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
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
|
/* SPDX-License-Identifier: GPL-2.0-only */
/* SPDX-FileCopyrightText: 1991,1992 Linus Torvalds */
/* SPDX-FileCopyrightText: 2007 rPath, Inc. */
/**
* @file
* @brief The actual transition into protected mode
*
* Note: This function is running in flat and real mode. Due to some
* other restrictions it must running from an address space below 0x10000
*/
/**
* @fn void protected_mode_jump(void)
* @brief Switches the first time from real mode to flat mode
*/
#include <asm/modes.h>
#include "boot.h"
.file "pmjump.S"
.code16
.section .boot.text.protected_mode_jump, "ax"
.globl protected_mode_jump
.type protected_mode_jump, @function
protected_mode_jump:
jmp 1f /* Short jump to serialize on 386/486 */
1:
movw $__BOOT_DS, %cx
movw $__BOOT_TSS, %di
movl %cr0, %edx
orb $X86_CR0_PE, %dl /* enable protected mode */
movl %edx, %cr0
/* Transition to 32-bit flat mode */
data32 ljmp $__BOOT_CS, $in_pm32
.size protected_mode_jump, .-protected_mode_jump
/* ------------------------------------------------------------------------ */
.section ".text.in_pm32","ax"
.code32
.extern uboot_entry
.extern __bss_stop
.type in_pm32, @function
in_pm32:
# Set up data segments for flat 32-bit mode
movl %ecx, %ds
movl %ecx, %es
movl %ecx, %fs
movl %ecx, %gs
movl %ecx, %ss
/*
* Our flat mode code uses its own stack area behind the bss. With this we
* are still able to return to real mode temporarely
*/
movl $__bss_stop + 32768, %esp
# Set up TR to make Intel VT happy
ltr %di
# Clear registers to allow for future extensions to the
# 32-bit boot protocol
xorl %ecx, %ecx
xorl %edx, %edx
xorl %ebx, %ebx
xorl %ebp, %ebp
xorl %edi, %edi
# Set up LDTR to make Intel VT happy
lldt %cx
jmp uboot_entry
.size in_pm32, .-in_pm32
|
