1 /* Frame unwinder for frames with DWARF Call Frame Information. 2 3 Copyright (C) 2003-2013 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 const gdb_byte *initial_instructions; 72 const 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 const gdb_byte *instructions; 120 const 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 ctx_no_get_addr_index 359 }; 360 361 static CORE_ADDR 362 execute_stack_op (const gdb_byte *exp, ULONGEST len, int addr_size, 363 CORE_ADDR offset, struct frame_info *this_frame, 364 CORE_ADDR initial, int initial_in_stack_memory) 365 { 366 struct dwarf_expr_context *ctx; 367 CORE_ADDR result; 368 struct cleanup *old_chain; 369 370 ctx = new_dwarf_expr_context (); 371 old_chain = make_cleanup_free_dwarf_expr_context (ctx); 372 make_cleanup_value_free_to_mark (value_mark ()); 373 374 ctx->gdbarch = get_frame_arch (this_frame); 375 ctx->addr_size = addr_size; 376 ctx->ref_addr_size = -1; 377 ctx->offset = offset; 378 ctx->baton = this_frame; 379 ctx->funcs = &dwarf2_frame_ctx_funcs; 380 381 dwarf_expr_push_address (ctx, initial, initial_in_stack_memory); 382 dwarf_expr_eval (ctx, exp, len); 383 384 if (ctx->location == DWARF_VALUE_MEMORY) 385 result = dwarf_expr_fetch_address (ctx, 0); 386 else if (ctx->location == DWARF_VALUE_REGISTER) 387 result = read_reg (this_frame, value_as_long (dwarf_expr_fetch (ctx, 0))); 388 else 389 { 390 /* This is actually invalid DWARF, but if we ever do run across 391 it somehow, we might as well support it. So, instead, report 392 it as unimplemented. */ 393 error (_("\ 394 Not implemented: computing unwound register using explicit value operator")); 395 } 396 397 do_cleanups (old_chain); 398 399 return result; 400 } 401 402 403 /* Execute FDE program from INSN_PTR possibly up to INSN_END or up to inferior 404 PC. Modify FS state accordingly. Return current INSN_PTR where the 405 execution has stopped, one can resume it on the next call. */ 406 407 static const gdb_byte * 408 execute_cfa_program (struct dwarf2_fde *fde, const gdb_byte *insn_ptr, 409 const gdb_byte *insn_end, struct gdbarch *gdbarch, 410 CORE_ADDR pc, struct dwarf2_frame_state *fs) 411 { 412 int eh_frame_p = fde->eh_frame_p; 413 int bytes_read; 414 enum bfd_endian byte_order = gdbarch_byte_order (gdbarch); 415 416 while (insn_ptr < insn_end && fs->pc <= pc) 417 { 418 gdb_byte insn = *insn_ptr++; 419 uint64_t utmp, reg; 420 int64_t offset; 421 422 if ((insn & 0xc0) == DW_CFA_advance_loc) 423 fs->pc += (insn & 0x3f) * fs->code_align; 424 else if ((insn & 0xc0) == DW_CFA_offset) 425 { 426 reg = insn & 0x3f; 427 reg = dwarf2_frame_adjust_regnum (gdbarch, reg, eh_frame_p); 428 insn_ptr = safe_read_uleb128 (insn_ptr, insn_end, &utmp); 429 offset = utmp * fs->data_align; 430 dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1); 431 fs->regs.reg[reg].how = DWARF2_FRAME_REG_SAVED_OFFSET; 432 fs->regs.reg[reg].loc.offset = offset; 433 } 434 else if ((insn & 0xc0) == DW_CFA_restore) 435 { 436 reg = insn & 0x3f; 437 dwarf2_restore_rule (gdbarch, reg, fs, eh_frame_p); 438 } 439 else 440 { 441 switch (insn) 442 { 443 case DW_CFA_set_loc: 444 fs->pc = read_encoded_value (fde->cie->unit, fde->cie->encoding, 445 fde->cie->ptr_size, insn_ptr, 446 &bytes_read, fde->initial_location); 447 /* Apply the objfile offset for relocatable objects. */ 448 fs->pc += ANOFFSET (fde->cie->unit->objfile->section_offsets, 449 SECT_OFF_TEXT (fde->cie->unit->objfile)); 450 insn_ptr += bytes_read; 451 break; 452 453 case DW_CFA_advance_loc1: 454 utmp = extract_unsigned_integer (insn_ptr, 1, byte_order); 455 fs->pc += utmp * fs->code_align; 456 insn_ptr++; 457 break; 458 case DW_CFA_advance_loc2: 459 utmp = extract_unsigned_integer (insn_ptr, 2, byte_order); 460 fs->pc += utmp * fs->code_align; 461 insn_ptr += 2; 462 break; 463 case DW_CFA_advance_loc4: 464 utmp = extract_unsigned_integer (insn_ptr, 4, byte_order); 465 fs->pc += utmp * fs->code_align; 466 insn_ptr += 4; 467 break; 468 469 case DW_CFA_offset_extended: 470 insn_ptr = safe_read_uleb128 (insn_ptr, insn_end, ®); 471 reg = dwarf2_frame_adjust_regnum (gdbarch, reg, eh_frame_p); 472 insn_ptr = safe_read_uleb128 (insn_ptr, insn_end, &utmp); 473 offset = utmp * fs->data_align; 474 dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1); 475 fs->regs.reg[reg].how = DWARF2_FRAME_REG_SAVED_OFFSET; 476 fs->regs.reg[reg].loc.offset = offset; 477 break; 478 479 case DW_CFA_restore_extended: 480 insn_ptr = safe_read_uleb128 (insn_ptr, insn_end, ®); 481 dwarf2_restore_rule (gdbarch, reg, fs, eh_frame_p); 482 break; 483 484 case DW_CFA_undefined: 485 insn_ptr = safe_read_uleb128 (insn_ptr, insn_end, ®); 486 reg = dwarf2_frame_adjust_regnum (gdbarch, reg, eh_frame_p); 487 dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1); 488 fs->regs.reg[reg].how = DWARF2_FRAME_REG_UNDEFINED; 489 break; 490 491 case DW_CFA_same_value: 492 insn_ptr = safe_read_uleb128 (insn_ptr, insn_end, ®); 493 reg = dwarf2_frame_adjust_regnum (gdbarch, reg, eh_frame_p); 494 dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1); 495 fs->regs.reg[reg].how = DWARF2_FRAME_REG_SAME_VALUE; 496 break; 497 498 case DW_CFA_register: 499 insn_ptr = safe_read_uleb128 (insn_ptr, insn_end, ®); 500 reg = dwarf2_frame_adjust_regnum (gdbarch, reg, eh_frame_p); 501 insn_ptr = safe_read_uleb128 (insn_ptr, insn_end, &utmp); 502 utmp = dwarf2_frame_adjust_regnum (gdbarch, utmp, eh_frame_p); 503 dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1); 504 fs->regs.reg[reg].how = DWARF2_FRAME_REG_SAVED_REG; 505 fs->regs.reg[reg].loc.reg = utmp; 506 break; 507 508 case DW_CFA_remember_state: 509 { 510 struct dwarf2_frame_state_reg_info *new_rs; 511 512 new_rs = XMALLOC (struct dwarf2_frame_state_reg_info); 513 *new_rs = fs->regs; 514 fs->regs.reg = dwarf2_frame_state_copy_regs (&fs->regs); 515 fs->regs.prev = new_rs; 516 } 517 break; 518 519 case DW_CFA_restore_state: 520 { 521 struct dwarf2_frame_state_reg_info *old_rs = fs->regs.prev; 522 523 if (old_rs == NULL) 524 { 525 complaint (&symfile_complaints, _("\ 526 bad CFI data; mismatched DW_CFA_restore_state at %s"), 527 paddress (gdbarch, fs->pc)); 528 } 529 else 530 { 531 xfree (fs->regs.reg); 532 fs->regs = *old_rs; 533 xfree (old_rs); 534 } 535 } 536 break; 537 538 case DW_CFA_def_cfa: 539 insn_ptr = safe_read_uleb128 (insn_ptr, insn_end, ®); 540 fs->regs.cfa_reg = reg; 541 insn_ptr = safe_read_uleb128 (insn_ptr, insn_end, &utmp); 542 543 if (fs->armcc_cfa_offsets_sf) 544 utmp *= fs->data_align; 545 546 fs->regs.cfa_offset = utmp; 547 fs->regs.cfa_how = CFA_REG_OFFSET; 548 break; 549 550 case DW_CFA_def_cfa_register: 551 insn_ptr = safe_read_uleb128 (insn_ptr, insn_end, ®); 552 fs->regs.cfa_reg = dwarf2_frame_adjust_regnum (gdbarch, reg, 553 eh_frame_p); 554 fs->regs.cfa_how = CFA_REG_OFFSET; 555 break; 556 557 case DW_CFA_def_cfa_offset: 558 insn_ptr = safe_read_uleb128 (insn_ptr, insn_end, &utmp); 559 560 if (fs->armcc_cfa_offsets_sf) 561 utmp *= fs->data_align; 562 563 fs->regs.cfa_offset = utmp; 564 /* cfa_how deliberately not set. */ 565 break; 566 567 case DW_CFA_nop: 568 break; 569 570 case DW_CFA_def_cfa_expression: 571 insn_ptr = safe_read_uleb128 (insn_ptr, insn_end, &utmp); 572 fs->regs.cfa_exp_len = utmp; 573 fs->regs.cfa_exp = insn_ptr; 574 fs->regs.cfa_how = CFA_EXP; 575 insn_ptr += fs->regs.cfa_exp_len; 576 break; 577 578 case DW_CFA_expression: 579 insn_ptr = safe_read_uleb128 (insn_ptr, insn_end, ®); 580 reg = dwarf2_frame_adjust_regnum (gdbarch, reg, eh_frame_p); 581 dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1); 582 insn_ptr = safe_read_uleb128 (insn_ptr, insn_end, &utmp); 583 fs->regs.reg[reg].loc.exp = insn_ptr; 584 fs->regs.reg[reg].exp_len = utmp; 585 fs->regs.reg[reg].how = DWARF2_FRAME_REG_SAVED_EXP; 586 insn_ptr += utmp; 587 break; 588 589 case DW_CFA_offset_extended_sf: 590 insn_ptr = safe_read_uleb128 (insn_ptr, insn_end, ®); 591 reg = dwarf2_frame_adjust_regnum (gdbarch, reg, eh_frame_p); 592 insn_ptr = safe_read_sleb128 (insn_ptr, insn_end, &offset); 593 offset *= fs->data_align; 594 dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1); 595 fs->regs.reg[reg].how = DWARF2_FRAME_REG_SAVED_OFFSET; 596 fs->regs.reg[reg].loc.offset = offset; 597 break; 598 599 case DW_CFA_val_offset: 600 insn_ptr = safe_read_uleb128 (insn_ptr, insn_end, ®); 601 dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1); 602 insn_ptr = safe_read_uleb128 (insn_ptr, insn_end, &utmp); 603 offset = utmp * fs->data_align; 604 fs->regs.reg[reg].how = DWARF2_FRAME_REG_SAVED_VAL_OFFSET; 605 fs->regs.reg[reg].loc.offset = offset; 606 break; 607 608 case DW_CFA_val_offset_sf: 609 insn_ptr = safe_read_uleb128 (insn_ptr, insn_end, ®); 610 dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1); 611 insn_ptr = safe_read_sleb128 (insn_ptr, insn_end, &offset); 612 offset *= fs->data_align; 613 fs->regs.reg[reg].how = DWARF2_FRAME_REG_SAVED_VAL_OFFSET; 614 fs->regs.reg[reg].loc.offset = offset; 615 break; 616 617 case DW_CFA_val_expression: 618 insn_ptr = safe_read_uleb128 (insn_ptr, insn_end, ®); 619 dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1); 620 insn_ptr = safe_read_uleb128 (insn_ptr, insn_end, &utmp); 621 fs->regs.reg[reg].loc.exp = insn_ptr; 622 fs->regs.reg[reg].exp_len = utmp; 623 fs->regs.reg[reg].how = DWARF2_FRAME_REG_SAVED_VAL_EXP; 624 insn_ptr += utmp; 625 break; 626 627 case DW_CFA_def_cfa_sf: 628 insn_ptr = safe_read_uleb128 (insn_ptr, insn_end, ®); 629 fs->regs.cfa_reg = dwarf2_frame_adjust_regnum (gdbarch, reg, 630 eh_frame_p); 631 insn_ptr = safe_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 = safe_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 = safe_read_uleb128 (insn_ptr, insn_end, &utmp); 670 break; 671 672 case DW_CFA_GNU_negative_offset_extended: 673 insn_ptr = safe_read_uleb128 (insn_ptr, insn_end, ®); 674 reg = dwarf2_frame_adjust_regnum (gdbarch, reg, eh_frame_p); 675 insn_ptr = safe_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 struct dwarf2_fde *fde; 892 CORE_ADDR text_offset; 893 struct dwarf2_frame_state fs; 894 int addr_size; 895 896 memset (&fs, 0, sizeof (struct dwarf2_frame_state)); 897 898 fs.pc = pc; 899 900 /* Find the correct FDE. */ 901 fde = dwarf2_frame_find_fde (&fs.pc, &text_offset); 902 if (fde == NULL) 903 error (_("Could not compute CFA; needed to translate this expression")); 904 905 /* Extract any interesting information from the CIE. */ 906 fs.data_align = fde->cie->data_alignment_factor; 907 fs.code_align = fde->cie->code_alignment_factor; 908 fs.retaddr_column = fde->cie->return_address_register; 909 addr_size = fde->cie->addr_size; 910 911 /* Check for "quirks" - known bugs in producers. */ 912 dwarf2_frame_find_quirks (&fs, fde); 913 914 /* First decode all the insns in the CIE. */ 915 execute_cfa_program (fde, fde->cie->initial_instructions, 916 fde->cie->end, gdbarch, pc, &fs); 917 918 /* Save the initialized register set. */ 919 fs.initial = fs.regs; 920 fs.initial.reg = dwarf2_frame_state_copy_regs (&fs.regs); 921 922 /* Then decode the insns in the FDE up to our target PC. */ 923 execute_cfa_program (fde, fde->instructions, fde->end, gdbarch, pc, &fs); 924 925 /* Calculate the CFA. */ 926 switch (fs.regs.cfa_how) 927 { 928 case CFA_REG_OFFSET: 929 { 930 int regnum = gdbarch_dwarf2_reg_to_regnum (gdbarch, fs.regs.cfa_reg); 931 932 if (regnum == -1) 933 error (_("Unable to access DWARF register number %d"), 934 (int) fs.regs.cfa_reg); /* FIXME */ 935 ax_reg (expr, regnum); 936 937 if (fs.regs.cfa_offset != 0) 938 { 939 if (fs.armcc_cfa_offsets_reversed) 940 ax_const_l (expr, -fs.regs.cfa_offset); 941 else 942 ax_const_l (expr, fs.regs.cfa_offset); 943 ax_simple (expr, aop_add); 944 } 945 } 946 break; 947 948 case CFA_EXP: 949 ax_const_l (expr, text_offset); 950 dwarf2_compile_expr_to_ax (expr, loc, gdbarch, addr_size, 951 fs.regs.cfa_exp, 952 fs.regs.cfa_exp + fs.regs.cfa_exp_len, 953 data); 954 break; 955 956 default: 957 internal_error (__FILE__, __LINE__, _("Unknown CFA rule.")); 958 } 959 } 960 961 962 struct dwarf2_frame_cache 963 { 964 /* DWARF Call Frame Address. */ 965 CORE_ADDR cfa; 966 967 /* Set if the return address column was marked as unavailable 968 (required non-collected memory or registers to compute). */ 969 int unavailable_retaddr; 970 971 /* Set if the return address column was marked as undefined. */ 972 int undefined_retaddr; 973 974 /* Saved registers, indexed by GDB register number, not by DWARF 975 register number. */ 976 struct dwarf2_frame_state_reg *reg; 977 978 /* Return address register. */ 979 struct dwarf2_frame_state_reg retaddr_reg; 980 981 /* Target address size in bytes. */ 982 int addr_size; 983 984 /* The .text offset. */ 985 CORE_ADDR text_offset; 986 987 /* If not NULL then this frame is the bottom frame of a TAILCALL_FRAME 988 sequence. If NULL then it is a normal case with no TAILCALL_FRAME 989 involved. Non-bottom frames of a virtual tail call frames chain use 990 dwarf2_tailcall_frame_unwind unwinder so this field does not apply for 991 them. */ 992 void *tailcall_cache; 993 }; 994 995 /* A cleanup that sets a pointer to NULL. */ 996 997 static void 998 clear_pointer_cleanup (void *arg) 999 { 1000 void **ptr = arg; 1001 1002 *ptr = NULL; 1003 } 1004 1005 static struct dwarf2_frame_cache * 1006 dwarf2_frame_cache (struct frame_info *this_frame, void **this_cache) 1007 { 1008 struct cleanup *reset_cache_cleanup, *old_chain; 1009 struct gdbarch *gdbarch = get_frame_arch (this_frame); 1010 const int num_regs = gdbarch_num_regs (gdbarch) 1011 + gdbarch_num_pseudo_regs (gdbarch); 1012 struct dwarf2_frame_cache *cache; 1013 struct dwarf2_frame_state *fs; 1014 struct dwarf2_fde *fde; 1015 volatile struct gdb_exception ex; 1016 CORE_ADDR entry_pc; 1017 LONGEST entry_cfa_sp_offset; 1018 int entry_cfa_sp_offset_p = 0; 1019 const gdb_byte *instr; 1020 1021 if (*this_cache) 1022 return *this_cache; 1023 1024 /* Allocate a new cache. */ 1025 cache = FRAME_OBSTACK_ZALLOC (struct dwarf2_frame_cache); 1026 cache->reg = FRAME_OBSTACK_CALLOC (num_regs, struct dwarf2_frame_state_reg); 1027 *this_cache = cache; 1028 reset_cache_cleanup = make_cleanup (clear_pointer_cleanup, this_cache); 1029 1030 /* Allocate and initialize the frame state. */ 1031 fs = XZALLOC (struct dwarf2_frame_state); 1032 old_chain = make_cleanup (dwarf2_frame_state_free, fs); 1033 1034 /* Unwind the PC. 1035 1036 Note that if the next frame is never supposed to return (i.e. a call 1037 to abort), the compiler might optimize away the instruction at 1038 its return address. As a result the return address will 1039 point at some random instruction, and the CFI for that 1040 instruction is probably worthless to us. GCC's unwinder solves 1041 this problem by substracting 1 from the return address to get an 1042 address in the middle of a presumed call instruction (or the 1043 instruction in the associated delay slot). This should only be 1044 done for "normal" frames and not for resume-type frames (signal 1045 handlers, sentinel frames, dummy frames). The function 1046 get_frame_address_in_block does just this. It's not clear how 1047 reliable the method is though; there is the potential for the 1048 register state pre-call being different to that on return. */ 1049 fs->pc = get_frame_address_in_block (this_frame); 1050 1051 /* Find the correct FDE. */ 1052 fde = dwarf2_frame_find_fde (&fs->pc, &cache->text_offset); 1053 gdb_assert (fde != NULL); 1054 1055 /* Extract any interesting information from the CIE. */ 1056 fs->data_align = fde->cie->data_alignment_factor; 1057 fs->code_align = fde->cie->code_alignment_factor; 1058 fs->retaddr_column = fde->cie->return_address_register; 1059 cache->addr_size = fde->cie->addr_size; 1060 1061 /* Check for "quirks" - known bugs in producers. */ 1062 dwarf2_frame_find_quirks (fs, fde); 1063 1064 /* First decode all the insns in the CIE. */ 1065 execute_cfa_program (fde, fde->cie->initial_instructions, 1066 fde->cie->end, gdbarch, 1067 get_frame_address_in_block (this_frame), fs); 1068 1069 /* Save the initialized register set. */ 1070 fs->initial = fs->regs; 1071 fs->initial.reg = dwarf2_frame_state_copy_regs (&fs->regs); 1072 1073 if (get_frame_func_if_available (this_frame, &entry_pc)) 1074 { 1075 /* Decode the insns in the FDE up to the entry PC. */ 1076 instr = execute_cfa_program (fde, fde->instructions, fde->end, gdbarch, 1077 entry_pc, fs); 1078 1079 if (fs->regs.cfa_how == CFA_REG_OFFSET 1080 && (gdbarch_dwarf2_reg_to_regnum (gdbarch, fs->regs.cfa_reg) 1081 == gdbarch_sp_regnum (gdbarch))) 1082 { 1083 entry_cfa_sp_offset = fs->regs.cfa_offset; 1084 entry_cfa_sp_offset_p = 1; 1085 } 1086 } 1087 else 1088 instr = fde->instructions; 1089 1090 /* Then decode the insns in the FDE up to our target PC. */ 1091 execute_cfa_program (fde, instr, fde->end, gdbarch, 1092 get_frame_address_in_block (this_frame), fs); 1093 1094 TRY_CATCH (ex, RETURN_MASK_ERROR) 1095 { 1096 /* Calculate the CFA. */ 1097 switch (fs->regs.cfa_how) 1098 { 1099 case CFA_REG_OFFSET: 1100 cache->cfa = read_reg (this_frame, fs->regs.cfa_reg); 1101 if (fs->armcc_cfa_offsets_reversed) 1102 cache->cfa -= fs->regs.cfa_offset; 1103 else 1104 cache->cfa += fs->regs.cfa_offset; 1105 break; 1106 1107 case CFA_EXP: 1108 cache->cfa = 1109 execute_stack_op (fs->regs.cfa_exp, fs->regs.cfa_exp_len, 1110 cache->addr_size, cache->text_offset, 1111 this_frame, 0, 0); 1112 break; 1113 1114 default: 1115 internal_error (__FILE__, __LINE__, _("Unknown CFA rule.")); 1116 } 1117 } 1118 if (ex.reason < 0) 1119 { 1120 if (ex.error == NOT_AVAILABLE_ERROR) 1121 { 1122 cache->unavailable_retaddr = 1; 1123 do_cleanups (old_chain); 1124 discard_cleanups (reset_cache_cleanup); 1125 return cache; 1126 } 1127 1128 throw_exception (ex); 1129 } 1130 1131 /* Initialize the register state. */ 1132 { 1133 int regnum; 1134 1135 for (regnum = 0; regnum < num_regs; regnum++) 1136 dwarf2_frame_init_reg (gdbarch, regnum, &cache->reg[regnum], this_frame); 1137 } 1138 1139 /* Go through the DWARF2 CFI generated table and save its register 1140 location information in the cache. Note that we don't skip the 1141 return address column; it's perfectly all right for it to 1142 correspond to a real register. If it doesn't correspond to a 1143 real register, or if we shouldn't treat it as such, 1144 gdbarch_dwarf2_reg_to_regnum should be defined to return a number outside 1145 the range [0, gdbarch_num_regs). */ 1146 { 1147 int column; /* CFI speak for "register number". */ 1148 1149 for (column = 0; column < fs->regs.num_regs; column++) 1150 { 1151 /* Use the GDB register number as the destination index. */ 1152 int regnum = gdbarch_dwarf2_reg_to_regnum (gdbarch, column); 1153 1154 /* If there's no corresponding GDB register, ignore it. */ 1155 if (regnum < 0 || regnum >= num_regs) 1156 continue; 1157 1158 /* NOTE: cagney/2003-09-05: CFI should specify the disposition 1159 of all debug info registers. If it doesn't, complain (but 1160 not too loudly). It turns out that GCC assumes that an 1161 unspecified register implies "same value" when CFI (draft 1162 7) specifies nothing at all. Such a register could equally 1163 be interpreted as "undefined". Also note that this check 1164 isn't sufficient; it only checks that all registers in the 1165 range [0 .. max column] are specified, and won't detect 1166 problems when a debug info register falls outside of the 1167 table. We need a way of iterating through all the valid 1168 DWARF2 register numbers. */ 1169 if (fs->regs.reg[column].how == DWARF2_FRAME_REG_UNSPECIFIED) 1170 { 1171 if (cache->reg[regnum].how == DWARF2_FRAME_REG_UNSPECIFIED) 1172 complaint (&symfile_complaints, _("\ 1173 incomplete CFI data; unspecified registers (e.g., %s) at %s"), 1174 gdbarch_register_name (gdbarch, regnum), 1175 paddress (gdbarch, fs->pc)); 1176 } 1177 else 1178 cache->reg[regnum] = fs->regs.reg[column]; 1179 } 1180 } 1181 1182 /* Eliminate any DWARF2_FRAME_REG_RA rules, and save the information 1183 we need for evaluating DWARF2_FRAME_REG_RA_OFFSET rules. */ 1184 { 1185 int regnum; 1186 1187 for (regnum = 0; regnum < num_regs; regnum++) 1188 { 1189 if (cache->reg[regnum].how == DWARF2_FRAME_REG_RA 1190 || cache->reg[regnum].how == DWARF2_FRAME_REG_RA_OFFSET) 1191 { 1192 struct dwarf2_frame_state_reg *retaddr_reg = 1193 &fs->regs.reg[fs->retaddr_column]; 1194 1195 /* It seems rather bizarre to specify an "empty" column as 1196 the return adress column. However, this is exactly 1197 what GCC does on some targets. It turns out that GCC 1198 assumes that the return address can be found in the 1199 register corresponding to the return address column. 1200 Incidentally, that's how we should treat a return 1201 address column specifying "same value" too. */ 1202 if (fs->retaddr_column < fs->regs.num_regs 1203 && retaddr_reg->how != DWARF2_FRAME_REG_UNSPECIFIED 1204 && retaddr_reg->how != DWARF2_FRAME_REG_SAME_VALUE) 1205 { 1206 if (cache->reg[regnum].how == DWARF2_FRAME_REG_RA) 1207 cache->reg[regnum] = *retaddr_reg; 1208 else 1209 cache->retaddr_reg = *retaddr_reg; 1210 } 1211 else 1212 { 1213 if (cache->reg[regnum].how == DWARF2_FRAME_REG_RA) 1214 { 1215 cache->reg[regnum].loc.reg = fs->retaddr_column; 1216 cache->reg[regnum].how = DWARF2_FRAME_REG_SAVED_REG; 1217 } 1218 else 1219 { 1220 cache->retaddr_reg.loc.reg = fs->retaddr_column; 1221 cache->retaddr_reg.how = DWARF2_FRAME_REG_SAVED_REG; 1222 } 1223 } 1224 } 1225 } 1226 } 1227 1228 if (fs->retaddr_column < fs->regs.num_regs 1229 && fs->regs.reg[fs->retaddr_column].how == DWARF2_FRAME_REG_UNDEFINED) 1230 cache->undefined_retaddr = 1; 1231 1232 do_cleanups (old_chain); 1233 1234 /* Try to find a virtual tail call frames chain with bottom (callee) frame 1235 starting at THIS_FRAME. */ 1236 dwarf2_tailcall_sniffer_first (this_frame, &cache->tailcall_cache, 1237 (entry_cfa_sp_offset_p 1238 ? &entry_cfa_sp_offset : NULL)); 1239 1240 discard_cleanups (reset_cache_cleanup); 1241 return cache; 1242 } 1243 1244 static enum unwind_stop_reason 1245 dwarf2_frame_unwind_stop_reason (struct frame_info *this_frame, 1246 void **this_cache) 1247 { 1248 struct dwarf2_frame_cache *cache 1249 = dwarf2_frame_cache (this_frame, this_cache); 1250 1251 if (cache->unavailable_retaddr) 1252 return UNWIND_UNAVAILABLE; 1253 1254 if (cache->undefined_retaddr) 1255 return UNWIND_OUTERMOST; 1256 1257 return UNWIND_NO_REASON; 1258 } 1259 1260 static void 1261 dwarf2_frame_this_id (struct frame_info *this_frame, void **this_cache, 1262 struct frame_id *this_id) 1263 { 1264 struct dwarf2_frame_cache *cache = 1265 dwarf2_frame_cache (this_frame, this_cache); 1266 1267 if (cache->unavailable_retaddr) 1268 return; 1269 1270 if (cache->undefined_retaddr) 1271 return; 1272 1273 (*this_id) = frame_id_build (cache->cfa, get_frame_func (this_frame)); 1274 } 1275 1276 static struct value * 1277 dwarf2_frame_prev_register (struct frame_info *this_frame, void **this_cache, 1278 int regnum) 1279 { 1280 struct gdbarch *gdbarch = get_frame_arch (this_frame); 1281 struct dwarf2_frame_cache *cache = 1282 dwarf2_frame_cache (this_frame, this_cache); 1283 CORE_ADDR addr; 1284 int realnum; 1285 1286 /* Non-bottom frames of a virtual tail call frames chain use 1287 dwarf2_tailcall_frame_unwind unwinder so this code does not apply for 1288 them. If dwarf2_tailcall_prev_register_first does not have specific value 1289 unwind the register, tail call frames are assumed to have the register set 1290 of the top caller. */ 1291 if (cache->tailcall_cache) 1292 { 1293 struct value *val; 1294 1295 val = dwarf2_tailcall_prev_register_first (this_frame, 1296 &cache->tailcall_cache, 1297 regnum); 1298 if (val) 1299 return val; 1300 } 1301 1302 switch (cache->reg[regnum].how) 1303 { 1304 case DWARF2_FRAME_REG_UNDEFINED: 1305 /* If CFI explicitly specified that the value isn't defined, 1306 mark it as optimized away; the value isn't available. */ 1307 return frame_unwind_got_optimized (this_frame, regnum); 1308 1309 case DWARF2_FRAME_REG_SAVED_OFFSET: 1310 addr = cache->cfa + cache->reg[regnum].loc.offset; 1311 return frame_unwind_got_memory (this_frame, regnum, addr); 1312 1313 case DWARF2_FRAME_REG_SAVED_REG: 1314 realnum 1315 = gdbarch_dwarf2_reg_to_regnum (gdbarch, cache->reg[regnum].loc.reg); 1316 return frame_unwind_got_register (this_frame, regnum, realnum); 1317 1318 case DWARF2_FRAME_REG_SAVED_EXP: 1319 addr = execute_stack_op (cache->reg[regnum].loc.exp, 1320 cache->reg[regnum].exp_len, 1321 cache->addr_size, cache->text_offset, 1322 this_frame, cache->cfa, 1); 1323 return frame_unwind_got_memory (this_frame, regnum, addr); 1324 1325 case DWARF2_FRAME_REG_SAVED_VAL_OFFSET: 1326 addr = cache->cfa + cache->reg[regnum].loc.offset; 1327 return frame_unwind_got_constant (this_frame, regnum, addr); 1328 1329 case DWARF2_FRAME_REG_SAVED_VAL_EXP: 1330 addr = execute_stack_op (cache->reg[regnum].loc.exp, 1331 cache->reg[regnum].exp_len, 1332 cache->addr_size, cache->text_offset, 1333 this_frame, cache->cfa, 1); 1334 return frame_unwind_got_constant (this_frame, regnum, addr); 1335 1336 case DWARF2_FRAME_REG_UNSPECIFIED: 1337 /* GCC, in its infinite wisdom decided to not provide unwind 1338 information for registers that are "same value". Since 1339 DWARF2 (3 draft 7) doesn't define such behavior, said 1340 registers are actually undefined (which is different to CFI 1341 "undefined"). Code above issues a complaint about this. 1342 Here just fudge the books, assume GCC, and that the value is 1343 more inner on the stack. */ 1344 return frame_unwind_got_register (this_frame, regnum, regnum); 1345 1346 case DWARF2_FRAME_REG_SAME_VALUE: 1347 return frame_unwind_got_register (this_frame, regnum, regnum); 1348 1349 case DWARF2_FRAME_REG_CFA: 1350 return frame_unwind_got_address (this_frame, regnum, cache->cfa); 1351 1352 case DWARF2_FRAME_REG_CFA_OFFSET: 1353 addr = cache->cfa + cache->reg[regnum].loc.offset; 1354 return frame_unwind_got_address (this_frame, regnum, addr); 1355 1356 case DWARF2_FRAME_REG_RA_OFFSET: 1357 addr = cache->reg[regnum].loc.offset; 1358 regnum = gdbarch_dwarf2_reg_to_regnum 1359 (gdbarch, cache->retaddr_reg.loc.reg); 1360 addr += get_frame_register_unsigned (this_frame, regnum); 1361 return frame_unwind_got_address (this_frame, regnum, addr); 1362 1363 case DWARF2_FRAME_REG_FN: 1364 return cache->reg[regnum].loc.fn (this_frame, this_cache, regnum); 1365 1366 default: 1367 internal_error (__FILE__, __LINE__, _("Unknown register rule.")); 1368 } 1369 } 1370 1371 /* Proxy for tailcall_frame_dealloc_cache for bottom frame of a virtual tail 1372 call frames chain. */ 1373 1374 static void 1375 dwarf2_frame_dealloc_cache (struct frame_info *self, void *this_cache) 1376 { 1377 struct dwarf2_frame_cache *cache = dwarf2_frame_cache (self, &this_cache); 1378 1379 if (cache->tailcall_cache) 1380 dwarf2_tailcall_frame_unwind.dealloc_cache (self, cache->tailcall_cache); 1381 } 1382 1383 static int 1384 dwarf2_frame_sniffer (const struct frame_unwind *self, 1385 struct frame_info *this_frame, void **this_cache) 1386 { 1387 /* Grab an address that is guarenteed to reside somewhere within the 1388 function. get_frame_pc(), with a no-return next function, can 1389 end up returning something past the end of this function's body. 1390 If the frame we're sniffing for is a signal frame whose start 1391 address is placed on the stack by the OS, its FDE must 1392 extend one byte before its start address or we could potentially 1393 select the FDE of the previous function. */ 1394 CORE_ADDR block_addr = get_frame_address_in_block (this_frame); 1395 struct dwarf2_fde *fde = dwarf2_frame_find_fde (&block_addr, NULL); 1396 1397 if (!fde) 1398 return 0; 1399 1400 /* On some targets, signal trampolines may have unwind information. 1401 We need to recognize them so that we set the frame type 1402 correctly. */ 1403 1404 if (fde->cie->signal_frame 1405 || dwarf2_frame_signal_frame_p (get_frame_arch (this_frame), 1406 this_frame)) 1407 return self->type == SIGTRAMP_FRAME; 1408 1409 if (self->type != NORMAL_FRAME) 1410 return 0; 1411 1412 /* Preinitializa the cache so that TAILCALL_FRAME can find the record by 1413 dwarf2_tailcall_sniffer_first. */ 1414 dwarf2_frame_cache (this_frame, this_cache); 1415 1416 return 1; 1417 } 1418 1419 static const struct frame_unwind dwarf2_frame_unwind = 1420 { 1421 NORMAL_FRAME, 1422 dwarf2_frame_unwind_stop_reason, 1423 dwarf2_frame_this_id, 1424 dwarf2_frame_prev_register, 1425 NULL, 1426 dwarf2_frame_sniffer, 1427 dwarf2_frame_dealloc_cache 1428 }; 1429 1430 static const struct frame_unwind dwarf2_signal_frame_unwind = 1431 { 1432 SIGTRAMP_FRAME, 1433 dwarf2_frame_unwind_stop_reason, 1434 dwarf2_frame_this_id, 1435 dwarf2_frame_prev_register, 1436 NULL, 1437 dwarf2_frame_sniffer, 1438 1439 /* TAILCALL_CACHE can never be in such frame to need dealloc_cache. */ 1440 NULL 1441 }; 1442 1443 /* Append the DWARF-2 frame unwinders to GDBARCH's list. */ 1444 1445 void 1446 dwarf2_append_unwinders (struct gdbarch *gdbarch) 1447 { 1448 /* TAILCALL_FRAME must be first to find the record by 1449 dwarf2_tailcall_sniffer_first. */ 1450 frame_unwind_append_unwinder (gdbarch, &dwarf2_tailcall_frame_unwind); 1451 1452 frame_unwind_append_unwinder (gdbarch, &dwarf2_frame_unwind); 1453 frame_unwind_append_unwinder (gdbarch, &dwarf2_signal_frame_unwind); 1454 } 1455 1456 1457 /* There is no explicitly defined relationship between the CFA and the 1458 location of frame's local variables and arguments/parameters. 1459 Therefore, frame base methods on this page should probably only be 1460 used as a last resort, just to avoid printing total garbage as a 1461 response to the "info frame" command. */ 1462 1463 static CORE_ADDR 1464 dwarf2_frame_base_address (struct frame_info *this_frame, void **this_cache) 1465 { 1466 struct dwarf2_frame_cache *cache = 1467 dwarf2_frame_cache (this_frame, this_cache); 1468 1469 return cache->cfa; 1470 } 1471 1472 static const struct frame_base dwarf2_frame_base = 1473 { 1474 &dwarf2_frame_unwind, 1475 dwarf2_frame_base_address, 1476 dwarf2_frame_base_address, 1477 dwarf2_frame_base_address 1478 }; 1479 1480 const struct frame_base * 1481 dwarf2_frame_base_sniffer (struct frame_info *this_frame) 1482 { 1483 CORE_ADDR block_addr = get_frame_address_in_block (this_frame); 1484 1485 if (dwarf2_frame_find_fde (&block_addr, NULL)) 1486 return &dwarf2_frame_base; 1487 1488 return NULL; 1489 } 1490 1491 /* Compute the CFA for THIS_FRAME, but only if THIS_FRAME came from 1492 the DWARF unwinder. This is used to implement 1493 DW_OP_call_frame_cfa. */ 1494 1495 CORE_ADDR 1496 dwarf2_frame_cfa (struct frame_info *this_frame) 1497 { 1498 while (get_frame_type (this_frame) == INLINE_FRAME) 1499 this_frame = get_prev_frame (this_frame); 1500 /* This restriction could be lifted if other unwinders are known to 1501 compute the frame base in a way compatible with the DWARF 1502 unwinder. */ 1503 if (!frame_unwinder_is (this_frame, &dwarf2_frame_unwind) 1504 && !frame_unwinder_is (this_frame, &dwarf2_tailcall_frame_unwind)) 1505 error (_("can't compute CFA for this frame")); 1506 if (get_frame_unwind_stop_reason (this_frame) == UNWIND_UNAVAILABLE) 1507 throw_error (NOT_AVAILABLE_ERROR, 1508 _("can't compute CFA for this frame: " 1509 "required registers or memory are unavailable")); 1510 return get_frame_base (this_frame); 1511 } 1512 1513 const struct objfile_data *dwarf2_frame_objfile_data; 1514 1515 static unsigned int 1516 read_1_byte (bfd *abfd, const gdb_byte *buf) 1517 { 1518 return bfd_get_8 (abfd, buf); 1519 } 1520 1521 static unsigned int 1522 read_4_bytes (bfd *abfd, const gdb_byte *buf) 1523 { 1524 return bfd_get_32 (abfd, buf); 1525 } 1526 1527 static ULONGEST 1528 read_8_bytes (bfd *abfd, const gdb_byte *buf) 1529 { 1530 return bfd_get_64 (abfd, buf); 1531 } 1532 1533 static ULONGEST 1534 read_initial_length (bfd *abfd, const gdb_byte *buf, 1535 unsigned int *bytes_read_ptr) 1536 { 1537 LONGEST result; 1538 1539 result = bfd_get_32 (abfd, buf); 1540 if (result == 0xffffffff) 1541 { 1542 result = bfd_get_64 (abfd, buf + 4); 1543 *bytes_read_ptr = 12; 1544 } 1545 else 1546 *bytes_read_ptr = 4; 1547 1548 return result; 1549 } 1550 1551 1552 /* Pointer encoding helper functions. */ 1553 1554 /* GCC supports exception handling based on DWARF2 CFI. However, for 1555 technical reasons, it encodes addresses in its FDE's in a different 1556 way. Several "pointer encodings" are supported. The encoding 1557 that's used for a particular FDE is determined by the 'R' 1558 augmentation in the associated CIE. The argument of this 1559 augmentation is a single byte. 1560 1561 The address can be encoded as 2 bytes, 4 bytes, 8 bytes, or as a 1562 LEB128. This is encoded in bits 0, 1 and 2. Bit 3 encodes whether 1563 the address is signed or unsigned. Bits 4, 5 and 6 encode how the 1564 address should be interpreted (absolute, relative to the current 1565 position in the FDE, ...). Bit 7, indicates that the address 1566 should be dereferenced. */ 1567 1568 static gdb_byte 1569 encoding_for_size (unsigned int size) 1570 { 1571 switch (size) 1572 { 1573 case 2: 1574 return DW_EH_PE_udata2; 1575 case 4: 1576 return DW_EH_PE_udata4; 1577 case 8: 1578 return DW_EH_PE_udata8; 1579 default: 1580 internal_error (__FILE__, __LINE__, _("Unsupported address size")); 1581 } 1582 } 1583 1584 static CORE_ADDR 1585 read_encoded_value (struct comp_unit *unit, gdb_byte encoding, 1586 int ptr_len, const gdb_byte *buf, 1587 unsigned int *bytes_read_ptr, 1588 CORE_ADDR func_base) 1589 { 1590 ptrdiff_t offset; 1591 CORE_ADDR base; 1592 1593 /* GCC currently doesn't generate DW_EH_PE_indirect encodings for 1594 FDE's. */ 1595 if (encoding & DW_EH_PE_indirect) 1596 internal_error (__FILE__, __LINE__, 1597 _("Unsupported encoding: DW_EH_PE_indirect")); 1598 1599 *bytes_read_ptr = 0; 1600 1601 switch (encoding & 0x70) 1602 { 1603 case DW_EH_PE_absptr: 1604 base = 0; 1605 break; 1606 case DW_EH_PE_pcrel: 1607 base = bfd_get_section_vma (unit->abfd, unit->dwarf_frame_section); 1608 base += (buf - unit->dwarf_frame_buffer); 1609 break; 1610 case DW_EH_PE_datarel: 1611 base = unit->dbase; 1612 break; 1613 case DW_EH_PE_textrel: 1614 base = unit->tbase; 1615 break; 1616 case DW_EH_PE_funcrel: 1617 base = func_base; 1618 break; 1619 case DW_EH_PE_aligned: 1620 base = 0; 1621 offset = buf - unit->dwarf_frame_buffer; 1622 if ((offset % ptr_len) != 0) 1623 { 1624 *bytes_read_ptr = ptr_len - (offset % ptr_len); 1625 buf += *bytes_read_ptr; 1626 } 1627 break; 1628 default: 1629 internal_error (__FILE__, __LINE__, 1630 _("Invalid or unsupported encoding")); 1631 } 1632 1633 if ((encoding & 0x07) == 0x00) 1634 { 1635 encoding |= encoding_for_size (ptr_len); 1636 if (bfd_get_sign_extend_vma (unit->abfd)) 1637 encoding |= DW_EH_PE_signed; 1638 } 1639 1640 switch (encoding & 0x0f) 1641 { 1642 case DW_EH_PE_uleb128: 1643 { 1644 uint64_t value; 1645 const gdb_byte *end_buf = buf + (sizeof (value) + 1) * 8 / 7; 1646 1647 *bytes_read_ptr += safe_read_uleb128 (buf, end_buf, &value) - buf; 1648 return base + value; 1649 } 1650 case DW_EH_PE_udata2: 1651 *bytes_read_ptr += 2; 1652 return (base + bfd_get_16 (unit->abfd, (bfd_byte *) buf)); 1653 case DW_EH_PE_udata4: 1654 *bytes_read_ptr += 4; 1655 return (base + bfd_get_32 (unit->abfd, (bfd_byte *) buf)); 1656 case DW_EH_PE_udata8: 1657 *bytes_read_ptr += 8; 1658 return (base + bfd_get_64 (unit->abfd, (bfd_byte *) buf)); 1659 case DW_EH_PE_sleb128: 1660 { 1661 int64_t value; 1662 const gdb_byte *end_buf = buf + (sizeof (value) + 1) * 8 / 7; 1663 1664 *bytes_read_ptr += safe_read_sleb128 (buf, end_buf, &value) - buf; 1665 return base + value; 1666 } 1667 case DW_EH_PE_sdata2: 1668 *bytes_read_ptr += 2; 1669 return (base + bfd_get_signed_16 (unit->abfd, (bfd_byte *) buf)); 1670 case DW_EH_PE_sdata4: 1671 *bytes_read_ptr += 4; 1672 return (base + bfd_get_signed_32 (unit->abfd, (bfd_byte *) buf)); 1673 case DW_EH_PE_sdata8: 1674 *bytes_read_ptr += 8; 1675 return (base + bfd_get_signed_64 (unit->abfd, (bfd_byte *) buf)); 1676 default: 1677 internal_error (__FILE__, __LINE__, 1678 _("Invalid or unsupported encoding")); 1679 } 1680 } 1681 1682 1683 static int 1684 bsearch_cie_cmp (const void *key, const void *element) 1685 { 1686 ULONGEST cie_pointer = *(ULONGEST *) key; 1687 struct dwarf2_cie *cie = *(struct dwarf2_cie **) element; 1688 1689 if (cie_pointer == cie->cie_pointer) 1690 return 0; 1691 1692 return (cie_pointer < cie->cie_pointer) ? -1 : 1; 1693 } 1694 1695 /* Find CIE with the given CIE_POINTER in CIE_TABLE. */ 1696 static struct dwarf2_cie * 1697 find_cie (struct dwarf2_cie_table *cie_table, ULONGEST cie_pointer) 1698 { 1699 struct dwarf2_cie **p_cie; 1700 1701 /* The C standard (ISO/IEC 9899:TC2) requires the BASE argument to 1702 bsearch be non-NULL. */ 1703 if (cie_table->entries == NULL) 1704 { 1705 gdb_assert (cie_table->num_entries == 0); 1706 return NULL; 1707 } 1708 1709 p_cie = bsearch (&cie_pointer, cie_table->entries, cie_table->num_entries, 1710 sizeof (cie_table->entries[0]), bsearch_cie_cmp); 1711 if (p_cie != NULL) 1712 return *p_cie; 1713 return NULL; 1714 } 1715 1716 /* Add a pointer to new CIE to the CIE_TABLE, allocating space for it. */ 1717 static void 1718 add_cie (struct dwarf2_cie_table *cie_table, struct dwarf2_cie *cie) 1719 { 1720 const int n = cie_table->num_entries; 1721 1722 gdb_assert (n < 1 1723 || cie_table->entries[n - 1]->cie_pointer < cie->cie_pointer); 1724 1725 cie_table->entries = 1726 xrealloc (cie_table->entries, (n + 1) * sizeof (cie_table->entries[0])); 1727 cie_table->entries[n] = cie; 1728 cie_table->num_entries = n + 1; 1729 } 1730 1731 static int 1732 bsearch_fde_cmp (const void *key, const void *element) 1733 { 1734 CORE_ADDR seek_pc = *(CORE_ADDR *) key; 1735 struct dwarf2_fde *fde = *(struct dwarf2_fde **) element; 1736 1737 if (seek_pc < fde->initial_location) 1738 return -1; 1739 if (seek_pc < fde->initial_location + fde->address_range) 1740 return 0; 1741 return 1; 1742 } 1743 1744 /* Find the FDE for *PC. Return a pointer to the FDE, and store the 1745 inital location associated with it into *PC. */ 1746 1747 static struct dwarf2_fde * 1748 dwarf2_frame_find_fde (CORE_ADDR *pc, CORE_ADDR *out_offset) 1749 { 1750 struct objfile *objfile; 1751 1752 ALL_OBJFILES (objfile) 1753 { 1754 struct dwarf2_fde_table *fde_table; 1755 struct dwarf2_fde **p_fde; 1756 CORE_ADDR offset; 1757 CORE_ADDR seek_pc; 1758 1759 fde_table = objfile_data (objfile, dwarf2_frame_objfile_data); 1760 if (fde_table == NULL) 1761 { 1762 dwarf2_build_frame_info (objfile); 1763 fde_table = objfile_data (objfile, dwarf2_frame_objfile_data); 1764 } 1765 gdb_assert (fde_table != NULL); 1766 1767 if (fde_table->num_entries == 0) 1768 continue; 1769 1770 gdb_assert (objfile->section_offsets); 1771 offset = ANOFFSET (objfile->section_offsets, SECT_OFF_TEXT (objfile)); 1772 1773 gdb_assert (fde_table->num_entries > 0); 1774 if (*pc < offset + fde_table->entries[0]->initial_location) 1775 continue; 1776 1777 seek_pc = *pc - offset; 1778 p_fde = bsearch (&seek_pc, fde_table->entries, fde_table->num_entries, 1779 sizeof (fde_table->entries[0]), bsearch_fde_cmp); 1780 if (p_fde != NULL) 1781 { 1782 *pc = (*p_fde)->initial_location + offset; 1783 if (out_offset) 1784 *out_offset = offset; 1785 return *p_fde; 1786 } 1787 } 1788 return NULL; 1789 } 1790 1791 /* Add a pointer to new FDE to the FDE_TABLE, allocating space for it. */ 1792 static void 1793 add_fde (struct dwarf2_fde_table *fde_table, struct dwarf2_fde *fde) 1794 { 1795 if (fde->address_range == 0) 1796 /* Discard useless FDEs. */ 1797 return; 1798 1799 fde_table->num_entries += 1; 1800 fde_table->entries = 1801 xrealloc (fde_table->entries, 1802 fde_table->num_entries * sizeof (fde_table->entries[0])); 1803 fde_table->entries[fde_table->num_entries - 1] = fde; 1804 } 1805 1806 #define DW64_CIE_ID 0xffffffffffffffffULL 1807 1808 /* Defines the type of eh_frames that are expected to be decoded: CIE, FDE 1809 or any of them. */ 1810 1811 enum eh_frame_type 1812 { 1813 EH_CIE_TYPE_ID = 1 << 0, 1814 EH_FDE_TYPE_ID = 1 << 1, 1815 EH_CIE_OR_FDE_TYPE_ID = EH_CIE_TYPE_ID | EH_FDE_TYPE_ID 1816 }; 1817 1818 static const gdb_byte *decode_frame_entry (struct comp_unit *unit, 1819 const gdb_byte *start, 1820 int eh_frame_p, 1821 struct dwarf2_cie_table *cie_table, 1822 struct dwarf2_fde_table *fde_table, 1823 enum eh_frame_type entry_type); 1824 1825 /* Decode the next CIE or FDE, entry_type specifies the expected type. 1826 Return NULL if invalid input, otherwise the next byte to be processed. */ 1827 1828 static const gdb_byte * 1829 decode_frame_entry_1 (struct comp_unit *unit, const gdb_byte *start, 1830 int eh_frame_p, 1831 struct dwarf2_cie_table *cie_table, 1832 struct dwarf2_fde_table *fde_table, 1833 enum eh_frame_type entry_type) 1834 { 1835 struct gdbarch *gdbarch = get_objfile_arch (unit->objfile); 1836 const gdb_byte *buf, *end; 1837 LONGEST length; 1838 unsigned int bytes_read; 1839 int dwarf64_p; 1840 ULONGEST cie_id; 1841 ULONGEST cie_pointer; 1842 int64_t sleb128; 1843 uint64_t uleb128; 1844 1845 buf = start; 1846 length = read_initial_length (unit->abfd, buf, &bytes_read); 1847 buf += bytes_read; 1848 end = buf + length; 1849 1850 /* Are we still within the section? */ 1851 if (end > unit->dwarf_frame_buffer + unit->dwarf_frame_size) 1852 return NULL; 1853 1854 if (length == 0) 1855 return end; 1856 1857 /* Distinguish between 32 and 64-bit encoded frame info. */ 1858 dwarf64_p = (bytes_read == 12); 1859 1860 /* In a .eh_frame section, zero is used to distinguish CIEs from FDEs. */ 1861 if (eh_frame_p) 1862 cie_id = 0; 1863 else if (dwarf64_p) 1864 cie_id = DW64_CIE_ID; 1865 else 1866 cie_id = DW_CIE_ID; 1867 1868 if (dwarf64_p) 1869 { 1870 cie_pointer = read_8_bytes (unit->abfd, buf); 1871 buf += 8; 1872 } 1873 else 1874 { 1875 cie_pointer = read_4_bytes (unit->abfd, buf); 1876 buf += 4; 1877 } 1878 1879 if (cie_pointer == cie_id) 1880 { 1881 /* This is a CIE. */ 1882 struct dwarf2_cie *cie; 1883 char *augmentation; 1884 unsigned int cie_version; 1885 1886 /* Check that a CIE was expected. */ 1887 if ((entry_type & EH_CIE_TYPE_ID) == 0) 1888 error (_("Found a CIE when not expecting it.")); 1889 1890 /* Record the offset into the .debug_frame section of this CIE. */ 1891 cie_pointer = start - unit->dwarf_frame_buffer; 1892 1893 /* Check whether we've already read it. */ 1894 if (find_cie (cie_table, cie_pointer)) 1895 return end; 1896 1897 cie = (struct dwarf2_cie *) 1898 obstack_alloc (&unit->objfile->objfile_obstack, 1899 sizeof (struct dwarf2_cie)); 1900 cie->initial_instructions = NULL; 1901 cie->cie_pointer = cie_pointer; 1902 1903 /* The encoding for FDE's in a normal .debug_frame section 1904 depends on the target address size. */ 1905 cie->encoding = DW_EH_PE_absptr; 1906 1907 /* We'll determine the final value later, but we need to 1908 initialize it conservatively. */ 1909 cie->signal_frame = 0; 1910 1911 /* Check version number. */ 1912 cie_version = read_1_byte (unit->abfd, buf); 1913 if (cie_version != 1 && cie_version != 3 && cie_version != 4) 1914 return NULL; 1915 cie->version = cie_version; 1916 buf += 1; 1917 1918 /* Interpret the interesting bits of the augmentation. */ 1919 cie->augmentation = augmentation = (char *) buf; 1920 buf += (strlen (augmentation) + 1); 1921 1922 /* Ignore armcc augmentations. We only use them for quirks, 1923 and that doesn't happen until later. */ 1924 if (strncmp (augmentation, "armcc", 5) == 0) 1925 augmentation += strlen (augmentation); 1926 1927 /* The GCC 2.x "eh" augmentation has a pointer immediately 1928 following the augmentation string, so it must be handled 1929 first. */ 1930 if (augmentation[0] == 'e' && augmentation[1] == 'h') 1931 { 1932 /* Skip. */ 1933 buf += gdbarch_ptr_bit (gdbarch) / TARGET_CHAR_BIT; 1934 augmentation += 2; 1935 } 1936 1937 if (cie->version >= 4) 1938 { 1939 /* FIXME: check that this is the same as from the CU header. */ 1940 cie->addr_size = read_1_byte (unit->abfd, buf); 1941 ++buf; 1942 cie->segment_size = read_1_byte (unit->abfd, buf); 1943 ++buf; 1944 } 1945 else 1946 { 1947 cie->addr_size = gdbarch_dwarf2_addr_size (gdbarch); 1948 cie->segment_size = 0; 1949 } 1950 /* Address values in .eh_frame sections are defined to have the 1951 target's pointer size. Watchout: This breaks frame info for 1952 targets with pointer size < address size, unless a .debug_frame 1953 section exists as well. */ 1954 if (eh_frame_p) 1955 cie->ptr_size = gdbarch_ptr_bit (gdbarch) / TARGET_CHAR_BIT; 1956 else 1957 cie->ptr_size = cie->addr_size; 1958 1959 buf = gdb_read_uleb128 (buf, end, &uleb128); 1960 if (buf == NULL) 1961 return NULL; 1962 cie->code_alignment_factor = uleb128; 1963 1964 buf = gdb_read_sleb128 (buf, end, &sleb128); 1965 if (buf == NULL) 1966 return NULL; 1967 cie->data_alignment_factor = sleb128; 1968 1969 if (cie_version == 1) 1970 { 1971 cie->return_address_register = read_1_byte (unit->abfd, buf); 1972 ++buf; 1973 } 1974 else 1975 { 1976 buf = gdb_read_uleb128 (buf, end, &uleb128); 1977 if (buf == NULL) 1978 return NULL; 1979 cie->return_address_register = uleb128; 1980 } 1981 1982 cie->return_address_register 1983 = dwarf2_frame_adjust_regnum (gdbarch, 1984 cie->return_address_register, 1985 eh_frame_p); 1986 1987 cie->saw_z_augmentation = (*augmentation == 'z'); 1988 if (cie->saw_z_augmentation) 1989 { 1990 uint64_t length; 1991 1992 buf = gdb_read_uleb128 (buf, end, &length); 1993 if (buf == NULL) 1994 return NULL; 1995 cie->initial_instructions = buf + length; 1996 augmentation++; 1997 } 1998 1999 while (*augmentation) 2000 { 2001 /* "L" indicates a byte showing how the LSDA pointer is encoded. */ 2002 if (*augmentation == 'L') 2003 { 2004 /* Skip. */ 2005 buf++; 2006 augmentation++; 2007 } 2008 2009 /* "R" indicates a byte indicating how FDE addresses are encoded. */ 2010 else if (*augmentation == 'R') 2011 { 2012 cie->encoding = *buf++; 2013 augmentation++; 2014 } 2015 2016 /* "P" indicates a personality routine in the CIE augmentation. */ 2017 else if (*augmentation == 'P') 2018 { 2019 /* Skip. Avoid indirection since we throw away the result. */ 2020 gdb_byte encoding = (*buf++) & ~DW_EH_PE_indirect; 2021 read_encoded_value (unit, encoding, cie->ptr_size, 2022 buf, &bytes_read, 0); 2023 buf += bytes_read; 2024 augmentation++; 2025 } 2026 2027 /* "S" indicates a signal frame, such that the return 2028 address must not be decremented to locate the call frame 2029 info for the previous frame; it might even be the first 2030 instruction of a function, so decrementing it would take 2031 us to a different function. */ 2032 else if (*augmentation == 'S') 2033 { 2034 cie->signal_frame = 1; 2035 augmentation++; 2036 } 2037 2038 /* Otherwise we have an unknown augmentation. Assume that either 2039 there is no augmentation data, or we saw a 'z' prefix. */ 2040 else 2041 { 2042 if (cie->initial_instructions) 2043 buf = cie->initial_instructions; 2044 break; 2045 } 2046 } 2047 2048 cie->initial_instructions = buf; 2049 cie->end = end; 2050 cie->unit = unit; 2051 2052 add_cie (cie_table, cie); 2053 } 2054 else 2055 { 2056 /* This is a FDE. */ 2057 struct dwarf2_fde *fde; 2058 2059 /* Check that an FDE was expected. */ 2060 if ((entry_type & EH_FDE_TYPE_ID) == 0) 2061 error (_("Found an FDE when not expecting it.")); 2062 2063 /* In an .eh_frame section, the CIE pointer is the delta between the 2064 address within the FDE where the CIE pointer is stored and the 2065 address of the CIE. Convert it to an offset into the .eh_frame 2066 section. */ 2067 if (eh_frame_p) 2068 { 2069 cie_pointer = buf - unit->dwarf_frame_buffer - cie_pointer; 2070 cie_pointer -= (dwarf64_p ? 8 : 4); 2071 } 2072 2073 /* In either case, validate the result is still within the section. */ 2074 if (cie_pointer >= unit->dwarf_frame_size) 2075 return NULL; 2076 2077 fde = (struct dwarf2_fde *) 2078 obstack_alloc (&unit->objfile->objfile_obstack, 2079 sizeof (struct dwarf2_fde)); 2080 fde->cie = find_cie (cie_table, cie_pointer); 2081 if (fde->cie == NULL) 2082 { 2083 decode_frame_entry (unit, unit->dwarf_frame_buffer + cie_pointer, 2084 eh_frame_p, cie_table, fde_table, 2085 EH_CIE_TYPE_ID); 2086 fde->cie = find_cie (cie_table, cie_pointer); 2087 } 2088 2089 gdb_assert (fde->cie != NULL); 2090 2091 fde->initial_location = 2092 read_encoded_value (unit, fde->cie->encoding, fde->cie->ptr_size, 2093 buf, &bytes_read, 0); 2094 buf += bytes_read; 2095 2096 fde->address_range = 2097 read_encoded_value (unit, fde->cie->encoding & 0x0f, 2098 fde->cie->ptr_size, buf, &bytes_read, 0); 2099 buf += bytes_read; 2100 2101 /* A 'z' augmentation in the CIE implies the presence of an 2102 augmentation field in the FDE as well. The only thing known 2103 to be in here at present is the LSDA entry for EH. So we 2104 can skip the whole thing. */ 2105 if (fde->cie->saw_z_augmentation) 2106 { 2107 uint64_t length; 2108 2109 buf = gdb_read_uleb128 (buf, end, &length); 2110 if (buf == NULL) 2111 return NULL; 2112 buf += length; 2113 if (buf > end) 2114 return NULL; 2115 } 2116 2117 fde->instructions = buf; 2118 fde->end = end; 2119 2120 fde->eh_frame_p = eh_frame_p; 2121 2122 add_fde (fde_table, fde); 2123 } 2124 2125 return end; 2126 } 2127 2128 /* Read a CIE or FDE in BUF and decode it. Entry_type specifies whether we 2129 expect an FDE or a CIE. */ 2130 2131 static const gdb_byte * 2132 decode_frame_entry (struct comp_unit *unit, const gdb_byte *start, 2133 int eh_frame_p, 2134 struct dwarf2_cie_table *cie_table, 2135 struct dwarf2_fde_table *fde_table, 2136 enum eh_frame_type entry_type) 2137 { 2138 enum { NONE, ALIGN4, ALIGN8, FAIL } workaround = NONE; 2139 const gdb_byte *ret; 2140 ptrdiff_t start_offset; 2141 2142 while (1) 2143 { 2144 ret = decode_frame_entry_1 (unit, start, eh_frame_p, 2145 cie_table, fde_table, entry_type); 2146 if (ret != NULL) 2147 break; 2148 2149 /* We have corrupt input data of some form. */ 2150 2151 /* ??? Try, weakly, to work around compiler/assembler/linker bugs 2152 and mismatches wrt padding and alignment of debug sections. */ 2153 /* Note that there is no requirement in the standard for any 2154 alignment at all in the frame unwind sections. Testing for 2155 alignment before trying to interpret data would be incorrect. 2156 2157 However, GCC traditionally arranged for frame sections to be 2158 sized such that the FDE length and CIE fields happen to be 2159 aligned (in theory, for performance). This, unfortunately, 2160 was done with .align directives, which had the side effect of 2161 forcing the section to be aligned by the linker. 2162 2163 This becomes a problem when you have some other producer that 2164 creates frame sections that are not as strictly aligned. That 2165 produces a hole in the frame info that gets filled by the 2166 linker with zeros. 2167 2168 The GCC behaviour is arguably a bug, but it's effectively now 2169 part of the ABI, so we're now stuck with it, at least at the 2170 object file level. A smart linker may decide, in the process 2171 of compressing duplicate CIE information, that it can rewrite 2172 the entire output section without this extra padding. */ 2173 2174 start_offset = start - unit->dwarf_frame_buffer; 2175 if (workaround < ALIGN4 && (start_offset & 3) != 0) 2176 { 2177 start += 4 - (start_offset & 3); 2178 workaround = ALIGN4; 2179 continue; 2180 } 2181 if (workaround < ALIGN8 && (start_offset & 7) != 0) 2182 { 2183 start += 8 - (start_offset & 7); 2184 workaround = ALIGN8; 2185 continue; 2186 } 2187 2188 /* Nothing left to try. Arrange to return as if we've consumed 2189 the entire input section. Hopefully we'll get valid info from 2190 the other of .debug_frame/.eh_frame. */ 2191 workaround = FAIL; 2192 ret = unit->dwarf_frame_buffer + unit->dwarf_frame_size; 2193 break; 2194 } 2195 2196 switch (workaround) 2197 { 2198 case NONE: 2199 break; 2200 2201 case ALIGN4: 2202 complaint (&symfile_complaints, _("\ 2203 Corrupt data in %s:%s; align 4 workaround apparently succeeded"), 2204 unit->dwarf_frame_section->owner->filename, 2205 unit->dwarf_frame_section->name); 2206 break; 2207 2208 case ALIGN8: 2209 complaint (&symfile_complaints, _("\ 2210 Corrupt data in %s:%s; align 8 workaround apparently succeeded"), 2211 unit->dwarf_frame_section->owner->filename, 2212 unit->dwarf_frame_section->name); 2213 break; 2214 2215 default: 2216 complaint (&symfile_complaints, 2217 _("Corrupt data in %s:%s"), 2218 unit->dwarf_frame_section->owner->filename, 2219 unit->dwarf_frame_section->name); 2220 break; 2221 } 2222 2223 return ret; 2224 } 2225 2226 static int 2227 qsort_fde_cmp (const void *a, const void *b) 2228 { 2229 struct dwarf2_fde *aa = *(struct dwarf2_fde **)a; 2230 struct dwarf2_fde *bb = *(struct dwarf2_fde **)b; 2231 2232 if (aa->initial_location == bb->initial_location) 2233 { 2234 if (aa->address_range != bb->address_range 2235 && aa->eh_frame_p == 0 && bb->eh_frame_p == 0) 2236 /* Linker bug, e.g. gold/10400. 2237 Work around it by keeping stable sort order. */ 2238 return (a < b) ? -1 : 1; 2239 else 2240 /* Put eh_frame entries after debug_frame ones. */ 2241 return aa->eh_frame_p - bb->eh_frame_p; 2242 } 2243 2244 return (aa->initial_location < bb->initial_location) ? -1 : 1; 2245 } 2246 2247 void 2248 dwarf2_build_frame_info (struct objfile *objfile) 2249 { 2250 struct comp_unit *unit; 2251 const gdb_byte *frame_ptr; 2252 struct dwarf2_cie_table cie_table; 2253 struct dwarf2_fde_table fde_table; 2254 struct dwarf2_fde_table *fde_table2; 2255 volatile struct gdb_exception e; 2256 2257 cie_table.num_entries = 0; 2258 cie_table.entries = NULL; 2259 2260 fde_table.num_entries = 0; 2261 fde_table.entries = NULL; 2262 2263 /* Build a minimal decoding of the DWARF2 compilation unit. */ 2264 unit = (struct comp_unit *) obstack_alloc (&objfile->objfile_obstack, 2265 sizeof (struct comp_unit)); 2266 unit->abfd = objfile->obfd; 2267 unit->objfile = objfile; 2268 unit->dbase = 0; 2269 unit->tbase = 0; 2270 2271 if (objfile->separate_debug_objfile_backlink == NULL) 2272 { 2273 /* Do not read .eh_frame from separate file as they must be also 2274 present in the main file. */ 2275 dwarf2_get_section_info (objfile, DWARF2_EH_FRAME, 2276 &unit->dwarf_frame_section, 2277 &unit->dwarf_frame_buffer, 2278 &unit->dwarf_frame_size); 2279 if (unit->dwarf_frame_size) 2280 { 2281 asection *got, *txt; 2282 2283 /* FIXME: kettenis/20030602: This is the DW_EH_PE_datarel base 2284 that is used for the i386/amd64 target, which currently is 2285 the only target in GCC that supports/uses the 2286 DW_EH_PE_datarel encoding. */ 2287 got = bfd_get_section_by_name (unit->abfd, ".got"); 2288 if (got) 2289 unit->dbase = got->vma; 2290 2291 /* GCC emits the DW_EH_PE_textrel encoding type on sh and ia64 2292 so far. */ 2293 txt = bfd_get_section_by_name (unit->abfd, ".text"); 2294 if (txt) 2295 unit->tbase = txt->vma; 2296 2297 TRY_CATCH (e, RETURN_MASK_ERROR) 2298 { 2299 frame_ptr = unit->dwarf_frame_buffer; 2300 while (frame_ptr < unit->dwarf_frame_buffer + unit->dwarf_frame_size) 2301 frame_ptr = decode_frame_entry (unit, frame_ptr, 1, 2302 &cie_table, &fde_table, 2303 EH_CIE_OR_FDE_TYPE_ID); 2304 } 2305 2306 if (e.reason < 0) 2307 { 2308 warning (_("skipping .eh_frame info of %s: %s"), 2309 objfile->name, e.message); 2310 2311 if (fde_table.num_entries != 0) 2312 { 2313 xfree (fde_table.entries); 2314 fde_table.entries = NULL; 2315 fde_table.num_entries = 0; 2316 } 2317 /* The cie_table is discarded by the next if. */ 2318 } 2319 2320 if (cie_table.num_entries != 0) 2321 { 2322 /* Reinit cie_table: debug_frame has different CIEs. */ 2323 xfree (cie_table.entries); 2324 cie_table.num_entries = 0; 2325 cie_table.entries = NULL; 2326 } 2327 } 2328 } 2329 2330 dwarf2_get_section_info (objfile, DWARF2_DEBUG_FRAME, 2331 &unit->dwarf_frame_section, 2332 &unit->dwarf_frame_buffer, 2333 &unit->dwarf_frame_size); 2334 if (unit->dwarf_frame_size) 2335 { 2336 int num_old_fde_entries = fde_table.num_entries; 2337 2338 TRY_CATCH (e, RETURN_MASK_ERROR) 2339 { 2340 frame_ptr = unit->dwarf_frame_buffer; 2341 while (frame_ptr < unit->dwarf_frame_buffer + unit->dwarf_frame_size) 2342 frame_ptr = decode_frame_entry (unit, frame_ptr, 0, 2343 &cie_table, &fde_table, 2344 EH_CIE_OR_FDE_TYPE_ID); 2345 } 2346 if (e.reason < 0) 2347 { 2348 warning (_("skipping .debug_frame info of %s: %s"), 2349 objfile->name, e.message); 2350 2351 if (fde_table.num_entries != 0) 2352 { 2353 fde_table.num_entries = num_old_fde_entries; 2354 if (num_old_fde_entries == 0) 2355 { 2356 xfree (fde_table.entries); 2357 fde_table.entries = NULL; 2358 } 2359 else 2360 { 2361 fde_table.entries = xrealloc (fde_table.entries, 2362 fde_table.num_entries * 2363 sizeof (fde_table.entries[0])); 2364 } 2365 } 2366 fde_table.num_entries = num_old_fde_entries; 2367 /* The cie_table is discarded by the next if. */ 2368 } 2369 } 2370 2371 /* Discard the cie_table, it is no longer needed. */ 2372 if (cie_table.num_entries != 0) 2373 { 2374 xfree (cie_table.entries); 2375 cie_table.entries = NULL; /* Paranoia. */ 2376 cie_table.num_entries = 0; /* Paranoia. */ 2377 } 2378 2379 /* Copy fde_table to obstack: it is needed at runtime. */ 2380 fde_table2 = (struct dwarf2_fde_table *) 2381 obstack_alloc (&objfile->objfile_obstack, sizeof (*fde_table2)); 2382 2383 if (fde_table.num_entries == 0) 2384 { 2385 fde_table2->entries = NULL; 2386 fde_table2->num_entries = 0; 2387 } 2388 else 2389 { 2390 struct dwarf2_fde *fde_prev = NULL; 2391 struct dwarf2_fde *first_non_zero_fde = NULL; 2392 int i; 2393 2394 /* Prepare FDE table for lookups. */ 2395 qsort (fde_table.entries, fde_table.num_entries, 2396 sizeof (fde_table.entries[0]), qsort_fde_cmp); 2397 2398 /* Check for leftovers from --gc-sections. The GNU linker sets 2399 the relevant symbols to zero, but doesn't zero the FDE *end* 2400 ranges because there's no relocation there. It's (offset, 2401 length), not (start, end). On targets where address zero is 2402 just another valid address this can be a problem, since the 2403 FDEs appear to be non-empty in the output --- we could pick 2404 out the wrong FDE. To work around this, when overlaps are 2405 detected, we prefer FDEs that do not start at zero. 2406 2407 Start by finding the first FDE with non-zero start. Below 2408 we'll discard all FDEs that start at zero and overlap this 2409 one. */ 2410 for (i = 0; i < fde_table.num_entries; i++) 2411 { 2412 struct dwarf2_fde *fde = fde_table.entries[i]; 2413 2414 if (fde->initial_location != 0) 2415 { 2416 first_non_zero_fde = fde; 2417 break; 2418 } 2419 } 2420 2421 /* Since we'll be doing bsearch, squeeze out identical (except 2422 for eh_frame_p) fde entries so bsearch result is predictable. 2423 Also discard leftovers from --gc-sections. */ 2424 fde_table2->num_entries = 0; 2425 for (i = 0; i < fde_table.num_entries; i++) 2426 { 2427 struct dwarf2_fde *fde = fde_table.entries[i]; 2428 2429 if (fde->initial_location == 0 2430 && first_non_zero_fde != NULL 2431 && (first_non_zero_fde->initial_location 2432 < fde->initial_location + fde->address_range)) 2433 continue; 2434 2435 if (fde_prev != NULL 2436 && fde_prev->initial_location == fde->initial_location) 2437 continue; 2438 2439 obstack_grow (&objfile->objfile_obstack, &fde_table.entries[i], 2440 sizeof (fde_table.entries[0])); 2441 ++fde_table2->num_entries; 2442 fde_prev = fde; 2443 } 2444 fde_table2->entries = obstack_finish (&objfile->objfile_obstack); 2445 2446 /* Discard the original fde_table. */ 2447 xfree (fde_table.entries); 2448 } 2449 2450 set_objfile_data (objfile, dwarf2_frame_objfile_data, fde_table2); 2451 } 2452 2453 /* Provide a prototype to silence -Wmissing-prototypes. */ 2454 void _initialize_dwarf2_frame (void); 2455 2456 void 2457 _initialize_dwarf2_frame (void) 2458 { 2459 dwarf2_frame_data = gdbarch_data_register_pre_init (dwarf2_frame_init); 2460 dwarf2_frame_objfile_data = register_objfile_data (); 2461 } 2462