summaryrefslogtreecommitdiff
path: root/arch/x86/boot/compressed/head_64.S
blob: 6233ae35d0d9a9d6682be147a1d3f305c59b3e30 (plain)
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
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
/* SPDX-License-Identifier: GPL-2.0 */
/*
 *  linux/boot/head.S
 *
 *  Copyright (C) 1991, 1992, 1993  Linus Torvalds
 */

/*
 *  head.S contains the 32-bit startup code.
 *
 * NOTE!!! Startup happens at absolute address 0x00001000, which is also where
 * the page directory will exist. The startup code will be overwritten by
 * the page directory. [According to comments etc elsewhere on a compressed
 * kernel it will end up at 0x1000 + 1Mb I hope so as I assume this. - AC]
 *
 * Page 0 is deliberately kept safe, since System Management Mode code in 
 * laptops may need to access the BIOS data stored there.  This is also
 * useful for future device drivers that either access the BIOS via VM86 
 * mode.
 */

/*
 * High loaded stuff by Hans Lermen & Werner Almesberger, Feb. 1996
 */
	.code32
	.text

#include <linux/init.h>
#include <linux/linkage.h>
#include <asm/segment.h>
#include <asm/boot.h>
#include <asm/msr.h>
#include <asm/processor-flags.h>
#include <asm/asm-offsets.h>
#include <asm/bootparam.h>
#include "pgtable.h"

/*
 * Locally defined symbols should be marked hidden:
 */
	.hidden _bss
	.hidden _ebss
	.hidden _got
	.hidden _egot

	__HEAD
	.code32
ENTRY(startup_32)
	/*
	 * 32bit entry is 0 and it is ABI so immutable!
	 * If we come here directly from a bootloader,
	 * kernel(text+data+bss+brk) ramdisk, zero_page, command line
	 * all need to be under the 4G limit.
	 */
	cld
	/*
	 * Test KEEP_SEGMENTS flag to see if the bootloader is asking
	 * us to not reload segments
	 */
	testb $KEEP_SEGMENTS, BP_loadflags(%esi)
	jnz 1f

	cli
	movl	$(__BOOT_DS), %eax
	movl	%eax, %ds
	movl	%eax, %es
	movl	%eax, %ss
1:

/*
 * Calculate the delta between where we were compiled to run
 * at and where we were actually loaded at.  This can only be done
 * with a short local call on x86.  Nothing  else will tell us what
 * address we are running at.  The reserved chunk of the real-mode
 * data at 0x1e4 (defined as a scratch field) are used as the stack
 * for this calculation. Only 4 bytes are needed.
 */
	leal	(BP_scratch+4)(%esi), %esp
	call	1f
1:	popl	%ebp
	subl	$1b, %ebp

/* setup a stack and make sure cpu supports long mode. */
	movl	$boot_stack_end, %eax
	addl	%ebp, %eax
	movl	%eax, %esp

	call	verify_cpu
	testl	%eax, %eax
	jnz	no_longmode

/*
 * Compute the delta between where we were compiled to run at
 * and where the code will actually run at.
 *
 * %ebp contains the address we are loaded at by the boot loader and %ebx
 * contains the address where we should move the kernel image temporarily
 * for safe in-place decompression.
 */

#ifdef CONFIG_RELOCATABLE
	movl	%ebp, %ebx
	movl	BP_kernel_alignment(%esi), %eax
	decl	%eax
	addl	%eax, %ebx
	notl	%eax
	andl	%eax, %ebx
	cmpl	$LOAD_PHYSICAL_ADDR, %ebx
	jge	1f
#endif
	movl	$LOAD_PHYSICAL_ADDR, %ebx
1:

	/* Target address to relocate to for decompression */
	movl	BP_init_size(%esi), %eax
	subl	$_end, %eax
	addl	%eax, %ebx

/*
 * Prepare for entering 64 bit mode
 */

	/* Load new GDT with the 64bit segments using 32bit descriptor */
	addl	%ebp, gdt+2(%ebp)
	lgdt	gdt(%ebp)

	/* Enable PAE mode */
	movl	%cr4, %eax
	orl	$X86_CR4_PAE, %eax
	movl	%eax, %cr4

 /*
  * Build early 4G boot pagetable
  */
	/*
	 * If SEV is active then set the encryption mask in the page tables.
	 * This will insure that when the kernel is copied and decompressed
	 * it will be done so encrypted.
	 */
	call	get_sev_encryption_bit
	xorl	%edx, %edx
	testl	%eax, %eax
	jz	1f
	subl	$32, %eax	/* Encryption bit is always above bit 31 */
	bts	%eax, %edx	/* Set encryption mask for page tables */
1:

	/* Initialize Page tables to 0 */
	leal	pgtable(%ebx), %edi
	xorl	%eax, %eax
	movl	$(BOOT_INIT_PGT_SIZE/4), %ecx
	rep	stosl

	/* Build Level 4 */
	leal	pgtable + 0(%ebx), %edi
	leal	0x1007 (%edi), %eax
	movl	%eax, 0(%edi)
	addl	%edx, 4(%edi)

	/* Build Level 3 */
	leal	pgtable + 0x1000(%ebx), %edi
	leal	0x1007(%edi), %eax
	movl	$4, %ecx
1:	movl	%eax, 0x00(%edi)
	addl	%edx, 0x04(%edi)
	addl	$0x00001000, %eax
	addl	$8, %edi
	decl	%ecx
	jnz	1b

	/* Build Level 2 */
	leal	pgtable + 0x2000(%ebx), %edi
	movl	$0x00000183, %eax
	movl	$2048, %ecx
1:	movl	%eax, 0(%edi)
	addl	%edx, 4(%edi)
	addl	$0x00200000, %eax
	addl	$8, %edi
	decl	%ecx
	jnz	1b

	/* Enable the boot page tables */
	leal	pgtable(%ebx), %eax
	movl	%eax, %cr3

	/* Enable Long mode in EFER (Extended Feature Enable Register) */
	movl	$MSR_EFER, %ecx
	rdmsr
	btsl	$_EFER_LME, %eax
	wrmsr

	/* After gdt is loaded */
	xorl	%eax, %eax
	lldt	%ax
	movl    $__BOOT_TSS, %eax
	ltr	%ax

	/*
	 * Setup for the jump to 64bit mode
	 *
	 * When the jump is performend we will be in long mode but
	 * in 32bit compatibility mode with EFER.LME = 1, CS.L = 0, CS.D = 1
	 * (and in turn EFER.LMA = 1).	To jump into 64bit mode we use
	 * the new gdt/idt that has __KERNEL_CS with CS.L = 1.
	 * We place all of the values on our mini stack so lret can
	 * used to perform that far jump.
	 */
	pushl	$__KERNEL_CS
	leal	startup_64(%ebp), %eax
#ifdef CONFIG_EFI_MIXED
	movl	efi32_config(%ebp), %ebx
	cmp	$0, %ebx
	jz	1f
	leal	handover_entry(%ebp), %eax
1:
#endif
	pushl	%eax

	/* Enter paged protected Mode, activating Long Mode */
	movl	$(X86_CR0_PG | X86_CR0_PE), %eax /* Enable Paging and Protected mode */
	movl	%eax, %cr0

	/* Jump from 32bit compatibility mode into 64bit mode. */
	lret
ENDPROC(startup_32)

#ifdef CONFIG_EFI_MIXED
	.org 0x190
ENTRY(efi32_stub_entry)
	add	$0x4, %esp		/* Discard return address */
	popl	%ecx
	popl	%edx
	popl	%esi

	leal	(BP_scratch+4)(%esi), %esp
	call	1f
1:	pop	%ebp
	subl	$1b, %ebp

	movl	%ecx, efi32_config(%ebp)
	movl	%edx, efi32_config+8(%ebp)
	sgdtl	efi32_boot_gdt(%ebp)

	leal	efi32_config(%ebp), %eax
	movl	%eax, efi_config(%ebp)

	jmp	startup_32
ENDPROC(efi32_stub_entry)
#endif

	.code64
	.org 0x200
ENTRY(startup_64)
	/*
	 * 64bit entry is 0x200 and it is ABI so immutable!
	 * We come here either from startup_32 or directly from a
	 * 64bit bootloader.
	 * If we come here from a bootloader, kernel(text+data+bss+brk),
	 * ramdisk, zero_page, command line could be above 4G.
	 * We depend on an identity mapped page table being provided
	 * that maps our entire kernel(text+data+bss+brk), zero page
	 * and command line.
	 */

	/* Setup data segments. */
	xorl	%eax, %eax
	movl	%eax, %ds
	movl	%eax, %es
	movl	%eax, %ss
	movl	%eax, %fs
	movl	%eax, %gs

	/*
	 * Compute the decompressed kernel start address.  It is where
	 * we were loaded at aligned to a 2M boundary. %rbp contains the
	 * decompressed kernel start address.
	 *
	 * If it is a relocatable kernel then decompress and run the kernel
	 * from load address aligned to 2MB addr, otherwise decompress and
	 * run the kernel from LOAD_PHYSICAL_ADDR
	 *
	 * We cannot rely on the calculation done in 32-bit mode, since we
	 * may have been invoked via the 64-bit entry point.
	 */

	/* Start with the delta to where the kernel will run at. */
#ifdef CONFIG_RELOCATABLE
	leaq	startup_32(%rip) /* - $startup_32 */, %rbp
	movl	BP_kernel_alignment(%rsi), %eax
	decl	%eax
	addq	%rax, %rbp
	notq	%rax
	andq	%rax, %rbp
	cmpq	$LOAD_PHYSICAL_ADDR, %rbp
	jge	1f
#endif
	movq	$LOAD_PHYSICAL_ADDR, %rbp
1:

	/* Target address to relocate to for decompression */
	movl	BP_init_size(%rsi), %ebx
	subl	$_end, %ebx
	addq	%rbp, %rbx

	/* Set up the stack */
	leaq	boot_stack_end(%rbx), %rsp

	/*
	 * paging_prepare() and cleanup_trampoline() below can have GOT
	 * references. Adjust the table with address we are running at.
	 *
	 * Zero RAX for adjust_got: the GOT was not adjusted before;
	 * there's no adjustment to undo.
	 */
	xorq	%rax, %rax

	/*
	 * Calculate the address the binary is loaded at and use it as
	 * a GOT adjustment.
	 */
	call	1f
1:	popq	%rdi
	subq	$1b, %rdi

	call	adjust_got

	/*
	 * At this point we are in long mode with 4-level paging enabled,
	 * but we might want to enable 5-level paging or vice versa.
	 *
	 * The problem is that we cannot do it directly. Setting or clearing
	 * CR4.LA57 in long mode would trigger #GP. So we need to switch off
	 * long mode and paging first.
	 *
	 * We also need a trampoline in lower memory to switch over from
	 * 4- to 5-level paging for cases when the bootloader puts the kernel
	 * above 4G, but didn't enable 5-level paging for us.
	 *
	 * The same trampoline can be used to switch from 5- to 4-level paging
	 * mode, like when starting 4-level paging kernel via kexec() when
	 * original kernel worked in 5-level paging mode.
	 *
	 * For the trampoline, we need the top page table to reside in lower
	 * memory as we don't have a way to load 64-bit values into CR3 in
	 * 32-bit mode.
	 *
	 * We go though the trampoline even if we don't have to: if we're
	 * already in a desired paging mode. This way the trampoline code gets
	 * tested on every boot.
	 */

	/* Make sure we have GDT with 32-bit code segment */
	leaq	gdt(%rip), %rax
	movq	%rax, gdt64+2(%rip)
	lgdt	gdt64(%rip)

	/*
	 * paging_prepare() sets up the trampoline and checks if we need to
	 * enable 5-level paging.
	 *
	 * paging_prepare() returns a two-quadword structure which lands
	 * into RDX:RAX:
	 *   - Address of the trampoline is returned in RAX.
	 *   - Non zero RDX means trampoline needs to enable 5-level
	 *     paging.
	 *
	 * RSI holds real mode data and needs to be preserved across
	 * this function call.
	 */
	pushq	%rsi
	movq	%rsi, %rdi		/* real mode address */
	call	paging_prepare
	popq	%rsi

	/* Save the trampoline address in RCX */
	movq	%rax, %rcx

	/*
	 * Load the address of trampoline_return() into RDI.
	 * It will be used by the trampoline to return to the main code.
	 */
	leaq	trampoline_return(%rip), %rdi

	/* Switch to compatibility mode (CS.L = 0 CS.D = 1) via far return */
	pushq	$__KERNEL32_CS
	leaq	TRAMPOLINE_32BIT_CODE_OFFSET(%rax), %rax
	pushq	%rax
	lretq
trampoline_return:
	/* Restore the stack, the 32-bit trampoline uses its own stack */
	leaq	boot_stack_end(%rbx), %rsp

	/*
	 * cleanup_trampoline() would restore trampoline memory.
	 *
	 * RDI is address of the page table to use instead of page table
	 * in trampoline memory (if required).
	 *
	 * RSI holds real mode data and needs to be preserved across
	 * this function call.
	 */
	pushq	%rsi
	leaq	top_pgtable(%rbx), %rdi
	call	cleanup_trampoline
	popq	%rsi

	/* Zero EFLAGS */
	pushq	$0
	popfq

	/*
	 * Previously we've adjusted the GOT with address the binary was
	 * loaded at. Now we need to re-adjust for relocation address.
	 *
	 * Calculate the address the binary is loaded at, so that we can
	 * undo the previous GOT adjustment.
	 */
	call	1f
1:	popq	%rax
	subq	$1b, %rax

	/* The new adjustment is the relocation address */
	movq	%rbx, %rdi
	call	adjust_got

/*
 * Copy the compressed kernel to the end of our buffer
 * where decompression in place becomes safe.
 */
	pushq	%rsi
	leaq	(_bss-8)(%rip), %rsi
	leaq	(_bss-8)(%rbx), %rdi
	movq	$_bss /* - $startup_32 */, %rcx
	shrq	$3, %rcx
	std
	rep	movsq
	cld
	popq	%rsi

/*
 * Jump to the relocated address.
 */
	leaq	relocated(%rbx), %rax
	jmp	*%rax

#ifdef CONFIG_EFI_STUB

/* The entry point for the PE/COFF executable is efi_pe_entry. */
ENTRY(efi_pe_entry)
	movq	%rcx, efi64_config(%rip)	/* Handle */
	movq	%rdx, efi64_config+8(%rip) /* EFI System table pointer */

	leaq	efi64_config(%rip), %rax
	movq	%rax, efi_config(%rip)

	call	1f
1:	popq	%rbp
	subq	$1b, %rbp

	/*
	 * Relocate efi_config->call().
	 */
	addq	%rbp, efi64_config+40(%rip)

	movq	%rax, %rdi
	call	make_boot_params
	cmpq	$0,%rax
	je	fail
	mov	%rax, %rsi
	leaq	startup_32(%rip), %rax
	movl	%eax, BP_code32_start(%rsi)
	jmp	2f		/* Skip the relocation */

handover_entry:
	call	1f
1:	popq	%rbp
	subq	$1b, %rbp

	/*
	 * Relocate efi_config->call().
	 */
	movq	efi_config(%rip), %rax
	addq	%rbp, 40(%rax)
2:
	movq	efi_config(%rip), %rdi
	call	efi_main
	movq	%rax,%rsi
	cmpq	$0,%rax
	jne	2f
fail:
	/* EFI init failed, so hang. */
	hlt
	jmp	fail
2:
	movl	BP_code32_start(%esi), %eax
	leaq	startup_64(%rax), %rax
	jmp	*%rax
ENDPROC(efi_pe_entry)

	.org 0x390
ENTRY(efi64_stub_entry)
	movq	%rdi, efi64_config(%rip)	/* Handle */
	movq	%rsi, efi64_config+8(%rip) /* EFI System table pointer */

	leaq	efi64_config(%rip), %rax
	movq	%rax, efi_config(%rip)

	movq	%rdx, %rsi
	jmp	handover_entry
ENDPROC(efi64_stub_entry)
#endif

	.text
relocated:

/*
 * Clear BSS (stack is currently empty)
 */
	xorl	%eax, %eax
	leaq    _bss(%rip), %rdi
	leaq    _ebss(%rip), %rcx
	subq	%rdi, %rcx
	shrq	$3, %rcx
	rep	stosq

/*
 * Do the extraction, and jump to the new kernel..
 */
	pushq	%rsi			/* Save the real mode argument */
	movq	%rsi, %rdi		/* real mode address */
	leaq	boot_heap(%rip), %rsi	/* malloc area for uncompression */
	leaq	input_data(%rip), %rdx  /* input_data */
	movl	$z_input_len, %ecx	/* input_len */
	movq	%rbp, %r8		/* output target address */
	movq	$z_output_len, %r9	/* decompressed length, end of relocs */
	call	extract_kernel		/* returns kernel location in %rax */
	popq	%rsi

/*
 * Jump to the decompressed kernel.
 */
	jmp	*%rax

/*
 * Adjust the global offset table
 *
 * RAX is the previous adjustment of the table to undo (use 0 if it's the
 * first time we touch GOT).
 * RDI is the new adjustment to apply.
 */
adjust_got:
	/* Walk through the GOT adding the address to the entries */
	leaq	_got(%rip), %rdx
	leaq	_egot(%rip), %rcx
1:
	cmpq	%rcx, %rdx
	jae	2f
	subq	%rax, (%rdx)	/* Undo previous adjustment */
	addq	%rdi, (%rdx)	/* Apply the new adjustment */
	addq	$8, %rdx
	jmp	1b
2:
	ret

	.code32
/*
 * This is the 32-bit trampoline that will be copied over to low memory.
 *
 * RDI contains the return address (might be above 4G).
 * ECX contains the base address of the trampoline memory.
 * Non zero RDX means trampoline needs to enable 5-level paging.
 */
ENTRY(trampoline_32bit_src)
	/* Set up data and stack segments */
	movl	$__KERNEL_DS, %eax
	movl	%eax, %ds
	movl	%eax, %ss

	/* Set up new stack */
	leal	TRAMPOLINE_32BIT_STACK_END(%ecx), %esp

	/* Disable paging */
	movl	%cr0, %eax
	btrl	$X86_CR0_PG_BIT, %eax
	movl	%eax, %cr0

	/* Check what paging mode we want to be in after the trampoline */
	cmpl	$0, %edx
	jz	1f

	/* We want 5-level paging: don't touch CR3 if it already points to 5-level page tables */
	movl	%cr4, %eax
	testl	$X86_CR4_LA57, %eax
	jnz	3f
	jmp	2f
1:
	/* We want 4-level paging: don't touch CR3 if it already points to 4-level page tables */
	movl	%cr4, %eax
	testl	$X86_CR4_LA57, %eax
	jz	3f
2:
	/* Point CR3 to the trampoline's new top level page table */
	leal	TRAMPOLINE_32BIT_PGTABLE_OFFSET(%ecx), %eax
	movl	%eax, %cr3
3:
	/* Set EFER.LME=1 as a precaution in case hypervsior pulls the rug */
	pushl	%ecx
	pushl	%edx
	movl	$MSR_EFER, %ecx
	rdmsr
	btsl	$_EFER_LME, %eax
	wrmsr
	popl	%edx
	popl	%ecx

	/* Enable PAE and LA57 (if required) paging modes */
	movl	$X86_CR4_PAE, %eax
	cmpl	$0, %edx
	jz	1f
	orl	$X86_CR4_LA57, %eax
1:
	movl	%eax, %cr4

	/* Calculate address of paging_enabled() once we are executing in the trampoline */
	leal	paging_enabled - trampoline_32bit_src + TRAMPOLINE_32BIT_CODE_OFFSET(%ecx), %eax

	/* Prepare the stack for far return to Long Mode */
	pushl	$__KERNEL_CS
	pushl	%eax

	/* Enable paging again */
	movl	$(X86_CR0_PG | X86_CR0_PE), %eax
	movl	%eax, %cr0

	lret

	.code64
paging_enabled:
	/* Return from the trampoline */
	jmp	*%rdi

	/*
         * The trampoline code has a size limit.
         * Make sure we fail to compile if the trampoline code grows
         * beyond TRAMPOLINE_32BIT_CODE_SIZE bytes.
	 */
	.org	trampoline_32bit_src + TRAMPOLINE_32BIT_CODE_SIZE

	.code32
no_longmode:
	/* This isn't an x86-64 CPU, so hang intentionally, we cannot continue */
1:
	hlt
	jmp     1b

#include "../../kernel/verify_cpu.S"

	.data
gdt64:
	.word	gdt_end - gdt
	.quad   0
	.balign	8
gdt:
	.word	gdt_end - gdt
	.long	gdt
	.word	0
	.quad	0x00cf9a000000ffff	/* __KERNEL32_CS */
	.quad	0x00af9a000000ffff	/* __KERNEL_CS */
	.quad	0x00cf92000000ffff	/* __KERNEL_DS */
	.quad	0x0080890000000000	/* TS descriptor */
	.quad   0x0000000000000000	/* TS continued */
gdt_end:

#ifdef CONFIG_EFI_STUB
efi_config:
	.quad	0

#ifdef CONFIG_EFI_MIXED
	.global efi32_config
efi32_config:
	.fill	5,8,0
	.quad	efi64_thunk
	.byte	0
#endif

	.global efi64_config
efi64_config:
	.fill	5,8,0
	.quad	efi_call
	.byte	1
#endif /* CONFIG_EFI_STUB */

/*
 * Stack and heap for uncompression
 */
	.bss
	.balign 4
boot_heap:
	.fill BOOT_HEAP_SIZE, 1, 0
boot_stack:
	.fill BOOT_STACK_SIZE, 1, 0
boot_stack_end:

/*
 * Space for page tables (not in .bss so not zeroed)
 */
	.section ".pgtable","a",@nobits
	.balign 4096
pgtable:
	.fill BOOT_PGT_SIZE, 1, 0

/*
 * The page table is going to be used instead of page table in the trampoline
 * memory.
 */
top_pgtable:
	.fill PAGE_SIZE, 1, 0