grub-lakitu/grub-core/boot/i386/pc/startup_raw.S - cos/cobble - Git at Google

 /*
  *  GRUB  --  GRand Unified Bootloader
  *  Copyright (C) 1999,2000,2001,2002,2003,2005,2006,2007,2008,2009,2011 Free Software Foundation, Inc.
  *
  *  GRUB is free software: you can redistribute it and/or modify
  *  it under the terms of the GNU General Public License as published by
  *  the Free Software Foundation, either version 3 of the License, or
  *  (at your option) any later version.
  *
  *  GRUB is distributed in the hope that it will be useful,
  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  *  GNU General Public License for more details.
  *
  *  You should have received a copy of the GNU General Public License
  *  along with GRUB.  If not, see <http://www.gnu.org/licenses/>.
  */

 #include <config.h>
 #include <grub/symbol.h>
 #include <grub/offsets.h>
 #include <grub/machine/boot.h>
 #include <grub/machine/memory.h>
 #include <grub/machine/kernel.h>

 #define ABS(x)	((x) - LOCAL (base) + GRUB_BOOT_MACHINE_KERNEL_ADDR + 0x200)

 	.file	"startup_raw.S"

 	.text

 	/* Tell GAS to generate 16-bit instructions so that this code works
 	   in real mode. */
 	.code16

 	.globl	start, _start
 start:
 _start:
 LOCAL (base):
 	/*
 	 *  Guarantee that "main" is loaded at 0x0:0x8200.
 	 */
 #ifdef __APPLE__
 	ljmp $0, $(ABS(LOCAL (codestart)) - 0x10000)
 #else
 	ljmp $0, $ABS(LOCAL (codestart))
 #endif

 	/*
 	 *  This is a special data area.
 	 */

 	.org GRUB_DECOMPRESSOR_MACHINE_COMPRESSED_SIZE
 LOCAL(compressed_size):
 	.long 0
 	.org GRUB_DECOMPRESSOR_MACHINE_UNCOMPRESSED_SIZE
 LOCAL(uncompressed_size):
 	.long 0

 	.org GRUB_KERNEL_I386_PC_REED_SOLOMON_REDUNDANCY
 reed_solomon_redundancy:
 	.long	0
 	.org GRUB_KERNEL_I386_PC_NO_REED_SOLOMON_LENGTH
 	.short	(LOCAL(reed_solomon_part) - _start)

 /*
  *  This is the area for all of the special variables.
  */
 	.org GRUB_DECOMPRESSOR_I386_PC_BOOT_DEVICE
 LOCAL(boot_dev):
 	.byte	0xFF, 0xFF, 0xFF
 LOCAL(boot_drive):
 	.byte	0x00

 /* the real mode code continues... */
 LOCAL (codestart):
 	cli		/* we're not safe here! */

 	/* set up %ds, %ss, and %es */
 	xorw	%ax, %ax
 	movw	%ax, %ds
 	movw	%ax, %ss
 	movw	%ax, %es

 	/* set up the real mode/BIOS stack */
 	movl	$GRUB_MEMORY_MACHINE_REAL_STACK, %ebp
 	movl	%ebp, %esp

 	sti		/* we're safe again */

 	/* save the boot drive */
 	movb	%dl, LOCAL(boot_drive)

 	/* reset disk system (%ah = 0) */
 	int	$0x13

 	/* transition to protected mode */
 	calll	real_to_prot

 	/* The ".code32" directive takes GAS out of 16-bit mode. */
 	.code32

 	cld
 	call	grub_gate_a20

 	movl	LOCAL(compressed_size), %edx
 #ifdef __APPLE__
 	addl    $decompressor_end, %edx
 	subl    $(LOCAL(reed_solomon_part)), %edx
 #else
 	addl    $(LOCAL(decompressor_end) - LOCAL(reed_solomon_part)), %edx
 #endif
 	movl    reed_solomon_redundancy, %ecx
 	leal    LOCAL(reed_solomon_part), %eax
 	cld
 	call    EXT_C (grub_reed_solomon_recover)
 	jmp	post_reed_solomon

 #include "../../../kern/i386/realmode.S"

 #include <rs_decoder.h>

 	.text

 /*
  * grub_gate_a20(void)
  *
  * Gate address-line 20 for high memory.
  *
  * This routine is probably overconservative in what it does, but so what?
  *
  * It also eats any keystrokes in the keyboard buffer.  :-(
  */

 grub_gate_a20:
 gate_a20_test_current_state:
 	/* first of all, test if already in a good state */
 	call	gate_a20_check_state
 	testb	%al, %al
 	jnz	gate_a20_try_bios
 	ret

 gate_a20_try_bios:
 	/* second, try a BIOS call */
 	pushl	%ebp
 	call	prot_to_real

 	.code16
 	movw	$0x2401, %ax
 	int	$0x15

 	calll	real_to_prot
 	.code32

 	popl	%ebp
 	call	gate_a20_check_state
 	testb	%al, %al
 	jnz	gate_a20_try_system_control_port_a
 	ret

 gate_a20_try_system_control_port_a:
 	/*
 	 * In macbook, the keyboard test would hang the machine, so we move
 	 * this forward.
 	 */
 	/* fourth, try the system control port A */
 	inb	$0x92
 	andb	$(~0x03), %al
 	orb	$0x02, %al
 	outb	$0x92

 	call	gate_a20_check_state
 	testb	%al, %al
 	jnz	gate_a20_try_keyboard_controller
 	ret

 gate_a20_flush_keyboard_buffer:
 	inb	$0x64
 	andb	$0x02, %al
 	jnz	gate_a20_flush_keyboard_buffer
 2:
 	inb	$0x64
 	andb	$0x01, %al
 	jz	3f
 	inb	$0x60
 	jmp	2b
 3:
 	ret

 gate_a20_try_keyboard_controller:
 	/* third, try the keyboard controller */
 	call    gate_a20_flush_keyboard_buffer

 	movb	$0xd1, %al
 	outb	$0x64
 4:
 	inb	$0x64
 	andb	$0x02, %al
 	jnz	4b

 	movb	$0xdf, %al
 	outb	$0x60
 	call    gate_a20_flush_keyboard_buffer

 	/* output a dummy command (USB keyboard hack) */
 	movb	$0xff, %al
 	outb	$0x64
 	call    gate_a20_flush_keyboard_buffer

 	call	gate_a20_check_state
 	testb	%al, %al
 	/* everything failed, so restart from the beginning */
 	jnz	gate_a20_try_bios
 	ret

 gate_a20_check_state:
 	/* iterate the checking for a while */
 	movl	$100, %ecx
 1:
 	call	3f
 	testb	%al, %al
 	jz	2f
 	loop	1b
 2:
 	ret
 3:
 	pushl	%ebx
 	pushl	%ecx
 	xorl	%eax, %eax
 	/* compare the byte at 0x8000 with that at 0x108000 */
 	movl	$GRUB_BOOT_MACHINE_KERNEL_ADDR, %ebx
 	pushl	%ebx
 	/* save the original byte in CL */
 	movb	(%ebx), %cl
 	/* store the value at 0x108000 in AL */
 	addl	$0x100000, %ebx
 	movb	(%ebx), %al
 	/* try to set one less value at 0x8000 */
 	popl	%ebx
 	movb	%al, %ch
 	decb	%ch
 	movb	%ch, (%ebx)
 	/* serialize */
 	outb	%al, $0x80
 	outb	%al, $0x80
 	/* obtain the value at 0x108000 in CH */
 	pushl	%ebx
 	addl	$0x100000, %ebx
 	movb	(%ebx), %ch
 	/* this result is 0 if A20 is on or 1 if it is off */
 	subb	%ch, %al
 	/* restore the original */
 	popl	%ebx
 	movb	%cl, (%ebx)
 	popl	%ecx
 	popl	%ebx
 	ret

 LOCAL(reed_solomon_part):

 /*
  * Support for booting GRUB from a Multiboot boot loader (e.g. GRUB itself).
  * This uses the a.out kludge to load raw binary to the area starting at 1MB,
  * and relocates itself after loaded.
  */
 	.p2align	2	/* force 4-byte alignment */
 multiboot_header:
 	/* magic */
 	.long	0x1BADB002
 	/* flags */
 	.long	(1 << 16)
 	/* checksum */
 	.long	-0x1BADB002 - (1 << 16)
 	/* header addr */
 	.long	multiboot_header - _start + 0x100000 + 0x200
 	/* load addr */
 	.long	0x100000
 	/* load end addr */
 	.long	0
 	/* bss end addr */
 	.long	0
 	/* entry addr */
 	.long	multiboot_entry - _start + 0x100000 + 0x200

 multiboot_entry:
 	.code32
 	/* obtain the boot device */
 	movl	12(%ebx), %edx

 	movl	$GRUB_MEMORY_MACHINE_PROT_STACK, %ebp
 	movl	%ebp, %esp

 	/* relocate the code */
 #ifdef __APPLE__
 	LOCAL(compressed_size_offset) = LOCAL(compressed_size) - LOCAL(base)
 	movl	$0x200, %ecx
 	addl    $decompressor_end, %ecx
 	subl    $LOCAL(base), %ecx
 	addl	LOCAL(compressed_size_offset) + 0x100000 + 0x200, %ecx
 #else
 	movl	$(LOCAL(decompressor_end) - _start + 0x200), %ecx
 	addl	LOCAL(compressed_size) - _start + 0x100000 + 0x200, %ecx
 #endif
 	movl	$0x100000, %esi
 	movl	$GRUB_BOOT_MACHINE_KERNEL_ADDR, %edi
 	cld
 	rep
 	movsb
 	/* jump to the real address */
 	movl	$multiboot_trampoline, %eax
 	jmp	*%eax

 multiboot_trampoline:
 	/* fill the boot information */
 	movl	%edx, LOCAL(boot_dev)
 	shrl	$24, %edx
 	/* enter the usual booting */
 	call	prot_to_real
 	.code16
 	jmp     LOCAL (codestart)
 	.code32

 post_reed_solomon:

 #ifdef ENABLE_LZMA
 	movl	$GRUB_MEMORY_MACHINE_DECOMPRESSION_ADDR, %edi
 #ifdef __APPLE__
 	movl	$decompressor_end, %esi
 #else
 	movl	$LOCAL(decompressor_end), %esi
 #endif
 	pushl	%edi
 	movl	LOCAL (uncompressed_size), %ecx
 	leal	(%edi, %ecx), %ebx
 	/* Don't remove this push: it's an argument.  */
 	push 	%ecx
 	call	_LzmaDecodeA
 	pop	%ecx
 	/* _LzmaDecodeA clears DF, so no need to run cld */
 	popl	%esi
 #endif

 	movl	LOCAL(boot_dev), %edx
 	movl	$prot_to_real, %edi
 	movl	$real_to_prot, %ecx
 	movl	$LOCAL(realidt), %eax
 	jmp	*%esi

 #ifdef ENABLE_LZMA
 #include "lzma_decode.S"
 #endif

 	.p2align 4

 #ifdef __APPLE__
 	.zerofill __DATA, __aa_before_bss, decompressor_end, 10, 0
 #else
 	.bss
 LOCAL(decompressor_end):
 #endif
	/*
	* GRUB -- GRand Unified Bootloader
	* Copyright (C) 1999,2000,2001,2002,2003,2005,2006,2007,2008,2009,2011 Free Software Foundation, Inc.
	*
	* GRUB is free software: you can redistribute it and/or modify
	* it under the terms of the GNU General Public License as published by
	* the Free Software Foundation, either version 3 of the License, or
	* (at your option) any later version.
	*
	* GRUB is distributed in the hope that it will be useful,
	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	* GNU General Public License for more details.
	*
	* You should have received a copy of the GNU General Public License
	* along with GRUB. If not, see <http://www.gnu.org/licenses/>.
	*/

	#include <config.h>
	#include <grub/symbol.h>
	#include <grub/offsets.h>
	#include <grub/machine/boot.h>
	#include <grub/machine/memory.h>
	#include <grub/machine/kernel.h>

	#define ABS(x) ((x) - LOCAL (base) + GRUB_BOOT_MACHINE_KERNEL_ADDR + 0x200)

	.file "startup_raw.S"

	.text

	/* Tell GAS to generate 16-bit instructions so that this code works
	in real mode. */
	.code16

	.globl start, _start
	start:
	_start:
	LOCAL (base):
	/*
	* Guarantee that "main" is loaded at 0x0:0x8200.
	*/
	#ifdef __APPLE__
	ljmp $0, $(ABS(LOCAL (codestart)) - 0x10000)
	#else
	ljmp $0, $ABS(LOCAL (codestart))
	#endif

	/*
	* This is a special data area.
	*/

	.org GRUB_DECOMPRESSOR_MACHINE_COMPRESSED_SIZE
	LOCAL(compressed_size):
	.long 0
	.org GRUB_DECOMPRESSOR_MACHINE_UNCOMPRESSED_SIZE
	LOCAL(uncompressed_size):
	.long 0

	.org GRUB_KERNEL_I386_PC_REED_SOLOMON_REDUNDANCY
	reed_solomon_redundancy:
	.long 0
	.org GRUB_KERNEL_I386_PC_NO_REED_SOLOMON_LENGTH
	.short (LOCAL(reed_solomon_part) - _start)

	/*
	* This is the area for all of the special variables.
	*/
	.org GRUB_DECOMPRESSOR_I386_PC_BOOT_DEVICE
	LOCAL(boot_dev):
	.byte 0xFF, 0xFF, 0xFF
	LOCAL(boot_drive):
	.byte 0x00

	/* the real mode code continues... */
	LOCAL (codestart):
	cli /* we're not safe here! */

	/* set up %ds, %ss, and %es */
	xorw %ax, %ax
	movw %ax, %ds
	movw %ax, %ss
	movw %ax, %es

	/* set up the real mode/BIOS stack */
	movl $GRUB_MEMORY_MACHINE_REAL_STACK, %ebp
	movl %ebp, %esp

	sti /* we're safe again */

	/* save the boot drive */
	movb %dl, LOCAL(boot_drive)

	/* reset disk system (%ah = 0) */
	int $0x13

	/* transition to protected mode */
	calll real_to_prot

	/* The ".code32" directive takes GAS out of 16-bit mode. */
	.code32

	cld
	call grub_gate_a20

	movl LOCAL(compressed_size), %edx
	#ifdef __APPLE__
	addl $decompressor_end, %edx
	subl $(LOCAL(reed_solomon_part)), %edx
	#else
	addl $(LOCAL(decompressor_end) - LOCAL(reed_solomon_part)), %edx
	#endif
	movl reed_solomon_redundancy, %ecx
	leal LOCAL(reed_solomon_part), %eax
	cld
	call EXT_C (grub_reed_solomon_recover)
	jmp post_reed_solomon

	#include "../../../kern/i386/realmode.S"

	#include <rs_decoder.h>

	.text

	/*
	* grub_gate_a20(void)
	*
	* Gate address-line 20 for high memory.
	*
	* This routine is probably overconservative in what it does, but so what?
	*
	* It also eats any keystrokes in the keyboard buffer. :-(
	*/

	grub_gate_a20:
	gate_a20_test_current_state:
	/* first of all, test if already in a good state */
	call gate_a20_check_state
	testb %al, %al
	jnz gate_a20_try_bios
	ret

	gate_a20_try_bios:
	/* second, try a BIOS call */
	pushl %ebp
	call prot_to_real

	.code16
	movw $0x2401, %ax
	int $0x15

	calll real_to_prot
	.code32

	popl %ebp
	call gate_a20_check_state
	testb %al, %al
	jnz gate_a20_try_system_control_port_a
	ret

	gate_a20_try_system_control_port_a:
	/*
	* In macbook, the keyboard test would hang the machine, so we move
	* this forward.
	*/
	/* fourth, try the system control port A */
	inb $0x92
	andb $(~0x03), %al
	orb $0x02, %al
	outb $0x92

	call gate_a20_check_state
	testb %al, %al
	jnz gate_a20_try_keyboard_controller
	ret

	gate_a20_flush_keyboard_buffer:
	inb $0x64
	andb $0x02, %al
	jnz gate_a20_flush_keyboard_buffer
	2:
	inb $0x64
	andb $0x01, %al
	jz 3f
	inb $0x60
	jmp 2b
	3:
	ret

	gate_a20_try_keyboard_controller:
	/* third, try the keyboard controller */
	call gate_a20_flush_keyboard_buffer

	movb $0xd1, %al
	outb $0x64
	4:
	inb $0x64
	andb $0x02, %al
	jnz 4b

	movb $0xdf, %al
	outb $0x60
	call gate_a20_flush_keyboard_buffer

	/* output a dummy command (USB keyboard hack) */
	movb $0xff, %al
	outb $0x64
	call gate_a20_flush_keyboard_buffer

	call gate_a20_check_state
	testb %al, %al
	/* everything failed, so restart from the beginning */
	jnz gate_a20_try_bios
	ret

	gate_a20_check_state:
	/* iterate the checking for a while */
	movl $100, %ecx
	1:
	call 3f
	testb %al, %al
	jz 2f
	loop 1b
	2:
	ret
	3:
	pushl %ebx
	pushl %ecx
	xorl %eax, %eax
	/* compare the byte at 0x8000 with that at 0x108000 */
	movl $GRUB_BOOT_MACHINE_KERNEL_ADDR, %ebx
	pushl %ebx
	/* save the original byte in CL */
	movb (%ebx), %cl
	/* store the value at 0x108000 in AL */
	addl $0x100000, %ebx
	movb (%ebx), %al
	/* try to set one less value at 0x8000 */
	popl %ebx
	movb %al, %ch
	decb %ch
	movb %ch, (%ebx)
	/* serialize */
	outb %al, $0x80
	outb %al, $0x80
	/* obtain the value at 0x108000 in CH */
	pushl %ebx
	addl $0x100000, %ebx
	movb (%ebx), %ch
	/* this result is 0 if A20 is on or 1 if it is off */
	subb %ch, %al
	/* restore the original */
	popl %ebx
	movb %cl, (%ebx)
	popl %ecx
	popl %ebx
	ret

	LOCAL(reed_solomon_part):

	/*
	* Support for booting GRUB from a Multiboot boot loader (e.g. GRUB itself).
	* This uses the a.out kludge to load raw binary to the area starting at 1MB,
	* and relocates itself after loaded.
	*/
	.p2align 2 /* force 4-byte alignment */
	multiboot_header:
	/* magic */
	.long 0x1BADB002
	/* flags */
	.long (1 << 16)
	/* checksum */
	.long -0x1BADB002 - (1 << 16)
	/* header addr */
	.long multiboot_header - _start + 0x100000 + 0x200
	/* load addr */
	.long 0x100000
	/* load end addr */
	.long 0
	/* bss end addr */
	.long 0
	/* entry addr */
	.long multiboot_entry - _start + 0x100000 + 0x200

	multiboot_entry:
	.code32
	/* obtain the boot device */
	movl 12(%ebx), %edx

	movl $GRUB_MEMORY_MACHINE_PROT_STACK, %ebp
	movl %ebp, %esp

	/* relocate the code */
	#ifdef __APPLE__
	LOCAL(compressed_size_offset) = LOCAL(compressed_size) - LOCAL(base)
	movl $0x200, %ecx
	addl $decompressor_end, %ecx
	subl $LOCAL(base), %ecx
	addl LOCAL(compressed_size_offset) + 0x100000 + 0x200, %ecx
	#else
	movl $(LOCAL(decompressor_end) - _start + 0x200), %ecx
	addl LOCAL(compressed_size) - _start + 0x100000 + 0x200, %ecx
	#endif
	movl $0x100000, %esi
	movl $GRUB_BOOT_MACHINE_KERNEL_ADDR, %edi
	cld
	rep
	movsb
	/* jump to the real address */
	movl $multiboot_trampoline, %eax
	jmp *%eax

	multiboot_trampoline:
	/* fill the boot information */
	movl %edx, LOCAL(boot_dev)
	shrl $24, %edx
	/* enter the usual booting */
	call prot_to_real
	.code16
	jmp LOCAL (codestart)
	.code32

	post_reed_solomon:

	#ifdef ENABLE_LZMA
	movl $GRUB_MEMORY_MACHINE_DECOMPRESSION_ADDR, %edi
	#ifdef __APPLE__
	movl $decompressor_end, %esi
	#else
	movl $LOCAL(decompressor_end), %esi
	#endif
	pushl %edi
	movl LOCAL (uncompressed_size), %ecx
	leal (%edi, %ecx), %ebx
	/* Don't remove this push: it's an argument. */
	push %ecx
	call _LzmaDecodeA
	pop %ecx
	/* _LzmaDecodeA clears DF, so no need to run cld */
	popl %esi
	#endif

	movl LOCAL(boot_dev), %edx
	movl $prot_to_real, %edi
	movl $real_to_prot, %ecx
	movl $LOCAL(realidt), %eax
	jmp *%esi

	#ifdef ENABLE_LZMA
	#include "lzma_decode.S"
	#endif

	.p2align 4

	#ifdef __APPLE__
	.zerofill __DATA, __aa_before_bss, decompressor_end, 10, 0
	#else
	.bss
	LOCAL(decompressor_end):
	#endif