tests/qruncom.c

   1 /*
   2  * Example of use of user mode libqemu: launch a basic .com DOS
   3  * executable
   4  */
   5 #include <stdlib.h>
   6 #include <stdio.h>
   7 #include <string.h>
   8 #include <inttypes.h>
   9 #include <unistd.h>
  10 #include <fcntl.h>
  11 #include <sys/mman.h>
  12 #include <signal.h>
  13 #include <malloc.h>
  14
  15 #include "cpu.h"
  16
  17 //#define SIGTEST
  18
  19 int cpu_get_pic_interrupt(CPUState *env)
  20 {
  21     return -1;
  22 }
  23
  24 uint64_t cpu_get_tsc(CPUState *env)
  25 {
  26     return 0;
  27 }
  28
  29 static void set_gate(void *ptr, unsigned int type, unsigned int dpl,
  30                      unsigned long addr, unsigned int sel)
  31 {
  32     unsigned int e1, e2;
  33     e1 = (addr & 0xffff) | (sel << 16);
  34     e2 = (addr & 0xffff0000) | 0x8000 | (dpl << 13) | (type << 8);
  35     stl((uint8_t *)ptr, e1);
  36     stl((uint8_t *)ptr + 4, e2);
  37 }
  38
  39 uint64_t idt_table[256];
  40
  41 /* only dpl matters as we do only user space emulation */
  42 static void set_idt(int n, unsigned int dpl)
  43 {
  44     set_gate(idt_table + n, 0, dpl, 0, 0);
  45 }
  46
  47 void qemu_free(void *ptr)
  48 {
  49     free(ptr);
  50 }
  51
  52 void *qemu_malloc(size_t size)
  53 {
  54     return malloc(size);
  55 }
  56
  57 void *qemu_mallocz(size_t size)
  58 {
  59     void *ptr;
  60     ptr = qemu_malloc(size);
  61     if (!ptr)
  62         return NULL;
  63     memset(ptr, 0, size);
  64     return ptr;
  65 }
  66
  67 void *qemu_vmalloc(size_t size)
  68 {
  69     return memalign(4096, size);
  70 }
  71
  72 void qemu_vfree(void *ptr)
  73 {
  74     free(ptr);
  75 }
  76
  77 void qemu_printf(const char *fmt, ...)
  78 {
  79     va_list ap;
  80     va_start(ap, fmt);
  81     vprintf(fmt, ap);
  82     va_end(ap);
  83 }
  84
  85 /* XXX: this is a bug in helper2.c */
  86 int errno;
  87
  88 /**********************************************/
  89
  90 #define COM_BASE_ADDR    0x10100
  91
  92 static void usage(void)
  93 {
  94     printf("qruncom version 0.1 (c) 2003 Fabrice Bellard\n"
  95            "usage: qruncom file.com\n"
  96            "user mode libqemu demo: run simple .com DOS executables\n");
  97     exit(1);
  98 }
  99
 100 static inline uint8_t *seg_to_linear(unsigned int seg, unsigned int reg)
 101 {
 102     return (uint8_t *)((seg << 4) + (reg & 0xffff));
 103 }
 104
 105 static inline void pushw(CPUState *env, int val)
 106 {
 107     env->regs[R_ESP] = (env->regs[R_ESP] & ~0xffff) | ((env->regs[R_ESP] - 2) & 0xffff);
 108     *(uint16_t *)seg_to_linear(env->segs[R_SS].selector, env->regs[R_ESP]) = val;
 109 }
 110
 111 static void host_segv_handler(int host_signum, siginfo_t *info,
 112                               void *puc)
 113 {
 114     if (cpu_signal_handler(host_signum, info, puc)) {
 115         return;
 116     }
 117     abort();
 118 }
 119
 120 int main(int argc, char **argv)
 121 {
 122     uint8_t *vm86_mem;
 123     const char *filename;
 124     int fd, ret, seg;
 125     CPUState *env;
 126
 127     if (argc != 2)
 128         usage();
 129     filename = argv[1];
 130
 131     vm86_mem = mmap((void *)0x00000000, 0x110000,
 132                     PROT_WRITE | PROT_READ | PROT_EXEC,
 133                     MAP_FIXED | MAP_ANON | MAP_PRIVATE, -1, 0);
 134     if (vm86_mem == MAP_FAILED) {
 135         perror("mmap");
 136         exit(1);
 137     }
 138
 139     /* load the MSDOS .com executable */
 140     fd = open(filename, O_RDONLY);
 141     if (fd < 0) {
 142         perror(filename);
 143         exit(1);
 144     }
 145     ret = read(fd, vm86_mem + COM_BASE_ADDR, 65536 - 256);
 146     if (ret < 0) {
 147         perror("read");
 148         exit(1);
 149     }
 150     close(fd);
 151
 152     /* install exception handler for CPU emulator */
 153     {
 154         struct sigaction act;
 155
 156         sigfillset(&act.sa_mask);
 157         act.sa_flags = SA_SIGINFO;
 158         //        act.sa_flags |= SA_ONSTACK;
 159
 160         act.sa_sigaction = host_segv_handler;
 161         sigaction(SIGSEGV, &act, NULL);
 162         sigaction(SIGBUS, &act, NULL);
 163     }
 164
 165     //    cpu_set_log(CPU_LOG_TB_IN_ASM | CPU_LOG_TB_OUT_ASM | CPU_LOG_EXEC);
 166
 167     env = cpu_init("qemu32");
 168
 169     cpu_x86_set_cpl(env, 3);
 170
 171     env->cr[0] = CR0_PG_MASK | CR0_WP_MASK | CR0_PE_MASK;
 172     /* NOTE: hflags duplicates some of the virtual CPU state */
 173     env->hflags |= HF_PE_MASK | VM_MASK;
 174
 175     /* flags setup : we activate the IRQs by default as in user
 176        mode. We also activate the VM86 flag to run DOS code */
 177     env->eflags |= IF_MASK | VM_MASK;
 178
 179     /* init basic registers */
 180     env->eip = 0x100;
 181     env->regs[R_ESP] = 0xfffe;
 182     seg = (COM_BASE_ADDR - 0x100) >> 4;
 183
 184     cpu_x86_load_seg_cache(env, R_CS, seg,
 185                            (seg << 4), 0xffff, 0);
 186     cpu_x86_load_seg_cache(env, R_SS, seg,
 187                            (seg << 4), 0xffff, 0);
 188     cpu_x86_load_seg_cache(env, R_DS, seg,
 189                            (seg << 4), 0xffff, 0);
 190     cpu_x86_load_seg_cache(env, R_ES, seg,
 191                            (seg << 4), 0xffff, 0);
 192     cpu_x86_load_seg_cache(env, R_FS, seg,
 193                            (seg << 4), 0xffff, 0);
 194     cpu_x86_load_seg_cache(env, R_GS, seg,
 195                            (seg << 4), 0xffff, 0);
 196
 197     /* exception support */
 198     env->idt.base = (unsigned long)idt_table;
 199     env->idt.limit = sizeof(idt_table) - 1;
 200     set_idt(0, 0);
 201     set_idt(1, 0);
 202     set_idt(2, 0);
 203     set_idt(3, 3);
 204     set_idt(4, 3);
 205     set_idt(5, 3);
 206     set_idt(6, 0);
 207     set_idt(7, 0);
 208     set_idt(8, 0);
 209     set_idt(9, 0);
 210     set_idt(10, 0);
 211     set_idt(11, 0);
 212     set_idt(12, 0);
 213     set_idt(13, 0);
 214     set_idt(14, 0);
 215     set_idt(15, 0);
 216     set_idt(16, 0);
 217     set_idt(17, 0);
 218     set_idt(18, 0);
 219     set_idt(19, 0);
 220
 221     /* put return code */
 222     *seg_to_linear(env->segs[R_CS].selector, 0) = 0xb4; /* mov ah, $0 */
 223     *seg_to_linear(env->segs[R_CS].selector, 1) = 0x00;
 224     *seg_to_linear(env->segs[R_CS].selector, 2) = 0xcd; /* int $0x21 */
 225     *seg_to_linear(env->segs[R_CS].selector, 3) = 0x21;
 226     pushw(env, 0x0000);
 227
 228     /* the value of these registers seem to be assumed by pi_10.com */
 229     env->regs[R_ESI] = 0x100;
 230     env->regs[R_ECX] = 0xff;
 231     env->regs[R_EBP] = 0x0900;
 232     env->regs[R_EDI] = 0xfffe;
 233
 234     /* inform the emulator of the mmaped memory */
 235     page_set_flags(0x00000000, 0x110000,
 236                    PAGE_WRITE | PAGE_READ | PAGE_EXEC | PAGE_VALID);
 237
 238     for(;;) {
 239         ret = cpu_x86_exec(env);
 240         switch(ret) {
 241         case EXCP0D_GPF:
 242             {
 243                 int int_num, ah;
 244                 int_num = *(uint8_t *)(env->segs[R_CS].base + env->eip + 1);
 245                 if (int_num != 0x21)
 246                     goto unknown_int;
 247                 ah = (env->regs[R_EAX] >> 8) & 0xff;
 248                 switch(ah) {
 249                 case 0x00: /* exit */
 250                     exit(0);
 251                 case 0x02: /* write char */
 252                     {
 253                         uint8_t c = env->regs[R_EDX];
 254                         write(1, &c, 1);
 255                     }
 256                     break;
 257                 case 0x09: /* write string */
 258                     {
 259                         uint8_t c;
 260                         for(;;) {
 261                             c = *seg_to_linear(env->segs[R_DS].selector, env->regs[R_EAX]);
 262                             if (c == '$')
 263                                 break;
 264                             write(1, &c, 1);
 265                         }
 266                         env->regs[R_EAX] = (env->regs[R_EAX] & ~0xff) | '$';
 267                     }
 268                     break;
 269                 default:
 270                 unknown_int:
 271                     fprintf(stderr, "unsupported int 0x%02x\n", int_num);
 272                     cpu_dump_state(env, stderr, fprintf, 0);
 273                     //                    exit(1);
 274                 }
 275                 env->eip += 2;
 276             }
 277             break;
 278         default:
 279             fprintf(stderr, "unhandled cpu_exec return code (0x%x)\n", ret);
 280             cpu_dump_state(env, stderr, fprintf, 0);
 281             exit(1);
 282         }
 283     }
 284 }