H. Peter Anvin | 6260731 | 2007-07-11 12:18:54 -0700 | [diff] [blame] | 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> |
Sam Ravnborg | 273b281 | 2009-10-18 00:52:28 +0200 | [diff] [blame] | 19 | #include <generated/utsrelease.h> |
H. Peter Anvin | 6260731 | 2007-07-11 12:18:54 -0700 | [diff] [blame] | 20 | #include <asm/boot.h> |
| 21 | #include <asm/e820.h> |
Jeremy Fitzhardinge | 0341c14 | 2009-02-13 11:14:01 -0800 | [diff] [blame] | 22 | #include <asm/page_types.h> |
H. Peter Anvin | 6260731 | 2007-07-11 12:18:54 -0700 | [diff] [blame] | 23 | #include <asm/setup.h> |
| 24 | #include "boot.h" |
H. Peter Anvin | 77d1a49 | 2009-05-11 14:21:12 -0700 | [diff] [blame] | 25 | #include "voffset.h" |
| 26 | #include "zoffset.h" |
H. Peter Anvin | 6260731 | 2007-07-11 12:18:54 -0700 | [diff] [blame] | 27 | |
H. Peter Anvin | 6260731 | 2007-07-11 12:18:54 -0700 | [diff] [blame] | 28 | BOOTSEG = 0x07C0 /* original address of boot-sector */ |
H. Peter Anvin | 5e47c47 | 2009-03-11 10:55:33 -0700 | [diff] [blame] | 29 | SYSSEG = 0x1000 /* historical load address >> 4 */ |
H. Peter Anvin | 6260731 | 2007-07-11 12:18:54 -0700 | [diff] [blame] | 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 |
| 47 | bootsect_start: |
Matt Fleming | 291f363 | 2011-12-12 21:27:52 +0000 | [diff] [blame] | 48 | #ifdef CONFIG_EFI_STUB |
| 49 | # "MZ", MS-DOS header |
| 50 | .byte 0x4d |
| 51 | .byte 0x5a |
| 52 | #endif |
H. Peter Anvin | 6260731 | 2007-07-11 12:18:54 -0700 | [diff] [blame] | 53 | |
| 54 | # Normalize the start address |
| 55 | ljmp $BOOTSEG, $start2 |
| 56 | |
| 57 | start2: |
| 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 | |
| 68 | msg_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 | |
| 77 | bs_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 | |
Matt Fleming | 291f363 | 2011-12-12 21:27:52 +0000 | [diff] [blame] | 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 | |
H. Peter Anvin | 6260731 | 2007-07-11 12:18:54 -0700 | [diff] [blame] | 95 | .section ".bsdata", "a" |
| 96 | bugger_off_msg: |
| 97 | .ascii "Direct booting from floppy is no longer supported.\r\n" |
| 98 | .ascii "Please 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 | |
Matt Fleming | 291f363 | 2011-12-12 21:27:52 +0000 | [diff] [blame] | 103 | #ifdef CONFIG_EFI_STUB |
| 104 | pe_header: |
| 105 | .ascii "PE" |
| 106 | .word 0 |
| 107 | |
| 108 | coff_header: |
| 109 | #ifdef CONFIG_X86_32 |
| 110 | .word 0x14c # i386 |
| 111 | #else |
| 112 | .word 0x8664 # x86-64 |
| 113 | #endif |
| 114 | .word 2 # 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 | |
| 132 | optional_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 0x0000 # BaseOfCode |
| 151 | #ifdef CONFIG_X86_32 |
| 152 | .long 0 # data |
| 153 | #endif |
| 154 | |
| 155 | extra_header_fields: |
| 156 | #ifdef CONFIG_X86_32 |
| 157 | .long 0 # ImageBase |
| 158 | #else |
| 159 | .quad 0 # ImageBase |
| 160 | #endif |
| 161 | .long 0x1000 # SectionAlignment |
| 162 | .long 0x200 # 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 0x1 # 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 |
| 202 | section_table: |
| 203 | .ascii ".text" |
| 204 | .byte 0 |
| 205 | .byte 0 |
| 206 | .byte 0 |
| 207 | .long 0 |
| 208 | .long 0x0 # startup_{32,64} |
| 209 | .long 0 # Size of initialized data |
| 210 | # on disk |
| 211 | .long 0x0 # startup_{32,64} |
| 212 | .long 0 # PointerToRelocations |
| 213 | .long 0 # PointerToLineNumbers |
| 214 | .word 0 # NumberOfRelocations |
| 215 | .word 0 # NumberOfLineNumbers |
| 216 | .long 0x60500020 # Characteristics (section flags) |
| 217 | |
| 218 | # |
| 219 | # The EFI application loader requires a relocation section |
| 220 | # because EFI applications are relocatable and not having |
| 221 | # this section seems to confuse it. But since we don't need |
| 222 | # the loader to fixup any relocs for us just fill it with a |
| 223 | # single dummy reloc. |
| 224 | # |
| 225 | .ascii ".reloc" |
| 226 | .byte 0 |
| 227 | .byte 0 |
| 228 | .long reloc_end - reloc_start |
| 229 | .long reloc_start |
| 230 | .long reloc_end - reloc_start # SizeOfRawData |
| 231 | .long reloc_start # PointerToRawData |
| 232 | .long 0 # PointerToRelocations |
| 233 | .long 0 # PointerToLineNumbers |
| 234 | .word 0 # NumberOfRelocations |
| 235 | .word 0 # NumberOfLineNumbers |
| 236 | .long 0x42100040 # Characteristics (section flags) |
| 237 | #endif /* CONFIG_EFI_STUB */ |
H. Peter Anvin | 6260731 | 2007-07-11 12:18:54 -0700 | [diff] [blame] | 238 | |
| 239 | # Kernel attributes; used by setup. This is part 1 of the |
| 240 | # header, from the old boot sector. |
| 241 | |
| 242 | .section ".header", "a" |
| 243 | .globl hdr |
| 244 | hdr: |
H. Peter Anvin | 5e47c47 | 2009-03-11 10:55:33 -0700 | [diff] [blame] | 245 | setup_sects: .byte 0 /* Filled in by build.c */ |
H. Peter Anvin | 6260731 | 2007-07-11 12:18:54 -0700 | [diff] [blame] | 246 | root_flags: .word ROOT_RDONLY |
H. Peter Anvin | 5e47c47 | 2009-03-11 10:55:33 -0700 | [diff] [blame] | 247 | syssize: .long 0 /* Filled in by build.c */ |
| 248 | ram_size: .word 0 /* Obsolete */ |
H. Peter Anvin | 6260731 | 2007-07-11 12:18:54 -0700 | [diff] [blame] | 249 | vid_mode: .word SVGA_MODE |
H. Peter Anvin | 5e47c47 | 2009-03-11 10:55:33 -0700 | [diff] [blame] | 250 | root_dev: .word 0 /* Filled in by build.c */ |
H. Peter Anvin | 6260731 | 2007-07-11 12:18:54 -0700 | [diff] [blame] | 251 | boot_flag: .word 0xAA55 |
| 252 | |
| 253 | # offset 512, entry point |
| 254 | |
| 255 | .globl _start |
| 256 | _start: |
| 257 | # Explicitly enter this as bytes, or the assembler |
| 258 | # tries to generate a 3-byte jump here, which causes |
| 259 | # everything else to push off to the wrong offset. |
| 260 | .byte 0xeb # short (2-byte) jump |
| 261 | .byte start_of_setup-1f |
| 262 | 1: |
| 263 | |
| 264 | # Part 2 of the header, from the old setup.S |
| 265 | |
| 266 | .ascii "HdrS" # header signature |
H. Peter Anvin | 37ba7ab | 2009-05-11 15:56:08 -0700 | [diff] [blame] | 267 | .word 0x020a # header version number (>= 0x0105) |
H. Peter Anvin | 6260731 | 2007-07-11 12:18:54 -0700 | [diff] [blame] | 268 | # or else old loadlin-1.5 will fail) |
| 269 | .globl realmode_swtch |
| 270 | realmode_swtch: .word 0, 0 # default_switch, SETUPSEG |
H. Peter Anvin | 5e47c47 | 2009-03-11 10:55:33 -0700 | [diff] [blame] | 271 | start_sys_seg: .word SYSSEG # obsolete and meaningless, but just |
| 272 | # in case something decided to "use" it |
H. Peter Anvin | 6260731 | 2007-07-11 12:18:54 -0700 | [diff] [blame] | 273 | .word kernel_version-512 # pointing to kernel version string |
| 274 | # above section of header is compatible |
| 275 | # with loadlin-1.5 (header v1.5). Don't |
| 276 | # change it. |
| 277 | |
H. Peter Anvin | 5e47c47 | 2009-03-11 10:55:33 -0700 | [diff] [blame] | 278 | type_of_loader: .byte 0 # 0 means ancient bootloader, newer |
| 279 | # bootloaders know to change this. |
Paul Bolle | 395cf96 | 2011-08-15 02:02:26 +0200 | [diff] [blame] | 280 | # See Documentation/x86/boot.txt for |
H. Peter Anvin | 6260731 | 2007-07-11 12:18:54 -0700 | [diff] [blame] | 281 | # assigned ids |
| 282 | |
| 283 | # flags, unused bits must be zero (RFU) bit within loadflags |
| 284 | loadflags: |
| 285 | LOADED_HIGH = 1 # If set, the kernel is loaded high |
| 286 | CAN_USE_HEAP = 0x80 # If set, the loader also has set |
| 287 | # heap_end_ptr to tell how much |
| 288 | # space behind setup.S can be used for |
| 289 | # heap purposes. |
| 290 | # Only the loader knows what is free |
H. Peter Anvin | 6260731 | 2007-07-11 12:18:54 -0700 | [diff] [blame] | 291 | .byte LOADED_HIGH |
H. Peter Anvin | 6260731 | 2007-07-11 12:18:54 -0700 | [diff] [blame] | 292 | |
| 293 | setup_move_size: .word 0x8000 # size to move, when setup is not |
| 294 | # loaded at 0x90000. We will move setup |
| 295 | # to 0x90000 then just before jumping |
| 296 | # into the kernel. However, only the |
| 297 | # loader knows how much data behind |
| 298 | # us also needs to be loaded. |
| 299 | |
| 300 | code32_start: # here loaders can put a different |
| 301 | # start address for 32-bit code. |
H. Peter Anvin | 6260731 | 2007-07-11 12:18:54 -0700 | [diff] [blame] | 302 | .long 0x100000 # 0x100000 = default for big kernel |
H. Peter Anvin | 6260731 | 2007-07-11 12:18:54 -0700 | [diff] [blame] | 303 | |
| 304 | ramdisk_image: .long 0 # address of loaded ramdisk image |
| 305 | # Here the loader puts the 32-bit |
| 306 | # address where it loaded the image. |
| 307 | # This only will be read by the kernel. |
| 308 | |
| 309 | ramdisk_size: .long 0 # its size in bytes |
| 310 | |
| 311 | bootsect_kludge: |
| 312 | .long 0 # obsolete |
| 313 | |
H. Peter Anvin | 6b6815c | 2007-10-25 16:11:33 -0700 | [diff] [blame] | 314 | heap_end_ptr: .word _end+STACK_SIZE-512 |
| 315 | # (Header version 0x0201 or later) |
H. Peter Anvin | 6260731 | 2007-07-11 12:18:54 -0700 | [diff] [blame] | 316 | # space from here (exclusive) down to |
| 317 | # end of setup code can be used by setup |
| 318 | # for local heap purposes. |
| 319 | |
H. Peter Anvin | 5031296 | 2009-05-07 16:54:11 -0700 | [diff] [blame] | 320 | ext_loader_ver: |
| 321 | .byte 0 # Extended boot loader version |
| 322 | ext_loader_type: |
| 323 | .byte 0 # Extended boot loader type |
| 324 | |
H. Peter Anvin | 6260731 | 2007-07-11 12:18:54 -0700 | [diff] [blame] | 325 | cmd_line_ptr: .long 0 # (Header version 0x0202 or later) |
| 326 | # If nonzero, a 32-bit pointer |
| 327 | # to the kernel command line. |
| 328 | # The command line should be |
| 329 | # located between the start of |
| 330 | # setup and the end of low |
| 331 | # memory (0xa0000), or it may |
| 332 | # get overwritten before it |
| 333 | # gets read. If this field is |
| 334 | # used, there is no longer |
| 335 | # anything magical about the |
| 336 | # 0x90000 segment; the setup |
| 337 | # can be located anywhere in |
| 338 | # low memory 0x10000 or higher. |
| 339 | |
H. Peter Anvin | cf8fa92 | 2008-01-30 13:32:51 +0100 | [diff] [blame] | 340 | ramdisk_max: .long 0x7fffffff |
H. Peter Anvin | 6260731 | 2007-07-11 12:18:54 -0700 | [diff] [blame] | 341 | # (Header version 0x0203 or later) |
| 342 | # The highest safe address for |
| 343 | # the contents of an initrd |
H. Peter Anvin | cf8fa92 | 2008-01-30 13:32:51 +0100 | [diff] [blame] | 344 | # The current kernel allows up to 4 GB, |
| 345 | # but leave it at 2 GB to avoid |
| 346 | # possible bootloader bugs. |
H. Peter Anvin | 6260731 | 2007-07-11 12:18:54 -0700 | [diff] [blame] | 347 | |
| 348 | kernel_alignment: .long CONFIG_PHYSICAL_ALIGN #physical addr alignment |
| 349 | #required for protected mode |
| 350 | #kernel |
| 351 | #ifdef CONFIG_RELOCATABLE |
| 352 | relocatable_kernel: .byte 1 |
| 353 | #else |
| 354 | relocatable_kernel: .byte 0 |
| 355 | #endif |
H. Peter Anvin | 37ba7ab | 2009-05-11 15:56:08 -0700 | [diff] [blame] | 356 | min_alignment: .byte MIN_KERNEL_ALIGN_LG2 # minimum alignment |
H. Peter Anvin | 6260731 | 2007-07-11 12:18:54 -0700 | [diff] [blame] | 357 | pad3: .word 0 |
| 358 | |
| 359 | cmdline_size: .long COMMAND_LINE_SIZE-1 #length of the command line, |
| 360 | #added with boot protocol |
| 361 | #version 2.06 |
| 362 | |
Rusty Russell | a24e785 | 2007-10-21 16:41:35 -0700 | [diff] [blame] | 363 | hardware_subarch: .long 0 # subarchitecture, added with 2.07 |
| 364 | # default to 0 for normal x86 PC |
| 365 | |
| 366 | hardware_subarch_data: .quad 0 |
| 367 | |
H. Peter Anvin | 77d1a49 | 2009-05-11 14:21:12 -0700 | [diff] [blame] | 368 | payload_offset: .long ZO_input_data |
| 369 | payload_length: .long ZO_z_input_len |
Ian Campbell | 099e137 | 2008-02-13 20:54:58 +0000 | [diff] [blame] | 370 | |
Huang, Ying | 8b664aa | 2008-03-28 10:49:44 +0800 | [diff] [blame] | 371 | setup_data: .quad 0 # 64-bit physical pointer to |
| 372 | # single linked list of |
| 373 | # struct setup_data |
| 374 | |
H. Peter Anvin | 37ba7ab | 2009-05-11 15:56:08 -0700 | [diff] [blame] | 375 | pref_address: .quad LOAD_PHYSICAL_ADDR # preferred load addr |
| 376 | |
H. Peter Anvin | c6ac4c1 | 2009-05-20 11:26:09 -0700 | [diff] [blame] | 377 | #define ZO_INIT_SIZE (ZO__end - ZO_startup_32 + ZO_z_extract_offset) |
H. Peter Anvin | 37ba7ab | 2009-05-11 15:56:08 -0700 | [diff] [blame] | 378 | #define VO_INIT_SIZE (VO__end - VO__text) |
| 379 | #if ZO_INIT_SIZE > VO_INIT_SIZE |
| 380 | #define INIT_SIZE ZO_INIT_SIZE |
| 381 | #else |
| 382 | #define INIT_SIZE VO_INIT_SIZE |
| 383 | #endif |
| 384 | init_size: .long INIT_SIZE # kernel initialization size |
| 385 | |
H. Peter Anvin | 6260731 | 2007-07-11 12:18:54 -0700 | [diff] [blame] | 386 | # End of setup header ##################################################### |
| 387 | |
H. Peter Anvin | 7a734e7 | 2009-04-01 18:08:28 -0700 | [diff] [blame] | 388 | .section ".entrytext", "ax" |
H. Peter Anvin | 6260731 | 2007-07-11 12:18:54 -0700 | [diff] [blame] | 389 | start_of_setup: |
| 390 | #ifdef SAFE_RESET_DISK_CONTROLLER |
| 391 | # Reset the disk controller. |
| 392 | movw $0x0000, %ax # Reset disk controller |
| 393 | movb $0x80, %dl # All disks |
| 394 | int $0x13 |
| 395 | #endif |
| 396 | |
H. Peter Anvin | 6260731 | 2007-07-11 12:18:54 -0700 | [diff] [blame] | 397 | # Force %es = %ds |
| 398 | movw %ds, %ax |
| 399 | movw %ax, %es |
| 400 | cld |
| 401 | |
Jens Rottmann | 16252da | 2007-11-27 12:35:13 +0100 | [diff] [blame] | 402 | # Apparently some ancient versions of LILO invoked the kernel with %ss != %ds, |
| 403 | # which happened to work by accident for the old code. Recalculate the stack |
| 404 | # pointer if %ss is invalid. Otherwise leave it alone, LOADLIN sets up the |
| 405 | # stack behind its own code, so we can't blindly put it directly past the heap. |
H. Peter Anvin | 6b6815c | 2007-10-25 16:11:33 -0700 | [diff] [blame] | 406 | |
H. Peter Anvin | 6b6815c | 2007-10-25 16:11:33 -0700 | [diff] [blame] | 407 | movw %ss, %dx |
| 408 | cmpw %ax, %dx # %ds == %ss? |
| 409 | movw %sp, %dx |
Jens Rottmann | 16252da | 2007-11-27 12:35:13 +0100 | [diff] [blame] | 410 | je 2f # -> assume %sp is reasonably set |
H. Peter Anvin | 6b6815c | 2007-10-25 16:11:33 -0700 | [diff] [blame] | 411 | |
Jens Rottmann | 16252da | 2007-11-27 12:35:13 +0100 | [diff] [blame] | 412 | # Invalid %ss, make up a new stack |
| 413 | movw $_end, %dx |
| 414 | testb $CAN_USE_HEAP, loadflags |
| 415 | jz 1f |
| 416 | movw heap_end_ptr, %dx |
| 417 | 1: addw $STACK_SIZE, %dx |
| 418 | jnc 2f |
| 419 | xorw %dx, %dx # Prevent wraparound |
| 420 | |
| 421 | 2: # Now %dx should point to the end of our stack space |
H. Peter Anvin | 6b6815c | 2007-10-25 16:11:33 -0700 | [diff] [blame] | 422 | andw $~3, %dx # dword align (might as well...) |
| 423 | jnz 3f |
| 424 | movw $0xfffc, %dx # Make sure we're not zero |
Jens Rottmann | 16252da | 2007-11-27 12:35:13 +0100 | [diff] [blame] | 425 | 3: movw %ax, %ss |
H. Peter Anvin | 6b6815c | 2007-10-25 16:11:33 -0700 | [diff] [blame] | 426 | movzwl %dx, %esp # Clear upper half of %esp |
| 427 | sti # Now we should have a working stack |
| 428 | |
| 429 | # We will have entered with %cs = %ds+0x20, normalize %cs so |
| 430 | # it is on par with the other segments. |
| 431 | pushw %ds |
| 432 | pushw $6f |
| 433 | lretw |
| 434 | 6: |
H. Peter Anvin | 6260731 | 2007-07-11 12:18:54 -0700 | [diff] [blame] | 435 | |
| 436 | # Check signature at end of setup |
| 437 | cmpl $0x5a5aaa55, setup_sig |
| 438 | jne setup_bad |
| 439 | |
| 440 | # Zero the bss |
| 441 | movw $__bss_start, %di |
| 442 | movw $_end+3, %cx |
| 443 | xorl %eax, %eax |
| 444 | subw %di, %cx |
| 445 | shrw $2, %cx |
| 446 | rep; stosl |
| 447 | |
| 448 | # Jump to C code (should not return) |
| 449 | calll main |
| 450 | |
| 451 | # Setup corrupt somehow... |
| 452 | setup_bad: |
| 453 | movl $setup_corrupt, %eax |
| 454 | calll puts |
| 455 | # Fall through... |
| 456 | |
| 457 | .globl die |
| 458 | .type die, @function |
| 459 | die: |
| 460 | hlt |
| 461 | jmp die |
| 462 | |
Paul Bolle | bbc15f4 | 2007-09-10 23:39:02 +0200 | [diff] [blame] | 463 | .size die, .-die |
H. Peter Anvin | 6260731 | 2007-07-11 12:18:54 -0700 | [diff] [blame] | 464 | |
| 465 | .section ".initdata", "a" |
| 466 | setup_corrupt: |
| 467 | .byte 7 |
H. Peter Anvin | 8b608d2 | 2007-07-26 16:10:22 -0700 | [diff] [blame] | 468 | .string "No setup signature found...\n" |
Matt Fleming | 291f363 | 2011-12-12 21:27:52 +0000 | [diff] [blame] | 469 | |
| 470 | .data |
| 471 | dummy: .long 0 |
| 472 | |
| 473 | .section .reloc |
| 474 | reloc_start: |
| 475 | .long dummy - reloc_start |
| 476 | .long 10 |
| 477 | .word 0 |
| 478 | reloc_end: |