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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
14static void efibc_str_to_str16(const char *str, efi_char16_t *str16)
15{
16 size_t i;
17
18 for (i = 0; i < strlen(str); i++)
19 str16[i] = str[i];
20
21 str16[i] = '\0';
22}
23
24static int efibc_set_variable(const char *name, const char *value)
25{
26 int ret;
27 efi_guid_t guid = LINUX_EFI_LOADER_ENTRY_GUID;
28 struct efivar_entry *entry;
29 size_t size = (strlen(value) + 1) * sizeof(efi_char16_t);
30
31 if (size > sizeof(entry->var.Data)) {
32 pr_err("value is too large (%zu bytes) for '%s' EFI variable\n", size, name);
33 return -EINVAL;
34 }
35
36 entry = kmalloc(sizeof(*entry), GFP_KERNEL);
37 if (!entry) {
38 pr_err("failed to allocate efivar entry for '%s' EFI variable\n", name);
39 return -ENOMEM;
40 }
41
42 efibc_str_to_str16(name, entry->var.VariableName);
43 efibc_str_to_str16(value, (efi_char16_t *)entry->var.Data);
44 memcpy(&entry->var.VendorGuid, &guid, sizeof(guid));
45
46 ret = efivar_entry_set_safe(entry->var.VariableName,
47 entry->var.VendorGuid,
48 EFI_VARIABLE_NON_VOLATILE
49 | EFI_VARIABLE_BOOTSERVICE_ACCESS
50 | EFI_VARIABLE_RUNTIME_ACCESS,
51 false, size, entry->var.Data);
52
53 if (ret)
54 pr_err("failed to set %s EFI variable: 0x%x\n",
55 name, ret);
56
57 kfree(entry);
58 return ret;
59}
60
61static int efibc_reboot_notifier_call(struct notifier_block *notifier,
62 unsigned long event, void *data)
63{
64 const char *reason = "shutdown";
65 int ret;
66
67 if (event == SYS_RESTART)
68 reason = "reboot";
69
70 ret = efibc_set_variable("LoaderEntryRebootReason", reason);
71 if (ret || !data)
72 return NOTIFY_DONE;
73
74 efibc_set_variable("LoaderEntryOneShot", (char *)data);
75
76 return NOTIFY_DONE;
77}
78
79static struct notifier_block efibc_reboot_notifier = {
80 .notifier_call = efibc_reboot_notifier_call,
81};
82
83static int __init efibc_init(void)
84{
85 int ret;
86
87 if (!efivars_kobject() || !efivar_supports_writes())
88 return -ENODEV;
89
90 ret = register_reboot_notifier(&efibc_reboot_notifier);
91 if (ret)
92 pr_err("unable to register reboot notifier\n");
93
94 return ret;
95}
96module_init(efibc_init);
97
98static void __exit efibc_exit(void)
99{
100 unregister_reboot_notifier(&efibc_reboot_notifier);
101}
102module_exit(efibc_exit);
103
104MODULE_AUTHOR("Jeremy Compostella <jeremy.compostella@intel.com>");
105MODULE_AUTHOR("Matt Gumbel <matthew.k.gumbel@intel.com");
106MODULE_DESCRIPTION("EFI Bootloader Control");
107MODULE_LICENSE("GPL v2");
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
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_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
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");