1 /***************************************************************************
2  *   Copyright (C) 2006 by Dominic Rath                                    *
3  *   Dominic.Rath@gmx.de                                                   *
4  *                                                                         *
5  *   Copyright (C) 2008 by Hongtao Zheng                                   *
6  *   hontor@126.com                                                        *
7  *                                                                         *
8  *   This program is free software; you can redistribute it and/or modify  *
9  *   it under the terms of the GNU General Public License as published by  *
10  *   the Free Software Foundation; either version 2 of the License, or     *
11  *   (at your option) any later version.                                   *
12  *                                                                         *
13  *   This program is distributed in the hope that it will be useful,       *
14  *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
15  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
16  *   GNU General Public License for more details.                          *
17  *                                                                         *
18  *   You should have received a copy of the GNU General Public License     *
19  *   along with this program.  If not, see <http://www.gnu.org/licenses/>. *
20  ***************************************************************************/
21 
22 #ifdef HAVE_CONFIG_H
23 #include "config.h"
24 #endif
25 
26 #include "arm.h"
27 #include "armv4_5.h"
28 #include "arm_disassembler.h"
29 #include "arm_simulator.h"
30 #include <helper/binarybuffer.h>
31 #include "register.h"
32 #include <helper/log.h>
33 
arm_shift(uint8_t shift,uint32_t Rm,uint32_t shift_amount,uint8_t * carry)34 static uint32_t arm_shift(uint8_t shift, uint32_t Rm,
35 	uint32_t shift_amount, uint8_t *carry)
36 {
37 	uint32_t return_value = 0;
38 	shift_amount &= 0xff;
39 
40 	if (shift == 0x0) {	/* LSL */
41 		if ((shift_amount > 0) && (shift_amount <= 32)) {
42 			return_value = Rm << shift_amount;
43 			*carry = Rm >> (32 - shift_amount);
44 		} else if (shift_amount > 32) {
45 			return_value = 0x0;
46 			*carry = 0x0;
47 		} else /* (shift_amount == 0) */
48 			return_value = Rm;
49 	} else if (shift == 0x1) {	/* LSR */
50 		if ((shift_amount > 0) && (shift_amount <= 32)) {
51 			return_value = Rm >> shift_amount;
52 			*carry = (Rm >> (shift_amount - 1)) & 1;
53 		} else if (shift_amount > 32) {
54 			return_value = 0x0;
55 			*carry = 0x0;
56 		} else /* (shift_amount == 0) */
57 			return_value = Rm;
58 	} else if (shift == 0x2) {	/* ASR */
59 		if ((shift_amount > 0) && (shift_amount <= 32)) {
60 			/* C right shifts of unsigned values are guaranteed to
61 			 * be logical (shift in zeroes); simulate an arithmetic
62 			 * shift (shift in signed-bit) by adding the sign bit
63 			 * manually
64 			 */
65 			return_value = Rm >> shift_amount;
66 			if (Rm & 0x80000000)
67 				return_value |= 0xffffffff << (32 - shift_amount);
68 		} else if (shift_amount > 32) {
69 			if (Rm & 0x80000000) {
70 				return_value = 0xffffffff;
71 				*carry = 0x1;
72 			} else {
73 				return_value = 0x0;
74 				*carry = 0x0;
75 			}
76 		} else /* (shift_amount == 0) */
77 			return_value = Rm;
78 	} else if (shift == 0x3) {	/* ROR */
79 		if (shift_amount == 0)
80 			return_value = Rm;
81 		else {
82 			shift_amount = shift_amount % 32;
83 			return_value = (Rm >> shift_amount) | (Rm << (32 - shift_amount));
84 			*carry = (return_value >> 31) & 0x1;
85 		}
86 	} else if (shift == 0x4) {	/* RRX */
87 		return_value = Rm >> 1;
88 		if (*carry)
89 			Rm |= 0x80000000;
90 		*carry = Rm & 0x1;
91 	}
92 
93 	return return_value;
94 }
95 
96 
arm_shifter_operand(struct arm_sim_interface * sim,int variant,union arm_shifter_operand shifter_operand,uint8_t * shifter_carry_out)97 static uint32_t arm_shifter_operand(struct arm_sim_interface *sim,
98 	int variant, union arm_shifter_operand shifter_operand,
99 	uint8_t *shifter_carry_out)
100 {
101 	uint32_t return_value;
102 	int instruction_size;
103 
104 	if (sim->get_state(sim) == ARM_STATE_ARM)
105 		instruction_size = 4;
106 	else
107 		instruction_size = 2;
108 
109 	*shifter_carry_out = sim->get_cpsr(sim, 29, 1);
110 
111 	if (variant == 0) /* 32-bit immediate */
112 		return_value = shifter_operand.immediate.immediate;
113 	else if (variant == 1) {/* immediate shift */
114 		uint32_t Rm = sim->get_reg_mode(sim, shifter_operand.immediate_shift.Rm);
115 
116 		/* adjust RM in case the PC is being read */
117 		if (shifter_operand.immediate_shift.Rm == 15)
118 			Rm += 2 * instruction_size;
119 
120 		return_value = arm_shift(shifter_operand.immediate_shift.shift,
121 				Rm, shifter_operand.immediate_shift.shift_imm,
122 				shifter_carry_out);
123 	} else if (variant == 2) {	/* register shift */
124 		uint32_t Rm = sim->get_reg_mode(sim, shifter_operand.register_shift.Rm);
125 		uint32_t Rs = sim->get_reg_mode(sim, shifter_operand.register_shift.Rs);
126 
127 		/* adjust RM in case the PC is being read */
128 		if (shifter_operand.register_shift.Rm == 15)
129 			Rm += 2 * instruction_size;
130 
131 		return_value = arm_shift(shifter_operand.immediate_shift.shift,
132 				Rm, Rs, shifter_carry_out);
133 	} else {
134 		LOG_ERROR("BUG: shifter_operand.variant not 0, 1 or 2");
135 		return_value = 0xffffffff;
136 	}
137 
138 	return return_value;
139 }
140 
pass_condition(uint32_t cpsr,uint32_t opcode)141 static int pass_condition(uint32_t cpsr, uint32_t opcode)
142 {
143 	switch ((opcode & 0xf0000000) >> 28) {
144 		case 0x0:	/* EQ */
145 			if (cpsr & 0x40000000)
146 				return 1;
147 			else
148 				return 0;
149 		case 0x1:	/* NE */
150 			if (!(cpsr & 0x40000000))
151 				return 1;
152 			else
153 				return 0;
154 		case 0x2:	/* CS */
155 			if (cpsr & 0x20000000)
156 				return 1;
157 			else
158 				return 0;
159 		case 0x3:	/* CC */
160 			if (!(cpsr & 0x20000000))
161 				return 1;
162 			else
163 				return 0;
164 		case 0x4:	/* MI */
165 			if (cpsr & 0x80000000)
166 				return 1;
167 			else
168 				return 0;
169 		case 0x5:	/* PL */
170 			if (!(cpsr & 0x80000000))
171 				return 1;
172 			else
173 				return 0;
174 		case 0x6:	/* VS */
175 			if (cpsr & 0x10000000)
176 				return 1;
177 			else
178 				return 0;
179 		case 0x7:	/* VC */
180 			if (!(cpsr & 0x10000000))
181 				return 1;
182 			else
183 				return 0;
184 		case 0x8:	/* HI */
185 			if ((cpsr & 0x20000000) && !(cpsr & 0x40000000))
186 				return 1;
187 			else
188 				return 0;
189 		case 0x9:	/* LS */
190 			if (!(cpsr & 0x20000000) || (cpsr & 0x40000000))
191 				return 1;
192 			else
193 				return 0;
194 		case 0xa:	/* GE */
195 			if (((cpsr & 0x80000000) && (cpsr & 0x10000000))
196 				|| (!(cpsr & 0x80000000) && !(cpsr & 0x10000000)))
197 				return 1;
198 			else
199 				return 0;
200 		case 0xb:	/* LT */
201 			if (((cpsr & 0x80000000) && !(cpsr & 0x10000000))
202 				|| (!(cpsr & 0x80000000) && (cpsr & 0x10000000)))
203 				return 1;
204 			else
205 				return 0;
206 		case 0xc:	/* GT */
207 			if (!(cpsr & 0x40000000) &&
208 				(((cpsr & 0x80000000) && (cpsr & 0x10000000))
209 				|| (!(cpsr & 0x80000000) && !(cpsr & 0x10000000))))
210 				return 1;
211 			else
212 				return 0;
213 		case 0xd:	/* LE */
214 			if ((cpsr & 0x40000000) ||
215 				((cpsr & 0x80000000) && !(cpsr & 0x10000000))
216 				|| (!(cpsr & 0x80000000) && (cpsr & 0x10000000)))
217 				return 1;
218 			else
219 				return 0;
220 		case 0xe:
221 		case 0xf:
222 			return 1;
223 
224 	}
225 
226 	LOG_ERROR("BUG: should never get here");
227 	return 0;
228 }
229 
thumb_pass_branch_condition(uint32_t cpsr,uint16_t opcode)230 static int thumb_pass_branch_condition(uint32_t cpsr, uint16_t opcode)
231 {
232 	return pass_condition(cpsr, (opcode & 0x0f00) << 20);
233 }
234 
235 /* simulate a single step (if possible)
236  * if the dry_run_pc argument is provided, no state is changed,
237  * but the new pc is stored in the variable pointed at by the argument
238  */
arm_simulate_step_core(struct target * target,uint32_t * dry_run_pc,struct arm_sim_interface * sim)239 static int arm_simulate_step_core(struct target *target,
240 	uint32_t *dry_run_pc, struct arm_sim_interface *sim)
241 {
242 	uint32_t current_pc = sim->get_reg(sim, 15);
243 	struct arm_instruction instruction;
244 	int instruction_size;
245 	int retval = ERROR_OK;
246 
247 	if (sim->get_state(sim) == ARM_STATE_ARM) {
248 		uint32_t opcode;
249 
250 		/* get current instruction, and identify it */
251 		retval = target_read_u32(target, current_pc, &opcode);
252 		if (retval != ERROR_OK)
253 			return retval;
254 		retval = arm_evaluate_opcode(opcode, current_pc, &instruction);
255 		if (retval != ERROR_OK)
256 			return retval;
257 		instruction_size = 4;
258 
259 		/* check condition code (for all instructions) */
260 		if (!pass_condition(sim->get_cpsr(sim, 0, 32), opcode)) {
261 			if (dry_run_pc)
262 				*dry_run_pc = current_pc + instruction_size;
263 			else
264 				sim->set_reg(sim, 15, current_pc + instruction_size);
265 
266 			return ERROR_OK;
267 		}
268 	} else {
269 		uint16_t opcode;
270 
271 		retval = target_read_u16(target, current_pc, &opcode);
272 		if (retval != ERROR_OK)
273 			return retval;
274 		retval = thumb_evaluate_opcode(opcode, current_pc, &instruction);
275 		if (retval != ERROR_OK)
276 			return retval;
277 		instruction_size = 2;
278 
279 		/* check condition code (only for branch (1) instructions) */
280 		if ((opcode & 0xf000) == 0xd000
281 			&& !thumb_pass_branch_condition(
282 			sim->get_cpsr(sim, 0, 32), opcode)) {
283 			if (dry_run_pc)
284 				*dry_run_pc = current_pc + instruction_size;
285 			else
286 				sim->set_reg(sim, 15, current_pc + instruction_size);
287 
288 			return ERROR_OK;
289 		}
290 
291 		/* Deal with 32-bit BL/BLX */
292 		if ((opcode & 0xf800) == 0xf000) {
293 			uint32_t high = instruction.info.b_bl_bx_blx.target_address;
294 			retval = target_read_u16(target, current_pc+2, &opcode);
295 			if (retval != ERROR_OK)
296 				return retval;
297 			retval = thumb_evaluate_opcode(opcode, current_pc, &instruction);
298 			if (retval != ERROR_OK)
299 				return retval;
300 			instruction.info.b_bl_bx_blx.target_address += high;
301 		}
302 	}
303 
304 	/* examine instruction type */
305 
306 	/* branch instructions */
307 	if ((instruction.type >= ARM_B) && (instruction.type <= ARM_BLX)) {
308 		uint32_t target_address;
309 
310 		if (instruction.info.b_bl_bx_blx.reg_operand == -1)
311 			target_address = instruction.info.b_bl_bx_blx.target_address;
312 		else {
313 			target_address = sim->get_reg_mode(sim,
314 					instruction.info.b_bl_bx_blx.reg_operand);
315 			if (instruction.info.b_bl_bx_blx.reg_operand == 15)
316 				target_address += 2 * instruction_size;
317 		}
318 
319 		if (dry_run_pc) {
320 			*dry_run_pc = target_address & ~1;
321 			return ERROR_OK;
322 		} else {
323 			if (instruction.type == ARM_B)
324 				sim->set_reg(sim, 15, target_address);
325 			else if (instruction.type == ARM_BL) {
326 				uint32_t old_pc = sim->get_reg(sim, 15);
327 				int T = (sim->get_state(sim) == ARM_STATE_THUMB);
328 				sim->set_reg_mode(sim, 14, old_pc + 4 + T);
329 				sim->set_reg(sim, 15, target_address);
330 			} else if (instruction.type == ARM_BX) {
331 				if (target_address & 0x1)
332 					sim->set_state(sim, ARM_STATE_THUMB);
333 				else
334 					sim->set_state(sim, ARM_STATE_ARM);
335 				sim->set_reg(sim, 15, target_address & 0xfffffffe);
336 			} else if (instruction.type == ARM_BLX) {
337 				uint32_t old_pc = sim->get_reg(sim, 15);
338 				int T = (sim->get_state(sim) == ARM_STATE_THUMB);
339 				sim->set_reg_mode(sim, 14, old_pc + 4 + T);
340 
341 				if (target_address & 0x1)
342 					sim->set_state(sim, ARM_STATE_THUMB);
343 				else
344 					sim->set_state(sim, ARM_STATE_ARM);
345 				sim->set_reg(sim, 15, target_address & 0xfffffffe);
346 			}
347 
348 			return ERROR_OK;
349 		}
350 	}
351 	/* data processing instructions, except compare instructions (CMP, CMN, TST, TEQ) */
352 	else if (((instruction.type >= ARM_AND) && (instruction.type <= ARM_RSC))
353 		|| ((instruction.type >= ARM_ORR) && (instruction.type <= ARM_MVN))) {
354 		uint32_t Rd, Rn, shifter_operand;
355 		uint8_t C = sim->get_cpsr(sim, 29, 1);
356 		uint8_t carry_out;
357 
358 		Rd = 0x0;
359 		/* ARM_MOV and ARM_MVN does not use Rn */
360 		if ((instruction.type != ARM_MOV) && (instruction.type != ARM_MVN))
361 			Rn = sim->get_reg_mode(sim, instruction.info.data_proc.Rn);
362 		else
363 			Rn = 0;
364 
365 		shifter_operand = arm_shifter_operand(sim,
366 				instruction.info.data_proc.variant,
367 				instruction.info.data_proc.shifter_operand,
368 				&carry_out);
369 
370 		/* adjust Rn in case the PC is being read */
371 		if (instruction.info.data_proc.Rn == 15)
372 			Rn += 2 * instruction_size;
373 
374 		if (instruction.type == ARM_AND)
375 			Rd = Rn & shifter_operand;
376 		else if (instruction.type == ARM_EOR)
377 			Rd = Rn ^ shifter_operand;
378 		else if (instruction.type == ARM_SUB)
379 			Rd = Rn - shifter_operand;
380 		else if (instruction.type == ARM_RSB)
381 			Rd = shifter_operand - Rn;
382 		else if (instruction.type == ARM_ADD)
383 			Rd = Rn + shifter_operand;
384 		else if (instruction.type == ARM_ADC)
385 			Rd = Rn + shifter_operand + (C & 1);
386 		else if (instruction.type == ARM_SBC)
387 			Rd = Rn - shifter_operand - (C & 1) ? 0 : 1;
388 		else if (instruction.type == ARM_RSC)
389 			Rd = shifter_operand - Rn - (C & 1) ? 0 : 1;
390 		else if (instruction.type == ARM_ORR)
391 			Rd = Rn | shifter_operand;
392 		else if (instruction.type == ARM_BIC)
393 			Rd = Rn & ~(shifter_operand);
394 		else if (instruction.type == ARM_MOV)
395 			Rd = shifter_operand;
396 		else if (instruction.type == ARM_MVN)
397 			Rd = ~shifter_operand;
398 		else
399 			LOG_WARNING("unhandled instruction type");
400 
401 		if (dry_run_pc) {
402 			if (instruction.info.data_proc.Rd == 15)
403 				*dry_run_pc = Rd & ~1;
404 			else
405 				*dry_run_pc = current_pc + instruction_size;
406 
407 			return ERROR_OK;
408 		} else {
409 			if (instruction.info.data_proc.Rd == 15) {
410 				sim->set_reg_mode(sim, 15, Rd & ~1);
411 				if (Rd & 1)
412 					sim->set_state(sim, ARM_STATE_THUMB);
413 				else
414 					sim->set_state(sim, ARM_STATE_ARM);
415 				return ERROR_OK;
416 			}
417 			sim->set_reg_mode(sim, instruction.info.data_proc.Rd, Rd);
418 			LOG_WARNING("no updating of flags yet");
419 		}
420 	}
421 	/* compare instructions (CMP, CMN, TST, TEQ) */
422 	else if ((instruction.type >= ARM_TST) && (instruction.type <= ARM_CMN)) {
423 		if (dry_run_pc) {
424 			*dry_run_pc = current_pc + instruction_size;
425 			return ERROR_OK;
426 		} else
427 			LOG_WARNING("no updating of flags yet");
428 	}
429 	/* load register instructions */
430 	else if ((instruction.type >= ARM_LDR) && (instruction.type <= ARM_LDRSH)) {
431 		uint32_t load_address = 0, modified_address = 0, load_value = 0;
432 		uint32_t Rn = sim->get_reg_mode(sim, instruction.info.load_store.Rn);
433 
434 		/* adjust Rn in case the PC is being read */
435 		if (instruction.info.load_store.Rn == 15)
436 			Rn += 2 * instruction_size;
437 
438 		if (instruction.info.load_store.offset_mode == 0) {
439 			if (instruction.info.load_store.U)
440 				modified_address = Rn + instruction.info.load_store.offset.offset;
441 			else
442 				modified_address = Rn - instruction.info.load_store.offset.offset;
443 		} else if (instruction.info.load_store.offset_mode == 1) {
444 			uint32_t offset;
445 			uint32_t Rm = sim->get_reg_mode(sim,
446 					instruction.info.load_store.offset.reg.Rm);
447 			uint8_t shift = instruction.info.load_store.offset.reg.shift;
448 			uint8_t shift_imm = instruction.info.load_store.offset.reg.shift_imm;
449 			uint8_t carry = sim->get_cpsr(sim, 29, 1);
450 
451 			offset = arm_shift(shift, Rm, shift_imm, &carry);
452 
453 			if (instruction.info.load_store.U)
454 				modified_address = Rn + offset;
455 			else
456 				modified_address = Rn - offset;
457 		} else
458 			LOG_ERROR("BUG: offset_mode neither 0 (offset) nor 1 (scaled register)");
459 
460 		if (instruction.info.load_store.index_mode == 0) {
461 			/* offset mode
462 			 * we load from the modified address, but don't change
463 			 * the base address register
464 			 */
465 			load_address = modified_address;
466 			modified_address = Rn;
467 		} else if (instruction.info.load_store.index_mode == 1) {
468 			/* pre-indexed mode
469 			 * we load from the modified address, and write it
470 			 * back to the base address register
471 			 */
472 			load_address = modified_address;
473 		} else if (instruction.info.load_store.index_mode == 2) {
474 			/* post-indexed mode
475 			 * we load from the unmodified address, and write the
476 			 * modified address back
477 			 */
478 			load_address = Rn;
479 		}
480 
481 		if ((!dry_run_pc) || (instruction.info.load_store.Rd == 15)) {
482 			retval = target_read_u32(target, load_address, &load_value);
483 			if (retval != ERROR_OK)
484 				return retval;
485 		}
486 
487 		if (dry_run_pc) {
488 			if (instruction.info.load_store.Rd == 15)
489 				*dry_run_pc = load_value & ~1;
490 			else
491 				*dry_run_pc = current_pc + instruction_size;
492 			return ERROR_OK;
493 		} else {
494 			if ((instruction.info.load_store.index_mode == 1) ||
495 				(instruction.info.load_store.index_mode == 2))
496 				sim->set_reg_mode(sim,
497 					instruction.info.load_store.Rn,
498 					modified_address);
499 
500 			if (instruction.info.load_store.Rd == 15) {
501 				sim->set_reg_mode(sim, 15, load_value & ~1);
502 				if (load_value & 1)
503 					sim->set_state(sim, ARM_STATE_THUMB);
504 				else
505 					sim->set_state(sim, ARM_STATE_ARM);
506 				return ERROR_OK;
507 			}
508 			sim->set_reg_mode(sim, instruction.info.load_store.Rd, load_value);
509 		}
510 	}
511 	/* load multiple instruction */
512 	else if (instruction.type == ARM_LDM) {
513 		int i;
514 		uint32_t Rn = sim->get_reg_mode(sim, instruction.info.load_store_multiple.Rn);
515 		uint32_t load_values[16];
516 		int bits_set = 0;
517 
518 		for (i = 0; i < 16; i++) {
519 			if (instruction.info.load_store_multiple.register_list & (1 << i))
520 				bits_set++;
521 		}
522 
523 		switch (instruction.info.load_store_multiple.addressing_mode) {
524 			case 0:	/* Increment after */
525 				/* Rn = Rn; */
526 				break;
527 			case 1:	/* Increment before */
528 				Rn = Rn + 4;
529 				break;
530 			case 2:	/* Decrement after */
531 				Rn = Rn - (bits_set * 4) + 4;
532 				break;
533 			case 3:	/* Decrement before */
534 				Rn = Rn - (bits_set * 4);
535 				break;
536 		}
537 
538 		for (i = 0; i < 16; i++) {
539 			if (instruction.info.load_store_multiple.register_list & (1 << i)) {
540 				if ((!dry_run_pc) || (i == 15))
541 					target_read_u32(target, Rn, &load_values[i]);
542 				Rn += 4;
543 			}
544 		}
545 
546 		if (dry_run_pc) {
547 			if (instruction.info.load_store_multiple.register_list & 0x8000) {
548 				*dry_run_pc = load_values[15] & ~1;
549 				return ERROR_OK;
550 			}
551 		} else {
552 			int update_cpsr = 0;
553 
554 			if (instruction.info.load_store_multiple.S) {
555 				if (instruction.info.load_store_multiple.register_list & 0x8000)
556 					update_cpsr = 1;
557 			}
558 
559 			for (i = 0; i < 16; i++) {
560 				if (instruction.info.load_store_multiple.register_list & (1 << i)) {
561 					if (i == 15) {
562 						uint32_t val = load_values[i];
563 						sim->set_reg_mode(sim, i, val & ~1);
564 						if (val & 1)
565 							sim->set_state(sim, ARM_STATE_THUMB);
566 						else
567 							sim->set_state(sim, ARM_STATE_ARM);
568 					} else
569 						sim->set_reg_mode(sim, i, load_values[i]);
570 				}
571 			}
572 
573 			if (update_cpsr) {
574 				uint32_t spsr = sim->get_reg_mode(sim, 16);
575 				sim->set_reg(sim, ARMV4_5_CPSR, spsr);
576 			}
577 
578 			/* base register writeback */
579 			if (instruction.info.load_store_multiple.W)
580 				sim->set_reg_mode(sim, instruction.info.load_store_multiple.Rn, Rn);
581 
582 
583 			if (instruction.info.load_store_multiple.register_list & 0x8000)
584 				return ERROR_OK;
585 		}
586 	}
587 	/* store multiple instruction */
588 	else if (instruction.type == ARM_STM) {
589 		int i;
590 
591 		if (dry_run_pc) {
592 			/* STM wont affect PC (advance by instruction size */
593 		} else {
594 			uint32_t Rn = sim->get_reg_mode(sim,
595 					instruction.info.load_store_multiple.Rn);
596 			int bits_set = 0;
597 
598 			for (i = 0; i < 16; i++) {
599 				if (instruction.info.load_store_multiple.register_list & (1 << i))
600 					bits_set++;
601 			}
602 
603 			switch (instruction.info.load_store_multiple.addressing_mode) {
604 				case 0:	/* Increment after */
605 					/* Rn = Rn; */
606 					break;
607 				case 1:	/* Increment before */
608 					Rn = Rn + 4;
609 					break;
610 				case 2:	/* Decrement after */
611 					Rn = Rn - (bits_set * 4) + 4;
612 					break;
613 				case 3:	/* Decrement before */
614 					Rn = Rn - (bits_set * 4);
615 					break;
616 			}
617 
618 			for (i = 0; i < 16; i++) {
619 				if (instruction.info.load_store_multiple.register_list & (1 << i)) {
620 					target_write_u32(target, Rn, sim->get_reg_mode(sim, i));
621 					Rn += 4;
622 				}
623 			}
624 
625 			/* base register writeback */
626 			if (instruction.info.load_store_multiple.W)
627 				sim->set_reg_mode(sim,
628 					instruction.info.load_store_multiple.Rn, Rn);
629 
630 		}
631 	} else if (!dry_run_pc) {
632 		/* the instruction wasn't handled, but we're supposed to simulate it
633 		 */
634 		LOG_ERROR("Unimplemented instruction, could not simulate it.");
635 		return ERROR_FAIL;
636 	}
637 
638 	if (dry_run_pc) {
639 		*dry_run_pc = current_pc + instruction_size;
640 		return ERROR_OK;
641 	} else {
642 		sim->set_reg(sim, 15, current_pc + instruction_size);
643 		return ERROR_OK;
644 	}
645 
646 }
647 
armv4_5_get_reg(struct arm_sim_interface * sim,int reg)648 static uint32_t armv4_5_get_reg(struct arm_sim_interface *sim, int reg)
649 {
650 	struct arm *arm = (struct arm *)sim->user_data;
651 
652 	return buf_get_u32(arm->core_cache->reg_list[reg].value, 0, 32);
653 }
654 
armv4_5_set_reg(struct arm_sim_interface * sim,int reg,uint32_t value)655 static void armv4_5_set_reg(struct arm_sim_interface *sim, int reg, uint32_t value)
656 {
657 	struct arm *arm = (struct arm *)sim->user_data;
658 
659 	buf_set_u32(arm->core_cache->reg_list[reg].value, 0, 32, value);
660 }
661 
armv4_5_get_reg_mode(struct arm_sim_interface * sim,int reg)662 static uint32_t armv4_5_get_reg_mode(struct arm_sim_interface *sim, int reg)
663 {
664 	struct arm *arm = (struct arm *)sim->user_data;
665 
666 	return buf_get_u32(ARMV4_5_CORE_REG_MODE(arm->core_cache,
667 			arm->core_mode, reg).value, 0, 32);
668 }
669 
armv4_5_set_reg_mode(struct arm_sim_interface * sim,int reg,uint32_t value)670 static void armv4_5_set_reg_mode(struct arm_sim_interface *sim, int reg, uint32_t value)
671 {
672 	struct arm *arm = (struct arm *)sim->user_data;
673 
674 	buf_set_u32(ARMV4_5_CORE_REG_MODE(arm->core_cache,
675 		arm->core_mode, reg).value, 0, 32, value);
676 }
677 
armv4_5_get_cpsr(struct arm_sim_interface * sim,int pos,int bits)678 static uint32_t armv4_5_get_cpsr(struct arm_sim_interface *sim, int pos, int bits)
679 {
680 	struct arm *arm = (struct arm *)sim->user_data;
681 
682 	return buf_get_u32(arm->cpsr->value, pos, bits);
683 }
684 
armv4_5_get_state(struct arm_sim_interface * sim)685 static enum arm_state armv4_5_get_state(struct arm_sim_interface *sim)
686 {
687 	struct arm *arm = (struct arm *)sim->user_data;
688 
689 	return arm->core_state;
690 }
691 
armv4_5_set_state(struct arm_sim_interface * sim,enum arm_state mode)692 static void armv4_5_set_state(struct arm_sim_interface *sim, enum arm_state mode)
693 {
694 	struct arm *arm = (struct arm *)sim->user_data;
695 
696 	arm->core_state = mode;
697 }
698 
armv4_5_get_mode(struct arm_sim_interface * sim)699 static enum arm_mode armv4_5_get_mode(struct arm_sim_interface *sim)
700 {
701 	struct arm *arm = (struct arm *)sim->user_data;
702 
703 	return arm->core_mode;
704 }
705 
arm_simulate_step(struct target * target,uint32_t * dry_run_pc)706 int arm_simulate_step(struct target *target, uint32_t *dry_run_pc)
707 {
708 	struct arm *arm = target_to_arm(target);
709 	struct arm_sim_interface sim;
710 
711 	sim.user_data = arm;
712 	sim.get_reg = &armv4_5_get_reg;
713 	sim.set_reg = &armv4_5_set_reg;
714 	sim.get_reg_mode = &armv4_5_get_reg_mode;
715 	sim.set_reg_mode = &armv4_5_set_reg_mode;
716 	sim.get_cpsr = &armv4_5_get_cpsr;
717 	sim.get_mode = &armv4_5_get_mode;
718 	sim.get_state = &armv4_5_get_state;
719 	sim.set_state = &armv4_5_set_state;
720 
721 	return arm_simulate_step_core(target, dry_run_pc, &sim);
722 }
723