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CommitLineData
1da177e4
LT
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>
1da177e4
LT
8 */
9
10
11#include <linux/linkage.h>
12#include <linux/threads.h>
f6c2e333 13#include <linux/init.h>
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LT
14#include <asm/desc.h>
15#include <asm/segment.h>
16#include <asm/page.h>
17#include <asm/msr.h>
18#include <asm/cache.h>
19
20/* we are not able to switch in one step to the final KERNEL ADRESS SPACE
21 * because we need identity-mapped pages on setup so define __START_KERNEL to
22 * 0x100000 for this stage
23 *
24 */
25
26 .text
eaeae0cc 27 .section .bootstrap.text
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LT
28 .code32
29 .globl startup_32
30/* %bx: 1 if coming from smp trampoline on secondary cpu */
31startup_32:
32
33 /*
34 * At this point the CPU runs in 32bit protected mode (CS.D = 1) with
35 * paging disabled and the point of this file is to switch to 64bit
36 * long mode with a kernel mapping for kerneland to jump into the
37 * kernel virtual addresses.
38 * There is no stack until we set one up.
39 */
40
41 /* Initialize the %ds segment register */
42 movl $__KERNEL_DS,%eax
43 movl %eax,%ds
44
45 /* Load new GDT with the 64bit segments using 32bit descriptor */
46 lgdt pGDT32 - __START_KERNEL_map
47
48 /* If the CPU doesn't support CPUID this will double fault.
49 * Unfortunately it is hard to check for CPUID without a stack.
50 */
51
52 /* Check if extended functions are implemented */
53 movl $0x80000000, %eax
54 cpuid
55 cmpl $0x80000000, %eax
56 jbe no_long_mode
57 /* Check if long mode is implemented */
58 mov $0x80000001, %eax
59 cpuid
60 btl $29, %edx
61 jnc no_long_mode
62
63 /*
64 * Prepare for entering 64bits mode
65 */
66
67 /* Enable PAE mode */
68 xorl %eax, %eax
69 btsl $5, %eax
70 movl %eax, %cr4
71
72 /* Setup early boot stage 4 level pagetables */
f6c2e333 73 movl $(boot_level4_pgt - __START_KERNEL_map), %eax
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LT
74 movl %eax, %cr3
75
76 /* Setup EFER (Extended Feature Enable Register) */
77 movl $MSR_EFER, %ecx
78 rdmsr
79
80 /* Enable Long Mode */
81 btsl $_EFER_LME, %eax
82
83 /* Make changes effective */
84 wrmsr
85
86 xorl %eax, %eax
87 btsl $31, %eax /* Enable paging and in turn activate Long Mode */
88 btsl $0, %eax /* Enable protected mode */
89 /* Make changes effective */
90 movl %eax, %cr0
91 /*
92 * At this point we're in long mode but in 32bit compatibility mode
93 * with EFER.LME = 1, CS.L = 0, CS.D = 1 (and in turn
94 * EFER.LMA = 1). Now we want to jump in 64bit mode, to do that we use
95 * the new gdt/idt that has __KERNEL_CS with CS.L = 1.
96 */
97 ljmp $__KERNEL_CS, $(startup_64 - __START_KERNEL_map)
98
99 .code64
100 .org 0x100
101 .globl startup_64
102startup_64:
103 /* We come here either from startup_32
104 * or directly from a 64bit bootloader.
105 * Since we may have come directly from a bootloader we
106 * reload the page tables here.
107 */
108
109 /* Enable PAE mode and PGE */
110 xorq %rax, %rax
111 btsq $5, %rax
112 btsq $7, %rax
113 movq %rax, %cr4
114
115 /* Setup early boot stage 4 level pagetables. */
f6c2e333 116 movq $(boot_level4_pgt - __START_KERNEL_map), %rax
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117 movq %rax, %cr3
118
119 /* Check if nx is implemented */
120 movl $0x80000001, %eax
121 cpuid
122 movl %edx,%edi
123
124 /* Setup EFER (Extended Feature Enable Register) */
125 movl $MSR_EFER, %ecx
126 rdmsr
127
128 /* Enable System Call */
129 btsl $_EFER_SCE, %eax
130
131 /* No Execute supported? */
132 btl $20,%edi
133 jnc 1f
134 btsl $_EFER_NX, %eax
1351:
136 /* Make changes effective */
137 wrmsr
138
139 /* Setup cr0 */
3829ee6b
AK
140#define CR0_PM 1 /* protected mode */
141#define CR0_MP (1<<1)
142#define CR0_ET (1<<4)
143#define CR0_NE (1<<5)
144#define CR0_WP (1<<16)
145#define CR0_AM (1<<18)
146#define CR0_PAGING (1<<31)
147 movl $CR0_PM|CR0_MP|CR0_ET|CR0_NE|CR0_WP|CR0_AM|CR0_PAGING,%eax
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LT
148 /* Make changes effective */
149 movq %rax, %cr0
150
151 /* Setup a boot time stack */
152 movq init_rsp(%rip),%rsp
153
154 /* zero EFLAGS after setting rsp */
155 pushq $0
156 popfq
157
158 /*
159 * We must switch to a new descriptor in kernel space for the GDT
160 * because soon the kernel won't have access anymore to the userspace
161 * addresses where we're currently running on. We have to do that here
162 * because in 32bit we couldn't load a 64bit linear address.
163 */
164 lgdt cpu_gdt_descr
165
166 /*
167 * Setup up a dummy PDA. this is just for some early bootup code
168 * that does in_interrupt()
169 */
170 movl $MSR_GS_BASE,%ecx
171 movq $empty_zero_page,%rax
172 movq %rax,%rdx
173 shrq $32,%rdx
174 wrmsr
175
176 /* set up data segments. actually 0 would do too */
177 movl $__KERNEL_DS,%eax
178 movl %eax,%ds
179 movl %eax,%ss
180 movl %eax,%es
181
182 /* esi is pointer to real mode structure with interesting info.
183 pass it to C */
184 movl %esi, %edi
185
186 /* Finally jump to run C code and to be on real kernel address
187 * Since we are running on identity-mapped space we have to jump
188 * to the full 64bit address , this is only possible as indirect
189 * jump
190 */
191 movq initial_code(%rip),%rax
c05991ed 192 pushq $0 # fake return address
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LT
193 jmp *%rax
194
e57113bc
JB
195 /* SMP bootup changes these two */
196 .align 8
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LT
197 .globl initial_code
198initial_code:
199 .quad x86_64_start_kernel
200 .globl init_rsp
201init_rsp:
202 .quad init_thread_union+THREAD_SIZE-8
203
204ENTRY(early_idt_handler)
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AK
205 cmpl $2,early_recursion_flag(%rip)
206 jz 1f
207 incl early_recursion_flag(%rip)
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LT
208 xorl %eax,%eax
209 movq 8(%rsp),%rsi # get rip
210 movq (%rsp),%rdx
211 movq %cr2,%rcx
212 leaq early_idt_msg(%rip),%rdi
213 call early_printk
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AK
214 cmpl $2,early_recursion_flag(%rip)
215 jz 1f
216 call dump_stack
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AK
217#ifdef CONFIG_KALLSYMS
218 leaq early_idt_ripmsg(%rip),%rdi
219 movq 8(%rsp),%rsi # get rip again
220 call __print_symbol
221#endif
1da177e4
LT
2221: hlt
223 jmp 1b
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AK
224early_recursion_flag:
225 .long 0
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LT
226
227early_idt_msg:
228 .asciz "PANIC: early exception rip %lx error %lx cr2 %lx\n"
6574ffd7
AK
229early_idt_ripmsg:
230 .asciz "RIP %s\n"
1da177e4
LT
231
232.code32
233ENTRY(no_long_mode)
234 /* This isn't an x86-64 CPU so hang */
2351:
236 jmp 1b
237
238.org 0xf00
239 .globl pGDT32
240pGDT32:
e57113bc 241 .word gdt_end-cpu_gdt_table-1
1da177e4
LT
242 .long cpu_gdt_table-__START_KERNEL_map
243
244.org 0xf10
245ljumpvector:
246 .long startup_64-__START_KERNEL_map
247 .word __KERNEL_CS
248
249ENTRY(stext)
250ENTRY(_stext)
251
f0cf5d1a
JB
252 $page = 0
253#define NEXT_PAGE(name) \
254 $page = $page + 1; \
255 .org $page * 0x1000; \
256 phys_/**/name = $page * 0x1000 + __PHYSICAL_START; \
257ENTRY(name)
258
259NEXT_PAGE(init_level4_pgt)
f6c2e333
SS
260 /* This gets initialized in x86_64_start_kernel */
261 .fill 512,8,0
1da177e4 262
f0cf5d1a
JB
263NEXT_PAGE(level3_ident_pgt)
264 .quad phys_level2_ident_pgt | 0x007
1da177e4
LT
265 .fill 511,8,0
266
f0cf5d1a 267NEXT_PAGE(level3_kernel_pgt)
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LT
268 .fill 510,8,0
269 /* (2^48-(2*1024*1024*1024)-((2^39)*511))/(2^30) = 510 */
f0cf5d1a 270 .quad phys_level2_kernel_pgt | 0x007
1da177e4
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271 .fill 1,8,0
272
f0cf5d1a 273NEXT_PAGE(level2_ident_pgt)
1da177e4 274 /* 40MB for bootup. */
f0cf5d1a
JB
275 i = 0
276 .rept 20
277 .quad i << 21 | 0x083
278 i = i + 1
279 .endr
1da177e4
LT
280 /* Temporary mappings for the super early allocator in arch/x86_64/mm/init.c */
281 .globl temp_boot_pmds
282temp_boot_pmds:
283 .fill 492,8,0
284
f0cf5d1a 285NEXT_PAGE(level2_kernel_pgt)
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286 /* 40MB kernel mapping. The kernel code cannot be bigger than that.
287 When you change this change KERNEL_TEXT_SIZE in page.h too. */
288 /* (2^48-(2*1024*1024*1024)-((2^39)*511)-((2^30)*510)) = 0 */
f0cf5d1a
JB
289 i = 0
290 .rept 20
291 .quad i << 21 | 0x183
292 i = i + 1
293 .endr
1da177e4
LT
294 /* Module mapping starts here */
295 .fill 492,8,0
296
f0cf5d1a
JB
297NEXT_PAGE(level3_physmem_pgt)
298 .quad phys_level2_kernel_pgt | 0x007 /* so that __va works even before pagetable_init */
299 .fill 511,8,0
1da177e4 300
f0cf5d1a 301#undef NEXT_PAGE
1da177e4 302
f0cf5d1a 303 .data
1da177e4 304
1da177e4 305#ifdef CONFIG_ACPI_SLEEP
f0cf5d1a 306 .align PAGE_SIZE
1da177e4 307ENTRY(wakeup_level4_pgt)
f0cf5d1a 308 .quad phys_level3_ident_pgt | 0x007
1da177e4 309 .fill 255,8,0
f0cf5d1a 310 .quad phys_level3_physmem_pgt | 0x007
1da177e4
LT
311 .fill 254,8,0
312 /* (2^48-(2*1024*1024*1024))/(2^39) = 511 */
f0cf5d1a 313 .quad phys_level3_kernel_pgt | 0x007
1da177e4
LT
314#endif
315
f6c2e333
SS
316#ifndef CONFIG_HOTPLUG_CPU
317 __INITDATA
318#endif
319 /*
320 * This default setting generates an ident mapping at address 0x100000
321 * and a mapping for the kernel that precisely maps virtual address
322 * 0xffffffff80000000 to physical address 0x000000. (always using
323 * 2Mbyte large pages provided by PAE mode)
324 */
325 .align PAGE_SIZE
326ENTRY(boot_level4_pgt)
f0cf5d1a 327 .quad phys_level3_ident_pgt | 0x007
f6c2e333 328 .fill 255,8,0
f0cf5d1a 329 .quad phys_level3_physmem_pgt | 0x007
f6c2e333
SS
330 .fill 254,8,0
331 /* (2^48-(2*1024*1024*1024))/(2^39) = 511 */
f0cf5d1a 332 .quad phys_level3_kernel_pgt | 0x007
f6c2e333 333
1da177e4
LT
334 .data
335
336 .align 16
337 .globl cpu_gdt_descr
338cpu_gdt_descr:
e57113bc 339 .word gdt_end-cpu_gdt_table-1
1da177e4
LT
340gdt:
341 .quad cpu_gdt_table
342#ifdef CONFIG_SMP
343 .rept NR_CPUS-1
344 .word 0
345 .quad 0
346 .endr
347#endif
348
349/* We need valid kernel segments for data and code in long mode too
350 * IRET will check the segment types kkeil 2000/10/28
351 * Also sysret mandates a special GDT layout
352 */
353
e57113bc
JB
354 .section .data.page_aligned, "aw"
355 .align PAGE_SIZE
1da177e4
LT
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 */
1da177e4
LT
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 */
c08c8205 372 .quad 0x0000f40000000000 /* node/CPU stored in limit */
1da177e4
LT
373gdt_end:
374 /* asm/segment.h:GDT_ENTRIES must match this */
375 /* This should be a multiple of the cache line size */
c11efdf9
RT
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
e57113bc
JB
381 .section .bss, "aw", @nobits
382 .align L1_CACHE_BYTES
383ENTRY(idt_table)
384 .skip 256 * 16
1da177e4 385
e57113bc
JB
386 .section .bss.page_aligned, "aw", @nobits
387 .align PAGE_SIZE
388ENTRY(empty_zero_page)
389 .skip PAGE_SIZE