summaryrefslogtreecommitdiffstats
path: root/arch/x86/kernel/acpi/realmode/wakeup.S
blob: ead21b6631175df124210113025f49f994186a98 (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
/*
 * ACPI wakeup real mode startup stub
 */
#include <asm/segment.h>
#include <asm/msr-index.h>
#include <asm/page_types.h>
#include <asm/pgtable_types.h>
#include <asm/processor-flags.h>
#include "wakeup.h"

	.code16
	.section ".jump", "ax"
	.globl	_start
_start:
	cli
	jmp	wakeup_code

/* This should match the structure in wakeup.h */
		.section ".header", "a"
		.globl	wakeup_header
wakeup_header:
video_mode:	.short	0	/* Video mode number */
pmode_return:	.byte	0x66, 0xea	/* ljmpl */
		.long	0	/* offset goes here */
		.short	__KERNEL_CS
pmode_cr0:	.long	0	/* Saved %cr0 */
pmode_cr3:	.long	0	/* Saved %cr3 */
pmode_cr4:	.long	0	/* Saved %cr4 */
pmode_efer:	.quad	0	/* Saved EFER */
pmode_gdt:	.quad	0
realmode_flags:	.long	0
real_magic:	.long	0
trampoline_segment:	.word 0
_pad1:		.byte	0
wakeup_jmp:	.byte	0xea	/* ljmpw */
wakeup_jmp_off:	.word	3f
wakeup_jmp_seg:	.word	0
wakeup_gdt:	.quad	0, 0, 0
signature:	.long	WAKEUP_HEADER_SIGNATURE

	.text
	.code16
wakeup_code:
	cld

	/* Apparently some dimwit BIOS programmers don't know how to
	   program a PM to RM transition, and we might end up here with
	   junk in the data segment descriptor registers.  The only way
	   to repair that is to go into PM and fix it ourselves... */
	movw	$16, %cx
	lgdtl	%cs:wakeup_gdt
	movl	%cr0, %eax
	orb	$X86_CR0_PE, %al
	movl	%eax, %cr0
	jmp	1f
1:	ljmpw	$8, $2f
2:
	movw	%cx, %ds
	movw	%cx, %es
	movw	%cx, %ss
	movw	%cx, %fs
	movw	%cx, %gs

	andb	$~X86_CR0_PE, %al
	movl	%eax, %cr0
	jmp	wakeup_jmp
3:
	/* Set up segments */
	movw	%cs, %ax
	movw	%ax, %ds
	movw	%ax, %es
	movw	%ax, %ss
	lidtl	wakeup_idt

	movl	$wakeup_stack_end, %esp

	/* Clear the EFLAGS */
	pushl	$0
	popfl

	/* Check header signature... */
	movl	signature, %eax
	cmpl	$WAKEUP_HEADER_SIGNATURE, %eax
	jne	bogus_real_magic

	/* Check we really have everything... */
	movl	end_signature, %eax
	cmpl	$WAKEUP_END_SIGNATURE, %eax
	jne	bogus_real_magic

	/* Call the C code */
	calll	main

	/* Do any other stuff... */

#ifndef CONFIG_64BIT
	/* This could also be done in C code... */
	movl	pmode_cr3, %eax
	movl	%eax, %cr3

	movl	pmode_cr4, %ecx
	jecxz	1f
	movl	%ecx, %cr4
1:
	movl	pmode_efer, %eax
	movl	pmode_efer + 4, %edx
	movl	%eax, %ecx
	orl	%edx, %ecx
	jz	1f
	movl	$MSR_EFER, %ecx
	wrmsr
1:

	lgdtl	pmode_gdt

	/* This really couldn't... */
	movl	pmode_cr0, %eax
	movl	%eax, %cr0
	jmp	pmode_return
#else
	pushw	$0
	pushw	trampoline_segment
	pushw	$0
	lret
#endif

bogus_real_magic:
1:
	hlt
	jmp	1b

	.data
	.balign	8

	/* This is the standard real-mode IDT */
wakeup_idt:
	.word	0xffff		/* limit */
	.long	0		/* address */
	.word	0

	.globl	HEAP, heap_end
HEAP:
	.long	wakeup_heap
heap_end:
	.long	wakeup_stack

	.bss
wakeup_heap:
	.space	2048
wakeup_stack:
	.space	2048
wakeup_stack_end:

	.section ".signature","a"
end_signature:
	.long	WAKEUP_END_SIGNATURE