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 "Use a boot loader.\r\n" 95 .ascii "\n" 96 .ascii "Remove disk and press any key to reboot...\r\n" 97 .byte 0 98 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 110 .word 4 # nr_sections 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 145 146 .long 0x0200 # BaseOfCode 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 157 .long 0x20 # SectionAlignment 158 .long 0x20 # FileAlignment 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 188 .long 0x6 # NumberOfRvaAndSizes 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: 199 # 200 # The offset & size fields are filled in by build.c. 201 # 202 .ascii ".setup" 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 218 # because EFI applications must be relocatable. The .reloc 219 # offset & size fields are filled in by build.c. 220 # 221 .ascii ".reloc" 222 .byte 0 223 .byte 0 224 .long 0 225 .long 0 226 .long 0 # SizeOfRawData 227 .long 0 # PointerToRawData 228 .long 0 # PointerToRelocations 229 .long 0 # PointerToLineNumbers 230 .word 0 # NumberOfRelocations 231 .word 0 # NumberOfLineNumbers 232 .long 0x42100040 # Characteristics (section flags) 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) 251 252 # 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) 270 271#endif /* CONFIG_EFI_STUB */ 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" 277 .globl sentinel 278sentinel: .byte 0xff, 0xff /* Used to detect broken loaders */ 279 280 .globl hdr 281hdr: 282setup_sects: .byte 0 /* Filled in by build.c */ 283root_flags: .word ROOT_RDONLY 284syssize: .long 0 /* Filled in by build.c */ 285ram_size: .word 0 /* Obsolete */ 286vid_mode: .word SVGA_MODE 287root_dev: .word 0 /* Filled in by build.c */ 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 304 .word 0x020d # header version number (>= 0x0105) 305 # or else old loadlin-1.5 will fail) 306 .globl realmode_swtch 307realmode_swtch: .word 0, 0 # default_switch, SETUPSEG 308start_sys_seg: .word SYSSEG # obsolete and meaningless, but just 309 # in case something decided to "use" it 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 315type_of_loader: .byte 0 # 0 means ancient bootloader, newer 316 # bootloaders know to change this. 317 # See Documentation/x86/boot.txt for 318 # assigned ids 319 320# flags, unused bits must be zero (RFU) bit within loadflags 321loadflags: 322 .byte LOADED_HIGH # The kernel is to be loaded high 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. 333 .long 0x100000 # 0x100000 = default for big kernel 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 345heap_end_ptr: .word _end+STACK_SIZE-512 346 # (Header version 0x0201 or later) 347 # space from here (exclusive) down to 348 # end of setup code can be used by setup 349 # for local heap purposes. 350 351ext_loader_ver: 352 .byte 0 # Extended boot loader version 353ext_loader_type: 354 .byte 0 # Extended boot loader type 355 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 371initrd_addr_max: .long 0x7fffffff 372 # (Header version 0x0203 or later) 373 # The highest safe address for 374 # the contents of an initrd 375 # The current kernel allows up to 4 GB, 376 # but leave it at 2 GB to avoid 377 # possible bootloader bugs. 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 387min_alignment: .byte MIN_KERNEL_ALIGN_LG2 # minimum alignment 388 389xloadflags: 390#ifdef CONFIG_X86_64 391# define XLF0 XLF_KERNEL_64 /* 64-bit kernel */ 392#else 393# define XLF0 0 394#endif 395 396#if defined(CONFIG_RELOCATABLE) && defined(CONFIG_X86_64) 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 402 403#ifdef CONFIG_EFI_STUB 404# ifdef CONFIG_EFI_MIXED 405# define XLF23 (XLF_EFI_HANDOVER_32|XLF_EFI_HANDOVER_64) 406# else 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 412# endif 413#else 414# define XLF23 0 415#endif 416 417#if defined(CONFIG_X86_64) && defined(CONFIG_EFI) && defined(CONFIG_KEXEC_CORE) 418# define XLF4 XLF_EFI_KEXEC 419#else 420# define XLF4 0 421#endif 422 423 .word XLF0 | XLF1 | XLF23 | XLF4 424 425cmdline_size: .long COMMAND_LINE_SIZE-1 #length of the command line, 426 #added with boot protocol 427 #version 2.06 428 429hardware_subarch: .long 0 # subarchitecture, added with 2.07 430 # default to 0 for normal x86 PC 431 432hardware_subarch_data: .quad 0 433 434payload_offset: .long ZO_input_data 435payload_length: .long ZO_z_input_len 436 437setup_data: .quad 0 # 64-bit physical pointer to 438 # single linked list of 439 # struct setup_data 440 441pref_address: .quad LOAD_PHYSICAL_ADDR # preferred load addr 442 443#define ZO_INIT_SIZE (ZO__end - ZO_startup_32 + ZO_z_extract_offset) 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 451handover_offset: .long 0 # Filled in by build.c 452 453# End of setup header ##################################################### 454 455 .section ".entrytext", "ax" 456start_of_setup: 457# Force %es = %ds 458 movw %ds, %ax 459 movw %ax, %es 460 cld 461 462# 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. 466 467 movw %ss, %dx 468 cmpw %ax, %dx # %ds == %ss? 469 movw %sp, %dx 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 480 4812: # Now %dx should point to the end of our stack space 482 andw $~3, %dx # dword align (might as well...) 483 jnz 3f 484 movw $0xfffc, %dx # Make sure we're not zero 4853: movw %ax, %ss 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: 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 522 523 .size die, .-die 524 525 .section ".initdata", "a" 526setup_corrupt: 527 .byte 7 528 .string "No setup signature found...\n" 529