1 // SPDX-License-Identifier: GPL-2.0-or-later
3 * probe-finder.c : C expression to kprobe event converter
5 * Written by Masami Hiramatsu <mhiramat@redhat.com>
9 #include <sys/utsname.h>
10 #include <sys/types.h>
19 #include <dwarf-regs.h>
21 #include <linux/bitops.h>
22 #include <linux/zalloc.h>
30 #include "probe-finder.h"
31 #include "probe-file.h"
34 /* Kprobe tracer basic type is up to u64 */
35 #define MAX_BASIC_TYPE_BITS 64
37 /* Dwarf FL wrappers */
38 static char *debuginfo_path; /* Currently dummy */
40 static const Dwfl_Callbacks offline_callbacks = {
41 .find_debuginfo = dwfl_standard_find_debuginfo,
42 .debuginfo_path = &debuginfo_path,
44 .section_address = dwfl_offline_section_address,
46 /* We use this table for core files too. */
47 .find_elf = dwfl_build_id_find_elf,
50 /* Get a Dwarf from offline image */
51 static int debuginfo__init_offline_dwarf(struct debuginfo *dbg,
56 fd = open(path, O_RDONLY);
60 dbg->dwfl = dwfl_begin(&offline_callbacks);
64 dwfl_report_begin(dbg->dwfl);
65 dbg->mod = dwfl_report_offline(dbg->dwfl, "", "", fd);
69 dbg->dbg = dwfl_module_getdwarf(dbg->mod, &dbg->bias);
73 dwfl_report_end(dbg->dwfl, NULL, NULL);
81 memset(dbg, 0, sizeof(*dbg));
86 static struct debuginfo *__debuginfo__new(const char *path)
88 struct debuginfo *dbg = zalloc(sizeof(*dbg));
92 if (debuginfo__init_offline_dwarf(dbg, path) < 0)
95 pr_debug("Open Debuginfo file: %s\n", path);
99 enum dso_binary_type distro_dwarf_types[] = {
100 DSO_BINARY_TYPE__FEDORA_DEBUGINFO,
101 DSO_BINARY_TYPE__UBUNTU_DEBUGINFO,
102 DSO_BINARY_TYPE__OPENEMBEDDED_DEBUGINFO,
103 DSO_BINARY_TYPE__BUILDID_DEBUGINFO,
104 DSO_BINARY_TYPE__NOT_FOUND,
107 struct debuginfo *debuginfo__new(const char *path)
109 enum dso_binary_type *type;
110 char buf[PATH_MAX], nil = '\0';
112 struct debuginfo *dinfo = NULL;
114 /* Try to open distro debuginfo files */
115 dso = dso__new(path);
119 for (type = distro_dwarf_types;
120 !dinfo && *type != DSO_BINARY_TYPE__NOT_FOUND;
122 if (dso__read_binary_type_filename(dso, *type, &nil,
125 dinfo = __debuginfo__new(buf);
130 /* if failed to open all distro debuginfo, open given binary */
131 return dinfo ? : __debuginfo__new(path);
134 void debuginfo__delete(struct debuginfo *dbg)
144 * Probe finder related functions
147 static struct probe_trace_arg_ref *alloc_trace_arg_ref(long offs)
149 struct probe_trace_arg_ref *ref;
150 ref = zalloc(sizeof(struct probe_trace_arg_ref));
157 * Convert a location into trace_arg.
158 * If tvar == NULL, this just checks variable can be converted.
159 * If fentry == true and vr_die is a parameter, do huristic search
160 * for the location fuzzed by function entry mcount.
162 static int convert_variable_location(Dwarf_Die *vr_die, Dwarf_Addr addr,
163 Dwarf_Op *fb_ops, Dwarf_Die *sp_die,
164 unsigned int machine,
165 struct probe_trace_arg *tvar)
167 Dwarf_Attribute attr;
177 if (dwarf_attr(vr_die, DW_AT_external, &attr) != NULL)
180 /* TODO: handle more than 1 exprs */
181 if (dwarf_attr(vr_die, DW_AT_location, &attr) == NULL)
182 return -EINVAL; /* Broken DIE ? */
183 if (dwarf_getlocation_addr(&attr, addr, &op, &nops, 1) <= 0) {
184 ret = dwarf_entrypc(sp_die, &tmp);
188 if (probe_conf.show_location_range &&
189 (dwarf_tag(vr_die) == DW_TAG_variable)) {
191 } else if (addr != tmp ||
192 dwarf_tag(vr_die) != DW_TAG_formal_parameter) {
196 ret = dwarf_highpc(sp_die, &tmp);
200 * This is fuzzed by fentry mcount. We try to find the
201 * parameter location at the earliest address.
203 for (addr += 1; addr <= tmp; addr++) {
204 if (dwarf_getlocation_addr(&attr, addr, &op,
212 /* TODO: Support const_value */
215 if (op->atom == DW_OP_addr) {
219 /* Static variables on memory (not stack), make @varname */
220 ret = strlen(dwarf_diename(vr_die));
221 tvar->value = zalloc(ret + 2);
222 if (tvar->value == NULL)
224 snprintf(tvar->value, ret + 2, "@%s", dwarf_diename(vr_die));
225 tvar->ref = alloc_trace_arg_ref((long)offs);
226 if (tvar->ref == NULL)
231 /* If this is based on frame buffer, set the offset */
232 if (op->atom == DW_OP_fbreg) {
240 if (op->atom >= DW_OP_breg0 && op->atom <= DW_OP_breg31) {
241 regn = op->atom - DW_OP_breg0;
244 } else if (op->atom >= DW_OP_reg0 && op->atom <= DW_OP_reg31) {
245 regn = op->atom - DW_OP_reg0;
246 } else if (op->atom == DW_OP_bregx) {
250 } else if (op->atom == DW_OP_regx) {
253 pr_debug("DW_OP %x is not supported.\n", op->atom);
260 regs = get_dwarf_regstr(regn, machine);
262 /* This should be a bug in DWARF or this tool */
263 pr_warning("Mapping for the register number %u "
264 "missing on this architecture.\n", regn);
268 tvar->value = strdup(regs);
269 if (tvar->value == NULL)
273 tvar->ref = alloc_trace_arg_ref((long)offs);
274 if (tvar->ref == NULL)
280 #define BYTES_TO_BITS(nb) ((nb) * BITS_PER_LONG / sizeof(long))
282 static int convert_variable_type(Dwarf_Die *vr_die,
283 struct probe_trace_arg *tvar,
284 const char *cast, bool user_access)
286 struct probe_trace_arg_ref **ref_ptr = &tvar->ref;
289 char sbuf[STRERR_BUFSIZE];
290 int bsize, boffs, total;
294 /* TODO: check all types */
295 if (cast && strcmp(cast, "string") != 0 && strcmp(cast, "x") != 0 &&
296 strcmp(cast, "s") != 0 && strcmp(cast, "u") != 0) {
297 /* Non string type is OK */
298 /* and respect signedness/hexadecimal cast */
299 tvar->type = strdup(cast);
300 return (tvar->type == NULL) ? -ENOMEM : 0;
303 bsize = dwarf_bitsize(vr_die);
305 /* This is a bitfield */
306 boffs = dwarf_bitoffset(vr_die);
307 total = dwarf_bytesize(vr_die);
308 if (boffs < 0 || total < 0)
310 ret = snprintf(buf, 16, "b%d@%d/%zd", bsize, boffs,
311 BYTES_TO_BITS(total));
315 if (die_get_real_type(vr_die, &type) == NULL) {
316 pr_warning("Failed to get a type information of %s.\n",
317 dwarf_diename(vr_die));
321 pr_debug("%s type is %s.\n",
322 dwarf_diename(vr_die), dwarf_diename(&type));
324 if (cast && (!strcmp(cast, "string") || !strcmp(cast, "ustring"))) {
326 ret = dwarf_tag(&type);
327 if (ret != DW_TAG_pointer_type &&
328 ret != DW_TAG_array_type) {
329 pr_warning("Failed to cast into string: "
330 "%s(%s) is not a pointer nor array.\n",
331 dwarf_diename(vr_die), dwarf_diename(&type));
334 if (die_get_real_type(&type, &type) == NULL) {
335 pr_warning("Failed to get a type"
339 if (ret == DW_TAG_pointer_type) {
341 ref_ptr = &(*ref_ptr)->next;
342 /* Add new reference with offset +0 */
343 *ref_ptr = zalloc(sizeof(struct probe_trace_arg_ref));
344 if (*ref_ptr == NULL) {
345 pr_warning("Out of memory error\n");
348 (*ref_ptr)->user_access = user_access;
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));
357 tvar->type = strdup(cast);
358 return (tvar->type == NULL) ? -ENOMEM : 0;
361 if (cast && (strcmp(cast, "u") == 0))
363 else if (cast && (strcmp(cast, "s") == 0))
365 else if (cast && (strcmp(cast, "x") == 0) &&
366 probe_type_is_available(PROBE_TYPE_X))
369 prefix = die_is_signed_type(&type) ? 's' :
370 probe_type_is_available(PROBE_TYPE_X) ? 'x' : 'u';
372 ret = dwarf_bytesize(&type);
374 /* No size ... try to use default type */
376 ret = BYTES_TO_BITS(ret);
378 /* Check the bitwidth */
379 if (ret > MAX_BASIC_TYPE_BITS) {
380 pr_info("%s exceeds max-bitwidth. Cut down to %d bits.\n",
381 dwarf_diename(&type), MAX_BASIC_TYPE_BITS);
382 ret = MAX_BASIC_TYPE_BITS;
384 ret = snprintf(buf, 16, "%c%d", prefix, ret);
387 if (ret < 0 || ret >= 16) {
390 pr_warning("Failed to convert variable type: %s\n",
391 str_error_r(-ret, sbuf, sizeof(sbuf)));
394 tvar->type = strdup(buf);
395 if (tvar->type == NULL)
400 static int convert_variable_fields(Dwarf_Die *vr_die, const char *varname,
401 struct perf_probe_arg_field *field,
402 struct probe_trace_arg_ref **ref_ptr,
403 Dwarf_Die *die_mem, bool user_access)
405 struct probe_trace_arg_ref *ref = *ref_ptr;
410 pr_debug("converting %s in %s\n", field->name, varname);
411 if (die_get_real_type(vr_die, &type) == NULL) {
412 pr_warning("Failed to get the type of %s.\n", varname);
415 pr_debug2("Var real type: %s (%x)\n", dwarf_diename(&type),
416 (unsigned)dwarf_dieoffset(&type));
417 tag = dwarf_tag(&type);
419 if (field->name[0] == '[' &&
420 (tag == DW_TAG_array_type || tag == DW_TAG_pointer_type)) {
421 /* Save original type for next field or type */
422 memcpy(die_mem, &type, sizeof(*die_mem));
423 /* Get the type of this array */
424 if (die_get_real_type(&type, &type) == NULL) {
425 pr_warning("Failed to get the type of %s.\n", varname);
428 pr_debug2("Array real type: %s (%x)\n", dwarf_diename(&type),
429 (unsigned)dwarf_dieoffset(&type));
430 if (tag == DW_TAG_pointer_type) {
431 ref = zalloc(sizeof(struct probe_trace_arg_ref));
435 (*ref_ptr)->next = ref;
439 ref->offset += dwarf_bytesize(&type) * field->index;
440 ref->user_access = user_access;
442 } else if (tag == DW_TAG_pointer_type) {
443 /* Check the pointer and dereference */
445 pr_err("Semantic error: %s must be referred by '->'\n",
449 /* Get the type pointed by this pointer */
450 if (die_get_real_type(&type, &type) == NULL) {
451 pr_warning("Failed to get the type of %s.\n", varname);
454 /* Verify it is a data structure */
455 tag = dwarf_tag(&type);
456 if (tag != DW_TAG_structure_type && tag != DW_TAG_union_type) {
457 pr_warning("%s is not a data structure nor a union.\n",
462 ref = zalloc(sizeof(struct probe_trace_arg_ref));
466 (*ref_ptr)->next = ref;
470 /* Verify it is a data structure */
471 if (tag != DW_TAG_structure_type && tag != DW_TAG_union_type) {
472 pr_warning("%s is not a data structure nor a union.\n",
476 if (field->name[0] == '[') {
477 pr_err("Semantic error: %s is not a pointer"
478 " nor array.\n", varname);
481 /* While prcessing unnamed field, we don't care about this */
482 if (field->ref && dwarf_diename(vr_die)) {
483 pr_err("Semantic error: %s must be referred by '.'\n",
488 pr_warning("Structure on a register is not "
494 if (die_find_member(&type, field->name, die_mem) == NULL) {
495 pr_warning("%s(type:%s) has no member %s.\n", varname,
496 dwarf_diename(&type), field->name);
500 /* Get the offset of the field */
501 if (tag == DW_TAG_union_type) {
504 ret = die_get_data_member_location(die_mem, &offs);
506 pr_warning("Failed to get the offset of %s.\n",
511 ref->offset += (long)offs;
512 ref->user_access = user_access;
514 /* If this member is unnamed, we need to reuse this field */
515 if (!dwarf_diename(die_mem))
516 return convert_variable_fields(die_mem, varname, field,
517 &ref, die_mem, user_access);
520 /* Converting next field */
522 return convert_variable_fields(die_mem, field->name,
523 field->next, &ref, die_mem, user_access);
528 /* Show a variables in kprobe event format */
529 static int convert_variable(Dwarf_Die *vr_die, struct probe_finder *pf)
534 pr_debug("Converting variable %s into trace event.\n",
535 dwarf_diename(vr_die));
537 ret = convert_variable_location(vr_die, pf->addr, pf->fb_ops,
538 &pf->sp_die, pf->machine, pf->tvar);
539 if (ret == -ENOENT || ret == -EINVAL) {
540 pr_err("Failed to find the location of the '%s' variable at this address.\n"
541 " Perhaps it has been optimized out.\n"
542 " Use -V with the --range option to show '%s' location range.\n",
543 pf->pvar->var, pf->pvar->var);
544 } else if (ret == -ENOTSUP)
545 pr_err("Sorry, we don't support this variable location yet.\n");
546 else if (ret == 0 && pf->pvar->field) {
547 ret = convert_variable_fields(vr_die, pf->pvar->var,
548 pf->pvar->field, &pf->tvar->ref,
549 &die_mem, pf->pvar->user_access);
553 ret = convert_variable_type(vr_die, pf->tvar, pf->pvar->type,
554 pf->pvar->user_access);
555 /* *expr will be cached in libdw. Don't free it. */
559 /* Find a variable in a scope DIE */
560 static int find_variable(Dwarf_Die *sc_die, struct probe_finder *pf)
566 /* Copy raw parameters */
567 if (!is_c_varname(pf->pvar->var))
568 return copy_to_probe_trace_arg(pf->tvar, pf->pvar);
571 pf->tvar->name = strdup(pf->pvar->name);
573 buf = synthesize_perf_probe_arg(pf->pvar);
576 ptr = strchr(buf, ':'); /* Change type separator to _ */
579 pf->tvar->name = buf;
581 if (pf->tvar->name == NULL)
584 pr_debug("Searching '%s' variable in context.\n", pf->pvar->var);
585 /* Search child die for local variables and parameters. */
586 if (!die_find_variable_at(sc_die, pf->pvar->var, pf->addr, &vr_die)) {
587 /* Search again in global variables */
588 if (!die_find_variable_at(&pf->cu_die, pf->pvar->var,
590 pr_warning("Failed to find '%s' in this function.\n",
596 ret = convert_variable(&vr_die, pf);
601 /* Convert subprogram DIE to trace point */
602 static int convert_to_trace_point(Dwarf_Die *sp_die, Dwfl_Module *mod,
603 Dwarf_Addr paddr, bool retprobe,
604 const char *function,
605 struct probe_trace_point *tp)
607 Dwarf_Addr eaddr, highaddr;
611 /* Verify the address is correct */
612 if (dwarf_entrypc(sp_die, &eaddr) != 0) {
613 pr_warning("Failed to get entry address of %s\n",
614 dwarf_diename(sp_die));
617 if (dwarf_highpc(sp_die, &highaddr) != 0) {
618 pr_warning("Failed to get end address of %s\n",
619 dwarf_diename(sp_die));
622 if (paddr > highaddr) {
623 pr_warning("Offset specified is greater than size of %s\n",
624 dwarf_diename(sp_die));
628 symbol = dwarf_diename(sp_die);
630 /* Try to get the symbol name from symtab */
631 symbol = dwfl_module_addrsym(mod, paddr, &sym, NULL);
633 pr_warning("Failed to find symbol at 0x%lx\n",
634 (unsigned long)paddr);
637 eaddr = sym.st_value;
639 tp->offset = (unsigned long)(paddr - eaddr);
640 tp->address = (unsigned long)paddr;
641 tp->symbol = strdup(symbol);
645 /* Return probe must be on the head of a subprogram */
647 if (eaddr != paddr) {
648 pr_warning("Failed to find \"%s%%return\",\n"
649 " because %s is an inlined function and"
650 " has no return point.\n", function,
660 /* Call probe_finder callback with scope DIE */
661 static int call_probe_finder(Dwarf_Die *sc_die, struct probe_finder *pf)
663 Dwarf_Attribute fb_attr;
664 Dwarf_Frame *frame = NULL;
669 pr_err("Caller must pass a scope DIE. Program error.\n");
673 /* If not a real subprogram, find a real one */
674 if (!die_is_func_def(sc_die)) {
675 if (!die_find_realfunc(&pf->cu_die, pf->addr, &pf->sp_die)) {
676 if (die_find_tailfunc(&pf->cu_die, pf->addr, &pf->sp_die)) {
677 pr_warning("Ignoring tail call from %s\n",
678 dwarf_diename(&pf->sp_die));
681 pr_warning("Failed to find probe point in any "
687 memcpy(&pf->sp_die, sc_die, sizeof(Dwarf_Die));
689 /* Get the frame base attribute/ops from subprogram */
690 dwarf_attr(&pf->sp_die, DW_AT_frame_base, &fb_attr);
691 ret = dwarf_getlocation_addr(&fb_attr, pf->addr, &pf->fb_ops, &nops, 1);
692 if (ret <= 0 || nops == 0) {
694 #if _ELFUTILS_PREREQ(0, 142)
695 } else if (nops == 1 && pf->fb_ops[0].atom == DW_OP_call_frame_cfa &&
696 (pf->cfi_eh != NULL || pf->cfi_dbg != NULL)) {
697 if ((dwarf_cfi_addrframe(pf->cfi_eh, pf->addr, &frame) != 0 &&
698 (dwarf_cfi_addrframe(pf->cfi_dbg, pf->addr, &frame) != 0)) ||
699 dwarf_frame_cfa(frame, &pf->fb_ops, &nops) != 0) {
700 pr_warning("Failed to get call frame on 0x%jx\n",
701 (uintmax_t)pf->addr);
708 /* Call finder's callback handler */
709 ret = pf->callback(sc_die, pf);
711 /* Since *pf->fb_ops can be a part of frame. we should free it here. */
718 struct find_scope_param {
719 const char *function;
727 static int find_best_scope_cb(Dwarf_Die *fn_die, void *data)
729 struct find_scope_param *fsp = data;
733 /* Skip if declared file name does not match */
735 file = dwarf_decl_file(fn_die);
736 if (!file || strcmp(fsp->file, file) != 0)
739 /* If the function name is given, that's what user expects */
741 if (die_match_name(fn_die, fsp->function)) {
742 memcpy(fsp->die_mem, fn_die, sizeof(Dwarf_Die));
747 /* With the line number, find the nearest declared DIE */
748 dwarf_decl_line(fn_die, &lno);
749 if (lno < fsp->line && fsp->diff > fsp->line - lno) {
750 /* Keep a candidate and continue */
751 fsp->diff = fsp->line - lno;
752 memcpy(fsp->die_mem, fn_die, sizeof(Dwarf_Die));
759 /* Find an appropriate scope fits to given conditions */
760 static Dwarf_Die *find_best_scope(struct probe_finder *pf, Dwarf_Die *die_mem)
762 struct find_scope_param fsp = {
763 .function = pf->pev->point.function,
771 cu_walk_functions_at(&pf->cu_die, pf->addr, find_best_scope_cb, &fsp);
773 return fsp.found ? die_mem : NULL;
776 static int probe_point_line_walker(const char *fname, int lineno,
777 Dwarf_Addr addr, void *data)
779 struct probe_finder *pf = data;
780 Dwarf_Die *sc_die, die_mem;
783 if (lineno != pf->lno || strtailcmp(fname, pf->fname) != 0)
787 sc_die = find_best_scope(pf, &die_mem);
789 pr_warning("Failed to find scope of probe point.\n");
793 ret = call_probe_finder(sc_die, pf);
795 /* Continue if no error, because the line will be in inline function */
796 return ret < 0 ? ret : 0;
799 /* Find probe point from its line number */
800 static int find_probe_point_by_line(struct probe_finder *pf)
802 return die_walk_lines(&pf->cu_die, probe_point_line_walker, pf);
805 /* Find lines which match lazy pattern */
806 static int find_lazy_match_lines(struct intlist *list,
807 const char *fname, const char *pat)
813 int count = 0, linenum = 1;
814 char sbuf[STRERR_BUFSIZE];
816 fp = fopen(fname, "r");
818 pr_warning("Failed to open %s: %s\n", fname,
819 str_error_r(errno, sbuf, sizeof(sbuf)));
823 while ((len = getline(&line, &line_len, fp)) > 0) {
825 if (line[len - 1] == '\n')
826 line[len - 1] = '\0';
828 if (strlazymatch(line, pat)) {
829 intlist__add(list, linenum);
841 pr_debug("No matched lines found in %s.\n", fname);
845 static int probe_point_lazy_walker(const char *fname, int lineno,
846 Dwarf_Addr addr, void *data)
848 struct probe_finder *pf = data;
849 Dwarf_Die *sc_die, die_mem;
852 if (!intlist__has_entry(pf->lcache, lineno) ||
853 strtailcmp(fname, pf->fname) != 0)
856 pr_debug("Probe line found: line:%d addr:0x%llx\n",
857 lineno, (unsigned long long)addr);
860 sc_die = find_best_scope(pf, &die_mem);
862 pr_warning("Failed to find scope of probe point.\n");
866 ret = call_probe_finder(sc_die, pf);
869 * Continue if no error, because the lazy pattern will match
872 return ret < 0 ? ret : 0;
875 /* Find probe points from lazy pattern */
876 static int find_probe_point_lazy(Dwarf_Die *sp_die, struct probe_finder *pf)
881 if (intlist__empty(pf->lcache)) {
882 const char *comp_dir;
884 comp_dir = cu_get_comp_dir(&pf->cu_die);
885 ret = get_real_path(pf->fname, comp_dir, &fpath);
887 pr_warning("Failed to find source file path.\n");
891 /* Matching lazy line pattern */
892 ret = find_lazy_match_lines(pf->lcache, fpath,
893 pf->pev->point.lazy_line);
899 return die_walk_lines(sp_die, probe_point_lazy_walker, pf);
902 static void skip_prologue(Dwarf_Die *sp_die, struct probe_finder *pf)
904 struct perf_probe_point *pp = &pf->pev->point;
907 if (!pf->pev->uprobes)
910 /* Compiled with optimization? */
911 if (die_is_optimized_target(&pf->cu_die))
914 /* Don't know entrypc? */
918 /* Only FUNC and FUNC@SRC are eligible. */
919 if (!pp->function || pp->line || pp->retprobe || pp->lazy_line ||
920 pp->offset || pp->abs_address)
923 /* Not interested in func parameter? */
924 if (!perf_probe_with_var(pf->pev))
927 pr_info("Target program is compiled without optimization. Skipping prologue.\n"
928 "Probe on address 0x%" PRIx64 " to force probing at the function entry.\n\n",
931 die_skip_prologue(sp_die, &pf->cu_die, &pf->addr);
934 static int probe_point_inline_cb(Dwarf_Die *in_die, void *data)
936 struct probe_finder *pf = data;
937 struct perf_probe_point *pp = &pf->pev->point;
942 ret = find_probe_point_lazy(in_die, pf);
944 /* Get probe address */
945 if (dwarf_entrypc(in_die, &addr) != 0) {
946 pr_warning("Failed to get entry address of %s.\n",
947 dwarf_diename(in_die));
951 pr_debug("%s has no valid entry address. skipped.\n",
952 dwarf_diename(in_die));
956 pf->addr += pp->offset;
957 pr_debug("found inline addr: 0x%jx\n",
958 (uintmax_t)pf->addr);
960 ret = call_probe_finder(in_die, pf);
966 /* Callback parameter with return value for libdw */
967 struct dwarf_callback_param {
972 /* Search function from function name */
973 static int probe_point_search_cb(Dwarf_Die *sp_die, void *data)
975 struct dwarf_callback_param *param = data;
976 struct probe_finder *pf = param->data;
977 struct perf_probe_point *pp = &pf->pev->point;
979 /* Check tag and diename */
980 if (!die_is_func_def(sp_die) ||
981 !die_match_name(sp_die, pp->function))
984 /* Check declared file */
985 if (pp->file && strtailcmp(pp->file, dwarf_decl_file(sp_die)))
988 pr_debug("Matched function: %s [%lx]\n", dwarf_diename(sp_die),
989 (unsigned long)dwarf_dieoffset(sp_die));
990 pf->fname = dwarf_decl_file(sp_die);
991 if (pp->line) { /* Function relative line */
992 dwarf_decl_line(sp_die, &pf->lno);
994 param->retval = find_probe_point_by_line(pf);
995 } else if (die_is_func_instance(sp_die)) {
996 /* Instances always have the entry address */
997 dwarf_entrypc(sp_die, &pf->addr);
998 /* But in some case the entry address is 0 */
1000 pr_debug("%s has no entry PC. Skipped\n",
1001 dwarf_diename(sp_die));
1004 } else if (pp->lazy_line)
1005 param->retval = find_probe_point_lazy(sp_die, pf);
1007 skip_prologue(sp_die, pf);
1008 pf->addr += pp->offset;
1009 /* TODO: Check the address in this function */
1010 param->retval = call_probe_finder(sp_die, pf);
1012 } else if (!probe_conf.no_inlines) {
1013 /* Inlined function: search instances */
1014 param->retval = die_walk_instances(sp_die,
1015 probe_point_inline_cb, (void *)pf);
1016 /* This could be a non-existed inline definition */
1017 if (param->retval == -ENOENT)
1021 /* We need to find other candidates */
1022 if (strisglob(pp->function) && param->retval >= 0) {
1023 param->retval = 0; /* We have to clear the result */
1027 return DWARF_CB_ABORT; /* Exit; no same symbol in this CU. */
1030 static int find_probe_point_by_func(struct probe_finder *pf)
1032 struct dwarf_callback_param _param = {.data = (void *)pf,
1034 dwarf_getfuncs(&pf->cu_die, probe_point_search_cb, &_param, 0);
1035 return _param.retval;
1038 struct pubname_callback_param {
1046 static int pubname_search_cb(Dwarf *dbg, Dwarf_Global *gl, void *data)
1048 struct pubname_callback_param *param = data;
1050 if (dwarf_offdie(dbg, gl->die_offset, param->sp_die)) {
1051 if (dwarf_tag(param->sp_die) != DW_TAG_subprogram)
1054 if (die_match_name(param->sp_die, param->function)) {
1055 if (!dwarf_offdie(dbg, gl->cu_offset, param->cu_die))
1059 strtailcmp(param->file, dwarf_decl_file(param->sp_die)))
1063 return DWARF_CB_ABORT;
1070 static int debuginfo__find_probe_location(struct debuginfo *dbg,
1071 struct probe_finder *pf)
1073 struct perf_probe_point *pp = &pf->pev->point;
1074 Dwarf_Off off, noff;
1080 pf->lcache = intlist__new(NULL);
1084 /* Fastpath: lookup by function name from .debug_pubnames section */
1085 if (pp->function && !strisglob(pp->function)) {
1086 struct pubname_callback_param pubname_param = {
1087 .function = pp->function,
1089 .cu_die = &pf->cu_die,
1090 .sp_die = &pf->sp_die,
1093 struct dwarf_callback_param probe_param = {
1097 dwarf_getpubnames(dbg->dbg, pubname_search_cb,
1099 if (pubname_param.found) {
1100 ret = probe_point_search_cb(&pf->sp_die, &probe_param);
1106 /* Loop on CUs (Compilation Unit) */
1107 while (!dwarf_nextcu(dbg->dbg, off, &noff, &cuhl, NULL, NULL, NULL)) {
1108 /* Get the DIE(Debugging Information Entry) of this CU */
1109 diep = dwarf_offdie(dbg->dbg, off + cuhl, &pf->cu_die);
1113 /* Check if target file is included. */
1115 pf->fname = cu_find_realpath(&pf->cu_die, pp->file);
1119 if (!pp->file || pf->fname) {
1121 ret = find_probe_point_by_func(pf);
1122 else if (pp->lazy_line)
1123 ret = find_probe_point_lazy(&pf->cu_die, pf);
1126 ret = find_probe_point_by_line(pf);
1135 intlist__delete(pf->lcache);
1141 /* Find probe points from debuginfo */
1142 static int debuginfo__find_probes(struct debuginfo *dbg,
1143 struct probe_finder *pf)
1149 if (pf->cfi_eh || pf->cfi_dbg)
1150 return debuginfo__find_probe_location(dbg, pf);
1152 /* Get the call frame information from this dwarf */
1153 elf = dwarf_getelf(dbg->dbg);
1157 if (gelf_getehdr(elf, &ehdr) == NULL)
1160 pf->machine = ehdr.e_machine;
1162 #if _ELFUTILS_PREREQ(0, 142)
1166 if (elf_section_by_name(elf, &ehdr, &shdr, ".eh_frame", NULL) &&
1167 shdr.sh_type == SHT_PROGBITS)
1168 pf->cfi_eh = dwarf_getcfi_elf(elf);
1170 pf->cfi_dbg = dwarf_getcfi(dbg->dbg);
1174 ret = debuginfo__find_probe_location(dbg, pf);
1178 struct local_vars_finder {
1179 struct probe_finder *pf;
1180 struct perf_probe_arg *args;
1187 /* Collect available variables in this scope */
1188 static int copy_variables_cb(Dwarf_Die *die_mem, void *data)
1190 struct local_vars_finder *vf = data;
1191 struct probe_finder *pf = vf->pf;
1194 tag = dwarf_tag(die_mem);
1195 if (tag == DW_TAG_formal_parameter ||
1196 (tag == DW_TAG_variable && vf->vars)) {
1197 if (convert_variable_location(die_mem, vf->pf->addr,
1198 vf->pf->fb_ops, &pf->sp_die,
1199 pf->machine, NULL) == 0) {
1200 vf->args[vf->nargs].var = (char *)dwarf_diename(die_mem);
1201 if (vf->args[vf->nargs].var == NULL) {
1203 return DIE_FIND_CB_END;
1205 pr_debug(" %s", vf->args[vf->nargs].var);
1210 if (dwarf_haspc(die_mem, vf->pf->addr))
1211 return DIE_FIND_CB_CONTINUE;
1213 return DIE_FIND_CB_SIBLING;
1216 static int expand_probe_args(Dwarf_Die *sc_die, struct probe_finder *pf,
1217 struct perf_probe_arg *args)
1222 struct local_vars_finder vf = {.pf = pf, .args = args, .vars = false,
1223 .max_args = MAX_PROBE_ARGS, .ret = 0};
1225 for (i = 0; i < pf->pev->nargs; i++) {
1226 /* var never be NULL */
1227 if (strcmp(pf->pev->args[i].var, PROBE_ARG_VARS) == 0)
1229 else if (strcmp(pf->pev->args[i].var, PROBE_ARG_PARAMS) != 0) {
1230 /* Copy normal argument */
1231 args[n] = pf->pev->args[i];
1235 pr_debug("Expanding %s into:", pf->pev->args[i].var);
1237 /* Special local variables */
1238 die_find_child(sc_die, copy_variables_cb, (void *)&vf,
1240 pr_debug(" (%d)\n", vf.nargs - n);
1248 static bool trace_event_finder_overlap(struct trace_event_finder *tf)
1252 for (i = 0; i < tf->ntevs; i++) {
1253 if (tf->pf.addr == tf->tevs[i].point.address)
1259 /* Add a found probe point into trace event list */
1260 static int add_probe_trace_event(Dwarf_Die *sc_die, struct probe_finder *pf)
1262 struct trace_event_finder *tf =
1263 container_of(pf, struct trace_event_finder, pf);
1264 struct perf_probe_point *pp = &pf->pev->point;
1265 struct probe_trace_event *tev;
1266 struct perf_probe_arg *args = NULL;
1270 * For some reason (e.g. different column assigned to same address)
1271 * This callback can be called with the address which already passed.
1274 if (trace_event_finder_overlap(tf))
1277 /* Check number of tevs */
1278 if (tf->ntevs == tf->max_tevs) {
1279 pr_warning("Too many( > %d) probe point found.\n",
1283 tev = &tf->tevs[tf->ntevs++];
1285 /* Trace point should be converted from subprogram DIE */
1286 ret = convert_to_trace_point(&pf->sp_die, tf->mod, pf->addr,
1287 pp->retprobe, pp->function, &tev->point);
1291 tev->point.realname = strdup(dwarf_diename(sc_die));
1292 if (!tev->point.realname) {
1297 pr_debug("Probe point found: %s+%lu\n", tev->point.symbol,
1300 /* Expand special probe argument if exist */
1301 args = zalloc(sizeof(struct perf_probe_arg) * MAX_PROBE_ARGS);
1307 ret = expand_probe_args(sc_die, pf, args);
1312 tev->args = zalloc(sizeof(struct probe_trace_arg) * tev->nargs);
1313 if (tev->args == NULL) {
1318 /* Find each argument */
1319 for (i = 0; i < tev->nargs; i++) {
1320 pf->pvar = &args[i];
1321 pf->tvar = &tev->args[i];
1322 /* Variable should be found from scope DIE */
1323 ret = find_variable(sc_die, pf);
1330 clear_probe_trace_event(tev);
1337 /* Find probe_trace_events specified by perf_probe_event from debuginfo */
1338 int debuginfo__find_trace_events(struct debuginfo *dbg,
1339 struct perf_probe_event *pev,
1340 struct probe_trace_event **tevs)
1342 struct trace_event_finder tf = {
1343 .pf = {.pev = pev, .callback = add_probe_trace_event},
1344 .max_tevs = probe_conf.max_probes, .mod = dbg->mod};
1347 /* Allocate result tevs array */
1348 *tevs = zalloc(sizeof(struct probe_trace_event) * tf.max_tevs);
1355 ret = debuginfo__find_probes(dbg, &tf.pf);
1357 for (i = 0; i < tf.ntevs; i++)
1358 clear_probe_trace_event(&tf.tevs[i]);
1363 return (ret < 0) ? ret : tf.ntevs;
1366 /* Collect available variables in this scope */
1367 static int collect_variables_cb(Dwarf_Die *die_mem, void *data)
1369 struct available_var_finder *af = data;
1370 struct variable_list *vl;
1371 struct strbuf buf = STRBUF_INIT;
1374 vl = &af->vls[af->nvls - 1];
1376 tag = dwarf_tag(die_mem);
1377 if (tag == DW_TAG_formal_parameter ||
1378 tag == DW_TAG_variable) {
1379 ret = convert_variable_location(die_mem, af->pf.addr,
1380 af->pf.fb_ops, &af->pf.sp_die,
1381 af->pf.machine, NULL);
1382 if (ret == 0 || ret == -ERANGE) {
1384 bool externs = !af->child;
1386 if (strbuf_init(&buf, 64) < 0)
1389 if (probe_conf.show_location_range) {
1391 ret2 = strbuf_add(&buf,
1392 ret ? "[INV]\t" : "[VAL]\t", 6);
1394 ret2 = strbuf_add(&buf, "[EXT]\t", 6);
1399 ret2 = die_get_varname(die_mem, &buf);
1401 if (!ret2 && probe_conf.show_location_range &&
1403 if (strbuf_addch(&buf, '\t') < 0)
1405 ret2 = die_get_var_range(&af->pf.sp_die,
1409 pr_debug("Add new var: %s\n", buf.buf);
1411 strlist__add(vl->vars,
1412 strbuf_detach(&buf, NULL));
1414 strbuf_release(&buf);
1418 if (af->child && dwarf_haspc(die_mem, af->pf.addr))
1419 return DIE_FIND_CB_CONTINUE;
1421 return DIE_FIND_CB_SIBLING;
1423 strbuf_release(&buf);
1424 pr_debug("Error in strbuf\n");
1425 return DIE_FIND_CB_END;
1428 /* Add a found vars into available variables list */
1429 static int add_available_vars(Dwarf_Die *sc_die, struct probe_finder *pf)
1431 struct available_var_finder *af =
1432 container_of(pf, struct available_var_finder, pf);
1433 struct perf_probe_point *pp = &pf->pev->point;
1434 struct variable_list *vl;
1438 /* Check number of tevs */
1439 if (af->nvls == af->max_vls) {
1440 pr_warning("Too many( > %d) probe point found.\n", af->max_vls);
1443 vl = &af->vls[af->nvls++];
1445 /* Trace point should be converted from subprogram DIE */
1446 ret = convert_to_trace_point(&pf->sp_die, af->mod, pf->addr,
1447 pp->retprobe, pp->function, &vl->point);
1451 pr_debug("Probe point found: %s+%lu\n", vl->point.symbol,
1454 /* Find local variables */
1455 vl->vars = strlist__new(NULL, NULL);
1456 if (vl->vars == NULL)
1459 die_find_child(sc_die, collect_variables_cb, (void *)af, &die_mem);
1461 /* Find external variables */
1462 if (!probe_conf.show_ext_vars)
1464 /* Don't need to search child DIE for external vars. */
1466 die_find_child(&pf->cu_die, collect_variables_cb, (void *)af, &die_mem);
1469 if (strlist__empty(vl->vars)) {
1470 strlist__delete(vl->vars);
1478 * Find available variables at given probe point
1479 * Return the number of found probe points. Return 0 if there is no
1480 * matched probe point. Return <0 if an error occurs.
1482 int debuginfo__find_available_vars_at(struct debuginfo *dbg,
1483 struct perf_probe_event *pev,
1484 struct variable_list **vls)
1486 struct available_var_finder af = {
1487 .pf = {.pev = pev, .callback = add_available_vars},
1489 .max_vls = probe_conf.max_probes};
1492 /* Allocate result vls array */
1493 *vls = zalloc(sizeof(struct variable_list) * af.max_vls);
1500 ret = debuginfo__find_probes(dbg, &af.pf);
1502 /* Free vlist for error */
1504 zfree(&af.vls[af.nvls].point.symbol);
1505 strlist__delete(af.vls[af.nvls].vars);
1511 return (ret < 0) ? ret : af.nvls;
1514 /* For the kernel module, we need a special code to get a DIE */
1515 int debuginfo__get_text_offset(struct debuginfo *dbg, Dwarf_Addr *offs,
1522 GElf_Shdr mem, *shdr;
1525 elf = dwfl_module_getelf(dbg->mod, &dbg->bias);
1529 /* Get the number of relocations */
1530 n = dwfl_module_relocations(dbg->mod);
1533 /* Search the relocation related .text section */
1534 for (i = 0; i < n; i++) {
1535 p = dwfl_module_relocation_info(dbg->mod, i, &shndx);
1536 if (strcmp(p, ".text") == 0) {
1537 /* OK, get the section header */
1538 scn = elf_getscn(elf, shndx);
1541 shdr = gelf_getshdr(scn, &mem);
1544 *offs = shdr->sh_addr;
1546 *offs -= shdr->sh_offset;
1552 /* Reverse search */
1553 int debuginfo__find_probe_point(struct debuginfo *dbg, unsigned long addr,
1554 struct perf_probe_point *ppt)
1556 Dwarf_Die cudie, spdie, indie;
1557 Dwarf_Addr _addr = 0, baseaddr = 0;
1558 const char *fname = NULL, *func = NULL, *basefunc = NULL, *tmp;
1559 int baseline = 0, lineno = 0, ret = 0;
1561 /* We always need to relocate the address for aranges */
1562 if (debuginfo__get_text_offset(dbg, &baseaddr, false) == 0)
1565 if (!dwarf_addrdie(dbg->dbg, (Dwarf_Addr)addr, &cudie)) {
1566 pr_warning("Failed to find debug information for address %lx\n",
1572 /* Find a corresponding line (filename and lineno) */
1573 cu_find_lineinfo(&cudie, addr, &fname, &lineno);
1574 /* Don't care whether it failed or not */
1576 /* Find a corresponding function (name, baseline and baseaddr) */
1577 if (die_find_realfunc(&cudie, (Dwarf_Addr)addr, &spdie)) {
1578 /* Get function entry information */
1579 func = basefunc = dwarf_diename(&spdie);
1581 dwarf_entrypc(&spdie, &baseaddr) != 0 ||
1582 dwarf_decl_line(&spdie, &baseline) != 0) {
1587 fname = dwarf_decl_file(&spdie);
1588 if (addr == (unsigned long)baseaddr) {
1589 /* Function entry - Relative line number is 0 */
1594 /* Track down the inline functions step by step */
1595 while (die_find_top_inlinefunc(&spdie, (Dwarf_Addr)addr,
1597 /* There is an inline function */
1598 if (dwarf_entrypc(&indie, &_addr) == 0 &&
1601 * addr is at an inline function entry.
1602 * In this case, lineno should be the call-site
1603 * line number. (overwrite lineinfo)
1605 lineno = die_get_call_lineno(&indie);
1606 fname = die_get_call_file(&indie);
1610 * addr is in an inline function body.
1611 * Since lineno points one of the lines
1612 * of the inline function, baseline should
1613 * be the entry line of the inline function.
1615 tmp = dwarf_diename(&indie);
1617 dwarf_decl_line(&indie, &baseline) != 0)
1623 /* Verify the lineno and baseline are in a same file */
1624 tmp = dwarf_decl_file(&spdie);
1625 if (!tmp || strcmp(tmp, fname) != 0)
1630 /* Make a relative line number or an offset */
1632 ppt->line = lineno - baseline;
1633 else if (basefunc) {
1634 ppt->offset = addr - (unsigned long)baseaddr;
1638 /* Duplicate strings */
1640 ppt->function = strdup(func);
1641 if (ppt->function == NULL) {
1647 ppt->file = strdup(fname);
1648 if (ppt->file == NULL) {
1649 zfree(&ppt->function);
1655 if (ret == 0 && (fname || func))
1656 ret = 1; /* Found a point */
1660 /* Add a line and store the src path */
1661 static int line_range_add_line(const char *src, unsigned int lineno,
1662 struct line_range *lr)
1664 /* Copy source path */
1666 lr->path = strdup(src);
1667 if (lr->path == NULL)
1670 return intlist__add(lr->line_list, lineno);
1673 static int line_range_walk_cb(const char *fname, int lineno,
1674 Dwarf_Addr addr __maybe_unused,
1677 struct line_finder *lf = data;
1680 if ((strtailcmp(fname, lf->fname) != 0) ||
1681 (lf->lno_s > lineno || lf->lno_e < lineno))
1684 err = line_range_add_line(fname, lineno, lf->lr);
1685 if (err < 0 && err != -EEXIST)
1691 /* Find line range from its line number */
1692 static int find_line_range_by_line(Dwarf_Die *sp_die, struct line_finder *lf)
1696 ret = die_walk_lines(sp_die ?: &lf->cu_die, line_range_walk_cb, lf);
1700 if (!intlist__empty(lf->lr->line_list))
1701 ret = lf->found = 1;
1703 ret = 0; /* Lines are not found */
1705 zfree(&lf->lr->path);
1710 static int line_range_inline_cb(Dwarf_Die *in_die, void *data)
1712 int ret = find_line_range_by_line(in_die, data);
1715 * We have to check all instances of inlined function, because
1716 * some execution paths can be optimized out depends on the
1717 * function argument of instances. However, if an error occurs,
1718 * it should be handled by the caller.
1720 return ret < 0 ? ret : 0;
1723 /* Search function definition from function name */
1724 static int line_range_search_cb(Dwarf_Die *sp_die, void *data)
1726 struct dwarf_callback_param *param = data;
1727 struct line_finder *lf = param->data;
1728 struct line_range *lr = lf->lr;
1730 /* Check declared file */
1731 if (lr->file && strtailcmp(lr->file, dwarf_decl_file(sp_die)))
1734 if (die_is_func_def(sp_die) &&
1735 die_match_name(sp_die, lr->function)) {
1736 lf->fname = dwarf_decl_file(sp_die);
1737 dwarf_decl_line(sp_die, &lr->offset);
1738 pr_debug("fname: %s, lineno:%d\n", lf->fname, lr->offset);
1739 lf->lno_s = lr->offset + lr->start;
1740 if (lf->lno_s < 0) /* Overflow */
1741 lf->lno_s = INT_MAX;
1742 lf->lno_e = lr->offset + lr->end;
1743 if (lf->lno_e < 0) /* Overflow */
1744 lf->lno_e = INT_MAX;
1745 pr_debug("New line range: %d to %d\n", lf->lno_s, lf->lno_e);
1746 lr->start = lf->lno_s;
1747 lr->end = lf->lno_e;
1748 if (!die_is_func_instance(sp_die))
1749 param->retval = die_walk_instances(sp_die,
1750 line_range_inline_cb, lf);
1752 param->retval = find_line_range_by_line(sp_die, lf);
1753 return DWARF_CB_ABORT;
1758 static int find_line_range_by_func(struct line_finder *lf)
1760 struct dwarf_callback_param param = {.data = (void *)lf, .retval = 0};
1761 dwarf_getfuncs(&lf->cu_die, line_range_search_cb, ¶m, 0);
1762 return param.retval;
1765 int debuginfo__find_line_range(struct debuginfo *dbg, struct line_range *lr)
1767 struct line_finder lf = {.lr = lr, .found = 0};
1769 Dwarf_Off off = 0, noff;
1772 const char *comp_dir;
1774 /* Fastpath: lookup by function name from .debug_pubnames section */
1776 struct pubname_callback_param pubname_param = {
1777 .function = lr->function, .file = lr->file,
1778 .cu_die = &lf.cu_die, .sp_die = &lf.sp_die, .found = 0};
1779 struct dwarf_callback_param line_range_param = {
1780 .data = (void *)&lf, .retval = 0};
1782 dwarf_getpubnames(dbg->dbg, pubname_search_cb,
1784 if (pubname_param.found) {
1785 line_range_search_cb(&lf.sp_die, &line_range_param);
1791 /* Loop on CUs (Compilation Unit) */
1792 while (!lf.found && ret >= 0) {
1793 if (dwarf_nextcu(dbg->dbg, off, &noff, &cuhl,
1794 NULL, NULL, NULL) != 0)
1797 /* Get the DIE(Debugging Information Entry) of this CU */
1798 diep = dwarf_offdie(dbg->dbg, off + cuhl, &lf.cu_die);
1802 /* Check if target file is included. */
1804 lf.fname = cu_find_realpath(&lf.cu_die, lr->file);
1808 if (!lr->file || lf.fname) {
1810 ret = find_line_range_by_func(&lf);
1812 lf.lno_s = lr->start;
1814 ret = find_line_range_by_line(NULL, &lf);
1821 /* Store comp_dir */
1823 comp_dir = cu_get_comp_dir(&lf.cu_die);
1825 lr->comp_dir = strdup(comp_dir);
1831 pr_debug("path: %s\n", lr->path);
1832 return (ret < 0) ? ret : lf.found;
1836 * Find a src file from a DWARF tag path. Prepend optional source path prefix
1837 * and chop off leading directories that do not exist. Result is passed back as
1838 * a newly allocated path on success.
1839 * Return 0 if file was found and readable, -errno otherwise.
1841 int get_real_path(const char *raw_path, const char *comp_dir,
1844 const char *prefix = symbol_conf.source_prefix;
1847 if (raw_path[0] != '/' && comp_dir)
1848 /* If not an absolute path, try to use comp_dir */
1851 if (access(raw_path, R_OK) == 0) {
1852 *new_path = strdup(raw_path);
1853 return *new_path ? 0 : -ENOMEM;
1859 *new_path = malloc((strlen(prefix) + strlen(raw_path) + 2));
1864 sprintf(*new_path, "%s/%s", prefix, raw_path);
1866 if (access(*new_path, R_OK) == 0)
1869 if (!symbol_conf.source_prefix) {
1870 /* In case of searching comp_dir, don't retry */
1880 raw_path = strchr(++raw_path, '/');