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 */
debuginfo__init_offline_dwarf(struct debuginfo * dbg,const char * path)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 dwfl_report_begin(dbg->dwfl);
74 dbg->mod = dwfl_report_offline(dbg->dwfl, "", "", fd);
75 if (!dbg->mod)
76 goto error;
77
78 dbg->dbg = dwfl_module_getdwarf(dbg->mod, &dbg->bias);
79 if (!dbg->dbg)
80 goto error;
81
82 dwfl_report_end(dbg->dwfl, NULL, NULL);
83
84 return 0;
85 error:
86 if (dbg->dwfl)
87 dwfl_end(dbg->dwfl);
88 else
89 close(fd);
90 memset(dbg, 0, sizeof(*dbg));
91
92 return -ENOENT;
93 }
94
__debuginfo__new(const char * path)95 static struct debuginfo *__debuginfo__new(const char *path)
96 {
97 struct debuginfo *dbg = zalloc(sizeof(*dbg));
98 if (!dbg)
99 return NULL;
100
101 if (debuginfo__init_offline_dwarf(dbg, path) < 0)
102 zfree(&dbg);
103 if (dbg)
104 pr_debug("Open Debuginfo file: %s\n", path);
105 return dbg;
106 }
107
108 enum dso_binary_type distro_dwarf_types[] = {
109 DSO_BINARY_TYPE__FEDORA_DEBUGINFO,
110 DSO_BINARY_TYPE__UBUNTU_DEBUGINFO,
111 DSO_BINARY_TYPE__OPENEMBEDDED_DEBUGINFO,
112 DSO_BINARY_TYPE__BUILDID_DEBUGINFO,
113 DSO_BINARY_TYPE__MIXEDUP_UBUNTU_DEBUGINFO,
114 DSO_BINARY_TYPE__NOT_FOUND,
115 };
116
debuginfo__new(const char * path)117 struct debuginfo *debuginfo__new(const char *path)
118 {
119 enum dso_binary_type *type;
120 char buf[PATH_MAX], nil = '\0';
121 struct dso *dso;
122 struct debuginfo *dinfo = NULL;
123
124 /* Try to open distro debuginfo files */
125 dso = dso__new(path);
126 if (!dso)
127 goto out;
128
129 for (type = distro_dwarf_types;
130 !dinfo && *type != DSO_BINARY_TYPE__NOT_FOUND;
131 type++) {
132 if (dso__read_binary_type_filename(dso, *type, &nil,
133 buf, PATH_MAX) < 0)
134 continue;
135 dinfo = __debuginfo__new(buf);
136 }
137 dso__put(dso);
138
139 out:
140 /* if failed to open all distro debuginfo, open given binary */
141 return dinfo ? : __debuginfo__new(path);
142 }
143
debuginfo__delete(struct debuginfo * dbg)144 void debuginfo__delete(struct debuginfo *dbg)
145 {
146 if (dbg) {
147 if (dbg->dwfl)
148 dwfl_end(dbg->dwfl);
149 free(dbg);
150 }
151 }
152
153 /*
154 * Probe finder related functions
155 */
156
alloc_trace_arg_ref(long offs)157 static struct probe_trace_arg_ref *alloc_trace_arg_ref(long offs)
158 {
159 struct probe_trace_arg_ref *ref;
160 ref = zalloc(sizeof(struct probe_trace_arg_ref));
161 if (ref != NULL)
162 ref->offset = offs;
163 return ref;
164 }
165
166 /*
167 * Convert a location into trace_arg.
168 * If tvar == NULL, this just checks variable can be converted.
169 * If fentry == true and vr_die is a parameter, do huristic search
170 * for the location fuzzed by function entry mcount.
171 */
convert_variable_location(Dwarf_Die * vr_die,Dwarf_Addr addr,Dwarf_Op * fb_ops,Dwarf_Die * sp_die,struct probe_trace_arg * tvar)172 static int convert_variable_location(Dwarf_Die *vr_die, Dwarf_Addr addr,
173 Dwarf_Op *fb_ops, Dwarf_Die *sp_die,
174 struct probe_trace_arg *tvar)
175 {
176 Dwarf_Attribute attr;
177 Dwarf_Addr tmp = 0;
178 Dwarf_Op *op;
179 size_t nops;
180 unsigned int regn;
181 Dwarf_Word offs = 0;
182 bool ref = false;
183 const char *regs;
184 int ret, ret2 = 0;
185
186 if (dwarf_attr(vr_die, DW_AT_external, &attr) != NULL)
187 goto static_var;
188
189 /* TODO: handle more than 1 exprs */
190 if (dwarf_attr(vr_die, DW_AT_location, &attr) == NULL)
191 return -EINVAL; /* Broken DIE ? */
192 if (dwarf_getlocation_addr(&attr, addr, &op, &nops, 1) <= 0) {
193 ret = dwarf_entrypc(sp_die, &tmp);
194 if (ret)
195 return -ENOENT;
196
197 if (probe_conf.show_location_range &&
198 (dwarf_tag(vr_die) == DW_TAG_variable)) {
199 ret2 = -ERANGE;
200 } else if (addr != tmp ||
201 dwarf_tag(vr_die) != DW_TAG_formal_parameter) {
202 return -ENOENT;
203 }
204
205 ret = dwarf_highpc(sp_die, &tmp);
206 if (ret)
207 return -ENOENT;
208 /*
209 * This is fuzzed by fentry mcount. We try to find the
210 * parameter location at the earliest address.
211 */
212 for (addr += 1; addr <= tmp; addr++) {
213 if (dwarf_getlocation_addr(&attr, addr, &op,
214 &nops, 1) > 0)
215 goto found;
216 }
217 return -ENOENT;
218 }
219 found:
220 if (nops == 0)
221 /* TODO: Support const_value */
222 return -ENOENT;
223
224 if (op->atom == DW_OP_addr) {
225 static_var:
226 if (!tvar)
227 return ret2;
228 /* Static variables on memory (not stack), make @varname */
229 ret = strlen(dwarf_diename(vr_die));
230 tvar->value = zalloc(ret + 2);
231 if (tvar->value == NULL)
232 return -ENOMEM;
233 snprintf(tvar->value, ret + 2, "@%s", dwarf_diename(vr_die));
234 tvar->ref = alloc_trace_arg_ref((long)offs);
235 if (tvar->ref == NULL)
236 return -ENOMEM;
237 return ret2;
238 }
239
240 /* If this is based on frame buffer, set the offset */
241 if (op->atom == DW_OP_fbreg) {
242 if (fb_ops == NULL)
243 return -ENOTSUP;
244 ref = true;
245 offs = op->number;
246 op = &fb_ops[0];
247 }
248
249 if (op->atom >= DW_OP_breg0 && op->atom <= DW_OP_breg31) {
250 regn = op->atom - DW_OP_breg0;
251 offs += op->number;
252 ref = true;
253 } else if (op->atom >= DW_OP_reg0 && op->atom <= DW_OP_reg31) {
254 regn = op->atom - DW_OP_reg0;
255 } else if (op->atom == DW_OP_bregx) {
256 regn = op->number;
257 offs += op->number2;
258 ref = true;
259 } else if (op->atom == DW_OP_regx) {
260 regn = op->number;
261 } else {
262 pr_debug("DW_OP %x is not supported.\n", op->atom);
263 return -ENOTSUP;
264 }
265
266 if (!tvar)
267 return ret2;
268
269 regs = get_arch_regstr(regn);
270 if (!regs) {
271 /* This should be a bug in DWARF or this tool */
272 pr_warning("Mapping for the register number %u "
273 "missing on this architecture.\n", regn);
274 return -ENOTSUP;
275 }
276
277 tvar->value = strdup(regs);
278 if (tvar->value == NULL)
279 return -ENOMEM;
280
281 if (ref) {
282 tvar->ref = alloc_trace_arg_ref((long)offs);
283 if (tvar->ref == NULL)
284 return -ENOMEM;
285 }
286 return ret2;
287 }
288
289 #define BYTES_TO_BITS(nb) ((nb) * BITS_PER_LONG / sizeof(long))
290
convert_variable_type(Dwarf_Die * vr_die,struct probe_trace_arg * tvar,const char * cast)291 static int convert_variable_type(Dwarf_Die *vr_die,
292 struct probe_trace_arg *tvar,
293 const char *cast)
294 {
295 struct probe_trace_arg_ref **ref_ptr = &tvar->ref;
296 Dwarf_Die type;
297 char buf[16];
298 char sbuf[STRERR_BUFSIZE];
299 int bsize, boffs, total;
300 int ret;
301
302 /* TODO: check all types */
303 if (cast && strcmp(cast, "string") != 0) {
304 /* Non string type is OK */
305 tvar->type = strdup(cast);
306 return (tvar->type == NULL) ? -ENOMEM : 0;
307 }
308
309 bsize = dwarf_bitsize(vr_die);
310 if (bsize > 0) {
311 /* This is a bitfield */
312 boffs = dwarf_bitoffset(vr_die);
313 total = dwarf_bytesize(vr_die);
314 if (boffs < 0 || total < 0)
315 return -ENOENT;
316 ret = snprintf(buf, 16, "b%d@%d/%zd", bsize, boffs,
317 BYTES_TO_BITS(total));
318 goto formatted;
319 }
320
321 if (die_get_real_type(vr_die, &type) == NULL) {
322 pr_warning("Failed to get a type information of %s.\n",
323 dwarf_diename(vr_die));
324 return -ENOENT;
325 }
326
327 pr_debug("%s type is %s.\n",
328 dwarf_diename(vr_die), dwarf_diename(&type));
329
330 if (cast && strcmp(cast, "string") == 0) { /* String type */
331 ret = dwarf_tag(&type);
332 if (ret != DW_TAG_pointer_type &&
333 ret != DW_TAG_array_type) {
334 pr_warning("Failed to cast into string: "
335 "%s(%s) is not a pointer nor array.\n",
336 dwarf_diename(vr_die), dwarf_diename(&type));
337 return -EINVAL;
338 }
339 if (die_get_real_type(&type, &type) == NULL) {
340 pr_warning("Failed to get a type"
341 " information.\n");
342 return -ENOENT;
343 }
344 if (ret == DW_TAG_pointer_type) {
345 while (*ref_ptr)
346 ref_ptr = &(*ref_ptr)->next;
347 /* Add new reference with offset +0 */
348 *ref_ptr = zalloc(sizeof(struct probe_trace_arg_ref));
349 if (*ref_ptr == NULL) {
350 pr_warning("Out of memory error\n");
351 return -ENOMEM;
352 }
353 }
354 if (!die_compare_name(&type, "char") &&
355 !die_compare_name(&type, "unsigned char")) {
356 pr_warning("Failed to cast into string: "
357 "%s is not (unsigned) char *.\n",
358 dwarf_diename(vr_die));
359 return -EINVAL;
360 }
361 tvar->type = strdup(cast);
362 return (tvar->type == NULL) ? -ENOMEM : 0;
363 }
364
365 ret = dwarf_bytesize(&type);
366 if (ret <= 0)
367 /* No size ... try to use default type */
368 return 0;
369 ret = BYTES_TO_BITS(ret);
370
371 /* Check the bitwidth */
372 if (ret > MAX_BASIC_TYPE_BITS) {
373 pr_info("%s exceeds max-bitwidth. Cut down to %d bits.\n",
374 dwarf_diename(&type), MAX_BASIC_TYPE_BITS);
375 ret = MAX_BASIC_TYPE_BITS;
376 }
377 ret = snprintf(buf, 16, "%c%d",
378 die_is_signed_type(&type) ? 's' : 'u', ret);
379
380 formatted:
381 if (ret < 0 || ret >= 16) {
382 if (ret >= 16)
383 ret = -E2BIG;
384 pr_warning("Failed to convert variable type: %s\n",
385 strerror_r(-ret, sbuf, sizeof(sbuf)));
386 return ret;
387 }
388 tvar->type = strdup(buf);
389 if (tvar->type == NULL)
390 return -ENOMEM;
391 return 0;
392 }
393
convert_variable_fields(Dwarf_Die * vr_die,const char * varname,struct perf_probe_arg_field * field,struct probe_trace_arg_ref ** ref_ptr,Dwarf_Die * die_mem)394 static int convert_variable_fields(Dwarf_Die *vr_die, const char *varname,
395 struct perf_probe_arg_field *field,
396 struct probe_trace_arg_ref **ref_ptr,
397 Dwarf_Die *die_mem)
398 {
399 struct probe_trace_arg_ref *ref = *ref_ptr;
400 Dwarf_Die type;
401 Dwarf_Word offs;
402 int ret, tag;
403
404 pr_debug("converting %s in %s\n", field->name, varname);
405 if (die_get_real_type(vr_die, &type) == NULL) {
406 pr_warning("Failed to get the type of %s.\n", varname);
407 return -ENOENT;
408 }
409 pr_debug2("Var real type: (%x)\n", (unsigned)dwarf_dieoffset(&type));
410 tag = dwarf_tag(&type);
411
412 if (field->name[0] == '[' &&
413 (tag == DW_TAG_array_type || tag == DW_TAG_pointer_type)) {
414 if (field->next)
415 /* Save original type for next field */
416 memcpy(die_mem, &type, sizeof(*die_mem));
417 /* Get the type of this array */
418 if (die_get_real_type(&type, &type) == NULL) {
419 pr_warning("Failed to get the type of %s.\n", varname);
420 return -ENOENT;
421 }
422 pr_debug2("Array real type: (%x)\n",
423 (unsigned)dwarf_dieoffset(&type));
424 if (tag == DW_TAG_pointer_type) {
425 ref = zalloc(sizeof(struct probe_trace_arg_ref));
426 if (ref == NULL)
427 return -ENOMEM;
428 if (*ref_ptr)
429 (*ref_ptr)->next = ref;
430 else
431 *ref_ptr = ref;
432 }
433 ref->offset += dwarf_bytesize(&type) * field->index;
434 if (!field->next)
435 /* Save vr_die for converting types */
436 memcpy(die_mem, vr_die, sizeof(*die_mem));
437 goto next;
438 } else if (tag == DW_TAG_pointer_type) {
439 /* Check the pointer and dereference */
440 if (!field->ref) {
441 pr_err("Semantic error: %s must be referred by '->'\n",
442 field->name);
443 return -EINVAL;
444 }
445 /* Get the type pointed by this pointer */
446 if (die_get_real_type(&type, &type) == NULL) {
447 pr_warning("Failed to get the type of %s.\n", varname);
448 return -ENOENT;
449 }
450 /* Verify it is a data structure */
451 tag = dwarf_tag(&type);
452 if (tag != DW_TAG_structure_type && tag != DW_TAG_union_type) {
453 pr_warning("%s is not a data structure nor an union.\n",
454 varname);
455 return -EINVAL;
456 }
457
458 ref = zalloc(sizeof(struct probe_trace_arg_ref));
459 if (ref == NULL)
460 return -ENOMEM;
461 if (*ref_ptr)
462 (*ref_ptr)->next = ref;
463 else
464 *ref_ptr = ref;
465 } else {
466 /* Verify it is a data structure */
467 if (tag != DW_TAG_structure_type && tag != DW_TAG_union_type) {
468 pr_warning("%s is not a data structure nor an union.\n",
469 varname);
470 return -EINVAL;
471 }
472 if (field->name[0] == '[') {
473 pr_err("Semantic error: %s is not a pointer"
474 " nor array.\n", varname);
475 return -EINVAL;
476 }
477 /* While prcessing unnamed field, we don't care about this */
478 if (field->ref && dwarf_diename(vr_die)) {
479 pr_err("Semantic error: %s must be referred by '.'\n",
480 field->name);
481 return -EINVAL;
482 }
483 if (!ref) {
484 pr_warning("Structure on a register is not "
485 "supported yet.\n");
486 return -ENOTSUP;
487 }
488 }
489
490 if (die_find_member(&type, field->name, die_mem) == NULL) {
491 pr_warning("%s(type:%s) has no member %s.\n", varname,
492 dwarf_diename(&type), field->name);
493 return -EINVAL;
494 }
495
496 /* Get the offset of the field */
497 if (tag == DW_TAG_union_type) {
498 offs = 0;
499 } else {
500 ret = die_get_data_member_location(die_mem, &offs);
501 if (ret < 0) {
502 pr_warning("Failed to get the offset of %s.\n",
503 field->name);
504 return ret;
505 }
506 }
507 ref->offset += (long)offs;
508
509 /* If this member is unnamed, we need to reuse this field */
510 if (!dwarf_diename(die_mem))
511 return convert_variable_fields(die_mem, varname, field,
512 &ref, die_mem);
513
514 next:
515 /* Converting next field */
516 if (field->next)
517 return convert_variable_fields(die_mem, field->name,
518 field->next, &ref, die_mem);
519 else
520 return 0;
521 }
522
523 /* Show a variables in kprobe event format */
convert_variable(Dwarf_Die * vr_die,struct probe_finder * pf)524 static int convert_variable(Dwarf_Die *vr_die, struct probe_finder *pf)
525 {
526 Dwarf_Die die_mem;
527 int ret;
528
529 pr_debug("Converting variable %s into trace event.\n",
530 dwarf_diename(vr_die));
531
532 ret = convert_variable_location(vr_die, pf->addr, pf->fb_ops,
533 &pf->sp_die, pf->tvar);
534 if (ret == -ENOENT || ret == -EINVAL) {
535 pr_err("Failed to find the location of the '%s' variable at this address.\n"
536 " Perhaps it has been optimized out.\n"
537 " Use -V with the --range option to show '%s' location range.\n",
538 pf->pvar->var, pf->pvar->var);
539 } else if (ret == -ENOTSUP)
540 pr_err("Sorry, we don't support this variable location yet.\n");
541 else if (ret == 0 && pf->pvar->field) {
542 ret = convert_variable_fields(vr_die, pf->pvar->var,
543 pf->pvar->field, &pf->tvar->ref,
544 &die_mem);
545 vr_die = &die_mem;
546 }
547 if (ret == 0)
548 ret = convert_variable_type(vr_die, pf->tvar, pf->pvar->type);
549 /* *expr will be cached in libdw. Don't free it. */
550 return ret;
551 }
552
553 /* Find a variable in a scope DIE */
find_variable(Dwarf_Die * sc_die,struct probe_finder * pf)554 static int find_variable(Dwarf_Die *sc_die, struct probe_finder *pf)
555 {
556 Dwarf_Die vr_die;
557 char buf[32], *ptr;
558 int ret = 0;
559
560 /* Copy raw parameters */
561 if (!is_c_varname(pf->pvar->var))
562 return copy_to_probe_trace_arg(pf->tvar, pf->pvar);
563
564 if (pf->pvar->name)
565 pf->tvar->name = strdup(pf->pvar->name);
566 else {
567 ret = synthesize_perf_probe_arg(pf->pvar, buf, 32);
568 if (ret < 0)
569 return ret;
570 ptr = strchr(buf, ':'); /* Change type separator to _ */
571 if (ptr)
572 *ptr = '_';
573 pf->tvar->name = strdup(buf);
574 }
575 if (pf->tvar->name == NULL)
576 return -ENOMEM;
577
578 pr_debug("Searching '%s' variable in context.\n", pf->pvar->var);
579 /* Search child die for local variables and parameters. */
580 if (!die_find_variable_at(sc_die, pf->pvar->var, pf->addr, &vr_die)) {
581 /* Search again in global variables */
582 if (!die_find_variable_at(&pf->cu_die, pf->pvar->var,
583 0, &vr_die)) {
584 pr_warning("Failed to find '%s' in this function.\n",
585 pf->pvar->var);
586 ret = -ENOENT;
587 }
588 }
589 if (ret >= 0)
590 ret = convert_variable(&vr_die, pf);
591
592 return ret;
593 }
594
595 /* Convert subprogram DIE to trace point */
convert_to_trace_point(Dwarf_Die * sp_die,Dwfl_Module * mod,Dwarf_Addr paddr,bool retprobe,const char * function,struct probe_trace_point * tp)596 static int convert_to_trace_point(Dwarf_Die *sp_die, Dwfl_Module *mod,
597 Dwarf_Addr paddr, bool retprobe,
598 const char *function,
599 struct probe_trace_point *tp)
600 {
601 Dwarf_Addr eaddr;
602 GElf_Sym sym;
603 const char *symbol;
604
605 /* Verify the address is correct */
606 if (!dwarf_haspc(sp_die, paddr)) {
607 pr_warning("Specified offset is out of %s\n",
608 dwarf_diename(sp_die));
609 return -EINVAL;
610 }
611
612 if (dwarf_entrypc(sp_die, &eaddr) == 0) {
613 /* If the DIE has entrypc, use it. */
614 symbol = dwarf_diename(sp_die);
615 } else {
616 /* Try to get actual symbol name and address from symtab */
617 symbol = dwfl_module_addrsym(mod, paddr, &sym, NULL);
618 eaddr = sym.st_value;
619 }
620 if (!symbol) {
621 pr_warning("Failed to find symbol at 0x%lx\n",
622 (unsigned long)paddr);
623 return -ENOENT;
624 }
625
626 tp->offset = (unsigned long)(paddr - eaddr);
627 tp->address = (unsigned long)paddr;
628 tp->symbol = strdup(symbol);
629 if (!tp->symbol)
630 return -ENOMEM;
631
632 /* Return probe must be on the head of a subprogram */
633 if (retprobe) {
634 if (eaddr != paddr) {
635 pr_warning("Failed to find \"%s%%return\",\n"
636 " because %s is an inlined function and"
637 " has no return point.\n", function,
638 function);
639 return -EINVAL;
640 }
641 tp->retprobe = true;
642 }
643
644 return 0;
645 }
646
647 /* Call probe_finder callback with scope DIE */
call_probe_finder(Dwarf_Die * sc_die,struct probe_finder * pf)648 static int call_probe_finder(Dwarf_Die *sc_die, struct probe_finder *pf)
649 {
650 Dwarf_Attribute fb_attr;
651 size_t nops;
652 int ret;
653
654 if (!sc_die) {
655 pr_err("Caller must pass a scope DIE. Program error.\n");
656 return -EINVAL;
657 }
658
659 /* If not a real subprogram, find a real one */
660 if (!die_is_func_def(sc_die)) {
661 if (!die_find_realfunc(&pf->cu_die, pf->addr, &pf->sp_die)) {
662 if (die_find_tailfunc(&pf->cu_die, pf->addr, &pf->sp_die)) {
663 pr_warning("Ignoring tail call from %s\n",
664 dwarf_diename(&pf->sp_die));
665 return 0;
666 } else {
667 pr_warning("Failed to find probe point in any "
668 "functions.\n");
669 return -ENOENT;
670 }
671 }
672 } else
673 memcpy(&pf->sp_die, sc_die, sizeof(Dwarf_Die));
674
675 /* Get the frame base attribute/ops from subprogram */
676 dwarf_attr(&pf->sp_die, DW_AT_frame_base, &fb_attr);
677 ret = dwarf_getlocation_addr(&fb_attr, pf->addr, &pf->fb_ops, &nops, 1);
678 if (ret <= 0 || nops == 0) {
679 pf->fb_ops = NULL;
680 #if _ELFUTILS_PREREQ(0, 142)
681 } else if (nops == 1 && pf->fb_ops[0].atom == DW_OP_call_frame_cfa &&
682 pf->cfi != NULL) {
683 Dwarf_Frame *frame;
684 if (dwarf_cfi_addrframe(pf->cfi, pf->addr, &frame) != 0 ||
685 dwarf_frame_cfa(frame, &pf->fb_ops, &nops) != 0) {
686 pr_warning("Failed to get call frame on 0x%jx\n",
687 (uintmax_t)pf->addr);
688 return -ENOENT;
689 }
690 #endif
691 }
692
693 /* Call finder's callback handler */
694 ret = pf->callback(sc_die, pf);
695
696 /* *pf->fb_ops will be cached in libdw. Don't free it. */
697 pf->fb_ops = NULL;
698
699 return ret;
700 }
701
702 struct find_scope_param {
703 const char *function;
704 const char *file;
705 int line;
706 int diff;
707 Dwarf_Die *die_mem;
708 bool found;
709 };
710
find_best_scope_cb(Dwarf_Die * fn_die,void * data)711 static int find_best_scope_cb(Dwarf_Die *fn_die, void *data)
712 {
713 struct find_scope_param *fsp = data;
714 const char *file;
715 int lno;
716
717 /* Skip if declared file name does not match */
718 if (fsp->file) {
719 file = dwarf_decl_file(fn_die);
720 if (!file || strcmp(fsp->file, file) != 0)
721 return 0;
722 }
723 /* If the function name is given, that's what user expects */
724 if (fsp->function) {
725 if (die_match_name(fn_die, fsp->function)) {
726 memcpy(fsp->die_mem, fn_die, sizeof(Dwarf_Die));
727 fsp->found = true;
728 return 1;
729 }
730 } else {
731 /* With the line number, find the nearest declared DIE */
732 dwarf_decl_line(fn_die, &lno);
733 if (lno < fsp->line && fsp->diff > fsp->line - lno) {
734 /* Keep a candidate and continue */
735 fsp->diff = fsp->line - lno;
736 memcpy(fsp->die_mem, fn_die, sizeof(Dwarf_Die));
737 fsp->found = true;
738 }
739 }
740 return 0;
741 }
742
743 /* Return innermost DIE */
find_inner_scope_cb(Dwarf_Die * fn_die,void * data)744 static int find_inner_scope_cb(Dwarf_Die *fn_die, void *data)
745 {
746 struct find_scope_param *fsp = data;
747
748 memcpy(fsp->die_mem, fn_die, sizeof(Dwarf_Die));
749 fsp->found = true;
750 return 1;
751 }
752
753 /* Find an appropriate scope fits to given conditions */
find_best_scope(struct probe_finder * pf,Dwarf_Die * die_mem)754 static Dwarf_Die *find_best_scope(struct probe_finder *pf, Dwarf_Die *die_mem)
755 {
756 struct find_scope_param fsp = {
757 .function = pf->pev->point.function,
758 .file = pf->fname,
759 .line = pf->lno,
760 .diff = INT_MAX,
761 .die_mem = die_mem,
762 .found = false,
763 };
764 int ret;
765
766 ret = cu_walk_functions_at(&pf->cu_die, pf->addr, find_best_scope_cb,
767 &fsp);
768 if (!ret && !fsp.found)
769 cu_walk_functions_at(&pf->cu_die, pf->addr,
770 find_inner_scope_cb, &fsp);
771
772 return fsp.found ? die_mem : NULL;
773 }
774
probe_point_line_walker(const char * fname,int lineno,Dwarf_Addr addr,void * data)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 */
find_probe_point_by_line(struct probe_finder * pf)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 */
find_lazy_match_lines(struct intlist * list,const char * fname,const char * pat)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
probe_point_lazy_walker(const char * fname,int lineno,Dwarf_Addr addr,void * data)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 */
find_probe_point_lazy(Dwarf_Die * sp_die,struct probe_finder * pf)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
probe_point_inline_cb(Dwarf_Die * in_die,void * data)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 (die_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 */
probe_point_search_cb(Dwarf_Die * sp_die,void * data)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
find_probe_point_by_func(struct probe_finder * pf)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
pubname_search_cb(Dwarf * dbg,Dwarf_Global * gl,void * data)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 */
debuginfo__find_probes(struct debuginfo * dbg,struct probe_finder * pf)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 */
copy_variables_cb(Dwarf_Die * die_mem,void * data)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
expand_probe_args(Dwarf_Die * sc_die,struct probe_finder * pf,struct perf_probe_arg * args)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 */
add_probe_trace_event(Dwarf_Die * sc_die,struct probe_finder * pf)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 perf_probe_point *pp = &pf->pev->point;
1194 struct probe_trace_event *tev;
1195 struct perf_probe_arg *args = NULL;
1196 int ret, i;
1197
1198 /* Check number of tevs */
1199 if (tf->ntevs == tf->max_tevs) {
1200 pr_warning("Too many( > %d) probe point found.\n",
1201 tf->max_tevs);
1202 return -ERANGE;
1203 }
1204 tev = &tf->tevs[tf->ntevs++];
1205
1206 /* Trace point should be converted from subprogram DIE */
1207 ret = convert_to_trace_point(&pf->sp_die, tf->mod, pf->addr,
1208 pp->retprobe, pp->function, &tev->point);
1209 if (ret < 0)
1210 goto end;
1211
1212 tev->point.realname = strdup(dwarf_diename(sc_die));
1213 if (!tev->point.realname) {
1214 ret = -ENOMEM;
1215 goto end;
1216 }
1217
1218 pr_debug("Probe point found: %s+%lu\n", tev->point.symbol,
1219 tev->point.offset);
1220
1221 /* Expand special probe argument if exist */
1222 args = zalloc(sizeof(struct perf_probe_arg) * MAX_PROBE_ARGS);
1223 if (args == NULL) {
1224 ret = -ENOMEM;
1225 goto end;
1226 }
1227
1228 ret = expand_probe_args(sc_die, pf, args);
1229 if (ret < 0)
1230 goto end;
1231
1232 tev->nargs = ret;
1233 tev->args = zalloc(sizeof(struct probe_trace_arg) * tev->nargs);
1234 if (tev->args == NULL) {
1235 ret = -ENOMEM;
1236 goto end;
1237 }
1238
1239 /* Find each argument */
1240 for (i = 0; i < tev->nargs; i++) {
1241 pf->pvar = &args[i];
1242 pf->tvar = &tev->args[i];
1243 /* Variable should be found from scope DIE */
1244 ret = find_variable(sc_die, pf);
1245 if (ret != 0)
1246 break;
1247 }
1248
1249 end:
1250 if (ret) {
1251 clear_probe_trace_event(tev);
1252 tf->ntevs--;
1253 }
1254 free(args);
1255 return ret;
1256 }
1257
1258 /* Find probe_trace_events specified by perf_probe_event from debuginfo */
debuginfo__find_trace_events(struct debuginfo * dbg,struct perf_probe_event * pev,struct probe_trace_event ** tevs)1259 int debuginfo__find_trace_events(struct debuginfo *dbg,
1260 struct perf_probe_event *pev,
1261 struct probe_trace_event **tevs)
1262 {
1263 struct trace_event_finder tf = {
1264 .pf = {.pev = pev, .callback = add_probe_trace_event},
1265 .max_tevs = probe_conf.max_probes, .mod = dbg->mod};
1266 int ret, i;
1267
1268 /* Allocate result tevs array */
1269 *tevs = zalloc(sizeof(struct probe_trace_event) * tf.max_tevs);
1270 if (*tevs == NULL)
1271 return -ENOMEM;
1272
1273 tf.tevs = *tevs;
1274 tf.ntevs = 0;
1275
1276 ret = debuginfo__find_probes(dbg, &tf.pf);
1277 if (ret < 0 || tf.ntevs == 0) {
1278 for (i = 0; i < tf.ntevs; i++)
1279 clear_probe_trace_event(&tf.tevs[i]);
1280 zfree(tevs);
1281 return ret;
1282 }
1283
1284 return (ret < 0) ? ret : tf.ntevs;
1285 }
1286
1287 /* Collect available variables in this scope */
collect_variables_cb(Dwarf_Die * die_mem,void * data)1288 static int collect_variables_cb(Dwarf_Die *die_mem, void *data)
1289 {
1290 struct available_var_finder *af = data;
1291 struct variable_list *vl;
1292 int tag, ret;
1293
1294 vl = &af->vls[af->nvls - 1];
1295
1296 tag = dwarf_tag(die_mem);
1297 if (tag == DW_TAG_formal_parameter ||
1298 tag == DW_TAG_variable) {
1299 ret = convert_variable_location(die_mem, af->pf.addr,
1300 af->pf.fb_ops, &af->pf.sp_die,
1301 NULL);
1302 if (ret == 0 || ret == -ERANGE) {
1303 int ret2;
1304 bool externs = !af->child;
1305 struct strbuf buf;
1306
1307 strbuf_init(&buf, 64);
1308
1309 if (probe_conf.show_location_range) {
1310 if (!externs) {
1311 if (ret)
1312 strbuf_addf(&buf, "[INV]\t");
1313 else
1314 strbuf_addf(&buf, "[VAL]\t");
1315 } else
1316 strbuf_addf(&buf, "[EXT]\t");
1317 }
1318
1319 ret2 = die_get_varname(die_mem, &buf);
1320
1321 if (!ret2 && probe_conf.show_location_range &&
1322 !externs) {
1323 strbuf_addf(&buf, "\t");
1324 ret2 = die_get_var_range(&af->pf.sp_die,
1325 die_mem, &buf);
1326 }
1327
1328 pr_debug("Add new var: %s\n", buf.buf);
1329 if (ret2 == 0) {
1330 strlist__add(vl->vars,
1331 strbuf_detach(&buf, NULL));
1332 }
1333 strbuf_release(&buf);
1334 }
1335 }
1336
1337 if (af->child && dwarf_haspc(die_mem, af->pf.addr))
1338 return DIE_FIND_CB_CONTINUE;
1339 else
1340 return DIE_FIND_CB_SIBLING;
1341 }
1342
available_var_finder_overlap(struct available_var_finder * af)1343 static bool available_var_finder_overlap(struct available_var_finder *af)
1344 {
1345 int i;
1346
1347 for (i = 0; i < af->nvls; i++) {
1348 if (af->pf.addr == af->vls[i].point.address)
1349 return true;
1350 }
1351 return false;
1352
1353 }
1354
1355 /* Add a found vars into available variables list */
add_available_vars(Dwarf_Die * sc_die,struct probe_finder * pf)1356 static int add_available_vars(Dwarf_Die *sc_die, struct probe_finder *pf)
1357 {
1358 struct available_var_finder *af =
1359 container_of(pf, struct available_var_finder, pf);
1360 struct perf_probe_point *pp = &pf->pev->point;
1361 struct variable_list *vl;
1362 Dwarf_Die die_mem;
1363 int ret;
1364
1365 /*
1366 * For some reason (e.g. different column assigned to same address),
1367 * this callback can be called with the address which already passed.
1368 * Ignore it first.
1369 */
1370 if (available_var_finder_overlap(af))
1371 return 0;
1372
1373 /* Check number of tevs */
1374 if (af->nvls == af->max_vls) {
1375 pr_warning("Too many( > %d) probe point found.\n", af->max_vls);
1376 return -ERANGE;
1377 }
1378 vl = &af->vls[af->nvls++];
1379
1380 /* Trace point should be converted from subprogram DIE */
1381 ret = convert_to_trace_point(&pf->sp_die, af->mod, pf->addr,
1382 pp->retprobe, pp->function, &vl->point);
1383 if (ret < 0)
1384 return ret;
1385
1386 pr_debug("Probe point found: %s+%lu\n", vl->point.symbol,
1387 vl->point.offset);
1388
1389 /* Find local variables */
1390 vl->vars = strlist__new(NULL, NULL);
1391 if (vl->vars == NULL)
1392 return -ENOMEM;
1393 af->child = true;
1394 die_find_child(sc_die, collect_variables_cb, (void *)af, &die_mem);
1395
1396 /* Find external variables */
1397 if (!probe_conf.show_ext_vars)
1398 goto out;
1399 /* Don't need to search child DIE for external vars. */
1400 af->child = false;
1401 die_find_child(&pf->cu_die, collect_variables_cb, (void *)af, &die_mem);
1402
1403 out:
1404 if (strlist__empty(vl->vars)) {
1405 strlist__delete(vl->vars);
1406 vl->vars = NULL;
1407 }
1408
1409 return ret;
1410 }
1411
1412 /*
1413 * Find available variables at given probe point
1414 * Return the number of found probe points. Return 0 if there is no
1415 * matched probe point. Return <0 if an error occurs.
1416 */
debuginfo__find_available_vars_at(struct debuginfo * dbg,struct perf_probe_event * pev,struct variable_list ** vls)1417 int debuginfo__find_available_vars_at(struct debuginfo *dbg,
1418 struct perf_probe_event *pev,
1419 struct variable_list **vls)
1420 {
1421 struct available_var_finder af = {
1422 .pf = {.pev = pev, .callback = add_available_vars},
1423 .mod = dbg->mod,
1424 .max_vls = probe_conf.max_probes};
1425 int ret;
1426
1427 /* Allocate result vls array */
1428 *vls = zalloc(sizeof(struct variable_list) * af.max_vls);
1429 if (*vls == NULL)
1430 return -ENOMEM;
1431
1432 af.vls = *vls;
1433 af.nvls = 0;
1434
1435 ret = debuginfo__find_probes(dbg, &af.pf);
1436 if (ret < 0) {
1437 /* Free vlist for error */
1438 while (af.nvls--) {
1439 zfree(&af.vls[af.nvls].point.symbol);
1440 strlist__delete(af.vls[af.nvls].vars);
1441 }
1442 zfree(vls);
1443 return ret;
1444 }
1445
1446 return (ret < 0) ? ret : af.nvls;
1447 }
1448
1449 /* For the kernel module, we need a special code to get a DIE */
debuginfo__get_text_offset(struct debuginfo * dbg,Dwarf_Addr * offs)1450 static int debuginfo__get_text_offset(struct debuginfo *dbg, Dwarf_Addr *offs)
1451 {
1452 int n, i;
1453 Elf32_Word shndx;
1454 Elf_Scn *scn;
1455 Elf *elf;
1456 GElf_Shdr mem, *shdr;
1457 const char *p;
1458
1459 elf = dwfl_module_getelf(dbg->mod, &dbg->bias);
1460 if (!elf)
1461 return -EINVAL;
1462
1463 /* Get the number of relocations */
1464 n = dwfl_module_relocations(dbg->mod);
1465 if (n < 0)
1466 return -ENOENT;
1467 /* Search the relocation related .text section */
1468 for (i = 0; i < n; i++) {
1469 p = dwfl_module_relocation_info(dbg->mod, i, &shndx);
1470 if (strcmp(p, ".text") == 0) {
1471 /* OK, get the section header */
1472 scn = elf_getscn(elf, shndx);
1473 if (!scn)
1474 return -ENOENT;
1475 shdr = gelf_getshdr(scn, &mem);
1476 if (!shdr)
1477 return -ENOENT;
1478 *offs = shdr->sh_addr;
1479 }
1480 }
1481 return 0;
1482 }
1483
1484 /* Reverse search */
debuginfo__find_probe_point(struct debuginfo * dbg,unsigned long addr,struct perf_probe_point * ppt)1485 int debuginfo__find_probe_point(struct debuginfo *dbg, unsigned long addr,
1486 struct perf_probe_point *ppt)
1487 {
1488 Dwarf_Die cudie, spdie, indie;
1489 Dwarf_Addr _addr = 0, baseaddr = 0;
1490 const char *fname = NULL, *func = NULL, *basefunc = NULL, *tmp;
1491 int baseline = 0, lineno = 0, ret = 0;
1492
1493 /* We always need to relocate the address for aranges */
1494 if (debuginfo__get_text_offset(dbg, &baseaddr) == 0)
1495 addr += baseaddr;
1496 /* Find cu die */
1497 if (!dwarf_addrdie(dbg->dbg, (Dwarf_Addr)addr, &cudie)) {
1498 pr_warning("Failed to find debug information for address %lx\n",
1499 addr);
1500 ret = -EINVAL;
1501 goto end;
1502 }
1503
1504 /* Find a corresponding line (filename and lineno) */
1505 cu_find_lineinfo(&cudie, addr, &fname, &lineno);
1506 /* Don't care whether it failed or not */
1507
1508 /* Find a corresponding function (name, baseline and baseaddr) */
1509 if (die_find_realfunc(&cudie, (Dwarf_Addr)addr, &spdie)) {
1510 /* Get function entry information */
1511 func = basefunc = dwarf_diename(&spdie);
1512 if (!func ||
1513 die_entrypc(&spdie, &baseaddr) != 0 ||
1514 dwarf_decl_line(&spdie, &baseline) != 0) {
1515 lineno = 0;
1516 goto post;
1517 }
1518
1519 fname = dwarf_decl_file(&spdie);
1520 if (addr == (unsigned long)baseaddr) {
1521 /* Function entry - Relative line number is 0 */
1522 lineno = baseline;
1523 goto post;
1524 }
1525
1526 /* Track down the inline functions step by step */
1527 while (die_find_top_inlinefunc(&spdie, (Dwarf_Addr)addr,
1528 &indie)) {
1529 /* There is an inline function */
1530 if (die_entrypc(&indie, &_addr) == 0 &&
1531 _addr == addr) {
1532 /*
1533 * addr is at an inline function entry.
1534 * In this case, lineno should be the call-site
1535 * line number. (overwrite lineinfo)
1536 */
1537 lineno = die_get_call_lineno(&indie);
1538 fname = die_get_call_file(&indie);
1539 break;
1540 } else {
1541 /*
1542 * addr is in an inline function body.
1543 * Since lineno points one of the lines
1544 * of the inline function, baseline should
1545 * be the entry line of the inline function.
1546 */
1547 tmp = dwarf_diename(&indie);
1548 if (!tmp ||
1549 dwarf_decl_line(&indie, &baseline) != 0)
1550 break;
1551 func = tmp;
1552 spdie = indie;
1553 }
1554 }
1555 /* Verify the lineno and baseline are in a same file */
1556 tmp = dwarf_decl_file(&spdie);
1557 if (!tmp || strcmp(tmp, fname) != 0)
1558 lineno = 0;
1559 }
1560
1561 post:
1562 /* Make a relative line number or an offset */
1563 if (lineno)
1564 ppt->line = lineno - baseline;
1565 else if (basefunc) {
1566 ppt->offset = addr - (unsigned long)baseaddr;
1567 func = basefunc;
1568 }
1569
1570 /* Duplicate strings */
1571 if (func) {
1572 ppt->function = strdup(func);
1573 if (ppt->function == NULL) {
1574 ret = -ENOMEM;
1575 goto end;
1576 }
1577 }
1578 if (fname) {
1579 ppt->file = strdup(fname);
1580 if (ppt->file == NULL) {
1581 zfree(&ppt->function);
1582 ret = -ENOMEM;
1583 goto end;
1584 }
1585 }
1586 end:
1587 if (ret == 0 && (fname || func))
1588 ret = 1; /* Found a point */
1589 return ret;
1590 }
1591
1592 /* Add a line and store the src path */
line_range_add_line(const char * src,unsigned int lineno,struct line_range * lr)1593 static int line_range_add_line(const char *src, unsigned int lineno,
1594 struct line_range *lr)
1595 {
1596 /* Copy source path */
1597 if (!lr->path) {
1598 lr->path = strdup(src);
1599 if (lr->path == NULL)
1600 return -ENOMEM;
1601 }
1602 return intlist__add(lr->line_list, lineno);
1603 }
1604
line_range_walk_cb(const char * fname,int lineno,Dwarf_Addr addr __maybe_unused,void * data)1605 static int line_range_walk_cb(const char *fname, int lineno,
1606 Dwarf_Addr addr __maybe_unused,
1607 void *data)
1608 {
1609 struct line_finder *lf = data;
1610 int err;
1611
1612 if ((strtailcmp(fname, lf->fname) != 0) ||
1613 (lf->lno_s > lineno || lf->lno_e < lineno))
1614 return 0;
1615
1616 err = line_range_add_line(fname, lineno, lf->lr);
1617 if (err < 0 && err != -EEXIST)
1618 return err;
1619
1620 return 0;
1621 }
1622
1623 /* Find line range from its line number */
find_line_range_by_line(Dwarf_Die * sp_die,struct line_finder * lf)1624 static int find_line_range_by_line(Dwarf_Die *sp_die, struct line_finder *lf)
1625 {
1626 int ret;
1627
1628 ret = die_walk_lines(sp_die ?: &lf->cu_die, line_range_walk_cb, lf);
1629
1630 /* Update status */
1631 if (ret >= 0)
1632 if (!intlist__empty(lf->lr->line_list))
1633 ret = lf->found = 1;
1634 else
1635 ret = 0; /* Lines are not found */
1636 else {
1637 zfree(&lf->lr->path);
1638 }
1639 return ret;
1640 }
1641
line_range_inline_cb(Dwarf_Die * in_die,void * data)1642 static int line_range_inline_cb(Dwarf_Die *in_die, void *data)
1643 {
1644 int ret = find_line_range_by_line(in_die, data);
1645
1646 /*
1647 * We have to check all instances of inlined function, because
1648 * some execution paths can be optimized out depends on the
1649 * function argument of instances. However, if an error occurs,
1650 * it should be handled by the caller.
1651 */
1652 return ret < 0 ? ret : 0;
1653 }
1654
1655 /* Search function definition from function name */
line_range_search_cb(Dwarf_Die * sp_die,void * data)1656 static int line_range_search_cb(Dwarf_Die *sp_die, void *data)
1657 {
1658 struct dwarf_callback_param *param = data;
1659 struct line_finder *lf = param->data;
1660 struct line_range *lr = lf->lr;
1661
1662 /* Check declared file */
1663 if (lr->file && strtailcmp(lr->file, dwarf_decl_file(sp_die)))
1664 return DWARF_CB_OK;
1665
1666 if (die_is_func_def(sp_die) &&
1667 die_match_name(sp_die, lr->function)) {
1668 lf->fname = dwarf_decl_file(sp_die);
1669 dwarf_decl_line(sp_die, &lr->offset);
1670 pr_debug("fname: %s, lineno:%d\n", lf->fname, lr->offset);
1671 lf->lno_s = lr->offset + lr->start;
1672 if (lf->lno_s < 0) /* Overflow */
1673 lf->lno_s = INT_MAX;
1674 lf->lno_e = lr->offset + lr->end;
1675 if (lf->lno_e < 0) /* Overflow */
1676 lf->lno_e = INT_MAX;
1677 pr_debug("New line range: %d to %d\n", lf->lno_s, lf->lno_e);
1678 lr->start = lf->lno_s;
1679 lr->end = lf->lno_e;
1680 if (!die_is_func_instance(sp_die))
1681 param->retval = die_walk_instances(sp_die,
1682 line_range_inline_cb, lf);
1683 else
1684 param->retval = find_line_range_by_line(sp_die, lf);
1685 return DWARF_CB_ABORT;
1686 }
1687 return DWARF_CB_OK;
1688 }
1689
find_line_range_by_func(struct line_finder * lf)1690 static int find_line_range_by_func(struct line_finder *lf)
1691 {
1692 struct dwarf_callback_param param = {.data = (void *)lf, .retval = 0};
1693 dwarf_getfuncs(&lf->cu_die, line_range_search_cb, ¶m, 0);
1694 return param.retval;
1695 }
1696
debuginfo__find_line_range(struct debuginfo * dbg,struct line_range * lr)1697 int debuginfo__find_line_range(struct debuginfo *dbg, struct line_range *lr)
1698 {
1699 struct line_finder lf = {.lr = lr, .found = 0};
1700 int ret = 0;
1701 Dwarf_Off off = 0, noff;
1702 size_t cuhl;
1703 Dwarf_Die *diep;
1704 const char *comp_dir;
1705
1706 /* Fastpath: lookup by function name from .debug_pubnames section */
1707 if (lr->function) {
1708 struct pubname_callback_param pubname_param = {
1709 .function = lr->function, .file = lr->file,
1710 .cu_die = &lf.cu_die, .sp_die = &lf.sp_die, .found = 0};
1711 struct dwarf_callback_param line_range_param = {
1712 .data = (void *)&lf, .retval = 0};
1713
1714 dwarf_getpubnames(dbg->dbg, pubname_search_cb,
1715 &pubname_param, 0);
1716 if (pubname_param.found) {
1717 line_range_search_cb(&lf.sp_die, &line_range_param);
1718 if (lf.found)
1719 goto found;
1720 }
1721 }
1722
1723 /* Loop on CUs (Compilation Unit) */
1724 while (!lf.found && ret >= 0) {
1725 if (dwarf_nextcu(dbg->dbg, off, &noff, &cuhl,
1726 NULL, NULL, NULL) != 0)
1727 break;
1728
1729 /* Get the DIE(Debugging Information Entry) of this CU */
1730 diep = dwarf_offdie(dbg->dbg, off + cuhl, &lf.cu_die);
1731 if (!diep)
1732 continue;
1733
1734 /* Check if target file is included. */
1735 if (lr->file)
1736 lf.fname = cu_find_realpath(&lf.cu_die, lr->file);
1737 else
1738 lf.fname = 0;
1739
1740 if (!lr->file || lf.fname) {
1741 if (lr->function)
1742 ret = find_line_range_by_func(&lf);
1743 else {
1744 lf.lno_s = lr->start;
1745 lf.lno_e = lr->end;
1746 ret = find_line_range_by_line(NULL, &lf);
1747 }
1748 }
1749 off = noff;
1750 }
1751
1752 found:
1753 /* Store comp_dir */
1754 if (lf.found) {
1755 comp_dir = cu_get_comp_dir(&lf.cu_die);
1756 if (comp_dir) {
1757 lr->comp_dir = strdup(comp_dir);
1758 if (!lr->comp_dir)
1759 ret = -ENOMEM;
1760 }
1761 }
1762
1763 pr_debug("path: %s\n", lr->path);
1764 return (ret < 0) ? ret : lf.found;
1765 }
1766
1767 /*
1768 * Find a src file from a DWARF tag path. Prepend optional source path prefix
1769 * and chop off leading directories that do not exist. Result is passed back as
1770 * a newly allocated path on success.
1771 * Return 0 if file was found and readable, -errno otherwise.
1772 */
get_real_path(const char * raw_path,const char * comp_dir,char ** new_path)1773 int get_real_path(const char *raw_path, const char *comp_dir,
1774 char **new_path)
1775 {
1776 const char *prefix = symbol_conf.source_prefix;
1777
1778 if (!prefix) {
1779 if (raw_path[0] != '/' && comp_dir)
1780 /* If not an absolute path, try to use comp_dir */
1781 prefix = comp_dir;
1782 else {
1783 if (access(raw_path, R_OK) == 0) {
1784 *new_path = strdup(raw_path);
1785 return *new_path ? 0 : -ENOMEM;
1786 } else
1787 return -errno;
1788 }
1789 }
1790
1791 *new_path = malloc((strlen(prefix) + strlen(raw_path) + 2));
1792 if (!*new_path)
1793 return -ENOMEM;
1794
1795 for (;;) {
1796 sprintf(*new_path, "%s/%s", prefix, raw_path);
1797
1798 if (access(*new_path, R_OK) == 0)
1799 return 0;
1800
1801 if (!symbol_conf.source_prefix) {
1802 /* In case of searching comp_dir, don't retry */
1803 zfree(new_path);
1804 return -errno;
1805 }
1806
1807 switch (errno) {
1808 case ENAMETOOLONG:
1809 case ENOENT:
1810 case EROFS:
1811 case EFAULT:
1812 raw_path = strchr(++raw_path, '/');
1813 if (!raw_path) {
1814 zfree(new_path);
1815 return -ENOENT;
1816 }
1817 continue;
1818
1819 default:
1820 zfree(new_path);
1821 return -errno;
1822 }
1823 }
1824 }
1825