1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
|
/* ----------------------------------------------------------------------- *
*
* Copyright (C) 1991, 1992 Linus Torvalds
* Copyright 2007 rPath, Inc. - All Rights Reserved
*
* This file is part of the Linux kernel, and is made available under
* the terms of the GNU General Public License version 2.
*
* ----------------------------------------------------------------------- */
/*
* arch/i386/boot/pmjump.S
*
* The actual transition into protected mode
*/
#include <asm/boot.h>
#include <asm/segment.h>
.text
.globl protected_mode_jump
.type protected_mode_jump, @function
.code16
/*
* void protected_mode_jump(u32 entrypoint, u32 bootparams);
*/
protected_mode_jump:
xorl %ebx, %ebx # Flag to indicate this is a boot
movl %edx, %esi # Pointer to boot_params table
movl %eax, 2f # Patch ljmpl instruction
movw $__BOOT_DS, %cx
movl %cr0, %edx
orb $1, %dl # Protected mode (PE) bit
movl %edx, %cr0
jmp 1f # Short jump to serialize on 386/486
1:
movw %cx, %ds
movw %cx, %es
movw %cx, %fs
movw %cx, %gs
movw %cx, %ss
# Jump to the 32-bit entrypoint
.byte 0x66, 0xea # ljmpl opcode
2: .long 0 # offset
.word __BOOT_CS # segment
.size protected_mode_jump, .-protected_mode_jump
|
