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Commit | Line | Data |
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62296fe3 FB |
1 | /* |
2 | * Simple example of use of vm86: launch a basic .com DOS executable | |
3 | */ | |
4 | #include <stdlib.h> | |
5 | #include <stdio.h> | |
7fb9a24e | 6 | #include <string.h> |
62296fe3 FB |
7 | #include <inttypes.h> |
8 | #include <unistd.h> | |
9 | #include <fcntl.h> | |
10 | #include <sys/mman.h> | |
11 | #include <signal.h> | |
12 | ||
13 | #include <linux/unistd.h> | |
14 | #include <asm/vm86.h> | |
15 | ||
e311248b PB |
16 | extern int vm86 (unsigned long int subfunction, |
17 | struct vm86plus_struct *info); | |
62296fe3 | 18 | |
e311248b | 19 | #define VIF_MASK 0x00080000 |
7fb9a24e | 20 | |
e311248b | 21 | //#define SIGTEST |
62296fe3 FB |
22 | |
23 | #define COM_BASE_ADDR 0x10100 | |
24 | ||
051eb6c1 | 25 | static void usage(void) |
62296fe3 FB |
26 | { |
27 | printf("runcom version 0.1 (c) 2003 Fabrice Bellard\n" | |
28 | "usage: runcom file.com\n" | |
29 | "VM86 Run simple .com DOS executables (linux vm86 test mode)\n"); | |
30 | exit(1); | |
31 | } | |
32 | ||
33 | static inline void set_bit(uint8_t *a, unsigned int bit) | |
34 | { | |
35 | a[bit / 8] |= (1 << (bit % 8)); | |
36 | } | |
37 | ||
38 | static inline uint8_t *seg_to_linear(unsigned int seg, unsigned int reg) | |
39 | { | |
40 | return (uint8_t *)((seg << 4) + (reg & 0xffff)); | |
41 | } | |
42 | ||
43 | static inline void pushw(struct vm86_regs *r, int val) | |
44 | { | |
45 | r->esp = (r->esp & ~0xffff) | ((r->esp - 2) & 0xffff); | |
46 | *(uint16_t *)seg_to_linear(r->ss, r->esp) = val; | |
47 | } | |
48 | ||
49 | void dump_regs(struct vm86_regs *r) | |
50 | { | |
5fafdf24 | 51 | fprintf(stderr, |
62296fe3 FB |
52 | "EAX=%08lx EBX=%08lx ECX=%08lx EDX=%08lx\n" |
53 | "ESI=%08lx EDI=%08lx EBP=%08lx ESP=%08lx\n" | |
54 | "EIP=%08lx EFL=%08lx\n" | |
55 | "CS=%04x DS=%04x ES=%04x SS=%04x FS=%04x GS=%04x\n", | |
56 | r->eax, r->ebx, r->ecx, r->edx, r->esi, r->edi, r->ebp, r->esp, | |
57 | r->eip, r->eflags, | |
58 | r->cs, r->ds, r->es, r->ss, r->fs, r->gs); | |
59 | } | |
60 | ||
61 | #ifdef SIGTEST | |
62 | void alarm_handler(int sig) | |
63 | { | |
64 | fprintf(stderr, "alarm signal=%d\n", sig); | |
65 | alarm(1); | |
66 | } | |
67 | #endif | |
68 | ||
69 | int main(int argc, char **argv) | |
70 | { | |
71 | uint8_t *vm86_mem; | |
72 | const char *filename; | |
73 | int fd, ret, seg; | |
74 | struct vm86plus_struct ctx; | |
75 | struct vm86_regs *r; | |
76 | ||
77 | if (argc != 2) | |
78 | usage(); | |
79 | filename = argv[1]; | |
3b46e624 | 80 | |
5fafdf24 TS |
81 | vm86_mem = mmap((void *)0x00000000, 0x110000, |
82 | PROT_WRITE | PROT_READ | PROT_EXEC, | |
62296fe3 FB |
83 | MAP_FIXED | MAP_ANON | MAP_PRIVATE, -1, 0); |
84 | if (vm86_mem == MAP_FAILED) { | |
85 | perror("mmap"); | |
86 | exit(1); | |
87 | } | |
88 | #ifdef SIGTEST | |
89 | { | |
90 | struct sigaction act; | |
91 | ||
92 | act.sa_handler = alarm_handler; | |
93 | sigemptyset(&act.sa_mask); | |
94 | act.sa_flags = 0; | |
95 | sigaction(SIGALRM, &act, NULL); | |
96 | alarm(1); | |
97 | } | |
98 | #endif | |
99 | ||
100 | /* load the MSDOS .com executable */ | |
101 | fd = open(filename, O_RDONLY); | |
102 | if (fd < 0) { | |
103 | perror(filename); | |
104 | exit(1); | |
105 | } | |
106 | ret = read(fd, vm86_mem + COM_BASE_ADDR, 65536 - 256); | |
107 | if (ret < 0) { | |
108 | perror("read"); | |
109 | exit(1); | |
110 | } | |
111 | close(fd); | |
112 | ||
113 | memset(&ctx, 0, sizeof(ctx)); | |
114 | /* init basic registers */ | |
115 | r = &ctx.regs; | |
116 | r->eip = 0x100; | |
117 | r->esp = 0xfffe; | |
118 | seg = (COM_BASE_ADDR - 0x100) >> 4; | |
119 | r->cs = seg; | |
120 | r->ss = seg; | |
121 | r->ds = seg; | |
122 | r->es = seg; | |
123 | r->fs = seg; | |
124 | r->gs = seg; | |
b8bf3e3a | 125 | r->eflags = VIF_MASK; |
62296fe3 FB |
126 | |
127 | /* put return code */ | |
128 | set_bit((uint8_t *)&ctx.int_revectored, 0x21); | |
129 | *seg_to_linear(r->cs, 0) = 0xb4; /* mov ah, $0 */ | |
130 | *seg_to_linear(r->cs, 1) = 0x00; | |
131 | *seg_to_linear(r->cs, 2) = 0xcd; /* int $0x21 */ | |
132 | *seg_to_linear(r->cs, 3) = 0x21; | |
133 | pushw(&ctx.regs, 0x0000); | |
134 | ||
135 | /* the value of these registers seem to be assumed by pi_10.com */ | |
136 | r->esi = 0x100; | |
137 | r->ecx = 0xff; | |
138 | r->ebp = 0x0900; | |
139 | r->edi = 0xfffe; | |
140 | ||
141 | for(;;) { | |
142 | ret = vm86(VM86_ENTER, &ctx); | |
143 | switch(VM86_TYPE(ret)) { | |
144 | case VM86_INTx: | |
145 | { | |
146 | int int_num, ah; | |
3b46e624 | 147 | |
62296fe3 FB |
148 | int_num = VM86_ARG(ret); |
149 | if (int_num != 0x21) | |
150 | goto unknown_int; | |
151 | ah = (r->eax >> 8) & 0xff; | |
152 | switch(ah) { | |
153 | case 0x00: /* exit */ | |
154 | exit(0); | |
155 | case 0x02: /* write char */ | |
156 | { | |
157 | uint8_t c = r->edx; | |
158 | write(1, &c, 1); | |
159 | } | |
160 | break; | |
161 | case 0x09: /* write string */ | |
162 | { | |
163 | uint8_t c; | |
164 | for(;;) { | |
165 | c = *seg_to_linear(r->ds, r->edx); | |
166 | if (c == '$') | |
167 | break; | |
168 | write(1, &c, 1); | |
169 | } | |
170 | r->eax = (r->eax & ~0xff) | '$'; | |
171 | } | |
172 | break; | |
173 | default: | |
174 | unknown_int: | |
175 | fprintf(stderr, "unsupported int 0x%02x\n", int_num); | |
176 | dump_regs(&ctx.regs); | |
177 | // exit(1); | |
178 | } | |
179 | } | |
180 | break; | |
181 | case VM86_SIGNAL: | |
182 | /* a signal came, we just ignore that */ | |
183 | break; | |
184 | case VM86_STI: | |
185 | break; | |
186 | default: | |
187 | fprintf(stderr, "unhandled vm86 return code (0x%x)\n", ret); | |
188 | dump_regs(&ctx.regs); | |
189 | exit(1); | |
190 | } | |
191 | } | |
192 | } |