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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 | ||
dd4b2659 | 21 | #include "optionrom.h" |
f16408df | 22 | |
75b9f690 GN |
23 | #define BOOT_ROM_PRODUCT "multiboot loader" |
24 | ||
f16408df AG |
25 | #define MULTIBOOT_MAGIC 0x2badb002 |
26 | ||
77873196 AG |
27 | #define GS_PROT_JUMP 0 |
28 | #define GS_GDT_DESC 6 | |
29 | ||
f16408df | 30 | |
dd4b2659 | 31 | BOOT_ROM_START |
f16408df AG |
32 | |
33 | run_multiboot: | |
34 | ||
35 | cli | |
36 | cld | |
37 | ||
38 | mov %cs, %eax | |
39 | shl $0x4, %eax | |
40 | ||
77873196 | 41 | /* set up a long jump descriptor that is PC relative */ |
f16408df | 42 | |
77873196 AG |
43 | /* move stack memory to %gs */ |
44 | mov %ss, %ecx | |
45 | shl $0x4, %ecx | |
46 | mov %esp, %ebx | |
47 | add %ebx, %ecx | |
48 | sub $0x20, %ecx | |
49 | sub $0x30, %esp | |
50 | shr $0x4, %ecx | |
51 | mov %cx, %gs | |
52 | ||
e7d81004 | 53 | /* now push the indirect jump descriptor there */ |
f16408df AG |
54 | mov (prot_jump), %ebx |
55 | add %eax, %ebx | |
77873196 AG |
56 | movl %ebx, %gs:GS_PROT_JUMP |
57 | mov $8, %bx | |
58 | movw %bx, %gs:GS_PROT_JUMP + 4 | |
59 | ||
60 | /* fix the gdt descriptor to be PC relative */ | |
61 | movw (gdt_desc), %bx | |
62 | movw %bx, %gs:GS_GDT_DESC | |
63 | movl (gdt_desc+2), %ebx | |
64 | add %eax, %ebx | |
65 | movl %ebx, %gs:GS_GDT_DESC + 2 | |
66 | ||
53ea95de AL |
67 | xor %eax, %eax |
68 | mov %eax, %es | |
69 | ||
77873196 AG |
70 | /* Read the bootinfo struct into RAM */ |
71 | read_fw_blob(FW_CFG_INITRD) | |
f16408df AG |
72 | |
73 | /* FS = bootinfo_struct */ | |
74 | read_fw FW_CFG_INITRD_ADDR | |
75 | shr $4, %eax | |
76 | mov %ax, %fs | |
77 | ||
c6e052f0 PB |
78 | /* Account for the EBDA in the multiboot structure's e801 |
79 | * map. | |
80 | */ | |
81 | int $0x12 | |
82 | cwtl | |
83 | movl %eax, %fs:4 | |
84 | ||
f16408df | 85 | /* ES = mmap_addr */ |
53ea95de | 86 | mov %fs:48, %eax |
f16408df AG |
87 | shr $4, %eax |
88 | mov %ax, %es | |
89 | ||
90 | /* Initialize multiboot mmap structs using int 0x15(e820) */ | |
91 | xor %ebx, %ebx | |
390fb6b4 KW |
92 | /* Start storing mmap data at %es:0 */ |
93 | xor %edi, %edi | |
f16408df AG |
94 | |
95 | mmap_loop: | |
390fb6b4 KW |
96 | /* The multiboot entry size has offset -4, so leave some space */ |
97 | add $4, %di | |
f16408df AG |
98 | /* entry size (mmap struct) & max buffer size (int15) */ |
99 | movl $20, %ecx | |
f16408df AG |
100 | /* e820 */ |
101 | movl $0x0000e820, %eax | |
102 | /* 'SMAP' magic */ | |
103 | movl $0x534d4150, %edx | |
104 | int $0x15 | |
105 | ||
106 | mmap_check_entry: | |
390fb6b4 | 107 | /* Error or last entry already done? */ |
f16408df | 108 | jb mmap_done |
f16408df AG |
109 | |
110 | mmap_store_entry: | |
390fb6b4 KW |
111 | /* store entry size */ |
112 | /* old as(1) doesn't like this insn so emit the bytes instead: | |
113 | movl %ecx, %es:-4(%edi) | |
114 | */ | |
115 | .dc.b 0x26,0x67,0x66,0x89,0x4f,0xfc | |
116 | ||
117 | /* %edi += entry_size, store as mbs_mmap_length */ | |
118 | add %ecx, %edi | |
f16408df | 119 | movw %di, %fs:0x2c |
390fb6b4 KW |
120 | |
121 | /* Continuation value 0 means last entry */ | |
122 | test %ebx, %ebx | |
123 | jnz mmap_loop | |
f16408df AG |
124 | |
125 | mmap_done: | |
26a8ec07 KW |
126 | /* Calculate upper_mem field: The amount of memory between 1 MB and |
127 | the first upper memory hole. Get it from the mmap. */ | |
128 | xor %di, %di | |
129 | mov $0x100000, %edx | |
130 | upper_mem_entry: | |
131 | cmp %fs:0x2c, %di | |
132 | je upper_mem_done | |
133 | add $4, %di | |
134 | ||
135 | /* Skip if type != 1 */ | |
136 | cmpl $1, %es:16(%di) | |
137 | jne upper_mem_next | |
138 | ||
139 | /* Skip if > 4 GB */ | |
140 | movl %es:4(%di), %eax | |
141 | test %eax, %eax | |
142 | jnz upper_mem_next | |
143 | ||
144 | /* Check for contiguous extension (base <= %edx < base + length) */ | |
145 | movl %es:(%di), %eax | |
146 | cmp %eax, %edx | |
147 | jb upper_mem_next | |
148 | addl %es:8(%di), %eax | |
149 | cmp %eax, %edx | |
150 | jae upper_mem_next | |
151 | ||
152 | /* If so, update %edx, and restart the search (mmap isn't ordered) */ | |
153 | mov %eax, %edx | |
154 | xor %di, %di | |
155 | jmp upper_mem_entry | |
156 | ||
157 | upper_mem_next: | |
158 | addl %es:-4(%di), %edi | |
159 | jmp upper_mem_entry | |
160 | ||
161 | upper_mem_done: | |
162 | sub $0x100000, %edx | |
163 | shr $10, %edx | |
164 | mov %edx, %fs:0x8 | |
165 | ||
f16408df AG |
166 | real_to_prot: |
167 | /* Load the GDT before going into protected mode */ | |
168 | lgdt: | |
77873196 | 169 | data32 lgdt %gs:GS_GDT_DESC |
f16408df AG |
170 | |
171 | /* get us to protected mode now */ | |
172 | movl $1, %eax | |
173 | movl %eax, %cr0 | |
174 | ||
175 | /* the LJMP sets CS for us and gets us to 32-bit */ | |
176 | ljmp: | |
77873196 | 177 | data32 ljmp *%gs:GS_PROT_JUMP |
f16408df AG |
178 | |
179 | prot_mode: | |
180 | .code32 | |
181 | ||
182 | /* initialize all other segments */ | |
183 | movl $0x10, %eax | |
184 | movl %eax, %ss | |
185 | movl %eax, %ds | |
186 | movl %eax, %es | |
187 | movl %eax, %fs | |
188 | movl %eax, %gs | |
189 | ||
77873196 AG |
190 | /* Read the kernel and modules into RAM */ |
191 | read_fw_blob(FW_CFG_KERNEL) | |
192 | ||
f16408df | 193 | /* Jump off to the kernel */ |
77873196 | 194 | read_fw FW_CFG_KERNEL_ENTRY |
f16408df AG |
195 | mov %eax, %ecx |
196 | ||
197 | /* EBX contains a pointer to the bootinfo struct */ | |
198 | read_fw FW_CFG_INITRD_ADDR | |
199 | movl %eax, %ebx | |
200 | ||
201 | /* EAX has to contain the magic */ | |
202 | movl $MULTIBOOT_MAGIC, %eax | |
203 | ljmp2: | |
204 | jmp *%ecx | |
205 | ||
206 | /* Variables */ | |
207 | .align 4, 0 | |
f16408df AG |
208 | prot_jump: .long prot_mode |
209 | .short 8 | |
210 | ||
211 | .align 4, 0 | |
212 | gdt: | |
213 | /* 0x00 */ | |
214 | .byte 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 | |
215 | ||
216 | /* 0x08: code segment (base=0, limit=0xfffff, type=32bit code exec/read, DPL=0, 4k) */ | |
217 | .byte 0xff, 0xff, 0x00, 0x00, 0x00, 0x9a, 0xcf, 0x00 | |
218 | ||
219 | /* 0x10: data segment (base=0, limit=0xfffff, type=32bit data read/write, DPL=0, 4k) */ | |
220 | .byte 0xff, 0xff, 0x00, 0x00, 0x00, 0x92, 0xcf, 0x00 | |
221 | ||
222 | /* 0x18: code segment (base=0, limit=0x0ffff, type=16bit code exec/read/conf, DPL=0, 1b) */ | |
223 | .byte 0xff, 0xff, 0x00, 0x00, 0x00, 0x9e, 0x00, 0x00 | |
224 | ||
225 | /* 0x20: data segment (base=0, limit=0x0ffff, type=16bit data read/write, DPL=0, 1b) */ | |
226 | .byte 0xff, 0xff, 0x00, 0x00, 0x00, 0x92, 0x00, 0x00 | |
227 | ||
228 | gdt_desc: | |
229 | .short (5 * 8) - 1 | |
230 | .long gdt | |
231 | ||
dd4b2659 | 232 | BOOT_ROM_END |