LXR qemu/tests/tcg/runcom.c

   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
  16extern 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
  25static 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
  33static inline void set_bit(uint8_t *a, unsigned int bit)
  34{
  35    a[bit / 8] |= (1 << (bit % 8));
  36}
  37
  38static inline uint8_t *seg_to_linear(unsigned int seg, unsigned int reg)
  39{
  40    return (uint8_t *)((seg << 4) + (reg & 0xffff));
  41}
  42
  43static 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
  49void 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
  62void alarm_handler(int sig)
  63{
  64    fprintf(stderr, "alarm signal=%d\n", sig);
  65    alarm(1);
  66}
  67#endif
  68
  69int 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}
 193