File:  [Qemu by Fabrice Bellard] / qemu / tests / runcom.c
Revision 1.1.1.3 (vendor branch): download - view: text, annotated - select for diffs
Tue Apr 24 18:25:25 2018 UTC (3 years, 6 months ago) by root
Branches: qemu, MAIN
CVS tags: qemu0130, HEAD
qemu 0.13.0

    1: /*
    2:  * Simple example of use of vm86: launch a basic .com DOS executable
    3:  */
    4: #include <stdlib.h>
    5: #include <stdio.h>
    6: #include <string.h>
    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: 
   16: //#define SIGTEST
   17: 
   18: #undef __syscall_return
   19: #define __syscall_return(type, res) \
   20: do { \
   21: 	return (type) (res); \
   22: } while (0)
   23: 
   24: _syscall2(int, vm86, int, func, struct vm86plus_struct *, v86)
   25: 
   26: #define COM_BASE_ADDR    0x10100
   27: 
   28: static void usage(void)
   29: {
   30:     printf("runcom version 0.1 (c) 2003 Fabrice Bellard\n"
   31:            "usage: runcom file.com\n"
   32:            "VM86 Run simple .com DOS executables (linux vm86 test mode)\n");
   33:     exit(1);
   34: }
   35: 
   36: static inline void set_bit(uint8_t *a, unsigned int bit)
   37: {
   38:     a[bit / 8] |= (1 << (bit % 8));
   39: }
   40: 
   41: static inline uint8_t *seg_to_linear(unsigned int seg, unsigned int reg)
   42: {
   43:     return (uint8_t *)((seg << 4) + (reg & 0xffff));
   44: }
   45: 
   46: static inline void pushw(struct vm86_regs *r, int val)
   47: {
   48:     r->esp = (r->esp & ~0xffff) | ((r->esp - 2) & 0xffff);
   49:     *(uint16_t *)seg_to_linear(r->ss, r->esp) = val;
   50: }
   51: 
   52: void dump_regs(struct vm86_regs *r)
   53: {
   54:     fprintf(stderr,
   55:             "EAX=%08lx EBX=%08lx ECX=%08lx EDX=%08lx\n"
   56:             "ESI=%08lx EDI=%08lx EBP=%08lx ESP=%08lx\n"
   57:             "EIP=%08lx EFL=%08lx\n"
   58:             "CS=%04x DS=%04x ES=%04x SS=%04x FS=%04x GS=%04x\n",
   59:             r->eax, r->ebx, r->ecx, r->edx, r->esi, r->edi, r->ebp, r->esp,
   60:             r->eip, r->eflags,
   61:             r->cs, r->ds, r->es, r->ss, r->fs, r->gs);
   62: }
   63: 
   64: #ifdef SIGTEST
   65: void alarm_handler(int sig)
   66: {
   67:     fprintf(stderr, "alarm signal=%d\n", sig);
   68:     alarm(1);
   69: }
   70: #endif
   71: 
   72: int main(int argc, char **argv)
   73: {
   74:     uint8_t *vm86_mem;
   75:     const char *filename;
   76:     int fd, ret, seg;
   77:     struct vm86plus_struct ctx;
   78:     struct vm86_regs *r;
   79: 
   80:     if (argc != 2)
   81:         usage();
   82:     filename = argv[1];
   83: 
   84:     vm86_mem = mmap((void *)0x00000000, 0x110000,
   85:                     PROT_WRITE | PROT_READ | PROT_EXEC,
   86:                     MAP_FIXED | MAP_ANON | MAP_PRIVATE, -1, 0);
   87:     if (vm86_mem == MAP_FAILED) {
   88:         perror("mmap");
   89:         exit(1);
   90:     }
   91: #ifdef SIGTEST
   92:     {
   93:         struct sigaction act;
   94: 
   95:         act.sa_handler = alarm_handler;
   96:         sigemptyset(&act.sa_mask);
   97:         act.sa_flags = 0;
   98:         sigaction(SIGALRM, &act, NULL);
   99:         alarm(1);
  100:     }
  101: #endif
  102: 
  103:     /* load the MSDOS .com executable */
  104:     fd = open(filename, O_RDONLY);
  105:     if (fd < 0) {
  106:         perror(filename);
  107:         exit(1);
  108:     }
  109:     ret = read(fd, vm86_mem + COM_BASE_ADDR, 65536 - 256);
  110:     if (ret < 0) {
  111:         perror("read");
  112:         exit(1);
  113:     }
  114:     close(fd);
  115: 
  116:     memset(&ctx, 0, sizeof(ctx));
  117:     /* init basic registers */
  118:     r = &ctx.regs;
  119:     r->eip = 0x100;
  120:     r->esp = 0xfffe;
  121:     seg = (COM_BASE_ADDR - 0x100) >> 4;
  122:     r->cs = seg;
  123:     r->ss = seg;
  124:     r->ds = seg;
  125:     r->es = seg;
  126:     r->fs = seg;
  127:     r->gs = seg;
  128:     r->eflags = VIF_MASK;
  129: 
  130:     /* put return code */
  131:     set_bit((uint8_t *)&ctx.int_revectored, 0x21);
  132:     *seg_to_linear(r->cs, 0) = 0xb4; /* mov ah, $0 */
  133:     *seg_to_linear(r->cs, 1) = 0x00;
  134:     *seg_to_linear(r->cs, 2) = 0xcd; /* int $0x21 */
  135:     *seg_to_linear(r->cs, 3) = 0x21;
  136:     pushw(&ctx.regs, 0x0000);
  137: 
  138:     /* the value of these registers seem to be assumed by pi_10.com */
  139:     r->esi = 0x100;
  140:     r->ecx = 0xff;
  141:     r->ebp = 0x0900;
  142:     r->edi = 0xfffe;
  143: 
  144:     for(;;) {
  145:         ret = vm86(VM86_ENTER, &ctx);
  146:         switch(VM86_TYPE(ret)) {
  147:         case VM86_INTx:
  148:             {
  149:                 int int_num, ah;
  150: 
  151:                 int_num = VM86_ARG(ret);
  152:                 if (int_num != 0x21)
  153:                     goto unknown_int;
  154:                 ah = (r->eax >> 8) & 0xff;
  155:                 switch(ah) {
  156:                 case 0x00: /* exit */
  157:                     exit(0);
  158:                 case 0x02: /* write char */
  159:                     {
  160:                         uint8_t c = r->edx;
  161:                         write(1, &c, 1);
  162:                     }
  163:                     break;
  164:                 case 0x09: /* write string */
  165:                     {
  166:                         uint8_t c;
  167:                         for(;;) {
  168:                             c = *seg_to_linear(r->ds, r->edx);
  169:                             if (c == '$')
  170:                                 break;
  171:                             write(1, &c, 1);
  172:                         }
  173:                         r->eax = (r->eax & ~0xff) | '$';
  174:                     }
  175:                     break;
  176:                 default:
  177:                 unknown_int:
  178:                     fprintf(stderr, "unsupported int 0x%02x\n", int_num);
  179:                     dump_regs(&ctx.regs);
  180:                     //                    exit(1);
  181:                 }
  182:             }
  183:             break;
  184:         case VM86_SIGNAL:
  185:             /* a signal came, we just ignore that */
  186:             break;
  187:         case VM86_STI:
  188:             break;
  189:         default:
  190:             fprintf(stderr, "unhandled vm86 return code (0x%x)\n", ret);
  191:             dump_regs(&ctx.regs);
  192:             exit(1);
  193:         }
  194:     }
  195: }

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