File:  [Qemu by Fabrice Bellard] / qemu / tests / runcom.c
Revision 1.1.1.4 (vendor branch): download - view: text, annotated - select for diffs
Tue Apr 24 18:35:04 2018 UTC (3 years, 3 months ago) by root
Branches: qemu, MAIN
CVS tags: qemu1001, qemu1000, qemu0151, qemu0150, qemu0141, qemu0140, HEAD
qemu 0.14.0

    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: extern int vm86 (unsigned long int subfunction,
   17: 		 struct vm86plus_struct *info);
   18: 
   19: #define VIF_MASK                0x00080000
   20: 
   21: //#define SIGTEST
   22: 
   23: #define COM_BASE_ADDR    0x10100
   24: 
   25: static void usage(void)
   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: {
   51:     fprintf(stderr,
   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];
   80: 
   81:     vm86_mem = mmap((void *)0x00000000, 0x110000,
   82:                     PROT_WRITE | PROT_READ | PROT_EXEC,
   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;
  125:     r->eflags = VIF_MASK;
  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 $0x21 */
  132:     *seg_to_linear(r->cs, 3) = 0x21;
  133:     pushw(&ctx.regs, 0x0000);
  134: 
  135:     /* the value of these registers seem to be assumed by pi_10.com */
  136:     r->esi = 0x100;
  137:     r->ecx = 0xff;
  138:     r->ebp = 0x0900;
  139:     r->edi = 0xfffe;
  140: 
  141:     for(;;) {
  142:         ret = vm86(VM86_ENTER, &ctx);
  143:         switch(VM86_TYPE(ret)) {
  144:         case VM86_INTx:
  145:             {
  146:                 int int_num, ah;
  147: 
  148:                 int_num = VM86_ARG(ret);
  149:                 if (int_num != 0x21)
  150:                     goto unknown_int;
  151:                 ah = (r->eax >> 8) & 0xff;
  152:                 switch(ah) {
  153:                 case 0x00: /* exit */
  154:                     exit(0);
  155:                 case 0x02: /* write char */
  156:                     {
  157:                         uint8_t c = r->edx;
  158:                         write(1, &c, 1);
  159:                     }
  160:                     break;
  161:                 case 0x09: /* write string */
  162:                     {
  163:                         uint8_t c;
  164:                         for(;;) {
  165:                             c = *seg_to_linear(r->ds, r->edx);
  166:                             if (c == '$')
  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: }

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