dynasm/dasm_arm.h

   1 /*
   2 ** DynASM ARM encoding engine.
   3 ** Copyright (C) 2005-2023 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               "arm"
  13
  14 #ifndef DASM_EXTERN
  15 #define DASM_EXTERN(a,b,c,d)    0
  16 #endif
  17
  18 /* Action definitions. */
  19 enum {
  20   DASM_STOP, DASM_SECTION, DASM_ESC, DASM_REL_EXT,
  21   /* The following actions need a buffer position. */
  22   DASM_ALIGN, DASM_REL_LG, DASM_LABEL_LG,
  23   /* The following actions also have an argument. */
  24   DASM_REL_PC, DASM_LABEL_PC,
  25   DASM_IMM, DASM_IMM12, DASM_IMM16, DASM_IMML8, DASM_IMML12, DASM_IMMV8,
  26   DASM__MAX
  27 };
  28
  29 /* Maximum number of section buffer positions for a single dasm_put() call. */
  30 #define DASM_MAXSECPOS          25
  31
  32 /* DynASM encoder status codes. Action list offset or number are or'ed in. */
  33 #define DASM_S_OK               0x00000000
  34 #define DASM_S_NOMEM            0x01000000
  35 #define DASM_S_PHASE            0x02000000
  36 #define DASM_S_MATCH_SEC        0x03000000
  37 #define DASM_S_RANGE_I          0x11000000
  38 #define DASM_S_RANGE_SEC        0x12000000
  39 #define DASM_S_RANGE_LG         0x13000000
  40 #define DASM_S_RANGE_PC         0x14000000
  41 #define DASM_S_RANGE_REL        0x15000000
  42 #define DASM_S_UNDEF_LG         0x21000000
  43 #define DASM_S_UNDEF_PC         0x22000000
  44
  45 /* Macros to convert positions (8 bit section + 24 bit index). */
  46 #define DASM_POS2IDX(pos)       ((pos)&0x00ffffff)
  47 #define DASM_POS2BIAS(pos)      ((pos)&0xff000000)
  48 #define DASM_SEC2POS(sec)       ((sec)<<24)
  49 #define DASM_POS2SEC(pos)       ((pos)>>24)
  50 #define DASM_POS2PTR(D, pos)    (D->sections[DASM_POS2SEC(pos)].rbuf + (pos))
  51
  52 /* Action list type. */
  53 typedef const unsigned int *dasm_ActList;
  54
  55 /* Per-section structure. */
  56 typedef struct dasm_Section {
  57   int *rbuf;            /* Biased buffer pointer (negative section bias). */
  58   int *buf;             /* True buffer pointer. */
  59   size_t bsize;         /* Buffer size in bytes. */
  60   int pos;              /* Biased buffer position. */
  61   int epos;             /* End of biased buffer position - max single put. */
  62   int ofs;              /* Byte offset into section. */
  63 } dasm_Section;
  64
  65 /* Core structure holding the DynASM encoding state. */
  66 struct dasm_State {
  67   size_t psize;                 /* Allocated size of this structure. */
  68   dasm_ActList actionlist;      /* Current actionlist pointer. */
  69   int *lglabels;                /* Local/global chain/pos ptrs. */
  70   size_t lgsize;
  71   int *pclabels;                /* PC label chains/pos ptrs. */
  72   size_t pcsize;
  73   void **globals;               /* Array of globals. */
  74   dasm_Section *section;        /* Pointer to active section. */
  75   size_t codesize;              /* Total size of all code sections. */
  76   int maxsection;               /* 0 <= sectionidx < maxsection. */
  77   int status;                   /* Status code. */
  78   dasm_Section sections[1];     /* All sections. Alloc-extended. */
  79 };
  80
  81 /* The size of the core structure depends on the max. number of sections. */
  82 #define DASM_PSZ(ms)    (sizeof(dasm_State)+(ms-1)*sizeof(dasm_Section))
  83
  84
  85 /* Initialize DynASM state. */
  86 void dasm_init(Dst_DECL, int maxsection)
  87 {
  88   dasm_State *D;
  89   size_t psz = 0;
  90   Dst_REF = NULL;
  91   DASM_M_GROW(Dst, struct dasm_State, Dst_REF, psz, DASM_PSZ(maxsection));
  92   D = Dst_REF;
  93   D->psize = psz;
  94   D->lglabels = NULL;
  95   D->lgsize = 0;
  96   D->pclabels = NULL;
  97   D->pcsize = 0;
  98   D->globals = NULL;
  99   D->maxsection = maxsection;
 100   memset((void *)D->sections, 0, maxsection * sizeof(dasm_Section));
 101 }
 102
 103 /* Free DynASM state. */
 104 void dasm_free(Dst_DECL)
 105 {
 106   dasm_State *D = Dst_REF;
 107   int i;
 108   for (i = 0; i < D->maxsection; i++)
 109     if (D->sections[i].buf)
 110       DASM_M_FREE(Dst, D->sections[i].buf, D->sections[i].bsize);
 111   if (D->pclabels) DASM_M_FREE(Dst, D->pclabels, D->pcsize);
 112   if (D->lglabels) DASM_M_FREE(Dst, D->lglabels, D->lgsize);
 113   DASM_M_FREE(Dst, D, D->psize);
 114 }
 115
 116 /* Setup global label array. Must be called before dasm_setup(). */
 117 void dasm_setupglobal(Dst_DECL, void **gl, unsigned int maxgl)
 118 {
 119   dasm_State *D = Dst_REF;
 120   D->globals = gl;
 121   DASM_M_GROW(Dst, int, D->lglabels, D->lgsize, (10+maxgl)*sizeof(int));
 122 }
 123
 124 /* Grow PC label array. Can be called after dasm_setup(), too. */
 125 void dasm_growpc(Dst_DECL, unsigned int maxpc)
 126 {
 127   dasm_State *D = Dst_REF;
 128   size_t osz = D->pcsize;
 129   DASM_M_GROW(Dst, int, D->pclabels, D->pcsize, maxpc*sizeof(int));
 130   memset((void *)(((unsigned char *)D->pclabels)+osz), 0, D->pcsize-osz);
 131 }
 132
 133 /* Setup encoder. */
 134 void dasm_setup(Dst_DECL, const void *actionlist)
 135 {
 136   dasm_State *D = Dst_REF;
 137   int i;
 138   D->actionlist = (dasm_ActList)actionlist;
 139   D->status = DASM_S_OK;
 140   D->section = &D->sections[0];
 141   memset((void *)D->lglabels, 0, D->lgsize);
 142   if (D->pclabels) memset((void *)D->pclabels, 0, D->pcsize);
 143   for (i = 0; i < D->maxsection; i++) {
 144     D->sections[i].pos = DASM_SEC2POS(i);
 145     D->sections[i].rbuf = D->sections[i].buf - D->sections[i].pos;
 146     D->sections[i].ofs = 0;
 147   }
 148 }
 149
 150
 151 #ifdef DASM_CHECKS
 152 #define CK(x, st) \
 153   do { if (!(x)) { \
 154     D->status = DASM_S_##st|(p-D->actionlist-1); return; } } while (0)
 155 #define CKPL(kind, st) \
 156   do { if ((size_t)((char *)pl-(char *)D->kind##labels) >= D->kind##size) { \
 157     D->status = DASM_S_RANGE_##st|(p-D->actionlist-1); return; } } while (0)
 158 #else
 159 #define CK(x, st)       ((void)0)
 160 #define CKPL(kind, st)  ((void)0)
 161 #endif
 162
 163 static int dasm_imm12(unsigned int n)
 164 {
 165   int i;
 166   for (i = 0; i < 16; i++, n = (n << 2) | (n >> 30))
 167     if (n <= 255) return (int)(n + (i << 8));
 168   return -1;
 169 }
 170
 171 /* Pass 1: Store actions and args, link branches/labels, estimate offsets. */
 172 void dasm_put(Dst_DECL, int start, ...)
 173 {
 174   va_list ap;
 175   dasm_State *D = Dst_REF;
 176   dasm_ActList p = D->actionlist + start;
 177   dasm_Section *sec = D->section;
 178   int pos = sec->pos, ofs = sec->ofs;
 179   int *b;
 180
 181   if (pos >= sec->epos) {
 182     DASM_M_GROW(Dst, int, sec->buf, sec->bsize,
 183       sec->bsize + 2*DASM_MAXSECPOS*sizeof(int));
 184     sec->rbuf = sec->buf - DASM_POS2BIAS(pos);
 185     sec->epos = (int)sec->bsize/sizeof(int) - DASM_MAXSECPOS+DASM_POS2BIAS(pos);
 186   }
 187
 188   b = sec->rbuf;
 189   b[pos++] = start;
 190
 191   va_start(ap, start);
 192   while (1) {
 193     unsigned int ins = *p++;
 194     unsigned int action = (ins >> 16);
 195     if (action >= DASM__MAX) {
 196       ofs += 4;
 197     } else {
 198       int *pl, n = action >= DASM_REL_PC ? va_arg(ap, int) : 0;
 199       switch (action) {
 200       case DASM_STOP: goto stop;
 201       case DASM_SECTION:
 202         n = (ins & 255); CK(n < D->maxsection, RANGE_SEC);
 203         D->section = &D->sections[n]; goto stop;
 204       case DASM_ESC: p++; ofs += 4; break;
 205       case DASM_REL_EXT: break;
 206       case DASM_ALIGN: ofs += (ins & 255); b[pos++] = ofs; break;
 207       case DASM_REL_LG:
 208         n = (ins & 2047) - 10; pl = D->lglabels + n;
 209         /* Bkwd rel or global. */
 210         if (n >= 0) { CK(n>=10||*pl<0, RANGE_LG); CKPL(lg, LG); goto putrel; }
 211         pl += 10; n = *pl;
 212         if (n < 0) n = 0;  /* Start new chain for fwd rel if label exists. */
 213         goto linkrel;
 214       case DASM_REL_PC:
 215         pl = D->pclabels + n; CKPL(pc, PC);
 216       putrel:
 217         n = *pl;
 218         if (n < 0) {  /* Label exists. Get label pos and store it. */
 219           b[pos] = -n;
 220         } else {
 221       linkrel:
 222           b[pos] = n;  /* Else link to rel chain, anchored at label. */
 223           *pl = pos;
 224         }
 225         pos++;
 226         break;
 227       case DASM_LABEL_LG:
 228         pl = D->lglabels + (ins & 2047) - 10; CKPL(lg, LG); goto putlabel;
 229       case DASM_LABEL_PC:
 230         pl = D->pclabels + n; CKPL(pc, PC);
 231       putlabel:
 232         n = *pl;  /* n > 0: Collapse rel chain and replace with label pos. */
 233         while (n > 0) { int *pb = DASM_POS2PTR(D, n); n = *pb; *pb = pos;
 234         }
 235         *pl = -pos;  /* Label exists now. */
 236         b[pos++] = ofs;  /* Store pass1 offset estimate. */
 237         break;
 238       case DASM_IMM:
 239       case DASM_IMM16:
 240 #ifdef DASM_CHECKS
 241         CK((n & ((1<<((ins>>10)&31))-1)) == 0, RANGE_I);
 242         if ((ins & 0x8000))
 243           CK(((n + (1<<(((ins>>5)&31)-1)))>>((ins>>5)&31)) == 0, RANGE_I);
 244         else
 245           CK((n>>((ins>>5)&31)) == 0, RANGE_I);
 246 #endif
 247         b[pos++] = n;
 248         break;
 249       case DASM_IMMV8:
 250         CK((n & 3) == 0, RANGE_I);
 251         n >>= 2;
 252         /* fallthrough */
 253       case DASM_IMML8:
 254       case DASM_IMML12:
 255         CK(n >= 0 ? ((n>>((ins>>5)&31)) == 0) :
 256                     (((-n)>>((ins>>5)&31)) == 0), RANGE_I);
 257         b[pos++] = n;
 258         break;
 259       case DASM_IMM12:
 260         CK(dasm_imm12((unsigned int)n) != -1, RANGE_I);
 261         b[pos++] = n;
 262         break;
 263       }
 264     }
 265   }
 266 stop:
 267   va_end(ap);
 268   sec->pos = pos;
 269   sec->ofs = ofs;
 270 }
 271 #undef CK
 272
 273 /* Pass 2: Link sections, shrink aligns, fix label offsets. */
 274 int dasm_link(Dst_DECL, size_t *szp)
 275 {
 276   dasm_State *D = Dst_REF;
 277   int secnum;
 278   int ofs = 0;
 279
 280 #ifdef DASM_CHECKS
 281   *szp = 0;
 282   if (D->status != DASM_S_OK) return D->status;
 283   {
 284     int pc;
 285     for (pc = 0; pc*sizeof(int) < D->pcsize; pc++)
 286       if (D->pclabels[pc] > 0) return DASM_S_UNDEF_PC|pc;
 287   }
 288 #endif
 289
 290   { /* Handle globals not defined in this translation unit. */
 291     int idx;
 292     for (idx = 10; idx*sizeof(int) < D->lgsize; idx++) {
 293       int n = D->lglabels[idx];
 294       /* Undefined label: Collapse rel chain and replace with marker (< 0). */
 295       while (n > 0) { int *pb = DASM_POS2PTR(D, n); n = *pb; *pb = -idx; }
 296     }
 297   }
 298
 299   /* Combine all code sections. No support for data sections (yet). */
 300   for (secnum = 0; secnum < D->maxsection; secnum++) {
 301     dasm_Section *sec = D->sections + secnum;
 302     int *b = sec->rbuf;
 303     int pos = DASM_SEC2POS(secnum);
 304     int lastpos = sec->pos;
 305
 306     while (pos != lastpos) {
 307       dasm_ActList p = D->actionlist + b[pos++];
 308       while (1) {
 309         unsigned int ins = *p++;
 310         unsigned int action = (ins >> 16);
 311         switch (action) {
 312         case DASM_STOP: case DASM_SECTION: goto stop;
 313         case DASM_ESC: p++; break;
 314         case DASM_REL_EXT: break;
 315         case DASM_ALIGN: ofs -= (b[pos++] + ofs) & (ins & 255); break;
 316         case DASM_REL_LG: case DASM_REL_PC: pos++; break;
 317         case DASM_LABEL_LG: case DASM_LABEL_PC: b[pos++] += ofs; break;
 318         case DASM_IMM: case DASM_IMM12: case DASM_IMM16:
 319         case DASM_IMML8: case DASM_IMML12: case DASM_IMMV8: pos++; break;
 320         }
 321       }
 322       stop: (void)0;
 323     }
 324     ofs += sec->ofs;  /* Next section starts right after current section. */
 325   }
 326
 327   D->codesize = ofs;  /* Total size of all code sections */
 328   *szp = ofs;
 329   return DASM_S_OK;
 330 }
 331
 332 #ifdef DASM_CHECKS
 333 #define CK(x, st) \
 334   do { if (!(x)) return DASM_S_##st|(p-D->actionlist-1); } while (0)
 335 #else
 336 #define CK(x, st)       ((void)0)
 337 #endif
 338
 339 /* Pass 3: Encode sections. */
 340 int dasm_encode(Dst_DECL, void *buffer)
 341 {
 342   dasm_State *D = Dst_REF;
 343   char *base = (char *)buffer;
 344   unsigned int *cp = (unsigned int *)buffer;
 345   int secnum;
 346
 347   /* Encode all code sections. No support for data sections (yet). */
 348   for (secnum = 0; secnum < D->maxsection; secnum++) {
 349     dasm_Section *sec = D->sections + secnum;
 350     int *b = sec->buf;
 351     int *endb = sec->rbuf + sec->pos;
 352
 353     while (b != endb) {
 354       dasm_ActList p = D->actionlist + *b++;
 355       while (1) {
 356         unsigned int ins = *p++;
 357         unsigned int action = (ins >> 16);
 358         int n = (action >= DASM_ALIGN && action < DASM__MAX) ? *b++ : 0;
 359         switch (action) {
 360         case DASM_STOP: case DASM_SECTION: goto stop;
 361         case DASM_ESC: *cp++ = *p++; break;
 362         case DASM_REL_EXT:
 363           n = DASM_EXTERN(Dst, (unsigned char *)cp, (ins&2047), !(ins&2048));
 364           goto patchrel;
 365         case DASM_ALIGN:
 366           ins &= 255; while ((((char *)cp - base) & ins)) *cp++ = 0xe1a00000;
 367           break;
 368         case DASM_REL_LG:
 369           if (n < 0) {
 370             n = (int)((ptrdiff_t)D->globals[-n-10] - (ptrdiff_t)cp - 4);
 371             goto patchrel;
 372           }
 373           /* fallthrough */
 374         case DASM_REL_PC:
 375           CK(n >= 0, UNDEF_PC);
 376           n = *DASM_POS2PTR(D, n) - (int)((char *)cp - base) - 4;
 377         patchrel:
 378           if ((ins & 0x800) == 0) {
 379             CK((n & 3) == 0 && ((n+0x02000000) >> 26) == 0, RANGE_REL);
 380             cp[-1] |= ((n >> 2) & 0x00ffffff);
 381           } else if ((ins & 0x1000)) {
 382             CK((n & 3) == 0 && -256 <= n && n <= 256, RANGE_REL);
 383             goto patchimml8;
 384           } else if ((ins & 0x2000) == 0) {
 385             CK((n & 3) == 0 && -4096 <= n && n <= 4096, RANGE_REL);
 386             goto patchimml;
 387           } else {
 388             CK((n & 3) == 0 && -1020 <= n && n <= 1020, RANGE_REL);
 389             n >>= 2;
 390             goto patchimml;
 391           }
 392           break;
 393         case DASM_LABEL_LG:
 394           ins &= 2047; if (ins >= 20) D->globals[ins-20] = (void *)(base + n);
 395           break;
 396         case DASM_LABEL_PC: break;
 397         case DASM_IMM:
 398           cp[-1] |= ((n>>((ins>>10)&31)) & ((1<<((ins>>5)&31))-1)) << (ins&31);
 399           break;
 400         case DASM_IMM12:
 401           cp[-1] |= dasm_imm12((unsigned int)n);
 402           break;
 403         case DASM_IMM16:
 404           cp[-1] |= ((n & 0xf000) << 4) | (n & 0x0fff);
 405           break;
 406         case DASM_IMML8: patchimml8:
 407           cp[-1] |= n >= 0 ? (0x00800000 | (n & 0x0f) | ((n & 0xf0) << 4)) :
 408                              ((-n & 0x0f) | ((-n & 0xf0) << 4));
 409           break;
 410         case DASM_IMML12: case DASM_IMMV8: patchimml:
 411           cp[-1] |= n >= 0 ? (0x00800000 | n) : (-n);
 412           break;
 413         default: *cp++ = ins; break;
 414         }
 415       }
 416       stop: (void)0;
 417     }
 418   }
 419
 420   if (base + D->codesize != (char *)cp)  /* Check for phase errors. */
 421     return DASM_S_PHASE;
 422   return DASM_S_OK;
 423 }
 424 #undef CK
 425
 426 /* Get PC label offset. */
 427 int dasm_getpclabel(Dst_DECL, unsigned int pc)
 428 {
 429   dasm_State *D = Dst_REF;
 430   if (pc*sizeof(int) < D->pcsize) {
 431     int pos = D->pclabels[pc];
 432     if (pos < 0) return *DASM_POS2PTR(D, -pos);
 433     if (pos > 0) return -1;  /* Undefined. */
 434   }
 435   return -2;  /* Unused or out of range. */
 436 }
 437
 438 #ifdef DASM_CHECKS
 439 /* Optional sanity checker to call between isolated encoding steps. */
 440 int dasm_checkstep(Dst_DECL, int secmatch)
 441 {
 442   dasm_State *D = Dst_REF;
 443   if (D->status == DASM_S_OK) {
 444     int i;
 445     for (i = 1; i <= 9; i++) {
 446       if (D->lglabels[i] > 0) { D->status = DASM_S_UNDEF_LG|i; break; }
 447       D->lglabels[i] = 0;
 448     }
 449   }
 450   if (D->status == DASM_S_OK && secmatch >= 0 &&
 451       D->section != &D->sections[secmatch])
 452     D->status = DASM_S_MATCH_SEC|(D->section-D->sections);
 453   return D->status;
 454 }
 455 #endif
 456