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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 | |
15 | * along with this program; if not, write to the Free Software | |
16 | * Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. | |
17 | * | |
18 | * Copyright Novell Inc, 2009 | |
19 | * Authors: Alexander Graf <agraf@suse.de> | |
20 | */ | |
21 | ||
22 | #define NO_QEMU_PROTOS | |
23 | #include "../../hw/fw_cfg.h" | |
24 | ||
25 | #define BIOS_CFG_IOPORT_CFG 0x510 | |
26 | #define BIOS_CFG_IOPORT_DATA 0x511 | |
27 | ||
28 | #define MULTIBOOT_MAGIC 0x2badb002 | |
29 | ||
30 | /* Read a variable from the fw_cfg device. | |
31 | Clobbers: %edx | |
32 | Out: %eax */ | |
33 | .macro read_fw VAR | |
34 | mov $\VAR, %ax | |
35 | mov $BIOS_CFG_IOPORT_CFG, %dx | |
36 | outw %ax, (%dx) | |
37 | mov $BIOS_CFG_IOPORT_DATA, %dx | |
38 | inb (%dx), %al | |
39 | shl $8, %eax | |
40 | inb (%dx), %al | |
41 | shl $8, %eax | |
42 | inb (%dx), %al | |
43 | shl $8, %eax | |
44 | inb (%dx), %al | |
45 | bswap %eax | |
46 | .endm | |
47 | ||
48 | .code16 | |
49 | .text | |
50 | .global _start | |
51 | _start: | |
52 | .short 0xaa55 | |
53 | .byte (_end - _start) / 512 | |
54 | push %eax | |
55 | push %ds | |
56 | ||
57 | /* setup ds so we can access the IVT */ | |
58 | xor %ax, %ax | |
59 | mov %ax, %ds | |
60 | ||
61 | /* save old int 19 */ | |
62 | mov (0x19*4), %eax | |
63 | mov %eax, %cs:old_int19 | |
64 | ||
65 | /* install our int 19 handler */ | |
66 | movw $int19_handler, (0x19*4) | |
67 | mov %cs, (0x19*4+2) | |
68 | ||
69 | pop %ds | |
70 | pop %eax | |
71 | lret | |
72 | ||
73 | int19_handler: | |
74 | /* DS = CS */ | |
75 | movw %cs, %ax | |
76 | movw %ax, %ds | |
77 | ||
78 | /* fall through */ | |
79 | ||
80 | run_multiboot: | |
81 | ||
82 | cli | |
83 | cld | |
84 | ||
85 | mov %cs, %eax | |
86 | shl $0x4, %eax | |
87 | ||
88 | /* fix the gdt descriptor to be PC relative */ | |
89 | mov (gdt_desc+2), %ebx | |
90 | add %eax, %ebx | |
91 | mov %ebx, (gdt_desc+2) | |
92 | ||
93 | /* fix the prot mode indirect jump to be PC relative */ | |
94 | mov (prot_jump), %ebx | |
95 | add %eax, %ebx | |
96 | mov %ebx, (prot_jump) | |
97 | ||
98 | /* FS = bootinfo_struct */ | |
99 | read_fw FW_CFG_INITRD_ADDR | |
100 | shr $4, %eax | |
101 | mov %ax, %fs | |
102 | ||
103 | /* ES = mmap_addr */ | |
104 | read_fw FW_CFG_INITRD_SIZE | |
105 | shr $4, %eax | |
106 | mov %ax, %es | |
107 | ||
108 | /* Initialize multiboot mmap structs using int 0x15(e820) */ | |
109 | xor %ebx, %ebx | |
110 | /* mmap start after first size */ | |
111 | movl $4, %edi | |
112 | ||
113 | mmap_loop: | |
114 | /* entry size (mmap struct) & max buffer size (int15) */ | |
115 | movl $20, %ecx | |
116 | /* store entry size */ | |
117 | movl %ecx, %es:-4(%edi) | |
118 | /* e820 */ | |
119 | movl $0x0000e820, %eax | |
120 | /* 'SMAP' magic */ | |
121 | movl $0x534d4150, %edx | |
122 | int $0x15 | |
123 | ||
124 | mmap_check_entry: | |
125 | /* last entry? then we're done */ | |
126 | jb mmap_done | |
127 | and %bx, %bx | |
128 | jz mmap_done | |
129 | /* valid entry, so let's loop on */ | |
130 | ||
131 | mmap_store_entry: | |
132 | /* %ax = entry_number * 24 */ | |
133 | mov $24, %ax | |
134 | mul %bx | |
135 | mov %ax, %di | |
136 | movw %di, %fs:0x2c | |
137 | /* %di = 4 + (entry_number * 24) */ | |
138 | add $4, %di | |
139 | jmp mmap_loop | |
140 | ||
141 | mmap_done: | |
142 | real_to_prot: | |
143 | /* Load the GDT before going into protected mode */ | |
144 | lgdt: | |
145 | data32 lgdt %cs:gdt_desc | |
146 | ||
147 | /* get us to protected mode now */ | |
148 | movl $1, %eax | |
149 | movl %eax, %cr0 | |
150 | ||
151 | /* the LJMP sets CS for us and gets us to 32-bit */ | |
152 | ljmp: | |
153 | data32 ljmp *%cs:prot_jump | |
154 | ||
155 | prot_mode: | |
156 | .code32 | |
157 | ||
158 | /* initialize all other segments */ | |
159 | movl $0x10, %eax | |
160 | movl %eax, %ss | |
161 | movl %eax, %ds | |
162 | movl %eax, %es | |
163 | movl %eax, %fs | |
164 | movl %eax, %gs | |
165 | ||
166 | /* Jump off to the kernel */ | |
167 | read_fw FW_CFG_KERNEL_ADDR | |
168 | mov %eax, %ecx | |
169 | ||
170 | /* EBX contains a pointer to the bootinfo struct */ | |
171 | read_fw FW_CFG_INITRD_ADDR | |
172 | movl %eax, %ebx | |
173 | ||
174 | /* EAX has to contain the magic */ | |
175 | movl $MULTIBOOT_MAGIC, %eax | |
176 | ljmp2: | |
177 | jmp *%ecx | |
178 | ||
179 | /* Variables */ | |
180 | .align 4, 0 | |
181 | old_int19: .long 0 | |
182 | ||
183 | prot_jump: .long prot_mode | |
184 | .short 8 | |
185 | ||
186 | .align 4, 0 | |
187 | gdt: | |
188 | /* 0x00 */ | |
189 | .byte 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 | |
190 | ||
191 | /* 0x08: code segment (base=0, limit=0xfffff, type=32bit code exec/read, DPL=0, 4k) */ | |
192 | .byte 0xff, 0xff, 0x00, 0x00, 0x00, 0x9a, 0xcf, 0x00 | |
193 | ||
194 | /* 0x10: data segment (base=0, limit=0xfffff, type=32bit data read/write, DPL=0, 4k) */ | |
195 | .byte 0xff, 0xff, 0x00, 0x00, 0x00, 0x92, 0xcf, 0x00 | |
196 | ||
197 | /* 0x18: code segment (base=0, limit=0x0ffff, type=16bit code exec/read/conf, DPL=0, 1b) */ | |
198 | .byte 0xff, 0xff, 0x00, 0x00, 0x00, 0x9e, 0x00, 0x00 | |
199 | ||
200 | /* 0x20: data segment (base=0, limit=0x0ffff, type=16bit data read/write, DPL=0, 1b) */ | |
201 | .byte 0xff, 0xff, 0x00, 0x00, 0x00, 0x92, 0x00, 0x00 | |
202 | ||
203 | gdt_desc: | |
204 | .short (5 * 8) - 1 | |
205 | .long gdt | |
206 | ||
207 | .align 512, 0 | |
208 | _end: | |
209 |