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