path: root/drivers/firmware/efi/efi.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * efi.c - EFI subsystem
 *
 * Copyright (C) 2001,2003,2004 Dell <Matt_Domsch@dell.com>
 * Copyright (C) 2004 Intel Corporation <matthew.e.tolentino@intel.com>
 * Copyright (C) 2013 Tom Gundersen <teg@jklm.no>
 *
 * This code registers /sys/firmware/efi{,/efivars} when EFI is supported,
 * allowing the efivarfs to be mounted or the efivars module to be loaded.
 * The existance of /sys/firmware/efi may also be used by userspace to
 * determine that the system supports EFI.
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/kobject.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/debugfs.h>
#include <linux/device.h>
#include <linux/efi.h>
#include <linux/of.h>
#include <linux/initrd.h>
#include <linux/io.h>
#include <linux/kexec.h>
#include <linux/platform_device.h>
#include <linux/random.h>
#include <linux/reboot.h>
#include <linux/slab.h>
#include <linux/acpi.h>
#include <linux/ucs2_string.h>
#include <linux/memblock.h>
#include <linux/security.h>

#include <asm/early_ioremap.h>

struct efi __read_mostly efi = {
	.runtime_supported_mask = EFI_RT_SUPPORTED_ALL,
	.acpi			= EFI_INVALID_TABLE_ADDR,
	.acpi20			= EFI_INVALID_TABLE_ADDR,
	.smbios			= EFI_INVALID_TABLE_ADDR,
	.smbios3		= EFI_INVALID_TABLE_ADDR,
	.esrt			= EFI_INVALID_TABLE_ADDR,
	.tpm_log		= EFI_INVALID_TABLE_ADDR,
	.tpm_final_log		= EFI_INVALID_TABLE_ADDR,
#ifdef CONFIG_LOAD_UEFI_KEYS
	.mokvar_table		= EFI_INVALID_TABLE_ADDR,
#endif
#ifdef CONFIG_EFI_COCO_SECRET
	.coco_secret		= EFI_INVALID_TABLE_ADDR,
#endif
};
EXPORT_SYMBOL(efi);

unsigned long __ro_after_init efi_rng_seed = EFI_INVALID_TABLE_ADDR;
static unsigned long __initdata mem_reserve = EFI_INVALID_TABLE_ADDR;
static unsigned long __initdata rt_prop = EFI_INVALID_TABLE_ADDR;
static unsigned long __initdata initrd = EFI_INVALID_TABLE_ADDR;

extern unsigned long screen_info_table;

struct mm_struct efi_mm = {
	.mm_mt			= MTREE_INIT_EXT(mm_mt, MM_MT_FLAGS, efi_mm.mmap_lock),
	.mm_users		= ATOMIC_INIT(2),
	.mm_count		= ATOMIC_INIT(1),
	.write_protect_seq      = SEQCNT_ZERO(efi_mm.write_protect_seq),
	MMAP_LOCK_INITIALIZER(efi_mm)
	.page_table_lock	= __SPIN_LOCK_UNLOCKED(efi_mm.page_table_lock),
	.mmlist			= LIST_HEAD_INIT(efi_mm.mmlist),
	.cpu_bitmap		= { [BITS_TO_LONGS(NR_CPUS)] = 0},
};

struct workqueue_struct *efi_rts_wq;

static bool disable_runtime = IS_ENABLED(CONFIG_EFI_DISABLE_RUNTIME);
static int __init setup_noefi(char *arg)
{
	disable_runtime = true;
	return 0;
}
early_param("noefi", setup_noefi);

bool efi_runtime_disabled(void)
{
	return disable_runtime;
}

bool __pure __efi_soft_reserve_enabled(void)
{
	return !efi_enabled(EFI_MEM_NO_SOFT_RESERVE);
}

static int __init parse_efi_cmdline(char *str)
{
	if (!str) {
		pr_warn("need at least one option\n");
		return -EINVAL;
	}

	if (parse_option_str(str, "debug"))
		set_bit(EFI_DBG, &efi.flags);

	if (parse_option_str(str, "noruntime"))
		disable_runtime = true;

	if (parse_option_str(str, "runtime"))
		disable_runtime = false;

	if (parse_option_str(str, "nosoftreserve"))
		set_bit(EFI_MEM_NO_SOFT_RESERVE, &efi.flags);

	return 0;
}
early_param("efi", parse_efi_cmdline);

struct kobject *efi_kobj;

/*
 * Let's not leave out systab information that snuck into
 * the efivars driver
 * Note, do not add more fields in systab sysfs file as it breaks sysfs
 * one value per file rule!
 */
static ssize_t systab_show(struct kobject *kobj,
			   struct kobj_attribute *attr, char *buf)
{
	char *str = buf;

	if (!kobj || !buf)
		return -EINVAL;

	if (efi.acpi20 != EFI_INVALID_TABLE_ADDR)
		str += sprintf(str, "ACPI20=0x%lx\n", efi.acpi20);
	if (efi.acpi != EFI_INVALID_TABLE_ADDR)
		str += sprintf(str, "ACPI=0x%lx\n", efi.acpi);
	/*
	 * If both SMBIOS and SMBIOS3 entry points are implemented, the
	 * SMBIOS3 entry point shall be preferred, so we list it first to
	 * let applications stop parsing after the first match.
	 */
	if (efi.smbios3 != EFI_INVALID_TABLE_ADDR)
		str += sprintf(str, "SMBIOS3=0x%lx\n", efi.smbios3);
	if (efi.smbios != EFI_INVALID_TABLE_ADDR)
		str += sprintf(str, "SMBIOS=0x%lx\n", efi.smbios);

	if (IS_ENABLED(CONFIG_IA64) || IS_ENABLED(CONFIG_X86))
		str = efi_systab_show_arch(str);

	return str - buf;
}

static struct kobj_attribute efi_attr_systab = __ATTR_RO_MODE(systab, 0400);

static ssize_t fw_platform_size_show(struct kobject *kobj,
				     struct kobj_attribute *attr, char *buf)
{
	return sprin