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>
80 #include <linux/slab.h>
82 #include <asm/uaccess.h>
84 #define EFIVARS_VERSION "0.08"
85 #define EFIVARS_DATE "2004-May-17"
87 MODULE_AUTHOR("Matt Domsch <Matt_Domsch@Dell.com>");
88 MODULE_DESCRIPTION("sysfs interface to EFI Variables");
89 MODULE_LICENSE("GPL");
90 MODULE_VERSION(EFIVARS_VERSION);
94 * ->lock protects two things:
95 * 1) ->list - adds, removals, reads, writes
96 * 2) efi.[gs]et_variable() calls.
97 * It must not be held when creating sysfs entries or calling kmalloc.
98 * efi.get_next_variable() is only called from efivars_init(),
99 * which is protected by the BKL, so that path is safe.
102 struct list_head list;
104 struct bin_attribute *new_var, *del_var;
108 * The maximum size of VariableName + Data = 1024
109 * Therefore, it's reasonable to save that much
110 * space in each part of the structure,
111 * and we use a page for reading/writing.
114 struct efi_variable {
115 efi_char16_t VariableName[1024/sizeof(efi_char16_t)];
116 efi_guid_t VendorGuid;
117 unsigned long DataSize;
121 } __attribute__((packed));
124 struct efivar_entry {
125 struct efivars *efivars;
126 struct efi_variable var;
127 struct list_head list;
131 struct efivar_attribute {
132 struct attribute attr;
133 ssize_t (*show) (struct efivar_entry *entry, char *buf);
134 ssize_t (*store)(struct efivar_entry *entry, const char *buf, size_t count);
138 #define EFIVAR_ATTR(_name, _mode, _show, _store) \
139 struct efivar_attribute efivar_attr_##_name = { \
140 .attr = {.name = __stringify(_name), .mode = _mode}, \
145 #define to_efivar_attr(_attr) container_of(_attr, struct efivar_attribute, attr)
146 #define to_efivar_entry(obj) container_of(obj, struct efivar_entry, kobj)
149 * Prototype for sysfs creation function
152 efivar_create_sysfs_entry(struct efivars *efivars,
153 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 efivars *efivars, 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(entry->efivars, 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(entry->efivars, 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(entry->efivars, 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 struct efivars *efivars = entry->efivars;
280 efi_status_t status = EFI_NOT_FOUND;
282 if (count != sizeof(struct efi_variable))
285 new_var = (struct efi_variable *)buf;
287 * If only updating the variable data, then the name
288 * and guid should remain the same
290 if (memcmp(new_var->VariableName, var->VariableName, sizeof(var->VariableName)) ||
291 efi_guidcmp(new_var->VendorGuid, var->VendorGuid)) {
292 printk(KERN_ERR "efivars: Cannot edit the wrong variable!\n");
296 if ((new_var->DataSize <= 0) || (new_var->Attributes == 0)){
297 printk(KERN_ERR "efivars: DataSize & Attributes must be valid!\n");
301 spin_lock(&efivars->lock);
302 status = efi.set_variable(new_var->VariableName,
303 &new_var->VendorGuid,
308 spin_unlock(&efivars->lock);
310 if (status != EFI_SUCCESS) {
311 printk(KERN_WARNING "efivars: set_variable() failed: status=%lx\n",
316 memcpy(&entry->var, new_var, count);
321 efivar_show_raw(struct efivar_entry *entry, char *buf)
323 struct efi_variable *var = &entry->var;
329 status = get_var_data(entry->efivars, var);
330 if (status != EFI_SUCCESS)
333 memcpy(buf, var, sizeof(*var));
338 * Generic read/write functions that call the specific functions of
341 static ssize_t efivar_attr_show(struct kobject *kobj, struct attribute *attr,
344 struct efivar_entry *var = to_efivar_entry(kobj);
345 struct efivar_attribute *efivar_attr = to_efivar_attr(attr);
348 if (!capable(CAP_SYS_ADMIN))
351 if (efivar_attr->show) {
352 ret = efivar_attr->show(var, buf);
357 static ssize_t efivar_attr_store(struct kobject *kobj, struct attribute *attr,
358 const char *buf, size_t count)
360 struct efivar_entry *var = to_efivar_entry(kobj);
361 struct efivar_attribute *efivar_attr = to_efivar_attr(attr);
364 if (!capable(CAP_SYS_ADMIN))
367 if (efivar_attr->store)
368 ret = efivar_attr->store(var, buf, count);
373 static const struct sysfs_ops efivar_attr_ops = {
374 .show = efivar_attr_show,
375 .store = efivar_attr_store,
378 static void efivar_release(struct kobject *kobj)
380 struct efivar_entry *var = container_of(kobj, struct efivar_entry, kobj);
384 static EFIVAR_ATTR(guid, 0400, efivar_guid_read, NULL);
385 static EFIVAR_ATTR(attributes, 0400, efivar_attr_read, NULL);
386 static EFIVAR_ATTR(size, 0400, efivar_size_read, NULL);
387 static EFIVAR_ATTR(data, 0400, efivar_data_read, NULL);
388 static EFIVAR_ATTR(raw_var, 0600, efivar_show_raw, efivar_store_raw);
390 static struct attribute *def_attrs[] = {
391 &efivar_attr_guid.attr,
392 &efivar_attr_size.attr,
393 &efivar_attr_attributes.attr,
394 &efivar_attr_data.attr,
395 &efivar_attr_raw_var.attr,
399 static struct kobj_type efivar_ktype = {
400 .release = efivar_release,
401 .sysfs_ops = &efivar_attr_ops,
402 .default_attrs = def_attrs,
406 efivar_unregister(struct efivar_entry *var)
408 kobject_put(&var->kobj);
412 static ssize_t efivar_create(struct file *filp, struct kobject *kobj,
413 struct bin_attribute *bin_attr,
414 char *buf, loff_t pos, size_t count)
416 struct efi_variable *new_var = (struct efi_variable *)buf;
417 struct efivars *efivars = bin_attr->private;
418 struct efivar_entry *search_efivar, *n;
419 unsigned long strsize1, strsize2;
420 efi_status_t status = EFI_NOT_FOUND;
423 if (!capable(CAP_SYS_ADMIN))
426 spin_lock(&efivars->lock);
429 * Does this variable already exist?
431 list_for_each_entry_safe(search_efivar, n, &efivars->list, list) {
432 strsize1 = utf8_strsize(search_efivar->var.VariableName, 1024);
433 strsize2 = utf8_strsize(new_var->VariableName, 1024);
434 if (strsize1 == strsize2 &&
435 !memcmp(&(search_efivar->var.VariableName),
436 new_var->VariableName, strsize1) &&
437 !efi_guidcmp(search_efivar->var.VendorGuid,
438 new_var->VendorGuid)) {
444 spin_unlock(&efivars->lock);
448 /* now *really* create the variable via EFI */
449 status = efi.set_variable(new_var->VariableName,
450 &new_var->VendorGuid,
455 if (status != EFI_SUCCESS) {
456 printk(KERN_WARNING "efivars: set_variable() failed: status=%lx\n",
458 spin_unlock(&efivars->lock);
461 spin_unlock(&efivars->lock);
463 /* Create the entry in sysfs. Locking is not required here */
464 status = efivar_create_sysfs_entry(efivars,
465 utf8_strsize(new_var->VariableName,
467 new_var->VariableName,
468 &new_var->VendorGuid);
470 printk(KERN_WARNING "efivars: variable created, but sysfs entry wasn't.\n");
475 static ssize_t efivar_delete(struct file *filp, struct kobject *kobj,
476 struct bin_attribute *bin_attr,
477 char *buf, loff_t pos, size_t count)
479 struct efi_variable *del_var = (struct efi_variable *)buf;
480 struct efivars *efivars = bin_attr->private;
481 struct efivar_entry *search_efivar, *n;
482 unsigned long strsize1, strsize2;
483 efi_status_t status = EFI_NOT_FOUND;
486 if (!capable(CAP_SYS_ADMIN))
489 spin_lock(&efivars->lock);
492 * Does this variable already exist?
494 list_for_each_entry_safe(search_efivar, n, &efivars->list, list) {
495 strsize1 = utf8_strsize(search_efivar->var.VariableName, 1024);
496 strsize2 = utf8_strsize(del_var->VariableName, 1024);
497 if (strsize1 == strsize2 &&
498 !memcmp(&(search_efivar->var.VariableName),
499 del_var->VariableName, strsize1) &&
500 !efi_guidcmp(search_efivar->var.VendorGuid,
501 del_var->VendorGuid)) {
507 spin_unlock(&efivars->lock);
510 /* force the Attributes/DataSize to 0 to ensure deletion */
511 del_var->Attributes = 0;
512 del_var->DataSize = 0;
514 status = efi.set_variable(del_var->VariableName,
515 &del_var->VendorGuid,
520 if (status != EFI_SUCCESS) {
521 printk(KERN_WARNING "efivars: set_variable() failed: status=%lx\n",
523 spin_unlock(&efivars->lock);
526 list_del(&search_efivar->list);
527 /* We need to release this lock before unregistering. */
528 spin_unlock(&efivars->lock);
529 efivar_unregister(search_efivar);
531 /* It's dead Jim.... */
536 * Let's not leave out systab information that snuck into
539 static ssize_t systab_show(struct kobject *kobj,
540 struct kobj_attribute *attr, char *buf)
547 if (efi.mps != EFI_INVALID_TABLE_ADDR)
548 str += sprintf(str, "MPS=0x%lx\n", efi.mps);
549 if (efi.acpi20 != EFI_INVALID_TABLE_ADDR)
550 str += sprintf(str, "ACPI20=0x%lx\n", efi.acpi20);
551 if (efi.acpi != EFI_INVALID_TABLE_ADDR)
552 str += sprintf(str, "ACPI=0x%lx\n", efi.acpi);
553 if (efi.smbios != EFI_INVALID_TABLE_ADDR)
554 str += sprintf(str, "SMBIOS=0x%lx\n", efi.smbios);
555 if (efi.hcdp != EFI_INVALID_TABLE_ADDR)
556 str += sprintf(str, "HCDP=0x%lx\n", efi.hcdp);
557 if (efi.boot_info != EFI_INVALID_TABLE_ADDR)
558 str += sprintf(str, "BOOTINFO=0x%lx\n", efi.boot_info);
559 if (efi.uga != EFI_INVALID_TABLE_ADDR)
560 str += sprintf(str, "UGA=0x%lx\n", efi.uga);
565 static struct kobj_attribute efi_attr_systab =
566 __ATTR(systab, 0400, systab_show, NULL);
568 static struct attribute *efi_subsys_attrs[] = {
569 &efi_attr_systab.attr,
570 NULL, /* maybe more in the future? */
573 static struct attribute_group efi_subsys_attr_group = {
574 .attrs = efi_subsys_attrs,
577 static struct kobject *efi_kobj;
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(struct efivars *efivars,
590 unsigned long variable_name_size,
591 efi_char16_t *variable_name,
592 efi_guid_t *vendor_guid)
594 int i, short_name_size = variable_name_size / sizeof(efi_char16_t) + 38;
596 struct efivar_entry *new_efivar;
598 short_name = kzalloc(short_name_size + 1, GFP_KERNEL);
599 new_efivar = kzalloc(sizeof(struct efivar_entry), GFP_KERNEL);
601 if (!short_name || !new_efivar) {
607 new_efivar->efivars = efivars;
608 memcpy(new_efivar->var.VariableName, variable_name,
610 memcpy(&(new_efivar->var.VendorGuid), vendor_guid, sizeof(efi_guid_t));
612 /* Convert Unicode to normal chars (assume top bits are 0),
614 for (i=0; i < (int)(variable_name_size / sizeof(efi_char16_t)); i++) {
615 short_name[i] = variable_name[i] & 0xFF;
617 /* This is ugly, but necessary to separate one vendor's
618 private variables from another's. */
620 *(short_name + strlen(short_name)) = '-';
621 efi_guid_unparse(vendor_guid, short_name + strlen(short_name));
623 new_efivar->kobj.kset = efivars->kset;
624 i = kobject_init_and_add(&new_efivar->kobj, &efivar_ktype, NULL,
632 kobject_uevent(&new_efivar->kobj, KOBJ_ADD);
636 spin_lock(&efivars->lock);
637 list_add(&new_efivar->list, &efivars->list);
638 spin_unlock(&efivars->lock);
644 create_efivars_bin_attributes(struct efivars *efivars)
646 struct bin_attribute *attr;
650 attr = kzalloc(sizeof(*attr), GFP_KERNEL);
654 attr->attr.name = "new_var";
655 attr->attr.mode = 0200;
656 attr->write = efivar_create;
657 attr->private = efivars;
658 efivars->new_var = attr;
661 attr = kzalloc(sizeof(*attr), GFP_KERNEL);
666 attr->attr.name = "del_var";
667 attr->attr.mode = 0200;
668 attr->write = efivar_delete;
669 attr->private = efivars;
670 efivars->del_var = attr;
672 sysfs_bin_attr_init(efivars->new_var);
673 sysfs_bin_attr_init(efivars->del_var);
676 error = sysfs_create_bin_file(&efivars->kset->kobj,
679 printk(KERN_ERR "efivars: unable to create new_var sysfs file"
680 " due to error %d\n", error);
683 error = sysfs_create_bin_file(&efivars->kset->kobj,
686 printk(KERN_ERR "efivars: unable to create del_var sysfs file"
687 " due to error %d\n", error);
688 sysfs_remove_bin_file(&efivars->kset->kobj,
695 kfree(efivars->new_var);
696 efivars->new_var = NULL;
697 kfree(efivars->new_var);
698 efivars->new_var = NULL;
702 static struct efivars __efivars;
705 * For now we register the efi subsystem with the firmware subsystem
706 * and the vars subsystem with the efi subsystem. In the future, it
707 * might make sense to split off the efi subsystem into its own
708 * driver, but for now only efivars will register with it, so just
715 efi_status_t status = EFI_NOT_FOUND;
716 efi_guid_t vendor_guid;
717 efi_char16_t *variable_name;
718 unsigned long variable_name_size = 1024;
719 struct efivars *efivars = &__efivars;
725 variable_name = kzalloc(variable_name_size, GFP_KERNEL);
726 if (!variable_name) {
727 printk(KERN_ERR "efivars: Memory allocation failed.\n");
731 printk(KERN_INFO "EFI Variables Facility v%s %s\n", EFIVARS_VERSION,
734 /* For now we'll register the efi directory at /sys/firmware/efi */
735 efi_kobj = kobject_create_and_add("efi", firmware_kobj);
737 printk(KERN_ERR "efivars: Firmware registration failed.\n");
742 spin_lock_init(&efivars->lock);
743 INIT_LIST_HEAD(&efivars->list);
745 efivars->kset = kset_create_and_add("vars", NULL, efi_kobj);
746 if (!efivars->kset) {
747 printk(KERN_ERR "efivars: Subsystem registration failed.\n");
749 goto out_firmware_unregister;
753 * Per EFI spec, the maximum storage allocated for both
754 * the variable name and variable data is 1024 bytes.
758 variable_name_size = 1024;
760 status = efi.get_next_variable(&variable_name_size,
765 efivar_create_sysfs_entry(efivars,
773 printk(KERN_WARNING "efivars: get_next_variable: status=%lx\n",
775 status = EFI_NOT_FOUND;
778 } while (status != EFI_NOT_FOUND);
780 error = create_efivars_bin_attributes(efivars);
782 /* Don't forget the systab entry */
783 error = sysfs_create_group(efi_kobj, &efi_subsys_attr_group);
785 printk(KERN_ERR "efivars: Sysfs attribute export failed with error %d.\n", error);
789 kset_unregister(efivars->kset);
791 out_firmware_unregister:
792 kobject_put(efi_kobj);
795 kfree(variable_name);
803 struct efivars *efivars = &__efivars;
804 struct efivar_entry *entry, *n;
806 list_for_each_entry_safe(entry, n, &efivars->list, list) {
807 spin_lock(&efivars->lock);
808 list_del(&entry->list);
809 spin_unlock(&efivars->lock);
810 efivar_unregister(entry);
812 if (efivars->new_var)
813 sysfs_remove_bin_file(&efivars->kset->kobj, efivars->new_var);
814 if (efivars->del_var)
815 sysfs_remove_bin_file(&efivars->kset->kobj, efivars->del_var);
816 kfree(efivars->new_var);
817 kfree(efivars->del_var);
818 kset_unregister(efivars->kset);
819 kobject_put(efi_kobj);
822 module_init(efivars_init);
823 module_exit(efivars_exit);