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1// SPDX-License-Identifier: GPL-2.02/*3 * efibc: control EFI bootloaders which obey LoaderEntryOneShot var4 * Copyright (c) 2013-2016, Intel Corporation.5 */6 7#define pr_fmt(fmt) "efibc: " fmt8 9#include <linux/efi.h>10#include <linux/module.h>11#include <linux/reboot.h>12#include <linux/slab.h>13#include <linux/ucs2_string.h>14 15#define MAX_DATA_LEN 51216 17static int efibc_set_variable(efi_char16_t *name, efi_char16_t *value,18 unsigned long len)19{20 efi_status_t status;21 22 status = efi.set_variable(name, &LINUX_EFI_LOADER_ENTRY_GUID,23 EFI_VARIABLE_NON_VOLATILE24 | EFI_VARIABLE_BOOTSERVICE_ACCESS25 | EFI_VARIABLE_RUNTIME_ACCESS,26 len * sizeof(efi_char16_t), value);27 28 if (status != EFI_SUCCESS) {29 pr_err("failed to set EFI variable: 0x%lx\n", status);30 return -EIO;31 }32 return 0;33}34 35static int efibc_reboot_notifier_call(struct notifier_block *notifier,36 unsigned long event, void *data)37{38 efi_char16_t *reason = event == SYS_RESTART ? L"reboot"39 : L"shutdown";40 const u8 *str = data;41 efi_char16_t *wdata;42 unsigned long l;43 int ret;44 45 ret = efibc_set_variable(L"LoaderEntryRebootReason", reason,46 ucs2_strlen(reason));47 if (ret || !data)48 return NOTIFY_DONE;49 50 wdata = kmalloc(MAX_DATA_LEN * sizeof(efi_char16_t), GFP_KERNEL);51 if (!wdata)52 return NOTIFY_DONE;53 54 for (l = 0; l < MAX_DATA_LEN - 1 && str[l] != '\0'; l++)55 wdata[l] = str[l];56 wdata[l] = L'\0';57 58 efibc_set_variable(L"LoaderEntryOneShot", wdata, l);59 60 kfree(wdata);61 return NOTIFY_DONE;62}63 64static struct notifier_block efibc_reboot_notifier = {65 .notifier_call = efibc_reboot_notifier_call,66};67 68static int __init efibc_init(void)69{70 int ret;71 72 if (!efi_rt_services_supported(EFI_RT_SUPPORTED_SET_VARIABLE))73 return -ENODEV;74 75 ret = register_reboot_notifier(&efibc_reboot_notifier);76 if (ret)77 pr_err("unable to register reboot notifier\n");78 79 return ret;80}81module_init(efibc_init);82 83static void __exit efibc_exit(void)84{85 unregister_reboot_notifier(&efibc_reboot_notifier);86}87module_exit(efibc_exit);88 89MODULE_AUTHOR("Jeremy Compostella <jeremy.compostella@intel.com>");90MODULE_AUTHOR("Matt Gumbel <matthew.k.gumbel@intel.com");91MODULE_DESCRIPTION("EFI Bootloader Control");92MODULE_LICENSE("GPL v2");93