tools/perf/util/probe-finder.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * probe-finder.c : C expression to kprobe event converter
   4  *
   5  * Written by Masami Hiramatsu <mhiramat@redhat.com>
   6  */
   7
   8 #include <inttypes.h>
   9 #include <sys/utsname.h>
  10 #include <sys/types.h>
  11 #include <sys/stat.h>
  12 #include <fcntl.h>
  13 #include <errno.h>
  14 #include <stdio.h>
  15 #include <unistd.h>
  16 #include <stdlib.h>
  17 #include <string.h>
  18 #include <stdarg.h>
  19 #include <dwarf-regs.h>
  20
  21 #include <linux/bitops.h>
  22 #include <linux/zalloc.h>
  23 #include "event.h"
  24 #include "dso.h"
  25 #include "debug.h"
  26 #include "intlist.h"
  27 #include "strbuf.h"
  28 #include "strlist.h"
  29 #include "symbol.h"
  30 #include "probe-finder.h"
  31 #include "probe-file.h"
  32 #include "string2.h"
  33
  34 /* Kprobe tracer basic type is up to u64 */
  35 #define MAX_BASIC_TYPE_BITS     64
  36
  37 /* Dwarf FL wrappers */
  38 static char *debuginfo_path;    /* Currently dummy */
  39
  40 static const Dwfl_Callbacks offline_callbacks = {
  41         .find_debuginfo = dwfl_standard_find_debuginfo,
  42         .debuginfo_path = &debuginfo_path,
  43
  44         .section_address = dwfl_offline_section_address,
  45
  46         /* We use this table for core files too.  */
  47         .find_elf = dwfl_build_id_find_elf,
  48 };
  49
  50 /* Get a Dwarf from offline image */
  51 static int debuginfo__init_offline_dwarf(struct debuginfo *dbg,
  52                                          const char *path)
  53 {
  54         int fd;
  55
  56         fd = open(path, O_RDONLY);
  57         if (fd < 0)
  58                 return fd;
  59
  60         dbg->dwfl = dwfl_begin(&offline_callbacks);
  61         if (!dbg->dwfl)
  62                 goto error;
  63
  64         dwfl_report_begin(dbg->dwfl);
  65         dbg->mod = dwfl_report_offline(dbg->dwfl, "", "", fd);
  66         if (!dbg->mod)
  67                 goto error;
  68
  69         dbg->dbg = dwfl_module_getdwarf(dbg->mod, &dbg->bias);
  70         if (!dbg->dbg)
  71                 goto error;
  72
  73         dwfl_report_end(dbg->dwfl, NULL, NULL);
  74
  75         return 0;
  76 error:
  77         if (dbg->dwfl)
  78                 dwfl_end(dbg->dwfl);
  79         else
  80                 close(fd);
  81         memset(dbg, 0, sizeof(*dbg));
  82
  83         return -ENOENT;
  84 }
  85
  86 static struct debuginfo *__debuginfo__new(const char *path)
  87 {
  88         struct debuginfo *dbg = zalloc(sizeof(*dbg));
  89         if (!dbg)
  90                 return NULL;
  91
  92         if (debuginfo__init_offline_dwarf(dbg, path) < 0)
  93                 zfree(&dbg);
  94         if (dbg)
  95                 pr_debug("Open Debuginfo file: %s\n", path);
  96         return dbg;
  97 }
  98
  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__MIXEDUP_UBUNTU_DEBUGINFO,
 105         DSO_BINARY_TYPE__NOT_FOUND,
 106 };
 107
 108 struct debuginfo *debuginfo__new(const char *path)
 109 {
 110         enum dso_binary_type *type;
 111         char buf[PATH_MAX], nil = '\0';
 112         struct dso *dso;
 113         struct debuginfo *dinfo = NULL;
 114
 115         /* Try to open distro debuginfo files */
 116         dso = dso__new(path);
 117         if (!dso)
 118                 goto out;
 119
 120         for (type = distro_dwarf_types;
 121              !dinfo && *type != DSO_BINARY_TYPE__NOT_FOUND;
 122              type++) {
 123                 if (dso__read_binary_type_filename(dso, *type, &nil,
 124                                                    buf, PATH_MAX) < 0)
 125                         continue;
 126                 dinfo = __debuginfo__new(buf);
 127         }
 128         dso__put(dso);
 129
 130 out:
 131         /* if failed to open all distro debuginfo, open given binary */
 132         return dinfo ? : __debuginfo__new(path);
 133 }
 134
 135 void debuginfo__delete(struct debuginfo *dbg)
 136 {
 137         if (dbg) {
 138                 if (dbg->dwfl)
 139                         dwfl_end(dbg->dwfl);
 140                 free(dbg);
 141         }
 142 }
 143
 144 /*
 145  * Probe finder related functions
 146  */
 147
 148 static struct probe_trace_arg_ref *alloc_trace_arg_ref(long offs)
 149 {
 150         struct probe_trace_arg_ref *ref;
 151         ref = zalloc(sizeof(struct probe_trace_arg_ref));
 152         if (ref != NULL)
 153                 ref->offset = offs;
 154         return ref;
 155 }
 156
 157 /*
 158  * Convert a location into trace_arg.
 159  * If tvar == NULL, this just checks variable can be converted.
 160  * If fentry == true and vr_die is a parameter, do huristic search
 161  * for the location fuzzed by function entry mcount.
 162  */
 163 static int convert_variable_location(Dwarf_Die *vr_die, Dwarf_Addr addr,
 164                                      Dwarf_Op *fb_ops, Dwarf_Die *sp_die,
 165                                      unsigned int machine,
 166                                      struct probe_trace_arg *tvar)
 167 {
 168         Dwarf_Attribute attr;
 169         Dwarf_Addr tmp = 0;
 170         Dwarf_Op *op;
 171         size_t nops;
 172         unsigned int regn;
 173         Dwarf_Word offs = 0;
 174         bool ref = false;
 175         const char *regs;
 176         int ret, ret2 = 0;
 177
 178         if (dwarf_attr(vr_die, DW_AT_external, &attr) != NULL)
 179                 goto static_var;
 180
 181         /* Constant value */
 182         if (dwarf_attr(vr_die, DW_AT_const_value, &attr) &&
 183             immediate_value_is_supported()) {
 184                 Dwarf_Sword snum;
 185
 186                 dwarf_formsdata(&attr, &snum);
 187                 ret = asprintf(&tvar->value, "\\%ld", (long)snum);
 188
 189                 return ret < 0 ? -ENOMEM : 0;
 190         }
 191
 192         /* TODO: handle more than 1 exprs */
 193         if (dwarf_attr(vr_die, DW_AT_location, &attr) == NULL)
 194                 return -EINVAL; /* Broken DIE ? */
 195         if (dwarf_getlocation_addr(&attr, addr, &op, &nops, 1) <= 0) {
 196                 ret = dwarf_entrypc(sp_die, &tmp);
 197                 if (ret)
 198                         return -ENOENT;
 199
 200                 if (probe_conf.show_location_range &&
 201                         (dwarf_tag(vr_die) == DW_TAG_variable)) {
 202                         ret2 = -ERANGE;
 203                 } else if (addr != tmp ||
 204                         dwarf_tag(vr_die) != DW_TAG_formal_parameter) {
 205                         return -ENOENT;
 206                 }
 207
 208                 ret = dwarf_highpc(sp_die, &tmp);
 209                 if (ret)
 210                         return -ENOENT;
 211                 /*
 212                  * This is fuzzed by fentry mcount. We try to find the
 213                  * parameter location at the earliest address.
 214                  */
 215                 for (addr += 1; addr <= tmp; addr++) {
 216                         if (dwarf_getlocation_addr(&attr, addr, &op,
 217                                                    &nops, 1) > 0)
 218                                 goto found;
 219                 }
 220                 return -ENOENT;
 221         }
 222 found:
 223         if (nops == 0)
 224                 /* TODO: Support const_value */
 225                 return -ENOENT;
 226
 227         if (op->atom == DW_OP_addr) {
 228 static_var:
 229                 if (!tvar)
 230                         return ret2;
 231                 /* Static variables on memory (not stack), make @varname */
 232                 ret = strlen(dwarf_diename(vr_die));
 233                 tvar->value = zalloc(ret + 2);
 234                 if (tvar->value == NULL)
 235                         return -ENOMEM;
 236                 snprintf(tvar->value, ret + 2, "@%s", dwarf_diename(vr_die));
 237                 tvar->ref = alloc_trace_arg_ref((long)offs);
 238                 if (tvar->ref == NULL)
 239                         return -ENOMEM;
 240                 return ret2;
 241         }
 242
 243         /* If this is based on frame buffer, set the offset */
 244         if (op->atom == DW_OP_fbreg) {
 245                 if (fb_ops == NULL)
 246                         return -ENOTSUP;
 247                 ref = true;
 248                 offs = op->number;
 249                 op = &fb_ops[0];
 250         }
 251
 252         if (op->atom >= DW_OP_breg0 && op->atom <= DW_OP_breg31) {
 253                 regn = op->atom - DW_OP_breg0;
 254                 offs += op->number;
 255                 ref = true;
 256         } else if (op->atom >= DW_OP_reg0 && op->atom <= DW_OP_reg31) {
 257                 regn = op->atom - DW_OP_reg0;
 258         } else if (op->atom == DW_OP_bregx) {
 259                 regn = op->number;
 260                 offs += op->number2;
 261                 ref = true;
 262         } else if (op->atom == DW_OP_regx) {
 263                 regn = op->number;
 264         } else {
 265                 pr_debug("DW_OP %x is not supported.\n", op->atom);
 266                 return -ENOTSUP;
 267         }
 268
 269         if (!tvar)
 270                 return ret2;
 271
 272         regs = get_dwarf_regstr(regn, machine);
 273         if (!regs) {
 274                 /* This should be a bug in DWARF or this tool */
 275                 pr_warning("Mapping for the register number %u "
 276                            "missing on this architecture.\n", regn);
 277                 return -ENOTSUP;
 278         }
 279
 280         tvar->value = strdup(regs);
 281         if (tvar->value == NULL)
 282                 return -ENOMEM;
 283
 284         if (ref) {
 285                 tvar->ref = alloc_trace_arg_ref((long)offs);
 286                 if (tvar->ref == NULL)
 287                         return -ENOMEM;
 288         }
 289         return ret2;
 290 }
 291
 292 #define BYTES_TO_BITS(nb)       ((nb) * BITS_PER_LONG / sizeof(long))
 293
 294 static int convert_variable_type(Dwarf_Die *vr_die,
 295                                  struct probe_trace_arg *tvar,
 296                                  const char *cast, bool user_access)
 297 {
 298         struct probe_trace_arg_ref **ref_ptr = &tvar->ref;
 299         Dwarf_Die type;
 300         char buf[16];
 301         char sbuf[STRERR_BUFSIZE];
 302         int bsize, boffs, total;
 303         int ret;
 304         char prefix;
 305
 306         /* TODO: check all types */
 307         if (cast && strcmp(cast, "string") != 0 && strcmp(cast, "ustring") &&
 308             strcmp(cast, "x") != 0 &&
 309             strcmp(cast, "s") != 0 && strcmp(cast, "u") != 0) {
 310                 /* Non string type is OK */
 311                 /* and respect signedness/hexadecimal cast */
 312                 tvar->type = strdup(cast);
 313                 return (tvar->type == NULL) ? -ENOMEM : 0;
 314         }
 315
 316         bsize = dwarf_bitsize(vr_die);
 317         if (bsize > 0) {
 318                 /* This is a bitfield */
 319                 boffs = dwarf_bitoffset(vr_die);
 320                 total = dwarf_bytesize(vr_die);
 321                 if (boffs < 0 || total < 0)
 322                         return -ENOENT;
 323                 ret = snprintf(buf, 16, "b%d@%d/%zd", bsize, boffs,
 324                                 BYTES_TO_BITS(total));
 325                 goto formatted;
 326         }
 327
 328         if (die_get_real_type(vr_die, &type) == NULL) {
 329                 pr_warning("Failed to get a type information of %s.\n",
 330                            dwarf_diename(vr_die));
 331                 return -ENOENT;
 332         }
 333
 334         pr_debug("%s type is %s.\n",
 335                  dwarf_diename(vr_die), dwarf_diename(&type));
 336
 337         if (cast && (!strcmp(cast, "string") || !strcmp(cast, "ustring"))) {
 338                 /* String type */
 339                 ret = dwarf_tag(&type);
 340                 if (ret != DW_TAG_pointer_type &&
 341                     ret != DW_TAG_array_type) {
 342                         pr_warning("Failed to cast into string: "
 343                                    "%s(%s) is not a pointer nor array.\n",
 344                                    dwarf_diename(vr_die), dwarf_diename(&type));
 345                         return -EINVAL;
 346                 }
 347                 if (die_get_real_type(&type, &type) == NULL) {
 348                         pr_warning("Failed to get a type"
 349                                    " information.\n");
 350                         return -ENOENT;
 351                 }
 352                 if (ret == DW_TAG_pointer_type) {
 353                         while (*ref_ptr)
 354                                 ref_ptr = &(*ref_ptr)->next;
 355                         /* Add new reference with offset +0 */
 356                         *ref_ptr = zalloc(sizeof(struct probe_trace_arg_ref));
 357                         if (*ref_ptr == NULL) {
 358                                 pr_warning("Out of memory error\n");
 359                                 return -ENOMEM;
 360                         }
 361                         (*ref_ptr)->user_access = user_access;
 362                 }
 363                 if (!die_compare_name(&type, "char") &&
 364                     !die_compare_name(&type, "unsigned char")) {
 365                         pr_warning("Failed to cast into string: "
 366                                    "%s is not (unsigned) char *.\n",
 367                                    dwarf_diename(vr_die));
 368                         return -EINVAL;
 369                 }
 370                 tvar->type = strdup(cast);
 371                 return (tvar->type == NULL) ? -ENOMEM : 0;
 372         }
 373
 374         if (cast && (strcmp(cast, "u") == 0))
 375                 prefix = 'u';
 376         else if (cast && (strcmp(cast, "s") == 0))
 377                 prefix = 's';
 378         else if (cast && (strcmp(cast, "x") == 0) &&
 379                  probe_type_is_available(PROBE_TYPE_X))
 380                 prefix = 'x';
 381         else
 382                 prefix = die_is_signed_type(&type) ? 's' :
 383                          probe_type_is_available(PROBE_TYPE_X) ? 'x' : 'u';
 384
 385         ret = dwarf_bytesize(&type);
 386         if (ret <= 0)
 387                 /* No size ... try to use default type */
 388                 return 0;
 389         ret = BYTES_TO_BITS(ret);
 390
 391         /* Check the bitwidth */
 392         if (ret > MAX_BASIC_TYPE_BITS) {
 393                 pr_info("%s exceeds max-bitwidth. Cut down to %d bits.\n",
 394                         dwarf_diename(&type), MAX_BASIC_TYPE_BITS);
 395                 ret = MAX_BASIC_TYPE_BITS;
 396         }
 397         ret = snprintf(buf, 16, "%c%d", prefix, ret);
 398
 399 formatted:
 400         if (ret < 0 || ret >= 16) {
 401                 if (ret >= 16)
 402                         ret = -E2BIG;
 403                 pr_warning("Failed to convert variable type: %s\n",
 404                            str_error_r(-ret, sbuf, sizeof(sbuf)));
 405                 return ret;
 406         }
 407         tvar->type = strdup(buf);
 408         if (tvar->type == NULL)
 409                 return -ENOMEM;
 410         return 0;
 411 }
 412
 413 static int convert_variable_fields(Dwarf_Die *vr_die, const char *varname,
 414                                     struct perf_probe_arg_field *field,
 415                                     struct probe_trace_arg_ref **ref_ptr,
 416                                     Dwarf_Die *die_mem, bool user_access)
 417 {
 418         struct probe_trace_arg_ref *ref = *ref_ptr;
 419         Dwarf_Die type;
 420         Dwarf_Word offs;
 421         int ret, tag;
 422
 423         pr_debug("converting %s in %s\n", field->name, varname);
 424         if (die_get_real_type(vr_die, &type) == NULL) {
 425                 pr_warning("Failed to get the type of %s.\n", varname);
 426                 return -ENOENT;
 427         }
 428         pr_debug2("Var real type: %s (%x)\n", dwarf_diename(&type),
 429                   (unsigned)dwarf_dieoffset(&type));
 430         tag = dwarf_tag(&type);
 431
 432         if (field->name[0] == '[' &&
 433             (tag == DW_TAG_array_type || tag == DW_TAG_pointer_type)) {
 434                 /* Save original type for next field or type */
 435                 memcpy(die_mem, &type, sizeof(*die_mem));
 436                 /* Get the type of this array */
 437                 if (die_get_real_type(&type, &type) == NULL) {
 438                         pr_warning("Failed to get the type of %s.\n", varname);
 439                         return -ENOENT;
 440                 }
 441                 pr_debug2("Array real type: %s (%x)\n", dwarf_diename(&type),
 442                          (unsigned)dwarf_dieoffset(&type));
 443                 if (tag == DW_TAG_pointer_type) {
 444                         ref = zalloc(sizeof(struct probe_trace_arg_ref));
 445                         if (ref == NULL)
 446                                 return -ENOMEM;
 447                         if (*ref_ptr)
 448                                 (*ref_ptr)->next = ref;
 449                         else
 450                                 *ref_ptr = ref;
 451                 }
 452                 ref->offset += dwarf_bytesize(&type) * field->index;
 453                 ref->user_access = user_access;
 454                 goto next;
 455         } else if (tag == DW_TAG_pointer_type) {
 456                 /* Check the pointer and dereference */
 457                 if (!field->ref) {
 458                         pr_err("Semantic error: %s must be referred by '->'\n",
 459                                field->name);
 460                         return -EINVAL;
 461                 }
 462                 /* Get the type pointed by this pointer */
 463                 if (die_get_real_type(&type, &type) == NULL) {
 464                         pr_warning("Failed to get the type of %s.\n", varname);
 465                         return -ENOENT;
 466                 }
 467                 /* Verify it is a data structure  */
 468                 tag = dwarf_tag(&type);
 469                 if (tag != DW_TAG_structure_type && tag != DW_TAG_union_type) {
 470                         pr_warning("%s is not a data structure nor a union.\n",
 471                                    varname);
 472                         return -EINVAL;
 473                 }
 474
 475                 ref = zalloc(sizeof(struct probe_trace_arg_ref));
 476                 if (ref == NULL)
 477                         return -ENOMEM;
 478                 if (*ref_ptr)
 479                         (*ref_ptr)->next = ref;
 480                 else
 481                         *ref_ptr = ref;
 482         } else {
 483                 /* Verify it is a data structure  */
 484                 if (tag != DW_TAG_structure_type && tag != DW_TAG_union_type) {
 485                         pr_warning("%s is not a data structure nor a union.\n",
 486                                    varname);
 487                         return -EINVAL;
 488                 }
 489                 if (field->name[0] == '[') {
 490                         pr_err("Semantic error: %s is not a pointer"
 491                                " nor array.\n", varname);
 492                         return -EINVAL;
 493                 }
 494                 /* While prcessing unnamed field, we don't care about this */
 495                 if (field->ref && dwarf_diename(vr_die)) {
 496                         pr_err("Semantic error: %s must be referred by '.'\n",
 497                                field->name);
 498                         return -EINVAL;
 499                 }
 500                 if (!ref) {
 501                         pr_warning("Structure on a register is not "
 502                                    "supported yet.\n");
 503                         return -ENOTSUP;
 504                 }
 505         }
 506
 507         if (die_find_member(&type, field->name, die_mem) == NULL) {
 508                 pr_warning("%s(type:%s) has no member %s.\n", varname,
 509                            dwarf_diename(&type), field->name);
 510                 return -EINVAL;
 511         }
 512
 513         /* Get the offset of the field */
 514         if (tag == DW_TAG_union_type) {
 515                 offs = 0;
 516         } else {
 517                 ret = die_get_data_member_location(die_mem, &offs);
 518                 if (ret < 0) {
 519                         pr_warning("Failed to get the offset of %s.\n",
 520                                    field->name);
 521                         return ret;
 522                 }
 523         }
 524         ref->offset += (long)offs;
 525         ref->user_access = user_access;
 526
 527         /* If this member is unnamed, we need to reuse this field */
 528         if (!dwarf_diename(die_mem))
 529                 return convert_variable_fields(die_mem, varname, field,
 530                                                 &ref, die_mem, user_access);
 531
 532 next:
 533         /* Converting next field */
 534         if (field->next)
 535                 return convert_variable_fields(die_mem, field->name,
 536                                 field->next, &ref, die_mem, user_access);
 537         else
 538                 return 0;
 539 }
 540
 541 static void print_var_not_found(const char *varname)
 542 {
 543         pr_err("Failed to find the location of the '%s' variable at this address.\n"
 544                " Perhaps it has been optimized out.\n"
 545                " Use -V with the --range option to show '%s' location range.\n",
 546                 varname, varname);
 547 }
 548
 549 /* Show a variables in kprobe event format */
 550 static int convert_variable(Dwarf_Die *vr_die, struct probe_finder *pf)
 551 {
 552         Dwarf_Die die_mem;
 553         int ret;
 554
 555         pr_debug("Converting variable %s into trace event.\n",
 556                  dwarf_diename(vr_die));
 557
 558         ret = convert_variable_location(vr_die, pf->addr, pf->fb_ops,
 559                                         &pf->sp_die, pf->machine, pf->tvar);
 560         if (ret == -ENOENT && pf->skip_empty_arg)
 561                 /* This can be found in other place. skip it */
 562                 return 0;
 563         if (ret == -ENOENT || ret == -EINVAL) {
 564                 print_var_not_found(pf->pvar->var);
 565         } else if (ret == -ENOTSUP)
 566                 pr_err("Sorry, we don't support this variable location yet.\n");
 567         else if (ret == 0 && pf->pvar->field) {
 568                 ret = convert_variable_fields(vr_die, pf->pvar->var,
 569                                               pf->pvar->field, &pf->tvar->ref,
 570                                               &die_mem, pf->pvar->user_access);
 571                 vr_die = &die_mem;
 572         }
 573         if (ret == 0)
 574                 ret = convert_variable_type(vr_die, pf->tvar, pf->pvar->type,
 575                                             pf->pvar->user_access);
 576         /* *expr will be cached in libdw. Don't free it. */
 577         return ret;
 578 }
 579
 580 /* Find a variable in a scope DIE */
 581 static int find_variable(Dwarf_Die *sc_die, struct probe_finder *pf)
 582 {
 583         Dwarf_Die vr_die;
 584         char *buf, *ptr;
 585         int ret = 0;
 586
 587         /* Copy raw parameters */
 588         if (!is_c_varname(pf->pvar->var))
 589                 return copy_to_probe_trace_arg(pf->tvar, pf->pvar);
 590
 591         if (pf->pvar->name)
 592                 pf->tvar->name = strdup(pf->pvar->name);
 593         else {
 594                 buf = synthesize_perf_probe_arg(pf->pvar);
 595                 if (!buf)
 596                         return -ENOMEM;
 597                 ptr = strchr(buf, ':'); /* Change type separator to _ */
 598                 if (ptr)
 599                         *ptr = '_';
 600                 pf->tvar->name = buf;
 601         }
 602         if (pf->tvar->name == NULL)
 603                 return -ENOMEM;
 604
 605         pr_debug("Searching '%s' variable in context.\n", pf->pvar->var);
 606         /* Search child die for local variables and parameters. */
 607         if (!die_find_variable_at(sc_die, pf->pvar->var, pf->addr, &vr_die)) {
 608                 /* Search again in global variables */
 609                 if (!die_find_variable_at(&pf->cu_die, pf->pvar->var,
 610                                                 0, &vr_die)) {
 611                         if (pf->skip_empty_arg)
 612                                 return 0;
 613                         pr_warning("Failed to find '%s' in this function.\n",
 614                                    pf->pvar->var);
 615                         ret = -ENOENT;
 616                 }
 617         }
 618         if (ret >= 0)
 619                 ret = convert_variable(&vr_die, pf);
 620
 621         return ret;
 622 }
 623
 624 /* Convert subprogram DIE to trace point */
 625 static int convert_to_trace_point(Dwarf_Die *sp_die, Dwfl_Module *mod,
 626                                   Dwarf_Addr paddr, bool retprobe,
 627                                   const char *function,
 628                                   struct probe_trace_point *tp)
 629 {
 630         Dwarf_Addr eaddr;
 631         GElf_Sym sym;
 632         const char *symbol;
 633
 634         /* Verify the address is correct */
 635         if (!dwarf_haspc(sp_die, paddr)) {
 636                 pr_warning("Specified offset is out of %s\n",
 637                            dwarf_diename(sp_die));
 638                 return -EINVAL;
 639         }
 640
 641         if (dwarf_entrypc(sp_die, &eaddr) == 0) {
 642                 /* If the DIE has entrypc, use it. */
 643                 symbol = dwarf_diename(sp_die);
 644         } else {
 645                 /* Try to get actual symbol name and address from symtab */
 646                 symbol = dwfl_module_addrsym(mod, paddr, &sym, NULL);
 647                 eaddr = sym.st_value;
 648         }
 649         if (!symbol) {
 650                 pr_warning("Failed to find symbol at 0x%lx\n",
 651                            (unsigned long)paddr);
 652                 return -ENOENT;
 653         }
 654
 655         tp->offset = (unsigned long)(paddr - eaddr);
 656         tp->address = (unsigned long)paddr;
 657         tp->symbol = strdup(symbol);
 658         if (!tp->symbol)
 659                 return -ENOMEM;
 660
 661         /* Return probe must be on the head of a subprogram */
 662         if (retprobe) {
 663                 if (eaddr != paddr) {
 664                         pr_warning("Failed to find \"%s%%return\",\n"
 665                                    " because %s is an inlined function and"
 666                                    " has no return point.\n", function,
 667                                    function);
 668                         return -EINVAL;
 669                 }
 670                 tp->retprobe = true;
 671         }
 672
 673         return 0;
 674 }
 675
 676 /* Call probe_finder callback with scope DIE */
 677 static int call_probe_finder(Dwarf_Die *sc_die, struct probe_finder *pf)
 678 {
 679         Dwarf_Attribute fb_attr;
 680         Dwarf_Frame *frame = NULL;
 681         size_t nops;
 682         int ret;
 683
 684         if (!sc_die) {
 685                 pr_err("Caller must pass a scope DIE. Program error.\n");
 686                 return -EINVAL;
 687         }
 688
 689         /* If not a real subprogram, find a real one */
 690         if (!die_is_func_def(sc_die)) {
 691                 if (!die_find_realfunc(&pf->cu_die, pf->addr, &pf->sp_die)) {
 692                         if (die_find_tailfunc(&pf->cu_die, pf->addr, &pf->sp_die)) {
 693                                 pr_warning("Ignoring tail call from %s\n",
 694                                                 dwarf_diename(&pf->sp_die));
 695                                 return 0;
 696                         } else {
 697                                 pr_warning("Failed to find probe point in any "
 698                                            "functions.\n");
 699                                 return -ENOENT;
 700                         }
 701                 }
 702         } else
 703                 memcpy(&pf->sp_die, sc_die, sizeof(Dwarf_Die));
 704
 705         /* Get the frame base attribute/ops from subprogram */
 706         dwarf_attr(&pf->sp_die, DW_AT_frame_base, &fb_attr);
 707         ret = dwarf_getlocation_addr(&fb_attr, pf->addr, &pf->fb_ops, &nops, 1);
 708         if (ret <= 0 || nops == 0) {
 709                 pf->fb_ops = NULL;
 710 #if _ELFUTILS_PREREQ(0, 142)
 711         } else if (nops == 1 && pf->fb_ops[0].atom == DW_OP_call_frame_cfa &&
 712                    (pf->cfi_eh != NULL || pf->cfi_dbg != NULL)) {
 713                 if ((dwarf_cfi_addrframe(pf->cfi_eh, pf->addr, &frame) != 0 &&
 714                      (dwarf_cfi_addrframe(pf->cfi_dbg, pf->addr, &frame) != 0)) ||
 715                     dwarf_frame_cfa(frame, &pf->fb_ops, &nops) != 0) {
 716                         pr_warning("Failed to get call frame on 0x%jx\n",
 717                                    (uintmax_t)pf->addr);
 718                         free(frame);
 719                         return -ENOENT;
 720                 }
 721 #endif
 722         }
 723
 724         /* Call finder's callback handler */
 725         ret = pf->callback(sc_die, pf);
 726
 727         /* Since *pf->fb_ops can be a part of frame. we should free it here. */
 728         free(frame);
 729         pf->fb_ops = NULL;
 730
 731         return ret;
 732 }
 733
 734 struct find_scope_param {
 735         const char *function;
 736         const char *file;
 737         int line;
 738         int diff;
 739         Dwarf_Die *die_mem;
 740         bool found;
 741 };
 742
 743 static int find_best_scope_cb(Dwarf_Die *fn_die, void *data)
 744 {
 745         struct find_scope_param *fsp = data;
 746         const char *file;
 747         int lno;
 748
 749         /* Skip if declared file name does not match */
 750         if (fsp->file) {
 751                 file = dwarf_decl_file(fn_die);
 752                 if (!file || strcmp(fsp->file, file) != 0)
 753                         return 0;
 754         }
 755         /* If the function name is given, that's what user expects */
 756         if (fsp->function) {
 757                 if (die_match_name(fn_die, fsp->function)) {
 758                         memcpy(fsp->die_mem, fn_die, sizeof(Dwarf_Die));
 759                         fsp->found = true;
 760                         return 1;
 761                 }
 762         } else {
 763                 /* With the line number, find the nearest declared DIE */
 764                 dwarf_decl_line(fn_die, &lno);
 765                 if (lno < fsp->line && fsp->diff > fsp->line - lno) {
 766                         /* Keep a candidate and continue */
 767                         fsp->diff = fsp->line - lno;
 768                         memcpy(fsp->die_mem, fn_die, sizeof(Dwarf_Die));
 769                         fsp->found = true;
 770                 }
 771         }
 772         return 0;
 773 }
 774
 775 /* Return innermost DIE */
 776 static int find_inner_scope_cb(Dwarf_Die *fn_die, void *data)
 777 {
 778         struct find_scope_param *fsp = data;
 779
 780         memcpy(fsp->die_mem, fn_die, sizeof(Dwarf_Die));
 781         fsp->found = true;
 782         return 1;
 783 }
 784
 785 /* Find an appropriate scope fits to given conditions */
 786 static Dwarf_Die *find_best_scope(struct probe_finder *pf, Dwarf_Die *die_mem)
 787 {
 788         struct find_scope_param fsp = {
 789                 .function = pf->pev->point.function,
 790                 .file = pf->fname,
 791                 .line = pf->lno,
 792                 .diff = INT_MAX,
 793                 .die_mem = die_mem,
 794                 .found = false,
 795         };
 796         int ret;
 797
 798         ret = cu_walk_functions_at(&pf->cu_die, pf->addr, find_best_scope_cb,
 799                                    &fsp);
 800         if (!ret && !fsp.found)
 801                 cu_walk_functions_at(&pf->cu_die, pf->addr,
 802                                      find_inner_scope_cb, &fsp);
 803
 804         return fsp.found ? die_mem : NULL;
 805 }
 806
 807 static int verify_representive_line(struct probe_finder *pf, const char *fname,
 808                                 int lineno, Dwarf_Addr addr)
 809 {
 810         const char *__fname, *__func = NULL;
 811         Dwarf_Die die_mem;
 812         int __lineno;
 813
 814         /* Verify line number and address by reverse search */
 815         if (cu_find_lineinfo(&pf->cu_die, addr, &__fname, &__lineno) < 0)
 816                 return 0;
 817
 818         pr_debug2("Reversed line: %s:%d\n", __fname, __lineno);
 819         if (strcmp(fname, __fname) || lineno == __lineno)
 820                 return 0;
 821
 822         pr_warning("This line is sharing the address with other lines.\n");
 823
 824         if (pf->pev->point.function) {
 825                 /* Find best match function name and lines */
 826                 pf->addr = addr;
 827                 if (find_best_scope(pf, &die_mem)
 828                     && die_match_name(&die_mem, pf->pev->point.function)
 829                     && dwarf_decl_line(&die_mem, &lineno) == 0) {
 830                         __func = dwarf_diename(&die_mem);
 831                         __lineno -= lineno;
 832                 }
 833         }
 834         pr_warning("Please try to probe at %s:%d instead.\n",
 835                    __func ? : __fname, __lineno);
 836
 837         return -ENOENT;
 838 }
 839
 840 static int probe_point_line_walker(const char *fname, int lineno,
 841                                    Dwarf_Addr addr, void *data)
 842 {
 843         struct probe_finder *pf = data;
 844         Dwarf_Die *sc_die, die_mem;
 845         int ret;
 846
 847         if (lineno != pf->lno || strtailcmp(fname, pf->fname) != 0)
 848                 return 0;
 849
 850         if (verify_representive_line(pf, fname, lineno, addr))
 851                 return -ENOENT;
 852
 853         pf->addr = addr;
 854         sc_die = find_best_scope(pf, &die_mem);
 855         if (!sc_die) {
 856                 pr_warning("Failed to find scope of probe point.\n");
 857                 return -ENOENT;
 858         }
 859
 860         ret = call_probe_finder(sc_die, pf);
 861
 862         /* Continue if no error, because the line will be in inline function */
 863         return ret < 0 ? ret : 0;
 864 }
 865
 866 /* Find probe point from its line number */
 867 static int find_probe_point_by_line(struct probe_finder *pf)
 868 {
 869         return die_walk_lines(&pf->cu_die, probe_point_line_walker, pf);
 870 }
 871
 872 /* Find lines which match lazy pattern */
 873 static int find_lazy_match_lines(struct intlist *list,
 874                                  const char *fname, const char *pat)
 875 {
 876         FILE *fp;
 877         char *line = NULL;
 878         size_t line_len;
 879         ssize_t len;
 880         int count = 0, linenum = 1;
 881         char sbuf[STRERR_BUFSIZE];
 882
 883         fp = fopen(fname, "r");
 884         if (!fp) {
 885                 pr_warning("Failed to open %s: %s\n", fname,
 886                            str_error_r(errno, sbuf, sizeof(sbuf)));
 887                 return -errno;
 888         }
 889
 890         while ((len = getline(&line, &line_len, fp)) > 0) {
 891
 892                 if (line[len - 1] == '\n')
 893                         line[len - 1] = '\0';
 894
 895                 if (strlazymatch(line, pat)) {
 896                         intlist__add(list, linenum);
 897                         count++;
 898                 }
 899                 linenum++;
 900         }
 901
 902         if (ferror(fp))
 903                 count = -errno;
 904         free(line);
 905         fclose(fp);
 906
 907         if (count == 0)
 908                 pr_debug("No matched lines found in %s.\n", fname);
 909         return count;
 910 }
 911
 912 static int probe_point_lazy_walker(const char *fname, int lineno,
 913                                    Dwarf_Addr addr, void *data)
 914 {
 915         struct probe_finder *pf = data;
 916         Dwarf_Die *sc_die, die_mem;
 917         int ret;
 918
 919         if (!intlist__has_entry(pf->lcache, lineno) ||
 920             strtailcmp(fname, pf->fname) != 0)
 921                 return 0;
 922
 923         pr_debug("Probe line found: line:%d addr:0x%llx\n",
 924                  lineno, (unsigned long long)addr);
 925         pf->addr = addr;
 926         pf->lno = lineno;
 927         sc_die = find_best_scope(pf, &die_mem);
 928         if (!sc_die) {
 929                 pr_warning("Failed to find scope of probe point.\n");
 930                 return -ENOENT;
 931         }
 932
 933         ret = call_probe_finder(sc_die, pf);
 934
 935         /*
 936          * Continue if no error, because the lazy pattern will match
 937          * to other lines
 938          */
 939         return ret < 0 ? ret : 0;
 940 }
 941
 942 /* Find probe points from lazy pattern  */
 943 static int find_probe_point_lazy(Dwarf_Die *sp_die, struct probe_finder *pf)
 944 {
 945         int ret = 0;
 946         char *fpath;
 947
 948         if (intlist__empty(pf->lcache)) {
 949                 const char *comp_dir;
 950
 951                 comp_dir = cu_get_comp_dir(&pf->cu_die);
 952                 ret = get_real_path(pf->fname, comp_dir, &fpath);
 953                 if (ret < 0) {
 954                         pr_warning("Failed to find source file path.\n");
 955                         return ret;
 956                 }
 957
 958                 /* Matching lazy line pattern */
 959                 ret = find_lazy_match_lines(pf->lcache, fpath,
 960                                             pf->pev->point.lazy_line);
 961                 free(fpath);
 962                 if (ret <= 0)
 963                         return ret;
 964         }
 965
 966         return die_walk_lines(sp_die, probe_point_lazy_walker, pf);
 967 }
 968
 969 static void skip_prologue(Dwarf_Die *sp_die, struct probe_finder *pf)
 970 {
 971         struct perf_probe_point *pp = &pf->pev->point;
 972
 973         /* Not uprobe? */
 974         if (!pf->pev->uprobes)
 975                 return;
 976
 977         /* Compiled with optimization? */
 978         if (die_is_optimized_target(&pf->cu_die))
 979                 return;
 980
 981         /* Don't know entrypc? */
 982         if (!pf->addr)
 983                 return;
 984
 985         /* Only FUNC and FUNC@SRC are eligible. */
 986         if (!pp->function || pp->line || pp->retprobe || pp->lazy_line ||
 987             pp->offset || pp->abs_address)
 988                 return;
 989
 990         /* Not interested in func parameter? */
 991         if (!perf_probe_with_var(pf->pev))
 992                 return;
 993
 994         pr_info("Target program is compiled without optimization. Skipping prologue.\n"
 995                 "Probe on address 0x%" PRIx64 " to force probing at the function entry.\n\n",
 996                 pf->addr);
 997
 998         die_skip_prologue(sp_die, &pf->cu_die, &pf->addr);
 999 }
1000
1001 static int probe_point_inline_cb(Dwarf_Die *in_die, void *data)
1002 {
1003         struct probe_finder *pf = data;
1004         struct perf_probe_point *pp = &pf->pev->point;
1005         Dwarf_Addr addr;
1006         int ret;
1007
1008         if (pp->lazy_line)
1009                 ret = find_probe_point_lazy(in_die, pf);
1010         else {
1011                 /* Get probe address */
1012                 if (die_entrypc(in_die, &addr) != 0) {
1013                         pr_warning("Failed to get entry address of %s.\n",
1014                                    dwarf_diename(in_die));
1015                         return -ENOENT;
1016                 }
1017                 if (addr == 0) {
1018                         pr_debug("%s has no valid entry address. skipped.\n",
1019                                  dwarf_diename(in_die));
1020                         return -ENOENT;
1021                 }
1022                 pf->addr = addr;
1023                 pf->addr += pp->offset;
1024                 pr_debug("found inline addr: 0x%jx\n",
1025                          (uintmax_t)pf->addr);
1026
1027                 ret = call_probe_finder(in_die, pf);
1028         }
1029
1030         return ret;
1031 }
1032
1033 /* Callback parameter with return value for libdw */
1034 struct dwarf_callback_param {
1035         void *data;
1036         int retval;
1037 };
1038
1039 /* Search function from function name */
1040 static int probe_point_search_cb(Dwarf_Die *sp_die, void *data)
1041 {
1042         struct dwarf_callback_param *param = data;
1043         struct probe_finder *pf = param->data;
1044         struct perf_probe_point *pp = &pf->pev->point;
1045
1046         /* Check tag and diename */
1047         if (!die_is_func_def(sp_die) ||
1048             !die_match_name(sp_die, pp->function))
1049                 return DWARF_CB_OK;
1050
1051         /* Check declared file */
1052         if (pp->file && strtailcmp(pp->file, dwarf_decl_file(sp_die)))
1053                 return DWARF_CB_OK;
1054
1055         pr_debug("Matched function: %s [%lx]\n", dwarf_diename(sp_die),
1056                  (unsigned long)dwarf_dieoffset(sp_die));
1057         pf->fname = dwarf_decl_file(sp_die);
1058         if (pp->line) { /* Function relative line */
1059                 dwarf_decl_line(sp_die, &pf->lno);
1060                 pf->lno += pp->line;
1061                 param->retval = find_probe_point_by_line(pf);
1062         } else if (die_is_func_instance(sp_die)) {
1063                 /* Instances always have the entry address */
1064                 die_entrypc(sp_die, &pf->addr);
1065                 /* But in some case the entry address is 0 */
1066                 if (pf->addr == 0) {
1067                         pr_debug("%s has no entry PC. Skipped\n",
1068                                  dwarf_diename(sp_die));
1069                         param->retval = 0;
1070                 /* Real function */
1071                 } else if (pp->lazy_line)
1072                         param->retval = find_probe_point_lazy(sp_die, pf);
1073                 else {
1074                         skip_prologue(sp_die, pf);
1075                         pf->addr += pp->offset;
1076                         /* TODO: Check the address in this function */
1077                         param->retval = call_probe_finder(sp_die, pf);
1078                 }
1079         } else if (!probe_conf.no_inlines) {
1080                 /* Inlined function: search instances */
1081                 param->retval = die_walk_instances(sp_die,
1082                                         probe_point_inline_cb, (void *)pf);
1083                 /* This could be a non-existed inline definition */
1084                 if (param->retval == -ENOENT)
1085                         param->retval = 0;
1086         }
1087
1088         /* We need to find other candidates */
1089         if (strisglob(pp->function) && param->retval >= 0) {
1090                 param->retval = 0;      /* We have to clear the result */
1091                 return DWARF_CB_OK;
1092         }
1093
1094         return DWARF_CB_ABORT; /* Exit; no same symbol in this CU. */
1095 }
1096
1097 static int find_probe_point_by_func(struct probe_finder *pf)
1098 {
1099         struct dwarf_callback_param _param = {.data = (void *)pf,
1100                                               .retval = 0};
1101         dwarf_getfuncs(&pf->cu_die, probe_point_search_cb, &_param, 0);
1102         return _param.retval;
1103 }
1104
1105 struct pubname_callback_param {
1106         char *function;
1107         char *file;
1108         Dwarf_Die *cu_die;
1109         Dwarf_Die *sp_die;
1110         int found;
1111 };
1112
1113 static int pubname_search_cb(Dwarf *dbg, Dwarf_Global *gl, void *data)
1114 {
1115         struct pubname_callback_param *param = data;
1116
1117         if (dwarf_offdie(dbg, gl->die_offset, param->sp_die)) {
1118                 if (dwarf_tag(param->sp_die) != DW_TAG_subprogram)
1119                         return DWARF_CB_OK;
1120
1121                 if (die_match_name(param->sp_die, param->function)) {
1122                         if (!dwarf_offdie(dbg, gl->cu_offset, param->cu_die))
1123                                 return DWARF_CB_OK;
1124
1125                         if (param->file &&
1126                             strtailcmp(param->file, dwarf_decl_file(param->sp_die)))
1127                                 return DWARF_CB_OK;
1128
1129                         param->found = 1;
1130                         return DWARF_CB_ABORT;
1131                 }
1132         }
1133
1134         return DWARF_CB_OK;
1135 }
1136
1137 static int debuginfo__find_probe_location(struct debuginfo *dbg,
1138                                   struct probe_finder *pf)
1139 {
1140         struct perf_probe_point *pp = &pf->pev->point;
1141         Dwarf_Off off, noff;
1142         size_t cuhl;
1143         Dwarf_Die *diep;
1144         int ret = 0;
1145
1146         off = 0;
1147         pf->lcache = intlist__new(NULL);
1148         if (!pf->lcache)
1149                 return -ENOMEM;
1150
1151         /* Fastpath: lookup by function name from .debug_pubnames section */
1152         if (pp->function && !strisglob(pp->function)) {
1153                 struct pubname_callback_param pubname_param = {
1154                         .function = pp->function,
1155                         .file     = pp->file,
1156                         .cu_die   = &pf->cu_die,
1157                         .sp_die   = &pf->sp_die,
1158                         .found    = 0,
1159                 };
1160                 struct dwarf_callback_param probe_param = {
1161                         .data = pf,
1162                 };
1163
1164                 dwarf_getpubnames(dbg->dbg, pubname_search_cb,
1165                                   &pubname_param, 0);
1166                 if (pubname_param.found) {
1167                         ret = probe_point_search_cb(&pf->sp_die, &probe_param);
1168                         if (ret)
1169                                 goto found;
1170                 }
1171         }
1172
1173         /* Loop on CUs (Compilation Unit) */
1174         while (!dwarf_nextcu(dbg->dbg, off, &noff, &cuhl, NULL, NULL, NULL)) {
1175                 /* Get the DIE(Debugging Information Entry) of this CU */
1176                 diep = dwarf_offdie(dbg->dbg, off + cuhl, &pf->cu_die);
1177                 if (!diep)
1178                         continue;
1179
1180                 /* Check if target file is included. */
1181                 if (pp->file)
1182                         pf->fname = cu_find_realpath(&pf->cu_die, pp->file);
1183                 else
1184                         pf->fname = NULL;
1185
1186                 if (!pp->file || pf->fname) {
1187                         if (pp->function)
1188                                 ret = find_probe_point_by_func(pf);
1189                         else if (pp->lazy_line)
1190                                 ret = find_probe_point_lazy(&pf->cu_die, pf);
1191                         else {
1192                                 pf->lno = pp->line;
1193                                 ret = find_probe_point_by_line(pf);
1194                         }
1195                         if (ret < 0)
1196                                 break;
1197                 }
1198                 off = noff;
1199         }
1200
1201 found:
1202         intlist__delete(pf->lcache);
1203         pf->lcache = NULL;
1204
1205         return ret;
1206 }
1207
1208 /* Find probe points from debuginfo */
1209 static int debuginfo__find_probes(struct debuginfo *dbg,
1210                                   struct probe_finder *pf)
1211 {
1212         int ret = 0;
1213         Elf *elf;
1214         GElf_Ehdr ehdr;
1215
1216         if (pf->cfi_eh || pf->cfi_dbg)
1217                 return debuginfo__find_probe_location(dbg, pf);
1218
1219         /* Get the call frame information from this dwarf */
1220         elf = dwarf_getelf(dbg->dbg);
1221         if (elf == NULL)
1222                 return -EINVAL;
1223
1224         if (gelf_getehdr(elf, &ehdr) == NULL)
1225                 return -EINVAL;
1226
1227         pf->machine = ehdr.e_machine;
1228
1229 #if _ELFUTILS_PREREQ(0, 142)
1230         do {
1231                 GElf_Shdr shdr;
1232
1233                 if (elf_section_by_name(elf, &ehdr, &shdr, ".eh_frame", NULL) &&
1234                     shdr.sh_type == SHT_PROGBITS)
1235                         pf->cfi_eh = dwarf_getcfi_elf(elf);
1236
1237                 pf->cfi_dbg = dwarf_getcfi(dbg->dbg);
1238         } while (0);
1239 #endif
1240
1241         ret = debuginfo__find_probe_location(dbg, pf);
1242         return ret;
1243 }
1244
1245 struct local_vars_finder {
1246         struct probe_finder *pf;
1247         struct perf_probe_arg *args;
1248         bool vars;
1249         int max_args;
1250         int nargs;
1251         int ret;
1252 };
1253
1254 /* Collect available variables in this scope */
1255 static int copy_variables_cb(Dwarf_Die *die_mem, void *data)
1256 {
1257         struct local_vars_finder *vf = data;
1258         struct probe_finder *pf = vf->pf;
1259         int tag;
1260
1261         tag = dwarf_tag(die_mem);
1262         if (tag == DW_TAG_formal_parameter ||
1263             (tag == DW_TAG_variable && vf->vars)) {
1264                 if (convert_variable_location(die_mem, vf->pf->addr,
1265                                               vf->pf->fb_ops, &pf->sp_die,
1266                                               pf->machine, NULL) == 0) {
1267                         vf->args[vf->nargs].var = (char *)dwarf_diename(die_mem);
1268                         if (vf->args[vf->nargs].var == NULL) {
1269                                 vf->ret = -ENOMEM;
1270                                 return DIE_FIND_CB_END;
1271                         }
1272                         pr_debug(" %s", vf->args[vf->nargs].var);
1273                         vf->nargs++;
1274                 }
1275         }
1276
1277         if (dwarf_haspc(die_mem, vf->pf->addr))
1278                 return DIE_FIND_CB_CONTINUE;
1279         else
1280                 return DIE_FIND_CB_SIBLING;
1281 }
1282
1283 static int expand_probe_args(Dwarf_Die *sc_die, struct probe_finder *pf,
1284                              struct perf_probe_arg *args)
1285 {
1286         Dwarf_Die die_mem;
1287         int i;
1288         int n = 0;
1289         struct local_vars_finder vf = {.pf = pf, .args = args, .vars = false,
1290                                 .max_args = MAX_PROBE_ARGS, .ret = 0};
1291
1292         for (i = 0; i < pf->pev->nargs; i++) {
1293                 /* var never be NULL */
1294                 if (strcmp(pf->pev->args[i].var, PROBE_ARG_VARS) == 0)
1295                         vf.vars = true;
1296                 else if (strcmp(pf->pev->args[i].var, PROBE_ARG_PARAMS) != 0) {
1297                         /* Copy normal argument */
1298                         args[n] = pf->pev->args[i];
1299                         n++;
1300                         continue;
1301                 }
1302                 pr_debug("Expanding %s into:", pf->pev->args[i].var);
1303                 vf.nargs = n;
1304                 /* Special local variables */
1305                 die_find_child(sc_die, copy_variables_cb, (void *)&vf,
1306                                &die_mem);
1307                 pr_debug(" (%d)\n", vf.nargs - n);
1308                 if (vf.ret < 0)
1309                         return vf.ret;
1310                 n = vf.nargs;
1311         }
1312         return n;
1313 }
1314
1315 static bool trace_event_finder_overlap(struct trace_event_finder *tf)
1316 {
1317         int i;
1318
1319         for (i = 0; i < tf->ntevs; i++) {
1320                 if (tf->pf.addr == tf->tevs[i].point.address)
1321                         return true;
1322         }
1323         return false;
1324 }
1325
1326 /* Add a found probe point into trace event list */
1327 static int add_probe_trace_event(Dwarf_Die *sc_die, struct probe_finder *pf)
1328 {
1329         struct trace_event_finder *tf =
1330                         container_of(pf, struct trace_event_finder, pf);
1331         struct perf_probe_point *pp = &pf->pev->point;
1332         struct probe_trace_event *tev;
1333         struct perf_probe_arg *args = NULL;
1334         int ret, i;
1335
1336         /*
1337          * For some reason (e.g. different column assigned to same address)
1338          * This callback can be called with the address which already passed.
1339          * Ignore it first.
1340          */
1341         if (trace_event_finder_overlap(tf))
1342                 return 0;
1343
1344         /* Check number of tevs */
1345         if (tf->ntevs == tf->max_tevs) {
1346                 pr_warning("Too many( > %d) probe point found.\n",
1347                            tf->max_tevs);
1348                 return -ERANGE;
1349         }
1350         tev = &tf->tevs[tf->ntevs++];
1351
1352         /* Trace point should be converted from subprogram DIE */
1353         ret = convert_to_trace_point(&pf->sp_die, tf->mod, pf->addr,
1354                                      pp->retprobe, pp->function, &tev->point);
1355         if (ret < 0)
1356                 goto end;
1357
1358         tev->point.realname = strdup(dwarf_diename(sc_die));
1359         if (!tev->point.realname) {
1360                 ret = -ENOMEM;
1361                 goto end;
1362         }
1363
1364         pr_debug("Probe point found: %s+%lu\n", tev->point.symbol,
1365                  tev->point.offset);
1366
1367         /* Expand special probe argument if exist */
1368         args = zalloc(sizeof(struct perf_probe_arg) * MAX_PROBE_ARGS);
1369         if (args == NULL) {
1370                 ret = -ENOMEM;
1371                 goto end;
1372         }
1373
1374         ret = expand_probe_args(sc_die, pf, args);
1375         if (ret < 0)
1376                 goto end;
1377
1378         tev->nargs = ret;
1379         tev->args = zalloc(sizeof(struct probe_trace_arg) * tev->nargs);
1380         if (tev->args == NULL) {
1381                 ret = -ENOMEM;
1382                 goto end;
1383         }
1384
1385         /* Find each argument */
1386         for (i = 0; i < tev->nargs; i++) {
1387                 pf->pvar = &args[i];
1388                 pf->tvar = &tev->args[i];
1389                 /* Variable should be found from scope DIE */
1390                 ret = find_variable(sc_die, pf);
1391                 if (ret != 0)
1392                         break;
1393         }
1394
1395 end:
1396         if (ret) {
1397                 clear_probe_trace_event(tev);
1398                 tf->ntevs--;
1399         }
1400         free(args);
1401         return ret;
1402 }
1403
1404 static int fill_empty_trace_arg(struct perf_probe_event *pev,
1405                                 struct probe_trace_event *tevs, int ntevs)
1406 {
1407         char **valp;
1408         char *type;
1409         int i, j, ret;
1410
1411         if (!ntevs)
1412                 return -ENOENT;
1413
1414         for (i = 0; i < pev->nargs; i++) {
1415                 type = NULL;
1416                 for (j = 0; j < ntevs; j++) {
1417                         if (tevs[j].args[i].value) {
1418                                 type = tevs[j].args[i].type;
1419                                 break;
1420                         }
1421                 }
1422                 if (j == ntevs) {
1423                         print_var_not_found(pev->args[i].var);
1424                         return -ENOENT;
1425                 }
1426                 for (j = 0; j < ntevs; j++) {
1427                         valp = &tevs[j].args[i].value;
1428                         if (*valp)
1429                                 continue;
1430
1431                         ret = asprintf(valp, "\\%lx", probe_conf.magic_num);
1432                         if (ret < 0)
1433                                 return -ENOMEM;
1434                         /* Note that type can be NULL */
1435                         if (type) {
1436                                 tevs[j].args[i].type = strdup(type);
1437                                 if (!tevs[j].args[i].type)
1438                                         return -ENOMEM;
1439                         }
1440                 }
1441         }
1442         return 0;
1443 }
1444
1445 /* Find probe_trace_events specified by perf_probe_event from debuginfo */
1446 int debuginfo__find_trace_events(struct debuginfo *dbg,
1447                                  struct perf_probe_event *pev,
1448                                  struct probe_trace_event **tevs)
1449 {
1450         struct trace_event_finder tf = {
1451                         .pf = {.pev = pev, .callback = add_probe_trace_event},
1452                         .max_tevs = probe_conf.max_probes, .mod = dbg->mod};
1453         int ret, i;
1454
1455         /* Allocate result tevs array */
1456         *tevs = zalloc(sizeof(struct probe_trace_event) * tf.max_tevs);
1457         if (*tevs == NULL)
1458                 return -ENOMEM;
1459
1460         tf.tevs = *tevs;
1461         tf.ntevs = 0;
1462
1463         if (pev->nargs != 0 && immediate_value_is_supported())
1464                 tf.pf.skip_empty_arg = true;
1465
1466         ret = debuginfo__find_probes(dbg, &tf.pf);
1467         if (ret >= 0 && tf.pf.skip_empty_arg)
1468                 ret = fill_empty_trace_arg(pev, tf.tevs, tf.ntevs);
1469
1470         if (ret < 0 || tf.ntevs == 0) {
1471                 for (i = 0; i < tf.ntevs; i++)
1472                         clear_probe_trace_event(&tf.tevs[i]);
1473                 zfree(tevs);
1474                 return ret;
1475         }
1476
1477         return (ret < 0) ? ret : tf.ntevs;
1478 }
1479
1480 /* Collect available variables in this scope */
1481 static int collect_variables_cb(Dwarf_Die *die_mem, void *data)
1482 {
1483         struct available_var_finder *af = data;
1484         struct variable_list *vl;
1485         struct strbuf buf = STRBUF_INIT;
1486         int tag, ret;
1487
1488         vl = &af->vls[af->nvls - 1];
1489
1490         tag = dwarf_tag(die_mem);
1491         if (tag == DW_TAG_formal_parameter ||
1492             tag == DW_TAG_variable) {
1493                 ret = convert_variable_location(die_mem, af->pf.addr,
1494                                                 af->pf.fb_ops, &af->pf.sp_die,
1495                                                 af->pf.machine, NULL);
1496                 if (ret == 0 || ret == -ERANGE) {
1497                         int ret2;
1498                         bool externs = !af->child;
1499
1500                         if (strbuf_init(&buf, 64) < 0)
1501                                 goto error;
1502
1503                         if (probe_conf.show_location_range) {
1504                                 if (!externs)
1505                                         ret2 = strbuf_add(&buf,
1506                                                 ret ? "[INV]\t" : "[VAL]\t", 6);
1507                                 else
1508                                         ret2 = strbuf_add(&buf, "[EXT]\t", 6);
1509                                 if (ret2)
1510                                         goto error;
1511                         }
1512
1513                         ret2 = die_get_varname(die_mem, &buf);
1514
1515                         if (!ret2 && probe_conf.show_location_range &&
1516                                 !externs) {
1517                                 if (strbuf_addch(&buf, '\t') < 0)
1518                                         goto error;
1519                                 ret2 = die_get_var_range(&af->pf.sp_die,
1520                                                         die_mem, &buf);
1521                         }
1522
1523                         pr_debug("Add new var: %s\n", buf.buf);
1524                         if (ret2 == 0) {
1525                                 strlist__add(vl->vars,
1526                                         strbuf_detach(&buf, NULL));
1527                         }
1528                         strbuf_release(&buf);
1529                 }
1530         }
1531
1532         if (af->child && dwarf_haspc(die_mem, af->pf.addr))
1533                 return DIE_FIND_CB_CONTINUE;
1534         else
1535                 return DIE_FIND_CB_SIBLING;
1536 error:
1537         strbuf_release(&buf);
1538         pr_debug("Error in strbuf\n");
1539         return DIE_FIND_CB_END;
1540 }
1541
1542 static bool available_var_finder_overlap(struct available_var_finder *af)
1543 {
1544         int i;
1545
1546         for (i = 0; i < af->nvls; i++) {
1547                 if (af->pf.addr == af->vls[i].point.address)
1548                         return true;
1549         }
1550         return false;
1551
1552 }
1553
1554 /* Add a found vars into available variables list */
1555 static int add_available_vars(Dwarf_Die *sc_die, struct probe_finder *pf)
1556 {
1557         struct available_var_finder *af =
1558                         container_of(pf, struct available_var_finder, pf);
1559         struct perf_probe_point *pp = &pf->pev->point;
1560         struct variable_list *vl;
1561         Dwarf_Die die_mem;
1562         int ret;
1563
1564         /*
1565          * For some reason (e.g. different column assigned to same address),
1566          * this callback can be called with the address which already passed.
1567          * Ignore it first.
1568          */
1569         if (available_var_finder_overlap(af))
1570                 return 0;
1571
1572         /* Check number of tevs */
1573         if (af->nvls == af->max_vls) {
1574                 pr_warning("Too many( > %d) probe point found.\n", af->max_vls);
1575                 return -ERANGE;
1576         }
1577         vl = &af->vls[af->nvls++];
1578
1579         /* Trace point should be converted from subprogram DIE */
1580         ret = convert_to_trace_point(&pf->sp_die, af->mod, pf->addr,
1581                                      pp->retprobe, pp->function, &vl->point);
1582         if (ret < 0)
1583                 return ret;
1584
1585         pr_debug("Probe point found: %s+%lu\n", vl->point.symbol,
1586                  vl->point.offset);
1587
1588         /* Find local variables */
1589         vl->vars = strlist__new(NULL, NULL);
1590         if (vl->vars == NULL)
1591                 return -ENOMEM;
1592         af->child = true;
1593         die_find_child(sc_die, collect_variables_cb, (void *)af, &die_mem);
1594
1595         /* Find external variables */
1596         if (!probe_conf.show_ext_vars)
1597                 goto out;
1598         /* Don't need to search child DIE for external vars. */
1599         af->child = false;
1600         die_find_child(&pf->cu_die, collect_variables_cb, (void *)af, &die_mem);
1601
1602 out:
1603         if (strlist__empty(vl->vars)) {
1604                 strlist__delete(vl->vars);
1605                 vl->vars = NULL;
1606         }
1607
1608         return ret;
1609 }
1610
1611 /*
1612  * Find available variables at given probe point
1613  * Return the number of found probe points. Return 0 if there is no
1614  * matched probe point. Return <0 if an error occurs.
1615  */
1616 int debuginfo__find_available_vars_at(struct debuginfo *dbg,
1617                                       struct perf_probe_event *pev,
1618                                       struct variable_list **vls)
1619 {
1620         struct available_var_finder af = {
1621                         .pf = {.pev = pev, .callback = add_available_vars},
1622                         .mod = dbg->mod,
1623                         .max_vls = probe_conf.max_probes};
1624         int ret;
1625
1626         /* Allocate result vls array */
1627         *vls = zalloc(sizeof(struct variable_list) * af.max_vls);
1628         if (*vls == NULL)
1629                 return -ENOMEM;
1630
1631         af.vls = *vls;
1632         af.nvls = 0;
1633
1634         ret = debuginfo__find_probes(dbg, &af.pf);
1635         if (ret < 0) {
1636                 /* Free vlist for error */
1637                 while (af.nvls--) {
1638                         zfree(&af.vls[af.nvls].point.symbol);
1639                         strlist__delete(af.vls[af.nvls].vars);
1640                 }
1641                 zfree(vls);
1642                 return ret;
1643         }
1644
1645         return (ret < 0) ? ret : af.nvls;
1646 }
1647
1648 /* For the kernel module, we need a special code to get a DIE */
1649 int debuginfo__get_text_offset(struct debuginfo *dbg, Dwarf_Addr *offs,
1650                                 bool adjust_offset)
1651 {
1652         int n, i;
1653         Elf32_Word shndx;
1654         Elf_Scn *scn;
1655         Elf *elf;
1656         GElf_Shdr mem, *shdr;
1657         const char *p;
1658
1659         elf = dwfl_module_getelf(dbg->mod, &dbg->bias);
1660         if (!elf)
1661                 return -EINVAL;
1662
1663         /* Get the number of relocations */
1664         n = dwfl_module_relocations(dbg->mod);
1665         if (n < 0)
1666                 return -ENOENT;
1667         /* Search the relocation related .text section */
1668         for (i = 0; i < n; i++) {
1669                 p = dwfl_module_relocation_info(dbg->mod, i, &shndx);
1670                 if (strcmp(p, ".text") == 0) {
1671                         /* OK, get the section header */
1672                         scn = elf_getscn(elf, shndx);
1673                         if (!scn)
1674                                 return -ENOENT;
1675                         shdr = gelf_getshdr(scn, &mem);
1676                         if (!shdr)
1677                                 return -ENOENT;
1678                         *offs = shdr->sh_addr;
1679                         if (adjust_offset)
1680                                 *offs -= shdr->sh_offset;
1681                 }
1682         }
1683         return 0;
1684 }
1685
1686 /* Reverse search */
1687 int debuginfo__find_probe_point(struct debuginfo *dbg, unsigned long addr,
1688                                 struct perf_probe_point *ppt)
1689 {
1690         Dwarf_Die cudie, spdie, indie;
1691         Dwarf_Addr _addr = 0, baseaddr = 0;
1692         const char *fname = NULL, *func = NULL, *basefunc = NULL, *tmp;
1693         int baseline = 0, lineno = 0, ret = 0;
1694
1695         /* We always need to relocate the address for aranges */
1696         if (debuginfo__get_text_offset(dbg, &baseaddr, false) == 0)
1697                 addr += baseaddr;
1698         /* Find cu die */
1699         if (!dwarf_addrdie(dbg->dbg, (Dwarf_Addr)addr, &cudie)) {
1700                 pr_warning("Failed to find debug information for address %lx\n",
1701                            addr);
1702                 ret = -EINVAL;
1703                 goto end;
1704         }
1705
1706         /* Find a corresponding line (filename and lineno) */
1707         cu_find_lineinfo(&cudie, addr, &fname, &lineno);
1708         /* Don't care whether it failed or not */
1709
1710         /* Find a corresponding function (name, baseline and baseaddr) */
1711         if (die_find_realfunc(&cudie, (Dwarf_Addr)addr, &spdie)) {
1712                 /* Get function entry information */
1713                 func = basefunc = dwarf_diename(&spdie);
1714                 if (!func ||
1715                     die_entrypc(&spdie, &baseaddr) != 0 ||
1716                     dwarf_decl_line(&spdie, &baseline) != 0) {
1717                         lineno = 0;
1718                         goto post;
1719                 }
1720
1721                 fname = dwarf_decl_file(&spdie);
1722                 if (addr == (unsigned long)baseaddr) {
1723                         /* Function entry - Relative line number is 0 */
1724                         lineno = baseline;
1725                         goto post;
1726                 }
1727
1728                 /* Track down the inline functions step by step */
1729                 while (die_find_top_inlinefunc(&spdie, (Dwarf_Addr)addr,
1730                                                 &indie)) {
1731                         /* There is an inline function */
1732                         if (die_entrypc(&indie, &_addr) == 0 &&
1733                             _addr == addr) {
1734                                 /*
1735                                  * addr is at an inline function entry.
1736                                  * In this case, lineno should be the call-site
1737                                  * line number. (overwrite lineinfo)
1738                                  */
1739                                 lineno = die_get_call_lineno(&indie);
1740                                 fname = die_get_call_file(&indie);
1741                                 break;
1742                         } else {
1743                                 /*
1744                                  * addr is in an inline function body.
1745                                  * Since lineno points one of the lines
1746                                  * of the inline function, baseline should
1747                                  * be the entry line of the inline function.
1748                                  */
1749                                 tmp = dwarf_diename(&indie);
1750                                 if (!tmp ||
1751                                     dwarf_decl_line(&indie, &baseline) != 0)
1752                                         break;
1753                                 func = tmp;
1754                                 spdie = indie;
1755                         }
1756                 }
1757                 /* Verify the lineno and baseline are in a same file */
1758                 tmp = dwarf_decl_file(&spdie);
1759                 if (!tmp || strcmp(tmp, fname) != 0)
1760                         lineno = 0;
1761         }
1762
1763 post:
1764         /* Make a relative line number or an offset */
1765         if (lineno)
1766                 ppt->line = lineno - baseline;
1767         else if (basefunc) {
1768                 ppt->offset = addr - (unsigned long)baseaddr;
1769                 func = basefunc;
1770         }
1771
1772         /* Duplicate strings */
1773         if (func) {
1774                 ppt->function = strdup(func);
1775                 if (ppt->function == NULL) {
1776                         ret = -ENOMEM;
1777                         goto end;
1778                 }
1779         }
1780         if (fname) {
1781                 ppt->file = strdup(fname);
1782                 if (ppt->file == NULL) {
1783                         zfree(&ppt->function);
1784                         ret = -ENOMEM;
1785                         goto end;
1786                 }
1787         }
1788 end:
1789         if (ret == 0 && (fname || func))
1790                 ret = 1;        /* Found a point */
1791         return ret;
1792 }
1793
1794 /* Add a line and store the src path */
1795 static int line_range_add_line(const char *src, unsigned int lineno,
1796                                struct line_range *lr)
1797 {
1798         /* Copy source path */
1799         if (!lr->path) {
1800                 lr->path = strdup(src);
1801                 if (lr->path == NULL)
1802                         return -ENOMEM;
1803         }
1804         return intlist__add(lr->line_list, lineno);
1805 }
1806
1807 static int line_range_walk_cb(const char *fname, int lineno,
1808                               Dwarf_Addr addr __maybe_unused,
1809                               void *data)
1810 {
1811         struct line_finder *lf = data;
1812         const char *__fname;
1813         int __lineno;
1814         int err;
1815
1816         if ((strtailcmp(fname, lf->fname) != 0) ||
1817             (lf->lno_s > lineno || lf->lno_e < lineno))
1818                 return 0;
1819
1820         /* Make sure this line can be reversable */
1821         if (cu_find_lineinfo(&lf->cu_die, addr, &__fname, &__lineno) > 0
1822             && (lineno != __lineno || strcmp(fname, __fname)))
1823                 return 0;
1824
1825         err = line_range_add_line(fname, lineno, lf->lr);
1826         if (err < 0 && err != -EEXIST)
1827                 return err;
1828
1829         return 0;
1830 }
1831
1832 /* Find line range from its line number */
1833 static int find_line_range_by_line(Dwarf_Die *sp_die, struct line_finder *lf)
1834 {
1835         int ret;
1836
1837         ret = die_walk_lines(sp_die ?: &lf->cu_die, line_range_walk_cb, lf);
1838
1839         /* Update status */
1840         if (ret >= 0)
1841                 if (!intlist__empty(lf->lr->line_list))
1842                         ret = lf->found = 1;
1843                 else
1844                         ret = 0;        /* Lines are not found */
1845         else {
1846                 zfree(&lf->lr->path);
1847         }
1848         return ret;
1849 }
1850
1851 static int line_range_inline_cb(Dwarf_Die *in_die, void *data)
1852 {
1853         int ret = find_line_range_by_line(in_die, data);
1854
1855         /*
1856          * We have to check all instances of inlined function, because
1857          * some execution paths can be optimized out depends on the
1858          * function argument of instances. However, if an error occurs,
1859          * it should be handled by the caller.
1860          */
1861         return ret < 0 ? ret : 0;
1862 }
1863
1864 /* Search function definition from function name */
1865 static int line_range_search_cb(Dwarf_Die *sp_die, void *data)
1866 {
1867         struct dwarf_callback_param *param = data;
1868         struct line_finder *lf = param->data;
1869         struct line_range *lr = lf->lr;
1870
1871         /* Check declared file */
1872         if (lr->file && strtailcmp(lr->file, dwarf_decl_file(sp_die)))
1873                 return DWARF_CB_OK;
1874
1875         if (die_is_func_def(sp_die) &&
1876             die_match_name(sp_die, lr->function)) {
1877                 lf->fname = dwarf_decl_file(sp_die);
1878                 dwarf_decl_line(sp_die, &lr->offset);
1879                 pr_debug("fname: %s, lineno:%d\n", lf->fname, lr->offset);
1880                 lf->lno_s = lr->offset + lr->start;
1881                 if (lf->lno_s < 0)      /* Overflow */
1882                         lf->lno_s = INT_MAX;
1883                 lf->lno_e = lr->offset + lr->end;
1884                 if (lf->lno_e < 0)      /* Overflow */
1885                         lf->lno_e = INT_MAX;
1886                 pr_debug("New line range: %d to %d\n", lf->lno_s, lf->lno_e);
1887                 lr->start = lf->lno_s;
1888                 lr->end = lf->lno_e;
1889                 if (!die_is_func_instance(sp_die))
1890                         param->retval = die_walk_instances(sp_die,
1891                                                 line_range_inline_cb, lf);
1892                 else
1893                         param->retval = find_line_range_by_line(sp_die, lf);
1894                 return DWARF_CB_ABORT;
1895         }
1896         return DWARF_CB_OK;
1897 }
1898
1899 static int find_line_range_by_func(struct line_finder *lf)
1900 {
1901         struct dwarf_callback_param param = {.data = (void *)lf, .retval = 0};
1902         dwarf_getfuncs(&lf->cu_die, line_range_search_cb, &param, 0);
1903         return param.retval;
1904 }
1905
1906 int debuginfo__find_line_range(struct debuginfo *dbg, struct line_range *lr)
1907 {
1908         struct line_finder lf = {.lr = lr, .found = 0};
1909         int ret = 0;
1910         Dwarf_Off off = 0, noff;
1911         size_t cuhl;
1912         Dwarf_Die *diep;
1913         const char *comp_dir;
1914
1915         /* Fastpath: lookup by function name from .debug_pubnames section */
1916         if (lr->function) {
1917                 struct pubname_callback_param pubname_param = {
1918                         .function = lr->function, .file = lr->file,
1919                         .cu_die = &lf.cu_die, .sp_die = &lf.sp_die, .found = 0};
1920                 struct dwarf_callback_param line_range_param = {
1921                         .data = (void *)&lf, .retval = 0};
1922
1923                 dwarf_getpubnames(dbg->dbg, pubname_search_cb,
1924                                   &pubname_param, 0);
1925                 if (pubname_param.found) {
1926                         line_range_search_cb(&lf.sp_die, &line_range_param);
1927                         if (lf.found)
1928                                 goto found;
1929                 }
1930         }
1931
1932         /* Loop on CUs (Compilation Unit) */
1933         while (!lf.found && ret >= 0) {
1934                 if (dwarf_nextcu(dbg->dbg, off, &noff, &cuhl,
1935                                  NULL, NULL, NULL) != 0)
1936                         break;
1937
1938                 /* Get the DIE(Debugging Information Entry) of this CU */
1939                 diep = dwarf_offdie(dbg->dbg, off + cuhl, &lf.cu_die);
1940                 if (!diep)
1941                         continue;
1942
1943                 /* Check if target file is included. */
1944                 if (lr->file)
1945                         lf.fname = cu_find_realpath(&lf.cu_die, lr->file);
1946                 else
1947                         lf.fname = 0;
1948
1949                 if (!lr->file || lf.fname) {
1950                         if (lr->function)
1951                                 ret = find_line_range_by_func(&lf);
1952                         else {
1953                                 lf.lno_s = lr->start;
1954                                 lf.lno_e = lr->end;
1955                                 ret = find_line_range_by_line(NULL, &lf);
1956                         }
1957                 }
1958                 off = noff;
1959         }
1960
1961 found:
1962         /* Store comp_dir */
1963         if (lf.found) {
1964                 comp_dir = cu_get_comp_dir(&lf.cu_die);
1965                 if (comp_dir) {
1966                         lr->comp_dir = strdup(comp_dir);
1967                         if (!lr->comp_dir)
1968                                 ret = -ENOMEM;
1969                 }
1970         }
1971
1972         pr_debug("path: %s\n", lr->path);
1973         return (ret < 0) ? ret : lf.found;
1974 }
1975
1976 /*
1977  * Find a src file from a DWARF tag path. Prepend optional source path prefix
1978  * and chop off leading directories that do not exist. Result is passed back as
1979  * a newly allocated path on success.
1980  * Return 0 if file was found and readable, -errno otherwise.
1981  */
1982 int get_real_path(const char *raw_path, const char *comp_dir,
1983                          char **new_path)
1984 {
1985         const char *prefix = symbol_conf.source_prefix;
1986
1987         if (!prefix) {
1988                 if (raw_path[0] != '/' && comp_dir)
1989                         /* If not an absolute path, try to use comp_dir */
1990                         prefix = comp_dir;
1991                 else {
1992                         if (access(raw_path, R_OK) == 0) {
1993                                 *new_path = strdup(raw_path);
1994                                 return *new_path ? 0 : -ENOMEM;
1995                         } else
1996                                 return -errno;
1997                 }
1998         }
1999
2000         *new_path = malloc((strlen(prefix) + strlen(raw_path) + 2));
2001         if (!*new_path)
2002                 return -ENOMEM;
2003
2004         for (;;) {
2005                 sprintf(*new_path, "%s/%s", prefix, raw_path);
2006
2007                 if (access(*new_path, R_OK) == 0)
2008                         return 0;
2009
2010                 if (!symbol_conf.source_prefix) {
2011                         /* In case of searching comp_dir, don't retry */
2012                         zfree(new_path);
2013                         return -errno;
2014                 }
2015
2016                 switch (errno) {
2017                 case ENAMETOOLONG:
2018                 case ENOENT:
2019                 case EROFS:
2020                 case EFAULT:
2021                         raw_path = strchr(++raw_path, '/');
2022                         if (!raw_path) {
2023                                 zfree(new_path);
2024                                 return -ENOENT;
2025                         }
2026                         continue;
2027
2028                 default:
2029                         zfree(new_path);
2030                         return -errno;
2031                 }
2032         }
2033 }