Linux Audio

Check our new training course

Embedded Linux Audio

Check our new training course
with Creative Commons CC-BY-SA
lecture materials

Bootlin logo

Elixir Cross Referencer

Loading...
  1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
/* SPDX-License-Identifier: GPL-2.0 */
/*
 *  linux/arch/x86/kernel/head_64.S -- start in 32bit and switch to 64bit
 *
 *  Copyright (C) 2000 Andrea Arcangeli <andrea@suse.de> SuSE
 *  Copyright (C) 2000 Pavel Machek <pavel@suse.cz>
 *  Copyright (C) 2000 Karsten Keil <kkeil@suse.de>
 *  Copyright (C) 2001,2002 Andi Kleen <ak@suse.de>
 *  Copyright (C) 2005 Eric Biederman <ebiederm@xmission.com>
 */


#include <linux/linkage.h>
#include <linux/threads.h>
#include <linux/init.h>
#include <linux/pgtable.h>
#include <asm/segment.h>
#include <asm/page.h>
#include <asm/msr.h>
#include <asm/cache.h>
#include <asm/processor-flags.h>
#include <asm/percpu.h>
#include <asm/nops.h>
#include "../entry/calling.h"
#include <asm/export.h>
#include <asm/nospec-branch.h>
#include <asm/fixmap.h>

#ifdef CONFIG_PARAVIRT_XXL
#include <asm/asm-offsets.h>
#include <asm/paravirt.h>
#define GET_CR2_INTO(reg) GET_CR2_INTO_AX ; _ASM_MOV %_ASM_AX, reg
#else
#define INTERRUPT_RETURN iretq
#define GET_CR2_INTO(reg) _ASM_MOV %cr2, reg
#endif

/*
 * We are not able to switch in one step to the final KERNEL ADDRESS SPACE
 * because we need identity-mapped pages.
 */
#define l4_index(x)	(((x) >> 39) & 511)
#define pud_index(x)	(((x) >> PUD_SHIFT) & (PTRS_PER_PUD-1))

L4_PAGE_OFFSET = l4_index(__PAGE_OFFSET_BASE_L4)
L4_START_KERNEL = l4_index(__START_KERNEL_map)

L3_START_KERNEL = pud_index(__START_KERNEL_map)

	.text
	__HEAD
	.code64
SYM_CODE_START_NOALIGN(startup_64)
	UNWIND_HINT_EMPTY
	/*
	 * At this point the CPU runs in 64bit mode CS.L = 1 CS.D = 0,
	 * and someone has loaded an identity mapped page table
	 * for us.  These identity mapped page tables map all of the
	 * kernel pages and possibly all of memory.
	 *
	 * %rsi holds a physical pointer to real_mode_data.
	 *
	 * We come here either directly from a 64bit bootloader, or from
	 * arch/x86/boot/compressed/head_64.S.
	 *
	 * We only come here initially at boot nothing else comes here.
	 *
	 * Since we may be loaded at an address different from what we were
	 * compiled to run at we first fixup the physical addresses in our page
	 * tables and then reload them.
	 */

	/* Set up the stack for verify_cpu(), similar to initial_stack below */
	leaq	(__end_init_task - SIZEOF_PTREGS)(%rip), %rsp

	leaq	_text(%rip), %rdi
	pushq	%rsi
	call	startup_64_setup_env
	popq	%rsi

	/* Now switch to __KERNEL_CS so IRET works reliably */
	pushq	$__KERNEL_CS
	leaq	.Lon_kernel_cs(%rip), %rax
	pushq	%rax
	lretq

.Lon_kernel_cs:
	UNWIND_HINT_EMPTY

	/* Sanitize CPU configuration */
	call verify_cpu

	/*
	 * Perform pagetable fixups. Additionally, if SME is active, encrypt
	 * the kernel and retrieve the modifier (SME encryption mask if SME
	 * is active) to be added to the initial pgdir entry that will be
	 * programmed into CR3.
	 */
	leaq	_text(%rip), %rdi
	pushq	%rsi
	call	__startup_64
	popq	%rsi

	/* Form the CR3 value being sure to include the CR3 modifier */
	addq	$(early_top_pgt - __START_KERNEL_map), %rax
	jmp 1f
SYM_CODE_END(startup_64)

SYM_CODE_START(secondary_startup_64)
	UNWIND_HINT_EMPTY
	/*
	 * At this point the CPU runs in 64bit mode CS.L = 1 CS.D = 0,
	 * and someone has loaded a mapped page table.
	 *
	 * %rsi holds a physical pointer to real_mode_data.
	 *
	 * We come here either from startup_64 (using physical addresses)
	 * or from trampoline.S (using virtual addresses).
	 *
	 * Using virtual addresses from trampoline.S removes the need
	 * to have any identity mapped pages in the kernel page table
	 * after the boot processor executes this code.
	 */

	/* Sanitize CPU configuration */
	call verify_cpu

	/*
	 * The secondary_startup_64_no_verify entry point is only used by
	 * SEV-ES guests. In those guests the call to verify_cpu() would cause
	 * #VC exceptions which can not be handled at this stage of secondary
	 * CPU bringup.
	 *
	 * All non SEV-ES systems, especially Intel systems, need to execute
	 * verify_cpu() above to make sure NX is enabled.
	 */
SYM_INNER_LABEL(secondary_startup_64_no_verify, SYM_L_GLOBAL)
	UNWIND_HINT_EMPTY

	/*
	 * Retrieve the modifier (SME encryption mask if SME is active) to be
	 * added to the initial pgdir entry that will be programmed into CR3.
	 */
	pushq	%rsi
	call	__startup_secondary_64
	popq	%rsi

	/* Form the CR3 value being sure to include the CR3 modifier */
	addq	$(init_top_pgt - __START_KERNEL_map), %rax
1:

	/* Enable PAE mode, PGE and LA57 */
	movl	$(X86_CR4_PAE | X86_CR4_PGE), %ecx
#ifdef CONFIG_X86_5LEVEL
	testl	$1, __pgtable_l5_enabled(%rip)
	jz	1f
	orl	$X86_CR4_LA57, %ecx
1:
#endif
	movq	%rcx, %cr4

	/* Setup early boot stage 4-/5-level pagetables. */
	addq	phys_base(%rip), %rax

	/*
	 * For SEV guests: Verify that the C-bit is correct. A malicious
	 * hypervisor could lie about the C-bit position to perform a ROP
	 * attack on the guest by writing to the unencrypted stack and wait for
	 * the next RET instruction.
	 * %rsi carries pointer to realmode data and is callee-clobbered. Save
	 * and restore it.
	 */
	pushq	%rsi
	movq	%rax, %rdi
	call	sev_verify_cbit
	popq	%rsi

	/* Switch to new page-table */
	movq	%rax, %cr3

	/* Ensure I am executing from virtual addresses */
	movq	$1f, %rax
	ANNOTATE_RETPOLINE_SAFE
	jmp	*%rax
1:
	UNWIND_HINT_EMPTY

	/*
	 * We must switch to a new descriptor in kernel space for the GDT
	 * because soon the kernel won't have access anymore to the userspace
	 * addresses where we're currently running on. We have to do that here
	 * because in 32bit we couldn't load a 64bit linear address.
	 */
	lgdt	early_gdt_descr(%rip)

	/* set up data segments */
	xorl %eax,%eax
	movl %eax,%ds
	movl %eax,%ss
	movl %eax,%es

	/*
	 * We don't really need to load %fs or %gs, but load them anyway
	 * to kill any stale realmode selectors.  This allows execution
	 * under VT hardware.
	 */
	movl %eax,%fs
	movl %eax,%gs

	/* Set up %gs.
	 *
	 * The base of %gs always points to fixed_percpu_data. If the
	 * stack protector canary is enabled, it is located at %gs:40.
	 * Note that, on SMP, the boot cpu uses init data section until
	 * the per cpu areas are set up.
	 */
	movl	$MSR_GS_BASE,%ecx
	movl	initial_gs(%rip),%eax
	movl	initial_gs+4(%rip),%edx
	wrmsr

	/*
	 * Setup a boot time stack - Any secondary CPU will have lost its stack
	 * by now because the cr3-switch above unmaps the real-mode stack
	 */
	movq initial_stack(%rip), %rsp

	/* Setup and Load IDT */
	pushq	%rsi
	call	early_setup_idt
	popq	%rsi

	/* Check if nx is implemented */
	movl	$0x80000001, %eax
	cpuid
	movl	%edx,%edi

	/* Setup EFER (Extended Feature Enable Register) */
	movl	$MSR_EFER, %ecx
	rdmsr
	btsl	$_EFER_SCE, %eax	/* Enable System Call */
	btl	$20,%edi		/* No Execute supported? */
	jnc     1f
	btsl	$_EFER_NX, %eax
	btsq	$_PAGE_BIT_NX,early_pmd_flags(%rip)
1:	wrmsr				/* Make changes effective */

	/* Setup cr0 */
	movl	$CR0_STATE, %eax
	/* Make changes effective */
	movq	%rax, %cr0

	/* zero EFLAGS after setting rsp */
	pushq $0
	popfq

	/* rsi is pointer to real mode structure with interesting info.
	   pass it to C */
	movq	%rsi, %rdi

.Ljump_to_C_code:
	/*
	 * Jump to run C code and to be on a real kernel address.
	 * Since we are running on identity-mapped space we have to jump
	 * to the full 64bit address, this is only possible as indirect
	 * jump.  In addition we need to ensure %cs is set so we make this
	 * a far return.
	 *
	 * Note: do not change to far jump indirect with 64bit offset.
	 *
	 * AMD does not support far jump indirect with 64bit offset.
	 * AMD64 Architecture Programmer's Manual, Volume 3: states only
	 *	JMP FAR mem16:16 FF /5 Far jump indirect,
	 *		with the target specified by a far pointer in memory.
	 *	JMP FAR mem16:32 FF /5 Far jump indirect,
	 *		with the target specified by a far pointer in memory.
	 *
	 * Intel64 does support 64bit offset.
	 * Software Developer Manual Vol 2: states:
	 *	FF /5 JMP m16:16 Jump far, absolute indirect,
	 *		address given in m16:16
	 *	FF /5 JMP m16:32 Jump far, absolute indirect,
	 *		address given in m16:32.
	 *	REX.W + FF /5 JMP m16:64 Jump far, absolute indirect,
	 *		address given in m16:64.
	 */
	pushq	$.Lafter_lret	# put return address on stack for unwinder
	xorl	%ebp, %ebp	# clear frame pointer
	movq	initial_code(%rip), %rax
	pushq	$__KERNEL_CS	# set correct cs
	pushq	%rax		# target address in negative space
	lretq
.Lafter_lret:
SYM_CODE_END(secondary_startup_64)

#include "verify_cpu.S"
#include "sev_verify_cbit.S"

#ifdef CONFIG_HOTPLUG_CPU
/*
 * Boot CPU0 entry point. It's called from play_dead(). Everything has been set
 * up already except stack. We just set up stack here. Then call
 * start_secondary() via .Ljump_to_C_code.
 */
SYM_CODE_START(start_cpu0)
	UNWIND_HINT_EMPTY
	movq	initial_stack(%rip), %rsp
	jmp	.Ljump_to_C_code
SYM_CODE_END(start_cpu0)
#endif

#ifdef CONFIG_AMD_MEM_ENCRYPT
/*
 * VC Exception handler used during early boot when running on kernel
 * addresses, but before the switch to the idt_table can be made.
 * The early_idt_handler_array can't be used here because it calls into a lot
 * of __init code and this handler is also used during CPU offlining/onlining.
 * Therefore this handler ends up in the .text section so that it stays around
 * when .init.text is freed.
 */
SYM_CODE_START_NOALIGN(vc_boot_ghcb)
	UNWIND_HINT_IRET_REGS offset=8

	/* Build pt_regs */
	PUSH_AND_CLEAR_REGS

	/* Call C handler */
	movq    %rsp, %rdi
	movq	ORIG_RAX(%rsp), %rsi
	movq	initial_vc_handler(%rip), %rax
	ANNOTATE_RETPOLINE_SAFE
	call	*%rax

	/* Unwind pt_regs */
	POP_REGS

	/* Remove Error Code */
	addq    $8, %rsp

	/* Pure iret required here - don't use INTERRUPT_RETURN */
	iretq
SYM_CODE_END(vc_boot_ghcb)
#endif

	/* Both SMP bootup and ACPI suspend change these variables */
	__REFDATA
	.balign	8
SYM_DATA(initial_code,	.quad x86_64_start_kernel)
SYM_DATA(initial_gs,	.quad INIT_PER_CPU_VAR(fixed_percpu_data))
#ifdef CONFIG_AMD_MEM_ENCRYPT
SYM_DATA(initial_vc_handler,	.quad handle_vc_boot_ghcb)
#endif

/*
 * The SIZEOF_PTREGS gap is a convention which helps the in-kernel unwinder
 * reliably detect the end of the stack.
 */
SYM_DATA(initial_stack, .quad init_thread_union + THREAD_SIZE - SIZEOF_PTREGS)
	__FINITDATA

	__INIT
SYM_CODE_START(early_idt_handler_array)
	i = 0
	.rept NUM_EXCEPTION_VECTORS
	.if ((EXCEPTION_ERRCODE_MASK >> i) & 1) == 0
		UNWIND_HINT_IRET_REGS
		pushq $0	# Dummy error code, to make stack frame uniform
	.else
		UNWIND_HINT_IRET_REGS offset=8
	.endif
	pushq $i		# 72(%rsp) Vector number
	jmp early_idt_handler_common
	UNWIND_HINT_IRET_REGS
	i = i + 1
	.fill early_idt_handler_array + i*EARLY_IDT_HANDLER_SIZE - ., 1, 0xcc
	.endr
	UNWIND_HINT_IRET_REGS offset=16
SYM_CODE_END(early_idt_handler_array)

SYM_CODE_START_LOCAL(early_idt_handler_common)
	/*
	 * The stack is the hardware frame, an error code or zero, and the
	 * vector number.
	 */
	cld

	incl early_recursion_flag(%rip)

	/* The vector number is currently in the pt_regs->di slot. */
	pushq %rsi				/* pt_regs->si */
	movq 8(%rsp), %rsi			/* RSI = vector number */
	movq %rdi, 8(%rsp)			/* pt_regs->di = RDI */
	pushq %rdx				/* pt_regs->dx */
	pushq %rcx				/* pt_regs->cx */
	pushq %rax				/* pt_regs->ax */
	pushq %r8				/* pt_regs->r8 */
	pushq %r9				/* pt_regs->r9 */
	pushq %r10				/* pt_regs->r10 */
	pushq %r11				/* pt_regs->r11 */
	pushq %rbx				/* pt_regs->bx */
	pushq %rbp				/* pt_regs->bp */
	pushq %r12				/* pt_regs->r12 */
	pushq %r13				/* pt_regs->r13 */
	pushq %r14				/* pt_regs->r14 */
	pushq %r15				/* pt_regs->r15 */
	UNWIND_HINT_REGS

	movq %rsp,%rdi		/* RDI = pt_regs; RSI is already trapnr */
	call do_early_exception

	decl early_recursion_flag(%rip)
	jmp restore_regs_and_return_to_kernel
SYM_CODE_END(early_idt_handler_common)

#ifdef CONFIG_AMD_MEM_ENCRYPT
/*
 * VC Exception handler used during very early boot. The
 * early_idt_handler_array can't be used because it returns via the
 * paravirtualized INTERRUPT_RETURN and pv-ops don't work that early.
 *
 * This handler will end up in the .init.text section and not be
 * available to boot secondary CPUs.
 */
SYM_CODE_START_NOALIGN(vc_no_ghcb)
	UNWIND_HINT_IRET_REGS offset=8

	/* Build pt_regs */
	PUSH_AND_CLEAR_REGS

	/* Call C handler */
	movq    %rsp, %rdi
	movq	ORIG_RAX(%rsp), %rsi
	call    do_vc_no_ghcb

	/* Unwind pt_regs */
	POP_REGS

	/* Remove Error Code */
	addq    $8, %rsp

	/* Pure iret required here - don't use INTERRUPT_RETURN */
	iretq
SYM_CODE_END(vc_no_ghcb)
#endif

#define SYM_DATA_START_PAGE_ALIGNED(name)			\
	SYM_START(name, SYM_L_GLOBAL, .balign PAGE_SIZE)

#ifdef CONFIG_PAGE_TABLE_ISOLATION
/*
 * Each PGD needs to be 8k long and 8k aligned.  We do not
 * ever go out to userspace with these, so we do not
 * strictly *need* the second page, but this allows us to
 * have a single set_pgd() implementation that does not
 * need to worry about whether it has 4k or 8k to work
 * with.
 *
 * This ensures PGDs are 8k long:
 */
#define PTI_USER_PGD_FILL	512
/* This ensures they are 8k-aligned: */
#define SYM_DATA_START_PTI_ALIGNED(name) \
	SYM_START(name, SYM_L_GLOBAL, .balign 2 * PAGE_SIZE)
#else
#define SYM_DATA_START_PTI_ALIGNED(name) \
	SYM_DATA_START_PAGE_ALIGNED(name)
#define PTI_USER_PGD_FILL	0
#endif

/* Automate the creation of 1 to 1 mapping pmd entries */
#define PMDS(START, PERM, COUNT)			\
	i = 0 ;						\
	.rept (COUNT) ;					\
	.quad	(START) + (i << PMD_SHIFT) + (PERM) ;	\
	i = i + 1 ;					\
	.endr

	__INITDATA
	.balign 4

SYM_DATA_START_PTI_ALIGNED(early_top_pgt)
	.fill	512,8,0
	.fill	PTI_USER_PGD_FILL,8,0
SYM_DATA_END(early_top_pgt)

SYM_DATA_START_PAGE_ALIGNED(early_dynamic_pgts)
	.fill	512*EARLY_DYNAMIC_PAGE_TABLES,8,0
SYM_DATA_END(early_dynamic_pgts)

SYM_DATA(early_recursion_flag, .long 0)

	.data

#if defined(CONFIG_XEN_PV) || defined(CONFIG_PVH)
SYM_DATA_START_PTI_ALIGNED(init_top_pgt)
	.quad   level3_ident_pgt - __START_KERNEL_map + _KERNPG_TABLE_NOENC
	.org    init_top_pgt + L4_PAGE_OFFSET*8, 0
	.quad   level3_ident_pgt - __START_KERNEL_map + _KERNPG_TABLE_NOENC
	.org    init_top_pgt + L4_START_KERNEL*8, 0
	/* (2^48-(2*1024*1024*1024))/(2^39) = 511 */
	.quad   level3_kernel_pgt - __START_KERNEL_map + _PAGE_TABLE_NOENC
	.fill	PTI_USER_PGD_FILL,8,0
SYM_DATA_END(init_top_pgt)

SYM_DATA_START_PAGE_ALIGNED(level3_ident_pgt)
	.quad	level2_ident_pgt - __START_KERNEL_map + _KERNPG_TABLE_NOENC
	.fill	511, 8, 0
SYM_DATA_END(level3_ident_pgt)
SYM_DATA_START_PAGE_ALIGNED(level2_ident_pgt)
	/*
	 * Since I easily can, map the first 1G.
	 * Don't set NX because code runs from these pages.
	 *
	 * Note: This sets _PAGE_GLOBAL despite whether
	 * the CPU supports it or it is enabled.  But,
	 * the CPU should ignore the bit.
	 */
	PMDS(0, __PAGE_KERNEL_IDENT_LARGE_EXEC, PTRS_PER_PMD)
SYM_DATA_END(level2_ident_pgt)
#else
SYM_DATA_START_PTI_ALIGNED(init_top_pgt)
	.fill	512,8,0
	.fill	PTI_USER_PGD_FILL,8,0
SYM_DATA_END(init_top_pgt)
#endif

#ifdef CONFIG_X86_5LEVEL
SYM_DATA_START_PAGE_ALIGNED(level4_kernel_pgt)
	.fill	511,8,0
	.quad	level3_kernel_pgt - __START_KERNEL_map + _PAGE_TABLE_NOENC
SYM_DATA_END(level4_kernel_pgt)
#endif

SYM_DATA_START_PAGE_ALIGNED(level3_kernel_pgt)
	.fill	L3_START_KERNEL,8,0
	/* (2^48-(2*1024*1024*1024)-((2^39)*511))/(2^30) = 510 */
	.quad	level2_kernel_pgt - __START_KERNEL_map + _KERNPG_TABLE_NOENC
	.quad	level2_fixmap_pgt - __START_KERNEL_map + _PAGE_TABLE_NOENC
SYM_DATA_END(level3_kernel_pgt)

SYM_DATA_START_PAGE_ALIGNED(level2_kernel_pgt)
	/*
	 * 512 MB kernel mapping. We spend a full page on this pagetable
	 * anyway.
	 *
	 * The kernel code+data+bss must not be bigger than that.
	 *
	 * (NOTE: at +512MB starts the module area, see MODULES_VADDR.
	 *  If you want to increase this then increase MODULES_VADDR
	 *  too.)
	 *
	 *  This table is eventually used by the kernel during normal
	 *  runtime.  Care must be taken to clear out undesired bits
	 *  later, like _PAGE_RW or _PAGE_GLOBAL in some cases.
	 */
	PMDS(0, __PAGE_KERNEL_LARGE_EXEC,
		KERNEL_IMAGE_SIZE/PMD_SIZE)
SYM_DATA_END(level2_kernel_pgt)

SYM_DATA_START_PAGE_ALIGNED(level2_fixmap_pgt)
	.fill	(512 - 4 - FIXMAP_PMD_NUM),8,0
	pgtno = 0
	.rept (FIXMAP_PMD_NUM)
	.quad level1_fixmap_pgt + (pgtno << PAGE_SHIFT) - __START_KERNEL_map \
		+ _PAGE_TABLE_NOENC;
	pgtno = pgtno + 1
	.endr
	/* 6 MB reserved space + a 2MB hole */
	.fill	4,8,0
SYM_DATA_END(level2_fixmap_pgt)

SYM_DATA_START_PAGE_ALIGNED(level1_fixmap_pgt)
	.rept (FIXMAP_PMD_NUM)
	.fill	512,8,0
	.endr
SYM_DATA_END(level1_fixmap_pgt)

#undef PMDS

	.data
	.align 16

SYM_DATA(early_gdt_descr,		.word GDT_ENTRIES*8-1)
SYM_DATA_LOCAL(early_gdt_descr_base,	.quad INIT_PER_CPU_VAR(gdt_page))

	.align 16
/* This must match the first entry in level2_kernel_pgt */
SYM_DATA(phys_base, .quad 0x0)
EXPORT_SYMBOL(phys_base)

#include "../../x86/xen/xen-head.S"

	__PAGE_ALIGNED_BSS
SYM_DATA_START_PAGE_ALIGNED(empty_zero_page)
	.skip PAGE_SIZE
SYM_DATA_END(empty_zero_page)
EXPORT_SYMBOL(empty_zero_page)