LXR linux/drivers/firmware/efi/efibc.c

   1/*
   2 * efibc: control EFI bootloaders which obey LoaderEntryOneShot var
   3 * Copyright (c) 2013-2016, Intel Corporation.
   4 *
   5 * This program is free software; you can redistribute it and/or modify it
   6 * under the terms and conditions of the GNU General Public License,
   7 * version 2, as published by the Free Software Foundation.
   8 *
   9 * This program is distributed in the hope it will be useful, but WITHOUT
  10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  12 * more details.
  13 */
  14
  15#define pr_fmt(fmt) "efibc: " fmt
  16
  17#include <linux/efi.h>
  18#include <linux/module.h>
  19#include <linux/reboot.h>
  20#include <linux/slab.h>
  21
  22static void efibc_str_to_str16(const char *str, efi_char16_t *str16)
  23{
  24        size_t i;
  25
  26        for (i = 0; i < strlen(str); i++)
  27                str16[i] = str[i];
  28
  29        str16[i] = '\0';
  30}
  31
  32static int efibc_set_variable(const char *name, const char *value)
  33{
  34        int ret;
  35        efi_guid_t guid = LINUX_EFI_LOADER_ENTRY_GUID;
  36        struct efivar_entry *entry;
  37        size_t size = (strlen(value) + 1) * sizeof(efi_char16_t);
  38
  39        if (size > sizeof(entry->var.Data)) {
  40                pr_err("value is too large (%zu bytes) for '%s' EFI variable\n", size, name);
  41                return -EINVAL;
  42        }
  43
  44        entry = kmalloc(sizeof(*entry), GFP_KERNEL);
  45        if (!entry) {
  46                pr_err("failed to allocate efivar entry for '%s' EFI variable\n", name);
  47                return -ENOMEM;
  48        }
  49
  50        efibc_str_to_str16(name, entry->var.VariableName);
  51        efibc_str_to_str16(value, (efi_char16_t *)entry->var.Data);
  52        memcpy(&entry->var.VendorGuid, &guid, sizeof(guid));
  53
  54        ret = efivar_entry_set(entry,
  55                               EFI_VARIABLE_NON_VOLATILE
  56                               | EFI_VARIABLE_BOOTSERVICE_ACCESS
  57                               | EFI_VARIABLE_RUNTIME_ACCESS,
  58                               size, entry->var.Data, NULL);
  59        if (ret)
  60                pr_err("failed to set %s EFI variable: 0x%x\n",
  61                       name, ret);
  62
  63        kfree(entry);
  64        return ret;
  65}
  66
  67static int efibc_reboot_notifier_call(struct notifier_block *notifier,
  68                                      unsigned long event, void *data)
  69{
  70        const char *reason = "shutdown";
  71        int ret;
  72
  73        if (event == SYS_RESTART)
  74                reason = "reboot";
  75
  76        ret = efibc_set_variable("LoaderEntryRebootReason", reason);
  77        if (ret || !data)
  78                return NOTIFY_DONE;
  79
  80        efibc_set_variable("LoaderEntryOneShot", (char *)data);
  81
  82        return NOTIFY_DONE;
  83}
  84
  85static struct notifier_block efibc_reboot_notifier = {
  86        .notifier_call = efibc_reboot_notifier_call,
  87};
  88
  89static int __init efibc_init(void)
  90{
  91        int ret;
  92
  93        if (!efi_enabled(EFI_RUNTIME_SERVICES))
  94                return -ENODEV;
  95
  96        ret = register_reboot_notifier(&efibc_reboot_notifier);
  97        if (ret)
  98                pr_err("unable to register reboot notifier\n");
  99
 100        return ret;
 101}
 102module_init(efibc_init);
 103
 104static void __exit efibc_exit(void)
 105{
 106        unregister_reboot_notifier(&efibc_reboot_notifier);
 107}
 108module_exit(efibc_exit);
 109
 110MODULE_AUTHOR("Jeremy Compostella <jeremy.compostella@intel.com>");
 111MODULE_AUTHOR("Matt Gumbel <matthew.k.gumbel@intel.com");
 112MODULE_DESCRIPTION("EFI Bootloader Control");
 113MODULE_LICENSE("GPL v2");
 114