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. */
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 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. */
dasm_free(Dst_DECL)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(). */
dasm_setupglobal(Dst_DECL,void ** gl,unsigned int maxgl)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. */
dasm_growpc(Dst_DECL,unsigned int maxpc)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. */
dasm_setup(Dst_DECL,const void * actionlist)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
dasm_imm12(unsigned int n)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. */
dasm_put(Dst_DECL,int start,...)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. */
dasm_link(Dst_DECL,size_t * szp)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. */
dasm_encode(Dst_DECL,void * buffer)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. */
dasm_getpclabel(Dst_DECL,unsigned int pc)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. */
dasm_checkstep(Dst_DECL,int secmatch)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
457
