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/*

 * EFI Variables - efivars.c

 *

 * Copyright (C) 2001 Dell Computer Corporation <Matt_Domsch@dell.com>

 *

 * This code takes all variables accessible from EFI runtime and

 *  exports them via /proc

 *

 * Reads to /proc/efi/vars/varname return an efi_variable_t structure.

 * Writes to /proc/efi/vars/varname must be an efi_variable_t structure.

 * Writes with DataSize = 0 or Attributes = 0 deletes the variable.

 * Writes with a new value in VariableName+VendorGuid creates

 * a new variable.

 *

 *

 *  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:

 *

 *  10 Dec 2002 - Matt Domsch <Matt_Domsch@dell.com>

 *   fix locking per Peter Chubb's findings

 *

 *  25 Mar 2002 - Matt Domsch <Matt_Domsch@dell.com>

 *   move uuid_unparse() to include/asm-ia64/efi.h:efi_guid_unparse()

 *

 *  12 Feb 2002 - Matt Domsch <Matt_Domsch@dell.com>

 *   use list_for_each_safe when deleting vars.

 *   remove ifdef CONFIG_SMP around include <linux/smp.h>

 *   v0.04 release to linux-ia64@linuxia64.org

 *

 *  20 April 2001 - Matt Domsch <Matt_Domsch@dell.com>

 *   Moved vars from /proc/efi to /proc/efi/vars, and made

 *   efi.c own the /proc/efi directory.

 *   v0.03 release to linux-ia64@linuxia64.org

 *

 *  26 March 2001 - Matt Domsch <Matt_Domsch@dell.com>

 *   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 <Matt_Domsch@dell.com>

 *   Feedback received from Stephane Eranian incorporated.

 *   efivar_write() checks copy_from_user() return value.

 *   efivar_read/write() returns proper errno.

 *   v0.02 release to linux-ia64@linuxia64.org

 *

 *  26 February 2001 - Matt Domsch <Matt_Domsch@dell.com>

 *   v0.01 release to linux-ia64@linuxia64.org

 */

#include <linux/config.h>

#include <linux/types.h>

#include <linux/errno.h>

#include <linux/init.h>

#include <linux/proc_fs.h>

#include <linux/sched.h>                /* for capable() */

#include <linux/mm.h>

#include <linux/module.h>

#include <linux/smp.h>

#include <linux/efi.h>

#include <asm/uaccess.h>

MODULE_AUTHOR("Matt Domsch <Matt_Domsch@Dell.com>");

MODULE_DESCRIPTION("/proc interface to EFI Variables");

MODULE_LICENSE("GPL");

#define EFIVARS_VERSION "0.06 2002-Dec-10"

static int

efivar_read(char *page, char **start, off_t off,

            int count, int *eof, void *data);

static int

efivar_write(struct file *file, const char *buffer,

             unsigned long count, void *data);

/*

 * 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.

 */

typedef struct _efi_variable_t {

        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)) efi_variable_t;

typedef struct _efivar_entry_t {

        efi_variable_t          var;

        struct proc_dir_entry   *entry;

        struct list_head        list;

} efivar_entry_t;

/*

  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 proc 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 spinlock_t efivars_lock = SPIN_LOCK_UNLOCKED;

static LIST_HEAD(efivar_list);

static struct proc_dir_entry *efi_vars_dir;

#define efivar_entry(n) list_entry(n, efivar_entry_t, list)

/* 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 int

proc_calc_metrics(char *page, char **start, off_t off,

                  int count, int *eof, int len)

{

        if (len <= off+count) *eof = 1;

        *start = page + off;

        len -= off;

        if (len>count) len = count;

        if (len<0) len = 0;

        return len;

}

/*

 * efivar_create_proc_entry()

 * Requires:

 *    variable_name_size = number of bytes required to hold

 *                         variable_name (not counting the NULL

 *                         character at the end.

 *    efivars_lock is not held on entry or exit.

 * Returns 1 on failure, 0 on success

 */

static int

efivar_create_proc_entry(unsigned long variable_name_size,

                         efi_char16_t *variable_name,

                         efi_guid_t *vendor_guid)

{

        int i, short_name_size = variable_name_size / sizeof(efi_char16_t) + 38;

        char *short_name;

        efivar_entry_t *new_efivar;

        short_name = kmalloc(short_name_size+1, GFP_KERNEL);

        new_efivar = kmalloc(sizeof(efivar_entry_t), GFP_KERNEL);

        if (!short_name || !new_efivar)  {

                if (short_name)        kfree(short_name);

                if (new_efivar)        kfree(new_efivar);

                return 1;

        }

        memset(short_name, 0, short_name_size+1);

        memset(new_efivar, 0, sizeof(efivar_entry_t));

        memcpy(new_efivar->var.VariableName, variable_name,

               variable_name_size);

        memcpy(&(new_efivar->var.VendorGuid), vendor_guid, sizeof(efi_guid_t));

        /* Convert Unicode to normal chars (assume top bits are 0),

           ala UTF-8 */

        for (i=0; i< (int) (variable_name_size / sizeof(efi_char16_t)); i++) {

                short_name[i] = variable_name[i] & 0xFF;

        }

        /* This is ugly, but necessary to separate one vendor's

           private variables from another's.         */

        *(short_name + strlen(short_name)) = '-';

        efi_guid_unparse(vendor_guid, short_name + strlen(short_name));

        /* Create the entry in proc */

        new_efivar->entry = create_proc_entry(short_name, 0600, efi_vars_dir);

        kfree(short_name); short_name = NULL;

        if (!new_efivar->entry) return 1;

        new_efivar->entry->data = new_efivar;

        new_efivar->entry->read_proc = efivar_read;

        new_efivar->entry->write_proc = efivar_write;

        spin_lock(&efivars_lock);

        list_add(&new_efivar->list, &efivar_list);

        spin_unlock(&efivars_lock);

        return 0;

}

/***********************************************************

 * efivar_read()

 * Requires:

 * Modifies: page

 * Returns: number of bytes written, or -EINVAL on failure

 ***********************************************************/

static int

efivar_read(char *page, char **start, off_t off, int count, int *eof, void *data)

{

        int len = sizeof(efi_variable_t);

        efivar_entry_t *efi_var = data;

        efi_variable_t *var_data = (efi_variable_t *)page;

        if (!page || !data) return -EINVAL;

        spin_lock(&efivars_lock);

        MOD_INC_USE_COUNT;

        memcpy(var_data, &efi_var->var, len);

        var_data->DataSize = 1024;

        var_data->Status = efi.get_variable(var_data->VariableName,

                                            &var_data->VendorGuid,

                                            &var_data->Attributes,

                                            &var_data->DataSize,

                                            var_data->Data);

        MOD_DEC_USE_COUNT;

        spin_unlock(&efivars_lock);

        return proc_calc_metrics(page, start, off, count, eof, len);

}

/***********************************************************

 * efivar_write()

 * Requires: data is an efi_setvariable_t data type,

 *           properly filled in, possibly by a call

 *           first to efivar_read().

 *           Caller must have CAP_SYS_ADMIN

 * Modifies: NVRAM

 * Returns: var_data->DataSize on success, errno on failure

 *

 ***********************************************************/

static int

efivar_write(struct file *file, const char *buffer,

             unsigned long count, void *data)

{

        unsigned long strsize1, strsize2;

        int found=0;

        struct list_head *pos, *n;

        unsigned long size = sizeof(efi_variable_t);

        efi_status_t status;

        efivar_entry_t *efivar = data, *search_efivar = NULL;

        efi_variable_t *var_data;

        if (!data || count != size) {

                printk(KERN_WARNING "efivars: improper struct of size 0x%lx passed.\n", count);

                return -EINVAL;

        }

        if (!capable(CAP_SYS_ADMIN))

                return -EACCES;

        MOD_INC_USE_COUNT;

        var_data = kmalloc(size, GFP_KERNEL);

        if (!var_data) {

                MOD_DEC_USE_COUNT;

                return -ENOMEM;

        }

        if (copy_from_user(var_data, buffer, size)) {

                MOD_DEC_USE_COUNT;

                kfree(var_data);

                return -EFAULT;

        }

        spin_lock(&efivars_lock);

        /* Since the data ptr we've currently got is probably for

           a different variable find the right variable.

           This allows any properly formatted data structure to

           be written to any of the files in /proc/efi/vars and it will work.

        */

        list_for_each_safe(pos, n, &efivar_list) {

                search_efivar = efivar_entry(pos);

                strsize1 = utf8_strsize(search_efivar->var.VariableName, 1024);

                strsize2 = utf8_strsize(var_data->VariableName, 1024);

                if ( strsize1 == strsize2 &&

                     !memcmp(&(search_efivar->var.VariableName),

                             var_data->VariableName, strsize1) &&

                     !efi_guidcmp(search_efivar->var.VendorGuid,

                                  var_data->VendorGuid)) {

                        found = 1;

                        break;

                }

        }

        if (found) efivar = search_efivar;

        status = efi.set_variable(var_data->VariableName,

                                  &var_data->VendorGuid,

                                  var_data->Attributes,

                                  var_data->DataSize,

                                  var_data->Data);

        if (status != EFI_SUCCESS) {

                printk(KERN_WARNING "set_variable() failed: status=%lx\n", status);

                kfree(var_data);

                MOD_DEC_USE_COUNT;

                spin_unlock(&efivars_lock);

                return -EIO;

        }

        if (!var_data->DataSize || !var_data->Attributes) {

                /* We just deleted the NVRAM variable */

                remove_proc_entry(efivar->entry->name, efi_vars_dir);

                list_del(&efivar->list);

                kfree(efivar);

        }

        spin_unlock(&efivars_lock);

        /* If this is a new variable, set up the proc entry for it. */

        if (!found) {

                efivar_create_proc_entry(utf8_strsize(var_data->VariableName,

                                                      1024),

                                         var_data->VariableName,

                                         &var_data->VendorGuid);

        }

        kfree(var_data);

        MOD_DEC_USE_COUNT;

        return size;

}

/*

 * The EFI system table contains pointers to the SAL system table,

 * HCDP, ACPI, SMBIOS, etc, that may be useful to applications.

 */

static ssize_t

efi_systab_read(struct file *file, char *buffer, size_t count, loff_t *ppos)

{

        void *data;

        u8 *proc_buffer;

        ssize_t size, length;

        int ret;

        const int max_nr_entries = 7;   /* num ptrs to tables we could expose */

        const int max_line_len = 80;

        if (!efi.systab)

                return 0;

        proc_buffer = kmalloc(max_nr_entries * max_line_len, GFP_KERNEL);

        if (!proc_buffer)

                return -ENOMEM;

        length = 0;

        if (efi.mps)

                length += sprintf(proc_buffer + length, "MPS=0x%lx\n", __pa(efi.mps));

        if (efi.acpi20)

                length += sprintf(proc_buffer + length, "ACPI20=0x%lx\n", __pa(efi.acpi20));

        if (efi.acpi)

                length += sprintf(proc_buffer + length, "ACPI=0x%lx\n", __pa(efi.acpi));

        if (efi.smbios)

                length += sprintf(proc_buffer + length, "SMBIOS=0x%lx\n", __pa(efi.smbios));

        if (efi.sal_systab)

                length += sprintf(proc_buffer + length, "SAL=0x%lx\n", __pa(efi.sal_systab));

        if (efi.hcdp)

                length += sprintf(proc_buffer + length, "HCDP=0x%lx\n", __pa(efi.hcdp));

        if (efi.boot_info)

                length += sprintf(proc_buffer + length, "BOOTINFO=0x%lx\n", __pa(efi.boot_info));

        if (*ppos >= length) {

                ret = 0;

                goto out;

        }

        data = proc_buffer + file->f_pos;

        size = length - file->f_pos;

        if (size > count)

                size = count;

        if (copy_to_user(buffer, data, size)) {

                ret = -EFAULT;

                goto out;

        }

        *ppos += size;

        ret = size;

out:

        kfree(proc_buffer);

        return ret;

}

static struct proc_dir_entry *efi_systab_entry;

static struct file_operations efi_systab_fops = {

        .read = efi_systab_read,

};

static int __init

efivars_init(void)

{

        efi_status_t status;

        efi_guid_t vendor_guid;

        efi_char16_t *variable_name = kmalloc(1024, GFP_KERNEL);

        unsigned long variable_name_size = 1024;

        printk(KERN_INFO "EFI Variables Facility v%s\n", EFIVARS_VERSION);

        /* Since efi.c happens before procfs is available,

           we create the directory here if it doesn't

           already exist.  There's probably a better way

           to do this.

        */

        if (!efi_dir)

                efi_dir = proc_mkdir("efi", NULL);

        efi_systab_entry = create_proc_entry("systab", S_IRUSR | S_IRGRP, efi_dir);

        if (efi_systab_entry)

                efi_systab_entry->proc_fops = &efi_systab_fops;

        efi_vars_dir = proc_mkdir("vars", efi_dir);

        /* Per EFI spec, the maximum storage allocated for both

           the variable name and variable data is 1024 bytes.

        */

        memset(variable_name, 0, 1024);

        do {

                variable_name_size=1024;

                status = efi.get_next_variable(&variable_name_size,

                                               variable_name,

                                               &vendor_guid);

                switch (status) {

                case EFI_SUCCESS:

                        efivar_create_proc_entry(variable_name_size,

                                                 variable_name,

                                                 &vendor_guid);

                        break;

                case EFI_NOT_FOUND:

                        break;

                default:

                        printk(KERN_WARNING "get_next_variable: status=%lx\n", status);

                        status = EFI_NOT_FOUND;

                        break;

                }

        } while (status != EFI_NOT_FOUND);

        kfree(variable_name);

        return 0;

}

static void __exit

efivars_exit(void)

{

        struct list_head *pos, *n;

        efivar_entry_t *efivar;

        spin_lock(&efivars_lock);

        if (efi_systab_entry)

                remove_proc_entry(efi_systab_entry->name, efi_dir);

        list_for_each_safe(pos, n, &efivar_list) {

                efivar = efivar_entry(pos);

                remove_proc_entry(efivar->entry->name, efi_vars_dir);

                list_del(&efivar->list);

                kfree(efivar);

        }

        spin_unlock(&efivars_lock);

        remove_proc_entry(efi_vars_dir->name, efi_dir);

}

module_init(efivars_init);

module_exit(efivars_exit);

/*

 * Overrides for Emacs so that we follow Linus's tabbing style.

 * Emacs will notice this stuff at the end of the file and automatically

 * adjust the settings for this buffer only.  This must remain at the end

 * of the file.

 * ---------------------------------------------------------------------------

 * Local variables:

 * c-indent-level: 4

 * c-brace-imaginary-offset: 0

 * c-brace-offset: -4

 * c-argdecl-indent: 4

 * c-label-offset: -4

 * c-continued-statement-offset: 4

 * c-continued-brace-offset: 0

 * indent-tabs-mode: nil

 * tab-width: 8

 * End:

 */