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1.1 root 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:
14: #include "cpu.h"
15:
16: //#define SIGTEST
17:
18: CPUState *cpu_single_env = NULL;
19:
20: void cpu_outb(CPUState *env, int addr, int val)
21: {
22: fprintf(stderr, "outb: port=0x%04x, data=%02x\n", addr, val);
23: }
24:
25: void cpu_outw(CPUState *env, int addr, int val)
26: {
27: fprintf(stderr, "outw: port=0x%04x, data=%04x\n", addr, val);
28: }
29:
30: void cpu_outl(CPUState *env, int addr, int val)
31: {
32: fprintf(stderr, "outl: port=0x%04x, data=%08x\n", addr, val);
33: }
34:
35: int cpu_inb(CPUState *env, int addr)
36: {
37: fprintf(stderr, "inb: port=0x%04x\n", addr);
38: return 0;
39: }
40:
41: int cpu_inw(CPUState *env, int addr)
42: {
43: fprintf(stderr, "inw: port=0x%04x\n", addr);
44: return 0;
45: }
46:
47: int cpu_inl(CPUState *env, int addr)
48: {
49: fprintf(stderr, "inl: port=0x%04x\n", addr);
50: return 0;
51: }
52:
53: int cpu_get_pic_interrupt(CPUState *env)
54: {
55: return -1;
56: }
57:
58: uint64_t cpu_get_tsc(CPUState *env)
59: {
60: return 0;
61: }
62:
63: static void set_gate(void *ptr, unsigned int type, unsigned int dpl,
64: unsigned long addr, unsigned int sel)
65: {
66: unsigned int e1, e2;
67: e1 = (addr & 0xffff) | (sel << 16);
68: e2 = (addr & 0xffff0000) | 0x8000 | (dpl << 13) | (type << 8);
69: stl((uint8_t *)ptr, e1);
70: stl((uint8_t *)ptr + 4, e2);
71: }
72:
73: uint64_t idt_table[256];
74:
75: /* only dpl matters as we do only user space emulation */
76: static void set_idt(int n, unsigned int dpl)
77: {
78: set_gate(idt_table + n, 0, dpl, 0, 0);
79: }
80:
81: void qemu_free(void *ptr)
82: {
83: free(ptr);
84: }
85:
86: void *qemu_malloc(size_t size)
87: {
88: return malloc(size);
89: }
90:
91: void qemu_printf(const char *fmt, ...)
92: {
93: va_list ap;
94: va_start(ap, fmt);
95: vprintf(fmt, ap);
96: va_end(ap);
97: }
98:
99: /* XXX: this is a bug in helper2.c */
100: int errno;
101:
102: /**********************************************/
103:
104: #define COM_BASE_ADDR 0x10100
105:
106: void usage(void)
107: {
108: printf("qruncom version 0.1 (c) 2003 Fabrice Bellard\n"
109: "usage: qruncom file.com\n"
110: "user mode libqemu demo: run simple .com DOS executables\n");
111: exit(1);
112: }
113:
114: static inline uint8_t *seg_to_linear(unsigned int seg, unsigned int reg)
115: {
116: return (uint8_t *)((seg << 4) + (reg & 0xffff));
117: }
118:
119: static inline void pushw(CPUState *env, int val)
120: {
121: env->regs[R_ESP] = (env->regs[R_ESP] & ~0xffff) | ((env->regs[R_ESP] - 2) & 0xffff);
122: *(uint16_t *)seg_to_linear(env->segs[R_SS].selector, env->regs[R_ESP]) = val;
123: }
124:
125: static void host_segv_handler(int host_signum, siginfo_t *info,
126: void *puc)
127: {
128: if (cpu_signal_handler(host_signum, info, puc)) {
129: return;
130: }
131: abort();
132: }
133:
134: int main(int argc, char **argv)
135: {
136: uint8_t *vm86_mem;
137: const char *filename;
138: int fd, ret, seg;
139: CPUState *env;
140:
141: if (argc != 2)
142: usage();
143: filename = argv[1];
144:
145: vm86_mem = mmap((void *)0x00000000, 0x110000,
146: PROT_WRITE | PROT_READ | PROT_EXEC,
147: MAP_FIXED | MAP_ANON | MAP_PRIVATE, -1, 0);
148: if (vm86_mem == MAP_FAILED) {
149: perror("mmap");
150: exit(1);
151: }
152:
153: /* load the MSDOS .com executable */
154: fd = open(filename, O_RDONLY);
155: if (fd < 0) {
156: perror(filename);
157: exit(1);
158: }
159: ret = read(fd, vm86_mem + COM_BASE_ADDR, 65536 - 256);
160: if (ret < 0) {
161: perror("read");
162: exit(1);
163: }
164: close(fd);
165:
166: /* install exception handler for CPU emulator */
167: {
168: struct sigaction act;
169:
170: sigfillset(&act.sa_mask);
171: act.sa_flags = SA_SIGINFO;
172: // act.sa_flags |= SA_ONSTACK;
173:
174: act.sa_sigaction = host_segv_handler;
175: sigaction(SIGSEGV, &act, NULL);
176: sigaction(SIGBUS, &act, NULL);
177: #if defined (TARGET_I386) && defined(USE_CODE_COPY)
178: sigaction(SIGFPE, &act, NULL);
179: #endif
180: }
181:
182: // cpu_set_log(CPU_LOG_TB_IN_ASM | CPU_LOG_TB_OUT_ASM | CPU_LOG_EXEC);
183:
184: env = cpu_init();
185:
186: /* disable code copy to simplify debugging */
187: code_copy_enabled = 0;
188:
189: /* set user mode state (XXX: should be done automatically by
190: cpu_init ?) */
191: env->user_mode_only = 1;
192:
193: cpu_x86_set_cpl(env, 3);
194:
195: env->cr[0] = CR0_PG_MASK | CR0_WP_MASK | CR0_PE_MASK;
196: /* NOTE: hflags duplicates some of the virtual CPU state */
197: env->hflags |= HF_PE_MASK | VM_MASK;
198:
199: /* flags setup : we activate the IRQs by default as in user
200: mode. We also activate the VM86 flag to run DOS code */
201: env->eflags |= IF_MASK | VM_MASK;
202:
203: /* init basic registers */
204: env->eip = 0x100;
205: env->regs[R_ESP] = 0xfffe;
206: seg = (COM_BASE_ADDR - 0x100) >> 4;
207:
208: cpu_x86_load_seg_cache(env, R_CS, seg,
209: (uint8_t *)(seg << 4), 0xffff, 0);
210: cpu_x86_load_seg_cache(env, R_SS, seg,
211: (uint8_t *)(seg << 4), 0xffff, 0);
212: cpu_x86_load_seg_cache(env, R_DS, seg,
213: (uint8_t *)(seg << 4), 0xffff, 0);
214: cpu_x86_load_seg_cache(env, R_ES, seg,
215: (uint8_t *)(seg << 4), 0xffff, 0);
216: cpu_x86_load_seg_cache(env, R_FS, seg,
217: (uint8_t *)(seg << 4), 0xffff, 0);
218: cpu_x86_load_seg_cache(env, R_GS, seg,
219: (uint8_t *)(seg << 4), 0xffff, 0);
220:
221: /* exception support */
222: env->idt.base = (void *)idt_table;
223: env->idt.limit = sizeof(idt_table) - 1;
224: set_idt(0, 0);
225: set_idt(1, 0);
226: set_idt(2, 0);
227: set_idt(3, 3);
228: set_idt(4, 3);
229: set_idt(5, 3);
230: set_idt(6, 0);
231: set_idt(7, 0);
232: set_idt(8, 0);
233: set_idt(9, 0);
234: set_idt(10, 0);
235: set_idt(11, 0);
236: set_idt(12, 0);
237: set_idt(13, 0);
238: set_idt(14, 0);
239: set_idt(15, 0);
240: set_idt(16, 0);
241: set_idt(17, 0);
242: set_idt(18, 0);
243: set_idt(19, 0);
244:
245: /* put return code */
246: *seg_to_linear(env->segs[R_CS].selector, 0) = 0xb4; /* mov ah, $0 */
247: *seg_to_linear(env->segs[R_CS].selector, 1) = 0x00;
248: *seg_to_linear(env->segs[R_CS].selector, 2) = 0xcd; /* int $0x21 */
249: *seg_to_linear(env->segs[R_CS].selector, 3) = 0x21;
250: pushw(env, 0x0000);
251:
252: /* the value of these registers seem to be assumed by pi_10.com */
253: env->regs[R_ESI] = 0x100;
254: env->regs[R_ECX] = 0xff;
255: env->regs[R_EBP] = 0x0900;
256: env->regs[R_EDI] = 0xfffe;
257:
258: /* inform the emulator of the mmaped memory */
259: page_set_flags(0x00000000, 0x110000,
260: PAGE_WRITE | PAGE_READ | PAGE_EXEC | PAGE_VALID);
261:
262: for(;;) {
263: ret = cpu_x86_exec(env);
264: switch(ret) {
265: case EXCP0D_GPF:
266: {
267: int int_num, ah;
268: int_num = *(env->segs[R_CS].base + env->eip + 1);
269: if (int_num != 0x21)
270: goto unknown_int;
271: ah = (env->regs[R_EAX] >> 8) & 0xff;
272: switch(ah) {
273: case 0x00: /* exit */
274: exit(0);
275: case 0x02: /* write char */
276: {
277: uint8_t c = env->regs[R_EDX];
278: write(1, &c, 1);
279: }
280: break;
281: case 0x09: /* write string */
282: {
283: uint8_t c;
284: for(;;) {
285: c = *seg_to_linear(env->segs[R_DS].selector, env->regs[R_EAX]);
286: if (c == '$')
287: break;
288: write(1, &c, 1);
289: }
290: env->regs[R_EAX] = (env->regs[R_EAX] & ~0xff) | '$';
291: }
292: break;
293: default:
294: unknown_int:
295: fprintf(stderr, "unsupported int 0x%02x\n", int_num);
296: cpu_dump_state(env, stderr, 0);
297: // exit(1);
298: }
299: env->eip += 2;
300: }
301: break;
302: default:
303: fprintf(stderr, "unhandled cpu_exec return code (0x%x)\n", ret);
304: cpu_dump_state(env, stderr, 0);
305: exit(1);
306: }
307: }
308: }
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