diff options
Diffstat (limited to 'arch/x86/lib/realmode_switch.S')
| -rw-r--r-- | arch/x86/lib/realmode_switch.S | 232 |
1 files changed, 0 insertions, 232 deletions
diff --git a/arch/x86/lib/realmode_switch.S b/arch/x86/lib/realmode_switch.S deleted file mode 100644 index c4c4c43..0000000 --- a/arch/x86/lib/realmode_switch.S +++ /dev/null @@ -1,232 +0,0 @@ -/* - * (C) Copyright 2002 - * Daniel Engström, Omicron Ceti AB, daniel@omicron.se - * - * See file CREDITS for list of people who contributed to this - * project. - * - * This program 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 2 of - * the License, or (at your option) any later version. - * - * This program 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 this program; if not, write to the Free Software - * Foundation, Inc., 59 Temple Place, Suite 330, Boston, - * MA 02111-1307 USA - */ - -/* 32bit -> 16bit -> 32bit mode switch code */ - -/* - * Stack frame at 0xe00 - * e00 ebx; - * e04 ecx; - * e08 edx; - * e0c esi; - * e10 edi; - * e14 ebp; - * e18 eax; - * e1c ds; - * e20 es; - * e24 fs; - * e28 gs; - * e2c orig_eax; - * e30 eip; - * e34 cs; - * e38 eflags; - * e3c esp; - * e40 ss; - */ - -#define a32 .byte 0x67; /* address size prefix 32 */ -#define o32 .byte 0x66; /* operand size prefix 32 */ - -.section .realmode, "ax" -.code16 - - /* 16bit protected mode code here */ -.globl realmode_enter -realmode_enter: -o32 pusha -o32 pushf - cli - sidt saved_idt - sgdt saved_gdt - movl %esp, %eax - movl %eax, saved_protected_mode_esp - - movl $0x10, %eax - movl %eax, %esp - movw $0x28, %ax - movw %ax, %ds - movw %ax, %es - movw %ax, %fs - movw %ax, %gs - - lidt realmode_idt_ptr - /* Go back into real mode by clearing PE to 0 */ - movl %cr0, %eax - andl $0x7ffffffe, %eax - movl %eax, %cr0 - - /* switch to real mode */ - ljmp $0x0,$do_realmode - -do_realmode: - /* realmode code from here */ - movw %cs,%ax - movw %ax,%ds - movw %ax,%es - movw %ax,%fs - movw %ax,%gs - - /* create a temporary stack */ - movw $0xc0, %ax - movw %ax, %ss - movw $0x200, %ax - movw %ax, %sp - - popl %ebx - popl %ecx - popl %edx - popl %esi - popl %edi - popl %ebp - popl %eax - movl %eax, temp_eax - popl %eax - movw %ax, %ds - popl %eax - movw %ax, %es - popl %eax - movw %ax, %fs - popl %eax - movw %ax, %gs - popl %eax /* orig_eax */ - popl %eax -cs movw %ax, temp_ip - popl %eax -cs movw %ax, temp_cs -o32 popf - popl %eax - popw %ss - movl %eax, %esp -cs movl temp_eax, %eax - - /* self-modifying code, better flush the cache */ - wbinvd - - .byte 0x9a /* lcall */ -temp_ip: - .word 0 /* new ip */ -temp_cs: - .word 0 /* new cs */ - -realmode_ret: - /* save eax, esp and ss */ -cs movl %eax, saved_eax - movl %esp, %eax -cs movl %eax, saved_esp - movw %ss, %ax -cs movw %ax, saved_ss - - /* - * restore the stack, note that we set sp to 0x244; - * pt_regs is 0x44 bytes long and we push the structure - * backwards on to the stack, bottom first - */ - movw $0xc0, %ax - movw %ax, %ss - movw $0x244, %ax - movw %ax, %sp - - xorl %eax,%eax -cs movw saved_ss, %ax - pushl %eax -cs movl saved_esp, %eax - pushl %eax -o32 pushf - xorl %eax,%eax -cs movw temp_cs, %ax - pushl %eax -cs movw temp_ip, %ax - pushl %eax - pushl $0 - movw %gs, %ax - pushl %eax - movw %fs, %ax - pushl %eax - movw %es, %ax - pushl %eax - movw %ds, %ax - pushl %eax - movl saved_eax, %eax - pushl %eax - pushl %ebp - pushl %edi - pushl %esi - pushl %edx - pushl %ecx - pushl %ebx - -o32 cs lidt saved_idt -o32 cs lgdt saved_gdt - - /* Go back into protected mode reset PE to 1 */ - movl %cr0, %eax - orl $1,%eax - movl %eax, %cr0 - - /* flush prefetch queue */ - jmp next_line -next_line: - movw $return_ptr, %ax - movw %ax,%bp -o32 cs ljmp *(%bp) - -.code32 -protected_mode: - /* Reload segment registers */ - movl $0x18, %eax - movw %ax, %fs - movw %ax, %ds - movw %ax, %gs - movw %ax, %es - movw %ax, %ss - movl saved_protected_mode_esp, %eax - movl %eax, %esp - popf - popa - ret - -temp_eax: - .long 0 - -saved_ss: - .word 0 -saved_esp: - .long 0 -saved_eax: - .long 0 - -realmode_idt_ptr: - .word 0x400 - .word 0x0, 0x0 - -saved_gdt: - .word 0, 0, 0, 0 -saved_idt: - .word 0, 0, 0, 0 - -saved_protected_mode_esp: - .long 0 - -return_ptr: - .long protected_mode - .word 0x10 |