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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 CONFIG_X86EMU_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. */
X86EMU_trace_regs(void)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 
X86EMU_trace_xregs(void)66 void X86EMU_trace_xregs(void)
67 {
68 	if (DEBUG_TRACE()) {
69 		x86emu_dump_xregs();
70 	}
71 }
72 
x86emu_just_disassemble(void)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 
disassemble_forward(u16 seg,u16 off,int n)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 
x86emu_check_ip_access(void)139 void x86emu_check_ip_access(void)
140 {
141 	/* NULL as of now */
142 }
143 
x86emu_check_sp_access(void)144 void x86emu_check_sp_access(void)
145 {
146 }
147 
x86emu_check_mem_access(u32 dummy)148 void x86emu_check_mem_access(u32 dummy)
149 {
150 	/*  check bounds, etc */
151 }
152 
x86emu_check_data_access(uint dummy1,uint dummy2)153 void x86emu_check_data_access(uint dummy1, uint dummy2)
154 {
155 	/*  check bounds, etc */
156 }
157 
x86emu_inc_decoded_inst_len(int x)158 void x86emu_inc_decoded_inst_len(int x)
159 {
160 	M.x86.enc_pos += x;
161 }
162 
x86emu_decode_printf(char * x)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 
x86emu_decode_printf2(char * x,int y)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 
x86emu_end_instr(void)177 void x86emu_end_instr(void)
178 {
179 	M.x86.enc_str_pos = 0;
180 	M.x86.enc_pos = 0;
181 }
182 
print_encoded_bytes(u16 s,u16 o)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 
print_decoded_instruction(void)193 static void print_decoded_instruction(void)
194 {
195 	printk("%s", M.x86.decoded_buf);
196 }
197 
x86emu_print_int_vect(u16 iv)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 
X86EMU_dump_memory(u16 seg,u16 off,u32 amt)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 
215 	while (end <= off + amt) {
216 		printk("%04x:%04x ", seg, start);
217 		for (i = start; i < off; i++)
218 			printk("   ");
219 		for (; i < end; i++)
220 			printk("%02x ", fetch_data_byte_abs(seg, i));
221 		printk("\n");
222 		start = end;
223 		end = start + 16;
224 	}
225 }
226 
x86emu_single_step(void)227 void x86emu_single_step(void)
228 {
229 	char s[1024];
230 	 int ps[10];
231 	int ntok;
232 	int cmd;
233 	int done;
234 	int segment;
235 	int offset;
236 	static int breakpoint;
237 	static int noDecode = 1;
238 
239 	if (DEBUG_BREAK()) {
240 		if (M.x86.saved_ip != breakpoint) {
241 			return;
242 		} else {
243 			M.x86.debug &= ~DEBUG_DECODE_NOPRINT_F;
244 			M.x86.debug |= DEBUG_TRACE_F;
245 			M.x86.debug &= ~DEBUG_BREAK_F;
246 			print_decoded_instruction();
247 			X86EMU_trace_regs();
248 		}
249 	}
250 	done = 0;
251 	offset = M.x86.saved_ip;
252 	while (!done) {
253 		printk("-");
254 		ps[1] = 0; /* Avoid dodgy compiler warnings */
255 		ps[2] = 0;
256 		cmd = x86emu_parse_line(s, ps, &ntok);
257 		switch (cmd) {
258 		case 'u':
259 			disassemble_forward(M.x86.saved_cs, (u16) offset, 10);
260 			break;
261 		case 'd':
262 			if (ntok == 2) {
263 				segment = M.x86.saved_cs;
264 				offset = ps[1];
265 				X86EMU_dump_memory(segment, (u16) offset, 16);
266 				offset += 16;
267 			} else if (ntok == 3) {
268 				segment = ps[1];
269 				offset = ps[2];
270 				X86EMU_dump_memory(segment, (u16) offset, 16);
271 				offset += 16;
272 			} else {
273 				segment = M.x86.saved_cs;
274 				X86EMU_dump_memory(segment, (u16) offset, 16);
275 				offset += 16;
276 			}
277 			break;
278 		case 'c':
279 			M.x86.debug ^= DEBUG_TRACECALL_F;
280 			break;
281 		case 's':
282 			M.x86.debug ^=
283 			    DEBUG_SVC_F | DEBUG_SYS_F | DEBUG_SYSINT_F;
284 			break;
285 		case 'r':
286 			X86EMU_trace_regs();
287 			break;
288 		case 'x':
289 			X86EMU_trace_xregs();
290 			break;
291 		case 'g':
292 			if (ntok == 2) {
293 				breakpoint = ps[1];
294 				if (noDecode) {
295 					M.x86.debug |= DEBUG_DECODE_NOPRINT_F;
296 				} else {
297 					M.x86.debug &= ~DEBUG_DECODE_NOPRINT_F;
298 				}
299 				M.x86.debug &= ~DEBUG_TRACE_F;
300 				M.x86.debug |= DEBUG_BREAK_F;
301 				done = 1;
302 			}
303 			break;
304 		case 'q':
305 			M.x86.debug |= DEBUG_EXIT;
306 			return;
307 		case 'P':
308 			noDecode = (noDecode) ? 0 : 1;
309 			printk("Toggled decoding to %s\n",
310 			       (noDecode) ? "false" : "true");
311 			break;
312 		case 't':
313 		case 0:
314 			done = 1;
315 			break;
316 		}
317 	}
318 }
319 
X86EMU_trace_on(void)320 int X86EMU_trace_on(void)
321 {
322 	return M.x86.debug |= DEBUG_STEP_F | DEBUG_DECODE_F | DEBUG_TRACE_F;
323 }
324 
X86EMU_trace_off(void)325 int X86EMU_trace_off(void)
326 {
327 	return M.x86.debug &= ~(DEBUG_STEP_F | DEBUG_DECODE_F | DEBUG_TRACE_F);
328 }
329 
x86emu_parse_line(char * s,int * ps,int * n)330 static int x86emu_parse_line(char *s, int *ps, int *n)
331 {
332 	int cmd;
333 
334 	*n = 0;
335 	while (isblank(*s))
336 		s++;
337 	ps[*n] = *s;
338 	switch (*s) {
339 	case '\n':
340 		*n += 1;
341 		return 0;
342 	default:
343 		cmd = *s;
344 		*n += 1;
345 	}
346 
347 	while (1) {
348 		while (!isblank(*s) && *s != '\n')
349 			s++;
350 
351 		if (*s == '\n')
352 			return cmd;
353 
354 		while (isblank(*s))
355 			s++;
356 
357 		*n += 1;
358 	}
359 }
360 
361 #endif				/* DEBUG */
362 
x86emu_dump_regs(void)363 void x86emu_dump_regs(void)
364 {
365 	printk("\tAX=%04x  ", M.x86.R_AX);
366 	printk("BX=%04x  ", M.x86.R_BX);
367 	printk("CX=%04x  ", M.x86.R_CX);
368 	printk("DX=%04x  ", M.x86.R_DX);
369 	printk("SP=%04x  ", M.x86.R_SP);
370 	printk("BP=%04x  ", M.x86.R_BP);
371 	printk("SI=%04x  ", M.x86.R_SI);
372 	printk("DI=%04x\n", M.x86.R_DI);
373 	printk("\tDS=%04x  ", M.x86.R_DS);
374 	printk("ES=%04x  ", M.x86.R_ES);
375 	printk("SS=%04x  ", M.x86.R_SS);
376 	printk("CS=%04x  ", M.x86.R_CS);
377 	printk("IP=%04x   ", M.x86.R_IP);
378 	if (ACCESS_FLAG(F_OF))
379 		printk("OV ");	/* CHECKED... */
380 	else
381 		printk("NV ");
382 	if (ACCESS_FLAG(F_DF))
383 		printk("DN ");
384 	else
385 		printk("UP ");
386 	if (ACCESS_FLAG(F_IF))
387 		printk("EI ");
388 	else
389 		printk("DI ");
390 	if (ACCESS_FLAG(F_SF))
391 		printk("NG ");
392 	else
393 		printk("PL ");
394 	if (ACCESS_FLAG(F_ZF))
395 		printk("ZR ");
396 	else
397 		printk("NZ ");
398 	if (ACCESS_FLAG(F_AF))
399 		printk("AC ");
400 	else
401 		printk("NA ");
402 	if (ACCESS_FLAG(F_PF))
403 		printk("PE ");
404 	else
405 		printk("PO ");
406 	if (ACCESS_FLAG(F_CF))
407 		printk("CY ");
408 	else
409 		printk("NC ");
410 	printk("\n");
411 }
412 
x86emu_dump_xregs(void)413 void x86emu_dump_xregs(void)
414 {
415 	printk("\tEAX=%08x  ", M.x86.R_EAX);
416 	printk("EBX=%08x  ", M.x86.R_EBX);
417 	printk("ECX=%08x  ", M.x86.R_ECX);
418 	printk("EDX=%08x  \n", M.x86.R_EDX);
419 	printk("\tESP=%08x  ", M.x86.R_ESP);
420 	printk("EBP=%08x  ", M.x86.R_EBP);
421 	printk("ESI=%08x  ", M.x86.R_ESI);
422 	printk("EDI=%08x\n", M.x86.R_EDI);
423 	printk("\tDS=%04x  ", M.x86.R_DS);
424 	printk("ES=%04x  ", M.x86.R_ES);
425 	printk("SS=%04x  ", M.x86.R_SS);
426 	printk("CS=%04x  ", M.x86.R_CS);
427 	printk("EIP=%08x\n\t", M.x86.R_EIP);
428 	if (ACCESS_FLAG(F_OF))
429 		printk("OV ");	/* CHECKED... */
430 	else
431 		printk("NV ");
432 	if (ACCESS_FLAG(F_DF))
433 		printk("DN ");
434 	else
435 		printk("UP ");
436 	if (ACCESS_FLAG(F_IF))
437 		printk("EI ");
438 	else
439 		printk("DI ");
440 	if (ACCESS_FLAG(F_SF))
441 		printk("NG ");
442 	else
443 		printk("PL ");
444 	if (ACCESS_FLAG(F_ZF))
445 		printk("ZR ");
446 	else
447 		printk("NZ ");
448 	if (ACCESS_FLAG(F_AF))
449 		printk("AC ");
450 	else
451 		printk("NA ");
452 	if (ACCESS_FLAG(F_PF))
453 		printk("PE ");
454 	else
455 		printk("PO ");
456 	if (ACCESS_FLAG(F_CF))
457 		printk("CY ");
458 	else
459 		printk("NC ");
460 	printk("\n");
461 }
462