main.c
6.1 KB
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
/*
* gemu main
*
* Copyright (c) 2003 Fabrice Bellard
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#include <stdlib.h>
#include <stdio.h>
#include <stdarg.h>
#include <string.h>
#include <errno.h>
#include <unistd.h>
#include "gemu.h"
#include "cpu-i386.h"
#define DEBUG_LOGFILE "/tmp/gemu.log"
FILE *logfile = NULL;
int loglevel;
unsigned long x86_stack_size;
unsigned long stktop;
void gemu_log(const char *fmt, ...)
{
va_list ap;
va_start(ap, fmt);
vfprintf(stderr, fmt, ap);
va_end(ap);
}
/***********************************************************/
/* CPUX86 core interface */
void cpu_x86_outb(int addr, int val)
{
fprintf(stderr, "outb: port=0x%04x, data=%02x\n", addr, val);
}
void cpu_x86_outw(int addr, int val)
{
fprintf(stderr, "outw: port=0x%04x, data=%04x\n", addr, val);
}
void cpu_x86_outl(int addr, int val)
{
fprintf(stderr, "outl: port=0x%04x, data=%08x\n", addr, val);
}
int cpu_x86_inb(int addr)
{
fprintf(stderr, "inb: port=0x%04x\n", addr);
return 0;
}
int cpu_x86_inw(int addr)
{
fprintf(stderr, "inw: port=0x%04x\n", addr);
return 0;
}
int cpu_x86_inl(int addr)
{
fprintf(stderr, "inl: port=0x%04x\n", addr);
return 0;
}
/* default linux values for the selectors */
#define __USER_CS (0x23)
#define __USER_DS (0x2B)
void write_dt(void *ptr, unsigned long addr, unsigned long limit,
int seg32_bit)
{
unsigned int e1, e2, limit_in_pages;
limit_in_pages = 0;
if (limit > 0xffff) {
limit = limit >> 12;
limit_in_pages = 1;
}
e1 = (addr << 16) | (limit & 0xffff);
e2 = ((addr >> 16) & 0xff) | (addr & 0xff000000) | (limit & 0x000f0000);
e2 |= limit_in_pages << 23; /* byte granularity */
e2 |= seg32_bit << 22; /* 32 bit segment */
stl((uint8_t *)ptr, e1);
stl((uint8_t *)ptr + 4, e2);
}
uint64_t gdt_table[6];
void usage(void)
{
printf("gemu version " GEMU_VERSION ", Copyright (c) 2003 Fabrice Bellard\n"
"usage: gemu [-d] program [arguments...]\n"
"Linux x86 emulator\n"
);
exit(1);
}
int main(int argc, char **argv)
{
const char *filename;
struct target_pt_regs regs1, *regs = ®s1;
struct image_info info1, *info = &info1;
CPUX86State *env;
int optind;
if (argc <= 1)
usage();
loglevel = 0;
optind = 1;
if (argv[optind] && !strcmp(argv[optind], "-d")) {
loglevel = 1;
optind++;
}
filename = argv[optind];
/* init debug */
if (loglevel) {
logfile = fopen(DEBUG_LOGFILE, "w");
if (!logfile) {
perror(DEBUG_LOGFILE);
exit(1);
}
setvbuf(logfile, NULL, _IOLBF, 0);
}
/* Zero out regs */
memset(regs, 0, sizeof(struct target_pt_regs));
/* Zero out image_info */
memset(info, 0, sizeof(struct image_info));
if(elf_exec(filename, argv+optind, environ, regs, info) != 0) {
printf("Error loading %s\n", filename);
exit(1);
}
if (loglevel) {
fprintf(logfile, "start_brk 0x%08lx\n" , info->start_brk);
fprintf(logfile, "end_code 0x%08lx\n" , info->end_code);
fprintf(logfile, "start_code 0x%08lx\n" , info->start_code);
fprintf(logfile, "end_data 0x%08lx\n" , info->end_data);
fprintf(logfile, "start_stack 0x%08lx\n" , info->start_stack);
fprintf(logfile, "brk 0x%08lx\n" , info->brk);
fprintf(logfile, "esp 0x%08lx\n" , regs->esp);
fprintf(logfile, "eip 0x%08lx\n" , regs->eip);
}
target_set_brk((char *)info->brk);
syscall_init();
env = cpu_x86_init();
/* linux register setup */
env->regs[R_EAX] = regs->eax;
env->regs[R_EBX] = regs->ebx;
env->regs[R_ECX] = regs->ecx;
env->regs[R_EDX] = regs->edx;
env->regs[R_ESI] = regs->esi;
env->regs[R_EDI] = regs->edi;
env->regs[R_EBP] = regs->ebp;
env->regs[R_ESP] = regs->esp;
env->eip = regs->eip;
/* linux segment setup */
env->gdt.base = (void *)gdt_table;
env->gdt.limit = sizeof(gdt_table) - 1;
write_dt(&gdt_table[__USER_CS >> 3], 0, 0xffffffff, 1);
write_dt(&gdt_table[__USER_DS >> 3], 0, 0xffffffff, 1);
cpu_x86_load_seg(env, R_CS, __USER_CS);
cpu_x86_load_seg(env, R_DS, __USER_DS);
cpu_x86_load_seg(env, R_ES, __USER_DS);
cpu_x86_load_seg(env, R_SS, __USER_DS);
cpu_x86_load_seg(env, R_FS, __USER_DS);
cpu_x86_load_seg(env, R_GS, __USER_DS);
for(;;) {
int err;
uint8_t *pc;
err = cpu_x86_exec(env);
pc = env->seg_cache[R_CS].base + env->eip;
switch(err) {
case EXCP0D_GPF:
if (pc[0] == 0xcd && pc[1] == 0x80) {
/* syscall */
env->eip += 2;
env->regs[R_EAX] = do_syscall(env,
env->regs[R_EAX],
env->regs[R_EBX],
env->regs[R_ECX],
env->regs[R_EDX],
env->regs[R_ESI],
env->regs[R_EDI],
env->regs[R_EBP]);
} else {
goto trap_error;
}
break;
default:
trap_error:
fprintf(stderr, "0x%08lx: Unknown exception %d, aborting\n",
(long)pc, err);
abort();
}
}
return 0;
}