xref: /openbmc/linux/arch/x86/kernel/head_32.S (revision 8b235f2f) 
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/cpufeature.h>
23#include <asm/percpu.h>
24#include <asm/nops.h>
25#include <asm/bootparam.h>
26
27/* Physical address */
28#define pa(X) ((X) - __PAGE_OFFSET)
29
30/*
31 * References to members of the new_cpu_data structure.
32 */
33
34#define X86		new_cpu_data+CPUINFO_x86
35#define X86_VENDOR	new_cpu_data+CPUINFO_x86_vendor
36#define X86_MODEL	new_cpu_data+CPUINFO_x86_model
37#define X86_MASK	new_cpu_data+CPUINFO_x86_mask
38#define X86_HARD_MATH	new_cpu_data+CPUINFO_hard_math
39#define X86_CPUID	new_cpu_data+CPUINFO_cpuid_level
40#define X86_CAPABILITY	new_cpu_data+CPUINFO_x86_capability
41#define X86_VENDOR_ID	new_cpu_data+CPUINFO_x86_vendor_id
42
43/*
44 * This is how much memory in addition to the memory covered up to
45 * and including _end we need mapped initially.
46 * We need:
47 *     (KERNEL_IMAGE_SIZE/4096) / 1024 pages (worst case, non PAE)
48 *     (KERNEL_IMAGE_SIZE/4096) / 512 + 4 pages (worst case for PAE)
49 *
50 * Modulo rounding, each megabyte assigned here requires a kilobyte of
51 * memory, which is currently unreclaimed.
52 *
53 * This should be a multiple of a page.
54 *
55 * KERNEL_IMAGE_SIZE should be greater than pa(_end)
56 * and small than max_low_pfn, otherwise will waste some page table entries
57 */
58
59#if PTRS_PER_PMD > 1
60#define PAGE_TABLE_SIZE(pages) (((pages) / PTRS_PER_PMD) + PTRS_PER_PGD)
61#else
62#define PAGE_TABLE_SIZE(pages) ((pages) / PTRS_PER_PGD)
63#endif
64
65/*
66 * Number of possible pages in the lowmem region.
67 *
68 * We shift 2 by 31 instead of 1 by 32 to the left in order to avoid a
69 * gas warning about overflowing shift count when gas has been compiled
70 * with only a host target support using a 32-bit type for internal
71 * representation.
72 */
73LOWMEM_PAGES = (((2<<31) - __PAGE_OFFSET) >> PAGE_SHIFT)
74
75/* Enough space to fit pagetables for the low memory linear map */
76MAPPING_BEYOND_END = PAGE_TABLE_SIZE(LOWMEM_PAGES) << PAGE_SHIFT
77
78/*
79 * Worst-case size of the kernel mapping we need to make:
80 * a relocatable kernel can live anywhere in lowmem, so we need to be able
81 * to map all of lowmem.
82 */
83KERNEL_PAGES = LOWMEM_PAGES
84
85INIT_MAP_SIZE = PAGE_TABLE_SIZE(KERNEL_PAGES) * PAGE_SIZE
86RESERVE_BRK(pagetables, INIT_MAP_SIZE)
87
88/*
89 * 32-bit kernel entrypoint; only used by the boot CPU.  On entry,
90 * %esi points to the real-mode code as a 32-bit pointer.
91 * CS and DS must be 4 GB flat segments, but we don't depend on
92 * any particular GDT layout, because we load our own as soon as we
93 * can.
94 */
95__HEAD
96ENTRY(startup_32)
97	movl pa(stack_start),%ecx
98
99	/* test KEEP_SEGMENTS flag to see if the bootloader is asking
100		us to not reload segments */
101	testb $KEEP_SEGMENTS, BP_loadflags(%esi)
102	jnz 2f
103
104/*
105 * Set segments to known values.
106 */
107	lgdt pa(boot_gdt_descr)
108	movl $(__BOOT_DS),%eax
109	movl %eax,%ds
110	movl %eax,%es
111	movl %eax,%fs
112	movl %eax,%gs
113	movl %eax,%ss
1142:
115	leal -__PAGE_OFFSET(%ecx),%esp
116
117/*
118 * Clear BSS first so that there are no surprises...
119 */
120	cld
121	xorl %eax,%eax
122	movl $pa(__bss_start),%edi
123	movl $pa(__bss_stop),%ecx
124	subl %edi,%ecx
125	shrl $2,%ecx
126	rep ; stosl
127/*
128 * Copy bootup parameters out of the way.
129 * Note: %esi still has the pointer to the real-mode data.
130 * With the kexec as boot loader, parameter segment might be loaded beyond
131 * kernel image and might not even be addressable by early boot page tables.
132 * (kexec on panic case). Hence copy out the parameters before initializing
133 * page tables.
134 */
135	movl $pa(boot_params),%edi
136	movl $(PARAM_SIZE/4),%ecx
137	cld
138	rep
139	movsl
140	movl pa(boot_params) + NEW_CL_POINTER,%esi
141	andl %esi,%esi
142	jz 1f			# No command line
143	movl $pa(boot_command_line),%edi
144	movl $(COMMAND_LINE_SIZE/4),%ecx
145	rep
146	movsl
1471:
148
149#ifdef CONFIG_OLPC
150	/* save OFW's pgdir table for later use when calling into OFW */
151	movl %cr3, %eax
152	movl %eax, pa(olpc_ofw_pgd)
153#endif
154
155#ifdef CONFIG_MICROCODE_EARLY
156	/* Early load ucode on BSP. */
157	call load_ucode_bsp
158#endif
159
160/*
161 * Initialize page tables.  This creates a PDE and a set of page
162 * tables, which are located immediately beyond __brk_base.  The variable
163 * _brk_end is set up to point to the first "safe" location.
164 * Mappings are created both at virtual address 0 (identity mapping)
165 * and PAGE_OFFSET for up to _end.
166 */
167#ifdef CONFIG_X86_PAE
168
169	/*
170	 * In PAE mode initial_page_table is statically defined to contain
171	 * enough entries to cover the VMSPLIT option (that is the top 1, 2 or 3
172	 * entries). The identity mapping is handled by pointing two PGD entries
173	 * to the first kernel PMD.
174	 *
175	 * Note the upper half of each PMD or PTE are always zero at this stage.
176	 */
177
178#define KPMDS (((-__PAGE_OFFSET) >> 30) & 3) /* Number of kernel PMDs */
179
180	xorl %ebx,%ebx				/* %ebx is kept at zero */
181
182	movl $pa(__brk_base), %edi
183	movl $pa(initial_pg_pmd), %edx
184	movl $PTE_IDENT_ATTR, %eax
18510:
186	leal PDE_IDENT_ATTR(%edi),%ecx		/* Create PMD entry */
187	movl %ecx,(%edx)			/* Store PMD entry */
188						/* Upper half already zero */
189	addl $8,%edx
190	movl $512,%ecx
19111:
192	stosl
193	xchgl %eax,%ebx
194	stosl
195	xchgl %eax,%ebx
196	addl $0x1000,%eax
197	loop 11b
198
199	/*
200	 * End condition: we must map up to the end + MAPPING_BEYOND_END.
201	 */
202	movl $pa(_end) + MAPPING_BEYOND_END + PTE_IDENT_ATTR, %ebp
203	cmpl %ebp,%eax
204	jb 10b
2051:
206	addl $__PAGE_OFFSET, %edi
207	movl %edi, pa(_brk_end)
208	shrl $12, %eax
209	movl %eax, pa(max_pfn_mapped)
210
211	/* Do early initialization of the fixmap area */
212	movl $pa(initial_pg_fixmap)+PDE_IDENT_ATTR,%eax
213	movl %eax,pa(initial_pg_pmd+0x1000*KPMDS-8)
214#else	/* Not PAE */
215
216page_pde_offset = (__PAGE_OFFSET >> 20);
217
218	movl $pa(__brk_base), %edi
219	movl $pa(initial_page_table), %edx
220	movl $PTE_IDENT_ATTR, %eax
22110:
222	leal PDE_IDENT_ATTR(%edi),%ecx		/* Create PDE entry */
223	movl %ecx,(%edx)			/* Store identity PDE entry */
224	movl %ecx,page_pde_offset(%edx)		/* Store kernel PDE entry */
225	addl $4,%edx
226	movl $1024, %ecx
22711:
228	stosl
229	addl $0x1000,%eax
230	loop 11b
231	/*
232	 * End condition: we must map up to the end + MAPPING_BEYOND_END.
233	 */
234	movl $pa(_end) + MAPPING_BEYOND_END + PTE_IDENT_ATTR, %ebp
235	cmpl %ebp,%eax
236	jb 10b
237	addl $__PAGE_OFFSET, %edi
238	movl %edi, pa(_brk_end)
239	shrl $12, %eax
240	movl %eax, pa(max_pfn_mapped)
241
242	/* Do early initialization of the fixmap area */
243	movl $pa(initial_pg_fixmap)+PDE_IDENT_ATTR,%eax
244	movl %eax,pa(initial_page_table+0xffc)
245#endif
246
247#ifdef CONFIG_PARAVIRT
248	/* This is can only trip for a broken bootloader... */
249	cmpw $0x207, pa(boot_params + BP_version)
250	jb default_entry
251
252	/* Paravirt-compatible boot parameters.  Look to see what architecture
253		we're booting under. */
254	movl pa(boot_params + BP_hardware_subarch), %eax
255	cmpl $num_subarch_entries, %eax
256	jae bad_subarch
257
258	movl pa(subarch_entries)(,%eax,4), %eax
259	subl $__PAGE_OFFSET, %eax
260	jmp *%eax
261
262bad_subarch:
263WEAK(lguest_entry)
264WEAK(xen_entry)
265	/* Unknown implementation; there's really
266	   nothing we can do at this point. */
267	ud2a
268
269	__INITDATA
270
271subarch_entries:
272	.long default_entry		/* normal x86/PC */
273	.long lguest_entry		/* lguest hypervisor */
274	.long xen_entry			/* Xen hypervisor */
275	.long default_entry		/* Moorestown MID */
276num_subarch_entries = (. - subarch_entries) / 4
277.previous
278#else
279	jmp default_entry
280#endif /* CONFIG_PARAVIRT */
281
282#ifdef CONFIG_HOTPLUG_CPU
283/*
284 * Boot CPU0 entry point. It's called from play_dead(). Everything has been set
285 * up already except stack. We just set up stack here. Then call
286 * start_secondary().
287 */
288ENTRY(start_cpu0)
289	movl stack_start, %ecx
290	movl %ecx, %esp
291	jmp  *(initial_code)
292ENDPROC(start_cpu0)
293#endif
294
295/*
296 * Non-boot CPU entry point; entered from trampoline.S
297 * We can't lgdt here, because lgdt itself uses a data segment, but
298 * we know the trampoline has already loaded the boot_gdt for us.
299 *
300 * If cpu hotplug is not supported then this code can go in init section
301 * which will be freed later
302 */
303ENTRY(startup_32_smp)
304	cld
305	movl $(__BOOT_DS),%eax
306	movl %eax,%ds
307	movl %eax,%es
308	movl %eax,%fs
309	movl %eax,%gs
310	movl pa(stack_start),%ecx
311	movl %eax,%ss
312	leal -__PAGE_OFFSET(%ecx),%esp
313
314#ifdef CONFIG_MICROCODE_EARLY
315	/* Early load ucode on AP. */
316	call load_ucode_ap
317#endif
318
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	cmpl $2,(%esp)		# X86_TRAP_NMI
560	je .Lis_nmi		# Ignore NMI
561
562	cmpl $2,%ss:early_recursion_flag
563	je hlt_loop
564	incl %ss:early_recursion_flag
565
566	push %eax		# 16(%esp)
567	push %ecx		# 12(%esp)
568	push %edx		#  8(%esp)
569	push %ds		#  4(%esp)
570	push %es		#  0(%esp)
571	movl $(__KERNEL_DS),%eax
572	movl %eax,%ds
573	movl %eax,%es
574
575	cmpl $(__KERNEL_CS),32(%esp)
576	jne 10f
577
578	leal 28(%esp),%eax	# Pointer to %eip
579	call early_fixup_exception
580	andl %eax,%eax
581	jnz ex_entry		/* found an exception entry */
582
58310:
584#ifdef CONFIG_PRINTK
585	xorl %eax,%eax
586	movw %ax,2(%esp)	/* clean up the segment values on some cpus */
587	movw %ax,6(%esp)
588	movw %ax,34(%esp)
589	leal  40(%esp),%eax
590	pushl %eax		/* %esp before the exception */
591	pushl %ebx
592	pushl %ebp
593	pushl %esi
594	pushl %edi
595	movl %cr2,%eax
596	pushl %eax
597	pushl (20+6*4)(%esp)	/* trapno */
598	pushl $fault_msg
599	call printk
600#endif
601	call dump_stack
602hlt_loop:
603	hlt
604	jmp hlt_loop
605
606ex_entry:
607	pop %es
608	pop %ds
609	pop %edx
610	pop %ecx
611	pop %eax
612	decl %ss:early_recursion_flag
613.Lis_nmi:
614	addl $8,%esp		/* drop vector number and error code */
615	iret
616ENDPROC(early_idt_handler_common)
617
618/* This is the default interrupt "handler" :-) */
619	ALIGN
620ignore_int:
621	cld
622#ifdef CONFIG_PRINTK
623	pushl %eax
624	pushl %ecx
625	pushl %edx
626	pushl %es
627	pushl %ds
628	movl $(__KERNEL_DS),%eax
629	movl %eax,%ds
630	movl %eax,%es
631	cmpl $2,early_recursion_flag
632	je hlt_loop
633	incl early_recursion_flag
634	pushl 16(%esp)
635	pushl 24(%esp)
636	pushl 32(%esp)
637	pushl 40(%esp)
638	pushl $int_msg
639	call printk
640
641	call dump_stack
642
643	addl $(5*4),%esp
644	popl %ds
645	popl %es
646	popl %edx
647	popl %ecx
648	popl %eax
649#endif
650	iret
651ENDPROC(ignore_int)
652__INITDATA
653	.align 4
654early_recursion_flag:
655	.long 0
656
657__REFDATA
658	.align 4
659ENTRY(initial_code)
660	.long i386_start_kernel
661ENTRY(setup_once_ref)
662	.long setup_once
663
664/*
665 * BSS section
666 */
667__PAGE_ALIGNED_BSS
668	.align PAGE_SIZE
669#ifdef CONFIG_X86_PAE
670initial_pg_pmd:
671	.fill 1024*KPMDS,4,0
672#else
673ENTRY(initial_page_table)
674	.fill 1024,4,0
675#endif
676initial_pg_fixmap:
677	.fill 1024,4,0
678ENTRY(empty_zero_page)
679	.fill 4096,1,0
680ENTRY(swapper_pg_dir)
681	.fill 1024,4,0
682
683/*
684 * This starts the data section.
685 */
686#ifdef CONFIG_X86_PAE
687__PAGE_ALIGNED_DATA
688	/* Page-aligned for the benefit of paravirt? */
689	.align PAGE_SIZE
690ENTRY(initial_page_table)
691	.long	pa(initial_pg_pmd+PGD_IDENT_ATTR),0	/* low identity map */
692# if KPMDS == 3
693	.long	pa(initial_pg_pmd+PGD_IDENT_ATTR),0
694	.long	pa(initial_pg_pmd+PGD_IDENT_ATTR+0x1000),0
695	.long	pa(initial_pg_pmd+PGD_IDENT_ATTR+0x2000),0
696# elif KPMDS == 2
697	.long	0,0
698	.long	pa(initial_pg_pmd+PGD_IDENT_ATTR),0
699	.long	pa(initial_pg_pmd+PGD_IDENT_ATTR+0x1000),0
700# elif KPMDS == 1
701	.long	0,0
702	.long	0,0
703	.long	pa(initial_pg_pmd+PGD_IDENT_ATTR),0
704# else
705#  error "Kernel PMDs should be 1, 2 or 3"
706# endif
707	.align PAGE_SIZE		/* needs to be page-sized too */
708#endif
709
710.data
711.balign 4
712ENTRY(stack_start)
713	.long init_thread_union+THREAD_SIZE
714
715__INITRODATA
716int_msg:
717	.asciz "Unknown interrupt or fault at: %p %p %p\n"
718
719fault_msg:
720/* fault info: */
721	.ascii "BUG: Int %d: CR2 %p\n"
722/* regs pushed in early_idt_handler: */
723	.ascii "     EDI %p  ESI %p  EBP %p  EBX %p\n"
724	.ascii "     ESP %p   ES %p   DS %p\n"
725	.ascii "     EDX %p  ECX %p  EAX %p\n"
726/* fault frame: */
727	.ascii "     vec %p  err %p  EIP %p   CS %p  flg %p\n"
728	.ascii "Stack: %p %p %p %p %p %p %p %p\n"
729	.ascii "       %p %p %p %p %p %p %p %p\n"
730	.asciz "       %p %p %p %p %p %p %p %p\n"
731
732#include "../../x86/xen/xen-head.S"
733
734/*
735 * The IDT and GDT 'descriptors' are a strange 48-bit object
736 * only used by the lidt and lgdt instructions. They are not
737 * like usual segment descriptors - they consist of a 16-bit
738 * segment size, and 32-bit linear address value:
739 */
740
741	.data
742.globl boot_gdt_descr
743.globl idt_descr
744
745	ALIGN
746# early boot GDT descriptor (must use 1:1 address mapping)
747	.word 0				# 32 bit align gdt_desc.address
748boot_gdt_descr:
749	.word __BOOT_DS+7
750	.long boot_gdt - __PAGE_OFFSET
751
752	.word 0				# 32-bit align idt_desc.address
753idt_descr:
754	.word IDT_ENTRIES*8-1		# idt contains 256 entries
755	.long idt_table
756
757# boot GDT descriptor (later on used by CPU#0):
758	.word 0				# 32 bit align gdt_desc.address
759ENTRY(early_gdt_descr)
760	.word GDT_ENTRIES*8-1
761	.long gdt_page			/* Overwritten for secondary CPUs */
762
763/*
764 * The boot_gdt must mirror the equivalent in setup.S and is
765 * used only for booting.
766 */
767	.align L1_CACHE_BYTES
768ENTRY(boot_gdt)
769	.fill GDT_ENTRY_BOOT_CS,8,0
770	.quad 0x00cf9a000000ffff	/* kernel 4GB code at 0x00000000 */
771	.quad 0x00cf92000000ffff	/* kernel 4GB data at 0x00000000 */
772