arch/x86/platform/efi/efi_64.c

Source file repositories/reference/linux-study-clean/arch/x86/platform/efi/efi_64.c

File Facts

System
Linux kernel
Corpus path
arch/x86/platform/efi/efi_64.c
Extension
.c
Size
23194 bytes
Lines
876
Domain
Architecture Layer
Bucket
arch/x86
Inferred role
Architecture Layer: implementation source
Status
source implementation candidate

Why This File Exists

CPU and platform-specific kernel glue: boot entry, traps, syscall entry, interrupts, page tables, context switch, and low-level barriers.

Dependency Surface

Detected Declarations

Annotated Snippet

// SPDX-License-Identifier: GPL-2.0
/*
 * x86_64 specific EFI support functions
 * Based on Extensible Firmware Interface Specification version 1.0
 *
 * Copyright (C) 2005-2008 Intel Co.
 *	Fenghua Yu <fenghua.yu@intel.com>
 *	Bibo Mao <bibo.mao@intel.com>
 *	Chandramouli Narayanan <mouli@linux.intel.com>
 *	Huang Ying <ying.huang@intel.com>
 *
 * Code to convert EFI to E820 map has been implemented in elilo bootloader
 * based on a EFI patch by Edgar Hucek. Based on the E820 map, the page table
 * is setup appropriately for EFI runtime code.
 * - mouli 06/14/2007.
 *
 */

#define pr_fmt(fmt) "efi: " fmt

#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/mm.h>
#include <linux/types.h>
#include <linux/spinlock.h>
#include <linux/memblock.h>
#include <linux/ioport.h>
#include <linux/mc146818rtc.h>
#include <linux/efi.h>
#include <linux/export.h>
#include <linux/uaccess.h>
#include <linux/io.h>
#include <linux/reboot.h>
#include <linux/slab.h>
#include <linux/ucs2_string.h>
#include <linux/cc_platform.h>
#include <linux/sched/task.h>

#include <asm/setup.h>
#include <asm/page.h>
#include <asm/e820/api.h>
#include <asm/tlbflush.h>
#include <asm/proto.h>
#include <asm/efi.h>
#include <asm/cacheflush.h>
#include <asm/fixmap.h>
#include <asm/realmode.h>
#include <asm/time.h>
#include <asm/pgalloc.h>
#include <asm/sev.h>

/*
 * We allocate runtime services regions top-down, starting from -4G, i.e.
 * 0xffff_ffff_0000_0000 and limit EFI VA mapping space to 64G.
 */
static u64 efi_va = EFI_VA_START;
static struct mm_struct *efi_prev_mm;
static unsigned long efi_cr4_lass;

/*
 * We need our own copy of the higher levels of the page tables
 * because we want to avoid inserting EFI region mappings (EFI_VA_END
 * to EFI_VA_START) into the standard kernel page tables. Everything
 * else can be shared, see efi_sync_low_kernel_mappings().
 *
 * We don't want the pgd on the pgd_list and cannot use pgd_alloc() for the
 * allocation.
 */
int __init efi_alloc_page_tables(void)
{
	pgd_t *pgd, *efi_pgd;
	p4d_t *p4d;
	pud_t *pud;
	gfp_t gfp_mask;

	gfp_mask = GFP_KERNEL | __GFP_ZERO;
	efi_pgd = (pgd_t *)__get_free_pages(gfp_mask, pgd_allocation_order());
	if (!efi_pgd)
		goto fail;

	pgd = efi_pgd + pgd_index(EFI_VA_END);
	p4d = p4d_alloc(&init_mm, pgd, EFI_VA_END);
	if (!p4d)
		goto free_pgd;

	pud = pud_alloc(&init_mm, p4d, EFI_VA_END);
	if (!pud)
		goto free_p4d;

	efi_mm.pgd = efi_pgd;

Annotation

Implementation Notes