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;
106 static struct efivars __efivars;
107 static struct efivars *efivars = &__efivars;
110 * The maximum size of VariableName + Data = 1024
111 * Therefore, it's reasonable to save that much
112 * space in each part of the structure,
113 * and we use a page for reading/writing.
116 struct efi_variable {
117 efi_char16_t VariableName[1024/sizeof(efi_char16_t)];
118 efi_guid_t VendorGuid;
119 unsigned long DataSize;
123 } __attribute__((packed));
126 struct efivar_entry {
127 struct efi_variable var;
128 struct list_head list;
132 struct efivar_attribute {
133 struct attribute attr;
134 ssize_t (*show) (struct efivar_entry *entry, char *buf);
135 ssize_t (*store)(struct efivar_entry *entry, const char *buf, size_t count);
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 const 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_put(&var->kobj);
411 static ssize_t efivar_create(struct file *filp, 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, &efivars->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 file *filp, 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, &efivars->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.... */
530 * Let's not leave out systab information that snuck into
533 static ssize_t systab_show(struct kobject *kobj,
534 struct kobj_attribute *attr, char *buf)
541 if (efi.mps != EFI_INVALID_TABLE_ADDR)
542 str += sprintf(str, "MPS=0x%lx\n", efi.mps);
543 if (efi.acpi20 != EFI_INVALID_TABLE_ADDR)
544 str += sprintf(str, "ACPI20=0x%lx\n", efi.acpi20);
545 if (efi.acpi != EFI_INVALID_TABLE_ADDR)
546 str += sprintf(str, "ACPI=0x%lx\n", efi.acpi);
547 if (efi.smbios != EFI_INVALID_TABLE_ADDR)
548 str += sprintf(str, "SMBIOS=0x%lx\n", efi.smbios);
549 if (efi.hcdp != EFI_INVALID_TABLE_ADDR)
550 str += sprintf(str, "HCDP=0x%lx\n", efi.hcdp);
551 if (efi.boot_info != EFI_INVALID_TABLE_ADDR)
552 str += sprintf(str, "BOOTINFO=0x%lx\n", efi.boot_info);
553 if (efi.uga != EFI_INVALID_TABLE_ADDR)
554 str += sprintf(str, "UGA=0x%lx\n", efi.uga);
559 static struct kobj_attribute efi_attr_systab =
560 __ATTR(systab, 0400, systab_show, NULL);
562 static struct attribute *efi_subsys_attrs[] = {
563 &efi_attr_systab.attr,
564 NULL, /* maybe more in the future? */
567 static struct attribute_group efi_subsys_attr_group = {
568 .attrs = efi_subsys_attrs,
571 static struct kobject *efi_kobj;
574 * efivar_create_sysfs_entry()
576 * variable_name_size = number of bytes required to hold
577 * variable_name (not counting the NULL
578 * character at the end.
579 * efivars->lock is not held on entry or exit.
580 * Returns 1 on failure, 0 on success
583 efivar_create_sysfs_entry(unsigned long variable_name_size,
584 efi_char16_t *variable_name,
585 efi_guid_t *vendor_guid)
587 int i, short_name_size = variable_name_size / sizeof(efi_char16_t) + 38;
589 struct efivar_entry *new_efivar;
591 short_name = kzalloc(short_name_size + 1, GFP_KERNEL);
592 new_efivar = kzalloc(sizeof(struct efivar_entry), GFP_KERNEL);
594 if (!short_name || !new_efivar) {
600 memcpy(new_efivar->var.VariableName, variable_name,
602 memcpy(&(new_efivar->var.VendorGuid), vendor_guid, sizeof(efi_guid_t));
604 /* Convert Unicode to normal chars (assume top bits are 0),
606 for (i=0; i < (int)(variable_name_size / sizeof(efi_char16_t)); i++) {
607 short_name[i] = variable_name[i] & 0xFF;
609 /* This is ugly, but necessary to separate one vendor's
610 private variables from another's. */
612 *(short_name + strlen(short_name)) = '-';
613 efi_guid_unparse(vendor_guid, short_name + strlen(short_name));
615 new_efivar->kobj.kset = efivars->kset;
616 i = kobject_init_and_add(&new_efivar->kobj, &efivar_ktype, NULL,
624 kobject_uevent(&new_efivar->kobj, KOBJ_ADD);
628 spin_lock(&efivars->lock);
629 list_add(&new_efivar->list, &efivars->list);
630 spin_unlock(&efivars->lock);
636 create_efivars_bin_attributes(struct efivars *efivars)
638 struct bin_attribute *attr;
642 attr = kzalloc(sizeof(*attr), GFP_KERNEL);
646 attr->attr.name = "new_var";
647 attr->attr.mode = 0200;
648 attr->write = efivar_create;
649 attr->private = efivars;
650 efivars->new_var = attr;
653 attr = kzalloc(sizeof(*attr), GFP_KERNEL);
658 attr->attr.name = "del_var";
659 attr->attr.mode = 0200;
660 attr->write = efivar_delete;
661 attr->private = efivars;
662 efivars->del_var = attr;
664 sysfs_bin_attr_init(efivars->new_var);
665 sysfs_bin_attr_init(efivars->del_var);
668 error = sysfs_create_bin_file(&efivars->kset->kobj,
671 printk(KERN_ERR "efivars: unable to create new_var sysfs file"
672 " due to error %d\n", error);
675 error = sysfs_create_bin_file(&efivars->kset->kobj,
678 printk(KERN_ERR "efivars: unable to create del_var sysfs file"
679 " due to error %d\n", error);
680 sysfs_remove_bin_file(&efivars->kset->kobj,
687 kfree(efivars->new_var);
688 efivars->new_var = NULL;
689 kfree(efivars->new_var);
690 efivars->new_var = NULL;
695 * For now we register the efi subsystem with the firmware subsystem
696 * and the vars subsystem with the efi subsystem. In the future, it
697 * might make sense to split off the efi subsystem into its own
698 * driver, but for now only efivars will register with it, so just
705 efi_status_t status = EFI_NOT_FOUND;
706 efi_guid_t vendor_guid;
707 efi_char16_t *variable_name;
708 unsigned long variable_name_size = 1024;
714 variable_name = kzalloc(variable_name_size, GFP_KERNEL);
715 if (!variable_name) {
716 printk(KERN_ERR "efivars: Memory allocation failed.\n");
720 printk(KERN_INFO "EFI Variables Facility v%s %s\n", EFIVARS_VERSION,
723 /* For now we'll register the efi directory at /sys/firmware/efi */
724 efi_kobj = kobject_create_and_add("efi", firmware_kobj);
726 printk(KERN_ERR "efivars: Firmware registration failed.\n");
731 spin_lock_init(&efivars->lock);
732 INIT_LIST_HEAD(&efivars->list);
734 efivars->kset = kset_create_and_add("vars", NULL, efi_kobj);
735 if (!efivars->kset) {
736 printk(KERN_ERR "efivars: Subsystem registration failed.\n");
738 goto out_firmware_unregister;
742 * Per EFI spec, the maximum storage allocated for both
743 * the variable name and variable data is 1024 bytes.
747 variable_name_size = 1024;
749 status = efi.get_next_variable(&variable_name_size,
754 efivar_create_sysfs_entry(variable_name_size,
761 printk(KERN_WARNING "efivars: get_next_variable: status=%lx\n",
763 status = EFI_NOT_FOUND;
766 } while (status != EFI_NOT_FOUND);
768 error = create_efivars_bin_attributes(efivars);
770 /* Don't forget the systab entry */
771 error = sysfs_create_group(efi_kobj, &efi_subsys_attr_group);
773 printk(KERN_ERR "efivars: Sysfs attribute export failed with error %d.\n", error);
777 kset_unregister(efivars->kset);
779 out_firmware_unregister:
780 kobject_put(efi_kobj);
783 kfree(variable_name);
791 struct efivar_entry *entry, *n;
793 list_for_each_entry_safe(entry, n, &efivars->list, list) {
794 spin_lock(&efivars->lock);
795 list_del(&entry->list);
796 spin_unlock(&efivars->lock);
797 efivar_unregister(entry);
799 if (efivars->new_var)
800 sysfs_remove_bin_file(&efivars->kset->kobj, efivars->new_var);
801 if (efivars->del_var)
802 sysfs_remove_bin_file(&efivars->kset->kobj, efivars->del_var);
803 kfree(efivars->new_var);
804 kfree(efivars->del_var);
805 kset_unregister(efivars->kset);
806 kobject_put(efi_kobj);
809 module_init(efivars_init);
810 module_exit(efivars_exit);