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 000000000..503bbe2a9
--- /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 (%zu bytes) for '%s' EFI variable\n", size, name);
+		return -EINVAL;
+	}
+
+	entry = kmalloc(sizeof(*entry), GFP_KERNEL);
+	if (!entry) {
+		pr_err("failed to allocate efivar entry for '%s' EFI variable\n", name);
+		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");