1 /* SPDX-License-Identifier: GPL-2.0 */
2 /*
3 * header.S
4 *
5 * Copyright (C) 1991, 1992 Linus Torvald
6 *
7 * Based on bootsect.S and setup.S
8 * modified by more people than can be co
9 *
10 * Rewritten as a common file by H. Peter
11 *
12 * BIG FAT NOTE: We're in real mode using 64k
13 * addresses must be multiplied by 16 to obtai
14 * addresses. To avoid confusion, linear addre
15 * hex while segment addresses are written as
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
28 BOOTSEG = 0x07C0 /* ori
29 SYSSEG = 0x1000 /* his
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
53 pe_header:
54 .long PE_MAGIC
55
56 coff_header:
57 #ifdef CONFIG_X86_32
58 .set image_file_add_flags, IMAGE_FI
59 .set pe_opt_magic, PE_OPT_MAGIC_PE3
60 .word IMAGE_FILE_MACHINE_I386
61 #else
62 .set image_file_add_flags, 0
63 .set pe_opt_magic, PE_OPT_MAGIC_PE3
64 .word IMAGE_FILE_MACHINE_AMD64
65 #endif
66 .word section_count
67 .long 0
68 .long 0
69 .long 1
70 .word section_table - optional_heade
71 .word IMAGE_FILE_EXECUTABLE_IMAGE
72 image_file_add_flags
73 IMAGE_FILE_DEBUG_STRIPPED
74 IMAGE_FILE_LINE_NUMS_STRIPPED
75
76 optional_header:
77 .word pe_opt_magic
78 .byte 0x02
79 .byte 0x14
80
81 .long ZO__data
82
83 .long ZO__end - ZO__data
84 .long 0
85
86 .long setup_size + ZO_efi_pe_entry
87
88 .long setup_size
89 #ifdef CONFIG_X86_32
90 .long 0
91 #endif
92
93 extra_header_fields:
94 #ifdef CONFIG_X86_32
95 .long 0
96 #else
97 .quad 0
98 #endif
99 .long salign
100 .long falign
101 .word 0
102 .word 0
103 .word LINUX_EFISTUB_MAJOR_VERSION
104 .word LINUX_EFISTUB_MINOR_VERSION
105 .word 0
106 .word 0
107 .long 0
108
109 .long setup_size + ZO__end
110
111 .long salign
112 .long 0
113 .word IMAGE_SUBSYSTEM_EFI_APPLICATIO
114 .word IMAGE_DLL_CHARACTERISTICS_NX_C
115 #ifdef CONFIG_X86_32
116 .long 0
117 .long 0
118 .long 0
119 .long 0
120 #else
121 .quad 0
122 .quad 0
123 .quad 0
124 .quad 0
125 #endif
126 .long 0
127 .long (section_table - .) / 8
128
129 .quad 0
130 .quad 0
131 .quad 0
132 .quad 0
133 .quad 0
134 .quad 0
135
136 # Section table
137 section_table:
138 .ascii ".setup"
139 .byte 0
140 .byte 0
141 .long pecompat_fstart - salign
142 .long salign
143 .long pecompat_fstart - salign
144 .long salign
145
146 .long 0, 0, 0
147 .long IMAGE_SCN_CNT_INITIALIZED_DATA
148 IMAGE_SCN_MEM_READ
149 IMAGE_SCN_MEM_DISCARDABLE
150
151 #ifdef CONFIG_EFI_MIXED
152 .asciz ".compat"
153
154 .long pecompat_fsize
155 .long pecompat_fstart
156 .long pecompat_fsize
157 .long pecompat_fstart
158
159 .long 0, 0, 0
160 .long IMAGE_SCN_CNT_INITIALIZED_DATA
161 IMAGE_SCN_MEM_READ
162 IMAGE_SCN_MEM_DISCARDABLE
163
164 /*
165 * Put the IA-32 machine type and the
166 * the .compat section, so loaders can
167 * modes this image supports.
168 */
169 .pushsection ".pecompat", "a", @progbi
170 .balign salign
171 .globl pecompat_fstart
172 pecompat_fstart:
173 .byte 0x1
174 .byte 8
175 .word IMAGE_FILE_MACHINE_I386
176 .long setup_size + ZO_efi32_pe_entry
177 .byte 0x0
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
189
190 .long setup_size
191 .long 0
192 .long 0
193 .word 0
194 .word 0
195 .long IMAGE_SCN_CNT_CODE
196 IMAGE_SCN_MEM_READ
197 IMAGE_SCN_MEM_EXECUTE
198
199 .ascii ".data\0\0\0"
200 .long ZO__end - ZO__data
201 .long setup_size + ZO__data
202 .long ZO__edata - ZO__data
203 .long setup_size + ZO__data
204
205 .long 0, 0, 0
206 .long IMAGE_SCN_CNT_INITIALIZED_DATA
207 IMAGE_SCN_MEM_READ
208 IMAGE_SCN_MEM_WRITE
209
210 .set section_count, (. - section_ta
211 #endif /* CONFIG_EFI_STUB */
212
213 # Kernel attributes; used by setup. T
214 # header, from the old boot sector.
215
216 .section ".header", "a"
217 .globl sentinel
218 sentinel: .byte 0xff, 0xff /* Use
219
220 .globl hdr
221 hdr:
222 .byte setup_sects - 1
223 root_flags: .word ROOT_RDONLY
224 syssize: .long ZO__edata / 16
225 ram_size: .word 0 /* Obs
226 vid_mode: .word SVGA_MODE
227 root_dev: .word 0 /* Def
228 boot_flag: .word 0xAA55
229
230 # offset 512, entry point
231
232 .globl _start
233 _start:
234 # Explicitly enter this as byt
235 # tries to generate a 3-byte j
236 # everything else to push off
237 .byte 0xeb # shor
238 .byte start_of_setup-1f
239 1:
240
241 # Part 2 of the header, from the old s
242
243 .ascii "HdrS" # head
244 .word 0x020f # head
245 # or e
246 .globl realmode_swtch
247 realmode_swtch: .word 0, 0 # defa
248 start_sys_seg: .word SYSSEG # obso
249 # in c
250 .word kernel_version-512 # p
251 # abov
252 # with
253 # chan
254
255 type_of_loader: .byte 0 # 0 me
256 # boot
257 # See
258 # assi
259
260 # flags, unused bits must be zero (RFU) bit wi
261 loadflags:
262 .byte LOADED_HIGH # The
263
264 setup_move_size: .word 0x8000 # size
265 # load
266 # to 0
267 # into
268 # load
269 # us a
270
271 code32_start: # here
272 # star
273 .long 0x100000 # 0x10
274
275 ramdisk_image: .long 0 # addr
276 # Here
277 # addr
278 # This
279
280 ramdisk_size: .long 0 # its
281
282 bootsect_kludge:
283 .long 0 # obso
284
285 heap_end_ptr: .word _end+STACK_SIZE-512
286 # (Hea
287 # spac
288 # end
289 # for
290
291 ext_loader_ver:
292 .byte 0 # Exte
293 ext_loader_type:
294 .byte 0 # Exte
295
296 cmd_line_ptr: .long 0 # (Hea
297 # If n
298 # to t
299 # The
300 # loca
301 # setu
302 # memo
303 # get
304 # gets
305 # used
306 # anyt
307 # 0x90
308 # can
309 # low
310
311 initrd_addr_max: .long 0x7fffffff
312 # (Hea
313 # The
314 # the
315 # The
316 # but
317 # poss
318
319 kernel_alignment: .long CONFIG_PHYSICAL_ALIGN
320
321
322 #ifdef CONFIG_RELOCATABLE
323 relocatable_kernel: .byte 1
324 #else
325 relocatable_kernel: .byte 0
326 #endif
327 min_alignment: .byte MIN_KERNEL_ALIGN
328
329 xloadflags:
330 #ifdef CONFIG_X86_64
331 # define XLF0 XLF_KERNEL_64
332 #else
333 # define XLF0 0
334 #endif
335
336 #if defined(CONFIG_RELOCATABLE) && defined(CON
337 /* kernel/boot_param/ramdisk could be loade
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_H
346 # else
347 # ifdef CONFIG_X86_64
348 # define XLF23 XLF_EFI_HANDOVER_64
349 # else
350 # define XLF23 XLF_EFI_HANDOVER_32
351 # endif
352 # endif
353 #else
354 # define XLF23 0
355 #endif
356
357 #if defined(CONFIG_X86_64) && defined(CONFIG_E
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 | XL
374
375 cmdline_size: .long COMMAND_LINE_SIZE-1
376
377
378
379 hardware_subarch: .long 0
380
381
382 hardware_subarch_data: .quad 0
383
384 payload_offset: .long ZO_input_data
385 payload_length: .long ZO_z_input_len
386
387 setup_data: .quad 0
388
389
390
391 pref_address: .quad LOAD_PHYSICAL_AD
392
393 #
394 # Getting to provably safe in-place decompress
395 # behaviours need to be analyzed. Here let's t
396 # a gzip-compressed kernel as example, to illu
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 uncom
410 #
411 # (For more information, please refer to RFC 1
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 th
418 # has been achieved. The smallest block type e
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
433 # data, plus a small amount extra to keep the
434 # compressed data is placed at the end of the
435 # is placed at the start of the buffer and the
436 # where the compressed data starts. Problems w
437 # pointer overruns the input pointer.
438 #
439 # The output pointer can only overrun the inpu
440 # pointer is moving faster than the output poi
441 # triggered by data whose compressed form is l
442 # form.
443 #
444 # The worst case at the block level is a growt
445 # of 5 bytes per 32767 bytes.
446 #
447 # The worst case internal to a compressed bloc
448 # The worst case can at least be bounded by ha
449 # 32764 bytes and then all of the rest of the
450 # very last byte.
451 #
452 # All of which is enough to compute an amount
453 # to be safe. To avoid problems at the block
454 # per 32767 bytes of data is sufficient. To a
455 # block adding an extra 32767 bytes (the worst
456 # is sufficient, to ensure that in the worst c
457 # block will stop the byte before the compress
458 # To avoid problems with the compressed data's
459 # bytes are needed. Leading to the formula:
460 #
461 # extra_bytes = (uncompressed_size >> 12) + 32
462 #
463 # Adding 8 bytes per 32K is a bit excessive bu
464 # Adding 32768 instead of 32767 just makes for
465 #
466 # Above analysis is for decompressing gzip com
467 # now 6 different decompressor are supported a
468 # xz stores data in chunks and has maximum chu
469 # margin should be updated to cover all decomp
470 # need to deal with each of them separately. P
471 # the description in lib/decompressor_xxx.c fo
472 #
473 # extra_bytes = (uncompressed_size >> 12) + 65
474 #
475 # LZ4 is even worse: data that cannot be furth
476 # or one byte per 256 bytes. OTOH, we can safe
477 # the size-dependent part now grows so fast.
478 #
479 # extra_bytes = (uncompressed_size >> 8) + 655
480 #
481 # ZSTD compressed data grows by at most 3 byte
482 # byte fixed overhead but has a maximum block
483 # larger margin.
484 #
485 # extra_bytes = (uncompressed_size >> 8) + 131
486
487 #define ZO_z_extra_bytes ((ZO_z_output_
488 #if ZO_z_output_len > ZO_z_input_len
489 # define ZO_z_extract_offset (ZO_z_output_l
490 ZO_z_input_le
491 #else
492 # define ZO_z_extract_offset ZO_z_extra_byt
493 #endif
494
495 /*
496 * The extract_offset has to be bigger than ZO
497 * the head code is running to move ZO to the
498 * overwrite the head code itself.
499 */
500 #if (ZO__ehead - ZO_startup_32) > ZO_z_extract
501 # define ZO_z_min_extract_offset ((ZO__ehead -
502 #else
503 # define ZO_z_min_extract_offset ((ZO_z_extrac
504 #endif
505
506 #define ZO_INIT_SIZE (ZO__end - ZO_startup_
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
522 .long ZO_efi64_stub_entry -
523 #ifdef CONFIG_EFI_MIXED
524 .if ZO_efi32_stub_entry !=
525 .error "32-bit and 64-bit EFI
526 .endif
527 #endif
528 #endif
529 .endm
530
531 init_size: .long INIT_SIZE
532 handover_offset: __handover_offset
533 kernel_info_offset: .long ZO_kernel_info
534
535 # End of setup header ########################
536
537 .section ".entrytext", "ax"
538 start_of_setup:
539 # Force %es = %ds
540 movw %ds, %ax
541 movw %ax, %es
542 cld
543
544 # Apparently some ancient versions of LILO inv
545 # which happened to work by accident for the o
546 # pointer if %ss is invalid. Otherwise leave
547 # stack behind its own code, so we can't blind
548
549 movw %ss, %dx
550 cmpw %ax, %dx # %ds == %ss?
551 movw %sp, %dx
552 je 2f # -> assume %s
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
559 1: addw $STACK_SIZE, %dx
560 jnc 2f
561 xorw %dx, %dx # Prevent wrap
562
563 2: # Now %dx should point to the end of o
564 andw $~3, %dx # dword align
565 jnz 3f
566 movw $0xfffc, %dx # Make sure we
567 3: movw %ax, %ss
568 movzwl %dx, %esp # Clear upper
569 sti # Now we shoul
570
571 # We will have entered with %cs = %ds+0x20, no
572 # it is on par with the other segments.
573 pushw %ds
574 pushw $6f
575 lretw
576 6:
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...
594 setup_bad:
595 movl $setup_corrupt, %eax
596 calll puts
597 # Fall through...
598
599 .globl die
600 .type die, @function
601 die:
602 hlt
603 jmp die
604
605 .size die, .-die
606
607 .section ".initdata", "a"
608 setup_corrupt:
609 .byte 7
610 .string "No setup signature found...\n
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