summaryrefslogtreecommitdiffstats
path: root/arch/x86_64/kernel/relocate_kernel.S
blob: d24fa9b72a2bc8856a4d6adcf556d091f69594e0 (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
/*
 * relocate_kernel.S - put the kernel image in place to boot
 * Copyright (C) 2002-2005 Eric Biederman  <ebiederm@xmission.com>
 *
 * This source code is licensed under the GNU General Public License,
 * Version 2.  See the file COPYING for more details.
 */

#include <linux/linkage.h>

	/*
	 * Must be relocatable PIC code callable as a C function, that once
	 * it starts can not use the previous processes stack.
	 */
	.globl relocate_new_kernel
	.code64
relocate_new_kernel:
	/* %rdi page_list
	 * %rsi reboot_code_buffer
	 * %rdx start address
	 * %rcx page_table
	 * %r8  arg5
	 * %r9  arg6
	 */

	/* zero out flags, and disable interrupts */
	pushq $0
	popfq

	/* set a new stack at the bottom of our page... */
	lea   4096(%rsi), %rsp

	/* store the parameters back on the stack */
	pushq	%rdx /* store the start address */

	/* Set cr0 to a known state:
	 * 31 1 == Paging enabled
	 * 18 0 == Alignment check disabled
	 * 16 0 == Write protect disabled
	 * 3  0 == No task switch
	 * 2  0 == Don't do FP software emulation.
	 * 0  1 == Proctected mode enabled
	 */
	movq	%cr0, %rax
	andq	$~((1<<18)|(1<<16)|(1<<3)|(1<<2)), %rax
	orl	$((1<<31)|(1<<0)), %eax
	movq	%rax, %cr0

	/* Set cr4 to a known state:
	 * 10 0 == xmm exceptions disabled
	 * 9  0 == xmm registers instructions disabled
	 * 8  0 == performance monitoring counter disabled
	 * 7  0 == page global disabled
	 * 6  0 == machine check exceptions disabled
	 * 5  1 == physical address extension enabled
	 * 4  0 == page size extensions	disabled
	 * 3  0 == Debug extensions disabled
	 * 2  0 == Time stamp disable (disabled)
	 * 1  0 == Protected mode virtual interrupts disabled
	 * 0  0 == VME disabled
	 */

	movq	$((1<<5)), %rax
	movq	%rax, %cr4

	jmp 1f
1:

	/* Switch to the identity mapped page tables,
	 * and flush the TLB.
	*/
	movq	%rcx, %cr3

	/* Do the copies */
	movq	%rdi, %rcx 	/* Put the page_list in %rcx */
	xorq	%rdi, %rdi
	xorq	%rsi, %rsi
	jmp	1f

0:	/* top, read another word for the indirection page */

	movq	(%rbx), %rcx
	addq	$8,	%rbx
1:
	testq	$0x1,	%rcx  /* is it a destination page? */
	jz	2f
	movq	%rcx,	%rdi
	andq	$0xfffffffffffff000, %rdi
	jmp	0b
2:
	testq	$0x2,	%rcx  /* is it an indirection page? */
	jz	2f
	movq	%rcx,   %rbx
	andq	$0xfffffffffffff000, %rbx
	jmp	0b
2:
	testq	$0x4,	%rcx  /* is it the done indicator? */
	jz	2f
	jmp	3f
2:
	testq	$0x8,	%rcx  /* is it the source indicator? */
	jz	0b	      /* Ignore it otherwise */
	movq	%rcx,   %rsi  /* For ever source page do a copy */
	andq	$0xfffffffffffff000, %rsi

	movq	$512,   %rcx
	rep ; movsq
	jmp	0b
3:

	/* To be certain of avoiding problems with self-modifying code
	 * I need to execute a serializing instruction here.
	 * So I flush the TLB by reloading %cr3 here, it's handy,
	 * and not processor dependent.
	 */
	movq	%cr3, %rax
	movq	%rax, %cr3

	/* set all of the registers to known values */
	/* leave %rsp alone */

	xorq	%rax, %rax
	xorq	%rbx, %rbx
	xorq    %rcx, %rcx
	xorq    %rdx, %rdx
	xorq    %rsi, %rsi
	xorq    %rdi, %rdi
	xorq    %rbp, %rbp
	xorq	%r8,  %r8
	xorq	%r9,  %r9
	xorq	%r10, %r9
	xorq	%r11, %r11
	xorq	%r12, %r12
	xorq	%r13, %r13
	xorq	%r14, %r14
	xorq	%r15, %r15

	ret
relocate_new_kernel_end:

	.globl relocate_new_kernel_size
relocate_new_kernel_size:
	.quad relocate_new_kernel_end - relocate_new_kernel