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
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
|
TITLE LongMode.asm: Assembly code for the entering long mode
;------------------------------------------------------------------------------
;*
;* Copyright (c) 2006, Intel Corporation
;* All rights reserved. This program and the accompanying materials
;* are licensed and made available under the terms and conditions of the BSD License
;* which accompanies this distribution. The full text of the license may be found at
;* http://opensource.org/licenses/bsd-license.php
;*
;* THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
;* WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
;*
;* LongMode.asm
;*
;* Abstract:
;*
;* Transition from 32-bit protected mode EFI environment into x64
;* 64-bit bit long mode.
;*
;------------------------------------------------------------------------------
.686p
.model flat
;
; Create the exception handler code in IA32 C code
;
.code
.stack
.MMX
.XMM
_LoadGo64Gdt PROC Near Public
push ebp ; C prolog
push edi
mov ebp, esp
;
; Disable interrupts
;
cli
;
; Reload the selectors
; Note:
; Make the Selectors 64-bit ready
;
mov edi, OFFSET gdtr ; Load GDT register
mov ax,cs ; Get the selector data from our code image
mov es,ax
lgdt FWORD PTR es:[edi] ; and update the GDTR
db 067h
db 0eah ; Far Jump Offset:Selector to reload CS
dd OFFSET DataSelectorRld; Offset is ensuing instruction boundary
dw LINEAR_CODE_SEL ; Selector is our code selector, 10h
DataSelectorRld::
mov ax, SYS_DATA_SEL ; Update the Base for the new selectors, too
mov ds, ax
mov es, ax
mov fs, ax
mov gs, ax
mov ss, ax
pop edi
pop ebp
ret
_LoadGo64Gdt endp
; VOID
; ActivateLongMode (
; IN EFI_PHYSICAL_ADDRESS PageTables,
; IN EFI_PHYSICAL_ADDRESS HobStart,
; IN EFI_PHYSICAL_ADDRESS Stack,
; IN EFI_PHYSICAL_ADDRESS PpisNeededByDxeIplEntryPoint,
; IN EFI_PHYSICAL_ADDRESS DxeCoreEntryPoint
; )
;
; Input: [ebp][0h] = Original ebp
; [ebp][4h] = Return address
; [ebp][8h] = PageTables
; [ebp][10h] = HobStart
; [ebp][18h] = Stack
; [ebp][20h] = CodeEntryPoint1 <--- Call this first (for each call, pass HOB pointer)
; [ebp][28h] = CodeEntryPoint2 <--- Call this second
;
;
_ActivateLongMode PROC Near Public
push ebp ; C prolog
mov ebp, esp
;
; Use CPUID to determine if the processor supports long mode.
;
mov eax, 80000000h ; Extended-function code 8000000h.
cpuid ; Is largest extended function
cmp eax, 80000000h ; any function > 80000000h?
jbe no_long_mode ; If not, no long mode.
mov eax, 80000001h ; Extended-function code 8000001h.
cpuid ; Now EDX = extended-features flags.
bt edx, 29 ; Test if long mode is supported.
jnc no_long_mode ; Exit if not supported.
;
; Enable the 64-bit page-translation-table entries by
; setting CR4.PAE=1 (this is _required_ before activating
; long mode). Paging is not enabled until after long mode
; is enabled.
;
mov eax, cr4
bts eax, 5
mov cr4, eax
;
; Get the long-mode page tables, and initialize the
; 64-bit CR3 (page-table base address) to point to the base
; of the PML4 page table. The PML4 page table must be located
; below 4 Gbytes because only 32 bits of CR3 are loaded when
; the processor is not in 64-bit mode.
;
mov eax, [ebp+8h] ; Get Page Tables
mov cr3, eax ; Initialize CR3 with PML4 base.
;
; Enable long mode (set EFER.LME=1).
;
mov ecx, 0c0000080h ; EFER MSR number.
rdmsr ; Read EFER.
bts eax, 8 ; Set LME=1.
wrmsr ; Write EFER.
;
; Enable paging to activate long mode (set CR0.PG=1)
;
mov eax, cr0 ; Read CR0.
bts eax, 31 ; Set PG=1.
mov cr0, eax ; Write CR0.
jmp go_to_long_mode
go_to_long_mode:
;
; This is the next instruction after enabling paging. Jump to long mode
;
db 067h
db 0eah ; Far Jump Offset:Selector to reload CS
dd OFFSET in_long_mode; Offset is ensuing instruction boundary
dw SYS_CODE64_SEL ; Selector is our code selector, 10h
in_long_mode::
mov ax, SYS_DATA64_SEL
mov es, ax
mov ss, ax
mov ds, ax
;; jmp $
;
; We're in long mode, so marshall the arguments to call the
; passed in function pointers
; Recall
; [ebp][10h] = HobStart
; [ebp][18h] = Stack
; [ebp][20h] = PpisNeededByDxeIplEntryPoint <--- Call this first (for each call, pass HOB pointer)
; [ebp][28h] = DxeCoreEntryPoint <--- Call this second
;
db 48h
mov ebx, [ebp+18h] ; Setup the stack
db 48h
mov esp, ebx ; On a new stack now
;; 00000905 FF D0 call rax
db 48h
mov ecx, [ebp+10h] ; Pass Hob Start in RCX
db 48h
mov eax, [ebp+28h] ; Get the function pointer for
; DxeCoreEntryPoint into EAX
;; 00000905 FF D0 call rax
db 0ffh
db 0d0h
;
; WE SHOULD NEVER GET HERE!!!!!!!!!!!!!
;
no_long_mode:
jmp no_long_mode
_ActivateLongMode endp
align 16
gdtr dw GDT_END - GDT_BASE - 1 ; GDT limit
dd OFFSET GDT_BASE ; (GDT base gets set above)
;-----------------------------------------------------------------------------;
; global descriptor table (GDT)
;-----------------------------------------------------------------------------;
align 16
public GDT_BASE
GDT_BASE:
; null descriptor
NULL_SEL equ $-GDT_BASE ; Selector [0]
dw 0 ; limit 15:0
dw 0 ; base 15:0
db 0 ; base 23:16
db 0 ; type
db 0 ; limit 19:16, flags
db 0 ; base 31:24
; linear data segment descriptor
LINEAR_SEL equ $-GDT_BASE ; Selector [0x8]
dw 0FFFFh ; limit 0xFFFFF
dw 0 ; base 0
db 0
db 092h ; present, ring 0, data, expand-up, writable
db 0CFh ; page-granular, 32-bit
db 0
; linear code segment descriptor
LINEAR_CODE_SEL equ $-GDT_BASE ; Selector [0x10]
dw 0FFFFh ; limit 0xFFFFF
dw 0 ; base 0
db 0
db 09Fh ; present, ring 0, data, expand-up, writable
db 0CFh ; page-granular, 32-bit
db 0
; system data segment descriptor
SYS_DATA_SEL equ $-GDT_BASE ; Selector [0x18]
dw 0FFFFh ; limit 0xFFFFF
dw 0 ; base 0
db 0
db 093h ; present, ring 0, data, expand-up, writable
db 0CFh ; page-granular, 32-bit
db 0
; system code segment descriptor
SYS_CODE_SEL equ $-GDT_BASE ; Selector [0x20]
dw 0FFFFh ; limit 0xFFFFF
dw 0 ; base 0
db 0
db 09Ah ; present, ring 0, data, expand-up, writable
db 0CFh ; page-granular, 32-bit
db 0
; spare segment descriptor
SPARE3_SEL equ $-GDT_BASE ; Selector [0x28]
dw 0 ; limit 0xFFFFF
dw 0 ; base 0
db 0
db 0 ; present, ring 0, data, expand-up, writable
db 0 ; page-granular, 32-bit
db 0
;
; system data segment descriptor
;
SYS_DATA64_SEL equ $-GDT_BASE ; Selector [0x30]
dw 0FFFFh ; limit 0xFFFFF
dw 0 ; base 0
db 0
db 092h ; P | DPL [1..2] | 1 | 1 | C | R | A
db 0CFh ; G | D | L | AVL | Segment [19..16]
db 0
;
; system code segment descriptor
;
SYS_CODE64_SEL equ $-GDT_BASE ; Selector [0x38]
dw 0FFFFh ; limit 0xFFFFF
dw 0 ; base 0
db 0
db 09Ah ; P | DPL [1..2] | 1 | 1 | C | R | A
db 0AFh ; G | D | L | AVL | Segment [19..16]
db 0
; spare segment descriptor
SPARE4_SEL equ $-GDT_BASE ; Selector [0x40]
dw 0 ; limit 0xFFFFF
dw 0 ; base 0
db 0
db 0 ; present, ring 0, data, expand-up, writable
db 0 ; page-granular, 32-bit
db 0
GDT_END:
END
|
