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 | ||
9ca8f72a MF |
45 | call make_boot_params |
46 | cmpl $0, %eax | |
47 | je 1f | |
48 | movl 0x4(%esp), %esi | |
49 | movl (%esp), %ecx | |
50 | pushl %eax | |
51 | pushl %esi | |
52 | pushl %ecx | |
f791620f | 53 | sub $0x4, %esp |
9ca8f72a | 54 | |
99f857db | 55 | ENTRY(efi_stub_entry) |
f791620f | 56 | add $0x4, %esp |
291f3632 MF |
57 | call efi_main |
58 | cmpl $0, %eax | |
291f3632 | 59 | movl %eax, %esi |
b1994304 | 60 | jne 2f |
291f3632 | 61 | 1: |
b1994304 MF |
62 | /* EFI init failed, so hang. */ |
63 | hlt | |
64 | jmp 1b | |
65 | 2: | |
66 | call 3f | |
67 | 3: | |
291f3632 | 68 | popl %eax |
b1994304 | 69 | subl $3b, %eax |
291f3632 MF |
70 | subl BP_pref_address(%esi), %eax |
71 | add BP_code32_start(%esi), %eax | |
72 | leal preferred_addr(%eax), %eax | |
73 | jmp *%eax | |
74 | ||
75 | preferred_addr: | |
76 | #endif | |
bd53147d | 77 | cld |
5f64ec64 PA |
78 | /* |
79 | * Test KEEP_SEGMENTS flag to see if the bootloader is asking | |
80 | * us to not reload segments | |
81 | */ | |
82 | testb $(1<<6), BP_loadflags(%esi) | |
83 | jnz 1f | |
a24e7851 | 84 | |
bd53147d | 85 | cli |
5f64ec64 PA |
86 | movl $__BOOT_DS, %eax |
87 | movl %eax, %ds | |
88 | movl %eax, %es | |
89 | movl %eax, %fs | |
90 | movl %eax, %gs | |
91 | movl %eax, %ss | |
bd53147d | 92 | 1: |
a24e7851 | 93 | |
5f64ec64 PA |
94 | /* |
95 | * Calculate the delta between where we were compiled to run | |
968de4f0 EB |
96 | * at and where we were actually loaded at. This can only be done |
97 | * with a short local call on x86. Nothing else will tell us what | |
98 | * address we are running at. The reserved chunk of the real-mode | |
85414b69 PA |
99 | * data at 0x1e4 (defined as a scratch field) are used as the stack |
100 | * for this calculation. Only 4 bytes are needed. | |
968de4f0 | 101 | */ |
5f64ec64 PA |
102 | leal (BP_scratch+4)(%esi), %esp |
103 | call 1f | |
104 | 1: popl %ebp | |
105 | subl $1b, %ebp | |
968de4f0 | 106 | |
5f64ec64 PA |
107 | /* |
108 | * %ebp contains the address we are loaded at by the boot loader and %ebx | |
e69f202d VG |
109 | * contains the address where we should move the kernel image temporarily |
110 | * for safe in-place decompression. | |
968de4f0 | 111 | */ |
e69f202d | 112 | |
968de4f0 | 113 | #ifdef CONFIG_RELOCATABLE |
5f64ec64 | 114 | movl %ebp, %ebx |
37ba7ab5 PA |
115 | movl BP_kernel_alignment(%esi), %eax |
116 | decl %eax | |
117 | addl %eax, %ebx | |
118 | notl %eax | |
119 | andl %eax, %ebx | |
968de4f0 | 120 | #else |
5f64ec64 | 121 | movl $LOAD_PHYSICAL_ADDR, %ebx |
968de4f0 EB |
122 | #endif |
123 | ||
02a884c0 PA |
124 | /* Target address to relocate to for decompression */ |
125 | addl $z_extract_offset, %ebx | |
968de4f0 | 126 | |
0a137736 PA |
127 | /* Set up the stack */ |
128 | leal boot_stack_end(%ebx), %esp | |
129 | ||
97541912 PA |
130 | /* Zero EFLAGS */ |
131 | pushl $0 | |
132 | popfl | |
133 | ||
5f64ec64 PA |
134 | /* |
135 | * Copy the compressed kernel to the end of our buffer | |
968de4f0 EB |
136 | * where decompression in place becomes safe. |
137 | */ | |
5f64ec64 | 138 | pushl %esi |
36d3793c PA |
139 | leal (_bss-4)(%ebp), %esi |
140 | leal (_bss-4)(%ebx), %edi | |
5b11f1ce | 141 | movl $(_bss - startup_32), %ecx |
36d3793c | 142 | shrl $2, %ecx |
968de4f0 | 143 | std |
36d3793c | 144 | rep movsl |
968de4f0 | 145 | cld |
5f64ec64 | 146 | popl %esi |
968de4f0 | 147 | |
1da177e4 | 148 | /* |
968de4f0 | 149 | * Jump to the relocated address. |
1da177e4 | 150 | */ |
5f64ec64 PA |
151 | leal relocated(%ebx), %eax |
152 | jmp *%eax | |
cb425afd CG |
153 | ENDPROC(startup_32) |
154 | ||
5f64ec64 | 155 | .text |
968de4f0 EB |
156 | relocated: |
157 | ||
1da177e4 | 158 | /* |
0a137736 | 159 | * Clear BSS (stack is currently empty) |
1da177e4 | 160 | */ |
5f64ec64 | 161 | xorl %eax, %eax |
5b11f1ce | 162 | leal _bss(%ebx), %edi |
5f64ec64 PA |
163 | leal _ebss(%ebx), %ecx |
164 | subl %edi, %ecx | |
36d3793c PA |
165 | shrl $2, %ecx |
166 | rep stosl | |
968de4f0 | 167 | |
22a57f58 PA |
168 | /* |
169 | * Adjust our own GOT | |
170 | */ | |
171 | leal _got(%ebx), %edx | |
172 | leal _egot(%ebx), %ecx | |
173 | 1: | |
174 | cmpl %ecx, %edx | |
175 | jae 2f | |
176 | addl %ebx, (%edx) | |
177 | addl $4, %edx | |
178 | jmp 1b | |
179 | 2: | |
180 | ||
1da177e4 LT |
181 | /* |
182 | * Do the decompression, and jump to the new kernel.. | |
183 | */ | |
02a884c0 | 184 | leal z_extract_offset_negative(%ebx), %ebp |
5f64ec64 PA |
185 | /* push arguments for decompress_kernel: */ |
186 | pushl %ebp /* output address */ | |
02a884c0 | 187 | pushl $z_input_len /* input_len */ |
5f64ec64 PA |
188 | leal input_data(%ebx), %eax |
189 | pushl %eax /* input_data */ | |
190 | leal boot_heap(%ebx), %eax | |
191 | pushl %eax /* heap area */ | |
192 | pushl %esi /* real mode pointer */ | |
193 | call decompress_kernel | |
194 | addl $20, %esp | |
968de4f0 EB |
195 | |
196 | #if CONFIG_RELOCATABLE | |
5f64ec64 PA |
197 | /* |
198 | * Find the address of the relocations. | |
968de4f0 | 199 | */ |
02a884c0 | 200 | leal z_output_len(%ebp), %edi |
968de4f0 | 201 | |
5f64ec64 PA |
202 | /* |
203 | * Calculate the delta between where vmlinux was compiled to run | |
968de4f0 EB |
204 | * and where it was actually loaded. |
205 | */ | |
5f64ec64 PA |
206 | movl %ebp, %ebx |
207 | subl $LOAD_PHYSICAL_ADDR, %ebx | |
208 | jz 2f /* Nothing to be done if loaded at compiled addr. */ | |
1da177e4 | 209 | /* |
968de4f0 | 210 | * Process relocations. |
1da177e4 | 211 | */ |
968de4f0 | 212 | |
5f64ec64 PA |
213 | 1: subl $4, %edi |
214 | movl (%edi), %ecx | |
215 | testl %ecx, %ecx | |
216 | jz 2f | |
217 | addl %ebx, -__PAGE_OFFSET(%ebx, %ecx) | |
218 | jmp 1b | |
968de4f0 EB |
219 | 2: |
220 | #endif | |
1da177e4 LT |
221 | |
222 | /* | |
968de4f0 | 223 | * Jump to the decompressed kernel. |
1da177e4 | 224 | */ |
5f64ec64 PA |
225 | xorl %ebx, %ebx |
226 | jmp *%ebp | |
968de4f0 | 227 | |
5f64ec64 PA |
228 | /* |
229 | * Stack and heap for uncompression | |
230 | */ | |
231 | .bss | |
232 | .balign 4 | |
7c539764 AH |
233 | boot_heap: |
234 | .fill BOOT_HEAP_SIZE, 1, 0 | |
235 | boot_stack: | |
236 | .fill BOOT_STACK_SIZE, 1, 0 | |
237 | boot_stack_end: |