diff options
Diffstat (limited to 'lib_i386/realmode_switch.S')
| -rw-r--r-- | lib_i386/realmode_switch.S | 100 |
1 files changed, 50 insertions, 50 deletions
diff --git a/lib_i386/realmode_switch.S b/lib_i386/realmode_switch.S index 17adcbd..0433cd4 100644 --- a/lib_i386/realmode_switch.S +++ b/lib_i386/realmode_switch.S @@ -1,7 +1,7 @@ /* * (C) Copyright 2002 * Daniel Engström, Omicron Ceti AB, daniel@omicron.se - * + * * See file CREDITS for list of people who contributed to this * project. * @@ -31,11 +31,11 @@ * e08 edx; * e0c esi; * e10 edi; - * e14 ebp; + * e14 ebp; * e18 eax; - * e1c ds; + * e1c ds; * e20 es; - * e24 fs; + * e24 fs; * e28 gs; * e2c orig_eax; * e30 eip; @@ -46,7 +46,7 @@ */ #define a32 .byte 0x67; /* address size prefix 32 */ -#define o32 .byte 0x66; /* operand size prefix 32 */ +#define o32 .byte 0x66; /* operand size prefix 32 */ .section .realmode, "ax" .code16 @@ -56,11 +56,11 @@ realmode_enter: o32 pusha o32 pushf cli - sidt saved_idt - sgdt saved_gdt - movl %esp, %eax - movl %eax, saved_protected_mode_esp - + sidt saved_idt + sgdt saved_gdt + movl %esp, %eax + movl %eax, saved_protected_mode_esp + movl $0x10, %eax movl %eax, %esp movw $0x28, %ax @@ -74,21 +74,21 @@ o32 pushf andl $0x7ffffffe, %eax /* clearing PE to 0 */ movl %eax, %cr0 ljmp $0x0,$do_realmode /* switch to real mode */ - -do_realmode: /* realmode code from here */ + +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 - + + movw $0xc0, %ax + movw %ax, %ss + movw $0x200, %ax + movw %ax, %sp + popl %ebx popl %ecx popl %edx @@ -117,11 +117,11 @@ o32 popf cs movl temp_eax, %eax wbinvd /* self-modifying code, * better flush the cache */ - + .byte 0x9a /* lcall */ temp_ip: .word 0 /* new ip */ -temp_cs: +temp_cs: .word 0 /* new cs */ realmode_ret: /* save eax, esp and ss */ @@ -130,16 +130,16 @@ cs movl %eax, saved_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 - + + movw $0xc0, %ax + movw %ax, %ss + movw $0x244, %ax + movw %ax, %sp + xorl %eax,%eax cs movw saved_ss, %ax pushl %eax @@ -172,28 +172,28 @@ cs movw temp_ip, %ax o32 cs lidt saved_idt o32 cs lgdt saved_gdt /* Set GDTR */ - movl %cr0, %eax /* Go back into protected mode */ - orl $1,%eax /* reset PE to 1 */ - movl %eax, %cr0 - jmp next_line /* flush prefetch queue */ -next_line: - movw $return_ptr, %ax - movw %ax,%bp + movl %cr0, %eax /* Go back into protected mode */ + orl $1,%eax /* reset PE to 1 */ + movl %eax, %cr0 + jmp next_line /* flush prefetch queue */ +next_line: + movw $return_ptr, %ax + movw %ax,%bp o32 cs ljmp *(%bp) .code32 protected_mode: - movl $0x18,%eax /* reload GDT[3] */ - movw %ax,%fs /* reset FS */ + movl $0x18,%eax /* reload GDT[3] */ + movw %ax,%fs /* reset FS */ movw %ax,%ds /* reset DS */ - movw %ax,%gs /* reset GS */ - movw %ax,%es /* reset ES */ - movw %ax,%ss /* reset SS */ - movl saved_protected_mode_esp, %eax + movw %ax,%gs /* reset GS */ + movw %ax,%es /* reset ES */ + movw %ax,%ss /* reset SS */ + movl saved_protected_mode_esp, %eax movl %eax, %esp popf popa - ret + ret temp_eax: .long 0 @@ -204,19 +204,19 @@ saved_esp: .long 0 saved_eax: .long 0 - + realmode_idt_ptr: - .word 0x400 - .word 0x0, 0x0 - -saved_gdt: - .word 0, 0, 0, 0 + .word 0x400 + .word 0x0, 0x0 + +saved_gdt: + .word 0, 0, 0, 0 saved_idt: - .word 0, 0, 0, 0 + .word 0, 0, 0, 0 saved_protected_mode_esp: .long 0 - + return_ptr: .long protected_mode .word 0x10 |