linux/drivers/firmware/efi/libstub/x86-5lvl.c

// SPDX-License-Identifier: GPL-2.0-only
#include <linux/efi.h>

#include <asm/boot.h>
#include <asm/desc.h>
#include <asm/efi.h>

#include "efistub.h"
#include "x86-stub.h"

bool efi_no5lvl;

static void (*la57_toggle)(void *cr3);

static const struct desc_struct gdt[] = …;

/*
 * Enabling (or disabling) 5 level paging is tricky, because it can only be
 * done from 32-bit mode with paging disabled. This means not only that the
 * code itself must be running from 32-bit addressable physical memory, but
 * also that the root page table must be 32-bit addressable, as programming
 * a 64-bit value into CR3 when running in 32-bit mode is not supported.
 */
efi_status_t efi_setup_5level_paging(void)
{ … }

void efi_5level_switch(void)
{ … }