// SPDX-License-Identifier: GPL-2.0
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/*
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* efibc: control EFI bootloaders which obey LoaderEntryOneShot var
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* Copyright (c) 2013-2016, Intel Corporation.
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*/
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#define pr_fmt(fmt) "efibc: " fmt
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#include <linux/efi.h>
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#include <linux/module.h>
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#include <linux/reboot.h>
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#include <linux/slab.h>
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static void efibc_str_to_str16(const char *str, efi_char16_t *str16)
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{
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size_t i;
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for (i = 0; i < strlen(str); i++)
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str16[i] = str[i];
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str16[i] = '\0';
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}
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static int efibc_set_variable(const char *name, const char *value)
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{
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int ret;
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efi_guid_t guid = LINUX_EFI_LOADER_ENTRY_GUID;
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struct efivar_entry *entry;
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size_t size = (strlen(value) + 1) * sizeof(efi_char16_t);
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if (size > sizeof(entry->var.Data)) {
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pr_err("value is too large (%zu bytes) for '%s' EFI variable\n", size, name);
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return -EINVAL;
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}
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entry = kmalloc(sizeof(*entry), GFP_KERNEL);
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if (!entry) {
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pr_err("failed to allocate efivar entry for '%s' EFI variable\n", name);
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return -ENOMEM;
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}
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efibc_str_to_str16(name, entry->var.VariableName);
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efibc_str_to_str16(value, (efi_char16_t *)entry->var.Data);
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memcpy(&entry->var.VendorGuid, &guid, sizeof(guid));
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ret = efivar_entry_set_safe(entry->var.VariableName,
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entry->var.VendorGuid,
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EFI_VARIABLE_NON_VOLATILE
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| EFI_VARIABLE_BOOTSERVICE_ACCESS
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| EFI_VARIABLE_RUNTIME_ACCESS,
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false, size, entry->var.Data);
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if (ret)
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pr_err("failed to set %s EFI variable: 0x%x\n",
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name, ret);
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kfree(entry);
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return ret;
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}
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static int efibc_reboot_notifier_call(struct notifier_block *notifier,
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unsigned long event, void *data)
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{
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const char *reason = "shutdown";
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int ret;
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if (event == SYS_RESTART)
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reason = "reboot";
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ret = efibc_set_variable("LoaderEntryRebootReason", reason);
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if (ret || !data)
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return NOTIFY_DONE;
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efibc_set_variable("LoaderEntryOneShot", (char *)data);
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return NOTIFY_DONE;
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}
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static struct notifier_block efibc_reboot_notifier = {
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.notifier_call = efibc_reboot_notifier_call,
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};
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static int __init efibc_init(void)
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{
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int ret;
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if (!efivars_kobject() || !efivar_supports_writes())
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return -ENODEV;
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ret = register_reboot_notifier(&efibc_reboot_notifier);
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if (ret)
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pr_err("unable to register reboot notifier\n");
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return ret;
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}
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module_init(efibc_init);
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static void __exit efibc_exit(void)
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{
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unregister_reboot_notifier(&efibc_reboot_notifier);
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}
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module_exit(efibc_exit);
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MODULE_AUTHOR("Jeremy Compostella <jeremy.compostella@intel.com>");
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MODULE_AUTHOR("Matt Gumbel <matthew.k.gumbel@intel.com");
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MODULE_DESCRIPTION("EFI Bootloader Control");
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MODULE_LICENSE("GPL v2");
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