGuid,
287 *vendor)) {
288 found = true;
289 break;
292 return found;
296 * Returns the size of variable_name, in bytes, including the
297 * terminating NULL character, or variable_name_size if no NULL
298 * character is found among the first variable_name_size bytes.
300 static unsigned long var_name_strnsize(efi_char16_t *variable_name,
301 unsigned long variable_name_size)
303 unsigned long len;
304 efi_char16_t c;
307 * The variable name is, by definition, a NULL-terminated
308 * string, so make absolutely sure that variable_name_size is
309 * the value we expect it to be. If not, return the real size.
311 for (len = 2; len <= variable_name_size; len += sizeof(c)) {
312 c = variable_name[(len / sizeof(c)) - 1];
313 if (!c)
314 break;
317 return min(len, variable_name_size);
321 * Print a warning when duplicate EFI variables are encountered and
322 * disable the sysfs workqueue since the firmware is buggy.
324 static void dup_variable_bug(efi_char16_t *str16, efi_guid_t *vendor_guid,
325 unsigned long len16)
327 size_t i, len8 = len16 / sizeof(efi_char16_t);
328 char *str8;
331 * Disable the workqueue since the algorithm it uses for
332 * detecting new variables won't work with this buggy
333 * implementation of GetNextVariableName().
335 efivar_wq_enabled = false;
337 str8 = kzalloc(len8, GFP_KERNEL);
338 if (!str8)
339 return;
341 for (i = 0; i < len8; i++)
342 str8[i] = str16[i];
344 printk(KERN_WARNING "efivars: duplicate variable: %s-%pUl\n",
345 str8, vendor_guid);
346 kfree(str8);
350 * efivar_init - build the initial list of EFI variables
351 * @func: callback function to invoke for every variable
352 * @data: function-specific data to pass to @func
353 * @atomic: do we need to execute the @func-loop atomically?
354 * @duplicates: error if we encounter duplicates on @head?
355 * @head: initialised head of variable list
357 * Get every EFI variable from the firmware and invoke @func. @func
358 * should call efivar_entry_add() to build the list of variables.
360 * Returns 0 on success, or a kernel error code on failure.
362 int efivar_init(int (*func)(efi_char16_t *, efi_guid_t, unsigned long, void *),
363 void *data, bool atomic, bool duplicates,
364 struct list_head *head)
366 const struct efivar_operations *ops = __efivars->ops;
367 unsigned long variable_name_size = 1024;
368 efi_char16_t *variable_name;
369 efi_status_t status;
370 efi_guid_t vendor_guid;
371 int err = 0;
373 variable_name = kzalloc(variable_name_size, GFP_KERNEL);
374 if (!variable_name) {
375 printk(KERN_ERR "efivars: Memory allocation failed.\n");
376 return -ENOMEM;
379 spin_lock_irq(&__efivars->lock);
382 * Per EFI spec, the maximum storage allocated for both
383 * the variable name and variable data is 1024 bytes.
386 do {
387 variable_name_size = 1024;
389 status = ops->get_next_variable(&variable_name_size,
390 variable_name,
391 &vendor_guid);
392 switch (status) {
393 case EFI_SUCCESS:
394 if (!atomic)
395 spin_unlock_irq(&__efivars->lock);
397 variable_name_size = var_name_strnsize(variable_name,
398 variable_name_size);
401 * Some firmware implementations return the
402 * same variable name on multiple calls to
403 * get_next_variable(). Terminate the loop
404 * immediately as there is no guarantee that
405 * we'll ever see a different variable name,
406 * and may end up looping here forever.
408 if (duplicates &&
409 variable_is_present(variable_name, &vendor_guid, head)) {
410 dup_variable_bug(variable_name, &vendor_guid,
411 variable_name_size);
412 if (!atomic)
413 spin_lock_irq(&__efivars->lock);
415 status = EFI_NOT_FOUND;
416 break;
419 err = func(variable_name, vendor_guid, variable_name_size, data);
420 if (err)
421 status = EFI_NOT_FOUND;
423 if (!atomic)
424 spin_lock_irq(&__efivars->lock);
426 break;
427 case EFI_NOT_FOUND:
428 break;
429 default:
430 printk(KERN_WARNING "efivars: get_next_variable: status=%lx\n",
431 status);
432 status = EFI_NOT_FOUND;
433 break;
436 } while (status != EFI_NOT_FOUND);
438 spin_unlock_irq(&__efivars->lock);
440 kfree(variable_name);
442 return err;
444 EXPORT_SYMBOL_GPL(efivar_init);
447 * efivar_entry_add - add entry to variable list
448 * @entry: entry to add to list
449 * @head: list head
451 void efivar_entry_add(struct efivar_entry *entry, struct list_head *head)
453 spin_lock_irq(&__efivars->lock);
454 list_add(&entry->list, head);
455 spin_unlock_irq(&__efivars->lock);
457 EXPORT_SYMBOL_GPL(efivar_entry_add);
460 * efivar_entry_remove - remove entry from variable list
461 * @entry: entry to remove from list
463 void efivar_entry_remove(struct efivar_entry *entry)
465 spin_lock_irq(&__efivars->lock);
466 list_del(&entry->list);
467 spin_unlock_irq(&__efivars->lock);
469 EXPORT_SYMBOL_GPL(efivar_entry_remove);
472 * efivar_entry_list_del_unlock - remove entry from variable list
473 * @entry: entry to remove
475 * Remove @entry from the variable list and release the list lock.
477 * NOTE: slightly weird locking semantics here - we expect to be
478 * called with the efivars lock already held, and we release it before
479 * returning. This is because this function is usually called after
480 * set_variable() while the lock is still held.
482 static void efivar_entry_list_del_unlock(struct efivar_entry *entry)
484 lockdep_assert_held(&__efivars->lock);
486 list_del(&entry->list);
487 spin_unlock_irq(&__efivars->lock);
491 * __efivar_entry_delete - delete an EFI variable
492 * @entry: entry containing EFI variable to delete
494 * Delete the variable from the firmware but leave @entry on the
495 * variable list.
497 * This function differs from efivar_entry_delete() because it does
498 * not remove @entry from the variable list. Also, it is safe to be
499 * called from within a efivar_entry_iter_begin() and
500 * efivar_entry_iter_end() region, unlike efivar_entry_delete().
502 * Returns 0 on success, or a converted EFI status code if
503 * set_variable() fails.
505 int __efivar_entry_delete(struct efivar_entry *entry)
507 const struct efivar_operations *ops = __efivars->ops;
508 efi_status_t status;
510 lockdep_assert_held(&__efivars->lock);
512 status = ops->set_variable(entry->var.VariableName,
513 &entry->var.VendorGuid,
514 0, 0, NULL);
516 return efi_status_to_err(status);
518 EXPORT_SYMBOL_GPL(__efivar_entry_delete);
521 * efivar_entry_delete - delete variable and remove entry from list
522 * @entry: entry containing variable to delete
524 * Delete the variable from the firmware and remove @entry from the
525 * variable list. It is the caller's responsibility to free @entry
526 * once we return.
528 * Returns 0 on success, or a converted EFI status code if
529 * set_variable() fails.
531 int efivar_entry_delete(struct efivar_entry *entry)
533 const struct efivar_operations *ops = __efivars->ops;
534 efi_status_t status;
536 spin_lock_irq(&__efivars->lock);
537 status = ops->set_variable(entry->var.VariableName,
538 &entry->var.VendorGuid,
539 0, 0, NULL);
540 if (!(status == EFI_SUCCESS || status == EFI_NOT_FOUND)) {
541 spin_unlock_irq(&__efivars->lock);
542 return efi_status_to_err(status);
545 efivar_entry_list_del_unlock(entry);
546 return 0;
548 EXPORT_SYMBOL_GPL(efivar_entry_delete);
551 * efivar_entry_set - call set_variable()
552 * @entry: entry containing the EFI variable to write
553 * @attributes: variable attributes
554 * @size: size of @data buffer
555 * @data: buffer containing variable data
556 * @head: head of variable list
558 * Calls set_variable() for an EFI variable. If creating a new EFI
559 * variable, this function is usually followed by efivar_entry_add().
561 * Before writing the variable, the remaining EFI variable storage
562 * space is checked to ensure there is enough room available.
564 * If @head is not NULL a lookup is performed to determine whether
565 * the entry is already on the list.
567 * Returns 0 on success, -EEXIST if a lookup is performed and the entry
568 * already exists on the list, or a converted EFI status code if
569 * set_variable() fails.
571 int efivar_entry_set(struct efivar_entry *entry, u32 attributes,
572 unsigned long size, void *data, struct list_head *head)
574 const struct efivar_operations *ops = __efivars->ops;
575 efi_status_t status;
576 efi_char16_t *name = entry->var.VariableName;
577 efi_guid_t vendor = entry->var.VendorGuid;
579 spin_lock_irq(&__efivars->lock);
581 if (head && efivar_entry_find(name, vendor, head, false)) {
582 spin_unlock_irq(&__efivars->lock);
583 return -EEXIST;
586 status = check_var_size(attributes, size + ucs2_strsize(name, 1024));
587 if (status == EFI_SUCCESS || status == EFI_UNSUPPORTED)
588 status = ops->set_variable(name, &vendor,
589 attributes, size, data);
591 spin_unlock_irq(&__efivars->lock);
593 return efi_status_to_err(status);
596 EXPORT_SYMBOL_GPL(efivar_entry_set);
599 * efivar_entry_set_nonblocking - call set_variable_nonblocking()
601 * This function is guaranteed to not block and is suitable for calling
602 * from crash/panic handlers.
604 * Crucially, this function will not block if it cannot acquire
605 * __efivars->lock. Instead, it returns -EBUSY.
607 static int
608 efivar_entry_set_nonblocking(efi_char16_t *name, efi_guid_t vendor,
609 u32 attributes, unsigned long size, void *data)
611 const struct efivar_operations *ops = __efivars->ops;
612 unsigned long flags;
613 efi_status_t status;
615 if (!spin_trylock_irqsave(&__efivars->lock, flags))
616 return -EBUSY;
618 status = check_var_size(attributes, size + ucs2_strsize(name, 1024));
619 if (status != EFI_SUCCESS) {
620 spin_unlock_irqrestore(&__efivars->lock, flags);
621 return -ENOSPC;
624 status = ops->set_variable_nonblocking(name, &vendor, attributes,
625 size, data);
627 spin_unlock_irqrestore(&__efivars->lock, flags);
628 return efi_status_to_err(status);
632 * efivar_entry_set_safe - call set_variable() if enough space in firmware
633 * @name: buffer containing the variable name
634 * @vendor: variable vendor guid
635 * @attributes: variable attributes
636 * @block: can we block in this context?
637 * @size: size of @data buffer
638 * @data: buffer containing variable data
640 * Ensures there is enough free storage in the firmware for this variable, and
641 * if so, calls set_variable(). If creating a new EFI variable, this function
642 * is usually followed by efivar_entry_add().
644 * Returns 0 on success, -ENOSPC if the firmware does not have enough
645 * space for set_variable() to succeed, or a converted EFI status code
646 * if set_variable() fails.
648 int efivar_entry_set_safe(efi_char16_t *name, efi_guid_t vendor, u32 attributes,
649 bool block, unsigned long size, void *data)
651 const struct efivar_operations *ops = __efivars->ops;
652 unsigned long flags;
653 efi_status_t status;
655 if (!ops->query_variable_store)
656 return -ENOSYS;
659 * If the EFI variable backend provides a non-blocking
660 * ->set_variable() operation and we're in a context where we
661 * cannot block, then we need to use it to avoid live-locks,
662 * since the implication is that the regular ->set_variable()
663 * will block.
665 * If no ->set_variable_nonblocking() is provided then
666 * ->set_variable() is assumed to be non-blocking.
668 if (!block && ops->set_variable_nonblocking)
669 return efivar_entry_set_nonblocking(name, vendor, attributes,
670 size, data);
672 if (!block) {
673 if (!spin_trylock_irqsave(&__efivars->lock, flags))
674 return -EBUSY;
675 } else {
676 spin_lock_irqsave(&__efivars->lock, flags);
679 status = check_var_size(attributes, size + ucs2_strsize(name, 1024));
680 if (status != EFI_SUCCESS) {
681 spin_unlock_irqrestore(&__efivars->lock, flags);
682 return -ENOSPC;
685 status = ops->set_variable(name, &vendor, attributes, size, data);
687 spin_unlock_irqrestore(&__efivars->lock, flags);
689 return efi_status_to_err(status);
691 EXPORT_SYMBOL_GPL(efivar_entry_set_safe);
694 * efivar_entry_find - search for an entry
695 * @name: the EFI variable name
696 * @guid: the EFI variable vendor's guid
697 * @head: head of the variable list
698 * @remove: should we remove the entry from the list?
700 * Search for an entry on the variable list that has the EFI variable
701 * name @name and vendor guid @guid. If an entry is found on the list
702 * and @remove is true, the entry is removed from the list.
704 * The caller MUST call efivar_entry_iter_begin() and
705 * efivar_entry_iter_end() before and after the invocation of this
706 * function, respectively.
708 * Returns the entry if found on the list, %NULL otherwise.
710 struct efivar_entry *efivar_entry_find(efi_char16_t *name, efi_guid_t guid,
711 struct list_head *head, bool remove)
713 struct efivar_entry *entry, *n;
714 int strsize1, strsize2;
715 bool found = false;
717 lockdep_assert_held(&__efivars->lock);
719 list_for_each_entry_safe(entry, n, head, list) {
720 strsize1 = ucs2_strsize(name, 1024);
721 strsize2 = ucs2_strsize(entry->var.VariableName, 1024);
722 if (strsize1 == strsize2 &&
723 !memcmp(name, &(entry->var.VariableName), strsize1) &&
724 !efi_guidcmp(guid, entry->var.VendorGuid)) {
725 found = true;
726 break;
730 if (!found)
731 return NULL;
733 if (remove) {
734 if (entry->scanning) {
736 * The entry will be deleted
737 * after scanning is completed.
739 entry->deleting = true;
740 } else
741 list_del(&entry->list);
744 return entry;
746 EXPORT_SYMBOL_GPL(efivar_entry_find);
749 * efivar_entry_size - obtain the size of a variable
750 * @entry: entry for this variable
751 * @size: location to store the variable's size
753 int efivar_entry_size(struct efivar_entry *entry, unsigned long *size)
755 const struct efivar_operations *ops = __efivars->ops;
756 efi_status_t status;
758 *size = 0;
760 spin_lock_irq(&__efivars->lock);
761 status = ops->get_variable(entry->var.VariableName,
762 &entry->var.VendorGuid, NULL, size, NULL);
763 spin_unlock_irq(&__efivars->lock);
765 if (status != EFI_BUFFER_TOO_SMALL)
766 return efi_status_to_err(status);
768 return 0;
770 EXPORT_SYMBOL_GPL(efivar_entry_size);
773 * __efivar_entry_get - call get_variable()
774 * @entry: read data for this variable
775 * @attributes: variable attributes
776 * @size: size of @data buffer
777 * @data: buffer to store variable data
779 * The caller MUST call efivar_entry_iter_begin() and
780 * efivar_entry_iter_end() before and after the invocation of this
781 * function, respectively.
783 int __efivar_entry_get(struct efivar_entry *entry, u32 *attributes,
784 unsigned long *size, void *data)
786 const struct efivar_operations *ops = __efivars->ops;
787 efi_status_t status;
789 lockdep_assert_held(&__efivars->lock);
791 status = ops->get_variable(entry->var.VariableName,
792 &entry->var.VendorGuid,
793 attributes, size, data);
795 return efi_status_to_err(status);
797 EXPORT_SYMBOL_GPL(__efivar_entry_get);
800 * efivar_entry_get - call get_variable()
801 * @entry: read data for this variable
802 * @attributes: variable attributes
803 * @size: size of @data buffer
804 * @data: buffer to store variable data
806 int efivar_entry_get(struct efivar_entry *entry, u32 *attributes,
807 unsigned long *size, void *data)
809 const struct efivar_operations *ops = __efivars->ops;
810 efi_status_t status;
812 spin_lock_irq(&__efivars->lock);
813 status = ops->get_variable(entry->var.VariableName,
814 &entry->var.VendorGuid,
815 attributes, size, data);
816 spin_unlock_irq(&__efivars->lock);
818 return efi_status_to_err(status);
820 EXPORT_SYMBOL_GPL(efivar_entry_get);
823 * efivar_entry_set_get_size - call set_variable() and get new size (atomic)
824 * @entry: entry containing variable to set and get
825 * @attributes: attributes of variable to be written
826 * @size: size of data buffer
827 * @data: buffer containing data to write
828 * @set: did the set_variable() call succeed?
830 * This is a pretty special (complex) function. See efivarfs_file_write().
832 * Atomically call set_variable() for @entry and if the call is
833 * successful, return the new size of the variable from get_variable()
834 * in @size. The success of set_variable() is indicated by @set.
836 * Returns 0 on success, -EINVAL if the variable data is invalid,
837 * -ENOSPC if the firmware does not have enough available space, or a
838 * converted EFI status code if either of set_variable() or
839 * get_variable() fail.
841 * If the EFI variable does not exist when calling set_variable()
842 * (EFI_NOT_FOUND), @entry is removed from the variable list.
844 int efivar_entry_set_get_size(struct efivar_entry *entry, u32 attributes,
845 unsigned long *size, void *data, bool *set)
847 const struct efivar_operations *ops = __efivars->ops;
848 efi_char16_t *name = entry->var.VariableName;
849 efi_guid_t *vendor = &entry->var.VendorGuid;
850 efi_status_t status;
851 int err;
853 *set = false;
855 if (efivar_validate(name, data, *size) == false)
856 return -EINVAL;
859 * The lock here protects the get_variable call, the conditional
860 * set_variable call, and removal of the variable from the efivars
861 * list (in the case of an authenticated delete).
863 spin_lock_irq(&__efivars->lock);
866 * Ensure that the available space hasn't shrunk below the safe level
868 status = check_var_size(attributes, *size + ucs2_strsize(name, 1024));
869 if (status != EFI_SUCCESS) {
870 if (status != EFI_UNSUPPORTED) {
871 err = efi_status_to_err(status);
872 goto out;
875 if (*size > 65536) {
876 err = -ENOSPC;
877 goto out;
881 status = ops->set_variable(name, vendor, attributes, *size, data);
882 if (status != EFI_SUCCESS) {
883 err = efi_status_to_err(status);
884 goto out;
887 *set = true;
890 * Writing to the variable may have caused a change in size (which
891 * could either be an append or an overwrite), or the variable to be
892 * deleted. Perform a GetVariable() so we can tell what actually
893 * happened.
895 *size = 0;
896 status = ops->get_variable(entry->var.VariableName,
897 &entry->var.VendorGuid,
898 NULL, size, NULL);
900 if (status == EFI_NOT_FOUND)
901 efivar_entry_list_del_unlock(entry);
902 else
903 spin_unlock_irq(&__efivars->lock);
905 if (status && status != EFI_BUFFER_TOO_SMALL)
906 return efi_status_to_err(status);
908 return 0;
910 out:
911 spin_unlock_irq(&__efivars->lock);
912 return err;
915 EXPORT_SYMBOL_GPL(efivar_entry_set_get_size);
918 * efivar_entry_iter_begin - begin iterating the variable list
920 * Lock the variable list to prevent entry insertion and removal until
921 * efivar_entry_iter_end() is called. This function is usually used in
922 * conjunction with __efivar_entry_iter() or efivar_entry_iter().
924 void efivar_entry_iter_begin(void)
926 spin_lock_irq(&__efivars->lock);
928 EXPORT_SYMBOL_GPL(efivar_entry_iter_begin);
931 * efivar_entry_iter_end - finish iterating the variable list
933 * Unlock the variable list and allow modifications to the list again.
935 void efivar_entry_iter_end(void)
937 spin_unlock_irq(&__efivars->lock);
939 EXPORT_SYMBOL_GPL(efivar_entry_iter_end);
942 * __efivar_entry_iter - iterate over variable list
943 * @func: callback function
944 * @head: head of the variable list
945 * @data: function-specific data to pass to callback
946 * @prev: entry to begin iterating from
948 * Iterate over the list of EFI variables and call @func with every
949 * entry on the list. It is safe for @func to remove entries in the
950 * list via efivar_entry_delete().
952 * You MUST call efivar_enter_iter_begin() before this function, and
953 * efivar_entry_iter_end() afterwards.
955 * It is possible to begin iteration from an arbitrary entry within
956 * the list by passing @prev. @prev is updated on return to point to
957 * the last entry passed to @func. To begin iterating from the
958 * beginning of the list @prev must be %NULL.
960 * The restrictions for @func are the same as documented for
961 * efivar_entry_iter().
963 int __efivar_entry_iter(int (*func)(struct efivar_entry *, void *),
964 struct list_head *head, void *data,
965 struct efivar_entry **prev)
967 struct efivar_entry *entry, *n;
968 int err = 0;
970 if (!prev || !*prev) {
971 list_for_each_entry_safe(entry, n, head, list) {
972 err = func(entry, data);
973 if (err)
974 break;
977 if (prev)
978 *prev = entry;
980 return err;
984 list_for_each_entry_safe_continue((*prev), n, head, list) {
985 err = func(*prev, data);
986 if (err)
987 break;
990 return err;
992 EXPORT_SYMBOL_GPL(__efivar_entry_iter);
995 * efivar_entry_iter - iterate over variable list
996 * @func: callback function
997 * @head: head of variable list
998 * @data: function-specific data to pass to callback
1000 * Iterate over the list of EFI variables and call @func with every
1001 * entry on the list. It is safe for @func to remove entries in the
1002 * list via efivar_entry_delete() while iterating.
1004 * Some notes for the callback function:
1005 * - a non-zero return value indicates an error and terminates the loop
1006 * - @func is called from atomic context
1008 int efivar_entry_iter(int (*func)(struct efivar_entry *, void *),
1009 struct list_head *head, void *data)
1011 int err = 0;
1013 efivar_entry_iter_begin();
1014 err = __efivar_entry_iter(func, head, data, NULL);
1015 efivar_entry_iter_end();
1017 return err;
1019 EXPORT_SYMBOL_GPL(efivar_entry_iter);
1022 * efivars_kobject - get the kobject for the registered efivars
1024 * If efivars_register() has not been called we return NULL,
1025 * otherwise return the kobject used at registration time.
1027 struct kobject *efivars_kobject(void)
1029 if (!__efivars)
1030 return NULL;
1032 return __efivars->kobject;
1034 EXPORT_SYMBOL_GPL(efivars_kobject);
1037 * efivar_run_worker - schedule the efivar worker thread
1039 void efivar_run_worker(void)
1041 if (efivar_wq_enabled)
1042 schedule_work(&efivar_work);
1044 EXPORT_SYMBOL_GPL(efivar_run_worker);
1047 * efivars_register - register an efivars
1048 * @efivars: efivars to register
1049 * @ops: efivars operations
1050 * @kobject: @efivars-specific kobject
1052 * Only a single efivars can be registered at any time.
1054 int efivars_register(struct efivars *efivars,
1055 const struct efivar_operations *ops,
1056 struct kobject *kobject)
1058 spin_lock_init(&efivars->lock);
1059 efivars->ops = ops;
1060 efivars->kobject = kobject;
1062 __efivars = efivars;
1064 return 0;
1066 EXPORT_SYMBOL_GPL(efivars_register);
1069 * efivars_unregister - unregister an efivars
1070 * @efivars: efivars to unregister
1072 * The caller must have already removed every entry from the list,
1073 * failure to do so is an error.
1075 int efivars_unregister(struct efivars *efivars)
1077 int rv;
1079 if (!__efivars) {
1080 printk(KERN_ERR "efivars not registered\n");
1081 rv = -EINVAL;
1082 goto out;
1085 if (__efivars != efivars) {
1086 rv = -EINVAL;
1087 goto out;
1090 __efivars = NULL;
1092 rv = 0;
1093 out:
1094 return rv;
1096 EXPORT_SYMBOL_GPL(efivars_unregister);