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1/*
2 * header.S
3 *
4 * Copyright (C) 1991, 1992 Linus Torvalds
5 *
6 * Based on bootsect.S and setup.S
7 * modified by more people than can be counted
8 *
9 * Rewritten as a common file by H. Peter Anvin (Apr 2007)
10 *
11 * BIG FAT NOTE: We're in real mode using 64k segments. Therefore segment
12 * addresses must be multiplied by 16 to obtain their respective linear
13 * addresses. To avoid confusion, linear addresses are written using leading
14 * hex while segment addresses are written as segment:offset.
15 *
16 */
17
18#include <asm/segment.h>
19#include <generated/utsrelease.h>
20#include <asm/boot.h>
21#include <asm/e820.h>
22#include <asm/page_types.h>
23#include <asm/setup.h>
24#include <asm/bootparam.h>
25#include "boot.h"
26#include "voffset.h"
27#include "zoffset.h"
28
29BOOTSEG = 0x07C0 /* original address of boot-sector */
30SYSSEG = 0x1000 /* historical load address >> 4 */
31
32#ifndef SVGA_MODE
33#define SVGA_MODE ASK_VGA
34#endif
35
36#ifndef ROOT_RDONLY
37#define ROOT_RDONLY 1
38#endif
39
40 .code16
41 .section ".bstext", "ax"
42
43 .global bootsect_start
44bootsect_start:
45#ifdef CONFIG_EFI_STUB
46 # "MZ", MS-DOS header
47 .byte 0x4d
48 .byte 0x5a
49#endif
50
51 # Normalize the start address
52 ljmp $BOOTSEG, $start2
53
54start2:
55 movw %cs, %ax
56 movw %ax, %ds
57 movw %ax, %es
58 movw %ax, %ss
59 xorw %sp, %sp
60 sti
61 cld
62
63 movw $bugger_off_msg, %si
64
65msg_loop:
66 lodsb
67 andb %al, %al
68 jz bs_die
69 movb $0xe, %ah
70 movw $7, %bx
71 int $0x10
72 jmp msg_loop
73
74bs_die:
75 # Allow the user to press a key, then reboot
76 xorw %ax, %ax
77 int $0x16
78 int $0x19
79
80 # int 0x19 should never return. In case it does anyway,
81 # invoke the BIOS reset code...
82 ljmp $0xf000,$0xfff0
83
84#ifdef CONFIG_EFI_STUB
85 .org 0x3c
86 #
87 # Offset to the PE header.
88 #
89 .long pe_header
90#endif /* CONFIG_EFI_STUB */
91
92 .section ".bsdata", "a"
93bugger_off_msg:
94 .ascii "Direct floppy boot is not supported. "
95 .ascii "Use a boot loader program instead.\r\n"
96 .ascii "\n"
97 .ascii "Remove disk and press any key to reboot ...\r\n"
98 .byte 0
99
100#ifdef CONFIG_EFI_STUB
101pe_header:
102 .ascii "PE"
103 .word 0
104
105coff_header:
106#ifdef CONFIG_X86_32
107 .word 0x14c # i386
108#else
109 .word 0x8664 # x86-64
110#endif
111 .word 3 # nr_sections
112 .long 0 # TimeDateStamp
113 .long 0 # PointerToSymbolTable
114 .long 1 # NumberOfSymbols
115 .word section_table - optional_header # SizeOfOptionalHeader
116#ifdef CONFIG_X86_32
117 .word 0x306 # Characteristics.
118 # IMAGE_FILE_32BIT_MACHINE |
119 # IMAGE_FILE_DEBUG_STRIPPED |
120 # IMAGE_FILE_EXECUTABLE_IMAGE |
121 # IMAGE_FILE_LINE_NUMS_STRIPPED
122#else
123 .word 0x206 # Characteristics
124 # IMAGE_FILE_DEBUG_STRIPPED |
125 # IMAGE_FILE_EXECUTABLE_IMAGE |
126 # IMAGE_FILE_LINE_NUMS_STRIPPED
127#endif
128
129optional_header:
130#ifdef CONFIG_X86_32
131 .word 0x10b # PE32 format
132#else
133 .word 0x20b # PE32+ format
134#endif
135 .byte 0x02 # MajorLinkerVersion
136 .byte 0x14 # MinorLinkerVersion
137
138 # Filled in by build.c
139 .long 0 # SizeOfCode
140
141 .long 0 # SizeOfInitializedData
142 .long 0 # SizeOfUninitializedData
143
144 # Filled in by build.c
145 .long 0x0000 # AddressOfEntryPoint
146
147 .long 0x0200 # BaseOfCode
148#ifdef CONFIG_X86_32
149 .long 0 # data
150#endif
151
152extra_header_fields:
153#ifdef CONFIG_X86_32
154 .long 0 # ImageBase
155#else
156 .quad 0 # ImageBase
157#endif
158 .long 0x20 # SectionAlignment
159 .long 0x20 # FileAlignment
160 .word 0 # MajorOperatingSystemVersion
161 .word 0 # MinorOperatingSystemVersion
162 .word 0 # MajorImageVersion
163 .word 0 # MinorImageVersion
164 .word 0 # MajorSubsystemVersion
165 .word 0 # MinorSubsystemVersion
166 .long 0 # Win32VersionValue
167
168 #
169 # The size of the bzImage is written in tools/build.c
170 #
171 .long 0 # SizeOfImage
172
173 .long 0x200 # SizeOfHeaders
174 .long 0 # CheckSum
175 .word 0xa # Subsystem (EFI application)
176 .word 0 # DllCharacteristics
177#ifdef CONFIG_X86_32
178 .long 0 # SizeOfStackReserve
179 .long 0 # SizeOfStackCommit
180 .long 0 # SizeOfHeapReserve
181 .long 0 # SizeOfHeapCommit
182#else
183 .quad 0 # SizeOfStackReserve
184 .quad 0 # SizeOfStackCommit
185 .quad 0 # SizeOfHeapReserve
186 .quad 0 # SizeOfHeapCommit
187#endif
188 .long 0 # LoaderFlags
189 .long 0x6 # NumberOfRvaAndSizes
190
191 .quad 0 # ExportTable
192 .quad 0 # ImportTable
193 .quad 0 # ResourceTable
194 .quad 0 # ExceptionTable
195 .quad 0 # CertificationTable
196 .quad 0 # BaseRelocationTable
197
198 # Section table
199section_table:
200 #
201 # The offset & size fields are filled in by build.c.
202 #
203 .ascii ".setup"
204 .byte 0
205 .byte 0
206 .long 0
207 .long 0x0 # startup_{32,64}
208 .long 0 # Size of initialized data
209 # on disk
210 .long 0x0 # startup_{32,64}
211 .long 0 # PointerToRelocations
212 .long 0 # PointerToLineNumbers
213 .word 0 # NumberOfRelocations
214 .word 0 # NumberOfLineNumbers
215 .long 0x60500020 # Characteristics (section flags)
216
217 #
218 # The EFI application loader requires a relocation section
219 # because EFI applications must be relocatable. The .reloc
220 # offset & size fields are filled in by build.c.
221 #
222 .ascii ".reloc"
223 .byte 0
224 .byte 0
225 .long 0
226 .long 0
227 .long 0 # SizeOfRawData
228 .long 0 # PointerToRawData
229 .long 0 # PointerToRelocations
230 .long 0 # PointerToLineNumbers
231 .word 0 # NumberOfRelocations
232 .word 0 # NumberOfLineNumbers
233 .long 0x42100040 # Characteristics (section flags)
234
235 #
236 # The offset & size fields are filled in by build.c.
237 #
238 .ascii ".text"
239 .byte 0
240 .byte 0
241 .byte 0
242 .long 0
243 .long 0x0 # startup_{32,64}
244 .long 0 # Size of initialized data
245 # on disk
246 .long 0x0 # startup_{32,64}
247 .long 0 # PointerToRelocations
248 .long 0 # PointerToLineNumbers
249 .word 0 # NumberOfRelocations
250 .word 0 # NumberOfLineNumbers
251 .long 0x60500020 # Characteristics (section flags)
252
253#endif /* CONFIG_EFI_STUB */
254
255 # Kernel attributes; used by setup. This is part 1 of the
256 # header, from the old boot sector.
257
258 .section ".header", "a"
259 .globl sentinel
260sentinel: .byte 0xff, 0xff /* Used to detect broken loaders */
261
262 .globl hdr
263hdr:
264setup_sects: .byte 0 /* Filled in by build.c */
265root_flags: .word ROOT_RDONLY
266syssize: .long 0 /* Filled in by build.c */
267ram_size: .word 0 /* Obsolete */
268vid_mode: .word SVGA_MODE
269root_dev: .word 0 /* Filled in by build.c */
270boot_flag: .word 0xAA55
271
272 # offset 512, entry point
273
274 .globl _start
275_start:
276 # Explicitly enter this as bytes, or the assembler
277 # tries to generate a 3-byte jump here, which causes
278 # everything else to push off to the wrong offset.
279 .byte 0xeb # short (2-byte) jump
280 .byte start_of_setup-1f
2811:
282
283 # Part 2 of the header, from the old setup.S
284
285 .ascii "HdrS" # header signature
286 .word 0x020d # header version number (>= 0x0105)
287 # or else old loadlin-1.5 will fail)
288 .globl realmode_swtch
289realmode_swtch: .word 0, 0 # default_switch, SETUPSEG
290start_sys_seg: .word SYSSEG # obsolete and meaningless, but just
291 # in case something decided to "use" it
292 .word kernel_version-512 # pointing to kernel version string
293 # above section of header is compatible
294 # with loadlin-1.5 (header v1.5). Don't
295 # change it.
296
297type_of_loader: .byte 0 # 0 means ancient bootloader, newer
298 # bootloaders know to change this.
299 # See Documentation/x86/boot.txt for
300 # assigned ids
301
302# flags, unused bits must be zero (RFU) bit within loadflags
303loadflags:
304 .byte LOADED_HIGH # The kernel is to be loaded high
305
306setup_move_size: .word 0x8000 # size to move, when setup is not
307 # loaded at 0x90000. We will move setup
308 # to 0x90000 then just before jumping
309 # into the kernel. However, only the
310 # loader knows how much data behind
311 # us also needs to be loaded.
312
313code32_start: # here loaders can put a different
314 # start address for 32-bit code.
315 .long 0x100000 # 0x100000 = default for big kernel
316
317ramdisk_image: .long 0 # address of loaded ramdisk image
318 # Here the loader puts the 32-bit
319 # address where it loaded the image.
320 # This only will be read by the kernel.
321
322ramdisk_size: .long 0 # its size in bytes
323
324bootsect_kludge:
325 .long 0 # obsolete
326
327heap_end_ptr: .word _end+STACK_SIZE-512
328 # (Header version 0x0201 or later)
329 # space from here (exclusive) down to
330 # end of setup code can be used by setup
331 # for local heap purposes.
332
333ext_loader_ver:
334 .byte 0 # Extended boot loader version
335ext_loader_type:
336 .byte 0 # Extended boot loader type
337
338cmd_line_ptr: .long 0 # (Header version 0x0202 or later)
339 # If nonzero, a 32-bit pointer
340 # to the kernel command line.
341 # The command line should be
342 # located between the start of
343 # setup and the end of low
344 # memory (0xa0000), or it may
345 # get overwritten before it
346 # gets read. If this field is
347 # used, there is no longer
348 # anything magical about the
349 # 0x90000 segment; the setup
350 # can be located anywhere in
351 # low memory 0x10000 or higher.
352
353initrd_addr_max: .long 0x7fffffff
354 # (Header version 0x0203 or later)
355 # The highest safe address for
356 # the contents of an initrd
357 # The current kernel allows up to 4 GB,
358 # but leave it at 2 GB to avoid
359 # possible bootloader bugs.
360
361kernel_alignment: .long CONFIG_PHYSICAL_ALIGN #physical addr alignment
362 #required for protected mode
363 #kernel
364#ifdef CONFIG_RELOCATABLE
365relocatable_kernel: .byte 1
366#else
367relocatable_kernel: .byte 0
368#endif
369min_alignment: .byte MIN_KERNEL_ALIGN_LG2 # minimum alignment
370
371xloadflags:
372#ifdef CONFIG_X86_64
373# define XLF0 XLF_KERNEL_64 /* 64-bit kernel */
374#else
375# define XLF0 0
376#endif
377
378#if defined(CONFIG_RELOCATABLE) && defined(CONFIG_X86_64)
379 /* kernel/boot_param/ramdisk could be loaded above 4g */
380# define XLF1 XLF_CAN_BE_LOADED_ABOVE_4G
381#else
382# define XLF1 0
383#endif
384
385#ifdef CONFIG_EFI_STUB
386# ifdef CONFIG_EFI_MIXED
387# define XLF23 (XLF_EFI_HANDOVER_32|XLF_EFI_HANDOVER_64)
388# else
389# ifdef CONFIG_X86_64
390# define XLF23 XLF_EFI_HANDOVER_64 /* 64-bit EFI handover ok */
391# else
392# define XLF23 XLF_EFI_HANDOVER_32 /* 32-bit EFI handover ok */
393# endif
394# endif
395#else
396# define XLF23 0
397#endif
398
399#if defined(CONFIG_X86_64) && defined(CONFIG_EFI) && defined(CONFIG_KEXEC)
400# define XLF4 XLF_EFI_KEXEC
401#else
402# define XLF4 0
403#endif
404
405 .word XLF0 | XLF1 | XLF23 | XLF4
406
407cmdline_size: .long COMMAND_LINE_SIZE-1 #length of the command line,
408 #added with boot protocol
409 #version 2.06
410
411hardware_subarch: .long 0 # subarchitecture, added with 2.07
412 # default to 0 for normal x86 PC
413
414hardware_subarch_data: .quad 0
415
416payload_offset: .long ZO_input_data
417payload_length: .long ZO_z_input_len
418
419setup_data: .quad 0 # 64-bit physical pointer to
420 # single linked list of
421 # struct setup_data
422
423pref_address: .quad LOAD_PHYSICAL_ADDR # preferred load addr
424
425#define ZO_INIT_SIZE (ZO__end - ZO_startup_32 + ZO_z_extract_offset)
426#define VO_INIT_SIZE (VO__end - VO__text)
427#if ZO_INIT_SIZE > VO_INIT_SIZE
428#define INIT_SIZE ZO_INIT_SIZE
429#else
430#define INIT_SIZE VO_INIT_SIZE
431#endif
432init_size: .long INIT_SIZE # kernel initialization size
433handover_offset: .long 0 # Filled in by build.c
434
435# End of setup header #####################################################
436
437 .section ".entrytext", "ax"
438start_of_setup:
439# Force %es = %ds
440 movw %ds, %ax
441 movw %ax, %es
442 cld
443
444# Apparently some ancient versions of LILO invoked the kernel with %ss != %ds,
445# which happened to work by accident for the old code. Recalculate the stack
446# pointer if %ss is invalid. Otherwise leave it alone, LOADLIN sets up the
447# stack behind its own code, so we can't blindly put it directly past the heap.
448
449 movw %ss, %dx
450 cmpw %ax, %dx # %ds == %ss?
451 movw %sp, %dx
452 je 2f # -> assume %sp is reasonably set
453
454 # Invalid %ss, make up a new stack
455 movw $_end, %dx
456 testb $CAN_USE_HEAP, loadflags
457 jz 1f
458 movw heap_end_ptr, %dx
4591: addw $STACK_SIZE, %dx
460 jnc 2f
461 xorw %dx, %dx # Prevent wraparound
462
4632: # Now %dx should point to the end of our stack space
464 andw $~3, %dx # dword align (might as well...)
465 jnz 3f
466 movw $0xfffc, %dx # Make sure we're not zero
4673: movw %ax, %ss
468 movzwl %dx, %esp # Clear upper half of %esp
469 sti # Now we should have a working stack
470
471# We will have entered with %cs = %ds+0x20, normalize %cs so
472# it is on par with the other segments.
473 pushw %ds
474 pushw $6f
475 lretw
4766:
477
478# Check signature at end of setup
479 cmpl $0x5a5aaa55, setup_sig
480 jne setup_bad
481
482# Zero the bss
483 movw $__bss_start, %di
484 movw $_end+3, %cx
485 xorl %eax, %eax
486 subw %di, %cx
487 shrw $2, %cx
488 rep; stosl
489
490# Jump to C code (should not return)
491 calll main
492
493# Setup corrupt somehow...
494setup_bad:
495 movl $setup_corrupt, %eax
496 calll puts
497 # Fall through...
498
499 .globl die
500 .type die, @function
501die:
502 hlt
503 jmp die
504
505 .size die, .-die
506
507 .section ".initdata", "a"
508setup_corrupt:
509 .byte 7
510 .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 .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"