efibc: Add EFI Bootloader Control module (06f7d4a1) · Commits · 戴 / test

drivers/firmware/efi/Kconfig

+15 −0

Original line number	Diff line number	Diff line
		@@ -87,6 +87,21 @@ config EFI_RUNTIME_WRAPPERS
		config EFI_ARMSTUB
		bool

		config EFI_BOOTLOADER_CONTROL
		tristate "EFI Bootloader Control"
		depends on EFI_VARS
		default n
		---help---
		This module installs a reboot hook, such that if reboot() is
		invoked with a string argument NNN, "NNN" is copied to the
		"LoaderEntryOneShot" EFI variable, to be read by the
		bootloader. If the string matches one of the boot labels
		defined in its configuration, the bootloader will boot once
		to that label. The "LoaderEntryRebootReason" EFI variable is
		set with the reboot reason: "reboot" or "shutdown". The
		bootloader reads this reboot reason and takes particular
		action according to its policy.

		endmenu

		config UEFI_CPER

drivers/firmware/efi/Makefile

+1 −0

Original line number	Diff line number	Diff line
		@@ -18,6 +18,7 @@ obj-$(CONFIG_EFI_RUNTIME_MAP) += runtime-map.o
		obj-$(CONFIG_EFI_RUNTIME_WRAPPERS) += runtime-wrappers.o
		obj-$(CONFIG_EFI_STUB) += libstub/
		obj-$(CONFIG_EFI_FAKE_MEMMAP) += fake_mem.o
		obj-$(CONFIG_EFI_BOOTLOADER_CONTROL) += efibc.o

		arm-obj-$(CONFIG_EFI) := arm-init.o arm-runtime.o
		obj-$(CONFIG_ARM) += $(arm-obj-y)

drivers/firmware/efi/efibc.c

0 → 100644

+101 −0

Original line number	Diff line number	Diff line
		/*
		* 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>

		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 void 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");

		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);
		}

		static int efibc_reboot_notifier_call(struct notifier_block *notifier,
		unsigned long event, void *data)
		{
		const char *reason = "shutdown";

		if (event == SYS_RESTART)
		reason = "reboot";

		efibc_set_variable("LoaderEntryRebootReason", reason);

		if (!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");

include/linux/efi.h

+4 −0

Original line number	Diff line number	Diff line
		@@ -642,6 +642,10 @@ void efi_native_runtime_setup(void);
		EFI_GUID(0xe03fc20a, 0x85dc, 0x406e, \
		0xb9, 0xe, 0x4a, 0xb5, 0x02, 0x37, 0x1d, 0x95)

		#define LINUX_EFI_LOADER_ENTRY_GUID \
		EFI_GUID(0x4a67b082, 0x0a4c, 0x41cf, \
		0xb6, 0xc7, 0x44, 0x0b, 0x29, 0xbb, 0x8c, 0x4f)

		typedef struct {
		efi_guid_t guid;
		u64 table;

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