1 /*
2 ** DynASM ARM encoding engine.
3 ** Copyright (C) 2005-2021 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 (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 int i;
171 for (i = 0; i < 16; i++, n = (n << 2) | (n >> 30))
172 if (n <= 255) return (int)(n + (i << 8));
173 return -1;
174 }
175
176 /* Pass 1: Store actions and args, link branches/labels, estimate offsets. */
dasm_put(Dst_DECL,int start,...)177 void dasm_put(Dst_DECL, int start, ...)
178 {
179 va_list ap;
180 dasm_State *D = Dst_REF;
181 dasm_ActList p = D->actionlist + start;
182 dasm_Section *sec = D->section;
183 int pos = sec->pos, ofs = sec->ofs;
184 int *b;
185
186 if (pos >= sec->epos) {
187 DASM_M_GROW(Dst, int, sec->buf, sec->bsize,
188 sec->bsize + 2*DASM_MAXSECPOS*sizeof(int));
189 sec->rbuf = sec->buf - DASM_POS2BIAS(pos);
190 sec->epos = (int)sec->bsize/sizeof(int) - DASM_MAXSECPOS+DASM_POS2BIAS(pos);
191 }
192
193 b = sec->rbuf;
194 b[pos++] = start;
195
196 va_start(ap, start);
197 while (1) {
198 unsigned int ins = *p++;
199 unsigned int action = (ins >> 16);
200 if (action >= DASM__MAX) {
201 ofs += 4;
202 } else {
203 int *pl, n = action >= DASM_REL_PC ? va_arg(ap, int) : 0;
204 switch (action) {
205 case DASM_STOP: goto stop;
206 case DASM_SECTION:
207 n = (ins & 255); CK(n < D->maxsection, RANGE_SEC);
208 D->section = &D->sections[n]; goto stop;
209 case DASM_ESC: p++; ofs += 4; break;
210 case DASM_REL_EXT: break;
211 case DASM_ALIGN: ofs += (ins & 255); b[pos++] = ofs; break;
212 case DASM_REL_LG:
213 n = (ins & 2047) - 10; pl = D->lglabels + n;
214 /* Bkwd rel or global. */
215 if (n >= 0) { CK(n>=10||*pl<0, RANGE_LG); CKPL(lg, LG); goto putrel; }
216 pl += 10; n = *pl;
217 if (n < 0) n = 0; /* Start new chain for fwd rel if label exists. */
218 goto linkrel;
219 case DASM_REL_PC:
220 pl = D->pclabels + n; CKPL(pc, PC);
221 putrel:
222 n = *pl;
223 if (n < 0) { /* Label exists. Get label pos and store it. */
224 b[pos] = -n;
225 } else {
226 linkrel:
227 b[pos] = n; /* Else link to rel chain, anchored at label. */
228 *pl = pos;
229 }
230 pos++;
231 break;
232 case DASM_LABEL_LG:
233 pl = D->lglabels + (ins & 2047) - 10; CKPL(lg, LG); goto putlabel;
234 case DASM_LABEL_PC:
235 pl = D->pclabels + n; CKPL(pc, PC);
236 putlabel:
237 n = *pl; /* n > 0: Collapse rel chain and replace with label pos. */
238 while (n > 0) { int *pb = DASM_POS2PTR(D, n); n = *pb; *pb = pos;
239 }
240 *pl = -pos; /* Label exists now. */
241 b[pos++] = ofs; /* Store pass1 offset estimate. */
242 break;
243 case DASM_IMM:
244 case DASM_IMM16:
245 #ifdef DASM_CHECKS
246 CK((n & ((1<<((ins>>10)&31))-1)) == 0, RANGE_I);
247 if ((ins & 0x8000))
248 CK(((n + (1<<(((ins>>5)&31)-1)))>>((ins>>5)&31)) == 0, RANGE_I);
249 else
250 CK((n>>((ins>>5)&31)) == 0, RANGE_I);
251 #endif
252 b[pos++] = n;
253 break;
254 case DASM_IMMV8:
255 CK((n & 3) == 0, RANGE_I);
256 n >>= 2;
257 /* fallthrough */
258 case DASM_IMML8:
259 case DASM_IMML12:
260 CK(n >= 0 ? ((n>>((ins>>5)&31)) == 0) :
261 (((-n)>>((ins>>5)&31)) == 0), RANGE_I);
262 b[pos++] = n;
263 break;
264 case DASM_IMM12:
265 CK(dasm_imm12((unsigned int)n) != -1, RANGE_I);
266 b[pos++] = n;
267 break;
268 }
269 }
270 }
271 stop:
272 va_end(ap);
273 sec->pos = pos;
274 sec->ofs = ofs;
275 }
276 #undef CK
277
278 /* Pass 2: Link sections, shrink aligns, fix label offsets. */
dasm_link(Dst_DECL,size_t * szp)279 int dasm_link(Dst_DECL, size_t *szp)
280 {
281 dasm_State *D = Dst_REF;
282 int secnum;
283 int ofs = 0;
284
285 #ifdef DASM_CHECKS
286 *szp = 0;
287 if (D->status != DASM_S_OK) return D->status;
288 {
289 int pc;
290 for (pc = 0; pc*sizeof(int) < D->pcsize; pc++)
291 if (D->pclabels[pc] > 0) return DASM_S_UNDEF_PC|pc;
292 }
293 #endif
294
295 { /* Handle globals not defined in this translation unit. */
296 int idx;
297 for (idx = 10; idx*sizeof(int) < D->lgsize; idx++) {
298 int n = D->lglabels[idx];
299 /* Undefined label: Collapse rel chain and replace with marker (< 0). */
300 while (n > 0) { int *pb = DASM_POS2PTR(D, n); n = *pb; *pb = -idx; }
301 }
302 }
303
304 /* Combine all code sections. No support for data sections (yet). */
305 for (secnum = 0; secnum < D->maxsection; secnum++) {
306 dasm_Section *sec = D->sections + secnum;
307 int *b = sec->rbuf;
308 int pos = DASM_SEC2POS(secnum);
309 int lastpos = sec->pos;
310
311 while (pos != lastpos) {
312 dasm_ActList p = D->actionlist + b[pos++];
313 while (1) {
314 unsigned int ins = *p++;
315 unsigned int action = (ins >> 16);
316 switch (action) {
317 case DASM_STOP: case DASM_SECTION: goto stop;
318 case DASM_ESC: p++; break;
319 case DASM_REL_EXT: break;
320 case DASM_ALIGN: ofs -= (b[pos++] + ofs) & (ins & 255); break;
321 case DASM_REL_LG: case DASM_REL_PC: pos++; break;
322 case DASM_LABEL_LG: case DASM_LABEL_PC: b[pos++] += ofs; break;
323 case DASM_IMM: case DASM_IMM12: case DASM_IMM16:
324 case DASM_IMML8: case DASM_IMML12: case DASM_IMMV8: pos++; break;
325 }
326 }
327 stop: (void)0;
328 }
329 ofs += sec->ofs; /* Next section starts right after current section. */
330 }
331
332 D->codesize = ofs; /* Total size of all code sections */
333 *szp = ofs;
334 return DASM_S_OK;
335 }
336
337 #ifdef DASM_CHECKS
338 #define CK(x, st) \
339 do { if (!(x)) return DASM_S_##st|(p-D->actionlist-1); } while (0)
340 #else
341 #define CK(x, st) ((void)0)
342 #endif
343
344 /* Pass 3: Encode sections. */
dasm_encode(Dst_DECL,void * buffer)345 int dasm_encode(Dst_DECL, void *buffer)
346 {
347 dasm_State *D = Dst_REF;
348 char *base = (char *)buffer;
349 unsigned int *cp = (unsigned int *)buffer;
350 int secnum;
351
352 /* Encode all code sections. No support for data sections (yet). */
353 for (secnum = 0; secnum < D->maxsection; secnum++) {
354 dasm_Section *sec = D->sections + secnum;
355 int *b = sec->buf;
356 int *endb = sec->rbuf + sec->pos;
357
358 while (b != endb) {
359 dasm_ActList p = D->actionlist + *b++;
360 while (1) {
361 unsigned int ins = *p++;
362 unsigned int action = (ins >> 16);
363 int n = (action >= DASM_ALIGN && action < DASM__MAX) ? *b++ : 0;
364 switch (action) {
365 case DASM_STOP: case DASM_SECTION: goto stop;
366 case DASM_ESC: *cp++ = *p++; break;
367 case DASM_REL_EXT:
368 n = DASM_EXTERN(Dst, (unsigned char *)cp, (ins&2047), !(ins&2048));
369 goto patchrel;
370 case DASM_ALIGN:
371 ins &= 255; while ((((char *)cp - base) & ins)) *cp++ = 0xe1a00000;
372 break;
373 case DASM_REL_LG:
374 if (n < 0) {
375 n = (int)((ptrdiff_t)D->globals[-n] - (ptrdiff_t)cp - 4);
376 goto patchrel;
377 }
378 /* fallthrough */
379 case DASM_REL_PC:
380 CK(n >= 0, UNDEF_PC);
381 n = *DASM_POS2PTR(D, n) - (int)((char *)cp - base) - 4;
382 patchrel:
383 if ((ins & 0x800) == 0) {
384 CK((n & 3) == 0 && ((n+0x02000000) >> 26) == 0, RANGE_REL);
385 cp[-1] |= ((n >> 2) & 0x00ffffff);
386 } else if ((ins & 0x1000)) {
387 CK((n & 3) == 0 && -256 <= n && n <= 256, RANGE_REL);
388 goto patchimml8;
389 } else if ((ins & 0x2000) == 0) {
390 CK((n & 3) == 0 && -4096 <= n && n <= 4096, RANGE_REL);
391 goto patchimml;
392 } else {
393 CK((n & 3) == 0 && -1020 <= n && n <= 1020, RANGE_REL);
394 n >>= 2;
395 goto patchimml;
396 }
397 break;
398 case DASM_LABEL_LG:
399 ins &= 2047; if (ins >= 20) D->globals[ins-10] = (void *)(base + n);
400 break;
401 case DASM_LABEL_PC: break;
402 case DASM_IMM:
403 cp[-1] |= ((n>>((ins>>10)&31)) & ((1<<((ins>>5)&31))-1)) << (ins&31);
404 break;
405 case DASM_IMM12:
406 cp[-1] |= dasm_imm12((unsigned int)n);
407 break;
408 case DASM_IMM16:
409 cp[-1] |= ((n & 0xf000) << 4) | (n & 0x0fff);
410 break;
411 case DASM_IMML8: patchimml8:
412 cp[-1] |= n >= 0 ? (0x00800000 | (n & 0x0f) | ((n & 0xf0) << 4)) :
413 ((-n & 0x0f) | ((-n & 0xf0) << 4));
414 break;
415 case DASM_IMML12: case DASM_IMMV8: patchimml:
416 cp[-1] |= n >= 0 ? (0x00800000 | n) : (-n);
417 break;
418 default: *cp++ = ins; break;
419 }
420 }
421 stop: (void)0;
422 }
423 }
424
425 if (base + D->codesize != (char *)cp) /* Check for phase errors. */
426 return DASM_S_PHASE;
427 return DASM_S_OK;
428 }
429 #undef CK
430
431 /* Get PC label offset. */
dasm_getpclabel(Dst_DECL,unsigned int pc)432 int dasm_getpclabel(Dst_DECL, unsigned int pc)
433 {
434 dasm_State *D = Dst_REF;
435 if (pc*sizeof(int) < D->pcsize) {
436 int pos = D->pclabels[pc];
437 if (pos < 0) return *DASM_POS2PTR(D, -pos);
438 if (pos > 0) return -1; /* Undefined. */
439 }
440 return -2; /* Unused or out of range. */
441 }
442
443 #ifdef DASM_CHECKS
444 /* Optional sanity checker to call between isolated encoding steps. */
dasm_checkstep(Dst_DECL,int secmatch)445 int dasm_checkstep(Dst_DECL, int secmatch)
446 {
447 dasm_State *D = Dst_REF;
448 if (D->status == DASM_S_OK) {
449 int i;
450 for (i = 1; i <= 9; i++) {
451 if (D->lglabels[i] > 0) { D->status = DASM_S_UNDEF_LG|i; break; }
452 D->lglabels[i] = 0;
453 }
454 }
455 if (D->status == DASM_S_OK && secmatch >= 0 &&
456 D->section != &D->sections[secmatch])
457 D->status = DASM_S_MATCH_SEC|(D->section-D->sections);
458 return D->status;
459 }
460 #endif
461
462
