Merge branch 'upstream'
[deliverable/linux.git] / arch / x86_64 / kernel / head.S
CommitLineData
1da177e4
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1/*
2 * linux/arch/x86_64/kernel/head.S -- start in 32bit and switch to 64bit
3 *
4 * Copyright (C) 2000 Andrea Arcangeli <andrea@suse.de> SuSE
5 * Copyright (C) 2000 Pavel Machek <pavel@suse.cz>
6 * Copyright (C) 2000 Karsten Keil <kkeil@suse.de>
7 * Copyright (C) 2001,2002 Andi Kleen <ak@suse.de>
8 *
9 * $Id: head.S,v 1.49 2002/03/19 17:39:25 ak Exp $
10 */
11
12
13#include <linux/linkage.h>
14#include <linux/threads.h>
f6c2e333 15#include <linux/init.h>
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16#include <asm/desc.h>
17#include <asm/segment.h>
18#include <asm/page.h>
19#include <asm/msr.h>
20#include <asm/cache.h>
21
22/* we are not able to switch in one step to the final KERNEL ADRESS SPACE
23 * because we need identity-mapped pages on setup so define __START_KERNEL to
24 * 0x100000 for this stage
25 *
26 */
27
28 .text
29 .code32
30 .globl startup_32
31/* %bx: 1 if coming from smp trampoline on secondary cpu */
32startup_32:
33
34 /*
35 * At this point the CPU runs in 32bit protected mode (CS.D = 1) with
36 * paging disabled and the point of this file is to switch to 64bit
37 * long mode with a kernel mapping for kerneland to jump into the
38 * kernel virtual addresses.
39 * There is no stack until we set one up.
40 */
41
42 /* Initialize the %ds segment register */
43 movl $__KERNEL_DS,%eax
44 movl %eax,%ds
45
46 /* Load new GDT with the 64bit segments using 32bit descriptor */
47 lgdt pGDT32 - __START_KERNEL_map
48
49 /* If the CPU doesn't support CPUID this will double fault.
50 * Unfortunately it is hard to check for CPUID without a stack.
51 */
52
53 /* Check if extended functions are implemented */
54 movl $0x80000000, %eax
55 cpuid
56 cmpl $0x80000000, %eax
57 jbe no_long_mode
58 /* Check if long mode is implemented */
59 mov $0x80000001, %eax
60 cpuid
61 btl $29, %edx
62 jnc no_long_mode
63
64 /*
65 * Prepare for entering 64bits mode
66 */
67
68 /* Enable PAE mode */
69 xorl %eax, %eax
70 btsl $5, %eax
71 movl %eax, %cr4
72
73 /* Setup early boot stage 4 level pagetables */
f6c2e333 74 movl $(boot_level4_pgt - __START_KERNEL_map), %eax
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75 movl %eax, %cr3
76
77 /* Setup EFER (Extended Feature Enable Register) */
78 movl $MSR_EFER, %ecx
79 rdmsr
80
81 /* Enable Long Mode */
82 btsl $_EFER_LME, %eax
83
84 /* Make changes effective */
85 wrmsr
86
87 xorl %eax, %eax
88 btsl $31, %eax /* Enable paging and in turn activate Long Mode */
89 btsl $0, %eax /* Enable protected mode */
90 /* Make changes effective */
91 movl %eax, %cr0
92 /*
93 * At this point we're in long mode but in 32bit compatibility mode
94 * with EFER.LME = 1, CS.L = 0, CS.D = 1 (and in turn
95 * EFER.LMA = 1). Now we want to jump in 64bit mode, to do that we use
96 * the new gdt/idt that has __KERNEL_CS with CS.L = 1.
97 */
98 ljmp $__KERNEL_CS, $(startup_64 - __START_KERNEL_map)
99
100 .code64
101 .org 0x100
102 .globl startup_64
103startup_64:
104 /* We come here either from startup_32
105 * or directly from a 64bit bootloader.
106 * Since we may have come directly from a bootloader we
107 * reload the page tables here.
108 */
109
110 /* Enable PAE mode and PGE */
111 xorq %rax, %rax
112 btsq $5, %rax
113 btsq $7, %rax
114 movq %rax, %cr4
115
116 /* Setup early boot stage 4 level pagetables. */
f6c2e333 117 movq $(boot_level4_pgt - __START_KERNEL_map), %rax
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118 movq %rax, %cr3
119
120 /* Check if nx is implemented */
121 movl $0x80000001, %eax
122 cpuid
123 movl %edx,%edi
124
125 /* Setup EFER (Extended Feature Enable Register) */
126 movl $MSR_EFER, %ecx
127 rdmsr
128
129 /* Enable System Call */
130 btsl $_EFER_SCE, %eax
131
132 /* No Execute supported? */
133 btl $20,%edi
134 jnc 1f
135 btsl $_EFER_NX, %eax
1361:
137 /* Make changes effective */
138 wrmsr
139
140 /* Setup cr0 */
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141#define CR0_PM 1 /* protected mode */
142#define CR0_MP (1<<1)
143#define CR0_ET (1<<4)
144#define CR0_NE (1<<5)
145#define CR0_WP (1<<16)
146#define CR0_AM (1<<18)
147#define CR0_PAGING (1<<31)
148 movl $CR0_PM|CR0_MP|CR0_ET|CR0_NE|CR0_WP|CR0_AM|CR0_PAGING,%eax
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149 /* Make changes effective */
150 movq %rax, %cr0
151
152 /* Setup a boot time stack */
153 movq init_rsp(%rip),%rsp
154
155 /* zero EFLAGS after setting rsp */
156 pushq $0
157 popfq
158
159 /*
160 * We must switch to a new descriptor in kernel space for the GDT
161 * because soon the kernel won't have access anymore to the userspace
162 * addresses where we're currently running on. We have to do that here
163 * because in 32bit we couldn't load a 64bit linear address.
164 */
165 lgdt cpu_gdt_descr
166
167 /*
168 * Setup up a dummy PDA. this is just for some early bootup code
169 * that does in_interrupt()
170 */
171 movl $MSR_GS_BASE,%ecx
172 movq $empty_zero_page,%rax
173 movq %rax,%rdx
174 shrq $32,%rdx
175 wrmsr
176
177 /* set up data segments. actually 0 would do too */
178 movl $__KERNEL_DS,%eax
179 movl %eax,%ds
180 movl %eax,%ss
181 movl %eax,%es
182
183 /* esi is pointer to real mode structure with interesting info.
184 pass it to C */
185 movl %esi, %edi
186
187 /* Finally jump to run C code and to be on real kernel address
188 * Since we are running on identity-mapped space we have to jump
189 * to the full 64bit address , this is only possible as indirect
190 * jump
191 */
192 movq initial_code(%rip),%rax
193 jmp *%rax
194
195 /* SMP bootup changes these two */
196 .globl initial_code
197initial_code:
198 .quad x86_64_start_kernel
199 .globl init_rsp
200init_rsp:
201 .quad init_thread_union+THREAD_SIZE-8
202
203ENTRY(early_idt_handler)
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204 cmpl $2,early_recursion_flag(%rip)
205 jz 1f
206 incl early_recursion_flag(%rip)
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207 xorl %eax,%eax
208 movq 8(%rsp),%rsi # get rip
209 movq (%rsp),%rdx
210 movq %cr2,%rcx
211 leaq early_idt_msg(%rip),%rdi
212 call early_printk
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213 cmpl $2,early_recursion_flag(%rip)
214 jz 1f
215 call dump_stack
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216#ifdef CONFIG_KALLSYMS
217 leaq early_idt_ripmsg(%rip),%rdi
218 movq 8(%rsp),%rsi # get rip again
219 call __print_symbol
220#endif
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2211: hlt
222 jmp 1b
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223early_recursion_flag:
224 .long 0
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225
226early_idt_msg:
227 .asciz "PANIC: early exception rip %lx error %lx cr2 %lx\n"
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228early_idt_ripmsg:
229 .asciz "RIP %s\n"
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230
231.code32
232ENTRY(no_long_mode)
233 /* This isn't an x86-64 CPU so hang */
2341:
235 jmp 1b
236
237.org 0xf00
238 .globl pGDT32
239pGDT32:
240 .word gdt_end-cpu_gdt_table
241 .long cpu_gdt_table-__START_KERNEL_map
242
243.org 0xf10
244ljumpvector:
245 .long startup_64-__START_KERNEL_map
246 .word __KERNEL_CS
247
248ENTRY(stext)
249ENTRY(_stext)
250
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JB
251 $page = 0
252#define NEXT_PAGE(name) \
253 $page = $page + 1; \
254 .org $page * 0x1000; \
255 phys_/**/name = $page * 0x1000 + __PHYSICAL_START; \
256ENTRY(name)
257
258NEXT_PAGE(init_level4_pgt)
f6c2e333
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259 /* This gets initialized in x86_64_start_kernel */
260 .fill 512,8,0
1da177e4 261
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262NEXT_PAGE(level3_ident_pgt)
263 .quad phys_level2_ident_pgt | 0x007
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264 .fill 511,8,0
265
f0cf5d1a 266NEXT_PAGE(level3_kernel_pgt)
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267 .fill 510,8,0
268 /* (2^48-(2*1024*1024*1024)-((2^39)*511))/(2^30) = 510 */
f0cf5d1a 269 .quad phys_level2_kernel_pgt | 0x007
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270 .fill 1,8,0
271
f0cf5d1a 272NEXT_PAGE(level2_ident_pgt)
1da177e4 273 /* 40MB for bootup. */
f0cf5d1a
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274 i = 0
275 .rept 20
276 .quad i << 21 | 0x083
277 i = i + 1
278 .endr
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279 /* Temporary mappings for the super early allocator in arch/x86_64/mm/init.c */
280 .globl temp_boot_pmds
281temp_boot_pmds:
282 .fill 492,8,0
283
f0cf5d1a 284NEXT_PAGE(level2_kernel_pgt)
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285 /* 40MB kernel mapping. The kernel code cannot be bigger than that.
286 When you change this change KERNEL_TEXT_SIZE in page.h too. */
287 /* (2^48-(2*1024*1024*1024)-((2^39)*511)-((2^30)*510)) = 0 */
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288 i = 0
289 .rept 20
290 .quad i << 21 | 0x183
291 i = i + 1
292 .endr
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293 /* Module mapping starts here */
294 .fill 492,8,0
295
f0cf5d1a 296NEXT_PAGE(empty_zero_page)
1da177e4 297
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298NEXT_PAGE(level3_physmem_pgt)
299 .quad phys_level2_kernel_pgt | 0x007 /* so that __va works even before pagetable_init */
300 .fill 511,8,0
1da177e4 301
f0cf5d1a 302#undef NEXT_PAGE
1da177e4 303
f0cf5d1a 304 .data
1da177e4 305
1da177e4 306#ifdef CONFIG_ACPI_SLEEP
f0cf5d1a 307 .align PAGE_SIZE
1da177e4 308ENTRY(wakeup_level4_pgt)
f0cf5d1a 309 .quad phys_level3_ident_pgt | 0x007
1da177e4 310 .fill 255,8,0
f0cf5d1a 311 .quad phys_level3_physmem_pgt | 0x007
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312 .fill 254,8,0
313 /* (2^48-(2*1024*1024*1024))/(2^39) = 511 */
f0cf5d1a 314 .quad phys_level3_kernel_pgt | 0x007
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315#endif
316
f6c2e333
SS
317#ifndef CONFIG_HOTPLUG_CPU
318 __INITDATA
319#endif
320 /*
321 * This default setting generates an ident mapping at address 0x100000
322 * and a mapping for the kernel that precisely maps virtual address
323 * 0xffffffff80000000 to physical address 0x000000. (always using
324 * 2Mbyte large pages provided by PAE mode)
325 */
326 .align PAGE_SIZE
327ENTRY(boot_level4_pgt)
f0cf5d1a 328 .quad phys_level3_ident_pgt | 0x007
f6c2e333 329 .fill 255,8,0
f0cf5d1a 330 .quad phys_level3_physmem_pgt | 0x007
f6c2e333
SS
331 .fill 254,8,0
332 /* (2^48-(2*1024*1024*1024))/(2^39) = 511 */
f0cf5d1a 333 .quad phys_level3_kernel_pgt | 0x007
f6c2e333 334
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335 .data
336
337 .align 16
338 .globl cpu_gdt_descr
339cpu_gdt_descr:
340 .word gdt_end-cpu_gdt_table
341gdt:
342 .quad cpu_gdt_table
343#ifdef CONFIG_SMP
344 .rept NR_CPUS-1
345 .word 0
346 .quad 0
347 .endr
348#endif
349
350/* We need valid kernel segments for data and code in long mode too
351 * IRET will check the segment types kkeil 2000/10/28
352 * Also sysret mandates a special GDT layout
353 */
354
c11efdf9 355.align PAGE_SIZE
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356
357/* The TLS descriptors are currently at a different place compared to i386.
358 Hopefully nobody expects them at a fixed place (Wine?) */
359
360ENTRY(cpu_gdt_table)
361 .quad 0x0000000000000000 /* NULL descriptor */
cdc4b9c0 362 .quad 0x0 /* unused */
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363 .quad 0x00af9a000000ffff /* __KERNEL_CS */
364 .quad 0x00cf92000000ffff /* __KERNEL_DS */
365 .quad 0x00cffa000000ffff /* __USER32_CS */
366 .quad 0x00cff2000000ffff /* __USER_DS, __USER32_DS */
367 .quad 0x00affa000000ffff /* __USER_CS */
368 .quad 0x00cf9a000000ffff /* __KERNEL32_CS */
369 .quad 0,0 /* TSS */
370 .quad 0,0 /* LDT */
371 .quad 0,0,0 /* three TLS descriptors */
cdc4b9c0 372 .quad 0 /* unused */
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373gdt_end:
374 /* asm/segment.h:GDT_ENTRIES must match this */
375 /* This should be a multiple of the cache line size */
c11efdf9
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376 /* GDTs of other CPUs are now dynamically allocated */
377
378 /* zero the remaining page */
379 .fill PAGE_SIZE / 8 - GDT_ENTRIES,8,0
1da177e4 380
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381ENTRY(idt_table)
382 .rept 256
383 .quad 0
384 .quad 0
385 .endr
386
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