| 1 | /* Frame unwinder for frames with DWARF Call Frame Information. |
| 2 | |
| 3 | Copyright 2003, 2004, 2005 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 2 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, write to the Free Software |
| 21 | Foundation, Inc., 59 Temple Place - Suite 330, |
| 22 | Boston, MA 02111-1307, USA. */ |
| 23 | |
| 24 | #include "defs.h" |
| 25 | #include "dwarf2expr.h" |
| 26 | #include "elf/dwarf2.h" |
| 27 | #include "frame.h" |
| 28 | #include "frame-base.h" |
| 29 | #include "frame-unwind.h" |
| 30 | #include "gdbcore.h" |
| 31 | #include "gdbtypes.h" |
| 32 | #include "symtab.h" |
| 33 | #include "objfiles.h" |
| 34 | #include "regcache.h" |
| 35 | |
| 36 | #include "gdb_assert.h" |
| 37 | #include "gdb_string.h" |
| 38 | |
| 39 | #include "complaints.h" |
| 40 | #include "dwarf2-frame.h" |
| 41 | |
| 42 | /* Call Frame Information (CFI). */ |
| 43 | |
| 44 | /* Common Information Entry (CIE). */ |
| 45 | |
| 46 | struct dwarf2_cie |
| 47 | { |
| 48 | /* Offset into the .debug_frame section where this CIE was found. |
| 49 | Used to identify this CIE. */ |
| 50 | ULONGEST cie_pointer; |
| 51 | |
| 52 | /* Constant that is factored out of all advance location |
| 53 | instructions. */ |
| 54 | ULONGEST code_alignment_factor; |
| 55 | |
| 56 | /* Constants that is factored out of all offset instructions. */ |
| 57 | LONGEST data_alignment_factor; |
| 58 | |
| 59 | /* Return address column. */ |
| 60 | ULONGEST return_address_register; |
| 61 | |
| 62 | /* Instruction sequence to initialize a register set. */ |
| 63 | gdb_byte *initial_instructions; |
| 64 | gdb_byte *end; |
| 65 | |
| 66 | /* Encoding of addresses. */ |
| 67 | gdb_byte encoding; |
| 68 | |
| 69 | /* True if a 'z' augmentation existed. */ |
| 70 | unsigned char saw_z_augmentation; |
| 71 | |
| 72 | struct dwarf2_cie *next; |
| 73 | }; |
| 74 | |
| 75 | /* Frame Description Entry (FDE). */ |
| 76 | |
| 77 | struct dwarf2_fde |
| 78 | { |
| 79 | /* CIE for this FDE. */ |
| 80 | struct dwarf2_cie *cie; |
| 81 | |
| 82 | /* First location associated with this FDE. */ |
| 83 | CORE_ADDR initial_location; |
| 84 | |
| 85 | /* Number of bytes of program instructions described by this FDE. */ |
| 86 | CORE_ADDR address_range; |
| 87 | |
| 88 | /* Instruction sequence. */ |
| 89 | gdb_byte *instructions; |
| 90 | gdb_byte *end; |
| 91 | |
| 92 | struct dwarf2_fde *next; |
| 93 | }; |
| 94 | |
| 95 | static struct dwarf2_fde *dwarf2_frame_find_fde (CORE_ADDR *pc); |
| 96 | \f |
| 97 | |
| 98 | /* Structure describing a frame state. */ |
| 99 | |
| 100 | struct dwarf2_frame_state |
| 101 | { |
| 102 | /* Each register save state can be described in terms of a CFA slot, |
| 103 | another register, or a location expression. */ |
| 104 | struct dwarf2_frame_state_reg_info |
| 105 | { |
| 106 | struct dwarf2_frame_state_reg *reg; |
| 107 | int num_regs; |
| 108 | |
| 109 | /* Used to implement DW_CFA_remember_state. */ |
| 110 | struct dwarf2_frame_state_reg_info *prev; |
| 111 | } regs; |
| 112 | |
| 113 | LONGEST cfa_offset; |
| 114 | ULONGEST cfa_reg; |
| 115 | gdb_byte *cfa_exp; |
| 116 | enum { |
| 117 | CFA_UNSET, |
| 118 | CFA_REG_OFFSET, |
| 119 | CFA_EXP |
| 120 | } cfa_how; |
| 121 | |
| 122 | /* The PC described by the current frame state. */ |
| 123 | CORE_ADDR pc; |
| 124 | |
| 125 | /* Initial register set from the CIE. |
| 126 | Used to implement DW_CFA_restore. */ |
| 127 | struct dwarf2_frame_state_reg_info initial; |
| 128 | |
| 129 | /* The information we care about from the CIE. */ |
| 130 | LONGEST data_align; |
| 131 | ULONGEST code_align; |
| 132 | ULONGEST retaddr_column; |
| 133 | }; |
| 134 | |
| 135 | /* Store the length the expression for the CFA in the `cfa_reg' field, |
| 136 | which is unused in that case. */ |
| 137 | #define cfa_exp_len cfa_reg |
| 138 | |
| 139 | /* Assert that the register set RS is large enough to store NUM_REGS |
| 140 | columns. If necessary, enlarge the register set. */ |
| 141 | |
| 142 | static void |
| 143 | dwarf2_frame_state_alloc_regs (struct dwarf2_frame_state_reg_info *rs, |
| 144 | int num_regs) |
| 145 | { |
| 146 | size_t size = sizeof (struct dwarf2_frame_state_reg); |
| 147 | |
| 148 | if (num_regs <= rs->num_regs) |
| 149 | return; |
| 150 | |
| 151 | rs->reg = (struct dwarf2_frame_state_reg *) |
| 152 | xrealloc (rs->reg, num_regs * size); |
| 153 | |
| 154 | /* Initialize newly allocated registers. */ |
| 155 | memset (rs->reg + rs->num_regs, 0, (num_regs - rs->num_regs) * size); |
| 156 | rs->num_regs = num_regs; |
| 157 | } |
| 158 | |
| 159 | /* Copy the register columns in register set RS into newly allocated |
| 160 | memory and return a pointer to this newly created copy. */ |
| 161 | |
| 162 | static struct dwarf2_frame_state_reg * |
| 163 | dwarf2_frame_state_copy_regs (struct dwarf2_frame_state_reg_info *rs) |
| 164 | { |
| 165 | size_t size = rs->num_regs * sizeof (struct dwarf2_frame_state_reg); |
| 166 | struct dwarf2_frame_state_reg *reg; |
| 167 | |
| 168 | reg = (struct dwarf2_frame_state_reg *) xmalloc (size); |
| 169 | memcpy (reg, rs->reg, size); |
| 170 | |
| 171 | return reg; |
| 172 | } |
| 173 | |
| 174 | /* Release the memory allocated to register set RS. */ |
| 175 | |
| 176 | static void |
| 177 | dwarf2_frame_state_free_regs (struct dwarf2_frame_state_reg_info *rs) |
| 178 | { |
| 179 | if (rs) |
| 180 | { |
| 181 | dwarf2_frame_state_free_regs (rs->prev); |
| 182 | |
| 183 | xfree (rs->reg); |
| 184 | xfree (rs); |
| 185 | } |
| 186 | } |
| 187 | |
| 188 | /* Release the memory allocated to the frame state FS. */ |
| 189 | |
| 190 | static void |
| 191 | dwarf2_frame_state_free (void *p) |
| 192 | { |
| 193 | struct dwarf2_frame_state *fs = p; |
| 194 | |
| 195 | dwarf2_frame_state_free_regs (fs->initial.prev); |
| 196 | dwarf2_frame_state_free_regs (fs->regs.prev); |
| 197 | xfree (fs->initial.reg); |
| 198 | xfree (fs->regs.reg); |
| 199 | xfree (fs); |
| 200 | } |
| 201 | \f |
| 202 | |
| 203 | /* Helper functions for execute_stack_op. */ |
| 204 | |
| 205 | static CORE_ADDR |
| 206 | read_reg (void *baton, int reg) |
| 207 | { |
| 208 | struct frame_info *next_frame = (struct frame_info *) baton; |
| 209 | struct gdbarch *gdbarch = get_frame_arch (next_frame); |
| 210 | int regnum; |
| 211 | gdb_byte *buf; |
| 212 | |
| 213 | regnum = DWARF2_REG_TO_REGNUM (reg); |
| 214 | |
| 215 | buf = alloca (register_size (gdbarch, regnum)); |
| 216 | frame_unwind_register (next_frame, regnum, buf); |
| 217 | return extract_typed_address (buf, builtin_type_void_data_ptr); |
| 218 | } |
| 219 | |
| 220 | static void |
| 221 | read_mem (void *baton, gdb_byte *buf, CORE_ADDR addr, size_t len) |
| 222 | { |
| 223 | read_memory (addr, buf, len); |
| 224 | } |
| 225 | |
| 226 | static void |
| 227 | no_get_frame_base (void *baton, gdb_byte **start, size_t *length) |
| 228 | { |
| 229 | internal_error (__FILE__, __LINE__, |
| 230 | _("Support for DW_OP_fbreg is unimplemented")); |
| 231 | } |
| 232 | |
| 233 | static CORE_ADDR |
| 234 | no_get_tls_address (void *baton, CORE_ADDR offset) |
| 235 | { |
| 236 | internal_error (__FILE__, __LINE__, |
| 237 | _("Support for DW_OP_GNU_push_tls_address is unimplemented")); |
| 238 | } |
| 239 | |
| 240 | static CORE_ADDR |
| 241 | execute_stack_op (gdb_byte *exp, ULONGEST len, |
| 242 | struct frame_info *next_frame, CORE_ADDR initial) |
| 243 | { |
| 244 | struct dwarf_expr_context *ctx; |
| 245 | CORE_ADDR result; |
| 246 | |
| 247 | ctx = new_dwarf_expr_context (); |
| 248 | ctx->baton = next_frame; |
| 249 | ctx->read_reg = read_reg; |
| 250 | ctx->read_mem = read_mem; |
| 251 | ctx->get_frame_base = no_get_frame_base; |
| 252 | ctx->get_tls_address = no_get_tls_address; |
| 253 | |
| 254 | dwarf_expr_push (ctx, initial); |
| 255 | dwarf_expr_eval (ctx, exp, len); |
| 256 | result = dwarf_expr_fetch (ctx, 0); |
| 257 | |
| 258 | if (ctx->in_reg) |
| 259 | result = read_reg (next_frame, result); |
| 260 | |
| 261 | free_dwarf_expr_context (ctx); |
| 262 | |
| 263 | return result; |
| 264 | } |
| 265 | \f |
| 266 | |
| 267 | static void |
| 268 | execute_cfa_program (gdb_byte *insn_ptr, gdb_byte *insn_end, |
| 269 | struct frame_info *next_frame, |
| 270 | struct dwarf2_frame_state *fs) |
| 271 | { |
| 272 | CORE_ADDR pc = frame_pc_unwind (next_frame); |
| 273 | int bytes_read; |
| 274 | |
| 275 | while (insn_ptr < insn_end && fs->pc <= pc) |
| 276 | { |
| 277 | gdb_byte insn = *insn_ptr++; |
| 278 | ULONGEST utmp, reg; |
| 279 | LONGEST offset; |
| 280 | |
| 281 | if ((insn & 0xc0) == DW_CFA_advance_loc) |
| 282 | fs->pc += (insn & 0x3f) * fs->code_align; |
| 283 | else if ((insn & 0xc0) == DW_CFA_offset) |
| 284 | { |
| 285 | reg = insn & 0x3f; |
| 286 | insn_ptr = read_uleb128 (insn_ptr, insn_end, &utmp); |
| 287 | offset = utmp * fs->data_align; |
| 288 | dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1); |
| 289 | fs->regs.reg[reg].how = DWARF2_FRAME_REG_SAVED_OFFSET; |
| 290 | fs->regs.reg[reg].loc.offset = offset; |
| 291 | } |
| 292 | else if ((insn & 0xc0) == DW_CFA_restore) |
| 293 | { |
| 294 | gdb_assert (fs->initial.reg); |
| 295 | reg = insn & 0x3f; |
| 296 | dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1); |
| 297 | fs->regs.reg[reg] = fs->initial.reg[reg]; |
| 298 | } |
| 299 | else |
| 300 | { |
| 301 | switch (insn) |
| 302 | { |
| 303 | case DW_CFA_set_loc: |
| 304 | fs->pc = dwarf2_read_address (insn_ptr, insn_end, &bytes_read); |
| 305 | insn_ptr += bytes_read; |
| 306 | break; |
| 307 | |
| 308 | case DW_CFA_advance_loc1: |
| 309 | utmp = extract_unsigned_integer (insn_ptr, 1); |
| 310 | fs->pc += utmp * fs->code_align; |
| 311 | insn_ptr++; |
| 312 | break; |
| 313 | case DW_CFA_advance_loc2: |
| 314 | utmp = extract_unsigned_integer (insn_ptr, 2); |
| 315 | fs->pc += utmp * fs->code_align; |
| 316 | insn_ptr += 2; |
| 317 | break; |
| 318 | case DW_CFA_advance_loc4: |
| 319 | utmp = extract_unsigned_integer (insn_ptr, 4); |
| 320 | fs->pc += utmp * fs->code_align; |
| 321 | insn_ptr += 4; |
| 322 | break; |
| 323 | |
| 324 | case DW_CFA_offset_extended: |
| 325 | insn_ptr = read_uleb128 (insn_ptr, insn_end, ®); |
| 326 | insn_ptr = read_uleb128 (insn_ptr, insn_end, &utmp); |
| 327 | offset = utmp * fs->data_align; |
| 328 | dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1); |
| 329 | fs->regs.reg[reg].how = DWARF2_FRAME_REG_SAVED_OFFSET; |
| 330 | fs->regs.reg[reg].loc.offset = offset; |
| 331 | break; |
| 332 | |
| 333 | case DW_CFA_restore_extended: |
| 334 | gdb_assert (fs->initial.reg); |
| 335 | insn_ptr = read_uleb128 (insn_ptr, insn_end, ®); |
| 336 | dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1); |
| 337 | fs->regs.reg[reg] = fs->initial.reg[reg]; |
| 338 | break; |
| 339 | |
| 340 | case DW_CFA_undefined: |
| 341 | insn_ptr = read_uleb128 (insn_ptr, insn_end, ®); |
| 342 | dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1); |
| 343 | fs->regs.reg[reg].how = DWARF2_FRAME_REG_UNDEFINED; |
| 344 | break; |
| 345 | |
| 346 | case DW_CFA_same_value: |
| 347 | insn_ptr = read_uleb128 (insn_ptr, insn_end, ®); |
| 348 | dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1); |
| 349 | fs->regs.reg[reg].how = DWARF2_FRAME_REG_SAME_VALUE; |
| 350 | break; |
| 351 | |
| 352 | case DW_CFA_register: |
| 353 | insn_ptr = read_uleb128 (insn_ptr, insn_end, ®); |
| 354 | insn_ptr = read_uleb128 (insn_ptr, insn_end, &utmp); |
| 355 | dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1); |
| 356 | fs->regs.reg[reg].how = DWARF2_FRAME_REG_SAVED_REG; |
| 357 | fs->regs.reg[reg].loc.reg = utmp; |
| 358 | break; |
| 359 | |
| 360 | case DW_CFA_remember_state: |
| 361 | { |
| 362 | struct dwarf2_frame_state_reg_info *new_rs; |
| 363 | |
| 364 | new_rs = XMALLOC (struct dwarf2_frame_state_reg_info); |
| 365 | *new_rs = fs->regs; |
| 366 | fs->regs.reg = dwarf2_frame_state_copy_regs (&fs->regs); |
| 367 | fs->regs.prev = new_rs; |
| 368 | } |
| 369 | break; |
| 370 | |
| 371 | case DW_CFA_restore_state: |
| 372 | { |
| 373 | struct dwarf2_frame_state_reg_info *old_rs = fs->regs.prev; |
| 374 | |
| 375 | if (old_rs == NULL) |
| 376 | { |
| 377 | complaint (&symfile_complaints, _("\ |
| 378 | bad CFI data; mismatched DW_CFA_restore_state at 0x%s"), paddr (fs->pc)); |
| 379 | } |
| 380 | else |
| 381 | { |
| 382 | xfree (fs->regs.reg); |
| 383 | fs->regs = *old_rs; |
| 384 | xfree (old_rs); |
| 385 | } |
| 386 | } |
| 387 | break; |
| 388 | |
| 389 | case DW_CFA_def_cfa: |
| 390 | insn_ptr = read_uleb128 (insn_ptr, insn_end, &fs->cfa_reg); |
| 391 | insn_ptr = read_uleb128 (insn_ptr, insn_end, &utmp); |
| 392 | fs->cfa_offset = utmp; |
| 393 | fs->cfa_how = CFA_REG_OFFSET; |
| 394 | break; |
| 395 | |
| 396 | case DW_CFA_def_cfa_register: |
| 397 | insn_ptr = read_uleb128 (insn_ptr, insn_end, &fs->cfa_reg); |
| 398 | fs->cfa_how = CFA_REG_OFFSET; |
| 399 | break; |
| 400 | |
| 401 | case DW_CFA_def_cfa_offset: |
| 402 | insn_ptr = read_uleb128 (insn_ptr, insn_end, &utmp); |
| 403 | fs->cfa_offset = utmp; |
| 404 | /* cfa_how deliberately not set. */ |
| 405 | break; |
| 406 | |
| 407 | case DW_CFA_nop: |
| 408 | break; |
| 409 | |
| 410 | case DW_CFA_def_cfa_expression: |
| 411 | insn_ptr = read_uleb128 (insn_ptr, insn_end, &fs->cfa_exp_len); |
| 412 | fs->cfa_exp = insn_ptr; |
| 413 | fs->cfa_how = CFA_EXP; |
| 414 | insn_ptr += fs->cfa_exp_len; |
| 415 | break; |
| 416 | |
| 417 | case DW_CFA_expression: |
| 418 | insn_ptr = read_uleb128 (insn_ptr, insn_end, ®); |
| 419 | dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1); |
| 420 | insn_ptr = read_uleb128 (insn_ptr, insn_end, &utmp); |
| 421 | fs->regs.reg[reg].loc.exp = insn_ptr; |
| 422 | fs->regs.reg[reg].exp_len = utmp; |
| 423 | fs->regs.reg[reg].how = DWARF2_FRAME_REG_SAVED_EXP; |
| 424 | insn_ptr += utmp; |
| 425 | break; |
| 426 | |
| 427 | case DW_CFA_offset_extended_sf: |
| 428 | insn_ptr = read_uleb128 (insn_ptr, insn_end, ®); |
| 429 | insn_ptr = read_sleb128 (insn_ptr, insn_end, &offset); |
| 430 | offset *= fs->data_align; |
| 431 | dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1); |
| 432 | fs->regs.reg[reg].how = DWARF2_FRAME_REG_SAVED_OFFSET; |
| 433 | fs->regs.reg[reg].loc.offset = offset; |
| 434 | break; |
| 435 | |
| 436 | case DW_CFA_def_cfa_sf: |
| 437 | insn_ptr = read_uleb128 (insn_ptr, insn_end, &fs->cfa_reg); |
| 438 | insn_ptr = read_sleb128 (insn_ptr, insn_end, &offset); |
| 439 | fs->cfa_offset = offset * fs->data_align; |
| 440 | fs->cfa_how = CFA_REG_OFFSET; |
| 441 | break; |
| 442 | |
| 443 | case DW_CFA_def_cfa_offset_sf: |
| 444 | insn_ptr = read_sleb128 (insn_ptr, insn_end, &offset); |
| 445 | fs->cfa_offset = offset * fs->data_align; |
| 446 | /* cfa_how deliberately not set. */ |
| 447 | break; |
| 448 | |
| 449 | case DW_CFA_GNU_window_save: |
| 450 | /* This is SPARC-specific code, and contains hard-coded |
| 451 | constants for the register numbering scheme used by |
| 452 | GCC. Rather than having a architecture-specific |
| 453 | operation that's only ever used by a single |
| 454 | architecture, we provide the implementation here. |
| 455 | Incidentally that's what GCC does too in its |
| 456 | unwinder. */ |
| 457 | { |
| 458 | struct gdbarch *gdbarch = get_frame_arch (next_frame); |
| 459 | int size = register_size(gdbarch, 0); |
| 460 | dwarf2_frame_state_alloc_regs (&fs->regs, 32); |
| 461 | for (reg = 8; reg < 16; reg++) |
| 462 | { |
| 463 | fs->regs.reg[reg].how = DWARF2_FRAME_REG_SAVED_REG; |
| 464 | fs->regs.reg[reg].loc.reg = reg + 16; |
| 465 | } |
| 466 | for (reg = 16; reg < 32; reg++) |
| 467 | { |
| 468 | fs->regs.reg[reg].how = DWARF2_FRAME_REG_SAVED_OFFSET; |
| 469 | fs->regs.reg[reg].loc.offset = (reg - 16) * size; |
| 470 | } |
| 471 | } |
| 472 | break; |
| 473 | |
| 474 | case DW_CFA_GNU_args_size: |
| 475 | /* Ignored. */ |
| 476 | insn_ptr = read_uleb128 (insn_ptr, insn_end, &utmp); |
| 477 | break; |
| 478 | |
| 479 | default: |
| 480 | internal_error (__FILE__, __LINE__, _("Unknown CFI encountered.")); |
| 481 | } |
| 482 | } |
| 483 | } |
| 484 | |
| 485 | /* Don't allow remember/restore between CIE and FDE programs. */ |
| 486 | dwarf2_frame_state_free_regs (fs->regs.prev); |
| 487 | fs->regs.prev = NULL; |
| 488 | } |
| 489 | \f |
| 490 | |
| 491 | /* Architecture-specific operations. */ |
| 492 | |
| 493 | /* Per-architecture data key. */ |
| 494 | static struct gdbarch_data *dwarf2_frame_data; |
| 495 | |
| 496 | struct dwarf2_frame_ops |
| 497 | { |
| 498 | /* Pre-initialize the register state REG for register REGNUM. */ |
| 499 | void (*init_reg) (struct gdbarch *, int, struct dwarf2_frame_state_reg *); |
| 500 | |
| 501 | /* Check whether the frame preceding NEXT_FRAME will be a signal |
| 502 | trampoline. */ |
| 503 | int (*signal_frame_p) (struct gdbarch *, struct frame_info *); |
| 504 | }; |
| 505 | |
| 506 | /* Default architecture-specific register state initialization |
| 507 | function. */ |
| 508 | |
| 509 | static void |
| 510 | dwarf2_frame_default_init_reg (struct gdbarch *gdbarch, int regnum, |
| 511 | struct dwarf2_frame_state_reg *reg) |
| 512 | { |
| 513 | /* If we have a register that acts as a program counter, mark it as |
| 514 | a destination for the return address. If we have a register that |
| 515 | serves as the stack pointer, arrange for it to be filled with the |
| 516 | call frame address (CFA). The other registers are marked as |
| 517 | unspecified. |
| 518 | |
| 519 | We copy the return address to the program counter, since many |
| 520 | parts in GDB assume that it is possible to get the return address |
| 521 | by unwinding the program counter register. However, on ISA's |
| 522 | with a dedicated return address register, the CFI usually only |
| 523 | contains information to unwind that return address register. |
| 524 | |
| 525 | The reason we're treating the stack pointer special here is |
| 526 | because in many cases GCC doesn't emit CFI for the stack pointer |
| 527 | and implicitly assumes that it is equal to the CFA. This makes |
| 528 | some sense since the DWARF specification (version 3, draft 8, |
| 529 | p. 102) says that: |
| 530 | |
| 531 | "Typically, the CFA is defined to be the value of the stack |
| 532 | pointer at the call site in the previous frame (which may be |
| 533 | different from its value on entry to the current frame)." |
| 534 | |
| 535 | However, this isn't true for all platforms supported by GCC |
| 536 | (e.g. IBM S/390 and zSeries). Those architectures should provide |
| 537 | their own architecture-specific initialization function. */ |
| 538 | |
| 539 | if (regnum == PC_REGNUM) |
| 540 | reg->how = DWARF2_FRAME_REG_RA; |
| 541 | else if (regnum == SP_REGNUM) |
| 542 | reg->how = DWARF2_FRAME_REG_CFA; |
| 543 | } |
| 544 | |
| 545 | /* Return a default for the architecture-specific operations. */ |
| 546 | |
| 547 | static void * |
| 548 | dwarf2_frame_init (struct obstack *obstack) |
| 549 | { |
| 550 | struct dwarf2_frame_ops *ops; |
| 551 | |
| 552 | ops = OBSTACK_ZALLOC (obstack, struct dwarf2_frame_ops); |
| 553 | ops->init_reg = dwarf2_frame_default_init_reg; |
| 554 | return ops; |
| 555 | } |
| 556 | |
| 557 | /* Set the architecture-specific register state initialization |
| 558 | function for GDBARCH to INIT_REG. */ |
| 559 | |
| 560 | void |
| 561 | dwarf2_frame_set_init_reg (struct gdbarch *gdbarch, |
| 562 | void (*init_reg) (struct gdbarch *, int, |
| 563 | struct dwarf2_frame_state_reg *)) |
| 564 | { |
| 565 | struct dwarf2_frame_ops *ops = gdbarch_data (gdbarch, dwarf2_frame_data); |
| 566 | |
| 567 | ops->init_reg = init_reg; |
| 568 | } |
| 569 | |
| 570 | /* Pre-initialize the register state REG for register REGNUM. */ |
| 571 | |
| 572 | static void |
| 573 | dwarf2_frame_init_reg (struct gdbarch *gdbarch, int regnum, |
| 574 | struct dwarf2_frame_state_reg *reg) |
| 575 | { |
| 576 | struct dwarf2_frame_ops *ops = gdbarch_data (gdbarch, dwarf2_frame_data); |
| 577 | |
| 578 | ops->init_reg (gdbarch, regnum, reg); |
| 579 | } |
| 580 | |
| 581 | /* Set the architecture-specific signal trampoline recognition |
| 582 | function for GDBARCH to SIGNAL_FRAME_P. */ |
| 583 | |
| 584 | void |
| 585 | dwarf2_frame_set_signal_frame_p (struct gdbarch *gdbarch, |
| 586 | int (*signal_frame_p) (struct gdbarch *, |
| 587 | struct frame_info *)) |
| 588 | { |
| 589 | struct dwarf2_frame_ops *ops = gdbarch_data (gdbarch, dwarf2_frame_data); |
| 590 | |
| 591 | ops->signal_frame_p = signal_frame_p; |
| 592 | } |
| 593 | |
| 594 | /* Query the architecture-specific signal frame recognizer for |
| 595 | NEXT_FRAME. */ |
| 596 | |
| 597 | static int |
| 598 | dwarf2_frame_signal_frame_p (struct gdbarch *gdbarch, |
| 599 | struct frame_info *next_frame) |
| 600 | { |
| 601 | struct dwarf2_frame_ops *ops = gdbarch_data (gdbarch, dwarf2_frame_data); |
| 602 | |
| 603 | if (ops->signal_frame_p == NULL) |
| 604 | return 0; |
| 605 | return ops->signal_frame_p (gdbarch, next_frame); |
| 606 | } |
| 607 | \f |
| 608 | |
| 609 | struct dwarf2_frame_cache |
| 610 | { |
| 611 | /* DWARF Call Frame Address. */ |
| 612 | CORE_ADDR cfa; |
| 613 | |
| 614 | /* Set if the return address column was marked as undefined. */ |
| 615 | int undefined_retaddr; |
| 616 | |
| 617 | /* Saved registers, indexed by GDB register number, not by DWARF |
| 618 | register number. */ |
| 619 | struct dwarf2_frame_state_reg *reg; |
| 620 | |
| 621 | /* Return address register. */ |
| 622 | struct dwarf2_frame_state_reg retaddr_reg; |
| 623 | }; |
| 624 | |
| 625 | static struct dwarf2_frame_cache * |
| 626 | dwarf2_frame_cache (struct frame_info *next_frame, void **this_cache) |
| 627 | { |
| 628 | struct cleanup *old_chain; |
| 629 | struct gdbarch *gdbarch = get_frame_arch (next_frame); |
| 630 | const int num_regs = NUM_REGS + NUM_PSEUDO_REGS; |
| 631 | struct dwarf2_frame_cache *cache; |
| 632 | struct dwarf2_frame_state *fs; |
| 633 | struct dwarf2_fde *fde; |
| 634 | |
| 635 | if (*this_cache) |
| 636 | return *this_cache; |
| 637 | |
| 638 | /* Allocate a new cache. */ |
| 639 | cache = FRAME_OBSTACK_ZALLOC (struct dwarf2_frame_cache); |
| 640 | cache->reg = FRAME_OBSTACK_CALLOC (num_regs, struct dwarf2_frame_state_reg); |
| 641 | |
| 642 | /* Allocate and initialize the frame state. */ |
| 643 | fs = XMALLOC (struct dwarf2_frame_state); |
| 644 | memset (fs, 0, sizeof (struct dwarf2_frame_state)); |
| 645 | old_chain = make_cleanup (dwarf2_frame_state_free, fs); |
| 646 | |
| 647 | /* Unwind the PC. |
| 648 | |
| 649 | Note that if NEXT_FRAME is never supposed to return (i.e. a call |
| 650 | to abort), the compiler might optimize away the instruction at |
| 651 | NEXT_FRAME's return address. As a result the return address will |
| 652 | point at some random instruction, and the CFI for that |
| 653 | instruction is probably worthless to us. GCC's unwinder solves |
| 654 | this problem by substracting 1 from the return address to get an |
| 655 | address in the middle of a presumed call instruction (or the |
| 656 | instruction in the associated delay slot). This should only be |
| 657 | done for "normal" frames and not for resume-type frames (signal |
| 658 | handlers, sentinel frames, dummy frames). The function |
| 659 | frame_unwind_address_in_block does just this. It's not clear how |
| 660 | reliable the method is though; there is the potential for the |
| 661 | register state pre-call being different to that on return. */ |
| 662 | fs->pc = frame_unwind_address_in_block (next_frame); |
| 663 | |
| 664 | /* Find the correct FDE. */ |
| 665 | fde = dwarf2_frame_find_fde (&fs->pc); |
| 666 | gdb_assert (fde != NULL); |
| 667 | |
| 668 | /* Extract any interesting information from the CIE. */ |
| 669 | fs->data_align = fde->cie->data_alignment_factor; |
| 670 | fs->code_align = fde->cie->code_alignment_factor; |
| 671 | fs->retaddr_column = fde->cie->return_address_register; |
| 672 | |
| 673 | /* First decode all the insns in the CIE. */ |
| 674 | execute_cfa_program (fde->cie->initial_instructions, |
| 675 | fde->cie->end, next_frame, fs); |
| 676 | |
| 677 | /* Save the initialized register set. */ |
| 678 | fs->initial = fs->regs; |
| 679 | fs->initial.reg = dwarf2_frame_state_copy_regs (&fs->regs); |
| 680 | |
| 681 | /* Then decode the insns in the FDE up to our target PC. */ |
| 682 | execute_cfa_program (fde->instructions, fde->end, next_frame, fs); |
| 683 | |
| 684 | /* Caclulate the CFA. */ |
| 685 | switch (fs->cfa_how) |
| 686 | { |
| 687 | case CFA_REG_OFFSET: |
| 688 | cache->cfa = read_reg (next_frame, fs->cfa_reg); |
| 689 | cache->cfa += fs->cfa_offset; |
| 690 | break; |
| 691 | |
| 692 | case CFA_EXP: |
| 693 | cache->cfa = |
| 694 | execute_stack_op (fs->cfa_exp, fs->cfa_exp_len, next_frame, 0); |
| 695 | break; |
| 696 | |
| 697 | default: |
| 698 | internal_error (__FILE__, __LINE__, _("Unknown CFA rule.")); |
| 699 | } |
| 700 | |
| 701 | /* Initialize the register state. */ |
| 702 | { |
| 703 | int regnum; |
| 704 | |
| 705 | for (regnum = 0; regnum < num_regs; regnum++) |
| 706 | dwarf2_frame_init_reg (gdbarch, regnum, &cache->reg[regnum]); |
| 707 | } |
| 708 | |
| 709 | /* Go through the DWARF2 CFI generated table and save its register |
| 710 | location information in the cache. Note that we don't skip the |
| 711 | return address column; it's perfectly all right for it to |
| 712 | correspond to a real register. If it doesn't correspond to a |
| 713 | real register, or if we shouldn't treat it as such, |
| 714 | DWARF2_REG_TO_REGNUM should be defined to return a number outside |
| 715 | the range [0, NUM_REGS). */ |
| 716 | { |
| 717 | int column; /* CFI speak for "register number". */ |
| 718 | |
| 719 | for (column = 0; column < fs->regs.num_regs; column++) |
| 720 | { |
| 721 | /* Use the GDB register number as the destination index. */ |
| 722 | int regnum = DWARF2_REG_TO_REGNUM (column); |
| 723 | |
| 724 | /* If there's no corresponding GDB register, ignore it. */ |
| 725 | if (regnum < 0 || regnum >= num_regs) |
| 726 | continue; |
| 727 | |
| 728 | /* NOTE: cagney/2003-09-05: CFI should specify the disposition |
| 729 | of all debug info registers. If it doesn't, complain (but |
| 730 | not too loudly). It turns out that GCC assumes that an |
| 731 | unspecified register implies "same value" when CFI (draft |
| 732 | 7) specifies nothing at all. Such a register could equally |
| 733 | be interpreted as "undefined". Also note that this check |
| 734 | isn't sufficient; it only checks that all registers in the |
| 735 | range [0 .. max column] are specified, and won't detect |
| 736 | problems when a debug info register falls outside of the |
| 737 | table. We need a way of iterating through all the valid |
| 738 | DWARF2 register numbers. */ |
| 739 | if (fs->regs.reg[column].how == DWARF2_FRAME_REG_UNSPECIFIED) |
| 740 | { |
| 741 | if (cache->reg[regnum].how == DWARF2_FRAME_REG_UNSPECIFIED) |
| 742 | complaint (&symfile_complaints, _("\ |
| 743 | incomplete CFI data; unspecified registers (e.g., %s) at 0x%s"), |
| 744 | gdbarch_register_name (gdbarch, regnum), |
| 745 | paddr_nz (fs->pc)); |
| 746 | } |
| 747 | else |
| 748 | cache->reg[regnum] = fs->regs.reg[column]; |
| 749 | } |
| 750 | } |
| 751 | |
| 752 | /* Eliminate any DWARF2_FRAME_REG_RA rules, and save the information |
| 753 | we need for evaluating DWARF2_FRAME_REG_RA_OFFSET rules. */ |
| 754 | { |
| 755 | int regnum; |
| 756 | |
| 757 | for (regnum = 0; regnum < num_regs; regnum++) |
| 758 | { |
| 759 | if (cache->reg[regnum].how == DWARF2_FRAME_REG_RA |
| 760 | || cache->reg[regnum].how == DWARF2_FRAME_REG_RA_OFFSET) |
| 761 | { |
| 762 | struct dwarf2_frame_state_reg *retaddr_reg = |
| 763 | &fs->regs.reg[fs->retaddr_column]; |
| 764 | |
| 765 | /* It seems rather bizarre to specify an "empty" column as |
| 766 | the return adress column. However, this is exactly |
| 767 | what GCC does on some targets. It turns out that GCC |
| 768 | assumes that the return address can be found in the |
| 769 | register corresponding to the return address column. |
| 770 | Incidentally, that's how we should treat a return |
| 771 | address column specifying "same value" too. */ |
| 772 | if (fs->retaddr_column < fs->regs.num_regs |
| 773 | && retaddr_reg->how != DWARF2_FRAME_REG_UNSPECIFIED |
| 774 | && retaddr_reg->how != DWARF2_FRAME_REG_SAME_VALUE) |
| 775 | { |
| 776 | if (cache->reg[regnum].how == DWARF2_FRAME_REG_RA) |
| 777 | cache->reg[regnum] = *retaddr_reg; |
| 778 | else |
| 779 | cache->retaddr_reg = *retaddr_reg; |
| 780 | } |
| 781 | else |
| 782 | { |
| 783 | if (cache->reg[regnum].how == DWARF2_FRAME_REG_RA) |
| 784 | { |
| 785 | cache->reg[regnum].loc.reg = fs->retaddr_column; |
| 786 | cache->reg[regnum].how = DWARF2_FRAME_REG_SAVED_REG; |
| 787 | } |
| 788 | else |
| 789 | { |
| 790 | cache->retaddr_reg.loc.reg = fs->retaddr_column; |
| 791 | cache->retaddr_reg.how = DWARF2_FRAME_REG_SAVED_REG; |
| 792 | } |
| 793 | } |
| 794 | } |
| 795 | } |
| 796 | } |
| 797 | |
| 798 | if (fs->retaddr_column < fs->regs.num_regs |
| 799 | && fs->regs.reg[fs->retaddr_column].how == DWARF2_FRAME_REG_UNDEFINED) |
| 800 | cache->undefined_retaddr = 1; |
| 801 | |
| 802 | do_cleanups (old_chain); |
| 803 | |
| 804 | *this_cache = cache; |
| 805 | return cache; |
| 806 | } |
| 807 | |
| 808 | static void |
| 809 | dwarf2_frame_this_id (struct frame_info *next_frame, void **this_cache, |
| 810 | struct frame_id *this_id) |
| 811 | { |
| 812 | struct dwarf2_frame_cache *cache = |
| 813 | dwarf2_frame_cache (next_frame, this_cache); |
| 814 | |
| 815 | if (cache->undefined_retaddr) |
| 816 | return; |
| 817 | |
| 818 | (*this_id) = frame_id_build (cache->cfa, frame_func_unwind (next_frame)); |
| 819 | } |
| 820 | |
| 821 | static void |
| 822 | dwarf2_frame_prev_register (struct frame_info *next_frame, void **this_cache, |
| 823 | int regnum, int *optimizedp, |
| 824 | enum lval_type *lvalp, CORE_ADDR *addrp, |
| 825 | int *realnump, gdb_byte *valuep) |
| 826 | { |
| 827 | struct gdbarch *gdbarch = get_frame_arch (next_frame); |
| 828 | struct dwarf2_frame_cache *cache = |
| 829 | dwarf2_frame_cache (next_frame, this_cache); |
| 830 | |
| 831 | switch (cache->reg[regnum].how) |
| 832 | { |
| 833 | case DWARF2_FRAME_REG_UNDEFINED: |
| 834 | /* If CFI explicitly specified that the value isn't defined, |
| 835 | mark it as optimized away; the value isn't available. */ |
| 836 | *optimizedp = 1; |
| 837 | *lvalp = not_lval; |
| 838 | *addrp = 0; |
| 839 | *realnump = -1; |
| 840 | if (valuep) |
| 841 | { |
| 842 | /* In some cases, for example %eflags on the i386, we have |
| 843 | to provide a sane value, even though this register wasn't |
| 844 | saved. Assume we can get it from NEXT_FRAME. */ |
| 845 | frame_unwind_register (next_frame, regnum, valuep); |
| 846 | } |
| 847 | break; |
| 848 | |
| 849 | case DWARF2_FRAME_REG_SAVED_OFFSET: |
| 850 | *optimizedp = 0; |
| 851 | *lvalp = lval_memory; |
| 852 | *addrp = cache->cfa + cache->reg[regnum].loc.offset; |
| 853 | *realnump = -1; |
| 854 | if (valuep) |
| 855 | { |
| 856 | /* Read the value in from memory. */ |
| 857 | read_memory (*addrp, valuep, register_size (gdbarch, regnum)); |
| 858 | } |
| 859 | break; |
| 860 | |
| 861 | case DWARF2_FRAME_REG_SAVED_REG: |
| 862 | *optimizedp = 0; |
| 863 | *lvalp = lval_register; |
| 864 | *addrp = 0; |
| 865 | *realnump = DWARF2_REG_TO_REGNUM (cache->reg[regnum].loc.reg); |
| 866 | if (valuep) |
| 867 | frame_unwind_register (next_frame, (*realnump), valuep); |
| 868 | break; |
| 869 | |
| 870 | case DWARF2_FRAME_REG_SAVED_EXP: |
| 871 | *optimizedp = 0; |
| 872 | *lvalp = lval_memory; |
| 873 | *addrp = execute_stack_op (cache->reg[regnum].loc.exp, |
| 874 | cache->reg[regnum].exp_len, |
| 875 | next_frame, cache->cfa); |
| 876 | *realnump = -1; |
| 877 | if (valuep) |
| 878 | { |
| 879 | /* Read the value in from memory. */ |
| 880 | read_memory (*addrp, valuep, register_size (gdbarch, regnum)); |
| 881 | } |
| 882 | break; |
| 883 | |
| 884 | case DWARF2_FRAME_REG_UNSPECIFIED: |
| 885 | /* GCC, in its infinite wisdom decided to not provide unwind |
| 886 | information for registers that are "same value". Since |
| 887 | DWARF2 (3 draft 7) doesn't define such behavior, said |
| 888 | registers are actually undefined (which is different to CFI |
| 889 | "undefined"). Code above issues a complaint about this. |
| 890 | Here just fudge the books, assume GCC, and that the value is |
| 891 | more inner on the stack. */ |
| 892 | *optimizedp = 0; |
| 893 | *lvalp = lval_register; |
| 894 | *addrp = 0; |
| 895 | *realnump = regnum; |
| 896 | if (valuep) |
| 897 | frame_unwind_register (next_frame, (*realnump), valuep); |
| 898 | break; |
| 899 | |
| 900 | case DWARF2_FRAME_REG_SAME_VALUE: |
| 901 | *optimizedp = 0; |
| 902 | *lvalp = lval_register; |
| 903 | *addrp = 0; |
| 904 | *realnump = regnum; |
| 905 | if (valuep) |
| 906 | frame_unwind_register (next_frame, (*realnump), valuep); |
| 907 | break; |
| 908 | |
| 909 | case DWARF2_FRAME_REG_CFA: |
| 910 | *optimizedp = 0; |
| 911 | *lvalp = not_lval; |
| 912 | *addrp = 0; |
| 913 | *realnump = -1; |
| 914 | if (valuep) |
| 915 | { |
| 916 | /* Store the value. */ |
| 917 | store_typed_address (valuep, builtin_type_void_data_ptr, cache->cfa); |
| 918 | } |
| 919 | break; |
| 920 | |
| 921 | case DWARF2_FRAME_REG_RA_OFFSET: |
| 922 | *optimizedp = 0; |
| 923 | *lvalp = not_lval; |
| 924 | *addrp = 0; |
| 925 | *realnump = -1; |
| 926 | if (valuep) |
| 927 | { |
| 928 | CORE_ADDR pc = cache->reg[regnum].loc.offset; |
| 929 | |
| 930 | regnum = DWARF2_REG_TO_REGNUM (cache->retaddr_reg.loc.reg); |
| 931 | pc += frame_unwind_register_unsigned (next_frame, regnum); |
| 932 | store_typed_address (valuep, builtin_type_void_func_ptr, pc); |
| 933 | } |
| 934 | break; |
| 935 | |
| 936 | default: |
| 937 | internal_error (__FILE__, __LINE__, _("Unknown register rule.")); |
| 938 | } |
| 939 | } |
| 940 | |
| 941 | static const struct frame_unwind dwarf2_frame_unwind = |
| 942 | { |
| 943 | NORMAL_FRAME, |
| 944 | dwarf2_frame_this_id, |
| 945 | dwarf2_frame_prev_register |
| 946 | }; |
| 947 | |
| 948 | static const struct frame_unwind dwarf2_signal_frame_unwind = |
| 949 | { |
| 950 | SIGTRAMP_FRAME, |
| 951 | dwarf2_frame_this_id, |
| 952 | dwarf2_frame_prev_register |
| 953 | }; |
| 954 | |
| 955 | const struct frame_unwind * |
| 956 | dwarf2_frame_sniffer (struct frame_info *next_frame) |
| 957 | { |
| 958 | /* Grab an address that is guarenteed to reside somewhere within the |
| 959 | function. frame_pc_unwind(), for a no-return next function, can |
| 960 | end up returning something past the end of this function's body. */ |
| 961 | CORE_ADDR block_addr = frame_unwind_address_in_block (next_frame); |
| 962 | if (!dwarf2_frame_find_fde (&block_addr)) |
| 963 | return NULL; |
| 964 | |
| 965 | /* On some targets, signal trampolines may have unwind information. |
| 966 | We need to recognize them so that we set the frame type |
| 967 | correctly. */ |
| 968 | |
| 969 | if (dwarf2_frame_signal_frame_p (get_frame_arch (next_frame), |
| 970 | next_frame)) |
| 971 | return &dwarf2_signal_frame_unwind; |
| 972 | |
| 973 | return &dwarf2_frame_unwind; |
| 974 | } |
| 975 | \f |
| 976 | |
| 977 | /* There is no explicitly defined relationship between the CFA and the |
| 978 | location of frame's local variables and arguments/parameters. |
| 979 | Therefore, frame base methods on this page should probably only be |
| 980 | used as a last resort, just to avoid printing total garbage as a |
| 981 | response to the "info frame" command. */ |
| 982 | |
| 983 | static CORE_ADDR |
| 984 | dwarf2_frame_base_address (struct frame_info *next_frame, void **this_cache) |
| 985 | { |
| 986 | struct dwarf2_frame_cache *cache = |
| 987 | dwarf2_frame_cache (next_frame, this_cache); |
| 988 | |
| 989 | return cache->cfa; |
| 990 | } |
| 991 | |
| 992 | static const struct frame_base dwarf2_frame_base = |
| 993 | { |
| 994 | &dwarf2_frame_unwind, |
| 995 | dwarf2_frame_base_address, |
| 996 | dwarf2_frame_base_address, |
| 997 | dwarf2_frame_base_address |
| 998 | }; |
| 999 | |
| 1000 | const struct frame_base * |
| 1001 | dwarf2_frame_base_sniffer (struct frame_info *next_frame) |
| 1002 | { |
| 1003 | CORE_ADDR pc = frame_pc_unwind (next_frame); |
| 1004 | if (dwarf2_frame_find_fde (&pc)) |
| 1005 | return &dwarf2_frame_base; |
| 1006 | |
| 1007 | return NULL; |
| 1008 | } |
| 1009 | \f |
| 1010 | /* A minimal decoding of DWARF2 compilation units. We only decode |
| 1011 | what's needed to get to the call frame information. */ |
| 1012 | |
| 1013 | struct comp_unit |
| 1014 | { |
| 1015 | /* Keep the bfd convenient. */ |
| 1016 | bfd *abfd; |
| 1017 | |
| 1018 | struct objfile *objfile; |
| 1019 | |
| 1020 | /* Linked list of CIEs for this object. */ |
| 1021 | struct dwarf2_cie *cie; |
| 1022 | |
| 1023 | /* Pointer to the .debug_frame section loaded into memory. */ |
| 1024 | gdb_byte *dwarf_frame_buffer; |
| 1025 | |
| 1026 | /* Length of the loaded .debug_frame section. */ |
| 1027 | unsigned long dwarf_frame_size; |
| 1028 | |
| 1029 | /* Pointer to the .debug_frame section. */ |
| 1030 | asection *dwarf_frame_section; |
| 1031 | |
| 1032 | /* Base for DW_EH_PE_datarel encodings. */ |
| 1033 | bfd_vma dbase; |
| 1034 | |
| 1035 | /* Base for DW_EH_PE_textrel encodings. */ |
| 1036 | bfd_vma tbase; |
| 1037 | }; |
| 1038 | |
| 1039 | const struct objfile_data *dwarf2_frame_objfile_data; |
| 1040 | |
| 1041 | static unsigned int |
| 1042 | read_1_byte (bfd *abfd, gdb_byte *buf) |
| 1043 | { |
| 1044 | return bfd_get_8 (abfd, buf); |
| 1045 | } |
| 1046 | |
| 1047 | static unsigned int |
| 1048 | read_4_bytes (bfd *abfd, gdb_byte *buf) |
| 1049 | { |
| 1050 | return bfd_get_32 (abfd, buf); |
| 1051 | } |
| 1052 | |
| 1053 | static ULONGEST |
| 1054 | read_8_bytes (bfd *abfd, gdb_byte *buf) |
| 1055 | { |
| 1056 | return bfd_get_64 (abfd, buf); |
| 1057 | } |
| 1058 | |
| 1059 | static ULONGEST |
| 1060 | read_unsigned_leb128 (bfd *abfd, gdb_byte *buf, unsigned int *bytes_read_ptr) |
| 1061 | { |
| 1062 | ULONGEST result; |
| 1063 | unsigned int num_read; |
| 1064 | int shift; |
| 1065 | gdb_byte byte; |
| 1066 | |
| 1067 | result = 0; |
| 1068 | shift = 0; |
| 1069 | num_read = 0; |
| 1070 | |
| 1071 | do |
| 1072 | { |
| 1073 | byte = bfd_get_8 (abfd, (bfd_byte *) buf); |
| 1074 | buf++; |
| 1075 | num_read++; |
| 1076 | result |= ((byte & 0x7f) << shift); |
| 1077 | shift += 7; |
| 1078 | } |
| 1079 | while (byte & 0x80); |
| 1080 | |
| 1081 | *bytes_read_ptr = num_read; |
| 1082 | |
| 1083 | return result; |
| 1084 | } |
| 1085 | |
| 1086 | static LONGEST |
| 1087 | read_signed_leb128 (bfd *abfd, gdb_byte *buf, unsigned int *bytes_read_ptr) |
| 1088 | { |
| 1089 | LONGEST result; |
| 1090 | int shift; |
| 1091 | unsigned int num_read; |
| 1092 | gdb_byte byte; |
| 1093 | |
| 1094 | result = 0; |
| 1095 | shift = 0; |
| 1096 | num_read = 0; |
| 1097 | |
| 1098 | do |
| 1099 | { |
| 1100 | byte = bfd_get_8 (abfd, (bfd_byte *) buf); |
| 1101 | buf++; |
| 1102 | num_read++; |
| 1103 | result |= ((byte & 0x7f) << shift); |
| 1104 | shift += 7; |
| 1105 | } |
| 1106 | while (byte & 0x80); |
| 1107 | |
| 1108 | if ((shift < 32) && (byte & 0x40)) |
| 1109 | result |= -(1 << shift); |
| 1110 | |
| 1111 | *bytes_read_ptr = num_read; |
| 1112 | |
| 1113 | return result; |
| 1114 | } |
| 1115 | |
| 1116 | static ULONGEST |
| 1117 | read_initial_length (bfd *abfd, gdb_byte *buf, unsigned int *bytes_read_ptr) |
| 1118 | { |
| 1119 | LONGEST result; |
| 1120 | |
| 1121 | result = bfd_get_32 (abfd, buf); |
| 1122 | if (result == 0xffffffff) |
| 1123 | { |
| 1124 | result = bfd_get_64 (abfd, buf + 4); |
| 1125 | *bytes_read_ptr = 12; |
| 1126 | } |
| 1127 | else |
| 1128 | *bytes_read_ptr = 4; |
| 1129 | |
| 1130 | return result; |
| 1131 | } |
| 1132 | \f |
| 1133 | |
| 1134 | /* Pointer encoding helper functions. */ |
| 1135 | |
| 1136 | /* GCC supports exception handling based on DWARF2 CFI. However, for |
| 1137 | technical reasons, it encodes addresses in its FDE's in a different |
| 1138 | way. Several "pointer encodings" are supported. The encoding |
| 1139 | that's used for a particular FDE is determined by the 'R' |
| 1140 | augmentation in the associated CIE. The argument of this |
| 1141 | augmentation is a single byte. |
| 1142 | |
| 1143 | The address can be encoded as 2 bytes, 4 bytes, 8 bytes, or as a |
| 1144 | LEB128. This is encoded in bits 0, 1 and 2. Bit 3 encodes whether |
| 1145 | the address is signed or unsigned. Bits 4, 5 and 6 encode how the |
| 1146 | address should be interpreted (absolute, relative to the current |
| 1147 | position in the FDE, ...). Bit 7, indicates that the address |
| 1148 | should be dereferenced. */ |
| 1149 | |
| 1150 | static gdb_byte |
| 1151 | encoding_for_size (unsigned int size) |
| 1152 | { |
| 1153 | switch (size) |
| 1154 | { |
| 1155 | case 2: |
| 1156 | return DW_EH_PE_udata2; |
| 1157 | case 4: |
| 1158 | return DW_EH_PE_udata4; |
| 1159 | case 8: |
| 1160 | return DW_EH_PE_udata8; |
| 1161 | default: |
| 1162 | internal_error (__FILE__, __LINE__, _("Unsupported address size")); |
| 1163 | } |
| 1164 | } |
| 1165 | |
| 1166 | static unsigned int |
| 1167 | size_of_encoded_value (gdb_byte encoding) |
| 1168 | { |
| 1169 | if (encoding == DW_EH_PE_omit) |
| 1170 | return 0; |
| 1171 | |
| 1172 | switch (encoding & 0x07) |
| 1173 | { |
| 1174 | case DW_EH_PE_absptr: |
| 1175 | return TYPE_LENGTH (builtin_type_void_data_ptr); |
| 1176 | case DW_EH_PE_udata2: |
| 1177 | return 2; |
| 1178 | case DW_EH_PE_udata4: |
| 1179 | return 4; |
| 1180 | case DW_EH_PE_udata8: |
| 1181 | return 8; |
| 1182 | default: |
| 1183 | internal_error (__FILE__, __LINE__, _("Invalid or unsupported encoding")); |
| 1184 | } |
| 1185 | } |
| 1186 | |
| 1187 | static CORE_ADDR |
| 1188 | read_encoded_value (struct comp_unit *unit, gdb_byte encoding, |
| 1189 | gdb_byte *buf, unsigned int *bytes_read_ptr) |
| 1190 | { |
| 1191 | int ptr_len = size_of_encoded_value (DW_EH_PE_absptr); |
| 1192 | ptrdiff_t offset; |
| 1193 | CORE_ADDR base; |
| 1194 | |
| 1195 | /* GCC currently doesn't generate DW_EH_PE_indirect encodings for |
| 1196 | FDE's. */ |
| 1197 | if (encoding & DW_EH_PE_indirect) |
| 1198 | internal_error (__FILE__, __LINE__, |
| 1199 | _("Unsupported encoding: DW_EH_PE_indirect")); |
| 1200 | |
| 1201 | *bytes_read_ptr = 0; |
| 1202 | |
| 1203 | switch (encoding & 0x70) |
| 1204 | { |
| 1205 | case DW_EH_PE_absptr: |
| 1206 | base = 0; |
| 1207 | break; |
| 1208 | case DW_EH_PE_pcrel: |
| 1209 | base = bfd_get_section_vma (unit->bfd, unit->dwarf_frame_section); |
| 1210 | base += (buf - unit->dwarf_frame_buffer); |
| 1211 | break; |
| 1212 | case DW_EH_PE_datarel: |
| 1213 | base = unit->dbase; |
| 1214 | break; |
| 1215 | case DW_EH_PE_textrel: |
| 1216 | base = unit->tbase; |
| 1217 | break; |
| 1218 | case DW_EH_PE_funcrel: |
| 1219 | /* FIXME: kettenis/20040501: For now just pretend |
| 1220 | DW_EH_PE_funcrel is equivalent to DW_EH_PE_absptr. For |
| 1221 | reading the initial location of an FDE it should be treated |
| 1222 | as such, and currently that's the only place where this code |
| 1223 | is used. */ |
| 1224 | base = 0; |
| 1225 | break; |
| 1226 | case DW_EH_PE_aligned: |
| 1227 | base = 0; |
| 1228 | offset = buf - unit->dwarf_frame_buffer; |
| 1229 | if ((offset % ptr_len) != 0) |
| 1230 | { |
| 1231 | *bytes_read_ptr = ptr_len - (offset % ptr_len); |
| 1232 | buf += *bytes_read_ptr; |
| 1233 | } |
| 1234 | break; |
| 1235 | default: |
| 1236 | internal_error (__FILE__, __LINE__, _("Invalid or unsupported encoding")); |
| 1237 | } |
| 1238 | |
| 1239 | if ((encoding & 0x07) == 0x00) |
| 1240 | encoding |= encoding_for_size (ptr_len); |
| 1241 | |
| 1242 | switch (encoding & 0x0f) |
| 1243 | { |
| 1244 | case DW_EH_PE_uleb128: |
| 1245 | { |
| 1246 | ULONGEST value; |
| 1247 | gdb_byte *end_buf = buf + (sizeof (value) + 1) * 8 / 7; |
| 1248 | *bytes_read_ptr += read_uleb128 (buf, end_buf, &value) - buf; |
| 1249 | return base + value; |
| 1250 | } |
| 1251 | case DW_EH_PE_udata2: |
| 1252 | *bytes_read_ptr += 2; |
| 1253 | return (base + bfd_get_16 (unit->abfd, (bfd_byte *) buf)); |
| 1254 | case DW_EH_PE_udata4: |
| 1255 | *bytes_read_ptr += 4; |
| 1256 | return (base + bfd_get_32 (unit->abfd, (bfd_byte *) buf)); |
| 1257 | case DW_EH_PE_udata8: |
| 1258 | *bytes_read_ptr += 8; |
| 1259 | return (base + bfd_get_64 (unit->abfd, (bfd_byte *) buf)); |
| 1260 | case DW_EH_PE_sleb128: |
| 1261 | { |
| 1262 | LONGEST value; |
| 1263 | gdb_byte *end_buf = buf + (sizeof (value) + 1) * 8 / 7; |
| 1264 | *bytes_read_ptr += read_sleb128 (buf, end_buf, &value) - buf; |
| 1265 | return base + value; |
| 1266 | } |
| 1267 | case DW_EH_PE_sdata2: |
| 1268 | *bytes_read_ptr += 2; |
| 1269 | return (base + bfd_get_signed_16 (unit->abfd, (bfd_byte *) buf)); |
| 1270 | case DW_EH_PE_sdata4: |
| 1271 | *bytes_read_ptr += 4; |
| 1272 | return (base + bfd_get_signed_32 (unit->abfd, (bfd_byte *) buf)); |
| 1273 | case DW_EH_PE_sdata8: |
| 1274 | *bytes_read_ptr += 8; |
| 1275 | return (base + bfd_get_signed_64 (unit->abfd, (bfd_byte *) buf)); |
| 1276 | default: |
| 1277 | internal_error (__FILE__, __LINE__, _("Invalid or unsupported encoding")); |
| 1278 | } |
| 1279 | } |
| 1280 | \f |
| 1281 | |
| 1282 | /* GCC uses a single CIE for all FDEs in a .debug_frame section. |
| 1283 | That's why we use a simple linked list here. */ |
| 1284 | |
| 1285 | static struct dwarf2_cie * |
| 1286 | find_cie (struct comp_unit *unit, ULONGEST cie_pointer) |
| 1287 | { |
| 1288 | struct dwarf2_cie *cie = unit->cie; |
| 1289 | |
| 1290 | while (cie) |
| 1291 | { |
| 1292 | if (cie->cie_pointer == cie_pointer) |
| 1293 | return cie; |
| 1294 | |
| 1295 | cie = cie->next; |
| 1296 | } |
| 1297 | |
| 1298 | return NULL; |
| 1299 | } |
| 1300 | |
| 1301 | static void |
| 1302 | add_cie (struct comp_unit *unit, struct dwarf2_cie *cie) |
| 1303 | { |
| 1304 | cie->next = unit->cie; |
| 1305 | unit->cie = cie; |
| 1306 | } |
| 1307 | |
| 1308 | /* Find the FDE for *PC. Return a pointer to the FDE, and store the |
| 1309 | inital location associated with it into *PC. */ |
| 1310 | |
| 1311 | static struct dwarf2_fde * |
| 1312 | dwarf2_frame_find_fde (CORE_ADDR *pc) |
| 1313 | { |
| 1314 | struct objfile *objfile; |
| 1315 | |
| 1316 | ALL_OBJFILES (objfile) |
| 1317 | { |
| 1318 | struct dwarf2_fde *fde; |
| 1319 | CORE_ADDR offset; |
| 1320 | |
| 1321 | fde = objfile_data (objfile, dwarf2_frame_objfile_data); |
| 1322 | if (fde == NULL) |
| 1323 | continue; |
| 1324 | |
| 1325 | gdb_assert (objfile->section_offsets); |
| 1326 | offset = ANOFFSET (objfile->section_offsets, SECT_OFF_TEXT (objfile)); |
| 1327 | |
| 1328 | while (fde) |
| 1329 | { |
| 1330 | if (*pc >= fde->initial_location + offset |
| 1331 | && *pc < fde->initial_location + offset + fde->address_range) |
| 1332 | { |
| 1333 | *pc = fde->initial_location + offset; |
| 1334 | return fde; |
| 1335 | } |
| 1336 | |
| 1337 | fde = fde->next; |
| 1338 | } |
| 1339 | } |
| 1340 | |
| 1341 | return NULL; |
| 1342 | } |
| 1343 | |
| 1344 | static void |
| 1345 | add_fde (struct comp_unit *unit, struct dwarf2_fde *fde) |
| 1346 | { |
| 1347 | fde->next = objfile_data (unit->objfile, dwarf2_frame_objfile_data); |
| 1348 | set_objfile_data (unit->objfile, dwarf2_frame_objfile_data, fde); |
| 1349 | } |
| 1350 | |
| 1351 | #ifdef CC_HAS_LONG_LONG |
| 1352 | #define DW64_CIE_ID 0xffffffffffffffffULL |
| 1353 | #else |
| 1354 | #define DW64_CIE_ID ~0 |
| 1355 | #endif |
| 1356 | |
| 1357 | static gdb_byte *decode_frame_entry (struct comp_unit *unit, gdb_byte *start, |
| 1358 | int eh_frame_p); |
| 1359 | |
| 1360 | /* Decode the next CIE or FDE. Return NULL if invalid input, otherwise |
| 1361 | the next byte to be processed. */ |
| 1362 | static gdb_byte * |
| 1363 | decode_frame_entry_1 (struct comp_unit *unit, gdb_byte *start, int eh_frame_p) |
| 1364 | { |
| 1365 | gdb_byte *buf, *end; |
| 1366 | LONGEST length; |
| 1367 | unsigned int bytes_read; |
| 1368 | int dwarf64_p; |
| 1369 | ULONGEST cie_id; |
| 1370 | ULONGEST cie_pointer; |
| 1371 | |
| 1372 | buf = start; |
| 1373 | length = read_initial_length (unit->abfd, buf, &bytes_read); |
| 1374 | buf += bytes_read; |
| 1375 | end = buf + length; |
| 1376 | |
| 1377 | /* Are we still within the section? */ |
| 1378 | if (end > unit->dwarf_frame_buffer + unit->dwarf_frame_size) |
| 1379 | return NULL; |
| 1380 | |
| 1381 | if (length == 0) |
| 1382 | return end; |
| 1383 | |
| 1384 | /* Distinguish between 32 and 64-bit encoded frame info. */ |
| 1385 | dwarf64_p = (bytes_read == 12); |
| 1386 | |
| 1387 | /* In a .eh_frame section, zero is used to distinguish CIEs from FDEs. */ |
| 1388 | if (eh_frame_p) |
| 1389 | cie_id = 0; |
| 1390 | else if (dwarf64_p) |
| 1391 | cie_id = DW64_CIE_ID; |
| 1392 | else |
| 1393 | cie_id = DW_CIE_ID; |
| 1394 | |
| 1395 | if (dwarf64_p) |
| 1396 | { |
| 1397 | cie_pointer = read_8_bytes (unit->abfd, buf); |
| 1398 | buf += 8; |
| 1399 | } |
| 1400 | else |
| 1401 | { |
| 1402 | cie_pointer = read_4_bytes (unit->abfd, buf); |
| 1403 | buf += 4; |
| 1404 | } |
| 1405 | |
| 1406 | if (cie_pointer == cie_id) |
| 1407 | { |
| 1408 | /* This is a CIE. */ |
| 1409 | struct dwarf2_cie *cie; |
| 1410 | char *augmentation; |
| 1411 | unsigned int cie_version; |
| 1412 | |
| 1413 | /* Record the offset into the .debug_frame section of this CIE. */ |
| 1414 | cie_pointer = start - unit->dwarf_frame_buffer; |
| 1415 | |
| 1416 | /* Check whether we've already read it. */ |
| 1417 | if (find_cie (unit, cie_pointer)) |
| 1418 | return end; |
| 1419 | |
| 1420 | cie = (struct dwarf2_cie *) |
| 1421 | obstack_alloc (&unit->objfile->objfile_obstack, |
| 1422 | sizeof (struct dwarf2_cie)); |
| 1423 | cie->initial_instructions = NULL; |
| 1424 | cie->cie_pointer = cie_pointer; |
| 1425 | |
| 1426 | /* The encoding for FDE's in a normal .debug_frame section |
| 1427 | depends on the target address size. */ |
| 1428 | cie->encoding = DW_EH_PE_absptr; |
| 1429 | |
| 1430 | /* Check version number. */ |
| 1431 | cie_version = read_1_byte (unit->abfd, buf); |
| 1432 | if (cie_version != 1 && cie_version != 3) |
| 1433 | return NULL; |
| 1434 | buf += 1; |
| 1435 | |
| 1436 | /* Interpret the interesting bits of the augmentation. */ |
| 1437 | augmentation = (char *) buf; |
| 1438 | buf += (strlen (augmentation) + 1); |
| 1439 | |
| 1440 | /* The GCC 2.x "eh" augmentation has a pointer immediately |
| 1441 | following the augmentation string, so it must be handled |
| 1442 | first. */ |
| 1443 | if (augmentation[0] == 'e' && augmentation[1] == 'h') |
| 1444 | { |
| 1445 | /* Skip. */ |
| 1446 | buf += TYPE_LENGTH (builtin_type_void_data_ptr); |
| 1447 | augmentation += 2; |
| 1448 | } |
| 1449 | |
| 1450 | cie->code_alignment_factor = |
| 1451 | read_unsigned_leb128 (unit->abfd, buf, &bytes_read); |
| 1452 | buf += bytes_read; |
| 1453 | |
| 1454 | cie->data_alignment_factor = |
| 1455 | read_signed_leb128 (unit->abfd, buf, &bytes_read); |
| 1456 | buf += bytes_read; |
| 1457 | |
| 1458 | if (cie_version == 1) |
| 1459 | { |
| 1460 | cie->return_address_register = read_1_byte (unit->abfd, buf); |
| 1461 | bytes_read = 1; |
| 1462 | } |
| 1463 | else |
| 1464 | cie->return_address_register = read_unsigned_leb128 (unit->abfd, buf, |
| 1465 | &bytes_read); |
| 1466 | buf += bytes_read; |
| 1467 | |
| 1468 | cie->saw_z_augmentation = (*augmentation == 'z'); |
| 1469 | if (cie->saw_z_augmentation) |
| 1470 | { |
| 1471 | ULONGEST length; |
| 1472 | |
| 1473 | length = read_unsigned_leb128 (unit->abfd, buf, &bytes_read); |
| 1474 | buf += bytes_read; |
| 1475 | if (buf > end) |
| 1476 | return NULL; |
| 1477 | cie->initial_instructions = buf + length; |
| 1478 | augmentation++; |
| 1479 | } |
| 1480 | |
| 1481 | while (*augmentation) |
| 1482 | { |
| 1483 | /* "L" indicates a byte showing how the LSDA pointer is encoded. */ |
| 1484 | if (*augmentation == 'L') |
| 1485 | { |
| 1486 | /* Skip. */ |
| 1487 | buf++; |
| 1488 | augmentation++; |
| 1489 | } |
| 1490 | |
| 1491 | /* "R" indicates a byte indicating how FDE addresses are encoded. */ |
| 1492 | else if (*augmentation == 'R') |
| 1493 | { |
| 1494 | cie->encoding = *buf++; |
| 1495 | augmentation++; |
| 1496 | } |
| 1497 | |
| 1498 | /* "P" indicates a personality routine in the CIE augmentation. */ |
| 1499 | else if (*augmentation == 'P') |
| 1500 | { |
| 1501 | /* Skip. Avoid indirection since we throw away the result. */ |
| 1502 | gdb_byte encoding = (*buf++) & ~DW_EH_PE_indirect; |
| 1503 | read_encoded_value (unit, encoding, buf, &bytes_read); |
| 1504 | buf += bytes_read; |
| 1505 | augmentation++; |
| 1506 | } |
| 1507 | |
| 1508 | /* Otherwise we have an unknown augmentation. |
| 1509 | Bail out unless we saw a 'z' prefix. */ |
| 1510 | else |
| 1511 | { |
| 1512 | if (cie->initial_instructions == NULL) |
| 1513 | return end; |
| 1514 | |
| 1515 | /* Skip unknown augmentations. */ |
| 1516 | buf = cie->initial_instructions; |
| 1517 | break; |
| 1518 | } |
| 1519 | } |
| 1520 | |
| 1521 | cie->initial_instructions = buf; |
| 1522 | cie->end = end; |
| 1523 | |
| 1524 | add_cie (unit, cie); |
| 1525 | } |
| 1526 | else |
| 1527 | { |
| 1528 | /* This is a FDE. */ |
| 1529 | struct dwarf2_fde *fde; |
| 1530 | |
| 1531 | /* In an .eh_frame section, the CIE pointer is the delta between the |
| 1532 | address within the FDE where the CIE pointer is stored and the |
| 1533 | address of the CIE. Convert it to an offset into the .eh_frame |
| 1534 | section. */ |
| 1535 | if (eh_frame_p) |
| 1536 | { |
| 1537 | cie_pointer = buf - unit->dwarf_frame_buffer - cie_pointer; |
| 1538 | cie_pointer -= (dwarf64_p ? 8 : 4); |
| 1539 | } |
| 1540 | |
| 1541 | /* In either case, validate the result is still within the section. */ |
| 1542 | if (cie_pointer >= unit->dwarf_frame_size) |
| 1543 | return NULL; |
| 1544 | |
| 1545 | fde = (struct dwarf2_fde *) |
| 1546 | obstack_alloc (&unit->objfile->objfile_obstack, |
| 1547 | sizeof (struct dwarf2_fde)); |
| 1548 | fde->cie = find_cie (unit, cie_pointer); |
| 1549 | if (fde->cie == NULL) |
| 1550 | { |
| 1551 | decode_frame_entry (unit, unit->dwarf_frame_buffer + cie_pointer, |
| 1552 | eh_frame_p); |
| 1553 | fde->cie = find_cie (unit, cie_pointer); |
| 1554 | } |
| 1555 | |
| 1556 | gdb_assert (fde->cie != NULL); |
| 1557 | |
| 1558 | fde->initial_location = |
| 1559 | read_encoded_value (unit, fde->cie->encoding, buf, &bytes_read); |
| 1560 | buf += bytes_read; |
| 1561 | |
| 1562 | fde->address_range = |
| 1563 | read_encoded_value (unit, fde->cie->encoding & 0x0f, buf, &bytes_read); |
| 1564 | buf += bytes_read; |
| 1565 | |
| 1566 | /* A 'z' augmentation in the CIE implies the presence of an |
| 1567 | augmentation field in the FDE as well. The only thing known |
| 1568 | to be in here at present is the LSDA entry for EH. So we |
| 1569 | can skip the whole thing. */ |
| 1570 | if (fde->cie->saw_z_augmentation) |
| 1571 | { |
| 1572 | ULONGEST length; |
| 1573 | |
| 1574 | length = read_unsigned_leb128 (unit->abfd, buf, &bytes_read); |
| 1575 | buf += bytes_read + length; |
| 1576 | if (buf > end) |
| 1577 | return NULL; |
| 1578 | } |
| 1579 | |
| 1580 | fde->instructions = buf; |
| 1581 | fde->end = end; |
| 1582 | |
| 1583 | add_fde (unit, fde); |
| 1584 | } |
| 1585 | |
| 1586 | return end; |
| 1587 | } |
| 1588 | |
| 1589 | /* Read a CIE or FDE in BUF and decode it. */ |
| 1590 | static gdb_byte * |
| 1591 | decode_frame_entry (struct comp_unit *unit, gdb_byte *start, int eh_frame_p) |
| 1592 | { |
| 1593 | enum { NONE, ALIGN4, ALIGN8, FAIL } workaround = NONE; |
| 1594 | gdb_byte *ret; |
| 1595 | const char *msg; |
| 1596 | ptrdiff_t start_offset; |
| 1597 | |
| 1598 | while (1) |
| 1599 | { |
| 1600 | ret = decode_frame_entry_1 (unit, start, eh_frame_p); |
| 1601 | if (ret != NULL) |
| 1602 | break; |
| 1603 | |
| 1604 | /* We have corrupt input data of some form. */ |
| 1605 | |
| 1606 | /* ??? Try, weakly, to work around compiler/assembler/linker bugs |
| 1607 | and mismatches wrt padding and alignment of debug sections. */ |
| 1608 | /* Note that there is no requirement in the standard for any |
| 1609 | alignment at all in the frame unwind sections. Testing for |
| 1610 | alignment before trying to interpret data would be incorrect. |
| 1611 | |
| 1612 | However, GCC traditionally arranged for frame sections to be |
| 1613 | sized such that the FDE length and CIE fields happen to be |
| 1614 | aligned (in theory, for performance). This, unfortunately, |
| 1615 | was done with .align directives, which had the side effect of |
| 1616 | forcing the section to be aligned by the linker. |
| 1617 | |
| 1618 | This becomes a problem when you have some other producer that |
| 1619 | creates frame sections that are not as strictly aligned. That |
| 1620 | produces a hole in the frame info that gets filled by the |
| 1621 | linker with zeros. |
| 1622 | |
| 1623 | The GCC behaviour is arguably a bug, but it's effectively now |
| 1624 | part of the ABI, so we're now stuck with it, at least at the |
| 1625 | object file level. A smart linker may decide, in the process |
| 1626 | of compressing duplicate CIE information, that it can rewrite |
| 1627 | the entire output section without this extra padding. */ |
| 1628 | |
| 1629 | start_offset = start - unit->dwarf_frame_buffer; |
| 1630 | if (workaround < ALIGN4 && (start_offset & 3) != 0) |
| 1631 | { |
| 1632 | start += 4 - (start_offset & 3); |
| 1633 | workaround = ALIGN4; |
| 1634 | continue; |
| 1635 | } |
| 1636 | if (workaround < ALIGN8 && (start_offset & 7) != 0) |
| 1637 | { |
| 1638 | start += 8 - (start_offset & 7); |
| 1639 | workaround = ALIGN8; |
| 1640 | continue; |
| 1641 | } |
| 1642 | |
| 1643 | /* Nothing left to try. Arrange to return as if we've consumed |
| 1644 | the entire input section. Hopefully we'll get valid info from |
| 1645 | the other of .debug_frame/.eh_frame. */ |
| 1646 | workaround = FAIL; |
| 1647 | ret = unit->dwarf_frame_buffer + unit->dwarf_frame_size; |
| 1648 | break; |
| 1649 | } |
| 1650 | |
| 1651 | switch (workaround) |
| 1652 | { |
| 1653 | case NONE: |
| 1654 | break; |
| 1655 | |
| 1656 | case ALIGN4: |
| 1657 | complaint (&symfile_complaints, |
| 1658 | _("Corrupt data in %s:%s; align 4 workaround apparently succeeded"), |
| 1659 | unit->dwarf_frame_section->owner->filename, |
| 1660 | unit->dwarf_frame_section->name); |
| 1661 | break; |
| 1662 | |
| 1663 | case ALIGN8: |
| 1664 | complaint (&symfile_complaints, |
| 1665 | _("Corrupt data in %s:%s; align 8 workaround apparently succeeded"), |
| 1666 | unit->dwarf_frame_section->owner->filename, |
| 1667 | unit->dwarf_frame_section->name); |
| 1668 | break; |
| 1669 | |
| 1670 | default: |
| 1671 | complaint (&symfile_complaints, |
| 1672 | _("Corrupt data in %s:%s"), |
| 1673 | unit->dwarf_frame_section->owner->filename, |
| 1674 | unit->dwarf_frame_section->name); |
| 1675 | break; |
| 1676 | } |
| 1677 | |
| 1678 | return ret; |
| 1679 | } |
| 1680 | \f |
| 1681 | |
| 1682 | /* FIXME: kettenis/20030504: This still needs to be integrated with |
| 1683 | dwarf2read.c in a better way. */ |
| 1684 | |
| 1685 | /* Imported from dwarf2read.c. */ |
| 1686 | extern asection *dwarf_frame_section; |
| 1687 | extern asection *dwarf_eh_frame_section; |
| 1688 | |
| 1689 | /* Imported from dwarf2read.c. */ |
| 1690 | extern char *dwarf2_read_section (struct objfile *objfile, asection *sectp); |
| 1691 | |
| 1692 | void |
| 1693 | dwarf2_build_frame_info (struct objfile *objfile) |
| 1694 | { |
| 1695 | struct comp_unit unit; |
| 1696 | gdb_byte *frame_ptr; |
| 1697 | |
| 1698 | /* Build a minimal decoding of the DWARF2 compilation unit. */ |
| 1699 | unit.abfd = objfile->obfd; |
| 1700 | unit.objfile = objfile; |
| 1701 | unit.dbase = 0; |
| 1702 | unit.tbase = 0; |
| 1703 | |
| 1704 | /* First add the information from the .eh_frame section. That way, |
| 1705 | the FDEs from that section are searched last. */ |
| 1706 | if (dwarf_eh_frame_section) |
| 1707 | { |
| 1708 | asection *got, *txt; |
| 1709 | |
| 1710 | unit.cie = NULL; |
| 1711 | unit.dwarf_frame_buffer = dwarf2_read_section (objfile, |
| 1712 | dwarf_eh_frame_section); |
| 1713 | |
| 1714 | unit.dwarf_frame_size = bfd_get_section_size (dwarf_eh_frame_section); |
| 1715 | unit.dwarf_frame_section = dwarf_eh_frame_section; |
| 1716 | |
| 1717 | /* FIXME: kettenis/20030602: This is the DW_EH_PE_datarel base |
| 1718 | that is used for the i386/amd64 target, which currently is |
| 1719 | the only target in GCC that supports/uses the |
| 1720 | DW_EH_PE_datarel encoding. */ |
| 1721 | got = bfd_get_section_by_name (unit.abfd, ".got"); |
| 1722 | if (got) |
| 1723 | unit.dbase = got->vma; |
| 1724 | |
| 1725 | /* GCC emits the DW_EH_PE_textrel encoding type on sh and ia64 |
| 1726 | so far. */ |
| 1727 | txt = bfd_get_section_by_name (unit.abfd, ".text"); |
| 1728 | if (txt) |
| 1729 | unit.tbase = txt->vma; |
| 1730 | |
| 1731 | frame_ptr = unit.dwarf_frame_buffer; |
| 1732 | while (frame_ptr < unit.dwarf_frame_buffer + unit.dwarf_frame_size) |
| 1733 | frame_ptr = decode_frame_entry (&unit, frame_ptr, 1); |
| 1734 | } |
| 1735 | |
| 1736 | if (dwarf_frame_section) |
| 1737 | { |
| 1738 | unit.cie = NULL; |
| 1739 | unit.dwarf_frame_buffer = dwarf2_read_section (objfile, |
| 1740 | dwarf_frame_section); |
| 1741 | unit.dwarf_frame_size = bfd_get_section_size (dwarf_frame_section); |
| 1742 | unit.dwarf_frame_section = dwarf_frame_section; |
| 1743 | |
| 1744 | frame_ptr = unit.dwarf_frame_buffer; |
| 1745 | while (frame_ptr < unit.dwarf_frame_buffer + unit.dwarf_frame_size) |
| 1746 | frame_ptr = decode_frame_entry (&unit, frame_ptr, 0); |
| 1747 | } |
| 1748 | } |
| 1749 | |
| 1750 | /* Provide a prototype to silence -Wmissing-prototypes. */ |
| 1751 | void _initialize_dwarf2_frame (void); |
| 1752 | |
| 1753 | void |
| 1754 | _initialize_dwarf2_frame (void) |
| 1755 | { |
| 1756 | dwarf2_frame_data = gdbarch_data_register_pre_init (dwarf2_frame_init); |
| 1757 | dwarf2_frame_objfile_data = register_objfile_data (); |
| 1758 | } |