xref: /openbmc/linux/arch/x86/kernel/head_32.S (revision ca79522c) 
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
26/* Physical address */
27#define pa(X) ((X) - __PAGE_OFFSET)
28
29/*
30 * References to members of the new_cpu_data structure.
31 */
32
33#define X86		new_cpu_data+CPUINFO_x86
34#define X86_VENDOR	new_cpu_data+CPUINFO_x86_vendor
35#define X86_MODEL	new_cpu_data+CPUINFO_x86_model
36#define X86_MASK	new_cpu_data+CPUINFO_x86_mask
37#define X86_HARD_MATH	new_cpu_data+CPUINFO_hard_math
38#define X86_CPUID	new_cpu_data+CPUINFO_cpuid_level
39#define X86_CAPABILITY	new_cpu_data+CPUINFO_x86_capability
40#define X86_VENDOR_ID	new_cpu_data+CPUINFO_x86_vendor_id
41
42/*
43 * This is how much memory in addition to the memory covered up to
44 * and including _end we need mapped initially.
45 * We need:
46 *     (KERNEL_IMAGE_SIZE/4096) / 1024 pages (worst case, non PAE)
47 *     (KERNEL_IMAGE_SIZE/4096) / 512 + 4 pages (worst case for PAE)
48 *
49 * Modulo rounding, each megabyte assigned here requires a kilobyte of
50 * memory, which is currently unreclaimed.
51 *
52 * This should be a multiple of a page.
53 *
54 * KERNEL_IMAGE_SIZE should be greater than pa(_end)
55 * and small than max_low_pfn, otherwise will waste some page table entries
56 */
57
58#if PTRS_PER_PMD > 1
59#define PAGE_TABLE_SIZE(pages) (((pages) / PTRS_PER_PMD) + PTRS_PER_PGD)
60#else
61#define PAGE_TABLE_SIZE(pages) ((pages) / PTRS_PER_PGD)
62#endif
63
64/* Number of possible pages in the lowmem region */
65LOWMEM_PAGES = (((1<<32) - __PAGE_OFFSET) >> PAGE_SHIFT)
66
67/* Enough space to fit pagetables for the low memory linear map */
68MAPPING_BEYOND_END = PAGE_TABLE_SIZE(LOWMEM_PAGES) << PAGE_SHIFT
69
70/*
71 * Worst-case size of the kernel mapping we need to make:
72 * a relocatable kernel can live anywhere in lowmem, so we need to be able
73 * to map all of lowmem.
74 */
75KERNEL_PAGES = LOWMEM_PAGES
76
77INIT_MAP_SIZE = PAGE_TABLE_SIZE(KERNEL_PAGES) * PAGE_SIZE
78RESERVE_BRK(pagetables, INIT_MAP_SIZE)
79
80/*
81 * 32-bit kernel entrypoint; only used by the boot CPU.  On entry,
82 * %esi points to the real-mode code as a 32-bit pointer.
83 * CS and DS must be 4 GB flat segments, but we don't depend on
84 * any particular GDT layout, because we load our own as soon as we
85 * can.
86 */
87__HEAD
88ENTRY(startup_32)
89	movl pa(stack_start),%ecx
90
91	/* test KEEP_SEGMENTS flag to see if the bootloader is asking
92		us to not reload segments */
93	testb $(1<<6), BP_loadflags(%esi)
94	jnz 2f
95
96/*
97 * Set segments to known values.
98 */
99	lgdt pa(boot_gdt_descr)
100	movl $(__BOOT_DS),%eax
101	movl %eax,%ds
102	movl %eax,%es
103	movl %eax,%fs
104	movl %eax,%gs
105	movl %eax,%ss
1062:
107	leal -__PAGE_OFFSET(%ecx),%esp
108
109/*
110 * Clear BSS first so that there are no surprises...
111 */
112	cld
113	xorl %eax,%eax
114	movl $pa(__bss_start),%edi
115	movl $pa(__bss_stop),%ecx
116	subl %edi,%ecx
117	shrl $2,%ecx
118	rep ; stosl
119/*
120 * Copy bootup parameters out of the way.
121 * Note: %esi still has the pointer to the real-mode data.
122 * With the kexec as boot loader, parameter segment might be loaded beyond
123 * kernel image and might not even be addressable by early boot page tables.
124 * (kexec on panic case). Hence copy out the parameters before initializing
125 * page tables.
126 */
127	movl $pa(boot_params),%edi
128	movl $(PARAM_SIZE/4),%ecx
129	cld
130	rep
131	movsl
132	movl pa(boot_params) + NEW_CL_POINTER,%esi
133	andl %esi,%esi
134	jz 1f			# No command line
135	movl $pa(boot_command_line),%edi
136	movl $(COMMAND_LINE_SIZE/4),%ecx
137	rep
138	movsl
1391:
140
141#ifdef CONFIG_OLPC
142	/* save OFW's pgdir table for later use when calling into OFW */
143	movl %cr3, %eax
144	movl %eax, pa(olpc_ofw_pgd)
145#endif
146
147#ifdef CONFIG_MICROCODE_EARLY
148	/* Early load ucode on BSP. */
149	call load_ucode_bsp
150#endif
151
152/*
153 * Initialize page tables.  This creates a PDE and a set of page
154 * tables, which are located immediately beyond __brk_base.  The variable
155 * _brk_end is set up to point to the first "safe" location.
156 * Mappings are created both at virtual address 0 (identity mapping)
157 * and PAGE_OFFSET for up to _end.
158 */
159#ifdef CONFIG_X86_PAE
160
161	/*
162	 * In PAE mode initial_page_table is statically defined to contain
163	 * enough entries to cover the VMSPLIT option (that is the top 1, 2 or 3
164	 * entries). The identity mapping is handled by pointing two PGD entries
165	 * to the first kernel PMD.
166	 *
167	 * Note the upper half of each PMD or PTE are always zero at this stage.
168	 */
169
170#define KPMDS (((-__PAGE_OFFSET) >> 30) & 3) /* Number of kernel PMDs */
171
172	xorl %ebx,%ebx				/* %ebx is kept at zero */
173
174	movl $pa(__brk_base), %edi
175	movl $pa(initial_pg_pmd), %edx
176	movl $PTE_IDENT_ATTR, %eax
17710:
178	leal PDE_IDENT_ATTR(%edi),%ecx		/* Create PMD entry */
179	movl %ecx,(%edx)			/* Store PMD entry */
180						/* Upper half already zero */
181	addl $8,%edx
182	movl $512,%ecx
18311:
184	stosl
185	xchgl %eax,%ebx
186	stosl
187	xchgl %eax,%ebx
188	addl $0x1000,%eax
189	loop 11b
190
191	/*
192	 * End condition: we must map up to the end + MAPPING_BEYOND_END.
193	 */
194	movl $pa(_end) + MAPPING_BEYOND_END + PTE_IDENT_ATTR, %ebp
195	cmpl %ebp,%eax
196	jb 10b
1971:
198	addl $__PAGE_OFFSET, %edi
199	movl %edi, pa(_brk_end)
200	shrl $12, %eax
201	movl %eax, pa(max_pfn_mapped)
202
203	/* Do early initialization of the fixmap area */
204	movl $pa(initial_pg_fixmap)+PDE_IDENT_ATTR,%eax
205	movl %eax,pa(initial_pg_pmd+0x1000*KPMDS-8)
206#else	/* Not PAE */
207
208page_pde_offset = (__PAGE_OFFSET >> 20);
209
210	movl $pa(__brk_base), %edi
211	movl $pa(initial_page_table), %edx
212	movl $PTE_IDENT_ATTR, %eax
21310:
214	leal PDE_IDENT_ATTR(%edi),%ecx		/* Create PDE entry */
215	movl %ecx,(%edx)			/* Store identity PDE entry */
216	movl %ecx,page_pde_offset(%edx)		/* Store kernel PDE entry */
217	addl $4,%edx
218	movl $1024, %ecx
21911:
220	stosl
221	addl $0x1000,%eax
222	loop 11b
223	/*
224	 * End condition: we must map up to the end + MAPPING_BEYOND_END.
225	 */
226	movl $pa(_end) + MAPPING_BEYOND_END + PTE_IDENT_ATTR, %ebp
227	cmpl %ebp,%eax
228	jb 10b
229	addl $__PAGE_OFFSET, %edi
230	movl %edi, pa(_brk_end)
231	shrl $12, %eax
232	movl %eax, pa(max_pfn_mapped)
233
234	/* Do early initialization of the fixmap area */
235	movl $pa(initial_pg_fixmap)+PDE_IDENT_ATTR,%eax
236	movl %eax,pa(initial_page_table+0xffc)
237#endif
238
239#ifdef CONFIG_PARAVIRT
240	/* This is can only trip for a broken bootloader... */
241	cmpw $0x207, pa(boot_params + BP_version)
242	jb default_entry
243
244	/* Paravirt-compatible boot parameters.  Look to see what architecture
245		we're booting under. */
246	movl pa(boot_params + BP_hardware_subarch), %eax
247	cmpl $num_subarch_entries, %eax
248	jae bad_subarch
249
250	movl pa(subarch_entries)(,%eax,4), %eax
251	subl $__PAGE_OFFSET, %eax
252	jmp *%eax
253
254bad_subarch:
255WEAK(lguest_entry)
256WEAK(xen_entry)
257	/* Unknown implementation; there's really
258	   nothing we can do at this point. */
259	ud2a
260
261	__INITDATA
262
263subarch_entries:
264	.long default_entry		/* normal x86/PC */
265	.long lguest_entry		/* lguest hypervisor */
266	.long xen_entry			/* Xen hypervisor */
267	.long default_entry		/* Moorestown MID */
268num_subarch_entries = (. - subarch_entries) / 4
269.previous
270#else
271	jmp default_entry
272#endif /* CONFIG_PARAVIRT */
273
274#ifdef CONFIG_HOTPLUG_CPU
275/*
276 * Boot CPU0 entry point. It's called from play_dead(). Everything has been set
277 * up already except stack. We just set up stack here. Then call
278 * start_secondary().
279 */
280ENTRY(start_cpu0)
281	movl stack_start, %ecx
282	movl %ecx, %esp
283	jmp  *(initial_code)
284ENDPROC(start_cpu0)
285#endif
286
287/*
288 * Non-boot CPU entry point; entered from trampoline.S
289 * We can't lgdt here, because lgdt itself uses a data segment, but
290 * we know the trampoline has already loaded the boot_gdt for us.
291 *
292 * If cpu hotplug is not supported then this code can go in init section
293 * which will be freed later
294 */
295__CPUINIT
296ENTRY(startup_32_smp)
297	cld
298	movl $(__BOOT_DS),%eax
299	movl %eax,%ds
300	movl %eax,%es
301	movl %eax,%fs
302	movl %eax,%gs
303	movl pa(stack_start),%ecx
304	movl %eax,%ss
305	leal -__PAGE_OFFSET(%ecx),%esp
306
307#ifdef CONFIG_MICROCODE_EARLY
308	/* Early load ucode on AP. */
309	call load_ucode_ap
310#endif
311
312
313default_entry:
314#define CR0_STATE	(X86_CR0_PE | X86_CR0_MP | X86_CR0_ET | \
315			 X86_CR0_NE | X86_CR0_WP | X86_CR0_AM | \
316			 X86_CR0_PG)
317	movl $(CR0_STATE & ~X86_CR0_PG),%eax
318	movl %eax,%cr0
319
320/*
321 * We want to start out with EFLAGS unambiguously cleared. Some BIOSes leave
322 * bits like NT set. This would confuse the debugger if this code is traced. So
323 * initialize them properly now before switching to protected mode. That means
324 * DF in particular (even though we have cleared it earlier after copying the
325 * command line) because GCC expects it.
326 */
327	pushl $0
328	popfl
329
330/*
331 * New page tables may be in 4Mbyte page mode and may be using the global pages.
332 *
333 * NOTE! If we are on a 486 we may have no cr4 at all! Specifically, cr4 exists
334 * if and only if CPUID exists and has flags other than the FPU flag set.
335 */
336	movl $-1,pa(X86_CPUID)		# preset CPUID level
337	movl $X86_EFLAGS_ID,%ecx
338	pushl %ecx
339	popfl				# set EFLAGS=ID
340	pushfl
341	popl %eax			# get EFLAGS
342	testl $X86_EFLAGS_ID,%eax	# did EFLAGS.ID remained set?
343	jz enable_paging		# hw disallowed setting of ID bit
344					# which means no CPUID and no CR4
345
346	xorl %eax,%eax
347	cpuid
348	movl %eax,pa(X86_CPUID)		# save largest std CPUID function
349
350	movl $1,%eax
351	cpuid
352	andl $~1,%edx			# Ignore CPUID.FPU
353	jz enable_paging		# No flags or only CPUID.FPU = no CR4
354
355	movl pa(mmu_cr4_features),%eax
356	movl %eax,%cr4
357
358	testb $X86_CR4_PAE, %al		# check if PAE is enabled
359	jz enable_paging
360
361	/* Check if extended functions are implemented */
362	movl $0x80000000, %eax
363	cpuid
364	/* Value must be in the range 0x80000001 to 0x8000ffff */
365	subl $0x80000001, %eax
366	cmpl $(0x8000ffff-0x80000001), %eax
367	ja enable_paging
368
369	/* Clear bogus XD_DISABLE bits */
370	call verify_cpu
371
372	mov $0x80000001, %eax
373	cpuid
374	/* Execute Disable bit supported? */
375	btl $(X86_FEATURE_NX & 31), %edx
376	jnc enable_paging
377
378	/* Setup EFER (Extended Feature Enable Register) */
379	movl $MSR_EFER, %ecx
380	rdmsr
381
382	btsl $_EFER_NX, %eax
383	/* Make changes effective */
384	wrmsr
385
386enable_paging:
387
388/*
389 * Enable paging
390 */
391	movl $pa(initial_page_table), %eax
392	movl %eax,%cr3		/* set the page table pointer.. */
393	movl $CR0_STATE,%eax
394	movl %eax,%cr0		/* ..and set paging (PG) bit */
395	ljmp $__BOOT_CS,$1f	/* Clear prefetch and normalize %eip */
3961:
397	/* Shift the stack pointer to a virtual address */
398	addl $__PAGE_OFFSET, %esp
399
400/*
401 * start system 32-bit setup. We need to re-do some of the things done
402 * in 16-bit mode for the "real" operations.
403 */
404	movl setup_once_ref,%eax
405	andl %eax,%eax
406	jz 1f				# Did we do this already?
407	call *%eax
4081:
409
410/*
411 * Check if it is 486
412 */
413	cmpl $-1,X86_CPUID
414	je is486
415
416	/* get vendor info */
417	xorl %eax,%eax			# call CPUID with 0 -> return vendor ID
418	cpuid
419	movl %eax,X86_CPUID		# save CPUID level
420	movl %ebx,X86_VENDOR_ID		# lo 4 chars
421	movl %edx,X86_VENDOR_ID+4	# next 4 chars
422	movl %ecx,X86_VENDOR_ID+8	# last 4 chars
423
424	orl %eax,%eax			# do we have processor info as well?
425	je is486
426
427	movl $1,%eax		# Use the CPUID instruction to get CPU type
428	cpuid
429	movb %al,%cl		# save reg for future use
430	andb $0x0f,%ah		# mask processor family
431	movb %ah,X86
432	andb $0xf0,%al		# mask model
433	shrb $4,%al
434	movb %al,X86_MODEL
435	andb $0x0f,%cl		# mask mask revision
436	movb %cl,X86_MASK
437	movl %edx,X86_CAPABILITY
438
439is486:
440	movb $4,X86
441	movl $0x50022,%ecx	# set AM, WP, NE and MP
442	movl %cr0,%eax
443	andl $0x80000011,%eax	# Save PG,PE,ET
444	orl %ecx,%eax
445	movl %eax,%cr0
446
447	call check_x87
448	lgdt early_gdt_descr
449	lidt idt_descr
450	ljmp $(__KERNEL_CS),$1f
4511:	movl $(__KERNEL_DS),%eax	# reload all the segment registers
452	movl %eax,%ss			# after changing gdt.
453
454	movl $(__USER_DS),%eax		# DS/ES contains default USER segment
455	movl %eax,%ds
456	movl %eax,%es
457
458	movl $(__KERNEL_PERCPU), %eax
459	movl %eax,%fs			# set this cpu's percpu
460
461	movl $(__KERNEL_STACK_CANARY),%eax
462	movl %eax,%gs
463
464	xorl %eax,%eax			# Clear LDT
465	lldt %ax
466
467	pushl $0		# fake return address for unwinder
468	jmp *(initial_code)
469
470/*
471 * We depend on ET to be correct. This checks for 287/387.
472 */
473check_x87:
474	movb $0,X86_HARD_MATH
475	clts
476	fninit
477	fstsw %ax
478	cmpb $0,%al
479	je 1f
480	movl %cr0,%eax		/* no coprocessor: have to set bits */
481	xorl $4,%eax		/* set EM */
482	movl %eax,%cr0
483	ret
484	ALIGN
4851:	movb $1,X86_HARD_MATH
486	.byte 0xDB,0xE4		/* fsetpm for 287, ignored by 387 */
487	ret
488
489
490#include "verify_cpu.S"
491
492/*
493 *  setup_once
494 *
495 *  The setup work we only want to run on the BSP.
496 *
497 *  Warning: %esi is live across this function.
498 */
499__INIT
500setup_once:
501	/*
502	 * Set up a idt with 256 entries pointing to ignore_int,
503	 * interrupt gates. It doesn't actually load idt - that needs
504	 * to be done on each CPU. Interrupts are enabled elsewhere,
505	 * when we can be relatively sure everything is ok.
506	 */
507
508	movl $idt_table,%edi
509	movl $early_idt_handlers,%eax
510	movl $NUM_EXCEPTION_VECTORS,%ecx
5111:
512	movl %eax,(%edi)
513	movl %eax,4(%edi)
514	/* interrupt gate, dpl=0, present */
515	movl $(0x8E000000 + __KERNEL_CS),2(%edi)
516	addl $9,%eax
517	addl $8,%edi
518	loop 1b
519
520	movl $256 - NUM_EXCEPTION_VECTORS,%ecx
521	movl $ignore_int,%edx
522	movl $(__KERNEL_CS << 16),%eax
523	movw %dx,%ax		/* selector = 0x0010 = cs */
524	movw $0x8E00,%dx	/* interrupt gate - dpl=0, present */
5252:
526	movl %eax,(%edi)
527	movl %edx,4(%edi)
528	addl $8,%edi
529	loop 2b
530
531#ifdef CONFIG_CC_STACKPROTECTOR
532	/*
533	 * Configure the stack canary. The linker can't handle this by
534	 * relocation.  Manually set base address in stack canary
535	 * segment descriptor.
536	 */
537	movl $gdt_page,%eax
538	movl $stack_canary,%ecx
539	movw %cx, 8 * GDT_ENTRY_STACK_CANARY + 2(%eax)
540	shrl $16, %ecx
541	movb %cl, 8 * GDT_ENTRY_STACK_CANARY + 4(%eax)
542	movb %ch, 8 * GDT_ENTRY_STACK_CANARY + 7(%eax)
543#endif
544
545	andl $0,setup_once_ref	/* Once is enough, thanks */
546	ret
547
548ENTRY(early_idt_handlers)
549	# 36(%esp) %eflags
550	# 32(%esp) %cs
551	# 28(%esp) %eip
552	# 24(%rsp) error code
553	i = 0
554	.rept NUM_EXCEPTION_VECTORS
555	.if (EXCEPTION_ERRCODE_MASK >> i) & 1
556	ASM_NOP2
557	.else
558	pushl $0		# Dummy error code, to make stack frame uniform
559	.endif
560	pushl $i		# 20(%esp) Vector number
561	jmp early_idt_handler
562	i = i + 1
563	.endr
564ENDPROC(early_idt_handlers)
565
566	/* This is global to keep gas from relaxing the jumps */
567ENTRY(early_idt_handler)
568	cld
569	cmpl $2,%ss:early_recursion_flag
570	je hlt_loop
571	incl %ss:early_recursion_flag
572
573	push %eax		# 16(%esp)
574	push %ecx		# 12(%esp)
575	push %edx		#  8(%esp)
576	push %ds		#  4(%esp)
577	push %es		#  0(%esp)
578	movl $(__KERNEL_DS),%eax
579	movl %eax,%ds
580	movl %eax,%es
581
582	cmpl $(__KERNEL_CS),32(%esp)
583	jne 10f
584
585	leal 28(%esp),%eax	# Pointer to %eip
586	call early_fixup_exception
587	andl %eax,%eax
588	jnz ex_entry		/* found an exception entry */
589
59010:
591#ifdef CONFIG_PRINTK
592	xorl %eax,%eax
593	movw %ax,2(%esp)	/* clean up the segment values on some cpus */
594	movw %ax,6(%esp)
595	movw %ax,34(%esp)
596	leal  40(%esp),%eax
597	pushl %eax		/* %esp before the exception */
598	pushl %ebx
599	pushl %ebp
600	pushl %esi
601	pushl %edi
602	movl %cr2,%eax
603	pushl %eax
604	pushl (20+6*4)(%esp)	/* trapno */
605	pushl $fault_msg
606	call printk
607#endif
608	call dump_stack
609hlt_loop:
610	hlt
611	jmp hlt_loop
612
613ex_entry:
614	pop %es
615	pop %ds
616	pop %edx
617	pop %ecx
618	pop %eax
619	addl $8,%esp		/* drop vector number and error code */
620	decl %ss:early_recursion_flag
621	iret
622ENDPROC(early_idt_handler)
623
624/* This is the default interrupt "handler" :-) */
625	ALIGN
626ignore_int:
627	cld
628#ifdef CONFIG_PRINTK
629	pushl %eax
630	pushl %ecx
631	pushl %edx
632	pushl %es
633	pushl %ds
634	movl $(__KERNEL_DS),%eax
635	movl %eax,%ds
636	movl %eax,%es
637	cmpl $2,early_recursion_flag
638	je hlt_loop
639	incl early_recursion_flag
640	pushl 16(%esp)
641	pushl 24(%esp)
642	pushl 32(%esp)
643	pushl 40(%esp)
644	pushl $int_msg
645	call printk
646
647	call dump_stack
648
649	addl $(5*4),%esp
650	popl %ds
651	popl %es
652	popl %edx
653	popl %ecx
654	popl %eax
655#endif
656	iret
657ENDPROC(ignore_int)
658__INITDATA
659	.align 4
660early_recursion_flag:
661	.long 0
662
663__REFDATA
664	.align 4
665ENTRY(initial_code)
666	.long i386_start_kernel
667ENTRY(setup_once_ref)
668	.long setup_once
669
670/*
671 * BSS section
672 */
673__PAGE_ALIGNED_BSS
674	.align PAGE_SIZE
675#ifdef CONFIG_X86_PAE
676initial_pg_pmd:
677	.fill 1024*KPMDS,4,0
678#else
679ENTRY(initial_page_table)
680	.fill 1024,4,0
681#endif
682initial_pg_fixmap:
683	.fill 1024,4,0
684ENTRY(empty_zero_page)
685	.fill 4096,1,0
686ENTRY(swapper_pg_dir)
687	.fill 1024,4,0
688
689/*
690 * This starts the data section.
691 */
692#ifdef CONFIG_X86_PAE
693__PAGE_ALIGNED_DATA
694	/* Page-aligned for the benefit of paravirt? */
695	.align PAGE_SIZE
696ENTRY(initial_page_table)
697	.long	pa(initial_pg_pmd+PGD_IDENT_ATTR),0	/* low identity map */
698# if KPMDS == 3
699	.long	pa(initial_pg_pmd+PGD_IDENT_ATTR),0
700	.long	pa(initial_pg_pmd+PGD_IDENT_ATTR+0x1000),0
701	.long	pa(initial_pg_pmd+PGD_IDENT_ATTR+0x2000),0
702# elif KPMDS == 2
703	.long	0,0
704	.long	pa(initial_pg_pmd+PGD_IDENT_ATTR),0
705	.long	pa(initial_pg_pmd+PGD_IDENT_ATTR+0x1000),0
706# elif KPMDS == 1
707	.long	0,0
708	.long	0,0
709	.long	pa(initial_pg_pmd+PGD_IDENT_ATTR),0
710# else
711#  error "Kernel PMDs should be 1, 2 or 3"
712# endif
713	.align PAGE_SIZE		/* needs to be page-sized too */
714#endif
715
716.data
717.balign 4
718ENTRY(stack_start)
719	.long init_thread_union+THREAD_SIZE
720
721__INITRODATA
722int_msg:
723	.asciz "Unknown interrupt or fault at: %p %p %p\n"
724
725fault_msg:
726/* fault info: */
727	.ascii "BUG: Int %d: CR2 %p\n"
728/* regs pushed in early_idt_handler: */
729	.ascii "     EDI %p  ESI %p  EBP %p  EBX %p\n"
730	.ascii "     ESP %p   ES %p   DS %p\n"
731	.ascii "     EDX %p  ECX %p  EAX %p\n"
732/* fault frame: */
733	.ascii "     vec %p  err %p  EIP %p   CS %p  flg %p\n"
734	.ascii "Stack: %p %p %p %p %p %p %p %p\n"
735	.ascii "       %p %p %p %p %p %p %p %p\n"
736	.asciz "       %p %p %p %p %p %p %p %p\n"
737
738#include "../../x86/xen/xen-head.S"
739
740/*
741 * The IDT and GDT 'descriptors' are a strange 48-bit object
742 * only used by the lidt and lgdt instructions. They are not
743 * like usual segment descriptors - they consist of a 16-bit
744 * segment size, and 32-bit linear address value:
745 */
746
747	.data
748.globl boot_gdt_descr
749.globl idt_descr
750
751	ALIGN
752# early boot GDT descriptor (must use 1:1 address mapping)
753	.word 0				# 32 bit align gdt_desc.address
754boot_gdt_descr:
755	.word __BOOT_DS+7
756	.long boot_gdt - __PAGE_OFFSET
757
758	.word 0				# 32-bit align idt_desc.address
759idt_descr:
760	.word IDT_ENTRIES*8-1		# idt contains 256 entries
761	.long idt_table
762
763# boot GDT descriptor (later on used by CPU#0):
764	.word 0				# 32 bit align gdt_desc.address
765ENTRY(early_gdt_descr)
766	.word GDT_ENTRIES*8-1
767	.long gdt_page			/* Overwritten for secondary CPUs */
768
769/*
770 * The boot_gdt must mirror the equivalent in setup.S and is
771 * used only for booting.
772 */
773	.align L1_CACHE_BYTES
774ENTRY(boot_gdt)
775	.fill GDT_ENTRY_BOOT_CS,8,0
776	.quad 0x00cf9a000000ffff	/* kernel 4GB code at 0x00000000 */
777	.quad 0x00cf92000000ffff	/* kernel 4GB data at 0x00000000 */
778