2 * EFI Variables - 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 code takes all variables accessible from EFI runtime and
8 * exports them via sysfs
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.
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.
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
26 * 17 May 2004 - Matt Domsch <Matt_Domsch@dell.com>
27 * remove check for efi_enabled in exit
30 * 26 Apr 2004 - Matt Domsch <Matt_Domsch@dell.com>
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
38 * 10 Dec 2002 - Matt Domsch <Matt_Domsch@dell.com>
39 * fix locking per Peter Chubb's findings
41 * 25 Mar 2002 - Matt Domsch <Matt_Domsch@dell.com>
42 * move uuid_unparse() to include/asm-ia64/efi.h:efi_guid_unparse()
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
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
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.
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
64 * 26 February 2001 - Matt Domsch <Matt_Domsch@dell.com>
65 * v0.01 release to linux-ia64@linuxia64.org
68 #include <linux/capability.h>
69 #include <linux/types.h>
70 #include <linux/errno.h>
71 #include <linux/init.h>
73 #include <linux/module.h>
74 #include <linux/string.h>
75 #include <linux/smp.h>
76 #include <linux/efi.h>
77 #include <linux/sysfs.h>
78 #include <linux/kobject.h>
79 #include <linux/device.h>
81 #include <asm/uaccess.h>
83 #define EFIVARS_VERSION "0.08"
84 #define EFIVARS_DATE "2004-May-17"
86 MODULE_AUTHOR("Matt Domsch <Matt_Domsch@Dell.com>");
87 MODULE_DESCRIPTION("sysfs interface to EFI Variables");
88 MODULE_LICENSE("GPL");
89 MODULE_VERSION(EFIVARS_VERSION
);
92 * efivars_lock protects two things:
93 * 1) efivar_list - adds, removals, reads, writes
94 * 2) efi.[gs]et_variable() calls.
95 * It must not be held when creating sysfs entries or calling kmalloc.
96 * efi.get_next_variable() is only called from efivars_init(),
97 * which is protected by the BKL, so that path is safe.
99 static DEFINE_SPINLOCK(efivars_lock
);
100 static LIST_HEAD(efivar_list
);
103 * The maximum size of VariableName + Data = 1024
104 * Therefore, it's reasonable to save that much
105 * space in each part of the structure,
106 * and we use a page for reading/writing.
109 struct efi_variable
{
110 efi_char16_t VariableName
[1024/sizeof(efi_char16_t
)];
111 efi_guid_t VendorGuid
;
112 unsigned long DataSize
;
116 } __attribute__((packed
));
119 struct efivar_entry
{
120 struct efi_variable var
;
121 struct list_head list
;
125 struct efivar_attribute
{
126 struct attribute attr
;
127 ssize_t (*show
) (struct efivar_entry
*entry
, char *buf
);
128 ssize_t (*store
)(struct efivar_entry
*entry
, const char *buf
, size_t count
);
132 #define EFI_ATTR(_name, _mode, _show, _store) \
133 struct subsys_attribute efi_attr_##_name = { \
134 .attr = {.name = __stringify(_name), .mode = _mode}, \
139 #define EFIVAR_ATTR(_name, _mode, _show, _store) \
140 struct efivar_attribute efivar_attr_##_name = { \
141 .attr = {.name = __stringify(_name), .mode = _mode}, \
146 #define to_efivar_attr(_attr) container_of(_attr, struct efivar_attribute, attr)
147 #define to_efivar_entry(obj) container_of(obj, struct efivar_entry, kobj)
150 * Prototype for sysfs creation function
153 efivar_create_sysfs_entry(unsigned long variable_name_size
,
154 efi_char16_t
*variable_name
,
155 efi_guid_t
*vendor_guid
);
157 /* Return the number of unicode characters in data */
159 utf8_strlen(efi_char16_t
*data
, unsigned long maxlength
)
161 unsigned long length
= 0;
163 while (*data
++ != 0 && length
< maxlength
)
169 * Return the number of bytes is the length of this string
170 * Note: this is NOT the same as the number of unicode characters
172 static inline unsigned long
173 utf8_strsize(efi_char16_t
*data
, unsigned long maxlength
)
175 return utf8_strlen(data
, maxlength
/sizeof(efi_char16_t
)) * sizeof(efi_char16_t
);
179 get_var_data(struct efi_variable
*var
)
183 spin_lock(&efivars_lock
);
184 var
->DataSize
= 1024;
185 status
= efi
.get_variable(var
->VariableName
,
190 spin_unlock(&efivars_lock
);
191 if (status
!= EFI_SUCCESS
) {
192 printk(KERN_WARNING
"efivars: get_variable() failed 0x%lx!\n",
199 efivar_guid_read(struct efivar_entry
*entry
, char *buf
)
201 struct efi_variable
*var
= &entry
->var
;
207 efi_guid_unparse(&var
->VendorGuid
, str
);
209 str
+= sprintf(str
, "\n");
215 efivar_attr_read(struct efivar_entry
*entry
, char *buf
)
217 struct efi_variable
*var
= &entry
->var
;
224 status
= get_var_data(var
);
225 if (status
!= EFI_SUCCESS
)
228 if (var
->Attributes
& 0x1)
229 str
+= sprintf(str
, "EFI_VARIABLE_NON_VOLATILE\n");
230 if (var
->Attributes
& 0x2)
231 str
+= sprintf(str
, "EFI_VARIABLE_BOOTSERVICE_ACCESS\n");
232 if (var
->Attributes
& 0x4)
233 str
+= sprintf(str
, "EFI_VARIABLE_RUNTIME_ACCESS\n");
238 efivar_size_read(struct efivar_entry
*entry
, char *buf
)
240 struct efi_variable
*var
= &entry
->var
;
247 status
= get_var_data(var
);
248 if (status
!= EFI_SUCCESS
)
251 str
+= sprintf(str
, "0x%lx\n", var
->DataSize
);
256 efivar_data_read(struct efivar_entry
*entry
, char *buf
)
258 struct efi_variable
*var
= &entry
->var
;
264 status
= get_var_data(var
);
265 if (status
!= EFI_SUCCESS
)
268 memcpy(buf
, var
->Data
, var
->DataSize
);
269 return var
->DataSize
;
272 * We allow each variable to be edited via rewriting the
273 * entire efi variable structure.
276 efivar_store_raw(struct efivar_entry
*entry
, const char *buf
, size_t count
)
278 struct efi_variable
*new_var
, *var
= &entry
->var
;
279 efi_status_t status
= EFI_NOT_FOUND
;
281 if (count
!= sizeof(struct efi_variable
))
284 new_var
= (struct efi_variable
*)buf
;
286 * If only updating the variable data, then the name
287 * and guid should remain the same
289 if (memcmp(new_var
->VariableName
, var
->VariableName
, sizeof(var
->VariableName
)) ||
290 efi_guidcmp(new_var
->VendorGuid
, var
->VendorGuid
)) {
291 printk(KERN_ERR
"efivars: Cannot edit the wrong variable!\n");
295 if ((new_var
->DataSize
<= 0) || (new_var
->Attributes
== 0)){
296 printk(KERN_ERR
"efivars: DataSize & Attributes must be valid!\n");
300 spin_lock(&efivars_lock
);
301 status
= efi
.set_variable(new_var
->VariableName
,
302 &new_var
->VendorGuid
,
307 spin_unlock(&efivars_lock
);
309 if (status
!= EFI_SUCCESS
) {
310 printk(KERN_WARNING
"efivars: set_variable() failed: status=%lx\n",
315 memcpy(&entry
->var
, new_var
, count
);
320 efivar_show_raw(struct efivar_entry
*entry
, char *buf
)
322 struct efi_variable
*var
= &entry
->var
;
328 status
= get_var_data(var
);
329 if (status
!= EFI_SUCCESS
)
332 memcpy(buf
, var
, sizeof(*var
));
337 * Generic read/write functions that call the specific functions of
340 static ssize_t
efivar_attr_show(struct kobject
*kobj
, struct attribute
*attr
,
343 struct efivar_entry
*var
= to_efivar_entry(kobj
);
344 struct efivar_attribute
*efivar_attr
= to_efivar_attr(attr
);
347 if (!capable(CAP_SYS_ADMIN
))
350 if (efivar_attr
->show
) {
351 ret
= efivar_attr
->show(var
, buf
);
356 static ssize_t
efivar_attr_store(struct kobject
*kobj
, struct attribute
*attr
,
357 const char *buf
, size_t count
)
359 struct efivar_entry
*var
= to_efivar_entry(kobj
);
360 struct efivar_attribute
*efivar_attr
= to_efivar_attr(attr
);
363 if (!capable(CAP_SYS_ADMIN
))
366 if (efivar_attr
->store
)
367 ret
= efivar_attr
->store(var
, buf
, count
);
372 static struct sysfs_ops efivar_attr_ops
= {
373 .show
= efivar_attr_show
,
374 .store
= efivar_attr_store
,
377 static void efivar_release(struct kobject
*kobj
)
379 struct efivar_entry
*var
= container_of(kobj
, struct efivar_entry
, kobj
);
383 static EFIVAR_ATTR(guid
, 0400, efivar_guid_read
, NULL
);
384 static EFIVAR_ATTR(attributes
, 0400, efivar_attr_read
, NULL
);
385 static EFIVAR_ATTR(size
, 0400, efivar_size_read
, NULL
);
386 static EFIVAR_ATTR(data
, 0400, efivar_data_read
, NULL
);
387 static EFIVAR_ATTR(raw_var
, 0600, efivar_show_raw
, efivar_store_raw
);
389 static struct attribute
*def_attrs
[] = {
390 &efivar_attr_guid
.attr
,
391 &efivar_attr_size
.attr
,
392 &efivar_attr_attributes
.attr
,
393 &efivar_attr_data
.attr
,
394 &efivar_attr_raw_var
.attr
,
398 static struct kobj_type efivar_ktype
= {
399 .release
= efivar_release
,
400 .sysfs_ops
= &efivar_attr_ops
,
401 .default_attrs
= def_attrs
,
405 efivar_unregister(struct efivar_entry
*var
)
407 kobject_unregister(&var
->kobj
);
411 static ssize_t
efivar_create(struct kobject
*kobj
,
412 struct bin_attribute
*bin_attr
,
413 char *buf
, loff_t pos
, size_t count
)
415 struct efi_variable
*new_var
= (struct efi_variable
*)buf
;
416 struct efivar_entry
*search_efivar
, *n
;
417 unsigned long strsize1
, strsize2
;
418 efi_status_t status
= EFI_NOT_FOUND
;
421 if (!capable(CAP_SYS_ADMIN
))
424 spin_lock(&efivars_lock
);
427 * Does this variable already exist?
429 list_for_each_entry_safe(search_efivar
, n
, &efivar_list
, list
) {
430 strsize1
= utf8_strsize(search_efivar
->var
.VariableName
, 1024);
431 strsize2
= utf8_strsize(new_var
->VariableName
, 1024);
432 if (strsize1
== strsize2
&&
433 !memcmp(&(search_efivar
->var
.VariableName
),
434 new_var
->VariableName
, strsize1
) &&
435 !efi_guidcmp(search_efivar
->var
.VendorGuid
,
436 new_var
->VendorGuid
)) {
442 spin_unlock(&efivars_lock
);
446 /* now *really* create the variable via EFI */
447 status
= efi
.set_variable(new_var
->VariableName
,
448 &new_var
->VendorGuid
,
453 if (status
!= EFI_SUCCESS
) {
454 printk(KERN_WARNING
"efivars: set_variable() failed: status=%lx\n",
456 spin_unlock(&efivars_lock
);
459 spin_unlock(&efivars_lock
);
461 /* Create the entry in sysfs. Locking is not required here */
462 status
= efivar_create_sysfs_entry(utf8_strsize(new_var
->VariableName
,
463 1024), new_var
->VariableName
, &new_var
->VendorGuid
);
465 printk(KERN_WARNING
"efivars: variable created, but sysfs entry wasn't.\n");
470 static ssize_t
efivar_delete(struct kobject
*kobj
,
471 struct bin_attribute
*bin_attr
,
472 char *buf
, loff_t pos
, size_t count
)
474 struct efi_variable
*del_var
= (struct efi_variable
*)buf
;
475 struct efivar_entry
*search_efivar
, *n
;
476 unsigned long strsize1
, strsize2
;
477 efi_status_t status
= EFI_NOT_FOUND
;
480 if (!capable(CAP_SYS_ADMIN
))
483 spin_lock(&efivars_lock
);
486 * Does this variable already exist?
488 list_for_each_entry_safe(search_efivar
, n
, &efivar_list
, list
) {
489 strsize1
= utf8_strsize(search_efivar
->var
.VariableName
, 1024);
490 strsize2
= utf8_strsize(del_var
->VariableName
, 1024);
491 if (strsize1
== strsize2
&&
492 !memcmp(&(search_efivar
->var
.VariableName
),
493 del_var
->VariableName
, strsize1
) &&
494 !efi_guidcmp(search_efivar
->var
.VendorGuid
,
495 del_var
->VendorGuid
)) {
501 spin_unlock(&efivars_lock
);
504 /* force the Attributes/DataSize to 0 to ensure deletion */
505 del_var
->Attributes
= 0;
506 del_var
->DataSize
= 0;
508 status
= efi
.set_variable(del_var
->VariableName
,
509 &del_var
->VendorGuid
,
514 if (status
!= EFI_SUCCESS
) {
515 printk(KERN_WARNING
"efivars: set_variable() failed: status=%lx\n",
517 spin_unlock(&efivars_lock
);
520 list_del(&search_efivar
->list
);
521 /* We need to release this lock before unregistering. */
522 spin_unlock(&efivars_lock
);
523 efivar_unregister(search_efivar
);
525 /* It's dead Jim.... */
529 static struct bin_attribute var_subsys_attr_new_var
= {
530 .attr
= {.name
= "new_var", .mode
= 0200},
531 .write
= efivar_create
,
534 static struct bin_attribute var_subsys_attr_del_var
= {
535 .attr
= {.name
= "del_var", .mode
= 0200},
536 .write
= efivar_delete
,
540 * Let's not leave out systab information that snuck into
544 systab_read(struct kset
*kset
, char *buf
)
551 if (efi
.mps
!= EFI_INVALID_TABLE_ADDR
)
552 str
+= sprintf(str
, "MPS=0x%lx\n", efi
.mps
);
553 if (efi
.acpi20
!= EFI_INVALID_TABLE_ADDR
)
554 str
+= sprintf(str
, "ACPI20=0x%lx\n", efi
.acpi20
);
555 if (efi
.acpi
!= EFI_INVALID_TABLE_ADDR
)
556 str
+= sprintf(str
, "ACPI=0x%lx\n", efi
.acpi
);
557 if (efi
.smbios
!= EFI_INVALID_TABLE_ADDR
)
558 str
+= sprintf(str
, "SMBIOS=0x%lx\n", efi
.smbios
);
559 if (efi
.hcdp
!= EFI_INVALID_TABLE_ADDR
)
560 str
+= sprintf(str
, "HCDP=0x%lx\n", efi
.hcdp
);
561 if (efi
.boot_info
!= EFI_INVALID_TABLE_ADDR
)
562 str
+= sprintf(str
, "BOOTINFO=0x%lx\n", efi
.boot_info
);
563 if (efi
.uga
!= EFI_INVALID_TABLE_ADDR
)
564 str
+= sprintf(str
, "UGA=0x%lx\n", efi
.uga
);
569 static EFI_ATTR(systab
, 0400, systab_read
, NULL
);
571 static struct subsys_attribute
*efi_subsys_attrs
[] = {
573 NULL
, /* maybe more in the future? */
576 static decl_subsys(vars
, NULL
);
577 static decl_subsys(efi
, NULL
);
580 * efivar_create_sysfs_entry()
582 * variable_name_size = number of bytes required to hold
583 * variable_name (not counting the NULL
584 * character at the end.
585 * efivars_lock is not held on entry or exit.
586 * Returns 1 on failure, 0 on success
589 efivar_create_sysfs_entry(unsigned long variable_name_size
,
590 efi_char16_t
*variable_name
,
591 efi_guid_t
*vendor_guid
)
593 int i
, short_name_size
= variable_name_size
/ sizeof(efi_char16_t
) + 38;
595 struct efivar_entry
*new_efivar
;
597 short_name
= kzalloc(short_name_size
+ 1, GFP_KERNEL
);
598 new_efivar
= kzalloc(sizeof(struct efivar_entry
), GFP_KERNEL
);
600 if (!short_name
|| !new_efivar
) {
606 memcpy(new_efivar
->var
.VariableName
, variable_name
,
608 memcpy(&(new_efivar
->var
.VendorGuid
), vendor_guid
, sizeof(efi_guid_t
));
610 /* Convert Unicode to normal chars (assume top bits are 0),
612 for (i
=0; i
< (int)(variable_name_size
/ sizeof(efi_char16_t
)); i
++) {
613 short_name
[i
] = variable_name
[i
] & 0xFF;
615 /* This is ugly, but necessary to separate one vendor's
616 private variables from another's. */
618 *(short_name
+ strlen(short_name
)) = '-';
619 efi_guid_unparse(vendor_guid
, short_name
+ strlen(short_name
));
621 kobject_set_name(&new_efivar
->kobj
, "%s", short_name
);
622 new_efivar
->kobj
.kset
= &vars_subsys
;
623 new_efivar
->kobj
.ktype
= &efivar_ktype
;
624 i
= kobject_register(&new_efivar
->kobj
);
634 spin_lock(&efivars_lock
);
635 list_add(&new_efivar
->list
, &efivar_list
);
636 spin_unlock(&efivars_lock
);
641 * For now we register the efi subsystem with the firmware subsystem
642 * and the vars subsystem with the efi subsystem. In the future, it
643 * might make sense to split off the efi subsystem into its own
644 * driver, but for now only efivars will register with it, so just
651 efi_status_t status
= EFI_NOT_FOUND
;
652 efi_guid_t vendor_guid
;
653 efi_char16_t
*variable_name
;
654 struct subsys_attribute
*attr
;
655 unsigned long variable_name_size
= 1024;
661 variable_name
= kzalloc(variable_name_size
, GFP_KERNEL
);
662 if (!variable_name
) {
663 printk(KERN_ERR
"efivars: Memory allocation failed.\n");
667 printk(KERN_INFO
"EFI Variables Facility v%s %s\n", EFIVARS_VERSION
,
671 * For now we'll register the efi subsys within this driver
674 error
= firmware_register(&efi_subsys
);
677 printk(KERN_ERR
"efivars: Firmware registration failed with error %d.\n", error
);
681 vars_subsys
.kobj
.kset
= &efi_subsys
;
683 error
= subsystem_register(&vars_subsys
);
686 printk(KERN_ERR
"efivars: Subsystem registration failed with error %d.\n", error
);
687 goto out_firmware_unregister
;
691 * Per EFI spec, the maximum storage allocated for both
692 * the variable name and variable data is 1024 bytes.
696 variable_name_size
= 1024;
698 status
= efi
.get_next_variable(&variable_name_size
,
703 efivar_create_sysfs_entry(variable_name_size
,
710 printk(KERN_WARNING
"efivars: get_next_variable: status=%lx\n",
712 status
= EFI_NOT_FOUND
;
715 } while (status
!= EFI_NOT_FOUND
);
718 * Now add attributes to allow creation of new vars
719 * and deletion of existing ones...
721 error
= sysfs_create_bin_file(&vars_subsys
.kobj
,
722 &var_subsys_attr_new_var
);
724 printk(KERN_ERR
"efivars: unable to create new_var sysfs file"
725 " due to error %d\n", error
);
726 error
= sysfs_create_bin_file(&vars_subsys
.kobj
,
727 &var_subsys_attr_del_var
);
729 printk(KERN_ERR
"efivars: unable to create del_var sysfs file"
730 " due to error %d\n", error
);
732 /* Don't forget the systab entry */
734 for (i
= 0; (attr
= efi_subsys_attrs
[i
]) && !error
; i
++) {
736 error
= subsys_create_file(&efi_subsys
, attr
);
740 printk(KERN_ERR
"efivars: Sysfs attribute export failed with error %d.\n", error
);
744 subsystem_unregister(&vars_subsys
);
746 out_firmware_unregister
:
747 firmware_unregister(&efi_subsys
);
750 kfree(variable_name
);
758 struct efivar_entry
*entry
, *n
;
760 list_for_each_entry_safe(entry
, n
, &efivar_list
, list
) {
761 spin_lock(&efivars_lock
);
762 list_del(&entry
->list
);
763 spin_unlock(&efivars_lock
);
764 efivar_unregister(entry
);
767 subsystem_unregister(&vars_subsys
);
768 firmware_unregister(&efi_subsys
);
771 module_init(efivars_init
);
772 module_exit(efivars_exit
);