summaryrefslogtreecommitdiff
path: root/DuetPkg/BootSector/Gpt.S
blob: 821ca846f0495601ff0837fff223bab7a3ccbce1 (plain)
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
295
296
297
#------------------------------------------------------------------------------
#*
#*   Copyright (c) 2006 - 2011, Intel Corporation. All rights reserved.<BR>
#*   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.             
#*   
#*    gpt.asm
#*  
#*   Abstract:
#*
#------------------------------------------------------------------------------

    #.MODEL small
#   .dosseg
    .stack: 
    .486p: 
    .code16 

.equ                      BLOCK_SIZE,  0x0200
.equ                      BLOCK_MASK,  0x01ff
.equ                      BLOCK_SHIFT, 9

# ****************************************************************************
# Code loaded by BIOS at 0x0000:0x7C00
# ****************************************************************************

        .org 0x00
Start: 

# ****************************************************************************
# Start Print
# ****************************************************************************

    movw $0xb800, %ax
    movw %ax, %es
    movw $0x7c0, %ax
    movw %ax, %ds
    leaw %cs:StartString, %si
    movw $10, %cx
    movw $160, %di
    rep
    movsw

# ****************************************************************************
# Print over
# ****************************************************************************

# ****************************************************************************
# Initialize segment registers and copy code at 0x0000:0x7c00 to 0x0000:0x0600
# ****************************************************************************
        xorw  %ax, %ax                  # AX = 0x0000  
        movw  $0x7c00, %bx              # BX = 0x7C00
        movw  $0x600, %bp               # BP = 0x0600
        movw  RelocatedStart, %si       # SI = Offset(RelocatedStart)
        movw  $0x200, %cx               # CX = 0x0200
        subw  %si, %cx                  # CS = 0x0200 - Offset(RelocatedStart)
        leaw  (%bp,%si,), %di           # DI = 0x0600 + Offset(RelocatedStart)
        leaw  (%bx,%si,), %si           # BX = 0x7C00 + Offset(RelocatedStart)
        movw  %ax, %ss                  # SS = 0x0000
        movw  %bx, %sp                  # SP = 0x7C00
        movw  %ax, %es                  # ES = 0x0000
        movw  %ax, %ds                  # DS = 0x0000
        pushw %ax                       # PUSH 0x0000
        pushw %di                       # PUSH 0x0600 + Offset(RelocatedStart)
        cld                             # Clear the direction flag
        rep
        movsb                           # Copy 0x0200 bytes from 0x7C00 to 0x0600
        retl                            # JMP 0x0000:0x0600 + Offset(RelocatedStart)

# ****************************************************************************
# Code relocated to 0x0000:0x0600
# ****************************************************************************

RelocatedStart: 
# ****************************************************************************
# Get Driver Parameters to 0x0000:0x7BFC
# ****************************************************************************
        xorw  %ax, %ax      # ax = 0
        movw  %ax, %ss      # ss = 0
        addw  $0x1000, %ax
        movw  %ax, %ds

        movw  $0x7c00, %sp  # sp = 0x7c00
        movw  %sp, %bp      # bp = 0x7c00

        movb  $8, %ah                             # ah = 8 - Get Drive Parameters Function
        movb  %dl, PhysicalDrive(%bp)             # BBS defines that BIOS would pass the booting driver number to the loader through DL
        int   $0x13                               # Get Drive Parameters
        xorw  %ax, %ax                # ax = 0
        movb  %dh, %al                # al = dh
        incb  %al                     # MaxHead = al + 1
        pushw %ax                     # 0000:7bfe = MaxHead
        movb  %cl, %al                # al = cl
        andb  $0x3f, %al              # MaxSector = al & 0x3f
        pushw %ax                     # 0000:7bfc = MaxSector

# ****************************************************************************
# Read GPT Header from hard disk to 0x0000:0x0800
# ****************************************************************************
        xorw    %ax, %ax
        movw    %ax, %es                          # Read to 0x0000:0x0800
        movw    $0x800, %di                       # Read to 0x0000:0x0800
        movl    $1, %eax                          # Read LBA #1
        movl    $0, %edx                          # Read LBA #1
        movw    $1, %bx                           # Read 1 Block
        pushw   %es
        call    ReadBlocks
        popw    %es

# ****************************************************************************
# Read Target GPT Entry from hard disk to 0x0000:0x0A00
# ****************************************************************************
        cmpl  $0x20494645, %es:(%di)              # Check for "EFI "
        jne   BadGpt
        cmpl  $0x54524150, %es:4(%di)             # Check for "PART"
        jne   BadGpt
        cmpl  $0x00010000, %es:8(%di)             # Check Revision - 0x10000
        jne   BadGpt

        movl  %es:84(%di), %eax                   # EAX = SizeOfPartitionEntry
        mulb  GptPartitionIndicator(%bp)          # EAX = SizeOfPartitionEntry * GptPartitionIndicator
        movl  %eax, %edx                          # EDX = SizeOfPartitionEntry * GptPartitionIndicator
        shrl  $BLOCK_SHIFT, %eax                  # EAX = (SizeOfPartitionEntry * GptPartitionIndicator) / BLOCK_SIZE
        andl  $BLOCK_MASK, %edx                   # EDX = Targer PartitionEntryLBA Offset
                                                  #     = (SizeOfPartitionEntry * GptPartitionIndicator) % BLOCK_SIZE
        pushl %edx
        movl  %es:72(%di), %ecx                   # ECX = PartitionEntryLBA (Low)
        movl  %es:76(%di), %ebx                   # EBX = PartitionEntryLBA (High)
        addl  %ecx, %eax                          # EAX = Target PartitionEntryLBA (Low)
                                                  #     = (PartitionEntryLBA + 
                                                  #        (SizeOfPartitionEntry * GptPartitionIndicator) / BLOCK_SIZE)
        adcl  %ebx, %edx                          # EDX = Target PartitionEntryLBA (High)

        movw  $0xA00, %di                         # Read to 0x0000:0x0A00
        movw  $1, %bx                             # Read 1 Block
        pushw %es
        call  ReadBlocks
        popw  %es

# ****************************************************************************
# Read Target DBR from hard disk to 0x0000:0x7C00
# ****************************************************************************
        popl  %edx                                # EDX = (SizeOfPartitionEntry * GptPartitionIndicator) % BLOCK_SIZE
        addw  %dx, %di                            # DI = Targer PartitionEntryLBA Offset
        cmpl  $0xC12A7328, %es:(%di)              # Check for EFI System Partition "C12A7328-F81F-11d2-BA4B-00A0C93EC93B"
        jne   BadGpt
        cmpl  $0x11d2F81F, %es:4(%di)             # 
        jne   BadGpt
        cmpl  $0xA0004BBA, %es:8(%di)             # 
        jne   BadGpt
        cmpl  $0x3BC93EC9, %es:0xc(%di)           # 
        jne   BadGpt

        movl  %es:32(%di), %eax                   # EAX = StartingLBA (Low)
        movl  %es:36(%di), %edx                   # EDX = StartingLBA (High)
        movw  $0x7C00, %di                        # Read to 0x0000:0x7C00
        movw  $1, %bx                             # Read 1 Block
        call  ReadBlocks

# ****************************************************************************
# Transfer control to BootSector - Jump to 0x0000:0x7C00
# ****************************************************************************
        xorw  %ax, %ax
        pushw %ax                       # PUSH 0x0000
        movw  $0x7c00, %di
        pushw %di                       # PUSH 0x7C00
        retl                            # JMP 0x0000:0x7C00

# ****************************************************************************
# ReadBlocks - Reads a set of blocks from a block device
#
# EDX:EAX = Start LBA
# BX      = Number of Blocks to Read (must < 127)
# ES:DI   = Buffer to store sectors read from disk
# ****************************************************************************

# si = DiskAddressPacket

ReadBlocks: 
        pushal
        pushw %ds
        xorw  %cx, %cx
        movw  %cx, %ds
        movw  $0x600, %bp                       # bp = 0x600
        leaw  AddressPacket(%bp), %si
        movb  %bl, %ds:2(%si)                   #    02 = Number Of Block transfered
        movw  %di, %ds:4(%si)                   #    04 = Transfer Buffer Offset
        movw  %es, %ds:6(%si)                   #    06 = Transfer Buffer Segment
        movl  %eax, %ds:8(%si)                  #    08 = Starting LBA (Low)
        movl  %edx, %ds:0xc(%si)                #    0C = Starting LBA (High)
        movb  $0x42, %ah                        # ah = Function 42
        movb  PhysicalDrive(%bp), %dl           # dl = Drive Number
        int   $0x13
        jc    BadGpt
        popw  %ds
        popal
        ret

# ****************************************************************************
# Address Packet used by ReadBlocks
# ****************************************************************************
AddressPacket: 
        .byte 0x10                      # Size of address packet
        .byte 0x0                       # Reserved.  Must be 0
        .byte 0x1                       # Read blocks at a time (To be fixed each times)
        .byte 0x0                       # Reserved.  Must be 0
        .word 0x000                     # Destination Address offset (To be fixed each times)
        .word 0x000                     # Destination Address segment (To be fixed each times)
AddressPacketLba: 
        .long 0x0,0x0                   # Start LBA (To be fixed each times)
AddressPacketEnd: 

# ****************************************************************************
# ERROR Condition:
# ****************************************************************************

BadGpt: 
    movw $0xb800, %ax
    movw %ax, %es
    movw $0x60, %ax
    movw %ax, %ds
    leaw %cs:ErrorString, %si
    movw $10, %cx
    movw $320, %di
    rep
    movsw
Halt: 
    jmp   Halt

StartString: 
    .byte 'G', 0x0c, 'P', 0x0c, 'T', 0x0c, ' ', 0x0c, 'S', 0x0c, 't', 0x0c, 'a', 0x0c, 'r', 0x0c, 't', 0x0c, '!', 0x0c
ErrorString: 
    .byte 'G', 0x0c, 'P', 0x0c, 'T', 0x0c, ' ', 0x0c, 'E', 0x0c, 'r', 0x0c, 'r', 0x0c, 'o', 0x0c, 'r', 0x0c, '!', 0x0c

# ****************************************************************************
# PhysicalDrive - Used to indicate which disk to be boot
#                 Can be patched by tool
# ****************************************************************************
    # .org   0x01B6 # Just for passing build.
PhysicalDrive:        .byte 0x80

# ****************************************************************************
# GptPartitionIndicator - Used to indicate which GPT partition to be boot
#                         Can be patched by tool
# ****************************************************************************
   # .org   0x01B7  # Just for passing build.
GptPartitionIndicator: .byte 0

# ****************************************************************************
# Unique MBR signature
# ****************************************************************************
   # .org   0x01B8  # Just for passing build.
    .ascii "DUET"

# ****************************************************************************
# Unknown
# ****************************************************************************
    # .org   0x01BC  # Just for passing build.
    .word 0

# ****************************************************************************
# PMBR Entry - Can be patched by tool
# ****************************************************************************
    # .org   0x01BE  # Just for passing build.
    .byte 0       # Boot Indicator
    .byte 0xff    # Start Header
    .byte 0xff    # Start Sector
    .byte 0xff    # Start Track
    .byte 0xee    # OS Type
    .byte 0xff    # End Header
    .byte 0xff    # End Sector
    .byte 0xff    # End Track
    .long 1       # Starting LBA
    .long 0xFFFFFFFF # End LBA

    # .org   0x01CE  # Just for passing build.
    .long  0,0,0,0
    # .org   0x01DE  # Just for passing build.
    .long  0,0,0,0
    # .org   0x01EE  # Just for passing build.
    .long 0,0,0,0

# ****************************************************************************
# Sector Signature
# ****************************************************************************

  # .org      0x01FE  # Just for passing build.
SectorSignature: 
  .word     0xaa55      # Boot Sector Signature