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>
26 #include "debuginfo.h"
31 #include "probe-finder.h"
32 #include "probe-file.h"
35 /* Kprobe tracer basic type is up to u64 */
36 #define MAX_BASIC_TYPE_BITS 64
39 * Probe finder related functions
42 static struct probe_trace_arg_ref *alloc_trace_arg_ref(long offs)
44 struct probe_trace_arg_ref *ref;
45 ref = zalloc(sizeof(struct probe_trace_arg_ref));
52 * Convert a location into trace_arg.
53 * If tvar == NULL, this just checks variable can be converted.
54 * If fentry == true and vr_die is a parameter, do heuristic search
55 * for the location fuzzed by function entry mcount.
57 static int convert_variable_location(Dwarf_Die *vr_die, Dwarf_Addr addr,
58 Dwarf_Op *fb_ops, Dwarf_Die *sp_die,
60 struct probe_trace_arg *tvar)
72 if (dwarf_attr(vr_die, DW_AT_external, &attr) != NULL)
76 if (dwarf_attr(vr_die, DW_AT_const_value, &attr) &&
77 immediate_value_is_supported()) {
83 dwarf_formsdata(&attr, &snum);
84 ret = asprintf(&tvar->value, "\\%ld", (long)snum);
86 return ret < 0 ? -ENOMEM : 0;
89 /* TODO: handle more than 1 exprs */
90 if (dwarf_attr(vr_die, DW_AT_location, &attr) == NULL)
91 return -EINVAL; /* Broken DIE ? */
92 if (dwarf_getlocation_addr(&attr, addr, &op, &nops, 1) <= 0) {
93 ret = dwarf_entrypc(sp_die, &tmp);
97 if (probe_conf.show_location_range &&
98 (dwarf_tag(vr_die) == DW_TAG_variable)) {
100 } else if (addr != tmp ||
101 dwarf_tag(vr_die) != DW_TAG_formal_parameter) {
105 ret = dwarf_highpc(sp_die, &tmp);
109 * This is fuzzed by fentry mcount. We try to find the
110 * parameter location at the earliest address.
112 for (addr += 1; addr <= tmp; addr++) {
113 if (dwarf_getlocation_addr(&attr, addr, &op,
121 /* TODO: Support const_value */
124 if (op->atom == DW_OP_addr) {
128 /* Static variables on memory (not stack), make @varname */
129 ret = strlen(dwarf_diename(vr_die));
130 tvar->value = zalloc(ret + 2);
131 if (tvar->value == NULL)
133 snprintf(tvar->value, ret + 2, "@%s", dwarf_diename(vr_die));
134 tvar->ref = alloc_trace_arg_ref((long)offs);
135 if (tvar->ref == NULL)
140 /* If this is based on frame buffer, set the offset */
141 if (op->atom == DW_OP_fbreg) {
149 if (op->atom >= DW_OP_breg0 && op->atom <= DW_OP_breg31) {
150 regn = op->atom - DW_OP_breg0;
153 } else if (op->atom >= DW_OP_reg0 && op->atom <= DW_OP_reg31) {
154 regn = op->atom - DW_OP_reg0;
155 } else if (op->atom == DW_OP_bregx) {
159 } else if (op->atom == DW_OP_regx) {
162 pr_debug("DW_OP %x is not supported.\n", op->atom);
169 regs = get_dwarf_regstr(regn, machine);
171 /* This should be a bug in DWARF or this tool */
172 pr_warning("Mapping for the register number %u "
173 "missing on this architecture.\n", regn);
177 tvar->value = strdup(regs);
178 if (tvar->value == NULL)
182 tvar->ref = alloc_trace_arg_ref((long)offs);
183 if (tvar->ref == NULL)
189 static int convert_variable_type(Dwarf_Die *vr_die,
190 struct probe_trace_arg *tvar,
191 const char *cast, bool user_access)
193 struct probe_trace_arg_ref **ref_ptr = &tvar->ref;
196 char sbuf[STRERR_BUFSIZE];
197 int bsize, boffs, total;
201 /* TODO: check all types */
202 if (cast && strcmp(cast, "string") != 0 && strcmp(cast, "ustring") &&
203 strcmp(cast, "x") != 0 &&
204 strcmp(cast, "s") != 0 && strcmp(cast, "u") != 0) {
205 /* Non string type is OK */
206 /* and respect signedness/hexadecimal cast */
207 tvar->type = strdup(cast);
208 return (tvar->type == NULL) ? -ENOMEM : 0;
211 bsize = dwarf_bitsize(vr_die);
213 /* This is a bitfield */
214 boffs = dwarf_bitoffset(vr_die);
215 total = dwarf_bytesize(vr_die);
216 if (boffs < 0 || total < 0)
218 ret = snprintf(buf, 16, "b%d@%d/%d", bsize, boffs,
219 BYTES_TO_BITS(total));
223 if (die_get_real_type(vr_die, &type) == NULL) {
224 pr_warning("Failed to get a type information of %s.\n",
225 dwarf_diename(vr_die));
229 pr_debug("%s type is %s.\n",
230 dwarf_diename(vr_die), dwarf_diename(&type));
232 if (cast && (!strcmp(cast, "string") || !strcmp(cast, "ustring"))) {
234 ret = dwarf_tag(&type);
235 if (ret != DW_TAG_pointer_type &&
236 ret != DW_TAG_array_type) {
237 pr_warning("Failed to cast into string: "
238 "%s(%s) is not a pointer nor array.\n",
239 dwarf_diename(vr_die), dwarf_diename(&type));
242 if (die_get_real_type(&type, &type) == NULL) {
243 pr_warning("Failed to get a type"
247 if (ret == DW_TAG_pointer_type) {
249 ref_ptr = &(*ref_ptr)->next;
250 /* Add new reference with offset +0 */
251 *ref_ptr = zalloc(sizeof(struct probe_trace_arg_ref));
252 if (*ref_ptr == NULL) {
253 pr_warning("Out of memory error\n");
256 (*ref_ptr)->user_access = user_access;
258 if (!die_compare_name(&type, "char") &&
259 !die_compare_name(&type, "unsigned char")) {
260 pr_warning("Failed to cast into string: "
261 "%s is not (unsigned) char *.\n",
262 dwarf_diename(vr_die));
265 tvar->type = strdup(cast);
266 return (tvar->type == NULL) ? -ENOMEM : 0;
269 if (cast && (strcmp(cast, "u") == 0))
271 else if (cast && (strcmp(cast, "s") == 0))
273 else if (cast && (strcmp(cast, "x") == 0) &&
274 probe_type_is_available(PROBE_TYPE_X))
277 prefix = die_is_signed_type(&type) ? 's' :
278 probe_type_is_available(PROBE_TYPE_X) ? 'x' : 'u';
280 ret = dwarf_bytesize(&type);
282 /* No size ... try to use default type */
284 ret = BYTES_TO_BITS(ret);
286 /* Check the bitwidth */
287 if (ret > MAX_BASIC_TYPE_BITS) {
288 pr_info("%s exceeds max-bitwidth. Cut down to %d bits.\n",
289 dwarf_diename(&type), MAX_BASIC_TYPE_BITS);
290 ret = MAX_BASIC_TYPE_BITS;
292 ret = snprintf(buf, 16, "%c%d", prefix, ret);
295 if (ret < 0 || ret >= 16) {
298 pr_warning("Failed to convert variable type: %s\n",
299 str_error_r(-ret, sbuf, sizeof(sbuf)));
302 tvar->type = strdup(buf);
303 if (tvar->type == NULL)
308 static int convert_variable_fields(Dwarf_Die *vr_die, const char *varname,
309 struct perf_probe_arg_field *field,
310 struct probe_trace_arg_ref **ref_ptr,
311 Dwarf_Die *die_mem, bool user_access)
313 struct probe_trace_arg_ref *ref = *ref_ptr;
318 pr_debug("converting %s in %s\n", field->name, varname);
319 if (die_get_real_type(vr_die, &type) == NULL) {
320 pr_warning("Failed to get the type of %s.\n", varname);
323 pr_debug2("Var real type: %s (%x)\n", dwarf_diename(&type),
324 (unsigned)dwarf_dieoffset(&type));
325 tag = dwarf_tag(&type);
327 if (field->name[0] == '[' &&
328 (tag == DW_TAG_array_type || tag == DW_TAG_pointer_type)) {
329 /* Save original type for next field or type */
330 memcpy(die_mem, &type, sizeof(*die_mem));
331 /* Get the type of this array */
332 if (die_get_real_type(&type, &type) == NULL) {
333 pr_warning("Failed to get the type of %s.\n", varname);
336 pr_debug2("Array real type: %s (%x)\n", dwarf_diename(&type),
337 (unsigned)dwarf_dieoffset(&type));
338 if (tag == DW_TAG_pointer_type) {
339 ref = zalloc(sizeof(struct probe_trace_arg_ref));
343 (*ref_ptr)->next = ref;
347 ref->offset += dwarf_bytesize(&type) * field->index;
348 ref->user_access = user_access;
350 } else if (tag == DW_TAG_pointer_type) {
351 /* Check the pointer and dereference */
353 pr_err("Semantic error: %s must be referred by '->'\n",
357 /* Get the type pointed by this pointer */
358 if (die_get_real_type(&type, &type) == NULL) {
359 pr_warning("Failed to get the type of %s.\n", varname);
362 /* Verify it is a data structure */
363 tag = dwarf_tag(&type);
364 if (tag != DW_TAG_structure_type && tag != DW_TAG_union_type) {
365 pr_warning("%s is not a data structure nor a union.\n",
370 ref = zalloc(sizeof(struct probe_trace_arg_ref));
374 (*ref_ptr)->next = ref;
378 /* Verify it is a data structure */
379 if (tag != DW_TAG_structure_type && tag != DW_TAG_union_type) {
380 pr_warning("%s is not a data structure nor a union.\n",
384 if (field->name[0] == '[') {
385 pr_err("Semantic error: %s is not a pointer"
386 " nor array.\n", varname);
389 /* While processing unnamed field, we don't care about this */
390 if (field->ref && dwarf_diename(vr_die)) {
391 pr_err("Semantic error: %s must be referred by '.'\n",
396 pr_warning("Structure on a register is not "
402 if (die_find_member(&type, field->name, die_mem) == NULL) {
403 pr_warning("%s(type:%s) has no member %s.\n", varname,
404 dwarf_diename(&type), field->name);
408 /* Get the offset of the field */
409 if (tag == DW_TAG_union_type) {
412 ret = die_get_data_member_location(die_mem, &offs);
414 pr_warning("Failed to get the offset of %s.\n",
419 ref->offset += (long)offs;
420 ref->user_access = user_access;
422 /* If this member is unnamed, we need to reuse this field */
423 if (!dwarf_diename(die_mem))
424 return convert_variable_fields(die_mem, varname, field,
425 &ref, die_mem, user_access);
428 /* Converting next field */
430 return convert_variable_fields(die_mem, field->name,
431 field->next, &ref, die_mem, user_access);
436 static void print_var_not_found(const char *varname)
438 pr_err("Failed to find the location of the '%s' variable at this address.\n"
439 " Perhaps it has been optimized out.\n"
440 " Use -V with the --range option to show '%s' location range.\n",
444 /* Show a variables in kprobe event format */
445 static int convert_variable(Dwarf_Die *vr_die, struct probe_finder *pf)
450 pr_debug("Converting variable %s into trace event.\n",
451 dwarf_diename(vr_die));
453 ret = convert_variable_location(vr_die, pf->addr, pf->fb_ops,
454 &pf->sp_die, pf->machine, pf->tvar);
455 if (ret == -ENOENT && pf->skip_empty_arg)
456 /* This can be found in other place. skip it */
458 if (ret == -ENOENT || ret == -EINVAL) {
459 print_var_not_found(pf->pvar->var);
460 } else if (ret == -ENOTSUP)
461 pr_err("Sorry, we don't support this variable location yet.\n");
462 else if (ret == 0 && pf->pvar->field) {
463 ret = convert_variable_fields(vr_die, pf->pvar->var,
464 pf->pvar->field, &pf->tvar->ref,
465 &die_mem, pf->pvar->user_access);
469 ret = convert_variable_type(vr_die, pf->tvar, pf->pvar->type,
470 pf->pvar->user_access);
471 /* *expr will be cached in libdw. Don't free it. */
475 /* Find a variable in a scope DIE */
476 static int find_variable(Dwarf_Die *sc_die, struct probe_finder *pf)
482 /* Copy raw parameters */
483 if (!is_c_varname(pf->pvar->var))
484 return copy_to_probe_trace_arg(pf->tvar, pf->pvar);
487 pf->tvar->name = strdup(pf->pvar->name);
489 buf = synthesize_perf_probe_arg(pf->pvar);
492 ptr = strchr(buf, ':'); /* Change type separator to _ */
495 pf->tvar->name = buf;
497 if (pf->tvar->name == NULL)
500 pr_debug("Searching '%s' variable in context.\n", pf->pvar->var);
501 /* Search child die for local variables and parameters. */
502 if (!die_find_variable_at(sc_die, pf->pvar->var, pf->addr, &vr_die)) {
503 /* Search again in global variables */
504 if (!die_find_variable_at(&pf->cu_die, pf->pvar->var,
506 if (pf->skip_empty_arg)
508 pr_warning("Failed to find '%s' in this function.\n",
514 ret = convert_variable(&vr_die, pf);
519 /* Convert subprogram DIE to trace point */
520 static int convert_to_trace_point(Dwarf_Die *sp_die, Dwfl_Module *mod,
521 Dwarf_Addr paddr, bool retprobe,
522 const char *function,
523 struct probe_trace_point *tp)
529 /* Verify the address is correct */
530 if (!dwarf_haspc(sp_die, paddr)) {
531 pr_warning("Specified offset is out of %s\n",
532 dwarf_diename(sp_die));
536 if (dwarf_entrypc(sp_die, &eaddr) == 0) {
537 /* If the DIE has entrypc, use it. */
538 symbol = dwarf_diename(sp_die);
540 /* Try to get actual symbol name and address from symtab */
541 symbol = dwfl_module_addrsym(mod, paddr, &sym, NULL);
542 eaddr = sym.st_value;
545 pr_warning("Failed to find symbol at 0x%lx\n",
546 (unsigned long)paddr);
550 tp->offset = (unsigned long)(paddr - eaddr);
552 tp->symbol = strdup(symbol);
556 /* Return probe must be on the head of a subprogram */
558 if (eaddr != paddr) {
559 pr_warning("Failed to find \"%s%%return\",\n"
560 " because %s is an inlined function and"
561 " has no return point.\n", function,
571 /* Call probe_finder callback with scope DIE */
572 static int call_probe_finder(Dwarf_Die *sc_die, struct probe_finder *pf)
574 Dwarf_Attribute fb_attr;
575 Dwarf_Frame *frame = NULL;
580 pr_err("Caller must pass a scope DIE. Program error.\n");
584 /* If not a real subprogram, find a real one */
585 if (!die_is_func_def(sc_die)) {
586 if (!die_find_realfunc(&pf->cu_die, pf->addr, &pf->sp_die)) {
587 if (die_find_tailfunc(&pf->cu_die, pf->addr, &pf->sp_die)) {
588 pr_warning("Ignoring tail call from %s\n",
589 dwarf_diename(&pf->sp_die));
592 pr_warning("Failed to find probe point in any "
598 memcpy(&pf->sp_die, sc_die, sizeof(Dwarf_Die));
600 /* Get the frame base attribute/ops from subprogram */
601 dwarf_attr(&pf->sp_die, DW_AT_frame_base, &fb_attr);
602 ret = dwarf_getlocation_addr(&fb_attr, pf->addr, &pf->fb_ops, &nops, 1);
603 if (ret <= 0 || nops == 0) {
605 #ifdef HAVE_DWARF_CFI_SUPPORT
606 } else if (nops == 1 && pf->fb_ops[0].atom == DW_OP_call_frame_cfa &&
607 (pf->cfi_eh != NULL || pf->cfi_dbg != NULL)) {
608 if ((dwarf_cfi_addrframe(pf->cfi_eh, pf->addr, &frame) != 0 &&
609 (dwarf_cfi_addrframe(pf->cfi_dbg, pf->addr, &frame) != 0)) ||
610 dwarf_frame_cfa(frame, &pf->fb_ops, &nops) != 0) {
611 pr_warning("Failed to get call frame on 0x%jx\n",
612 (uintmax_t)pf->addr);
616 #endif /* HAVE_DWARF_CFI_SUPPORT */
619 /* Call finder's callback handler */
620 ret = pf->callback(sc_die, pf);
622 /* Since *pf->fb_ops can be a part of frame. we should free it here. */
629 struct find_scope_param {
630 const char *function;
638 static int find_best_scope_cb(Dwarf_Die *fn_die, void *data)
640 struct find_scope_param *fsp = data;
644 /* Skip if declared file name does not match */
646 file = die_get_decl_file(fn_die);
647 if (!file || strcmp(fsp->file, file) != 0)
650 /* If the function name is given, that's what user expects */
652 if (die_match_name(fn_die, fsp->function)) {
653 memcpy(fsp->die_mem, fn_die, sizeof(Dwarf_Die));
658 /* With the line number, find the nearest declared DIE */
659 dwarf_decl_line(fn_die, &lno);
660 if (lno < fsp->line && fsp->diff > fsp->line - lno) {
661 /* Keep a candidate and continue */
662 fsp->diff = fsp->line - lno;
663 memcpy(fsp->die_mem, fn_die, sizeof(Dwarf_Die));
670 /* Return innermost DIE */
671 static int find_inner_scope_cb(Dwarf_Die *fn_die, void *data)
673 struct find_scope_param *fsp = data;
675 memcpy(fsp->die_mem, fn_die, sizeof(Dwarf_Die));
680 /* Find an appropriate scope fits to given conditions */
681 static Dwarf_Die *find_best_scope(struct probe_finder *pf, Dwarf_Die *die_mem)
683 struct find_scope_param fsp = {
684 .function = pf->pev->point.function,
693 ret = cu_walk_functions_at(&pf->cu_die, pf->addr, find_best_scope_cb,
695 if (!ret && !fsp.found)
696 cu_walk_functions_at(&pf->cu_die, pf->addr,
697 find_inner_scope_cb, &fsp);
699 return fsp.found ? die_mem : NULL;
702 static int verify_representive_line(struct probe_finder *pf, const char *fname,
703 int lineno, Dwarf_Addr addr)
705 const char *__fname, *__func = NULL;
709 /* Verify line number and address by reverse search */
710 if (cu_find_lineinfo(&pf->cu_die, addr, &__fname, &__lineno) < 0)
713 pr_debug2("Reversed line: %s:%d\n", __fname, __lineno);
714 if (strcmp(fname, __fname) || lineno == __lineno)
717 pr_warning("This line is sharing the address with other lines.\n");
719 if (pf->pev->point.function) {
720 /* Find best match function name and lines */
722 if (find_best_scope(pf, &die_mem)
723 && die_match_name(&die_mem, pf->pev->point.function)
724 && dwarf_decl_line(&die_mem, &lineno) == 0) {
725 __func = dwarf_diename(&die_mem);
729 pr_warning("Please try to probe at %s:%d instead.\n",
730 __func ? : __fname, __lineno);
735 static int probe_point_line_walker(const char *fname, int lineno,
736 Dwarf_Addr addr, void *data)
738 struct probe_finder *pf = data;
739 Dwarf_Die *sc_die, die_mem;
742 if (lineno != pf->lno || strtailcmp(fname, pf->fname) != 0)
745 if (verify_representive_line(pf, fname, lineno, addr))
749 sc_die = find_best_scope(pf, &die_mem);
751 pr_warning("Failed to find scope of probe point.\n");
755 ret = call_probe_finder(sc_die, pf);
757 /* Continue if no error, because the line will be in inline function */
758 return ret < 0 ? ret : 0;
761 /* Find probe point from its line number */
762 static int find_probe_point_by_line(struct probe_finder *pf)
764 return die_walk_lines(&pf->cu_die, probe_point_line_walker, pf);
767 /* Find lines which match lazy pattern */
768 static int find_lazy_match_lines(struct intlist *list,
769 const char *fname, const char *pat)
775 int count = 0, linenum = 1;
776 char sbuf[STRERR_BUFSIZE];
778 fp = fopen(fname, "r");
780 pr_warning("Failed to open %s: %s\n", fname,
781 str_error_r(errno, sbuf, sizeof(sbuf)));
785 while ((len = getline(&line, &line_len, fp)) > 0) {
787 if (line[len - 1] == '\n')
788 line[len - 1] = '\0';
790 if (strlazymatch(line, pat)) {
791 intlist__add(list, linenum);
803 pr_debug("No matched lines found in %s.\n", fname);
807 static int probe_point_lazy_walker(const char *fname, int lineno,
808 Dwarf_Addr addr, void *data)
810 struct probe_finder *pf = data;
811 Dwarf_Die *sc_die, die_mem;
814 if (!intlist__has_entry(pf->lcache, lineno) ||
815 strtailcmp(fname, pf->fname) != 0)
818 pr_debug("Probe line found: line:%d addr:0x%llx\n",
819 lineno, (unsigned long long)addr);
822 sc_die = find_best_scope(pf, &die_mem);
824 pr_warning("Failed to find scope of probe point.\n");
828 ret = call_probe_finder(sc_die, pf);
831 * Continue if no error, because the lazy pattern will match
834 return ret < 0 ? ret : 0;
837 /* Find probe points from lazy pattern */
838 static int find_probe_point_lazy(Dwarf_Die *sp_die, struct probe_finder *pf)
841 char sbuild_id[SBUILD_ID_SIZE] = "";
845 if (intlist__empty(pf->lcache)) {
846 const char *comp_dir;
848 comp_dir = cu_get_comp_dir(&pf->cu_die);
849 if (pf->dbg->build_id) {
850 build_id__init(&bid, pf->dbg->build_id, BUILD_ID_SIZE);
851 build_id__sprintf(&bid, sbuild_id);
853 ret = find_source_path(pf->fname, sbuild_id, comp_dir, &fpath);
855 pr_warning("Failed to find source file path.\n");
859 /* Matching lazy line pattern */
860 ret = find_lazy_match_lines(pf->lcache, fpath,
861 pf->pev->point.lazy_line);
867 return die_walk_lines(sp_die, probe_point_lazy_walker, pf);
870 static void skip_prologue(Dwarf_Die *sp_die, struct probe_finder *pf)
872 struct perf_probe_point *pp = &pf->pev->point;
875 if (!pf->pev->uprobes)
878 /* Compiled with optimization? */
879 if (die_is_optimized_target(&pf->cu_die))
882 /* Don't know entrypc? */
886 /* Only FUNC and FUNC@SRC are eligible. */
887 if (!pp->function || pp->line || pp->retprobe || pp->lazy_line ||
888 pp->offset || pp->abs_address)
891 /* Not interested in func parameter? */
892 if (!perf_probe_with_var(pf->pev))
895 pr_info("Target program is compiled without optimization. Skipping prologue.\n"
896 "Probe on address 0x%" PRIx64 " to force probing at the function entry.\n\n",
899 die_skip_prologue(sp_die, &pf->cu_die, &pf->addr);
902 static int probe_point_inline_cb(Dwarf_Die *in_die, void *data)
904 struct probe_finder *pf = data;
905 struct perf_probe_point *pp = &pf->pev->point;
910 ret = find_probe_point_lazy(in_die, pf);
912 /* Get probe address */
913 if (die_entrypc(in_die, &addr) != 0) {
914 pr_warning("Failed to get entry address of %s.\n",
915 dwarf_diename(in_die));
919 pr_debug("%s has no valid entry address. skipped.\n",
920 dwarf_diename(in_die));
924 pf->addr += pp->offset;
925 pr_debug("found inline addr: 0x%jx\n",
926 (uintmax_t)pf->addr);
928 ret = call_probe_finder(in_die, pf);
934 /* Callback parameter with return value for libdw */
935 struct dwarf_callback_param {
940 /* Search function from function name */
941 static int probe_point_search_cb(Dwarf_Die *sp_die, void *data)
943 struct dwarf_callback_param *param = data;
944 struct probe_finder *pf = param->data;
945 struct perf_probe_point *pp = &pf->pev->point;
948 /* Check tag and diename */
949 if (!die_is_func_def(sp_die) ||
950 !die_match_name(sp_die, pp->function))
953 /* Check declared file */
954 fname = die_get_decl_file(sp_die);
956 pr_warning("A function DIE doesn't have decl_line. Maybe broken DWARF?\n");
959 if (pp->file && fname && strtailcmp(pp->file, fname))
962 pr_debug("Matched function: %s [%lx]\n", dwarf_diename(sp_die),
963 (unsigned long)dwarf_dieoffset(sp_die));
965 if (pp->line) { /* Function relative line */
966 dwarf_decl_line(sp_die, &pf->lno);
968 param->retval = find_probe_point_by_line(pf);
969 } else if (die_is_func_instance(sp_die)) {
970 /* Instances always have the entry address */
971 die_entrypc(sp_die, &pf->addr);
972 /* But in some case the entry address is 0 */
974 pr_debug("%s has no entry PC. Skipped\n",
975 dwarf_diename(sp_die));
978 } else if (pp->lazy_line)
979 param->retval = find_probe_point_lazy(sp_die, pf);
981 skip_prologue(sp_die, pf);
982 pf->addr += pp->offset;
983 /* TODO: Check the address in this function */
984 param->retval = call_probe_finder(sp_die, pf);
986 } else if (!probe_conf.no_inlines) {
987 /* Inlined function: search instances */
988 param->retval = die_walk_instances(sp_die,
989 probe_point_inline_cb, (void *)pf);
990 /* This could be a non-existed inline definition */
991 if (param->retval == -ENOENT)
995 /* We need to find other candidates */
996 if (strisglob(pp->function) && param->retval >= 0) {
997 param->retval = 0; /* We have to clear the result */
1001 return DWARF_CB_ABORT; /* Exit; no same symbol in this CU. */
1004 static int find_probe_point_by_func(struct probe_finder *pf)
1006 struct dwarf_callback_param _param = {.data = (void *)pf,
1008 dwarf_getfuncs(&pf->cu_die, probe_point_search_cb, &_param, 0);
1009 return _param.retval;
1012 struct pubname_callback_param {
1020 static int pubname_search_cb(Dwarf *dbg, Dwarf_Global *gl, void *data)
1022 struct pubname_callback_param *param = data;
1025 if (dwarf_offdie(dbg, gl->die_offset, param->sp_die)) {
1026 if (dwarf_tag(param->sp_die) != DW_TAG_subprogram)
1029 if (die_match_name(param->sp_die, param->function)) {
1030 if (!dwarf_offdie(dbg, gl->cu_offset, param->cu_die))
1034 fname = die_get_decl_file(param->sp_die);
1035 if (!fname || strtailcmp(param->file, fname))
1040 return DWARF_CB_ABORT;
1047 static int debuginfo__find_probe_location(struct debuginfo *dbg,
1048 struct probe_finder *pf)
1050 struct perf_probe_point *pp = &pf->pev->point;
1051 Dwarf_Off off, noff;
1057 pf->lcache = intlist__new(NULL);
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,
1066 .cu_die = &pf->cu_die,
1067 .sp_die = &pf->sp_die,
1070 struct dwarf_callback_param probe_param = {
1074 dwarf_getpubnames(dbg->dbg, pubname_search_cb,
1076 if (pubname_param.found) {
1077 ret = probe_point_search_cb(&pf->sp_die, &probe_param);
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);
1092 /* Check if target file is included. */
1094 pf->fname = cu_find_realpath(&pf->cu_die, pp->file);
1098 if (!pp->file || pf->fname) {
1100 ret = find_probe_point_by_func(pf);
1101 else if (pp->lazy_line)
1102 ret = find_probe_point_lazy(&pf->cu_die, pf);
1105 ret = find_probe_point_by_line(pf);
1114 intlist__delete(pf->lcache);
1120 /* Find probe points from debuginfo */
1121 static int debuginfo__find_probes(struct debuginfo *dbg,
1122 struct probe_finder *pf)
1128 if (pf->cfi_eh || pf->cfi_dbg)
1129 return debuginfo__find_probe_location(dbg, pf);
1131 /* Get the call frame information from this dwarf */
1132 elf = dwarf_getelf(dbg->dbg);
1136 if (gelf_getehdr(elf, &ehdr) == NULL)
1139 pf->machine = ehdr.e_machine;
1141 #ifdef HAVE_DWARF_CFI_SUPPORT
1145 if (elf_section_by_name(elf, &ehdr, &shdr, ".eh_frame", NULL) &&
1146 shdr.sh_type == SHT_PROGBITS)
1147 pf->cfi_eh = dwarf_getcfi_elf(elf);
1149 pf->cfi_dbg = dwarf_getcfi(dbg->dbg);
1151 #endif /* HAVE_DWARF_CFI_SUPPORT */
1153 ret = debuginfo__find_probe_location(dbg, pf);
1157 struct local_vars_finder {
1158 struct probe_finder *pf;
1159 struct perf_probe_arg *args;
1166 /* Collect available variables in this scope */
1167 static int copy_variables_cb(Dwarf_Die *die_mem, void *data)
1169 struct local_vars_finder *vf = data;
1170 struct probe_finder *pf = vf->pf;
1173 tag = dwarf_tag(die_mem);
1174 if (tag == DW_TAG_formal_parameter ||
1175 (tag == DW_TAG_variable && vf->vars)) {
1176 if (convert_variable_location(die_mem, vf->pf->addr,
1177 vf->pf->fb_ops, &pf->sp_die,
1178 pf->machine, NULL) == 0) {
1179 vf->args[vf->nargs].var = (char *)dwarf_diename(die_mem);
1180 if (vf->args[vf->nargs].var == NULL) {
1182 return DIE_FIND_CB_END;
1184 pr_debug(" %s", vf->args[vf->nargs].var);
1189 if (dwarf_haspc(die_mem, vf->pf->addr))
1190 return DIE_FIND_CB_CONTINUE;
1192 return DIE_FIND_CB_SIBLING;
1195 static int expand_probe_args(Dwarf_Die *sc_die, struct probe_finder *pf,
1196 struct perf_probe_arg *args)
1201 struct local_vars_finder vf = {.pf = pf, .args = args, .vars = false,
1202 .max_args = MAX_PROBE_ARGS, .ret = 0};
1204 for (i = 0; i < pf->pev->nargs; i++) {
1205 /* var never be NULL */
1206 if (strcmp(pf->pev->args[i].var, PROBE_ARG_VARS) == 0)
1208 else if (strcmp(pf->pev->args[i].var, PROBE_ARG_PARAMS) != 0) {
1209 /* Copy normal argument */
1210 args[n] = pf->pev->args[i];
1214 pr_debug("Expanding %s into:", pf->pev->args[i].var);
1216 /* Special local variables */
1217 die_find_child(sc_die, copy_variables_cb, (void *)&vf,
1219 pr_debug(" (%d)\n", vf.nargs - n);
1227 static bool trace_event_finder_overlap(struct trace_event_finder *tf)
1231 for (i = 0; i < tf->ntevs; i++) {
1232 if (tf->pf.addr == tf->tevs[i].point.address)
1238 /* Add a found probe point into trace event list */
1239 static int add_probe_trace_event(Dwarf_Die *sc_die, struct probe_finder *pf)
1241 struct trace_event_finder *tf =
1242 container_of(pf, struct trace_event_finder, pf);
1243 struct perf_probe_point *pp = &pf->pev->point;
1244 struct probe_trace_event *tev;
1245 struct perf_probe_arg *args = NULL;
1249 * For some reason (e.g. different column assigned to same address)
1250 * This callback can be called with the address which already passed.
1253 if (trace_event_finder_overlap(tf))
1256 /* Check number of tevs */
1257 if (tf->ntevs == tf->max_tevs) {
1258 pr_warning("Too many( > %d) probe point found.\n",
1262 tev = &tf->tevs[tf->ntevs++];
1264 /* Trace point should be converted from subprogram DIE */
1265 ret = convert_to_trace_point(&pf->sp_die, tf->mod, pf->addr,
1266 pp->retprobe, pp->function, &tev->point);
1270 tev->point.realname = strdup(dwarf_diename(sc_die));
1271 if (!tev->point.realname) {
1276 pr_debug("Probe point found: %s+%lu\n", tev->point.symbol,
1279 /* Expand special probe argument if exist */
1280 args = zalloc(sizeof(struct perf_probe_arg) * MAX_PROBE_ARGS);
1286 ret = expand_probe_args(sc_die, pf, args);
1291 tev->args = zalloc(sizeof(struct probe_trace_arg) * tev->nargs);
1292 if (tev->args == NULL) {
1297 /* Find each argument */
1298 for (i = 0; i < tev->nargs; i++) {
1299 pf->pvar = &args[i];
1300 pf->tvar = &tev->args[i];
1301 /* Variable should be found from scope DIE */
1302 ret = find_variable(sc_die, pf);
1309 clear_probe_trace_event(tev);
1316 static int fill_empty_trace_arg(struct perf_probe_event *pev,
1317 struct probe_trace_event *tevs, int ntevs)
1326 for (i = 0; i < pev->nargs; i++) {
1328 for (j = 0; j < ntevs; j++) {
1329 if (tevs[j].args[i].value) {
1330 type = tevs[j].args[i].type;
1335 print_var_not_found(pev->args[i].var);
1338 for (j = 0; j < ntevs; j++) {
1339 valp = &tevs[j].args[i].value;
1343 ret = asprintf(valp, "\\%lx", probe_conf.magic_num);
1346 /* Note that type can be NULL */
1348 tevs[j].args[i].type = strdup(type);
1349 if (!tevs[j].args[i].type)
1357 /* Find probe_trace_events specified by perf_probe_event from debuginfo */
1358 int debuginfo__find_trace_events(struct debuginfo *dbg,
1359 struct perf_probe_event *pev,
1360 struct probe_trace_event **tevs)
1362 struct trace_event_finder tf = {
1363 .pf = {.pev = pev, .dbg = dbg, .callback = add_probe_trace_event},
1364 .max_tevs = probe_conf.max_probes, .mod = dbg->mod};
1367 /* Allocate result tevs array */
1368 *tevs = zalloc(sizeof(struct probe_trace_event) * tf.max_tevs);
1375 if (pev->nargs != 0 && immediate_value_is_supported())
1376 tf.pf.skip_empty_arg = true;
1378 ret = debuginfo__find_probes(dbg, &tf.pf);
1379 if (ret >= 0 && tf.pf.skip_empty_arg)
1380 ret = fill_empty_trace_arg(pev, tf.tevs, tf.ntevs);
1382 if (ret < 0 || tf.ntevs == 0) {
1383 for (i = 0; i < tf.ntevs; i++)
1384 clear_probe_trace_event(&tf.tevs[i]);
1389 return (ret < 0) ? ret : tf.ntevs;
1392 /* Collect available variables in this scope */
1393 static int collect_variables_cb(Dwarf_Die *die_mem, void *data)
1395 struct available_var_finder *af = data;
1396 struct variable_list *vl;
1397 struct strbuf buf = STRBUF_INIT;
1400 vl = &af->vls[af->nvls - 1];
1402 tag = dwarf_tag(die_mem);
1403 if (tag == DW_TAG_formal_parameter ||
1404 tag == DW_TAG_variable) {
1405 ret = convert_variable_location(die_mem, af->pf.addr,
1406 af->pf.fb_ops, &af->pf.sp_die,
1407 af->pf.machine, NULL);
1408 if (ret == 0 || ret == -ERANGE) {
1410 bool externs = !af->child;
1412 if (strbuf_init(&buf, 64) < 0)
1415 if (probe_conf.show_location_range) {
1417 ret2 = strbuf_add(&buf,
1418 ret ? "[INV]\t" : "[VAL]\t", 6);
1420 ret2 = strbuf_add(&buf, "[EXT]\t", 6);
1425 ret2 = die_get_varname(die_mem, &buf);
1427 if (!ret2 && probe_conf.show_location_range &&
1429 if (strbuf_addch(&buf, '\t') < 0)
1431 ret2 = die_get_var_range(&af->pf.sp_die,
1435 pr_debug("Add new var: %s\n", buf.buf);
1437 strlist__add(vl->vars,
1438 strbuf_detach(&buf, NULL));
1440 strbuf_release(&buf);
1444 if (af->child && dwarf_haspc(die_mem, af->pf.addr))
1445 return DIE_FIND_CB_CONTINUE;
1447 return DIE_FIND_CB_SIBLING;
1449 strbuf_release(&buf);
1450 pr_debug("Error in strbuf\n");
1451 return DIE_FIND_CB_END;
1454 static bool available_var_finder_overlap(struct available_var_finder *af)
1458 for (i = 0; i < af->nvls; i++) {
1459 if (af->pf.addr == af->vls[i].point.address)
1466 /* Add a found vars into available variables list */
1467 static int add_available_vars(Dwarf_Die *sc_die, struct probe_finder *pf)
1469 struct available_var_finder *af =
1470 container_of(pf, struct available_var_finder, pf);
1471 struct perf_probe_point *pp = &pf->pev->point;
1472 struct variable_list *vl;
1477 * For some reason (e.g. different column assigned to same address),
1478 * this callback can be called with the address which already passed.
1481 if (available_var_finder_overlap(af))
1484 /* Check number of tevs */
1485 if (af->nvls == af->max_vls) {
1486 pr_warning("Too many( > %d) probe point found.\n", af->max_vls);
1489 vl = &af->vls[af->nvls++];
1491 /* Trace point should be converted from subprogram DIE */
1492 ret = convert_to_trace_point(&pf->sp_die, af->mod, pf->addr,
1493 pp->retprobe, pp->function, &vl->point);
1497 pr_debug("Probe point found: %s+%lu\n", vl->point.symbol,
1500 /* Find local variables */
1501 vl->vars = strlist__new(NULL, NULL);
1502 if (vl->vars == NULL)
1505 die_find_child(sc_die, collect_variables_cb, (void *)af, &die_mem);
1507 /* Find external variables */
1508 if (!probe_conf.show_ext_vars)
1510 /* Don't need to search child DIE for external vars. */
1512 die_find_child(&pf->cu_die, collect_variables_cb, (void *)af, &die_mem);
1515 if (strlist__empty(vl->vars)) {
1516 strlist__delete(vl->vars);
1524 * Find available variables at given probe point
1525 * Return the number of found probe points. Return 0 if there is no
1526 * matched probe point. Return <0 if an error occurs.
1528 int debuginfo__find_available_vars_at(struct debuginfo *dbg,
1529 struct perf_probe_event *pev,
1530 struct variable_list **vls)
1532 struct available_var_finder af = {
1533 .pf = {.pev = pev, .dbg = dbg, .callback = add_available_vars},
1535 .max_vls = probe_conf.max_probes};
1538 /* Allocate result vls array */
1539 *vls = zalloc(sizeof(struct variable_list) * af.max_vls);
1546 ret = debuginfo__find_probes(dbg, &af.pf);
1548 /* Free vlist for error */
1550 zfree(&af.vls[af.nvls].point.symbol);
1551 strlist__delete(af.vls[af.nvls].vars);
1557 return (ret < 0) ? ret : af.nvls;
1560 /* Reverse search */
1561 int debuginfo__find_probe_point(struct debuginfo *dbg, u64 addr,
1562 struct perf_probe_point *ppt)
1564 Dwarf_Die cudie, spdie, indie;
1565 Dwarf_Addr _addr = 0, baseaddr = 0;
1566 const char *fname = NULL, *func = NULL, *basefunc = NULL, *tmp;
1567 int baseline = 0, lineno = 0, ret = 0;
1569 /* We always need to relocate the address for aranges */
1570 if (debuginfo__get_text_offset(dbg, &baseaddr, false) == 0)
1573 if (!dwarf_addrdie(dbg->dbg, (Dwarf_Addr)addr, &cudie)) {
1574 pr_warning("Failed to find debug information for address %#" PRIx64 "\n",
1580 /* Find a corresponding line (filename and lineno) */
1581 cu_find_lineinfo(&cudie, (Dwarf_Addr)addr, &fname, &lineno);
1582 /* Don't care whether it failed or not */
1584 /* Find a corresponding function (name, baseline and baseaddr) */
1585 if (die_find_realfunc(&cudie, (Dwarf_Addr)addr, &spdie)) {
1586 /* Get function entry information */
1587 func = basefunc = dwarf_diename(&spdie);
1589 die_entrypc(&spdie, &baseaddr) != 0 ||
1590 dwarf_decl_line(&spdie, &baseline) != 0) {
1595 fname = die_get_decl_file(&spdie);
1596 if (addr == baseaddr) {
1597 /* Function entry - Relative line number is 0 */
1602 /* Track down the inline functions step by step */
1603 while (die_find_top_inlinefunc(&spdie, (Dwarf_Addr)addr,
1605 /* There is an inline function */
1606 if (die_entrypc(&indie, &_addr) == 0 &&
1609 * addr is at an inline function entry.
1610 * In this case, lineno should be the call-site
1611 * line number. (overwrite lineinfo)
1613 lineno = die_get_call_lineno(&indie);
1614 fname = die_get_call_file(&indie);
1618 * addr is in an inline function body.
1619 * Since lineno points one of the lines
1620 * of the inline function, baseline should
1621 * be the entry line of the inline function.
1623 tmp = dwarf_diename(&indie);
1625 dwarf_decl_line(&indie, &baseline) != 0)
1631 /* Verify the lineno and baseline are in a same file */
1632 tmp = die_get_decl_file(&spdie);
1633 if (!tmp || (fname && strcmp(tmp, fname) != 0))
1638 /* Make a relative line number or an offset */
1640 ppt->line = lineno - baseline;
1641 else if (basefunc) {
1642 ppt->offset = addr - baseaddr;
1646 /* Duplicate strings */
1648 ppt->function = strdup(func);
1649 if (ppt->function == NULL) {
1655 ppt->file = strdup(fname);
1656 if (ppt->file == NULL) {
1657 zfree(&ppt->function);
1663 if (ret == 0 && (fname || func))
1664 ret = 1; /* Found a point */
1668 /* Add a line and store the src path */
1669 static int line_range_add_line(const char *src, unsigned int lineno,
1670 struct line_range *lr)
1672 /* Copy source path */
1674 lr->path = strdup(src);
1675 if (lr->path == NULL)
1678 return intlist__add(lr->line_list, lineno);
1681 static int line_range_walk_cb(const char *fname, int lineno,
1682 Dwarf_Addr addr, void *data)
1684 struct line_finder *lf = data;
1685 const char *__fname;
1689 if ((strtailcmp(fname, lf->fname) != 0) ||
1690 (lf->lno_s > lineno || lf->lno_e < lineno))
1693 /* Make sure this line can be reversible */
1694 if (cu_find_lineinfo(&lf->cu_die, addr, &__fname, &__lineno) > 0
1695 && (lineno != __lineno || strcmp(fname, __fname)))
1698 err = line_range_add_line(fname, lineno, lf->lr);
1699 if (err < 0 && err != -EEXIST)
1705 /* Find line range from its line number */
1706 static int find_line_range_by_line(Dwarf_Die *sp_die, struct line_finder *lf)
1710 ret = die_walk_lines(sp_die ?: &lf->cu_die, line_range_walk_cb, lf);
1714 if (!intlist__empty(lf->lr->line_list))
1715 ret = lf->found = 1;
1717 ret = 0; /* Lines are not found */
1719 zfree(&lf->lr->path);
1724 static int line_range_inline_cb(Dwarf_Die *in_die, void *data)
1726 int ret = find_line_range_by_line(in_die, data);
1729 * We have to check all instances of inlined function, because
1730 * some execution paths can be optimized out depends on the
1731 * function argument of instances. However, if an error occurs,
1732 * it should be handled by the caller.
1734 return ret < 0 ? ret : 0;
1737 /* Search function definition from function name */
1738 static int line_range_search_cb(Dwarf_Die *sp_die, void *data)
1740 struct dwarf_callback_param *param = data;
1741 struct line_finder *lf = param->data;
1742 struct line_range *lr = lf->lr;
1745 /* Check declared file */
1747 fname = die_get_decl_file(sp_die);
1748 if (!fname || strtailcmp(lr->file, fname))
1752 if (die_match_name(sp_die, lr->function) && die_is_func_def(sp_die)) {
1753 lf->fname = die_get_decl_file(sp_die);
1754 dwarf_decl_line(sp_die, &lr->offset);
1755 pr_debug("fname: %s, lineno:%d\n", lf->fname, lr->offset);
1756 lf->lno_s = lr->offset + lr->start;
1757 if (lf->lno_s < 0) /* Overflow */
1758 lf->lno_s = INT_MAX;
1759 lf->lno_e = lr->offset + lr->end;
1760 if (lf->lno_e < 0) /* Overflow */
1761 lf->lno_e = INT_MAX;
1762 pr_debug("New line range: %d to %d\n", lf->lno_s, lf->lno_e);
1763 lr->start = lf->lno_s;
1764 lr->end = lf->lno_e;
1765 if (!die_is_func_instance(sp_die))
1766 param->retval = die_walk_instances(sp_die,
1767 line_range_inline_cb, lf);
1769 param->retval = find_line_range_by_line(sp_die, lf);
1770 return DWARF_CB_ABORT;
1775 static int find_line_range_by_func(struct line_finder *lf)
1777 struct dwarf_callback_param param = {.data = (void *)lf, .retval = 0};
1778 dwarf_getfuncs(&lf->cu_die, line_range_search_cb, ¶m, 0);
1779 return param.retval;
1782 int debuginfo__find_line_range(struct debuginfo *dbg, struct line_range *lr)
1784 struct line_finder lf = {.lr = lr, .found = 0};
1786 Dwarf_Off off = 0, noff;
1789 const char *comp_dir;
1791 /* Fastpath: lookup by function name from .debug_pubnames section */
1793 struct pubname_callback_param pubname_param = {
1794 .function = lr->function, .file = lr->file,
1795 .cu_die = &lf.cu_die, .sp_die = &lf.sp_die, .found = 0};
1796 struct dwarf_callback_param line_range_param = {
1797 .data = (void *)&lf, .retval = 0};
1799 dwarf_getpubnames(dbg->dbg, pubname_search_cb,
1801 if (pubname_param.found) {
1802 line_range_search_cb(&lf.sp_die, &line_range_param);
1808 /* Loop on CUs (Compilation Unit) */
1809 while (!lf.found && ret >= 0) {
1810 if (dwarf_nextcu(dbg->dbg, off, &noff, &cuhl,
1811 NULL, NULL, NULL) != 0)
1814 /* Get the DIE(Debugging Information Entry) of this CU */
1815 diep = dwarf_offdie(dbg->dbg, off + cuhl, &lf.cu_die);
1821 /* Check if target file is included. */
1823 lf.fname = cu_find_realpath(&lf.cu_die, lr->file);
1827 if (!lr->file || lf.fname) {
1829 ret = find_line_range_by_func(&lf);
1831 lf.lno_s = lr->start;
1833 ret = find_line_range_by_line(NULL, &lf);
1840 /* Store comp_dir */
1842 comp_dir = cu_get_comp_dir(&lf.cu_die);
1844 lr->comp_dir = strdup(comp_dir);
1850 pr_debug("path: %s\n", lr->path);
1851 return (ret < 0) ? ret : lf.found;
1855 * Find a src file from a DWARF tag path. Prepend optional source path prefix
1856 * and chop off leading directories that do not exist. Result is passed back as
1857 * a newly allocated path on success.
1858 * Return 0 if file was found and readable, -errno otherwise.
1860 int find_source_path(const char *raw_path, const char *sbuild_id,
1861 const char *comp_dir, char **new_path)
1863 const char *prefix = symbol_conf.source_prefix;
1865 if (sbuild_id && !prefix) {
1866 if (!get_source_from_debuginfod(raw_path, sbuild_id, new_path))
1871 if (raw_path[0] != '/' && comp_dir)
1872 /* If not an absolute path, try to use comp_dir */
1875 if (access(raw_path, R_OK) == 0) {
1876 *new_path = strdup(raw_path);
1877 return *new_path ? 0 : -ENOMEM;
1883 *new_path = malloc((strlen(prefix) + strlen(raw_path) + 2));
1888 sprintf(*new_path, "%s/%s", prefix, raw_path);
1890 if (access(*new_path, R_OK) == 0)
1893 if (!symbol_conf.source_prefix) {
1894 /* In case of searching comp_dir, don't retry */
1904 raw_path = strchr(++raw_path, '/');