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
|
/*-
* Copyright (c) 1997 Jonathan Lemon
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* $FreeBSD$
*/
/*
* Functions for calling x86 BIOS functions from the BSD kernel
*/
#include <machine/asmacros.h>
#include "assym.s"
.data
ALIGN_DATA
bioscall_frame: .long 0
bioscall_stack: .long 0
.text
/*
* bios32(regs, offset, segment)
* struct bios_regs *regs;
* u_int offset;
* u_short segment;
*/
ENTRY(bios32)
pushl %ebp
movl 16(%esp),%ebp
mov %bp,bioscall_vector+4
movl 12(%esp),%ebp
movl %ebp,bioscall_vector
movl 8(%esp),%ebp
pushl %ebx
pushl %esi
pushl %edi
movl 0(%ebp),%eax
movl 4(%ebp),%ebx
movl 8(%ebp),%ecx
movl 12(%ebp),%edx
movl 16(%ebp),%esi
movl 20(%ebp),%edi
pushl %ebp
lcall *bioscall_vector
popl %ebp
movl %eax,0(%ebp)
movl %ebx,4(%ebp)
movl %ecx,8(%ebp)
movl %edx,12(%ebp)
movl %esi,16(%ebp)
movl %edi,20(%ebp)
movl $0,%eax /* presume success */
jnc 1f
movl $1,%eax /* nope */
1:
popl %edi
popl %esi
popl %ebx
popl %ebp
ret
/*
* bios16_call(regs, stack)
* struct bios_regs *regs;
* char *stack;
*/
ENTRY(bios16_call)
pushl %ebp
movl %esp,%ebp
addl $4,%ebp /* frame pointer */
movl %ebp,bioscall_frame /* ... save it */
pushl %ebx
pushl %esi
pushl %edi
/*
* the problem with a full 32-bit stack segment is that 16-bit code
* tends to do a pushf, which only pushes %sp, not %esp. This value
* is then popped off (into %esp) which causes a page fault because
* it is the wrong address.
*
* the reverse problem happens for 16-bit stack addresses; the kernel
* code attempts to get the address of something on the stack, and the
* value returned is the address relative to %ss, not %ds.
*
* we fix this by installing a temporary stack at page 0, so the
* addresses are always valid in both 32 bit and 16 bit modes.
*/
movl %esp,bioscall_stack /* save current stack location */
movl 8(%ebp),%esp /* switch to page 0 stack */
movl 4(%ebp),%ebp /* regs */
movl 0(%ebp),%eax
movl 4(%ebp),%ebx
movl 8(%ebp),%ecx
movl 12(%ebp),%edx
movl 16(%ebp),%esi
movl 20(%ebp),%edi
pushl $BC32SEL
leal CNAME(bios16_jmp),%ebp
andl $PAGE_MASK,%ebp
pushl %ebp /* reload %cs and */
lret /* ...continue below */
.globl CNAME(bios16_jmp)
CNAME(bios16_jmp):
lcallw *bioscall_vector /* 16-bit call */
jc 1f
pushl $0 /* success */
jmp 2f
1:
pushl $1 /* failure */
2:
movl bioscall_frame,%ebp
movl 4(%ebp),%ebp /* regs */
movl %eax,0(%ebp)
movl %ebx,4(%ebp)
movl %ecx,8(%ebp)
movl %edx,12(%ebp)
movl %esi,16(%ebp)
movl %edi,20(%ebp)
popl %eax /* recover return value */
movl bioscall_stack,%esp /* return to normal stack */
popl %edi
popl %esi
popl %ebx
popl %ebp
movl (%esp),%ecx
pushl %ecx /* return address */
movl $KCSEL,4(%esp)
lret /* reload %cs on the way out */
|
