1 /****************************************************************************
2 *
3 *                       Realmode X86 Emulator Library
4 *
5 *               Copyright (C) 1991-2004 SciTech Software, Inc.
6 *                    Copyright (C) David Mosberger-Tang
7 *                      Copyright (C) 1999 Egbert Eich
8 *
9 *  ========================================================================
10 *
11 *  Permission to use, copy, modify, distribute, and sell this software and
12 *  its documentation for any purpose is hereby granted without fee,
13 *  provided that the above copyright notice appear in all copies and that
14 *  both that copyright notice and this permission notice appear in
15 *  supporting documentation, and that the name of the authors not be used
16 *  in advertising or publicity pertaining to distribution of the software
17 *  without specific, written prior permission.  The authors makes no
18 *  representations about the suitability of this software for any purpose.
19 *  It is provided "as is" without express or implied warranty.
20 *
21 *  THE AUTHORS DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
22 *  INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
23 *  EVENT SHALL THE AUTHORS BE LIABLE FOR ANY SPECIAL, INDIRECT OR
24 *  CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF
25 *  USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
26 *  OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
27 *  PERFORMANCE OF THIS SOFTWARE.
28 *
29 *  ========================================================================
30 *
31 * Language:     ANSI C
32 * Environment:  Any
33 * Developer:    Kendall Bennett
34 *
35 * Description:  This file contains the code to handle debugging of the
36 *               emulator.
37 *
38 ****************************************************************************/
39 
40 #include <stdarg.h>
41 #include <common.h>
42 #include <linux/ctype.h>
43 #include "x86emu/x86emui.h"
44 
45 /*----------------------------- Implementation ----------------------------*/
46 
47 #ifdef DEBUG
48 
49 static void print_encoded_bytes(u16 s, u16 o);
50 static void print_decoded_instruction(void);
51 static int x86emu_parse_line(char *s, int *ps, int *n);
52 
53 /* should look something like debug's output. */
54 void X86EMU_trace_regs(void)
55 {
56 	if (DEBUG_TRACE()) {
57 		x86emu_dump_regs();
58 	}
59 	if (DEBUG_DECODE() && !DEBUG_DECODE_NOPRINT()) {
60 		printk("%04x:%04x ", M.x86.saved_cs, M.x86.saved_ip);
61 		print_encoded_bytes(M.x86.saved_cs, M.x86.saved_ip);
62 		print_decoded_instruction();
63 	}
64 }
65 
66 void X86EMU_trace_xregs(void)
67 {
68 	if (DEBUG_TRACE()) {
69 		x86emu_dump_xregs();
70 	}
71 }
72 
73 void x86emu_just_disassemble(void)
74 {
75 	/*
76 	 * This routine called if the flag DEBUG_DISASSEMBLE is set kind
77 	 * of a hack!
78 	 */
79 	printk("%04x:%04x ", M.x86.saved_cs, M.x86.saved_ip);
80 	print_encoded_bytes(M.x86.saved_cs, M.x86.saved_ip);
81 	print_decoded_instruction();
82 }
83 
84 static void disassemble_forward(u16 seg, u16 off, int n)
85 {
86 	X86EMU_sysEnv tregs;
87 	int i;
88 	u8 op1;
89 	/*
90 	 * hack, hack, hack.  What we do is use the exact machinery set up
91 	 * for execution, except that now there is an additional state
92 	 * flag associated with the "execution", and we are using a copy
93 	 * of the register struct.  All the major opcodes, once fully
94 	 * decoded, have the following two steps: TRACE_REGS(r,m);
95 	 * SINGLE_STEP(r,m); which disappear if DEBUG is not defined to
96 	 * the preprocessor.  The TRACE_REGS macro expands to:
97 	 *
98 	 * if (debug&DEBUG_DISASSEMBLE)
99 	 *     {just_disassemble(); goto EndOfInstruction;}
100 	 *     if (debug&DEBUG_TRACE) trace_regs(r,m);
101 	 *
102 	 * ......  and at the last line of the routine.
103 	 *
104 	 * EndOfInstruction: end_instr();
105 	 *
106 	 * Up to the point where TRACE_REG is expanded, NO modifications
107 	 * are done to any register EXCEPT the IP register, for fetch and
108 	 * decoding purposes.
109 	 *
110 	 * This was done for an entirely different reason, but makes a
111 	 * nice way to get the system to help debug codes.
112 	 */
113 	tregs = M;
114 	tregs.x86.R_IP = off;
115 	tregs.x86.R_CS = seg;
116 
117 	/* reset the decoding buffers */
118 	tregs.x86.enc_str_pos = 0;
119 	tregs.x86.enc_pos = 0;
120 
121 	/* turn on the "disassemble only, no execute" flag */
122 	tregs.x86.debug |= DEBUG_DISASSEMBLE_F;
123 
124 	/* DUMP NEXT n instructions to screen in straight_line fashion */
125 	/*
126 	 * This looks like the regular instruction fetch stream, except
127 	 * that when this occurs, each fetched opcode, upon seeing the
128 	 * DEBUG_DISASSEMBLE flag set, exits immediately after decoding
129 	 * the instruction.  XXX --- CHECK THAT MEM IS NOT AFFECTED!!!
130 	 * Note the use of a copy of the register structure...
131 	 */
132 	for (i = 0; i < n; i++) {
133 		op1 = (*sys_rdb) (((u32) M.x86.R_CS << 4) + (M.x86.R_IP++));
134 		(x86emu_optab[op1]) (op1);
135 	}
136 	/* end major hack mode. */
137 }
138 
139 void x86emu_check_ip_access(void)
140 {
141 	/* NULL as of now */
142 }
143 
144 void x86emu_check_sp_access(void)
145 {
146 }
147 
148 void x86emu_check_mem_access(u32 dummy)
149 {
150 	/*  check bounds, etc */
151 }
152 
153 void x86emu_check_data_access(uint dummy1, uint dummy2)
154 {
155 	/*  check bounds, etc */
156 }
157 
158 void x86emu_inc_decoded_inst_len(int x)
159 {
160 	M.x86.enc_pos += x;
161 }
162 
163 void x86emu_decode_printf(char *x)
164 {
165 	sprintf(M.x86.decoded_buf + M.x86.enc_str_pos, "%s", x);
166 	M.x86.enc_str_pos += strlen(x);
167 }
168 
169 void x86emu_decode_printf2(char *x, int y)
170 {
171 	char temp[100];
172 	sprintf(temp, x, y);
173 	sprintf(M.x86.decoded_buf + M.x86.enc_str_pos, "%s", temp);
174 	M.x86.enc_str_pos += strlen(temp);
175 }
176 
177 void x86emu_end_instr(void)
178 {
179 	M.x86.enc_str_pos = 0;
180 	M.x86.enc_pos = 0;
181 }
182 
183 static void print_encoded_bytes(u16 s, u16 o)
184 {
185 	int i;
186 	char buf1[64];
187 	for (i = 0; i < M.x86.enc_pos; i++) {
188 		sprintf(buf1 + 2 * i, "%02x", fetch_data_byte_abs(s, o + i));
189 	}
190 	printk("%-20s", buf1);
191 }
192 
193 static void print_decoded_instruction(void)
194 {
195 	printk("%s", M.x86.decoded_buf);
196 }
197 
198 void x86emu_print_int_vect(u16 iv)
199 {
200 	u16 seg, off;
201 
202 	if (iv > 256)
203 		return;
204 	seg = fetch_data_word_abs(0, iv * 4);
205 	off = fetch_data_word_abs(0, iv * 4 + 2);
206 	printk("%04x:%04x ", seg, off);
207 }
208 
209 void X86EMU_dump_memory(u16 seg, u16 off, u32 amt)
210 {
211 	u32 start = off & 0xfffffff0;
212 	u32 end = (off + 16) & 0xfffffff0;
213 	u32 i;
214 	u32 current;
215 
216 	current = start;
217 	while (end <= off + amt) {
218 		printk("%04x:%04x ", seg, start);
219 		for (i = start; i < off; i++)
220 			printk("   ");
221 		for (; i < end; i++)
222 			printk("%02x ", fetch_data_byte_abs(seg, i));
223 		printk("\n");
224 		start = end;
225 		end = start + 16;
226 	}
227 }
228 
229 void x86emu_single_step(void)
230 {
231 	char s[1024];
232 	int ps[10];
233 	int ntok;
234 	int cmd;
235 	int done;
236 	int segment;
237 	int offset;
238 	static int breakpoint;
239 	static int noDecode = 1;
240 
241 	char *p;
242 
243 	if (DEBUG_BREAK()) {
244 		if (M.x86.saved_ip != breakpoint) {
245 			return;
246 		} else {
247 			M.x86.debug &= ~DEBUG_DECODE_NOPRINT_F;
248 			M.x86.debug |= DEBUG_TRACE_F;
249 			M.x86.debug &= ~DEBUG_BREAK_F;
250 			print_decoded_instruction();
251 			X86EMU_trace_regs();
252 		}
253 	}
254 	done = 0;
255 	offset = M.x86.saved_ip;
256 	while (!done) {
257 		printk("-");
258 		cmd = x86emu_parse_line(s, ps, &ntok);
259 		switch (cmd) {
260 		case 'u':
261 			disassemble_forward(M.x86.saved_cs, (u16) offset, 10);
262 			break;
263 		case 'd':
264 			if (ntok == 2) {
265 				segment = M.x86.saved_cs;
266 				offset = ps[1];
267 				X86EMU_dump_memory(segment, (u16) offset, 16);
268 				offset += 16;
269 			} else if (ntok == 3) {
270 				segment = ps[1];
271 				offset = ps[2];
272 				X86EMU_dump_memory(segment, (u16) offset, 16);
273 				offset += 16;
274 			} else {
275 				segment = M.x86.saved_cs;
276 				X86EMU_dump_memory(segment, (u16) offset, 16);
277 				offset += 16;
278 			}
279 			break;
280 		case 'c':
281 			M.x86.debug ^= DEBUG_TRACECALL_F;
282 			break;
283 		case 's':
284 			M.x86.debug ^=
285 			    DEBUG_SVC_F | DEBUG_SYS_F | DEBUG_SYSINT_F;
286 			break;
287 		case 'r':
288 			X86EMU_trace_regs();
289 			break;
290 		case 'x':
291 			X86EMU_trace_xregs();
292 			break;
293 		case 'g':
294 			if (ntok == 2) {
295 				breakpoint = ps[1];
296 				if (noDecode) {
297 					M.x86.debug |= DEBUG_DECODE_NOPRINT_F;
298 				} else {
299 					M.x86.debug &= ~DEBUG_DECODE_NOPRINT_F;
300 				}
301 				M.x86.debug &= ~DEBUG_TRACE_F;
302 				M.x86.debug |= DEBUG_BREAK_F;
303 				done = 1;
304 			}
305 			break;
306 		case 'q':
307 			M.x86.debug |= DEBUG_EXIT;
308 			return;
309 		case 'P':
310 			noDecode = (noDecode) ? 0 : 1;
311 			printk("Toggled decoding to %s\n",
312 			       (noDecode) ? "FALSE" : "TRUE");
313 			break;
314 		case 't':
315 		case 0:
316 			done = 1;
317 			break;
318 		}
319 	}
320 }
321 
322 int X86EMU_trace_on(void)
323 {
324 	return M.x86.debug |= DEBUG_STEP_F | DEBUG_DECODE_F | DEBUG_TRACE_F;
325 }
326 
327 int X86EMU_trace_off(void)
328 {
329 	return M.x86.debug &= ~(DEBUG_STEP_F | DEBUG_DECODE_F | DEBUG_TRACE_F);
330 }
331 
332 static int x86emu_parse_line(char *s, int *ps, int *n)
333 {
334 	int cmd;
335 
336 	*n = 0;
337 	while (isblank(*s))
338 		s++;
339 	ps[*n] = *s;
340 	switch (*s) {
341 	case '\n':
342 		*n += 1;
343 		return 0;
344 	default:
345 		cmd = *s;
346 		*n += 1;
347 	}
348 
349 	while (1) {
350 		while (!isblank(*s) && *s != '\n')
351 			s++;
352 
353 		if (*s == '\n')
354 			return cmd;
355 
356 		while (isblank(*s))
357 			s++;
358 
359 		*n += 1;
360 	}
361 }
362 
363 #endif				/* DEBUG */
364 
365 void x86emu_dump_regs(void)
366 {
367 	printk("\tAX=%04x  ", M.x86.R_AX);
368 	printk("BX=%04x  ", M.x86.R_BX);
369 	printk("CX=%04x  ", M.x86.R_CX);
370 	printk("DX=%04x  ", M.x86.R_DX);
371 	printk("SP=%04x  ", M.x86.R_SP);
372 	printk("BP=%04x  ", M.x86.R_BP);
373 	printk("SI=%04x  ", M.x86.R_SI);
374 	printk("DI=%04x\n", M.x86.R_DI);
375 	printk("\tDS=%04x  ", M.x86.R_DS);
376 	printk("ES=%04x  ", M.x86.R_ES);
377 	printk("SS=%04x  ", M.x86.R_SS);
378 	printk("CS=%04x  ", M.x86.R_CS);
379 	printk("IP=%04x   ", M.x86.R_IP);
380 	if (ACCESS_FLAG(F_OF))
381 		printk("OV ");	/* CHECKED... */
382 	else
383 		printk("NV ");
384 	if (ACCESS_FLAG(F_DF))
385 		printk("DN ");
386 	else
387 		printk("UP ");
388 	if (ACCESS_FLAG(F_IF))
389 		printk("EI ");
390 	else
391 		printk("DI ");
392 	if (ACCESS_FLAG(F_SF))
393 		printk("NG ");
394 	else
395 		printk("PL ");
396 	if (ACCESS_FLAG(F_ZF))
397 		printk("ZR ");
398 	else
399 		printk("NZ ");
400 	if (ACCESS_FLAG(F_AF))
401 		printk("AC ");
402 	else
403 		printk("NA ");
404 	if (ACCESS_FLAG(F_PF))
405 		printk("PE ");
406 	else
407 		printk("PO ");
408 	if (ACCESS_FLAG(F_CF))
409 		printk("CY ");
410 	else
411 		printk("NC ");
412 	printk("\n");
413 }
414 
415 void x86emu_dump_xregs(void)
416 {
417 	printk("\tEAX=%08x  ", M.x86.R_EAX);
418 	printk("EBX=%08x  ", M.x86.R_EBX);
419 	printk("ECX=%08x  ", M.x86.R_ECX);
420 	printk("EDX=%08x  \n", M.x86.R_EDX);
421 	printk("\tESP=%08x  ", M.x86.R_ESP);
422 	printk("EBP=%08x  ", M.x86.R_EBP);
423 	printk("ESI=%08x  ", M.x86.R_ESI);
424 	printk("EDI=%08x\n", M.x86.R_EDI);
425 	printk("\tDS=%04x  ", M.x86.R_DS);
426 	printk("ES=%04x  ", M.x86.R_ES);
427 	printk("SS=%04x  ", M.x86.R_SS);
428 	printk("CS=%04x  ", M.x86.R_CS);
429 	printk("EIP=%08x\n\t", M.x86.R_EIP);
430 	if (ACCESS_FLAG(F_OF))
431 		printk("OV ");	/* CHECKED... */
432 	else
433 		printk("NV ");
434 	if (ACCESS_FLAG(F_DF))
435 		printk("DN ");
436 	else
437 		printk("UP ");
438 	if (ACCESS_FLAG(F_IF))
439 		printk("EI ");
440 	else
441 		printk("DI ");
442 	if (ACCESS_FLAG(F_SF))
443 		printk("NG ");
444 	else
445 		printk("PL ");
446 	if (ACCESS_FLAG(F_ZF))
447 		printk("ZR ");
448 	else
449 		printk("NZ ");
450 	if (ACCESS_FLAG(F_AF))
451 		printk("AC ");
452 	else
453 		printk("NA ");
454 	if (ACCESS_FLAG(F_PF))
455 		printk("PE ");
456 	else
457 		printk("PO ");
458 	if (ACCESS_FLAG(F_CF))
459 		printk("CY ");
460 	else
461 		printk("NC ");
462 	printk("\n");
463 }
464