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" 511