1 | // SPDX-License-Identifier: GPL-2.0 |
2 | /* |
3 | * efibc: control EFI bootloaders which obey LoaderEntryOneShot var |
4 | * Copyright (c) 2013-2016, Intel Corporation. |
5 | */ |
6 | |
7 | #define pr_fmt(fmt) "efibc: " fmt |
8 | |
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 512 |
16 | |
17 | static 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_VOLATILE |
24 | | EFI_VARIABLE_BOOTSERVICE_ACCESS |
25 | | 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 | |
35 | static 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(name: L"LoaderEntryRebootReason" , value: reason, |
46 | len: ucs2_strlen(s: 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(name: L"LoaderEntryOneShot" , value: wdata, len: l); |
59 | |
60 | kfree(objp: wdata); |
61 | return NOTIFY_DONE; |
62 | } |
63 | |
64 | static struct notifier_block efibc_reboot_notifier = { |
65 | .notifier_call = efibc_reboot_notifier_call, |
66 | }; |
67 | |
68 | static 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 | } |
81 | module_init(efibc_init); |
82 | |
83 | static void __exit efibc_exit(void) |
84 | { |
85 | unregister_reboot_notifier(&efibc_reboot_notifier); |
86 | } |
87 | module_exit(efibc_exit); |
88 | |
89 | MODULE_AUTHOR("Jeremy Compostella <jeremy.compostella@intel.com>" ); |
90 | MODULE_AUTHOR("Matt Gumbel <matthew.k.gumbel@intel.com" ); |
91 | MODULE_DESCRIPTION("EFI Bootloader Control" ); |
92 | MODULE_LICENSE("GPL v2" ); |
93 | |