bellard | 62296fe | 2003-03-30 21:41:51 +0000 | [diff] [blame] | 1 | /* |
| 2 | * Simple example of use of vm86: launch a basic .com DOS executable |
| 3 | */ |
| 4 | #include <stdlib.h> |
| 5 | #include <stdio.h> |
bellard | 7fb9a24 | 2003-04-11 00:13:04 +0000 | [diff] [blame] | 6 | #include <string.h> |
bellard | 62296fe | 2003-03-30 21:41:51 +0000 | [diff] [blame] | 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 | |
Paolo Bonzini | e311248 | 2010-10-21 10:18:38 +0200 | [diff] [blame] | 16 | extern int vm86 (unsigned long int subfunction, |
| 17 | struct vm86plus_struct *info); |
| 18 | |
| 19 | #define VIF_MASK 0x00080000 |
| 20 | |
bellard | 62296fe | 2003-03-30 21:41:51 +0000 | [diff] [blame] | 21 | //#define SIGTEST |
| 22 | |
bellard | 62296fe | 2003-03-30 21:41:51 +0000 | [diff] [blame] | 23 | #define COM_BASE_ADDR 0x10100 |
| 24 | |
Stefan Weil | 051eb6c | 2010-05-06 22:17:54 +0200 | [diff] [blame] | 25 | static void usage(void) |
bellard | 62296fe | 2003-03-30 21:41:51 +0000 | [diff] [blame] | 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 | { |
ths | 5fafdf2 | 2007-09-16 21:08:06 +0000 | [diff] [blame] | 51 | fprintf(stderr, |
bellard | 62296fe | 2003-03-30 21:41:51 +0000 | [diff] [blame] | 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]; |
ths | 3b46e62 | 2007-09-17 08:09:54 +0000 | [diff] [blame] | 80 | |
ths | 5fafdf2 | 2007-09-16 21:08:06 +0000 | [diff] [blame] | 81 | vm86_mem = mmap((void *)0x00000000, 0x110000, |
| 82 | PROT_WRITE | PROT_READ | PROT_EXEC, |
bellard | 62296fe | 2003-03-30 21:41:51 +0000 | [diff] [blame] | 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; |
bellard | b8bf3e3 | 2003-05-10 21:39:42 +0000 | [diff] [blame] | 125 | r->eflags = VIF_MASK; |
bellard | 62296fe | 2003-03-30 21:41:51 +0000 | [diff] [blame] | 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 $0x21 */ |
| 132 | *seg_to_linear(r->cs, 3) = 0x21; |
| 133 | pushw(&ctx.regs, 0x0000); |
| 134 | |
| 135 | /* the value of these registers seem to be assumed by pi_10.com */ |
| 136 | r->esi = 0x100; |
| 137 | r->ecx = 0xff; |
| 138 | r->ebp = 0x0900; |
| 139 | r->edi = 0xfffe; |
| 140 | |
| 141 | for(;;) { |
| 142 | ret = vm86(VM86_ENTER, &ctx); |
| 143 | switch(VM86_TYPE(ret)) { |
| 144 | case VM86_INTx: |
| 145 | { |
| 146 | int int_num, ah; |
ths | 3b46e62 | 2007-09-17 08:09:54 +0000 | [diff] [blame] | 147 | |
bellard | 62296fe | 2003-03-30 21:41:51 +0000 | [diff] [blame] | 148 | int_num = VM86_ARG(ret); |
| 149 | if (int_num != 0x21) |
| 150 | goto unknown_int; |
| 151 | ah = (r->eax >> 8) & 0xff; |
| 152 | switch(ah) { |
| 153 | case 0x00: /* exit */ |
| 154 | exit(0); |
| 155 | case 0x02: /* write char */ |
| 156 | { |
| 157 | uint8_t c = r->edx; |
| 158 | write(1, &c, 1); |
| 159 | } |
| 160 | break; |
| 161 | case 0x09: /* write string */ |
| 162 | { |
| 163 | uint8_t c; |
| 164 | for(;;) { |
| 165 | c = *seg_to_linear(r->ds, r->edx); |
| 166 | if (c == '$') |
| 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 | } |