1 /*
2 ** DynASM ARM64 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 "arm64"
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_IMM6, DASM_IMM12, DASM_IMM13W, DASM_IMM13X, DASM_IMML,
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 (bias -10). */
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. */
dasm_init(Dst_DECL,int maxsection)86 void dasm_init(Dst_DECL, int maxsection)
87 {
88 dasm_State *D;
89 size_t psz = 0;
90 int i;
91 Dst_REF = NULL;
92 DASM_M_GROW(Dst, struct dasm_State, Dst_REF, psz, DASM_PSZ(maxsection));
93 D = Dst_REF;
94 D->psize = psz;
95 D->lglabels = NULL;
96 D->lgsize = 0;
97 D->pclabels = NULL;
98 D->pcsize = 0;
99 D->globals = NULL;
100 D->maxsection = maxsection;
101 for (i = 0; i < maxsection; i++) {
102 D->sections[i].buf = NULL; /* Need this for pass3. */
103 D->sections[i].rbuf = D->sections[i].buf - DASM_SEC2POS(i);
104 D->sections[i].bsize = 0;
105 D->sections[i].epos = 0; /* Wrong, but is recalculated after resize. */
106 }
107 }
108
109 /* Free DynASM state. */
dasm_free(Dst_DECL)110 void dasm_free(Dst_DECL)
111 {
112 dasm_State *D = Dst_REF;
113 int i;
114 for (i = 0; i < D->maxsection; i++)
115 if (D->sections[i].buf)
116 DASM_M_FREE(Dst, D->sections[i].buf, D->sections[i].bsize);
117 if (D->pclabels) DASM_M_FREE(Dst, D->pclabels, D->pcsize);
118 if (D->lglabels) DASM_M_FREE(Dst, D->lglabels, D->lgsize);
119 DASM_M_FREE(Dst, D, D->psize);
120 }
121
122 /* Setup global label array. Must be called before dasm_setup(). */
dasm_setupglobal(Dst_DECL,void ** gl,unsigned int maxgl)123 void dasm_setupglobal(Dst_DECL, void **gl, unsigned int maxgl)
124 {
125 dasm_State *D = Dst_REF;
126 D->globals = gl - 10; /* Negative bias to compensate for locals. */
127 DASM_M_GROW(Dst, int, D->lglabels, D->lgsize, (10+maxgl)*sizeof(int));
128 }
129
130 /* Grow PC label array. Can be called after dasm_setup(), too. */
dasm_growpc(Dst_DECL,unsigned int maxpc)131 void dasm_growpc(Dst_DECL, unsigned int maxpc)
132 {
133 dasm_State *D = Dst_REF;
134 size_t osz = D->pcsize;
135 DASM_M_GROW(Dst, int, D->pclabels, D->pcsize, maxpc*sizeof(int));
136 memset((void *)(((unsigned char *)D->pclabels)+osz), 0, D->pcsize-osz);
137 }
138
139 /* Setup encoder. */
dasm_setup(Dst_DECL,const void * actionlist)140 void dasm_setup(Dst_DECL, const void *actionlist)
141 {
142 dasm_State *D = Dst_REF;
143 int i;
144 D->actionlist = (dasm_ActList)actionlist;
145 D->status = DASM_S_OK;
146 D->section = &D->sections[0];
147 memset((void *)D->lglabels, 0, D->lgsize);
148 if (D->pclabels) memset((void *)D->pclabels, 0, D->pcsize);
149 for (i = 0; i < D->maxsection; i++) {
150 D->sections[i].pos = DASM_SEC2POS(i);
151 D->sections[i].ofs = 0;
152 }
153 }
154
155
156 #ifdef DASM_CHECKS
157 #define CK(x, st) \
158 do { if (!(x)) { \
159 D->status = DASM_S_##st|(p-D->actionlist-1); return; } } while (0)
160 #define CKPL(kind, st) \
161 do { if ((size_t)((char *)pl-(char *)D->kind##labels) >= D->kind##size) { \
162 D->status = DASM_S_RANGE_##st|(p-D->actionlist-1); return; } } while (0)
163 #else
164 #define CK(x, st) ((void)0)
165 #define CKPL(kind, st) ((void)0)
166 #endif
167
dasm_imm12(unsigned int n)168 static int dasm_imm12(unsigned int n)
169 {
170 if ((n >> 12) == 0)
171 return n;
172 else if ((n & 0xff000fff) == 0)
173 return (n >> 12) | 0x1000;
174 else
175 return -1;
176 }
177
dasm_ffs(unsigned long long x)178 static int dasm_ffs(unsigned long long x)
179 {
180 int n = -1;
181 while (x) { x >>= 1; n++; }
182 return n;
183 }
184
dasm_imm13(int lo,int hi)185 static int dasm_imm13(int lo, int hi)
186 {
187 int inv = 0, w = 64, s = 0xfff, xa, xb;
188 unsigned long long n = (((unsigned long long)hi) << 32) | (unsigned int)lo;
189 unsigned long long m = 1ULL, a, b, c;
190 if (n & 1) { n = ~n; inv = 1; }
191 a = n & -n; b = (n+a)&-(n+a); c = (n+a-b)&-(n+a-b);
192 xa = dasm_ffs(a); xb = dasm_ffs(b);
193 if (c) {
194 w = dasm_ffs(c) - xa;
195 if (w == 32) m = 0x0000000100000001UL;
196 else if (w == 16) m = 0x0001000100010001UL;
197 else if (w == 8) m = 0x0101010101010101UL;
198 else if (w == 4) m = 0x1111111111111111UL;
199 else if (w == 2) m = 0x5555555555555555UL;
200 else return -1;
201 s = (-2*w & 0x3f) - 1;
202 } else if (!a) {
203 return -1;
204 } else if (xb == -1) {
205 xb = 64;
206 }
207 if ((b-a) * m != n) return -1;
208 if (inv) {
209 return ((w - xb) << 6) | (s+w+xa-xb);
210 } else {
211 return ((w - xa) << 6) | (s+xb-xa);
212 }
213 return -1;
214 }
215
216 /* Pass 1: Store actions and args, link branches/labels, estimate offsets. */
dasm_put(Dst_DECL,int start,...)217 void dasm_put(Dst_DECL, int start, ...)
218 {
219 va_list ap;
220 dasm_State *D = Dst_REF;
221 dasm_ActList p = D->actionlist + start;
222 dasm_Section *sec = D->section;
223 int pos = sec->pos, ofs = sec->ofs;
224 int *b;
225
226 if (pos >= sec->epos) {
227 DASM_M_GROW(Dst, int, sec->buf, sec->bsize,
228 sec->bsize + 2*DASM_MAXSECPOS*sizeof(int));
229 sec->rbuf = sec->buf - DASM_POS2BIAS(pos);
230 sec->epos = (int)sec->bsize/sizeof(int) - DASM_MAXSECPOS+DASM_POS2BIAS(pos);
231 }
232
233 b = sec->rbuf;
234 b[pos++] = start;
235
236 va_start(ap, start);
237 while (1) {
238 unsigned int ins = *p++;
239 unsigned int action = (ins >> 16);
240 if (action >= DASM__MAX) {
241 ofs += 4;
242 } else {
243 int *pl, n = action >= DASM_REL_PC ? va_arg(ap, int) : 0;
244 switch (action) {
245 case DASM_STOP: goto stop;
246 case DASM_SECTION:
247 n = (ins & 255); CK(n < D->maxsection, RANGE_SEC);
248 D->section = &D->sections[n]; goto stop;
249 case DASM_ESC: p++; ofs += 4; break;
250 case DASM_REL_EXT: break;
251 case DASM_ALIGN: ofs += (ins & 255); b[pos++] = ofs; break;
252 case DASM_REL_LG:
253 n = (ins & 2047) - 10; pl = D->lglabels + n;
254 /* Bkwd rel or global. */
255 if (n >= 0) { CK(n>=10||*pl<0, RANGE_LG); CKPL(lg, LG); goto putrel; }
256 pl += 10; n = *pl;
257 if (n < 0) n = 0; /* Start new chain for fwd rel if label exists. */
258 goto linkrel;
259 case DASM_REL_PC:
260 pl = D->pclabels + n; CKPL(pc, PC);
261 putrel:
262 n = *pl;
263 if (n < 0) { /* Label exists. Get label pos and store it. */
264 b[pos] = -n;
265 } else {
266 linkrel:
267 b[pos] = n; /* Else link to rel chain, anchored at label. */
268 *pl = pos;
269 }
270 pos++;
271 break;
272 case DASM_LABEL_LG:
273 pl = D->lglabels + (ins & 2047) - 10; CKPL(lg, LG); goto putlabel;
274 case DASM_LABEL_PC:
275 pl = D->pclabels + n; CKPL(pc, PC);
276 putlabel:
277 n = *pl; /* n > 0: Collapse rel chain and replace with label pos. */
278 while (n > 0) { int *pb = DASM_POS2PTR(D, n); n = *pb; *pb = pos;
279 }
280 *pl = -pos; /* Label exists now. */
281 b[pos++] = ofs; /* Store pass1 offset estimate. */
282 break;
283 case DASM_IMM:
284 CK((n & ((1<<((ins>>10)&31))-1)) == 0, RANGE_I);
285 n >>= ((ins>>10)&31);
286 #ifdef DASM_CHECKS
287 if ((ins & 0x8000))
288 CK(((n + (1<<(((ins>>5)&31)-1)))>>((ins>>5)&31)) == 0, RANGE_I);
289 else
290 CK((n>>((ins>>5)&31)) == 0, RANGE_I);
291 #endif
292 b[pos++] = n;
293 break;
294 case DASM_IMM6:
295 CK((n >> 6) == 0, RANGE_I);
296 b[pos++] = n;
297 break;
298 case DASM_IMM12:
299 CK(dasm_imm12((unsigned int)n) != -1, RANGE_I);
300 b[pos++] = n;
301 break;
302 case DASM_IMM13W:
303 CK(dasm_imm13(n, n) != -1, RANGE_I);
304 b[pos++] = n;
305 break;
306 case DASM_IMM13X: {
307 int m = va_arg(ap, int);
308 CK(dasm_imm13(n, m) != -1, RANGE_I);
309 b[pos++] = n;
310 b[pos++] = m;
311 break;
312 }
313 case DASM_IMML: {
314 #ifdef DASM_CHECKS
315 int scale = (p[-2] >> 30);
316 CK((!(n & ((1<<scale)-1)) && (unsigned int)(n>>scale) < 4096) ||
317 (unsigned int)(n+256) < 512, RANGE_I);
318 #endif
319 b[pos++] = n;
320 break;
321 }
322 }
323 }
324 }
325 stop:
326 va_end(ap);
327 sec->pos = pos;
328 sec->ofs = ofs;
329 }
330 #undef CK
331
332 /* Pass 2: Link sections, shrink aligns, fix label offsets. */
dasm_link(Dst_DECL,size_t * szp)333 int dasm_link(Dst_DECL, size_t *szp)
334 {
335 dasm_State *D = Dst_REF;
336 int secnum;
337 int ofs = 0;
338
339 #ifdef DASM_CHECKS
340 *szp = 0;
341 if (D->status != DASM_S_OK) return D->status;
342 {
343 int pc;
344 for (pc = 0; pc*sizeof(int) < D->pcsize; pc++)
345 if (D->pclabels[pc] > 0) return DASM_S_UNDEF_PC|pc;
346 }
347 #endif
348
349 { /* Handle globals not defined in this translation unit. */
350 int idx;
351 for (idx = 20; idx*sizeof(int) < D->lgsize; idx++) {
352 int n = D->lglabels[idx];
353 /* Undefined label: Collapse rel chain and replace with marker (< 0). */
354 while (n > 0) { int *pb = DASM_POS2PTR(D, n); n = *pb; *pb = -idx; }
355 }
356 }
357
358 /* Combine all code sections. No support for data sections (yet). */
359 for (secnum = 0; secnum < D->maxsection; secnum++) {
360 dasm_Section *sec = D->sections + secnum;
361 int *b = sec->rbuf;
362 int pos = DASM_SEC2POS(secnum);
363 int lastpos = sec->pos;
364
365 while (pos != lastpos) {
366 dasm_ActList p = D->actionlist + b[pos++];
367 while (1) {
368 unsigned int ins = *p++;
369 unsigned int action = (ins >> 16);
370 switch (action) {
371 case DASM_STOP: case DASM_SECTION: goto stop;
372 case DASM_ESC: p++; break;
373 case DASM_REL_EXT: break;
374 case DASM_ALIGN: ofs -= (b[pos++] + ofs) & (ins & 255); break;
375 case DASM_REL_LG: case DASM_REL_PC: pos++; break;
376 case DASM_LABEL_LG: case DASM_LABEL_PC: b[pos++] += ofs; break;
377 case DASM_IMM: case DASM_IMM6: case DASM_IMM12: case DASM_IMM13W:
378 case DASM_IMML: pos++; break;
379 case DASM_IMM13X: pos += 2; break;
380 }
381 }
382 stop: (void)0;
383 }
384 ofs += sec->ofs; /* Next section starts right after current section. */
385 }
386
387 D->codesize = ofs; /* Total size of all code sections */
388 *szp = ofs;
389 return DASM_S_OK;
390 }
391
392 #ifdef DASM_CHECKS
393 #define CK(x, st) \
394 do { if (!(x)) return DASM_S_##st|(p-D->actionlist-1); } while (0)
395 #else
396 #define CK(x, st) ((void)0)
397 #endif
398
399 /* Pass 3: Encode sections. */
dasm_encode(Dst_DECL,void * buffer)400 int dasm_encode(Dst_DECL, void *buffer)
401 {
402 dasm_State *D = Dst_REF;
403 char *base = (char *)buffer;
404 unsigned int *cp = (unsigned int *)buffer;
405 int secnum;
406
407 /* Encode all code sections. No support for data sections (yet). */
408 for (secnum = 0; secnum < D->maxsection; secnum++) {
409 dasm_Section *sec = D->sections + secnum;
410 int *b = sec->buf;
411 int *endb = sec->rbuf + sec->pos;
412
413 while (b != endb) {
414 dasm_ActList p = D->actionlist + *b++;
415 while (1) {
416 unsigned int ins = *p++;
417 unsigned int action = (ins >> 16);
418 int n = (action >= DASM_ALIGN && action < DASM__MAX) ? *b++ : 0;
419 switch (action) {
420 case DASM_STOP: case DASM_SECTION: goto stop;
421 case DASM_ESC: *cp++ = *p++; break;
422 case DASM_REL_EXT:
423 n = DASM_EXTERN(Dst, (unsigned char *)cp, (ins&2047), !(ins&2048));
424 goto patchrel;
425 case DASM_ALIGN:
426 ins &= 255; while ((((char *)cp - base) & ins)) *cp++ = 0xe1a00000;
427 break;
428 case DASM_REL_LG:
429 CK(n >= 0, UNDEF_LG);
430 case DASM_REL_PC:
431 CK(n >= 0, UNDEF_PC);
432 n = *DASM_POS2PTR(D, n) - (int)((char *)cp - base) + 4;
433 patchrel:
434 if (!(ins & 0xf800)) { /* B, BL */
435 CK((n & 3) == 0 && ((n+0x08000000) >> 28) == 0, RANGE_REL);
436 cp[-1] |= ((n >> 2) & 0x03ffffff);
437 } else if ((ins & 0x800)) { /* B.cond, CBZ, CBNZ, LDR* literal */
438 CK((n & 3) == 0 && ((n+0x00100000) >> 21) == 0, RANGE_REL);
439 cp[-1] |= ((n << 3) & 0x00ffffe0);
440 } else if ((ins & 0x3000) == 0x2000) { /* ADR */
441 CK(((n+0x00100000) >> 21) == 0, RANGE_REL);
442 cp[-1] |= ((n << 3) & 0x00ffffe0) | ((n & 3) << 29);
443 } else if ((ins & 0x3000) == 0x3000) { /* ADRP */
444 cp[-1] |= ((n >> 9) & 0x00ffffe0) | (((n >> 12) & 3) << 29);
445 } else if ((ins & 0x1000)) { /* TBZ, TBNZ */
446 CK((n & 3) == 0 && ((n+0x00008000) >> 16) == 0, RANGE_REL);
447 cp[-1] |= ((n << 3) & 0x0007ffe0);
448 }
449 break;
450 case DASM_LABEL_LG:
451 ins &= 2047; if (ins >= 20) D->globals[ins-10] = (void *)(base + n);
452 break;
453 case DASM_LABEL_PC: break;
454 case DASM_IMM:
455 cp[-1] |= (n & ((1<<((ins>>5)&31))-1)) << (ins&31);
456 break;
457 case DASM_IMM6:
458 cp[-1] |= ((n&31) << 19) | ((n&32) << 26);
459 break;
460 case DASM_IMM12:
461 cp[-1] |= (dasm_imm12((unsigned int)n) << 10);
462 break;
463 case DASM_IMM13W:
464 cp[-1] |= (dasm_imm13(n, n) << 10);
465 break;
466 case DASM_IMM13X:
467 cp[-1] |= (dasm_imm13(n, *b++) << 10);
468 break;
469 case DASM_IMML: {
470 int scale = (p[-2] >> 30);
471 cp[-1] |= (!(n & ((1<<scale)-1)) && (unsigned int)(n>>scale) < 4096) ?
472 ((n << (10-scale)) | 0x01000000) : ((n & 511) << 12);
473 break;
474 }
475 default: *cp++ = ins; break;
476 }
477 }
478 stop: (void)0;
479 }
480 }
481
482 if (base + D->codesize != (char *)cp) /* Check for phase errors. */
483 return DASM_S_PHASE;
484 return DASM_S_OK;
485 }
486 #undef CK
487
488 /* Get PC label offset. */
dasm_getpclabel(Dst_DECL,unsigned int pc)489 int dasm_getpclabel(Dst_DECL, unsigned int pc)
490 {
491 dasm_State *D = Dst_REF;
492 if (pc*sizeof(int) < D->pcsize) {
493 int pos = D->pclabels[pc];
494 if (pos < 0) return *DASM_POS2PTR(D, -pos);
495 if (pos > 0) return -1; /* Undefined. */
496 }
497 return -2; /* Unused or out of range. */
498 }
499
500 #ifdef DASM_CHECKS
501 /* Optional sanity checker to call between isolated encoding steps. */
dasm_checkstep(Dst_DECL,int secmatch)502 int dasm_checkstep(Dst_DECL, int secmatch)
503 {
504 dasm_State *D = Dst_REF;
505 if (D->status == DASM_S_OK) {
506 int i;
507 for (i = 1; i <= 9; i++) {
508 if (D->lglabels[i] > 0) { D->status = DASM_S_UNDEF_LG|i; break; }
509 D->lglabels[i] = 0;
510 }
511 }
512 if (D->status == DASM_S_OK && secmatch >= 0 &&
513 D->section != &D->sections[secmatch])
514 D->status = DASM_S_MATCH_SEC|(D->section-D->sections);
515 return D->status;
516 }
517 #endif
518
519
