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1/* SPDX-License-Identifier: GPL-2.0 */
2/*
3 * header.S
4 *
5 * Copyright (C) 1991, 1992 Linus Torvalds
6 *
7 * Based on bootsect.S and setup.S
8 * modified by more people than can be counted
9 *
10 * Rewritten as a common file by H. Peter Anvin (Apr 2007)
11 *
12 * BIG FAT NOTE: We're in real mode using 64k segments. Therefore segment
13 * addresses must be multiplied by 16 to obtain their respective linear
14 * addresses. To avoid confusion, linear addresses are written using leading
15 * hex while segment addresses are written as segment:offset.
16 *
17 */
18#include <linux/pe.h>
19#include <asm/segment.h>
20#include <asm/boot.h>
21#include <asm/page_types.h>
22#include <asm/setup.h>
23#include <asm/bootparam.h>
24#include "boot.h"
25#include "voffset.h"
26#include "zoffset.h"
27
28BOOTSEG = 0x07C0 /* original address of boot-sector */
29SYSSEG = 0x1000 /* historical load address >> 4 */
30
31#ifndef SVGA_MODE
32#define SVGA_MODE ASK_VGA
33#endif
34
35#ifndef ROOT_RDONLY
36#define ROOT_RDONLY 1
37#endif
38
39 .set salign, 0x1000
40 .set falign, 0x200
41
42 .code16
43 .section ".bstext", "ax"
44#ifdef CONFIG_EFI_STUB
45 # "MZ", MS-DOS header
46 .word MZ_MAGIC
47 .org 0x38
48 #
49 # Offset to the PE header.
50 #
51 .long LINUX_PE_MAGIC
52 .long pe_header
53pe_header:
54 .long PE_MAGIC
55
56coff_header:
57#ifdef CONFIG_X86_32
58 .set image_file_add_flags, IMAGE_FILE_32BIT_MACHINE
59 .set pe_opt_magic, PE_OPT_MAGIC_PE32
60 .word IMAGE_FILE_MACHINE_I386
61#else
62 .set image_file_add_flags, 0
63 .set pe_opt_magic, PE_OPT_MAGIC_PE32PLUS
64 .word IMAGE_FILE_MACHINE_AMD64
65#endif
66 .word section_count # nr_sections
67 .long 0 # TimeDateStamp
68 .long 0 # PointerToSymbolTable
69 .long 1 # NumberOfSymbols
70 .word section_table - optional_header # SizeOfOptionalHeader
71 .word IMAGE_FILE_EXECUTABLE_IMAGE | \
72 image_file_add_flags | \
73 IMAGE_FILE_DEBUG_STRIPPED | \
74 IMAGE_FILE_LINE_NUMS_STRIPPED # Characteristics
75
76optional_header:
77 .word pe_opt_magic
78 .byte 0x02 # MajorLinkerVersion
79 .byte 0x14 # MinorLinkerVersion
80
81 .long ZO__data # SizeOfCode
82
83 .long ZO__end - ZO__data # SizeOfInitializedData
84 .long 0 # SizeOfUninitializedData
85
86 .long setup_size + ZO_efi_pe_entry # AddressOfEntryPoint
87
88 .long setup_size # BaseOfCode
89#ifdef CONFIG_X86_32
90 .long 0 # data
91#endif
92
93extra_header_fields:
94#ifdef CONFIG_X86_32
95 .long 0 # ImageBase
96#else
97 .quad 0 # ImageBase
98#endif
99 .long salign # SectionAlignment
100 .long falign # FileAlignment
101 .word 0 # MajorOperatingSystemVersion
102 .word 0 # MinorOperatingSystemVersion
103 .word LINUX_EFISTUB_MAJOR_VERSION # MajorImageVersion
104 .word LINUX_EFISTUB_MINOR_VERSION # MinorImageVersion
105 .word 0 # MajorSubsystemVersion
106 .word 0 # MinorSubsystemVersion
107 .long 0 # Win32VersionValue
108
109 .long setup_size + ZO__end # SizeOfImage
110
111 .long salign # SizeOfHeaders
112 .long 0 # CheckSum
113 .word IMAGE_SUBSYSTEM_EFI_APPLICATION # Subsystem (EFI application)
114 .word IMAGE_DLL_CHARACTERISTICS_NX_COMPAT # DllCharacteristics
115#ifdef CONFIG_X86_32
116 .long 0 # SizeOfStackReserve
117 .long 0 # SizeOfStackCommit
118 .long 0 # SizeOfHeapReserve
119 .long 0 # SizeOfHeapCommit
120#else
121 .quad 0 # SizeOfStackReserve
122 .quad 0 # SizeOfStackCommit
123 .quad 0 # SizeOfHeapReserve
124 .quad 0 # SizeOfHeapCommit
125#endif
126 .long 0 # LoaderFlags
127 .long (section_table - .) / 8 # NumberOfRvaAndSizes
128
129 .quad 0 # ExportTable
130 .quad 0 # ImportTable
131 .quad 0 # ResourceTable
132 .quad 0 # ExceptionTable
133 .quad 0 # CertificationTable
134 .quad 0 # BaseRelocationTable
135
136 # Section table
137section_table:
138 .ascii ".setup"
139 .byte 0
140 .byte 0
141 .long pecompat_fstart - salign # VirtualSize
142 .long salign # VirtualAddress
143 .long pecompat_fstart - salign # SizeOfRawData
144 .long salign # PointerToRawData
145
146 .long 0, 0, 0
147 .long IMAGE_SCN_CNT_INITIALIZED_DATA | \
148 IMAGE_SCN_MEM_READ | \
149 IMAGE_SCN_MEM_DISCARDABLE # Characteristics
150
151#ifdef CONFIG_EFI_MIXED
152 .asciz ".compat"
153
154 .long pecompat_fsize # VirtualSize
155 .long pecompat_fstart # VirtualAddress
156 .long pecompat_fsize # SizeOfRawData
157 .long pecompat_fstart # PointerToRawData
158
159 .long 0, 0, 0
160 .long IMAGE_SCN_CNT_INITIALIZED_DATA | \
161 IMAGE_SCN_MEM_READ | \
162 IMAGE_SCN_MEM_DISCARDABLE # Characteristics
163
164 /*
165 * Put the IA-32 machine type and the associated entry point address in
166 * the .compat section, so loaders can figure out which other execution
167 * modes this image supports.
168 */
169 .pushsection ".pecompat", "a", @progbits
170 .balign salign
171 .globl pecompat_fstart
172pecompat_fstart:
173 .byte 0x1 # Version
174 .byte 8 # Size
175 .word IMAGE_FILE_MACHINE_I386 # PE machine type
176 .long setup_size + ZO_efi32_pe_entry # Entrypoint
177 .byte 0x0 # Sentinel
178 .popsection
179#else
180 .set pecompat_fstart, setup_size
181#endif
182 .ascii ".text"
183 .byte 0
184 .byte 0
185 .byte 0
186 .long ZO__data
187 .long setup_size
188 .long ZO__data # Size of initialized data
189 # on disk
190 .long setup_size
191 .long 0 # PointerToRelocations
192 .long 0 # PointerToLineNumbers
193 .word 0 # NumberOfRelocations
194 .word 0 # NumberOfLineNumbers
195 .long IMAGE_SCN_CNT_CODE | \
196 IMAGE_SCN_MEM_READ | \
197 IMAGE_SCN_MEM_EXECUTE # Characteristics
198
199 .ascii ".data\0\0\0"
200 .long ZO__end - ZO__data # VirtualSize
201 .long setup_size + ZO__data # VirtualAddress
202 .long ZO__edata - ZO__data # SizeOfRawData
203 .long setup_size + ZO__data # PointerToRawData
204
205 .long 0, 0, 0
206 .long IMAGE_SCN_CNT_INITIALIZED_DATA | \
207 IMAGE_SCN_MEM_READ | \
208 IMAGE_SCN_MEM_WRITE # Characteristics
209
210 .set section_count, (. - section_table) / 40
211#endif /* CONFIG_EFI_STUB */
212
213 # Kernel attributes; used by setup. This is part 1 of the
214 # header, from the old boot sector.
215
216 .section ".header", "a"
217 .globl sentinel
218sentinel: .byte 0xff, 0xff /* Used to detect broken loaders */
219
220 .globl hdr
221hdr:
222 .byte setup_sects - 1
223root_flags: .word ROOT_RDONLY
224syssize: .long ZO__edata / 16
225ram_size: .word 0 /* Obsolete */
226vid_mode: .word SVGA_MODE
227root_dev: .word 0 /* Default to major/minor 0/0 */
228boot_flag: .word 0xAA55
229
230 # offset 512, entry point
231
232 .globl _start
233_start:
234 # Explicitly enter this as bytes, or the assembler
235 # tries to generate a 3-byte jump here, which causes
236 # everything else to push off to the wrong offset.
237 .byte 0xeb # short (2-byte) jump
238 .byte start_of_setup-1f
2391:
240
241 # Part 2 of the header, from the old setup.S
242
243 .ascii "HdrS" # header signature
244 .word 0x020f # header version number (>= 0x0105)
245 # or else old loadlin-1.5 will fail)
246 .globl realmode_swtch
247realmode_swtch: .word 0, 0 # default_switch, SETUPSEG
248start_sys_seg: .word SYSSEG # obsolete and meaningless, but just
249 # in case something decided to "use" it
250 .word kernel_version-512 # pointing to kernel version string
251 # above section of header is compatible
252 # with loadlin-1.5 (header v1.5). Don't
253 # change it.
254
255type_of_loader: .byte 0 # 0 means ancient bootloader, newer
256 # bootloaders know to change this.
257 # See Documentation/arch/x86/boot.rst for
258 # assigned ids
259
260# flags, unused bits must be zero (RFU) bit within loadflags
261loadflags:
262 .byte LOADED_HIGH # The kernel is to be loaded high
263
264setup_move_size: .word 0x8000 # size to move, when setup is not
265 # loaded at 0x90000. We will move setup
266 # to 0x90000 then just before jumping
267 # into the kernel. However, only the
268 # loader knows how much data behind
269 # us also needs to be loaded.
270
271code32_start: # here loaders can put a different
272 # start address for 32-bit code.
273 .long 0x100000 # 0x100000 = default for big kernel
274
275ramdisk_image: .long 0 # address of loaded ramdisk image
276 # Here the loader puts the 32-bit
277 # address where it loaded the image.
278 # This only will be read by the kernel.
279
280ramdisk_size: .long 0 # its size in bytes
281
282bootsect_kludge:
283 .long 0 # obsolete
284
285heap_end_ptr: .word _end+STACK_SIZE-512
286 # (Header version 0x0201 or later)
287 # space from here (exclusive) down to
288 # end of setup code can be used by setup
289 # for local heap purposes.
290
291ext_loader_ver:
292 .byte 0 # Extended boot loader version
293ext_loader_type:
294 .byte 0 # Extended boot loader type
295
296cmd_line_ptr: .long 0 # (Header version 0x0202 or later)
297 # If nonzero, a 32-bit pointer
298 # to the kernel command line.
299 # The command line should be
300 # located between the start of
301 # setup and the end of low
302 # memory (0xa0000), or it may
303 # get overwritten before it
304 # gets read. If this field is
305 # used, there is no longer
306 # anything magical about the
307 # 0x90000 segment; the setup
308 # can be located anywhere in
309 # low memory 0x10000 or higher.
310
311initrd_addr_max: .long 0x7fffffff
312 # (Header version 0x0203 or later)
313 # The highest safe address for
314 # the contents of an initrd
315 # The current kernel allows up to 4 GB,
316 # but leave it at 2 GB to avoid
317 # possible bootloader bugs.
318
319kernel_alignment: .long CONFIG_PHYSICAL_ALIGN #physical addr alignment
320 #required for protected mode
321 #kernel
322#ifdef CONFIG_RELOCATABLE
323relocatable_kernel: .byte 1
324#else
325relocatable_kernel: .byte 0
326#endif
327min_alignment: .byte MIN_KERNEL_ALIGN_LG2 # minimum alignment
328
329xloadflags:
330#ifdef CONFIG_X86_64
331# define XLF0 XLF_KERNEL_64 /* 64-bit kernel */
332#else
333# define XLF0 0
334#endif
335
336#if defined(CONFIG_RELOCATABLE) && defined(CONFIG_X86_64)
337 /* kernel/boot_param/ramdisk could be loaded above 4g */
338# define XLF1 XLF_CAN_BE_LOADED_ABOVE_4G
339#else
340# define XLF1 0
341#endif
342
343#ifdef CONFIG_EFI_HANDOVER_PROTOCOL
344# ifdef CONFIG_EFI_MIXED
345# define XLF23 (XLF_EFI_HANDOVER_32|XLF_EFI_HANDOVER_64)
346# else
347# ifdef CONFIG_X86_64
348# define XLF23 XLF_EFI_HANDOVER_64 /* 64-bit EFI handover ok */
349# else
350# define XLF23 XLF_EFI_HANDOVER_32 /* 32-bit EFI handover ok */
351# endif
352# endif
353#else
354# define XLF23 0
355#endif
356
357#if defined(CONFIG_X86_64) && defined(CONFIG_EFI) && defined(CONFIG_KEXEC_CORE)
358# define XLF4 XLF_EFI_KEXEC
359#else
360# define XLF4 0
361#endif
362
363#ifdef CONFIG_X86_64
364#ifdef CONFIG_X86_5LEVEL
365#define XLF56 (XLF_5LEVEL|XLF_5LEVEL_ENABLED)
366#else
367#define XLF56 XLF_5LEVEL
368#endif
369#else
370#define XLF56 0
371#endif
372
373 .word XLF0 | XLF1 | XLF23 | XLF4 | XLF56
374
375cmdline_size: .long COMMAND_LINE_SIZE-1 #length of the command line,
376 #added with boot protocol
377 #version 2.06
378
379hardware_subarch: .long 0 # subarchitecture, added with 2.07
380 # default to 0 for normal x86 PC
381
382hardware_subarch_data: .quad 0
383
384payload_offset: .long ZO_input_data
385payload_length: .long ZO_z_input_len
386
387setup_data: .quad 0 # 64-bit physical pointer to
388 # single linked list of
389 # struct setup_data
390
391pref_address: .quad LOAD_PHYSICAL_ADDR # preferred load addr
392
393#
394# Getting to provably safe in-place decompression is hard. Worst case
395# behaviours need to be analyzed. Here let's take the decompression of
396# a gzip-compressed kernel as example, to illustrate it:
397#
398# The file layout of gzip compressed kernel is:
399#
400# magic[2]
401# method[1]
402# flags[1]
403# timestamp[4]
404# extraflags[1]
405# os[1]
406# compressed data blocks[N]
407# crc[4] orig_len[4]
408#
409# ... resulting in +18 bytes overhead of uncompressed data.
410#
411# (For more information, please refer to RFC 1951 and RFC 1952.)
412#
413# Files divided into blocks
414# 1 bit (last block flag)
415# 2 bits (block type)
416#
417# 1 block occurs every 32K -1 bytes or when there 50% compression
418# has been achieved. The smallest block type encoding is always used.
419#
420# stored:
421# 32 bits length in bytes.
422#
423# fixed:
424# magic fixed tree.
425# symbols.
426#
427# dynamic:
428# dynamic tree encoding.
429# symbols.
430#
431#
432# The buffer for decompression in place is the length of the uncompressed
433# data, plus a small amount extra to keep the algorithm safe. The
434# compressed data is placed at the end of the buffer. The output pointer
435# is placed at the start of the buffer and the input pointer is placed
436# where the compressed data starts. Problems will occur when the output
437# pointer overruns the input pointer.
438#
439# The output pointer can only overrun the input pointer if the input
440# pointer is moving faster than the output pointer. A condition only
441# triggered by data whose compressed form is larger than the uncompressed
442# form.
443#
444# The worst case at the block level is a growth of the compressed data
445# of 5 bytes per 32767 bytes.
446#
447# The worst case internal to a compressed block is very hard to figure.
448# The worst case can at least be bounded by having one bit that represents
449# 32764 bytes and then all of the rest of the bytes representing the very
450# very last byte.
451#
452# All of which is enough to compute an amount of extra data that is required
453# to be safe. To avoid problems at the block level allocating 5 extra bytes
454# per 32767 bytes of data is sufficient. To avoid problems internal to a
455# block adding an extra 32767 bytes (the worst case uncompressed block size)
456# is sufficient, to ensure that in the worst case the decompressed data for
457# block will stop the byte before the compressed data for a block begins.
458# To avoid problems with the compressed data's meta information an extra 18
459# bytes are needed. Leading to the formula:
460#
461# extra_bytes = (uncompressed_size >> 12) + 32768 + 18
462#
463# Adding 8 bytes per 32K is a bit excessive but much easier to calculate.
464# Adding 32768 instead of 32767 just makes for round numbers.
465#
466# Above analysis is for decompressing gzip compressed kernel only. Up to
467# now 6 different decompressor are supported all together. And among them
468# xz stores data in chunks and has maximum chunk of 64K. Hence safety
469# margin should be updated to cover all decompressors so that we don't
470# need to deal with each of them separately. Please check
471# the description in lib/decompressor_xxx.c for specific information.
472#
473# extra_bytes = (uncompressed_size >> 12) + 65536 + 128
474#
475# LZ4 is even worse: data that cannot be further compressed grows by 0.4%,
476# or one byte per 256 bytes. OTOH, we can safely get rid of the +128 as
477# the size-dependent part now grows so fast.
478#
479# extra_bytes = (uncompressed_size >> 8) + 65536
480#
481# ZSTD compressed data grows by at most 3 bytes per 128K, and only has a 22
482# byte fixed overhead but has a maximum block size of 128K, so it needs a
483# larger margin.
484#
485# extra_bytes = (uncompressed_size >> 8) + 131072
486
487#define ZO_z_extra_bytes ((ZO_z_output_len >> 8) + 131072)
488#if ZO_z_output_len > ZO_z_input_len
489# define ZO_z_extract_offset (ZO_z_output_len + ZO_z_extra_bytes - \
490 ZO_z_input_len)
491#else
492# define ZO_z_extract_offset ZO_z_extra_bytes
493#endif
494
495/*
496 * The extract_offset has to be bigger than ZO head section. Otherwise when
497 * the head code is running to move ZO to the end of the buffer, it will
498 * overwrite the head code itself.
499 */
500#if (ZO__ehead - ZO_startup_32) > ZO_z_extract_offset
501# define ZO_z_min_extract_offset ((ZO__ehead - ZO_startup_32 + 4095) & ~4095)
502#else
503# define ZO_z_min_extract_offset ((ZO_z_extract_offset + 4095) & ~4095)
504#endif
505
506#define ZO_INIT_SIZE (ZO__end - ZO_startup_32 + ZO_z_min_extract_offset)
507
508#define VO_INIT_SIZE (VO__end - VO__text)
509#if ZO_INIT_SIZE > VO_INIT_SIZE
510# define INIT_SIZE ZO_INIT_SIZE
511#else
512# define INIT_SIZE VO_INIT_SIZE
513#endif
514
515 .macro __handover_offset
516#ifndef CONFIG_EFI_HANDOVER_PROTOCOL
517 .long 0
518#elif !defined(CONFIG_X86_64)
519 .long ZO_efi32_stub_entry
520#else
521 /* Yes, this is really how we defined it :( */
522 .long ZO_efi64_stub_entry - 0x200
523#ifdef CONFIG_EFI_MIXED
524 .if ZO_efi32_stub_entry != ZO_efi64_stub_entry - 0x200
525 .error "32-bit and 64-bit EFI entry points do not match"
526 .endif
527#endif
528#endif
529 .endm
530
531init_size: .long INIT_SIZE # kernel initialization size
532handover_offset: __handover_offset
533kernel_info_offset: .long ZO_kernel_info
534
535# End of setup header #####################################################
536
537 .section ".entrytext", "ax"
538start_of_setup:
539# Force %es = %ds
540 movw %ds, %ax
541 movw %ax, %es
542 cld
543
544# Apparently some ancient versions of LILO invoked the kernel with %ss != %ds,
545# which happened to work by accident for the old code. Recalculate the stack
546# pointer if %ss is invalid. Otherwise leave it alone, LOADLIN sets up the
547# stack behind its own code, so we can't blindly put it directly past the heap.
548
549 movw %ss, %dx
550 cmpw %ax, %dx # %ds == %ss?
551 movw %sp, %dx
552 je 2f # -> assume %sp is reasonably set
553
554 # Invalid %ss, make up a new stack
555 movw $_end, %dx
556 testb $CAN_USE_HEAP, loadflags
557 jz 1f
558 movw heap_end_ptr, %dx
5591: addw $STACK_SIZE, %dx
560 jnc 2f
561 xorw %dx, %dx # Prevent wraparound
562
5632: # Now %dx should point to the end of our stack space
564 andw $~3, %dx # dword align (might as well...)
565 jnz 3f
566 movw $0xfffc, %dx # Make sure we're not zero
5673: movw %ax, %ss
568 movzwl %dx, %esp # Clear upper half of %esp
569 sti # Now we should have a working stack
570
571# We will have entered with %cs = %ds+0x20, normalize %cs so
572# it is on par with the other segments.
573 pushw %ds
574 pushw $6f
575 lretw
5766:
577
578# Check signature at end of setup
579 cmpl $0x5a5aaa55, setup_sig
580 jne setup_bad
581
582# Zero the bss
583 movw $__bss_start, %di
584 movw $_end+3, %cx
585 xorl %eax, %eax
586 subw %di, %cx
587 shrw $2, %cx
588 rep; stosl
589
590# Jump to C code (should not return)
591 calll main
592
593# Setup corrupt somehow...
594setup_bad:
595 movl $setup_corrupt, %eax
596 calll puts
597 # Fall through...
598
599 .globl die
600 .type die, @function
601die:
602 hlt
603 jmp die
604
605 .size die, .-die
606
607 .section ".initdata", "a"
608setup_corrupt:
609 .byte 7
610 .string "No setup signature found...\n"
1/* SPDX-License-Identifier: GPL-2.0 */
2/*
3 * header.S
4 *
5 * Copyright (C) 1991, 1992 Linus Torvalds
6 *
7 * Based on bootsect.S and setup.S
8 * modified by more people than can be counted
9 *
10 * Rewritten as a common file by H. Peter Anvin (Apr 2007)
11 *
12 * BIG FAT NOTE: We're in real mode using 64k segments. Therefore segment
13 * addresses must be multiplied by 16 to obtain their respective linear
14 * addresses. To avoid confusion, linear addresses are written using leading
15 * hex while segment addresses are written as segment:offset.
16 *
17 */
18#include <linux/pe.h>
19#include <asm/segment.h>
20#include <asm/boot.h>
21#include <asm/page_types.h>
22#include <asm/setup.h>
23#include <asm/bootparam.h>
24#include "boot.h"
25#include "voffset.h"
26#include "zoffset.h"
27
28BOOTSEG = 0x07C0 /* original address of boot-sector */
29SYSSEG = 0x1000 /* historical load address >> 4 */
30
31#ifndef SVGA_MODE
32#define SVGA_MODE ASK_VGA
33#endif
34
35#ifndef ROOT_RDONLY
36#define ROOT_RDONLY 1
37#endif
38
39 .set salign, 0x1000
40 .set falign, 0x200
41
42 .code16
43 .section ".bstext", "ax"
44#ifdef CONFIG_EFI_STUB
45 # "MZ", MS-DOS header
46 .word MZ_MAGIC
47 .org 0x38
48 #
49 # Offset to the PE header.
50 #
51 .long LINUX_PE_MAGIC
52 .long pe_header
53pe_header:
54 .long PE_MAGIC
55
56coff_header:
57#ifdef CONFIG_X86_32
58 .set image_file_add_flags, IMAGE_FILE_32BIT_MACHINE
59 .set pe_opt_magic, PE_OPT_MAGIC_PE32
60 .word IMAGE_FILE_MACHINE_I386
61#else
62 .set image_file_add_flags, 0
63 .set pe_opt_magic, PE_OPT_MAGIC_PE32PLUS
64 .word IMAGE_FILE_MACHINE_AMD64
65#endif
66 .word section_count # nr_sections
67 .long 0 # TimeDateStamp
68 .long 0 # PointerToSymbolTable
69 .long 1 # NumberOfSymbols
70 .word section_table - optional_header # SizeOfOptionalHeader
71 .word IMAGE_FILE_EXECUTABLE_IMAGE | \
72 image_file_add_flags | \
73 IMAGE_FILE_DEBUG_STRIPPED | \
74 IMAGE_FILE_LINE_NUMS_STRIPPED # Characteristics
75
76optional_header:
77 .word pe_opt_magic
78 .byte 0x02 # MajorLinkerVersion
79 .byte 0x14 # MinorLinkerVersion
80
81 .long ZO__data # SizeOfCode
82
83 .long ZO__end - ZO__data # SizeOfInitializedData
84 .long 0 # SizeOfUninitializedData
85
86 .long setup_size + ZO_efi_pe_entry # AddressOfEntryPoint
87
88 .long setup_size # BaseOfCode
89#ifdef CONFIG_X86_32
90 .long 0 # data
91#endif
92
93extra_header_fields:
94#ifdef CONFIG_X86_32
95 .long 0 # ImageBase
96#else
97 .quad 0 # ImageBase
98#endif
99 .long salign # SectionAlignment
100 .long falign # FileAlignment
101 .word 0 # MajorOperatingSystemVersion
102 .word 0 # MinorOperatingSystemVersion
103 .word LINUX_EFISTUB_MAJOR_VERSION # MajorImageVersion
104 .word LINUX_EFISTUB_MINOR_VERSION # MinorImageVersion
105 .word 0 # MajorSubsystemVersion
106 .word 0 # MinorSubsystemVersion
107 .long 0 # Win32VersionValue
108
109 .long setup_size + ZO__end # SizeOfImage
110
111 .long salign # SizeOfHeaders
112 .long 0 # CheckSum
113 .word IMAGE_SUBSYSTEM_EFI_APPLICATION # Subsystem (EFI application)
114#ifdef CONFIG_EFI_DXE_MEM_ATTRIBUTES
115 .word IMAGE_DLL_CHARACTERISTICS_NX_COMPAT # DllCharacteristics
116#else
117 .word 0 # DllCharacteristics
118#endif
119#ifdef CONFIG_X86_32
120 .long 0 # SizeOfStackReserve
121 .long 0 # SizeOfStackCommit
122 .long 0 # SizeOfHeapReserve
123 .long 0 # SizeOfHeapCommit
124#else
125 .quad 0 # SizeOfStackReserve
126 .quad 0 # SizeOfStackCommit
127 .quad 0 # SizeOfHeapReserve
128 .quad 0 # SizeOfHeapCommit
129#endif
130 .long 0 # LoaderFlags
131 .long (section_table - .) / 8 # NumberOfRvaAndSizes
132
133 .quad 0 # ExportTable
134 .quad 0 # ImportTable
135 .quad 0 # ResourceTable
136 .quad 0 # ExceptionTable
137 .quad 0 # CertificationTable
138 .quad 0 # BaseRelocationTable
139
140 # Section table
141section_table:
142 .ascii ".setup"
143 .byte 0
144 .byte 0
145 .long pecompat_fstart - salign # VirtualSize
146 .long salign # VirtualAddress
147 .long pecompat_fstart - salign # SizeOfRawData
148 .long salign # PointerToRawData
149
150 .long 0, 0, 0
151 .long IMAGE_SCN_CNT_INITIALIZED_DATA | \
152 IMAGE_SCN_MEM_READ | \
153 IMAGE_SCN_MEM_DISCARDABLE # Characteristics
154
155#ifdef CONFIG_EFI_MIXED
156 .asciz ".compat"
157
158 .long pecompat_fsize # VirtualSize
159 .long pecompat_fstart # VirtualAddress
160 .long pecompat_fsize # SizeOfRawData
161 .long pecompat_fstart # PointerToRawData
162
163 .long 0, 0, 0
164 .long IMAGE_SCN_CNT_INITIALIZED_DATA | \
165 IMAGE_SCN_MEM_READ | \
166 IMAGE_SCN_MEM_DISCARDABLE # Characteristics
167
168 /*
169 * Put the IA-32 machine type and the associated entry point address in
170 * the .compat section, so loaders can figure out which other execution
171 * modes this image supports.
172 */
173 .pushsection ".pecompat", "a", @progbits
174 .balign salign
175 .globl pecompat_fstart
176pecompat_fstart:
177 .byte 0x1 # Version
178 .byte 8 # Size
179 .word IMAGE_FILE_MACHINE_I386 # PE machine type
180 .long setup_size + ZO_efi32_pe_entry # Entrypoint
181 .byte 0x0 # Sentinel
182 .popsection
183#else
184 .set pecompat_fstart, setup_size
185#endif
186 .ascii ".text"
187 .byte 0
188 .byte 0
189 .byte 0
190 .long ZO__data
191 .long setup_size
192 .long ZO__data # Size of initialized data
193 # on disk
194 .long setup_size
195 .long 0 # PointerToRelocations
196 .long 0 # PointerToLineNumbers
197 .word 0 # NumberOfRelocations
198 .word 0 # NumberOfLineNumbers
199 .long IMAGE_SCN_CNT_CODE | \
200 IMAGE_SCN_MEM_READ | \
201 IMAGE_SCN_MEM_EXECUTE # Characteristics
202
203 .ascii ".data\0\0\0"
204 .long ZO__end - ZO__data # VirtualSize
205 .long setup_size + ZO__data # VirtualAddress
206 .long ZO__edata - ZO__data # SizeOfRawData
207 .long setup_size + ZO__data # PointerToRawData
208
209 .long 0, 0, 0
210 .long IMAGE_SCN_CNT_INITIALIZED_DATA | \
211 IMAGE_SCN_MEM_READ | \
212 IMAGE_SCN_MEM_WRITE # Characteristics
213
214 .set section_count, (. - section_table) / 40
215#endif /* CONFIG_EFI_STUB */
216
217 # Kernel attributes; used by setup. This is part 1 of the
218 # header, from the old boot sector.
219
220 .section ".header", "a"
221 .globl sentinel
222sentinel: .byte 0xff, 0xff /* Used to detect broken loaders */
223
224 .globl hdr
225hdr:
226 .byte setup_sects - 1
227root_flags: .word ROOT_RDONLY
228syssize: .long ZO__edata / 16
229ram_size: .word 0 /* Obsolete */
230vid_mode: .word SVGA_MODE
231root_dev: .word 0 /* Default to major/minor 0/0 */
232boot_flag: .word 0xAA55
233
234 # offset 512, entry point
235
236 .globl _start
237_start:
238 # Explicitly enter this as bytes, or the assembler
239 # tries to generate a 3-byte jump here, which causes
240 # everything else to push off to the wrong offset.
241 .byte 0xeb # short (2-byte) jump
242 .byte start_of_setup-1f
2431:
244
245 # Part 2 of the header, from the old setup.S
246
247 .ascii "HdrS" # header signature
248 .word 0x020f # header version number (>= 0x0105)
249 # or else old loadlin-1.5 will fail)
250 .globl realmode_swtch
251realmode_swtch: .word 0, 0 # default_switch, SETUPSEG
252start_sys_seg: .word SYSSEG # obsolete and meaningless, but just
253 # in case something decided to "use" it
254 .word kernel_version-512 # pointing to kernel version string
255 # above section of header is compatible
256 # with loadlin-1.5 (header v1.5). Don't
257 # change it.
258
259type_of_loader: .byte 0 # 0 means ancient bootloader, newer
260 # bootloaders know to change this.
261 # See Documentation/arch/x86/boot.rst for
262 # assigned ids
263
264# flags, unused bits must be zero (RFU) bit within loadflags
265loadflags:
266 .byte LOADED_HIGH # The kernel is to be loaded high
267
268setup_move_size: .word 0x8000 # size to move, when setup is not
269 # loaded at 0x90000. We will move setup
270 # to 0x90000 then just before jumping
271 # into the kernel. However, only the
272 # loader knows how much data behind
273 # us also needs to be loaded.
274
275code32_start: # here loaders can put a different
276 # start address for 32-bit code.
277 .long 0x100000 # 0x100000 = default for big kernel
278
279ramdisk_image: .long 0 # address of loaded ramdisk image
280 # Here the loader puts the 32-bit
281 # address where it loaded the image.
282 # This only will be read by the kernel.
283
284ramdisk_size: .long 0 # its size in bytes
285
286bootsect_kludge:
287 .long 0 # obsolete
288
289heap_end_ptr: .word _end+STACK_SIZE-512
290 # (Header version 0x0201 or later)
291 # space from here (exclusive) down to
292 # end of setup code can be used by setup
293 # for local heap purposes.
294
295ext_loader_ver:
296 .byte 0 # Extended boot loader version
297ext_loader_type:
298 .byte 0 # Extended boot loader type
299
300cmd_line_ptr: .long 0 # (Header version 0x0202 or later)
301 # If nonzero, a 32-bit pointer
302 # to the kernel command line.
303 # The command line should be
304 # located between the start of
305 # setup and the end of low
306 # memory (0xa0000), or it may
307 # get overwritten before it
308 # gets read. If this field is
309 # used, there is no longer
310 # anything magical about the
311 # 0x90000 segment; the setup
312 # can be located anywhere in
313 # low memory 0x10000 or higher.
314
315initrd_addr_max: .long 0x7fffffff
316 # (Header version 0x0203 or later)
317 # The highest safe address for
318 # the contents of an initrd
319 # The current kernel allows up to 4 GB,
320 # but leave it at 2 GB to avoid
321 # possible bootloader bugs.
322
323kernel_alignment: .long CONFIG_PHYSICAL_ALIGN #physical addr alignment
324 #required for protected mode
325 #kernel
326#ifdef CONFIG_RELOCATABLE
327relocatable_kernel: .byte 1
328#else
329relocatable_kernel: .byte 0
330#endif
331min_alignment: .byte MIN_KERNEL_ALIGN_LG2 # minimum alignment
332
333xloadflags:
334#ifdef CONFIG_X86_64
335# define XLF0 XLF_KERNEL_64 /* 64-bit kernel */
336#else
337# define XLF0 0
338#endif
339
340#if defined(CONFIG_RELOCATABLE) && defined(CONFIG_X86_64)
341 /* kernel/boot_param/ramdisk could be loaded above 4g */
342# define XLF1 XLF_CAN_BE_LOADED_ABOVE_4G
343#else
344# define XLF1 0
345#endif
346
347#ifdef CONFIG_EFI_HANDOVER_PROTOCOL
348# ifdef CONFIG_EFI_MIXED
349# define XLF23 (XLF_EFI_HANDOVER_32|XLF_EFI_HANDOVER_64)
350# else
351# ifdef CONFIG_X86_64
352# define XLF23 XLF_EFI_HANDOVER_64 /* 64-bit EFI handover ok */
353# else
354# define XLF23 XLF_EFI_HANDOVER_32 /* 32-bit EFI handover ok */
355# endif
356# endif
357#else
358# define XLF23 0
359#endif
360
361#if defined(CONFIG_X86_64) && defined(CONFIG_EFI) && defined(CONFIG_KEXEC_CORE)
362# define XLF4 XLF_EFI_KEXEC
363#else
364# define XLF4 0
365#endif
366
367#ifdef CONFIG_X86_64
368#ifdef CONFIG_X86_5LEVEL
369#define XLF56 (XLF_5LEVEL|XLF_5LEVEL_ENABLED)
370#else
371#define XLF56 XLF_5LEVEL
372#endif
373#else
374#define XLF56 0
375#endif
376
377 .word XLF0 | XLF1 | XLF23 | XLF4 | XLF56
378
379cmdline_size: .long COMMAND_LINE_SIZE-1 #length of the command line,
380 #added with boot protocol
381 #version 2.06
382
383hardware_subarch: .long 0 # subarchitecture, added with 2.07
384 # default to 0 for normal x86 PC
385
386hardware_subarch_data: .quad 0
387
388payload_offset: .long ZO_input_data
389payload_length: .long ZO_z_input_len
390
391setup_data: .quad 0 # 64-bit physical pointer to
392 # single linked list of
393 # struct setup_data
394
395pref_address: .quad LOAD_PHYSICAL_ADDR # preferred load addr
396
397#
398# Getting to provably safe in-place decompression is hard. Worst case
399# behaviours need to be analyzed. Here let's take the decompression of
400# a gzip-compressed kernel as example, to illustrate it:
401#
402# The file layout of gzip compressed kernel is:
403#
404# magic[2]
405# method[1]
406# flags[1]
407# timestamp[4]
408# extraflags[1]
409# os[1]
410# compressed data blocks[N]
411# crc[4] orig_len[4]
412#
413# ... resulting in +18 bytes overhead of uncompressed data.
414#
415# (For more information, please refer to RFC 1951 and RFC 1952.)
416#
417# Files divided into blocks
418# 1 bit (last block flag)
419# 2 bits (block type)
420#
421# 1 block occurs every 32K -1 bytes or when there 50% compression
422# has been achieved. The smallest block type encoding is always used.
423#
424# stored:
425# 32 bits length in bytes.
426#
427# fixed:
428# magic fixed tree.
429# symbols.
430#
431# dynamic:
432# dynamic tree encoding.
433# symbols.
434#
435#
436# The buffer for decompression in place is the length of the uncompressed
437# data, plus a small amount extra to keep the algorithm safe. The
438# compressed data is placed at the end of the buffer. The output pointer
439# is placed at the start of the buffer and the input pointer is placed
440# where the compressed data starts. Problems will occur when the output
441# pointer overruns the input pointer.
442#
443# The output pointer can only overrun the input pointer if the input
444# pointer is moving faster than the output pointer. A condition only
445# triggered by data whose compressed form is larger than the uncompressed
446# form.
447#
448# The worst case at the block level is a growth of the compressed data
449# of 5 bytes per 32767 bytes.
450#
451# The worst case internal to a compressed block is very hard to figure.
452# The worst case can at least be bounded by having one bit that represents
453# 32764 bytes and then all of the rest of the bytes representing the very
454# very last byte.
455#
456# All of which is enough to compute an amount of extra data that is required
457# to be safe. To avoid problems at the block level allocating 5 extra bytes
458# per 32767 bytes of data is sufficient. To avoid problems internal to a
459# block adding an extra 32767 bytes (the worst case uncompressed block size)
460# is sufficient, to ensure that in the worst case the decompressed data for
461# block will stop the byte before the compressed data for a block begins.
462# To avoid problems with the compressed data's meta information an extra 18
463# bytes are needed. Leading to the formula:
464#
465# extra_bytes = (uncompressed_size >> 12) + 32768 + 18
466#
467# Adding 8 bytes per 32K is a bit excessive but much easier to calculate.
468# Adding 32768 instead of 32767 just makes for round numbers.
469#
470# Above analysis is for decompressing gzip compressed kernel only. Up to
471# now 6 different decompressor are supported all together. And among them
472# xz stores data in chunks and has maximum chunk of 64K. Hence safety
473# margin should be updated to cover all decompressors so that we don't
474# need to deal with each of them separately. Please check
475# the description in lib/decompressor_xxx.c for specific information.
476#
477# extra_bytes = (uncompressed_size >> 12) + 65536 + 128
478#
479# LZ4 is even worse: data that cannot be further compressed grows by 0.4%,
480# or one byte per 256 bytes. OTOH, we can safely get rid of the +128 as
481# the size-dependent part now grows so fast.
482#
483# extra_bytes = (uncompressed_size >> 8) + 65536
484#
485# ZSTD compressed data grows by at most 3 bytes per 128K, and only has a 22
486# byte fixed overhead but has a maximum block size of 128K, so it needs a
487# larger margin.
488#
489# extra_bytes = (uncompressed_size >> 8) + 131072
490
491#define ZO_z_extra_bytes ((ZO_z_output_len >> 8) + 131072)
492#if ZO_z_output_len > ZO_z_input_len
493# define ZO_z_extract_offset (ZO_z_output_len + ZO_z_extra_bytes - \
494 ZO_z_input_len)
495#else
496# define ZO_z_extract_offset ZO_z_extra_bytes
497#endif
498
499/*
500 * The extract_offset has to be bigger than ZO head section. Otherwise when
501 * the head code is running to move ZO to the end of the buffer, it will
502 * overwrite the head code itself.
503 */
504#if (ZO__ehead - ZO_startup_32) > ZO_z_extract_offset
505# define ZO_z_min_extract_offset ((ZO__ehead - ZO_startup_32 + 4095) & ~4095)
506#else
507# define ZO_z_min_extract_offset ((ZO_z_extract_offset + 4095) & ~4095)
508#endif
509
510#define ZO_INIT_SIZE (ZO__end - ZO_startup_32 + ZO_z_min_extract_offset)
511
512#define VO_INIT_SIZE (VO__end - VO__text)
513#if ZO_INIT_SIZE > VO_INIT_SIZE
514# define INIT_SIZE ZO_INIT_SIZE
515#else
516# define INIT_SIZE VO_INIT_SIZE
517#endif
518
519 .macro __handover_offset
520#ifndef CONFIG_EFI_HANDOVER_PROTOCOL
521 .long 0
522#elif !defined(CONFIG_X86_64)
523 .long ZO_efi32_stub_entry
524#else
525 /* Yes, this is really how we defined it :( */
526 .long ZO_efi64_stub_entry - 0x200
527#ifdef CONFIG_EFI_MIXED
528 .if ZO_efi32_stub_entry != ZO_efi64_stub_entry - 0x200
529 .error "32-bit and 64-bit EFI entry points do not match"
530 .endif
531#endif
532#endif
533 .endm
534
535init_size: .long INIT_SIZE # kernel initialization size
536handover_offset: __handover_offset
537kernel_info_offset: .long ZO_kernel_info
538
539# End of setup header #####################################################
540
541 .section ".entrytext", "ax"
542start_of_setup:
543# Force %es = %ds
544 movw %ds, %ax
545 movw %ax, %es
546 cld
547
548# Apparently some ancient versions of LILO invoked the kernel with %ss != %ds,
549# which happened to work by accident for the old code. Recalculate the stack
550# pointer if %ss is invalid. Otherwise leave it alone, LOADLIN sets up the
551# stack behind its own code, so we can't blindly put it directly past the heap.
552
553 movw %ss, %dx
554 cmpw %ax, %dx # %ds == %ss?
555 movw %sp, %dx
556 je 2f # -> assume %sp is reasonably set
557
558 # Invalid %ss, make up a new stack
559 movw $_end, %dx
560 testb $CAN_USE_HEAP, loadflags
561 jz 1f
562 movw heap_end_ptr, %dx
5631: addw $STACK_SIZE, %dx
564 jnc 2f
565 xorw %dx, %dx # Prevent wraparound
566
5672: # Now %dx should point to the end of our stack space
568 andw $~3, %dx # dword align (might as well...)
569 jnz 3f
570 movw $0xfffc, %dx # Make sure we're not zero
5713: movw %ax, %ss
572 movzwl %dx, %esp # Clear upper half of %esp
573 sti # Now we should have a working stack
574
575# We will have entered with %cs = %ds+0x20, normalize %cs so
576# it is on par with the other segments.
577 pushw %ds
578 pushw $6f
579 lretw
5806:
581
582# Check signature at end of setup
583 cmpl $0x5a5aaa55, setup_sig
584 jne setup_bad
585
586# Zero the bss
587 movw $__bss_start, %di
588 movw $_end+3, %cx
589 xorl %eax, %eax
590 subw %di, %cx
591 shrw $2, %cx
592 rep; stosl
593
594# Jump to C code (should not return)
595 calll main
596
597# Setup corrupt somehow...
598setup_bad:
599 movl $setup_corrupt, %eax
600 calll puts
601 # Fall through...
602
603 .globl die
604 .type die, @function
605die:
606 hlt
607 jmp die
608
609 .size die, .-die
610
611 .section ".initdata", "a"
612setup_corrupt:
613 .byte 7
614 .string "No setup signature found...\n"