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>
29 #include "probe-finder.h"
30 #include "probe-file.h"
33 /* Kprobe tracer basic type is up to u64 */
34 #define MAX_BASIC_TYPE_BITS 64
36 /* Dwarf FL wrappers */
37 static char *debuginfo_path; /* Currently dummy */
39 static const Dwfl_Callbacks offline_callbacks = {
40 .find_debuginfo = dwfl_standard_find_debuginfo,
41 .debuginfo_path = &debuginfo_path,
43 .section_address = dwfl_offline_section_address,
45 /* We use this table for core files too. */
46 .find_elf = dwfl_build_id_find_elf,
49 /* Get a Dwarf from offline image */
50 static int debuginfo__init_offline_dwarf(struct debuginfo *dbg,
55 fd = open(path, O_RDONLY);
59 dbg->dwfl = dwfl_begin(&offline_callbacks);
63 dwfl_report_begin(dbg->dwfl);
64 dbg->mod = dwfl_report_offline(dbg->dwfl, "", "", fd);
68 dbg->dbg = dwfl_module_getdwarf(dbg->mod, &dbg->bias);
72 dwfl_report_end(dbg->dwfl, NULL, NULL);
80 memset(dbg, 0, sizeof(*dbg));
85 static struct debuginfo *__debuginfo__new(const char *path)
87 struct debuginfo *dbg = zalloc(sizeof(*dbg));
91 if (debuginfo__init_offline_dwarf(dbg, path) < 0)
94 pr_debug("Open Debuginfo file: %s\n", path);
98 enum dso_binary_type distro_dwarf_types[] = {
99 DSO_BINARY_TYPE__FEDORA_DEBUGINFO,
100 DSO_BINARY_TYPE__UBUNTU_DEBUGINFO,
101 DSO_BINARY_TYPE__OPENEMBEDDED_DEBUGINFO,
102 DSO_BINARY_TYPE__BUILDID_DEBUGINFO,
103 DSO_BINARY_TYPE__NOT_FOUND,
106 struct debuginfo *debuginfo__new(const char *path)
108 enum dso_binary_type *type;
109 char buf[PATH_MAX], nil = '\0';
111 struct debuginfo *dinfo = NULL;
113 /* Try to open distro debuginfo files */
114 dso = dso__new(path);
118 for (type = distro_dwarf_types;
119 !dinfo && *type != DSO_BINARY_TYPE__NOT_FOUND;
121 if (dso__read_binary_type_filename(dso, *type, &nil,
124 dinfo = __debuginfo__new(buf);
129 /* if failed to open all distro debuginfo, open given binary */
130 return dinfo ? : __debuginfo__new(path);
133 void debuginfo__delete(struct debuginfo *dbg)
143 * Probe finder related functions
146 static struct probe_trace_arg_ref *alloc_trace_arg_ref(long offs)
148 struct probe_trace_arg_ref *ref;
149 ref = zalloc(sizeof(struct probe_trace_arg_ref));
156 * Convert a location into trace_arg.
157 * If tvar == NULL, this just checks variable can be converted.
158 * If fentry == true and vr_die is a parameter, do huristic search
159 * for the location fuzzed by function entry mcount.
161 static int convert_variable_location(Dwarf_Die *vr_die, Dwarf_Addr addr,
162 Dwarf_Op *fb_ops, Dwarf_Die *sp_die,
163 unsigned int machine,
164 struct probe_trace_arg *tvar)
166 Dwarf_Attribute attr;
176 if (dwarf_attr(vr_die, DW_AT_external, &attr) != NULL)
179 /* TODO: handle more than 1 exprs */
180 if (dwarf_attr(vr_die, DW_AT_location, &attr) == NULL)
181 return -EINVAL; /* Broken DIE ? */
182 if (dwarf_getlocation_addr(&attr, addr, &op, &nops, 1) <= 0) {
183 ret = dwarf_entrypc(sp_die, &tmp);
187 if (probe_conf.show_location_range &&
188 (dwarf_tag(vr_die) == DW_TAG_variable)) {
190 } else if (addr != tmp ||
191 dwarf_tag(vr_die) != DW_TAG_formal_parameter) {
195 ret = dwarf_highpc(sp_die, &tmp);
199 * This is fuzzed by fentry mcount. We try to find the
200 * parameter location at the earliest address.
202 for (addr += 1; addr <= tmp; addr++) {
203 if (dwarf_getlocation_addr(&attr, addr, &op,
211 /* TODO: Support const_value */
214 if (op->atom == DW_OP_addr) {
218 /* Static variables on memory (not stack), make @varname */
219 ret = strlen(dwarf_diename(vr_die));
220 tvar->value = zalloc(ret + 2);
221 if (tvar->value == NULL)
223 snprintf(tvar->value, ret + 2, "@%s", dwarf_diename(vr_die));
224 tvar->ref = alloc_trace_arg_ref((long)offs);
225 if (tvar->ref == NULL)
230 /* If this is based on frame buffer, set the offset */
231 if (op->atom == DW_OP_fbreg) {
239 if (op->atom >= DW_OP_breg0 && op->atom <= DW_OP_breg31) {
240 regn = op->atom - DW_OP_breg0;
243 } else if (op->atom >= DW_OP_reg0 && op->atom <= DW_OP_reg31) {
244 regn = op->atom - DW_OP_reg0;
245 } else if (op->atom == DW_OP_bregx) {
249 } else if (op->atom == DW_OP_regx) {
252 pr_debug("DW_OP %x is not supported.\n", op->atom);
259 regs = get_dwarf_regstr(regn, machine);
261 /* This should be a bug in DWARF or this tool */
262 pr_warning("Mapping for the register number %u "
263 "missing on this architecture.\n", regn);
267 tvar->value = strdup(regs);
268 if (tvar->value == NULL)
272 tvar->ref = alloc_trace_arg_ref((long)offs);
273 if (tvar->ref == NULL)
279 #define BYTES_TO_BITS(nb) ((nb) * BITS_PER_LONG / sizeof(long))
281 static int convert_variable_type(Dwarf_Die *vr_die,
282 struct probe_trace_arg *tvar,
283 const char *cast, bool user_access)
285 struct probe_trace_arg_ref **ref_ptr = &tvar->ref;
288 char sbuf[STRERR_BUFSIZE];
289 int bsize, boffs, total;
293 /* TODO: check all types */
294 if (cast && strcmp(cast, "string") != 0 && strcmp(cast, "x") != 0 &&
295 strcmp(cast, "s") != 0 && strcmp(cast, "u") != 0) {
296 /* Non string type is OK */
297 /* and respect signedness/hexadecimal cast */
298 tvar->type = strdup(cast);
299 return (tvar->type == NULL) ? -ENOMEM : 0;
302 bsize = dwarf_bitsize(vr_die);
304 /* This is a bitfield */
305 boffs = dwarf_bitoffset(vr_die);
306 total = dwarf_bytesize(vr_die);
307 if (boffs < 0 || total < 0)
309 ret = snprintf(buf, 16, "b%d@%d/%zd", bsize, boffs,
310 BYTES_TO_BITS(total));
314 if (die_get_real_type(vr_die, &type) == NULL) {
315 pr_warning("Failed to get a type information of %s.\n",
316 dwarf_diename(vr_die));
320 pr_debug("%s type is %s.\n",
321 dwarf_diename(vr_die), dwarf_diename(&type));
323 if (cast && (!strcmp(cast, "string") || !strcmp(cast, "ustring"))) {
325 ret = dwarf_tag(&type);
326 if (ret != DW_TAG_pointer_type &&
327 ret != DW_TAG_array_type) {
328 pr_warning("Failed to cast into string: "
329 "%s(%s) is not a pointer nor array.\n",
330 dwarf_diename(vr_die), dwarf_diename(&type));
333 if (die_get_real_type(&type, &type) == NULL) {
334 pr_warning("Failed to get a type"
338 if (ret == DW_TAG_pointer_type) {
340 ref_ptr = &(*ref_ptr)->next;
341 /* Add new reference with offset +0 */
342 *ref_ptr = zalloc(sizeof(struct probe_trace_arg_ref));
343 if (*ref_ptr == NULL) {
344 pr_warning("Out of memory error\n");
347 (*ref_ptr)->user_access = user_access;
349 if (!die_compare_name(&type, "char") &&
350 !die_compare_name(&type, "unsigned char")) {
351 pr_warning("Failed to cast into string: "
352 "%s is not (unsigned) char *.\n",
353 dwarf_diename(vr_die));
356 tvar->type = strdup(cast);
357 return (tvar->type == NULL) ? -ENOMEM : 0;
360 if (cast && (strcmp(cast, "u") == 0))
362 else if (cast && (strcmp(cast, "s") == 0))
364 else if (cast && (strcmp(cast, "x") == 0) &&
365 probe_type_is_available(PROBE_TYPE_X))
368 prefix = die_is_signed_type(&type) ? 's' :
369 probe_type_is_available(PROBE_TYPE_X) ? 'x' : 'u';
371 ret = dwarf_bytesize(&type);
373 /* No size ... try to use default type */
375 ret = BYTES_TO_BITS(ret);
377 /* Check the bitwidth */
378 if (ret > MAX_BASIC_TYPE_BITS) {
379 pr_info("%s exceeds max-bitwidth. Cut down to %d bits.\n",
380 dwarf_diename(&type), MAX_BASIC_TYPE_BITS);
381 ret = MAX_BASIC_TYPE_BITS;
383 ret = snprintf(buf, 16, "%c%d", prefix, ret);
386 if (ret < 0 || ret >= 16) {
389 pr_warning("Failed to convert variable type: %s\n",
390 str_error_r(-ret, sbuf, sizeof(sbuf)));
393 tvar->type = strdup(buf);
394 if (tvar->type == NULL)
399 static int convert_variable_fields(Dwarf_Die *vr_die, const char *varname,
400 struct perf_probe_arg_field *field,
401 struct probe_trace_arg_ref **ref_ptr,
402 Dwarf_Die *die_mem, bool user_access)
404 struct probe_trace_arg_ref *ref = *ref_ptr;
409 pr_debug("converting %s in %s\n", field->name, varname);
410 if (die_get_real_type(vr_die, &type) == NULL) {
411 pr_warning("Failed to get the type of %s.\n", varname);
414 pr_debug2("Var real type: %s (%x)\n", dwarf_diename(&type),
415 (unsigned)dwarf_dieoffset(&type));
416 tag = dwarf_tag(&type);
418 if (field->name[0] == '[' &&
419 (tag == DW_TAG_array_type || tag == DW_TAG_pointer_type)) {
420 /* Save original type for next field or type */
421 memcpy(die_mem, &type, sizeof(*die_mem));
422 /* Get the type of this array */
423 if (die_get_real_type(&type, &type) == NULL) {
424 pr_warning("Failed to get the type of %s.\n", varname);
427 pr_debug2("Array real type: %s (%x)\n", dwarf_diename(&type),
428 (unsigned)dwarf_dieoffset(&type));
429 if (tag == DW_TAG_pointer_type) {
430 ref = zalloc(sizeof(struct probe_trace_arg_ref));
434 (*ref_ptr)->next = ref;
438 ref->offset += dwarf_bytesize(&type) * field->index;
439 ref->user_access = user_access;
441 } else if (tag == DW_TAG_pointer_type) {
442 /* Check the pointer and dereference */
444 pr_err("Semantic error: %s must be referred by '->'\n",
448 /* Get the type pointed by this pointer */
449 if (die_get_real_type(&type, &type) == NULL) {
450 pr_warning("Failed to get the type of %s.\n", varname);
453 /* Verify it is a data structure */
454 tag = dwarf_tag(&type);
455 if (tag != DW_TAG_structure_type && tag != DW_TAG_union_type) {
456 pr_warning("%s is not a data structure nor a union.\n",
461 ref = zalloc(sizeof(struct probe_trace_arg_ref));
465 (*ref_ptr)->next = ref;
469 /* Verify it is a data structure */
470 if (tag != DW_TAG_structure_type && tag != DW_TAG_union_type) {
471 pr_warning("%s is not a data structure nor a union.\n",
475 if (field->name[0] == '[') {
476 pr_err("Semantic error: %s is not a pointer"
477 " nor array.\n", varname);
480 /* While prcessing unnamed field, we don't care about this */
481 if (field->ref && dwarf_diename(vr_die)) {
482 pr_err("Semantic error: %s must be referred by '.'\n",
487 pr_warning("Structure on a register is not "
493 if (die_find_member(&type, field->name, die_mem) == NULL) {
494 pr_warning("%s(type:%s) has no member %s.\n", varname,
495 dwarf_diename(&type), field->name);
499 /* Get the offset of the field */
500 if (tag == DW_TAG_union_type) {
503 ret = die_get_data_member_location(die_mem, &offs);
505 pr_warning("Failed to get the offset of %s.\n",
510 ref->offset += (long)offs;
511 ref->user_access = user_access;
513 /* If this member is unnamed, we need to reuse this field */
514 if (!dwarf_diename(die_mem))
515 return convert_variable_fields(die_mem, varname, field,
516 &ref, die_mem, user_access);
519 /* Converting next field */
521 return convert_variable_fields(die_mem, field->name,
522 field->next, &ref, die_mem, user_access);
527 /* Show a variables in kprobe event format */
528 static int convert_variable(Dwarf_Die *vr_die, struct probe_finder *pf)
533 pr_debug("Converting variable %s into trace event.\n",
534 dwarf_diename(vr_die));
536 ret = convert_variable_location(vr_die, pf->addr, pf->fb_ops,
537 &pf->sp_die, pf->machine, pf->tvar);
538 if (ret == -ENOENT || ret == -EINVAL) {
539 pr_err("Failed to find the location of the '%s' variable at this address.\n"
540 " Perhaps it has been optimized out.\n"
541 " Use -V with the --range option to show '%s' location range.\n",
542 pf->pvar->var, pf->pvar->var);
543 } else if (ret == -ENOTSUP)
544 pr_err("Sorry, we don't support this variable location yet.\n");
545 else if (ret == 0 && pf->pvar->field) {
546 ret = convert_variable_fields(vr_die, pf->pvar->var,
547 pf->pvar->field, &pf->tvar->ref,
548 &die_mem, pf->pvar->user_access);
552 ret = convert_variable_type(vr_die, pf->tvar, pf->pvar->type,
553 pf->pvar->user_access);
554 /* *expr will be cached in libdw. Don't free it. */
558 /* Find a variable in a scope DIE */
559 static int find_variable(Dwarf_Die *sc_die, struct probe_finder *pf)
565 /* Copy raw parameters */
566 if (!is_c_varname(pf->pvar->var))
567 return copy_to_probe_trace_arg(pf->tvar, pf->pvar);
570 pf->tvar->name = strdup(pf->pvar->name);
572 buf = synthesize_perf_probe_arg(pf->pvar);
575 ptr = strchr(buf, ':'); /* Change type separator to _ */
578 pf->tvar->name = buf;
580 if (pf->tvar->name == NULL)
583 pr_debug("Searching '%s' variable in context.\n", pf->pvar->var);
584 /* Search child die for local variables and parameters. */
585 if (!die_find_variable_at(sc_die, pf->pvar->var, pf->addr, &vr_die)) {
586 /* Search again in global variables */
587 if (!die_find_variable_at(&pf->cu_die, pf->pvar->var,
589 pr_warning("Failed to find '%s' in this function.\n",
595 ret = convert_variable(&vr_die, pf);
600 /* Convert subprogram DIE to trace point */
601 static int convert_to_trace_point(Dwarf_Die *sp_die, Dwfl_Module *mod,
602 Dwarf_Addr paddr, bool retprobe,
603 const char *function,
604 struct probe_trace_point *tp)
606 Dwarf_Addr eaddr, highaddr;
610 /* Verify the address is correct */
611 if (dwarf_entrypc(sp_die, &eaddr) != 0) {
612 pr_warning("Failed to get entry address of %s\n",
613 dwarf_diename(sp_die));
616 if (dwarf_highpc(sp_die, &highaddr) != 0) {
617 pr_warning("Failed to get end address of %s\n",
618 dwarf_diename(sp_die));
621 if (paddr > highaddr) {
622 pr_warning("Offset specified is greater than size of %s\n",
623 dwarf_diename(sp_die));
627 symbol = dwarf_diename(sp_die);
629 /* Try to get the symbol name from symtab */
630 symbol = dwfl_module_addrsym(mod, paddr, &sym, NULL);
632 pr_warning("Failed to find symbol at 0x%lx\n",
633 (unsigned long)paddr);
636 eaddr = sym.st_value;
638 tp->offset = (unsigned long)(paddr - eaddr);
639 tp->address = (unsigned long)paddr;
640 tp->symbol = strdup(symbol);
644 /* Return probe must be on the head of a subprogram */
646 if (eaddr != paddr) {
647 pr_warning("Failed to find \"%s%%return\",\n"
648 " because %s is an inlined function and"
649 " has no return point.\n", function,
659 /* Call probe_finder callback with scope DIE */
660 static int call_probe_finder(Dwarf_Die *sc_die, struct probe_finder *pf)
662 Dwarf_Attribute fb_attr;
663 Dwarf_Frame *frame = NULL;
668 pr_err("Caller must pass a scope DIE. Program error.\n");
672 /* If not a real subprogram, find a real one */
673 if (!die_is_func_def(sc_die)) {
674 if (!die_find_realfunc(&pf->cu_die, pf->addr, &pf->sp_die)) {
675 if (die_find_tailfunc(&pf->cu_die, pf->addr, &pf->sp_die)) {
676 pr_warning("Ignoring tail call from %s\n",
677 dwarf_diename(&pf->sp_die));
680 pr_warning("Failed to find probe point in any "
686 memcpy(&pf->sp_die, sc_die, sizeof(Dwarf_Die));
688 /* Get the frame base attribute/ops from subprogram */
689 dwarf_attr(&pf->sp_die, DW_AT_frame_base, &fb_attr);
690 ret = dwarf_getlocation_addr(&fb_attr, pf->addr, &pf->fb_ops, &nops, 1);
691 if (ret <= 0 || nops == 0) {
693 #if _ELFUTILS_PREREQ(0, 142)
694 } else if (nops == 1 && pf->fb_ops[0].atom == DW_OP_call_frame_cfa &&
695 (pf->cfi_eh != NULL || pf->cfi_dbg != NULL)) {
696 if ((dwarf_cfi_addrframe(pf->cfi_eh, pf->addr, &frame) != 0 &&
697 (dwarf_cfi_addrframe(pf->cfi_dbg, pf->addr, &frame) != 0)) ||
698 dwarf_frame_cfa(frame, &pf->fb_ops, &nops) != 0) {
699 pr_warning("Failed to get call frame on 0x%jx\n",
700 (uintmax_t)pf->addr);
707 /* Call finder's callback handler */
708 ret = pf->callback(sc_die, pf);
710 /* Since *pf->fb_ops can be a part of frame. we should free it here. */
717 struct find_scope_param {
718 const char *function;
726 static int find_best_scope_cb(Dwarf_Die *fn_die, void *data)
728 struct find_scope_param *fsp = data;
732 /* Skip if declared file name does not match */
734 file = dwarf_decl_file(fn_die);
735 if (!file || strcmp(fsp->file, file) != 0)
738 /* If the function name is given, that's what user expects */
740 if (die_match_name(fn_die, fsp->function)) {
741 memcpy(fsp->die_mem, fn_die, sizeof(Dwarf_Die));
746 /* With the line number, find the nearest declared DIE */
747 dwarf_decl_line(fn_die, &lno);
748 if (lno < fsp->line && fsp->diff > fsp->line - lno) {
749 /* Keep a candidate and continue */
750 fsp->diff = fsp->line - lno;
751 memcpy(fsp->die_mem, fn_die, sizeof(Dwarf_Die));
758 /* Find an appropriate scope fits to given conditions */
759 static Dwarf_Die *find_best_scope(struct probe_finder *pf, Dwarf_Die *die_mem)
761 struct find_scope_param fsp = {
762 .function = pf->pev->point.function,
770 cu_walk_functions_at(&pf->cu_die, pf->addr, find_best_scope_cb, &fsp);
772 return fsp.found ? die_mem : NULL;
775 static int probe_point_line_walker(const char *fname, int lineno,
776 Dwarf_Addr addr, void *data)
778 struct probe_finder *pf = data;
779 Dwarf_Die *sc_die, die_mem;
782 if (lineno != pf->lno || strtailcmp(fname, pf->fname) != 0)
786 sc_die = find_best_scope(pf, &die_mem);
788 pr_warning("Failed to find scope of probe point.\n");
792 ret = call_probe_finder(sc_die, pf);
794 /* Continue if no error, because the line will be in inline function */
795 return ret < 0 ? ret : 0;
798 /* Find probe point from its line number */
799 static int find_probe_point_by_line(struct probe_finder *pf)
801 return die_walk_lines(&pf->cu_die, probe_point_line_walker, pf);
804 /* Find lines which match lazy pattern */
805 static int find_lazy_match_lines(struct intlist *list,
806 const char *fname, const char *pat)
812 int count = 0, linenum = 1;
813 char sbuf[STRERR_BUFSIZE];
815 fp = fopen(fname, "r");
817 pr_warning("Failed to open %s: %s\n", fname,
818 str_error_r(errno, sbuf, sizeof(sbuf)));
822 while ((len = getline(&line, &line_len, fp)) > 0) {
824 if (line[len - 1] == '\n')
825 line[len - 1] = '\0';
827 if (strlazymatch(line, pat)) {
828 intlist__add(list, linenum);
840 pr_debug("No matched lines found in %s.\n", fname);
844 static int probe_point_lazy_walker(const char *fname, int lineno,
845 Dwarf_Addr addr, void *data)
847 struct probe_finder *pf = data;
848 Dwarf_Die *sc_die, die_mem;
851 if (!intlist__has_entry(pf->lcache, lineno) ||
852 strtailcmp(fname, pf->fname) != 0)
855 pr_debug("Probe line found: line:%d addr:0x%llx\n",
856 lineno, (unsigned long long)addr);
859 sc_die = find_best_scope(pf, &die_mem);
861 pr_warning("Failed to find scope of probe point.\n");
865 ret = call_probe_finder(sc_die, pf);
868 * Continue if no error, because the lazy pattern will match
871 return ret < 0 ? ret : 0;
874 /* Find probe points from lazy pattern */
875 static int find_probe_point_lazy(Dwarf_Die *sp_die, struct probe_finder *pf)
880 if (intlist__empty(pf->lcache)) {
881 const char *comp_dir;
883 comp_dir = cu_get_comp_dir(&pf->cu_die);
884 ret = get_real_path(pf->fname, comp_dir, &fpath);
886 pr_warning("Failed to find source file path.\n");
890 /* Matching lazy line pattern */
891 ret = find_lazy_match_lines(pf->lcache, fpath,
892 pf->pev->point.lazy_line);
898 return die_walk_lines(sp_die, probe_point_lazy_walker, pf);
901 static void skip_prologue(Dwarf_Die *sp_die, struct probe_finder *pf)
903 struct perf_probe_point *pp = &pf->pev->point;
906 if (!pf->pev->uprobes)
909 /* Compiled with optimization? */
910 if (die_is_optimized_target(&pf->cu_die))
913 /* Don't know entrypc? */
917 /* Only FUNC and FUNC@SRC are eligible. */
918 if (!pp->function || pp->line || pp->retprobe || pp->lazy_line ||
919 pp->offset || pp->abs_address)
922 /* Not interested in func parameter? */
923 if (!perf_probe_with_var(pf->pev))
926 pr_info("Target program is compiled without optimization. Skipping prologue.\n"
927 "Probe on address 0x%" PRIx64 " to force probing at the function entry.\n\n",
930 die_skip_prologue(sp_die, &pf->cu_die, &pf->addr);
933 static int probe_point_inline_cb(Dwarf_Die *in_die, void *data)
935 struct probe_finder *pf = data;
936 struct perf_probe_point *pp = &pf->pev->point;
941 ret = find_probe_point_lazy(in_die, pf);
943 /* Get probe address */
944 if (dwarf_entrypc(in_die, &addr) != 0) {
945 pr_warning("Failed to get entry address of %s.\n",
946 dwarf_diename(in_die));
950 pr_debug("%s has no valid entry address. skipped.\n",
951 dwarf_diename(in_die));
955 pf->addr += pp->offset;
956 pr_debug("found inline addr: 0x%jx\n",
957 (uintmax_t)pf->addr);
959 ret = call_probe_finder(in_die, pf);
965 /* Callback parameter with return value for libdw */
966 struct dwarf_callback_param {
971 /* Search function from function name */
972 static int probe_point_search_cb(Dwarf_Die *sp_die, void *data)
974 struct dwarf_callback_param *param = data;
975 struct probe_finder *pf = param->data;
976 struct perf_probe_point *pp = &pf->pev->point;
978 /* Check tag and diename */
979 if (!die_is_func_def(sp_die) ||
980 !die_match_name(sp_die, pp->function))
983 /* Check declared file */
984 if (pp->file && strtailcmp(pp->file, dwarf_decl_file(sp_die)))
987 pr_debug("Matched function: %s [%lx]\n", dwarf_diename(sp_die),
988 (unsigned long)dwarf_dieoffset(sp_die));
989 pf->fname = dwarf_decl_file(sp_die);
990 if (pp->line) { /* Function relative line */
991 dwarf_decl_line(sp_die, &pf->lno);
993 param->retval = find_probe_point_by_line(pf);
994 } else if (die_is_func_instance(sp_die)) {
995 /* Instances always have the entry address */
996 dwarf_entrypc(sp_die, &pf->addr);
997 /* But in some case the entry address is 0 */
999 pr_debug("%s has no entry PC. Skipped\n",
1000 dwarf_diename(sp_die));
1003 } else if (pp->lazy_line)
1004 param->retval = find_probe_point_lazy(sp_die, pf);
1006 skip_prologue(sp_die, pf);
1007 pf->addr += pp->offset;
1008 /* TODO: Check the address in this function */
1009 param->retval = call_probe_finder(sp_die, pf);
1011 } else if (!probe_conf.no_inlines) {
1012 /* Inlined function: search instances */
1013 param->retval = die_walk_instances(sp_die,
1014 probe_point_inline_cb, (void *)pf);
1015 /* This could be a non-existed inline definition */
1016 if (param->retval == -ENOENT)
1020 /* We need to find other candidates */
1021 if (strisglob(pp->function) && param->retval >= 0) {
1022 param->retval = 0; /* We have to clear the result */
1026 return DWARF_CB_ABORT; /* Exit; no same symbol in this CU. */
1029 static int find_probe_point_by_func(struct probe_finder *pf)
1031 struct dwarf_callback_param _param = {.data = (void *)pf,
1033 dwarf_getfuncs(&pf->cu_die, probe_point_search_cb, &_param, 0);
1034 return _param.retval;
1037 struct pubname_callback_param {
1045 static int pubname_search_cb(Dwarf *dbg, Dwarf_Global *gl, void *data)
1047 struct pubname_callback_param *param = data;
1049 if (dwarf_offdie(dbg, gl->die_offset, param->sp_die)) {
1050 if (dwarf_tag(param->sp_die) != DW_TAG_subprogram)
1053 if (die_match_name(param->sp_die, param->function)) {
1054 if (!dwarf_offdie(dbg, gl->cu_offset, param->cu_die))
1058 strtailcmp(param->file, dwarf_decl_file(param->sp_die)))
1062 return DWARF_CB_ABORT;
1069 static int debuginfo__find_probe_location(struct debuginfo *dbg,
1070 struct probe_finder *pf)
1072 struct perf_probe_point *pp = &pf->pev->point;
1073 Dwarf_Off off, noff;
1079 pf->lcache = intlist__new(NULL);
1083 /* Fastpath: lookup by function name from .debug_pubnames section */
1084 if (pp->function && !strisglob(pp->function)) {
1085 struct pubname_callback_param pubname_param = {
1086 .function = pp->function,
1088 .cu_die = &pf->cu_die,
1089 .sp_die = &pf->sp_die,
1092 struct dwarf_callback_param probe_param = {
1096 dwarf_getpubnames(dbg->dbg, pubname_search_cb,
1098 if (pubname_param.found) {
1099 ret = probe_point_search_cb(&pf->sp_die, &probe_param);
1105 /* Loop on CUs (Compilation Unit) */
1106 while (!dwarf_nextcu(dbg->dbg, off, &noff, &cuhl, NULL, NULL, NULL)) {
1107 /* Get the DIE(Debugging Information Entry) of this CU */
1108 diep = dwarf_offdie(dbg->dbg, off + cuhl, &pf->cu_die);
1112 /* Check if target file is included. */
1114 pf->fname = cu_find_realpath(&pf->cu_die, pp->file);
1118 if (!pp->file || pf->fname) {
1120 ret = find_probe_point_by_func(pf);
1121 else if (pp->lazy_line)
1122 ret = find_probe_point_lazy(&pf->cu_die, pf);
1125 ret = find_probe_point_by_line(pf);
1134 intlist__delete(pf->lcache);
1140 /* Find probe points from debuginfo */
1141 static int debuginfo__find_probes(struct debuginfo *dbg,
1142 struct probe_finder *pf)
1148 if (pf->cfi_eh || pf->cfi_dbg)
1149 return debuginfo__find_probe_location(dbg, pf);
1151 /* Get the call frame information from this dwarf */
1152 elf = dwarf_getelf(dbg->dbg);
1156 if (gelf_getehdr(elf, &ehdr) == NULL)
1159 pf->machine = ehdr.e_machine;
1161 #if _ELFUTILS_PREREQ(0, 142)
1165 if (elf_section_by_name(elf, &ehdr, &shdr, ".eh_frame", NULL) &&
1166 shdr.sh_type == SHT_PROGBITS)
1167 pf->cfi_eh = dwarf_getcfi_elf(elf);
1169 pf->cfi_dbg = dwarf_getcfi(dbg->dbg);
1173 ret = debuginfo__find_probe_location(dbg, pf);
1177 struct local_vars_finder {
1178 struct probe_finder *pf;
1179 struct perf_probe_arg *args;
1186 /* Collect available variables in this scope */
1187 static int copy_variables_cb(Dwarf_Die *die_mem, void *data)
1189 struct local_vars_finder *vf = data;
1190 struct probe_finder *pf = vf->pf;
1193 tag = dwarf_tag(die_mem);
1194 if (tag == DW_TAG_formal_parameter ||
1195 (tag == DW_TAG_variable && vf->vars)) {
1196 if (convert_variable_location(die_mem, vf->pf->addr,
1197 vf->pf->fb_ops, &pf->sp_die,
1198 pf->machine, NULL) == 0) {
1199 vf->args[vf->nargs].var = (char *)dwarf_diename(die_mem);
1200 if (vf->args[vf->nargs].var == NULL) {
1202 return DIE_FIND_CB_END;
1204 pr_debug(" %s", vf->args[vf->nargs].var);
1209 if (dwarf_haspc(die_mem, vf->pf->addr))
1210 return DIE_FIND_CB_CONTINUE;
1212 return DIE_FIND_CB_SIBLING;
1215 static int expand_probe_args(Dwarf_Die *sc_die, struct probe_finder *pf,
1216 struct perf_probe_arg *args)
1221 struct local_vars_finder vf = {.pf = pf, .args = args, .vars = false,
1222 .max_args = MAX_PROBE_ARGS, .ret = 0};
1224 for (i = 0; i < pf->pev->nargs; i++) {
1225 /* var never be NULL */
1226 if (strcmp(pf->pev->args[i].var, PROBE_ARG_VARS) == 0)
1228 else if (strcmp(pf->pev->args[i].var, PROBE_ARG_PARAMS) != 0) {
1229 /* Copy normal argument */
1230 args[n] = pf->pev->args[i];
1234 pr_debug("Expanding %s into:", pf->pev->args[i].var);
1236 /* Special local variables */
1237 die_find_child(sc_die, copy_variables_cb, (void *)&vf,
1239 pr_debug(" (%d)\n", vf.nargs - n);
1247 /* Add a found probe point into trace event list */
1248 static int add_probe_trace_event(Dwarf_Die *sc_die, struct probe_finder *pf)
1250 struct trace_event_finder *tf =
1251 container_of(pf, struct trace_event_finder, pf);
1252 struct perf_probe_point *pp = &pf->pev->point;
1253 struct probe_trace_event *tev;
1254 struct perf_probe_arg *args = NULL;
1257 /* Check number of tevs */
1258 if (tf->ntevs == tf->max_tevs) {
1259 pr_warning("Too many( > %d) probe point found.\n",
1263 tev = &tf->tevs[tf->ntevs++];
1265 /* Trace point should be converted from subprogram DIE */
1266 ret = convert_to_trace_point(&pf->sp_die, tf->mod, pf->addr,
1267 pp->retprobe, pp->function, &tev->point);
1271 tev->point.realname = strdup(dwarf_diename(sc_die));
1272 if (!tev->point.realname) {
1277 pr_debug("Probe point found: %s+%lu\n", tev->point.symbol,
1280 /* Expand special probe argument if exist */
1281 args = zalloc(sizeof(struct perf_probe_arg) * MAX_PROBE_ARGS);
1287 ret = expand_probe_args(sc_die, pf, args);
1292 tev->args = zalloc(sizeof(struct probe_trace_arg) * tev->nargs);
1293 if (tev->args == NULL) {
1298 /* Find each argument */
1299 for (i = 0; i < tev->nargs; i++) {
1300 pf->pvar = &args[i];
1301 pf->tvar = &tev->args[i];
1302 /* Variable should be found from scope DIE */
1303 ret = find_variable(sc_die, pf);
1310 clear_probe_trace_event(tev);
1317 /* Find probe_trace_events specified by perf_probe_event from debuginfo */
1318 int debuginfo__find_trace_events(struct debuginfo *dbg,
1319 struct perf_probe_event *pev,
1320 struct probe_trace_event **tevs)
1322 struct trace_event_finder tf = {
1323 .pf = {.pev = pev, .callback = add_probe_trace_event},
1324 .max_tevs = probe_conf.max_probes, .mod = dbg->mod};
1327 /* Allocate result tevs array */
1328 *tevs = zalloc(sizeof(struct probe_trace_event) * tf.max_tevs);
1335 ret = debuginfo__find_probes(dbg, &tf.pf);
1337 for (i = 0; i < tf.ntevs; i++)
1338 clear_probe_trace_event(&tf.tevs[i]);
1343 return (ret < 0) ? ret : tf.ntevs;
1346 /* Collect available variables in this scope */
1347 static int collect_variables_cb(Dwarf_Die *die_mem, void *data)
1349 struct available_var_finder *af = data;
1350 struct variable_list *vl;
1351 struct strbuf buf = STRBUF_INIT;
1354 vl = &af->vls[af->nvls - 1];
1356 tag = dwarf_tag(die_mem);
1357 if (tag == DW_TAG_formal_parameter ||
1358 tag == DW_TAG_variable) {
1359 ret = convert_variable_location(die_mem, af->pf.addr,
1360 af->pf.fb_ops, &af->pf.sp_die,
1361 af->pf.machine, NULL);
1362 if (ret == 0 || ret == -ERANGE) {
1364 bool externs = !af->child;
1366 if (strbuf_init(&buf, 64) < 0)
1369 if (probe_conf.show_location_range) {
1371 ret2 = strbuf_add(&buf,
1372 ret ? "[INV]\t" : "[VAL]\t", 6);
1374 ret2 = strbuf_add(&buf, "[EXT]\t", 6);
1379 ret2 = die_get_varname(die_mem, &buf);
1381 if (!ret2 && probe_conf.show_location_range &&
1383 if (strbuf_addch(&buf, '\t') < 0)
1385 ret2 = die_get_var_range(&af->pf.sp_die,
1389 pr_debug("Add new var: %s\n", buf.buf);
1391 strlist__add(vl->vars,
1392 strbuf_detach(&buf, NULL));
1394 strbuf_release(&buf);
1398 if (af->child && dwarf_haspc(die_mem, af->pf.addr))
1399 return DIE_FIND_CB_CONTINUE;
1401 return DIE_FIND_CB_SIBLING;
1403 strbuf_release(&buf);
1404 pr_debug("Error in strbuf\n");
1405 return DIE_FIND_CB_END;
1408 /* Add a found vars into available variables list */
1409 static int add_available_vars(Dwarf_Die *sc_die, struct probe_finder *pf)
1411 struct available_var_finder *af =
1412 container_of(pf, struct available_var_finder, pf);
1413 struct perf_probe_point *pp = &pf->pev->point;
1414 struct variable_list *vl;
1418 /* Check number of tevs */
1419 if (af->nvls == af->max_vls) {
1420 pr_warning("Too many( > %d) probe point found.\n", af->max_vls);
1423 vl = &af->vls[af->nvls++];
1425 /* Trace point should be converted from subprogram DIE */
1426 ret = convert_to_trace_point(&pf->sp_die, af->mod, pf->addr,
1427 pp->retprobe, pp->function, &vl->point);
1431 pr_debug("Probe point found: %s+%lu\n", vl->point.symbol,
1434 /* Find local variables */
1435 vl->vars = strlist__new(NULL, NULL);
1436 if (vl->vars == NULL)
1439 die_find_child(sc_die, collect_variables_cb, (void *)af, &die_mem);
1441 /* Find external variables */
1442 if (!probe_conf.show_ext_vars)
1444 /* Don't need to search child DIE for external vars. */
1446 die_find_child(&pf->cu_die, collect_variables_cb, (void *)af, &die_mem);
1449 if (strlist__empty(vl->vars)) {
1450 strlist__delete(vl->vars);
1458 * Find available variables at given probe point
1459 * Return the number of found probe points. Return 0 if there is no
1460 * matched probe point. Return <0 if an error occurs.
1462 int debuginfo__find_available_vars_at(struct debuginfo *dbg,
1463 struct perf_probe_event *pev,
1464 struct variable_list **vls)
1466 struct available_var_finder af = {
1467 .pf = {.pev = pev, .callback = add_available_vars},
1469 .max_vls = probe_conf.max_probes};
1472 /* Allocate result vls array */
1473 *vls = zalloc(sizeof(struct variable_list) * af.max_vls);
1480 ret = debuginfo__find_probes(dbg, &af.pf);
1482 /* Free vlist for error */
1484 zfree(&af.vls[af.nvls].point.symbol);
1485 strlist__delete(af.vls[af.nvls].vars);
1491 return (ret < 0) ? ret : af.nvls;
1494 /* For the kernel module, we need a special code to get a DIE */
1495 int debuginfo__get_text_offset(struct debuginfo *dbg, Dwarf_Addr *offs,
1502 GElf_Shdr mem, *shdr;
1505 elf = dwfl_module_getelf(dbg->mod, &dbg->bias);
1509 /* Get the number of relocations */
1510 n = dwfl_module_relocations(dbg->mod);
1513 /* Search the relocation related .text section */
1514 for (i = 0; i < n; i++) {
1515 p = dwfl_module_relocation_info(dbg->mod, i, &shndx);
1516 if (strcmp(p, ".text") == 0) {
1517 /* OK, get the section header */
1518 scn = elf_getscn(elf, shndx);
1521 shdr = gelf_getshdr(scn, &mem);
1524 *offs = shdr->sh_addr;
1526 *offs -= shdr->sh_offset;
1532 /* Reverse search */
1533 int debuginfo__find_probe_point(struct debuginfo *dbg, unsigned long addr,
1534 struct perf_probe_point *ppt)
1536 Dwarf_Die cudie, spdie, indie;
1537 Dwarf_Addr _addr = 0, baseaddr = 0;
1538 const char *fname = NULL, *func = NULL, *basefunc = NULL, *tmp;
1539 int baseline = 0, lineno = 0, ret = 0;
1541 /* We always need to relocate the address for aranges */
1542 if (debuginfo__get_text_offset(dbg, &baseaddr, false) == 0)
1545 if (!dwarf_addrdie(dbg->dbg, (Dwarf_Addr)addr, &cudie)) {
1546 pr_warning("Failed to find debug information for address %lx\n",
1552 /* Find a corresponding line (filename and lineno) */
1553 cu_find_lineinfo(&cudie, addr, &fname, &lineno);
1554 /* Don't care whether it failed or not */
1556 /* Find a corresponding function (name, baseline and baseaddr) */
1557 if (die_find_realfunc(&cudie, (Dwarf_Addr)addr, &spdie)) {
1558 /* Get function entry information */
1559 func = basefunc = dwarf_diename(&spdie);
1561 dwarf_entrypc(&spdie, &baseaddr) != 0 ||
1562 dwarf_decl_line(&spdie, &baseline) != 0) {
1567 fname = dwarf_decl_file(&spdie);
1568 if (addr == (unsigned long)baseaddr) {
1569 /* Function entry - Relative line number is 0 */
1574 /* Track down the inline functions step by step */
1575 while (die_find_top_inlinefunc(&spdie, (Dwarf_Addr)addr,
1577 /* There is an inline function */
1578 if (dwarf_entrypc(&indie, &_addr) == 0 &&
1581 * addr is at an inline function entry.
1582 * In this case, lineno should be the call-site
1583 * line number. (overwrite lineinfo)
1585 lineno = die_get_call_lineno(&indie);
1586 fname = die_get_call_file(&indie);
1590 * addr is in an inline function body.
1591 * Since lineno points one of the lines
1592 * of the inline function, baseline should
1593 * be the entry line of the inline function.
1595 tmp = dwarf_diename(&indie);
1597 dwarf_decl_line(&indie, &baseline) != 0)
1603 /* Verify the lineno and baseline are in a same file */
1604 tmp = dwarf_decl_file(&spdie);
1605 if (!tmp || strcmp(tmp, fname) != 0)
1610 /* Make a relative line number or an offset */
1612 ppt->line = lineno - baseline;
1613 else if (basefunc) {
1614 ppt->offset = addr - (unsigned long)baseaddr;
1618 /* Duplicate strings */
1620 ppt->function = strdup(func);
1621 if (ppt->function == NULL) {
1627 ppt->file = strdup(fname);
1628 if (ppt->file == NULL) {
1629 zfree(&ppt->function);
1635 if (ret == 0 && (fname || func))
1636 ret = 1; /* Found a point */
1640 /* Add a line and store the src path */
1641 static int line_range_add_line(const char *src, unsigned int lineno,
1642 struct line_range *lr)
1644 /* Copy source path */
1646 lr->path = strdup(src);
1647 if (lr->path == NULL)
1650 return intlist__add(lr->line_list, lineno);
1653 static int line_range_walk_cb(const char *fname, int lineno,
1654 Dwarf_Addr addr __maybe_unused,
1657 struct line_finder *lf = data;
1660 if ((strtailcmp(fname, lf->fname) != 0) ||
1661 (lf->lno_s > lineno || lf->lno_e < lineno))
1664 err = line_range_add_line(fname, lineno, lf->lr);
1665 if (err < 0 && err != -EEXIST)
1671 /* Find line range from its line number */
1672 static int find_line_range_by_line(Dwarf_Die *sp_die, struct line_finder *lf)
1676 ret = die_walk_lines(sp_die ?: &lf->cu_die, line_range_walk_cb, lf);
1680 if (!intlist__empty(lf->lr->line_list))
1681 ret = lf->found = 1;
1683 ret = 0; /* Lines are not found */
1685 zfree(&lf->lr->path);
1690 static int line_range_inline_cb(Dwarf_Die *in_die, void *data)
1692 int ret = find_line_range_by_line(in_die, data);
1695 * We have to check all instances of inlined function, because
1696 * some execution paths can be optimized out depends on the
1697 * function argument of instances. However, if an error occurs,
1698 * it should be handled by the caller.
1700 return ret < 0 ? ret : 0;
1703 /* Search function definition from function name */
1704 static int line_range_search_cb(Dwarf_Die *sp_die, void *data)
1706 struct dwarf_callback_param *param = data;
1707 struct line_finder *lf = param->data;
1708 struct line_range *lr = lf->lr;
1710 /* Check declared file */
1711 if (lr->file && strtailcmp(lr->file, dwarf_decl_file(sp_die)))
1714 if (die_is_func_def(sp_die) &&
1715 die_match_name(sp_die, lr->function)) {
1716 lf->fname = dwarf_decl_file(sp_die);
1717 dwarf_decl_line(sp_die, &lr->offset);
1718 pr_debug("fname: %s, lineno:%d\n", lf->fname, lr->offset);
1719 lf->lno_s = lr->offset + lr->start;
1720 if (lf->lno_s < 0) /* Overflow */
1721 lf->lno_s = INT_MAX;
1722 lf->lno_e = lr->offset + lr->end;
1723 if (lf->lno_e < 0) /* Overflow */
1724 lf->lno_e = INT_MAX;
1725 pr_debug("New line range: %d to %d\n", lf->lno_s, lf->lno_e);
1726 lr->start = lf->lno_s;
1727 lr->end = lf->lno_e;
1728 if (!die_is_func_instance(sp_die))
1729 param->retval = die_walk_instances(sp_die,
1730 line_range_inline_cb, lf);
1732 param->retval = find_line_range_by_line(sp_die, lf);
1733 return DWARF_CB_ABORT;
1738 static int find_line_range_by_func(struct line_finder *lf)
1740 struct dwarf_callback_param param = {.data = (void *)lf, .retval = 0};
1741 dwarf_getfuncs(&lf->cu_die, line_range_search_cb, ¶m, 0);
1742 return param.retval;
1745 int debuginfo__find_line_range(struct debuginfo *dbg, struct line_range *lr)
1747 struct line_finder lf = {.lr = lr, .found = 0};
1749 Dwarf_Off off = 0, noff;
1752 const char *comp_dir;
1754 /* Fastpath: lookup by function name from .debug_pubnames section */
1756 struct pubname_callback_param pubname_param = {
1757 .function = lr->function, .file = lr->file,
1758 .cu_die = &lf.cu_die, .sp_die = &lf.sp_die, .found = 0};
1759 struct dwarf_callback_param line_range_param = {
1760 .data = (void *)&lf, .retval = 0};
1762 dwarf_getpubnames(dbg->dbg, pubname_search_cb,
1764 if (pubname_param.found) {
1765 line_range_search_cb(&lf.sp_die, &line_range_param);
1771 /* Loop on CUs (Compilation Unit) */
1772 while (!lf.found && ret >= 0) {
1773 if (dwarf_nextcu(dbg->dbg, off, &noff, &cuhl,
1774 NULL, NULL, NULL) != 0)
1777 /* Get the DIE(Debugging Information Entry) of this CU */
1778 diep = dwarf_offdie(dbg->dbg, off + cuhl, &lf.cu_die);
1782 /* Check if target file is included. */
1784 lf.fname = cu_find_realpath(&lf.cu_die, lr->file);
1788 if (!lr->file || lf.fname) {
1790 ret = find_line_range_by_func(&lf);
1792 lf.lno_s = lr->start;
1794 ret = find_line_range_by_line(NULL, &lf);
1801 /* Store comp_dir */
1803 comp_dir = cu_get_comp_dir(&lf.cu_die);
1805 lr->comp_dir = strdup(comp_dir);
1811 pr_debug("path: %s\n", lr->path);
1812 return (ret < 0) ? ret : lf.found;
1816 * Find a src file from a DWARF tag path. Prepend optional source path prefix
1817 * and chop off leading directories that do not exist. Result is passed back as
1818 * a newly allocated path on success.
1819 * Return 0 if file was found and readable, -errno otherwise.
1821 int get_real_path(const char *raw_path, const char *comp_dir,
1824 const char *prefix = symbol_conf.source_prefix;
1827 if (raw_path[0] != '/' && comp_dir)
1828 /* If not an absolute path, try to use comp_dir */
1831 if (access(raw_path, R_OK) == 0) {
1832 *new_path = strdup(raw_path);
1833 return *new_path ? 0 : -ENOMEM;
1839 *new_path = malloc((strlen(prefix) + strlen(raw_path) + 2));
1844 sprintf(*new_path, "%s/%s", prefix, raw_path);
1846 if (access(*new_path, R_OK) == 0)
1849 if (!symbol_conf.source_prefix) {
1850 /* In case of searching comp_dir, don't retry */
1860 raw_path = strchr(++raw_path, '/');