Commit | Line | Data |
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1da177e4 LT |
1 | /* |
2 | * linux/boot/head.S | |
3 | * | |
4 | * Copyright (C) 1991, 1992, 1993 Linus Torvalds | |
5 | */ | |
6 | ||
7 | /* | |
8 | * head.S contains the 32-bit startup code. | |
9 | * | |
10 | * NOTE!!! Startup happens at absolute address 0x00001000, which is also where | |
11 | * the page directory will exist. The startup code will be overwritten by | |
12 | * the page directory. [According to comments etc elsewhere on a compressed | |
13 | * kernel it will end up at 0x1000 + 1Mb I hope so as I assume this. - AC] | |
14 | * | |
5f64ec64 | 15 | * Page 0 is deliberately kept safe, since System Management Mode code in |
1da177e4 | 16 | * laptops may need to access the BIOS data stored there. This is also |
5f64ec64 | 17 | * useful for future device drivers that either access the BIOS via VM86 |
1da177e4 LT |
18 | * mode. |
19 | */ | |
20 | ||
21 | /* | |
22 | * High loaded stuff by Hans Lermen & Werner Almesberger, Feb. 1996 | |
23 | */ | |
5f64ec64 | 24 | .text |
1da177e4 | 25 | |
1dc818c1 | 26 | #include <linux/init.h> |
1da177e4 LT |
27 | #include <linux/linkage.h> |
28 | #include <asm/segment.h> | |
0341c14d | 29 | #include <asm/page_types.h> |
e69f202d | 30 | #include <asm/boot.h> |
a24e7851 | 31 | #include <asm/asm-offsets.h> |
1da177e4 | 32 | |
1dc818c1 | 33 | __HEAD |
cb425afd | 34 | ENTRY(startup_32) |
291f3632 | 35 | #ifdef CONFIG_EFI_STUB |
b1994304 MF |
36 | jmp preferred_addr |
37 | ||
291f3632 MF |
38 | /* |
39 | * We don't need the return address, so set up the stack so | |
99f857db | 40 | * efi_main() can find its arguments. |
291f3632 | 41 | */ |
99f857db | 42 | ENTRY(efi_pe_entry) |
291f3632 MF |
43 | add $0x4, %esp |
44 | ||
54b52d87 MF |
45 | call 1f |
46 | 1: popl %esi | |
47 | subl $1b, %esi | |
48 | ||
49 | popl %ecx | |
50 | movl %ecx, efi32_config(%esi) /* Handle */ | |
51 | popl %ecx | |
52 | movl %ecx, efi32_config+8(%esi) /* EFI System table pointer */ | |
53 | ||
54 | /* Relocate efi_config->call() */ | |
55 | leal efi32_config(%esi), %eax | |
56 | add %esi, 88(%eax) | |
57 | pushl %eax | |
58 | ||
9ca8f72a MF |
59 | call make_boot_params |
60 | cmpl $0, %eax | |
54b52d87 | 61 | je fail |
7e8213c1 | 62 | movl %esi, BP_code32_start(%eax) |
54b52d87 | 63 | popl %ecx |
9ca8f72a | 64 | pushl %eax |
9ca8f72a | 65 | pushl %ecx |
54b52d87 | 66 | jmp 2f /* Skip efi_config initialization */ |
9ca8f72a | 67 | |
b8ff87a6 | 68 | ENTRY(efi32_stub_entry) |
f791620f | 69 | add $0x4, %esp |
54b52d87 MF |
70 | popl %ecx |
71 | popl %edx | |
72 | ||
73 | call 1f | |
74 | 1: popl %esi | |
75 | subl $1b, %esi | |
76 | ||
77 | movl %ecx, efi32_config(%esi) /* Handle */ | |
78 | movl %edx, efi32_config+8(%esi) /* EFI System table pointer */ | |
79 | ||
80 | /* Relocate efi_config->call() */ | |
81 | leal efi32_config(%esi), %eax | |
82 | add %esi, 88(%eax) | |
83 | pushl %eax | |
84 | 2: | |
291f3632 MF |
85 | call efi_main |
86 | cmpl $0, %eax | |
291f3632 | 87 | movl %eax, %esi |
b1994304 | 88 | jne 2f |
54b52d87 | 89 | fail: |
b1994304 MF |
90 | /* EFI init failed, so hang. */ |
91 | hlt | |
54b52d87 | 92 | jmp fail |
b1994304 | 93 | 2: |
7e8213c1 | 94 | movl BP_code32_start(%esi), %eax |
291f3632 MF |
95 | leal preferred_addr(%eax), %eax |
96 | jmp *%eax | |
97 | ||
98 | preferred_addr: | |
99 | #endif | |
bd53147d | 100 | cld |
5f64ec64 PA |
101 | /* |
102 | * Test KEEP_SEGMENTS flag to see if the bootloader is asking | |
103 | * us to not reload segments | |
104 | */ | |
105 | testb $(1<<6), BP_loadflags(%esi) | |
106 | jnz 1f | |
a24e7851 | 107 | |
bd53147d | 108 | cli |
5f64ec64 PA |
109 | movl $__BOOT_DS, %eax |
110 | movl %eax, %ds | |
111 | movl %eax, %es | |
112 | movl %eax, %fs | |
113 | movl %eax, %gs | |
114 | movl %eax, %ss | |
bd53147d | 115 | 1: |
a24e7851 | 116 | |
5f64ec64 PA |
117 | /* |
118 | * Calculate the delta between where we were compiled to run | |
968de4f0 EB |
119 | * at and where we were actually loaded at. This can only be done |
120 | * with a short local call on x86. Nothing else will tell us what | |
121 | * address we are running at. The reserved chunk of the real-mode | |
85414b69 PA |
122 | * data at 0x1e4 (defined as a scratch field) are used as the stack |
123 | * for this calculation. Only 4 bytes are needed. | |
968de4f0 | 124 | */ |
5f64ec64 PA |
125 | leal (BP_scratch+4)(%esi), %esp |
126 | call 1f | |
127 | 1: popl %ebp | |
128 | subl $1b, %ebp | |
968de4f0 | 129 | |
5f64ec64 PA |
130 | /* |
131 | * %ebp contains the address we are loaded at by the boot loader and %ebx | |
e69f202d VG |
132 | * contains the address where we should move the kernel image temporarily |
133 | * for safe in-place decompression. | |
968de4f0 | 134 | */ |
e69f202d | 135 | |
968de4f0 | 136 | #ifdef CONFIG_RELOCATABLE |
5f64ec64 | 137 | movl %ebp, %ebx |
37ba7ab5 PA |
138 | movl BP_kernel_alignment(%esi), %eax |
139 | decl %eax | |
140 | addl %eax, %ebx | |
141 | notl %eax | |
142 | andl %eax, %ebx | |
8ab3820f KC |
143 | cmpl $LOAD_PHYSICAL_ADDR, %ebx |
144 | jge 1f | |
968de4f0 | 145 | #endif |
8ab3820f KC |
146 | movl $LOAD_PHYSICAL_ADDR, %ebx |
147 | 1: | |
968de4f0 | 148 | |
02a884c0 PA |
149 | /* Target address to relocate to for decompression */ |
150 | addl $z_extract_offset, %ebx | |
968de4f0 | 151 | |
0a137736 PA |
152 | /* Set up the stack */ |
153 | leal boot_stack_end(%ebx), %esp | |
154 | ||
97541912 PA |
155 | /* Zero EFLAGS */ |
156 | pushl $0 | |
157 | popfl | |
158 | ||
5f64ec64 PA |
159 | /* |
160 | * Copy the compressed kernel to the end of our buffer | |
968de4f0 EB |
161 | * where decompression in place becomes safe. |
162 | */ | |
5f64ec64 | 163 | pushl %esi |
36d3793c PA |
164 | leal (_bss-4)(%ebp), %esi |
165 | leal (_bss-4)(%ebx), %edi | |
5b11f1ce | 166 | movl $(_bss - startup_32), %ecx |
36d3793c | 167 | shrl $2, %ecx |
968de4f0 | 168 | std |
36d3793c | 169 | rep movsl |
968de4f0 | 170 | cld |
5f64ec64 | 171 | popl %esi |
968de4f0 | 172 | |
1da177e4 | 173 | /* |
968de4f0 | 174 | * Jump to the relocated address. |
1da177e4 | 175 | */ |
5f64ec64 PA |
176 | leal relocated(%ebx), %eax |
177 | jmp *%eax | |
cb425afd CG |
178 | ENDPROC(startup_32) |
179 | ||
5f64ec64 | 180 | .text |
968de4f0 EB |
181 | relocated: |
182 | ||
1da177e4 | 183 | /* |
0a137736 | 184 | * Clear BSS (stack is currently empty) |
1da177e4 | 185 | */ |
5f64ec64 | 186 | xorl %eax, %eax |
5b11f1ce | 187 | leal _bss(%ebx), %edi |
5f64ec64 PA |
188 | leal _ebss(%ebx), %ecx |
189 | subl %edi, %ecx | |
36d3793c PA |
190 | shrl $2, %ecx |
191 | rep stosl | |
968de4f0 | 192 | |
f3670394 LT |
193 | /* |
194 | * Adjust our own GOT | |
195 | */ | |
196 | leal _got(%ebx), %edx | |
197 | leal _egot(%ebx), %ecx | |
198 | 1: | |
199 | cmpl %ecx, %edx | |
200 | jae 2f | |
201 | addl %ebx, (%edx) | |
202 | addl $4, %edx | |
203 | jmp 1b | |
204 | 2: | |
205 | ||
1da177e4 LT |
206 | /* |
207 | * Do the decompression, and jump to the new kernel.. | |
208 | */ | |
5f64ec64 | 209 | /* push arguments for decompress_kernel: */ |
e6023367 JM |
210 | pushl $z_run_size /* size of kernel with .bss and .brk */ |
211 | pushl $z_output_len /* decompressed length, end of relocs */ | |
a0215061 | 212 | leal z_extract_offset_negative(%ebx), %ebp |
5f64ec64 | 213 | pushl %ebp /* output address */ |
02a884c0 | 214 | pushl $z_input_len /* input_len */ |
5f64ec64 PA |
215 | leal input_data(%ebx), %eax |
216 | pushl %eax /* input_data */ | |
217 | leal boot_heap(%ebx), %eax | |
218 | pushl %eax /* heap area */ | |
219 | pushl %esi /* real mode pointer */ | |
8ab3820f | 220 | call decompress_kernel /* returns kernel location in %eax */ |
e6023367 | 221 | addl $28, %esp |
1da177e4 LT |
222 | |
223 | /* | |
968de4f0 | 224 | * Jump to the decompressed kernel. |
1da177e4 | 225 | */ |
5f64ec64 | 226 | xorl %ebx, %ebx |
8ab3820f | 227 | jmp *%eax |
968de4f0 | 228 | |
9cb0e394 | 229 | #ifdef CONFIG_EFI_STUB |
f3670394 | 230 | .data |
54b52d87 MF |
231 | efi32_config: |
232 | .fill 11,8,0 | |
233 | .long efi_call_phys | |
234 | .long 0 | |
235 | .byte 0 | |
3db4cafd | 236 | #endif |
54b52d87 | 237 | |
5f64ec64 PA |
238 | /* |
239 | * Stack and heap for uncompression | |
240 | */ | |
241 | .bss | |
242 | .balign 4 | |
7c539764 AH |
243 | boot_heap: |
244 | .fill BOOT_HEAP_SIZE, 1, 0 | |
245 | boot_stack: | |
246 | .fill BOOT_STACK_SIZE, 1, 0 | |
247 | boot_stack_end: |