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f16408df AG |
1 | /* |
2 | * Multiboot Option ROM | |
3 | * | |
4 | * This program is free software; you can redistribute it and/or modify | |
5 | * it under the terms of the GNU General Public License as published by | |
6 | * the Free Software Foundation; either version 2 of the License, or | |
7 | * (at your option) any later version. | |
8 | * | |
9 | * This program is distributed in the hope that it will be useful, | |
10 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
11 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
12 | * GNU General Public License for more details. | |
13 | * | |
14 | * You should have received a copy of the GNU General Public License | |
8167ee88 | 15 | * along with this program; if not, see <http://www.gnu.org/licenses/>. |
f16408df AG |
16 | * |
17 | * Copyright Novell Inc, 2009 | |
18 | * Authors: Alexander Graf <agraf@suse.de> | |
19 | */ | |
20 | ||
21 | #define NO_QEMU_PROTOS | |
22 | #include "../../hw/fw_cfg.h" | |
23 | ||
24 | #define BIOS_CFG_IOPORT_CFG 0x510 | |
25 | #define BIOS_CFG_IOPORT_DATA 0x511 | |
26 | ||
27 | #define MULTIBOOT_MAGIC 0x2badb002 | |
28 | ||
29 | /* Read a variable from the fw_cfg device. | |
30 | Clobbers: %edx | |
31 | Out: %eax */ | |
32 | .macro read_fw VAR | |
33 | mov $\VAR, %ax | |
34 | mov $BIOS_CFG_IOPORT_CFG, %dx | |
35 | outw %ax, (%dx) | |
36 | mov $BIOS_CFG_IOPORT_DATA, %dx | |
37 | inb (%dx), %al | |
38 | shl $8, %eax | |
39 | inb (%dx), %al | |
40 | shl $8, %eax | |
41 | inb (%dx), %al | |
42 | shl $8, %eax | |
43 | inb (%dx), %al | |
44 | bswap %eax | |
45 | .endm | |
46 | ||
47 | .code16 | |
48 | .text | |
49 | .global _start | |
50 | _start: | |
51 | .short 0xaa55 | |
8676188b | 52 | .byte 1 /* (_end - _start) / 512 */ |
f16408df AG |
53 | push %eax |
54 | push %ds | |
55 | ||
56 | /* setup ds so we can access the IVT */ | |
57 | xor %ax, %ax | |
58 | mov %ax, %ds | |
59 | ||
60 | /* save old int 19 */ | |
61 | mov (0x19*4), %eax | |
62 | mov %eax, %cs:old_int19 | |
63 | ||
64 | /* install our int 19 handler */ | |
65 | movw $int19_handler, (0x19*4) | |
66 | mov %cs, (0x19*4+2) | |
67 | ||
68 | pop %ds | |
69 | pop %eax | |
70 | lret | |
71 | ||
72 | int19_handler: | |
73 | /* DS = CS */ | |
74 | movw %cs, %ax | |
75 | movw %ax, %ds | |
76 | ||
77 | /* fall through */ | |
78 | ||
79 | run_multiboot: | |
80 | ||
81 | cli | |
82 | cld | |
83 | ||
84 | mov %cs, %eax | |
85 | shl $0x4, %eax | |
86 | ||
87 | /* fix the gdt descriptor to be PC relative */ | |
88 | mov (gdt_desc+2), %ebx | |
89 | add %eax, %ebx | |
90 | mov %ebx, (gdt_desc+2) | |
91 | ||
92 | /* fix the prot mode indirect jump to be PC relative */ | |
93 | mov (prot_jump), %ebx | |
94 | add %eax, %ebx | |
95 | mov %ebx, (prot_jump) | |
96 | ||
97 | /* FS = bootinfo_struct */ | |
98 | read_fw FW_CFG_INITRD_ADDR | |
99 | shr $4, %eax | |
100 | mov %ax, %fs | |
101 | ||
102 | /* ES = mmap_addr */ | |
103 | read_fw FW_CFG_INITRD_SIZE | |
104 | shr $4, %eax | |
105 | mov %ax, %es | |
106 | ||
107 | /* Initialize multiboot mmap structs using int 0x15(e820) */ | |
108 | xor %ebx, %ebx | |
109 | /* mmap start after first size */ | |
110 | movl $4, %edi | |
111 | ||
112 | mmap_loop: | |
113 | /* entry size (mmap struct) & max buffer size (int15) */ | |
114 | movl $20, %ecx | |
115 | /* store entry size */ | |
ff56954b | 116 | /* old as(1) doesn't like this insn so emit the bytes instead: |
f16408df | 117 | movl %ecx, %es:-4(%edi) |
ff56954b JL |
118 | */ |
119 | .dc.b 0x26,0x67,0x66,0x89,0x4f,0xfc | |
f16408df AG |
120 | /* e820 */ |
121 | movl $0x0000e820, %eax | |
122 | /* 'SMAP' magic */ | |
123 | movl $0x534d4150, %edx | |
124 | int $0x15 | |
125 | ||
126 | mmap_check_entry: | |
127 | /* last entry? then we're done */ | |
128 | jb mmap_done | |
129 | and %bx, %bx | |
130 | jz mmap_done | |
131 | /* valid entry, so let's loop on */ | |
132 | ||
133 | mmap_store_entry: | |
134 | /* %ax = entry_number * 24 */ | |
135 | mov $24, %ax | |
136 | mul %bx | |
137 | mov %ax, %di | |
138 | movw %di, %fs:0x2c | |
139 | /* %di = 4 + (entry_number * 24) */ | |
140 | add $4, %di | |
141 | jmp mmap_loop | |
142 | ||
143 | mmap_done: | |
144 | real_to_prot: | |
145 | /* Load the GDT before going into protected mode */ | |
146 | lgdt: | |
147 | data32 lgdt %cs:gdt_desc | |
148 | ||
149 | /* get us to protected mode now */ | |
150 | movl $1, %eax | |
151 | movl %eax, %cr0 | |
152 | ||
153 | /* the LJMP sets CS for us and gets us to 32-bit */ | |
154 | ljmp: | |
155 | data32 ljmp *%cs:prot_jump | |
156 | ||
157 | prot_mode: | |
158 | .code32 | |
159 | ||
160 | /* initialize all other segments */ | |
161 | movl $0x10, %eax | |
162 | movl %eax, %ss | |
163 | movl %eax, %ds | |
164 | movl %eax, %es | |
165 | movl %eax, %fs | |
166 | movl %eax, %gs | |
167 | ||
168 | /* Jump off to the kernel */ | |
169 | read_fw FW_CFG_KERNEL_ADDR | |
170 | mov %eax, %ecx | |
171 | ||
172 | /* EBX contains a pointer to the bootinfo struct */ | |
173 | read_fw FW_CFG_INITRD_ADDR | |
174 | movl %eax, %ebx | |
175 | ||
176 | /* EAX has to contain the magic */ | |
177 | movl $MULTIBOOT_MAGIC, %eax | |
178 | ljmp2: | |
179 | jmp *%ecx | |
180 | ||
181 | /* Variables */ | |
182 | .align 4, 0 | |
183 | old_int19: .long 0 | |
184 | ||
185 | prot_jump: .long prot_mode | |
186 | .short 8 | |
187 | ||
188 | .align 4, 0 | |
189 | gdt: | |
190 | /* 0x00 */ | |
191 | .byte 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 | |
192 | ||
193 | /* 0x08: code segment (base=0, limit=0xfffff, type=32bit code exec/read, DPL=0, 4k) */ | |
194 | .byte 0xff, 0xff, 0x00, 0x00, 0x00, 0x9a, 0xcf, 0x00 | |
195 | ||
196 | /* 0x10: data segment (base=0, limit=0xfffff, type=32bit data read/write, DPL=0, 4k) */ | |
197 | .byte 0xff, 0xff, 0x00, 0x00, 0x00, 0x92, 0xcf, 0x00 | |
198 | ||
199 | /* 0x18: code segment (base=0, limit=0x0ffff, type=16bit code exec/read/conf, DPL=0, 1b) */ | |
200 | .byte 0xff, 0xff, 0x00, 0x00, 0x00, 0x9e, 0x00, 0x00 | |
201 | ||
202 | /* 0x20: data segment (base=0, limit=0x0ffff, type=16bit data read/write, DPL=0, 1b) */ | |
203 | .byte 0xff, 0xff, 0x00, 0x00, 0x00, 0x92, 0x00, 0x00 | |
204 | ||
205 | gdt_desc: | |
206 | .short (5 * 8) - 1 | |
207 | .long gdt | |
208 | ||
209 | .align 512, 0 | |
210 | _end: | |
211 |