path: root/arch/x86/boot/header.S

/* SPDX-License-Identifier: GPL-2.0 */
/*
 *	header.S
 *
 *	Copyright (C) 1991, 1992 Linus Torvalds
 *
 *	Based on bootsect.S and setup.S
 *	modified by more people than can be counted
 *
 *	Rewritten as a common file by H. Peter Anvin (Apr 2007)
 *
 * BIG FAT NOTE: We're in real mode using 64k segments.  Therefore segment
 * addresses must be multiplied by 16 to obtain their respective linear
 * addresses. To avoid confusion, linear addresses are written using leading
 * hex while segment addresses are written as segment:offset.
 *
 */
#include <linux/pe.h>
#include <asm/segment.h>
#include <asm/boot.h>
#include <asm/page_types.h>
#include <asm/setup.h>
#include <asm/bootparam.h>
#include "boot.h"
#include "voffset.h"
#include "zoffset.h"

BOOTSEG		= 0x07C0		/* original address of boot-sector */
SYSSEG		= 0x1000		/* historical load address >> 4 */

#ifndef SVGA_MODE
#define SVGA_MODE ASK_VGA
#endif

#ifndef ROOT_RDONLY
#define ROOT_RDONLY 1
#endif

	.set	salign, 0x1000
	.set	falign, 0x200

	.code16
	.section ".bstext", "ax"
#ifdef CONFIG_EFI_STUB
	# "MZ", MS-DOS header
	.word	MZ_MAGIC
	.org	0x38
	#
	# Offset to the PE header.
	#
	.long	LINUX_PE_MAGIC
	.long	pe_header
pe_header:
	.long	PE_MAGIC

coff_header:
#ifdef CONFIG_X86_32
	.set	image_file_add_flags, IMAGE_FILE_32BIT_MACHINE
	.set	pe_opt_magic, PE_OPT_MAGIC_PE32
	.word	IMAGE_FILE_MACHINE_I386
#else
	.set	image_file_add_flags, 0
	.set	pe_opt_magic, PE_OPT_MAGIC_PE32PLUS
	.word	IMAGE_FILE_MACHINE_AMD64
#endif
	.word	section_count			# nr_sections
	.long	0 				# TimeDateStamp
	.long	0				# PointerToSymbolTable
	.long	1				# NumberOfSymbols
	.word	section_table - optional_header	# SizeOfOptionalHeader
	.word	IMAGE_FILE_EXECUTABLE_IMAGE	| \
		image_file_add_flags		| \
		IMAGE_FILE_DEBUG_STRIPPED	| \
		IMAGE_FILE_LINE_NUMS_STRIPPED	# Characteristics

optional_header:
	.word	pe_opt_magic
	.byte	0x02				# MajorLinkerVersion
	.byte	0x14				# MinorLinkerVersion

	.long	ZO__data			# SizeOfCode

	.long	ZO__end - ZO__data		# SizeOfInitializedData
	.long	0				# SizeOfUninitializedData

	.long	setup_size + ZO_efi_pe_entry	# AddressOfEntryPoint

	.long	setup_size			# BaseOfCode
#ifdef CONFIG_X86_32
	.long	0				# data
#endif

extra_header_fields:
#ifdef CONFIG_X86_32
	.long	0				# ImageBase
#else
	.quad	0				# ImageBase
#endif
	.long	salign				# SectionAlignment
	.long	falign				# FileAlignment
	.word	0				# MajorOperatingSystemVersion
	.word	0				# MinorOperatingSystemVersion
	.word	LINUX_EFISTUB_MAJOR_VERSION	# MajorImageVersion
	.word	LINUX_EFISTUB_MINOR_VERSION	# MinorImageVersion
	.word	0				# MajorSubsystemVersion
	.word	0				# MinorSubsystemVersion
	.long	0				# Win32VersionValue

	.long	setup_size + ZO__end		# SizeOfImage

	.long	salign				# SizeOfHeaders
	.long	0				# CheckSum
	.word	IMAGE_SUBSYSTEM_EFI_APPLICATION	# Subsystem (EFI application)
	.word	IMAGE_DLL_CHARACTERISTICS_NX_COMPAT	# DllCharacteristics
#ifdef CONFIG_X86_32
	.long	0				# SizeOfStackReserve
	.long	0				# SizeOfStackCommit
	.long	0				# SizeOfHeapReserve
	.long	0				# SizeOfHeapCommit
#else
	.quad	0				# SizeOfStackReserve
	.quad	0				# SizeOfStackCommit
	.quad	0				# SizeOfHeapReserve
	.quad	0				# SizeOfHeapCommit
#endif
	.long	0				# LoaderFlags
	.long	(section_table - .) / 8		# NumberOfRvaAndSizes

	.quad	0				# ExportTable
	.quad	0				# ImportTable
	.quad	0				# ResourceTable
	.quad	0				# ExceptionTable
	.quad	0				# CertificationTable
	.quad	0				# BaseRelocationTable

	# Section table
section_table:
	.ascii	".setup"
	.byte	0
	.byte	0
	.long	pecompat_fstart - salign 	# VirtualSize
	.long	salign				# VirtualAddress
	.long	pecompat_fstart - salign	# SizeOfRawData
	.long	salign				# PointerToRawData

	.long	0, 0, 0
	.long	IMAGE_SCN_CNT_INITIALIZED_DATA	| \
		IMAGE_SCN_MEM_READ		| \
		IMAGE_SCN_MEM_DISCARDABLE	# Characteristics

#ifdef CONFIG_EFI_MIXED
	.asciz	".compat"

	.long	pecompat_fsize			# VirtualSize
	.long	pecompat_fstart			# VirtualAddress
	.long	pecompat_fsize			# SizeOfRawData
	.long	pecompat_fstart			# PointerToRawData

	.long	0, 0, 0
	.long	IMAGE_SCN_CNT_INITIALIZED_DATA	| \
		IMAGE_SCN_MEM_READ		| \
		IMAGE_SCN_MEM_DISCARDABLE	# Characteristics

	/*
	 * Put the IA-32 machine type and the associated entry point address in
	 * the .compat section, so loaders can figure out which other execution
	 * modes this image supports.
	 */
	.pushsection ".pecompat", "a", @progbits
	.balign	salign
	.globl	pecompat_fstart
pecompat_fstart:
	.byte	0x1				# Version
	.byte	8				# Size
	.word	IMAGE_FILE_MACHINE_I386		# PE machine type
	.long	setup_size + ZO_efi32_pe_entry	# Entrypoint
	.byte	0x0				# Sentinel
	.popsection
#else
	.set	pecompat_fstart, setup_size
#endif
	.ascii	".text"
	.byte	0
	.byte	0
	.byte	0
	.long	ZO__data
	.long	setup_size
	.long	ZO__data			# Size of initialized data
						# on disk
	.long	setup_size
	.long	0				# PointerToRelocations
	.long	0				# PointerToLineNumbers
	.word	0				# NumberOfRelocations
	.word	0				# NumberOfLineNumbers
	.long	IMAGE_SCN_CNT_CODE		| \
		IMAGE_SCN_MEM_READ		| \
		IMAGE_SCN_MEM_EXECUTE		# Characteristics

	.ascii	".data\0\0\0"
	.long	ZO__end - ZO__data		# VirtualSize
	.long	setup_size + ZO__data		# VirtualAddress
	.long	ZO__edata - ZO__data		# SizeOfRawData
	.long	setup_size + ZO__data		# PointerToRawData

	.long	0, 0, 0
	.long	IMAGE_SCN_CNT_INITIALIZED_DATA	| \
		IMAGE_SCN_MEM_READ		| \
		IMAGE_SCN_MEM_WRITE		# Characteristics

	.set	section_count, (. - section_table) / 40
#endif /* CONFIG_EFI_STUB */

	# Kernel attributes; used by setup.  This is part 1 of the
	# header, from the old boot sector.

	.section ".header", "a"
	.globl	sentinel
sentinel:	.byte 0xff, 0xff        /* Used to detect broken loaders */

	.globl	hdr
hdr:
		.byte setup_sects - 1
root_flags:	.word ROOT_RDONLY
syssize:	.long ZO__edata / 16
ram_size:	.word 0			/* Obsolete */
vid_mode:	.word SVGA_MODE
root_dev:	.word 0			/* Default to major/minor 0/0 */
boot_flag:	.word 0xAA55

	# offset 512, entry point

	.globl	_start
_start:
		# Explicitly enter this as bytes, or the assembler
		# tries to generate a 3-byte jump here, which causes
		# everything else to push off to the wrong offset.
		.byte	0xeb		# short (2-byte) jump
		.byte	start_of_setup-1f
1:

	# Part 2 of the header, from the old setup.S

		.ascii	"HdrS"		# header signature
		.word	0x020f		# header version number (>= 0x0105)
					# or else old loadlin-1.5 will fail)
		.globl