1 /* Frame unwinder for frames with DWARF Call Frame Information. 2 3 Copyright (C) 2003-2005, 2007-2012 Free Software Foundation, Inc. 4 5 Contributed by Mark Kettenis. 6 7 This file is part of GDB. 8 9 This program is free software; you can redistribute it and/or modify 10 it under the terms of the GNU General Public License as published by 11 the Free Software Foundation; either version 3 of the License, or 12 (at your option) any later version. 13 14 This program is distributed in the hope that it will be useful, 15 but WITHOUT ANY WARRANTY; without even the implied warranty of 16 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 17 GNU General Public License for more details. 18 19 You should have received a copy of the GNU General Public License 20 along with this program. If not, see <http://www.gnu.org/licenses/>. */ 21 22 #include "defs.h" 23 #include "dwarf2expr.h" 24 #include "dwarf2.h" 25 #include "frame.h" 26 #include "frame-base.h" 27 #include "frame-unwind.h" 28 #include "gdbcore.h" 29 #include "gdbtypes.h" 30 #include "symtab.h" 31 #include "objfiles.h" 32 #include "regcache.h" 33 #include "value.h" 34 35 #include "gdb_assert.h" 36 #include "gdb_string.h" 37 38 #include "complaints.h" 39 #include "dwarf2-frame.h" 40 #include "ax.h" 41 #include "dwarf2loc.h" 42 #include "exceptions.h" 43 #include "dwarf2-frame-tailcall.h" 44 45 struct comp_unit; 46 47 /* Call Frame Information (CFI). */ 48 49 /* Common Information Entry (CIE). */ 50 51 struct dwarf2_cie 52 { 53 /* Computation Unit for this CIE. */ 54 struct comp_unit *unit; 55 56 /* Offset into the .debug_frame section where this CIE was found. 57 Used to identify this CIE. */ 58 ULONGEST cie_pointer; 59 60 /* Constant that is factored out of all advance location 61 instructions. */ 62 ULONGEST code_alignment_factor; 63 64 /* Constants that is factored out of all offset instructions. */ 65 LONGEST data_alignment_factor; 66 67 /* Return address column. */ 68 ULONGEST return_address_register; 69 70 /* Instruction sequence to initialize a register set. */ 71 gdb_byte *initial_instructions; 72 gdb_byte *end; 73 74 /* Saved augmentation, in case it's needed later. */ 75 char *augmentation; 76 77 /* Encoding of addresses. */ 78 gdb_byte encoding; 79 80 /* Target address size in bytes. */ 81 int addr_size; 82 83 /* Target pointer size in bytes. */ 84 int ptr_size; 85 86 /* True if a 'z' augmentation existed. */ 87 unsigned char saw_z_augmentation; 88 89 /* True if an 'S' augmentation existed. */ 90 unsigned char signal_frame; 91 92 /* The version recorded in the CIE. */ 93 unsigned char version; 94 95 /* The segment size. */ 96 unsigned char segment_size; 97 }; 98 99 struct dwarf2_cie_table 100 { 101 int num_entries; 102 struct dwarf2_cie **entries; 103 }; 104 105 /* Frame Description Entry (FDE). */ 106 107 struct dwarf2_fde 108 { 109 /* CIE for this FDE. */ 110 struct dwarf2_cie *cie; 111 112 /* First location associated with this FDE. */ 113 CORE_ADDR initial_location; 114 115 /* Number of bytes of program instructions described by this FDE. */ 116 CORE_ADDR address_range; 117 118 /* Instruction sequence. */ 119 gdb_byte *instructions; 120 gdb_byte *end; 121 122 /* True if this FDE is read from a .eh_frame instead of a .debug_frame 123 section. */ 124 unsigned char eh_frame_p; 125 }; 126 127 struct dwarf2_fde_table 128 { 129 int num_entries; 130 struct dwarf2_fde **entries; 131 }; 132 133 /* A minimal decoding of DWARF2 compilation units. We only decode 134 what's needed to get to the call frame information. */ 135 136 struct comp_unit 137 { 138 /* Keep the bfd convenient. */ 139 bfd *abfd; 140 141 struct objfile *objfile; 142 143 /* Pointer to the .debug_frame section loaded into memory. */ 144 gdb_byte *dwarf_frame_buffer; 145 146 /* Length of the loaded .debug_frame section. */ 147 bfd_size_type dwarf_frame_size; 148 149 /* Pointer to the .debug_frame section. */ 150 asection *dwarf_frame_section; 151 152 /* Base for DW_EH_PE_datarel encodings. */ 153 bfd_vma dbase; 154 155 /* Base for DW_EH_PE_textrel encodings. */ 156 bfd_vma tbase; 157 }; 158 159 static struct dwarf2_fde *dwarf2_frame_find_fde (CORE_ADDR *pc, 160 CORE_ADDR *out_offset); 161 162 static int dwarf2_frame_adjust_regnum (struct gdbarch *gdbarch, int regnum, 163 int eh_frame_p); 164 165 static CORE_ADDR read_encoded_value (struct comp_unit *unit, gdb_byte encoding, 166 int ptr_len, const gdb_byte *buf, 167 unsigned int *bytes_read_ptr, 168 CORE_ADDR func_base); 169 170 171 /* Structure describing a frame state. */ 172 173 struct dwarf2_frame_state 174 { 175 /* Each register save state can be described in terms of a CFA slot, 176 another register, or a location expression. */ 177 struct dwarf2_frame_state_reg_info 178 { 179 struct dwarf2_frame_state_reg *reg; 180 int num_regs; 181 182 LONGEST cfa_offset; 183 ULONGEST cfa_reg; 184 enum { 185 CFA_UNSET, 186 CFA_REG_OFFSET, 187 CFA_EXP 188 } cfa_how; 189 const gdb_byte *cfa_exp; 190 191 /* Used to implement DW_CFA_remember_state. */ 192 struct dwarf2_frame_state_reg_info *prev; 193 } regs; 194 195 /* The PC described by the current frame state. */ 196 CORE_ADDR pc; 197 198 /* Initial register set from the CIE. 199 Used to implement DW_CFA_restore. */ 200 struct dwarf2_frame_state_reg_info initial; 201 202 /* The information we care about from the CIE. */ 203 LONGEST data_align; 204 ULONGEST code_align; 205 ULONGEST retaddr_column; 206 207 /* Flags for known producer quirks. */ 208 209 /* The ARM compilers, in DWARF2 mode, assume that DW_CFA_def_cfa 210 and DW_CFA_def_cfa_offset takes a factored offset. */ 211 int armcc_cfa_offsets_sf; 212 213 /* The ARM compilers, in DWARF2 or DWARF3 mode, may assume that 214 the CFA is defined as REG - OFFSET rather than REG + OFFSET. */ 215 int armcc_cfa_offsets_reversed; 216 }; 217 218 /* Store the length the expression for the CFA in the `cfa_reg' field, 219 which is unused in that case. */ 220 #define cfa_exp_len cfa_reg 221 222 /* Assert that the register set RS is large enough to store gdbarch_num_regs 223 columns. If necessary, enlarge the register set. */ 224 225 static void 226 dwarf2_frame_state_alloc_regs (struct dwarf2_frame_state_reg_info *rs, 227 int num_regs) 228 { 229 size_t size = sizeof (struct dwarf2_frame_state_reg); 230 231 if (num_regs <= rs->num_regs) 232 return; 233 234 rs->reg = (struct dwarf2_frame_state_reg *) 235 xrealloc (rs->reg, num_regs * size); 236 237 /* Initialize newly allocated registers. */ 238 memset (rs->reg + rs->num_regs, 0, (num_regs - rs->num_regs) * size); 239 rs->num_regs = num_regs; 240 } 241 242 /* Copy the register columns in register set RS into newly allocated 243 memory and return a pointer to this newly created copy. */ 244 245 static struct dwarf2_frame_state_reg * 246 dwarf2_frame_state_copy_regs (struct dwarf2_frame_state_reg_info *rs) 247 { 248 size_t size = rs->num_regs * sizeof (struct dwarf2_frame_state_reg); 249 struct dwarf2_frame_state_reg *reg; 250 251 reg = (struct dwarf2_frame_state_reg *) xmalloc (size); 252 memcpy (reg, rs->reg, size); 253 254 return reg; 255 } 256 257 /* Release the memory allocated to register set RS. */ 258 259 static void 260 dwarf2_frame_state_free_regs (struct dwarf2_frame_state_reg_info *rs) 261 { 262 if (rs) 263 { 264 dwarf2_frame_state_free_regs (rs->prev); 265 266 xfree (rs->reg); 267 xfree (rs); 268 } 269 } 270 271 /* Release the memory allocated to the frame state FS. */ 272 273 static void 274 dwarf2_frame_state_free (void *p) 275 { 276 struct dwarf2_frame_state *fs = p; 277 278 dwarf2_frame_state_free_regs (fs->initial.prev); 279 dwarf2_frame_state_free_regs (fs->regs.prev); 280 xfree (fs->initial.reg); 281 xfree (fs->regs.reg); 282 xfree (fs); 283 } 284 285 286 /* Helper functions for execute_stack_op. */ 287 288 static CORE_ADDR 289 read_reg (void *baton, int reg) 290 { 291 struct frame_info *this_frame = (struct frame_info *) baton; 292 struct gdbarch *gdbarch = get_frame_arch (this_frame); 293 int regnum; 294 gdb_byte *buf; 295 296 regnum = gdbarch_dwarf2_reg_to_regnum (gdbarch, reg); 297 298 buf = alloca (register_size (gdbarch, regnum)); 299 get_frame_register (this_frame, regnum, buf); 300 301 /* Convert the register to an integer. This returns a LONGEST 302 rather than a CORE_ADDR, but unpack_pointer does the same thing 303 under the covers, and this makes more sense for non-pointer 304 registers. Maybe read_reg and the associated interfaces should 305 deal with "struct value" instead of CORE_ADDR. */ 306 return unpack_long (register_type (gdbarch, regnum), buf); 307 } 308 309 static void 310 read_mem (void *baton, gdb_byte *buf, CORE_ADDR addr, size_t len) 311 { 312 read_memory (addr, buf, len); 313 } 314 315 /* Execute the required actions for both the DW_CFA_restore and 316 DW_CFA_restore_extended instructions. */ 317 static void 318 dwarf2_restore_rule (struct gdbarch *gdbarch, ULONGEST reg_num, 319 struct dwarf2_frame_state *fs, int eh_frame_p) 320 { 321 ULONGEST reg; 322 323 gdb_assert (fs->initial.reg); 324 reg = dwarf2_frame_adjust_regnum (gdbarch, reg_num, eh_frame_p); 325 dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1); 326 327 /* Check if this register was explicitly initialized in the 328 CIE initial instructions. If not, default the rule to 329 UNSPECIFIED. */ 330 if (reg < fs->initial.num_regs) 331 fs->regs.reg[reg] = fs->initial.reg[reg]; 332 else 333 fs->regs.reg[reg].how = DWARF2_FRAME_REG_UNSPECIFIED; 334 335 if (fs->regs.reg[reg].how == DWARF2_FRAME_REG_UNSPECIFIED) 336 complaint (&symfile_complaints, _("\ 337 incomplete CFI data; DW_CFA_restore unspecified\n\ 338 register %s (#%d) at %s"), 339 gdbarch_register_name 340 (gdbarch, gdbarch_dwarf2_reg_to_regnum (gdbarch, reg)), 341 gdbarch_dwarf2_reg_to_regnum (gdbarch, reg), 342 paddress (gdbarch, fs->pc)); 343 } 344 345 /* Virtual method table for execute_stack_op below. */ 346 347 static const struct dwarf_expr_context_funcs dwarf2_frame_ctx_funcs = 348 { 349 read_reg, 350 read_mem, 351 ctx_no_get_frame_base, 352 ctx_no_get_frame_cfa, 353 ctx_no_get_frame_pc, 354 ctx_no_get_tls_address, 355 ctx_no_dwarf_call, 356 ctx_no_get_base_type, 357 ctx_no_push_dwarf_reg_entry_value 358 }; 359 360 static CORE_ADDR 361 execute_stack_op (const gdb_byte *exp, ULONGEST len, int addr_size, 362 CORE_ADDR offset, struct frame_info *this_frame, 363 CORE_ADDR initial, int initial_in_stack_memory) 364 { 365 struct dwarf_expr_context *ctx; 366 CORE_ADDR result; 367 struct cleanup *old_chain; 368 369 ctx = new_dwarf_expr_context (); 370 old_chain = make_cleanup_free_dwarf_expr_context (ctx); 371 make_cleanup_value_free_to_mark (value_mark ()); 372 373 ctx->gdbarch = get_frame_arch (this_frame); 374 ctx->addr_size = addr_size; 375 ctx->ref_addr_size = -1; 376 ctx->offset = offset; 377 ctx->baton = this_frame; 378 ctx->funcs = &dwarf2_frame_ctx_funcs; 379 380 dwarf_expr_push_address (ctx, initial, initial_in_stack_memory); 381 dwarf_expr_eval (ctx, exp, len); 382 383 if (ctx->location == DWARF_VALUE_MEMORY) 384 result = dwarf_expr_fetch_address (ctx, 0); 385 else if (ctx->location == DWARF_VALUE_REGISTER) 386 result = read_reg (this_frame, value_as_long (dwarf_expr_fetch (ctx, 0))); 387 else 388 { 389 /* This is actually invalid DWARF, but if we ever do run across 390 it somehow, we might as well support it. So, instead, report 391 it as unimplemented. */ 392 error (_("\ 393 Not implemented: computing unwound register using explicit value operator")); 394 } 395 396 do_cleanups (old_chain); 397 398 return result; 399 } 400 401 402 /* Execute FDE program from INSN_PTR possibly up to INSN_END or up to inferior 403 PC. Modify FS state accordingly. Return current INSN_PTR where the 404 execution has stopped, one can resume it on the next call. */ 405 406 static const gdb_byte * 407 execute_cfa_program (struct dwarf2_fde *fde, const gdb_byte *insn_ptr, 408 const gdb_byte *insn_end, struct gdbarch *gdbarch, 409 CORE_ADDR pc, struct dwarf2_frame_state *fs) 410 { 411 int eh_frame_p = fde->eh_frame_p; 412 int bytes_read; 413 enum bfd_endian byte_order = gdbarch_byte_order (gdbarch); 414 415 while (insn_ptr < insn_end && fs->pc <= pc) 416 { 417 gdb_byte insn = *insn_ptr++; 418 ULONGEST utmp, reg; 419 LONGEST offset; 420 421 if ((insn & 0xc0) == DW_CFA_advance_loc) 422 fs->pc += (insn & 0x3f) * fs->code_align; 423 else if ((insn & 0xc0) == DW_CFA_offset) 424 { 425 reg = insn & 0x3f; 426 reg = dwarf2_frame_adjust_regnum (gdbarch, reg, eh_frame_p); 427 insn_ptr = read_uleb128 (insn_ptr, insn_end, &utmp); 428 offset = utmp * fs->data_align; 429 dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1); 430 fs->regs.reg[reg].how = DWARF2_FRAME_REG_SAVED_OFFSET; 431 fs->regs.reg[reg].loc.offset = offset; 432 } 433 else if ((insn & 0xc0) == DW_CFA_restore) 434 { 435 reg = insn & 0x3f; 436 dwarf2_restore_rule (gdbarch, reg, fs, eh_frame_p); 437 } 438 else 439 { 440 switch (insn) 441 { 442 case DW_CFA_set_loc: 443 fs->pc = read_encoded_value (fde->cie->unit, fde->cie->encoding, 444 fde->cie->ptr_size, insn_ptr, 445 &bytes_read, fde->initial_location); 446 /* Apply the objfile offset for relocatable objects. */ 447 fs->pc += ANOFFSET (fde->cie->unit->objfile->section_offsets, 448 SECT_OFF_TEXT (fde->cie->unit->objfile)); 449 insn_ptr += bytes_read; 450 break; 451 452 case DW_CFA_advance_loc1: 453 utmp = extract_unsigned_integer (insn_ptr, 1, byte_order); 454 fs->pc += utmp * fs->code_align; 455 insn_ptr++; 456 break; 457 case DW_CFA_advance_loc2: 458 utmp = extract_unsigned_integer (insn_ptr, 2, byte_order); 459 fs->pc += utmp * fs->code_align; 460 insn_ptr += 2; 461 break; 462 case DW_CFA_advance_loc4: 463 utmp = extract_unsigned_integer (insn_ptr, 4, byte_order); 464 fs->pc += utmp * fs->code_align; 465 insn_ptr += 4; 466 break; 467 468 case DW_CFA_offset_extended: 469 insn_ptr = read_uleb128 (insn_ptr, insn_end, ®); 470 reg = dwarf2_frame_adjust_regnum (gdbarch, reg, eh_frame_p); 471 insn_ptr = read_uleb128 (insn_ptr, insn_end, &utmp); 472 offset = utmp * fs->data_align; 473 dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1); 474 fs->regs.reg[reg].how = DWARF2_FRAME_REG_SAVED_OFFSET; 475 fs->regs.reg[reg].loc.offset = offset; 476 break; 477 478 case DW_CFA_restore_extended: 479 insn_ptr = read_uleb128 (insn_ptr, insn_end, ®); 480 dwarf2_restore_rule (gdbarch, reg, fs, eh_frame_p); 481 break; 482 483 case DW_CFA_undefined: 484 insn_ptr = read_uleb128 (insn_ptr, insn_end, ®); 485 reg = dwarf2_frame_adjust_regnum (gdbarch, reg, eh_frame_p); 486 dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1); 487 fs->regs.reg[reg].how = DWARF2_FRAME_REG_UNDEFINED; 488 break; 489 490 case DW_CFA_same_value: 491 insn_ptr = read_uleb128 (insn_ptr, insn_end, ®); 492 reg = dwarf2_frame_adjust_regnum (gdbarch, reg, eh_frame_p); 493 dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1); 494 fs->regs.reg[reg].how = DWARF2_FRAME_REG_SAME_VALUE; 495 break; 496 497 case DW_CFA_register: 498 insn_ptr = read_uleb128 (insn_ptr, insn_end, ®); 499 reg = dwarf2_frame_adjust_regnum (gdbarch, reg, eh_frame_p); 500 insn_ptr = read_uleb128 (insn_ptr, insn_end, &utmp); 501 utmp = dwarf2_frame_adjust_regnum (gdbarch, utmp, eh_frame_p); 502 dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1); 503 fs->regs.reg[reg].how = DWARF2_FRAME_REG_SAVED_REG; 504 fs->regs.reg[reg].loc.reg = utmp; 505 break; 506 507 case DW_CFA_remember_state: 508 { 509 struct dwarf2_frame_state_reg_info *new_rs; 510 511 new_rs = XMALLOC (struct dwarf2_frame_state_reg_info); 512 *new_rs = fs->regs; 513 fs->regs.reg = dwarf2_frame_state_copy_regs (&fs->regs); 514 fs->regs.prev = new_rs; 515 } 516 break; 517 518 case DW_CFA_restore_state: 519 { 520 struct dwarf2_frame_state_reg_info *old_rs = fs->regs.prev; 521 522 if (old_rs == NULL) 523 { 524 complaint (&symfile_complaints, _("\ 525 bad CFI data; mismatched DW_CFA_restore_state at %s"), 526 paddress (gdbarch, fs->pc)); 527 } 528 else 529 { 530 xfree (fs->regs.reg); 531 fs->regs = *old_rs; 532 xfree (old_rs); 533 } 534 } 535 break; 536 537 case DW_CFA_def_cfa: 538 insn_ptr = read_uleb128 (insn_ptr, insn_end, &fs->regs.cfa_reg); 539 insn_ptr = read_uleb128 (insn_ptr, insn_end, &utmp); 540 541 if (fs->armcc_cfa_offsets_sf) 542 utmp *= fs->data_align; 543 544 fs->regs.cfa_offset = utmp; 545 fs->regs.cfa_how = CFA_REG_OFFSET; 546 break; 547 548 case DW_CFA_def_cfa_register: 549 insn_ptr = read_uleb128 (insn_ptr, insn_end, &fs->regs.cfa_reg); 550 fs->regs.cfa_reg = dwarf2_frame_adjust_regnum (gdbarch, 551 fs->regs.cfa_reg, 552 eh_frame_p); 553 fs->regs.cfa_how = CFA_REG_OFFSET; 554 break; 555 556 case DW_CFA_def_cfa_offset: 557 insn_ptr = read_uleb128 (insn_ptr, insn_end, &utmp); 558 559 if (fs->armcc_cfa_offsets_sf) 560 utmp *= fs->data_align; 561 562 fs->regs.cfa_offset = utmp; 563 /* cfa_how deliberately not set. */ 564 break; 565 566 case DW_CFA_nop: 567 break; 568 569 case DW_CFA_def_cfa_expression: 570 insn_ptr = read_uleb128 (insn_ptr, insn_end, 571 &fs->regs.cfa_exp_len); 572 fs->regs.cfa_exp = insn_ptr; 573 fs->regs.cfa_how = CFA_EXP; 574 insn_ptr += fs->regs.cfa_exp_len; 575 break; 576 577 case DW_CFA_expression: 578 insn_ptr = read_uleb128 (insn_ptr, insn_end, ®); 579 reg = dwarf2_frame_adjust_regnum (gdbarch, reg, eh_frame_p); 580 dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1); 581 insn_ptr = read_uleb128 (insn_ptr, insn_end, &utmp); 582 fs->regs.reg[reg].loc.exp = insn_ptr; 583 fs->regs.reg[reg].exp_len = utmp; 584 fs->regs.reg[reg].how = DWARF2_FRAME_REG_SAVED_EXP; 585 insn_ptr += utmp; 586 break; 587 588 case DW_CFA_offset_extended_sf: 589 insn_ptr = read_uleb128 (insn_ptr, insn_end, ®); 590 reg = dwarf2_frame_adjust_regnum (gdbarch, reg, eh_frame_p); 591 insn_ptr = read_sleb128 (insn_ptr, insn_end, &offset); 592 offset *= fs->data_align; 593 dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1); 594 fs->regs.reg[reg].how = DWARF2_FRAME_REG_SAVED_OFFSET; 595 fs->regs.reg[reg].loc.offset = offset; 596 break; 597 598 case DW_CFA_val_offset: 599 insn_ptr = read_uleb128 (insn_ptr, insn_end, ®); 600 dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1); 601 insn_ptr = read_uleb128 (insn_ptr, insn_end, &utmp); 602 offset = utmp * fs->data_align; 603 fs->regs.reg[reg].how = DWARF2_FRAME_REG_SAVED_VAL_OFFSET; 604 fs->regs.reg[reg].loc.offset = offset; 605 break; 606 607 case DW_CFA_val_offset_sf: 608 insn_ptr = read_uleb128 (insn_ptr, insn_end, ®); 609 dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1); 610 insn_ptr = read_sleb128 (insn_ptr, insn_end, &offset); 611 offset *= fs->data_align; 612 fs->regs.reg[reg].how = DWARF2_FRAME_REG_SAVED_VAL_OFFSET; 613 fs->regs.reg[reg].loc.offset = offset; 614 break; 615 616 case DW_CFA_val_expression: 617 insn_ptr = read_uleb128 (insn_ptr, insn_end, ®); 618 dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1); 619 insn_ptr = read_uleb128 (insn_ptr, insn_end, &utmp); 620 fs->regs.reg[reg].loc.exp = insn_ptr; 621 fs->regs.reg[reg].exp_len = utmp; 622 fs->regs.reg[reg].how = DWARF2_FRAME_REG_SAVED_VAL_EXP; 623 insn_ptr += utmp; 624 break; 625 626 case DW_CFA_def_cfa_sf: 627 insn_ptr = read_uleb128 (insn_ptr, insn_end, &fs->regs.cfa_reg); 628 fs->regs.cfa_reg = dwarf2_frame_adjust_regnum (gdbarch, 629 fs->regs.cfa_reg, 630 eh_frame_p); 631 insn_ptr = read_sleb128 (insn_ptr, insn_end, &offset); 632 fs->regs.cfa_offset = offset * fs->data_align; 633 fs->regs.cfa_how = CFA_REG_OFFSET; 634 break; 635 636 case DW_CFA_def_cfa_offset_sf: 637 insn_ptr = read_sleb128 (insn_ptr, insn_end, &offset); 638 fs->regs.cfa_offset = offset * fs->data_align; 639 /* cfa_how deliberately not set. */ 640 break; 641 642 case DW_CFA_GNU_window_save: 643 /* This is SPARC-specific code, and contains hard-coded 644 constants for the register numbering scheme used by 645 GCC. Rather than having a architecture-specific 646 operation that's only ever used by a single 647 architecture, we provide the implementation here. 648 Incidentally that's what GCC does too in its 649 unwinder. */ 650 { 651 int size = register_size (gdbarch, 0); 652 653 dwarf2_frame_state_alloc_regs (&fs->regs, 32); 654 for (reg = 8; reg < 16; reg++) 655 { 656 fs->regs.reg[reg].how = DWARF2_FRAME_REG_SAVED_REG; 657 fs->regs.reg[reg].loc.reg = reg + 16; 658 } 659 for (reg = 16; reg < 32; reg++) 660 { 661 fs->regs.reg[reg].how = DWARF2_FRAME_REG_SAVED_OFFSET; 662 fs->regs.reg[reg].loc.offset = (reg - 16) * size; 663 } 664 } 665 break; 666 667 case DW_CFA_GNU_args_size: 668 /* Ignored. */ 669 insn_ptr = read_uleb128 (insn_ptr, insn_end, &utmp); 670 break; 671 672 case DW_CFA_GNU_negative_offset_extended: 673 insn_ptr = read_uleb128 (insn_ptr, insn_end, ®); 674 reg = dwarf2_frame_adjust_regnum (gdbarch, reg, eh_frame_p); 675 insn_ptr = read_uleb128 (insn_ptr, insn_end, &offset); 676 offset *= fs->data_align; 677 dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1); 678 fs->regs.reg[reg].how = DWARF2_FRAME_REG_SAVED_OFFSET; 679 fs->regs.reg[reg].loc.offset = -offset; 680 break; 681 682 default: 683 internal_error (__FILE__, __LINE__, 684 _("Unknown CFI encountered.")); 685 } 686 } 687 } 688 689 if (fs->initial.reg == NULL) 690 { 691 /* Don't allow remember/restore between CIE and FDE programs. */ 692 dwarf2_frame_state_free_regs (fs->regs.prev); 693 fs->regs.prev = NULL; 694 } 695 696 return insn_ptr; 697 } 698 699 700 /* Architecture-specific operations. */ 701 702 /* Per-architecture data key. */ 703 static struct gdbarch_data *dwarf2_frame_data; 704 705 struct dwarf2_frame_ops 706 { 707 /* Pre-initialize the register state REG for register REGNUM. */ 708 void (*init_reg) (struct gdbarch *, int, struct dwarf2_frame_state_reg *, 709 struct frame_info *); 710 711 /* Check whether the THIS_FRAME is a signal trampoline. */ 712 int (*signal_frame_p) (struct gdbarch *, struct frame_info *); 713 714 /* Convert .eh_frame register number to DWARF register number, or 715 adjust .debug_frame register number. */ 716 int (*adjust_regnum) (struct gdbarch *, int, int); 717 }; 718 719 /* Default architecture-specific register state initialization 720 function. */ 721 722 static void 723 dwarf2_frame_default_init_reg (struct gdbarch *gdbarch, int regnum, 724 struct dwarf2_frame_state_reg *reg, 725 struct frame_info *this_frame) 726 { 727 /* If we have a register that acts as a program counter, mark it as 728 a destination for the return address. If we have a register that 729 serves as the stack pointer, arrange for it to be filled with the 730 call frame address (CFA). The other registers are marked as 731 unspecified. 732 733 We copy the return address to the program counter, since many 734 parts in GDB assume that it is possible to get the return address 735 by unwinding the program counter register. However, on ISA's 736 with a dedicated return address register, the CFI usually only 737 contains information to unwind that return address register. 738 739 The reason we're treating the stack pointer special here is 740 because in many cases GCC doesn't emit CFI for the stack pointer 741 and implicitly assumes that it is equal to the CFA. This makes 742 some sense since the DWARF specification (version 3, draft 8, 743 p. 102) says that: 744 745 "Typically, the CFA is defined to be the value of the stack 746 pointer at the call site in the previous frame (which may be 747 different from its value on entry to the current frame)." 748 749 However, this isn't true for all platforms supported by GCC 750 (e.g. IBM S/390 and zSeries). Those architectures should provide 751 their own architecture-specific initialization function. */ 752 753 if (regnum == gdbarch_pc_regnum (gdbarch)) 754 reg->how = DWARF2_FRAME_REG_RA; 755 else if (regnum == gdbarch_sp_regnum (gdbarch)) 756 reg->how = DWARF2_FRAME_REG_CFA; 757 } 758 759 /* Return a default for the architecture-specific operations. */ 760 761 static void * 762 dwarf2_frame_init (struct obstack *obstack) 763 { 764 struct dwarf2_frame_ops *ops; 765 766 ops = OBSTACK_ZALLOC (obstack, struct dwarf2_frame_ops); 767 ops->init_reg = dwarf2_frame_default_init_reg; 768 return ops; 769 } 770 771 /* Set the architecture-specific register state initialization 772 function for GDBARCH to INIT_REG. */ 773 774 void 775 dwarf2_frame_set_init_reg (struct gdbarch *gdbarch, 776 void (*init_reg) (struct gdbarch *, int, 777 struct dwarf2_frame_state_reg *, 778 struct frame_info *)) 779 { 780 struct dwarf2_frame_ops *ops = gdbarch_data (gdbarch, dwarf2_frame_data); 781 782 ops->init_reg = init_reg; 783 } 784 785 /* Pre-initialize the register state REG for register REGNUM. */ 786 787 static void 788 dwarf2_frame_init_reg (struct gdbarch *gdbarch, int regnum, 789 struct dwarf2_frame_state_reg *reg, 790 struct frame_info *this_frame) 791 { 792 struct dwarf2_frame_ops *ops = gdbarch_data (gdbarch, dwarf2_frame_data); 793 794 ops->init_reg (gdbarch, regnum, reg, this_frame); 795 } 796 797 /* Set the architecture-specific signal trampoline recognition 798 function for GDBARCH to SIGNAL_FRAME_P. */ 799 800 void 801 dwarf2_frame_set_signal_frame_p (struct gdbarch *gdbarch, 802 int (*signal_frame_p) (struct gdbarch *, 803 struct frame_info *)) 804 { 805 struct dwarf2_frame_ops *ops = gdbarch_data (gdbarch, dwarf2_frame_data); 806 807 ops->signal_frame_p = signal_frame_p; 808 } 809 810 /* Query the architecture-specific signal frame recognizer for 811 THIS_FRAME. */ 812 813 static int 814 dwarf2_frame_signal_frame_p (struct gdbarch *gdbarch, 815 struct frame_info *this_frame) 816 { 817 struct dwarf2_frame_ops *ops = gdbarch_data (gdbarch, dwarf2_frame_data); 818 819 if (ops->signal_frame_p == NULL) 820 return 0; 821 return ops->signal_frame_p (gdbarch, this_frame); 822 } 823 824 /* Set the architecture-specific adjustment of .eh_frame and .debug_frame 825 register numbers. */ 826 827 void 828 dwarf2_frame_set_adjust_regnum (struct gdbarch *gdbarch, 829 int (*adjust_regnum) (struct gdbarch *, 830 int, int)) 831 { 832 struct dwarf2_frame_ops *ops = gdbarch_data (gdbarch, dwarf2_frame_data); 833 834 ops->adjust_regnum = adjust_regnum; 835 } 836 837 /* Translate a .eh_frame register to DWARF register, or adjust a .debug_frame 838 register. */ 839 840 static int 841 dwarf2_frame_adjust_regnum (struct gdbarch *gdbarch, 842 int regnum, int eh_frame_p) 843 { 844 struct dwarf2_frame_ops *ops = gdbarch_data (gdbarch, dwarf2_frame_data); 845 846 if (ops->adjust_regnum == NULL) 847 return regnum; 848 return ops->adjust_regnum (gdbarch, regnum, eh_frame_p); 849 } 850 851 static void 852 dwarf2_frame_find_quirks (struct dwarf2_frame_state *fs, 853 struct dwarf2_fde *fde) 854 { 855 struct symtab *s; 856 857 s = find_pc_symtab (fs->pc); 858 if (s == NULL) 859 return; 860 861 if (producer_is_realview (s->producer)) 862 { 863 if (fde->cie->version == 1) 864 fs->armcc_cfa_offsets_sf = 1; 865 866 if (fde->cie->version == 1) 867 fs->armcc_cfa_offsets_reversed = 1; 868 869 /* The reversed offset problem is present in some compilers 870 using DWARF3, but it was eventually fixed. Check the ARM 871 defined augmentations, which are in the format "armcc" followed 872 by a list of one-character options. The "+" option means 873 this problem is fixed (no quirk needed). If the armcc 874 augmentation is missing, the quirk is needed. */ 875 if (fde->cie->version == 3 876 && (strncmp (fde->cie->augmentation, "armcc", 5) != 0 877 || strchr (fde->cie->augmentation + 5, '+') == NULL)) 878 fs->armcc_cfa_offsets_reversed = 1; 879 880 return; 881 } 882 } 883 884 885 void 886 dwarf2_compile_cfa_to_ax (struct agent_expr *expr, struct axs_value *loc, 887 struct gdbarch *gdbarch, 888 CORE_ADDR pc, 889 struct dwarf2_per_cu_data *data) 890 { 891 const int num_regs = gdbarch_num_regs (gdbarch) 892 + gdbarch_num_pseudo_regs (gdbarch); 893 struct dwarf2_fde *fde; 894 CORE_ADDR text_offset, cfa; 895 struct dwarf2_frame_state fs; 896 int addr_size; 897 898 memset (&fs, 0, sizeof (struct dwarf2_frame_state)); 899 900 fs.pc = pc; 901 902 /* Find the correct FDE. */ 903 fde = dwarf2_frame_find_fde (&fs.pc, &text_offset); 904 if (fde == NULL) 905 error (_("Could not compute CFA; needed to translate this expression")); 906 907 /* Extract any interesting information from the CIE. */ 908 fs.data_align = fde->cie->data_alignment_factor; 909 fs.code_align = fde->cie->code_alignment_factor; 910 fs.retaddr_column = fde->cie->return_address_register; 911 addr_size = fde->cie->addr_size; 912 913 /* Check for "quirks" - known bugs in producers. */ 914 dwarf2_frame_find_quirks (&fs, fde); 915 916 /* First decode all the insns in the CIE. */ 917 execute_cfa_program (fde, fde->cie->initial_instructions, 918 fde->cie->end, gdbarch, pc, &fs); 919 920 /* Save the initialized register set. */ 921 fs.initial = fs.regs; 922 fs.initial.reg = dwarf2_frame_state_copy_regs (&fs.regs); 923 924 /* Then decode the insns in the FDE up to our target PC. */ 925 execute_cfa_program (fde, fde->instructions, fde->end, gdbarch, pc, &fs); 926 927 /* Calculate the CFA. */ 928 switch (fs.regs.cfa_how) 929 { 930 case CFA_REG_OFFSET: 931 { 932 int regnum = gdbarch_dwarf2_reg_to_regnum (gdbarch, fs.regs.cfa_reg); 933 934 if (regnum == -1) 935 error (_("Unable to access DWARF register number %d"), 936 (int) fs.regs.cfa_reg); /* FIXME */ 937 ax_reg (expr, regnum); 938 939 if (fs.regs.cfa_offset != 0) 940 { 941 if (fs.armcc_cfa_offsets_reversed) 942 ax_const_l (expr, -fs.regs.cfa_offset); 943 else 944 ax_const_l (expr, fs.regs.cfa_offset); 945 ax_simple (expr, aop_add); 946 } 947 } 948 break; 949 950 case CFA_EXP: 951 ax_const_l (expr, text_offset); 952 dwarf2_compile_expr_to_ax (expr, loc, gdbarch, addr_size, 953 fs.regs.cfa_exp, 954 fs.regs.cfa_exp + fs.regs.cfa_exp_len, 955 data); 956 break; 957 958 default: 959 internal_error (__FILE__, __LINE__, _("Unknown CFA rule.")); 960 } 961 } 962 963 964 struct dwarf2_frame_cache 965 { 966 /* DWARF Call Frame Address. */ 967 CORE_ADDR cfa; 968 969 /* Set if the return address column was marked as unavailable 970 (required non-collected memory or registers to compute). */ 971 int unavailable_retaddr; 972 973 /* Set if the return address column was marked as undefined. */ 974 int undefined_retaddr; 975 976 /* Saved registers, indexed by GDB register number, not by DWARF 977 register number. */ 978 struct dwarf2_frame_state_reg *reg; 979 980 /* Return address register. */ 981 struct dwarf2_frame_state_reg retaddr_reg; 982 983 /* Target address size in bytes. */ 984 int addr_size; 985 986 /* The .text offset. */ 987 CORE_ADDR text_offset; 988 989 /* If not NULL then this frame is the bottom frame of a TAILCALL_FRAME 990 sequence. If NULL then it is a normal case with no TAILCALL_FRAME 991 involved. Non-bottom frames of a virtual tail call frames chain use 992 dwarf2_tailcall_frame_unwind unwinder so this field does not apply for 993 them. */ 994 void *tailcall_cache; 995 }; 996 997 static struct dwarf2_frame_cache * 998 dwarf2_frame_cache (struct frame_info *this_frame, void **this_cache) 999 { 1000 struct cleanup *old_chain; 1001 struct gdbarch *gdbarch = get_frame_arch (this_frame); 1002 const int num_regs = gdbarch_num_regs (gdbarch) 1003 + gdbarch_num_pseudo_regs (gdbarch); 1004 struct dwarf2_frame_cache *cache; 1005 struct dwarf2_frame_state *fs; 1006 struct dwarf2_fde *fde; 1007 volatile struct gdb_exception ex; 1008 CORE_ADDR entry_pc; 1009 LONGEST entry_cfa_sp_offset; 1010 int entry_cfa_sp_offset_p = 0; 1011 const gdb_byte *instr; 1012 1013 if (*this_cache) 1014 return *this_cache; 1015 1016 /* Allocate a new cache. */ 1017 cache = FRAME_OBSTACK_ZALLOC (struct dwarf2_frame_cache); 1018 cache->reg = FRAME_OBSTACK_CALLOC (num_regs, struct dwarf2_frame_state_reg); 1019 *this_cache = cache; 1020 1021 /* Allocate and initialize the frame state. */ 1022 fs = XZALLOC (struct dwarf2_frame_state); 1023 old_chain = make_cleanup (dwarf2_frame_state_free, fs); 1024 1025 /* Unwind the PC. 1026 1027 Note that if the next frame is never supposed to return (i.e. a call 1028 to abort), the compiler might optimize away the instruction at 1029 its return address. As a result the return address will 1030 point at some random instruction, and the CFI for that 1031 instruction is probably worthless to us. GCC's unwinder solves 1032 this problem by substracting 1 from the return address to get an 1033 address in the middle of a presumed call instruction (or the 1034 instruction in the associated delay slot). This should only be 1035 done for "normal" frames and not for resume-type frames (signal 1036 handlers, sentinel frames, dummy frames). The function 1037 get_frame_address_in_block does just this. It's not clear how 1038 reliable the method is though; there is the potential for the 1039 register state pre-call being different to that on return. */ 1040 fs->pc = get_frame_address_in_block (this_frame); 1041 1042 /* Find the correct FDE. */ 1043 fde = dwarf2_frame_find_fde (&fs->pc, &cache->text_offset); 1044 gdb_assert (fde != NULL); 1045 1046 /* Extract any interesting information from the CIE. */ 1047 fs->data_align = fde->cie->data_alignment_factor; 1048 fs->code_align = fde->cie->code_alignment_factor; 1049 fs->retaddr_column = fde->cie->return_address_register; 1050 cache->addr_size = fde->cie->addr_size; 1051 1052 /* Check for "quirks" - known bugs in producers. */ 1053 dwarf2_frame_find_quirks (fs, fde); 1054 1055 /* First decode all the insns in the CIE. */ 1056 execute_cfa_program (fde, fde->cie->initial_instructions, 1057 fde->cie->end, gdbarch, get_frame_pc (this_frame), fs); 1058 1059 /* Save the initialized register set. */ 1060 fs->initial = fs->regs; 1061 fs->initial.reg = dwarf2_frame_state_copy_regs (&fs->regs); 1062 1063 if (get_frame_func_if_available (this_frame, &entry_pc)) 1064 { 1065 /* Decode the insns in the FDE up to the entry PC. */ 1066 instr = execute_cfa_program (fde, fde->instructions, fde->end, gdbarch, 1067 entry_pc, fs); 1068 1069 if (fs->regs.cfa_how == CFA_REG_OFFSET 1070 && (gdbarch_dwarf2_reg_to_regnum (gdbarch, fs->regs.cfa_reg) 1071 == gdbarch_sp_regnum (gdbarch))) 1072 { 1073 entry_cfa_sp_offset = fs->regs.cfa_offset; 1074 entry_cfa_sp_offset_p = 1; 1075 } 1076 } 1077 else 1078 instr = fde->instructions; 1079 1080 /* Then decode the insns in the FDE up to our target PC. */ 1081 execute_cfa_program (fde, instr, fde->end, gdbarch, 1082 get_frame_pc (this_frame), fs); 1083 1084 TRY_CATCH (ex, RETURN_MASK_ERROR) 1085 { 1086 /* Calculate the CFA. */ 1087 switch (fs->regs.cfa_how) 1088 { 1089 case CFA_REG_OFFSET: 1090 cache->cfa = read_reg (this_frame, fs->regs.cfa_reg); 1091 if (fs->armcc_cfa_offsets_reversed) 1092 cache->cfa -= fs->regs.cfa_offset; 1093 else 1094 cache->cfa += fs->regs.cfa_offset; 1095 break; 1096 1097 case CFA_EXP: 1098 cache->cfa = 1099 execute_stack_op (fs->regs.cfa_exp, fs->regs.cfa_exp_len, 1100 cache->addr_size, cache->text_offset, 1101 this_frame, 0, 0); 1102 break; 1103 1104 default: 1105 internal_error (__FILE__, __LINE__, _("Unknown CFA rule.")); 1106 } 1107 } 1108 if (ex.reason < 0) 1109 { 1110 if (ex.error == NOT_AVAILABLE_ERROR) 1111 { 1112 cache->unavailable_retaddr = 1; 1113 return cache; 1114 } 1115 1116 throw_exception (ex); 1117 } 1118 1119 /* Initialize the register state. */ 1120 { 1121 int regnum; 1122 1123 for (regnum = 0; regnum < num_regs; regnum++) 1124 dwarf2_frame_init_reg (gdbarch, regnum, &cache->reg[regnum], this_frame); 1125 } 1126 1127 /* Go through the DWARF2 CFI generated table and save its register 1128 location information in the cache. Note that we don't skip the 1129 return address column; it's perfectly all right for it to 1130 correspond to a real register. If it doesn't correspond to a 1131 real register, or if we shouldn't treat it as such, 1132 gdbarch_dwarf2_reg_to_regnum should be defined to return a number outside 1133 the range [0, gdbarch_num_regs). */ 1134 { 1135 int column; /* CFI speak for "register number". */ 1136 1137 for (column = 0; column < fs->regs.num_regs; column++) 1138 { 1139 /* Use the GDB register number as the destination index. */ 1140 int regnum = gdbarch_dwarf2_reg_to_regnum (gdbarch, column); 1141 1142 /* If there's no corresponding GDB register, ignore it. */ 1143 if (regnum < 0 || regnum >= num_regs) 1144 continue; 1145 1146 /* NOTE: cagney/2003-09-05: CFI should specify the disposition 1147 of all debug info registers. If it doesn't, complain (but 1148 not too loudly). It turns out that GCC assumes that an 1149 unspecified register implies "same value" when CFI (draft 1150 7) specifies nothing at all. Such a register could equally 1151 be interpreted as "undefined". Also note that this check 1152 isn't sufficient; it only checks that all registers in the 1153 range [0 .. max column] are specified, and won't detect 1154 problems when a debug info register falls outside of the 1155 table. We need a way of iterating through all the valid 1156 DWARF2 register numbers. */ 1157 if (fs->regs.reg[column].how == DWARF2_FRAME_REG_UNSPECIFIED) 1158 { 1159 if (cache->reg[regnum].how == DWARF2_FRAME_REG_UNSPECIFIED) 1160 complaint (&symfile_complaints, _("\ 1161 incomplete CFI data; unspecified registers (e.g., %s) at %s"), 1162 gdbarch_register_name (gdbarch, regnum), 1163 paddress (gdbarch, fs->pc)); 1164 } 1165 else 1166 cache->reg[regnum] = fs->regs.reg[column]; 1167 } 1168 } 1169 1170 /* Eliminate any DWARF2_FRAME_REG_RA rules, and save the information 1171 we need for evaluating DWARF2_FRAME_REG_RA_OFFSET rules. */ 1172 { 1173 int regnum; 1174 1175 for (regnum = 0; regnum < num_regs; regnum++) 1176 { 1177 if (cache->reg[regnum].how == DWARF2_FRAME_REG_RA 1178 || cache->reg[regnum].how == DWARF2_FRAME_REG_RA_OFFSET) 1179 { 1180 struct dwarf2_frame_state_reg *retaddr_reg = 1181 &fs->regs.reg[fs->retaddr_column]; 1182 1183 /* It seems rather bizarre to specify an "empty" column as 1184 the return adress column. However, this is exactly 1185 what GCC does on some targets. It turns out that GCC 1186 assumes that the return address can be found in the 1187 register corresponding to the return address column. 1188 Incidentally, that's how we should treat a return 1189 address column specifying "same value" too. */ 1190 if (fs->retaddr_column < fs->regs.num_regs 1191 && retaddr_reg->how != DWARF2_FRAME_REG_UNSPECIFIED 1192 && retaddr_reg->how != DWARF2_FRAME_REG_SAME_VALUE) 1193 { 1194 if (cache->reg[regnum].how == DWARF2_FRAME_REG_RA) 1195 cache->reg[regnum] = *retaddr_reg; 1196 else 1197 cache->retaddr_reg = *retaddr_reg; 1198 } 1199 else 1200 { 1201 if (cache->reg[regnum].how == DWARF2_FRAME_REG_RA) 1202 { 1203 cache->reg[regnum].loc.reg = fs->retaddr_column; 1204 cache->reg[regnum].how = DWARF2_FRAME_REG_SAVED_REG; 1205 } 1206 else 1207 { 1208 cache->retaddr_reg.loc.reg = fs->retaddr_column; 1209 cache->retaddr_reg.how = DWARF2_FRAME_REG_SAVED_REG; 1210 } 1211 } 1212 } 1213 } 1214 } 1215 1216 if (fs->retaddr_column < fs->regs.num_regs 1217 && fs->regs.reg[fs->retaddr_column].how == DWARF2_FRAME_REG_UNDEFINED) 1218 cache->undefined_retaddr = 1; 1219 1220 do_cleanups (old_chain); 1221 1222 /* Try to find a virtual tail call frames chain with bottom (callee) frame 1223 starting at THIS_FRAME. */ 1224 dwarf2_tailcall_sniffer_first (this_frame, &cache->tailcall_cache, 1225 (entry_cfa_sp_offset_p 1226 ? &entry_cfa_sp_offset : NULL)); 1227 1228 return cache; 1229 } 1230 1231 static enum unwind_stop_reason 1232 dwarf2_frame_unwind_stop_reason (struct frame_info *this_frame, 1233 void **this_cache) 1234 { 1235 struct dwarf2_frame_cache *cache 1236 = dwarf2_frame_cache (this_frame, this_cache); 1237 1238 if (cache->unavailable_retaddr) 1239 return UNWIND_UNAVAILABLE; 1240 1241 if (cache->undefined_retaddr) 1242 return UNWIND_OUTERMOST; 1243 1244 return UNWIND_NO_REASON; 1245 } 1246 1247 static void 1248 dwarf2_frame_this_id (struct frame_info *this_frame, void **this_cache, 1249 struct frame_id *this_id) 1250 { 1251 struct dwarf2_frame_cache *cache = 1252 dwarf2_frame_cache (this_frame, this_cache); 1253 1254 if (cache->unavailable_retaddr) 1255 return; 1256 1257 if (cache->undefined_retaddr) 1258 return; 1259 1260 (*this_id) = frame_id_build (cache->cfa, get_frame_func (this_frame)); 1261 } 1262 1263 static struct value * 1264 dwarf2_frame_prev_register (struct frame_info *this_frame, void **this_cache, 1265 int regnum) 1266 { 1267 struct gdbarch *gdbarch = get_frame_arch (this_frame); 1268 struct dwarf2_frame_cache *cache = 1269 dwarf2_frame_cache (this_frame, this_cache); 1270 CORE_ADDR addr; 1271 int realnum; 1272 1273 /* Non-bottom frames of a virtual tail call frames chain use 1274 dwarf2_tailcall_frame_unwind unwinder so this code does not apply for 1275 them. If dwarf2_tailcall_prev_register_first does not have specific value 1276 unwind the register, tail call frames are assumed to have the register set 1277 of the top caller. */ 1278 if (cache->tailcall_cache) 1279 { 1280 struct value *val; 1281 1282 val = dwarf2_tailcall_prev_register_first (this_frame, 1283 &cache->tailcall_cache, 1284 regnum); 1285 if (val) 1286 return val; 1287 } 1288 1289 switch (cache->reg[regnum].how) 1290 { 1291 case DWARF2_FRAME_REG_UNDEFINED: 1292 /* If CFI explicitly specified that the value isn't defined, 1293 mark it as optimized away; the value isn't available. */ 1294 return frame_unwind_got_optimized (this_frame, regnum); 1295 1296 case DWARF2_FRAME_REG_SAVED_OFFSET: 1297 addr = cache->cfa + cache->reg[regnum].loc.offset; 1298 return frame_unwind_got_memory (this_frame, regnum, addr); 1299 1300 case DWARF2_FRAME_REG_SAVED_REG: 1301 realnum 1302 = gdbarch_dwarf2_reg_to_regnum (gdbarch, cache->reg[regnum].loc.reg); 1303 return frame_unwind_got_register (this_frame, regnum, realnum); 1304 1305 case DWARF2_FRAME_REG_SAVED_EXP: 1306 addr = execute_stack_op (cache->reg[regnum].loc.exp, 1307 cache->reg[regnum].exp_len, 1308 cache->addr_size, cache->text_offset, 1309 this_frame, cache->cfa, 1); 1310 return frame_unwind_got_memory (this_frame, regnum, addr); 1311 1312 case DWARF2_FRAME_REG_SAVED_VAL_OFFSET: 1313 addr = cache->cfa + cache->reg[regnum].loc.offset; 1314 return frame_unwind_got_constant (this_frame, regnum, addr); 1315 1316 case DWARF2_FRAME_REG_SAVED_VAL_EXP: 1317 addr = execute_stack_op (cache->reg[regnum].loc.exp, 1318 cache->reg[regnum].exp_len, 1319 cache->addr_size, cache->text_offset, 1320 this_frame, cache->cfa, 1); 1321 return frame_unwind_got_constant (this_frame, regnum, addr); 1322 1323 case DWARF2_FRAME_REG_UNSPECIFIED: 1324 /* GCC, in its infinite wisdom decided to not provide unwind 1325 information for registers that are "same value". Since 1326 DWARF2 (3 draft 7) doesn't define such behavior, said 1327 registers are actually undefined (which is different to CFI 1328 "undefined"). Code above issues a complaint about this. 1329 Here just fudge the books, assume GCC, and that the value is 1330 more inner on the stack. */ 1331 return frame_unwind_got_register (this_frame, regnum, regnum); 1332 1333 case DWARF2_FRAME_REG_SAME_VALUE: 1334 return frame_unwind_got_register (this_frame, regnum, regnum); 1335 1336 case DWARF2_FRAME_REG_CFA: 1337 return frame_unwind_got_address (this_frame, regnum, cache->cfa); 1338 1339 case DWARF2_FRAME_REG_CFA_OFFSET: 1340 addr = cache->cfa + cache->reg[regnum].loc.offset; 1341 return frame_unwind_got_address (this_frame, regnum, addr); 1342 1343 case DWARF2_FRAME_REG_RA_OFFSET: 1344 addr = cache->reg[regnum].loc.offset; 1345 regnum = gdbarch_dwarf2_reg_to_regnum 1346 (gdbarch, cache->retaddr_reg.loc.reg); 1347 addr += get_frame_register_unsigned (this_frame, regnum); 1348 return frame_unwind_got_address (this_frame, regnum, addr); 1349 1350 case DWARF2_FRAME_REG_FN: 1351 return cache->reg[regnum].loc.fn (this_frame, this_cache, regnum); 1352 1353 default: 1354 internal_error (__FILE__, __LINE__, _("Unknown register rule.")); 1355 } 1356 } 1357 1358 /* Proxy for tailcall_frame_dealloc_cache for bottom frame of a virtual tail 1359 call frames chain. */ 1360 1361 static void 1362 dwarf2_frame_dealloc_cache (struct frame_info *self, void *this_cache) 1363 { 1364 struct dwarf2_frame_cache *cache = dwarf2_frame_cache (self, &this_cache); 1365 1366 if (cache->tailcall_cache) 1367 dwarf2_tailcall_frame_unwind.dealloc_cache (self, cache->tailcall_cache); 1368 } 1369 1370 static int 1371 dwarf2_frame_sniffer (const struct frame_unwind *self, 1372 struct frame_info *this_frame, void **this_cache) 1373 { 1374 /* Grab an address that is guarenteed to reside somewhere within the 1375 function. get_frame_pc(), with a no-return next function, can 1376 end up returning something past the end of this function's body. 1377 If the frame we're sniffing for is a signal frame whose start 1378 address is placed on the stack by the OS, its FDE must 1379 extend one byte before its start address or we could potentially 1380 select the FDE of the previous function. */ 1381 CORE_ADDR block_addr = get_frame_address_in_block (this_frame); 1382 struct dwarf2_fde *fde = dwarf2_frame_find_fde (&block_addr, NULL); 1383 1384 if (!fde) 1385 return 0; 1386 1387 /* On some targets, signal trampolines may have unwind information. 1388 We need to recognize them so that we set the frame type 1389 correctly. */ 1390 1391 if (fde->cie->signal_frame 1392 || dwarf2_frame_signal_frame_p (get_frame_arch (this_frame), 1393 this_frame)) 1394 return self->type == SIGTRAMP_FRAME; 1395 1396 if (self->type != NORMAL_FRAME) 1397 return 0; 1398 1399 /* Preinitializa the cache so that TAILCALL_FRAME can find the record by 1400 dwarf2_tailcall_sniffer_first. */ 1401 dwarf2_frame_cache (this_frame, this_cache); 1402 1403 return 1; 1404 } 1405 1406 static const struct frame_unwind dwarf2_frame_unwind = 1407 { 1408 NORMAL_FRAME, 1409 dwarf2_frame_unwind_stop_reason, 1410 dwarf2_frame_this_id, 1411 dwarf2_frame_prev_register, 1412 NULL, 1413 dwarf2_frame_sniffer, 1414 dwarf2_frame_dealloc_cache 1415 }; 1416 1417 static const struct frame_unwind dwarf2_signal_frame_unwind = 1418 { 1419 SIGTRAMP_FRAME, 1420 dwarf2_frame_unwind_stop_reason, 1421 dwarf2_frame_this_id, 1422 dwarf2_frame_prev_register, 1423 NULL, 1424 dwarf2_frame_sniffer, 1425 1426 /* TAILCALL_CACHE can never be in such frame to need dealloc_cache. */ 1427 NULL 1428 }; 1429 1430 /* Append the DWARF-2 frame unwinders to GDBARCH's list. */ 1431 1432 void 1433 dwarf2_append_unwinders (struct gdbarch *gdbarch) 1434 { 1435 /* TAILCALL_FRAME must be first to find the record by 1436 dwarf2_tailcall_sniffer_first. */ 1437 frame_unwind_append_unwinder (gdbarch, &dwarf2_tailcall_frame_unwind); 1438 1439 frame_unwind_append_unwinder (gdbarch, &dwarf2_frame_unwind); 1440 frame_unwind_append_unwinder (gdbarch, &dwarf2_signal_frame_unwind); 1441 } 1442 1443 1444 /* There is no explicitly defined relationship between the CFA and the 1445 location of frame's local variables and arguments/parameters. 1446 Therefore, frame base methods on this page should probably only be 1447 used as a last resort, just to avoid printing total garbage as a 1448 response to the "info frame" command. */ 1449 1450 static CORE_ADDR 1451 dwarf2_frame_base_address (struct frame_info *this_frame, void **this_cache) 1452 { 1453 struct dwarf2_frame_cache *cache = 1454 dwarf2_frame_cache (this_frame, this_cache); 1455 1456 return cache->cfa; 1457 } 1458 1459 static const struct frame_base dwarf2_frame_base = 1460 { 1461 &dwarf2_frame_unwind, 1462 dwarf2_frame_base_address, 1463 dwarf2_frame_base_address, 1464 dwarf2_frame_base_address 1465 }; 1466 1467 const struct frame_base * 1468 dwarf2_frame_base_sniffer (struct frame_info *this_frame) 1469 { 1470 CORE_ADDR block_addr = get_frame_address_in_block (this_frame); 1471 1472 if (dwarf2_frame_find_fde (&block_addr, NULL)) 1473 return &dwarf2_frame_base; 1474 1475 return NULL; 1476 } 1477 1478 /* Compute the CFA for THIS_FRAME, but only if THIS_FRAME came from 1479 the DWARF unwinder. This is used to implement 1480 DW_OP_call_frame_cfa. */ 1481 1482 CORE_ADDR 1483 dwarf2_frame_cfa (struct frame_info *this_frame) 1484 { 1485 while (get_frame_type (this_frame) == INLINE_FRAME) 1486 this_frame = get_prev_frame (this_frame); 1487 /* This restriction could be lifted if other unwinders are known to 1488 compute the frame base in a way compatible with the DWARF 1489 unwinder. */ 1490 if (!frame_unwinder_is (this_frame, &dwarf2_frame_unwind) 1491 && !frame_unwinder_is (this_frame, &dwarf2_tailcall_frame_unwind)) 1492 error (_("can't compute CFA for this frame")); 1493 return get_frame_base (this_frame); 1494 } 1495 1496 const struct objfile_data *dwarf2_frame_objfile_data; 1497 1498 static unsigned int 1499 read_1_byte (bfd *abfd, gdb_byte *buf) 1500 { 1501 return bfd_get_8 (abfd, buf); 1502 } 1503 1504 static unsigned int 1505 read_4_bytes (bfd *abfd, gdb_byte *buf) 1506 { 1507 return bfd_get_32 (abfd, buf); 1508 } 1509 1510 static ULONGEST 1511 read_8_bytes (bfd *abfd, gdb_byte *buf) 1512 { 1513 return bfd_get_64 (abfd, buf); 1514 } 1515 1516 static ULONGEST 1517 read_unsigned_leb128 (bfd *abfd, gdb_byte *buf, unsigned int *bytes_read_ptr) 1518 { 1519 ULONGEST result; 1520 unsigned int num_read; 1521 int shift; 1522 gdb_byte byte; 1523 1524 result = 0; 1525 shift = 0; 1526 num_read = 0; 1527 1528 do 1529 { 1530 byte = bfd_get_8 (abfd, (bfd_byte *) buf); 1531 buf++; 1532 num_read++; 1533 result |= ((byte & 0x7f) << shift); 1534 shift += 7; 1535 } 1536 while (byte & 0x80); 1537 1538 *bytes_read_ptr = num_read; 1539 1540 return result; 1541 } 1542 1543 static LONGEST 1544 read_signed_leb128 (bfd *abfd, gdb_byte *buf, unsigned int *bytes_read_ptr) 1545 { 1546 LONGEST result; 1547 int shift; 1548 unsigned int num_read; 1549 gdb_byte byte; 1550 1551 result = 0; 1552 shift = 0; 1553 num_read = 0; 1554 1555 do 1556 { 1557 byte = bfd_get_8 (abfd, (bfd_byte *) buf); 1558 buf++; 1559 num_read++; 1560 result |= ((byte & 0x7f) << shift); 1561 shift += 7; 1562 } 1563 while (byte & 0x80); 1564 1565 if (shift < 8 * sizeof (result) && (byte & 0x40)) 1566 result |= -(((LONGEST)1) << shift); 1567 1568 *bytes_read_ptr = num_read; 1569 1570 return result; 1571 } 1572 1573 static ULONGEST 1574 read_initial_length (bfd *abfd, gdb_byte *buf, unsigned int *bytes_read_ptr) 1575 { 1576 LONGEST result; 1577 1578 result = bfd_get_32 (abfd, buf); 1579 if (result == 0xffffffff) 1580 { 1581 result = bfd_get_64 (abfd, buf + 4); 1582 *bytes_read_ptr = 12; 1583 } 1584 else 1585 *bytes_read_ptr = 4; 1586 1587 return result; 1588 } 1589 1590 1591 /* Pointer encoding helper functions. */ 1592 1593 /* GCC supports exception handling based on DWARF2 CFI. However, for 1594 technical reasons, it encodes addresses in its FDE's in a different 1595 way. Several "pointer encodings" are supported. The encoding 1596 that's used for a particular FDE is determined by the 'R' 1597 augmentation in the associated CIE. The argument of this 1598 augmentation is a single byte. 1599 1600 The address can be encoded as 2 bytes, 4 bytes, 8 bytes, or as a 1601 LEB128. This is encoded in bits 0, 1 and 2. Bit 3 encodes whether 1602 the address is signed or unsigned. Bits 4, 5 and 6 encode how the 1603 address should be interpreted (absolute, relative to the current 1604 position in the FDE, ...). Bit 7, indicates that the address 1605 should be dereferenced. */ 1606 1607 static gdb_byte 1608 encoding_for_size (unsigned int size) 1609 { 1610 switch (size) 1611 { 1612 case 2: 1613 return DW_EH_PE_udata2; 1614 case 4: 1615 return DW_EH_PE_udata4; 1616 case 8: 1617 return DW_EH_PE_udata8; 1618 default: 1619 internal_error (__FILE__, __LINE__, _("Unsupported address size")); 1620 } 1621 } 1622 1623 static CORE_ADDR 1624 read_encoded_value (struct comp_unit *unit, gdb_byte encoding, 1625 int ptr_len, const gdb_byte *buf, 1626 unsigned int *bytes_read_ptr, 1627 CORE_ADDR func_base) 1628 { 1629 ptrdiff_t offset; 1630 CORE_ADDR base; 1631 1632 /* GCC currently doesn't generate DW_EH_PE_indirect encodings for 1633 FDE's. */ 1634 if (encoding & DW_EH_PE_indirect) 1635 internal_error (__FILE__, __LINE__, 1636 _("Unsupported encoding: DW_EH_PE_indirect")); 1637 1638 *bytes_read_ptr = 0; 1639 1640 switch (encoding & 0x70) 1641 { 1642 case DW_EH_PE_absptr: 1643 base = 0; 1644 break; 1645 case DW_EH_PE_pcrel: 1646 base = bfd_get_section_vma (unit->abfd, unit->dwarf_frame_section); 1647 base += (buf - unit->dwarf_frame_buffer); 1648 break; 1649 case DW_EH_PE_datarel: 1650 base = unit->dbase; 1651 break; 1652 case DW_EH_PE_textrel: 1653 base = unit->tbase; 1654 break; 1655 case DW_EH_PE_funcrel: 1656 base = func_base; 1657 break; 1658 case DW_EH_PE_aligned: 1659 base = 0; 1660 offset = buf - unit->dwarf_frame_buffer; 1661 if ((offset % ptr_len) != 0) 1662 { 1663 *bytes_read_ptr = ptr_len - (offset % ptr_len); 1664 buf += *bytes_read_ptr; 1665 } 1666 break; 1667 default: 1668 internal_error (__FILE__, __LINE__, 1669 _("Invalid or unsupported encoding")); 1670 } 1671 1672 if ((encoding & 0x07) == 0x00) 1673 { 1674 encoding |= encoding_for_size (ptr_len); 1675 if (bfd_get_sign_extend_vma (unit->abfd)) 1676 encoding |= DW_EH_PE_signed; 1677 } 1678 1679 switch (encoding & 0x0f) 1680 { 1681 case DW_EH_PE_uleb128: 1682 { 1683 ULONGEST value; 1684 const gdb_byte *end_buf = buf + (sizeof (value) + 1) * 8 / 7; 1685 1686 *bytes_read_ptr += read_uleb128 (buf, end_buf, &value) - buf; 1687 return base + value; 1688 } 1689 case DW_EH_PE_udata2: 1690 *bytes_read_ptr += 2; 1691 return (base + bfd_get_16 (unit->abfd, (bfd_byte *) buf)); 1692 case DW_EH_PE_udata4: 1693 *bytes_read_ptr += 4; 1694 return (base + bfd_get_32 (unit->abfd, (bfd_byte *) buf)); 1695 case DW_EH_PE_udata8: 1696 *bytes_read_ptr += 8; 1697 return (base + bfd_get_64 (unit->abfd, (bfd_byte *) buf)); 1698 case DW_EH_PE_sleb128: 1699 { 1700 LONGEST value; 1701 const gdb_byte *end_buf = buf + (sizeof (value) + 1) * 8 / 7; 1702 1703 *bytes_read_ptr += read_sleb128 (buf, end_buf, &value) - buf; 1704 return base + value; 1705 } 1706 case DW_EH_PE_sdata2: 1707 *bytes_read_ptr += 2; 1708 return (base + bfd_get_signed_16 (unit->abfd, (bfd_byte *) buf)); 1709 case DW_EH_PE_sdata4: 1710 *bytes_read_ptr += 4; 1711 return (base + bfd_get_signed_32 (unit->abfd, (bfd_byte *) buf)); 1712 case DW_EH_PE_sdata8: 1713 *bytes_read_ptr += 8; 1714 return (base + bfd_get_signed_64 (unit->abfd, (bfd_byte *) buf)); 1715 default: 1716 internal_error (__FILE__, __LINE__, 1717 _("Invalid or unsupported encoding")); 1718 } 1719 } 1720 1721 1722 static int 1723 bsearch_cie_cmp (const void *key, const void *element) 1724 { 1725 ULONGEST cie_pointer = *(ULONGEST *) key; 1726 struct dwarf2_cie *cie = *(struct dwarf2_cie **) element; 1727 1728 if (cie_pointer == cie->cie_pointer) 1729 return 0; 1730 1731 return (cie_pointer < cie->cie_pointer) ? -1 : 1; 1732 } 1733 1734 /* Find CIE with the given CIE_POINTER in CIE_TABLE. */ 1735 static struct dwarf2_cie * 1736 find_cie (struct dwarf2_cie_table *cie_table, ULONGEST cie_pointer) 1737 { 1738 struct dwarf2_cie **p_cie; 1739 1740 /* The C standard (ISO/IEC 9899:TC2) requires the BASE argument to 1741 bsearch be non-NULL. */ 1742 if (cie_table->entries == NULL) 1743 { 1744 gdb_assert (cie_table->num_entries == 0); 1745 return NULL; 1746 } 1747 1748 p_cie = bsearch (&cie_pointer, cie_table->entries, cie_table->num_entries, 1749 sizeof (cie_table->entries[0]), bsearch_cie_cmp); 1750 if (p_cie != NULL) 1751 return *p_cie; 1752 return NULL; 1753 } 1754 1755 /* Add a pointer to new CIE to the CIE_TABLE, allocating space for it. */ 1756 static void 1757 add_cie (struct dwarf2_cie_table *cie_table, struct dwarf2_cie *cie) 1758 { 1759 const int n = cie_table->num_entries; 1760 1761 gdb_assert (n < 1 1762 || cie_table->entries[n - 1]->cie_pointer < cie->cie_pointer); 1763 1764 cie_table->entries = 1765 xrealloc (cie_table->entries, (n + 1) * sizeof (cie_table->entries[0])); 1766 cie_table->entries[n] = cie; 1767 cie_table->num_entries = n + 1; 1768 } 1769 1770 static int 1771 bsearch_fde_cmp (const void *key, const void *element) 1772 { 1773 CORE_ADDR seek_pc = *(CORE_ADDR *) key; 1774 struct dwarf2_fde *fde = *(struct dwarf2_fde **) element; 1775 1776 if (seek_pc < fde->initial_location) 1777 return -1; 1778 if (seek_pc < fde->initial_location + fde->address_range) 1779 return 0; 1780 return 1; 1781 } 1782 1783 /* Find the FDE for *PC. Return a pointer to the FDE, and store the 1784 inital location associated with it into *PC. */ 1785 1786 static struct dwarf2_fde * 1787 dwarf2_frame_find_fde (CORE_ADDR *pc, CORE_ADDR *out_offset) 1788 { 1789 struct objfile *objfile; 1790 1791 ALL_OBJFILES (objfile) 1792 { 1793 struct dwarf2_fde_table *fde_table; 1794 struct dwarf2_fde **p_fde; 1795 CORE_ADDR offset; 1796 CORE_ADDR seek_pc; 1797 1798 fde_table = objfile_data (objfile, dwarf2_frame_objfile_data); 1799 if (fde_table == NULL) 1800 { 1801 dwarf2_build_frame_info (objfile); 1802 fde_table = objfile_data (objfile, dwarf2_frame_objfile_data); 1803 } 1804 gdb_assert (fde_table != NULL); 1805 1806 if (fde_table->num_entries == 0) 1807 continue; 1808 1809 gdb_assert (objfile->section_offsets); 1810 offset = ANOFFSET (objfile->section_offsets, SECT_OFF_TEXT (objfile)); 1811 1812 gdb_assert (fde_table->num_entries > 0); 1813 if (*pc < offset + fde_table->entries[0]->initial_location) 1814 continue; 1815 1816 seek_pc = *pc - offset; 1817 p_fde = bsearch (&seek_pc, fde_table->entries, fde_table->num_entries, 1818 sizeof (fde_table->entries[0]), bsearch_fde_cmp); 1819 if (p_fde != NULL) 1820 { 1821 *pc = (*p_fde)->initial_location + offset; 1822 if (out_offset) 1823 *out_offset = offset; 1824 return *p_fde; 1825 } 1826 } 1827 return NULL; 1828 } 1829 1830 /* Add a pointer to new FDE to the FDE_TABLE, allocating space for it. */ 1831 static void 1832 add_fde (struct dwarf2_fde_table *fde_table, struct dwarf2_fde *fde) 1833 { 1834 if (fde->address_range == 0) 1835 /* Discard useless FDEs. */ 1836 return; 1837 1838 fde_table->num_entries += 1; 1839 fde_table->entries = 1840 xrealloc (fde_table->entries, 1841 fde_table->num_entries * sizeof (fde_table->entries[0])); 1842 fde_table->entries[fde_table->num_entries - 1] = fde; 1843 } 1844 1845 #ifdef CC_HAS_LONG_LONG 1846 #define DW64_CIE_ID 0xffffffffffffffffULL 1847 #else 1848 #define DW64_CIE_ID ~0 1849 #endif 1850 1851 /* Defines the type of eh_frames that are expected to be decoded: CIE, FDE 1852 or any of them. */ 1853 1854 enum eh_frame_type 1855 { 1856 EH_CIE_TYPE_ID = 1 << 0, 1857 EH_FDE_TYPE_ID = 1 << 1, 1858 EH_CIE_OR_FDE_TYPE_ID = EH_CIE_TYPE_ID | EH_FDE_TYPE_ID 1859 }; 1860 1861 static gdb_byte *decode_frame_entry (struct comp_unit *unit, gdb_byte *start, 1862 int eh_frame_p, 1863 struct dwarf2_cie_table *cie_table, 1864 struct dwarf2_fde_table *fde_table, 1865 enum eh_frame_type entry_type); 1866 1867 /* Decode the next CIE or FDE, entry_type specifies the expected type. 1868 Return NULL if invalid input, otherwise the next byte to be processed. */ 1869 1870 static gdb_byte * 1871 decode_frame_entry_1 (struct comp_unit *unit, gdb_byte *start, int eh_frame_p, 1872 struct dwarf2_cie_table *cie_table, 1873 struct dwarf2_fde_table *fde_table, 1874 enum eh_frame_type entry_type) 1875 { 1876 struct gdbarch *gdbarch = get_objfile_arch (unit->objfile); 1877 gdb_byte *buf, *end; 1878 LONGEST length; 1879 unsigned int bytes_read; 1880 int dwarf64_p; 1881 ULONGEST cie_id; 1882 ULONGEST cie_pointer; 1883 1884 buf = start; 1885 length = read_initial_length (unit->abfd, buf, &bytes_read); 1886 buf += bytes_read; 1887 end = buf + length; 1888 1889 /* Are we still within the section? */ 1890 if (end > unit->dwarf_frame_buffer + unit->dwarf_frame_size) 1891 return NULL; 1892 1893 if (length == 0) 1894 return end; 1895 1896 /* Distinguish between 32 and 64-bit encoded frame info. */ 1897 dwarf64_p = (bytes_read == 12); 1898 1899 /* In a .eh_frame section, zero is used to distinguish CIEs from FDEs. */ 1900 if (eh_frame_p) 1901 cie_id = 0; 1902 else if (dwarf64_p) 1903 cie_id = DW64_CIE_ID; 1904 else 1905 cie_id = DW_CIE_ID; 1906 1907 if (dwarf64_p) 1908 { 1909 cie_pointer = read_8_bytes (unit->abfd, buf); 1910 buf += 8; 1911 } 1912 else 1913 { 1914 cie_pointer = read_4_bytes (unit->abfd, buf); 1915 buf += 4; 1916 } 1917 1918 if (cie_pointer == cie_id) 1919 { 1920 /* This is a CIE. */ 1921 struct dwarf2_cie *cie; 1922 char *augmentation; 1923 unsigned int cie_version; 1924 1925 /* Check that a CIE was expected. */ 1926 if ((entry_type & EH_CIE_TYPE_ID) == 0) 1927 error (_("Found a CIE when not expecting it.")); 1928 1929 /* Record the offset into the .debug_frame section of this CIE. */ 1930 cie_pointer = start - unit->dwarf_frame_buffer; 1931 1932 /* Check whether we've already read it. */ 1933 if (find_cie (cie_table, cie_pointer)) 1934 return end; 1935 1936 cie = (struct dwarf2_cie *) 1937 obstack_alloc (&unit->objfile->objfile_obstack, 1938 sizeof (struct dwarf2_cie)); 1939 cie->initial_instructions = NULL; 1940 cie->cie_pointer = cie_pointer; 1941 1942 /* The encoding for FDE's in a normal .debug_frame section 1943 depends on the target address size. */ 1944 cie->encoding = DW_EH_PE_absptr; 1945 1946 /* We'll determine the final value later, but we need to 1947 initialize it conservatively. */ 1948 cie->signal_frame = 0; 1949 1950 /* Check version number. */ 1951 cie_version = read_1_byte (unit->abfd, buf); 1952 if (cie_version != 1 && cie_version != 3 && cie_version != 4) 1953 return NULL; 1954 cie->version = cie_version; 1955 buf += 1; 1956 1957 /* Interpret the interesting bits of the augmentation. */ 1958 cie->augmentation = augmentation = (char *) buf; 1959 buf += (strlen (augmentation) + 1); 1960 1961 /* Ignore armcc augmentations. We only use them for quirks, 1962 and that doesn't happen until later. */ 1963 if (strncmp (augmentation, "armcc", 5) == 0) 1964 augmentation += strlen (augmentation); 1965 1966 /* The GCC 2.x "eh" augmentation has a pointer immediately 1967 following the augmentation string, so it must be handled 1968 first. */ 1969 if (augmentation[0] == 'e' && augmentation[1] == 'h') 1970 { 1971 /* Skip. */ 1972 buf += gdbarch_ptr_bit (gdbarch) / TARGET_CHAR_BIT; 1973 augmentation += 2; 1974 } 1975 1976 if (cie->version >= 4) 1977 { 1978 /* FIXME: check that this is the same as from the CU header. */ 1979 cie->addr_size = read_1_byte (unit->abfd, buf); 1980 ++buf; 1981 cie->segment_size = read_1_byte (unit->abfd, buf); 1982 ++buf; 1983 } 1984 else 1985 { 1986 cie->addr_size = gdbarch_dwarf2_addr_size (gdbarch); 1987 cie->segment_size = 0; 1988 } 1989 /* Address values in .eh_frame sections are defined to have the 1990 target's pointer size. Watchout: This breaks frame info for 1991 targets with pointer size < address size, unless a .debug_frame 1992 section exists as well. */ 1993 if (eh_frame_p) 1994 cie->ptr_size = gdbarch_ptr_bit (gdbarch) / TARGET_CHAR_BIT; 1995 else 1996 cie->ptr_size = cie->addr_size; 1997 1998 cie->code_alignment_factor = 1999 read_unsigned_leb128 (unit->abfd, buf, &bytes_read); 2000 buf += bytes_read; 2001 2002 cie->data_alignment_factor = 2003 read_signed_leb128 (unit->abfd, buf, &bytes_read); 2004 buf += bytes_read; 2005 2006 if (cie_version == 1) 2007 { 2008 cie->return_address_register = read_1_byte (unit->abfd, buf); 2009 bytes_read = 1; 2010 } 2011 else 2012 cie->return_address_register = read_unsigned_leb128 (unit->abfd, buf, 2013 &bytes_read); 2014 cie->return_address_register 2015 = dwarf2_frame_adjust_regnum (gdbarch, 2016 cie->return_address_register, 2017 eh_frame_p); 2018 2019 buf += bytes_read; 2020 2021 cie->saw_z_augmentation = (*augmentation == 'z'); 2022 if (cie->saw_z_augmentation) 2023 { 2024 ULONGEST length; 2025 2026 length = read_unsigned_leb128 (unit->abfd, buf, &bytes_read); 2027 buf += bytes_read; 2028 if (buf > end) 2029 return NULL; 2030 cie->initial_instructions = buf + length; 2031 augmentation++; 2032 } 2033 2034 while (*augmentation) 2035 { 2036 /* "L" indicates a byte showing how the LSDA pointer is encoded. */ 2037 if (*augmentation == 'L') 2038 { 2039 /* Skip. */ 2040 buf++; 2041 augmentation++; 2042 } 2043 2044 /* "R" indicates a byte indicating how FDE addresses are encoded. */ 2045 else if (*augmentation == 'R') 2046 { 2047 cie->encoding = *buf++; 2048 augmentation++; 2049 } 2050 2051 /* "P" indicates a personality routine in the CIE augmentation. */ 2052 else if (*augmentation == 'P') 2053 { 2054 /* Skip. Avoid indirection since we throw away the result. */ 2055 gdb_byte encoding = (*buf++) & ~DW_EH_PE_indirect; 2056 read_encoded_value (unit, encoding, cie->ptr_size, 2057 buf, &bytes_read, 0); 2058 buf += bytes_read; 2059 augmentation++; 2060 } 2061 2062 /* "S" indicates a signal frame, such that the return 2063 address must not be decremented to locate the call frame 2064 info for the previous frame; it might even be the first 2065 instruction of a function, so decrementing it would take 2066 us to a different function. */ 2067 else if (*augmentation == 'S') 2068 { 2069 cie->signal_frame = 1; 2070 augmentation++; 2071 } 2072 2073 /* Otherwise we have an unknown augmentation. Assume that either 2074 there is no augmentation data, or we saw a 'z' prefix. */ 2075 else 2076 { 2077 if (cie->initial_instructions) 2078 buf = cie->initial_instructions; 2079 break; 2080 } 2081 } 2082 2083 cie->initial_instructions = buf; 2084 cie->end = end; 2085 cie->unit = unit; 2086 2087 add_cie (cie_table, cie); 2088 } 2089 else 2090 { 2091 /* This is a FDE. */ 2092 struct dwarf2_fde *fde; 2093 2094 /* Check that an FDE was expected. */ 2095 if ((entry_type & EH_FDE_TYPE_ID) == 0) 2096 error (_("Found an FDE when not expecting it.")); 2097 2098 /* In an .eh_frame section, the CIE pointer is the delta between the 2099 address within the FDE where the CIE pointer is stored and the 2100 address of the CIE. Convert it to an offset into the .eh_frame 2101 section. */ 2102 if (eh_frame_p) 2103 { 2104 cie_pointer = buf - unit->dwarf_frame_buffer - cie_pointer; 2105 cie_pointer -= (dwarf64_p ? 8 : 4); 2106 } 2107 2108 /* In either case, validate the result is still within the section. */ 2109 if (cie_pointer >= unit->dwarf_frame_size) 2110 return NULL; 2111 2112 fde = (struct dwarf2_fde *) 2113 obstack_alloc (&unit->objfile->objfile_obstack, 2114 sizeof (struct dwarf2_fde)); 2115 fde->cie = find_cie (cie_table, cie_pointer); 2116 if (fde->cie == NULL) 2117 { 2118 decode_frame_entry (unit, unit->dwarf_frame_buffer + cie_pointer, 2119 eh_frame_p, cie_table, fde_table, 2120 EH_CIE_TYPE_ID); 2121 fde->cie = find_cie (cie_table, cie_pointer); 2122 } 2123 2124 gdb_assert (fde->cie != NULL); 2125 2126 fde->initial_location = 2127 read_encoded_value (unit, fde->cie->encoding, fde->cie->ptr_size, 2128 buf, &bytes_read, 0); 2129 buf += bytes_read; 2130 2131 fde->address_range = 2132 read_encoded_value (unit, fde->cie->encoding & 0x0f, 2133 fde->cie->ptr_size, buf, &bytes_read, 0); 2134 buf += bytes_read; 2135 2136 /* A 'z' augmentation in the CIE implies the presence of an 2137 augmentation field in the FDE as well. The only thing known 2138 to be in here at present is the LSDA entry for EH. So we 2139 can skip the whole thing. */ 2140 if (fde->cie->saw_z_augmentation) 2141 { 2142 ULONGEST length; 2143 2144 length = read_unsigned_leb128 (unit->abfd, buf, &bytes_read); 2145 buf += bytes_read + length; 2146 if (buf > end) 2147 return NULL; 2148 } 2149 2150 fde->instructions = buf; 2151 fde->end = end; 2152 2153 fde->eh_frame_p = eh_frame_p; 2154 2155 add_fde (fde_table, fde); 2156 } 2157 2158 return end; 2159 } 2160 2161 /* Read a CIE or FDE in BUF and decode it. Entry_type specifies whether we 2162 expect an FDE or a CIE. */ 2163 2164 static gdb_byte * 2165 decode_frame_entry (struct comp_unit *unit, gdb_byte *start, int eh_frame_p, 2166 struct dwarf2_cie_table *cie_table, 2167 struct dwarf2_fde_table *fde_table, 2168 enum eh_frame_type entry_type) 2169 { 2170 enum { NONE, ALIGN4, ALIGN8, FAIL } workaround = NONE; 2171 gdb_byte *ret; 2172 ptrdiff_t start_offset; 2173 2174 while (1) 2175 { 2176 ret = decode_frame_entry_1 (unit, start, eh_frame_p, 2177 cie_table, fde_table, entry_type); 2178 if (ret != NULL) 2179 break; 2180 2181 /* We have corrupt input data of some form. */ 2182 2183 /* ??? Try, weakly, to work around compiler/assembler/linker bugs 2184 and mismatches wrt padding and alignment of debug sections. */ 2185 /* Note that there is no requirement in the standard for any 2186 alignment at all in the frame unwind sections. Testing for 2187 alignment before trying to interpret data would be incorrect. 2188 2189 However, GCC traditionally arranged for frame sections to be 2190 sized such that the FDE length and CIE fields happen to be 2191 aligned (in theory, for performance). This, unfortunately, 2192 was done with .align directives, which had the side effect of 2193 forcing the section to be aligned by the linker. 2194 2195 This becomes a problem when you have some other producer that 2196 creates frame sections that are not as strictly aligned. That 2197 produces a hole in the frame info that gets filled by the 2198 linker with zeros. 2199 2200 The GCC behaviour is arguably a bug, but it's effectively now 2201 part of the ABI, so we're now stuck with it, at least at the 2202 object file level. A smart linker may decide, in the process 2203 of compressing duplicate CIE information, that it can rewrite 2204 the entire output section without this extra padding. */ 2205 2206 start_offset = start - unit->dwarf_frame_buffer; 2207 if (workaround < ALIGN4 && (start_offset & 3) != 0) 2208 { 2209 start += 4 - (start_offset & 3); 2210 workaround = ALIGN4; 2211 continue; 2212 } 2213 if (workaround < ALIGN8 && (start_offset & 7) != 0) 2214 { 2215 start += 8 - (start_offset & 7); 2216 workaround = ALIGN8; 2217 continue; 2218 } 2219 2220 /* Nothing left to try. Arrange to return as if we've consumed 2221 the entire input section. Hopefully we'll get valid info from 2222 the other of .debug_frame/.eh_frame. */ 2223 workaround = FAIL; 2224 ret = unit->dwarf_frame_buffer + unit->dwarf_frame_size; 2225 break; 2226 } 2227 2228 switch (workaround) 2229 { 2230 case NONE: 2231 break; 2232 2233 case ALIGN4: 2234 complaint (&symfile_complaints, _("\ 2235 Corrupt data in %s:%s; align 4 workaround apparently succeeded"), 2236 unit->dwarf_frame_section->owner->filename, 2237 unit->dwarf_frame_section->name); 2238 break; 2239 2240 case ALIGN8: 2241 complaint (&symfile_complaints, _("\ 2242 Corrupt data in %s:%s; align 8 workaround apparently succeeded"), 2243 unit->dwarf_frame_section->owner->filename, 2244 unit->dwarf_frame_section->name); 2245 break; 2246 2247 default: 2248 complaint (&symfile_complaints, 2249 _("Corrupt data in %s:%s"), 2250 unit->dwarf_frame_section->owner->filename, 2251 unit->dwarf_frame_section->name); 2252 break; 2253 } 2254 2255 return ret; 2256 } 2257 2258 static int 2259 qsort_fde_cmp (const void *a, const void *b) 2260 { 2261 struct dwarf2_fde *aa = *(struct dwarf2_fde **)a; 2262 struct dwarf2_fde *bb = *(struct dwarf2_fde **)b; 2263 2264 if (aa->initial_location == bb->initial_location) 2265 { 2266 if (aa->address_range != bb->address_range 2267 && aa->eh_frame_p == 0 && bb->eh_frame_p == 0) 2268 /* Linker bug, e.g. gold/10400. 2269 Work around it by keeping stable sort order. */ 2270 return (a < b) ? -1 : 1; 2271 else 2272 /* Put eh_frame entries after debug_frame ones. */ 2273 return aa->eh_frame_p - bb->eh_frame_p; 2274 } 2275 2276 return (aa->initial_location < bb->initial_location) ? -1 : 1; 2277 } 2278 2279 void 2280 dwarf2_build_frame_info (struct objfile *objfile) 2281 { 2282 struct comp_unit *unit; 2283 gdb_byte *frame_ptr; 2284 struct dwarf2_cie_table cie_table; 2285 struct dwarf2_fde_table fde_table; 2286 struct dwarf2_fde_table *fde_table2; 2287 volatile struct gdb_exception e; 2288 2289 cie_table.num_entries = 0; 2290 cie_table.entries = NULL; 2291 2292 fde_table.num_entries = 0; 2293 fde_table.entries = NULL; 2294 2295 /* Build a minimal decoding of the DWARF2 compilation unit. */ 2296 unit = (struct comp_unit *) obstack_alloc (&objfile->objfile_obstack, 2297 sizeof (struct comp_unit)); 2298 unit->abfd = objfile->obfd; 2299 unit->objfile = objfile; 2300 unit->dbase = 0; 2301 unit->tbase = 0; 2302 2303 if (objfile->separate_debug_objfile_backlink == NULL) 2304 { 2305 /* Do not read .eh_frame from separate file as they must be also 2306 present in the main file. */ 2307 dwarf2_get_section_info (objfile, DWARF2_EH_FRAME, 2308 &unit->dwarf_frame_section, 2309 &unit->dwarf_frame_buffer, 2310 &unit->dwarf_frame_size); 2311 if (unit->dwarf_frame_size) 2312 { 2313 asection *got, *txt; 2314 2315 /* FIXME: kettenis/20030602: This is the DW_EH_PE_datarel base 2316 that is used for the i386/amd64 target, which currently is 2317 the only target in GCC that supports/uses the 2318 DW_EH_PE_datarel encoding. */ 2319 got = bfd_get_section_by_name (unit->abfd, ".got"); 2320 if (got) 2321 unit->dbase = got->vma; 2322 2323 /* GCC emits the DW_EH_PE_textrel encoding type on sh and ia64 2324 so far. */ 2325 txt = bfd_get_section_by_name (unit->abfd, ".text"); 2326 if (txt) 2327 unit->tbase = txt->vma; 2328 2329 TRY_CATCH (e, RETURN_MASK_ERROR) 2330 { 2331 frame_ptr = unit->dwarf_frame_buffer; 2332 while (frame_ptr < unit->dwarf_frame_buffer + unit->dwarf_frame_size) 2333 frame_ptr = decode_frame_entry (unit, frame_ptr, 1, 2334 &cie_table, &fde_table, 2335 EH_CIE_OR_FDE_TYPE_ID); 2336 } 2337 2338 if (e.reason < 0) 2339 { 2340 warning (_("skipping .eh_frame info of %s: %s"), 2341 objfile->name, e.message); 2342 2343 if (fde_table.num_entries != 0) 2344 { 2345 xfree (fde_table.entries); 2346 fde_table.entries = NULL; 2347 fde_table.num_entries = 0; 2348 } 2349 /* The cie_table is discarded by the next if. */ 2350 } 2351 2352 if (cie_table.num_entries != 0) 2353 { 2354 /* Reinit cie_table: debug_frame has different CIEs. */ 2355 xfree (cie_table.entries); 2356 cie_table.num_entries = 0; 2357 cie_table.entries = NULL; 2358 } 2359 } 2360 } 2361 2362 dwarf2_get_section_info (objfile, DWARF2_DEBUG_FRAME, 2363 &unit->dwarf_frame_section, 2364 &unit->dwarf_frame_buffer, 2365 &unit->dwarf_frame_size); 2366 if (unit->dwarf_frame_size) 2367 { 2368 int num_old_fde_entries = fde_table.num_entries; 2369 2370 TRY_CATCH (e, RETURN_MASK_ERROR) 2371 { 2372 frame_ptr = unit->dwarf_frame_buffer; 2373 while (frame_ptr < unit->dwarf_frame_buffer + unit->dwarf_frame_size) 2374 frame_ptr = decode_frame_entry (unit, frame_ptr, 0, 2375 &cie_table, &fde_table, 2376 EH_CIE_OR_FDE_TYPE_ID); 2377 } 2378 if (e.reason < 0) 2379 { 2380 warning (_("skipping .debug_frame info of %s: %s"), 2381 objfile->name, e.message); 2382 2383 if (fde_table.num_entries != 0) 2384 { 2385 fde_table.num_entries = num_old_fde_entries; 2386 if (num_old_fde_entries == 0) 2387 { 2388 xfree (fde_table.entries); 2389 fde_table.entries = NULL; 2390 } 2391 else 2392 { 2393 fde_table.entries = xrealloc (fde_table.entries, 2394 fde_table.num_entries * 2395 sizeof (fde_table.entries[0])); 2396 } 2397 } 2398 fde_table.num_entries = num_old_fde_entries; 2399 /* The cie_table is discarded by the next if. */ 2400 } 2401 } 2402 2403 /* Discard the cie_table, it is no longer needed. */ 2404 if (cie_table.num_entries != 0) 2405 { 2406 xfree (cie_table.entries); 2407 cie_table.entries = NULL; /* Paranoia. */ 2408 cie_table.num_entries = 0; /* Paranoia. */ 2409 } 2410 2411 /* Copy fde_table to obstack: it is needed at runtime. */ 2412 fde_table2 = (struct dwarf2_fde_table *) 2413 obstack_alloc (&objfile->objfile_obstack, sizeof (*fde_table2)); 2414 2415 if (fde_table.num_entries == 0) 2416 { 2417 fde_table2->entries = NULL; 2418 fde_table2->num_entries = 0; 2419 } 2420 else 2421 { 2422 struct dwarf2_fde *fde_prev = NULL; 2423 struct dwarf2_fde *first_non_zero_fde = NULL; 2424 int i; 2425 2426 /* Prepare FDE table for lookups. */ 2427 qsort (fde_table.entries, fde_table.num_entries, 2428 sizeof (fde_table.entries[0]), qsort_fde_cmp); 2429 2430 /* Check for leftovers from --gc-sections. The GNU linker sets 2431 the relevant symbols to zero, but doesn't zero the FDE *end* 2432 ranges because there's no relocation there. It's (offset, 2433 length), not (start, end). On targets where address zero is 2434 just another valid address this can be a problem, since the 2435 FDEs appear to be non-empty in the output --- we could pick 2436 out the wrong FDE. To work around this, when overlaps are 2437 detected, we prefer FDEs that do not start at zero. 2438 2439 Start by finding the first FDE with non-zero start. Below 2440 we'll discard all FDEs that start at zero and overlap this 2441 one. */ 2442 for (i = 0; i < fde_table.num_entries; i++) 2443 { 2444 struct dwarf2_fde *fde = fde_table.entries[i]; 2445 2446 if (fde->initial_location != 0) 2447 { 2448 first_non_zero_fde = fde; 2449 break; 2450 } 2451 } 2452 2453 /* Since we'll be doing bsearch, squeeze out identical (except 2454 for eh_frame_p) fde entries so bsearch result is predictable. 2455 Also discard leftovers from --gc-sections. */ 2456 fde_table2->num_entries = 0; 2457 for (i = 0; i < fde_table.num_entries; i++) 2458 { 2459 struct dwarf2_fde *fde = fde_table.entries[i]; 2460 2461 if (fde->initial_location == 0 2462 && first_non_zero_fde != NULL 2463 && (first_non_zero_fde->initial_location 2464 < fde->initial_location + fde->address_range)) 2465 continue; 2466 2467 if (fde_prev != NULL 2468 && fde_prev->initial_location == fde->initial_location) 2469 continue; 2470 2471 obstack_grow (&objfile->objfile_obstack, &fde_table.entries[i], 2472 sizeof (fde_table.entries[0])); 2473 ++fde_table2->num_entries; 2474 fde_prev = fde; 2475 } 2476 fde_table2->entries = obstack_finish (&objfile->objfile_obstack); 2477 2478 /* Discard the original fde_table. */ 2479 xfree (fde_table.entries); 2480 } 2481 2482 set_objfile_data (objfile, dwarf2_frame_objfile_data, fde_table2); 2483 } 2484 2485 /* Provide a prototype to silence -Wmissing-prototypes. */ 2486 void _initialize_dwarf2_frame (void); 2487 2488 void 2489 _initialize_dwarf2_frame (void) 2490 { 2491 dwarf2_frame_data = gdbarch_data_register_pre_init (dwarf2_frame_init); 2492 dwarf2_frame_objfile_data = register_objfile_data (); 2493 } 2494