mirror of
https://mirrors.bfsu.edu.cn/git/linux.git
synced 2024-12-23 02:54:32 +08:00
0fe4f4ef8c
Bump the ZO_z_extra_bytes margin for zstd. Zstd needs 3 bytes per 128 KB, and has a 22 byte fixed overhead. Zstd needs to maintain 128 KB of space at all times, since that is the maximum block size. See the comments regarding in-place decompression added in lib/decompress_unzstd.c for details. The existing code is written so that all the compression algorithms use the same ZO_z_extra_bytes. It is taken to be the maximum of the growth rate plus the maximum fixed overhead. The comments just above this diff state that: Signed-off-by: Nick Terrell <terrelln@fb.com> Signed-off-by: Ingo Molnar <mingo@kernel.org> Tested-by: Sedat Dilek <sedat.dilek@gmail.com> Reviewed-by: Kees Cook <keescook@chromium.org> Link: https://lore.kernel.org/r/20200730190841.2071656-6-nickrterrell@gmail.com
657 lines
18 KiB
ArmAsm
657 lines
18 KiB
ArmAsm
/* 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
|
|
|
|
.code16
|
|
.section ".bstext", "ax"
|
|
|
|
.global bootsect_start
|
|
bootsect_start:
|
|
#ifdef CONFIG_EFI_STUB
|
|
# "MZ", MS-DOS header
|
|
.word MZ_MAGIC
|
|
#endif
|
|
|
|
# Normalize the start address
|
|
ljmp $BOOTSEG, $start2
|
|
|
|
start2:
|
|
movw %cs, %ax
|
|
movw %ax, %ds
|
|
movw %ax, %es
|
|
movw %ax, %ss
|
|
xorw %sp, %sp
|
|
sti
|
|
cld
|
|
|
|
movw $bugger_off_msg, %si
|
|
|
|
msg_loop:
|
|
lodsb
|
|
andb %al, %al
|
|
jz bs_die
|
|
movb $0xe, %ah
|
|
movw $7, %bx
|
|
int $0x10
|
|
jmp msg_loop
|
|
|
|
bs_die:
|
|
# Allow the user to press a key, then reboot
|
|
xorw %ax, %ax
|
|
int $0x16
|
|
int $0x19
|
|
|
|
# int 0x19 should never return. In case it does anyway,
|
|
# invoke the BIOS reset code...
|
|
ljmp $0xf000,$0xfff0
|
|
|
|
#ifdef CONFIG_EFI_STUB
|
|
.org 0x3c
|
|
#
|
|
# Offset to the PE header.
|
|
#
|
|
.long pe_header
|
|
#endif /* CONFIG_EFI_STUB */
|
|
|
|
.section ".bsdata", "a"
|
|
bugger_off_msg:
|
|
.ascii "Use a boot loader.\r\n"
|
|
.ascii "\n"
|
|
.ascii "Remove disk and press any key to reboot...\r\n"
|
|
.byte 0
|
|
|
|
#ifdef CONFIG_EFI_STUB
|
|
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
|
|
|
|
# Filled in by build.c
|
|
.long 0 # SizeOfCode
|
|
|
|
.long 0 # SizeOfInitializedData
|
|
.long 0 # SizeOfUninitializedData
|
|
|
|
# Filled in by build.c
|
|
.long 0x0000 # AddressOfEntryPoint
|
|
|
|
.long 0x0200 # BaseOfCode
|
|
#ifdef CONFIG_X86_32
|
|
.long 0 # data
|
|
#endif
|
|
|
|
extra_header_fields:
|
|
# PE specification requires ImageBase to be 64k aligned
|
|
.set image_base, (LOAD_PHYSICAL_ADDR + 0xffff) & ~0xffff
|
|
#ifdef CONFIG_X86_32
|
|
.long image_base # ImageBase
|
|
#else
|
|
.quad image_base # ImageBase
|
|
#endif
|
|
.long 0x20 # SectionAlignment
|
|
.long 0x20 # 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
|
|
|
|
#
|
|
# The size of the bzImage is written in tools/build.c
|
|
#
|
|
.long 0 # SizeOfImage
|
|
|
|
.long 0x200 # SizeOfHeaders
|
|
.long 0 # CheckSum
|
|
.word IMAGE_SUBSYSTEM_EFI_APPLICATION # Subsystem (EFI application)
|
|
.word 0 # 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:
|
|
#
|
|
# The offset & size fields are filled in by build.c.
|
|
#
|
|
.ascii ".setup"
|
|
.byte 0
|
|
.byte 0
|
|
.long 0
|
|
.long 0x0 # startup_{32,64}
|
|
.long 0 # Size of initialized data
|
|
# on disk
|
|
.long 0x0 # startup_{32,64}
|
|
.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 | \
|
|
IMAGE_SCN_ALIGN_16BYTES # Characteristics
|
|
|
|
#
|
|
# The EFI application loader requires a relocation section
|
|
# because EFI applications must be relocatable. The .reloc
|
|
# offset & size fields are filled in by build.c.
|
|
#
|
|
.ascii ".reloc"
|
|
.byte 0
|
|
.byte 0
|
|
.long 0
|
|
.long 0
|
|
.long 0 # SizeOfRawData
|
|
.long 0 # PointerToRawData
|
|
.long 0 # PointerToRelocations
|
|
.long 0 # PointerToLineNumbers
|
|
.word 0 # NumberOfRelocations
|
|
.word 0 # NumberOfLineNumbers
|
|
.long IMAGE_SCN_CNT_INITIALIZED_DATA | \
|
|
IMAGE_SCN_MEM_READ | \
|
|
IMAGE_SCN_MEM_DISCARDABLE | \
|
|
IMAGE_SCN_ALIGN_1BYTES # Characteristics
|
|
|
|
#ifdef CONFIG_EFI_MIXED
|
|
#
|
|
# The offset & size fields are filled in by build.c.
|
|
#
|
|
.asciz ".compat"
|
|
.long 0
|
|
.long 0x0
|
|
.long 0 # Size of initialized data
|
|
# on disk
|
|
.long 0x0
|
|
.long 0 # PointerToRelocations
|
|
.long 0 # PointerToLineNumbers
|
|
.word 0 # NumberOfRelocations
|
|
.word 0 # NumberOfLineNumbers
|
|
.long IMAGE_SCN_CNT_INITIALIZED_DATA | \
|
|
IMAGE_SCN_MEM_READ | \
|
|
IMAGE_SCN_MEM_DISCARDABLE | \
|
|
IMAGE_SCN_ALIGN_1BYTES # Characteristics
|
|
#endif
|
|
|
|
#
|
|
# The offset & size fields are filled in by build.c.
|
|
#
|
|
.ascii ".text"
|
|
.byte 0
|
|
.byte 0
|
|
.byte 0
|
|
.long 0
|
|
.long 0x0 # startup_{32,64}
|
|
.long 0 # Size of initialized data
|
|
# on disk
|
|
.long 0x0 # startup_{32,64}
|
|
.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 | \
|
|
IMAGE_SCN_ALIGN_16BYTES # 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:
|
|
setup_sects: .byte 0 /* Filled in by build.c */
|
|
root_flags: .word ROOT_RDONLY
|
|
syssize: .long 0 /* Filled in by build.c */
|
|
ram_size: .word 0 /* Obsolete */
|
|
vid_mode: .word SVGA_MODE
|
|
root_dev: .word 0 /* Filled in by build.c */
|
|
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 realmode_swtch
|
|
realmode_swtch: .word 0, 0 # default_switch, SETUPSEG
|
|
start_sys_seg: .word SYSSEG # obsolete and meaningless, but just
|
|
# in case something decided to "use" it
|
|
.word kernel_version-512 # pointing to kernel version string
|
|
# above section of header is compatible
|
|
# with loadlin-1.5 (header v1.5). Don't
|
|
# change it.
|
|
|
|
type_of_loader: .byte 0 # 0 means ancient bootloader, newer
|
|
# bootloaders know to change this.
|
|
# See Documentation/x86/boot.rst for
|
|
# assigned ids
|
|
|
|
# flags, unused bits must be zero (RFU) bit within loadflags
|
|
loadflags:
|
|
.byte LOADED_HIGH # The kernel is to be loaded high
|
|
|
|
setup_move_size: .word 0x8000 # size to move, when setup is not
|
|
# loaded at 0x90000. We will move setup
|
|
# to 0x90000 then just before jumping
|
|
# into the kernel. However, only the
|
|
# loader knows how much data behind
|
|
# us also needs to be loaded.
|
|
|
|
code32_start: # here loaders can put a different
|
|
# start address for 32-bit code.
|
|
.long 0x100000 # 0x100000 = default for big kernel
|
|
|
|
ramdisk_image: .long 0 # address of loaded ramdisk image
|
|
# Here the loader puts the 32-bit
|
|
# address where it loaded the image.
|
|
# This only will be read by the kernel.
|
|
|
|
ramdisk_size: .long 0 # its size in bytes
|
|
|
|
bootsect_kludge:
|
|
.long 0 # obsolete
|
|
|
|
heap_end_ptr: .word _end+STACK_SIZE-512
|
|
# (Header version 0x0201 or later)
|
|
# space from here (exclusive) down to
|
|
# end of setup code can be used by setup
|
|
# for local heap purposes.
|
|
|
|
ext_loader_ver:
|
|
.byte 0 # Extended boot loader version
|
|
ext_loader_type:
|
|
.byte 0 # Extended boot loader type
|
|
|
|
cmd_line_ptr: .long 0 # (Header version 0x0202 or later)
|
|
# If nonzero, a 32-bit pointer
|
|
# to the kernel command line.
|
|
# The command line should be
|
|
# located between the start of
|
|
# setup and the end of low
|
|
# memory (0xa0000), or it may
|
|
# get overwritten before it
|
|
# gets read. If this field is
|
|
# used, there is no longer
|
|
# anything magical about the
|
|
# 0x90000 segment; the setup
|
|
# can be located anywhere in
|
|
# low memory 0x10000 or higher.
|
|
|
|
initrd_addr_max: .long 0x7fffffff
|
|
# (Header version 0x0203 or later)
|
|
# The highest safe address for
|
|
# the contents of an initrd
|
|
# The current kernel allows up to 4 GB,
|
|
# but leave it at 2 GB to avoid
|
|
# possible bootloader bugs.
|
|
|
|
kernel_alignment: .long CONFIG_PHYSICAL_ALIGN #physical addr alignment
|
|
#required for protected mode
|
|
#kernel
|
|
#ifdef CONFIG_RELOCATABLE
|
|
relocatable_kernel: .byte 1
|
|
#else
|
|
relocatable_kernel: .byte 0
|
|
#endif
|
|
min_alignment: .byte MIN_KERNEL_ALIGN_LG2 # minimum alignment
|
|
|
|
xloadflags:
|
|
#ifdef CONFIG_X86_64
|
|
# define XLF0 XLF_KERNEL_64 /* 64-bit kernel */
|
|
#else
|
|
# define XLF0 0
|
|
#endif
|
|
|
|
#if defined(CONFIG_RELOCATABLE) && defined(CONFIG_X86_64)
|
|
/* kernel/boot_param/ramdisk could be loaded above 4g */
|
|
# define XLF1 XLF_CAN_BE_LOADED_ABOVE_4G
|
|
#else
|
|
# define XLF1 0
|
|
#endif
|
|
|
|
#ifdef CONFIG_EFI_STUB
|
|
# ifdef CONFIG_EFI_MIXED
|
|
# define XLF23 (XLF_EFI_HANDOVER_32|XLF_EFI_HANDOVER_64)
|
|
# else
|
|
# ifdef CONFIG_X86_64
|
|
# define XLF23 XLF_EFI_HANDOVER_64 /* 64-bit EFI handover ok */
|
|
# else
|
|
# define XLF23 XLF_EFI_HANDOVER_32 /* 32-bit EFI handover ok */
|
|
# endif
|
|
# endif
|
|
#else
|
|
# define XLF23 0
|
|
#endif
|
|
|
|
#if defined(CONFIG_X86_64) && defined(CONFIG_EFI) && defined(CONFIG_KEXEC_CORE)
|
|
# define XLF4 XLF_EFI_KEXEC
|
|
#else
|
|
# define XLF4 0
|
|
#endif
|
|
|
|
#ifdef CONFIG_X86_64
|
|
#ifdef CONFIG_X86_5LEVEL
|
|
#define XLF56 (XLF_5LEVEL|XLF_5LEVEL_ENABLED)
|
|
#else
|
|
#define XLF56 XLF_5LEVEL
|
|
#endif
|
|
#else
|
|
#define XLF56 0
|
|
#endif
|
|
|
|
.word XLF0 | XLF1 | XLF23 | XLF4 | XLF56
|
|
|
|
cmdline_size: .long COMMAND_LINE_SIZE-1 #length of the command line,
|
|
#added with boot protocol
|
|
#version 2.06
|
|
|
|
hardware_subarch: .long 0 # subarchitecture, added with 2.07
|
|
# default to 0 for normal x86 PC
|
|
|
|
hardware_subarch_data: .quad 0
|
|
|
|
payload_offset: .long ZO_input_data
|
|
payload_length: .long ZO_z_input_len
|
|
|
|
setup_data: .quad 0 # 64-bit physical pointer to
|
|
# single linked list of
|
|
# struct setup_data
|
|
|
|
pref_address: .quad LOAD_PHYSICAL_ADDR # preferred load addr
|
|
|
|
#
|
|
# Getting to provably safe in-place decompression is hard. Worst case
|
|
# behaviours need to be analyzed. Here let's take the decompression of
|
|
# a gzip-compressed kernel as example, to illustrate it:
|
|
#
|
|
# The file layout of gzip compressed kernel is:
|
|
#
|
|
# magic[2]
|
|
# method[1]
|
|
# flags[1]
|
|
# timestamp[4]
|
|
# extraflags[1]
|
|
# os[1]
|
|
# compressed data blocks[N]
|
|
# crc[4] orig_len[4]
|
|
#
|
|
# ... resulting in +18 bytes overhead of uncompressed data.
|
|
#
|
|
# (For more information, please refer to RFC 1951 and RFC 1952.)
|
|
#
|
|
# Files divided into blocks
|
|
# 1 bit (last block flag)
|
|
# 2 bits (block type)
|
|
#
|
|
# 1 block occurs every 32K -1 bytes or when there 50% compression
|
|
# has been achieved. The smallest block type encoding is always used.
|
|
#
|
|
# stored:
|
|
# 32 bits length in bytes.
|
|
#
|
|
# fixed:
|
|
# magic fixed tree.
|
|
# symbols.
|
|
#
|
|
# dynamic:
|
|
# dynamic tree encoding.
|
|
# symbols.
|
|
#
|
|
#
|
|
# The buffer for decompression in place is the length of the uncompressed
|
|
# data, plus a small amount extra to keep the algorithm safe. The
|
|
# compressed data is placed at the end of the buffer. The output pointer
|
|
# is placed at the start of the buffer and the input pointer is placed
|
|
# where the compressed data starts. Problems will occur when the output
|
|
# pointer overruns the input pointer.
|
|
#
|
|
# The output pointer can only overrun the input pointer if the input
|
|
# pointer is moving faster than the output pointer. A condition only
|
|
# triggered by data whose compressed form is larger than the uncompressed
|
|
# form.
|
|
#
|
|
# The worst case at the block level is a growth of the compressed data
|
|
# of 5 bytes per 32767 bytes.
|
|
#
|
|
# The worst case internal to a compressed block is very hard to figure.
|
|
# The worst case can at least be bounded by having one bit that represents
|
|
# 32764 bytes and then all of the rest of the bytes representing the very
|
|
# very last byte.
|
|
#
|
|
# All of which is enough to compute an amount of extra data that is required
|
|
# to be safe. To avoid problems at the block level allocating 5 extra bytes
|
|
# per 32767 bytes of data is sufficient. To avoid problems internal to a
|
|
# block adding an extra 32767 bytes (the worst case uncompressed block size)
|
|
# is sufficient, to ensure that in the worst case the decompressed data for
|
|
# block will stop the byte before the compressed data for a block begins.
|
|
# To avoid problems with the compressed data's meta information an extra 18
|
|
# bytes are needed. Leading to the formula:
|
|
#
|
|
# extra_bytes = (uncompressed_size >> 12) + 32768 + 18
|
|
#
|
|
# Adding 8 bytes per 32K is a bit excessive but much easier to calculate.
|
|
# Adding 32768 instead of 32767 just makes for round numbers.
|
|
#
|
|
# Above analysis is for decompressing gzip compressed kernel only. Up to
|
|
# now 6 different decompressor are supported all together. And among them
|
|
# xz stores data in chunks and has maximum chunk of 64K. Hence safety
|
|
# margin should be updated to cover all decompressors so that we don't
|
|
# need to deal with each of them separately. Please check
|
|
# the description in lib/decompressor_xxx.c for specific information.
|
|
#
|
|
# extra_bytes = (uncompressed_size >> 12) + 65536 + 128
|
|
#
|
|
# LZ4 is even worse: data that cannot be further compressed grows by 0.4%,
|
|
# or one byte per 256 bytes. OTOH, we can safely get rid of the +128 as
|
|
# the size-dependent part now grows so fast.
|
|
#
|
|
# extra_bytes = (uncompressed_size >> 8) + 65536
|
|
#
|
|
# ZSTD compressed data grows by at most 3 bytes per 128K, and only has a 22
|
|
# byte fixed overhead but has a maximum block size of 128K, so it needs a
|
|
# larger margin.
|
|
#
|
|
# extra_bytes = (uncompressed_size >> 8) + 131072
|
|
|
|
#define ZO_z_extra_bytes ((ZO_z_output_len >> 8) + 131072)
|
|
#if ZO_z_output_len > ZO_z_input_len
|
|
# define ZO_z_extract_offset (ZO_z_output_len + ZO_z_extra_bytes - \
|
|
ZO_z_input_len)
|
|
#else
|
|
# define ZO_z_extract_offset ZO_z_extra_bytes
|
|
#endif
|
|
|
|
/*
|
|
* The extract_offset has to be bigger than ZO head section. Otherwise when
|
|
* the head code is running to move ZO to the end of the buffer, it will
|
|
* overwrite the head code itself.
|
|
*/
|
|
#if (ZO__ehead - ZO_startup_32) > ZO_z_extract_offset
|
|
# define ZO_z_min_extract_offset ((ZO__ehead - ZO_startup_32 + 4095) & ~4095)
|
|
#else
|
|
# define ZO_z_min_extract_offset ((ZO_z_extract_offset + 4095) & ~4095)
|
|
#endif
|
|
|
|
#define ZO_INIT_SIZE (ZO__end - ZO_startup_32 + ZO_z_min_extract_offset)
|
|
|
|
#define VO_INIT_SIZE (VO__end - VO__text)
|
|
#if ZO_INIT_SIZE > VO_INIT_SIZE
|
|
# define INIT_SIZE ZO_INIT_SIZE
|
|
#else
|
|
# define INIT_SIZE VO_INIT_SIZE
|
|
#endif
|
|
|
|
init_size: .long INIT_SIZE # kernel initialization size
|
|
handover_offset: .long 0 # Filled in by build.c
|
|
kernel_info_offset: .long 0 # Filled in by build.c
|
|
|
|
# End of setup header #####################################################
|
|
|
|
.section ".entrytext", "ax"
|
|
start_of_setup:
|
|
# Force %es = %ds
|
|
movw %ds, %ax
|
|
movw %ax, %es
|
|
cld
|
|
|
|
# Apparently some ancient versions of LILO invoked the kernel with %ss != %ds,
|
|
# which happened to work by accident for the old code. Recalculate the stack
|
|
# pointer if %ss is invalid. Otherwise leave it alone, LOADLIN sets up the
|
|
# stack behind its own code, so we can't blindly put it directly past the heap.
|
|
|
|
movw %ss, %dx
|
|
cmpw %ax, %dx # %ds == %ss?
|
|
movw %sp, %dx
|
|
je 2f # -> assume %sp is reasonably set
|
|
|
|
# Invalid %ss, make up a new stack
|
|
movw $_end, %dx
|
|
testb $CAN_USE_HEAP, loadflags
|
|
jz 1f
|
|
movw heap_end_ptr, %dx
|
|
1: addw $STACK_SIZE, %dx
|
|
jnc 2f
|
|
xorw %dx, %dx # Prevent wraparound
|
|
|
|
2: # Now %dx should point to the end of our stack space
|
|
andw $~3, %dx # dword align (might as well...)
|
|
jnz 3f
|
|
movw $0xfffc, %dx # Make sure we're not zero
|
|
3: movw %ax, %ss
|
|
movzwl %dx, %esp # Clear upper half of %esp
|
|
sti # Now we should have a working stack
|
|
|
|
# We will have entered with %cs = %ds+0x20, normalize %cs so
|
|
# it is on par with the other segments.
|
|
pushw %ds
|
|
pushw $6f
|
|
lretw
|
|
6:
|
|
|
|
# Check signature at end of setup
|
|
cmpl $0x5a5aaa55, setup_sig
|
|
jne setup_bad
|
|
|
|
# Zero the bss
|
|
movw $__bss_start, %di
|
|
movw $_end+3, %cx
|
|
xorl %eax, %eax
|
|
subw %di, %cx
|
|
shrw $2, %cx
|
|
rep; stosl
|
|
|
|
# Jump to C code (should not return)
|
|
calll main
|
|
|
|
# Setup corrupt somehow...
|
|
setup_bad:
|
|
movl $setup_corrupt, %eax
|
|
calll puts
|
|
# Fall through...
|
|
|
|
.globl die
|
|
.type die, @function
|
|
die:
|
|
hlt
|
|
jmp die
|
|
|
|
.size die, .-die
|
|
|
|
.section ".initdata", "a"
|
|
setup_corrupt:
|
|
.byte 7
|
|
.string "No setup signature found...\n"
|