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;
105 static struct efivars __efivars;
106 static struct efivars *efivars = &__efivars;
109 * The maximum size of VariableName + Data = 1024
110 * Therefore, it's reasonable to save that much
111 * space in each part of the structure,
112 * and we use a page for reading/writing.
115 struct efi_variable {
116 efi_char16_t VariableName[1024/sizeof(efi_char16_t)];
117 efi_guid_t VendorGuid;
118 unsigned long DataSize;
122 } __attribute__((packed));
125 struct efivar_entry {
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(unsigned long variable_name_size,
153 efi_char16_t *variable_name,
154 efi_guid_t *vendor_guid);
156 /* Return the number of unicode characters in data */
158 utf8_strlen(efi_char16_t *data, unsigned long maxlength)
160 unsigned long length = 0;
162 while (*data++ != 0 && length < maxlength)
168 * Return the number of bytes is the length of this string
169 * Note: this is NOT the same as the number of unicode characters
171 static inline unsigned long
172 utf8_strsize(efi_char16_t *data, unsigned long maxlength)
174 return utf8_strlen(data, maxlength/sizeof(efi_char16_t)) * sizeof(efi_char16_t);
178 get_var_data(struct efi_variable *var)
182 spin_lock(&efivars->lock);
183 var->DataSize = 1024;
184 status = efi.get_variable(var->VariableName,
189 spin_unlock(&efivars->lock);
190 if (status != EFI_SUCCESS) {
191 printk(KERN_WARNING "efivars: get_variable() failed 0x%lx!\n",
198 efivar_guid_read(struct efivar_entry *entry, char *buf)
200 struct efi_variable *var = &entry->var;
206 efi_guid_unparse(&var->VendorGuid, str);
208 str += sprintf(str, "\n");
214 efivar_attr_read(struct efivar_entry *entry, char *buf)
216 struct efi_variable *var = &entry->var;
223 status = get_var_data(var);
224 if (status != EFI_SUCCESS)
227 if (var->Attributes & 0x1)
228 str += sprintf(str, "EFI_VARIABLE_NON_VOLATILE\n");
229 if (var->Attributes & 0x2)
230 str += sprintf(str, "EFI_VARIABLE_BOOTSERVICE_ACCESS\n");
231 if (var->Attributes & 0x4)
232 str += sprintf(str, "EFI_VARIABLE_RUNTIME_ACCESS\n");
237 efivar_size_read(struct efivar_entry *entry, char *buf)
239 struct efi_variable *var = &entry->var;
246 status = get_var_data(var);
247 if (status != EFI_SUCCESS)
250 str += sprintf(str, "0x%lx\n", var->DataSize);
255 efivar_data_read(struct efivar_entry *entry, char *buf)
257 struct efi_variable *var = &entry->var;
263 status = get_var_data(var);
264 if (status != EFI_SUCCESS)
267 memcpy(buf, var->Data, var->DataSize);
268 return var->DataSize;
271 * We allow each variable to be edited via rewriting the
272 * entire efi variable structure.
275 efivar_store_raw(struct efivar_entry *entry, const char *buf, size_t count)
277 struct efi_variable *new_var, *var = &entry->var;
278 efi_status_t status = EFI_NOT_FOUND;
280 if (count != sizeof(struct efi_variable))
283 new_var = (struct efi_variable *)buf;
285 * If only updating the variable data, then the name
286 * and guid should remain the same
288 if (memcmp(new_var->VariableName, var->VariableName, sizeof(var->VariableName)) ||
289 efi_guidcmp(new_var->VendorGuid, var->VendorGuid)) {
290 printk(KERN_ERR "efivars: Cannot edit the wrong variable!\n");
294 if ((new_var->DataSize <= 0) || (new_var->Attributes == 0)){
295 printk(KERN_ERR "efivars: DataSize & Attributes must be valid!\n");
299 spin_lock(&efivars->lock);
300 status = efi.set_variable(new_var->VariableName,
301 &new_var->VendorGuid,
306 spin_unlock(&efivars->lock);
308 if (status != EFI_SUCCESS) {
309 printk(KERN_WARNING "efivars: set_variable() failed: status=%lx\n",
314 memcpy(&entry->var, new_var, count);
319 efivar_show_raw(struct efivar_entry *entry, char *buf)
321 struct efi_variable *var = &entry->var;
327 status = get_var_data(var);
328 if (status != EFI_SUCCESS)
331 memcpy(buf, var, sizeof(*var));
336 * Generic read/write functions that call the specific functions of
339 static ssize_t efivar_attr_show(struct kobject *kobj, struct attribute *attr,
342 struct efivar_entry *var = to_efivar_entry(kobj);
343 struct efivar_attribute *efivar_attr = to_efivar_attr(attr);
346 if (!capable(CAP_SYS_ADMIN))
349 if (efivar_attr->show) {
350 ret = efivar_attr->show(var, buf);
355 static ssize_t efivar_attr_store(struct kobject *kobj, struct attribute *attr,
356 const char *buf, size_t count)
358 struct efivar_entry *var = to_efivar_entry(kobj);
359 struct efivar_attribute *efivar_attr = to_efivar_attr(attr);
362 if (!capable(CAP_SYS_ADMIN))
365 if (efivar_attr->store)
366 ret = efivar_attr->store(var, buf, count);
371 static const struct sysfs_ops efivar_attr_ops = {
372 .show = efivar_attr_show,
373 .store = efivar_attr_store,
376 static void efivar_release(struct kobject *kobj)
378 struct efivar_entry *var = container_of(kobj, struct efivar_entry, kobj);
382 static EFIVAR_ATTR(guid, 0400, efivar_guid_read, NULL);
383 static EFIVAR_ATTR(attributes, 0400, efivar_attr_read, NULL);
384 static EFIVAR_ATTR(size, 0400, efivar_size_read, NULL);
385 static EFIVAR_ATTR(data, 0400, efivar_data_read, NULL);
386 static EFIVAR_ATTR(raw_var, 0600, efivar_show_raw, efivar_store_raw);
388 static struct attribute *def_attrs[] = {
389 &efivar_attr_guid.attr,
390 &efivar_attr_size.attr,
391 &efivar_attr_attributes.attr,
392 &efivar_attr_data.attr,
393 &efivar_attr_raw_var.attr,
397 static struct kobj_type efivar_ktype = {
398 .release = efivar_release,
399 .sysfs_ops = &efivar_attr_ops,
400 .default_attrs = def_attrs,
404 efivar_unregister(struct efivar_entry *var)
406 kobject_put(&var->kobj);
410 static ssize_t efivar_create(struct file *filp, struct kobject *kobj,
411 struct bin_attribute *bin_attr,
412 char *buf, loff_t pos, size_t count)
414 struct efi_variable *new_var = (struct efi_variable *)buf;
415 struct efivar_entry *search_efivar, *n;
416 unsigned long strsize1, strsize2;
417 efi_status_t status = EFI_NOT_FOUND;
420 if (!capable(CAP_SYS_ADMIN))
423 spin_lock(&efivars->lock);
426 * Does this variable already exist?
428 list_for_each_entry_safe(search_efivar, n, &efivars->list, list) {
429 strsize1 = utf8_strsize(search_efivar->var.VariableName, 1024);
430 strsize2 = utf8_strsize(new_var->VariableName, 1024);
431 if (strsize1 == strsize2 &&
432 !memcmp(&(search_efivar->var.VariableName),
433 new_var->VariableName, strsize1) &&
434 !efi_guidcmp(search_efivar->var.VendorGuid,
435 new_var->VendorGuid)) {
441 spin_unlock(&efivars->lock);
445 /* now *really* create the variable via EFI */
446 status = efi.set_variable(new_var->VariableName,
447 &new_var->VendorGuid,
452 if (status != EFI_SUCCESS) {
453 printk(KERN_WARNING "efivars: set_variable() failed: status=%lx\n",
455 spin_unlock(&efivars->lock);
458 spin_unlock(&efivars->lock);
460 /* Create the entry in sysfs. Locking is not required here */
461 status = efivar_create_sysfs_entry(utf8_strsize(new_var->VariableName,
462 1024), new_var->VariableName, &new_var->VendorGuid);
464 printk(KERN_WARNING "efivars: variable created, but sysfs entry wasn't.\n");
469 static ssize_t efivar_delete(struct file *filp, struct kobject *kobj,
470 struct bin_attribute *bin_attr,
471 char *buf, loff_t pos, size_t count)
473 struct efi_variable *del_var = (struct efi_variable *)buf;
474 struct efivar_entry *search_efivar, *n;
475 unsigned long strsize1, strsize2;
476 efi_status_t status = EFI_NOT_FOUND;
479 if (!capable(CAP_SYS_ADMIN))
482 spin_lock(&efivars->lock);
485 * Does this variable already exist?
487 list_for_each_entry_safe(search_efivar, n, &efivars->list, list) {
488 strsize1 = utf8_strsize(search_efivar->var.VariableName, 1024);
489 strsize2 = utf8_strsize(del_var->VariableName, 1024);
490 if (strsize1 == strsize2 &&
491 !memcmp(&(search_efivar->var.VariableName),
492 del_var->VariableName, strsize1) &&
493 !efi_guidcmp(search_efivar->var.VendorGuid,
494 del_var->VendorGuid)) {
500 spin_unlock(&efivars->lock);
503 /* force the Attributes/DataSize to 0 to ensure deletion */
504 del_var->Attributes = 0;
505 del_var->DataSize = 0;
507 status = efi.set_variable(del_var->VariableName,
508 &del_var->VendorGuid,
513 if (status != EFI_SUCCESS) {
514 printk(KERN_WARNING "efivars: set_variable() failed: status=%lx\n",
516 spin_unlock(&efivars->lock);
519 list_del(&search_efivar->list);
520 /* We need to release this lock before unregistering. */
521 spin_unlock(&efivars->lock);
522 efivar_unregister(search_efivar);
524 /* It's dead Jim.... */
528 static struct bin_attribute var_subsys_attr_new_var = {
529 .attr = {.name = "new_var", .mode = 0200},
530 .write = efivar_create,
533 static struct bin_attribute var_subsys_attr_del_var = {
534 .attr = {.name = "del_var", .mode = 0200},
535 .write = efivar_delete,
539 * Let's not leave out systab information that snuck into
542 static ssize_t systab_show(struct kobject *kobj,
543 struct kobj_attribute *attr, char *buf)
550 if (efi.mps != EFI_INVALID_TABLE_ADDR)
551 str += sprintf(str, "MPS=0x%lx\n", efi.mps);
552 if (efi.acpi20 != EFI_INVALID_TABLE_ADDR)
553 str += sprintf(str, "ACPI20=0x%lx\n", efi.acpi20);
554 if (efi.acpi != EFI_INVALID_TABLE_ADDR)
555 str += sprintf(str, "ACPI=0x%lx\n", efi.acpi);
556 if (efi.smbios != EFI_INVALID_TABLE_ADDR)
557 str += sprintf(str, "SMBIOS=0x%lx\n", efi.smbios);
558 if (efi.hcdp != EFI_INVALID_TABLE_ADDR)
559 str += sprintf(str, "HCDP=0x%lx\n", efi.hcdp);
560 if (efi.boot_info != EFI_INVALID_TABLE_ADDR)
561 str += sprintf(str, "BOOTINFO=0x%lx\n", efi.boot_info);
562 if (efi.uga != EFI_INVALID_TABLE_ADDR)
563 str += sprintf(str, "UGA=0x%lx\n", efi.uga);
568 static struct kobj_attribute efi_attr_systab =
569 __ATTR(systab, 0400, systab_show, NULL);
571 static struct attribute *efi_subsys_attrs[] = {
572 &efi_attr_systab.attr,
573 NULL, /* maybe more in the future? */
576 static struct attribute_group efi_subsys_attr_group = {
577 .attrs = efi_subsys_attrs,
580 static struct kobject *efi_kobj;
583 * efivar_create_sysfs_entry()
585 * variable_name_size = number of bytes required to hold
586 * variable_name (not counting the NULL
587 * character at the end.
588 * efivars->lock is not held on entry or exit.
589 * Returns 1 on failure, 0 on success
592 efivar_create_sysfs_entry(unsigned long variable_name_size,
593 efi_char16_t *variable_name,
594 efi_guid_t *vendor_guid)
596 int i, short_name_size = variable_name_size / sizeof(efi_char16_t) + 38;
598 struct efivar_entry *new_efivar;
600 short_name = kzalloc(short_name_size + 1, GFP_KERNEL);
601 new_efivar = kzalloc(sizeof(struct efivar_entry), GFP_KERNEL);
603 if (!short_name || !new_efivar) {
609 memcpy(new_efivar->var.VariableName, variable_name,
611 memcpy(&(new_efivar->var.VendorGuid), vendor_guid, sizeof(efi_guid_t));
613 /* Convert Unicode to normal chars (assume top bits are 0),
615 for (i=0; i < (int)(variable_name_size / sizeof(efi_char16_t)); i++) {
616 short_name[i] = variable_name[i] & 0xFF;
618 /* This is ugly, but necessary to separate one vendor's
619 private variables from another's. */
621 *(short_name + strlen(short_name)) = '-';
622 efi_guid_unparse(vendor_guid, short_name + strlen(short_name));
624 new_efivar->kobj.kset = efivars->kset;
625 i = kobject_init_and_add(&new_efivar->kobj, &efivar_ktype, NULL,
633 kobject_uevent(&new_efivar->kobj, KOBJ_ADD);
637 spin_lock(&efivars->lock);
638 list_add(&new_efivar->list, &efivars->list);
639 spin_unlock(&efivars->lock);
644 * For now we register the efi subsystem with the firmware subsystem
645 * and the vars subsystem with the efi subsystem. In the future, it
646 * might make sense to split off the efi subsystem into its own
647 * driver, but for now only efivars will register with it, so just
654 efi_status_t status = EFI_NOT_FOUND;
655 efi_guid_t vendor_guid;
656 efi_char16_t *variable_name;
657 unsigned long variable_name_size = 1024;
663 variable_name = kzalloc(variable_name_size, GFP_KERNEL);
664 if (!variable_name) {
665 printk(KERN_ERR "efivars: Memory allocation failed.\n");
669 printk(KERN_INFO "EFI Variables Facility v%s %s\n", EFIVARS_VERSION,
672 /* For now we'll register the efi directory at /sys/firmware/efi */
673 efi_kobj = kobject_create_and_add("efi", firmware_kobj);
675 printk(KERN_ERR "efivars: Firmware registration failed.\n");
680 spin_lock_init(&efivars->lock);
681 INIT_LIST_HEAD(&efivars->list);
683 efivars->kset = kset_create_and_add("vars", NULL, efi_kobj);
684 if (!efivars->kset) {
685 printk(KERN_ERR "efivars: Subsystem registration failed.\n");
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(&efivars->kset->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(&efivars->kset->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 */
733 error = sysfs_create_group(efi_kobj, &efi_subsys_attr_group);
735 printk(KERN_ERR "efivars: Sysfs attribute export failed with error %d.\n", error);
739 kset_unregister(efivars->kset);
741 out_firmware_unregister:
742 kobject_put(efi_kobj);
745 kfree(variable_name);
753 struct efivar_entry *entry, *n;
755 list_for_each_entry_safe(entry, n, &efivars->list, list) {
756 spin_lock(&efivars->lock);
757 list_del(&entry->list);
758 spin_unlock(&efivars->lock);
759 efivar_unregister(entry);
762 kset_unregister(efivars->kset);
763 kobject_put(efi_kobj);
766 module_init(efivars_init);
767 module_exit(efivars_exit);