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