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// SPDX-License-Identifier: GPL-2.0
/*
* efibc: control EFI bootloaders which obey LoaderEntryOneShot var
* Copyright (c) 2013-2016, Intel Corporation.
*/
#define pr_fmt(fmt) "efibc: " fmt
#include <linux/efi.h>
#include <linux/module.h>
#include <linux/reboot.h>
#include <linux/slab.h>
#include <linux/ucs2_string.h>
#define MAX_DATA_LEN 512
static int efibc_set_variable(efi_char16_t *name, efi_char16_t *value,
unsigned long len)
{
efi_status_t status;
status = efi.set_variable(name, &LINUX_EFI_LOADER_ENTRY_GUID,
EFI_VARIABLE_NON_VOLATILE
| EFI_VARIABLE_BOOTSERVICE_ACCESS
| EFI_VARIABLE_RUNTIME_ACCESS,
len * sizeof(efi_char16_t), value);
if (status != EFI_SUCCESS) {
pr_err("failed to set EFI variable: 0x%lx\n", status);
return -EIO;
}
return 0;
}
static int efibc_reboot_notifier_call(struct notifier_block *notifier,
unsigned long event, void *data)
{
efi_char16_t *reason = event == SYS_RESTART ? L"reboot"
: L"shutdown";
const u8 *str = data;
efi_char16_t *wdata;
unsigned long l;
int ret;
ret = efibc_set_variable(L"LoaderEntryRebootReason", reason,
ucs2_strlen(reason));
if (ret || !data)
return NOTIFY_DONE;
wdata = kmalloc(MAX_DATA_LEN * sizeof(efi_char16_t), GFP_KERNEL);
if (!wdata)
return NOTIFY_DONE;
for (l = 0; l < MAX_DATA_LEN - 1 && str[l] != '\0'; l++)
wdata[l] = str[l];
wdata[l] = L'\0';
efibc_set_variable(L"LoaderEntryOneShot", wdata, l);
kfree(wdata);
return NOTIFY_DONE;
}
static struct notifier_block efibc_reboot_notifier = {
.notifier_call = efibc_reboot_notifier_call,
};
static int __init efibc_init(void)
{
int ret;
if (!efi_rt_services_supported(EFI_RT_SUPPORTED_SET_VARIABLE))
return -ENODEV;
ret = register_reboot_notifier(&efibc_reboot_notifier);
if (ret)
pr_err("unable to register reboot notifier\n");
return ret;
}
module_init(efibc_init);
static void __exit efibc_exit(void)
{
unregister_reboot_notifier(&efibc_reboot_notifier);
}
module_exit(efibc_exit);
MODULE_AUTHOR("Jeremy Compostella <jeremy.compostella@intel.com>");
MODULE_AUTHOR("Matt Gumbel <matthew.k.gumbel@intel.com");
MODULE_DESCRIPTION("EFI Bootloader Control");
MODULE_LICENSE("GPL v2");
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