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Linux 3.12.28
[linux/fpc-iii.git] / arch / arc / kernel / disasm.c
blobb8a549c4f54071f97d26c473a9dca532e1db8b41
1 /*
2 * several functions that help interpret ARC instructions
3 * used for unaligned accesses, kprobes and kgdb
4 *
5 * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
6 *
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License version 2 as
9 * published by the Free Software Foundation.
10 */
11
12 #include <linux/types.h>
13 #include <linux/kprobes.h>
14 #include <linux/slab.h>
15 #include <linux/uaccess.h>
16 #include <asm/disasm.h>
17
18 #if defined(CONFIG_KGDB) || defined(CONFIG_ARC_MISALIGN_ACCESS) || \
19 defined(CONFIG_KPROBES)
20
21 /* disasm_instr: Analyses instruction at addr, stores
22 * findings in *state
23 */
24 void __kprobes disasm_instr(unsigned long addr, struct disasm_state *state,
25 int userspace, struct pt_regs *regs, struct callee_regs *cregs)
26 {
27 int fieldA = 0;
28 int fieldC = 0, fieldCisReg = 0;
29 uint16_t word1 = 0, word0 = 0;
30 int subopcode, is_linked, op_format;
31 uint16_t *ins_ptr;
32 uint16_t ins_buf[4];
33 int bytes_not_copied = 0;
34
35 memset(state, 0, sizeof(struct disasm_state));
36
37 /* This fetches the upper part of the 32 bit instruction
38 * in both the cases of Little Endian or Big Endian configurations. */
39 if (userspace) {
40 bytes_not_copied = copy_from_user(ins_buf,
41 (const void __user *) addr, 8);
42 if (bytes_not_copied > 6)
43 goto fault;
44 ins_ptr = ins_buf;
45 } else {
46 ins_ptr = (uint16_t *) addr;
47 }
48
49 word1 = *((uint16_t *)addr);
50
51 state->major_opcode = (word1 >> 11) & 0x1F;
52
53 /* Check if the instruction is 32 bit or 16 bit instruction */
54 if (state->major_opcode < 0x0B) {
55 if (bytes_not_copied > 4)
56 goto fault;
57 state->instr_len = 4;
58 word0 = *((uint16_t *)(addr+2));
59 state->words[0] = (word1 << 16) | word0;
60 } else {
61 state->instr_len = 2;
62 state->words[0] = word1;
63 }
64
65 /* Read the second word in case of limm */
66 word1 = *((uint16_t *)(addr + state->instr_len));
67 word0 = *((uint16_t *)(addr + state->instr_len + 2));
68 state->words[1] = (word1 << 16) | word0;
69
70 switch (state->major_opcode) {
71 case op_Bcc:
72 state->is_branch = 1;
73
74 /* unconditional branch s25, conditional branch s21 */
75 fieldA = (IS_BIT(state->words[0], 16)) ?
76 FIELD_s25(state->words[0]) :
77 FIELD_s21(state->words[0]);
78
79 state->delay_slot = IS_BIT(state->words[0], 5);
80 state->target = fieldA + (addr & ~0x3);
81 state->flow = direct_jump;
82 break;
83
84 case op_BLcc:
85 if (IS_BIT(state->words[0], 16)) {
86 /* Branch and Link*/
87 /* unconditional branch s25, conditional branch s21 */
88 fieldA = (IS_BIT(state->words[0], 17)) ?
89 (FIELD_s25(state->words[0]) & ~0x3) :
90 FIELD_s21(state->words[0]);
91
92 state->flow = direct_call;
93 } else {
94 /*Branch On Compare */
95 fieldA = FIELD_s9(state->words[0]) & ~0x3;
96 state->flow = direct_jump;
97 }
98
99 state->delay_slot = IS_BIT(state->words[0], 5);
100 state->target = fieldA + (addr & ~0x3);
101 state->is_branch = 1;
102 break;
103
104 case op_LD: /* LD<zz> a,[b,s9] */
105 state->write = 0;
106 state->di = BITS(state->words[0], 11, 11);
107 if (state->di)
108 break;
109 state->x = BITS(state->words[0], 6, 6);
110 state->zz = BITS(state->words[0], 7, 8);
111 state->aa = BITS(state->words[0], 9, 10);
112 state->wb_reg = FIELD_B(state->words[0]);
113 if (state->wb_reg == REG_LIMM) {
114 state->instr_len += 4;
115 state->aa = 0;
116 state->src1 = state->words[1];
117 } else {
118 state->src1 = get_reg(state->wb_reg, regs, cregs);
119 }
120 state->src2 = FIELD_s9(state->words[0]);
121 state->dest = FIELD_A(state->words[0]);
122 state->pref = (state->dest == REG_LIMM);
123 break;
124
125 case op_ST:
126 state->write = 1;
127 state->di = BITS(state->words[0], 5, 5);
128 if (state->di)
129 break;
130 state->aa = BITS(state->words[0], 3, 4);
131 state->zz = BITS(state->words[0], 1, 2);
132 state->src1 = FIELD_C(state->words[0]);
133 if (state->src1 == REG_LIMM) {
134 state->instr_len += 4;
135 state->src1 = state->words[1];
136 } else {
137 state->src1 = get_reg(state->src1, regs, cregs);
138 }
139 state->wb_reg = FIELD_B(state->words[0]);
140 if (state->wb_reg == REG_LIMM) {
141 state->aa = 0;
142 state->instr_len += 4;
143 state->src2 = state->words[1];
144 } else {
145 state->src2 = get_reg(state->wb_reg, regs, cregs);
146 }
147 state->src3 = FIELD_s9(state->words[0]);
148 break;
149
150 case op_MAJOR_4:
151 subopcode = MINOR_OPCODE(state->words[0]);
152 switch (subopcode) {
153 case 32: /* Jcc */
154 case 33: /* Jcc.D */
155 case 34: /* JLcc */
156 case 35: /* JLcc.D */
157 is_linked = 0;
158
159 if (subopcode == 33 || subopcode == 35)
160 state->delay_slot = 1;
161
162 if (subopcode == 34 || subopcode == 35)
163 is_linked = 1;
164
165 fieldCisReg = 0;
166 op_format = BITS(state->words[0], 22, 23);
167 if (op_format == 0 || ((op_format == 3) &&
168 (!IS_BIT(state->words[0], 5)))) {
169 fieldC = FIELD_C(state->words[0]);
170
171 if (fieldC == REG_LIMM) {
172 fieldC = state->words[1];
173 state->instr_len += 4;
174 } else {
175 fieldCisReg = 1;
176 }
177 } else if (op_format == 1 || ((op_format == 3)
178 && (IS_BIT(state->words[0], 5)))) {
179 fieldC = FIELD_C(state->words[0]);
180 } else {
181 /* op_format == 2 */
182 fieldC = FIELD_s12(state->words[0]);
183 }
184
185 if (!fieldCisReg) {
186 state->target = fieldC;
187 state->flow = is_linked ?
188 direct_call : direct_jump;
189 } else {
190 state->target = get_reg(fieldC, regs, cregs);
191 state->flow = is_linked ?
192 indirect_call : indirect_jump;
193 }
194 state->is_branch = 1;
195 break;
196
197 case 40: /* LPcc */
198 if (BITS(state->words[0], 22, 23) == 3) {
199 /* Conditional LPcc u7 */
200 fieldC = FIELD_C(state->words[0]);
201
202 fieldC = fieldC << 1;
203 fieldC += (addr & ~0x03);
204 state->is_branch = 1;
205 state->flow = direct_jump;
206 state->target = fieldC;
207 }
208 /* For Unconditional lp, next pc is the fall through
209 * which is updated */
210 break;
211
212 case 48 ... 55: /* LD a,[b,c] */
213 state->di = BITS(state->words[0], 15, 15);
214 if (state->di)
215 break;
216 state->x = BITS(state->words[0], 16, 16);
217 state->zz = BITS(state->words[0], 17, 18);
218 state->aa = BITS(state->words[0], 22, 23);
219 state->wb_reg = FIELD_B(state->words[0]);
220 if (state->wb_reg == REG_LIMM) {
221 state->instr_len += 4;
222 state->src1 = state->words[1];
223 } else {
224 state->src1 = get_reg(state->wb_reg, regs,
225 cregs);
226 }
227 state->src2 = FIELD_C(state->words[0]);
228 if (state->src2 == REG_LIMM) {
229 state->instr_len += 4;
230 state->src2 = state->words[1];
231 } else {
232 state->src2 = get_reg(state->src2, regs,
233 cregs);
234 }
235 state->dest = FIELD_A(state->words[0]);
236 if (state->dest == REG_LIMM)
237 state->pref = 1;
238 break;
239
240 case 10: /* MOV */
241 /* still need to check for limm to extract instr len */
242 /* MOV is special case because it only takes 2 args */
243 switch (BITS(state->words[0], 22, 23)) {
244 case 0: /* OP a,b,c */
245 if (FIELD_C(state->words[0]) == REG_LIMM)
246 state->instr_len += 4;
247 break;
248 case 1: /* OP a,b,u6 */
249 break;
250 case 2: /* OP b,b,s12 */
251 break;
252 case 3: /* OP.cc b,b,c/u6 */
253 if ((!IS_BIT(state->words[0], 5)) &&
254 (FIELD_C(state->words[0]) == REG_LIMM))
255 state->instr_len += 4;
256 break;
257 }
258 break;
259
260
261 default:
262 /* Not a Load, Jump or Loop instruction */
263 /* still need to check for limm to extract instr len */
264 switch (BITS(state->words[0], 22, 23)) {
265 case 0: /* OP a,b,c */
266 if ((FIELD_B(state->words[0]) == REG_LIMM) ||
267 (FIELD_C(state->words[0]) == REG_LIMM))
268 state->instr_len += 4;
269 break;
270 case 1: /* OP a,b,u6 */
271 break;
272 case 2: /* OP b,b,s12 */
273 break;
274 case 3: /* OP.cc b,b,c/u6 */
275 if ((!IS_BIT(state->words[0], 5)) &&
276 ((FIELD_B(state->words[0]) == REG_LIMM) ||
277 (FIELD_C(state->words[0]) == REG_LIMM)))
278 state->instr_len += 4;
279 break;
280 }
281 break;
282 }
283 break;
284
285 /* 16 Bit Instructions */
286 case op_LD_ADD: /* LD_S|LDB_S|LDW_S a,[b,c] */
287 state->zz = BITS(state->words[0], 3, 4);
288 state->src1 = get_reg(FIELD_S_B(state->words[0]), regs, cregs);
289 state->src2 = get_reg(FIELD_S_C(state->words[0]), regs, cregs);
290 state->dest = FIELD_S_A(state->words[0]);
291 break;
292
293 case op_ADD_MOV_CMP:
294 /* check for limm, ignore mov_s h,b (== mov_s 0,b) */
295 if ((BITS(state->words[0], 3, 4) < 3) &&
296 (FIELD_S_H(state->words[0]) == REG_LIMM))
297 state->instr_len += 4;
298 break;
299
300 case op_S:
301 subopcode = BITS(state->words[0], 5, 7);
302 switch (subopcode) {
303 case 0: /* j_s */
304 case 1: /* j_s.d */
305 case 2: /* jl_s */
306 case 3: /* jl_s.d */
307 state->target = get_reg(FIELD_S_B(state->words[0]),
308 regs, cregs);
309 state->delay_slot = subopcode & 1;
310 state->flow = (subopcode >= 2) ?
311 direct_call : indirect_jump;
312 break;
313 case 7:
314 switch (BITS(state->words[0], 8, 10)) {
315 case 4: /* jeq_s [blink] */
316 case 5: /* jne_s [blink] */
317 case 6: /* j_s [blink] */
318 case 7: /* j_s.d [blink] */
319 state->delay_slot = (subopcode == 7);
320 state->flow = indirect_jump;
321 state->target = get_reg(31, regs, cregs);
322 default:
323 break;
324 }
325 default:
326 break;
327 }
328 break;
329
330 case op_LD_S: /* LD_S c, [b, u7] */
331 state->src1 = get_reg(FIELD_S_B(state->words[0]), regs, cregs);
332 state->src2 = FIELD_S_u7(state->words[0]);
333 state->dest = FIELD_S_C(state->words[0]);
334 break;
335
336 case op_LDB_S:
337 case op_STB_S:
338 /* no further handling required as byte accesses should not
339 * cause an unaligned access exception */
340 state->zz = 1;
341 break;
342
343 case op_LDWX_S: /* LDWX_S c, [b, u6] */
344 state->x = 1;
345 /* intentional fall-through */
346
347 case op_LDW_S: /* LDW_S c, [b, u6] */
348 state->zz = 2;
349 state->src1 = get_reg(FIELD_S_B(state->words[0]), regs, cregs);
350 state->src2 = FIELD_S_u6(state->words[0]);
351 state->dest = FIELD_S_C(state->words[0]);
352 break;
353
354 case op_ST_S: /* ST_S c, [b, u7] */
355 state->write = 1;
356 state->src1 = get_reg(FIELD_S_C(state->words[0]), regs, cregs);
357 state->src2 = get_reg(FIELD_S_B(state->words[0]), regs, cregs);
358 state->src3 = FIELD_S_u7(state->words[0]);
359 break;
360
361 case op_STW_S: /* STW_S c,[b,u6] */
362 state->write = 1;
363 state->zz = 2;
364 state->src1 = get_reg(FIELD_S_C(state->words[0]), regs, cregs);
365 state->src2 = get_reg(FIELD_S_B(state->words[0]), regs, cregs);
366 state->src3 = FIELD_S_u6(state->words[0]);
367 break;
368
369 case op_SP: /* LD_S|LDB_S b,[sp,u7], ST_S|STB_S b,[sp,u7] */
370 /* note: we are ignoring possibility of:
371 * ADD_S, SUB_S, PUSH_S, POP_S as these should not
372 * cause unaliged exception anyway */
373 state->write = BITS(state->words[0], 6, 6);
374 state->zz = BITS(state->words[0], 5, 5);
375 if (state->zz)
376 break; /* byte accesses should not come here */
377 if (!state->write) {
378 state->src1 = get_reg(28, regs, cregs);
379 state->src2 = FIELD_S_u7(state->words[0]);
380 state->dest = FIELD_S_B(state->words[0]);
381 } else {
382 state->src1 = get_reg(FIELD_S_B(state->words[0]), regs,
383 cregs);
384 state->src2 = get_reg(28, regs, cregs);
385 state->src3 = FIELD_S_u7(state->words[0]);
386 }
387 break;
388
389 case op_GP: /* LD_S|LDB_S|LDW_S r0,[gp,s11/s9/s10] */
390 /* note: ADD_S r0, gp, s11 is ignored */
391 state->zz = BITS(state->words[0], 9, 10);
392 state->src1 = get_reg(26, regs, cregs);
393 state->src2 = state->zz ? FIELD_S_s10(state->words[0]) :
394 FIELD_S_s11(state->words[0]);
395 state->dest = 0;
396 break;
397
398 case op_Pcl: /* LD_S b,[pcl,u10] */
399 state->src1 = regs->ret & ~3;
400 state->src2 = FIELD_S_u10(state->words[0]);
401 state->dest = FIELD_S_B(state->words[0]);
402 break;
403
404 case op_BR_S:
405 state->target = FIELD_S_s8(state->words[0]) + (addr & ~0x03);
406 state->flow = direct_jump;
407 state->is_branch = 1;
408 break;
409
410 case op_B_S:
411 fieldA = (BITS(state->words[0], 9, 10) == 3) ?
412 FIELD_S_s7(state->words[0]) :
413 FIELD_S_s10(state->words[0]);
414 state->target = fieldA + (addr & ~0x03);
415 state->flow = direct_jump;
416 state->is_branch = 1;
417 break;
418
419 case op_BL_S:
420 state->target = FIELD_S_s13(state->words[0]) + (addr & ~0x03);
421 state->flow = direct_call;
422 state->is_branch = 1;
423 break;
424
425 default:
426 break;
427 }
428
429 if (bytes_not_copied <= (8 - state->instr_len))
430 return;
431
432 fault: state->fault = 1;
433 }
434
435 long __kprobes get_reg(int reg, struct pt_regs *regs,
436 struct callee_regs *cregs)
437 {
438 long *p;
439
440 if (reg <= 12) {
441 p = &regs->r0;
442 return p[-reg];
443 }
444
445 if (cregs && (reg <= 25)) {
446 p = &cregs->r13;
447 return p[13-reg];
448 }
449
450 if (reg == 26)
451 return regs->r26;
452 if (reg == 27)
453 return regs->fp;
454 if (reg == 28)
455 return regs->sp;
456 if (reg == 31)
457 return regs->blink;
458
459 return 0;
460 }
461
462 void __kprobes set_reg(int reg, long val, struct pt_regs *regs,
463 struct callee_regs *cregs)
464 {
465 long *p;
466
467 switch (reg) {
468 case 0 ... 12:
469 p = &regs->r0;
470 p[-reg] = val;
471 break;
472 case 13 ... 25:
473 if (cregs) {
474 p = &cregs->r13;
475 p[13-reg] = val;
476 }
477 break;
478 case 26:
479 regs->r26 = val;
480 break;
481 case 27:
482 regs->fp = val;
483 break;
484 case 28:
485 regs->sp = val;
486 break;
487 case 31:
488 regs->blink = val;
489 break;
490 default:
491 break;
492 }
493 }
494
495 /*
496 * Disassembles the insn at @pc and sets @next_pc to next PC (which could be
497 * @pc +2/4/6 (ARCompact ISA allows free intermixing of 16/32 bit insns).
498 *
499 * If @pc is a branch
500 * -@tgt_if_br is set to branch target.
501 * -If branch has delay slot, @next_pc updated with actual next PC.
502 */
503 int __kprobes disasm_next_pc(unsigned long pc, struct pt_regs *regs,
504 struct callee_regs *cregs,
505 unsigned long *next_pc, unsigned long *tgt_if_br)
506 {
507 struct disasm_state instr;
508
509 memset(&instr, 0, sizeof(struct disasm_state));
510 disasm_instr(pc, &instr, 0, regs, cregs);
511
512 *next_pc = pc + instr.instr_len;
513
514 /* Instruction with possible two targets branch, jump and loop */
515 if (instr.is_branch)
516 *tgt_if_br = instr.target;
517
518 /* For the instructions with delay slots, the fall through is the
519 * instruction following the instruction in delay slot.
520 */
521 if (instr.delay_slot) {
522 struct disasm_state instr_d;
523
524 disasm_instr(*next_pc, &instr_d, 0, regs, cregs);
525
526 *next_pc += instr_d.instr_len;
527 }
528
529 /* Zero Overhead Loop - end of the loop */
530 if (!(regs->status32 & STATUS32_L) && (*next_pc == regs->lp_end)
531 && (regs->lp_count > 1)) {
532 *next_pc = regs->lp_start;
533 }
534
535 return instr.is_branch;
536 }
537
538 #endif /* CONFIG_KGDB || CONFIG_ARC_MISALIGN_ACCESS || CONFIG_KPROBES */
Linux with added FPC-III support