dasm_x86.h (15944B)
1 /* 2 ** DynASM x86 encoding engine. 3 ** Copyright (C) 2005-2016 Mike Pall. All rights reserved. 4 ** Released under the MIT license. See dynasm.lua for full copyright notice. 5 */ 6 7 #include <stddef.h> 8 #include <stdarg.h> 9 #include <string.h> 10 #include <stdlib.h> 11 12 #define DASM_ARCH "x86" 13 14 #ifndef DASM_EXTERN 15 #define DASM_EXTERN(a,b,c,d) 0 16 #endif 17 18 /* Action definitions. DASM_STOP must be 255. */ 19 enum { 20 DASM_DISP = 233, 21 DASM_IMM_S, DASM_IMM_B, DASM_IMM_W, DASM_IMM_D, DASM_IMM_WB, DASM_IMM_DB, 22 DASM_VREG, DASM_SPACE, DASM_SETLABEL, DASM_REL_A, DASM_REL_LG, DASM_REL_PC, 23 DASM_IMM_LG, DASM_IMM_PC, DASM_LABEL_LG, DASM_LABEL_PC, DASM_ALIGN, 24 DASM_EXTERN, DASM_ESC, DASM_MARK, DASM_SECTION, DASM_STOP 25 }; 26 27 /* Maximum number of section buffer positions for a single dasm_put() call. */ 28 #define DASM_MAXSECPOS 25 29 30 /* DynASM encoder status codes. Action list offset or number are or'ed in. */ 31 #define DASM_S_OK 0x00000000 32 #define DASM_S_NOMEM 0x01000000 33 #define DASM_S_PHASE 0x02000000 34 #define DASM_S_MATCH_SEC 0x03000000 35 #define DASM_S_RANGE_I 0x11000000 36 #define DASM_S_RANGE_SEC 0x12000000 37 #define DASM_S_RANGE_LG 0x13000000 38 #define DASM_S_RANGE_PC 0x14000000 39 #define DASM_S_RANGE_VREG 0x15000000 40 #define DASM_S_UNDEF_L 0x21000000 41 #define DASM_S_UNDEF_PC 0x22000000 42 43 /* Macros to convert positions (8 bit section + 24 bit index). */ 44 #define DASM_POS2IDX(pos) ((pos)&0x00ffffff) 45 #define DASM_POS2BIAS(pos) ((pos)&0xff000000) 46 #define DASM_SEC2POS(sec) ((sec)<<24) 47 #define DASM_POS2SEC(pos) ((pos)>>24) 48 #define DASM_POS2PTR(D, pos) (D->sections[DASM_POS2SEC(pos)].rbuf + (pos)) 49 50 /* Action list type. */ 51 typedef const unsigned char *dasm_ActList; 52 53 /* Per-section structure. */ 54 typedef struct dasm_Section { 55 int *rbuf; /* Biased buffer pointer (negative section bias). */ 56 int *buf; /* True buffer pointer. */ 57 size_t bsize; /* Buffer size in bytes. */ 58 int pos; /* Biased buffer position. */ 59 int epos; /* End of biased buffer position - max single put. */ 60 int ofs; /* Byte offset into section. */ 61 } dasm_Section; 62 63 /* Core structure holding the DynASM encoding state. */ 64 struct dasm_State { 65 size_t psize; /* Allocated size of this structure. */ 66 dasm_ActList actionlist; /* Current actionlist pointer. */ 67 int *lglabels; /* Local/global chain/pos ptrs. */ 68 size_t lgsize; 69 int *pclabels; /* PC label chains/pos ptrs. */ 70 size_t pcsize; 71 void **globals; /* Array of globals (bias -10). */ 72 dasm_Section *section; /* Pointer to active section. */ 73 size_t codesize; /* Total size of all code sections. */ 74 int maxsection; /* 0 <= sectionidx < maxsection. */ 75 int status; /* Status code. */ 76 dasm_Section sections[1]; /* All sections. Alloc-extended. */ 77 }; 78 79 /* The size of the core structure depends on the max. number of sections. */ 80 #define DASM_PSZ(ms) (sizeof(dasm_State)+(ms-1)*sizeof(dasm_Section)) 81 82 83 /* Initialize DynASM state. */ 84 void dasm_init(Dst_DECL, int maxsection) 85 { 86 dasm_State *D; 87 size_t psz = 0; 88 int i; 89 Dst_REF = NULL; 90 DASM_M_GROW(Dst, struct dasm_State, Dst_REF, psz, DASM_PSZ(maxsection)); 91 D = Dst_REF; 92 D->psize = psz; 93 D->lglabels = NULL; 94 D->lgsize = 0; 95 D->pclabels = NULL; 96 D->pcsize = 0; 97 D->globals = NULL; 98 D->maxsection = maxsection; 99 for (i = 0; i < maxsection; i++) { 100 D->sections[i].buf = NULL; /* Need this for pass3. */ 101 D->sections[i].rbuf = D->sections[i].buf - DASM_SEC2POS(i); 102 D->sections[i].bsize = 0; 103 D->sections[i].epos = 0; /* Wrong, but is recalculated after resize. */ 104 } 105 } 106 107 /* Free DynASM state. */ 108 void dasm_free(Dst_DECL) 109 { 110 dasm_State *D = Dst_REF; 111 int i; 112 for (i = 0; i < D->maxsection; i++) 113 if (D->sections[i].buf) 114 DASM_M_FREE(Dst, D->sections[i].buf, D->sections[i].bsize); 115 if (D->pclabels) DASM_M_FREE(Dst, D->pclabels, D->pcsize); 116 if (D->lglabels) DASM_M_FREE(Dst, D->lglabels, D->lgsize); 117 DASM_M_FREE(Dst, D, D->psize); 118 } 119 120 /* Setup global label array. Must be called before dasm_setup(). */ 121 void dasm_setupglobal(Dst_DECL, void **gl, unsigned int maxgl) 122 { 123 dasm_State *D = Dst_REF; 124 D->globals = gl - 10; /* Negative bias to compensate for locals. */ 125 DASM_M_GROW(Dst, int, D->lglabels, D->lgsize, (10+maxgl)*sizeof(int)); 126 } 127 128 /* Grow PC label array. Can be called after dasm_setup(), too. */ 129 void dasm_growpc(Dst_DECL, unsigned int maxpc) 130 { 131 dasm_State *D = Dst_REF; 132 size_t osz = D->pcsize; 133 DASM_M_GROW(Dst, int, D->pclabels, D->pcsize, maxpc*sizeof(int)); 134 memset((void *)(((unsigned char *)D->pclabels)+osz), 0, D->pcsize-osz); 135 } 136 137 /* Setup encoder. */ 138 void dasm_setup(Dst_DECL, const void *actionlist) 139 { 140 dasm_State *D = Dst_REF; 141 int i; 142 D->actionlist = (dasm_ActList)actionlist; 143 D->status = DASM_S_OK; 144 D->section = &D->sections[0]; 145 memset((void *)D->lglabels, 0, D->lgsize); 146 if (D->pclabels) memset((void *)D->pclabels, 0, D->pcsize); 147 for (i = 0; i < D->maxsection; i++) { 148 D->sections[i].pos = DASM_SEC2POS(i); 149 D->sections[i].ofs = 0; 150 } 151 } 152 153 154 #ifdef DASM_CHECKS 155 #define CK(x, st) \ 156 do { if (!(x)) { \ 157 D->status = DASM_S_##st|(int)(p-D->actionlist-1); return; } } while (0) 158 #define CKPL(kind, st) \ 159 do { if ((size_t)((char *)pl-(char *)D->kind##labels) >= D->kind##size) { \ 160 D->status=DASM_S_RANGE_##st|(int)(p-D->actionlist-1); return; } } while (0) 161 #else 162 #define CK(x, st) ((void)0) 163 #define CKPL(kind, st) ((void)0) 164 #endif 165 166 /* Pass 1: Store actions and args, link branches/labels, estimate offsets. */ 167 void dasm_put(Dst_DECL, int start, ...) 168 { 169 va_list ap; 170 dasm_State *D = Dst_REF; 171 dasm_ActList p = D->actionlist + start; 172 dasm_Section *sec = D->section; 173 int pos = sec->pos, ofs = sec->ofs, mrm = -1; 174 int *b; 175 176 if (pos >= sec->epos) { 177 DASM_M_GROW(Dst, int, sec->buf, sec->bsize, 178 sec->bsize + 2*DASM_MAXSECPOS*sizeof(int)); 179 sec->rbuf = sec->buf - DASM_POS2BIAS(pos); 180 sec->epos = (int)sec->bsize/sizeof(int) - DASM_MAXSECPOS+DASM_POS2BIAS(pos); 181 } 182 183 b = sec->rbuf; 184 b[pos++] = start; 185 186 va_start(ap, start); 187 while (1) { 188 int action = *p++; 189 if (action < DASM_DISP) { 190 ofs++; 191 } else if (action <= DASM_REL_A) { 192 int n = va_arg(ap, int); 193 b[pos++] = n; 194 switch (action) { 195 case DASM_DISP: 196 if (n == 0) { if (mrm < 0) mrm = p[-2]; if ((mrm&7) != 5) break; } 197 case DASM_IMM_DB: if (((n+128)&-256) == 0) goto ob; 198 case DASM_REL_A: /* Assumes ptrdiff_t is int. !x64 */ 199 case DASM_IMM_D: ofs += 4; break; 200 case DASM_IMM_S: CK(((n+128)&-256) == 0, RANGE_I); goto ob; 201 case DASM_IMM_B: CK((n&-256) == 0, RANGE_I); ob: ofs++; break; 202 case DASM_IMM_WB: if (((n+128)&-256) == 0) goto ob; 203 case DASM_IMM_W: CK((n&-65536) == 0, RANGE_I); ofs += 2; break; 204 case DASM_SPACE: p++; ofs += n; break; 205 case DASM_SETLABEL: b[pos-2] = -0x40000000; break; /* Neg. label ofs. */ 206 case DASM_VREG: CK((n&-16) == 0 && (n != 4 || (*p>>5) != 2), RANGE_VREG); 207 if (*p < 0x40 && p[1] == DASM_DISP) mrm = n; 208 if (*p < 0x20 && (n&7) == 4) ofs++; 209 switch ((*p++ >> 3) & 3) { 210 case 3: n |= b[pos-3]; 211 case 2: n |= b[pos-2]; 212 case 1: if (n <= 7) { b[pos-1] |= 0x10; ofs--; } 213 } 214 continue; 215 } 216 mrm = -1; 217 } else { 218 int *pl, n; 219 switch (action) { 220 case DASM_REL_LG: 221 case DASM_IMM_LG: 222 n = *p++; pl = D->lglabels + n; 223 /* Bkwd rel or global. */ 224 if (n <= 246) { CK(n>=10||*pl<0, RANGE_LG); CKPL(lg, LG); goto putrel; } 225 pl -= 246; n = *pl; 226 if (n < 0) n = 0; /* Start new chain for fwd rel if label exists. */ 227 goto linkrel; 228 case DASM_REL_PC: 229 case DASM_IMM_PC: pl = D->pclabels + va_arg(ap, int); CKPL(pc, PC); 230 putrel: 231 n = *pl; 232 if (n < 0) { /* Label exists. Get label pos and store it. */ 233 b[pos] = -n; 234 } else { 235 linkrel: 236 b[pos] = n; /* Else link to rel chain, anchored at label. */ 237 *pl = pos; 238 } 239 pos++; 240 ofs += 4; /* Maximum offset needed. */ 241 if (action == DASM_REL_LG || action == DASM_REL_PC) 242 b[pos++] = ofs; /* Store pass1 offset estimate. */ 243 break; 244 case DASM_LABEL_LG: pl = D->lglabels + *p++; CKPL(lg, LG); goto putlabel; 245 case DASM_LABEL_PC: pl = D->pclabels + va_arg(ap, int); CKPL(pc, PC); 246 putlabel: 247 n = *pl; /* n > 0: Collapse rel chain and replace with label pos. */ 248 while (n > 0) { int *pb = DASM_POS2PTR(D, n); n = *pb; *pb = pos; } 249 *pl = -pos; /* Label exists now. */ 250 b[pos++] = ofs; /* Store pass1 offset estimate. */ 251 break; 252 case DASM_ALIGN: 253 ofs += *p++; /* Maximum alignment needed (arg is 2**n-1). */ 254 b[pos++] = ofs; /* Store pass1 offset estimate. */ 255 break; 256 case DASM_EXTERN: p += 2; ofs += 4; break; 257 case DASM_ESC: p++; ofs++; break; 258 case DASM_MARK: mrm = p[-2]; break; 259 case DASM_SECTION: 260 n = *p; CK(n < D->maxsection, RANGE_SEC); D->section = &D->sections[n]; 261 case DASM_STOP: goto stop; 262 } 263 } 264 } 265 stop: 266 va_end(ap); 267 sec->pos = pos; 268 sec->ofs = ofs; 269 } 270 #undef CK 271 272 /* Pass 2: Link sections, shrink branches/aligns, fix label offsets. */ 273 int dasm_link(Dst_DECL, size_t *szp) 274 { 275 dasm_State *D = Dst_REF; 276 int secnum; 277 int ofs = 0; 278 279 #ifdef DASM_CHECKS 280 *szp = 0; 281 if (D->status != DASM_S_OK) return D->status; 282 { 283 int pc; 284 for (pc = 0; pc*sizeof(int) < D->pcsize; pc++) 285 if (D->pclabels[pc] > 0) return DASM_S_UNDEF_PC|pc; 286 } 287 #endif 288 289 { /* Handle globals not defined in this translation unit. */ 290 int idx; 291 for (idx = 10; idx*sizeof(int) < D->lgsize; idx++) { 292 int n = D->lglabels[idx]; 293 /* Undefined label: Collapse rel chain and replace with marker (< 0). */ 294 while (n > 0) { int *pb = DASM_POS2PTR(D, n); n = *pb; *pb = -idx; } 295 } 296 } 297 298 /* Combine all code sections. No support for data sections (yet). */ 299 for (secnum = 0; secnum < D->maxsection; secnum++) { 300 dasm_Section *sec = D->sections + secnum; 301 int *b = sec->rbuf; 302 int pos = DASM_SEC2POS(secnum); 303 int lastpos = sec->pos; 304 305 while (pos != lastpos) { 306 dasm_ActList p = D->actionlist + b[pos++]; 307 while (1) { 308 int op, action = *p++; 309 switch (action) { 310 case DASM_REL_LG: p++; op = p[-3]; goto rel_pc; 311 case DASM_REL_PC: op = p[-2]; rel_pc: { 312 int shrink = op == 0xe9 ? 3 : ((op&0xf0) == 0x80 ? 4 : 0); 313 if (shrink) { /* Shrinkable branch opcode? */ 314 int lofs, lpos = b[pos]; 315 if (lpos < 0) goto noshrink; /* Ext global? */ 316 lofs = *DASM_POS2PTR(D, lpos); 317 if (lpos > pos) { /* Fwd label: add cumulative section offsets. */ 318 int i; 319 for (i = secnum; i < DASM_POS2SEC(lpos); i++) 320 lofs += D->sections[i].ofs; 321 } else { 322 lofs -= ofs; /* Bkwd label: unfix offset. */ 323 } 324 lofs -= b[pos+1]; /* Short branch ok? */ 325 if (lofs >= -128-shrink && lofs <= 127) ofs -= shrink; /* Yes. */ 326 else { noshrink: shrink = 0; } /* No, cannot shrink op. */ 327 } 328 b[pos+1] = shrink; 329 pos += 2; 330 break; 331 } 332 case DASM_SPACE: case DASM_IMM_LG: case DASM_VREG: p++; 333 case DASM_DISP: case DASM_IMM_S: case DASM_IMM_B: case DASM_IMM_W: 334 case DASM_IMM_D: case DASM_IMM_WB: case DASM_IMM_DB: 335 case DASM_SETLABEL: case DASM_REL_A: case DASM_IMM_PC: pos++; break; 336 case DASM_LABEL_LG: p++; 337 case DASM_LABEL_PC: b[pos++] += ofs; break; /* Fix label offset. */ 338 case DASM_ALIGN: ofs -= (b[pos++]+ofs)&*p++; break; /* Adjust ofs. */ 339 case DASM_EXTERN: p += 2; break; 340 case DASM_ESC: p++; break; 341 case DASM_MARK: break; 342 case DASM_SECTION: case DASM_STOP: goto stop; 343 } 344 } 345 stop: (void)0; 346 } 347 ofs += sec->ofs; /* Next section starts right after current section. */ 348 } 349 350 D->codesize = ofs; /* Total size of all code sections */ 351 *szp = ofs; 352 return DASM_S_OK; 353 } 354 355 #define dasmb(x) *cp++ = (unsigned char)(x) 356 #ifndef DASM_ALIGNED_WRITES 357 #define dasmw(x) \ 358 do { *((unsigned short *)cp) = (unsigned short)(x); cp+=2; } while (0) 359 #define dasmd(x) \ 360 do { *((unsigned int *)cp) = (unsigned int)(x); cp+=4; } while (0) 361 #else 362 #define dasmw(x) do { dasmb(x); dasmb((x)>>8); } while (0) 363 #define dasmd(x) do { dasmw(x); dasmw((x)>>16); } while (0) 364 #endif 365 366 /* Pass 3: Encode sections. */ 367 int dasm_encode(Dst_DECL, void *buffer) 368 { 369 dasm_State *D = Dst_REF; 370 unsigned char *base = (unsigned char *)buffer; 371 unsigned char *cp = base; 372 int secnum; 373 374 /* Encode all code sections. No support for data sections (yet). */ 375 for (secnum = 0; secnum < D->maxsection; secnum++) { 376 dasm_Section *sec = D->sections + secnum; 377 int *b = sec->buf; 378 int *endb = sec->rbuf + sec->pos; 379 380 while (b != endb) { 381 dasm_ActList p = D->actionlist + *b++; 382 unsigned char *mark = NULL; 383 while (1) { 384 int action = *p++; 385 int n = (action >= DASM_DISP && action <= DASM_ALIGN) ? *b++ : 0; 386 switch (action) { 387 case DASM_DISP: if (!mark) mark = cp; { 388 unsigned char *mm = mark; 389 if (*p != DASM_IMM_DB && *p != DASM_IMM_WB) mark = NULL; 390 if (n == 0) { int mrm = mm[-1]&7; if (mrm == 4) mrm = mm[0]&7; 391 if (mrm != 5) { mm[-1] -= 0x80; break; } } 392 if (((n+128) & -256) != 0) goto wd; else mm[-1] -= 0x40; 393 } 394 case DASM_IMM_S: case DASM_IMM_B: wb: dasmb(n); break; 395 case DASM_IMM_DB: if (((n+128)&-256) == 0) { 396 db: if (!mark) mark = cp; mark[-2] += 2; mark = NULL; goto wb; 397 } else mark = NULL; 398 case DASM_IMM_D: wd: dasmd(n); break; 399 case DASM_IMM_WB: if (((n+128)&-256) == 0) goto db; else mark = NULL; 400 case DASM_IMM_W: dasmw(n); break; 401 case DASM_VREG: { 402 int t = *p++; 403 unsigned char *ex = cp - (t&7); 404 if ((n & 8) && t < 0xa0) { 405 if (*ex & 0x80) ex[1] ^= 0x20 << (t>>6); else *ex ^= 1 << (t>>6); 406 n &= 7; 407 } else if (n & 0x10) { 408 if (*ex & 0x80) { 409 *ex = 0xc5; ex[1] = (ex[1] & 0x80) | ex[2]; ex += 2; 410 } 411 while (++ex < cp) ex[-1] = *ex; 412 if (mark) mark--; 413 cp--; 414 n &= 7; 415 } 416 if (t >= 0xc0) n <<= 4; 417 else if (t >= 0x40) n <<= 3; 418 else if (n == 4 && t < 0x20) { cp[-1] ^= n; *cp++ = 0x20; } 419 cp[-1] ^= n; 420 break; 421 } 422 case DASM_REL_LG: p++; if (n >= 0) goto rel_pc; 423 b++; n = (int)(ptrdiff_t)D->globals[-n]; 424 case DASM_REL_A: rel_a: n -= (int)(ptrdiff_t)(cp+4); goto wd; /* !x64 */ 425 case DASM_REL_PC: rel_pc: { 426 int shrink = *b++; 427 int *pb = DASM_POS2PTR(D, n); if (*pb < 0) { n = pb[1]; goto rel_a; } 428 n = *pb - ((int)(cp-base) + 4-shrink); 429 if (shrink == 0) goto wd; 430 if (shrink == 4) { cp--; cp[-1] = *cp-0x10; } else cp[-1] = 0xeb; 431 goto wb; 432 } 433 case DASM_IMM_LG: 434 p++; if (n < 0) { n = (int)(ptrdiff_t)D->globals[-n]; goto wd; } 435 case DASM_IMM_PC: { 436 int *pb = DASM_POS2PTR(D, n); 437 n = *pb < 0 ? pb[1] : (*pb + (int)(ptrdiff_t)base); 438 goto wd; 439 } 440 case DASM_LABEL_LG: { 441 int idx = *p++; 442 if (idx >= 10) 443 D->globals[idx] = (void *)(base + (*p == DASM_SETLABEL ? *b : n)); 444 break; 445 } 446 case DASM_LABEL_PC: case DASM_SETLABEL: break; 447 case DASM_SPACE: { int fill = *p++; while (n--) *cp++ = fill; break; } 448 case DASM_ALIGN: 449 n = *p++; 450 while (((cp-base) & n)) *cp++ = 0x90; /* nop */ 451 break; 452 case DASM_EXTERN: n = DASM_EXTERN(Dst, cp, p[1], *p); p += 2; goto wd; 453 case DASM_MARK: mark = cp; break; 454 case DASM_ESC: action = *p++; 455 default: *cp++ = action; break; 456 case DASM_SECTION: case DASM_STOP: goto stop; 457 } 458 } 459 stop: (void)0; 460 } 461 } 462 463 if (base + D->codesize != cp) /* Check for phase errors. */ 464 return DASM_S_PHASE; 465 return DASM_S_OK; 466 } 467 468 /* Get PC label offset. */ 469 int dasm_getpclabel(Dst_DECL, unsigned int pc) 470 { 471 dasm_State *D = Dst_REF; 472 if (pc*sizeof(int) < D->pcsize) { 473 int pos = D->pclabels[pc]; 474 if (pos < 0) return *DASM_POS2PTR(D, -pos); 475 if (pos > 0) return -1; /* Undefined. */ 476 } 477 return -2; /* Unused or out of range. */ 478 } 479 480 #ifdef DASM_CHECKS 481 /* Optional sanity checker to call between isolated encoding steps. */ 482 int dasm_checkstep(Dst_DECL, int secmatch) 483 { 484 dasm_State *D = Dst_REF; 485 if (D->status == DASM_S_OK) { 486 int i; 487 for (i = 1; i <= 9; i++) { 488 if (D->lglabels[i] > 0) { D->status = DASM_S_UNDEF_L|i; break; } 489 D->lglabels[i] = 0; 490 } 491 } 492 if (D->status == DASM_S_OK && secmatch >= 0 && 493 D->section != &D->sections[secmatch]) 494 D->status = DASM_S_MATCH_SEC|(int)(D->section-D->sections); 495 return D->status; 496 } 497 #endif 498