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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 "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 RAMDISK
36#define RAMDISK 0
37#endif
38
39#ifndef ROOT_RDONLY
40#define ROOT_RDONLY 1
41#endif
42
43 .code16
44 .section ".bstext", "ax"
45
46 .global bootsect_start
47bootsect_start:
48#ifdef CONFIG_EFI_STUB
49 # "MZ", MS-DOS header
50 .byte 0x4d
51 .byte 0x5a
52#endif
53
54 # Normalize the start address
55 ljmp $BOOTSEG, $start2
56
57start2:
58 movw %cs, %ax
59 movw %ax, %ds
60 movw %ax, %es
61 movw %ax, %ss
62 xorw %sp, %sp
63 sti
64 cld
65
66 movw $bugger_off_msg, %si
67
68msg_loop:
69 lodsb
70 andb %al, %al
71 jz bs_die
72 movb $0xe, %ah
73 movw $7, %bx
74 int $0x10
75 jmp msg_loop
76
77bs_die:
78 # Allow the user to press a key, then reboot
79 xorw %ax, %ax
80 int $0x16
81 int $0x19
82
83 # int 0x19 should never return. In case it does anyway,
84 # invoke the BIOS reset code...
85 ljmp $0xf000,$0xfff0
86
87#ifdef CONFIG_EFI_STUB
88 .org 0x3c
89 #
90 # Offset to the PE header.
91 #
92 .long pe_header
93#endif /* CONFIG_EFI_STUB */
94
95 .section ".bsdata", "a"
96bugger_off_msg:
97 .ascii "Direct floppy boot is not supported. "
98 .ascii "Use a boot loader program instead.\r\n"
99 .ascii "\n"
100 .ascii "Remove disk and press any key to reboot ...\r\n"
101 .byte 0
102
103#ifdef CONFIG_EFI_STUB
104pe_header:
105 .ascii "PE"
106 .word 0
107
108coff_header:
109#ifdef CONFIG_X86_32
110 .word 0x14c # i386
111#else
112 .word 0x8664 # x86-64
113#endif
114 .word 3 # nr_sections
115 .long 0 # TimeDateStamp
116 .long 0 # PointerToSymbolTable
117 .long 1 # NumberOfSymbols
118 .word section_table - optional_header # SizeOfOptionalHeader
119#ifdef CONFIG_X86_32
120 .word 0x306 # Characteristics.
121 # IMAGE_FILE_32BIT_MACHINE |
122 # IMAGE_FILE_DEBUG_STRIPPED |
123 # IMAGE_FILE_EXECUTABLE_IMAGE |
124 # IMAGE_FILE_LINE_NUMS_STRIPPED
125#else
126 .word 0x206 # Characteristics
127 # IMAGE_FILE_DEBUG_STRIPPED |
128 # IMAGE_FILE_EXECUTABLE_IMAGE |
129 # IMAGE_FILE_LINE_NUMS_STRIPPED
130#endif
131
132optional_header:
133#ifdef CONFIG_X86_32
134 .word 0x10b # PE32 format
135#else
136 .word 0x20b # PE32+ format
137#endif
138 .byte 0x02 # MajorLinkerVersion
139 .byte 0x14 # MinorLinkerVersion
140
141 # Filled in by build.c
142 .long 0 # SizeOfCode
143
144 .long 0 # SizeOfInitializedData
145 .long 0 # SizeOfUninitializedData
146
147 # Filled in by build.c
148 .long 0x0000 # AddressOfEntryPoint
149
150 .long 0x0200 # BaseOfCode
151#ifdef CONFIG_X86_32
152 .long 0 # data
153#endif
154
155extra_header_fields:
156#ifdef CONFIG_X86_32
157 .long 0 # ImageBase
158#else
159 .quad 0 # ImageBase
160#endif
161 .long 0x20 # SectionAlignment
162 .long 0x20 # FileAlignment
163 .word 0 # MajorOperatingSystemVersion
164 .word 0 # MinorOperatingSystemVersion
165 .word 0 # MajorImageVersion
166 .word 0 # MinorImageVersion
167 .word 0 # MajorSubsystemVersion
168 .word 0 # MinorSubsystemVersion
169 .long 0 # Win32VersionValue
170
171 #
172 # The size of the bzImage is written in tools/build.c
173 #
174 .long 0 # SizeOfImage
175
176 .long 0x200 # SizeOfHeaders
177 .long 0 # CheckSum
178 .word 0xa # Subsystem (EFI application)
179 .word 0 # DllCharacteristics
180#ifdef CONFIG_X86_32
181 .long 0 # SizeOfStackReserve
182 .long 0 # SizeOfStackCommit
183 .long 0 # SizeOfHeapReserve
184 .long 0 # SizeOfHeapCommit
185#else
186 .quad 0 # SizeOfStackReserve
187 .quad 0 # SizeOfStackCommit
188 .quad 0 # SizeOfHeapReserve
189 .quad 0 # SizeOfHeapCommit
190#endif
191 .long 0 # LoaderFlags
192 .long 0x6 # NumberOfRvaAndSizes
193
194 .quad 0 # ExportTable
195 .quad 0 # ImportTable
196 .quad 0 # ResourceTable
197 .quad 0 # ExceptionTable
198 .quad 0 # CertificationTable
199 .quad 0 # BaseRelocationTable
200
201 # Section table
202section_table:
203 #
204 # The offset & size fields are filled in by build.c.
205 #
206 .ascii ".setup"
207 .byte 0
208 .byte 0
209 .long 0
210 .long 0x0 # startup_{32,64}
211 .long 0 # Size of initialized data
212 # on disk
213 .long 0x0 # startup_{32,64}
214 .long 0 # PointerToRelocations
215 .long 0 # PointerToLineNumbers
216 .word 0 # NumberOfRelocations
217 .word 0 # NumberOfLineNumbers
218 .long 0x60500020 # Characteristics (section flags)
219
220 #
221 # The EFI application loader requires a relocation section
222 # because EFI applications must be relocatable. The .reloc
223 # offset & size fields are filled in by build.c.
224 #
225 .ascii ".reloc"
226 .byte 0
227 .byte 0
228 .long 0
229 .long 0
230 .long 0 # SizeOfRawData
231 .long 0 # PointerToRawData
232 .long 0 # PointerToRelocations
233 .long 0 # PointerToLineNumbers
234 .word 0 # NumberOfRelocations
235 .word 0 # NumberOfLineNumbers
236 .long 0x42100040 # Characteristics (section flags)
237
238 #
239 # The offset & size fields are filled in by build.c.
240 #
241 .ascii ".text"
242 .byte 0
243 .byte 0
244 .byte 0
245 .long 0
246 .long 0x0 # startup_{32,64}
247 .long 0 # Size of initialized data
248 # on disk
249 .long 0x0 # startup_{32,64}
250 .long 0 # PointerToRelocations
251 .long 0 # PointerToLineNumbers
252 .word 0 # NumberOfRelocations
253 .word 0 # NumberOfLineNumbers
254 .long 0x60500020 # Characteristics (section flags)
255
256#endif /* CONFIG_EFI_STUB */
257
258 # Kernel attributes; used by setup. This is part 1 of the
259 # header, from the old boot sector.
260
261 .section ".header", "a"
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 0x020a # 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:
304LOADED_HIGH = 1 # If set, the kernel is loaded high
305CAN_USE_HEAP = 0x80 # If set, the loader also has set
306 # heap_end_ptr to tell how much
307 # space behind setup.S can be used for
308 # heap purposes.
309 # Only the loader knows what is free
310 .byte LOADED_HIGH
311
312setup_move_size: .word 0x8000 # size to move, when setup is not
313 # loaded at 0x90000. We will move setup
314 # to 0x90000 then just before jumping
315 # into the kernel. However, only the
316 # loader knows how much data behind
317 # us also needs to be loaded.
318
319code32_start: # here loaders can put a different
320 # start address for 32-bit code.
321 .long 0x100000 # 0x100000 = default for big kernel
322
323ramdisk_image: .long 0 # address of loaded ramdisk image
324 # Here the loader puts the 32-bit
325 # address where it loaded the image.
326 # This only will be read by the kernel.
327
328ramdisk_size: .long 0 # its size in bytes
329
330bootsect_kludge:
331 .long 0 # obsolete
332
333heap_end_ptr: .word _end+STACK_SIZE-512
334 # (Header version 0x0201 or later)
335 # space from here (exclusive) down to
336 # end of setup code can be used by setup
337 # for local heap purposes.
338
339ext_loader_ver:
340 .byte 0 # Extended boot loader version
341ext_loader_type:
342 .byte 0 # Extended boot loader type
343
344cmd_line_ptr: .long 0 # (Header version 0x0202 or later)
345 # If nonzero, a 32-bit pointer
346 # to the kernel command line.
347 # The command line should be
348 # located between the start of
349 # setup and the end of low
350 # memory (0xa0000), or it may
351 # get overwritten before it
352 # gets read. If this field is
353 # used, there is no longer
354 # anything magical about the
355 # 0x90000 segment; the setup
356 # can be located anywhere in
357 # low memory 0x10000 or higher.
358
359ramdisk_max: .long 0x7fffffff
360 # (Header version 0x0203 or later)
361 # The highest safe address for
362 # the contents of an initrd
363 # The current kernel allows up to 4 GB,
364 # but leave it at 2 GB to avoid
365 # possible bootloader bugs.
366
367kernel_alignment: .long CONFIG_PHYSICAL_ALIGN #physical addr alignment
368 #required for protected mode
369 #kernel
370#ifdef CONFIG_RELOCATABLE
371relocatable_kernel: .byte 1
372#else
373relocatable_kernel: .byte 0
374#endif
375min_alignment: .byte MIN_KERNEL_ALIGN_LG2 # minimum alignment
376pad3: .word 0
377
378cmdline_size: .long COMMAND_LINE_SIZE-1 #length of the command line,
379 #added with boot protocol
380 #version 2.06
381
382hardware_subarch: .long 0 # subarchitecture, added with 2.07
383 # default to 0 for normal x86 PC
384
385hardware_subarch_data: .quad 0
386
387payload_offset: .long ZO_input_data
388payload_length: .long ZO_z_input_len
389
390setup_data: .quad 0 # 64-bit physical pointer to
391 # single linked list of
392 # struct setup_data
393
394pref_address: .quad LOAD_PHYSICAL_ADDR # preferred load addr
395
396#define ZO_INIT_SIZE (ZO__end - ZO_startup_32 + ZO_z_extract_offset)
397#define VO_INIT_SIZE (VO__end - VO__text)
398#if ZO_INIT_SIZE > VO_INIT_SIZE
399#define INIT_SIZE ZO_INIT_SIZE
400#else
401#define INIT_SIZE VO_INIT_SIZE
402#endif
403init_size: .long INIT_SIZE # kernel initialization size
404
405# End of setup header #####################################################
406
407 .section ".entrytext", "ax"
408start_of_setup:
409#ifdef SAFE_RESET_DISK_CONTROLLER
410# Reset the disk controller.
411 movw $0x0000, %ax # Reset disk controller
412 movb $0x80, %dl # All disks
413 int $0x13
414#endif
415
416# Force %es = %ds
417 movw %ds, %ax
418 movw %ax, %es
419 cld
420
421# Apparently some ancient versions of LILO invoked the kernel with %ss != %ds,
422# which happened to work by accident for the old code. Recalculate the stack
423# pointer if %ss is invalid. Otherwise leave it alone, LOADLIN sets up the
424# stack behind its own code, so we can't blindly put it directly past the heap.
425
426 movw %ss, %dx
427 cmpw %ax, %dx # %ds == %ss?
428 movw %sp, %dx
429 je 2f # -> assume %sp is reasonably set
430
431 # Invalid %ss, make up a new stack
432 movw $_end, %dx
433 testb $CAN_USE_HEAP, loadflags
434 jz 1f
435 movw heap_end_ptr, %dx
4361: addw $STACK_SIZE, %dx
437 jnc 2f
438 xorw %dx, %dx # Prevent wraparound
439
4402: # Now %dx should point to the end of our stack space
441 andw $~3, %dx # dword align (might as well...)
442 jnz 3f
443 movw $0xfffc, %dx # Make sure we're not zero
4443: movw %ax, %ss
445 movzwl %dx, %esp # Clear upper half of %esp
446 sti # Now we should have a working stack
447
448# We will have entered with %cs = %ds+0x20, normalize %cs so
449# it is on par with the other segments.
450 pushw %ds
451 pushw $6f
452 lretw
4536:
454
455# Check signature at end of setup
456 cmpl $0x5a5aaa55, setup_sig
457 jne setup_bad
458
459# Zero the bss
460 movw $__bss_start, %di
461 movw $_end+3, %cx
462 xorl %eax, %eax
463 subw %di, %cx
464 shrw $2, %cx
465 rep; stosl
466
467# Jump to C code (should not return)
468 calll main
469
470# Setup corrupt somehow...
471setup_bad:
472 movl $setup_corrupt, %eax
473 calll puts
474 # Fall through...
475
476 .globl die
477 .type die, @function
478die:
479 hlt
480 jmp die
481
482 .size die, .-die
483
484 .section ".initdata", "a"
485setup_corrupt:
486 .byte 7
487 .string "No setup signature found...\n"
488
489 .data
490dummy: .long 0
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 .code16
40 .section ".bstext", "ax"
41
42 .global bootsect_start
43bootsect_start:
44#ifdef CONFIG_EFI_STUB
45 # "MZ", MS-DOS header
46 .word MZ_MAGIC
47#endif
48
49 # Normalize the start address
50 ljmp $BOOTSEG, $start2
51
52start2:
53 movw %cs, %ax
54 movw %ax, %ds
55 movw %ax, %es
56 movw %ax, %ss
57 xorw %sp, %sp
58 sti
59 cld
60
61 movw $bugger_off_msg, %si
62
63msg_loop:
64 lodsb
65 andb %al, %al
66 jz bs_die
67 movb $0xe, %ah
68 movw $7, %bx
69 int $0x10
70 jmp msg_loop
71
72bs_die:
73 # Allow the user to press a key, then reboot
74 xorw %ax, %ax
75 int $0x16
76 int $0x19
77
78 # int 0x19 should never return. In case it does anyway,
79 # invoke the BIOS reset code...
80 ljmp $0xf000,$0xfff0
81
82#ifdef CONFIG_EFI_STUB
83 .org 0x3c
84 #
85 # Offset to the PE header.
86 #
87 .long pe_header
88#endif /* CONFIG_EFI_STUB */
89
90 .section ".bsdata", "a"
91bugger_off_msg:
92 .ascii "Use a boot loader.\r\n"
93 .ascii "\n"
94 .ascii "Remove disk and press any key to reboot...\r\n"
95 .byte 0
96
97#ifdef CONFIG_EFI_STUB
98pe_header:
99 .long PE_MAGIC
100
101coff_header:
102#ifdef CONFIG_X86_32
103 .set image_file_add_flags, IMAGE_FILE_32BIT_MACHINE
104 .set pe_opt_magic, PE_OPT_MAGIC_PE32
105 .word IMAGE_FILE_MACHINE_I386
106#else
107 .set image_file_add_flags, 0
108 .set pe_opt_magic, PE_OPT_MAGIC_PE32PLUS
109 .word IMAGE_FILE_MACHINE_AMD64
110#endif
111 .word section_count # nr_sections
112 .long 0 # TimeDateStamp
113 .long 0 # PointerToSymbolTable
114 .long 1 # NumberOfSymbols
115 .word section_table - optional_header # SizeOfOptionalHeader
116 .word IMAGE_FILE_EXECUTABLE_IMAGE | \
117 image_file_add_flags | \
118 IMAGE_FILE_DEBUG_STRIPPED | \
119 IMAGE_FILE_LINE_NUMS_STRIPPED # Characteristics
120
121optional_header:
122 .word pe_opt_magic
123 .byte 0x02 # MajorLinkerVersion
124 .byte 0x14 # MinorLinkerVersion
125
126 # Filled in by build.c
127 .long 0 # SizeOfCode
128
129 .long 0 # SizeOfInitializedData
130 .long 0 # SizeOfUninitializedData
131
132 # Filled in by build.c
133 .long 0x0000 # AddressOfEntryPoint
134
135 .long 0x0200 # BaseOfCode
136#ifdef CONFIG_X86_32
137 .long 0 # data
138#endif
139
140extra_header_fields:
141 # PE specification requires ImageBase to be 64k aligned
142 .set image_base, (LOAD_PHYSICAL_ADDR + 0xffff) & ~0xffff
143#ifdef CONFIG_X86_32
144 .long image_base # ImageBase
145#else
146 .quad image_base # ImageBase
147#endif
148 .long 0x20 # SectionAlignment
149 .long 0x20 # FileAlignment
150 .word 0 # MajorOperatingSystemVersion
151 .word 0 # MinorOperatingSystemVersion
152 .word LINUX_EFISTUB_MAJOR_VERSION # MajorImageVersion
153 .word LINUX_EFISTUB_MINOR_VERSION # MinorImageVersion
154 .word 0 # MajorSubsystemVersion
155 .word 0 # MinorSubsystemVersion
156 .long 0 # Win32VersionValue
157
158 #
159 # The size of the bzImage is written in tools/build.c
160 #
161 .long 0 # SizeOfImage
162
163 .long 0x200 # SizeOfHeaders
164 .long 0 # CheckSum
165 .word IMAGE_SUBSYSTEM_EFI_APPLICATION # Subsystem (EFI application)
166 .word 0 # DllCharacteristics
167#ifdef CONFIG_X86_32
168 .long 0 # SizeOfStackReserve
169 .long 0 # SizeOfStackCommit
170 .long 0 # SizeOfHeapReserve
171 .long 0 # SizeOfHeapCommit
172#else
173 .quad 0 # SizeOfStackReserve
174 .quad 0 # SizeOfStackCommit
175 .quad 0 # SizeOfHeapReserve
176 .quad 0 # SizeOfHeapCommit
177#endif
178 .long 0 # LoaderFlags
179 .long (section_table - .) / 8 # NumberOfRvaAndSizes
180
181 .quad 0 # ExportTable
182 .quad 0 # ImportTable
183 .quad 0 # ResourceTable
184 .quad 0 # ExceptionTable
185 .quad 0 # CertificationTable
186 .quad 0 # BaseRelocationTable
187
188 # Section table
189section_table:
190 #
191 # The offset & size fields are filled in by build.c.
192 #
193 .ascii ".setup"
194 .byte 0
195 .byte 0
196 .long 0
197 .long 0x0 # startup_{32,64}
198 .long 0 # Size of initialized data
199 # on disk
200 .long 0x0 # startup_{32,64}
201 .long 0 # PointerToRelocations
202 .long 0 # PointerToLineNumbers
203 .word 0 # NumberOfRelocations
204 .word 0 # NumberOfLineNumbers
205 .long IMAGE_SCN_CNT_CODE | \
206 IMAGE_SCN_MEM_READ | \
207 IMAGE_SCN_MEM_EXECUTE | \
208 IMAGE_SCN_ALIGN_16BYTES # Characteristics
209
210 #
211 # The EFI application loader requires a relocation section
212 # because EFI applications must be relocatable. The .reloc
213 # offset & size fields are filled in by build.c.
214 #
215 .ascii ".reloc"
216 .byte 0
217 .byte 0
218 .long 0
219 .long 0
220 .long 0 # SizeOfRawData
221 .long 0 # PointerToRawData
222 .long 0 # PointerToRelocations
223 .long 0 # PointerToLineNumbers
224 .word 0 # NumberOfRelocations
225 .word 0 # NumberOfLineNumbers
226 .long IMAGE_SCN_CNT_INITIALIZED_DATA | \
227 IMAGE_SCN_MEM_READ | \
228 IMAGE_SCN_MEM_DISCARDABLE | \
229 IMAGE_SCN_ALIGN_1BYTES # Characteristics
230
231#ifdef CONFIG_EFI_MIXED
232 #
233 # The offset & size fields are filled in by build.c.
234 #
235 .asciz ".compat"
236 .long 0
237 .long 0x0
238 .long 0 # Size of initialized data
239 # on disk
240 .long 0x0
241 .long 0 # PointerToRelocations
242 .long 0 # PointerToLineNumbers
243 .word 0 # NumberOfRelocations
244 .word 0 # NumberOfLineNumbers
245 .long IMAGE_SCN_CNT_INITIALIZED_DATA | \
246 IMAGE_SCN_MEM_READ | \
247 IMAGE_SCN_MEM_DISCARDABLE | \
248 IMAGE_SCN_ALIGN_1BYTES # Characteristics
249#endif
250
251 #
252 # The offset & size fields are filled in by build.c.
253 #
254 .ascii ".text"
255 .byte 0
256 .byte 0
257 .byte 0
258 .long 0
259 .long 0x0 # startup_{32,64}
260 .long 0 # Size of initialized data
261 # on disk
262 .long 0x0 # startup_{32,64}
263 .long 0 # PointerToRelocations
264 .long 0 # PointerToLineNumbers
265 .word 0 # NumberOfRelocations
266 .word 0 # NumberOfLineNumbers
267 .long IMAGE_SCN_CNT_CODE | \
268 IMAGE_SCN_MEM_READ | \
269 IMAGE_SCN_MEM_EXECUTE | \
270 IMAGE_SCN_ALIGN_16BYTES # Characteristics
271
272 .set section_count, (. - section_table) / 40
273#endif /* CONFIG_EFI_STUB */
274
275 # Kernel attributes; used by setup. This is part 1 of the
276 # header, from the old boot sector.
277
278 .section ".header", "a"
279 .globl sentinel
280sentinel: .byte 0xff, 0xff /* Used to detect broken loaders */
281
282 .globl hdr
283hdr:
284setup_sects: .byte 0 /* Filled in by build.c */
285root_flags: .word ROOT_RDONLY
286syssize: .long 0 /* Filled in by build.c */
287ram_size: .word 0 /* Obsolete */
288vid_mode: .word SVGA_MODE
289root_dev: .word 0 /* Filled in by build.c */
290boot_flag: .word 0xAA55
291
292 # offset 512, entry point
293
294 .globl _start
295_start:
296 # Explicitly enter this as bytes, or the assembler
297 # tries to generate a 3-byte jump here, which causes
298 # everything else to push off to the wrong offset.
299 .byte 0xeb # short (2-byte) jump
300 .byte start_of_setup-1f
3011:
302
303 # Part 2 of the header, from the old setup.S
304
305 .ascii "HdrS" # header signature
306 .word 0x020f # header version number (>= 0x0105)
307 # or else old loadlin-1.5 will fail)
308 .globl realmode_swtch
309realmode_swtch: .word 0, 0 # default_switch, SETUPSEG
310start_sys_seg: .word SYSSEG # obsolete and meaningless, but just
311 # in case something decided to "use" it
312 .word kernel_version-512 # pointing to kernel version string
313 # above section of header is compatible
314 # with loadlin-1.5 (header v1.5). Don't
315 # change it.
316
317type_of_loader: .byte 0 # 0 means ancient bootloader, newer
318 # bootloaders know to change this.
319 # See Documentation/x86/boot.rst for
320 # assigned ids
321
322# flags, unused bits must be zero (RFU) bit within loadflags
323loadflags:
324 .byte LOADED_HIGH # The kernel is to be loaded high
325
326setup_move_size: .word 0x8000 # size to move, when setup is not
327 # loaded at 0x90000. We will move setup
328 # to 0x90000 then just before jumping
329 # into the kernel. However, only the
330 # loader knows how much data behind
331 # us also needs to be loaded.
332
333code32_start: # here loaders can put a different
334 # start address for 32-bit code.
335 .long 0x100000 # 0x100000 = default for big kernel
336
337ramdisk_image: .long 0 # address of loaded ramdisk image
338 # Here the loader puts the 32-bit
339 # address where it loaded the image.
340 # This only will be read by the kernel.
341
342ramdisk_size: .long 0 # its size in bytes
343
344bootsect_kludge:
345 .long 0 # obsolete
346
347heap_end_ptr: .word _end+STACK_SIZE-512
348 # (Header version 0x0201 or later)
349 # space from here (exclusive) down to
350 # end of setup code can be used by setup
351 # for local heap purposes.
352
353ext_loader_ver:
354 .byte 0 # Extended boot loader version
355ext_loader_type:
356 .byte 0 # Extended boot loader type
357
358cmd_line_ptr: .long 0 # (Header version 0x0202 or later)
359 # If nonzero, a 32-bit pointer
360 # to the kernel command line.
361 # The command line should be
362 # located between the start of
363 # setup and the end of low
364 # memory (0xa0000), or it may
365 # get overwritten before it
366 # gets read. If this field is
367 # used, there is no longer
368 # anything magical about the
369 # 0x90000 segment; the setup
370 # can be located anywhere in
371 # low memory 0x10000 or higher.
372
373initrd_addr_max: .long 0x7fffffff
374 # (Header version 0x0203 or later)
375 # The highest safe address for
376 # the contents of an initrd
377 # The current kernel allows up to 4 GB,
378 # but leave it at 2 GB to avoid
379 # possible bootloader bugs.
380
381kernel_alignment: .long CONFIG_PHYSICAL_ALIGN #physical addr alignment
382 #required for protected mode
383 #kernel
384#ifdef CONFIG_RELOCATABLE
385relocatable_kernel: .byte 1
386#else
387relocatable_kernel: .byte 0
388#endif
389min_alignment: .byte MIN_KERNEL_ALIGN_LG2 # minimum alignment
390
391xloadflags:
392#ifdef CONFIG_X86_64
393# define XLF0 XLF_KERNEL_64 /* 64-bit kernel */
394#else
395# define XLF0 0
396#endif
397
398#if defined(CONFIG_RELOCATABLE) && defined(CONFIG_X86_64)
399 /* kernel/boot_param/ramdisk could be loaded above 4g */
400# define XLF1 XLF_CAN_BE_LOADED_ABOVE_4G
401#else
402# define XLF1 0
403#endif
404
405#ifdef CONFIG_EFI_STUB
406# ifdef CONFIG_EFI_MIXED
407# define XLF23 (XLF_EFI_HANDOVER_32|XLF_EFI_HANDOVER_64)
408# else
409# ifdef CONFIG_X86_64
410# define XLF23 XLF_EFI_HANDOVER_64 /* 64-bit EFI handover ok */
411# else
412# define XLF23 XLF_EFI_HANDOVER_32 /* 32-bit EFI handover ok */
413# endif
414# endif
415#else
416# define XLF23 0
417#endif
418
419#if defined(CONFIG_X86_64) && defined(CONFIG_EFI) && defined(CONFIG_KEXEC_CORE)
420# define XLF4 XLF_EFI_KEXEC
421#else
422# define XLF4 0
423#endif
424
425#ifdef CONFIG_X86_64
426#ifdef CONFIG_X86_5LEVEL
427#define XLF56 (XLF_5LEVEL|XLF_5LEVEL_ENABLED)
428#else
429#define XLF56 XLF_5LEVEL
430#endif
431#else
432#define XLF56 0
433#endif
434
435 .word XLF0 | XLF1 | XLF23 | XLF4 | XLF56
436
437cmdline_size: .long COMMAND_LINE_SIZE-1 #length of the command line,
438 #added with boot protocol
439 #version 2.06
440
441hardware_subarch: .long 0 # subarchitecture, added with 2.07
442 # default to 0 for normal x86 PC
443
444hardware_subarch_data: .quad 0
445
446payload_offset: .long ZO_input_data
447payload_length: .long ZO_z_input_len
448
449setup_data: .quad 0 # 64-bit physical pointer to
450 # single linked list of
451 # struct setup_data
452
453pref_address: .quad LOAD_PHYSICAL_ADDR # preferred load addr
454
455#
456# Getting to provably safe in-place decompression is hard. Worst case
457# behaviours need to be analyzed. Here let's take the decompression of
458# a gzip-compressed kernel as example, to illustrate it:
459#
460# The file layout of gzip compressed kernel is:
461#
462# magic[2]
463# method[1]
464# flags[1]
465# timestamp[4]
466# extraflags[1]
467# os[1]
468# compressed data blocks[N]
469# crc[4] orig_len[4]
470#
471# ... resulting in +18 bytes overhead of uncompressed data.
472#
473# (For more information, please refer to RFC 1951 and RFC 1952.)
474#
475# Files divided into blocks
476# 1 bit (last block flag)
477# 2 bits (block type)
478#
479# 1 block occurs every 32K -1 bytes or when there 50% compression
480# has been achieved. The smallest block type encoding is always used.
481#
482# stored:
483# 32 bits length in bytes.
484#
485# fixed:
486# magic fixed tree.
487# symbols.
488#
489# dynamic:
490# dynamic tree encoding.
491# symbols.
492#
493#
494# The buffer for decompression in place is the length of the uncompressed
495# data, plus a small amount extra to keep the algorithm safe. The
496# compressed data is placed at the end of the buffer. The output pointer
497# is placed at the start of the buffer and the input pointer is placed
498# where the compressed data starts. Problems will occur when the output
499# pointer overruns the input pointer.
500#
501# The output pointer can only overrun the input pointer if the input
502# pointer is moving faster than the output pointer. A condition only
503# triggered by data whose compressed form is larger than the uncompressed
504# form.
505#
506# The worst case at the block level is a growth of the compressed data
507# of 5 bytes per 32767 bytes.
508#
509# The worst case internal to a compressed block is very hard to figure.
510# The worst case can at least be bounded by having one bit that represents
511# 32764 bytes and then all of the rest of the bytes representing the very
512# very last byte.
513#
514# All of which is enough to compute an amount of extra data that is required
515# to be safe. To avoid problems at the block level allocating 5 extra bytes
516# per 32767 bytes of data is sufficient. To avoid problems internal to a
517# block adding an extra 32767 bytes (the worst case uncompressed block size)
518# is sufficient, to ensure that in the worst case the decompressed data for
519# block will stop the byte before the compressed data for a block begins.
520# To avoid problems with the compressed data's meta information an extra 18
521# bytes are needed. Leading to the formula:
522#
523# extra_bytes = (uncompressed_size >> 12) + 32768 + 18
524#
525# Adding 8 bytes per 32K is a bit excessive but much easier to calculate.
526# Adding 32768 instead of 32767 just makes for round numbers.
527#
528# Above analysis is for decompressing gzip compressed kernel only. Up to
529# now 6 different decompressor are supported all together. And among them
530# xz stores data in chunks and has maximum chunk of 64K. Hence safety
531# margin should be updated to cover all decompressors so that we don't
532# need to deal with each of them separately. Please check
533# the description in lib/decompressor_xxx.c for specific information.
534#
535# extra_bytes = (uncompressed_size >> 12) + 65536 + 128
536#
537# LZ4 is even worse: data that cannot be further compressed grows by 0.4%,
538# or one byte per 256 bytes. OTOH, we can safely get rid of the +128 as
539# the size-dependent part now grows so fast.
540#
541# extra_bytes = (uncompressed_size >> 8) + 65536
542#
543# ZSTD compressed data grows by at most 3 bytes per 128K, and only has a 22
544# byte fixed overhead but has a maximum block size of 128K, so it needs a
545# larger margin.
546#
547# extra_bytes = (uncompressed_size >> 8) + 131072
548
549#define ZO_z_extra_bytes ((ZO_z_output_len >> 8) + 131072)
550#if ZO_z_output_len > ZO_z_input_len
551# define ZO_z_extract_offset (ZO_z_output_len + ZO_z_extra_bytes - \
552 ZO_z_input_len)
553#else
554# define ZO_z_extract_offset ZO_z_extra_bytes
555#endif
556
557/*
558 * The extract_offset has to be bigger than ZO head section. Otherwise when
559 * the head code is running to move ZO to the end of the buffer, it will
560 * overwrite the head code itself.
561 */
562#if (ZO__ehead - ZO_startup_32) > ZO_z_extract_offset
563# define ZO_z_min_extract_offset ((ZO__ehead - ZO_startup_32 + 4095) & ~4095)
564#else
565# define ZO_z_min_extract_offset ((ZO_z_extract_offset + 4095) & ~4095)
566#endif
567
568#define ZO_INIT_SIZE (ZO__end - ZO_startup_32 + ZO_z_min_extract_offset)
569
570#define VO_INIT_SIZE (VO__end - VO__text)
571#if ZO_INIT_SIZE > VO_INIT_SIZE
572# define INIT_SIZE ZO_INIT_SIZE
573#else
574# define INIT_SIZE VO_INIT_SIZE
575#endif
576
577init_size: .long INIT_SIZE # kernel initialization size
578handover_offset: .long 0 # Filled in by build.c
579kernel_info_offset: .long 0 # Filled in by build.c
580
581# End of setup header #####################################################
582
583 .section ".entrytext", "ax"
584start_of_setup:
585# Force %es = %ds
586 movw %ds, %ax
587 movw %ax, %es
588 cld
589
590# Apparently some ancient versions of LILO invoked the kernel with %ss != %ds,
591# which happened to work by accident for the old code. Recalculate the stack
592# pointer if %ss is invalid. Otherwise leave it alone, LOADLIN sets up the
593# stack behind its own code, so we can't blindly put it directly past the heap.
594
595 movw %ss, %dx
596 cmpw %ax, %dx # %ds == %ss?
597 movw %sp, %dx
598 je 2f # -> assume %sp is reasonably set
599
600 # Invalid %ss, make up a new stack
601 movw $_end, %dx
602 testb $CAN_USE_HEAP, loadflags
603 jz 1f
604 movw heap_end_ptr, %dx
6051: addw $STACK_SIZE, %dx
606 jnc 2f
607 xorw %dx, %dx # Prevent wraparound
608
6092: # Now %dx should point to the end of our stack space
610 andw $~3, %dx # dword align (might as well...)
611 jnz 3f
612 movw $0xfffc, %dx # Make sure we're not zero
6133: movw %ax, %ss
614 movzwl %dx, %esp # Clear upper half of %esp
615 sti # Now we should have a working stack
616
617# We will have entered with %cs = %ds+0x20, normalize %cs so
618# it is on par with the other segments.
619 pushw %ds
620 pushw $6f
621 lretw
6226:
623
624# Check signature at end of setup
625 cmpl $0x5a5aaa55, setup_sig
626 jne setup_bad
627
628# Zero the bss
629 movw $__bss_start, %di
630 movw $_end+3, %cx
631 xorl %eax, %eax
632 subw %di, %cx
633 shrw $2, %cx
634 rep; stosl
635
636# Jump to C code (should not return)
637 calll main
638
639# Setup corrupt somehow...
640setup_bad:
641 movl $setup_corrupt, %eax
642 calll puts
643 # Fall through...
644
645 .globl die
646 .type die, @function
647die:
648 hlt
649 jmp die
650
651 .size die, .-die
652
653 .section ".initdata", "a"
654setup_corrupt:
655 .byte 7
656 .string "No setup signature found...\n"