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
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
|
.code32
.extern begin_long_mode
.section .boot32.text, "a"
.global _start
_start:
cli
mov $stack_top, %esp
pushl $0
pushl %eax
pushl $0
pushl %ebx
call setup_page_tables
call enable_paging
lgdt gdtp
ljmp $0x08, $begin_long_mode
setup_page_tables:
// first 2mb
mov $pt_lvl3, %eax
or $0x3, %eax
mov %eax, pt_lvl4
mov $pt_lvl2, %eax
or $0x3, %eax
mov %eax, pt_lvl3
xor %ecx, %ecx
1:
movl $0x00200000, %eax
mul %ecx
or $0b10000011, %eax
movl $pt_lvl2, %edx
leal (%edx, %ecx, 8), %edx
movl %eax, (%edx)
inc %ecx
cmp $1, %ecx
jne 1b
// first 2mb in hh
mov $pt_lvl3_hh, %eax
or $0x3, %eax
mov %eax, pt_lvl4 + 4096 - 8
mov $pt_lvl2_hh, %eax
or $0x3, %eax
mov %eax, pt_lvl3_hh + 4096 - 16
xor %ecx, %ecx
2:
movl $0x00200000, %eax
mul %ecx
or $0b10000011, %eax
movl $pt_lvl2_hh, %edx
leal (%edx, %ecx, 8), %edx
movl %eax, (%edx)
inc %ecx
cmp $1, %ecx
jne 2b
ret
enable_paging:
// enable PAE
mov %cr4, %edx
or $1<<5 ,%edx
mov %edx, %cr4
// set LME (long mode enable)
mov $0xC0000080, %ecx
rdmsr
or $1<<8, %eax
wrmsr
// pt_lvl4
mov $pt_lvl4, %eax
mov %eax, %cr3
// enable paging (+ protected mode if not already enabled)
mov %cr0, %eax
or $1<<31 + 1<<0, %eax
mov %eax, %cr0
ret
.section .boot32.rodata
gdt:
gdt_null = . - gdt
.quad 0
gdt_code = . - gdt
.long 0xFFFF
.byte 0
.byte 0x9A
.byte 0xAF
.byte 0
gdt_data = . - gdt
.long 0xFFFF
.byte 0
.byte 0xA2
.byte 0xAF
.byte 0
gdtp:
.word . - gdt - 1
.quad gdt
.section .boot32.bss
.align 4096
pt_lvl4:
.skip 4096
pt_lvl3:
.skip 4096
pt_lvl3_hh:
.skip 4096
pt_lvl2:
.skip 4096
pt_lvl2_hh:
.skip 4096
stack_bottom:
.skip 4096*4
stack_top:
|
