xref: /openbmc/linux/arch/x86/kernel/head_32.S (revision f3a8b664) 
1/*
2 *
3 *  Copyright (C) 1991, 1992  Linus Torvalds
4 *
5 *  Enhanced CPU detection and feature setting code by Mike Jagdis
6 *  and Martin Mares, November 1997.
7 */
8
9.text
10#include <linux/threads.h>
11#include <linux/init.h>
12#include <linux/linkage.h>
13#include <asm/segment.h>
14#include <asm/page_types.h>
15#include <asm/pgtable_types.h>
16#include <asm/cache.h>
17#include <asm/thread_info.h>
18#include <asm/asm-offsets.h>
19#include <asm/setup.h>
20#include <asm/processor-flags.h>
21#include <asm/msr-index.h>
22#include <asm/cpufeatures.h>
23#include <asm/percpu.h>
24#include <asm/nops.h>
25#include <asm/bootparam.h>
26#include <asm/export.h>
27
28/* Physical address */
29#define pa(X) ((X) - __PAGE_OFFSET)
30
31/*
32 * References to members of the new_cpu_data structure.
33 */
34
35#define X86		new_cpu_data+CPUINFO_x86
36#define X86_VENDOR	new_cpu_data+CPUINFO_x86_vendor
37#define X86_MODEL	new_cpu_data+CPUINFO_x86_model
38#define X86_MASK	new_cpu_data+CPUINFO_x86_mask
39#define X86_HARD_MATH	new_cpu_data+CPUINFO_hard_math
40#define X86_CPUID	new_cpu_data+CPUINFO_cpuid_level
41#define X86_CAPABILITY	new_cpu_data+CPUINFO_x86_capability
42#define X86_VENDOR_ID	new_cpu_data+CPUINFO_x86_vendor_id
43
44/*
45 * This is how much memory in addition to the memory covered up to
46 * and including _end we need mapped initially.
47 * We need:
48 *     (KERNEL_IMAGE_SIZE/4096) / 1024 pages (worst case, non PAE)
49 *     (KERNEL_IMAGE_SIZE/4096) / 512 + 4 pages (worst case for PAE)
50 *
51 * Modulo rounding, each megabyte assigned here requires a kilobyte of
52 * memory, which is currently unreclaimed.
53 *
54 * This should be a multiple of a page.
55 *
56 * KERNEL_IMAGE_SIZE should be greater than pa(_end)
57 * and small than max_low_pfn, otherwise will waste some page table entries
58 */
59
60#if PTRS_PER_PMD > 1
61#define PAGE_TABLE_SIZE(pages) (((pages) / PTRS_PER_PMD) + PTRS_PER_PGD)
62#else
63#define PAGE_TABLE_SIZE(pages) ((pages) / PTRS_PER_PGD)
64#endif
65
66/*
67 * Number of possible pages in the lowmem region.
68 *
69 * We shift 2 by 31 instead of 1 by 32 to the left in order to avoid a
70 * gas warning about overflowing shift count when gas has been compiled
71 * with only a host target support using a 32-bit type for internal
72 * representation.
73 */
74LOWMEM_PAGES = (((2<<31) - __PAGE_OFFSET) >> PAGE_SHIFT)
75
76/* Enough space to fit pagetables for the low memory linear map */
77MAPPING_BEYOND_END = PAGE_TABLE_SIZE(LOWMEM_PAGES) << PAGE_SHIFT
78
79/*
80 * Worst-case size of the kernel mapping we need to make:
81 * a relocatable kernel can live anywhere in lowmem, so we need to be able
82 * to map all of lowmem.
83 */
84KERNEL_PAGES = LOWMEM_PAGES
85
86INIT_MAP_SIZE = PAGE_TABLE_SIZE(KERNEL_PAGES) * PAGE_SIZE
87RESERVE_BRK(pagetables, INIT_MAP_SIZE)
88
89/*
90 * 32-bit kernel entrypoint; only used by the boot CPU.  On entry,
91 * %esi points to the real-mode code as a 32-bit pointer.
92 * CS and DS must be 4 GB flat segments, but we don't depend on
93 * any particular GDT layout, because we load our own as soon as we
94 * can.
95 */
96__HEAD
97ENTRY(startup_32)
98	movl pa(initial_stack),%ecx
99
100	/* test KEEP_SEGMENTS flag to see if the bootloader is asking
101		us to not reload segments */
102	testb $KEEP_SEGMENTS, BP_loadflags(%esi)
103	jnz 2f
104
105/*
106 * Set segments to known values.
107 */
108	lgdt pa(boot_gdt_descr)
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
1152:
116	leal -__PAGE_OFFSET(%ecx),%esp
117
118/*
119 * Clear BSS first so that there are no surprises...
120 */
121	cld
122	xorl %eax,%eax
123	movl $pa(__bss_start),%edi
124	movl $pa(__bss_stop),%ecx
125	subl %edi,%ecx
126	shrl $2,%ecx
127	rep ; stosl
128/*
129 * Copy bootup parameters out of the way.
130 * Note: %esi still has the pointer to the real-mode data.
131 * With the kexec as boot loader, parameter segment might be loaded beyond
132 * kernel image and might not even be addressable by early boot page tables.
133 * (kexec on panic case). Hence copy out the parameters before initializing
134 * page tables.
135 */
136	movl $pa(boot_params),%edi
137	movl $(PARAM_SIZE/4),%ecx
138	cld
139	rep
140	movsl
141	movl pa(boot_params) + NEW_CL_POINTER,%esi
142	andl %esi,%esi
143	jz 1f			# No command line
144	movl $pa(boot_command_line),%edi
145	movl $(COMMAND_LINE_SIZE/4),%ecx
146	rep
147	movsl
1481:
149
150#ifdef CONFIG_OLPC
151	/* save OFW's pgdir table for later use when calling into OFW */
152	movl %cr3, %eax
153	movl %eax, pa(olpc_ofw_pgd)
154#endif
155
156#ifdef CONFIG_MICROCODE
157	/* Early load ucode on BSP. */
158	call load_ucode_bsp
159#endif
160
161/*
162 * Initialize page tables.  This creates a PDE and a set of page
163 * tables, which are located immediately beyond __brk_base.  The variable
164 * _brk_end is set up to point to the first "safe" location.
165 * Mappings are created both at virtual address 0 (identity mapping)
166 * and PAGE_OFFSET for up to _end.
167 */
168#ifdef CONFIG_X86_PAE
169
170	/*
171	 * In PAE mode initial_page_table is statically defined to contain
172	 * enough entries to cover the VMSPLIT option (that is the top 1, 2 or 3
173	 * entries). The identity mapping is handled by pointing two PGD entries
174	 * to the first kernel PMD.
175	 *
176	 * Note the upper half of each PMD or PTE are always zero at this stage.
177	 */
178
179#define KPMDS (((-__PAGE_OFFSET) >> 30) & 3) /* Number of kernel PMDs */
180
181	xorl %ebx,%ebx				/* %ebx is kept at zero */
182
183	movl $pa(__brk_base), %edi
184	movl $pa(initial_pg_pmd), %edx
185	movl $PTE_IDENT_ATTR, %eax
18610:
187	leal PDE_IDENT_ATTR(%edi),%ecx		/* Create PMD entry */
188	movl %ecx,(%edx)			/* Store PMD entry */
189						/* Upper half already zero */
190	addl $8,%edx
191	movl $512,%ecx
19211:
193	stosl
194	xchgl %eax,%ebx
195	stosl
196	xchgl %eax,%ebx
197	addl $0x1000,%eax
198	loop 11b
199
200	/*
201	 * End condition: we must map up to the end + MAPPING_BEYOND_END.
202	 */
203	movl $pa(_end) + MAPPING_BEYOND_END + PTE_IDENT_ATTR, %ebp
204	cmpl %ebp,%eax
205	jb 10b
2061:
207	addl $__PAGE_OFFSET, %edi
208	movl %edi, pa(_brk_end)
209	shrl $12, %eax
210	movl %eax, pa(max_pfn_mapped)
211
212	/* Do early initialization of the fixmap area */
213	movl $pa(initial_pg_fixmap)+PDE_IDENT_ATTR,%eax
214	movl %eax,pa(initial_pg_pmd+0x1000*KPMDS-8)
215#else	/* Not PAE */
216
217page_pde_offset = (__PAGE_OFFSET >> 20);
218
219	movl $pa(__brk_base), %edi
220	movl $pa(initial_page_table), %edx
221	movl $PTE_IDENT_ATTR, %eax
22210:
223	leal PDE_IDENT_ATTR(%edi),%ecx		/* Create PDE entry */
224	movl %ecx,(%edx)			/* Store identity PDE entry */
225	movl %ecx,page_pde_offset(%edx)		/* Store kernel PDE entry */
226	addl $4,%edx
227	movl $1024, %ecx
22811:
229	stosl
230	addl $0x1000,%eax
231	loop 11b
232	/*
233	 * End condition: we must map up to the end + MAPPING_BEYOND_END.
234	 */
235	movl $pa(_end) + MAPPING_BEYOND_END + PTE_IDENT_ATTR, %ebp
236	cmpl %ebp,%eax
237	jb 10b
238	addl $__PAGE_OFFSET, %edi
239	movl %edi, pa(_brk_end)
240	shrl $12, %eax
241	movl %eax, pa(max_pfn_mapped)
242
243	/* Do early initialization of the fixmap area */
244	movl $pa(initial_pg_fixmap)+PDE_IDENT_ATTR,%eax
245	movl %eax,pa(initial_page_table+0xffc)
246#endif
247
248#ifdef CONFIG_PARAVIRT
249	/* This is can only trip for a broken bootloader... */
250	cmpw $0x207, pa(boot_params + BP_version)
251	jb default_entry
252
253	/* Paravirt-compatible boot parameters.  Look to see what architecture
254		we're booting under. */
255	movl pa(boot_params + BP_hardware_subarch), %eax
256	cmpl $num_subarch_entries, %eax
257	jae bad_subarch
258
259	movl pa(subarch_entries)(,%eax,4), %eax
260	subl $__PAGE_OFFSET, %eax
261	jmp *%eax
262
263bad_subarch:
264WEAK(lguest_entry)
265WEAK(xen_entry)
266	/* Unknown implementation; there's really
267	   nothing we can do at this point. */
268	ud2a
269
270	__INITDATA
271
272subarch_entries:
273	.long default_entry		/* normal x86/PC */
274	.long lguest_entry		/* lguest hypervisor */
275	.long xen_entry			/* Xen hypervisor */
276	.long default_entry		/* Moorestown MID */
277num_subarch_entries = (. - subarch_entries) / 4
278.previous
279#else
280	jmp default_entry
281#endif /* CONFIG_PARAVIRT */
282
283#ifdef CONFIG_HOTPLUG_CPU
284/*
285 * Boot CPU0 entry point. It's called from play_dead(). Everything has been set
286 * up already except stack. We just set up stack here. Then call
287 * start_secondary().
288 */
289ENTRY(start_cpu0)
290	movl initial_stack, %ecx
291	movl %ecx, %esp
292	jmp  *(initial_code)
293ENDPROC(start_cpu0)
294#endif
295
296/*
297 * Non-boot CPU entry point; entered from trampoline.S
298 * We can't lgdt here, because lgdt itself uses a data segment, but
299 * we know the trampoline has already loaded the boot_gdt for us.
300 *
301 * If cpu hotplug is not supported then this code can go in init section
302 * which will be freed later
303 */
304ENTRY(startup_32_smp)
305	cld
306	movl $(__BOOT_DS),%eax
307	movl %eax,%ds
308	movl %eax,%es
309	movl %eax,%fs
310	movl %eax,%gs
311	movl pa(initial_stack),%ecx
312	movl %eax,%ss
313	leal -__PAGE_OFFSET(%ecx),%esp
314
315#ifdef CONFIG_MICROCODE
316	/* Early load ucode on AP. */
317	call load_ucode_ap
318#endif
319
320default_entry:
321#define CR0_STATE	(X86_CR0_PE | X86_CR0_MP | X86_CR0_ET | \
322			 X86_CR0_NE | X86_CR0_WP | X86_CR0_AM | \
323			 X86_CR0_PG)
324	movl $(CR0_STATE & ~X86_CR0_PG),%eax
325	movl %eax,%cr0
326
327/*
328 * We want to start out with EFLAGS unambiguously cleared. Some BIOSes leave
329 * bits like NT set. This would confuse the debugger if this code is traced. So
330 * initialize them properly now before switching to protected mode. That means
331 * DF in particular (even though we have cleared it earlier after copying the
332 * command line) because GCC expects it.
333 */
334	pushl $0
335	popfl
336
337/*
338 * New page tables may be in 4Mbyte page mode and may be using the global pages.
339 *
340 * NOTE! If we are on a 486 we may have no cr4 at all! Specifically, cr4 exists
341 * if and only if CPUID exists and has flags other than the FPU flag set.
342 */
343	movl $-1,pa(X86_CPUID)		# preset CPUID level
344	movl $X86_EFLAGS_ID,%ecx
345	pushl %ecx
346	popfl				# set EFLAGS=ID
347	pushfl
348	popl %eax			# get EFLAGS
349	testl $X86_EFLAGS_ID,%eax	# did EFLAGS.ID remained set?
350	jz enable_paging		# hw disallowed setting of ID bit
351					# which means no CPUID and no CR4
352
353	xorl %eax,%eax
354	cpuid
355	movl %eax,pa(X86_CPUID)		# save largest std CPUID function
356
357	movl $1,%eax
358	cpuid
359	andl $~1,%edx			# Ignore CPUID.FPU
360	jz enable_paging		# No flags or only CPUID.FPU = no CR4
361
362	movl pa(mmu_cr4_features),%eax
363	movl %eax,%cr4
364
365	testb $X86_CR4_PAE, %al		# check if PAE is enabled
366	jz enable_paging
367
368	/* Check if extended functions are implemented */
369	movl $0x80000000, %eax
370	cpuid
371	/* Value must be in the range 0x80000001 to 0x8000ffff */
372	subl $0x80000001, %eax
373	cmpl $(0x8000ffff-0x80000001), %eax
374	ja enable_paging
375
376	/* Clear bogus XD_DISABLE bits */
377	call verify_cpu
378
379	mov $0x80000001, %eax
380	cpuid
381	/* Execute Disable bit supported? */
382	btl $(X86_FEATURE_NX & 31), %edx
383	jnc enable_paging
384
385	/* Setup EFER (Extended Feature Enable Register) */
386	movl $MSR_EFER, %ecx
387	rdmsr
388
389	btsl $_EFER_NX, %eax
390	/* Make changes effective */
391	wrmsr
392
393enable_paging:
394
395/*
396 * Enable paging
397 */
398	movl $pa(initial_page_table), %eax
399	movl %eax,%cr3		/* set the page table pointer.. */
400	movl $CR0_STATE,%eax
401	movl %eax,%cr0		/* ..and set paging (PG) bit */
402	ljmp $__BOOT_CS,$1f	/* Clear prefetch and normalize %eip */
4031:
404	/* Shift the stack pointer to a virtual address */
405	addl $__PAGE_OFFSET, %esp
406
407/*
408 * start system 32-bit setup. We need to re-do some of the things done
409 * in 16-bit mode for the "real" operations.
410 */
411	movl setup_once_ref,%eax
412	andl %eax,%eax
413	jz 1f				# Did we do this already?
414	call *%eax
4151:
416
417/*
418 * Check if it is 486
419 */
420	movb $4,X86			# at least 486
421	cmpl $-1,X86_CPUID
422	je is486
423
424	/* get vendor info */
425	xorl %eax,%eax			# call CPUID with 0 -> return vendor ID
426	cpuid
427	movl %eax,X86_CPUID		# save CPUID level
428	movl %ebx,X86_VENDOR_ID		# lo 4 chars
429	movl %edx,X86_VENDOR_ID+4	# next 4 chars
430	movl %ecx,X86_VENDOR_ID+8	# last 4 chars
431
432	orl %eax,%eax			# do we have processor info as well?
433	je is486
434
435	movl $1,%eax		# Use the CPUID instruction to get CPU type
436	cpuid
437	movb %al,%cl		# save reg for future use
438	andb $0x0f,%ah		# mask processor family
439	movb %ah,X86
440	andb $0xf0,%al		# mask model
441	shrb $4,%al
442	movb %al,X86_MODEL
443	andb $0x0f,%cl		# mask mask revision
444	movb %cl,X86_MASK
445	movl %edx,X86_CAPABILITY
446
447is486:
448	movl $0x50022,%ecx	# set AM, WP, NE and MP
449	movl %cr0,%eax
450	andl $0x80000011,%eax	# Save PG,PE,ET
451	orl %ecx,%eax
452	movl %eax,%cr0
453
454	lgdt early_gdt_descr
455	lidt idt_descr
456	ljmp $(__KERNEL_CS),$1f
4571:	movl $(__KERNEL_DS),%eax	# reload all the segment registers
458	movl %eax,%ss			# after changing gdt.
459
460	movl $(__USER_DS),%eax		# DS/ES contains default USER segment
461	movl %eax,%ds
462	movl %eax,%es
463
464	movl $(__KERNEL_PERCPU), %eax
465	movl %eax,%fs			# set this cpu's percpu
466
467	movl $(__KERNEL_STACK_CANARY),%eax
468	movl %eax,%gs
469
470	xorl %eax,%eax			# Clear LDT
471	lldt %ax
472
473	pushl $0		# fake return address for unwinder
474	jmp *(initial_code)
475
476#include "verify_cpu.S"
477
478/*
479 *  setup_once
480 *
481 *  The setup work we only want to run on the BSP.
482 *
483 *  Warning: %esi is live across this function.
484 */
485__INIT
486setup_once:
487	/*
488	 * Set up a idt with 256 interrupt gates that push zero if there
489	 * is no error code and then jump to early_idt_handler_common.
490	 * It doesn't actually load the idt - that needs to be done on
491	 * each CPU. Interrupts are enabled elsewhere, when we can be
492	 * relatively sure everything is ok.
493	 */
494
495	movl $idt_table,%edi
496	movl $early_idt_handler_array,%eax
497	movl $NUM_EXCEPTION_VECTORS,%ecx
4981:
499	movl %eax,(%edi)
500	movl %eax,4(%edi)
501	/* interrupt gate, dpl=0, present */
502	movl $(0x8E000000 + __KERNEL_CS),2(%edi)
503	addl $EARLY_IDT_HANDLER_SIZE,%eax
504	addl $8,%edi
505	loop 1b
506
507	movl $256 - NUM_EXCEPTION_VECTORS,%ecx
508	movl $ignore_int,%edx
509	movl $(__KERNEL_CS << 16),%eax
510	movw %dx,%ax		/* selector = 0x0010 = cs */
511	movw $0x8E00,%dx	/* interrupt gate - dpl=0, present */
5122:
513	movl %eax,(%edi)
514	movl %edx,4(%edi)
515	addl $8,%edi
516	loop 2b
517
518#ifdef CONFIG_CC_STACKPROTECTOR
519	/*
520	 * Configure the stack canary. The linker can't handle this by
521	 * relocation.  Manually set base address in stack canary
522	 * segment descriptor.
523	 */
524	movl $gdt_page,%eax
525	movl $stack_canary,%ecx
526	movw %cx, 8 * GDT_ENTRY_STACK_CANARY + 2(%eax)
527	shrl $16, %ecx
528	movb %cl, 8 * GDT_ENTRY_STACK_CANARY + 4(%eax)
529	movb %ch, 8 * GDT_ENTRY_STACK_CANARY + 7(%eax)
530#endif
531
532	andl $0,setup_once_ref	/* Once is enough, thanks */
533	ret
534
535ENTRY(early_idt_handler_array)
536	# 36(%esp) %eflags
537	# 32(%esp) %cs
538	# 28(%esp) %eip
539	# 24(%rsp) error code
540	i = 0
541	.rept NUM_EXCEPTION_VECTORS
542	.ifeq (EXCEPTION_ERRCODE_MASK >> i) & 1
543	pushl $0		# Dummy error code, to make stack frame uniform
544	.endif
545	pushl $i		# 20(%esp) Vector number
546	jmp early_idt_handler_common
547	i = i + 1
548	.fill early_idt_handler_array + i*EARLY_IDT_HANDLER_SIZE - ., 1, 0xcc
549	.endr
550ENDPROC(early_idt_handler_array)
551
552early_idt_handler_common:
553	/*
554	 * The stack is the hardware frame, an error code or zero, and the
555	 * vector number.
556	 */
557	cld
558
559	incl %ss:early_recursion_flag
560
561	/* The vector number is in pt_regs->gs */
562
563	cld
564	pushl	%fs		/* pt_regs->fs */
565	movw	$0, 2(%esp)	/* clear high bits (some CPUs leave garbage) */
566	pushl	%es		/* pt_regs->es */
567	movw	$0, 2(%esp)	/* clear high bits (some CPUs leave garbage) */
568	pushl	%ds		/* pt_regs->ds */
569	movw	$0, 2(%esp)	/* clear high bits (some CPUs leave garbage) */
570	pushl	%eax		/* pt_regs->ax */
571	pushl	%ebp		/* pt_regs->bp */
572	pushl	%edi		/* pt_regs->di */
573	pushl	%esi		/* pt_regs->si */
574	pushl	%edx		/* pt_regs->dx */
575	pushl	%ecx		/* pt_regs->cx */
576	pushl	%ebx		/* pt_regs->bx */
577
578	/* Fix up DS and ES */
579	movl	$(__KERNEL_DS), %ecx
580	movl	%ecx, %ds
581	movl	%ecx, %es
582
583	/* Load the vector number into EDX */
584	movl	PT_GS(%esp), %edx
585
586	/* Load GS into pt_regs->gs and clear high bits */
587	movw	%gs, PT_GS(%esp)
588	movw	$0, PT_GS+2(%esp)
589
590	movl	%esp, %eax	/* args are pt_regs (EAX), trapnr (EDX) */
591	call	early_fixup_exception
592
593	popl	%ebx		/* pt_regs->bx */
594	popl	%ecx		/* pt_regs->cx */
595	popl	%edx		/* pt_regs->dx */
596	popl	%esi		/* pt_regs->si */
597	popl	%edi		/* pt_regs->di */
598	popl	%ebp		/* pt_regs->bp */
599	popl	%eax		/* pt_regs->ax */
600	popl	%ds		/* pt_regs->ds */
601	popl	%es		/* pt_regs->es */
602	popl	%fs		/* pt_regs->fs */
603	popl	%gs		/* pt_regs->gs */
604	decl	%ss:early_recursion_flag
605	addl	$4, %esp	/* pop pt_regs->orig_ax */
606	iret
607ENDPROC(early_idt_handler_common)
608
609/* This is the default interrupt "handler" :-) */
610	ALIGN
611ignore_int:
612	cld
613#ifdef CONFIG_PRINTK
614	pushl %eax
615	pushl %ecx
616	pushl %edx
617	pushl %es
618	pushl %ds
619	movl $(__KERNEL_DS),%eax
620	movl %eax,%ds
621	movl %eax,%es
622	cmpl $2,early_recursion_flag
623	je hlt_loop
624	incl early_recursion_flag
625	pushl 16(%esp)
626	pushl 24(%esp)
627	pushl 32(%esp)
628	pushl 40(%esp)
629	pushl $int_msg
630	call printk
631
632	call dump_stack
633
634	addl $(5*4),%esp
635	popl %ds
636	popl %es
637	popl %edx
638	popl %ecx
639	popl %eax
640#endif
641	iret
642
643hlt_loop:
644	hlt
645	jmp hlt_loop
646ENDPROC(ignore_int)
647__INITDATA
648	.align 4
649GLOBAL(early_recursion_flag)
650	.long 0
651
652__REFDATA
653	.align 4
654ENTRY(initial_code)
655	.long i386_start_kernel
656ENTRY(setup_once_ref)
657	.long setup_once
658
659/*
660 * BSS section
661 */
662__PAGE_ALIGNED_BSS
663	.align PAGE_SIZE
664#ifdef CONFIG_X86_PAE
665initial_pg_pmd:
666	.fill 1024*KPMDS,4,0
667#else
668ENTRY(initial_page_table)
669	.fill 1024,4,0
670#endif
671initial_pg_fixmap:
672	.fill 1024,4,0
673ENTRY(empty_zero_page)
674	.fill 4096,1,0
675ENTRY(swapper_pg_dir)
676	.fill 1024,4,0
677EXPORT_SYMBOL(empty_zero_page)
678
679/*
680 * This starts the data section.
681 */
682#ifdef CONFIG_X86_PAE
683__PAGE_ALIGNED_DATA
684	/* Page-aligned for the benefit of paravirt? */
685	.align PAGE_SIZE
686ENTRY(initial_page_table)
687	.long	pa(initial_pg_pmd+PGD_IDENT_ATTR),0	/* low identity map */
688# if KPMDS == 3
689	.long	pa(initial_pg_pmd+PGD_IDENT_ATTR),0
690	.long	pa(initial_pg_pmd+PGD_IDENT_ATTR+0x1000),0
691	.long	pa(initial_pg_pmd+PGD_IDENT_ATTR+0x2000),0
692# elif KPMDS == 2
693	.long	0,0
694	.long	pa(initial_pg_pmd+PGD_IDENT_ATTR),0
695	.long	pa(initial_pg_pmd+PGD_IDENT_ATTR+0x1000),0
696# elif KPMDS == 1
697	.long	0,0
698	.long	0,0
699	.long	pa(initial_pg_pmd+PGD_IDENT_ATTR),0
700# else
701#  error "Kernel PMDs should be 1, 2 or 3"
702# endif
703	.align PAGE_SIZE		/* needs to be page-sized too */
704#endif
705
706.data
707.balign 4
708ENTRY(initial_stack)
709	.long init_thread_union+THREAD_SIZE
710
711__INITRODATA
712int_msg:
713	.asciz "Unknown interrupt or fault at: %p %p %p\n"
714
715#include "../../x86/xen/xen-head.S"
716
717/*
718 * The IDT and GDT 'descriptors' are a strange 48-bit object
719 * only used by the lidt and lgdt instructions. They are not
720 * like usual segment descriptors - they consist of a 16-bit
721 * segment size, and 32-bit linear address value:
722 */
723
724	.data
725.globl boot_gdt_descr
726.globl idt_descr
727
728	ALIGN
729# early boot GDT descriptor (must use 1:1 address mapping)
730	.word 0				# 32 bit align gdt_desc.address
731boot_gdt_descr:
732	.word __BOOT_DS+7
733	.long boot_gdt - __PAGE_OFFSET
734
735	.word 0				# 32-bit align idt_desc.address
736idt_descr:
737	.word IDT_ENTRIES*8-1		# idt contains 256 entries
738	.long idt_table
739
740# boot GDT descriptor (later on used by CPU#0):
741	.word 0				# 32 bit align gdt_desc.address
742ENTRY(early_gdt_descr)
743	.word GDT_ENTRIES*8-1
744	.long gdt_page			/* Overwritten for secondary CPUs */
745
746/*
747 * The boot_gdt must mirror the equivalent in setup.S and is
748 * used only for booting.
749 */
750	.align L1_CACHE_BYTES
751ENTRY(boot_gdt)
752	.fill GDT_ENTRY_BOOT_CS,8,0
753	.quad 0x00cf9a000000ffff	/* kernel 4GB code at 0x00000000 */
754	.quad 0x00cf92000000ffff	/* kernel 4GB data at 0x00000000 */
755