tools/perf/util/probe-finder.c

   1 /*
   2  * probe-finder.c : C expression to kprobe event converter
   3  *
   4  * Written by Masami Hiramatsu <mhiramat@redhat.com>
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; either version 2 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program; if not, write to the Free Software
  18  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  19  *
  20  */
  21
  22 #include <sys/utsname.h>
  23 #include <sys/types.h>
  24 #include <sys/stat.h>
  25 #include <fcntl.h>
  26 #include <errno.h>
  27 #include <stdio.h>
  28 #include <unistd.h>
  29 #include <getopt.h>
  30 #include <stdlib.h>
  31 #include <string.h>
  32 #include <stdarg.h>
  33 #include <ctype.h>
  34
  35 #include "event.h"
  36 #include "debug.h"
  37 #include "util.h"
  38 #include "probe-finder.h"
  39
  40
  41 /* Dwarf_Die Linkage to parent Die */
  42 struct die_link {
  43         struct die_link *parent;        /* Parent die */
  44         Dwarf_Die die;                  /* Current die */
  45 };
  46
  47 static Dwarf_Debug __dw_debug;
  48 static Dwarf_Error __dw_error;
  49
  50 /*
  51  * Generic dwarf analysis helpers
  52  */
  53
  54 #define X86_32_MAX_REGS 8
  55 const char *x86_32_regs_table[X86_32_MAX_REGS] = {
  56         "%ax",
  57         "%cx",
  58         "%dx",
  59         "%bx",
  60         "$stack",       /* Stack address instead of %sp */
  61         "%bp",
  62         "%si",
  63         "%di",
  64 };
  65
  66 #define X86_64_MAX_REGS 16
  67 const char *x86_64_regs_table[X86_64_MAX_REGS] = {
  68         "%ax",
  69         "%dx",
  70         "%cx",
  71         "%bx",
  72         "%si",
  73         "%di",
  74         "%bp",
  75         "%sp",
  76         "%r8",
  77         "%r9",
  78         "%r10",
  79         "%r11",
  80         "%r12",
  81         "%r13",
  82         "%r14",
  83         "%r15",
  84 };
  85
  86 /* TODO: switching by dwarf address size */
  87 #ifdef __x86_64__
  88 #define ARCH_MAX_REGS X86_64_MAX_REGS
  89 #define arch_regs_table x86_64_regs_table
  90 #else
  91 #define ARCH_MAX_REGS X86_32_MAX_REGS
  92 #define arch_regs_table x86_32_regs_table
  93 #endif
  94
  95 /* Return architecture dependent register string (for kprobe-tracer) */
  96 static const char *get_arch_regstr(unsigned int n)
  97 {
  98         return (n <= ARCH_MAX_REGS) ? arch_regs_table[n] : NULL;
  99 }
 100
 101 /*
 102  * Compare the tail of two strings.
 103  * Return 0 if whole of either string is same as another's tail part.
 104  */
 105 static int strtailcmp(const char *s1, const char *s2)
 106 {
 107         int i1 = strlen(s1);
 108         int i2 = strlen(s2);
 109         while (--i1 >= 0 && --i2 >= 0) {
 110                 if (s1[i1] != s2[i2])
 111                         return s1[i1] - s2[i2];
 112         }
 113         return 0;
 114 }
 115
 116 /* Find the fileno of the target file. */
 117 static Dwarf_Unsigned cu_find_fileno(Dwarf_Die cu_die, const char *fname)
 118 {
 119         Dwarf_Signed cnt, i;
 120         Dwarf_Unsigned found = 0;
 121         char **srcs;
 122         int ret;
 123
 124         if (!fname)
 125                 return 0;
 126
 127         ret = dwarf_srcfiles(cu_die, &srcs, &cnt, &__dw_error);
 128         if (ret == DW_DLV_OK) {
 129                 for (i = 0; i < cnt && !found; i++) {
 130                         if (strtailcmp(srcs[i], fname) == 0)
 131                                 found = i + 1;
 132                         dwarf_dealloc(__dw_debug, srcs[i], DW_DLA_STRING);
 133                 }
 134                 for (; i < cnt; i++)
 135                         dwarf_dealloc(__dw_debug, srcs[i], DW_DLA_STRING);
 136                 dwarf_dealloc(__dw_debug, srcs, DW_DLA_LIST);
 137         }
 138         if (found)
 139                 pr_debug("found fno: %d\n", (int)found);
 140         return found;
 141 }
 142
 143 /* Compare diename and tname */
 144 static int die_compare_name(Dwarf_Die dw_die, const char *tname)
 145 {
 146         char *name;
 147         int ret;
 148         ret = dwarf_diename(dw_die, &name, &__dw_error);
 149         DIE_IF(ret == DW_DLV_ERROR);
 150         if (ret == DW_DLV_OK) {
 151                 ret = strcmp(tname, name);
 152                 dwarf_dealloc(__dw_debug, name, DW_DLA_STRING);
 153         } else
 154                 ret = -1;
 155         return ret;
 156 }
 157
 158 /* Check the address is in the subprogram(function). */
 159 static int die_within_subprogram(Dwarf_Die sp_die, Dwarf_Addr addr,
 160                                  Dwarf_Signed *offs)
 161 {
 162         Dwarf_Addr lopc, hipc;
 163         int ret;
 164
 165         /* TODO: check ranges */
 166         ret = dwarf_lowpc(sp_die, &lopc, &__dw_error);
 167         DIE_IF(ret == DW_DLV_ERROR);
 168         if (ret == DW_DLV_NO_ENTRY)
 169                 return 0;
 170         ret = dwarf_highpc(sp_die, &hipc, &__dw_error);
 171         DIE_IF(ret != DW_DLV_OK);
 172         if (lopc <= addr && addr < hipc) {
 173                 *offs = addr - lopc;
 174                 return 1;
 175         } else
 176                 return 0;
 177 }
 178
 179 /* Check the die is inlined function */
 180 static Dwarf_Bool die_inlined_subprogram(Dwarf_Die dw_die)
 181 {
 182         /* TODO: check strictly */
 183         Dwarf_Bool inl;
 184         int ret;
 185
 186         ret = dwarf_hasattr(dw_die, DW_AT_inline, &inl, &__dw_error);
 187         DIE_IF(ret == DW_DLV_ERROR);
 188         return inl;
 189 }
 190
 191 /* Get the offset of abstruct_origin */
 192 static Dwarf_Off die_get_abstract_origin(Dwarf_Die dw_die)
 193 {
 194         Dwarf_Attribute attr;
 195         Dwarf_Off cu_offs;
 196         int ret;
 197
 198         ret = dwarf_attr(dw_die, DW_AT_abstract_origin, &attr, &__dw_error);
 199         DIE_IF(ret != DW_DLV_OK);
 200         ret = dwarf_formref(attr, &cu_offs, &__dw_error);
 201         DIE_IF(ret != DW_DLV_OK);
 202         dwarf_dealloc(__dw_debug, attr, DW_DLA_ATTR);
 203         return cu_offs;
 204 }
 205
 206 /* Get entry pc(or low pc, 1st entry of ranges)  of the die */
 207 static Dwarf_Addr die_get_entrypc(Dwarf_Die dw_die)
 208 {
 209         Dwarf_Attribute attr;
 210         Dwarf_Addr addr;
 211         Dwarf_Off offs;
 212         Dwarf_Ranges *ranges;
 213         Dwarf_Signed cnt;
 214         int ret;
 215
 216         /* Try to get entry pc */
 217         ret = dwarf_attr(dw_die, DW_AT_entry_pc, &attr, &__dw_error);
 218         DIE_IF(ret == DW_DLV_ERROR);
 219         if (ret == DW_DLV_OK) {
 220                 ret = dwarf_formaddr(attr, &addr, &__dw_error);
 221                 DIE_IF(ret != DW_DLV_OK);
 222                 dwarf_dealloc(__dw_debug, attr, DW_DLA_ATTR);
 223                 return addr;
 224         }
 225
 226         /* Try to get low pc */
 227         ret = dwarf_lowpc(dw_die, &addr, &__dw_error);
 228         DIE_IF(ret == DW_DLV_ERROR);
 229         if (ret == DW_DLV_OK)
 230                 return addr;
 231
 232         /* Try to get ranges */
 233         ret = dwarf_attr(dw_die, DW_AT_ranges, &attr, &__dw_error);
 234         DIE_IF(ret != DW_DLV_OK);
 235         ret = dwarf_formref(attr, &offs, &__dw_error);
 236         DIE_IF(ret != DW_DLV_OK);
 237         ret = dwarf_get_ranges(__dw_debug, offs, &ranges, &cnt, NULL,
 238                                 &__dw_error);
 239         DIE_IF(ret != DW_DLV_OK);
 240         addr = ranges[0].dwr_addr1;
 241         dwarf_ranges_dealloc(__dw_debug, ranges, cnt);
 242         return addr;
 243 }
 244
 245 /*
 246  * Search a Die from Die tree.
 247  * Note: cur_link->die should be deallocated in this function.
 248  */
 249 static int __search_die_tree(struct die_link *cur_link,
 250                              int (*die_cb)(struct die_link *, void *),
 251                              void *data)
 252 {
 253         Dwarf_Die new_die;
 254         struct die_link new_link;
 255         int ret;
 256
 257         if (!die_cb)
 258                 return 0;
 259
 260         /* Check current die */
 261         while (!(ret = die_cb(cur_link, data))) {
 262                 /* Check child die */
 263                 ret = dwarf_child(cur_link->die, &new_die, &__dw_error);
 264                 DIE_IF(ret == DW_DLV_ERROR);
 265                 if (ret == DW_DLV_OK) {
 266                         new_link.parent = cur_link;
 267                         new_link.die = new_die;
 268                         ret = __search_die_tree(&new_link, die_cb, data);
 269                         if (ret)
 270                                 break;
 271                 }
 272
 273                 /* Move to next sibling */
 274                 ret = dwarf_siblingof(__dw_debug, cur_link->die, &new_die,
 275                                       &__dw_error);
 276                 DIE_IF(ret == DW_DLV_ERROR);
 277                 dwarf_dealloc(__dw_debug, cur_link->die, DW_DLA_DIE);
 278                 cur_link->die = new_die;
 279                 if (ret == DW_DLV_NO_ENTRY)
 280                         return 0;
 281         }
 282         dwarf_dealloc(__dw_debug, cur_link->die, DW_DLA_DIE);
 283         return ret;
 284 }
 285
 286 /* Search a die in its children's die tree */
 287 static int search_die_from_children(Dwarf_Die parent_die,
 288                                     int (*die_cb)(struct die_link *, void *),
 289                                     void *data)
 290 {
 291         struct die_link new_link;
 292         int ret;
 293
 294         new_link.parent = NULL;
 295         ret = dwarf_child(parent_die, &new_link.die, &__dw_error);
 296         DIE_IF(ret == DW_DLV_ERROR);
 297         if (ret == DW_DLV_OK)
 298                 return __search_die_tree(&new_link, die_cb, data);
 299         else
 300                 return 0;
 301 }
 302
 303 /* Find a locdesc corresponding to the address */
 304 static int attr_get_locdesc(Dwarf_Attribute attr, Dwarf_Locdesc *desc,
 305                             Dwarf_Addr addr)
 306 {
 307         Dwarf_Signed lcnt;
 308         Dwarf_Locdesc **llbuf;
 309         int ret, i;
 310
 311         ret = dwarf_loclist_n(attr, &llbuf, &lcnt, &__dw_error);
 312         DIE_IF(ret != DW_DLV_OK);
 313         ret = DW_DLV_NO_ENTRY;
 314         for (i = 0; i < lcnt; ++i) {
 315                 if (llbuf[i]->ld_lopc <= addr &&
 316                     llbuf[i]->ld_hipc > addr) {
 317                         memcpy(desc, llbuf[i], sizeof(Dwarf_Locdesc));
 318                         desc->ld_s =
 319                                 malloc(sizeof(Dwarf_Loc) * llbuf[i]->ld_cents);
 320                         DIE_IF(desc->ld_s == NULL);
 321                         memcpy(desc->ld_s, llbuf[i]->ld_s,
 322                                 sizeof(Dwarf_Loc) * llbuf[i]->ld_cents);
 323                         ret = DW_DLV_OK;
 324                         break;
 325                 }
 326                 dwarf_dealloc(__dw_debug, llbuf[i]->ld_s, DW_DLA_LOC_BLOCK);
 327                 dwarf_dealloc(__dw_debug, llbuf[i], DW_DLA_LOCDESC);
 328         }
 329         /* Releasing loop */
 330         for (; i < lcnt; ++i) {
 331                 dwarf_dealloc(__dw_debug, llbuf[i]->ld_s, DW_DLA_LOC_BLOCK);
 332                 dwarf_dealloc(__dw_debug, llbuf[i], DW_DLA_LOCDESC);
 333         }
 334         dwarf_dealloc(__dw_debug, llbuf, DW_DLA_LIST);
 335         return ret;
 336 }
 337
 338 /* Get decl_file attribute value (file number) */
 339 static Dwarf_Unsigned die_get_decl_file(Dwarf_Die sp_die)
 340 {
 341         Dwarf_Attribute attr;
 342         Dwarf_Unsigned fno;
 343         int ret;
 344
 345         ret = dwarf_attr(sp_die, DW_AT_decl_file, &attr, &__dw_error);
 346         DIE_IF(ret != DW_DLV_OK);
 347         dwarf_formudata(attr, &fno, &__dw_error);
 348         DIE_IF(ret != DW_DLV_OK);
 349         dwarf_dealloc(__dw_debug, attr, DW_DLA_ATTR);
 350         return fno;
 351 }
 352
 353 /* Get decl_line attribute value (line number) */
 354 static Dwarf_Unsigned die_get_decl_line(Dwarf_Die sp_die)
 355 {
 356         Dwarf_Attribute attr;
 357         Dwarf_Unsigned lno;
 358         int ret;
 359
 360         ret = dwarf_attr(sp_die, DW_AT_decl_line, &attr, &__dw_error);
 361         DIE_IF(ret != DW_DLV_OK);
 362         dwarf_formudata(attr, &lno, &__dw_error);
 363         DIE_IF(ret != DW_DLV_OK);
 364         dwarf_dealloc(__dw_debug, attr, DW_DLA_ATTR);
 365         return lno;
 366 }
 367
 368 /*
 369  * Probe finder related functions
 370  */
 371
 372 /* Show a location */
 373 static void show_location(Dwarf_Loc *loc, struct probe_finder *pf)
 374 {
 375         Dwarf_Small op;
 376         Dwarf_Unsigned regn;
 377         Dwarf_Signed offs;
 378         int deref = 0, ret;
 379         const char *regs;
 380
 381         op = loc->lr_atom;
 382
 383         /* If this is based on frame buffer, set the offset */
 384         if (op == DW_OP_fbreg) {
 385                 deref = 1;
 386                 offs = (Dwarf_Signed)loc->lr_number;
 387                 op = pf->fbloc.ld_s[0].lr_atom;
 388                 loc = &pf->fbloc.ld_s[0];
 389         } else
 390                 offs = 0;
 391
 392         if (op >= DW_OP_breg0 && op <= DW_OP_breg31) {
 393                 regn = op - DW_OP_breg0;
 394                 offs += (Dwarf_Signed)loc->lr_number;
 395                 deref = 1;
 396         } else if (op >= DW_OP_reg0 && op <= DW_OP_reg31) {
 397                 regn = op - DW_OP_reg0;
 398         } else if (op == DW_OP_bregx) {
 399                 regn = loc->lr_number;
 400                 offs += (Dwarf_Signed)loc->lr_number2;
 401                 deref = 1;
 402         } else if (op == DW_OP_regx) {
 403                 regn = loc->lr_number;
 404         } else
 405                 die("Dwarf_OP %d is not supported.\n", op);
 406
 407         regs = get_arch_regstr(regn);
 408         if (!regs)
 409                 die("%lld exceeds max register number.\n", regn);
 410
 411         if (deref)
 412                 ret = snprintf(pf->buf, pf->len,
 413                                  " %s=%+lld(%s)", pf->var, offs, regs);
 414         else
 415                 ret = snprintf(pf->buf, pf->len, " %s=%s", pf->var, regs);
 416         DIE_IF(ret < 0);
 417         DIE_IF(ret >= pf->len);
 418 }
 419
 420 /* Show a variables in kprobe event format */
 421 static void show_variable(Dwarf_Die vr_die, struct probe_finder *pf)
 422 {
 423         Dwarf_Attribute attr;
 424         Dwarf_Locdesc ld;
 425         int ret;
 426
 427         ret = dwarf_attr(vr_die, DW_AT_location, &attr, &__dw_error);
 428         if (ret != DW_DLV_OK)
 429                 goto error;
 430         ret = attr_get_locdesc(attr, &ld, (pf->addr - pf->cu_base));
 431         if (ret != DW_DLV_OK)
 432                 goto error;
 433         /* TODO? */
 434         DIE_IF(ld.ld_cents != 1);
 435         show_location(&ld.ld_s[0], pf);
 436         free(ld.ld_s);
 437         dwarf_dealloc(__dw_debug, attr, DW_DLA_ATTR);
 438         return ;
 439 error:
 440         die("Failed to find the location of %s at this address.\n"
 441             " Perhaps, it has been optimized out.\n", pf->var);
 442 }
 443
 444 static int variable_callback(struct die_link *dlink, void *data)
 445 {
 446         struct probe_finder *pf = (struct probe_finder *)data;
 447         Dwarf_Half tag;
 448         int ret;
 449
 450         ret = dwarf_tag(dlink->die, &tag, &__dw_error);
 451         DIE_IF(ret == DW_DLV_ERROR);
 452         if ((tag == DW_TAG_formal_parameter ||
 453              tag == DW_TAG_variable) &&
 454             (die_compare_name(dlink->die, pf->var) == 0)) {
 455                 show_variable(dlink->die, pf);
 456                 return 1;
 457         }
 458         /* TODO: Support struct members and arrays */
 459         return 0;
 460 }
 461
 462 /* Find a variable in a subprogram die */
 463 static void find_variable(Dwarf_Die sp_die, struct probe_finder *pf)
 464 {
 465         int ret;
 466
 467         if (!is_c_varname(pf->var)) {
 468                 /* Output raw parameters */
 469                 ret = snprintf(pf->buf, pf->len, " %s", pf->var);
 470                 DIE_IF(ret < 0);
 471                 DIE_IF(ret >= pf->len);
 472                 return ;
 473         }
 474
 475         pr_debug("Searching '%s' variable in context.\n", pf->var);
 476         /* Search child die for local variables and parameters. */
 477         ret = search_die_from_children(sp_die, variable_callback, pf);
 478         if (!ret)
 479                 die("Failed to find '%s' in this function.\n", pf->var);
 480 }
 481
 482 /* Get a frame base on the address */
 483 static void get_current_frame_base(Dwarf_Die sp_die, struct probe_finder *pf)
 484 {
 485         Dwarf_Attribute attr;
 486         int ret;
 487
 488         ret = dwarf_attr(sp_die, DW_AT_frame_base, &attr, &__dw_error);
 489         DIE_IF(ret != DW_DLV_OK);
 490         ret = attr_get_locdesc(attr, &pf->fbloc, (pf->addr - pf->cu_base));
 491         DIE_IF(ret != DW_DLV_OK);
 492         dwarf_dealloc(__dw_debug, attr, DW_DLA_ATTR);
 493 }
 494
 495 static void free_current_frame_base(struct probe_finder *pf)
 496 {
 497         free(pf->fbloc.ld_s);
 498         memset(&pf->fbloc, 0, sizeof(Dwarf_Locdesc));
 499 }
 500
 501 /* Show a probe point to output buffer */
 502 static void show_probepoint(Dwarf_Die sp_die, Dwarf_Signed offs,
 503                             struct probe_finder *pf)
 504 {
 505         struct probe_point *pp = pf->pp;
 506         char *name;
 507         char tmp[MAX_PROBE_BUFFER];
 508         int ret, i, len;
 509
 510         /* Output name of probe point */
 511         ret = dwarf_diename(sp_die, &name, &__dw_error);
 512         DIE_IF(ret == DW_DLV_ERROR);
 513         if (ret == DW_DLV_OK) {
 514                 ret = snprintf(tmp, MAX_PROBE_BUFFER, "%s+%u", name,
 515                                 (unsigned int)offs);
 516                 /* Copy the function name if possible */
 517                 if (!pp->function) {
 518                         pp->function = strdup(name);
 519                         pp->offset = offs;
 520                 }
 521                 dwarf_dealloc(__dw_debug, name, DW_DLA_STRING);
 522         } else {
 523                 /* This function has no name. */
 524                 ret = snprintf(tmp, MAX_PROBE_BUFFER, "0x%llx", pf->addr);
 525                 if (!pp->function) {
 526                         /* TODO: Use _stext */
 527                         pp->function = strdup("");
 528                         pp->offset = (int)pf->addr;
 529                 }
 530         }
 531         DIE_IF(ret < 0);
 532         DIE_IF(ret >= MAX_PROBE_BUFFER);
 533         len = ret;
 534         pr_debug("Probe point found: %s\n", tmp);
 535
 536         /* Find each argument */
 537         get_current_frame_base(sp_die, pf);
 538         for (i = 0; i < pp->nr_args; i++) {
 539                 pf->var = pp->args[i];
 540                 pf->buf = &tmp[len];
 541                 pf->len = MAX_PROBE_BUFFER - len;
 542                 find_variable(sp_die, pf);
 543                 len += strlen(pf->buf);
 544         }
 545         free_current_frame_base(pf);
 546
 547         pp->probes[pp->found] = strdup(tmp);
 548         pp->found++;
 549 }
 550
 551 static int probeaddr_callback(struct die_link *dlink, void *data)
 552 {
 553         struct probe_finder *pf = (struct probe_finder *)data;
 554         Dwarf_Half tag;
 555         Dwarf_Signed offs;
 556         int ret;
 557
 558         ret = dwarf_tag(dlink->die, &tag, &__dw_error);
 559         DIE_IF(ret == DW_DLV_ERROR);
 560         /* Check the address is in this subprogram */
 561         if (tag == DW_TAG_subprogram &&
 562             die_within_subprogram(dlink->die, pf->addr, &offs)) {
 563                 show_probepoint(dlink->die, offs, pf);
 564                 return 1;
 565         }
 566         return 0;
 567 }
 568
 569 /* Find probe point from its line number */
 570 static void find_by_line(struct probe_finder *pf)
 571 {
 572         Dwarf_Signed cnt, i, clm;
 573         Dwarf_Line *lines;
 574         Dwarf_Unsigned lineno = 0;
 575         Dwarf_Addr addr;
 576         Dwarf_Unsigned fno;
 577         int ret;
 578
 579         ret = dwarf_srclines(pf->cu_die, &lines, &cnt, &__dw_error);
 580         DIE_IF(ret != DW_DLV_OK);
 581
 582         for (i = 0; i < cnt; i++) {
 583                 ret = dwarf_line_srcfileno(lines[i], &fno, &__dw_error);
 584                 DIE_IF(ret != DW_DLV_OK);
 585                 if (fno != pf->fno)
 586                         continue;
 587
 588                 ret = dwarf_lineno(lines[i], &lineno, &__dw_error);
 589                 DIE_IF(ret != DW_DLV_OK);
 590                 if (lineno != pf->lno)
 591                         continue;
 592
 593                 ret = dwarf_lineoff(lines[i], &clm, &__dw_error);
 594                 DIE_IF(ret != DW_DLV_OK);
 595
 596                 ret = dwarf_lineaddr(lines[i], &addr, &__dw_error);
 597                 DIE_IF(ret != DW_DLV_OK);
 598                 pr_debug("Probe line found: line[%d]:%u,%d addr:0x%llx\n",
 599                          (int)i, (unsigned)lineno, (int)clm, addr);
 600                 pf->addr = addr;
 601                 /* Search a real subprogram including this line, */
 602                 ret = search_die_from_children(pf->cu_die,
 603                                                probeaddr_callback, pf);
 604                 if (ret == 0)
 605                         die("Probe point is not found in subprograms.\n");
 606                 /* Continuing, because target line might be inlined. */
 607         }
 608         dwarf_srclines_dealloc(__dw_debug, lines, cnt);
 609 }
 610
 611 /* Search function from function name */
 612 static int probefunc_callback(struct die_link *dlink, void *data)
 613 {
 614         struct probe_finder *pf = (struct probe_finder *)data;
 615         struct probe_point *pp = pf->pp;
 616         struct die_link *lk;
 617         Dwarf_Signed offs;
 618         Dwarf_Half tag;
 619         int ret;
 620
 621         ret = dwarf_tag(dlink->die, &tag, &__dw_error);
 622         DIE_IF(ret == DW_DLV_ERROR);
 623         if (tag == DW_TAG_subprogram) {
 624                 if (die_compare_name(dlink->die, pp->function) == 0) {
 625                         if (pp->line) { /* Function relative line */
 626                                 pf->fno = die_get_decl_file(dlink->die);
 627                                 pf->lno = die_get_decl_line(dlink->die)
 628                                          + pp->line;
 629                                 find_by_line(pf);
 630                                 return 1;
 631                         }
 632                         if (die_inlined_subprogram(dlink->die)) {
 633                                 /* Inlined function, save it. */
 634                                 ret = dwarf_die_CU_offset(dlink->die,
 635                                                           &pf->inl_offs,
 636                                                           &__dw_error);
 637                                 DIE_IF(ret != DW_DLV_OK);
 638                                 pr_debug("inline definition offset %lld\n",
 639                                          pf->inl_offs);
 640                                 return 0;       /* Continue to search */
 641                         }
 642                         /* Get probe address */
 643                         pf->addr = die_get_entrypc(dlink->die);
 644                         pf->addr += pp->offset;
 645                         /* TODO: Check the address in this function */
 646                         show_probepoint(dlink->die, pp->offset, pf);
 647                         return 1; /* Exit; no same symbol in this CU. */
 648                 }
 649         } else if (tag == DW_TAG_inlined_subroutine && pf->inl_offs) {
 650                 if (die_get_abstract_origin(dlink->die) == pf->inl_offs) {
 651                         /* Get probe address */
 652                         pf->addr = die_get_entrypc(dlink->die);
 653                         pf->addr += pp->offset;
 654                         pr_debug("found inline addr: 0x%llx\n", pf->addr);
 655                         /* Inlined function. Get a real subprogram */
 656                         for (lk = dlink->parent; lk != NULL; lk = lk->parent) {
 657                                 tag = 0;
 658                                 dwarf_tag(lk->die, &tag, &__dw_error);
 659                                 DIE_IF(ret == DW_DLV_ERROR);
 660                                 if (tag == DW_TAG_subprogram &&
 661                                     !die_inlined_subprogram(lk->die))
 662                                         goto found;
 663                         }
 664                         die("Failed to find real subprogram.\n");
 665 found:
 666                         /* Get offset from subprogram */
 667                         ret = die_within_subprogram(lk->die, pf->addr, &offs);
 668                         DIE_IF(!ret);
 669                         show_probepoint(lk->die, offs, pf);
 670                         /* Continue to search */
 671                 }
 672         }
 673         return 0;
 674 }
 675
 676 static void find_by_func(struct probe_finder *pf)
 677 {
 678         search_die_from_children(pf->cu_die, probefunc_callback, pf);
 679 }
 680
 681 /* Find a probe point */
 682 int find_probepoint(int fd, struct probe_point *pp)
 683 {
 684         Dwarf_Half addr_size = 0;
 685         Dwarf_Unsigned next_cuh = 0;
 686         int cu_number = 0, ret;
 687         struct probe_finder pf = {.pp = pp};
 688
 689         ret = dwarf_init(fd, DW_DLC_READ, 0, 0, &__dw_debug, &__dw_error);
 690         if (ret != DW_DLV_OK) {
 691                 pr_warning("No dwarf info found in the vmlinux - please rebuild with CONFIG_DEBUG_INFO.\n");
 692                 return -ENOENT;
 693         }
 694
 695         pp->found = 0;
 696         while (++cu_number) {
 697                 /* Search CU (Compilation Unit) */
 698                 ret = dwarf_next_cu_header(__dw_debug, NULL, NULL, NULL,
 699                         &addr_size, &next_cuh, &__dw_error);
 700                 DIE_IF(ret == DW_DLV_ERROR);
 701                 if (ret == DW_DLV_NO_ENTRY)
 702                         break;
 703
 704                 /* Get the DIE(Debugging Information Entry) of this CU */
 705                 ret = dwarf_siblingof(__dw_debug, 0, &pf.cu_die, &__dw_error);
 706                 DIE_IF(ret != DW_DLV_OK);
 707
 708                 /* Check if target file is included. */
 709                 if (pp->file)
 710                         pf.fno = cu_find_fileno(pf.cu_die, pp->file);
 711
 712                 if (!pp->file || pf.fno) {
 713                         /* Save CU base address (for frame_base) */
 714                         ret = dwarf_lowpc(pf.cu_die, &pf.cu_base, &__dw_error);
 715                         DIE_IF(ret == DW_DLV_ERROR);
 716                         if (ret == DW_DLV_NO_ENTRY)
 717                                 pf.cu_base = 0;
 718                         if (pp->function)
 719                                 find_by_func(&pf);
 720                         else {
 721                                 pf.lno = pp->line;
 722                                 find_by_line(&pf);
 723                         }
 724                 }
 725                 dwarf_dealloc(__dw_debug, pf.cu_die, DW_DLA_DIE);
 726         }
 727         ret = dwarf_finish(__dw_debug, &__dw_error);
 728         DIE_IF(ret != DW_DLV_OK);
 729
 730         return pp->found;
 731 }
 732