1 files changed, 113 insertions, 0 deletions

diff --git a/drivers/firmware/efi/efibc.c b/drivers/firmware/efi/efibc.c
new file mode 100644
index 000000000000..8dd0c7085e59
--- /dev/null
+++ b/drivers/firmware/efi/efibc.c
@@ -0,0 +1,113 @@
+/*
+ * efibc: control EFI bootloaders which obey LoaderEntryOneShot var
+ * Copyright (c) 2013-2016, Intel Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ */
+
+#define pr_fmt(fmt) "efibc: " fmt
+
+#include <linux/efi.h>
+#include <linux/module.h>
+#include <linux/reboot.h>
+#include <linux/slab.h>
+
+static void efibc_str_to_str16(const char *str, efi_char16_t *str16)
+{
+        size_t i;
+
+        for (i = 0; i < strlen(str); i++)
+                str16[i] = str[i];
+
+        str16[i] = '\0';
+}
+
+static int efibc_set_variable(const char *name, const char *value)
+{
+        int ret;
+        efi_guid_t guid = LINUX_EFI_LOADER_ENTRY_GUID;
+        struct efivar_entry *entry;
+        size_t size = (strlen(value) + 1) * sizeof(efi_char16_t);
+
+        if (size > sizeof(entry->var.Data)) {
+                pr_err("value is too large");
+                return -EINVAL;
+        }
+
+        entry = kmalloc(sizeof(*entry), GFP_KERNEL);
+        if (!entry) {
+                pr_err("failed to allocate efivar entry");
+                return -ENOMEM;
+        }
+
+        efibc_str_to_str16(name, entry->var.VariableName);
+        efibc_str_to_str16(value, (efi_char16_t *)entry->var.Data);
+        memcpy(&entry->var.VendorGuid, &guid, sizeof(guid));
+
+        ret = efivar_entry_set(entry,
+                               EFI_VARIABLE_NON_VOLATILE
+                               | EFI_VARIABLE_BOOTSERVICE_ACCESS
+                               | EFI_VARIABLE_RUNTIME_ACCESS,
+                               size, entry->var.Data, NULL);
+        if (ret)
+                pr_err("failed to set %s EFI variable: 0x%x\n",
+                       name, ret);
+
+        kfree(entry);
+        return ret;
+}
+
+static int efibc_reboot_notifier_call(struct notifier_block *notifier,
+                                      unsigned long event, void *data)
+{
+        const char *reason = "shutdown";
+        int ret;
+
+        if (event == SYS_RESTART)
+                reason = "reboot";
+
+        ret = efibc_set_variable("LoaderEntryRebootReason", reason);
+        if (ret || !data)
+                return NOTIFY_DONE;
+
+        efibc_set_variable("LoaderEntryOneShot", (char *)data);
+
+        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_enabled(EFI_RUNTIME_SERVICES))
+                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");