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> |
fb148d83 | 32 | #include <asm/bootparam.h> |
1da177e4 | 33 | |
6d92bc9d L |
34 | /* |
35 | * The 32-bit x86 assembler in binutils 2.26 will generate R_386_GOT32X | |
36 | * relocation to get the symbol address in PIC. When the compressed x86 | |
37 | * kernel isn't built as PIC, the linker optimizes R_386_GOT32X | |
38 | * relocations to their fixed symbol addresses. However, when the | |
39 | * compressed x86 kernel is loaded at a different address, it leads | |
40 | * to the following load failure: | |
41 | * | |
42 | * Failed to allocate space for phdrs | |
43 | * | |
44 | * during the decompression stage. | |
45 | * | |
46 | * If the compressed x86 kernel is relocatable at run-time, it should be | |
47 | * compiled with -fPIE, instead of -fPIC, if possible and should be built as | |
48 | * Position Independent Executable (PIE) so that linker won't optimize | |
49 | * R_386_GOT32X relocation to its fixed symbol address. Older | |
50 | * linkers generate R_386_32 relocations against locally defined symbols, | |
51 | * _bss, _ebss, _got and _egot, in PIE. It isn't wrong, just less | |
52 | * optimal than R_386_RELATIVE. But the x86 kernel fails to properly handle | |
53 | * R_386_32 relocations when relocating the kernel. To generate | |
54 | * R_386_RELATIVE relocations, we mark _bss, _ebss, _got and _egot as | |
55 | * hidden: | |
56 | */ | |
57 | .hidden _bss | |
58 | .hidden _ebss | |
59 | .hidden _got | |
60 | .hidden _egot | |
61 | ||
1dc818c1 | 62 | __HEAD |
cb425afd | 63 | ENTRY(startup_32) |
291f3632 | 64 | #ifdef CONFIG_EFI_STUB |
b1994304 MF |
65 | jmp preferred_addr |
66 | ||
291f3632 MF |
67 | /* |
68 | * We don't need the return address, so set up the stack so | |
99f857db | 69 | * efi_main() can find its arguments. |
291f3632 | 70 | */ |
99f857db | 71 | ENTRY(efi_pe_entry) |
291f3632 MF |
72 | add $0x4, %esp |
73 | ||
54b52d87 MF |
74 | call 1f |
75 | 1: popl %esi | |
76 | subl $1b, %esi | |
77 | ||
78 | popl %ecx | |
79 | movl %ecx, efi32_config(%esi) /* Handle */ | |
80 | popl %ecx | |
81 | movl %ecx, efi32_config+8(%esi) /* EFI System table pointer */ | |
82 | ||
83 | /* Relocate efi_config->call() */ | |
84 | leal efi32_config(%esi), %eax | |
85 | add %esi, 88(%eax) | |
86 | pushl %eax | |
87 | ||
9ca8f72a MF |
88 | call make_boot_params |
89 | cmpl $0, %eax | |
54b52d87 | 90 | je fail |
7e8213c1 | 91 | movl %esi, BP_code32_start(%eax) |
54b52d87 | 92 | popl %ecx |
9ca8f72a | 93 | pushl %eax |
9ca8f72a | 94 | pushl %ecx |
54b52d87 | 95 | jmp 2f /* Skip efi_config initialization */ |
9ca8f72a | 96 | |
b8ff87a6 | 97 | ENTRY(efi32_stub_entry) |
f791620f | 98 | add $0x4, %esp |
54b52d87 MF |
99 | popl %ecx |
100 | popl %edx | |
101 | ||
102 | call 1f | |
103 | 1: popl %esi | |
104 | subl $1b, %esi | |
105 | ||
106 | movl %ecx, efi32_config(%esi) /* Handle */ | |
107 | movl %edx, efi32_config+8(%esi) /* EFI System table pointer */ | |
108 | ||
109 | /* Relocate efi_config->call() */ | |
110 | leal efi32_config(%esi), %eax | |
111 | add %esi, 88(%eax) | |
112 | pushl %eax | |
113 | 2: | |
291f3632 MF |
114 | call efi_main |
115 | cmpl $0, %eax | |
291f3632 | 116 | movl %eax, %esi |
b1994304 | 117 | jne 2f |
54b52d87 | 118 | fail: |
b1994304 MF |
119 | /* EFI init failed, so hang. */ |
120 | hlt | |
54b52d87 | 121 | jmp fail |
b1994304 | 122 | 2: |
7e8213c1 | 123 | movl BP_code32_start(%esi), %eax |
291f3632 MF |
124 | leal preferred_addr(%eax), %eax |
125 | jmp *%eax | |
126 | ||
127 | preferred_addr: | |
128 | #endif | |
bd53147d | 129 | cld |
5f64ec64 PA |
130 | /* |
131 | * Test KEEP_SEGMENTS flag to see if the bootloader is asking | |
132 | * us to not reload segments | |
133 | */ | |
fb148d83 | 134 | testb $KEEP_SEGMENTS, BP_loadflags(%esi) |
5f64ec64 | 135 | jnz 1f |
a24e7851 | 136 | |
bd53147d | 137 | cli |
5f64ec64 PA |
138 | movl $__BOOT_DS, %eax |
139 | movl %eax, %ds | |
140 | movl %eax, %es | |
141 | movl %eax, %fs | |
142 | movl %eax, %gs | |
143 | movl %eax, %ss | |
bd53147d | 144 | 1: |
a24e7851 | 145 | |
5f64ec64 PA |
146 | /* |
147 | * Calculate the delta between where we were compiled to run | |
968de4f0 EB |
148 | * at and where we were actually loaded at. This can only be done |
149 | * with a short local call on x86. Nothing else will tell us what | |
150 | * address we are running at. The reserved chunk of the real-mode | |
85414b69 PA |
151 | * data at 0x1e4 (defined as a scratch field) are used as the stack |
152 | * for this calculation. Only 4 bytes are needed. | |
968de4f0 | 153 | */ |
5f64ec64 PA |
154 | leal (BP_scratch+4)(%esi), %esp |
155 | call 1f | |
156 | 1: popl %ebp | |
157 | subl $1b, %ebp | |
968de4f0 | 158 | |
5f64ec64 PA |
159 | /* |
160 | * %ebp contains the address we are loaded at by the boot loader and %ebx | |
e69f202d VG |
161 | * contains the address where we should move the kernel image temporarily |
162 | * for safe in-place decompression. | |
968de4f0 | 163 | */ |
e69f202d | 164 | |
968de4f0 | 165 | #ifdef CONFIG_RELOCATABLE |
5f64ec64 | 166 | movl %ebp, %ebx |
37ba7ab5 PA |
167 | movl BP_kernel_alignment(%esi), %eax |
168 | decl %eax | |
169 | addl %eax, %ebx | |
170 | notl %eax | |
171 | andl %eax, %ebx | |
8ab3820f KC |
172 | cmpl $LOAD_PHYSICAL_ADDR, %ebx |
173 | jge 1f | |
968de4f0 | 174 | #endif |
8ab3820f KC |
175 | movl $LOAD_PHYSICAL_ADDR, %ebx |
176 | 1: | |
968de4f0 | 177 | |
02a884c0 PA |
178 | /* Target address to relocate to for decompression */ |
179 | addl $z_extract_offset, %ebx | |
968de4f0 | 180 | |
0a137736 PA |
181 | /* Set up the stack */ |
182 | leal boot_stack_end(%ebx), %esp | |
183 | ||
97541912 PA |
184 | /* Zero EFLAGS */ |
185 | pushl $0 | |
186 | popfl | |
187 | ||
5f64ec64 PA |
188 | /* |
189 | * Copy the compressed kernel to the end of our buffer | |
968de4f0 EB |
190 | * where decompression in place becomes safe. |
191 | */ | |
5f64ec64 | 192 | pushl %esi |
36d3793c PA |
193 | leal (_bss-4)(%ebp), %esi |
194 | leal (_bss-4)(%ebx), %edi | |
5b11f1ce | 195 | movl $(_bss - startup_32), %ecx |
36d3793c | 196 | shrl $2, %ecx |
968de4f0 | 197 | std |
36d3793c | 198 | rep movsl |
968de4f0 | 199 | cld |
5f64ec64 | 200 | popl %esi |
968de4f0 | 201 | |
1da177e4 | 202 | /* |
968de4f0 | 203 | * Jump to the relocated address. |
1da177e4 | 204 | */ |
5f64ec64 PA |
205 | leal relocated(%ebx), %eax |
206 | jmp *%eax | |
cb425afd CG |
207 | ENDPROC(startup_32) |
208 | ||
5f64ec64 | 209 | .text |
968de4f0 EB |
210 | relocated: |
211 | ||
1da177e4 | 212 | /* |
0a137736 | 213 | * Clear BSS (stack is currently empty) |
1da177e4 | 214 | */ |
5f64ec64 | 215 | xorl %eax, %eax |
5b11f1ce | 216 | leal _bss(%ebx), %edi |
5f64ec64 PA |
217 | leal _ebss(%ebx), %ecx |
218 | subl %edi, %ecx | |
36d3793c PA |
219 | shrl $2, %ecx |
220 | rep stosl | |
968de4f0 | 221 | |
f3670394 LT |
222 | /* |
223 | * Adjust our own GOT | |
224 | */ | |
225 | leal _got(%ebx), %edx | |
226 | leal _egot(%ebx), %ecx | |
227 | 1: | |
228 | cmpl %ecx, %edx | |
229 | jae 2f | |
230 | addl %ebx, (%edx) | |
231 | addl $4, %edx | |
232 | jmp 1b | |
233 | 2: | |
234 | ||
1da177e4 LT |
235 | /* |
236 | * Do the decompression, and jump to the new kernel.. | |
237 | */ | |
5f64ec64 | 238 | /* push arguments for decompress_kernel: */ |
e6023367 JM |
239 | pushl $z_run_size /* size of kernel with .bss and .brk */ |
240 | pushl $z_output_len /* decompressed length, end of relocs */ | |
a0215061 | 241 | leal z_extract_offset_negative(%ebx), %ebp |
5f64ec64 | 242 | pushl %ebp /* output address */ |
02a884c0 | 243 | pushl $z_input_len /* input_len */ |
5f64ec64 PA |
244 | leal input_data(%ebx), %eax |
245 | pushl %eax /* input_data */ | |
246 | leal boot_heap(%ebx), %eax | |
247 | pushl %eax /* heap area */ | |
248 | pushl %esi /* real mode pointer */ | |
8ab3820f | 249 | call decompress_kernel /* returns kernel location in %eax */ |
e6023367 | 250 | addl $28, %esp |
1da177e4 LT |
251 | |
252 | /* | |
968de4f0 | 253 | * Jump to the decompressed kernel. |
1da177e4 | 254 | */ |
5f64ec64 | 255 | xorl %ebx, %ebx |
8ab3820f | 256 | jmp *%eax |
968de4f0 | 257 | |
9cb0e394 | 258 | #ifdef CONFIG_EFI_STUB |
f3670394 | 259 | .data |
54b52d87 MF |
260 | efi32_config: |
261 | .fill 11,8,0 | |
262 | .long efi_call_phys | |
263 | .long 0 | |
264 | .byte 0 | |
3db4cafd | 265 | #endif |
54b52d87 | 266 | |
5f64ec64 PA |
267 | /* |
268 | * Stack and heap for uncompression | |
269 | */ | |
270 | .bss | |
271 | .balign 4 | |
7c539764 AH |
272 | boot_heap: |
273 | .fill BOOT_HEAP_SIZE, 1, 0 | |
274 | boot_stack: | |
275 | .fill BOOT_STACK_SIZE, 1, 0 | |
276 | boot_stack_end: |