1 #include <u.h>
2 #include <libc.h>
3 #include <bio.h>
4 #include <mach.h>
5 #include "elf.h"
6 #include "dwarf.h"
7 
8 static void	dwarfsymclose(Fhdr*);
9 static int	dwarfpc2file(Fhdr*, u64int, char*, uint, ulong*);
10 static int	dwarfline2pc(Fhdr*, u64int, ulong, u64int*);
11 static int	dwarflookuplsym(Fhdr*, Symbol*, char*, Symbol*);
12 static int	dwarfindexlsym(Fhdr*, Symbol*, uint, Symbol*);
13 static int	dwarffindlsym(Fhdr*, Symbol*, Loc, Symbol*);
14 static void	dwarfsyminit(Fhdr*);
15 static int	dwarftosym(Fhdr*, Dwarf*, DwarfSym*, Symbol*, int);
16 static int	_dwarfunwind(Fhdr *fhdr, Map *map, Regs *regs, u64int *next, Symbol*);
17 
18 int
19 symdwarf(Fhdr *hdr)
20 {
21 	if(hdr->dwarf == nil){
22 		werrstr("no dwarf debugging symbols");
23 		return -1;
24 	}
25 
26 	hdr->symclose = dwarfsymclose;
27 	hdr->pc2file = dwarfpc2file;
28 	hdr->line2pc = dwarfline2pc;
29 	hdr->lookuplsym = dwarflookuplsym;
30 	hdr->indexlsym = dwarfindexlsym;
31 	hdr->findlsym = dwarffindlsym;
32 	hdr->unwind = _dwarfunwind;
33 	dwarfsyminit(hdr);
34 
35 	return 0;
36 }
37 
38 static void
39 dwarfsymclose(Fhdr *hdr)
40 {
41 	dwarfclose(hdr->dwarf);
42 	hdr->dwarf = nil;
43 }
44 
45 static int
46 dwarfpc2file(Fhdr *fhdr, u64int pc, char *buf, uint nbuf, ulong *line)
47 {
48 	char *cdir, *dir, *file;
49 
50 	if(dwarfpctoline(fhdr->dwarf, pc, &cdir, &dir, &file, line, nil, nil) < 0)
51 		return -1;
52 
53 	if(file[0] == '/' || (dir==nil && cdir==nil))
54 		strecpy(buf, buf+nbuf, file);
55 	else if((dir && dir[0] == '/') || cdir==nil)
56 		snprint(buf, nbuf, "%s/%s", dir, file);
57 	else
58 		snprint(buf, nbuf, "%s/%s/%s", cdir, dir ? dir : "", file);
59 	cleanname(buf);
60 	return 0;;
61 }
62 
63 static int
64 dwarfline2pc(Fhdr *fhdr, u64int basepc, ulong line, u64int *pc)
65 {
66 	werrstr("dwarf line2pc not implemented");
67 	return -1;
68 }
69 
70 static uint
71 typesize(Dwarf *dwarf, ulong unit, ulong tref, char *name)
72 {
73 	DwarfSym ds;
74 
75 top:
76 	if(dwarfseeksym(dwarf, unit, tref-unit, &ds) < 0){
77 	cannot:
78 		fprint(2, "warning: cannot compute size of parameter %s (%lud %lud: %r)\n",
79 			name, unit, tref);
80 		return 0;
81 	}
82 
83 	if(ds.attrs.have.bytesize)
84 		return ds.attrs.bytesize;
85 
86 	switch(ds.attrs.tag){
87 	case TagVolatileType:
88 	case TagRestrictType:
89 	case TagTypedef:
90 		if(ds.attrs.have.type != TReference)
91 			goto cannot;
92 		tref = ds.attrs.type;
93 		goto top;
94 	}
95 
96 	goto cannot;
97 }
98 
99 static int
100 roundup(int s, int n)
101 {
102 	return (s+n-1)&~(n-1);
103 }
104 
105 static int
106 dwarflenum(Fhdr *fhdr, Symbol *p, char *name, uint j, Loc l, Symbol *s)
107 {
108 	int depth, bpoff;
109 	DwarfSym ds;
110 	Symbol s1;
111 
112 	if(p == nil)
113 		return -1;
114 
115 	if(p->u.dwarf.unit == 0 && p->u.dwarf.uoff == 0)
116 		return -1;
117 
118 	if(dwarfseeksym(fhdr->dwarf, p->u.dwarf.unit, p->u.dwarf.uoff, &ds) < 0)
119 		return -1;
120 
121 	ds.depth = 1;
122 	depth = 1;
123 
124 	bpoff = 8;
125 	while(dwarfnextsym(fhdr->dwarf, &ds) == 1 && depth < ds.depth){
126 		if(ds.attrs.tag != TagVariable){
127 			if(ds.attrs.tag != TagFormalParameter
128 			&& ds.attrs.tag != TagUnspecifiedParameters)
129 				continue;
130 			if(ds.depth != depth+1)
131 				continue;
132 		}
133 		if(dwarftosym(fhdr, fhdr->dwarf, &ds, &s1, 1) < 0)
134 			continue;
135 		/* XXX move this out once there is another architecture */
136 		/*
137 		 * gcc tells us the registers where the parameters might be
138 		 * held for an instruction or two.  use the parameter list to
139 		 * recompute the actual stack locations.
140 		 */
141 		if(fhdr->mtype == M386)
142 		if(ds.attrs.tag==TagFormalParameter || ds.attrs.tag==TagUnspecifiedParameters){
143 			if(s1.loc.type==LOFFSET
144 			&& strcmp(s1.loc.reg, "BP")==0
145 			&& s1.loc.offset >= 8)
146 				bpoff = s1.loc.offset;
147 			else{
148 				s1.loc.type = LOFFSET;
149 				s1.loc.reg = "BP";
150 				s1.loc.offset = bpoff;
151 			}
152 			if(ds.attrs.tag == TagFormalParameter){
153 				if(ds.attrs.have.type)
154 					bpoff += roundup(typesize(fhdr->dwarf, p->u.dwarf.unit, ds.attrs.type, s1.name), 4);
155 				else
156 					fprint(2, "warning: cannot compute size of parameter %s\n", s1.name);
157 			}
158 		}
159 		if(name){
160 			if(strcmp(ds.attrs.name, name) != 0)
161 				continue;
162 		}else if(l.type){
163 			if(loccmp(&s1.loc, &l) != 0)
164 				continue;
165 		}else{
166 			if(j-- > 0)
167 				continue;
168 		}
169 		*s = s1;
170 		return 0;
171 	}
172 	return -1;
173 }
174 
175 static Loc zl;
176 
177 static int
178 dwarflookuplsym(Fhdr *fhdr, Symbol *p, char *name, Symbol *s)
179 {
180 	return dwarflenum(fhdr, p, name, 0, zl, s);
181 }
182 
183 static int
184 dwarfindexlsym(Fhdr *fhdr, Symbol *p, uint i, Symbol *s)
185 {
186 	return dwarflenum(fhdr, p, nil, i, zl, s);
187 }
188 
189 static int
190 dwarffindlsym(Fhdr *fhdr, Symbol *p, Loc l, Symbol *s)
191 {
192 	return dwarflenum(fhdr, p, nil, 0, l, s);
193 }
194 
195 static void
196 dwarfsyminit(Fhdr *fp)
197 {
198 	Dwarf *d;
199 	DwarfSym s;
200 	Symbol sym;
201 
202 	d = fp->dwarf;
203 	if(dwarfenum(d, &s) < 0)
204 		return;
205 
206 	while(dwarfnextsymat(d, &s, 0) == 1)
207 	while(dwarfnextsymat(d, &s, 1) == 1){
208 		if(s.attrs.name == nil)
209 			continue;
210 		switch(s.attrs.tag){
211 		case TagSubprogram:
212 		case TagVariable:
213 			if(dwarftosym(fp, d, &s, &sym, 0) < 0)
214 				continue;
215 			_addsym(fp, &sym);
216 		}
217 	}
218 }
219 
220 static char*
221 regname(Dwarf *d, int i)
222 {
223 	if(i < 0 || i >= d->nreg)
224 		return nil;
225 	return d->reg[i];
226 }
227 
228 static int
229 dwarftosym(Fhdr *fp, Dwarf *d, DwarfSym *ds, Symbol *s, int infn)
230 {
231 	DwarfBuf buf;
232 	DwarfBlock b;
233 
234 	memset(s, 0, sizeof *s);
235 	s->u.dwarf.uoff = ds->uoff;
236 	s->u.dwarf.unit = ds->unit;
237 	switch(ds->attrs.tag){
238 	default:
239 		return -1;
240 	case TagUnspecifiedParameters:
241 		ds->attrs.name = "...";
242 		s->type = 'p';
243 		goto sym;
244 	case TagFormalParameter:
245 		s->type = 'p';
246 		s->class = CPARAM;
247 		goto sym;
248 	case TagSubprogram:
249 		s->type = 't';
250 		s->class = CTEXT;
251 		goto sym;
252 	case TagVariable:
253 		if(infn){
254 			s->type = 'a';
255 			s->class = CAUTO;
256 		}else{
257 			s->type = 'd';
258 			s->class = CDATA;
259 		}
260 	sym:
261 		s->name = ds->attrs.name;
262 		if(ds->attrs.have.lowpc){
263 			s->loc.type = LADDR;
264 			s->loc.addr = ds->attrs.lowpc;
265 			if(ds->attrs.have.highpc){
266 				s->hiloc.type = LADDR;
267 				s->hiloc.addr = ds->attrs.highpc;
268 			}
269 		}else if(ds->attrs.have.location == TConstant){
270 			s->loc.type = LADDR;
271 			s->loc.addr = ds->attrs.location.c;
272 		}else if(ds->attrs.have.location == TBlock){
273 			b = ds->attrs.location.b;
274 			if(b.len == 0)
275 				return -1;
276 			buf.p = b.data+1;
277 			buf.ep = b.data+b.len;
278 			buf.d = d;
279 			buf.addrsize = 0;
280 			if(b.data[0]==OpAddr){
281 				if(b.len != 5)
282 					return -1;
283 				s->loc.type = LADDR;
284 				s->loc.addr = dwarfgetaddr(&buf);
285 			}else if(OpReg0 <= b.data[0] && b.data[0] < OpReg0+0x20){
286 				if(b.len != 1 || (s->loc.reg = regname(d, b.data[0]-OpReg0)) == nil)
287 					return -1;
288 				s->loc.type = LREG;
289 			}else if(OpBreg0 <= b.data[0] && b.data[0] < OpBreg0+0x20){
290 				s->loc.type = LOFFSET;
291 				s->loc.reg = regname(d, b.data[0]-0x70);
292 				s->loc.offset = dwarfget128s(&buf);
293 				if(s->loc.reg == nil)
294 					return -1;
295 			}else if(b.data[0] == OpRegx){
296 				s->loc.type = LREG;
297 				s->loc.reg = regname(d, dwarfget128(&buf));
298 				if(s->loc.reg == nil)
299 					return -1;
300 			}else if(b.data[0] == OpFbreg){
301 				s->loc.type = LOFFSET;
302 				s->loc.reg = mach->fp;
303 				s->loc.offset = dwarfget128s(&buf);
304 			}else if(b.data[0] == OpBregx){
305 				s->loc.type = LOFFSET;
306 				s->loc.reg = regname(d, dwarfget128(&buf));
307 				s->loc.offset = dwarfget128s(&buf);
308 				if(s->loc.reg == nil)
309 					return -1;
310 			}else
311 				s->loc.type = LNONE;
312 			if(buf.p != buf.ep)
313 				s->loc.type = LNONE;
314 		}else
315 			return -1;
316 		if(ds->attrs.isexternal)
317 			s->type += 'A' - 'a';
318 		if(ds->attrs.tag==TagVariable && s->loc.type==LADDR && s->loc.addr>=fp->dataddr+fp->datsz)
319 			s->type += 'b' - 'd';
320 		s->fhdr = fp;
321 		return 0;
322 	}
323 }
324 
325 static int
326 dwarfeval(Dwarf *d, Map *map, Regs *regs, ulong cfa, int rno, DwarfExpr e, u64int *u)
327 {
328 	int i;
329 	u32int u4;
330 	u64int uu;
331 
332 	switch(e.type){
333 	case RuleUndef:
334 		*u = 0;
335 		return 0;
336 	case RuleSame:
337 		if(rno == -1){
338 			werrstr("pc cannot be `same'");
339 			return -1;
340 		}
341 		return rget(regs, regname(d, rno), u);
342 	case RuleRegister:
343 		if((i = windindex(regname(d, e.reg))) < 0)
344 			return -1;
345 		return rget(regs, regname(d, i), u);
346 	case RuleCfaOffset:
347 		if(cfa == 0){
348 			werrstr("unknown cfa");
349 			return -1;
350 		}
351 		if(get4(map, cfa + e.offset, &u4) < 0)
352 			return -1;
353 		*u = u4;
354 		return 0;
355 	case RuleRegOff:
356 		if(rget(regs, regname(d, e.reg), &uu) < 0)
357 			return -1;
358 		if(get4(map, uu+e.offset, &u4) < 0)
359 			return -1;
360 		*u = u4;
361 		return 0;
362 	case RuleLocation:
363 		werrstr("not evaluating dwarf loc expressions");
364 		return -1;
365 	}
366 	werrstr("not reached in dwarfeval");
367 	return -1;
368 }
369 
370 #if 0
371 static int
372 dwarfexprfmt(Fmt *fmt)
373 {
374 	DwarfExpr *e;
375 
376 	if((e = va_arg(fmt->args, DwarfExpr*)) == nil)
377 		return fmtstrcpy(fmt, "<nil>");
378 
379 	switch(e->type){
380 	case RuleUndef:
381 		return fmtstrcpy(fmt, "undef");
382 	case RuleSame:
383 		return fmtstrcpy(fmt, "same");
384 	case RuleCfaOffset:
385 		return fmtprint(fmt, "%ld(cfa)", e->offset);
386 	case RuleRegister:
387 		return fmtprint(fmt, "r%ld", e->reg);
388 	case RuleRegOff:
389 		return fmtprint(fmt, "%ld(r%ld)", e->offset, e->reg);
390 	case RuleLocation:
391 		return fmtprint(fmt, "l.%.*H", e->loc.len, e->loc.data);
392 	default:
393 		return fmtprint(fmt, "?%d", e->type);
394 	}
395 }
396 #endif
397 
398 static int
399 _dwarfunwind(Fhdr *fhdr, Map *map, Regs *regs, u64int *next, Symbol *sym)
400 {
401 	char *name;
402 	int i, j;
403 	u64int cfa, pc, u;
404 	Dwarf *d;
405 	DwarfExpr *e, epc, ecfa;
406 
407 
408 	/*
409 	 * Use dwarfunwind to tell us what to do.
410 	 */
411 	d = fhdr->dwarf;
412 	e = malloc(d->nreg*sizeof(e[0]));
413 	if(e == nil)
414 		return -1;
415 	if(rget(regs, mach->pc, &pc) < 0)
416 		goto err;
417 	if(dwarfunwind(d, pc, &ecfa, &epc, e, d->nreg) < 0)
418 		goto err;
419 
420 	/*
421 	 * Compute CFA.
422 	 */
423 	switch(ecfa.type){
424 	default:
425 		werrstr("invalid call-frame-address in _dwarfunwind");
426 		goto err;
427 	case RuleRegister:
428 		ecfa.offset = 0;
429 	case RuleRegOff:
430 		if((name = regname(d, ecfa.reg)) == nil){
431 			werrstr("invalid call-frame-address register %d", (int)ecfa.reg);
432 			goto err;
433 		}
434 		if(rget(regs, name, &cfa) < 0){
435 			werrstr("fetching %s for call-frame-address: %r", name);
436 			goto err;
437 		}
438 		cfa += ecfa.offset;
439 	}
440 
441 	/*
442 	 * Compute registers.
443 	 */
444 	for(i=0; i<d->nreg; i++){
445 		j = windindex(d->reg[i]);
446 		if(j == -1)
447 			continue;
448 		if(dwarfeval(d, map, regs, cfa, i, e[i], &u) < 0)
449 			u = ~(ulong)0;
450 		next[j] = u;
451 	}
452 
453 	/*
454 	 * Compute caller pc
455 	 */
456 	if(dwarfeval(d, map, regs, cfa, -1, epc, &u) < 0){
457 		werrstr("computing caller %s: %r", mach->pc);
458 		goto err;
459 	}
460 	next[windindex(mach->pc)] = u;
461 	free(e);
462 	return 0;
463 
464 err:
465 	free(e);
466 	return -1;
467 }