1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * dwarf-aux.c : libdw auxiliary interfaces
4 */
5
6 #include <errno.h>
7 #include <inttypes.h>
8 #include <stdbool.h>
9 #include <stdlib.h>
10 #include "debug.h"
11 #include "dwarf-aux.h"
12 #include "dwarf-regs.h"
13 #include "strbuf.h"
14 #include "string2.h"
15
16 /**
17 * cu_find_realpath - Find the realpath of the target file
18 * @cu_die: A DIE(dwarf information entry) of CU(compilation Unit)
19 * @fname: The tail filename of the target file
20 *
21 * Find the real(long) path of @fname in @cu_die.
22 */
23 const char *cu_find_realpath(Dwarf_Die *cu_die, const char *fname)
24 {
25 Dwarf_Files *files;
26 size_t nfiles, i;
27 const char *src = NULL;
28 int ret;
29
30 if (!fname)
31 return NULL;
32
33 ret = dwarf_getsrcfiles(cu_die, &files, &nfiles);
34 if (ret != 0)
35 return NULL;
36
37 for (i = 0; i < nfiles; i++) {
38 src = dwarf_filesrc(files, i, NULL, NULL);
39 if (strtailcmp(src, fname) == 0)
40 break;
41 }
42 if (i == nfiles)
43 return NULL;
44 return src;
45 }
46
47 /**
48 * cu_get_comp_dir - Get the path of compilation directory
49 * @cu_die: a CU DIE
50 *
51 * Get the path of compilation directory of given @cu_die.
52 * Since this depends on DW_AT_comp_dir, older gcc will not
53 * embedded it. In that case, this returns NULL.
54 */
55 const char *cu_get_comp_dir(Dwarf_Die *cu_die)
56 {
57 Dwarf_Attribute attr;
58 if (dwarf_attr(cu_die, DW_AT_comp_dir, &attr) == NULL)
59 return NULL;
60 return dwarf_formstring(&attr);
61 }
62
63 /* Unlike dwarf_getsrc_die(), cu_getsrc_die() only returns statement line */
64 static Dwarf_Line *cu_getsrc_die(Dwarf_Die *cu_die, Dwarf_Addr addr)
65 {
66 Dwarf_Addr laddr;
67 Dwarf_Lines *lines;
68 Dwarf_Line *line;
69 size_t nlines, l, u, n;
70 bool flag;
71
72 if (dwarf_getsrclines(cu_die, &lines, &nlines) != 0 ||
73 nlines == 0)
74 return NULL;
75
76 /* Lines are sorted by address, use binary search */
77 l = 0; u = nlines - 1;
78 while (l < u) {
79 n = u - (u - l) / 2;
80 line = dwarf_onesrcline(lines, n);
81 if (!line || dwarf_lineaddr(line, &laddr) != 0)
82 return NULL;
83 if (addr < laddr)
84 u = n - 1;
85 else
86 l = n;
87 }
88 /* Going backward to find the lowest line */
89 do {
90 line = dwarf_onesrcline(lines, --l);
91 if (!line || dwarf_lineaddr(line, &laddr) != 0)
92 return NULL;
93 } while (laddr == addr);
94 l++;
95 /* Going forward to find the statement line */
96 do {
97 line = dwarf_onesrcline(lines, l++);
98 if (!line || dwarf_lineaddr(line, &laddr) != 0 ||
99 dwarf_linebeginstatement(line, &flag) != 0)
100 return NULL;
101 if (laddr > addr)
102 return NULL;
103 } while (!flag);
104
105 return line;
106 }
107
108 /**
109 * cu_find_lineinfo - Get a line number and file name for given address
110 * @cu_die: a CU DIE
111 * @addr: An address
112 * @fname: a pointer which returns the file name string
113 * @lineno: a pointer which returns the line number
114 *
115 * Find a line number and file name for @addr in @cu_die.
116 */
117 int cu_find_lineinfo(Dwarf_Die *cu_die, Dwarf_Addr addr,
118 const char **fname, int *lineno)
119 {
120 Dwarf_Line *line;
121 Dwarf_Die die_mem;
122 Dwarf_Addr faddr;
123
124 if (die_find_realfunc(cu_die, addr, &die_mem)
125 && die_entrypc(&die_mem, &faddr) == 0 &&
126 faddr == addr) {
127 *fname = die_get_decl_file(&die_mem);
128 dwarf_decl_line(&die_mem, lineno);
129 goto out;
130 }
131
132 line = cu_getsrc_die(cu_die, addr);
133 if (line && dwarf_lineno(line, lineno) == 0) {
134 *fname = dwarf_linesrc(line, NULL, NULL);
135 if (!*fname)
136 /* line number is useless without filename */
137 *lineno = 0;
138 }
139
140 out:
141 return (*lineno && *fname) ? *lineno : -ENOENT;
142 }
143
144 static int __die_find_inline_cb(Dwarf_Die *die_mem, void *data);
145
146 /**
147 * cu_walk_functions_at - Walk on function DIEs at given address
148 * @cu_die: A CU DIE
149 * @addr: An address
150 * @callback: A callback which called with found DIEs
151 * @data: A user data
152 *
153 * Walk on function DIEs at given @addr in @cu_die. Passed DIEs
154 * should be subprogram or inlined-subroutines.
155 */
156 int cu_walk_functions_at(Dwarf_Die *cu_die, Dwarf_Addr addr,
157 int (*callback)(Dwarf_Die *, void *), void *data)
158 {
159 Dwarf_Die die_mem;
160 Dwarf_Die *sc_die;
161 int ret = -ENOENT;
162
163 /* Inlined function could be recursive. Trace it until fail */
164 for (sc_die = die_find_realfunc(cu_die, addr, &die_mem);
165 sc_die != NULL;
166 sc_die = die_find_child(sc_die, __die_find_inline_cb, &addr,
167 &die_mem)) {
168 ret = callback(sc_die, data);
169 if (ret)
170 break;
171 }
172
173 return ret;
174
175 }
176
177 /**
178 * die_get_linkage_name - Get the linkage name of the object
179 * @dw_die: A DIE of the object
180 *
181 * Get the linkage name attribute of given @dw_die.
182 * For C++ binary, the linkage name will be the mangled symbol.
183 */
184 const char *die_get_linkage_name(Dwarf_Die *dw_die)
185 {
186 Dwarf_Attribute attr;
187
188 if (dwarf_attr_integrate(dw_die, DW_AT_linkage_name, &attr) == NULL)
189 return NULL;
190 return dwarf_formstring(&attr);
191 }
192
193 /**
194 * die_compare_name - Compare diename and tname
195 * @dw_die: a DIE
196 * @tname: a string of target name
197 *
198 * Compare the name of @dw_die and @tname. Return false if @dw_die has no name.
199 */
200 bool die_compare_name(Dwarf_Die *dw_die, const char *tname)
201 {
202 const char *name;
203
204 name = dwarf_diename(dw_die);
205 return name ? (strcmp(tname, name) == 0) : false;
206 }
207
208 /**
209 * die_match_name - Match diename/linkage name and glob
210 * @dw_die: a DIE
211 * @glob: a string of target glob pattern
212 *
213 * Glob matching the name of @dw_die and @glob. Return false if matching fail.
214 * This also match linkage name.
215 */
216 bool die_match_name(Dwarf_Die *dw_die, const char *glob)
217 {
218 const char *name;
219
220 name = dwarf_diename(dw_die);
221 if (name && strglobmatch(name, glob))
222 return true;
223 /* fall back to check linkage name */
224 name = die_get_linkage_name(dw_die);
225 if (name && strglobmatch(name, glob))
226 return true;
227
228 return false;
229 }
230
231 /**
232 * die_get_call_lineno - Get callsite line number of inline-function instance
233 * @in_die: a DIE of an inlined function instance
234 *
235 * Get call-site line number of @in_die. This means from where the inline
236 * function is called.
237 */
238 int die_get_call_lineno(Dwarf_Die *in_die)
239 {
240 Dwarf_Attribute attr;
241 Dwarf_Word ret;
242
243 if (!dwarf_attr(in_die, DW_AT_call_line, &attr))
244 return -ENOENT;
245
246 dwarf_formudata(&attr, &ret);
247 return (int)ret;
248 }
249
250 /**
251 * die_get_type - Get type DIE
252 * @vr_die: a DIE of a variable
253 * @die_mem: where to store a type DIE
254 *
255 * Get a DIE of the type of given variable (@vr_die), and store
256 * it to die_mem. Return NULL if fails to get a type DIE.
257 */
258 Dwarf_Die *die_get_type(Dwarf_Die *vr_die, Dwarf_Die *die_mem)
259 {
260 Dwarf_Attribute attr;
261
262 if (dwarf_attr_integrate(vr_die, DW_AT_type, &attr) &&
263 dwarf_formref_die(&attr, die_mem))
264 return die_mem;
265 else
266 return NULL;
267 }
268
269 /* Get a type die, but skip qualifiers */
270 static Dwarf_Die *__die_get_real_type(Dwarf_Die *vr_die, Dwarf_Die *die_mem)
271 {
272 int tag;
273
274 do {
275 vr_die = die_get_type(vr_die, die_mem);
276 if (!vr_die)
277 break;
278 tag = dwarf_tag(vr_die);
279 } while (tag == DW_TAG_const_type ||
280 tag == DW_TAG_restrict_type ||
281 tag == DW_TAG_volatile_type ||
282 tag == DW_TAG_shared_type);
283
284 return vr_die;
285 }
286
287 /**
288 * die_get_real_type - Get a type die, but skip qualifiers and typedef
289 * @vr_die: a DIE of a variable
290 * @die_mem: where to store a type DIE
291 *
292 * Get a DIE of the type of given variable (@vr_die), and store
293 * it to die_mem. Return NULL if fails to get a type DIE.
294 * If the type is qualifiers (e.g. const) or typedef, this skips it
295 * and tries to find real type (structure or basic types, e.g. int).
296 */
297 Dwarf_Die *die_get_real_type(Dwarf_Die *vr_die, Dwarf_Die *die_mem)
298 {
299 do {
300 vr_die = __die_get_real_type(vr_die, die_mem);
301 } while (vr_die && dwarf_tag(vr_die) == DW_TAG_typedef);
302
303 return vr_die;
304 }
305
306 /* Get attribute and translate it as a udata */
307 static int die_get_attr_udata(Dwarf_Die *tp_die, unsigned int attr_name,
308 Dwarf_Word *result)
309 {
310 Dwarf_Attribute attr;
311
312 if (dwarf_attr_integrate(tp_die, attr_name, &attr) == NULL ||
313 dwarf_formudata(&attr, result) != 0)
314 return -ENOENT;
315
316 return 0;
317 }
318
319 /**
320 * die_is_signed_type - Check whether a type DIE is signed or not
321 * @tp_die: a DIE of a type
322 *
323 * Get the encoding of @tp_die and return true if the encoding
324 * is signed.
325 */
326 bool die_is_signed_type(Dwarf_Die *tp_die)
327 {
328 Dwarf_Word ret;
329
330 if (die_get_attr_udata(tp_die, DW_AT_encoding, &ret))
331 return false;
332
333 return (ret == DW_ATE_signed_char || ret == DW_ATE_signed ||
334 ret == DW_ATE_signed_fixed);
335 }
336
337 /**
338 * die_is_func_def - Ensure that this DIE is a subprogram and definition
339 * @dw_die: a DIE
340 *
341 * Ensure that this DIE is a subprogram and NOT a declaration. This
342 * returns true if @dw_die is a function definition.
343 **/
344 bool die_is_func_def(Dwarf_Die *dw_die)
345 {
346 Dwarf_Attribute attr;
347 Dwarf_Addr addr = 0;
348
349 if (dwarf_tag(dw_die) != DW_TAG_subprogram)
350 return false;
351
352 if (dwarf_attr(dw_die, DW_AT_declaration, &attr))
353 return false;
354
355 /*
356 * DW_AT_declaration can be lost from function declaration
357 * by gcc's bug #97060.
358 * So we need to check this subprogram DIE has DW_AT_inline
359 * or an entry address.
360 */
361 if (!dwarf_attr(dw_die, DW_AT_inline, &attr) &&
362 die_entrypc(dw_die, &addr) < 0)
363 return false;
364
365 return true;
366 }
367
368 /**
369 * die_entrypc - Returns entry PC (the lowest address) of a DIE
370 * @dw_die: a DIE
371 * @addr: where to store entry PC
372 *
373 * Since dwarf_entrypc() does not return entry PC if the DIE has only address
374 * range, we have to use this to retrieve the lowest address from the address
375 * range attribute.
376 */
377 int die_entrypc(Dwarf_Die *dw_die, Dwarf_Addr *addr)
378 {
379 Dwarf_Addr base, end;
380 Dwarf_Attribute attr;
381
382 if (!addr)
383 return -EINVAL;
384
385 if (dwarf_entrypc(dw_die, addr) == 0)
386 return 0;
387
388 /*
389 * Since the dwarf_ranges() will return 0 if there is no
390 * DW_AT_ranges attribute, we should check it first.
391 */
392 if (!dwarf_attr(dw_die, DW_AT_ranges, &attr))
393 return -ENOENT;
394
395 return dwarf_ranges(dw_die, 0, &base, addr, &end) < 0 ? -ENOENT : 0;
396 }
397
398 /**
399 * die_is_func_instance - Ensure that this DIE is an instance of a subprogram
400 * @dw_die: a DIE
401 *
402 * Ensure that this DIE is an instance (which has an entry address).
403 * This returns true if @dw_die is a function instance. If not, the @dw_die
404 * must be a prototype. You can use die_walk_instances() to find actual
405 * instances.
406 **/
407 bool die_is_func_instance(Dwarf_Die *dw_die)
408 {
409 Dwarf_Addr tmp;
410 Dwarf_Attribute attr_mem;
411 int tag = dwarf_tag(dw_die);
412
413 if (tag != DW_TAG_subprogram &&
414 tag != DW_TAG_inlined_subroutine)
415 return false;
416
417 return dwarf_entrypc(dw_die, &tmp) == 0 ||
418 dwarf_attr(dw_die, DW_AT_ranges, &attr_mem) != NULL;
419 }
420
421 /**
422 * die_get_data_member_location - Get the data-member offset
423 * @mb_die: a DIE of a member of a data structure
424 * @offs: The offset of the member in the data structure
425 *
426 * Get the offset of @mb_die in the data structure including @mb_die, and
427 * stores result offset to @offs. If any error occurs this returns errno.
428 */
429 int die_get_data_member_location(Dwarf_Die *mb_die, Dwarf_Word *offs)
430 {
431 Dwarf_Attribute attr;
432 Dwarf_Op *expr;
433 size_t nexpr;
434 int ret;
435
436 if (dwarf_attr(mb_die, DW_AT_data_member_location, &attr) == NULL)
437 return -ENOENT;
438
439 if (dwarf_formudata(&attr, offs) != 0) {
440 /* DW_AT_data_member_location should be DW_OP_plus_uconst */
441 ret = dwarf_getlocation(&attr, &expr, &nexpr);
442 if (ret < 0 || nexpr == 0)
443 return -ENOENT;
444
445 if (expr[0].atom != DW_OP_plus_uconst || nexpr != 1) {
446 pr_debug("Unable to get offset:Unexpected OP %x (%zd)\n",
447 expr[0].atom, nexpr);
448 return -ENOTSUP;
449 }
450 *offs = (Dwarf_Word)expr[0].number;
451 }
452 return 0;
453 }
454
455 /* Get the call file index number in CU DIE */
456 static int die_get_call_fileno(Dwarf_Die *in_die)
457 {
458 Dwarf_Word idx;
459
460 if (die_get_attr_udata(in_die, DW_AT_call_file, &idx) == 0)
461 return (int)idx;
462 else
463 return -ENOENT;
464 }
465
466 /* Get the declared file index number in CU DIE */
467 static int die_get_decl_fileno(Dwarf_Die *pdie)
468 {
469 Dwarf_Word idx;
470
471 if (die_get_attr_udata(pdie, DW_AT_decl_file, &idx) == 0)
472 return (int)idx;
473 else
474 return -ENOENT;
475 }
476
477 /* Return the file name by index */
478 static const char *die_get_file_name(Dwarf_Die *dw_die, int idx)
479 {
480 Dwarf_Die cu_die;
481 Dwarf_Files *files;
482 Dwarf_Attribute attr_mem;
483
484 if (idx < 0 || !dwarf_attr_integrate(dw_die, DW_AT_decl_file, &attr_mem) ||
485 !dwarf_cu_die(attr_mem.cu, &cu_die, NULL, NULL, NULL, NULL, NULL, NULL) ||
486 dwarf_getsrcfiles(&cu_die, &files, NULL) != 0)
487 return NULL;
488
489 return dwarf_filesrc(files, idx, NULL, NULL);
490 }
491
492 /**
493 * die_get_call_file - Get callsite file name of inlined function instance
494 * @in_die: a DIE of an inlined function instance
495 *
496 * Get call-site file name of @in_die. This means from which file the inline
497 * function is called.
498 */
499 const char *die_get_call_file(Dwarf_Die *in_die)
500 {
501 return die_get_file_name(in_die, die_get_call_fileno(in_die));
502 }
503
504 /**
505 * die_get_decl_file - Find the declared file name of this DIE
506 * @dw_die: a DIE for something declared.
507 *
508 * Get declared file name of @dw_die.
509 * NOTE: Since some version of clang DWARF5 implementation incorrectly uses
510 * file index 0 for DW_AT_decl_file, die_get_decl_file() will return NULL for
511 * such cases. Use this function instead.
512 */
513 const char *die_get_decl_file(Dwarf_Die *dw_die)
514 {
515 return die_get_file_name(dw_die, die_get_decl_fileno(dw_die));
516 }
517
518 /**
519 * die_find_child - Generic DIE search function in DIE tree
520 * @rt_die: a root DIE
521 * @callback: a callback function
522 * @data: a user data passed to the callback function
523 * @die_mem: a buffer for result DIE
524 *
525 * Trace DIE tree from @rt_die and call @callback for each child DIE.
526 * If @callback returns DIE_FIND_CB_END, this stores the DIE into
527 * @die_mem and returns it. If @callback returns DIE_FIND_CB_CONTINUE,
528 * this continues to trace the tree. Optionally, @callback can return
529 * DIE_FIND_CB_CHILD and DIE_FIND_CB_SIBLING, those means trace only
530 * the children and trace only the siblings respectively.
531 * Returns NULL if @callback can't find any appropriate DIE.
532 */
533 Dwarf_Die *die_find_child(Dwarf_Die *rt_die,
534 int (*callback)(Dwarf_Die *, void *),
535 void *data, Dwarf_Die *die_mem)
536 {
537 Dwarf_Die child_die;
538 int ret;
539
540 ret = dwarf_child(rt_die, die_mem);
541 if (ret != 0)
542 return NULL;
543
544 do {
545 ret = callback(die_mem, data);
546 if (ret == DIE_FIND_CB_END)
547 return die_mem;
548
549 if ((ret & DIE_FIND_CB_CHILD) &&
550 die_find_child(die_mem, callback, data, &child_die)) {
551 memcpy(die_mem, &child_die, sizeof(Dwarf_Die));
552 return die_mem;
553 }
554 } while ((ret & DIE_FIND_CB_SIBLING) &&
555 dwarf_siblingof(die_mem, die_mem) == 0);
556
557 return NULL;
558 }
559
560 struct __addr_die_search_param {
561 Dwarf_Addr addr;
562 Dwarf_Die *die_mem;
563 };
564
565 static int __die_search_func_tail_cb(Dwarf_Die *fn_die, void *data)
566 {
567 struct __addr_die_search_param *ad = data;
568 Dwarf_Addr addr = 0;
569
570 if (dwarf_tag(fn_die) == DW_TAG_subprogram &&
571 !dwarf_highpc(fn_die, &addr) &&
572 addr == ad->addr) {
573 memcpy(ad->die_mem, fn_die, sizeof(Dwarf_Die));
574 return DWARF_CB_ABORT;
575 }
576 return DWARF_CB_OK;
577 }
578
579 /**
580 * die_find_tailfunc - Search for a non-inlined function with tail call at
581 * given address
582 * @cu_die: a CU DIE which including @addr
583 * @addr: target address
584 * @die_mem: a buffer for result DIE
585 *
586 * Search for a non-inlined function DIE with tail call at @addr. Stores the
587 * DIE to @die_mem and returns it if found. Returns NULL if failed.
588 */
589 Dwarf_Die *die_find_tailfunc(Dwarf_Die *cu_die, Dwarf_Addr addr,
590 Dwarf_Die *die_mem)
591 {
592 struct __addr_die_search_param ad;
593 ad.addr = addr;
594 ad.die_mem = die_mem;
595 /* dwarf_getscopes can't find subprogram. */
596 if (!dwarf_getfuncs(cu_die, __die_search_func_tail_cb, &ad, 0))
597 return NULL;
598 else
599 return die_mem;
600 }
601
602 /* die_find callback for non-inlined function search */
603 static int __die_search_func_cb(Dwarf_Die *fn_die, void *data)
604 {
605 struct __addr_die_search_param *ad = data;
606
607 /*
608 * Since a declaration entry doesn't has given pc, this always returns
609 * function definition entry.
610 */
611 if (dwarf_tag(fn_die) == DW_TAG_subprogram &&
612 dwarf_haspc(fn_die, ad->addr)) {
613 memcpy(ad->die_mem, fn_die, sizeof(Dwarf_Die));
614 return DWARF_CB_ABORT;
615 }
616 return DWARF_CB_OK;
617 }
618
619 /**
620 * die_find_realfunc - Search a non-inlined function at given address
621 * @cu_die: a CU DIE which including @addr
622 * @addr: target address
623 * @die_mem: a buffer for result DIE
624 *
625 * Search a non-inlined function DIE which includes @addr. Stores the
626 * DIE to @die_mem and returns it if found. Returns NULL if failed.
627 */
628 Dwarf_Die *die_find_realfunc(Dwarf_Die *cu_die, Dwarf_Addr addr,
629 Dwarf_Die *die_mem)
630 {
631 struct __addr_die_search_param ad;
632 ad.addr = addr;
633 ad.die_mem = die_mem;
634 /* dwarf_getscopes can't find subprogram. */
635 if (!dwarf_getfuncs(cu_die, __die_search_func_cb, &ad, 0))
636 return NULL;
637 else
638 return die_mem;
639 }
640
641 /* die_find callback for inline function search */
642 static int __die_find_inline_cb(Dwarf_Die *die_mem, void *data)
643 {
644 Dwarf_Addr *addr = data;
645
646 if (dwarf_tag(die_mem) == DW_TAG_inlined_subroutine &&
647 dwarf_haspc(die_mem, *addr))
648 return DIE_FIND_CB_END;
649
650 return DIE_FIND_CB_CONTINUE;
651 }
652
653 /**
654 * die_find_top_inlinefunc - Search the top inlined function at given address
655 * @sp_die: a subprogram DIE which including @addr
656 * @addr: target address
657 * @die_mem: a buffer for result DIE
658 *
659 * Search an inlined function DIE which includes @addr. Stores the
660 * DIE to @die_mem and returns it if found. Returns NULL if failed.
661 * Even if several inlined functions are expanded recursively, this
662 * doesn't trace it down, and returns the topmost one.
663 */
664 Dwarf_Die *die_find_top_inlinefunc(Dwarf_Die *sp_die, Dwarf_Addr addr,
665 Dwarf_Die *die_mem)
666 {
667 return die_find_child(sp_die, __die_find_inline_cb, &addr, die_mem);
668 }
669
670 /**
671 * die_find_inlinefunc - Search an inlined function at given address
672 * @sp_die: a subprogram DIE which including @addr
673 * @addr: target address
674 * @die_mem: a buffer for result DIE
675 *
676 * Search an inlined function DIE which includes @addr. Stores the
677 * DIE to @die_mem and returns it if found. Returns NULL if failed.
678 * If several inlined functions are expanded recursively, this trace
679 * it down and returns deepest one.
680 */
681 Dwarf_Die *die_find_inlinefunc(Dwarf_Die *sp_die, Dwarf_Addr addr,
682 Dwarf_Die *die_mem)
683 {
684 Dwarf_Die tmp_die;
685
686 sp_die = die_find_child(sp_die, __die_find_inline_cb, &addr, &tmp_die);
687 if (!sp_die)
688 return NULL;
689
690 /* Inlined function could be recursive. Trace it until fail */
691 while (sp_die) {
692 memcpy(die_mem, sp_die, sizeof(Dwarf_Die));
693 sp_die = die_find_child(sp_die, __die_find_inline_cb, &addr,
694 &tmp_die);
695 }
696
697 return die_mem;
698 }
699
700 static int __die_find_func_rettype_cb(Dwarf_Die *die_mem, void *data)
701 {
702 const char *func_name;
703
704 if (dwarf_tag(die_mem) != DW_TAG_subprogram)
705 return DIE_FIND_CB_SIBLING;
706
707 func_name = dwarf_diename(die_mem);
708 if (func_name && !strcmp(func_name, data))
709 return DIE_FIND_CB_END;
710
711 return DIE_FIND_CB_SIBLING;
712 }
713
714 /**
715 * die_find_func_rettype - Search a return type of function
716 * @cu_die: a CU DIE
717 * @name: target function name
718 * @die_mem: a buffer for result DIE
719 *
720 * Search a non-inlined function which matches to @name and stores the
721 * return type of the function to @die_mem and returns it if found.
722 * Returns NULL if failed. Note that it doesn't needs to find a
723 * definition of the function, so it doesn't match with address.
724 * Most likely, it can find a declaration at the top level. Thus the
725 * callback function continues to sibling entries only.
726 */
727 Dwarf_Die *die_find_func_rettype(Dwarf_Die *cu_die, const char *name,
728 Dwarf_Die *die_mem)
729 {
730 Dwarf_Die tmp_die;
731
732 cu_die = die_find_child(cu_die, __die_find_func_rettype_cb,
733 (void *)name, &tmp_die);
734 if (!cu_die)
735 return NULL;
736
737 if (die_get_real_type(&tmp_die, die_mem) == NULL)
738 return NULL;
739
740 return die_mem;
741 }
742
743 struct __instance_walk_param {
744 void *addr;
745 int (*callback)(Dwarf_Die *, void *);
746 void *data;
747 int retval;
748 };
749
750 static int __die_walk_instances_cb(Dwarf_Die *inst, void *data)
751 {
752 struct __instance_walk_param *iwp = data;
753 Dwarf_Attribute attr_mem;
754 Dwarf_Die origin_mem;
755 Dwarf_Attribute *attr;
756 Dwarf_Die *origin;
757 int tmp;
758
759 if (!die_is_func_instance(inst))
760 return DIE_FIND_CB_CONTINUE;
761
762 attr = dwarf_attr(inst, DW_AT_abstract_origin, &attr_mem);
763 if (attr == NULL)
764 return DIE_FIND_CB_CONTINUE;
765
766 origin = dwarf_formref_die(attr, &origin_mem);
767 if (origin == NULL || origin->addr != iwp->addr)
768 return DIE_FIND_CB_CONTINUE;
769
770 /* Ignore redundant instances */
771 if (dwarf_tag(inst) == DW_TAG_inlined_subroutine) {
772 dwarf_decl_line(origin, &tmp);
773 if (die_get_call_lineno(inst) == tmp) {
774 tmp = die_get_decl_fileno(origin);
775 if (die_get_call_fileno(inst) == tmp)
776 return DIE_FIND_CB_CONTINUE;
777 }
778 }
779
780 iwp->retval = iwp->callback(inst, iwp->data);
781
782 return (iwp->retval) ? DIE_FIND_CB_END : DIE_FIND_CB_CONTINUE;
783 }
784
785 /**
786 * die_walk_instances - Walk on instances of given DIE
787 * @or_die: an abstract original DIE
788 * @callback: a callback function which is called with instance DIE
789 * @data: user data
790 *
791 * Walk on the instances of give @in_die. @in_die must be an inlined function
792 * declaration. This returns the return value of @callback if it returns
793 * non-zero value, or -ENOENT if there is no instance.
794 */
795 int die_walk_instances(Dwarf_Die *or_die, int (*callback)(Dwarf_Die *, void *),
796 void *data)
797 {
798 Dwarf_Die cu_die;
799 Dwarf_Die die_mem;
800 struct __instance_walk_param iwp = {
801 .addr = or_die->addr,
802 .callback = callback,
803 .data = data,
804 .retval = -ENOENT,
805 };
806
807 if (dwarf_diecu(or_die, &cu_die, NULL, NULL) == NULL)
808 return -ENOENT;
809
810 die_find_child(&cu_die, __die_walk_instances_cb, &iwp, &die_mem);
811
812 return iwp.retval;
813 }
814
815 /* Line walker internal parameters */
816 struct __line_walk_param {
817 bool recursive;
818 line_walk_callback_t callback;
819 void *data;
820 int retval;
821 };
822
823 static int __die_walk_funclines_cb(Dwarf_Die *in_die, void *data)
824 {
825 struct __line_walk_param *lw = data;
826 Dwarf_Addr addr = 0;
827 const char *fname;
828 int lineno;
829
830 if (dwarf_tag(in_die) == DW_TAG_inlined_subroutine) {
831 fname = die_get_call_file(in_die);
832 lineno = die_get_call_lineno(in_die);
833 if (fname && lineno > 0 && die_entrypc(in_die, &addr) == 0) {
834 lw->retval = lw->callback(fname, lineno, addr, lw->data);
835 if (lw->retval != 0)
836 return DIE_FIND_CB_END;
837 }
838 if (!lw->recursive)
839 return DIE_FIND_CB_SIBLING;
840 }
841
842 if (addr) {
843 fname = die_get_decl_file(in_die);
844 if (fname && dwarf_decl_line(in_die, &lineno) == 0) {
845 lw->retval = lw->callback(fname, lineno, addr, lw->data);
846 if (lw->retval != 0)
847 return DIE_FIND_CB_END;
848 }
849 }
850
851 /* Continue to search nested inlined function call-sites */
852 return DIE_FIND_CB_CONTINUE;
853 }
854
855 /* Walk on lines of blocks included in given DIE */
856 static int __die_walk_funclines(Dwarf_Die *sp_die, bool recursive,
857 line_walk_callback_t callback, void *data)
858 {
859 struct __line_walk_param lw = {
860 .recursive = recursive,
861 .callback = callback,
862 .data = data,
863 .retval = 0,
864 };
865 Dwarf_Die die_mem;
866 Dwarf_Addr addr;
867 const char *fname;
868 int lineno;
869
870 /* Handle function declaration line */
871 fname = die_get_decl_file(sp_die);
872 if (fname && dwarf_decl_line(sp_die, &lineno) == 0 &&
873 die_entrypc(sp_die, &addr) == 0) {
874 lw.retval = callback(fname, lineno, addr, data);
875 if (lw.retval != 0)
876 goto done;
877 }
878 die_find_child(sp_die, __die_walk_funclines_cb, &lw, &die_mem);
879 done:
880 return lw.retval;
881 }
882
883 static int __die_walk_culines_cb(Dwarf_Die *sp_die, void *data)
884 {
885 struct __line_walk_param *lw = data;
886
887 /*
888 * Since inlined function can include another inlined function in
889 * the same file, we need to walk in it recursively.
890 */
891 lw->retval = __die_walk_funclines(sp_die, true, lw->callback, lw->data);
892 if (lw->retval != 0)
893 return DWARF_CB_ABORT;
894
895 return DWARF_CB_OK;
896 }
897
898 /**
899 * die_walk_lines - Walk on lines inside given DIE
900 * @rt_die: a root DIE (CU, subprogram or inlined_subroutine)
901 * @callback: callback routine
902 * @data: user data
903 *
904 * Walk on all lines inside given @rt_die and call @callback on each line.
905 * If the @rt_die is a function, walk only on the lines inside the function,
906 * otherwise @rt_die must be a CU DIE.
907 * Note that this walks not only dwarf line list, but also function entries
908 * and inline call-site.
909 */
910 int die_walk_lines(Dwarf_Die *rt_die, line_walk_callback_t callback, void *data)
911 {
912 Dwarf_Lines *lines;
913 Dwarf_Line *line;
914 Dwarf_Addr addr;
915 const char *fname, *decf = NULL, *inf = NULL;
916 int lineno, ret = 0;
917 int decl = 0, inl;
918 Dwarf_Die die_mem, *cu_die;
919 size_t nlines, i;
920 bool flag;
921
922 /* Get the CU die */
923 if (dwarf_tag(rt_die) != DW_TAG_compile_unit) {
924 cu_die = dwarf_diecu(rt_die, &die_mem, NULL, NULL);
925 dwarf_decl_line(rt_die, &decl);
926 decf = die_get_decl_file(rt_die);
927 if (!decf) {
928 pr_debug2("Failed to get the declared file name of %s\n",
929 dwarf_diename(rt_die));
930 return -EINVAL;
931 }
932 } else
933 cu_die = rt_die;
934 if (!cu_die) {
935 pr_debug2("Failed to get CU from given DIE.\n");
936 return -EINVAL;
937 }
938
939 /* Get lines list in the CU */
940 if (dwarf_getsrclines(cu_die, &lines, &nlines) != 0) {
941 pr_debug2("Failed to get source lines on this CU.\n");
942 return -ENOENT;
943 }
944 pr_debug2("Get %zd lines from this CU\n", nlines);
945
946 /* Walk on the lines on lines list */
947 for (i = 0; i < nlines; i++) {
948 line = dwarf_onesrcline(lines, i);
949 if (line == NULL ||
950 dwarf_lineno(line, &lineno) != 0 ||
951 dwarf_lineaddr(line, &addr) != 0) {
952 pr_debug2("Failed to get line info. "
953 "Possible error in debuginfo.\n");
954 continue;
955 }
956 /* Skip end-of-sequence */
957 if (dwarf_lineendsequence(line, &flag) != 0 || flag)
958 continue;
959 /* Skip Non statement line-info */
960 if (dwarf_linebeginstatement(line, &flag) != 0 || !flag)
961 continue;
962 /* Filter lines based on address */
963 if (rt_die != cu_die) {
964 /*
965 * Address filtering
966 * The line is included in given function, and
967 * no inline block includes it.
968 */
969 if (!dwarf_haspc(rt_die, addr))
970 continue;
971
972 if (die_find_inlinefunc(rt_die, addr, &die_mem)) {
973 /* Call-site check */
974 inf = die_get_call_file(&die_mem);
975 if ((inf && !strcmp(inf, decf)) &&
976 die_get_call_lineno(&die_mem) == lineno)
977 goto found;
978
979 dwarf_decl_line(&die_mem, &inl);
980 if (inl != decl ||
981 decf != die_get_decl_file(&die_mem))
982 continue;
983 }
984 }
985 found:
986 /* Get source line */
987 fname = dwarf_linesrc(line, NULL, NULL);
988
989 ret = callback(fname, lineno, addr, data);
990 if (ret != 0)
991 return ret;
992 }
993
994 /*
995 * Dwarf lines doesn't include function declarations and inlined
996 * subroutines. We have to check functions list or given function.
997 */
998 if (rt_die != cu_die)
999 /*
1000 * Don't need walk inlined functions recursively, because
1001 * inner inlined functions don't have the lines of the
1002 * specified function.
1003 */
1004 ret = __die_walk_funclines(rt_die, false, callback, data);
1005 else {
1006 struct __line_walk_param param = {
1007 .callback = callback,
1008 .data = data,
1009 .retval = 0,
1010 };
1011 dwarf_getfuncs(cu_die, __die_walk_culines_cb, ¶m, 0);
1012 ret = param.retval;
1013 }
1014
1015 return ret;
1016 }
1017
1018 struct __find_variable_param {
1019 const char *name;
1020 Dwarf_Addr addr;
1021 };
1022
1023 static int __die_find_variable_cb(Dwarf_Die *die_mem, void *data)
1024 {
1025 struct __find_variable_param *fvp = data;
1026 Dwarf_Attribute attr;
1027 int tag;
1028
1029 tag = dwarf_tag(die_mem);
1030 if ((tag == DW_TAG_formal_parameter ||
1031 tag == DW_TAG_variable) &&
1032 die_compare_name(die_mem, fvp->name) &&
1033 /*
1034 * Does the DIE have location information or const value
1035 * or external instance?
1036 */
1037 (dwarf_attr(die_mem, DW_AT_external, &attr) ||
1038 dwarf_attr(die_mem, DW_AT_location, &attr) ||
1039 dwarf_attr(die_mem, DW_AT_const_value, &attr)))
1040 return DIE_FIND_CB_END;
1041 if (dwarf_haspc(die_mem, fvp->addr))
1042 return DIE_FIND_CB_CONTINUE;
1043 else
1044 return DIE_FIND_CB_SIBLING;
1045 }
1046
1047 /**
1048 * die_find_variable_at - Find a given name variable at given address
1049 * @sp_die: a function DIE
1050 * @name: variable name
1051 * @addr: address
1052 * @die_mem: a buffer for result DIE
1053 *
1054 * Find a variable DIE called @name at @addr in @sp_die.
1055 */
1056 Dwarf_Die *die_find_variable_at(Dwarf_Die *sp_die, const char *name,
1057 Dwarf_Addr addr, Dwarf_Die *die_mem)
1058 {
1059 struct __find_variable_param fvp = { .name = name, .addr = addr};
1060
1061 return die_find_child(sp_die, __die_find_variable_cb, (void *)&fvp,
1062 die_mem);
1063 }
1064
1065 static int __die_find_member_cb(Dwarf_Die *die_mem, void *data)
1066 {
1067 const char *name = data;
1068
1069 if (dwarf_tag(die_mem) == DW_TAG_member) {
1070 if (die_compare_name(die_mem, name))
1071 return DIE_FIND_CB_END;
1072 else if (!dwarf_diename(die_mem)) { /* Unnamed structure */
1073 Dwarf_Die type_die, tmp_die;
1074 if (die_get_type(die_mem, &type_die) &&
1075 die_find_member(&type_die, name, &tmp_die))
1076 return DIE_FIND_CB_END;
1077 }
1078 }
1079 return DIE_FIND_CB_SIBLING;
1080 }
1081
1082 /**
1083 * die_find_member - Find a given name member in a data structure
1084 * @st_die: a data structure type DIE
1085 * @name: member name
1086 * @die_mem: a buffer for result DIE
1087 *
1088 * Find a member DIE called @name in @st_die.
1089 */
1090 Dwarf_Die *die_find_member(Dwarf_Die *st_die, const char *name,
1091 Dwarf_Die *die_mem)
1092 {
1093 return die_find_child(st_die, __die_find_member_cb, (void *)name,
1094 die_mem);
1095 }
1096
1097 /**
1098 * die_get_typename_from_type - Get the name of given type DIE
1099 * @type_die: a type DIE
1100 * @buf: a strbuf for result type name
1101 *
1102 * Get the name of @type_die and stores it to @buf. Return 0 if succeeded.
1103 * and Return -ENOENT if failed to find type name.
1104 * Note that the result will stores typedef name if possible, and stores
1105 * "*(function_type)" if the type is a function pointer.
1106 */
1107 int die_get_typename_from_type(Dwarf_Die *type_die, struct strbuf *buf)
1108 {
1109 int tag, ret;
1110 const char *tmp = "";
1111
1112 tag = dwarf_tag(type_die);
1113 if (tag == DW_TAG_pointer_type)
1114 tmp = "*";
1115 else if (tag == DW_TAG_array_type)
1116 tmp = "[]";
1117 else if (tag == DW_TAG_subroutine_type) {
1118 /* Function pointer */
1119 return strbuf_add(buf, "(function_type)", 15);
1120 } else {
1121 const char *name = dwarf_diename(type_die);
1122
1123 if (tag == DW_TAG_union_type)
1124 tmp = "union ";
1125 else if (tag == DW_TAG_structure_type)
1126 tmp = "struct ";
1127 else if (tag == DW_TAG_enumeration_type)
1128 tmp = "enum ";
1129 else if (name == NULL)
1130 return -ENOENT;
1131 /* Write a base name */
1132 return strbuf_addf(buf, "%s%s", tmp, name ?: "");
1133 }
1134 ret = die_get_typename(type_die, buf);
1135 if (ret < 0) {
1136 /* void pointer has no type attribute */
1137 if (tag == DW_TAG_pointer_type && ret == -ENOENT)
1138 return strbuf_addf(buf, "void*");
1139
1140 return ret;
1141 }
1142 return strbuf_addstr(buf, tmp);
1143 }
1144
1145 /**
1146 * die_get_typename - Get the name of given variable DIE
1147 * @vr_die: a variable DIE
1148 * @buf: a strbuf for result type name
1149 *
1150 * Get the name of @vr_die and stores it to @buf. Return 0 if succeeded.
1151 * and Return -ENOENT if failed to find type name.
1152 * Note that the result will stores typedef name if possible, and stores
1153 * "*(function_type)" if the type is a function pointer.
1154 */
1155 int die_get_typename(Dwarf_Die *vr_die, struct strbuf *buf)
1156 {
1157 Dwarf_Die type;
1158
1159 if (__die_get_real_type(vr_die, &type) == NULL)
1160 return -ENOENT;
1161
1162 return die_get_typename_from_type(&type, buf);
1163 }
1164
1165 /**
1166 * die_get_varname - Get the name and type of given variable DIE
1167 * @vr_die: a variable DIE
1168 * @buf: a strbuf for type and variable name
1169 *
1170 * Get the name and type of @vr_die and stores it in @buf as "type\tname".
1171 */
1172 int die_get_varname(Dwarf_Die *vr_die, struct strbuf *buf)
1173 {
1174 int ret;
1175
1176 ret = die_get_typename(vr_die, buf);
1177 if (ret < 0) {
1178 pr_debug("Failed to get type, make it unknown.\n");
1179 ret = strbuf_add(buf, "(unknown_type)", 14);
1180 }
1181
1182 return ret < 0 ? ret : strbuf_addf(buf, "\t%s", dwarf_diename(vr_die));
1183 }
1184
1185 #if defined(HAVE_DWARF_GETLOCATIONS_SUPPORT) || defined(HAVE_DWARF_CFI_SUPPORT)
1186 static int reg_from_dwarf_op(Dwarf_Op *op)
1187 {
1188 switch (op->atom) {
1189 case DW_OP_reg0 ... DW_OP_reg31:
1190 return op->atom - DW_OP_reg0;
1191 case DW_OP_breg0 ... DW_OP_breg31:
1192 return op->atom - DW_OP_breg0;
1193 case DW_OP_regx:
1194 case DW_OP_bregx:
1195 return op->number;
1196 case DW_OP_fbreg:
1197 return DWARF_REG_FB;
1198 default:
1199 break;
1200 }
1201 return -1;
1202 }
1203
1204 static int offset_from_dwarf_op(Dwarf_Op *op)
1205 {
1206 switch (op->atom) {
1207 case DW_OP_reg0 ... DW_OP_reg31:
1208 case DW_OP_regx:
1209 return 0;
1210 case DW_OP_breg0 ... DW_OP_breg31:
1211 case DW_OP_fbreg:
1212 return op->number;
1213 case DW_OP_bregx:
1214 return op->number2;
1215 default:
1216 break;
1217 }
1218 return -1;
1219 }
1220
1221 static bool check_allowed_ops(Dwarf_Op *ops, size_t nops)
1222 {
1223 /* The first op is checked separately */
1224 ops++;
1225 nops--;
1226
1227 /*
1228 * It needs to make sure if the location expression matches to the given
1229 * register and offset exactly. Thus it rejects any complex expressions
1230 * and only allows a few of selected operators that doesn't change the
1231 * location.
1232 */
1233 while (nops) {
1234 switch (ops->atom) {
1235 case DW_OP_stack_value:
1236 case DW_OP_deref_size:
1237 case DW_OP_deref:
1238 case DW_OP_piece:
1239 break;
1240 default:
1241 return false;
1242 }
1243 ops++;
1244 nops--;
1245 }
1246 return true;
1247 }
1248 #endif /* HAVE_DWARF_GETLOCATIONS_SUPPORT || HAVE_DWARF_CFI_SUPPORT */
1249
1250 #ifdef HAVE_DWARF_GETLOCATIONS_SUPPORT
1251 /**
1252 * die_get_var_innermost_scope - Get innermost scope range of given variable DIE
1253 * @sp_die: a subprogram DIE
1254 * @vr_die: a variable DIE
1255 * @buf: a strbuf for variable byte offset range
1256 *
1257 * Get the innermost scope range of @vr_die and stores it in @buf as
1258 * "@<function_name+[NN-NN,NN-NN]>".
1259 */
1260 static int die_get_var_innermost_scope(Dwarf_Die *sp_die, Dwarf_Die *vr_die,
1261 struct strbuf *buf)
1262 {
1263 Dwarf_Die *scopes;
1264 int count;
1265 size_t offset = 0;
1266 Dwarf_Addr base;
1267 Dwarf_Addr start, end;
1268 Dwarf_Addr entry;
1269 int ret;
1270 bool first = true;
1271 const char *name;
1272
1273 ret = die_entrypc(sp_die, &entry);
1274 if (ret)
1275 return ret;
1276
1277 name = dwarf_diename(sp_die);
1278 if (!name)
1279 return -ENOENT;
1280
1281 count = dwarf_getscopes_die(vr_die, &scopes);
1282
1283 /* (*SCOPES)[1] is the DIE for the scope containing that scope */
1284 if (count <= 1) {
1285 ret = -EINVAL;
1286 goto out;
1287 }
1288
1289 while ((offset = dwarf_ranges(&scopes[1], offset, &base,
1290 &start, &end)) > 0) {
1291 start -= entry;
1292 end -= entry;
1293
1294 if (first) {
1295 ret = strbuf_addf(buf, "@<%s+[%" PRIu64 "-%" PRIu64,
1296 name, start, end);
1297 first = false;
1298 } else {
1299 ret = strbuf_addf(buf, ",%" PRIu64 "-%" PRIu64,
1300 start, end);
1301 }
1302 if (ret < 0)
1303 goto out;
1304 }
1305
1306 if (!first)
1307 ret = strbuf_add(buf, "]>", 2);
1308
1309 out:
1310 free(scopes);
1311 return ret;
1312 }
1313
1314 /**
1315 * die_get_var_range - Get byte offset range of given variable DIE
1316 * @sp_die: a subprogram DIE
1317 * @vr_die: a variable DIE
1318 * @buf: a strbuf for type and variable name and byte offset range
1319 *
1320 * Get the byte offset range of @vr_die and stores it in @buf as
1321 * "@<function_name+[NN-NN,NN-NN]>".
1322 */
1323 int die_get_var_range(Dwarf_Die *sp_die, Dwarf_Die *vr_die, struct strbuf *buf)
1324 {
1325 int ret = 0;
1326 Dwarf_Addr base;
1327 Dwarf_Addr start, end;
1328 Dwarf_Addr entry;
1329 Dwarf_Op *op;
1330 size_t nops;
1331 size_t offset = 0;
1332 Dwarf_Attribute attr;
1333 bool first = true;
1334 const char *name;
1335
1336 ret = die_entrypc(sp_die, &entry);
1337 if (ret)
1338 return ret;
1339
1340 name = dwarf_diename(sp_die);
1341 if (!name)
1342 return -ENOENT;
1343
1344 if (dwarf_attr(vr_die, DW_AT_location, &attr) == NULL)
1345 return -EINVAL;
1346
1347 while ((offset = dwarf_getlocations(&attr, offset, &base,
1348 &start, &end, &op, &nops)) > 0) {
1349 if (start == 0) {
1350 /* Single Location Descriptions */
1351 ret = die_get_var_innermost_scope(sp_die, vr_die, buf);
1352 goto out;
1353 }
1354
1355 /* Location Lists */
1356 start -= entry;
1357 end -= entry;
1358 if (first) {
1359 ret = strbuf_addf(buf, "@<%s+[%" PRIu64 "-%" PRIu64,
1360 name, start, end);
1361 first = false;
1362 } else {
1363 ret = strbuf_addf(buf, ",%" PRIu64 "-%" PRIu64,
1364 start, end);
1365 }
1366 if (ret < 0)
1367 goto out;
1368 }
1369
1370 if (!first)
1371 ret = strbuf_add(buf, "]>", 2);
1372 out:
1373 return ret;
1374 }
1375
1376 /* Interval parameters for __die_find_var_reg_cb() */
1377 struct find_var_data {
1378 /* Target instruction address */
1379 Dwarf_Addr pc;
1380 /* Target memory address (for global data) */
1381 Dwarf_Addr addr;
1382 /* Target register */
1383 unsigned reg;
1384 /* Access offset, set for global data */
1385 int offset;
1386 /* True if the current register is the frame base */
1387 bool is_fbreg;
1388 };
1389
1390 /* Max number of registers DW_OP_regN supports */
1391 #define DWARF_OP_DIRECT_REGS 32
1392
1393 static bool match_var_offset(Dwarf_Die *die_mem, struct find_var_data *data,
1394 u64 addr_offset, u64 addr_type, bool is_pointer)
1395 {
1396 Dwarf_Die type_die;
1397 Dwarf_Word size;
1398
1399 if (addr_offset == addr_type) {
1400 /* Update offset relative to the start of the variable */
1401 data->offset = 0;
1402 return true;
1403 }
1404
1405 if (addr_offset < addr_type)
1406 return false;
1407
1408 if (die_get_real_type(die_mem, &type_die) == NULL)
1409 return false;
1410
1411 if (is_pointer && dwarf_tag(&type_die) == DW_TAG_pointer_type) {
1412 /* Get the target type of the pointer */
1413 if (die_get_real_type(&type_die, &type_die) == NULL)
1414 return false;
1415 }
1416
1417 if (dwarf_aggregate_size(&type_die, &size) < 0)
1418 return false;
1419
1420 if (addr_offset >= addr_type + size)
1421 return false;
1422
1423 /* Update offset relative to the start of the variable */
1424 data->offset = addr_offset - addr_type;
1425 return true;
1426 }
1427
1428 /* Only checks direct child DIEs in the given scope. */
1429 static int __die_find_var_reg_cb(Dwarf_Die *die_mem, void *arg)
1430 {
1431 struct find_var_data *data = arg;
1432 int tag = dwarf_tag(die_mem);
1433 ptrdiff_t off = 0;
1434 Dwarf_Attribute attr;
1435 Dwarf_Addr base, start, end;
1436 Dwarf_Op *ops;
1437 size_t nops;
1438
1439 if (tag != DW_TAG_variable && tag != DW_TAG_formal_parameter)
1440 return DIE_FIND_CB_SIBLING;
1441
1442 if (dwarf_attr(die_mem, DW_AT_location, &attr) == NULL)
1443 return DIE_FIND_CB_SIBLING;
1444
1445 while ((off = dwarf_getlocations(&attr, off, &base, &start, &end, &ops, &nops)) > 0) {
1446 /* Assuming the location list is sorted by address */
1447 if (end <= data->pc)
1448 continue;
1449 if (start > data->pc)
1450 break;
1451
1452 /* Local variables accessed using frame base register */
1453 if (data->is_fbreg && ops->atom == DW_OP_fbreg &&
1454 check_allowed_ops(ops, nops) &&
1455 match_var_offset(die_mem, data, data->offset, ops->number,
1456 /*is_pointer=*/false))
1457 return DIE_FIND_CB_END;
1458
1459 /* Only match with a simple case */
1460 if (data->reg < DWARF_OP_DIRECT_REGS) {
1461 /* pointer variables saved in a register 0 to 31 */
1462 if (ops->atom == (DW_OP_reg0 + data->reg) &&
1463 check_allowed_ops(ops, nops) &&
1464 match_var_offset(die_mem, data, data->offset, 0,
1465 /*is_pointer=*/true))
1466 return DIE_FIND_CB_END;
1467
1468 /* Local variables accessed by a register + offset */
1469 if (ops->atom == (DW_OP_breg0 + data->reg) &&
1470 check_allowed_ops(ops, nops) &&
1471 match_var_offset(die_mem, data, data->offset, ops->number,
1472 /*is_pointer=*/false))
1473 return DIE_FIND_CB_END;
1474 } else {
1475 /* pointer variables saved in a register 32 or above */
1476 if (ops->atom == DW_OP_regx && ops->number == data->reg &&
1477 check_allowed_ops(ops, nops) &&
1478 match_var_offset(die_mem, data, data->offset, 0,
1479 /*is_pointer=*/true))
1480 return DIE_FIND_CB_END;
1481
1482 /* Local variables accessed by a register + offset */
1483 if (ops->atom == DW_OP_bregx && data->reg == ops->number &&
1484 check_allowed_ops(ops, nops) &&
1485 match_var_offset(die_mem, data, data->offset, ops->number2,
1486 /*is_poitner=*/false))
1487 return DIE_FIND_CB_END;
1488 }
1489 }
1490 return DIE_FIND_CB_SIBLING;
1491 }
1492
1493 /**
1494 * die_find_variable_by_reg - Find a variable saved in a register
1495 * @sc_die: a scope DIE
1496 * @pc: the program address to find
1497 * @reg: the register number to find
1498 * @poffset: pointer to offset, will be updated for fbreg case
1499 * @is_fbreg: boolean value if the current register is the frame base
1500 * @die_mem: a buffer to save the resulting DIE
1501 *
1502 * Find the variable DIE accessed by the given register. It'll update the @offset
1503 * when the variable is in the stack.
1504 */
1505 Dwarf_Die *die_find_variable_by_reg(Dwarf_Die *sc_die, Dwarf_Addr pc, int reg,
1506 int *poffset, bool is_fbreg,
1507 Dwarf_Die *die_mem)
1508 {
1509 struct find_var_data data = {
1510 .pc = pc,
1511 .reg = reg,
1512 .offset = *poffset,
1513 .is_fbreg = is_fbreg,
1514 };
1515 Dwarf_Die *result;
1516
1517 result = die_find_child(sc_die, __die_find_var_reg_cb, &data, die_mem);
1518 if (result)
1519 *poffset = data.offset;
1520 return result;
1521 }
1522
1523 /* Only checks direct child DIEs in the given scope */
1524 static int __die_find_var_addr_cb(Dwarf_Die *die_mem, void *arg)
1525 {
1526 struct find_var_data *data = arg;
1527 int tag = dwarf_tag(die_mem);
1528 ptrdiff_t off = 0;
1529 Dwarf_Attribute attr;
1530 Dwarf_Addr base, start, end;
1531 Dwarf_Op *ops;
1532 size_t nops;
1533
1534 if (tag != DW_TAG_variable)
1535 return DIE_FIND_CB_SIBLING;
1536
1537 if (dwarf_attr(die_mem, DW_AT_location, &attr) == NULL)
1538 return DIE_FIND_CB_SIBLING;
1539
1540 while ((off = dwarf_getlocations(&attr, off, &base, &start, &end, &ops, &nops)) > 0) {
1541 if (ops->atom != DW_OP_addr)
1542 continue;
1543
1544 if (check_allowed_ops(ops, nops) &&
1545 match_var_offset(die_mem, data, data->addr, ops->number,
1546 /*is_pointer=*/false))
1547 return DIE_FIND_CB_END;
1548 }
1549 return DIE_FIND_CB_SIBLING;
1550 }
1551
1552 /**
1553 * die_find_variable_by_addr - Find variable located at given address
1554 * @sc_die: a scope DIE
1555 * @addr: the data address to find
1556 * @die_mem: a buffer to save the resulting DIE
1557 * @offset: the offset in the resulting type
1558 *
1559 * Find the variable DIE located at the given address (in PC-relative mode).
1560 * This is usually for global variables.
1561 */
1562 Dwarf_Die *die_find_variable_by_addr(Dwarf_Die *sc_die, Dwarf_Addr addr,
1563 Dwarf_Die *die_mem, int *offset)
1564 {
1565 struct find_var_data data = {
1566 .addr = addr,
1567 };
1568 Dwarf_Die *result;
1569
1570 result = die_find_child(sc_die, __die_find_var_addr_cb, &data, die_mem);
1571 if (result)
1572 *offset = data.offset;
1573 return result;
1574 }
1575
1576 static int __die_collect_vars_cb(Dwarf_Die *die_mem, void *arg)
1577 {
1578 struct die_var_type **var_types = arg;
1579 Dwarf_Die type_die;
1580 int tag = dwarf_tag(die_mem);
1581 Dwarf_Attribute attr;
1582 Dwarf_Addr base, start, end;
1583 Dwarf_Op *ops;
1584 size_t nops;
1585 struct die_var_type *vt;
1586
1587 if (tag != DW_TAG_variable && tag != DW_TAG_formal_parameter)
1588 return DIE_FIND_CB_SIBLING;
1589
1590 if (dwarf_attr(die_mem, DW_AT_location, &attr) == NULL)
1591 return DIE_FIND_CB_SIBLING;
1592
1593 /*
1594 * Only collect the first location as it can reconstruct the
1595 * remaining state by following the instructions.
1596 * start = 0 means it covers the whole range.
1597 */
1598 if (dwarf_getlocations(&attr, 0, &base, &start, &end, &ops, &nops) <= 0)
1599 return DIE_FIND_CB_SIBLING;
1600
1601 if (!check_allowed_ops(ops, nops))
1602 return DIE_FIND_CB_SIBLING;
1603
1604 if (die_get_real_type(die_mem, &type_die) == NULL)
1605 return DIE_FIND_CB_SIBLING;
1606
1607 vt = malloc(sizeof(*vt));
1608 if (vt == NULL)
1609 return DIE_FIND_CB_END;
1610
1611 vt->die_off = dwarf_dieoffset(&type_die);
1612 vt->addr = start;
1613 vt->reg = reg_from_dwarf_op(ops);
1614 vt->offset = offset_from_dwarf_op(ops);
1615 vt->next = *var_types;
1616 *var_types = vt;
1617
1618 return DIE_FIND_CB_SIBLING;
1619 }
1620
1621 /**
1622 * die_collect_vars - Save all variables and parameters
1623 * @sc_die: a scope DIE
1624 * @var_types: a pointer to save the resulting list
1625 *
1626 * Save all variables and parameters in the @sc_die and save them to @var_types.
1627 * The @var_types is a singly-linked list containing type and location info.
1628 * Actual type can be retrieved using dwarf_offdie() with 'die_off' later.
1629 *
1630 * Callers should free @var_types.
1631 */
1632 void die_collect_vars(Dwarf_Die *sc_die, struct die_var_type **var_types)
1633 {
1634 Dwarf_Die die_mem;
1635
1636 die_find_child(sc_die, __die_collect_vars_cb, (void *)var_types, &die_mem);
1637 }
1638
1639 static int __die_collect_global_vars_cb(Dwarf_Die *die_mem, void *arg)
1640 {
1641 struct die_var_type **var_types = arg;
1642 Dwarf_Die type_die;
1643 int tag = dwarf_tag(die_mem);
1644 Dwarf_Attribute attr;
1645 Dwarf_Addr base, start, end;
1646 Dwarf_Op *ops;
1647 size_t nops;
1648 struct die_var_type *vt;
1649
1650 if (tag != DW_TAG_variable)
1651 return DIE_FIND_CB_SIBLING;
1652
1653 if (dwarf_attr(die_mem, DW_AT_location, &attr) == NULL)
1654 return DIE_FIND_CB_SIBLING;
1655
1656 /* Only collect the location with an absolute address. */
1657 if (dwarf_getlocations(&attr, 0, &base, &start, &end, &ops, &nops) <= 0)
1658 return DIE_FIND_CB_SIBLING;
1659
1660 if (ops->atom != DW_OP_addr)
1661 return DIE_FIND_CB_SIBLING;
1662
1663 if (!check_allowed_ops(ops, nops))
1664 return DIE_FIND_CB_SIBLING;
1665
1666 if (die_get_real_type(die_mem, &type_die) == NULL)
1667 return DIE_FIND_CB_SIBLING;
1668
1669 vt = malloc(sizeof(*vt));
1670 if (vt == NULL)
1671 return DIE_FIND_CB_END;
1672
1673 vt->die_off = dwarf_dieoffset(&type_die);
1674 vt->addr = ops->number;
1675 vt->reg = -1;
1676 vt->offset = 0;
1677 vt->next = *var_types;
1678 *var_types = vt;
1679
1680 return DIE_FIND_CB_SIBLING;
1681 }
1682
1683 /**
1684 * die_collect_global_vars - Save all global variables
1685 * @cu_die: a CU DIE
1686 * @var_types: a pointer to save the resulting list
1687 *
1688 * Save all global variables in the @cu_die and save them to @var_types.
1689 * The @var_types is a singly-linked list containing type and location info.
1690 * Actual type can be retrieved using dwarf_offdie() with 'die_off' later.
1691 *
1692 * Callers should free @var_types.
1693 */
1694 void die_collect_global_vars(Dwarf_Die *cu_die, struct die_var_type **var_types)
1695 {
1696 Dwarf_Die die_mem;
1697
1698 die_find_child(cu_die, __die_collect_global_vars_cb, (void *)var_types, &die_mem);
1699 }
1700 #endif /* HAVE_DWARF_GETLOCATIONS_SUPPORT */
1701
1702 #ifdef HAVE_DWARF_CFI_SUPPORT
1703 /**
1704 * die_get_cfa - Get frame base information
1705 * @dwarf: a Dwarf info
1706 * @pc: program address
1707 * @preg: pointer for saved register
1708 * @poffset: pointer for saved offset
1709 *
1710 * This function gets register and offset for CFA (Canonical Frame Address)
1711 * by searching the CIE/FDE info. The CFA usually points to the start address
1712 * of the current stack frame and local variables can be located using an offset
1713 * from the CFA. The @preg and @poffset will be updated if it returns 0.
1714 */
1715 int die_get_cfa(Dwarf *dwarf, u64 pc, int *preg, int *poffset)
1716 {
1717 Dwarf_CFI *cfi;
1718 Dwarf_Frame *frame = NULL;
1719 Dwarf_Op *ops = NULL;
1720 size_t nops;
1721
1722 cfi = dwarf_getcfi(dwarf);
1723 if (cfi == NULL)
1724 return -1;
1725
1726 if (!dwarf_cfi_addrframe(cfi, pc, &frame) &&
1727 !dwarf_frame_cfa(frame, &ops, &nops) &&
1728 check_allowed_ops(ops, nops)) {
1729 *preg = reg_from_dwarf_op(ops);
1730 *poffset = offset_from_dwarf_op(ops);
1731 return 0;
1732 }
1733 return -1;
1734 }
1735 #endif /* HAVE_DWARF_CFI_SUPPORT */
1736
1737 /*
1738 * die_has_loclist - Check if DW_AT_location of @vr_die is a location list
1739 * @vr_die: a variable DIE
1740 */
1741 static bool die_has_loclist(Dwarf_Die *vr_die)
1742 {
1743 Dwarf_Attribute loc;
1744 int tag = dwarf_tag(vr_die);
1745
1746 if (tag != DW_TAG_formal_parameter &&
1747 tag != DW_TAG_variable)
1748 return false;
1749
1750 return (dwarf_attr_integrate(vr_die, DW_AT_location, &loc) &&
1751 dwarf_whatform(&loc) == DW_FORM_sec_offset);
1752 }
1753
1754 /*
1755 * die_is_optimized_target - Check if target program is compiled with
1756 * optimization
1757 * @cu_die: a CU DIE
1758 *
1759 * For any object in given CU whose DW_AT_location is a location list,
1760 * target program is compiled with optimization. This is applicable to
1761 * clang as well.
1762 */
1763 bool die_is_optimized_target(Dwarf_Die *cu_die)
1764 {
1765 Dwarf_Die tmp_die;
1766
1767 if (die_has_loclist(cu_die))
1768 return true;
1769
1770 if (!dwarf_child(cu_die, &tmp_die) &&
1771 die_is_optimized_target(&tmp_die))
1772 return true;
1773
1774 if (!dwarf_siblingof(cu_die, &tmp_die) &&
1775 die_is_optimized_target(&tmp_die))
1776 return true;
1777
1778 return false;
1779 }
1780
1781 /*
1782 * die_search_idx - Search index of given line address
1783 * @lines: Line records of single CU
1784 * @nr_lines: Number of @lines
1785 * @addr: address we are looking for
1786 * @idx: index to be set by this function (return value)
1787 *
1788 * Search for @addr by looping over every lines of CU. If address
1789 * matches, set index of that line in @idx. Note that single source
1790 * line can have multiple line records. i.e. single source line can
1791 * have multiple index.
1792 */
1793 static bool die_search_idx(Dwarf_Lines *lines, unsigned long nr_lines,
1794 Dwarf_Addr addr, unsigned long *idx)
1795 {
1796 unsigned long i;
1797 Dwarf_Addr tmp;
1798
1799 for (i = 0; i < nr_lines; i++) {
1800 if (dwarf_lineaddr(dwarf_onesrcline(lines, i), &tmp))
1801 return false;
1802
1803 if (tmp == addr) {
1804 *idx = i;
1805 return true;
1806 }
1807 }
1808 return false;
1809 }
1810
1811 /*
1812 * die_get_postprologue_addr - Search next address after function prologue
1813 * @entrypc_idx: entrypc index
1814 * @lines: Line records of single CU
1815 * @nr_lines: Number of @lines
1816 * @hignpc: high PC address of function
1817 * @postprologue_addr: Next address after function prologue (return value)
1818 *
1819 * Look for prologue-end marker. If there is no explicit marker, return
1820 * address of next line record or next source line.
1821 */
1822 static bool die_get_postprologue_addr(unsigned long entrypc_idx,
1823 Dwarf_Lines *lines,
1824 unsigned long nr_lines,
1825 Dwarf_Addr highpc,
1826 Dwarf_Addr *postprologue_addr)
1827 {
1828 unsigned long i;
1829 int entrypc_lno, lno;
1830 Dwarf_Line *line;
1831 Dwarf_Addr addr;
1832 bool p_end;
1833
1834 /* entrypc_lno is actual source line number */
1835 line = dwarf_onesrcline(lines, entrypc_idx);
1836 if (dwarf_lineno(line, &entrypc_lno))
1837 return false;
1838
1839 for (i = entrypc_idx; i < nr_lines; i++) {
1840 line = dwarf_onesrcline(lines, i);
1841
1842 if (dwarf_lineaddr(line, &addr) ||
1843 dwarf_lineno(line, &lno) ||
1844 dwarf_lineprologueend(line, &p_end))
1845 return false;
1846
1847 /* highpc is exclusive. [entrypc,highpc) */
1848 if (addr >= highpc)
1849 break;
1850
1851 /* clang supports prologue-end marker */
1852 if (p_end)
1853 break;
1854
1855 /* Actual next line in source */
1856 if (lno != entrypc_lno)
1857 break;
1858
1859 /*
1860 * Single source line can have multiple line records.
1861 * For Example,
1862 * void foo() { printf("hello\n"); }
1863 * contains two line records. One points to declaration and
1864 * other points to printf() line. Variable 'lno' won't get
1865 * incremented in this case but 'i' will.
1866 */
1867 if (i != entrypc_idx)
1868 break;
1869 }
1870
1871 dwarf_lineaddr(line, postprologue_addr);
1872 if (*postprologue_addr >= highpc)
1873 dwarf_lineaddr(dwarf_onesrcline(lines, i - 1),
1874 postprologue_addr);
1875
1876 return true;
1877 }
1878
1879 /*
1880 * die_skip_prologue - Use next address after prologue as probe location
1881 * @sp_die: a subprogram DIE
1882 * @cu_die: a CU DIE
1883 * @entrypc: entrypc of the function
1884 *
1885 * Function prologue prepares stack and registers before executing function
1886 * logic. When target program is compiled without optimization, function
1887 * parameter information is only valid after prologue. When we probe entrypc
1888 * of the function, and try to record function parameter, it contains
1889 * garbage value.
1890 */
1891 void die_skip_prologue(Dwarf_Die *sp_die, Dwarf_Die *cu_die,
1892 Dwarf_Addr *entrypc)
1893 {
1894 size_t nr_lines = 0;
1895 unsigned long entrypc_idx = 0;
1896 Dwarf_Lines *lines = NULL;
1897 Dwarf_Addr postprologue_addr;
1898 Dwarf_Addr highpc;
1899
1900 if (dwarf_highpc(sp_die, &highpc))
1901 return;
1902
1903 if (dwarf_getsrclines(cu_die, &lines, &nr_lines))
1904 return;
1905
1906 if (!die_search_idx(lines, nr_lines, *entrypc, &entrypc_idx))
1907 return;
1908
1909 if (!die_get_postprologue_addr(entrypc_idx, lines, nr_lines,
1910 highpc, &postprologue_addr))
1911 return;
1912
1913 *entrypc = postprologue_addr;
1914 }
1915
1916 /* Internal parameters for __die_find_scope_cb() */
1917 struct find_scope_data {
1918 /* Target instruction address */
1919 Dwarf_Addr pc;
1920 /* Number of scopes found [output] */
1921 int nr;
1922 /* Array of scopes found, 0 for the outermost one. [output] */
1923 Dwarf_Die *scopes;
1924 };
1925
1926 static int __die_find_scope_cb(Dwarf_Die *die_mem, void *arg)
1927 {
1928 struct find_scope_data *data = arg;
1929
1930 if (dwarf_haspc(die_mem, data->pc)) {
1931 Dwarf_Die *tmp;
1932
1933 tmp = realloc(data->scopes, (data->nr + 1) * sizeof(*tmp));
1934 if (tmp == NULL)
1935 return DIE_FIND_CB_END;
1936
1937 memcpy(tmp + data->nr, die_mem, sizeof(*die_mem));
1938 data->scopes = tmp;
1939 data->nr++;
1940 return DIE_FIND_CB_CHILD;
1941 }
1942 return DIE_FIND_CB_SIBLING;
1943 }
1944
1945 /**
1946 * die_get_scopes - Return a list of scopes including the address
1947 * @cu_die: a compile unit DIE
1948 * @pc: the address to find
1949 * @scopes: the array of DIEs for scopes (result)
1950 *
1951 * This function does the same as the dwarf_getscopes() but doesn't follow
1952 * the origins of inlined functions. It returns the number of scopes saved
1953 * in the @scopes argument. The outer scope will be saved first (index 0) and
1954 * the last one is the innermost scope at the @pc.
1955 */
1956 int die_get_scopes(Dwarf_Die *cu_die, Dwarf_Addr pc, Dwarf_Die **scopes)
1957 {
1958 struct find_scope_data data = {
1959 .pc = pc,
1960 };
1961 Dwarf_Die die_mem;
1962
1963 die_find_child(cu_die, __die_find_scope_cb, &data, &die_mem);
1964
1965 *scopes = data.scopes;
1966 return data.nr;
1967 }
1968
1969 static int __die_find_member_offset_cb(Dwarf_Die *die_mem, void *arg)
1970 {
1971 Dwarf_Die type_die;
1972 Dwarf_Word size, loc;
1973 Dwarf_Word offset = (long)arg;
1974 int tag = dwarf_tag(die_mem);
1975
1976 if (tag != DW_TAG_member)
1977 return DIE_FIND_CB_SIBLING;
1978
1979 /* Unions might not have location */
1980 if (die_get_data_member_location(die_mem, &loc) < 0) {
1981 Dwarf_Attribute attr;
1982
1983 if (dwarf_attr_integrate(die_mem, DW_AT_data_bit_offset, &attr) &&
1984 dwarf_formudata(&attr, &loc) == 0)
1985 loc /= 8;
1986 else
1987 loc = 0;
1988 }
1989
1990 if (offset == loc)
1991 return DIE_FIND_CB_END;
1992
1993 if (die_get_real_type(die_mem, &type_die) == NULL) {
1994 // TODO: add a pr_debug_dtp() later for this unlikely failure
1995 return DIE_FIND_CB_SIBLING;
1996 }
1997
1998 if (dwarf_aggregate_size(&type_die, &size) < 0)
1999 size = 0;
2000
2001 if (loc < offset && offset < (loc + size))
2002 return DIE_FIND_CB_END;
2003
2004 return DIE_FIND_CB_SIBLING;
2005 }
2006
2007 /**
2008 * die_get_member_type - Return type info of struct member
2009 * @type_die: a type DIE
2010 * @offset: offset in the type
2011 * @die_mem: a buffer to save the resulting DIE
2012 *
2013 * This function returns a type of a member in @type_die where it's located at
2014 * @offset if it's a struct. For now, it just returns the first matching
2015 * member in a union. For other types, it'd return the given type directly
2016 * if it's within the size of the type or NULL otherwise.
2017 */
2018 Dwarf_Die *die_get_member_type(Dwarf_Die *type_die, int offset,
2019 Dwarf_Die *die_mem)
2020 {
2021 Dwarf_Die *member;
2022 Dwarf_Die mb_type;
2023 int tag;
2024
2025 tag = dwarf_tag(type_die);
2026 /* If it's not a compound type, return the type directly */
2027 if (tag != DW_TAG_structure_type && tag != DW_TAG_union_type) {
2028 Dwarf_Word size;
2029
2030 if (dwarf_aggregate_size(type_die, &size) < 0)
2031 size = 0;
2032
2033 if ((unsigned)offset >= size)
2034 return NULL;
2035
2036 *die_mem = *type_die;
2037 return die_mem;
2038 }
2039
2040 mb_type = *type_die;
2041 /* TODO: Handle union types better? */
2042 while (tag == DW_TAG_structure_type || tag == DW_TAG_union_type) {
2043 member = die_find_child(&mb_type, __die_find_member_offset_cb,
2044 (void *)(long)offset, die_mem);
2045 if (member == NULL)
2046 return NULL;
2047
2048 if (die_get_real_type(member, &mb_type) == NULL)
2049 return NULL;
2050
2051 tag = dwarf_tag(&mb_type);
2052
2053 if (tag == DW_TAG_structure_type || tag == DW_TAG_union_type) {
2054 Dwarf_Word loc;
2055
2056 /* Update offset for the start of the member struct */
2057 if (die_get_data_member_location(member, &loc) == 0)
2058 offset -= loc;
2059 }
2060 }
2061 *die_mem = mb_type;
2062 return die_mem;
2063 }
2064
2065 /**
2066 * die_deref_ptr_type - Return type info for pointer access
2067 * @ptr_die: a pointer type DIE
2068 * @offset: access offset for the pointer
2069 * @die_mem: a buffer to save the resulting DIE
2070 *
2071 * This function follows the pointer in @ptr_die with given @offset
2072 * and saves the resulting type in @die_mem. If the pointer points
2073 * a struct type, actual member at the offset would be returned.
2074 */
2075 Dwarf_Die *die_deref_ptr_type(Dwarf_Die *ptr_die, int offset,
2076 Dwarf_Die *die_mem)
2077 {
2078 Dwarf_Die type_die;
2079
2080 if (dwarf_tag(ptr_die) != DW_TAG_pointer_type)
2081 return NULL;
2082
2083 if (die_get_real_type(ptr_die, &type_die) == NULL)
2084 return NULL;
2085
2086 return die_get_member_type(&type_die, offset, die_mem);
2087 }
2088
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