1// SPDX-License-Identifier: GPL-2.0-or-later
   2/*
   3 * dwarf-aux.c : libdw auxiliary interfaces
   4 */
   5
   6#include <errno.h>
   7#include <inttypes.h>
   8#include <stdbool.h>
   9#include <stdlib.h>
  10#include "debug.h"
  11#include "dwarf-aux.h"
  12#include "strbuf.h"
  13#include "string2.h"
  14
  15/**
  16 * cu_find_realpath - Find the realpath of the target file
  17 * @cu_die: A DIE(dwarf information entry) of CU(compilation Unit)
  18 * @fname:  The tail filename of the target file
  19 *
  20 * Find the real(long) path of @fname in @cu_die.
  21 */
  22const char *cu_find_realpath(Dwarf_Die *cu_die, const char *fname)
  23{
  24	Dwarf_Files *files;
  25	size_t nfiles, i;
  26	const char *src = NULL;
  27	int ret;
  28
  29	if (!fname)
  30		return NULL;
  31
  32	ret = dwarf_getsrcfiles(cu_die, &files, &nfiles);
  33	if (ret != 0)
  34		return NULL;
  35
  36	for (i = 0; i < nfiles; i++) {
  37		src = dwarf_filesrc(files, i, NULL, NULL);
  38		if (strtailcmp(src, fname) == 0)
  39			break;
  40	}
  41	if (i == nfiles)
  42		return NULL;
  43	return src;
  44}
  45
  46/**
  47 * cu_get_comp_dir - Get the path of compilation directory
  48 * @cu_die: a CU DIE
  49 *
  50 * Get the path of compilation directory of given @cu_die.
  51 * Since this depends on DW_AT_comp_dir, older gcc will not
  52 * embedded it. In that case, this returns NULL.
  53 */
  54const char *cu_get_comp_dir(Dwarf_Die *cu_die)
  55{
  56	Dwarf_Attribute attr;
  57	if (dwarf_attr(cu_die, DW_AT_comp_dir, &attr) == NULL)
  58		return NULL;
  59	return dwarf_formstring(&attr);
  60}
  61
  62/* Unlike dwarf_getsrc_die(), cu_getsrc_die() only returns statement line */
  63static Dwarf_Line *cu_getsrc_die(Dwarf_Die *cu_die, Dwarf_Addr addr)
  64{
  65	Dwarf_Addr laddr;
  66	Dwarf_Lines *lines;
  67	Dwarf_Line *line;
  68	size_t nlines, l, u, n;
  69	bool flag;
  70
  71	if (dwarf_getsrclines(cu_die, &lines, &nlines) != 0 ||
  72	    nlines == 0)
  73		return NULL;
  74
  75	/* Lines are sorted by address, use binary search */
  76	l = 0; u = nlines - 1;
  77	while (l < u) {
  78		n = u - (u - l) / 2;
  79		line = dwarf_onesrcline(lines, n);
  80		if (!line || dwarf_lineaddr(line, &laddr) != 0)
  81			return NULL;
  82		if (addr < laddr)
  83			u = n - 1;
  84		else
  85			l = n;
  86	}
  87	/* Going backward to find the lowest line */
  88	do {
  89		line = dwarf_onesrcline(lines, --l);
  90		if (!line || dwarf_lineaddr(line, &laddr) != 0)
  91			return NULL;
  92	} while (laddr == addr);
  93	l++;
  94	/* Going forward to find the statement line */
  95	do {
  96		line = dwarf_onesrcline(lines, l++);
  97		if (!line || dwarf_lineaddr(line, &laddr) != 0 ||
  98		    dwarf_linebeginstatement(line, &flag) != 0)
  99			return NULL;
 100		if (laddr > addr)
 101			return NULL;
 102	} while (!flag);
 103
 104	return line;
 105}
 106
 107/**
 108 * cu_find_lineinfo - Get a line number and file name for given address
 109 * @cu_die: a CU DIE
 110 * @addr: An address
 111 * @fname: a pointer which returns the file name string
 112 * @lineno: a pointer which returns the line number
 113 *
 114 * Find a line number and file name for @addr in @cu_die.
 115 */
 116int cu_find_lineinfo(Dwarf_Die *cu_die, Dwarf_Addr addr,
 117		     const char **fname, int *lineno)
 118{
 119	Dwarf_Line *line;
 120	Dwarf_Die die_mem;
 121	Dwarf_Addr faddr;
 122
 123	if (die_find_realfunc(cu_die, addr, &die_mem)
 124	    && die_entrypc(&die_mem, &faddr) == 0 &&
 125	    faddr == addr) {
 126		*fname = die_get_decl_file(&die_mem);
 127		dwarf_decl_line(&die_mem, lineno);
 128		goto out;
 129	}
 130
 131	line = cu_getsrc_die(cu_die, addr);
 132	if (line && dwarf_lineno(line, lineno) == 0) {
 133		*fname = dwarf_linesrc(line, NULL, NULL);
 134		if (!*fname)
 135			/* line number is useless without filename */
 136			*lineno = 0;
 137	}
 138
 139out:
 140	return (*lineno && *fname) ? *lineno : -ENOENT;
 141}
 142
 143static int __die_find_inline_cb(Dwarf_Die *die_mem, void *data);
 144
 145/**
 146 * cu_walk_functions_at - Walk on function DIEs at given address
 147 * @cu_die: A CU DIE
 148 * @addr: An address
 149 * @callback: A callback which called with found DIEs
 150 * @data: A user data
 151 *
 152 * Walk on function DIEs at given @addr in @cu_die. Passed DIEs
 153 * should be subprogram or inlined-subroutines.
 154 */
 155int cu_walk_functions_at(Dwarf_Die *cu_die, Dwarf_Addr addr,
 156		    int (*callback)(Dwarf_Die *, void *), void *data)
 157{
 158	Dwarf_Die die_mem;
 159	Dwarf_Die *sc_die;
 160	int ret = -ENOENT;
 161
 162	/* Inlined function could be recursive. Trace it until fail */
 163	for (sc_die = die_find_realfunc(cu_die, addr, &die_mem);
 164	     sc_die != NULL;
 165	     sc_die = die_find_child(sc_die, __die_find_inline_cb, &addr,
 166				     &die_mem)) {
 167		ret = callback(sc_die, data);
 168		if (ret)
 169			break;
 170	}
 171
 172	return ret;
 173
 174}
 175
 176/**
 177 * die_get_linkage_name - Get the linkage name of the object
 178 * @dw_die: A DIE of the object
 179 *
 180 * Get the linkage name attribute of given @dw_die.
 181 * For C++ binary, the linkage name will be the mangled symbol.
 182 */
 183const char *die_get_linkage_name(Dwarf_Die *dw_die)
 184{
 185	Dwarf_Attribute attr;
 186
 187	if (dwarf_attr_integrate(dw_die, DW_AT_linkage_name, &attr) == NULL)
 188		return NULL;
 189	return dwarf_formstring(&attr);
 190}
 191
 192/**
 193 * die_compare_name - Compare diename and tname
 194 * @dw_die: a DIE
 195 * @tname: a string of target name
 196 *
 197 * Compare the name of @dw_die and @tname. Return false if @dw_die has no name.
 198 */
 199bool die_compare_name(Dwarf_Die *dw_die, const char *tname)
 200{
 201	const char *name;
 202
 203	name = dwarf_diename(dw_die);
 204	return name ? (strcmp(tname, name) == 0) : false;
 205}
 206
 207/**
 208 * die_match_name - Match diename/linkage name and glob
 209 * @dw_die: a DIE
 210 * @glob: a string of target glob pattern
 211 *
 212 * Glob matching the name of @dw_die and @glob. Return false if matching fail.
 213 * This also match linkage name.
 214 */
 215bool die_match_name(Dwarf_Die *dw_die, const char *glob)
 216{
 217	const char *name;
 218
 219	name = dwarf_diename(dw_die);
 220	if (name && strglobmatch(name, glob))
 221		return true;
 222	/* fall back to check linkage name */
 223	name = die_get_linkage_name(dw_die);
 224	if (name && strglobmatch(name, glob))
 225		return true;
 226
 227	return false;
 228}
 229
 230/**
 231 * die_get_call_lineno - Get callsite line number of inline-function instance
 232 * @in_die: a DIE of an inlined function instance
 233 *
 234 * Get call-site line number of @in_die. This means from where the inline
 235 * function is called.
 236 */
 237int die_get_call_lineno(Dwarf_Die *in_die)
 238{
 239	Dwarf_Attribute attr;
 240	Dwarf_Word ret;
 241
 242	if (!dwarf_attr(in_die, DW_AT_call_line, &attr))
 243		return -ENOENT;
 244
 245	dwarf_formudata(&attr, &ret);
 246	return (int)ret;
 247}
 248
 249/**
 250 * die_get_type - Get type DIE
 251 * @vr_die: a DIE of a variable
 252 * @die_mem: where to store a type DIE
 253 *
 254 * Get a DIE of the type of given variable (@vr_die), and store
 255 * it to die_mem. Return NULL if fails to get a type DIE.
 256 */
 257Dwarf_Die *die_get_type(Dwarf_Die *vr_die, Dwarf_Die *die_mem)
 258{
 259	Dwarf_Attribute attr;
 260
 261	if (dwarf_attr_integrate(vr_die, DW_AT_type, &attr) &&
 262	    dwarf_formref_die(&attr, die_mem))
 263		return die_mem;
 264	else
 265		return NULL;
 266}
 267
 268/* Get a type die, but skip qualifiers */
 269static Dwarf_Die *__die_get_real_type(Dwarf_Die *vr_die, Dwarf_Die *die_mem)
 270{
 271	int tag;
 272
 273	do {
 274		vr_die = die_get_type(vr_die, die_mem);
 275		if (!vr_die)
 276			break;
 277		tag = dwarf_tag(vr_die);
 278	} while (tag == DW_TAG_const_type ||
 279		 tag == DW_TAG_restrict_type ||
 280		 tag == DW_TAG_volatile_type ||
 281		 tag == DW_TAG_shared_type);
 282
 283	return vr_die;
 284}
 285
 286/**
 287 * die_get_real_type - Get a type die, but skip qualifiers and typedef
 288 * @vr_die: a DIE of a variable
 289 * @die_mem: where to store a type DIE
 290 *
 291 * Get a DIE of the type of given variable (@vr_die), and store
 292 * it to die_mem. Return NULL if fails to get a type DIE.
 293 * If the type is qualifiers (e.g. const) or typedef, this skips it
 294 * and tries to find real type (structure or basic types, e.g. int).
 295 */
 296Dwarf_Die *die_get_real_type(Dwarf_Die *vr_die, Dwarf_Die *die_mem)
 297{
 298	do {
 299		vr_die = __die_get_real_type(vr_die, die_mem);
 300	} while (vr_die && dwarf_tag(vr_die) == DW_TAG_typedef);
 301
 302	return vr_die;
 303}
 304
 305/* Get attribute and translate it as a udata */
 306static int die_get_attr_udata(Dwarf_Die *tp_die, unsigned int attr_name,
 307			      Dwarf_Word *result)
 308{
 309	Dwarf_Attribute attr;
 310
 311	if (dwarf_attr_integrate(tp_die, attr_name, &attr) == NULL ||
 312	    dwarf_formudata(&attr, result) != 0)
 313		return -ENOENT;
 314
 315	return 0;
 316}
 317
 318/**
 319 * die_is_signed_type - Check whether a type DIE is signed or not
 320 * @tp_die: a DIE of a type
 321 *
 322 * Get the encoding of @tp_die and return true if the encoding
 323 * is signed.
 324 */
 325bool die_is_signed_type(Dwarf_Die *tp_die)
 326{
 327	Dwarf_Word ret;
 328
 329	if (die_get_attr_udata(tp_die, DW_AT_encoding, &ret))
 330		return false;
 331
 332	return (ret == DW_ATE_signed_char || ret == DW_ATE_signed ||
 333		ret == DW_ATE_signed_fixed);
 334}
 335
 336/**
 337 * die_is_func_def - Ensure that this DIE is a subprogram and definition
 338 * @dw_die: a DIE
 339 *
 340 * Ensure that this DIE is a subprogram and NOT a declaration. This
 341 * returns true if @dw_die is a function definition.
 342 **/
 343bool die_is_func_def(Dwarf_Die *dw_die)
 344{
 345	Dwarf_Attribute attr;
 346	Dwarf_Addr addr = 0;
 347
 348	if (dwarf_tag(dw_die) != DW_TAG_subprogram)
 349		return false;
 350
 351	if (dwarf_attr(dw_die, DW_AT_declaration, &attr))
 352		return false;
 353
 354	/*
 355	 * DW_AT_declaration can be lost from function declaration
 356	 * by gcc's bug #97060.
 357	 * So we need to check this subprogram DIE has DW_AT_inline
 358	 * or an entry address.
 359	 */
 360	if (!dwarf_attr(dw_die, DW_AT_inline, &attr) &&
 361	    die_entrypc(dw_die, &addr) < 0)
 362		return false;
 363
 364	return true;
 365}
 366
 367/**
 368 * die_entrypc - Returns entry PC (the lowest address) of a DIE
 369 * @dw_die: a DIE
 370 * @addr: where to store entry PC
 371 *
 372 * Since dwarf_entrypc() does not return entry PC if the DIE has only address
 373 * range, we have to use this to retrieve the lowest address from the address
 374 * range attribute.
 375 */
 376int die_entrypc(Dwarf_Die *dw_die, Dwarf_Addr *addr)
 377{
 378	Dwarf_Addr base, end;
 379	Dwarf_Attribute attr;
 380
 381	if (!addr)
 382		return -EINVAL;
 383
 384	if (dwarf_entrypc(dw_die, addr) == 0)
 385		return 0;
 386
 387	/*
 388	 *  Since the dwarf_ranges() will return 0 if there is no
 389	 * DW_AT_ranges attribute, we should check it first.
 390	 */
 391	if (!dwarf_attr(dw_die, DW_AT_ranges, &attr))
 392		return -ENOENT;
 393
 394	return dwarf_ranges(dw_die, 0, &base, addr, &end) < 0 ? -ENOENT : 0;
 395}
 396
 397/**
 398 * die_is_func_instance - Ensure that this DIE is an instance of a subprogram
 399 * @dw_die: a DIE
 400 *
 401 * Ensure that this DIE is an instance (which has an entry address).
 402 * This returns true if @dw_die is a function instance. If not, the @dw_die
 403 * must be a prototype. You can use die_walk_instances() to find actual
 404 * instances.
 405 **/
 406bool die_is_func_instance(Dwarf_Die *dw_die)
 407{
 408	Dwarf_Addr tmp;
 409	Dwarf_Attribute attr_mem;
 410	int tag = dwarf_tag(dw_die);
 411
 412	if (tag != DW_TAG_subprogram &&
 413	    tag != DW_TAG_inlined_subroutine)
 414		return false;
 415
 416	return dwarf_entrypc(dw_die, &tmp) == 0 ||
 417		dwarf_attr(dw_die, DW_AT_ranges, &attr_mem) != NULL;
 418}
 419
 420/**
 421 * die_get_data_member_location - Get the data-member offset
 422 * @mb_die: a DIE of a member of a data structure
 423 * @offs: The offset of the member in the data structure
 424 *
 425 * Get the offset of @mb_die in the data structure including @mb_die, and
 426 * stores result offset to @offs. If any error occurs this returns errno.
 427 */
 428int die_get_data_member_location(Dwarf_Die *mb_die, Dwarf_Word *offs)
 429{
 430	Dwarf_Attribute attr;
 431	Dwarf_Op *expr;
 432	size_t nexpr;
 433	int ret;
 434
 435	if (dwarf_attr(mb_die, DW_AT_data_member_location, &attr) == NULL)
 436		return -ENOENT;
 437
 438	if (dwarf_formudata(&attr, offs) != 0) {
 439		/* DW_AT_data_member_location should be DW_OP_plus_uconst */
 440		ret = dwarf_getlocation(&attr, &expr, &nexpr);
 441		if (ret < 0 || nexpr == 0)
 442			return -ENOENT;
 443
 444		if (expr[0].atom != DW_OP_plus_uconst || nexpr != 1) {
 445			pr_debug("Unable to get offset:Unexpected OP %x (%zd)\n",
 446				 expr[0].atom, nexpr);
 447			return -ENOTSUP;
 448		}
 449		*offs = (Dwarf_Word)expr[0].number;
 450	}
 451	return 0;
 452}
 453
 454/* Get the call file index number in CU DIE */
 455static int die_get_call_fileno(Dwarf_Die *in_die)
 456{
 457	Dwarf_Word idx;
 458
 459	if (die_get_attr_udata(in_die, DW_AT_call_file, &idx) == 0)
 460		return (int)idx;
 461	else
 462		return -ENOENT;
 463}
 464
 465/* Get the declared file index number in CU DIE */
 466static int die_get_decl_fileno(Dwarf_Die *pdie)
 467{
 468	Dwarf_Word idx;
 469
 470	if (die_get_attr_udata(pdie, DW_AT_decl_file, &idx) == 0)
 471		return (int)idx;
 472	else
 473		return -ENOENT;
 474}
 475
 476/* Return the file name by index */
 477static const char *die_get_file_name(Dwarf_Die *dw_die, int idx)
 478{
 479	Dwarf_Die cu_die;
 480	Dwarf_Files *files;
 481	Dwarf_Attribute attr_mem;
 482
 483	if (idx < 0 || !dwarf_attr_integrate(dw_die, DW_AT_decl_file, &attr_mem) ||
 484	    !dwarf_cu_die(attr_mem.cu, &cu_die, NULL, NULL, NULL, NULL, NULL, NULL) ||
 485	    dwarf_getsrcfiles(&cu_die, &files, NULL) != 0)
 486		return NULL;
 487
 488	return dwarf_filesrc(files, idx, NULL, NULL);
 489}
 490
 491/**
 492 * die_get_call_file - Get callsite file name of inlined function instance
 493 * @in_die: a DIE of an inlined function instance
 494 *
 495 * Get call-site file name of @in_die. This means from which file the inline
 496 * function is called.
 497 */
 498const char *die_get_call_file(Dwarf_Die *in_die)
 499{
 500	return die_get_file_name(in_die, die_get_call_fileno(in_die));
 501}
 502
 503/**
 504 * die_get_decl_file - Find the declared file name of this DIE
 505 * @dw_die: a DIE for something declared.
 506 *
 507 * Get declared file name of @dw_die.
 508 * NOTE: Since some version of clang DWARF5 implementation incorrectly uses
 509 * file index 0 for DW_AT_decl_file, die_get_decl_file() will return NULL for
 510 * such cases. Use this function instead.
 511 */
 512const char *die_get_decl_file(Dwarf_Die *dw_die)
 513{
 514	return die_get_file_name(dw_die, die_get_decl_fileno(dw_die));
 515}
 516
 517/**
 518 * die_find_child - Generic DIE search function in DIE tree
 519 * @rt_die: a root DIE
 520 * @callback: a callback function
 521 * @data: a user data passed to the callback function
 522 * @die_mem: a buffer for result DIE
 523 *
 524 * Trace DIE tree from @rt_die and call @callback for each child DIE.
 525 * If @callback returns DIE_FIND_CB_END, this stores the DIE into
 526 * @die_mem and returns it. If @callback returns DIE_FIND_CB_CONTINUE,
 527 * this continues to trace the tree. Optionally, @callback can return
 528 * DIE_FIND_CB_CHILD and DIE_FIND_CB_SIBLING, those means trace only
 529 * the children and trace only the siblings respectively.
 530 * Returns NULL if @callback can't find any appropriate DIE.
 531 */
 532Dwarf_Die *die_find_child(Dwarf_Die *rt_die,
 533			  int (*callback)(Dwarf_Die *, void *),
 534			  void *data, Dwarf_Die *die_mem)
 535{
 536	Dwarf_Die child_die;
 537	int ret;
 538
 539	ret = dwarf_child(rt_die, die_mem);
 540	if (ret != 0)
 541		return NULL;
 542
 543	do {
 544		ret = callback(die_mem, data);
 545		if (ret == DIE_FIND_CB_END)
 546			return die_mem;
 547
 548		if ((ret & DIE_FIND_CB_CHILD) &&
 549		    die_find_child(die_mem, callback, data, &child_die)) {
 550			memcpy(die_mem, &child_die, sizeof(Dwarf_Die));
 551			return die_mem;
 552		}
 553	} while ((ret & DIE_FIND_CB_SIBLING) &&
 554		 dwarf_siblingof(die_mem, die_mem) == 0);
 555
 556	return NULL;
 557}
 558
 559struct __addr_die_search_param {
 560	Dwarf_Addr	addr;
 561	Dwarf_Die	*die_mem;
 562};
 563
 564static int __die_search_func_tail_cb(Dwarf_Die *fn_die, void *data)
 565{
 566	struct __addr_die_search_param *ad = data;
 567	Dwarf_Addr addr = 0;
 568
 569	if (dwarf_tag(fn_die) == DW_TAG_subprogram &&
 570	    !dwarf_highpc(fn_die, &addr) &&
 571	    addr == ad->addr) {
 572		memcpy(ad->die_mem, fn_die, sizeof(Dwarf_Die));
 573		return DWARF_CB_ABORT;
 574	}
 575	return DWARF_CB_OK;
 576}
 577
 578/**
 579 * die_find_tailfunc - Search for a non-inlined function with tail call at
 580 * given address
 581 * @cu_die: a CU DIE which including @addr
 582 * @addr: target address
 583 * @die_mem: a buffer for result DIE
 584 *
 585 * Search for a non-inlined function DIE with tail call at @addr. Stores the
 586 * DIE to @die_mem and returns it if found. Returns NULL if failed.
 587 */
 588Dwarf_Die *die_find_tailfunc(Dwarf_Die *cu_die, Dwarf_Addr addr,
 589				    Dwarf_Die *die_mem)
 590{
 591	struct __addr_die_search_param ad;
 592	ad.addr = addr;
 593	ad.die_mem = die_mem;
 594	/* dwarf_getscopes can't find subprogram. */
 595	if (!dwarf_getfuncs(cu_die, __die_search_func_tail_cb, &ad, 0))
 596		return NULL;
 597	else
 598		return die_mem;
 599}
 600
 601/* die_find callback for non-inlined function search */
 602static int __die_search_func_cb(Dwarf_Die *fn_die, void *data)
 603{
 604	struct __addr_die_search_param *ad = data;
 605
 606	/*
 607	 * Since a declaration entry doesn't has given pc, this always returns
 608	 * function definition entry.
 609	 */
 610	if (dwarf_tag(fn_die) == DW_TAG_subprogram &&
 611	    dwarf_haspc(fn_die, ad->addr)) {
 612		memcpy(ad->die_mem, fn_die, sizeof(Dwarf_Die));
 613		return DWARF_CB_ABORT;
 614	}
 615	return DWARF_CB_OK;
 616}
 617
 618/**
 619 * die_find_realfunc - Search a non-inlined function at given address
 620 * @cu_die: a CU DIE which including @addr
 621 * @addr: target address
 622 * @die_mem: a buffer for result DIE
 623 *
 624 * Search a non-inlined function DIE which includes @addr. Stores the
 625 * DIE to @die_mem and returns it if found. Returns NULL if failed.
 626 */
 627Dwarf_Die *die_find_realfunc(Dwarf_Die *cu_die, Dwarf_Addr addr,
 628				    Dwarf_Die *die_mem)
 629{
 630	struct __addr_die_search_param ad;
 631	ad.addr = addr;
 632	ad.die_mem = die_mem;
 633	/* dwarf_getscopes can't find subprogram. */
 634	if (!dwarf_getfuncs(cu_die, __die_search_func_cb, &ad, 0))
 635		return NULL;
 636	else
 637		return die_mem;
 638}
 639
 640/* die_find callback for inline function search */
 641static int __die_find_inline_cb(Dwarf_Die *die_mem, void *data)
 642{
 643	Dwarf_Addr *addr = data;
 644
 645	if (dwarf_tag(die_mem) == DW_TAG_inlined_subroutine &&
 646	    dwarf_haspc(die_mem, *addr))
 647		return DIE_FIND_CB_END;
 648
 649	return DIE_FIND_CB_CONTINUE;
 650}
 651
 652/**
 653 * die_find_top_inlinefunc - Search the top inlined function at given address
 654 * @sp_die: a subprogram DIE which including @addr
 655 * @addr: target address
 656 * @die_mem: a buffer for result DIE
 657 *
 658 * Search an inlined function DIE which includes @addr. Stores the
 659 * DIE to @die_mem and returns it if found. Returns NULL if failed.
 660 * Even if several inlined functions are expanded recursively, this
 661 * doesn't trace it down, and returns the topmost one.
 662 */
 663Dwarf_Die *die_find_top_inlinefunc(Dwarf_Die *sp_die, Dwarf_Addr addr,
 664				   Dwarf_Die *die_mem)
 665{
 666	return die_find_child(sp_die, __die_find_inline_cb, &addr, die_mem);
 667}
 668
 669/**
 670 * die_find_inlinefunc - Search an inlined function at given address
 671 * @sp_die: a subprogram DIE which including @addr
 672 * @addr: target address
 673 * @die_mem: a buffer for result DIE
 674 *
 675 * Search an inlined function DIE which includes @addr. Stores the
 676 * DIE to @die_mem and returns it if found. Returns NULL if failed.
 677 * If several inlined functions are expanded recursively, this trace
 678 * it down and returns deepest one.
 679 */
 680Dwarf_Die *die_find_inlinefunc(Dwarf_Die *sp_die, Dwarf_Addr addr,
 681			       Dwarf_Die *die_mem)
 682{
 683	Dwarf_Die tmp_die;
 684
 685	sp_die = die_find_child(sp_die, __die_find_inline_cb, &addr, &tmp_die);
 686	if (!sp_die)
 687		return NULL;
 688
 689	/* Inlined function could be recursive. Trace it until fail */
 690	while (sp_die) {
 691		memcpy(die_mem, sp_die, sizeof(Dwarf_Die));
 692		sp_die = die_find_child(sp_die, __die_find_inline_cb, &addr,
 693					&tmp_die);
 694	}
 695
 696	return die_mem;
 697}
 698
 699struct __instance_walk_param {
 700	void    *addr;
 701	int	(*callback)(Dwarf_Die *, void *);
 702	void    *data;
 703	int	retval;
 704};
 705
 706static int __die_walk_instances_cb(Dwarf_Die *inst, void *data)
 707{
 708	struct __instance_walk_param *iwp = data;
 709	Dwarf_Attribute attr_mem;
 710	Dwarf_Die origin_mem;
 711	Dwarf_Attribute *attr;
 712	Dwarf_Die *origin;
 713	int tmp;
 714
 715	if (!die_is_func_instance(inst))
 716		return DIE_FIND_CB_CONTINUE;
 717
 718	attr = dwarf_attr(inst, DW_AT_abstract_origin, &attr_mem);
 719	if (attr == NULL)
 720		return DIE_FIND_CB_CONTINUE;
 721
 722	origin = dwarf_formref_die(attr, &origin_mem);
 723	if (origin == NULL || origin->addr != iwp->addr)
 724		return DIE_FIND_CB_CONTINUE;
 725
 726	/* Ignore redundant instances */
 727	if (dwarf_tag(inst) == DW_TAG_inlined_subroutine) {
 728		dwarf_decl_line(origin, &tmp);
 729		if (die_get_call_lineno(inst) == tmp) {
 730			tmp = die_get_decl_fileno(origin);
 731			if (die_get_call_fileno(inst) == tmp)
 732				return DIE_FIND_CB_CONTINUE;
 733		}
 734	}
 735
 736	iwp->retval = iwp->callback(inst, iwp->data);
 737
 738	return (iwp->retval) ? DIE_FIND_CB_END : DIE_FIND_CB_CONTINUE;
 739}
 740
 741/**
 742 * die_walk_instances - Walk on instances of given DIE
 743 * @or_die: an abstract original DIE
 744 * @callback: a callback function which is called with instance DIE
 745 * @data: user data
 746 *
 747 * Walk on the instances of give @in_die. @in_die must be an inlined function
 748 * declaration. This returns the return value of @callback if it returns
 749 * non-zero value, or -ENOENT if there is no instance.
 750 */
 751int die_walk_instances(Dwarf_Die *or_die, int (*callback)(Dwarf_Die *, void *),
 752		       void *data)
 753{
 754	Dwarf_Die cu_die;
 755	Dwarf_Die die_mem;
 756	struct __instance_walk_param iwp = {
 757		.addr = or_die->addr,
 758		.callback = callback,
 759		.data = data,
 760		.retval = -ENOENT,
 761	};
 762
 763	if (dwarf_diecu(or_die, &cu_die, NULL, NULL) == NULL)
 764		return -ENOENT;
 765
 766	die_find_child(&cu_die, __die_walk_instances_cb, &iwp, &die_mem);
 767
 768	return iwp.retval;
 769}
 770
 771/* Line walker internal parameters */
 772struct __line_walk_param {
 773	bool recursive;
 774	line_walk_callback_t callback;
 775	void *data;
 776	int retval;
 777};
 778
 779static int __die_walk_funclines_cb(Dwarf_Die *in_die, void *data)
 780{
 781	struct __line_walk_param *lw = data;
 782	Dwarf_Addr addr = 0;
 783	const char *fname;
 784	int lineno;
 785
 786	if (dwarf_tag(in_die) == DW_TAG_inlined_subroutine) {
 787		fname = die_get_call_file(in_die);
 788		lineno = die_get_call_lineno(in_die);
 789		if (fname && lineno > 0 && die_entrypc(in_die, &addr) == 0) {
 790			lw->retval = lw->callback(fname, lineno, addr, lw->data);
 791			if (lw->retval != 0)
 792				return DIE_FIND_CB_END;
 793		}
 794		if (!lw->recursive)
 795			return DIE_FIND_CB_SIBLING;
 796	}
 797
 798	if (addr) {
 799		fname = die_get_decl_file(in_die);
 800		if (fname && dwarf_decl_line(in_die, &lineno) == 0) {
 801			lw->retval = lw->callback(fname, lineno, addr, lw->data);
 802			if (lw->retval != 0)
 803				return DIE_FIND_CB_END;
 804		}
 805	}
 806
 807	/* Continue to search nested inlined function call-sites */
 808	return DIE_FIND_CB_CONTINUE;
 809}
 810
 811/* Walk on lines of blocks included in given DIE */
 812static int __die_walk_funclines(Dwarf_Die *sp_die, bool recursive,
 813				line_walk_callback_t callback, void *data)
 814{
 815	struct __line_walk_param lw = {
 816		.recursive = recursive,
 817		.callback = callback,
 818		.data = data,
 819		.retval = 0,
 820	};
 821	Dwarf_Die die_mem;
 822	Dwarf_Addr addr;
 823	const char *fname;
 824	int lineno;
 825
 826	/* Handle function declaration line */
 827	fname = die_get_decl_file(sp_die);
 828	if (fname && dwarf_decl_line(sp_die, &lineno) == 0 &&
 829	    die_entrypc(sp_die, &addr) == 0) {
 830		lw.retval = callback(fname, lineno, addr, data);
 831		if (lw.retval != 0)
 832			goto done;
 833	}
 834	die_find_child(sp_die, __die_walk_funclines_cb, &lw, &die_mem);
 835done:
 836	return lw.retval;
 837}
 838
 839static int __die_walk_culines_cb(Dwarf_Die *sp_die, void *data)
 840{
 841	struct __line_walk_param *lw = data;
 842
 843	/*
 844	 * Since inlined function can include another inlined function in
 845	 * the same file, we need to walk in it recursively.
 846	 */
 847	lw->retval = __die_walk_funclines(sp_die, true, lw->callback, lw->data);
 848	if (lw->retval != 0)
 849		return DWARF_CB_ABORT;
 850
 851	return DWARF_CB_OK;
 852}
 853
 854/**
 855 * die_walk_lines - Walk on lines inside given DIE
 856 * @rt_die: a root DIE (CU, subprogram or inlined_subroutine)
 857 * @callback: callback routine
 858 * @data: user data
 859 *
 860 * Walk on all lines inside given @rt_die and call @callback on each line.
 861 * If the @rt_die is a function, walk only on the lines inside the function,
 862 * otherwise @rt_die must be a CU DIE.
 863 * Note that this walks not only dwarf line list, but also function entries
 864 * and inline call-site.
 865 */
 866int die_walk_lines(Dwarf_Die *rt_die, line_walk_callback_t callback, void *data)
 867{
 868	Dwarf_Lines *lines;
 869	Dwarf_Line *line;
 870	Dwarf_Addr addr;
 871	const char *fname, *decf = NULL, *inf = NULL;
 872	int lineno, ret = 0;
 873	int decl = 0, inl;
 874	Dwarf_Die die_mem, *cu_die;
 875	size_t nlines, i;
 876	bool flag;
 877
 878	/* Get the CU die */
 879	if (dwarf_tag(rt_die) != DW_TAG_compile_unit) {
 880		cu_die = dwarf_diecu(rt_die, &die_mem, NULL, NULL);
 881		dwarf_decl_line(rt_die, &decl);
 882		decf = die_get_decl_file(rt_die);
 883		if (!decf) {
 884			pr_debug2("Failed to get the declared file name of %s\n",
 885				  dwarf_diename(rt_die));
 886			return -EINVAL;
 887		}
 888	} else
 889		cu_die = rt_die;
 890	if (!cu_die) {
 891		pr_debug2("Failed to get CU from given DIE.\n");
 892		return -EINVAL;
 893	}
 894
 895	/* Get lines list in the CU */
 896	if (dwarf_getsrclines(cu_die, &lines, &nlines) != 0) {
 897		pr_debug2("Failed to get source lines on this CU.\n");
 898		return -ENOENT;
 899	}
 900	pr_debug2("Get %zd lines from this CU\n", nlines);
 901
 902	/* Walk on the lines on lines list */
 903	for (i = 0; i < nlines; i++) {
 904		line = dwarf_onesrcline(lines, i);
 905		if (line == NULL ||
 906		    dwarf_lineno(line, &lineno) != 0 ||
 907		    dwarf_lineaddr(line, &addr) != 0) {
 908			pr_debug2("Failed to get line info. "
 909				  "Possible error in debuginfo.\n");
 910			continue;
 911		}
 912		/* Skip end-of-sequence */
 913		if (dwarf_lineendsequence(line, &flag) != 0 || flag)
 914			continue;
 915		/* Skip Non statement line-info */
 916		if (dwarf_linebeginstatement(line, &flag) != 0 || !flag)
 917			continue;
 918		/* Filter lines based on address */
 919		if (rt_die != cu_die) {
 920			/*
 921			 * Address filtering
 922			 * The line is included in given function, and
 923			 * no inline block includes it.
 924			 */
 925			if (!dwarf_haspc(rt_die, addr))
 926				continue;
 927
 928			if (die_find_inlinefunc(rt_die, addr, &die_mem)) {
 929				/* Call-site check */
 930				inf = die_get_call_file(&die_mem);
 931				if ((inf && !strcmp(inf, decf)) &&
 932				    die_get_call_lineno(&die_mem) == lineno)
 933					goto found;
 934
 935				dwarf_decl_line(&die_mem, &inl);
 936				if (inl != decl ||
 937				    decf != die_get_decl_file(&die_mem))
 938					continue;
 939			}
 940		}
 941found:
 942		/* Get source line */
 943		fname = dwarf_linesrc(line, NULL, NULL);
 944
 945		ret = callback(fname, lineno, addr, data);
 946		if (ret != 0)
 947			return ret;
 948	}
 949
 950	/*
 951	 * Dwarf lines doesn't include function declarations and inlined
 952	 * subroutines. We have to check functions list or given function.
 953	 */
 954	if (rt_die != cu_die)
 955		/*
 956		 * Don't need walk inlined functions recursively, because
 957		 * inner inlined functions don't have the lines of the
 958		 * specified function.
 959		 */
 960		ret = __die_walk_funclines(rt_die, false, callback, data);
 961	else {
 962		struct __line_walk_param param = {
 963			.callback = callback,
 964			.data = data,
 965			.retval = 0,
 966		};
 967		dwarf_getfuncs(cu_die, __die_walk_culines_cb, &param, 0);
 968		ret = param.retval;
 969	}
 970
 971	return ret;
 972}
 973
 974struct __find_variable_param {
 975	const char *name;
 976	Dwarf_Addr addr;
 977};
 978
 979static int __die_find_variable_cb(Dwarf_Die *die_mem, void *data)
 980{
 981	struct __find_variable_param *fvp = data;
 982	Dwarf_Attribute attr;
 983	int tag;
 984
 985	tag = dwarf_tag(die_mem);
 986	if ((tag == DW_TAG_formal_parameter ||
 987	     tag == DW_TAG_variable) &&
 988	    die_compare_name(die_mem, fvp->name) &&
 989	/*
 990	 * Does the DIE have location information or const value
 991	 * or external instance?
 992	 */
 993	    (dwarf_attr(die_mem, DW_AT_external, &attr) ||
 994	     dwarf_attr(die_mem, DW_AT_location, &attr) ||
 995	     dwarf_attr(die_mem, DW_AT_const_value, &attr)))
 996		return DIE_FIND_CB_END;
 997	if (dwarf_haspc(die_mem, fvp->addr))
 998		return DIE_FIND_CB_CONTINUE;
 999	else
1000		return DIE_FIND_CB_SIBLING;
1001}
1002
1003/**
1004 * die_find_variable_at - Find a given name variable at given address
1005 * @sp_die: a function DIE
1006 * @name: variable name
1007 * @addr: address
1008 * @die_mem: a buffer for result DIE
1009 *
1010 * Find a variable DIE called @name at @addr in @sp_die.
1011 */
1012Dwarf_Die *die_find_variable_at(Dwarf_Die *sp_die, const char *name,
1013				Dwarf_Addr addr, Dwarf_Die *die_mem)
1014{
1015	struct __find_variable_param fvp = { .name = name, .addr = addr};
1016
1017	return die_find_child(sp_die, __die_find_variable_cb, (void *)&fvp,
1018			      die_mem);
1019}
1020
1021static int __die_find_member_cb(Dwarf_Die *die_mem, void *data)
1022{
1023	const char *name = data;
1024
1025	if (dwarf_tag(die_mem) == DW_TAG_member) {
1026		if (die_compare_name(die_mem, name))
1027			return DIE_FIND_CB_END;
1028		else if (!dwarf_diename(die_mem)) {	/* Unnamed structure */
1029			Dwarf_Die type_die, tmp_die;
1030			if (die_get_type(die_mem, &type_die) &&
1031			    die_find_member(&type_die, name, &tmp_die))
1032				return DIE_FIND_CB_END;
1033		}
1034	}
1035	return DIE_FIND_CB_SIBLING;
1036}
1037
1038/**
1039 * die_find_member - Find a given name member in a data structure
1040 * @st_die: a data structure type DIE
1041 * @name: member name
1042 * @die_mem: a buffer for result DIE
1043 *
1044 * Find a member DIE called @name in @st_die.
1045 */
1046Dwarf_Die *die_find_member(Dwarf_Die *st_die, const char *name,
1047			   Dwarf_Die *die_mem)
1048{
1049	return die_find_child(st_die, __die_find_member_cb, (void *)name,
1050			      die_mem);
1051}
1052
1053/**
1054 * die_get_typename_from_type - Get the name of given type DIE
1055 * @type_die: a type DIE
1056 * @buf: a strbuf for result type name
1057 *
1058 * Get the name of @type_die and stores it to @buf. Return 0 if succeeded.
1059 * and Return -ENOENT if failed to find type name.
1060 * Note that the result will stores typedef name if possible, and stores
1061 * "*(function_type)" if the type is a function pointer.
1062 */
1063int die_get_typename_from_type(Dwarf_Die *type_die, struct strbuf *buf)
1064{
 
1065	int tag, ret;
1066	const char *tmp = "";
1067
1068	tag = dwarf_tag(type_die);
 
 
 
1069	if (tag == DW_TAG_array_type || tag == DW_TAG_pointer_type)
1070		tmp = "*";
1071	else if (tag == DW_TAG_subroutine_type) {
1072		/* Function pointer */
1073		return strbuf_add(buf, "(function_type)", 15);
1074	} else {
1075		const char *name = dwarf_diename(type_die);
1076
1077		if (tag == DW_TAG_union_type)
1078			tmp = "union ";
1079		else if (tag == DW_TAG_structure_type)
1080			tmp = "struct ";
1081		else if (tag == DW_TAG_enumeration_type)
1082			tmp = "enum ";
1083		else if (name == NULL)
1084			return -ENOENT;
1085		/* Write a base name */
1086		return strbuf_addf(buf, "%s%s", tmp, name ?: "");
1087	}
1088	ret = die_get_typename(type_die, buf);
1089	if (ret < 0) {
1090		/* void pointer has no type attribute */
1091		if (tag == DW_TAG_pointer_type && ret == -ENOENT)
1092			return strbuf_addf(buf, "void*");
1093
1094		return ret;
1095	}
1096	return strbuf_addstr(buf, tmp);
1097}
1098
1099/**
1100 * die_get_typename - Get the name of given variable DIE
1101 * @vr_die: a variable DIE
1102 * @buf: a strbuf for result type name
1103 *
1104 * Get the name of @vr_die and stores it to @buf. Return 0 if succeeded.
1105 * and Return -ENOENT if failed to find type name.
1106 * Note that the result will stores typedef name if possible, and stores
1107 * "*(function_type)" if the type is a function pointer.
1108 */
1109int die_get_typename(Dwarf_Die *vr_die, struct strbuf *buf)
1110{
1111	Dwarf_Die type;
1112
1113	if (__die_get_real_type(vr_die, &type) == NULL)
1114		return -ENOENT;
1115
1116	return die_get_typename_from_type(&type, buf);
1117}
1118
1119/**
1120 * die_get_varname - Get the name and type of given variable DIE
1121 * @vr_die: a variable DIE
1122 * @buf: a strbuf for type and variable name
1123 *
1124 * Get the name and type of @vr_die and stores it in @buf as "type\tname".
1125 */
1126int die_get_varname(Dwarf_Die *vr_die, struct strbuf *buf)
1127{
1128	int ret;
1129
1130	ret = die_get_typename(vr_die, buf);
1131	if (ret < 0) {
1132		pr_debug("Failed to get type, make it unknown.\n");
1133		ret = strbuf_add(buf, "(unknown_type)", 14);
1134	}
1135
1136	return ret < 0 ? ret : strbuf_addf(buf, "\t%s", dwarf_diename(vr_die));
1137}
1138
1139#ifdef HAVE_DWARF_GETLOCATIONS_SUPPORT
1140/**
1141 * die_get_var_innermost_scope - Get innermost scope range of given variable DIE
1142 * @sp_die: a subprogram DIE
1143 * @vr_die: a variable DIE
1144 * @buf: a strbuf for variable byte offset range
1145 *
1146 * Get the innermost scope range of @vr_die and stores it in @buf as
1147 * "@<function_name+[NN-NN,NN-NN]>".
1148 */
1149static int die_get_var_innermost_scope(Dwarf_Die *sp_die, Dwarf_Die *vr_die,
1150				struct strbuf *buf)
1151{
1152	Dwarf_Die *scopes;
1153	int count;
1154	size_t offset = 0;
1155	Dwarf_Addr base;
1156	Dwarf_Addr start, end;
1157	Dwarf_Addr entry;
1158	int ret;
1159	bool first = true;
1160	const char *name;
1161
1162	ret = die_entrypc(sp_die, &entry);
1163	if (ret)
1164		return ret;
1165
1166	name = dwarf_diename(sp_die);
1167	if (!name)
1168		return -ENOENT;
1169
1170	count = dwarf_getscopes_die(vr_die, &scopes);
1171
1172	/* (*SCOPES)[1] is the DIE for the scope containing that scope */
1173	if (count <= 1) {
1174		ret = -EINVAL;
1175		goto out;
1176	}
1177
1178	while ((offset = dwarf_ranges(&scopes[1], offset, &base,
1179					&start, &end)) > 0) {
1180		start -= entry;
1181		end -= entry;
1182
1183		if (first) {
1184			ret = strbuf_addf(buf, "@<%s+[%" PRIu64 "-%" PRIu64,
1185					  name, start, end);
1186			first = false;
1187		} else {
1188			ret = strbuf_addf(buf, ",%" PRIu64 "-%" PRIu64,
1189					  start, end);
1190		}
1191		if (ret < 0)
1192			goto out;
1193	}
1194
1195	if (!first)
1196		ret = strbuf_add(buf, "]>", 2);
1197
1198out:
1199	free(scopes);
1200	return ret;
1201}
1202
1203/**
1204 * die_get_var_range - Get byte offset range of given variable DIE
1205 * @sp_die: a subprogram DIE
1206 * @vr_die: a variable DIE
1207 * @buf: a strbuf for type and variable name and byte offset range
1208 *
1209 * Get the byte offset range of @vr_die and stores it in @buf as
1210 * "@<function_name+[NN-NN,NN-NN]>".
1211 */
1212int die_get_var_range(Dwarf_Die *sp_die, Dwarf_Die *vr_die, struct strbuf *buf)
1213{
1214	int ret = 0;
1215	Dwarf_Addr base;
1216	Dwarf_Addr start, end;
1217	Dwarf_Addr entry;
1218	Dwarf_Op *op;
1219	size_t nops;
1220	size_t offset = 0;
1221	Dwarf_Attribute attr;
1222	bool first = true;
1223	const char *name;
1224
1225	ret = die_entrypc(sp_die, &entry);
1226	if (ret)
1227		return ret;
1228
1229	name = dwarf_diename(sp_die);
1230	if (!name)
1231		return -ENOENT;
1232
1233	if (dwarf_attr(vr_die, DW_AT_location, &attr) == NULL)
1234		return -EINVAL;
1235
1236	while ((offset = dwarf_getlocations(&attr, offset, &base,
1237					&start, &end, &op, &nops)) > 0) {
1238		if (start == 0) {
1239			/* Single Location Descriptions */
1240			ret = die_get_var_innermost_scope(sp_die, vr_die, buf);
1241			goto out;
1242		}
1243
1244		/* Location Lists */
1245		start -= entry;
1246		end -= entry;
1247		if (first) {
1248			ret = strbuf_addf(buf, "@<%s+[%" PRIu64 "-%" PRIu64,
1249					  name, start, end);
1250			first = false;
1251		} else {
1252			ret = strbuf_addf(buf, ",%" PRIu64 "-%" PRIu64,
1253					  start, end);
1254		}
1255		if (ret < 0)
1256			goto out;
1257	}
1258
1259	if (!first)
1260		ret = strbuf_add(buf, "]>", 2);
1261out:
1262	return ret;
1263}
1264
1265/* Interval parameters for __die_find_var_reg_cb() */
1266struct find_var_data {
1267	/* Target instruction address */
1268	Dwarf_Addr pc;
1269	/* Target memory address (for global data) */
1270	Dwarf_Addr addr;
1271	/* Target register */
1272	unsigned reg;
1273	/* Access offset, set for global data */
1274	int offset;
1275};
1276
1277/* Max number of registers DW_OP_regN supports */
1278#define DWARF_OP_DIRECT_REGS  32
1279
1280/* Only checks direct child DIEs in the given scope. */
1281static int __die_find_var_reg_cb(Dwarf_Die *die_mem, void *arg)
1282{
1283	struct find_var_data *data = arg;
1284	int tag = dwarf_tag(die_mem);
1285	ptrdiff_t off = 0;
1286	Dwarf_Attribute attr;
1287	Dwarf_Addr base, start, end;
1288	Dwarf_Op *ops;
1289	size_t nops;
1290
1291	if (tag != DW_TAG_variable && tag != DW_TAG_formal_parameter)
1292		return DIE_FIND_CB_SIBLING;
1293
1294	if (dwarf_attr(die_mem, DW_AT_location, &attr) == NULL)
1295		return DIE_FIND_CB_SIBLING;
1296
1297	while ((off = dwarf_getlocations(&attr, off, &base, &start, &end, &ops, &nops)) > 0) {
1298		/* Assuming the location list is sorted by address */
1299		if (end < data->pc)
1300			continue;
1301		if (start > data->pc)
1302			break;
1303
1304		/* Only match with a simple case */
1305		if (data->reg < DWARF_OP_DIRECT_REGS) {
1306			if (ops->atom == (DW_OP_reg0 + data->reg) && nops == 1)
1307				return DIE_FIND_CB_END;
1308		} else {
1309			if (ops->atom == DW_OP_regx && ops->number == data->reg &&
1310			    nops == 1)
1311				return DIE_FIND_CB_END;
1312		}
1313	}
1314	return DIE_FIND_CB_SIBLING;
1315}
1316
1317/**
1318 * die_find_variable_by_reg - Find a variable saved in a register
1319 * @sc_die: a scope DIE
1320 * @pc: the program address to find
1321 * @reg: the register number to find
1322 * @die_mem: a buffer to save the resulting DIE
1323 *
1324 * Find the variable DIE accessed by the given register.
1325 */
1326Dwarf_Die *die_find_variable_by_reg(Dwarf_Die *sc_die, Dwarf_Addr pc, int reg,
1327				    Dwarf_Die *die_mem)
1328{
1329	struct find_var_data data = {
1330		.pc = pc,
1331		.reg = reg,
1332	};
1333	return die_find_child(sc_die, __die_find_var_reg_cb, &data, die_mem);
1334}
1335
1336/* Only checks direct child DIEs in the given scope */
1337static int __die_find_var_addr_cb(Dwarf_Die *die_mem, void *arg)
1338{
1339	struct find_var_data *data = arg;
1340	int tag = dwarf_tag(die_mem);
1341	ptrdiff_t off = 0;
1342	Dwarf_Attribute attr;
1343	Dwarf_Addr base, start, end;
1344	Dwarf_Word size;
1345	Dwarf_Die type_die;
1346	Dwarf_Op *ops;
1347	size_t nops;
1348
1349	if (tag != DW_TAG_variable)
1350		return DIE_FIND_CB_SIBLING;
1351
1352	if (dwarf_attr(die_mem, DW_AT_location, &attr) == NULL)
1353		return DIE_FIND_CB_SIBLING;
1354
1355	while ((off = dwarf_getlocations(&attr, off, &base, &start, &end, &ops, &nops)) > 0) {
1356		if (ops->atom != DW_OP_addr)
1357			continue;
1358
1359		if (data->addr < ops->number)
1360			continue;
1361
1362		if (data->addr == ops->number) {
1363			/* Update offset relative to the start of the variable */
1364			data->offset = 0;
1365			return DIE_FIND_CB_END;
1366		}
1367
1368		if (die_get_real_type(die_mem, &type_die) == NULL)
1369			continue;
1370
1371		if (dwarf_aggregate_size(&type_die, &size) < 0)
1372			continue;
1373
1374		if (data->addr >= ops->number + size)
1375			continue;
1376
1377		/* Update offset relative to the start of the variable */
1378		data->offset = data->addr - ops->number;
1379		return DIE_FIND_CB_END;
1380	}
1381	return DIE_FIND_CB_SIBLING;
1382}
1383
1384/**
1385 * die_find_variable_by_addr - Find variable located at given address
1386 * @sc_die: a scope DIE
1387 * @pc: the program address to find
1388 * @addr: the data address to find
1389 * @die_mem: a buffer to save the resulting DIE
1390 * @offset: the offset in the resulting type
1391 *
1392 * Find the variable DIE located at the given address (in PC-relative mode).
1393 * This is usually for global variables.
1394 */
1395Dwarf_Die *die_find_variable_by_addr(Dwarf_Die *sc_die, Dwarf_Addr pc,
1396				     Dwarf_Addr addr, Dwarf_Die *die_mem,
1397				     int *offset)
1398{
1399	struct find_var_data data = {
1400		.pc = pc,
1401		.addr = addr,
1402	};
1403	Dwarf_Die *result;
1404
1405	result = die_find_child(sc_die, __die_find_var_addr_cb, &data, die_mem);
1406	if (result)
1407		*offset = data.offset;
1408	return result;
1409}
1410#endif
1411
1412/*
1413 * die_has_loclist - Check if DW_AT_location of @vr_die is a location list
1414 * @vr_die: a variable DIE
1415 */
1416static bool die_has_loclist(Dwarf_Die *vr_die)
1417{
1418	Dwarf_Attribute loc;
1419	int tag = dwarf_tag(vr_die);
1420
1421	if (tag != DW_TAG_formal_parameter &&
1422	    tag != DW_TAG_variable)
1423		return false;
1424
1425	return (dwarf_attr_integrate(vr_die, DW_AT_location, &loc) &&
1426		dwarf_whatform(&loc) == DW_FORM_sec_offset);
1427}
1428
1429/*
1430 * die_is_optimized_target - Check if target program is compiled with
1431 * optimization
1432 * @cu_die: a CU DIE
1433 *
1434 * For any object in given CU whose DW_AT_location is a location list,
1435 * target program is compiled with optimization. This is applicable to
1436 * clang as well.
1437 */
1438bool die_is_optimized_target(Dwarf_Die *cu_die)
1439{
1440	Dwarf_Die tmp_die;
1441
1442	if (die_has_loclist(cu_die))
1443		return true;
1444
1445	if (!dwarf_child(cu_die, &tmp_die) &&
1446	    die_is_optimized_target(&tmp_die))
1447		return true;
1448
1449	if (!dwarf_siblingof(cu_die, &tmp_die) &&
1450	    die_is_optimized_target(&tmp_die))
1451		return true;
1452
1453	return false;
1454}
1455
1456/*
1457 * die_search_idx - Search index of given line address
1458 * @lines: Line records of single CU
1459 * @nr_lines: Number of @lines
1460 * @addr: address we are looking for
1461 * @idx: index to be set by this function (return value)
1462 *
1463 * Search for @addr by looping over every lines of CU. If address
1464 * matches, set index of that line in @idx. Note that single source
1465 * line can have multiple line records. i.e. single source line can
1466 * have multiple index.
1467 */
1468static bool die_search_idx(Dwarf_Lines *lines, unsigned long nr_lines,
1469			   Dwarf_Addr addr, unsigned long *idx)
1470{
1471	unsigned long i;
1472	Dwarf_Addr tmp;
1473
1474	for (i = 0; i < nr_lines; i++) {
1475		if (dwarf_lineaddr(dwarf_onesrcline(lines, i), &tmp))
1476			return false;
1477
1478		if (tmp == addr) {
1479			*idx = i;
1480			return true;
1481		}
1482	}
1483	return false;
1484}
1485
1486/*
1487 * die_get_postprologue_addr - Search next address after function prologue
1488 * @entrypc_idx: entrypc index
1489 * @lines: Line records of single CU
1490 * @nr_lines: Number of @lines
1491 * @hignpc: high PC address of function
1492 * @postprologue_addr: Next address after function prologue (return value)
1493 *
1494 * Look for prologue-end marker. If there is no explicit marker, return
1495 * address of next line record or next source line.
1496 */
1497static bool die_get_postprologue_addr(unsigned long entrypc_idx,
1498				      Dwarf_Lines *lines,
1499				      unsigned long nr_lines,
1500				      Dwarf_Addr highpc,
1501				      Dwarf_Addr *postprologue_addr)
1502{
1503	unsigned long i;
1504	int entrypc_lno, lno;
1505	Dwarf_Line *line;
1506	Dwarf_Addr addr;
1507	bool p_end;
1508
1509	/* entrypc_lno is actual source line number */
1510	line = dwarf_onesrcline(lines, entrypc_idx);
1511	if (dwarf_lineno(line, &entrypc_lno))
1512		return false;
1513
1514	for (i = entrypc_idx; i < nr_lines; i++) {
1515		line = dwarf_onesrcline(lines, i);
1516
1517		if (dwarf_lineaddr(line, &addr) ||
1518		    dwarf_lineno(line, &lno)    ||
1519		    dwarf_lineprologueend(line, &p_end))
1520			return false;
1521
1522		/* highpc is exclusive. [entrypc,highpc) */
1523		if (addr >= highpc)
1524			break;
1525
1526		/* clang supports prologue-end marker */
1527		if (p_end)
1528			break;
1529
1530		/* Actual next line in source */
1531		if (lno != entrypc_lno)
1532			break;
1533
1534		/*
1535		 * Single source line can have multiple line records.
1536		 * For Example,
1537		 *     void foo() { printf("hello\n"); }
1538		 * contains two line records. One points to declaration and
1539		 * other points to printf() line. Variable 'lno' won't get
1540		 * incremented in this case but 'i' will.
1541		 */
1542		if (i != entrypc_idx)
1543			break;
1544	}
1545
1546	dwarf_lineaddr(line, postprologue_addr);
1547	if (*postprologue_addr >= highpc)
1548		dwarf_lineaddr(dwarf_onesrcline(lines, i - 1),
1549			       postprologue_addr);
1550
1551	return true;
1552}
1553
1554/*
1555 * die_skip_prologue - Use next address after prologue as probe location
1556 * @sp_die: a subprogram DIE
1557 * @cu_die: a CU DIE
1558 * @entrypc: entrypc of the function
1559 *
1560 * Function prologue prepares stack and registers before executing function
1561 * logic. When target program is compiled without optimization, function
1562 * parameter information is only valid after prologue. When we probe entrypc
1563 * of the function, and try to record function parameter, it contains
1564 * garbage value.
1565 */
1566void die_skip_prologue(Dwarf_Die *sp_die, Dwarf_Die *cu_die,
1567		       Dwarf_Addr *entrypc)
1568{
1569	size_t nr_lines = 0;
1570	unsigned long entrypc_idx = 0;
1571	Dwarf_Lines *lines = NULL;
1572	Dwarf_Addr postprologue_addr;
1573	Dwarf_Addr highpc;
1574
1575	if (dwarf_highpc(sp_die, &highpc))
1576		return;
1577
1578	if (dwarf_getsrclines(cu_die, &lines, &nr_lines))
1579		return;
1580
1581	if (!die_search_idx(lines, nr_lines, *entrypc, &entrypc_idx))
1582		return;
1583
1584	if (!die_get_postprologue_addr(entrypc_idx, lines, nr_lines,
1585				       highpc, &postprologue_addr))
1586		return;
1587
1588	*entrypc = postprologue_addr;
1589}
1590
1591/* Internal parameters for __die_find_scope_cb() */
1592struct find_scope_data {
1593	/* Target instruction address */
1594	Dwarf_Addr pc;
1595	/* Number of scopes found [output] */
1596	int nr;
1597	/* Array of scopes found, 0 for the outermost one. [output] */
1598	Dwarf_Die *scopes;
1599};
1600
1601static int __die_find_scope_cb(Dwarf_Die *die_mem, void *arg)
1602{
1603	struct find_scope_data *data = arg;
1604
1605	if (dwarf_haspc(die_mem, data->pc)) {
1606		Dwarf_Die *tmp;
1607
1608		tmp = realloc(data->scopes, (data->nr + 1) * sizeof(*tmp));
1609		if (tmp == NULL)
1610			return DIE_FIND_CB_END;
1611
1612		memcpy(tmp + data->nr, die_mem, sizeof(*die_mem));
1613		data->scopes = tmp;
1614		data->nr++;
1615		return DIE_FIND_CB_CHILD;
1616	}
1617	return DIE_FIND_CB_SIBLING;
1618}
1619
1620/**
1621 * die_get_scopes - Return a list of scopes including the address
1622 * @cu_die: a compile unit DIE
1623 * @pc: the address to find
1624 * @scopes: the array of DIEs for scopes (result)
1625 *
1626 * This function does the same as the dwarf_getscopes() but doesn't follow
1627 * the origins of inlined functions.  It returns the number of scopes saved
1628 * in the @scopes argument.  The outer scope will be saved first (index 0) and
1629 * the last one is the innermost scope at the @pc.
1630 */
1631int die_get_scopes(Dwarf_Die *cu_die, Dwarf_Addr pc, Dwarf_Die **scopes)
1632{
1633	struct find_scope_data data = {
1634		.pc = pc,
1635	};
1636	Dwarf_Die die_mem;
1637
1638	die_find_child(cu_die, __die_find_scope_cb, &data, &die_mem);
1639
1640	*scopes = data.scopes;
1641	return data.nr;
1642}