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
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
|
bits 32
global syscall_isr
global quit_isr
global yield_isr
global _start_user_mode
global kbd_isr
global udf_isr
global dfa_isr
global tsf_isr
global npf_isr
global ssf_isr
global gpf_isr
global pff_isr
extern syscall_table
extern active_task
extern delete_task
extern advance_active_task
extern on_kbd_isr
extern make_sure_tasks
extern exception_halt
n_syscalls equ 0xf
;section .bss
;_debug_is_start_task resb 1
;extern switch_to_kernel_cr3
;extern switch_to_task_cr3
section .text
syscall_isr:
cmp eax, n_syscalls
jge .bad
; mov byte [_debug_is_start_task], 0
; cmp eax, 0x4
; jne .dont_set_debug
; mov byte [_debug_is_start_task], 1
;.dont_set_debug:
mov eax, dword [syscall_table + eax * 4]
push edi
push esi
push edx
push ecx
push ebx
call eax
add esp, 20
; cmp byte [_debug_is_start_task], 0
; je .dont_do_debug
; push eax
; call switch_to_kernel_cr3
; jmp $
; call switch_to_task_cr3
; pop eax
;.dont_do_debug:
._before_return:
iret
.bad:
mov eax, -1
iret
quit_isr:
push dword [active_task]
call delete_task
call make_sure_tasks
mov dword [esp], yield_isr.return_to_task
jmp advance_active_task
yield_isr:
mov eax, dword [active_task]
mov dword [eax + 8], ebx
mov dword [eax + 12], ecx
mov dword [eax + 16], edx
mov dword [eax + 20], esi
mov dword [eax + 24], edi
mov dword [eax + 28], ebp
mov edx, dword [esp]
mov dword [eax], edx
mov edx, cr3
mov dword [eax + 4], edx
mov edx, dword [esp + 12]
mov dword [eax + 32], edx
call advance_active_task
.return_to_task:
mov eax, dword [active_task]
mov edx, dword [eax]
mov dword [esp], edx
mov edx, dword [eax + 4]
mov cr3, edx
mov edx, dword [eax + 32]
mov dword [esp + 12], edx
mov ebx, dword [eax + 8]
mov ecx, dword [eax + 12]
mov edx, dword [eax + 16]
mov esi, dword [eax + 20]
mov edi, dword [eax + 24]
mov ebp, dword [eax + 28]
._before_return:
iret
_start_user_mode:
mov ax, 0x2b
mov ds, ax
mov es, ax
push dword 0x2b
sub esp, 4
push dword 0x00000200;interrupt flag
push dword 0x23
sub esp, 4
jmp yield_isr.return_to_task
kbd_isr:
push eax
push ecx
push edx
call on_kbd_isr
mov al, 0x20
out 0x0020, al
pop edx
pop ecx
pop eax
iret
udf_isr:
push 0
push udid
call exception_halt
dfa_isr:
push dfid
call exception_halt
tsf_isr:
push tsid
call exception_halt
npf_isr:
push npid
call exception_halt
ssf_isr:
push ssid
call exception_halt
gpf_isr:
push gpid
call exception_halt
pff_isr:
push pfid
call exception_halt
section .rodata
udid db "UD", 0
dfid db "DF", 0
tsid db "TS", 0
npid db "NP", 0
ssid db "SS", 0
gpid db "GP", 0
pfid db "PF", 0
|