efivars.c

对于那些带有区码限制的DVD光驱

/*
 * EFI Variables - efivars.c
 *
 * Copyright (C) 2001,2003,2004 Dell <[e-mail]>
 * Copyright (C) 2004 Intel Corporation <[e-mail]>
 *
 * This code takes all variables accessible from EFI runtime and
 *  exports them via sysfs
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 * Changelog:
 *
 *  17 May 2004 - Matt Domsch <[e-mail]>
 *   remove check for efi_enabled in exit
 *   add MODULE_VERSION
 *
 *  26 Apr 2004 - Matt Domsch <[e-mail]>
 *   minor bug fixes
 *
 *  21 Apr 2004 - Matt Tolentino <[e-mail])
 *   converted driver to export variable information via sysfs
 *   and moved to drivers/firmware directory
 *   bumped revision number to v0.07 to reflect conversion & move
 *
 *  10 Dec 2002 - Matt Domsch <[e-mail]>
 *   fix locking per Peter Chubb's findings
 *
 *  25 Mar 2002 - Matt Domsch <[e-mail]>
 *   move uuid_unparse() to include/asm-ia64/efi.h:efi_guid_unparse()
 *
 *  12 Feb 2002 - Matt Domsch <[e-mail]>
 *   use list_for_each_safe when deleting vars.
 *   remove ifdef CONFIG_SMP around include <linux/smp.h>
 *   v0.04 release to [e-mail]
 *
 *  20 April 2001 - Matt Domsch <[e-mail]>
 *   Moved vars from /proc/efi to /proc/efi/vars, and made
 *   efi.c own the /proc/efi directory.
 *   v0.03 release to [e-mail]
 *
 *  26 March 2001 - Matt Domsch <[e-mail]>
 *   At the request of Stephane, moved ownership of /proc/efi
 *   to efi.c, and now efivars lives under /proc/efi/vars.
 *
 *  12 March 2001 - Matt Domsch <[e-mail]>
 *   Feedback received from Stephane Eranian incorporated.
 *   efivar_write() checks copy_from_user() return value.
 *   efivar_read/write() returns proper errno.
 *   v0.02 release to [e-mail]
 *
 *  26 February 2001 - Matt Domsch <[e-mail]>
 *   v0.01 release to [e-mail]
 */

#include <linux/config.h>
#include <linux/types.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/sched.h>		/* for capable() */
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/string.h>
#include <linux/smp.h>
#include <linux/efi.h>
#include <linux/sysfs.h>
#include <linux/kobject.h>
#include <linux/device.h>

#include <asm/uaccess.h>

#define EFIVARS_VERSION "0.08"
#define EFIVARS_DATE "2004-May-17"

MODULE_AUTHOR("Matt Domsch <[e-mail]>");
MODULE_DESCRIPTION("sysfs interface to EFI Variables");
MODULE_LICENSE("GPL");
MODULE_VERSION(EFIVARS_VERSION);

/*
 * efivars_lock protects two things:
 * 1) efivar_list - adds, removals, reads, writes
 * 2) efi.[gs]et_variable() calls.
 * It must not be held when creating sysfs entries or calling kmalloc.
 * efi.get_next_variable() is only called from efivars_init(),
 * which is protected by the BKL, so that path is safe.
 */
static DEFINE_SPINLOCK(efivars_lock);
static LIST_HEAD(efivar_list);

/*
 * The maximum size of VariableName + Data = 1024
 * Therefore, it's reasonable to save that much
 * space in each part of the structure,
 * and we use a page for reading/writing.
 */

struct efi_variable {
	efi_char16_t  VariableName[1024/sizeof(efi_char16_t)];
	efi_guid_t    VendorGuid;
	unsigned long DataSize;
	__u8          Data[1024];
	efi_status_t  Status;
	__u32         Attributes;
} __attribute__((packed));


struct efivar_entry {
	struct efi_variable var;
	struct list_head list;
	struct kobject kobj;
};

#define get_efivar_entry(n) list_entry(n, struct efivar_entry, list)

struct efivar_attribute {
	struct attribute attr;
	ssize_t (*show) (struct efivar_entry *entry, char *buf);
	ssize_t (*store)(struct efivar_entry *entry, const char *buf, size_t count);
};


#define EFI_ATTR(_name, _mode, _show, _store) \
struct subsys_attribute efi_attr_##_name = { \
	.attr = {.name = __stringify(_name), .mode = _mode, .owner = THIS_MODULE}, \
	.show = _show, \
	.store = _store, \
};

#define EFIVAR_ATTR(_name, _mode, _show, _store) \
struct efivar_attribute efivar_attr_##_name = { \
	.attr = {.name = __stringify(_name), .mode = _mode, .owner = THIS_MODULE}, \
	.show = _show, \
	.store = _store, \
};

#define VAR_SUBSYS_ATTR(_name, _mode, _show, _store) \
struct subsys_attribute var_subsys_attr_##_name = { \
	.attr = {.name = __stringify(_name), .mode = _mode, .owner = THIS_MODULE}, \
	.show = _show, \
	.store = _store, \
};

#define to_efivar_attr(_attr) container_of(_attr, struct efivar_attribute, attr)
#define to_efivar_entry(obj)  container_of(obj, struct efivar_entry, kobj)

/*
 * Prototype for sysfs creation function
 */
static int
efivar_create_sysfs_entry(unsigned long variable_name_size,
				efi_char16_t *variable_name,
				efi_guid_t *vendor_guid);

/* Return the number of unicode characters in data */
static unsigned long
utf8_strlen(efi_char16_t *data, unsigned long maxlength)
{
	unsigned long length = 0;

	while (*data++ != 0 && length < maxlength)
		length++;
	return length;
}

/*
 * Return the number of bytes is the length of this string
 * Note: this is NOT the same as the number of unicode characters
 */
static inline unsigned long
utf8_strsize(efi_char16_t *data, unsigned long maxlength)
{
	return utf8_strlen(data, maxlength/sizeof(efi_char16_t)) * sizeof(efi_char16_t);
}

static efi_status_t
get_var_data(struct efi_variable *var)
{
	efi_status_t status;

	spin_lock(&efivars_lock);
	var->DataSize = 1024;
	status = efi.get_variable(var->VariableName,
				&var->VendorGuid,
				&var->Attributes,
				&var->DataSize,
				var->Data);
	spin_unlock(&efivars_lock);
	if (status != EFI_SUCCESS) {
		printk(KERN_WARNING "efivars: get_variable() failed 0x%lx!\n",
			status);
	}
	return status;
}

static ssize_t
efivar_guid_read(struct efivar_entry *entry, char *buf)
{
	struct efi_variable *var = &entry->var;
	char *str = buf;

	if (!entry || !buf)
		return 0;

	efi_guid_unparse(&var->VendorGuid, str);
	str += strlen(str);
	str += sprintf(str, "\n");

	return str - buf;
}

static ssize_t
efivar_attr_read(struct efivar_entry *entry, char *buf)
{
	struct efi_variable *var = &entry->var;
	char *str = buf;
	efi_status_t status;

	if (!entry || !buf)
		return -EINVAL;

	status = get_var_data(var);
	if (status != EFI_SUCCESS)
		return -EIO;

	if (var->Attributes & 0x1)
		str += sprintf(str, "EFI_VARIABLE_NON_VOLATILE\n");
	if (var->Attributes & 0x2)
		str += sprintf(str, "EFI_VARIABLE_BOOTSERVICE_ACCESS\n");
	if (var->Attributes & 0x4)
		str += sprintf(str, "EFI_VARIABLE_RUNTIME_ACCESS\n");
	return str - buf;
}

static ssize_t
efivar_size_read(struct efivar_entry *entry, char *buf)
{
	struct efi_variable *var = &entry->var;
	char *str = buf;
	efi_status_t status;

	if (!entry || !buf)
		return -EINVAL;

	status = get_var_data(var);
	if (status != EFI_SUCCESS)
		return -EIO;

	str += sprintf(str, "0x%lx\n", var->DataSize);
	return str - buf;
}

static ssize_t
efivar_data_read(struct efivar_entry *entry, char *buf)
{
	struct efi_variable *var = &entry->var;
	efi_status_t status;

	if (!entry || !buf)
		return -EINVAL;

	status = get_var_data(var);
	if (status != EFI_SUCCESS)
		return -EIO;

	memcpy(buf, var->Data, var->DataSize);
	return var->DataSize;
}
/*
 * We allow each variable to be edited via rewriting the
 * entire efi variable structure.
 */
static ssize_t
efivar_store_raw(struct efivar_entry *entry, const char *buf, size_t count)
{
	struct efi_variable *new_var, *var = &entry->var;
	efi_status_t status = EFI_NOT_FOUND;

	if (count != sizeof(struct efi_variable))
		return -EINVAL;

	new_var = (struct efi_variable *)buf;
	/*
	 * If only updating the variable data, then the name
	 * and guid should remain the same
	 */
	if (memcmp(new_var->VariableName, var->VariableName, sizeof(var->VariableName)) ||
		efi_guidcmp(new_var->VendorGuid, var->VendorGuid)) {
		printk(KERN_ERR "efivars: Cannot edit the wrong variable!\n");
		return -EINVAL;
	}

	if ((new_var->DataSize <= 0) || (new_var->Attributes == 0)){
		printk(KERN_ERR "efivars: DataSize & Attributes must be valid!\n");
		return -EINVAL;
	}

	spin_lock(&efivars_lock);
	status = efi.set_variable(new_var->VariableName,
					&new_var->VendorGuid,
					new_var->Attributes,
					new_var->DataSize,
					new_var->Data);

	spin_unlock(&efivars_lock);

	if (status != EFI_SUCCESS) {
		printk(KERN_WARNING "efivars: set_variable() failed: status=%lx\n",
			status);
		return -EIO;
	}

	memcpy(&entry->var, new_var, count);
	return count;
}

static ssize_t
efivar_show_raw(struct efivar_entry *entry, char *buf)
{
	struct efi_variable *var = &entry->var;
	efi_status_t status;

	if (!entry || !buf)
		return 0;

	status = get_var_data(var);
	if (status != EFI_SUCCESS)
		return -EIO;

	memcpy(buf, var, sizeof(*var));
	return sizeof(*var);
}

/*
 * Generic read/write functions that call the specific functions of
 * the atttributes...
 */
static ssize_t efivar_attr_show(struct kobject *kobj, struct attribute *attr,
				char *buf)
{
	struct efivar_entry *var = to_efivar_entry(kobj);
	struct efivar_attribute *efivar_attr = to_efivar_attr(attr);
	ssize_t ret = -EIO;

	if (!capable(CAP_SYS_ADMIN))
		return -EACCES;

	if (efivar_attr->show) {
		ret = efivar_attr->show(var, buf);
	}
	return ret;
}

static ssize_t efivar_attr_store(struct kobject *kobj, struct attribute *attr,
				const char *buf, size_t count)
{
	struct efivar_entry *var = to_efivar_entry(kobj);
	struct efivar_attribute *efivar_attr = to_efivar_attr(attr);
	ssize_t ret = -EIO;

	if (!capable(CAP_SYS_ADMIN))
		return -EACCES;

	if (efivar_attr->store)
		ret = efivar_attr->store(var, buf, count);

	return ret;
}

static struct sysfs_ops efivar_attr_ops = {
	.show = efivar_attr_show,
	.store = efivar_attr_store,
};

static void efivar_release(struct kobject *kobj)
{
	struct efivar_entry *var = container_of(kobj, struct efivar_entry, kobj);
	spin_lock(&efivars_lock);