xref: /openbmc/linux/tools/perf/util/probe-finder.c (revision d7a3d85e)
1 /*
2  * probe-finder.c : C expression to kprobe event converter
3  *
4  * Written by Masami Hiramatsu <mhiramat@redhat.com>
5  *
6  * This program is free software; you can redistribute it and/or modify
7  * it under the terms of the GNU General Public License as published by
8  * the Free Software Foundation; either version 2 of the License, or
9  * (at your option) any later version.
10  *
11  * This program is distributed in the hope that it will be useful,
12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14  * GNU General Public License for more details.
15  *
16  * You should have received a copy of the GNU General Public License
17  * along with this program; if not, write to the Free Software
18  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
19  *
20  */
21 
22 #include <sys/utsname.h>
23 #include <sys/types.h>
24 #include <sys/stat.h>
25 #include <fcntl.h>
26 #include <errno.h>
27 #include <stdio.h>
28 #include <unistd.h>
29 #include <stdlib.h>
30 #include <string.h>
31 #include <stdarg.h>
32 #include <dwarf-regs.h>
33 
34 #include <linux/bitops.h>
35 #include "event.h"
36 #include "dso.h"
37 #include "debug.h"
38 #include "intlist.h"
39 #include "util.h"
40 #include "symbol.h"
41 #include "probe-finder.h"
42 
43 /* Kprobe tracer basic type is up to u64 */
44 #define MAX_BASIC_TYPE_BITS	64
45 
46 /* Dwarf FL wrappers */
47 static char *debuginfo_path;	/* Currently dummy */
48 
49 static const Dwfl_Callbacks offline_callbacks = {
50 	.find_debuginfo = dwfl_standard_find_debuginfo,
51 	.debuginfo_path = &debuginfo_path,
52 
53 	.section_address = dwfl_offline_section_address,
54 
55 	/* We use this table for core files too.  */
56 	.find_elf = dwfl_build_id_find_elf,
57 };
58 
59 /* Get a Dwarf from offline image */
60 static int debuginfo__init_offline_dwarf(struct debuginfo *dbg,
61 					 const char *path)
62 {
63 	int fd;
64 
65 	fd = open(path, O_RDONLY);
66 	if (fd < 0)
67 		return fd;
68 
69 	dbg->dwfl = dwfl_begin(&offline_callbacks);
70 	if (!dbg->dwfl)
71 		goto error;
72 
73 	dbg->mod = dwfl_report_offline(dbg->dwfl, "", "", fd);
74 	if (!dbg->mod)
75 		goto error;
76 
77 	dbg->dbg = dwfl_module_getdwarf(dbg->mod, &dbg->bias);
78 	if (!dbg->dbg)
79 		goto error;
80 
81 	return 0;
82 error:
83 	if (dbg->dwfl)
84 		dwfl_end(dbg->dwfl);
85 	else
86 		close(fd);
87 	memset(dbg, 0, sizeof(*dbg));
88 
89 	return -ENOENT;
90 }
91 
92 static struct debuginfo *__debuginfo__new(const char *path)
93 {
94 	struct debuginfo *dbg = zalloc(sizeof(*dbg));
95 	if (!dbg)
96 		return NULL;
97 
98 	if (debuginfo__init_offline_dwarf(dbg, path) < 0)
99 		zfree(&dbg);
100 	if (dbg)
101 		pr_debug("Open Debuginfo file: %s\n", path);
102 	return dbg;
103 }
104 
105 enum dso_binary_type distro_dwarf_types[] = {
106 	DSO_BINARY_TYPE__FEDORA_DEBUGINFO,
107 	DSO_BINARY_TYPE__UBUNTU_DEBUGINFO,
108 	DSO_BINARY_TYPE__OPENEMBEDDED_DEBUGINFO,
109 	DSO_BINARY_TYPE__BUILDID_DEBUGINFO,
110 	DSO_BINARY_TYPE__NOT_FOUND,
111 };
112 
113 struct debuginfo *debuginfo__new(const char *path)
114 {
115 	enum dso_binary_type *type;
116 	char buf[PATH_MAX], nil = '\0';
117 	struct dso *dso;
118 	struct debuginfo *dinfo = NULL;
119 
120 	/* Try to open distro debuginfo files */
121 	dso = dso__new(path);
122 	if (!dso)
123 		goto out;
124 
125 	for (type = distro_dwarf_types;
126 	     !dinfo && *type != DSO_BINARY_TYPE__NOT_FOUND;
127 	     type++) {
128 		if (dso__read_binary_type_filename(dso, *type, &nil,
129 						   buf, PATH_MAX) < 0)
130 			continue;
131 		dinfo = __debuginfo__new(buf);
132 	}
133 	dso__delete(dso);
134 
135 out:
136 	/* if failed to open all distro debuginfo, open given binary */
137 	return dinfo ? : __debuginfo__new(path);
138 }
139 
140 void debuginfo__delete(struct debuginfo *dbg)
141 {
142 	if (dbg) {
143 		if (dbg->dwfl)
144 			dwfl_end(dbg->dwfl);
145 		free(dbg);
146 	}
147 }
148 
149 /*
150  * Probe finder related functions
151  */
152 
153 static struct probe_trace_arg_ref *alloc_trace_arg_ref(long offs)
154 {
155 	struct probe_trace_arg_ref *ref;
156 	ref = zalloc(sizeof(struct probe_trace_arg_ref));
157 	if (ref != NULL)
158 		ref->offset = offs;
159 	return ref;
160 }
161 
162 /*
163  * Convert a location into trace_arg.
164  * If tvar == NULL, this just checks variable can be converted.
165  * If fentry == true and vr_die is a parameter, do huristic search
166  * for the location fuzzed by function entry mcount.
167  */
168 static int convert_variable_location(Dwarf_Die *vr_die, Dwarf_Addr addr,
169 				     Dwarf_Op *fb_ops, Dwarf_Die *sp_die,
170 				     struct probe_trace_arg *tvar)
171 {
172 	Dwarf_Attribute attr;
173 	Dwarf_Addr tmp = 0;
174 	Dwarf_Op *op;
175 	size_t nops;
176 	unsigned int regn;
177 	Dwarf_Word offs = 0;
178 	bool ref = false;
179 	const char *regs;
180 	int ret, ret2 = 0;
181 
182 	if (dwarf_attr(vr_die, DW_AT_external, &attr) != NULL)
183 		goto static_var;
184 
185 	/* TODO: handle more than 1 exprs */
186 	if (dwarf_attr(vr_die, DW_AT_location, &attr) == NULL)
187 		return -EINVAL;	/* Broken DIE ? */
188 	if (dwarf_getlocation_addr(&attr, addr, &op, &nops, 1) <= 0) {
189 		ret = dwarf_entrypc(sp_die, &tmp);
190 		if (ret)
191 			return -ENOENT;
192 
193 		if (probe_conf.show_location_range &&
194 			(dwarf_tag(vr_die) == DW_TAG_variable)) {
195 			ret2 = -ERANGE;
196 		} else if (addr != tmp ||
197 			dwarf_tag(vr_die) != DW_TAG_formal_parameter) {
198 			return -ENOENT;
199 		}
200 
201 		ret = dwarf_highpc(sp_die, &tmp);
202 		if (ret)
203 			return -ENOENT;
204 		/*
205 		 * This is fuzzed by fentry mcount. We try to find the
206 		 * parameter location at the earliest address.
207 		 */
208 		for (addr += 1; addr <= tmp; addr++) {
209 			if (dwarf_getlocation_addr(&attr, addr, &op,
210 						   &nops, 1) > 0)
211 				goto found;
212 		}
213 		return -ENOENT;
214 	}
215 found:
216 	if (nops == 0)
217 		/* TODO: Support const_value */
218 		return -ENOENT;
219 
220 	if (op->atom == DW_OP_addr) {
221 static_var:
222 		if (!tvar)
223 			return ret2;
224 		/* Static variables on memory (not stack), make @varname */
225 		ret = strlen(dwarf_diename(vr_die));
226 		tvar->value = zalloc(ret + 2);
227 		if (tvar->value == NULL)
228 			return -ENOMEM;
229 		snprintf(tvar->value, ret + 2, "@%s", dwarf_diename(vr_die));
230 		tvar->ref = alloc_trace_arg_ref((long)offs);
231 		if (tvar->ref == NULL)
232 			return -ENOMEM;
233 		return ret2;
234 	}
235 
236 	/* If this is based on frame buffer, set the offset */
237 	if (op->atom == DW_OP_fbreg) {
238 		if (fb_ops == NULL)
239 			return -ENOTSUP;
240 		ref = true;
241 		offs = op->number;
242 		op = &fb_ops[0];
243 	}
244 
245 	if (op->atom >= DW_OP_breg0 && op->atom <= DW_OP_breg31) {
246 		regn = op->atom - DW_OP_breg0;
247 		offs += op->number;
248 		ref = true;
249 	} else if (op->atom >= DW_OP_reg0 && op->atom <= DW_OP_reg31) {
250 		regn = op->atom - DW_OP_reg0;
251 	} else if (op->atom == DW_OP_bregx) {
252 		regn = op->number;
253 		offs += op->number2;
254 		ref = true;
255 	} else if (op->atom == DW_OP_regx) {
256 		regn = op->number;
257 	} else {
258 		pr_debug("DW_OP %x is not supported.\n", op->atom);
259 		return -ENOTSUP;
260 	}
261 
262 	if (!tvar)
263 		return ret2;
264 
265 	regs = get_arch_regstr(regn);
266 	if (!regs) {
267 		/* This should be a bug in DWARF or this tool */
268 		pr_warning("Mapping for the register number %u "
269 			   "missing on this architecture.\n", regn);
270 		return -ENOTSUP;
271 	}
272 
273 	tvar->value = strdup(regs);
274 	if (tvar->value == NULL)
275 		return -ENOMEM;
276 
277 	if (ref) {
278 		tvar->ref = alloc_trace_arg_ref((long)offs);
279 		if (tvar->ref == NULL)
280 			return -ENOMEM;
281 	}
282 	return ret2;
283 }
284 
285 #define BYTES_TO_BITS(nb)	((nb) * BITS_PER_LONG / sizeof(long))
286 
287 static int convert_variable_type(Dwarf_Die *vr_die,
288 				 struct probe_trace_arg *tvar,
289 				 const char *cast)
290 {
291 	struct probe_trace_arg_ref **ref_ptr = &tvar->ref;
292 	Dwarf_Die type;
293 	char buf[16];
294 	char sbuf[STRERR_BUFSIZE];
295 	int bsize, boffs, total;
296 	int ret;
297 
298 	/* TODO: check all types */
299 	if (cast && strcmp(cast, "string") != 0) {
300 		/* Non string type is OK */
301 		tvar->type = strdup(cast);
302 		return (tvar->type == NULL) ? -ENOMEM : 0;
303 	}
304 
305 	bsize = dwarf_bitsize(vr_die);
306 	if (bsize > 0) {
307 		/* This is a bitfield */
308 		boffs = dwarf_bitoffset(vr_die);
309 		total = dwarf_bytesize(vr_die);
310 		if (boffs < 0 || total < 0)
311 			return -ENOENT;
312 		ret = snprintf(buf, 16, "b%d@%d/%zd", bsize, boffs,
313 				BYTES_TO_BITS(total));
314 		goto formatted;
315 	}
316 
317 	if (die_get_real_type(vr_die, &type) == NULL) {
318 		pr_warning("Failed to get a type information of %s.\n",
319 			   dwarf_diename(vr_die));
320 		return -ENOENT;
321 	}
322 
323 	pr_debug("%s type is %s.\n",
324 		 dwarf_diename(vr_die), dwarf_diename(&type));
325 
326 	if (cast && strcmp(cast, "string") == 0) {	/* String type */
327 		ret = dwarf_tag(&type);
328 		if (ret != DW_TAG_pointer_type &&
329 		    ret != DW_TAG_array_type) {
330 			pr_warning("Failed to cast into string: "
331 				   "%s(%s) is not a pointer nor array.\n",
332 				   dwarf_diename(vr_die), dwarf_diename(&type));
333 			return -EINVAL;
334 		}
335 		if (die_get_real_type(&type, &type) == NULL) {
336 			pr_warning("Failed to get a type"
337 				   " information.\n");
338 			return -ENOENT;
339 		}
340 		if (ret == DW_TAG_pointer_type) {
341 			while (*ref_ptr)
342 				ref_ptr = &(*ref_ptr)->next;
343 			/* Add new reference with offset +0 */
344 			*ref_ptr = zalloc(sizeof(struct probe_trace_arg_ref));
345 			if (*ref_ptr == NULL) {
346 				pr_warning("Out of memory error\n");
347 				return -ENOMEM;
348 			}
349 		}
350 		if (!die_compare_name(&type, "char") &&
351 		    !die_compare_name(&type, "unsigned char")) {
352 			pr_warning("Failed to cast into string: "
353 				   "%s is not (unsigned) char *.\n",
354 				   dwarf_diename(vr_die));
355 			return -EINVAL;
356 		}
357 		tvar->type = strdup(cast);
358 		return (tvar->type == NULL) ? -ENOMEM : 0;
359 	}
360 
361 	ret = dwarf_bytesize(&type);
362 	if (ret <= 0)
363 		/* No size ... try to use default type */
364 		return 0;
365 	ret = BYTES_TO_BITS(ret);
366 
367 	/* Check the bitwidth */
368 	if (ret > MAX_BASIC_TYPE_BITS) {
369 		pr_info("%s exceeds max-bitwidth. Cut down to %d bits.\n",
370 			dwarf_diename(&type), MAX_BASIC_TYPE_BITS);
371 		ret = MAX_BASIC_TYPE_BITS;
372 	}
373 	ret = snprintf(buf, 16, "%c%d",
374 		       die_is_signed_type(&type) ? 's' : 'u', ret);
375 
376 formatted:
377 	if (ret < 0 || ret >= 16) {
378 		if (ret >= 16)
379 			ret = -E2BIG;
380 		pr_warning("Failed to convert variable type: %s\n",
381 			   strerror_r(-ret, sbuf, sizeof(sbuf)));
382 		return ret;
383 	}
384 	tvar->type = strdup(buf);
385 	if (tvar->type == NULL)
386 		return -ENOMEM;
387 	return 0;
388 }
389 
390 static int convert_variable_fields(Dwarf_Die *vr_die, const char *varname,
391 				    struct perf_probe_arg_field *field,
392 				    struct probe_trace_arg_ref **ref_ptr,
393 				    Dwarf_Die *die_mem)
394 {
395 	struct probe_trace_arg_ref *ref = *ref_ptr;
396 	Dwarf_Die type;
397 	Dwarf_Word offs;
398 	int ret, tag;
399 
400 	pr_debug("converting %s in %s\n", field->name, varname);
401 	if (die_get_real_type(vr_die, &type) == NULL) {
402 		pr_warning("Failed to get the type of %s.\n", varname);
403 		return -ENOENT;
404 	}
405 	pr_debug2("Var real type: (%x)\n", (unsigned)dwarf_dieoffset(&type));
406 	tag = dwarf_tag(&type);
407 
408 	if (field->name[0] == '[' &&
409 	    (tag == DW_TAG_array_type || tag == DW_TAG_pointer_type)) {
410 		if (field->next)
411 			/* Save original type for next field */
412 			memcpy(die_mem, &type, sizeof(*die_mem));
413 		/* Get the type of this array */
414 		if (die_get_real_type(&type, &type) == NULL) {
415 			pr_warning("Failed to get the type of %s.\n", varname);
416 			return -ENOENT;
417 		}
418 		pr_debug2("Array real type: (%x)\n",
419 			 (unsigned)dwarf_dieoffset(&type));
420 		if (tag == DW_TAG_pointer_type) {
421 			ref = zalloc(sizeof(struct probe_trace_arg_ref));
422 			if (ref == NULL)
423 				return -ENOMEM;
424 			if (*ref_ptr)
425 				(*ref_ptr)->next = ref;
426 			else
427 				*ref_ptr = ref;
428 		}
429 		ref->offset += dwarf_bytesize(&type) * field->index;
430 		if (!field->next)
431 			/* Save vr_die for converting types */
432 			memcpy(die_mem, vr_die, sizeof(*die_mem));
433 		goto next;
434 	} else if (tag == DW_TAG_pointer_type) {
435 		/* Check the pointer and dereference */
436 		if (!field->ref) {
437 			pr_err("Semantic error: %s must be referred by '->'\n",
438 			       field->name);
439 			return -EINVAL;
440 		}
441 		/* Get the type pointed by this pointer */
442 		if (die_get_real_type(&type, &type) == NULL) {
443 			pr_warning("Failed to get the type of %s.\n", varname);
444 			return -ENOENT;
445 		}
446 		/* Verify it is a data structure  */
447 		tag = dwarf_tag(&type);
448 		if (tag != DW_TAG_structure_type && tag != DW_TAG_union_type) {
449 			pr_warning("%s is not a data structure nor an union.\n",
450 				   varname);
451 			return -EINVAL;
452 		}
453 
454 		ref = zalloc(sizeof(struct probe_trace_arg_ref));
455 		if (ref == NULL)
456 			return -ENOMEM;
457 		if (*ref_ptr)
458 			(*ref_ptr)->next = ref;
459 		else
460 			*ref_ptr = ref;
461 	} else {
462 		/* Verify it is a data structure  */
463 		if (tag != DW_TAG_structure_type && tag != DW_TAG_union_type) {
464 			pr_warning("%s is not a data structure nor an union.\n",
465 				   varname);
466 			return -EINVAL;
467 		}
468 		if (field->name[0] == '[') {
469 			pr_err("Semantic error: %s is not a pointer"
470 			       " nor array.\n", varname);
471 			return -EINVAL;
472 		}
473 		/* While prcessing unnamed field, we don't care about this */
474 		if (field->ref && dwarf_diename(vr_die)) {
475 			pr_err("Semantic error: %s must be referred by '.'\n",
476 			       field->name);
477 			return -EINVAL;
478 		}
479 		if (!ref) {
480 			pr_warning("Structure on a register is not "
481 				   "supported yet.\n");
482 			return -ENOTSUP;
483 		}
484 	}
485 
486 	if (die_find_member(&type, field->name, die_mem) == NULL) {
487 		pr_warning("%s(type:%s) has no member %s.\n", varname,
488 			   dwarf_diename(&type), field->name);
489 		return -EINVAL;
490 	}
491 
492 	/* Get the offset of the field */
493 	if (tag == DW_TAG_union_type) {
494 		offs = 0;
495 	} else {
496 		ret = die_get_data_member_location(die_mem, &offs);
497 		if (ret < 0) {
498 			pr_warning("Failed to get the offset of %s.\n",
499 				   field->name);
500 			return ret;
501 		}
502 	}
503 	ref->offset += (long)offs;
504 
505 	/* If this member is unnamed, we need to reuse this field */
506 	if (!dwarf_diename(die_mem))
507 		return convert_variable_fields(die_mem, varname, field,
508 						&ref, die_mem);
509 
510 next:
511 	/* Converting next field */
512 	if (field->next)
513 		return convert_variable_fields(die_mem, field->name,
514 					field->next, &ref, die_mem);
515 	else
516 		return 0;
517 }
518 
519 /* Show a variables in kprobe event format */
520 static int convert_variable(Dwarf_Die *vr_die, struct probe_finder *pf)
521 {
522 	Dwarf_Die die_mem;
523 	int ret;
524 
525 	pr_debug("Converting variable %s into trace event.\n",
526 		 dwarf_diename(vr_die));
527 
528 	ret = convert_variable_location(vr_die, pf->addr, pf->fb_ops,
529 					&pf->sp_die, pf->tvar);
530 	if (ret == -ENOENT || ret == -EINVAL) {
531 		pr_err("Failed to find the location of the '%s' variable at this address.\n"
532 		       " Perhaps it has been optimized out.\n"
533 		       " Use -V with the --range option to show '%s' location range.\n",
534 		       pf->pvar->var, pf->pvar->var);
535 	} else if (ret == -ENOTSUP)
536 		pr_err("Sorry, we don't support this variable location yet.\n");
537 	else if (ret == 0 && pf->pvar->field) {
538 		ret = convert_variable_fields(vr_die, pf->pvar->var,
539 					      pf->pvar->field, &pf->tvar->ref,
540 					      &die_mem);
541 		vr_die = &die_mem;
542 	}
543 	if (ret == 0)
544 		ret = convert_variable_type(vr_die, pf->tvar, pf->pvar->type);
545 	/* *expr will be cached in libdw. Don't free it. */
546 	return ret;
547 }
548 
549 /* Find a variable in a scope DIE */
550 static int find_variable(Dwarf_Die *sc_die, struct probe_finder *pf)
551 {
552 	Dwarf_Die vr_die;
553 	char buf[32], *ptr;
554 	int ret = 0;
555 
556 	if (!is_c_varname(pf->pvar->var)) {
557 		/* Copy raw parameters */
558 		pf->tvar->value = strdup(pf->pvar->var);
559 		if (pf->tvar->value == NULL)
560 			return -ENOMEM;
561 		if (pf->pvar->type) {
562 			pf->tvar->type = strdup(pf->pvar->type);
563 			if (pf->tvar->type == NULL)
564 				return -ENOMEM;
565 		}
566 		if (pf->pvar->name) {
567 			pf->tvar->name = strdup(pf->pvar->name);
568 			if (pf->tvar->name == NULL)
569 				return -ENOMEM;
570 		} else
571 			pf->tvar->name = NULL;
572 		return 0;
573 	}
574 
575 	if (pf->pvar->name)
576 		pf->tvar->name = strdup(pf->pvar->name);
577 	else {
578 		ret = synthesize_perf_probe_arg(pf->pvar, buf, 32);
579 		if (ret < 0)
580 			return ret;
581 		ptr = strchr(buf, ':');	/* Change type separator to _ */
582 		if (ptr)
583 			*ptr = '_';
584 		pf->tvar->name = strdup(buf);
585 	}
586 	if (pf->tvar->name == NULL)
587 		return -ENOMEM;
588 
589 	pr_debug("Searching '%s' variable in context.\n", pf->pvar->var);
590 	/* Search child die for local variables and parameters. */
591 	if (!die_find_variable_at(sc_die, pf->pvar->var, pf->addr, &vr_die)) {
592 		/* Search again in global variables */
593 		if (!die_find_variable_at(&pf->cu_die, pf->pvar->var,
594 						0, &vr_die)) {
595 			pr_warning("Failed to find '%s' in this function.\n",
596 				   pf->pvar->var);
597 			ret = -ENOENT;
598 		}
599 	}
600 	if (ret >= 0)
601 		ret = convert_variable(&vr_die, pf);
602 
603 	return ret;
604 }
605 
606 /* Convert subprogram DIE to trace point */
607 static int convert_to_trace_point(Dwarf_Die *sp_die, Dwfl_Module *mod,
608 				  Dwarf_Addr paddr, bool retprobe,
609 				  struct probe_trace_point *tp)
610 {
611 	Dwarf_Addr eaddr, highaddr;
612 	GElf_Sym sym;
613 	const char *symbol;
614 
615 	/* Verify the address is correct */
616 	if (dwarf_entrypc(sp_die, &eaddr) != 0) {
617 		pr_warning("Failed to get entry address of %s\n",
618 			   dwarf_diename(sp_die));
619 		return -ENOENT;
620 	}
621 	if (dwarf_highpc(sp_die, &highaddr) != 0) {
622 		pr_warning("Failed to get end address of %s\n",
623 			   dwarf_diename(sp_die));
624 		return -ENOENT;
625 	}
626 	if (paddr > highaddr) {
627 		pr_warning("Offset specified is greater than size of %s\n",
628 			   dwarf_diename(sp_die));
629 		return -EINVAL;
630 	}
631 
632 	symbol = dwarf_diename(sp_die);
633 	if (!symbol) {
634 		/* Try to get the symbol name from symtab */
635 		symbol = dwfl_module_addrsym(mod, paddr, &sym, NULL);
636 		if (!symbol) {
637 			pr_warning("Failed to find symbol at 0x%lx\n",
638 				   (unsigned long)paddr);
639 			return -ENOENT;
640 		}
641 		eaddr = sym.st_value;
642 	}
643 	tp->offset = (unsigned long)(paddr - eaddr);
644 	tp->address = (unsigned long)paddr;
645 	tp->symbol = strdup(symbol);
646 	if (!tp->symbol)
647 		return -ENOMEM;
648 
649 	/* Return probe must be on the head of a subprogram */
650 	if (retprobe) {
651 		if (eaddr != paddr) {
652 			pr_warning("Return probe must be on the head of"
653 				   " a real function.\n");
654 			return -EINVAL;
655 		}
656 		tp->retprobe = true;
657 	}
658 
659 	return 0;
660 }
661 
662 /* Call probe_finder callback with scope DIE */
663 static int call_probe_finder(Dwarf_Die *sc_die, struct probe_finder *pf)
664 {
665 	Dwarf_Attribute fb_attr;
666 	size_t nops;
667 	int ret;
668 
669 	if (!sc_die) {
670 		pr_err("Caller must pass a scope DIE. Program error.\n");
671 		return -EINVAL;
672 	}
673 
674 	/* If not a real subprogram, find a real one */
675 	if (!die_is_func_def(sc_die)) {
676 		if (!die_find_realfunc(&pf->cu_die, pf->addr, &pf->sp_die)) {
677 			if (die_find_tailfunc(&pf->cu_die, pf->addr, &pf->sp_die)) {
678 				pr_warning("Ignoring tail call from %s\n",
679 						dwarf_diename(&pf->sp_die));
680 				return 0;
681 			} else {
682 				pr_warning("Failed to find probe point in any "
683 					   "functions.\n");
684 				return -ENOENT;
685 			}
686 		}
687 	} else
688 		memcpy(&pf->sp_die, sc_die, sizeof(Dwarf_Die));
689 
690 	/* Get the frame base attribute/ops from subprogram */
691 	dwarf_attr(&pf->sp_die, DW_AT_frame_base, &fb_attr);
692 	ret = dwarf_getlocation_addr(&fb_attr, pf->addr, &pf->fb_ops, &nops, 1);
693 	if (ret <= 0 || nops == 0) {
694 		pf->fb_ops = NULL;
695 #if _ELFUTILS_PREREQ(0, 142)
696 	} else if (nops == 1 && pf->fb_ops[0].atom == DW_OP_call_frame_cfa &&
697 		   pf->cfi != NULL) {
698 		Dwarf_Frame *frame;
699 		if (dwarf_cfi_addrframe(pf->cfi, pf->addr, &frame) != 0 ||
700 		    dwarf_frame_cfa(frame, &pf->fb_ops, &nops) != 0) {
701 			pr_warning("Failed to get call frame on 0x%jx\n",
702 				   (uintmax_t)pf->addr);
703 			return -ENOENT;
704 		}
705 #endif
706 	}
707 
708 	/* Call finder's callback handler */
709 	ret = pf->callback(sc_die, pf);
710 
711 	/* *pf->fb_ops will be cached in libdw. Don't free it. */
712 	pf->fb_ops = NULL;
713 
714 	return ret;
715 }
716 
717 struct find_scope_param {
718 	const char *function;
719 	const char *file;
720 	int line;
721 	int diff;
722 	Dwarf_Die *die_mem;
723 	bool found;
724 };
725 
726 static int find_best_scope_cb(Dwarf_Die *fn_die, void *data)
727 {
728 	struct find_scope_param *fsp = data;
729 	const char *file;
730 	int lno;
731 
732 	/* Skip if declared file name does not match */
733 	if (fsp->file) {
734 		file = dwarf_decl_file(fn_die);
735 		if (!file || strcmp(fsp->file, file) != 0)
736 			return 0;
737 	}
738 	/* If the function name is given, that's what user expects */
739 	if (fsp->function) {
740 		if (die_match_name(fn_die, fsp->function)) {
741 			memcpy(fsp->die_mem, fn_die, sizeof(Dwarf_Die));
742 			fsp->found = true;
743 			return 1;
744 		}
745 	} else {
746 		/* With the line number, find the nearest declared DIE */
747 		dwarf_decl_line(fn_die, &lno);
748 		if (lno < fsp->line && fsp->diff > fsp->line - lno) {
749 			/* Keep a candidate and continue */
750 			fsp->diff = fsp->line - lno;
751 			memcpy(fsp->die_mem, fn_die, sizeof(Dwarf_Die));
752 			fsp->found = true;
753 		}
754 	}
755 	return 0;
756 }
757 
758 /* Find an appropriate scope fits to given conditions */
759 static Dwarf_Die *find_best_scope(struct probe_finder *pf, Dwarf_Die *die_mem)
760 {
761 	struct find_scope_param fsp = {
762 		.function = pf->pev->point.function,
763 		.file = pf->fname,
764 		.line = pf->lno,
765 		.diff = INT_MAX,
766 		.die_mem = die_mem,
767 		.found = false,
768 	};
769 
770 	cu_walk_functions_at(&pf->cu_die, pf->addr, find_best_scope_cb, &fsp);
771 
772 	return fsp.found ? die_mem : NULL;
773 }
774 
775 static int probe_point_line_walker(const char *fname, int lineno,
776 				   Dwarf_Addr addr, void *data)
777 {
778 	struct probe_finder *pf = data;
779 	Dwarf_Die *sc_die, die_mem;
780 	int ret;
781 
782 	if (lineno != pf->lno || strtailcmp(fname, pf->fname) != 0)
783 		return 0;
784 
785 	pf->addr = addr;
786 	sc_die = find_best_scope(pf, &die_mem);
787 	if (!sc_die) {
788 		pr_warning("Failed to find scope of probe point.\n");
789 		return -ENOENT;
790 	}
791 
792 	ret = call_probe_finder(sc_die, pf);
793 
794 	/* Continue if no error, because the line will be in inline function */
795 	return ret < 0 ? ret : 0;
796 }
797 
798 /* Find probe point from its line number */
799 static int find_probe_point_by_line(struct probe_finder *pf)
800 {
801 	return die_walk_lines(&pf->cu_die, probe_point_line_walker, pf);
802 }
803 
804 /* Find lines which match lazy pattern */
805 static int find_lazy_match_lines(struct intlist *list,
806 				 const char *fname, const char *pat)
807 {
808 	FILE *fp;
809 	char *line = NULL;
810 	size_t line_len;
811 	ssize_t len;
812 	int count = 0, linenum = 1;
813 	char sbuf[STRERR_BUFSIZE];
814 
815 	fp = fopen(fname, "r");
816 	if (!fp) {
817 		pr_warning("Failed to open %s: %s\n", fname,
818 			   strerror_r(errno, sbuf, sizeof(sbuf)));
819 		return -errno;
820 	}
821 
822 	while ((len = getline(&line, &line_len, fp)) > 0) {
823 
824 		if (line[len - 1] == '\n')
825 			line[len - 1] = '\0';
826 
827 		if (strlazymatch(line, pat)) {
828 			intlist__add(list, linenum);
829 			count++;
830 		}
831 		linenum++;
832 	}
833 
834 	if (ferror(fp))
835 		count = -errno;
836 	free(line);
837 	fclose(fp);
838 
839 	if (count == 0)
840 		pr_debug("No matched lines found in %s.\n", fname);
841 	return count;
842 }
843 
844 static int probe_point_lazy_walker(const char *fname, int lineno,
845 				   Dwarf_Addr addr, void *data)
846 {
847 	struct probe_finder *pf = data;
848 	Dwarf_Die *sc_die, die_mem;
849 	int ret;
850 
851 	if (!intlist__has_entry(pf->lcache, lineno) ||
852 	    strtailcmp(fname, pf->fname) != 0)
853 		return 0;
854 
855 	pr_debug("Probe line found: line:%d addr:0x%llx\n",
856 		 lineno, (unsigned long long)addr);
857 	pf->addr = addr;
858 	pf->lno = lineno;
859 	sc_die = find_best_scope(pf, &die_mem);
860 	if (!sc_die) {
861 		pr_warning("Failed to find scope of probe point.\n");
862 		return -ENOENT;
863 	}
864 
865 	ret = call_probe_finder(sc_die, pf);
866 
867 	/*
868 	 * Continue if no error, because the lazy pattern will match
869 	 * to other lines
870 	 */
871 	return ret < 0 ? ret : 0;
872 }
873 
874 /* Find probe points from lazy pattern  */
875 static int find_probe_point_lazy(Dwarf_Die *sp_die, struct probe_finder *pf)
876 {
877 	int ret = 0;
878 	char *fpath;
879 
880 	if (intlist__empty(pf->lcache)) {
881 		const char *comp_dir;
882 
883 		comp_dir = cu_get_comp_dir(&pf->cu_die);
884 		ret = get_real_path(pf->fname, comp_dir, &fpath);
885 		if (ret < 0) {
886 			pr_warning("Failed to find source file path.\n");
887 			return ret;
888 		}
889 
890 		/* Matching lazy line pattern */
891 		ret = find_lazy_match_lines(pf->lcache, fpath,
892 					    pf->pev->point.lazy_line);
893 		free(fpath);
894 		if (ret <= 0)
895 			return ret;
896 	}
897 
898 	return die_walk_lines(sp_die, probe_point_lazy_walker, pf);
899 }
900 
901 static int probe_point_inline_cb(Dwarf_Die *in_die, void *data)
902 {
903 	struct probe_finder *pf = data;
904 	struct perf_probe_point *pp = &pf->pev->point;
905 	Dwarf_Addr addr;
906 	int ret;
907 
908 	if (pp->lazy_line)
909 		ret = find_probe_point_lazy(in_die, pf);
910 	else {
911 		/* Get probe address */
912 		if (dwarf_entrypc(in_die, &addr) != 0) {
913 			pr_warning("Failed to get entry address of %s.\n",
914 				   dwarf_diename(in_die));
915 			return -ENOENT;
916 		}
917 		pf->addr = addr;
918 		pf->addr += pp->offset;
919 		pr_debug("found inline addr: 0x%jx\n",
920 			 (uintmax_t)pf->addr);
921 
922 		ret = call_probe_finder(in_die, pf);
923 	}
924 
925 	return ret;
926 }
927 
928 /* Callback parameter with return value for libdw */
929 struct dwarf_callback_param {
930 	void *data;
931 	int retval;
932 };
933 
934 /* Search function from function name */
935 static int probe_point_search_cb(Dwarf_Die *sp_die, void *data)
936 {
937 	struct dwarf_callback_param *param = data;
938 	struct probe_finder *pf = param->data;
939 	struct perf_probe_point *pp = &pf->pev->point;
940 
941 	/* Check tag and diename */
942 	if (!die_is_func_def(sp_die) ||
943 	    !die_match_name(sp_die, pp->function))
944 		return DWARF_CB_OK;
945 
946 	/* Check declared file */
947 	if (pp->file && strtailcmp(pp->file, dwarf_decl_file(sp_die)))
948 		return DWARF_CB_OK;
949 
950 	pr_debug("Matched function: %s\n", dwarf_diename(sp_die));
951 	pf->fname = dwarf_decl_file(sp_die);
952 	if (pp->line) { /* Function relative line */
953 		dwarf_decl_line(sp_die, &pf->lno);
954 		pf->lno += pp->line;
955 		param->retval = find_probe_point_by_line(pf);
956 	} else if (die_is_func_instance(sp_die)) {
957 		/* Instances always have the entry address */
958 		dwarf_entrypc(sp_die, &pf->addr);
959 		/* Real function */
960 		if (pp->lazy_line)
961 			param->retval = find_probe_point_lazy(sp_die, pf);
962 		else {
963 			pf->addr += pp->offset;
964 			/* TODO: Check the address in this function */
965 			param->retval = call_probe_finder(sp_die, pf);
966 		}
967 	} else if (!probe_conf.no_inlines) {
968 		/* Inlined function: search instances */
969 		param->retval = die_walk_instances(sp_die,
970 					probe_point_inline_cb, (void *)pf);
971 		/* This could be a non-existed inline definition */
972 		if (param->retval == -ENOENT && strisglob(pp->function))
973 			param->retval = 0;
974 	}
975 
976 	/* We need to find other candidates */
977 	if (strisglob(pp->function) && param->retval >= 0) {
978 		param->retval = 0;	/* We have to clear the result */
979 		return DWARF_CB_OK;
980 	}
981 
982 	return DWARF_CB_ABORT; /* Exit; no same symbol in this CU. */
983 }
984 
985 static int find_probe_point_by_func(struct probe_finder *pf)
986 {
987 	struct dwarf_callback_param _param = {.data = (void *)pf,
988 					      .retval = 0};
989 	dwarf_getfuncs(&pf->cu_die, probe_point_search_cb, &_param, 0);
990 	return _param.retval;
991 }
992 
993 struct pubname_callback_param {
994 	char *function;
995 	char *file;
996 	Dwarf_Die *cu_die;
997 	Dwarf_Die *sp_die;
998 	int found;
999 };
1000 
1001 static int pubname_search_cb(Dwarf *dbg, Dwarf_Global *gl, void *data)
1002 {
1003 	struct pubname_callback_param *param = data;
1004 
1005 	if (dwarf_offdie(dbg, gl->die_offset, param->sp_die)) {
1006 		if (dwarf_tag(param->sp_die) != DW_TAG_subprogram)
1007 			return DWARF_CB_OK;
1008 
1009 		if (die_match_name(param->sp_die, param->function)) {
1010 			if (!dwarf_offdie(dbg, gl->cu_offset, param->cu_die))
1011 				return DWARF_CB_OK;
1012 
1013 			if (param->file &&
1014 			    strtailcmp(param->file, dwarf_decl_file(param->sp_die)))
1015 				return DWARF_CB_OK;
1016 
1017 			param->found = 1;
1018 			return DWARF_CB_ABORT;
1019 		}
1020 	}
1021 
1022 	return DWARF_CB_OK;
1023 }
1024 
1025 /* Find probe points from debuginfo */
1026 static int debuginfo__find_probes(struct debuginfo *dbg,
1027 				  struct probe_finder *pf)
1028 {
1029 	struct perf_probe_point *pp = &pf->pev->point;
1030 	Dwarf_Off off, noff;
1031 	size_t cuhl;
1032 	Dwarf_Die *diep;
1033 	int ret = 0;
1034 
1035 #if _ELFUTILS_PREREQ(0, 142)
1036 	Elf *elf;
1037 	GElf_Ehdr ehdr;
1038 	GElf_Shdr shdr;
1039 
1040 	/* Get the call frame information from this dwarf */
1041 	elf = dwarf_getelf(dbg->dbg);
1042 	if (elf == NULL)
1043 		return -EINVAL;
1044 
1045 	if (gelf_getehdr(elf, &ehdr) == NULL)
1046 		return -EINVAL;
1047 
1048 	if (elf_section_by_name(elf, &ehdr, &shdr, ".eh_frame", NULL) &&
1049 	    shdr.sh_type == SHT_PROGBITS) {
1050 		pf->cfi = dwarf_getcfi_elf(elf);
1051 	} else {
1052 		pf->cfi = dwarf_getcfi(dbg->dbg);
1053 	}
1054 #endif
1055 
1056 	off = 0;
1057 	pf->lcache = intlist__new(NULL);
1058 	if (!pf->lcache)
1059 		return -ENOMEM;
1060 
1061 	/* Fastpath: lookup by function name from .debug_pubnames section */
1062 	if (pp->function && !strisglob(pp->function)) {
1063 		struct pubname_callback_param pubname_param = {
1064 			.function = pp->function,
1065 			.file	  = pp->file,
1066 			.cu_die	  = &pf->cu_die,
1067 			.sp_die	  = &pf->sp_die,
1068 			.found	  = 0,
1069 		};
1070 		struct dwarf_callback_param probe_param = {
1071 			.data = pf,
1072 		};
1073 
1074 		dwarf_getpubnames(dbg->dbg, pubname_search_cb,
1075 				  &pubname_param, 0);
1076 		if (pubname_param.found) {
1077 			ret = probe_point_search_cb(&pf->sp_die, &probe_param);
1078 			if (ret)
1079 				goto found;
1080 		}
1081 	}
1082 
1083 	/* Loop on CUs (Compilation Unit) */
1084 	while (!dwarf_nextcu(dbg->dbg, off, &noff, &cuhl, NULL, NULL, NULL)) {
1085 		/* Get the DIE(Debugging Information Entry) of this CU */
1086 		diep = dwarf_offdie(dbg->dbg, off + cuhl, &pf->cu_die);
1087 		if (!diep)
1088 			continue;
1089 
1090 		/* Check if target file is included. */
1091 		if (pp->file)
1092 			pf->fname = cu_find_realpath(&pf->cu_die, pp->file);
1093 		else
1094 			pf->fname = NULL;
1095 
1096 		if (!pp->file || pf->fname) {
1097 			if (pp->function)
1098 				ret = find_probe_point_by_func(pf);
1099 			else if (pp->lazy_line)
1100 				ret = find_probe_point_lazy(&pf->cu_die, pf);
1101 			else {
1102 				pf->lno = pp->line;
1103 				ret = find_probe_point_by_line(pf);
1104 			}
1105 			if (ret < 0)
1106 				break;
1107 		}
1108 		off = noff;
1109 	}
1110 
1111 found:
1112 	intlist__delete(pf->lcache);
1113 	pf->lcache = NULL;
1114 
1115 	return ret;
1116 }
1117 
1118 struct local_vars_finder {
1119 	struct probe_finder *pf;
1120 	struct perf_probe_arg *args;
1121 	bool vars;
1122 	int max_args;
1123 	int nargs;
1124 	int ret;
1125 };
1126 
1127 /* Collect available variables in this scope */
1128 static int copy_variables_cb(Dwarf_Die *die_mem, void *data)
1129 {
1130 	struct local_vars_finder *vf = data;
1131 	struct probe_finder *pf = vf->pf;
1132 	int tag;
1133 
1134 	tag = dwarf_tag(die_mem);
1135 	if (tag == DW_TAG_formal_parameter ||
1136 	    (tag == DW_TAG_variable && vf->vars)) {
1137 		if (convert_variable_location(die_mem, vf->pf->addr,
1138 					      vf->pf->fb_ops, &pf->sp_die,
1139 					      NULL) == 0) {
1140 			vf->args[vf->nargs].var = (char *)dwarf_diename(die_mem);
1141 			if (vf->args[vf->nargs].var == NULL) {
1142 				vf->ret = -ENOMEM;
1143 				return DIE_FIND_CB_END;
1144 			}
1145 			pr_debug(" %s", vf->args[vf->nargs].var);
1146 			vf->nargs++;
1147 		}
1148 	}
1149 
1150 	if (dwarf_haspc(die_mem, vf->pf->addr))
1151 		return DIE_FIND_CB_CONTINUE;
1152 	else
1153 		return DIE_FIND_CB_SIBLING;
1154 }
1155 
1156 static int expand_probe_args(Dwarf_Die *sc_die, struct probe_finder *pf,
1157 			     struct perf_probe_arg *args)
1158 {
1159 	Dwarf_Die die_mem;
1160 	int i;
1161 	int n = 0;
1162 	struct local_vars_finder vf = {.pf = pf, .args = args, .vars = false,
1163 				.max_args = MAX_PROBE_ARGS, .ret = 0};
1164 
1165 	for (i = 0; i < pf->pev->nargs; i++) {
1166 		/* var never be NULL */
1167 		if (strcmp(pf->pev->args[i].var, PROBE_ARG_VARS) == 0)
1168 			vf.vars = true;
1169 		else if (strcmp(pf->pev->args[i].var, PROBE_ARG_PARAMS) != 0) {
1170 			/* Copy normal argument */
1171 			args[n] = pf->pev->args[i];
1172 			n++;
1173 			continue;
1174 		}
1175 		pr_debug("Expanding %s into:", pf->pev->args[i].var);
1176 		vf.nargs = n;
1177 		/* Special local variables */
1178 		die_find_child(sc_die, copy_variables_cb, (void *)&vf,
1179 			       &die_mem);
1180 		pr_debug(" (%d)\n", vf.nargs - n);
1181 		if (vf.ret < 0)
1182 			return vf.ret;
1183 		n = vf.nargs;
1184 	}
1185 	return n;
1186 }
1187 
1188 /* Add a found probe point into trace event list */
1189 static int add_probe_trace_event(Dwarf_Die *sc_die, struct probe_finder *pf)
1190 {
1191 	struct trace_event_finder *tf =
1192 			container_of(pf, struct trace_event_finder, pf);
1193 	struct probe_trace_event *tev;
1194 	struct perf_probe_arg *args;
1195 	int ret, i;
1196 
1197 	/* Check number of tevs */
1198 	if (tf->ntevs == tf->max_tevs) {
1199 		pr_warning("Too many( > %d) probe point found.\n",
1200 			   tf->max_tevs);
1201 		return -ERANGE;
1202 	}
1203 	tev = &tf->tevs[tf->ntevs++];
1204 
1205 	/* Trace point should be converted from subprogram DIE */
1206 	ret = convert_to_trace_point(&pf->sp_die, tf->mod, pf->addr,
1207 				     pf->pev->point.retprobe, &tev->point);
1208 	if (ret < 0)
1209 		return ret;
1210 
1211 	tev->point.realname = strdup(dwarf_diename(sc_die));
1212 	if (!tev->point.realname)
1213 		return -ENOMEM;
1214 
1215 	pr_debug("Probe point found: %s+%lu\n", tev->point.symbol,
1216 		 tev->point.offset);
1217 
1218 	/* Expand special probe argument if exist */
1219 	args = zalloc(sizeof(struct perf_probe_arg) * MAX_PROBE_ARGS);
1220 	if (args == NULL)
1221 		return -ENOMEM;
1222 
1223 	ret = expand_probe_args(sc_die, pf, args);
1224 	if (ret < 0)
1225 		goto end;
1226 
1227 	tev->nargs = ret;
1228 	tev->args = zalloc(sizeof(struct probe_trace_arg) * tev->nargs);
1229 	if (tev->args == NULL) {
1230 		ret = -ENOMEM;
1231 		goto end;
1232 	}
1233 
1234 	/* Find each argument */
1235 	for (i = 0; i < tev->nargs; i++) {
1236 		pf->pvar = &args[i];
1237 		pf->tvar = &tev->args[i];
1238 		/* Variable should be found from scope DIE */
1239 		ret = find_variable(sc_die, pf);
1240 		if (ret != 0)
1241 			break;
1242 	}
1243 
1244 end:
1245 	free(args);
1246 	return ret;
1247 }
1248 
1249 /* Find probe_trace_events specified by perf_probe_event from debuginfo */
1250 int debuginfo__find_trace_events(struct debuginfo *dbg,
1251 				 struct perf_probe_event *pev,
1252 				 struct probe_trace_event **tevs)
1253 {
1254 	struct trace_event_finder tf = {
1255 			.pf = {.pev = pev, .callback = add_probe_trace_event},
1256 			.max_tevs = probe_conf.max_probes, .mod = dbg->mod};
1257 	int ret;
1258 
1259 	/* Allocate result tevs array */
1260 	*tevs = zalloc(sizeof(struct probe_trace_event) * tf.max_tevs);
1261 	if (*tevs == NULL)
1262 		return -ENOMEM;
1263 
1264 	tf.tevs = *tevs;
1265 	tf.ntevs = 0;
1266 
1267 	ret = debuginfo__find_probes(dbg, &tf.pf);
1268 	if (ret < 0) {
1269 		zfree(tevs);
1270 		return ret;
1271 	}
1272 
1273 	return (ret < 0) ? ret : tf.ntevs;
1274 }
1275 
1276 /* Collect available variables in this scope */
1277 static int collect_variables_cb(Dwarf_Die *die_mem, void *data)
1278 {
1279 	struct available_var_finder *af = data;
1280 	struct variable_list *vl;
1281 	int tag, ret;
1282 
1283 	vl = &af->vls[af->nvls - 1];
1284 
1285 	tag = dwarf_tag(die_mem);
1286 	if (tag == DW_TAG_formal_parameter ||
1287 	    tag == DW_TAG_variable) {
1288 		ret = convert_variable_location(die_mem, af->pf.addr,
1289 						af->pf.fb_ops, &af->pf.sp_die,
1290 						NULL);
1291 		if (ret == 0 || ret == -ERANGE) {
1292 			int ret2;
1293 			bool externs = !af->child;
1294 			struct strbuf buf;
1295 
1296 			strbuf_init(&buf, 64);
1297 
1298 			if (probe_conf.show_location_range) {
1299 				if (!externs) {
1300 					if (ret)
1301 						strbuf_addf(&buf, "[INV]\t");
1302 					else
1303 						strbuf_addf(&buf, "[VAL]\t");
1304 				} else
1305 					strbuf_addf(&buf, "[EXT]\t");
1306 			}
1307 
1308 			ret2 = die_get_varname(die_mem, &buf);
1309 
1310 			if (!ret2 && probe_conf.show_location_range &&
1311 				!externs) {
1312 				strbuf_addf(&buf, "\t");
1313 				ret2 = die_get_var_range(&af->pf.sp_die,
1314 							die_mem, &buf);
1315 			}
1316 
1317 			pr_debug("Add new var: %s\n", buf.buf);
1318 			if (ret2 == 0) {
1319 				strlist__add(vl->vars,
1320 					strbuf_detach(&buf, NULL));
1321 			}
1322 			strbuf_release(&buf);
1323 		}
1324 	}
1325 
1326 	if (af->child && dwarf_haspc(die_mem, af->pf.addr))
1327 		return DIE_FIND_CB_CONTINUE;
1328 	else
1329 		return DIE_FIND_CB_SIBLING;
1330 }
1331 
1332 /* Add a found vars into available variables list */
1333 static int add_available_vars(Dwarf_Die *sc_die, struct probe_finder *pf)
1334 {
1335 	struct available_var_finder *af =
1336 			container_of(pf, struct available_var_finder, pf);
1337 	struct variable_list *vl;
1338 	Dwarf_Die die_mem;
1339 	int ret;
1340 
1341 	/* Check number of tevs */
1342 	if (af->nvls == af->max_vls) {
1343 		pr_warning("Too many( > %d) probe point found.\n", af->max_vls);
1344 		return -ERANGE;
1345 	}
1346 	vl = &af->vls[af->nvls++];
1347 
1348 	/* Trace point should be converted from subprogram DIE */
1349 	ret = convert_to_trace_point(&pf->sp_die, af->mod, pf->addr,
1350 				     pf->pev->point.retprobe, &vl->point);
1351 	if (ret < 0)
1352 		return ret;
1353 
1354 	pr_debug("Probe point found: %s+%lu\n", vl->point.symbol,
1355 		 vl->point.offset);
1356 
1357 	/* Find local variables */
1358 	vl->vars = strlist__new(true, NULL);
1359 	if (vl->vars == NULL)
1360 		return -ENOMEM;
1361 	af->child = true;
1362 	die_find_child(sc_die, collect_variables_cb, (void *)af, &die_mem);
1363 
1364 	/* Find external variables */
1365 	if (!probe_conf.show_ext_vars)
1366 		goto out;
1367 	/* Don't need to search child DIE for external vars. */
1368 	af->child = false;
1369 	die_find_child(&pf->cu_die, collect_variables_cb, (void *)af, &die_mem);
1370 
1371 out:
1372 	if (strlist__empty(vl->vars)) {
1373 		strlist__delete(vl->vars);
1374 		vl->vars = NULL;
1375 	}
1376 
1377 	return ret;
1378 }
1379 
1380 /*
1381  * Find available variables at given probe point
1382  * Return the number of found probe points. Return 0 if there is no
1383  * matched probe point. Return <0 if an error occurs.
1384  */
1385 int debuginfo__find_available_vars_at(struct debuginfo *dbg,
1386 				      struct perf_probe_event *pev,
1387 				      struct variable_list **vls)
1388 {
1389 	struct available_var_finder af = {
1390 			.pf = {.pev = pev, .callback = add_available_vars},
1391 			.mod = dbg->mod,
1392 			.max_vls = probe_conf.max_probes};
1393 	int ret;
1394 
1395 	/* Allocate result vls array */
1396 	*vls = zalloc(sizeof(struct variable_list) * af.max_vls);
1397 	if (*vls == NULL)
1398 		return -ENOMEM;
1399 
1400 	af.vls = *vls;
1401 	af.nvls = 0;
1402 
1403 	ret = debuginfo__find_probes(dbg, &af.pf);
1404 	if (ret < 0) {
1405 		/* Free vlist for error */
1406 		while (af.nvls--) {
1407 			zfree(&af.vls[af.nvls].point.symbol);
1408 			strlist__delete(af.vls[af.nvls].vars);
1409 		}
1410 		zfree(vls);
1411 		return ret;
1412 	}
1413 
1414 	return (ret < 0) ? ret : af.nvls;
1415 }
1416 
1417 /* Reverse search */
1418 int debuginfo__find_probe_point(struct debuginfo *dbg, unsigned long addr,
1419 				struct perf_probe_point *ppt)
1420 {
1421 	Dwarf_Die cudie, spdie, indie;
1422 	Dwarf_Addr _addr = 0, baseaddr = 0;
1423 	const char *fname = NULL, *func = NULL, *basefunc = NULL, *tmp;
1424 	int baseline = 0, lineno = 0, ret = 0;
1425 
1426 	/* Find cu die */
1427 	if (!dwarf_addrdie(dbg->dbg, (Dwarf_Addr)addr, &cudie)) {
1428 		pr_warning("Failed to find debug information for address %lx\n",
1429 			   addr);
1430 		ret = -EINVAL;
1431 		goto end;
1432 	}
1433 
1434 	/* Find a corresponding line (filename and lineno) */
1435 	cu_find_lineinfo(&cudie, addr, &fname, &lineno);
1436 	/* Don't care whether it failed or not */
1437 
1438 	/* Find a corresponding function (name, baseline and baseaddr) */
1439 	if (die_find_realfunc(&cudie, (Dwarf_Addr)addr, &spdie)) {
1440 		/* Get function entry information */
1441 		func = basefunc = dwarf_diename(&spdie);
1442 		if (!func ||
1443 		    dwarf_entrypc(&spdie, &baseaddr) != 0 ||
1444 		    dwarf_decl_line(&spdie, &baseline) != 0) {
1445 			lineno = 0;
1446 			goto post;
1447 		}
1448 
1449 		fname = dwarf_decl_file(&spdie);
1450 		if (addr == (unsigned long)baseaddr) {
1451 			/* Function entry - Relative line number is 0 */
1452 			lineno = baseline;
1453 			goto post;
1454 		}
1455 
1456 		/* Track down the inline functions step by step */
1457 		while (die_find_top_inlinefunc(&spdie, (Dwarf_Addr)addr,
1458 						&indie)) {
1459 			/* There is an inline function */
1460 			if (dwarf_entrypc(&indie, &_addr) == 0 &&
1461 			    _addr == addr) {
1462 				/*
1463 				 * addr is at an inline function entry.
1464 				 * In this case, lineno should be the call-site
1465 				 * line number. (overwrite lineinfo)
1466 				 */
1467 				lineno = die_get_call_lineno(&indie);
1468 				fname = die_get_call_file(&indie);
1469 				break;
1470 			} else {
1471 				/*
1472 				 * addr is in an inline function body.
1473 				 * Since lineno points one of the lines
1474 				 * of the inline function, baseline should
1475 				 * be the entry line of the inline function.
1476 				 */
1477 				tmp = dwarf_diename(&indie);
1478 				if (!tmp ||
1479 				    dwarf_decl_line(&indie, &baseline) != 0)
1480 					break;
1481 				func = tmp;
1482 				spdie = indie;
1483 			}
1484 		}
1485 		/* Verify the lineno and baseline are in a same file */
1486 		tmp = dwarf_decl_file(&spdie);
1487 		if (!tmp || strcmp(tmp, fname) != 0)
1488 			lineno = 0;
1489 	}
1490 
1491 post:
1492 	/* Make a relative line number or an offset */
1493 	if (lineno)
1494 		ppt->line = lineno - baseline;
1495 	else if (basefunc) {
1496 		ppt->offset = addr - (unsigned long)baseaddr;
1497 		func = basefunc;
1498 	}
1499 
1500 	/* Duplicate strings */
1501 	if (func) {
1502 		ppt->function = strdup(func);
1503 		if (ppt->function == NULL) {
1504 			ret = -ENOMEM;
1505 			goto end;
1506 		}
1507 	}
1508 	if (fname) {
1509 		ppt->file = strdup(fname);
1510 		if (ppt->file == NULL) {
1511 			zfree(&ppt->function);
1512 			ret = -ENOMEM;
1513 			goto end;
1514 		}
1515 	}
1516 end:
1517 	if (ret == 0 && (fname || func))
1518 		ret = 1;	/* Found a point */
1519 	return ret;
1520 }
1521 
1522 /* Add a line and store the src path */
1523 static int line_range_add_line(const char *src, unsigned int lineno,
1524 			       struct line_range *lr)
1525 {
1526 	/* Copy source path */
1527 	if (!lr->path) {
1528 		lr->path = strdup(src);
1529 		if (lr->path == NULL)
1530 			return -ENOMEM;
1531 	}
1532 	return intlist__add(lr->line_list, lineno);
1533 }
1534 
1535 static int line_range_walk_cb(const char *fname, int lineno,
1536 			      Dwarf_Addr addr __maybe_unused,
1537 			      void *data)
1538 {
1539 	struct line_finder *lf = data;
1540 	int err;
1541 
1542 	if ((strtailcmp(fname, lf->fname) != 0) ||
1543 	    (lf->lno_s > lineno || lf->lno_e < lineno))
1544 		return 0;
1545 
1546 	err = line_range_add_line(fname, lineno, lf->lr);
1547 	if (err < 0 && err != -EEXIST)
1548 		return err;
1549 
1550 	return 0;
1551 }
1552 
1553 /* Find line range from its line number */
1554 static int find_line_range_by_line(Dwarf_Die *sp_die, struct line_finder *lf)
1555 {
1556 	int ret;
1557 
1558 	ret = die_walk_lines(sp_die ?: &lf->cu_die, line_range_walk_cb, lf);
1559 
1560 	/* Update status */
1561 	if (ret >= 0)
1562 		if (!intlist__empty(lf->lr->line_list))
1563 			ret = lf->found = 1;
1564 		else
1565 			ret = 0;	/* Lines are not found */
1566 	else {
1567 		zfree(&lf->lr->path);
1568 	}
1569 	return ret;
1570 }
1571 
1572 static int line_range_inline_cb(Dwarf_Die *in_die, void *data)
1573 {
1574 	int ret = find_line_range_by_line(in_die, data);
1575 
1576 	/*
1577 	 * We have to check all instances of inlined function, because
1578 	 * some execution paths can be optimized out depends on the
1579 	 * function argument of instances. However, if an error occurs,
1580 	 * it should be handled by the caller.
1581 	 */
1582 	return ret < 0 ? ret : 0;
1583 }
1584 
1585 /* Search function definition from function name */
1586 static int line_range_search_cb(Dwarf_Die *sp_die, void *data)
1587 {
1588 	struct dwarf_callback_param *param = data;
1589 	struct line_finder *lf = param->data;
1590 	struct line_range *lr = lf->lr;
1591 
1592 	/* Check declared file */
1593 	if (lr->file && strtailcmp(lr->file, dwarf_decl_file(sp_die)))
1594 		return DWARF_CB_OK;
1595 
1596 	if (die_is_func_def(sp_die) &&
1597 	    die_match_name(sp_die, lr->function)) {
1598 		lf->fname = dwarf_decl_file(sp_die);
1599 		dwarf_decl_line(sp_die, &lr->offset);
1600 		pr_debug("fname: %s, lineno:%d\n", lf->fname, lr->offset);
1601 		lf->lno_s = lr->offset + lr->start;
1602 		if (lf->lno_s < 0)	/* Overflow */
1603 			lf->lno_s = INT_MAX;
1604 		lf->lno_e = lr->offset + lr->end;
1605 		if (lf->lno_e < 0)	/* Overflow */
1606 			lf->lno_e = INT_MAX;
1607 		pr_debug("New line range: %d to %d\n", lf->lno_s, lf->lno_e);
1608 		lr->start = lf->lno_s;
1609 		lr->end = lf->lno_e;
1610 		if (!die_is_func_instance(sp_die))
1611 			param->retval = die_walk_instances(sp_die,
1612 						line_range_inline_cb, lf);
1613 		else
1614 			param->retval = find_line_range_by_line(sp_die, lf);
1615 		return DWARF_CB_ABORT;
1616 	}
1617 	return DWARF_CB_OK;
1618 }
1619 
1620 static int find_line_range_by_func(struct line_finder *lf)
1621 {
1622 	struct dwarf_callback_param param = {.data = (void *)lf, .retval = 0};
1623 	dwarf_getfuncs(&lf->cu_die, line_range_search_cb, &param, 0);
1624 	return param.retval;
1625 }
1626 
1627 int debuginfo__find_line_range(struct debuginfo *dbg, struct line_range *lr)
1628 {
1629 	struct line_finder lf = {.lr = lr, .found = 0};
1630 	int ret = 0;
1631 	Dwarf_Off off = 0, noff;
1632 	size_t cuhl;
1633 	Dwarf_Die *diep;
1634 	const char *comp_dir;
1635 
1636 	/* Fastpath: lookup by function name from .debug_pubnames section */
1637 	if (lr->function) {
1638 		struct pubname_callback_param pubname_param = {
1639 			.function = lr->function, .file = lr->file,
1640 			.cu_die = &lf.cu_die, .sp_die = &lf.sp_die, .found = 0};
1641 		struct dwarf_callback_param line_range_param = {
1642 			.data = (void *)&lf, .retval = 0};
1643 
1644 		dwarf_getpubnames(dbg->dbg, pubname_search_cb,
1645 				  &pubname_param, 0);
1646 		if (pubname_param.found) {
1647 			line_range_search_cb(&lf.sp_die, &line_range_param);
1648 			if (lf.found)
1649 				goto found;
1650 		}
1651 	}
1652 
1653 	/* Loop on CUs (Compilation Unit) */
1654 	while (!lf.found && ret >= 0) {
1655 		if (dwarf_nextcu(dbg->dbg, off, &noff, &cuhl,
1656 				 NULL, NULL, NULL) != 0)
1657 			break;
1658 
1659 		/* Get the DIE(Debugging Information Entry) of this CU */
1660 		diep = dwarf_offdie(dbg->dbg, off + cuhl, &lf.cu_die);
1661 		if (!diep)
1662 			continue;
1663 
1664 		/* Check if target file is included. */
1665 		if (lr->file)
1666 			lf.fname = cu_find_realpath(&lf.cu_die, lr->file);
1667 		else
1668 			lf.fname = 0;
1669 
1670 		if (!lr->file || lf.fname) {
1671 			if (lr->function)
1672 				ret = find_line_range_by_func(&lf);
1673 			else {
1674 				lf.lno_s = lr->start;
1675 				lf.lno_e = lr->end;
1676 				ret = find_line_range_by_line(NULL, &lf);
1677 			}
1678 		}
1679 		off = noff;
1680 	}
1681 
1682 found:
1683 	/* Store comp_dir */
1684 	if (lf.found) {
1685 		comp_dir = cu_get_comp_dir(&lf.cu_die);
1686 		if (comp_dir) {
1687 			lr->comp_dir = strdup(comp_dir);
1688 			if (!lr->comp_dir)
1689 				ret = -ENOMEM;
1690 		}
1691 	}
1692 
1693 	pr_debug("path: %s\n", lr->path);
1694 	return (ret < 0) ? ret : lf.found;
1695 }
1696 
1697 /*
1698  * Find a src file from a DWARF tag path. Prepend optional source path prefix
1699  * and chop off leading directories that do not exist. Result is passed back as
1700  * a newly allocated path on success.
1701  * Return 0 if file was found and readable, -errno otherwise.
1702  */
1703 int get_real_path(const char *raw_path, const char *comp_dir,
1704 			 char **new_path)
1705 {
1706 	const char *prefix = symbol_conf.source_prefix;
1707 
1708 	if (!prefix) {
1709 		if (raw_path[0] != '/' && comp_dir)
1710 			/* If not an absolute path, try to use comp_dir */
1711 			prefix = comp_dir;
1712 		else {
1713 			if (access(raw_path, R_OK) == 0) {
1714 				*new_path = strdup(raw_path);
1715 				return *new_path ? 0 : -ENOMEM;
1716 			} else
1717 				return -errno;
1718 		}
1719 	}
1720 
1721 	*new_path = malloc((strlen(prefix) + strlen(raw_path) + 2));
1722 	if (!*new_path)
1723 		return -ENOMEM;
1724 
1725 	for (;;) {
1726 		sprintf(*new_path, "%s/%s", prefix, raw_path);
1727 
1728 		if (access(*new_path, R_OK) == 0)
1729 			return 0;
1730 
1731 		if (!symbol_conf.source_prefix) {
1732 			/* In case of searching comp_dir, don't retry */
1733 			zfree(new_path);
1734 			return -errno;
1735 		}
1736 
1737 		switch (errno) {
1738 		case ENAMETOOLONG:
1739 		case ENOENT:
1740 		case EROFS:
1741 		case EFAULT:
1742 			raw_path = strchr(++raw_path, '/');
1743 			if (!raw_path) {
1744 				zfree(new_path);
1745 				return -ENOENT;
1746 			}
1747 			continue;
1748 
1749 		default:
1750 			zfree(new_path);
1751 			return -errno;
1752 		}
1753 	}
1754 }
1755