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 "strbuf.h"
13 #include "string2.h"
14
15 /**
16 * cu_find_realpath - Find the realpath of the target file
17 * @cu_die: A DIE(dwarf information entry) of CU(compilation Unit)
18 * @fname: The tail filename of the target file
19 *
20 * Find the real(long) path of @fname in @cu_die.
21 */
cu_find_realpath(Dwarf_Die * cu_die,const char * fname)22 const char *cu_find_realpath(Dwarf_Die *cu_die, const char *fname)
23 {
24 Dwarf_Files *files;
25 size_t nfiles, i;
26 const char *src = NULL;
27 int ret;
28
29 if (!fname)
30 return NULL;
31
32 ret = dwarf_getsrcfiles(cu_die, &files, &nfiles);
33 if (ret != 0)
34 return NULL;
35
36 for (i = 0; i < nfiles; i++) {
37 src = dwarf_filesrc(files, i, NULL, NULL);
38 if (strtailcmp(src, fname) == 0)
39 break;
40 }
41 if (i == nfiles)
42 return NULL;
43 return src;
44 }
45
46 /**
47 * cu_get_comp_dir - Get the path of compilation directory
48 * @cu_die: a CU DIE
49 *
50 * Get the path of compilation directory of given @cu_die.
51 * Since this depends on DW_AT_comp_dir, older gcc will not
52 * embedded it. In that case, this returns NULL.
53 */
cu_get_comp_dir(Dwarf_Die * cu_die)54 const char *cu_get_comp_dir(Dwarf_Die *cu_die)
55 {
56 Dwarf_Attribute attr;
57 if (dwarf_attr(cu_die, DW_AT_comp_dir, &attr) == NULL)
58 return NULL;
59 return dwarf_formstring(&attr);
60 }
61
62 /* Unlike dwarf_getsrc_die(), cu_getsrc_die() only returns statement line */
cu_getsrc_die(Dwarf_Die * cu_die,Dwarf_Addr addr)63 static Dwarf_Line *cu_getsrc_die(Dwarf_Die *cu_die, Dwarf_Addr addr)
64 {
65 Dwarf_Addr laddr;
66 Dwarf_Lines *lines;
67 Dwarf_Line *line;
68 size_t nlines, l, u, n;
69 bool flag;
70
71 if (dwarf_getsrclines(cu_die, &lines, &nlines) != 0 ||
72 nlines == 0)
73 return NULL;
74
75 /* Lines are sorted by address, use binary search */
76 l = 0; u = nlines - 1;
77 while (l < u) {
78 n = u - (u - l) / 2;
79 line = dwarf_onesrcline(lines, n);
80 if (!line || dwarf_lineaddr(line, &laddr) != 0)
81 return NULL;
82 if (addr < laddr)
83 u = n - 1;
84 else
85 l = n;
86 }
87 /* Going backward to find the lowest line */
88 do {
89 line = dwarf_onesrcline(lines, --l);
90 if (!line || dwarf_lineaddr(line, &laddr) != 0)
91 return NULL;
92 } while (laddr == addr);
93 l++;
94 /* Going foward to find the statement line */
95 do {
96 line = dwarf_onesrcline(lines, l++);
97 if (!line || dwarf_lineaddr(line, &laddr) != 0 ||
98 dwarf_linebeginstatement(line, &flag) != 0)
99 return NULL;
100 if (laddr > addr)
101 return NULL;
102 } while (!flag);
103
104 return line;
105 }
106
107 /**
108 * cu_find_lineinfo - Get a line number and file name for given address
109 * @cu_die: a CU DIE
110 * @addr: An address
111 * @fname: a pointer which returns the file name string
112 * @lineno: a pointer which returns the line number
113 *
114 * Find a line number and file name for @addr in @cu_die.
115 */
cu_find_lineinfo(Dwarf_Die * cu_die,unsigned long addr,const char ** fname,int * lineno)116 int cu_find_lineinfo(Dwarf_Die *cu_die, unsigned long addr,
117 const char **fname, int *lineno)
118 {
119 Dwarf_Line *line;
120 Dwarf_Die die_mem;
121 Dwarf_Addr faddr;
122
123 if (die_find_realfunc(cu_die, (Dwarf_Addr)addr, &die_mem)
124 && die_entrypc(&die_mem, &faddr) == 0 &&
125 faddr == addr) {
126 *fname = dwarf_decl_file(&die_mem);
127 dwarf_decl_line(&die_mem, lineno);
128 goto out;
129 }
130
131 line = cu_getsrc_die(cu_die, (Dwarf_Addr)addr);
132 if (line && dwarf_lineno(line, lineno) == 0) {
133 *fname = dwarf_linesrc(line, NULL, NULL);
134 if (!*fname)
135 /* line number is useless without filename */
136 *lineno = 0;
137 }
138
139 out:
140 return *lineno ?: -ENOENT;
141 }
142
143 static int __die_find_inline_cb(Dwarf_Die *die_mem, void *data);
144
145 /**
146 * cu_walk_functions_at - Walk on function DIEs at given address
147 * @cu_die: A CU DIE
148 * @addr: An address
149 * @callback: A callback which called with found DIEs
150 * @data: A user data
151 *
152 * Walk on function DIEs at given @addr in @cu_die. Passed DIEs
153 * should be subprogram or inlined-subroutines.
154 */
cu_walk_functions_at(Dwarf_Die * cu_die,Dwarf_Addr addr,int (* callback)(Dwarf_Die *,void *),void * data)155 int cu_walk_functions_at(Dwarf_Die *cu_die, Dwarf_Addr addr,
156 int (*callback)(Dwarf_Die *, void *), void *data)
157 {
158 Dwarf_Die die_mem;
159 Dwarf_Die *sc_die;
160 int ret = -ENOENT;
161
162 /* Inlined function could be recursive. Trace it until fail */
163 for (sc_die = die_find_realfunc(cu_die, addr, &die_mem);
164 sc_die != NULL;
165 sc_die = die_find_child(sc_die, __die_find_inline_cb, &addr,
166 &die_mem)) {
167 ret = callback(sc_die, data);
168 if (ret)
169 break;
170 }
171
172 return ret;
173
174 }
175
176 /**
177 * die_get_linkage_name - Get the linkage name of the object
178 * @dw_die: A DIE of the object
179 *
180 * Get the linkage name attiribute of given @dw_die.
181 * For C++ binary, the linkage name will be the mangled symbol.
182 */
die_get_linkage_name(Dwarf_Die * dw_die)183 const char *die_get_linkage_name(Dwarf_Die *dw_die)
184 {
185 Dwarf_Attribute attr;
186
187 if (dwarf_attr_integrate(dw_die, DW_AT_linkage_name, &attr) == NULL)
188 return NULL;
189 return dwarf_formstring(&attr);
190 }
191
192 /**
193 * die_compare_name - Compare diename and tname
194 * @dw_die: a DIE
195 * @tname: a string of target name
196 *
197 * Compare the name of @dw_die and @tname. Return false if @dw_die has no name.
198 */
die_compare_name(Dwarf_Die * dw_die,const char * tname)199 bool die_compare_name(Dwarf_Die *dw_die, const char *tname)
200 {
201 const char *name;
202
203 name = dwarf_diename(dw_die);
204 return name ? (strcmp(tname, name) == 0) : false;
205 }
206
207 /**
208 * die_match_name - Match diename/linkage name and glob
209 * @dw_die: a DIE
210 * @glob: a string of target glob pattern
211 *
212 * Glob matching the name of @dw_die and @glob. Return false if matching fail.
213 * This also match linkage name.
214 */
die_match_name(Dwarf_Die * dw_die,const char * glob)215 bool die_match_name(Dwarf_Die *dw_die, const char *glob)
216 {
217 const char *name;
218
219 name = dwarf_diename(dw_die);
220 if (name && strglobmatch(name, glob))
221 return true;
222 /* fall back to check linkage name */
223 name = die_get_linkage_name(dw_die);
224 if (name && strglobmatch(name, glob))
225 return true;
226
227 return false;
228 }
229
230 /**
231 * die_get_call_lineno - Get callsite line number of inline-function instance
232 * @in_die: a DIE of an inlined function instance
233 *
234 * Get call-site line number of @in_die. This means from where the inline
235 * function is called.
236 */
die_get_call_lineno(Dwarf_Die * in_die)237 int die_get_call_lineno(Dwarf_Die *in_die)
238 {
239 Dwarf_Attribute attr;
240 Dwarf_Word ret;
241
242 if (!dwarf_attr(in_die, DW_AT_call_line, &attr))
243 return -ENOENT;
244
245 dwarf_formudata(&attr, &ret);
246 return (int)ret;
247 }
248
249 /**
250 * die_get_type - Get type DIE
251 * @vr_die: a DIE of a variable
252 * @die_mem: where to store a type DIE
253 *
254 * Get a DIE of the type of given variable (@vr_die), and store
255 * it to die_mem. Return NULL if fails to get a type DIE.
256 */
die_get_type(Dwarf_Die * vr_die,Dwarf_Die * die_mem)257 Dwarf_Die *die_get_type(Dwarf_Die *vr_die, Dwarf_Die *die_mem)
258 {
259 Dwarf_Attribute attr;
260
261 if (dwarf_attr_integrate(vr_die, DW_AT_type, &attr) &&
262 dwarf_formref_die(&attr, die_mem))
263 return die_mem;
264 else
265 return NULL;
266 }
267
268 /* Get a type die, but skip qualifiers */
__die_get_real_type(Dwarf_Die * vr_die,Dwarf_Die * die_mem)269 static Dwarf_Die *__die_get_real_type(Dwarf_Die *vr_die, Dwarf_Die *die_mem)
270 {
271 int tag;
272
273 do {
274 vr_die = die_get_type(vr_die, die_mem);
275 if (!vr_die)
276 break;
277 tag = dwarf_tag(vr_die);
278 } while (tag == DW_TAG_const_type ||
279 tag == DW_TAG_restrict_type ||
280 tag == DW_TAG_volatile_type ||
281 tag == DW_TAG_shared_type);
282
283 return vr_die;
284 }
285
286 /**
287 * die_get_real_type - Get a type die, but skip qualifiers and typedef
288 * @vr_die: a DIE of a variable
289 * @die_mem: where to store a type DIE
290 *
291 * Get a DIE of the type of given variable (@vr_die), and store
292 * it to die_mem. Return NULL if fails to get a type DIE.
293 * If the type is qualifiers (e.g. const) or typedef, this skips it
294 * and tries to find real type (structure or basic types, e.g. int).
295 */
die_get_real_type(Dwarf_Die * vr_die,Dwarf_Die * die_mem)296 Dwarf_Die *die_get_real_type(Dwarf_Die *vr_die, Dwarf_Die *die_mem)
297 {
298 do {
299 vr_die = __die_get_real_type(vr_die, die_mem);
300 } while (vr_die && dwarf_tag(vr_die) == DW_TAG_typedef);
301
302 return vr_die;
303 }
304
305 /* Get attribute and translate it as a udata */
die_get_attr_udata(Dwarf_Die * tp_die,unsigned int attr_name,Dwarf_Word * result)306 static int die_get_attr_udata(Dwarf_Die *tp_die, unsigned int attr_name,
307 Dwarf_Word *result)
308 {
309 Dwarf_Attribute attr;
310
311 if (dwarf_attr_integrate(tp_die, attr_name, &attr) == NULL ||
312 dwarf_formudata(&attr, result) != 0)
313 return -ENOENT;
314
315 return 0;
316 }
317
318 /**
319 * die_is_signed_type - Check whether a type DIE is signed or not
320 * @tp_die: a DIE of a type
321 *
322 * Get the encoding of @tp_die and return true if the encoding
323 * is signed.
324 */
die_is_signed_type(Dwarf_Die * tp_die)325 bool die_is_signed_type(Dwarf_Die *tp_die)
326 {
327 Dwarf_Word ret;
328
329 if (die_get_attr_udata(tp_die, DW_AT_encoding, &ret))
330 return false;
331
332 return (ret == DW_ATE_signed_char || ret == DW_ATE_signed ||
333 ret == DW_ATE_signed_fixed);
334 }
335
336 /**
337 * die_is_func_def - Ensure that this DIE is a subprogram and definition
338 * @dw_die: a DIE
339 *
340 * Ensure that this DIE is a subprogram and NOT a declaration. This
341 * returns true if @dw_die is a function definition.
342 **/
die_is_func_def(Dwarf_Die * dw_die)343 bool die_is_func_def(Dwarf_Die *dw_die)
344 {
345 Dwarf_Attribute attr;
346 Dwarf_Addr addr = 0;
347
348 if (dwarf_tag(dw_die) != DW_TAG_subprogram)
349 return false;
350
351 if (dwarf_attr(dw_die, DW_AT_declaration, &attr))
352 return false;
353
354 /*
355 * DW_AT_declaration can be lost from function declaration
356 * by gcc's bug #97060.
357 * So we need to check this subprogram DIE has DW_AT_inline
358 * or an entry address.
359 */
360 if (!dwarf_attr(dw_die, DW_AT_inline, &attr) &&
361 die_entrypc(dw_die, &addr) < 0)
362 return false;
363
364 return true;
365 }
366
367 /**
368 * die_entrypc - Returns entry PC (the lowest address) of a DIE
369 * @dw_die: a DIE
370 * @addr: where to store entry PC
371 *
372 * Since dwarf_entrypc() does not return entry PC if the DIE has only address
373 * range, we have to use this to retrieve the lowest address from the address
374 * range attribute.
375 */
die_entrypc(Dwarf_Die * dw_die,Dwarf_Addr * addr)376 int die_entrypc(Dwarf_Die *dw_die, Dwarf_Addr *addr)
377 {
378 Dwarf_Addr base, end;
379 Dwarf_Attribute attr;
380
381 if (!addr)
382 return -EINVAL;
383
384 if (dwarf_entrypc(dw_die, addr) == 0)
385 return 0;
386
387 /*
388 * Since the dwarf_ranges() will return 0 if there is no
389 * DW_AT_ranges attribute, we should check it first.
390 */
391 if (!dwarf_attr(dw_die, DW_AT_ranges, &attr))
392 return -ENOENT;
393
394 return dwarf_ranges(dw_die, 0, &base, addr, &end) < 0 ? -ENOENT : 0;
395 }
396
397 /**
398 * die_is_func_instance - Ensure that this DIE is an instance of a subprogram
399 * @dw_die: a DIE
400 *
401 * Ensure that this DIE is an instance (which has an entry address).
402 * This returns true if @dw_die is a function instance. If not, the @dw_die
403 * must be a prototype. You can use die_walk_instances() to find actual
404 * instances.
405 **/
die_is_func_instance(Dwarf_Die * dw_die)406 bool die_is_func_instance(Dwarf_Die *dw_die)
407 {
408 Dwarf_Addr tmp;
409 Dwarf_Attribute attr_mem;
410 int tag = dwarf_tag(dw_die);
411
412 if (tag != DW_TAG_subprogram &&
413 tag != DW_TAG_inlined_subroutine)
414 return false;
415
416 return dwarf_entrypc(dw_die, &tmp) == 0 ||
417 dwarf_attr(dw_die, DW_AT_ranges, &attr_mem) != NULL;
418 }
419
420 /**
421 * die_get_data_member_location - Get the data-member offset
422 * @mb_die: a DIE of a member of a data structure
423 * @offs: The offset of the member in the data structure
424 *
425 * Get the offset of @mb_die in the data structure including @mb_die, and
426 * stores result offset to @offs. If any error occurs this returns errno.
427 */
die_get_data_member_location(Dwarf_Die * mb_die,Dwarf_Word * offs)428 int die_get_data_member_location(Dwarf_Die *mb_die, Dwarf_Word *offs)
429 {
430 Dwarf_Attribute attr;
431 Dwarf_Op *expr;
432 size_t nexpr;
433 int ret;
434
435 if (dwarf_attr(mb_die, DW_AT_data_member_location, &attr) == NULL)
436 return -ENOENT;
437
438 if (dwarf_formudata(&attr, offs) != 0) {
439 /* DW_AT_data_member_location should be DW_OP_plus_uconst */
440 ret = dwarf_getlocation(&attr, &expr, &nexpr);
441 if (ret < 0 || nexpr == 0)
442 return -ENOENT;
443
444 if (expr[0].atom != DW_OP_plus_uconst || nexpr != 1) {
445 pr_debug("Unable to get offset:Unexpected OP %x (%zd)\n",
446 expr[0].atom, nexpr);
447 return -ENOTSUP;
448 }
449 *offs = (Dwarf_Word)expr[0].number;
450 }
451 return 0;
452 }
453
454 /* Get the call file index number in CU DIE */
die_get_call_fileno(Dwarf_Die * in_die)455 static int die_get_call_fileno(Dwarf_Die *in_die)
456 {
457 Dwarf_Word idx;
458
459 if (die_get_attr_udata(in_die, DW_AT_call_file, &idx) == 0)
460 return (int)idx;
461 else
462 return -ENOENT;
463 }
464
465 /* Get the declared file index number in CU DIE */
die_get_decl_fileno(Dwarf_Die * pdie)466 static int die_get_decl_fileno(Dwarf_Die *pdie)
467 {
468 Dwarf_Word idx;
469
470 if (die_get_attr_udata(pdie, DW_AT_decl_file, &idx) == 0)
471 return (int)idx;
472 else
473 return -ENOENT;
474 }
475
476 /**
477 * die_get_call_file - Get callsite file name of inlined function instance
478 * @in_die: a DIE of an inlined function instance
479 *
480 * Get call-site file name of @in_die. This means from which file the inline
481 * function is called.
482 */
die_get_call_file(Dwarf_Die * in_die)483 const char *die_get_call_file(Dwarf_Die *in_die)
484 {
485 Dwarf_Die cu_die;
486 Dwarf_Files *files;
487 int idx;
488
489 idx = die_get_call_fileno(in_die);
490 if (idx < 0 || !dwarf_diecu(in_die, &cu_die, NULL, NULL) ||
491 dwarf_getsrcfiles(&cu_die, &files, NULL) != 0)
492 return NULL;
493
494 return dwarf_filesrc(files, idx, NULL, NULL);
495 }
496
497
498 /**
499 * die_find_child - Generic DIE search function in DIE tree
500 * @rt_die: a root DIE
501 * @callback: a callback function
502 * @data: a user data passed to the callback function
503 * @die_mem: a buffer for result DIE
504 *
505 * Trace DIE tree from @rt_die and call @callback for each child DIE.
506 * If @callback returns DIE_FIND_CB_END, this stores the DIE into
507 * @die_mem and returns it. If @callback returns DIE_FIND_CB_CONTINUE,
508 * this continues to trace the tree. Optionally, @callback can return
509 * DIE_FIND_CB_CHILD and DIE_FIND_CB_SIBLING, those means trace only
510 * the children and trace only the siblings respectively.
511 * Returns NULL if @callback can't find any appropriate DIE.
512 */
die_find_child(Dwarf_Die * rt_die,int (* callback)(Dwarf_Die *,void *),void * data,Dwarf_Die * die_mem)513 Dwarf_Die *die_find_child(Dwarf_Die *rt_die,
514 int (*callback)(Dwarf_Die *, void *),
515 void *data, Dwarf_Die *die_mem)
516 {
517 Dwarf_Die child_die;
518 int ret;
519
520 ret = dwarf_child(rt_die, die_mem);
521 if (ret != 0)
522 return NULL;
523
524 do {
525 ret = callback(die_mem, data);
526 if (ret == DIE_FIND_CB_END)
527 return die_mem;
528
529 if ((ret & DIE_FIND_CB_CHILD) &&
530 die_find_child(die_mem, callback, data, &child_die)) {
531 memcpy(die_mem, &child_die, sizeof(Dwarf_Die));
532 return die_mem;
533 }
534 } while ((ret & DIE_FIND_CB_SIBLING) &&
535 dwarf_siblingof(die_mem, die_mem) == 0);
536
537 return NULL;
538 }
539
540 struct __addr_die_search_param {
541 Dwarf_Addr addr;
542 Dwarf_Die *die_mem;
543 };
544
__die_search_func_tail_cb(Dwarf_Die * fn_die,void * data)545 static int __die_search_func_tail_cb(Dwarf_Die *fn_die, void *data)
546 {
547 struct __addr_die_search_param *ad = data;
548 Dwarf_Addr addr = 0;
549
550 if (dwarf_tag(fn_die) == DW_TAG_subprogram &&
551 !dwarf_highpc(fn_die, &addr) &&
552 addr == ad->addr) {
553 memcpy(ad->die_mem, fn_die, sizeof(Dwarf_Die));
554 return DWARF_CB_ABORT;
555 }
556 return DWARF_CB_OK;
557 }
558
559 /**
560 * die_find_tailfunc - Search for a non-inlined function with tail call at
561 * given address
562 * @cu_die: a CU DIE which including @addr
563 * @addr: target address
564 * @die_mem: a buffer for result DIE
565 *
566 * Search for a non-inlined function DIE with tail call at @addr. Stores the
567 * DIE to @die_mem and returns it if found. Returns NULL if failed.
568 */
die_find_tailfunc(Dwarf_Die * cu_die,Dwarf_Addr addr,Dwarf_Die * die_mem)569 Dwarf_Die *die_find_tailfunc(Dwarf_Die *cu_die, Dwarf_Addr addr,
570 Dwarf_Die *die_mem)
571 {
572 struct __addr_die_search_param ad;
573 ad.addr = addr;
574 ad.die_mem = die_mem;
575 /* dwarf_getscopes can't find subprogram. */
576 if (!dwarf_getfuncs(cu_die, __die_search_func_tail_cb, &ad, 0))
577 return NULL;
578 else
579 return die_mem;
580 }
581
582 /* die_find callback for non-inlined function search */
__die_search_func_cb(Dwarf_Die * fn_die,void * data)583 static int __die_search_func_cb(Dwarf_Die *fn_die, void *data)
584 {
585 struct __addr_die_search_param *ad = data;
586
587 /*
588 * Since a declaration entry doesn't has given pc, this always returns
589 * function definition entry.
590 */
591 if (dwarf_tag(fn_die) == DW_TAG_subprogram &&
592 dwarf_haspc(fn_die, ad->addr)) {
593 memcpy(ad->die_mem, fn_die, sizeof(Dwarf_Die));
594 return DWARF_CB_ABORT;
595 }
596 return DWARF_CB_OK;
597 }
598
599 /**
600 * die_find_realfunc - Search a non-inlined function at given address
601 * @cu_die: a CU DIE which including @addr
602 * @addr: target address
603 * @die_mem: a buffer for result DIE
604 *
605 * Search a non-inlined function DIE which includes @addr. Stores the
606 * DIE to @die_mem and returns it if found. Returns NULL if failed.
607 */
die_find_realfunc(Dwarf_Die * cu_die,Dwarf_Addr addr,Dwarf_Die * die_mem)608 Dwarf_Die *die_find_realfunc(Dwarf_Die *cu_die, Dwarf_Addr addr,
609 Dwarf_Die *die_mem)
610 {
611 struct __addr_die_search_param ad;
612 ad.addr = addr;
613 ad.die_mem = die_mem;
614 /* dwarf_getscopes can't find subprogram. */
615 if (!dwarf_getfuncs(cu_die, __die_search_func_cb, &ad, 0))
616 return NULL;
617 else
618 return die_mem;
619 }
620
621 /* die_find callback for inline function search */
__die_find_inline_cb(Dwarf_Die * die_mem,void * data)622 static int __die_find_inline_cb(Dwarf_Die *die_mem, void *data)
623 {
624 Dwarf_Addr *addr = data;
625
626 if (dwarf_tag(die_mem) == DW_TAG_inlined_subroutine &&
627 dwarf_haspc(die_mem, *addr))
628 return DIE_FIND_CB_END;
629
630 return DIE_FIND_CB_CONTINUE;
631 }
632
633 /**
634 * die_find_top_inlinefunc - Search the top inlined function at given address
635 * @sp_die: a subprogram DIE which including @addr
636 * @addr: target address
637 * @die_mem: a buffer for result DIE
638 *
639 * Search an inlined function DIE which includes @addr. Stores the
640 * DIE to @die_mem and returns it if found. Returns NULL if failed.
641 * Even if several inlined functions are expanded recursively, this
642 * doesn't trace it down, and returns the topmost one.
643 */
die_find_top_inlinefunc(Dwarf_Die * sp_die,Dwarf_Addr addr,Dwarf_Die * die_mem)644 Dwarf_Die *die_find_top_inlinefunc(Dwarf_Die *sp_die, Dwarf_Addr addr,
645 Dwarf_Die *die_mem)
646 {
647 return die_find_child(sp_die, __die_find_inline_cb, &addr, die_mem);
648 }
649
650 /**
651 * die_find_inlinefunc - Search an inlined function at given address
652 * @sp_die: a subprogram DIE which including @addr
653 * @addr: target address
654 * @die_mem: a buffer for result DIE
655 *
656 * Search an inlined function DIE which includes @addr. Stores the
657 * DIE to @die_mem and returns it if found. Returns NULL if failed.
658 * If several inlined functions are expanded recursively, this trace
659 * it down and returns deepest one.
660 */
die_find_inlinefunc(Dwarf_Die * sp_die,Dwarf_Addr addr,Dwarf_Die * die_mem)661 Dwarf_Die *die_find_inlinefunc(Dwarf_Die *sp_die, Dwarf_Addr addr,
662 Dwarf_Die *die_mem)
663 {
664 Dwarf_Die tmp_die;
665
666 sp_die = die_find_child(sp_die, __die_find_inline_cb, &addr, &tmp_die);
667 if (!sp_die)
668 return NULL;
669
670 /* Inlined function could be recursive. Trace it until fail */
671 while (sp_die) {
672 memcpy(die_mem, sp_die, sizeof(Dwarf_Die));
673 sp_die = die_find_child(sp_die, __die_find_inline_cb, &addr,
674 &tmp_die);
675 }
676
677 return die_mem;
678 }
679
680 struct __instance_walk_param {
681 void *addr;
682 int (*callback)(Dwarf_Die *, void *);
683 void *data;
684 int retval;
685 };
686
__die_walk_instances_cb(Dwarf_Die * inst,void * data)687 static int __die_walk_instances_cb(Dwarf_Die *inst, void *data)
688 {
689 struct __instance_walk_param *iwp = data;
690 Dwarf_Attribute attr_mem;
691 Dwarf_Die origin_mem;
692 Dwarf_Attribute *attr;
693 Dwarf_Die *origin;
694 int tmp;
695
696 if (!die_is_func_instance(inst))
697 return DIE_FIND_CB_CONTINUE;
698
699 attr = dwarf_attr(inst, DW_AT_abstract_origin, &attr_mem);
700 if (attr == NULL)
701 return DIE_FIND_CB_CONTINUE;
702
703 origin = dwarf_formref_die(attr, &origin_mem);
704 if (origin == NULL || origin->addr != iwp->addr)
705 return DIE_FIND_CB_CONTINUE;
706
707 /* Ignore redundant instances */
708 if (dwarf_tag(inst) == DW_TAG_inlined_subroutine) {
709 dwarf_decl_line(origin, &tmp);
710 if (die_get_call_lineno(inst) == tmp) {
711 tmp = die_get_decl_fileno(origin);
712 if (die_get_call_fileno(inst) == tmp)
713 return DIE_FIND_CB_CONTINUE;
714 }
715 }
716
717 iwp->retval = iwp->callback(inst, iwp->data);
718
719 return (iwp->retval) ? DIE_FIND_CB_END : DIE_FIND_CB_CONTINUE;
720 }
721
722 /**
723 * die_walk_instances - Walk on instances of given DIE
724 * @or_die: an abstract original DIE
725 * @callback: a callback function which is called with instance DIE
726 * @data: user data
727 *
728 * Walk on the instances of give @in_die. @in_die must be an inlined function
729 * declartion. This returns the return value of @callback if it returns
730 * non-zero value, or -ENOENT if there is no instance.
731 */
die_walk_instances(Dwarf_Die * or_die,int (* callback)(Dwarf_Die *,void *),void * data)732 int die_walk_instances(Dwarf_Die *or_die, int (*callback)(Dwarf_Die *, void *),
733 void *data)
734 {
735 Dwarf_Die cu_die;
736 Dwarf_Die die_mem;
737 struct __instance_walk_param iwp = {
738 .addr = or_die->addr,
739 .callback = callback,
740 .data = data,
741 .retval = -ENOENT,
742 };
743
744 if (dwarf_diecu(or_die, &cu_die, NULL, NULL) == NULL)
745 return -ENOENT;
746
747 die_find_child(&cu_die, __die_walk_instances_cb, &iwp, &die_mem);
748
749 return iwp.retval;
750 }
751
752 /* Line walker internal parameters */
753 struct __line_walk_param {
754 bool recursive;
755 line_walk_callback_t callback;
756 void *data;
757 int retval;
758 };
759
__die_walk_funclines_cb(Dwarf_Die * in_die,void * data)760 static int __die_walk_funclines_cb(Dwarf_Die *in_die, void *data)
761 {
762 struct __line_walk_param *lw = data;
763 Dwarf_Addr addr = 0;
764 const char *fname;
765 int lineno;
766
767 if (dwarf_tag(in_die) == DW_TAG_inlined_subroutine) {
768 fname = die_get_call_file(in_die);
769 lineno = die_get_call_lineno(in_die);
770 if (fname && lineno > 0 && die_entrypc(in_die, &addr) == 0) {
771 lw->retval = lw->callback(fname, lineno, addr, lw->data);
772 if (lw->retval != 0)
773 return DIE_FIND_CB_END;
774 }
775 if (!lw->recursive)
776 return DIE_FIND_CB_SIBLING;
777 }
778
779 if (addr) {
780 fname = dwarf_decl_file(in_die);
781 if (fname && dwarf_decl_line(in_die, &lineno) == 0) {
782 lw->retval = lw->callback(fname, lineno, addr, lw->data);
783 if (lw->retval != 0)
784 return DIE_FIND_CB_END;
785 }
786 }
787
788 /* Continue to search nested inlined function call-sites */
789 return DIE_FIND_CB_CONTINUE;
790 }
791
792 /* Walk on lines of blocks included in given DIE */
__die_walk_funclines(Dwarf_Die * sp_die,bool recursive,line_walk_callback_t callback,void * data)793 static int __die_walk_funclines(Dwarf_Die *sp_die, bool recursive,
794 line_walk_callback_t callback, void *data)
795 {
796 struct __line_walk_param lw = {
797 .recursive = recursive,
798 .callback = callback,
799 .data = data,
800 .retval = 0,
801 };
802 Dwarf_Die die_mem;
803 Dwarf_Addr addr;
804 const char *fname;
805 int lineno;
806
807 /* Handle function declaration line */
808 fname = dwarf_decl_file(sp_die);
809 if (fname && dwarf_decl_line(sp_die, &lineno) == 0 &&
810 die_entrypc(sp_die, &addr) == 0) {
811 lw.retval = callback(fname, lineno, addr, data);
812 if (lw.retval != 0)
813 goto done;
814 }
815 die_find_child(sp_die, __die_walk_funclines_cb, &lw, &die_mem);
816 done:
817 return lw.retval;
818 }
819
__die_walk_culines_cb(Dwarf_Die * sp_die,void * data)820 static int __die_walk_culines_cb(Dwarf_Die *sp_die, void *data)
821 {
822 struct __line_walk_param *lw = data;
823
824 /*
825 * Since inlined function can include another inlined function in
826 * the same file, we need to walk in it recursively.
827 */
828 lw->retval = __die_walk_funclines(sp_die, true, lw->callback, lw->data);
829 if (lw->retval != 0)
830 return DWARF_CB_ABORT;
831
832 return DWARF_CB_OK;
833 }
834
835 /**
836 * die_walk_lines - Walk on lines inside given DIE
837 * @rt_die: a root DIE (CU, subprogram or inlined_subroutine)
838 * @callback: callback routine
839 * @data: user data
840 *
841 * Walk on all lines inside given @rt_die and call @callback on each line.
842 * If the @rt_die is a function, walk only on the lines inside the function,
843 * otherwise @rt_die must be a CU DIE.
844 * Note that this walks not only dwarf line list, but also function entries
845 * and inline call-site.
846 */
die_walk_lines(Dwarf_Die * rt_die,line_walk_callback_t callback,void * data)847 int die_walk_lines(Dwarf_Die *rt_die, line_walk_callback_t callback, void *data)
848 {
849 Dwarf_Lines *lines;
850 Dwarf_Line *line;
851 Dwarf_Addr addr;
852 const char *fname, *decf = NULL, *inf = NULL;
853 int lineno, ret = 0;
854 int decl = 0, inl;
855 Dwarf_Die die_mem, *cu_die;
856 size_t nlines, i;
857 bool flag;
858
859 /* Get the CU die */
860 if (dwarf_tag(rt_die) != DW_TAG_compile_unit) {
861 cu_die = dwarf_diecu(rt_die, &die_mem, NULL, NULL);
862 dwarf_decl_line(rt_die, &decl);
863 decf = dwarf_decl_file(rt_die);
864 } else
865 cu_die = rt_die;
866 if (!cu_die) {
867 pr_debug2("Failed to get CU from given DIE.\n");
868 return -EINVAL;
869 }
870
871 /* Get lines list in the CU */
872 if (dwarf_getsrclines(cu_die, &lines, &nlines) != 0) {
873 pr_debug2("Failed to get source lines on this CU.\n");
874 return -ENOENT;
875 }
876 pr_debug2("Get %zd lines from this CU\n", nlines);
877
878 /* Walk on the lines on lines list */
879 for (i = 0; i < nlines; i++) {
880 line = dwarf_onesrcline(lines, i);
881 if (line == NULL ||
882 dwarf_lineno(line, &lineno) != 0 ||
883 dwarf_lineaddr(line, &addr) != 0) {
884 pr_debug2("Failed to get line info. "
885 "Possible error in debuginfo.\n");
886 continue;
887 }
888 /* Skip end-of-sequence */
889 if (dwarf_lineendsequence(line, &flag) != 0 || flag)
890 continue;
891 /* Skip Non statement line-info */
892 if (dwarf_linebeginstatement(line, &flag) != 0 || !flag)
893 continue;
894 /* Filter lines based on address */
895 if (rt_die != cu_die) {
896 /*
897 * Address filtering
898 * The line is included in given function, and
899 * no inline block includes it.
900 */
901 if (!dwarf_haspc(rt_die, addr))
902 continue;
903
904 if (die_find_inlinefunc(rt_die, addr, &die_mem)) {
905 /* Call-site check */
906 inf = die_get_call_file(&die_mem);
907 if ((inf && !strcmp(inf, decf)) &&
908 die_get_call_lineno(&die_mem) == lineno)
909 goto found;
910
911 dwarf_decl_line(&die_mem, &inl);
912 if (inl != decl ||
913 decf != dwarf_decl_file(&die_mem))
914 continue;
915 }
916 }
917 found:
918 /* Get source line */
919 fname = dwarf_linesrc(line, NULL, NULL);
920
921 ret = callback(fname, lineno, addr, data);
922 if (ret != 0)
923 return ret;
924 }
925
926 /*
927 * Dwarf lines doesn't include function declarations and inlined
928 * subroutines. We have to check functions list or given function.
929 */
930 if (rt_die != cu_die)
931 /*
932 * Don't need walk inlined functions recursively, because
933 * inner inlined functions don't have the lines of the
934 * specified function.
935 */
936 ret = __die_walk_funclines(rt_die, false, callback, data);
937 else {
938 struct __line_walk_param param = {
939 .callback = callback,
940 .data = data,
941 .retval = 0,
942 };
943 dwarf_getfuncs(cu_die, __die_walk_culines_cb, ¶m, 0);
944 ret = param.retval;
945 }
946
947 return ret;
948 }
949
950 struct __find_variable_param {
951 const char *name;
952 Dwarf_Addr addr;
953 };
954
__die_find_variable_cb(Dwarf_Die * die_mem,void * data)955 static int __die_find_variable_cb(Dwarf_Die *die_mem, void *data)
956 {
957 struct __find_variable_param *fvp = data;
958 Dwarf_Attribute attr;
959 int tag;
960
961 tag = dwarf_tag(die_mem);
962 if ((tag == DW_TAG_formal_parameter ||
963 tag == DW_TAG_variable) &&
964 die_compare_name(die_mem, fvp->name) &&
965 /*
966 * Does the DIE have location information or const value
967 * or external instance?
968 */
969 (dwarf_attr(die_mem, DW_AT_external, &attr) ||
970 dwarf_attr(die_mem, DW_AT_location, &attr) ||
971 dwarf_attr(die_mem, DW_AT_const_value, &attr)))
972 return DIE_FIND_CB_END;
973 if (dwarf_haspc(die_mem, fvp->addr))
974 return DIE_FIND_CB_CONTINUE;
975 else
976 return DIE_FIND_CB_SIBLING;
977 }
978
979 /**
980 * die_find_variable_at - Find a given name variable at given address
981 * @sp_die: a function DIE
982 * @name: variable name
983 * @addr: address
984 * @die_mem: a buffer for result DIE
985 *
986 * Find a variable DIE called @name at @addr in @sp_die.
987 */
die_find_variable_at(Dwarf_Die * sp_die,const char * name,Dwarf_Addr addr,Dwarf_Die * die_mem)988 Dwarf_Die *die_find_variable_at(Dwarf_Die *sp_die, const char *name,
989 Dwarf_Addr addr, Dwarf_Die *die_mem)
990 {
991 struct __find_variable_param fvp = { .name = name, .addr = addr};
992
993 return die_find_child(sp_die, __die_find_variable_cb, (void *)&fvp,
994 die_mem);
995 }
996
__die_find_member_cb(Dwarf_Die * die_mem,void * data)997 static int __die_find_member_cb(Dwarf_Die *die_mem, void *data)
998 {
999 const char *name = data;
1000
1001 if (dwarf_tag(die_mem) == DW_TAG_member) {
1002 if (die_compare_name(die_mem, name))
1003 return DIE_FIND_CB_END;
1004 else if (!dwarf_diename(die_mem)) { /* Unnamed structure */
1005 Dwarf_Die type_die, tmp_die;
1006 if (die_get_type(die_mem, &type_die) &&
1007 die_find_member(&type_die, name, &tmp_die))
1008 return DIE_FIND_CB_END;
1009 }
1010 }
1011 return DIE_FIND_CB_SIBLING;
1012 }
1013
1014 /**
1015 * die_find_member - Find a given name member in a data structure
1016 * @st_die: a data structure type DIE
1017 * @name: member name
1018 * @die_mem: a buffer for result DIE
1019 *
1020 * Find a member DIE called @name in @st_die.
1021 */
die_find_member(Dwarf_Die * st_die,const char * name,Dwarf_Die * die_mem)1022 Dwarf_Die *die_find_member(Dwarf_Die *st_die, const char *name,
1023 Dwarf_Die *die_mem)
1024 {
1025 return die_find_child(st_die, __die_find_member_cb, (void *)name,
1026 die_mem);
1027 }
1028
1029 /**
1030 * die_get_typename - Get the name of given variable DIE
1031 * @vr_die: a variable DIE
1032 * @buf: a strbuf for result type name
1033 *
1034 * Get the name of @vr_die and stores it to @buf. Return 0 if succeeded.
1035 * and Return -ENOENT if failed to find type name.
1036 * Note that the result will stores typedef name if possible, and stores
1037 * "*(function_type)" if the type is a function pointer.
1038 */
die_get_typename(Dwarf_Die * vr_die,struct strbuf * buf)1039 int die_get_typename(Dwarf_Die *vr_die, struct strbuf *buf)
1040 {
1041 Dwarf_Die type;
1042 int tag, ret;
1043 const char *tmp = "";
1044
1045 if (__die_get_real_type(vr_die, &type) == NULL)
1046 return -ENOENT;
1047
1048 tag = dwarf_tag(&type);
1049 if (tag == DW_TAG_array_type || tag == DW_TAG_pointer_type)
1050 tmp = "*";
1051 else if (tag == DW_TAG_subroutine_type) {
1052 /* Function pointer */
1053 return strbuf_add(buf, "(function_type)", 15);
1054 } else {
1055 if (!dwarf_diename(&type))
1056 return -ENOENT;
1057 if (tag == DW_TAG_union_type)
1058 tmp = "union ";
1059 else if (tag == DW_TAG_structure_type)
1060 tmp = "struct ";
1061 else if (tag == DW_TAG_enumeration_type)
1062 tmp = "enum ";
1063 /* Write a base name */
1064 return strbuf_addf(buf, "%s%s", tmp, dwarf_diename(&type));
1065 }
1066 ret = die_get_typename(&type, buf);
1067 return ret ? ret : strbuf_addstr(buf, tmp);
1068 }
1069
1070 /**
1071 * die_get_varname - Get the name and type of given variable DIE
1072 * @vr_die: a variable DIE
1073 * @buf: a strbuf for type and variable name
1074 *
1075 * Get the name and type of @vr_die and stores it in @buf as "type\tname".
1076 */
die_get_varname(Dwarf_Die * vr_die,struct strbuf * buf)1077 int die_get_varname(Dwarf_Die *vr_die, struct strbuf *buf)
1078 {
1079 int ret;
1080
1081 ret = die_get_typename(vr_die, buf);
1082 if (ret < 0) {
1083 pr_debug("Failed to get type, make it unknown.\n");
1084 ret = strbuf_add(buf, " (unknown_type)", 14);
1085 }
1086
1087 return ret < 0 ? ret : strbuf_addf(buf, "\t%s", dwarf_diename(vr_die));
1088 }
1089
1090 #ifdef HAVE_DWARF_GETLOCATIONS_SUPPORT
1091 /**
1092 * die_get_var_innermost_scope - Get innermost scope range of given variable DIE
1093 * @sp_die: a subprogram DIE
1094 * @vr_die: a variable DIE
1095 * @buf: a strbuf for variable byte offset range
1096 *
1097 * Get the innermost scope range of @vr_die and stores it in @buf as
1098 * "@<function_name+[NN-NN,NN-NN]>".
1099 */
die_get_var_innermost_scope(Dwarf_Die * sp_die,Dwarf_Die * vr_die,struct strbuf * buf)1100 static int die_get_var_innermost_scope(Dwarf_Die *sp_die, Dwarf_Die *vr_die,
1101 struct strbuf *buf)
1102 {
1103 Dwarf_Die *scopes;
1104 int count;
1105 size_t offset = 0;
1106 Dwarf_Addr base;
1107 Dwarf_Addr start, end;
1108 Dwarf_Addr entry;
1109 int ret;
1110 bool first = true;
1111 const char *name;
1112
1113 ret = die_entrypc(sp_die, &entry);
1114 if (ret)
1115 return ret;
1116
1117 name = dwarf_diename(sp_die);
1118 if (!name)
1119 return -ENOENT;
1120
1121 count = dwarf_getscopes_die(vr_die, &scopes);
1122
1123 /* (*SCOPES)[1] is the DIE for the scope containing that scope */
1124 if (count <= 1) {
1125 ret = -EINVAL;
1126 goto out;
1127 }
1128
1129 while ((offset = dwarf_ranges(&scopes[1], offset, &base,
1130 &start, &end)) > 0) {
1131 start -= entry;
1132 end -= entry;
1133
1134 if (first) {
1135 ret = strbuf_addf(buf, "@<%s+[%" PRIu64 "-%" PRIu64,
1136 name, start, end);
1137 first = false;
1138 } else {
1139 ret = strbuf_addf(buf, ",%" PRIu64 "-%" PRIu64,
1140 start, end);
1141 }
1142 if (ret < 0)
1143 goto out;
1144 }
1145
1146 if (!first)
1147 ret = strbuf_add(buf, "]>", 2);
1148
1149 out:
1150 free(scopes);
1151 return ret;
1152 }
1153
1154 /**
1155 * die_get_var_range - Get byte offset range of given variable DIE
1156 * @sp_die: a subprogram DIE
1157 * @vr_die: a variable DIE
1158 * @buf: a strbuf for type and variable name and byte offset range
1159 *
1160 * Get the byte offset range of @vr_die and stores it in @buf as
1161 * "@<function_name+[NN-NN,NN-NN]>".
1162 */
die_get_var_range(Dwarf_Die * sp_die,Dwarf_Die * vr_die,struct strbuf * buf)1163 int die_get_var_range(Dwarf_Die *sp_die, Dwarf_Die *vr_die, struct strbuf *buf)
1164 {
1165 int ret = 0;
1166 Dwarf_Addr base;
1167 Dwarf_Addr start, end;
1168 Dwarf_Addr entry;
1169 Dwarf_Op *op;
1170 size_t nops;
1171 size_t offset = 0;
1172 Dwarf_Attribute attr;
1173 bool first = true;
1174 const char *name;
1175
1176 ret = die_entrypc(sp_die, &entry);
1177 if (ret)
1178 return ret;
1179
1180 name = dwarf_diename(sp_die);
1181 if (!name)
1182 return -ENOENT;
1183
1184 if (dwarf_attr(vr_die, DW_AT_location, &attr) == NULL)
1185 return -EINVAL;
1186
1187 while ((offset = dwarf_getlocations(&attr, offset, &base,
1188 &start, &end, &op, &nops)) > 0) {
1189 if (start == 0) {
1190 /* Single Location Descriptions */
1191 ret = die_get_var_innermost_scope(sp_die, vr_die, buf);
1192 goto out;
1193 }
1194
1195 /* Location Lists */
1196 start -= entry;
1197 end -= entry;
1198 if (first) {
1199 ret = strbuf_addf(buf, "@<%s+[%" PRIu64 "-%" PRIu64,
1200 name, start, end);
1201 first = false;
1202 } else {
1203 ret = strbuf_addf(buf, ",%" PRIu64 "-%" PRIu64,
1204 start, end);
1205 }
1206 if (ret < 0)
1207 goto out;
1208 }
1209
1210 if (!first)
1211 ret = strbuf_add(buf, "]>", 2);
1212 out:
1213 return ret;
1214 }
1215 #else
die_get_var_range(Dwarf_Die * sp_die __maybe_unused,Dwarf_Die * vr_die __maybe_unused,struct strbuf * buf __maybe_unused)1216 int die_get_var_range(Dwarf_Die *sp_die __maybe_unused,
1217 Dwarf_Die *vr_die __maybe_unused,
1218 struct strbuf *buf __maybe_unused)
1219 {
1220 return -ENOTSUP;
1221 }
1222 #endif
1223
1224 /*
1225 * die_has_loclist - Check if DW_AT_location of @vr_die is a location list
1226 * @vr_die: a variable DIE
1227 */
die_has_loclist(Dwarf_Die * vr_die)1228 static bool die_has_loclist(Dwarf_Die *vr_die)
1229 {
1230 Dwarf_Attribute loc;
1231 int tag = dwarf_tag(vr_die);
1232
1233 if (tag != DW_TAG_formal_parameter &&
1234 tag != DW_TAG_variable)
1235 return false;
1236
1237 return (dwarf_attr_integrate(vr_die, DW_AT_location, &loc) &&
1238 dwarf_whatform(&loc) == DW_FORM_sec_offset);
1239 }
1240
1241 /*
1242 * die_is_optimized_target - Check if target program is compiled with
1243 * optimization
1244 * @cu_die: a CU DIE
1245 *
1246 * For any object in given CU whose DW_AT_location is a location list,
1247 * target program is compiled with optimization. This is applicable to
1248 * clang as well.
1249 */
die_is_optimized_target(Dwarf_Die * cu_die)1250 bool die_is_optimized_target(Dwarf_Die *cu_die)
1251 {
1252 Dwarf_Die tmp_die;
1253
1254 if (die_has_loclist(cu_die))
1255 return true;
1256
1257 if (!dwarf_child(cu_die, &tmp_die) &&
1258 die_is_optimized_target(&tmp_die))
1259 return true;
1260
1261 if (!dwarf_siblingof(cu_die, &tmp_die) &&
1262 die_is_optimized_target(&tmp_die))
1263 return true;
1264
1265 return false;
1266 }
1267
1268 /*
1269 * die_search_idx - Search index of given line address
1270 * @lines: Line records of single CU
1271 * @nr_lines: Number of @lines
1272 * @addr: address we are looking for
1273 * @idx: index to be set by this function (return value)
1274 *
1275 * Search for @addr by looping over every lines of CU. If address
1276 * matches, set index of that line in @idx. Note that single source
1277 * line can have multiple line records. i.e. single source line can
1278 * have multiple index.
1279 */
die_search_idx(Dwarf_Lines * lines,unsigned long nr_lines,Dwarf_Addr addr,unsigned long * idx)1280 static bool die_search_idx(Dwarf_Lines *lines, unsigned long nr_lines,
1281 Dwarf_Addr addr, unsigned long *idx)
1282 {
1283 unsigned long i;
1284 Dwarf_Addr tmp;
1285
1286 for (i = 0; i < nr_lines; i++) {
1287 if (dwarf_lineaddr(dwarf_onesrcline(lines, i), &tmp))
1288 return false;
1289
1290 if (tmp == addr) {
1291 *idx = i;
1292 return true;
1293 }
1294 }
1295 return false;
1296 }
1297
1298 /*
1299 * die_get_postprologue_addr - Search next address after function prologue
1300 * @entrypc_idx: entrypc index
1301 * @lines: Line records of single CU
1302 * @nr_lines: Number of @lines
1303 * @hignpc: high PC address of function
1304 * @postprologue_addr: Next address after function prologue (return value)
1305 *
1306 * Look for prologue-end marker. If there is no explicit marker, return
1307 * address of next line record or next source line.
1308 */
die_get_postprologue_addr(unsigned long entrypc_idx,Dwarf_Lines * lines,unsigned long nr_lines,Dwarf_Addr highpc,Dwarf_Addr * postprologue_addr)1309 static bool die_get_postprologue_addr(unsigned long entrypc_idx,
1310 Dwarf_Lines *lines,
1311 unsigned long nr_lines,
1312 Dwarf_Addr highpc,
1313 Dwarf_Addr *postprologue_addr)
1314 {
1315 unsigned long i;
1316 int entrypc_lno, lno;
1317 Dwarf_Line *line;
1318 Dwarf_Addr addr;
1319 bool p_end;
1320
1321 /* entrypc_lno is actual source line number */
1322 line = dwarf_onesrcline(lines, entrypc_idx);
1323 if (dwarf_lineno(line, &entrypc_lno))
1324 return false;
1325
1326 for (i = entrypc_idx; i < nr_lines; i++) {
1327 line = dwarf_onesrcline(lines, i);
1328
1329 if (dwarf_lineaddr(line, &addr) ||
1330 dwarf_lineno(line, &lno) ||
1331 dwarf_lineprologueend(line, &p_end))
1332 return false;
1333
1334 /* highpc is exclusive. [entrypc,highpc) */
1335 if (addr >= highpc)
1336 break;
1337
1338 /* clang supports prologue-end marker */
1339 if (p_end)
1340 break;
1341
1342 /* Actual next line in source */
1343 if (lno != entrypc_lno)
1344 break;
1345
1346 /*
1347 * Single source line can have multiple line records.
1348 * For Example,
1349 * void foo() { printf("hello\n"); }
1350 * contains two line records. One points to declaration and
1351 * other points to printf() line. Variable 'lno' won't get
1352 * incremented in this case but 'i' will.
1353 */
1354 if (i != entrypc_idx)
1355 break;
1356 }
1357
1358 dwarf_lineaddr(line, postprologue_addr);
1359 if (*postprologue_addr >= highpc)
1360 dwarf_lineaddr(dwarf_onesrcline(lines, i - 1),
1361 postprologue_addr);
1362
1363 return true;
1364 }
1365
1366 /*
1367 * die_skip_prologue - Use next address after prologue as probe location
1368 * @sp_die: a subprogram DIE
1369 * @cu_die: a CU DIE
1370 * @entrypc: entrypc of the function
1371 *
1372 * Function prologue prepares stack and registers before executing function
1373 * logic. When target program is compiled without optimization, function
1374 * parameter information is only valid after prologue. When we probe entrypc
1375 * of the function, and try to record function parameter, it contains
1376 * garbage value.
1377 */
die_skip_prologue(Dwarf_Die * sp_die,Dwarf_Die * cu_die,Dwarf_Addr * entrypc)1378 void die_skip_prologue(Dwarf_Die *sp_die, Dwarf_Die *cu_die,
1379 Dwarf_Addr *entrypc)
1380 {
1381 size_t nr_lines = 0;
1382 unsigned long entrypc_idx = 0;
1383 Dwarf_Lines *lines = NULL;
1384 Dwarf_Addr postprologue_addr;
1385 Dwarf_Addr highpc;
1386
1387 if (dwarf_highpc(sp_die, &highpc))
1388 return;
1389
1390 if (dwarf_getsrclines(cu_die, &lines, &nr_lines))
1391 return;
1392
1393 if (!die_search_idx(lines, nr_lines, *entrypc, &entrypc_idx))
1394 return;
1395
1396 if (!die_get_postprologue_addr(entrypc_idx, lines, nr_lines,
1397 highpc, &postprologue_addr))
1398 return;
1399
1400 *entrypc = postprologue_addr;
1401 }
1402