x86/KASLR: Rename "random" to "random_addr"
[deliverable/linux.git] / arch / x86 / boot / header.S
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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>
273b281f 19#include <generated/utsrelease.h>
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20#include <asm/boot.h>
21#include <asm/e820.h>
0341c14d 22#include <asm/page_types.h>
62607313 23#include <asm/setup.h>
09c205af 24#include <asm/bootparam.h>
62607313 25#include "boot.h"
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26#include "voffset.h"
27#include "zoffset.h"
62607313 28
62607313 29BOOTSEG = 0x07C0 /* original address of boot-sector */
5e47c478 30SYSSEG = 0x1000 /* historical load address >> 4 */
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31
32#ifndef SVGA_MODE
33#define SVGA_MODE ASK_VGA
34#endif
35
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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:
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45#ifdef CONFIG_EFI_STUB
46 # "MZ", MS-DOS header
47 .byte 0x4d
48 .byte 0x5a
49#endif
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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
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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
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92 .section ".bsdata", "a"
93bugger_off_msg:
c7fb93ec 94 .ascii "Use a boot loader.\r\n"
62607313 95 .ascii "\n"
c7fb93ec 96 .ascii "Remove disk and press any key to reboot...\r\n"
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97 .byte 0
98
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99#ifdef CONFIG_EFI_STUB
100pe_header:
101 .ascii "PE"
102 .word 0
103
104coff_header:
105#ifdef CONFIG_X86_32
106 .word 0x14c # i386
107#else
108 .word 0x8664 # x86-64
109#endif
c7fb93ec 110 .word 4 # nr_sections
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111 .long 0 # TimeDateStamp
112 .long 0 # PointerToSymbolTable
113 .long 1 # NumberOfSymbols
114 .word section_table - optional_header # SizeOfOptionalHeader
115#ifdef CONFIG_X86_32
116 .word 0x306 # Characteristics.
117 # IMAGE_FILE_32BIT_MACHINE |
118 # IMAGE_FILE_DEBUG_STRIPPED |
119 # IMAGE_FILE_EXECUTABLE_IMAGE |
120 # IMAGE_FILE_LINE_NUMS_STRIPPED
121#else
122 .word 0x206 # Characteristics
123 # IMAGE_FILE_DEBUG_STRIPPED |
124 # IMAGE_FILE_EXECUTABLE_IMAGE |
125 # IMAGE_FILE_LINE_NUMS_STRIPPED
126#endif
127
128optional_header:
129#ifdef CONFIG_X86_32
130 .word 0x10b # PE32 format
131#else
132 .word 0x20b # PE32+ format
133#endif
134 .byte 0x02 # MajorLinkerVersion
135 .byte 0x14 # MinorLinkerVersion
136
137 # Filled in by build.c
138 .long 0 # SizeOfCode
139
140 .long 0 # SizeOfInitializedData
141 .long 0 # SizeOfUninitializedData
142
143 # Filled in by build.c
144 .long 0x0000 # AddressOfEntryPoint
145
e31be363 146 .long 0x0200 # BaseOfCode
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147#ifdef CONFIG_X86_32
148 .long 0 # data
149#endif
150
151extra_header_fields:
152#ifdef CONFIG_X86_32
153 .long 0 # ImageBase
154#else
155 .quad 0 # ImageBase
156#endif
fa5c3501 157 .long 0x20 # SectionAlignment
743628e8 158 .long 0x20 # FileAlignment
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159 .word 0 # MajorOperatingSystemVersion
160 .word 0 # MinorOperatingSystemVersion
161 .word 0 # MajorImageVersion
162 .word 0 # MinorImageVersion
163 .word 0 # MajorSubsystemVersion
164 .word 0 # MinorSubsystemVersion
165 .long 0 # Win32VersionValue
166
167 #
168 # The size of the bzImage is written in tools/build.c
169 #
170 .long 0 # SizeOfImage
171
172 .long 0x200 # SizeOfHeaders
173 .long 0 # CheckSum
174 .word 0xa # Subsystem (EFI application)
175 .word 0 # DllCharacteristics
176#ifdef CONFIG_X86_32
177 .long 0 # SizeOfStackReserve
178 .long 0 # SizeOfStackCommit
179 .long 0 # SizeOfHeapReserve
180 .long 0 # SizeOfHeapCommit
181#else
182 .quad 0 # SizeOfStackReserve
183 .quad 0 # SizeOfStackCommit
184 .quad 0 # SizeOfHeapReserve
185 .quad 0 # SizeOfHeapCommit
186#endif
187 .long 0 # LoaderFlags
e47bb0bd 188 .long 0x6 # NumberOfRvaAndSizes
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189
190 .quad 0 # ExportTable
191 .quad 0 # ImportTable
192 .quad 0 # ResourceTable
193 .quad 0 # ExceptionTable
194 .quad 0 # CertificationTable
195 .quad 0 # BaseRelocationTable
196
197 # Section table
198section_table:
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199 #
200 # The offset & size fields are filled in by build.c.
201 #
202 .ascii ".setup"
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203 .byte 0
204 .byte 0
205 .long 0
206 .long 0x0 # startup_{32,64}
207 .long 0 # Size of initialized data
208 # on disk
209 .long 0x0 # startup_{32,64}
210 .long 0 # PointerToRelocations
211 .long 0 # PointerToLineNumbers
212 .word 0 # NumberOfRelocations
213 .word 0 # NumberOfLineNumbers
214 .long 0x60500020 # Characteristics (section flags)
215
216 #
217 # The EFI application loader requires a relocation section
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218 # because EFI applications must be relocatable. The .reloc
219 # offset & size fields are filled in by build.c.
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220 #
221 .ascii ".reloc"
222 .byte 0
223 .byte 0
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224 .long 0
225 .long 0
226 .long 0 # SizeOfRawData
227 .long 0 # PointerToRawData
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228 .long 0 # PointerToRelocations
229 .long 0 # PointerToLineNumbers
230 .word 0 # NumberOfRelocations
231 .word 0 # NumberOfLineNumbers
232 .long 0x42100040 # Characteristics (section flags)
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233
234 #
235 # The offset & size fields are filled in by build.c.
236 #
237 .ascii ".text"
238 .byte 0
239 .byte 0
240 .byte 0
241 .long 0
242 .long 0x0 # startup_{32,64}
243 .long 0 # Size of initialized data
244 # on disk
245 .long 0x0 # startup_{32,64}
246 .long 0 # PointerToRelocations
247 .long 0 # PointerToLineNumbers
248 .word 0 # NumberOfRelocations
249 .word 0 # NumberOfLineNumbers
250 .long 0x60500020 # Characteristics (section flags)
251
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252 #
253 # The offset & size fields are filled in by build.c.
254 #
255 .ascii ".bss"
256 .byte 0
257 .byte 0
258 .byte 0
259 .byte 0
260 .long 0
261 .long 0x0
262 .long 0 # Size of initialized data
263 # on disk
264 .long 0x0
265 .long 0 # PointerToRelocations
266 .long 0 # PointerToLineNumbers
267 .word 0 # NumberOfRelocations
268 .word 0 # NumberOfLineNumbers
269 .long 0xc8000080 # Characteristics (section flags)
270
291f3632 271#endif /* CONFIG_EFI_STUB */
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272
273 # Kernel attributes; used by setup. This is part 1 of the
274 # header, from the old boot sector.
275
276 .section ".header", "a"
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277 .globl sentinel
278sentinel: .byte 0xff, 0xff /* Used to detect broken loaders */
279
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280 .globl hdr
281hdr:
5e47c478 282setup_sects: .byte 0 /* Filled in by build.c */
62607313 283root_flags: .word ROOT_RDONLY
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284syssize: .long 0 /* Filled in by build.c */
285ram_size: .word 0 /* Obsolete */
62607313 286vid_mode: .word SVGA_MODE
5e47c478 287root_dev: .word 0 /* Filled in by build.c */
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288boot_flag: .word 0xAA55
289
290 # offset 512, entry point
291
292 .globl _start
293_start:
294 # Explicitly enter this as bytes, or the assembler
295 # tries to generate a 3-byte jump here, which causes
296 # everything else to push off to the wrong offset.
297 .byte 0xeb # short (2-byte) jump
298 .byte start_of_setup-1f
2991:
300
301 # Part 2 of the header, from the old setup.S
302
303 .ascii "HdrS" # header signature
7d453eee 304 .word 0x020d # header version number (>= 0x0105)
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305 # or else old loadlin-1.5 will fail)
306 .globl realmode_swtch
307realmode_swtch: .word 0, 0 # default_switch, SETUPSEG
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308start_sys_seg: .word SYSSEG # obsolete and meaningless, but just
309 # in case something decided to "use" it
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310 .word kernel_version-512 # pointing to kernel version string
311 # above section of header is compatible
312 # with loadlin-1.5 (header v1.5). Don't
313 # change it.
314
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315type_of_loader: .byte 0 # 0 means ancient bootloader, newer
316 # bootloaders know to change this.
395cf969 317 # See Documentation/x86/boot.txt for
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318 # assigned ids
319
320# flags, unused bits must be zero (RFU) bit within loadflags
321loadflags:
09c205af 322 .byte LOADED_HIGH # The kernel is to be loaded high
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323
324setup_move_size: .word 0x8000 # size to move, when setup is not
325 # loaded at 0x90000. We will move setup
326 # to 0x90000 then just before jumping
327 # into the kernel. However, only the
328 # loader knows how much data behind
329 # us also needs to be loaded.
330
331code32_start: # here loaders can put a different
332 # start address for 32-bit code.
62607313 333 .long 0x100000 # 0x100000 = default for big kernel
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334
335ramdisk_image: .long 0 # address of loaded ramdisk image
336 # Here the loader puts the 32-bit
337 # address where it loaded the image.
338 # This only will be read by the kernel.
339
340ramdisk_size: .long 0 # its size in bytes
341
342bootsect_kludge:
343 .long 0 # obsolete
344
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345heap_end_ptr: .word _end+STACK_SIZE-512
346 # (Header version 0x0201 or later)
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347 # space from here (exclusive) down to
348 # end of setup code can be used by setup
349 # for local heap purposes.
350
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351ext_loader_ver:
352 .byte 0 # Extended boot loader version
353ext_loader_type:
354 .byte 0 # Extended boot loader type
355
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356cmd_line_ptr: .long 0 # (Header version 0x0202 or later)
357 # If nonzero, a 32-bit pointer
358 # to the kernel command line.
359 # The command line should be
360 # located between the start of
361 # setup and the end of low
362 # memory (0xa0000), or it may
363 # get overwritten before it
364 # gets read. If this field is
365 # used, there is no longer
366 # anything magical about the
367 # 0x90000 segment; the setup
368 # can be located anywhere in
369 # low memory 0x10000 or higher.
370
3e920b53 371initrd_addr_max: .long 0x7fffffff
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372 # (Header version 0x0203 or later)
373 # The highest safe address for
374 # the contents of an initrd
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375 # The current kernel allows up to 4 GB,
376 # but leave it at 2 GB to avoid
377 # possible bootloader bugs.
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378
379kernel_alignment: .long CONFIG_PHYSICAL_ALIGN #physical addr alignment
380 #required for protected mode
381 #kernel
382#ifdef CONFIG_RELOCATABLE
383relocatable_kernel: .byte 1
384#else
385relocatable_kernel: .byte 0
386#endif
37ba7ab5 387min_alignment: .byte MIN_KERNEL_ALIGN_LG2 # minimum alignment
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388
389xloadflags:
390#ifdef CONFIG_X86_64
391# define XLF0 XLF_KERNEL_64 /* 64-bit kernel */
392#else
393# define XLF0 0
394#endif
ee92d815 395
745c5167 396#if defined(CONFIG_RELOCATABLE) && defined(CONFIG_X86_64)
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397 /* kernel/boot_param/ramdisk could be loaded above 4g */
398# define XLF1 XLF_CAN_BE_LOADED_ABOVE_4G
399#else
400# define XLF1 0
401#endif
402
09c205af 403#ifdef CONFIG_EFI_STUB
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404# ifdef CONFIG_EFI_MIXED
405# define XLF23 (XLF_EFI_HANDOVER_32|XLF_EFI_HANDOVER_64)
09c205af 406# else
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407# ifdef CONFIG_X86_64
408# define XLF23 XLF_EFI_HANDOVER_64 /* 64-bit EFI handover ok */
409# else
410# define XLF23 XLF_EFI_HANDOVER_32 /* 32-bit EFI handover ok */
411# endif
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412# endif
413#else
414# define XLF23 0
415#endif
456a29dd 416
2965faa5 417#if defined(CONFIG_X86_64) && defined(CONFIG_EFI) && defined(CONFIG_KEXEC_CORE)
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418# define XLF4 XLF_EFI_KEXEC
419#else
420# define XLF4 0
421#endif
422
423 .word XLF0 | XLF1 | XLF23 | XLF4
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424
425cmdline_size: .long COMMAND_LINE_SIZE-1 #length of the command line,
426 #added with boot protocol
427 #version 2.06
428
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429hardware_subarch: .long 0 # subarchitecture, added with 2.07
430 # default to 0 for normal x86 PC
431
432hardware_subarch_data: .quad 0
433
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434payload_offset: .long ZO_input_data
435payload_length: .long ZO_z_input_len
099e1377 436
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437setup_data: .quad 0 # 64-bit physical pointer to
438 # single linked list of
439 # struct setup_data
440
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441pref_address: .quad LOAD_PHYSICAL_ADDR # preferred load addr
442
c6ac4c18 443#define ZO_INIT_SIZE (ZO__end - ZO_startup_32 + ZO_z_extract_offset)
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444#define VO_INIT_SIZE (VO__end - VO__text)
445#if ZO_INIT_SIZE > VO_INIT_SIZE
446#define INIT_SIZE ZO_INIT_SIZE
447#else
448#define INIT_SIZE VO_INIT_SIZE
449#endif
450init_size: .long INIT_SIZE # kernel initialization size
86134a1b 451handover_offset: .long 0 # Filled in by build.c
37ba7ab5 452
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453# End of setup header #####################################################
454
7a734e7d 455 .section ".entrytext", "ax"
62607313 456start_of_setup:
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457# Force %es = %ds
458 movw %ds, %ax
459 movw %ax, %es
460 cld
461
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462# Apparently some ancient versions of LILO invoked the kernel with %ss != %ds,
463# which happened to work by accident for the old code. Recalculate the stack
464# pointer if %ss is invalid. Otherwise leave it alone, LOADLIN sets up the
465# stack behind its own code, so we can't blindly put it directly past the heap.
6b6815c6 466
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467 movw %ss, %dx
468 cmpw %ax, %dx # %ds == %ss?
469 movw %sp, %dx
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470 je 2f # -> assume %sp is reasonably set
471
472 # Invalid %ss, make up a new stack
473 movw $_end, %dx
474 testb $CAN_USE_HEAP, loadflags
475 jz 1f
476 movw heap_end_ptr, %dx
4771: addw $STACK_SIZE, %dx
478 jnc 2f
479 xorw %dx, %dx # Prevent wraparound
6b6815c6 480
16252da6 4812: # Now %dx should point to the end of our stack space
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482 andw $~3, %dx # dword align (might as well...)
483 jnz 3f
484 movw $0xfffc, %dx # Make sure we're not zero
16252da6 4853: movw %ax, %ss
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486 movzwl %dx, %esp # Clear upper half of %esp
487 sti # Now we should have a working stack
488
489# We will have entered with %cs = %ds+0x20, normalize %cs so
490# it is on par with the other segments.
491 pushw %ds
492 pushw $6f
493 lretw
4946:
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495
496# Check signature at end of setup
497 cmpl $0x5a5aaa55, setup_sig
498 jne setup_bad
499
500# Zero the bss
501 movw $__bss_start, %di
502 movw $_end+3, %cx
503 xorl %eax, %eax
504 subw %di, %cx
505 shrw $2, %cx
506 rep; stosl
507
508# Jump to C code (should not return)
509 calll main
510
511# Setup corrupt somehow...
512setup_bad:
513 movl $setup_corrupt, %eax
514 calll puts
515 # Fall through...
516
517 .globl die
518 .type die, @function
519die:
520 hlt
521 jmp die
522
bbc15f46 523 .size die, .-die
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524
525 .section ".initdata", "a"
526setup_corrupt:
527 .byte 7
8b608d2f 528 .string "No setup signature found...\n"
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