1 /* Frame unwinder for frames with DWARF Call Frame Information.
3 Copyright (C) 2003-2019 Free Software Foundation, Inc.
5 Contributed by Mark Kettenis.
7 This file is part of GDB.
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.
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.
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/>. */
23 #include "dwarf2expr.h"
26 #include "frame-base.h"
27 #include "frame-unwind.h"
36 #include "complaints.h"
37 #include "dwarf2-frame.h"
38 #include "dwarf2read.h"
40 #include "dwarf2loc.h"
41 #include "dwarf2-frame-tailcall.h"
43 #include "common/selftest.h"
44 #include "selftest-arch.h"
49 /* Call Frame Information (CFI). */
51 /* Common Information Entry (CIE). */
55 /* Computation Unit for this CIE. */
56 struct comp_unit *unit;
58 /* Offset into the .debug_frame section where this CIE was found.
59 Used to identify this CIE. */
62 /* Constant that is factored out of all advance location
64 ULONGEST code_alignment_factor;
66 /* Constants that is factored out of all offset instructions. */
67 LONGEST data_alignment_factor;
69 /* Return address column. */
70 ULONGEST return_address_register;
72 /* Instruction sequence to initialize a register set. */
73 const gdb_byte *initial_instructions;
76 /* Saved augmentation, in case it's needed later. */
79 /* Encoding of addresses. */
82 /* Target address size in bytes. */
85 /* Target pointer size in bytes. */
88 /* True if a 'z' augmentation existed. */
89 unsigned char saw_z_augmentation;
91 /* True if an 'S' augmentation existed. */
92 unsigned char signal_frame;
94 /* The version recorded in the CIE. */
95 unsigned char version;
97 /* The segment size. */
98 unsigned char segment_size;
101 struct dwarf2_cie_table
104 struct dwarf2_cie **entries;
107 /* Frame Description Entry (FDE). */
111 /* CIE for this FDE. */
112 struct dwarf2_cie *cie;
114 /* First location associated with this FDE. */
115 CORE_ADDR initial_location;
117 /* Number of bytes of program instructions described by this FDE. */
118 CORE_ADDR address_range;
120 /* Instruction sequence. */
121 const gdb_byte *instructions;
124 /* True if this FDE is read from a .eh_frame instead of a .debug_frame
126 unsigned char eh_frame_p;
129 struct dwarf2_fde_table
132 struct dwarf2_fde **entries;
135 /* A minimal decoding of DWARF2 compilation units. We only decode
136 what's needed to get to the call frame information. */
140 /* Keep the bfd convenient. */
143 struct objfile *objfile;
145 /* Pointer to the .debug_frame section loaded into memory. */
146 const gdb_byte *dwarf_frame_buffer;
148 /* Length of the loaded .debug_frame section. */
149 bfd_size_type dwarf_frame_size;
151 /* Pointer to the .debug_frame section. */
152 asection *dwarf_frame_section;
154 /* Base for DW_EH_PE_datarel encodings. */
157 /* Base for DW_EH_PE_textrel encodings. */
161 static struct dwarf2_fde *dwarf2_frame_find_fde (CORE_ADDR *pc,
162 CORE_ADDR *out_offset);
164 static int dwarf2_frame_adjust_regnum (struct gdbarch *gdbarch, int regnum,
167 static CORE_ADDR read_encoded_value (struct comp_unit *unit, gdb_byte encoding,
168 int ptr_len, const gdb_byte *buf,
169 unsigned int *bytes_read_ptr,
170 CORE_ADDR func_base);
173 /* See dwarf2-frame.h. */
174 int dwarf2_frame_unwinders_enabled_p = 1;
176 /* Store the length the expression for the CFA in the `cfa_reg' field,
177 which is unused in that case. */
178 #define cfa_exp_len cfa_reg
180 dwarf2_frame_state::dwarf2_frame_state (CORE_ADDR pc_, struct dwarf2_cie *cie)
181 : pc (pc_), data_align (cie->data_alignment_factor),
182 code_align (cie->code_alignment_factor),
183 retaddr_column (cie->return_address_register)
188 /* Helper functions for execute_stack_op. */
191 read_addr_from_reg (struct frame_info *this_frame, int reg)
193 struct gdbarch *gdbarch = get_frame_arch (this_frame);
194 int regnum = dwarf_reg_to_regnum_or_error (gdbarch, reg);
196 return address_from_register (regnum, this_frame);
199 /* Execute the required actions for both the DW_CFA_restore and
200 DW_CFA_restore_extended instructions. */
202 dwarf2_restore_rule (struct gdbarch *gdbarch, ULONGEST reg_num,
203 struct dwarf2_frame_state *fs, int eh_frame_p)
207 reg = dwarf2_frame_adjust_regnum (gdbarch, reg_num, eh_frame_p);
208 fs->regs.alloc_regs (reg + 1);
210 /* Check if this register was explicitly initialized in the
211 CIE initial instructions. If not, default the rule to
213 if (reg < fs->initial.reg.size ())
214 fs->regs.reg[reg] = fs->initial.reg[reg];
216 fs->regs.reg[reg].how = DWARF2_FRAME_REG_UNSPECIFIED;
218 if (fs->regs.reg[reg].how == DWARF2_FRAME_REG_UNSPECIFIED)
220 int regnum = dwarf_reg_to_regnum (gdbarch, reg);
223 incomplete CFI data; DW_CFA_restore unspecified\n\
224 register %s (#%d) at %s"),
225 gdbarch_register_name (gdbarch, regnum), regnum,
226 paddress (gdbarch, fs->pc));
230 class dwarf_expr_executor : public dwarf_expr_context
234 struct frame_info *this_frame;
236 CORE_ADDR read_addr_from_reg (int reg) override
238 return ::read_addr_from_reg (this_frame, reg);
241 struct value *get_reg_value (struct type *type, int reg) override
243 struct gdbarch *gdbarch = get_frame_arch (this_frame);
244 int regnum = dwarf_reg_to_regnum_or_error (gdbarch, reg);
246 return value_from_register (type, regnum, this_frame);
249 void read_mem (gdb_byte *buf, CORE_ADDR addr, size_t len) override
251 read_memory (addr, buf, len);
254 void get_frame_base (const gdb_byte **start, size_t *length) override
256 invalid ("DW_OP_fbreg");
259 void push_dwarf_reg_entry_value (enum call_site_parameter_kind kind,
260 union call_site_parameter_u kind_u,
261 int deref_size) override
263 invalid ("DW_OP_entry_value");
266 CORE_ADDR get_object_address () override
268 invalid ("DW_OP_push_object_address");
271 CORE_ADDR get_frame_cfa () override
273 invalid ("DW_OP_call_frame_cfa");
276 CORE_ADDR get_tls_address (CORE_ADDR offset) override
278 invalid ("DW_OP_form_tls_address");
281 void dwarf_call (cu_offset die_offset) override
283 invalid ("DW_OP_call*");
286 struct value *dwarf_variable_value (sect_offset sect_off) override
288 invalid ("DW_OP_GNU_variable_value");
291 CORE_ADDR get_addr_index (unsigned int index) override
293 invalid ("DW_OP_GNU_addr_index");
298 void invalid (const char *op) ATTRIBUTE_NORETURN
300 error (_("%s is invalid in this context"), op);
305 execute_stack_op (const gdb_byte *exp, ULONGEST len, int addr_size,
306 CORE_ADDR offset, struct frame_info *this_frame,
307 CORE_ADDR initial, int initial_in_stack_memory)
311 dwarf_expr_executor ctx;
312 scoped_value_mark free_values;
314 ctx.this_frame = this_frame;
315 ctx.gdbarch = get_frame_arch (this_frame);
316 ctx.addr_size = addr_size;
317 ctx.ref_addr_size = -1;
320 ctx.push_address (initial, initial_in_stack_memory);
323 if (ctx.location == DWARF_VALUE_MEMORY)
324 result = ctx.fetch_address (0);
325 else if (ctx.location == DWARF_VALUE_REGISTER)
326 result = ctx.read_addr_from_reg (value_as_long (ctx.fetch (0)));
329 /* This is actually invalid DWARF, but if we ever do run across
330 it somehow, we might as well support it. So, instead, report
331 it as unimplemented. */
333 Not implemented: computing unwound register using explicit value operator"));
340 /* Execute FDE program from INSN_PTR possibly up to INSN_END or up to inferior
341 PC. Modify FS state accordingly. Return current INSN_PTR where the
342 execution has stopped, one can resume it on the next call. */
344 static const gdb_byte *
345 execute_cfa_program (struct dwarf2_fde *fde, const gdb_byte *insn_ptr,
346 const gdb_byte *insn_end, struct gdbarch *gdbarch,
347 CORE_ADDR pc, struct dwarf2_frame_state *fs)
349 int eh_frame_p = fde->eh_frame_p;
350 unsigned int bytes_read;
351 enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
353 while (insn_ptr < insn_end && fs->pc <= pc)
355 gdb_byte insn = *insn_ptr++;
359 if ((insn & 0xc0) == DW_CFA_advance_loc)
360 fs->pc += (insn & 0x3f) * fs->code_align;
361 else if ((insn & 0xc0) == DW_CFA_offset)
364 reg = dwarf2_frame_adjust_regnum (gdbarch, reg, eh_frame_p);
365 insn_ptr = safe_read_uleb128 (insn_ptr, insn_end, &utmp);
366 offset = utmp * fs->data_align;
367 fs->regs.alloc_regs (reg + 1);
368 fs->regs.reg[reg].how = DWARF2_FRAME_REG_SAVED_OFFSET;
369 fs->regs.reg[reg].loc.offset = offset;
371 else if ((insn & 0xc0) == DW_CFA_restore)
374 dwarf2_restore_rule (gdbarch, reg, fs, eh_frame_p);
381 fs->pc = read_encoded_value (fde->cie->unit, fde->cie->encoding,
382 fde->cie->ptr_size, insn_ptr,
383 &bytes_read, fde->initial_location);
384 /* Apply the objfile offset for relocatable objects. */
385 fs->pc += ANOFFSET (fde->cie->unit->objfile->section_offsets,
386 SECT_OFF_TEXT (fde->cie->unit->objfile));
387 insn_ptr += bytes_read;
390 case DW_CFA_advance_loc1:
391 utmp = extract_unsigned_integer (insn_ptr, 1, byte_order);
392 fs->pc += utmp * fs->code_align;
395 case DW_CFA_advance_loc2:
396 utmp = extract_unsigned_integer (insn_ptr, 2, byte_order);
397 fs->pc += utmp * fs->code_align;
400 case DW_CFA_advance_loc4:
401 utmp = extract_unsigned_integer (insn_ptr, 4, byte_order);
402 fs->pc += utmp * fs->code_align;
406 case DW_CFA_offset_extended:
407 insn_ptr = safe_read_uleb128 (insn_ptr, insn_end, ®);
408 reg = dwarf2_frame_adjust_regnum (gdbarch, reg, eh_frame_p);
409 insn_ptr = safe_read_uleb128 (insn_ptr, insn_end, &utmp);
410 offset = utmp * fs->data_align;
411 fs->regs.alloc_regs (reg + 1);
412 fs->regs.reg[reg].how = DWARF2_FRAME_REG_SAVED_OFFSET;
413 fs->regs.reg[reg].loc.offset = offset;
416 case DW_CFA_restore_extended:
417 insn_ptr = safe_read_uleb128 (insn_ptr, insn_end, ®);
418 dwarf2_restore_rule (gdbarch, reg, fs, eh_frame_p);
421 case DW_CFA_undefined:
422 insn_ptr = safe_read_uleb128 (insn_ptr, insn_end, ®);
423 reg = dwarf2_frame_adjust_regnum (gdbarch, reg, eh_frame_p);
424 fs->regs.alloc_regs (reg + 1);
425 fs->regs.reg[reg].how = DWARF2_FRAME_REG_UNDEFINED;
428 case DW_CFA_same_value:
429 insn_ptr = safe_read_uleb128 (insn_ptr, insn_end, ®);
430 reg = dwarf2_frame_adjust_regnum (gdbarch, reg, eh_frame_p);
431 fs->regs.alloc_regs (reg + 1);
432 fs->regs.reg[reg].how = DWARF2_FRAME_REG_SAME_VALUE;
435 case DW_CFA_register:
436 insn_ptr = safe_read_uleb128 (insn_ptr, insn_end, ®);
437 reg = dwarf2_frame_adjust_regnum (gdbarch, reg, eh_frame_p);
438 insn_ptr = safe_read_uleb128 (insn_ptr, insn_end, &utmp);
439 utmp = dwarf2_frame_adjust_regnum (gdbarch, utmp, eh_frame_p);
440 fs->regs.alloc_regs (reg + 1);
441 fs->regs.reg[reg].how = DWARF2_FRAME_REG_SAVED_REG;
442 fs->regs.reg[reg].loc.reg = utmp;
445 case DW_CFA_remember_state:
447 struct dwarf2_frame_state_reg_info *new_rs;
449 new_rs = new dwarf2_frame_state_reg_info (fs->regs);
450 fs->regs.prev = new_rs;
454 case DW_CFA_restore_state:
456 struct dwarf2_frame_state_reg_info *old_rs = fs->regs.prev;
461 bad CFI data; mismatched DW_CFA_restore_state at %s"),
462 paddress (gdbarch, fs->pc));
465 fs->regs = std::move (*old_rs);
470 insn_ptr = safe_read_uleb128 (insn_ptr, insn_end, ®);
471 fs->regs.cfa_reg = reg;
472 insn_ptr = safe_read_uleb128 (insn_ptr, insn_end, &utmp);
474 if (fs->armcc_cfa_offsets_sf)
475 utmp *= fs->data_align;
477 fs->regs.cfa_offset = utmp;
478 fs->regs.cfa_how = CFA_REG_OFFSET;
481 case DW_CFA_def_cfa_register:
482 insn_ptr = safe_read_uleb128 (insn_ptr, insn_end, ®);
483 fs->regs.cfa_reg = dwarf2_frame_adjust_regnum (gdbarch, reg,
485 fs->regs.cfa_how = CFA_REG_OFFSET;
488 case DW_CFA_def_cfa_offset:
489 insn_ptr = safe_read_uleb128 (insn_ptr, insn_end, &utmp);
491 if (fs->armcc_cfa_offsets_sf)
492 utmp *= fs->data_align;
494 fs->regs.cfa_offset = utmp;
495 /* cfa_how deliberately not set. */
501 case DW_CFA_def_cfa_expression:
502 insn_ptr = safe_read_uleb128 (insn_ptr, insn_end, &utmp);
503 fs->regs.cfa_exp_len = utmp;
504 fs->regs.cfa_exp = insn_ptr;
505 fs->regs.cfa_how = CFA_EXP;
506 insn_ptr += fs->regs.cfa_exp_len;
509 case DW_CFA_expression:
510 insn_ptr = safe_read_uleb128 (insn_ptr, insn_end, ®);
511 reg = dwarf2_frame_adjust_regnum (gdbarch, reg, eh_frame_p);
512 fs->regs.alloc_regs (reg + 1);
513 insn_ptr = safe_read_uleb128 (insn_ptr, insn_end, &utmp);
514 fs->regs.reg[reg].loc.exp.start = insn_ptr;
515 fs->regs.reg[reg].loc.exp.len = utmp;
516 fs->regs.reg[reg].how = DWARF2_FRAME_REG_SAVED_EXP;
520 case DW_CFA_offset_extended_sf:
521 insn_ptr = safe_read_uleb128 (insn_ptr, insn_end, ®);
522 reg = dwarf2_frame_adjust_regnum (gdbarch, reg, eh_frame_p);
523 insn_ptr = safe_read_sleb128 (insn_ptr, insn_end, &offset);
524 offset *= fs->data_align;
525 fs->regs.alloc_regs (reg + 1);
526 fs->regs.reg[reg].how = DWARF2_FRAME_REG_SAVED_OFFSET;
527 fs->regs.reg[reg].loc.offset = offset;
530 case DW_CFA_val_offset:
531 insn_ptr = safe_read_uleb128 (insn_ptr, insn_end, ®);
532 fs->regs.alloc_regs (reg + 1);
533 insn_ptr = safe_read_uleb128 (insn_ptr, insn_end, &utmp);
534 offset = utmp * fs->data_align;
535 fs->regs.reg[reg].how = DWARF2_FRAME_REG_SAVED_VAL_OFFSET;
536 fs->regs.reg[reg].loc.offset = offset;
539 case DW_CFA_val_offset_sf:
540 insn_ptr = safe_read_uleb128 (insn_ptr, insn_end, ®);
541 fs->regs.alloc_regs (reg + 1);
542 insn_ptr = safe_read_sleb128 (insn_ptr, insn_end, &offset);
543 offset *= fs->data_align;
544 fs->regs.reg[reg].how = DWARF2_FRAME_REG_SAVED_VAL_OFFSET;
545 fs->regs.reg[reg].loc.offset = offset;
548 case DW_CFA_val_expression:
549 insn_ptr = safe_read_uleb128 (insn_ptr, insn_end, ®);
550 fs->regs.alloc_regs (reg + 1);
551 insn_ptr = safe_read_uleb128 (insn_ptr, insn_end, &utmp);
552 fs->regs.reg[reg].loc.exp.start = insn_ptr;
553 fs->regs.reg[reg].loc.exp.len = utmp;
554 fs->regs.reg[reg].how = DWARF2_FRAME_REG_SAVED_VAL_EXP;
558 case DW_CFA_def_cfa_sf:
559 insn_ptr = safe_read_uleb128 (insn_ptr, insn_end, ®);
560 fs->regs.cfa_reg = dwarf2_frame_adjust_regnum (gdbarch, reg,
562 insn_ptr = safe_read_sleb128 (insn_ptr, insn_end, &offset);
563 fs->regs.cfa_offset = offset * fs->data_align;
564 fs->regs.cfa_how = CFA_REG_OFFSET;
567 case DW_CFA_def_cfa_offset_sf:
568 insn_ptr = safe_read_sleb128 (insn_ptr, insn_end, &offset);
569 fs->regs.cfa_offset = offset * fs->data_align;
570 /* cfa_how deliberately not set. */
573 case DW_CFA_GNU_args_size:
575 insn_ptr = safe_read_uleb128 (insn_ptr, insn_end, &utmp);
578 case DW_CFA_GNU_negative_offset_extended:
579 insn_ptr = safe_read_uleb128 (insn_ptr, insn_end, ®);
580 reg = dwarf2_frame_adjust_regnum (gdbarch, reg, eh_frame_p);
581 insn_ptr = safe_read_uleb128 (insn_ptr, insn_end, &utmp);
582 offset = utmp * fs->data_align;
583 fs->regs.alloc_regs (reg + 1);
584 fs->regs.reg[reg].how = DWARF2_FRAME_REG_SAVED_OFFSET;
585 fs->regs.reg[reg].loc.offset = -offset;
589 if (insn >= DW_CFA_lo_user && insn <= DW_CFA_hi_user)
591 /* Handle vendor-specific CFI for different architectures. */
592 if (!gdbarch_execute_dwarf_cfa_vendor_op (gdbarch, insn, fs))
593 error (_("Call Frame Instruction op %d in vendor extension "
594 "space is not handled on this architecture."),
598 internal_error (__FILE__, __LINE__,
599 _("Unknown CFI encountered."));
604 if (fs->initial.reg.empty ())
606 /* Don't allow remember/restore between CIE and FDE programs. */
607 delete fs->regs.prev;
608 fs->regs.prev = NULL;
616 namespace selftests {
618 /* Unit test to function execute_cfa_program. */
621 execute_cfa_program_test (struct gdbarch *gdbarch)
623 struct dwarf2_fde fde;
624 struct dwarf2_cie cie;
626 memset (&fde, 0, sizeof fde);
627 memset (&cie, 0, sizeof cie);
629 cie.data_alignment_factor = -4;
630 cie.code_alignment_factor = 2;
633 dwarf2_frame_state fs (0, fde.cie);
637 DW_CFA_def_cfa, 1, 4, /* DW_CFA_def_cfa: r1 ofs 4 */
638 DW_CFA_offset | 0x2, 1, /* DW_CFA_offset: r2 at cfa-4 */
639 DW_CFA_remember_state,
640 DW_CFA_restore_state,
643 const gdb_byte *insn_end = insns + sizeof (insns);
644 const gdb_byte *out = execute_cfa_program (&fde, insns, insn_end, gdbarch,
647 SELF_CHECK (out == insn_end);
648 SELF_CHECK (fs.pc == 0);
650 /* The instructions above only use r1 and r2, but the register numbers
651 used are adjusted by dwarf2_frame_adjust_regnum. */
652 auto r1 = dwarf2_frame_adjust_regnum (gdbarch, 1, fde.eh_frame_p);
653 auto r2 = dwarf2_frame_adjust_regnum (gdbarch, 2, fde.eh_frame_p);
655 SELF_CHECK (fs.regs.reg.size () == (std::max (r1, r2) + 1));
657 SELF_CHECK (fs.regs.reg[r2].how == DWARF2_FRAME_REG_SAVED_OFFSET);
658 SELF_CHECK (fs.regs.reg[r2].loc.offset == -4);
660 for (auto i = 0; i < fs.regs.reg.size (); i++)
662 SELF_CHECK (fs.regs.reg[i].how == DWARF2_FRAME_REG_UNSPECIFIED);
664 SELF_CHECK (fs.regs.cfa_reg == 1);
665 SELF_CHECK (fs.regs.cfa_offset == 4);
666 SELF_CHECK (fs.regs.cfa_how == CFA_REG_OFFSET);
667 SELF_CHECK (fs.regs.cfa_exp == NULL);
668 SELF_CHECK (fs.regs.prev == NULL);
671 } // namespace selftests
672 #endif /* GDB_SELF_TEST */
676 /* Architecture-specific operations. */
678 /* Per-architecture data key. */
679 static struct gdbarch_data *dwarf2_frame_data;
681 struct dwarf2_frame_ops
683 /* Pre-initialize the register state REG for register REGNUM. */
684 void (*init_reg) (struct gdbarch *, int, struct dwarf2_frame_state_reg *,
685 struct frame_info *);
687 /* Check whether the THIS_FRAME is a signal trampoline. */
688 int (*signal_frame_p) (struct gdbarch *, struct frame_info *);
690 /* Convert .eh_frame register number to DWARF register number, or
691 adjust .debug_frame register number. */
692 int (*adjust_regnum) (struct gdbarch *, int, int);
695 /* Default architecture-specific register state initialization
699 dwarf2_frame_default_init_reg (struct gdbarch *gdbarch, int regnum,
700 struct dwarf2_frame_state_reg *reg,
701 struct frame_info *this_frame)
703 /* If we have a register that acts as a program counter, mark it as
704 a destination for the return address. If we have a register that
705 serves as the stack pointer, arrange for it to be filled with the
706 call frame address (CFA). The other registers are marked as
709 We copy the return address to the program counter, since many
710 parts in GDB assume that it is possible to get the return address
711 by unwinding the program counter register. However, on ISA's
712 with a dedicated return address register, the CFI usually only
713 contains information to unwind that return address register.
715 The reason we're treating the stack pointer special here is
716 because in many cases GCC doesn't emit CFI for the stack pointer
717 and implicitly assumes that it is equal to the CFA. This makes
718 some sense since the DWARF specification (version 3, draft 8,
721 "Typically, the CFA is defined to be the value of the stack
722 pointer at the call site in the previous frame (which may be
723 different from its value on entry to the current frame)."
725 However, this isn't true for all platforms supported by GCC
726 (e.g. IBM S/390 and zSeries). Those architectures should provide
727 their own architecture-specific initialization function. */
729 if (regnum == gdbarch_pc_regnum (gdbarch))
730 reg->how = DWARF2_FRAME_REG_RA;
731 else if (regnum == gdbarch_sp_regnum (gdbarch))
732 reg->how = DWARF2_FRAME_REG_CFA;
735 /* Return a default for the architecture-specific operations. */
738 dwarf2_frame_init (struct obstack *obstack)
740 struct dwarf2_frame_ops *ops;
742 ops = OBSTACK_ZALLOC (obstack, struct dwarf2_frame_ops);
743 ops->init_reg = dwarf2_frame_default_init_reg;
747 /* Set the architecture-specific register state initialization
748 function for GDBARCH to INIT_REG. */
751 dwarf2_frame_set_init_reg (struct gdbarch *gdbarch,
752 void (*init_reg) (struct gdbarch *, int,
753 struct dwarf2_frame_state_reg *,
754 struct frame_info *))
756 struct dwarf2_frame_ops *ops
757 = (struct dwarf2_frame_ops *) gdbarch_data (gdbarch, dwarf2_frame_data);
759 ops->init_reg = init_reg;
762 /* Pre-initialize the register state REG for register REGNUM. */
765 dwarf2_frame_init_reg (struct gdbarch *gdbarch, int regnum,
766 struct dwarf2_frame_state_reg *reg,
767 struct frame_info *this_frame)
769 struct dwarf2_frame_ops *ops
770 = (struct dwarf2_frame_ops *) gdbarch_data (gdbarch, dwarf2_frame_data);
772 ops->init_reg (gdbarch, regnum, reg, this_frame);
775 /* Set the architecture-specific signal trampoline recognition
776 function for GDBARCH to SIGNAL_FRAME_P. */
779 dwarf2_frame_set_signal_frame_p (struct gdbarch *gdbarch,
780 int (*signal_frame_p) (struct gdbarch *,
781 struct frame_info *))
783 struct dwarf2_frame_ops *ops
784 = (struct dwarf2_frame_ops *) gdbarch_data (gdbarch, dwarf2_frame_data);
786 ops->signal_frame_p = signal_frame_p;
789 /* Query the architecture-specific signal frame recognizer for
793 dwarf2_frame_signal_frame_p (struct gdbarch *gdbarch,
794 struct frame_info *this_frame)
796 struct dwarf2_frame_ops *ops
797 = (struct dwarf2_frame_ops *) gdbarch_data (gdbarch, dwarf2_frame_data);
799 if (ops->signal_frame_p == NULL)
801 return ops->signal_frame_p (gdbarch, this_frame);
804 /* Set the architecture-specific adjustment of .eh_frame and .debug_frame
808 dwarf2_frame_set_adjust_regnum (struct gdbarch *gdbarch,
809 int (*adjust_regnum) (struct gdbarch *,
812 struct dwarf2_frame_ops *ops
813 = (struct dwarf2_frame_ops *) gdbarch_data (gdbarch, dwarf2_frame_data);
815 ops->adjust_regnum = adjust_regnum;
818 /* Translate a .eh_frame register to DWARF register, or adjust a .debug_frame
822 dwarf2_frame_adjust_regnum (struct gdbarch *gdbarch,
823 int regnum, int eh_frame_p)
825 struct dwarf2_frame_ops *ops
826 = (struct dwarf2_frame_ops *) gdbarch_data (gdbarch, dwarf2_frame_data);
828 if (ops->adjust_regnum == NULL)
830 return ops->adjust_regnum (gdbarch, regnum, eh_frame_p);
834 dwarf2_frame_find_quirks (struct dwarf2_frame_state *fs,
835 struct dwarf2_fde *fde)
837 struct compunit_symtab *cust;
839 cust = find_pc_compunit_symtab (fs->pc);
843 if (producer_is_realview (COMPUNIT_PRODUCER (cust)))
845 if (fde->cie->version == 1)
846 fs->armcc_cfa_offsets_sf = 1;
848 if (fde->cie->version == 1)
849 fs->armcc_cfa_offsets_reversed = 1;
851 /* The reversed offset problem is present in some compilers
852 using DWARF3, but it was eventually fixed. Check the ARM
853 defined augmentations, which are in the format "armcc" followed
854 by a list of one-character options. The "+" option means
855 this problem is fixed (no quirk needed). If the armcc
856 augmentation is missing, the quirk is needed. */
857 if (fde->cie->version == 3
858 && (!startswith (fde->cie->augmentation, "armcc")
859 || strchr (fde->cie->augmentation + 5, '+') == NULL))
860 fs->armcc_cfa_offsets_reversed = 1;
867 /* See dwarf2-frame.h. */
870 dwarf2_fetch_cfa_info (struct gdbarch *gdbarch, CORE_ADDR pc,
871 struct dwarf2_per_cu_data *data,
872 int *regnum_out, LONGEST *offset_out,
873 CORE_ADDR *text_offset_out,
874 const gdb_byte **cfa_start_out,
875 const gdb_byte **cfa_end_out)
877 struct dwarf2_fde *fde;
878 CORE_ADDR text_offset;
881 /* Find the correct FDE. */
882 fde = dwarf2_frame_find_fde (&pc1, &text_offset);
884 error (_("Could not compute CFA; needed to translate this expression"));
886 dwarf2_frame_state fs (pc1, fde->cie);
888 /* Check for "quirks" - known bugs in producers. */
889 dwarf2_frame_find_quirks (&fs, fde);
891 /* First decode all the insns in the CIE. */
892 execute_cfa_program (fde, fde->cie->initial_instructions,
893 fde->cie->end, gdbarch, pc, &fs);
895 /* Save the initialized register set. */
896 fs.initial = fs.regs;
898 /* Then decode the insns in the FDE up to our target PC. */
899 execute_cfa_program (fde, fde->instructions, fde->end, gdbarch, pc, &fs);
901 /* Calculate the CFA. */
902 switch (fs.regs.cfa_how)
906 int regnum = dwarf_reg_to_regnum_or_error (gdbarch, fs.regs.cfa_reg);
908 *regnum_out = regnum;
909 if (fs.armcc_cfa_offsets_reversed)
910 *offset_out = -fs.regs.cfa_offset;
912 *offset_out = fs.regs.cfa_offset;
917 *text_offset_out = text_offset;
918 *cfa_start_out = fs.regs.cfa_exp;
919 *cfa_end_out = fs.regs.cfa_exp + fs.regs.cfa_exp_len;
923 internal_error (__FILE__, __LINE__, _("Unknown CFA rule."));
928 struct dwarf2_frame_cache
930 /* DWARF Call Frame Address. */
933 /* Set if the return address column was marked as unavailable
934 (required non-collected memory or registers to compute). */
935 int unavailable_retaddr;
937 /* Set if the return address column was marked as undefined. */
938 int undefined_retaddr;
940 /* Saved registers, indexed by GDB register number, not by DWARF
942 struct dwarf2_frame_state_reg *reg;
944 /* Return address register. */
945 struct dwarf2_frame_state_reg retaddr_reg;
947 /* Target address size in bytes. */
950 /* The .text offset. */
951 CORE_ADDR text_offset;
953 /* True if we already checked whether this frame is the bottom frame
954 of a virtual tail call frame chain. */
955 int checked_tailcall_bottom;
957 /* If not NULL then this frame is the bottom frame of a TAILCALL_FRAME
958 sequence. If NULL then it is a normal case with no TAILCALL_FRAME
959 involved. Non-bottom frames of a virtual tail call frames chain use
960 dwarf2_tailcall_frame_unwind unwinder so this field does not apply for
962 void *tailcall_cache;
964 /* The number of bytes to subtract from TAILCALL_FRAME frames frame
965 base to get the SP, to simulate the return address pushed on the
967 LONGEST entry_cfa_sp_offset;
968 int entry_cfa_sp_offset_p;
971 static struct dwarf2_frame_cache *
972 dwarf2_frame_cache (struct frame_info *this_frame, void **this_cache)
974 struct gdbarch *gdbarch = get_frame_arch (this_frame);
975 const int num_regs = gdbarch_num_cooked_regs (gdbarch);
976 struct dwarf2_frame_cache *cache;
977 struct dwarf2_fde *fde;
979 const gdb_byte *instr;
982 return (struct dwarf2_frame_cache *) *this_cache;
984 /* Allocate a new cache. */
985 cache = FRAME_OBSTACK_ZALLOC (struct dwarf2_frame_cache);
986 cache->reg = FRAME_OBSTACK_CALLOC (num_regs, struct dwarf2_frame_state_reg);
991 Note that if the next frame is never supposed to return (i.e. a call
992 to abort), the compiler might optimize away the instruction at
993 its return address. As a result the return address will
994 point at some random instruction, and the CFI for that
995 instruction is probably worthless to us. GCC's unwinder solves
996 this problem by substracting 1 from the return address to get an
997 address in the middle of a presumed call instruction (or the
998 instruction in the associated delay slot). This should only be
999 done for "normal" frames and not for resume-type frames (signal
1000 handlers, sentinel frames, dummy frames). The function
1001 get_frame_address_in_block does just this. It's not clear how
1002 reliable the method is though; there is the potential for the
1003 register state pre-call being different to that on return. */
1004 CORE_ADDR pc1 = get_frame_address_in_block (this_frame);
1006 /* Find the correct FDE. */
1007 fde = dwarf2_frame_find_fde (&pc1, &cache->text_offset);
1008 gdb_assert (fde != NULL);
1010 /* Allocate and initialize the frame state. */
1011 struct dwarf2_frame_state fs (pc1, fde->cie);
1013 cache->addr_size = fde->cie->addr_size;
1015 /* Check for "quirks" - known bugs in producers. */
1016 dwarf2_frame_find_quirks (&fs, fde);
1018 /* First decode all the insns in the CIE. */
1019 execute_cfa_program (fde, fde->cie->initial_instructions,
1020 fde->cie->end, gdbarch,
1021 get_frame_address_in_block (this_frame), &fs);
1023 /* Save the initialized register set. */
1024 fs.initial = fs.regs;
1026 if (get_frame_func_if_available (this_frame, &entry_pc))
1028 /* Decode the insns in the FDE up to the entry PC. */
1029 instr = execute_cfa_program (fde, fde->instructions, fde->end, gdbarch,
1032 if (fs.regs.cfa_how == CFA_REG_OFFSET
1033 && (dwarf_reg_to_regnum (gdbarch, fs.regs.cfa_reg)
1034 == gdbarch_sp_regnum (gdbarch)))
1036 cache->entry_cfa_sp_offset = fs.regs.cfa_offset;
1037 cache->entry_cfa_sp_offset_p = 1;
1041 instr = fde->instructions;
1043 /* Then decode the insns in the FDE up to our target PC. */
1044 execute_cfa_program (fde, instr, fde->end, gdbarch,
1045 get_frame_address_in_block (this_frame), &fs);
1049 /* Calculate the CFA. */
1050 switch (fs.regs.cfa_how)
1052 case CFA_REG_OFFSET:
1053 cache->cfa = read_addr_from_reg (this_frame, fs.regs.cfa_reg);
1054 if (fs.armcc_cfa_offsets_reversed)
1055 cache->cfa -= fs.regs.cfa_offset;
1057 cache->cfa += fs.regs.cfa_offset;
1062 execute_stack_op (fs.regs.cfa_exp, fs.regs.cfa_exp_len,
1063 cache->addr_size, cache->text_offset,
1068 internal_error (__FILE__, __LINE__, _("Unknown CFA rule."));
1071 catch (const gdb_exception_RETURN_MASK_ERROR &ex)
1073 if (ex.error == NOT_AVAILABLE_ERROR)
1075 cache->unavailable_retaddr = 1;
1079 throw_exception (ex);
1082 /* Initialize the register state. */
1086 for (regnum = 0; regnum < num_regs; regnum++)
1087 dwarf2_frame_init_reg (gdbarch, regnum, &cache->reg[regnum], this_frame);
1090 /* Go through the DWARF2 CFI generated table and save its register
1091 location information in the cache. Note that we don't skip the
1092 return address column; it's perfectly all right for it to
1093 correspond to a real register. */
1095 int column; /* CFI speak for "register number". */
1097 for (column = 0; column < fs.regs.reg.size (); column++)
1099 /* Use the GDB register number as the destination index. */
1100 int regnum = dwarf_reg_to_regnum (gdbarch, column);
1102 /* Protect against a target returning a bad register. */
1103 if (regnum < 0 || regnum >= num_regs)
1106 /* NOTE: cagney/2003-09-05: CFI should specify the disposition
1107 of all debug info registers. If it doesn't, complain (but
1108 not too loudly). It turns out that GCC assumes that an
1109 unspecified register implies "same value" when CFI (draft
1110 7) specifies nothing at all. Such a register could equally
1111 be interpreted as "undefined". Also note that this check
1112 isn't sufficient; it only checks that all registers in the
1113 range [0 .. max column] are specified, and won't detect
1114 problems when a debug info register falls outside of the
1115 table. We need a way of iterating through all the valid
1116 DWARF2 register numbers. */
1117 if (fs.regs.reg[column].how == DWARF2_FRAME_REG_UNSPECIFIED)
1119 if (cache->reg[regnum].how == DWARF2_FRAME_REG_UNSPECIFIED)
1121 incomplete CFI data; unspecified registers (e.g., %s) at %s"),
1122 gdbarch_register_name (gdbarch, regnum),
1123 paddress (gdbarch, fs.pc));
1126 cache->reg[regnum] = fs.regs.reg[column];
1130 /* Eliminate any DWARF2_FRAME_REG_RA rules, and save the information
1131 we need for evaluating DWARF2_FRAME_REG_RA_OFFSET rules. */
1135 for (regnum = 0; regnum < num_regs; regnum++)
1137 if (cache->reg[regnum].how == DWARF2_FRAME_REG_RA
1138 || cache->reg[regnum].how == DWARF2_FRAME_REG_RA_OFFSET)
1140 const std::vector<struct dwarf2_frame_state_reg> ®s
1142 ULONGEST retaddr_column = fs.retaddr_column;
1144 /* It seems rather bizarre to specify an "empty" column as
1145 the return adress column. However, this is exactly
1146 what GCC does on some targets. It turns out that GCC
1147 assumes that the return address can be found in the
1148 register corresponding to the return address column.
1149 Incidentally, that's how we should treat a return
1150 address column specifying "same value" too. */
1151 if (fs.retaddr_column < fs.regs.reg.size ()
1152 && regs[retaddr_column].how != DWARF2_FRAME_REG_UNSPECIFIED
1153 && regs[retaddr_column].how != DWARF2_FRAME_REG_SAME_VALUE)
1155 if (cache->reg[regnum].how == DWARF2_FRAME_REG_RA)
1156 cache->reg[regnum] = regs[retaddr_column];
1158 cache->retaddr_reg = regs[retaddr_column];
1162 if (cache->reg[regnum].how == DWARF2_FRAME_REG_RA)
1164 cache->reg[regnum].loc.reg = fs.retaddr_column;
1165 cache->reg[regnum].how = DWARF2_FRAME_REG_SAVED_REG;
1169 cache->retaddr_reg.loc.reg = fs.retaddr_column;
1170 cache->retaddr_reg.how = DWARF2_FRAME_REG_SAVED_REG;
1177 if (fs.retaddr_column < fs.regs.reg.size ()
1178 && fs.regs.reg[fs.retaddr_column].how == DWARF2_FRAME_REG_UNDEFINED)
1179 cache->undefined_retaddr = 1;
1184 static enum unwind_stop_reason
1185 dwarf2_frame_unwind_stop_reason (struct frame_info *this_frame,
1188 struct dwarf2_frame_cache *cache
1189 = dwarf2_frame_cache (this_frame, this_cache);
1191 if (cache->unavailable_retaddr)
1192 return UNWIND_UNAVAILABLE;
1194 if (cache->undefined_retaddr)
1195 return UNWIND_OUTERMOST;
1197 return UNWIND_NO_REASON;
1201 dwarf2_frame_this_id (struct frame_info *this_frame, void **this_cache,
1202 struct frame_id *this_id)
1204 struct dwarf2_frame_cache *cache =
1205 dwarf2_frame_cache (this_frame, this_cache);
1207 if (cache->unavailable_retaddr)
1208 (*this_id) = frame_id_build_unavailable_stack (get_frame_func (this_frame));
1209 else if (cache->undefined_retaddr)
1212 (*this_id) = frame_id_build (cache->cfa, get_frame_func (this_frame));
1215 static struct value *
1216 dwarf2_frame_prev_register (struct frame_info *this_frame, void **this_cache,
1219 struct gdbarch *gdbarch = get_frame_arch (this_frame);
1220 struct dwarf2_frame_cache *cache =
1221 dwarf2_frame_cache (this_frame, this_cache);
1225 /* Check whether THIS_FRAME is the bottom frame of a virtual tail
1226 call frame chain. */
1227 if (!cache->checked_tailcall_bottom)
1229 cache->checked_tailcall_bottom = 1;
1230 dwarf2_tailcall_sniffer_first (this_frame, &cache->tailcall_cache,
1231 (cache->entry_cfa_sp_offset_p
1232 ? &cache->entry_cfa_sp_offset : NULL));
1235 /* Non-bottom frames of a virtual tail call frames chain use
1236 dwarf2_tailcall_frame_unwind unwinder so this code does not apply for
1237 them. If dwarf2_tailcall_prev_register_first does not have specific value
1238 unwind the register, tail call frames are assumed to have the register set
1239 of the top caller. */
1240 if (cache->tailcall_cache)
1244 val = dwarf2_tailcall_prev_register_first (this_frame,
1245 &cache->tailcall_cache,
1251 switch (cache->reg[regnum].how)
1253 case DWARF2_FRAME_REG_UNDEFINED:
1254 /* If CFI explicitly specified that the value isn't defined,
1255 mark it as optimized away; the value isn't available. */
1256 return frame_unwind_got_optimized (this_frame, regnum);
1258 case DWARF2_FRAME_REG_SAVED_OFFSET:
1259 addr = cache->cfa + cache->reg[regnum].loc.offset;
1260 return frame_unwind_got_memory (this_frame, regnum, addr);
1262 case DWARF2_FRAME_REG_SAVED_REG:
1263 realnum = dwarf_reg_to_regnum_or_error
1264 (gdbarch, cache->reg[regnum].loc.reg);
1265 return frame_unwind_got_register (this_frame, regnum, realnum);
1267 case DWARF2_FRAME_REG_SAVED_EXP:
1268 addr = execute_stack_op (cache->reg[regnum].loc.exp.start,
1269 cache->reg[regnum].loc.exp.len,
1270 cache->addr_size, cache->text_offset,
1271 this_frame, cache->cfa, 1);
1272 return frame_unwind_got_memory (this_frame, regnum, addr);
1274 case DWARF2_FRAME_REG_SAVED_VAL_OFFSET:
1275 addr = cache->cfa + cache->reg[regnum].loc.offset;
1276 return frame_unwind_got_constant (this_frame, regnum, addr);
1278 case DWARF2_FRAME_REG_SAVED_VAL_EXP:
1279 addr = execute_stack_op (cache->reg[regnum].loc.exp.start,
1280 cache->reg[regnum].loc.exp.len,
1281 cache->addr_size, cache->text_offset,
1282 this_frame, cache->cfa, 1);
1283 return frame_unwind_got_constant (this_frame, regnum, addr);
1285 case DWARF2_FRAME_REG_UNSPECIFIED:
1286 /* GCC, in its infinite wisdom decided to not provide unwind
1287 information for registers that are "same value". Since
1288 DWARF2 (3 draft 7) doesn't define such behavior, said
1289 registers are actually undefined (which is different to CFI
1290 "undefined"). Code above issues a complaint about this.
1291 Here just fudge the books, assume GCC, and that the value is
1292 more inner on the stack. */
1293 return frame_unwind_got_register (this_frame, regnum, regnum);
1295 case DWARF2_FRAME_REG_SAME_VALUE:
1296 return frame_unwind_got_register (this_frame, regnum, regnum);
1298 case DWARF2_FRAME_REG_CFA:
1299 return frame_unwind_got_address (this_frame, regnum, cache->cfa);
1301 case DWARF2_FRAME_REG_CFA_OFFSET:
1302 addr = cache->cfa + cache->reg[regnum].loc.offset;
1303 return frame_unwind_got_address (this_frame, regnum, addr);
1305 case DWARF2_FRAME_REG_RA_OFFSET:
1306 addr = cache->reg[regnum].loc.offset;
1307 regnum = dwarf_reg_to_regnum_or_error
1308 (gdbarch, cache->retaddr_reg.loc.reg);
1309 addr += get_frame_register_unsigned (this_frame, regnum);
1310 return frame_unwind_got_address (this_frame, regnum, addr);
1312 case DWARF2_FRAME_REG_FN:
1313 return cache->reg[regnum].loc.fn (this_frame, this_cache, regnum);
1316 internal_error (__FILE__, __LINE__, _("Unknown register rule."));
1320 /* Proxy for tailcall_frame_dealloc_cache for bottom frame of a virtual tail
1321 call frames chain. */
1324 dwarf2_frame_dealloc_cache (struct frame_info *self, void *this_cache)
1326 struct dwarf2_frame_cache *cache = dwarf2_frame_cache (self, &this_cache);
1328 if (cache->tailcall_cache)
1329 dwarf2_tailcall_frame_unwind.dealloc_cache (self, cache->tailcall_cache);
1333 dwarf2_frame_sniffer (const struct frame_unwind *self,
1334 struct frame_info *this_frame, void **this_cache)
1336 if (!dwarf2_frame_unwinders_enabled_p)
1339 /* Grab an address that is guarenteed to reside somewhere within the
1340 function. get_frame_pc(), with a no-return next function, can
1341 end up returning something past the end of this function's body.
1342 If the frame we're sniffing for is a signal frame whose start
1343 address is placed on the stack by the OS, its FDE must
1344 extend one byte before its start address or we could potentially
1345 select the FDE of the previous function. */
1346 CORE_ADDR block_addr = get_frame_address_in_block (this_frame);
1347 struct dwarf2_fde *fde = dwarf2_frame_find_fde (&block_addr, NULL);
1352 /* On some targets, signal trampolines may have unwind information.
1353 We need to recognize them so that we set the frame type
1356 if (fde->cie->signal_frame
1357 || dwarf2_frame_signal_frame_p (get_frame_arch (this_frame),
1359 return self->type == SIGTRAMP_FRAME;
1361 if (self->type != NORMAL_FRAME)
1367 static const struct frame_unwind dwarf2_frame_unwind =
1370 dwarf2_frame_unwind_stop_reason,
1371 dwarf2_frame_this_id,
1372 dwarf2_frame_prev_register,
1374 dwarf2_frame_sniffer,
1375 dwarf2_frame_dealloc_cache
1378 static const struct frame_unwind dwarf2_signal_frame_unwind =
1381 dwarf2_frame_unwind_stop_reason,
1382 dwarf2_frame_this_id,
1383 dwarf2_frame_prev_register,
1385 dwarf2_frame_sniffer,
1387 /* TAILCALL_CACHE can never be in such frame to need dealloc_cache. */
1391 /* Append the DWARF-2 frame unwinders to GDBARCH's list. */
1394 dwarf2_append_unwinders (struct gdbarch *gdbarch)
1396 /* TAILCALL_FRAME must be first to find the record by
1397 dwarf2_tailcall_sniffer_first. */
1398 frame_unwind_append_unwinder (gdbarch, &dwarf2_tailcall_frame_unwind);
1400 frame_unwind_append_unwinder (gdbarch, &dwarf2_frame_unwind);
1401 frame_unwind_append_unwinder (gdbarch, &dwarf2_signal_frame_unwind);
1405 /* There is no explicitly defined relationship between the CFA and the
1406 location of frame's local variables and arguments/parameters.
1407 Therefore, frame base methods on this page should probably only be
1408 used as a last resort, just to avoid printing total garbage as a
1409 response to the "info frame" command. */
1412 dwarf2_frame_base_address (struct frame_info *this_frame, void **this_cache)
1414 struct dwarf2_frame_cache *cache =
1415 dwarf2_frame_cache (this_frame, this_cache);
1420 static const struct frame_base dwarf2_frame_base =
1422 &dwarf2_frame_unwind,
1423 dwarf2_frame_base_address,
1424 dwarf2_frame_base_address,
1425 dwarf2_frame_base_address
1428 const struct frame_base *
1429 dwarf2_frame_base_sniffer (struct frame_info *this_frame)
1431 CORE_ADDR block_addr = get_frame_address_in_block (this_frame);
1433 if (dwarf2_frame_find_fde (&block_addr, NULL))
1434 return &dwarf2_frame_base;
1439 /* Compute the CFA for THIS_FRAME, but only if THIS_FRAME came from
1440 the DWARF unwinder. This is used to implement
1441 DW_OP_call_frame_cfa. */
1444 dwarf2_frame_cfa (struct frame_info *this_frame)
1446 if (frame_unwinder_is (this_frame, &record_btrace_tailcall_frame_unwind)
1447 || frame_unwinder_is (this_frame, &record_btrace_frame_unwind))
1448 throw_error (NOT_AVAILABLE_ERROR,
1449 _("cfa not available for record btrace target"));
1451 while (get_frame_type (this_frame) == INLINE_FRAME)
1452 this_frame = get_prev_frame (this_frame);
1453 if (get_frame_unwind_stop_reason (this_frame) == UNWIND_UNAVAILABLE)
1454 throw_error (NOT_AVAILABLE_ERROR,
1455 _("can't compute CFA for this frame: "
1456 "required registers or memory are unavailable"));
1458 if (get_frame_id (this_frame).stack_status != FID_STACK_VALID)
1459 throw_error (NOT_AVAILABLE_ERROR,
1460 _("can't compute CFA for this frame: "
1461 "frame base not available"));
1463 return get_frame_base (this_frame);
1466 const struct objfile_data *dwarf2_frame_objfile_data;
1469 read_1_byte (bfd *abfd, const gdb_byte *buf)
1471 return bfd_get_8 (abfd, buf);
1475 read_4_bytes (bfd *abfd, const gdb_byte *buf)
1477 return bfd_get_32 (abfd, buf);
1481 read_8_bytes (bfd *abfd, const gdb_byte *buf)
1483 return bfd_get_64 (abfd, buf);
1487 read_initial_length (bfd *abfd, const gdb_byte *buf,
1488 unsigned int *bytes_read_ptr)
1492 result = bfd_get_32 (abfd, buf);
1493 if (result == 0xffffffff)
1495 result = bfd_get_64 (abfd, buf + 4);
1496 *bytes_read_ptr = 12;
1499 *bytes_read_ptr = 4;
1505 /* Pointer encoding helper functions. */
1507 /* GCC supports exception handling based on DWARF2 CFI. However, for
1508 technical reasons, it encodes addresses in its FDE's in a different
1509 way. Several "pointer encodings" are supported. The encoding
1510 that's used for a particular FDE is determined by the 'R'
1511 augmentation in the associated CIE. The argument of this
1512 augmentation is a single byte.
1514 The address can be encoded as 2 bytes, 4 bytes, 8 bytes, or as a
1515 LEB128. This is encoded in bits 0, 1 and 2. Bit 3 encodes whether
1516 the address is signed or unsigned. Bits 4, 5 and 6 encode how the
1517 address should be interpreted (absolute, relative to the current
1518 position in the FDE, ...). Bit 7, indicates that the address
1519 should be dereferenced. */
1522 encoding_for_size (unsigned int size)
1527 return DW_EH_PE_udata2;
1529 return DW_EH_PE_udata4;
1531 return DW_EH_PE_udata8;
1533 internal_error (__FILE__, __LINE__, _("Unsupported address size"));
1538 read_encoded_value (struct comp_unit *unit, gdb_byte encoding,
1539 int ptr_len, const gdb_byte *buf,
1540 unsigned int *bytes_read_ptr,
1541 CORE_ADDR func_base)
1546 /* GCC currently doesn't generate DW_EH_PE_indirect encodings for
1548 if (encoding & DW_EH_PE_indirect)
1549 internal_error (__FILE__, __LINE__,
1550 _("Unsupported encoding: DW_EH_PE_indirect"));
1552 *bytes_read_ptr = 0;
1554 switch (encoding & 0x70)
1556 case DW_EH_PE_absptr:
1559 case DW_EH_PE_pcrel:
1560 base = bfd_get_section_vma (unit->abfd, unit->dwarf_frame_section);
1561 base += (buf - unit->dwarf_frame_buffer);
1563 case DW_EH_PE_datarel:
1566 case DW_EH_PE_textrel:
1569 case DW_EH_PE_funcrel:
1572 case DW_EH_PE_aligned:
1574 offset = buf - unit->dwarf_frame_buffer;
1575 if ((offset % ptr_len) != 0)
1577 *bytes_read_ptr = ptr_len - (offset % ptr_len);
1578 buf += *bytes_read_ptr;
1582 internal_error (__FILE__, __LINE__,
1583 _("Invalid or unsupported encoding"));
1586 if ((encoding & 0x07) == 0x00)
1588 encoding |= encoding_for_size (ptr_len);
1589 if (bfd_get_sign_extend_vma (unit->abfd))
1590 encoding |= DW_EH_PE_signed;
1593 switch (encoding & 0x0f)
1595 case DW_EH_PE_uleb128:
1598 const gdb_byte *end_buf = buf + (sizeof (value) + 1) * 8 / 7;
1600 *bytes_read_ptr += safe_read_uleb128 (buf, end_buf, &value) - buf;
1601 return base + value;
1603 case DW_EH_PE_udata2:
1604 *bytes_read_ptr += 2;
1605 return (base + bfd_get_16 (unit->abfd, (bfd_byte *) buf));
1606 case DW_EH_PE_udata4:
1607 *bytes_read_ptr += 4;
1608 return (base + bfd_get_32 (unit->abfd, (bfd_byte *) buf));
1609 case DW_EH_PE_udata8:
1610 *bytes_read_ptr += 8;
1611 return (base + bfd_get_64 (unit->abfd, (bfd_byte *) buf));
1612 case DW_EH_PE_sleb128:
1615 const gdb_byte *end_buf = buf + (sizeof (value) + 1) * 8 / 7;
1617 *bytes_read_ptr += safe_read_sleb128 (buf, end_buf, &value) - buf;
1618 return base + value;
1620 case DW_EH_PE_sdata2:
1621 *bytes_read_ptr += 2;
1622 return (base + bfd_get_signed_16 (unit->abfd, (bfd_byte *) buf));
1623 case DW_EH_PE_sdata4:
1624 *bytes_read_ptr += 4;
1625 return (base + bfd_get_signed_32 (unit->abfd, (bfd_byte *) buf));
1626 case DW_EH_PE_sdata8:
1627 *bytes_read_ptr += 8;
1628 return (base + bfd_get_signed_64 (unit->abfd, (bfd_byte *) buf));
1630 internal_error (__FILE__, __LINE__,
1631 _("Invalid or unsupported encoding"));
1637 bsearch_cie_cmp (const void *key, const void *element)
1639 ULONGEST cie_pointer = *(ULONGEST *) key;
1640 struct dwarf2_cie *cie = *(struct dwarf2_cie **) element;
1642 if (cie_pointer == cie->cie_pointer)
1645 return (cie_pointer < cie->cie_pointer) ? -1 : 1;
1648 /* Find CIE with the given CIE_POINTER in CIE_TABLE. */
1649 static struct dwarf2_cie *
1650 find_cie (struct dwarf2_cie_table *cie_table, ULONGEST cie_pointer)
1652 struct dwarf2_cie **p_cie;
1654 /* The C standard (ISO/IEC 9899:TC2) requires the BASE argument to
1655 bsearch be non-NULL. */
1656 if (cie_table->entries == NULL)
1658 gdb_assert (cie_table->num_entries == 0);
1662 p_cie = ((struct dwarf2_cie **)
1663 bsearch (&cie_pointer, cie_table->entries, cie_table->num_entries,
1664 sizeof (cie_table->entries[0]), bsearch_cie_cmp));
1670 /* Add a pointer to new CIE to the CIE_TABLE, allocating space for it. */
1672 add_cie (struct dwarf2_cie_table *cie_table, struct dwarf2_cie *cie)
1674 const int n = cie_table->num_entries;
1677 || cie_table->entries[n - 1]->cie_pointer < cie->cie_pointer);
1680 = XRESIZEVEC (struct dwarf2_cie *, cie_table->entries, n + 1);
1681 cie_table->entries[n] = cie;
1682 cie_table->num_entries = n + 1;
1686 bsearch_fde_cmp (const void *key, const void *element)
1688 CORE_ADDR seek_pc = *(CORE_ADDR *) key;
1689 struct dwarf2_fde *fde = *(struct dwarf2_fde **) element;
1691 if (seek_pc < fde->initial_location)
1693 if (seek_pc < fde->initial_location + fde->address_range)
1698 /* Find the FDE for *PC. Return a pointer to the FDE, and store the
1699 inital location associated with it into *PC. */
1701 static struct dwarf2_fde *
1702 dwarf2_frame_find_fde (CORE_ADDR *pc, CORE_ADDR *out_offset)
1704 for (objfile *objfile : current_program_space->objfiles ())
1706 struct dwarf2_fde_table *fde_table;
1707 struct dwarf2_fde **p_fde;
1711 fde_table = ((struct dwarf2_fde_table *)
1712 objfile_data (objfile, dwarf2_frame_objfile_data));
1713 if (fde_table == NULL)
1715 dwarf2_build_frame_info (objfile);
1716 fde_table = ((struct dwarf2_fde_table *)
1717 objfile_data (objfile, dwarf2_frame_objfile_data));
1719 gdb_assert (fde_table != NULL);
1721 if (fde_table->num_entries == 0)
1724 gdb_assert (objfile->section_offsets);
1725 offset = ANOFFSET (objfile->section_offsets, SECT_OFF_TEXT (objfile));
1727 gdb_assert (fde_table->num_entries > 0);
1728 if (*pc < offset + fde_table->entries[0]->initial_location)
1731 seek_pc = *pc - offset;
1732 p_fde = ((struct dwarf2_fde **)
1733 bsearch (&seek_pc, fde_table->entries, fde_table->num_entries,
1734 sizeof (fde_table->entries[0]), bsearch_fde_cmp));
1737 *pc = (*p_fde)->initial_location + offset;
1739 *out_offset = offset;
1746 /* Add a pointer to new FDE to the FDE_TABLE, allocating space for it. */
1748 add_fde (struct dwarf2_fde_table *fde_table, struct dwarf2_fde *fde)
1750 if (fde->address_range == 0)
1751 /* Discard useless FDEs. */
1754 fde_table->num_entries += 1;
1755 fde_table->entries = XRESIZEVEC (struct dwarf2_fde *, fde_table->entries,
1756 fde_table->num_entries);
1757 fde_table->entries[fde_table->num_entries - 1] = fde;
1760 #define DW64_CIE_ID 0xffffffffffffffffULL
1762 /* Defines the type of eh_frames that are expected to be decoded: CIE, FDE
1767 EH_CIE_TYPE_ID = 1 << 0,
1768 EH_FDE_TYPE_ID = 1 << 1,
1769 EH_CIE_OR_FDE_TYPE_ID = EH_CIE_TYPE_ID | EH_FDE_TYPE_ID
1772 static const gdb_byte *decode_frame_entry (struct comp_unit *unit,
1773 const gdb_byte *start,
1775 struct dwarf2_cie_table *cie_table,
1776 struct dwarf2_fde_table *fde_table,
1777 enum eh_frame_type entry_type);
1779 /* Decode the next CIE or FDE, entry_type specifies the expected type.
1780 Return NULL if invalid input, otherwise the next byte to be processed. */
1782 static const gdb_byte *
1783 decode_frame_entry_1 (struct comp_unit *unit, const gdb_byte *start,
1785 struct dwarf2_cie_table *cie_table,
1786 struct dwarf2_fde_table *fde_table,
1787 enum eh_frame_type entry_type)
1789 struct gdbarch *gdbarch = get_objfile_arch (unit->objfile);
1790 const gdb_byte *buf, *end;
1792 unsigned int bytes_read;
1795 ULONGEST cie_pointer;
1800 length = read_initial_length (unit->abfd, buf, &bytes_read);
1804 /* Are we still within the section? */
1805 if (end > unit->dwarf_frame_buffer + unit->dwarf_frame_size)
1811 /* Distinguish between 32 and 64-bit encoded frame info. */
1812 dwarf64_p = (bytes_read == 12);
1814 /* In a .eh_frame section, zero is used to distinguish CIEs from FDEs. */
1818 cie_id = DW64_CIE_ID;
1824 cie_pointer = read_8_bytes (unit->abfd, buf);
1829 cie_pointer = read_4_bytes (unit->abfd, buf);
1833 if (cie_pointer == cie_id)
1835 /* This is a CIE. */
1836 struct dwarf2_cie *cie;
1838 unsigned int cie_version;
1840 /* Check that a CIE was expected. */
1841 if ((entry_type & EH_CIE_TYPE_ID) == 0)
1842 error (_("Found a CIE when not expecting it."));
1844 /* Record the offset into the .debug_frame section of this CIE. */
1845 cie_pointer = start - unit->dwarf_frame_buffer;
1847 /* Check whether we've already read it. */
1848 if (find_cie (cie_table, cie_pointer))
1851 cie = XOBNEW (&unit->objfile->objfile_obstack, struct dwarf2_cie);
1852 cie->initial_instructions = NULL;
1853 cie->cie_pointer = cie_pointer;
1855 /* The encoding for FDE's in a normal .debug_frame section
1856 depends on the target address size. */
1857 cie->encoding = DW_EH_PE_absptr;
1859 /* We'll determine the final value later, but we need to
1860 initialize it conservatively. */
1861 cie->signal_frame = 0;
1863 /* Check version number. */
1864 cie_version = read_1_byte (unit->abfd, buf);
1865 if (cie_version != 1 && cie_version != 3 && cie_version != 4)
1867 cie->version = cie_version;
1870 /* Interpret the interesting bits of the augmentation. */
1871 cie->augmentation = augmentation = (char *) buf;
1872 buf += (strlen (augmentation) + 1);
1874 /* Ignore armcc augmentations. We only use them for quirks,
1875 and that doesn't happen until later. */
1876 if (startswith (augmentation, "armcc"))
1877 augmentation += strlen (augmentation);
1879 /* The GCC 2.x "eh" augmentation has a pointer immediately
1880 following the augmentation string, so it must be handled
1882 if (augmentation[0] == 'e' && augmentation[1] == 'h')
1885 buf += gdbarch_ptr_bit (gdbarch) / TARGET_CHAR_BIT;
1889 if (cie->version >= 4)
1891 /* FIXME: check that this is the same as from the CU header. */
1892 cie->addr_size = read_1_byte (unit->abfd, buf);
1894 cie->segment_size = read_1_byte (unit->abfd, buf);
1899 cie->addr_size = gdbarch_dwarf2_addr_size (gdbarch);
1900 cie->segment_size = 0;
1902 /* Address values in .eh_frame sections are defined to have the
1903 target's pointer size. Watchout: This breaks frame info for
1904 targets with pointer size < address size, unless a .debug_frame
1905 section exists as well. */
1907 cie->ptr_size = gdbarch_ptr_bit (gdbarch) / TARGET_CHAR_BIT;
1909 cie->ptr_size = cie->addr_size;
1911 buf = gdb_read_uleb128 (buf, end, &uleb128);
1914 cie->code_alignment_factor = uleb128;
1916 buf = gdb_read_sleb128 (buf, end, &sleb128);
1919 cie->data_alignment_factor = sleb128;
1921 if (cie_version == 1)
1923 cie->return_address_register = read_1_byte (unit->abfd, buf);
1928 buf = gdb_read_uleb128 (buf, end, &uleb128);
1931 cie->return_address_register = uleb128;
1934 cie->return_address_register
1935 = dwarf2_frame_adjust_regnum (gdbarch,
1936 cie->return_address_register,
1939 cie->saw_z_augmentation = (*augmentation == 'z');
1940 if (cie->saw_z_augmentation)
1942 uint64_t uleb_length;
1944 buf = gdb_read_uleb128 (buf, end, &uleb_length);
1947 cie->initial_instructions = buf + uleb_length;
1951 while (*augmentation)
1953 /* "L" indicates a byte showing how the LSDA pointer is encoded. */
1954 if (*augmentation == 'L')
1961 /* "R" indicates a byte indicating how FDE addresses are encoded. */
1962 else if (*augmentation == 'R')
1964 cie->encoding = *buf++;
1968 /* "P" indicates a personality routine in the CIE augmentation. */
1969 else if (*augmentation == 'P')
1971 /* Skip. Avoid indirection since we throw away the result. */
1972 gdb_byte encoding = (*buf++) & ~DW_EH_PE_indirect;
1973 read_encoded_value (unit, encoding, cie->ptr_size,
1974 buf, &bytes_read, 0);
1979 /* "S" indicates a signal frame, such that the return
1980 address must not be decremented to locate the call frame
1981 info for the previous frame; it might even be the first
1982 instruction of a function, so decrementing it would take
1983 us to a different function. */
1984 else if (*augmentation == 'S')
1986 cie->signal_frame = 1;
1990 /* Otherwise we have an unknown augmentation. Assume that either
1991 there is no augmentation data, or we saw a 'z' prefix. */
1994 if (cie->initial_instructions)
1995 buf = cie->initial_instructions;
2000 cie->initial_instructions = buf;
2004 add_cie (cie_table, cie);
2008 /* This is a FDE. */
2009 struct dwarf2_fde *fde;
2012 /* Check that an FDE was expected. */
2013 if ((entry_type & EH_FDE_TYPE_ID) == 0)
2014 error (_("Found an FDE when not expecting it."));
2016 /* In an .eh_frame section, the CIE pointer is the delta between the
2017 address within the FDE where the CIE pointer is stored and the
2018 address of the CIE. Convert it to an offset into the .eh_frame
2022 cie_pointer = buf - unit->dwarf_frame_buffer - cie_pointer;
2023 cie_pointer -= (dwarf64_p ? 8 : 4);
2026 /* In either case, validate the result is still within the section. */
2027 if (cie_pointer >= unit->dwarf_frame_size)
2030 fde = XOBNEW (&unit->objfile->objfile_obstack, struct dwarf2_fde);
2031 fde->cie = find_cie (cie_table, cie_pointer);
2032 if (fde->cie == NULL)
2034 decode_frame_entry (unit, unit->dwarf_frame_buffer + cie_pointer,
2035 eh_frame_p, cie_table, fde_table,
2037 fde->cie = find_cie (cie_table, cie_pointer);
2040 gdb_assert (fde->cie != NULL);
2042 addr = read_encoded_value (unit, fde->cie->encoding, fde->cie->ptr_size,
2043 buf, &bytes_read, 0);
2044 fde->initial_location = gdbarch_adjust_dwarf2_addr (gdbarch, addr);
2047 fde->address_range =
2048 read_encoded_value (unit, fde->cie->encoding & 0x0f,
2049 fde->cie->ptr_size, buf, &bytes_read, 0);
2050 addr = gdbarch_adjust_dwarf2_addr (gdbarch, addr + fde->address_range);
2051 fde->address_range = addr - fde->initial_location;
2054 /* A 'z' augmentation in the CIE implies the presence of an
2055 augmentation field in the FDE as well. The only thing known
2056 to be in here at present is the LSDA entry for EH. So we
2057 can skip the whole thing. */
2058 if (fde->cie->saw_z_augmentation)
2060 uint64_t uleb_length;
2062 buf = gdb_read_uleb128 (buf, end, &uleb_length);
2070 fde->instructions = buf;
2073 fde->eh_frame_p = eh_frame_p;
2075 add_fde (fde_table, fde);
2081 /* Read a CIE or FDE in BUF and decode it. Entry_type specifies whether we
2082 expect an FDE or a CIE. */
2084 static const gdb_byte *
2085 decode_frame_entry (struct comp_unit *unit, const gdb_byte *start,
2087 struct dwarf2_cie_table *cie_table,
2088 struct dwarf2_fde_table *fde_table,
2089 enum eh_frame_type entry_type)
2091 enum { NONE, ALIGN4, ALIGN8, FAIL } workaround = NONE;
2092 const gdb_byte *ret;
2093 ptrdiff_t start_offset;
2097 ret = decode_frame_entry_1 (unit, start, eh_frame_p,
2098 cie_table, fde_table, entry_type);
2102 /* We have corrupt input data of some form. */
2104 /* ??? Try, weakly, to work around compiler/assembler/linker bugs
2105 and mismatches wrt padding and alignment of debug sections. */
2106 /* Note that there is no requirement in the standard for any
2107 alignment at all in the frame unwind sections. Testing for
2108 alignment before trying to interpret data would be incorrect.
2110 However, GCC traditionally arranged for frame sections to be
2111 sized such that the FDE length and CIE fields happen to be
2112 aligned (in theory, for performance). This, unfortunately,
2113 was done with .align directives, which had the side effect of
2114 forcing the section to be aligned by the linker.
2116 This becomes a problem when you have some other producer that
2117 creates frame sections that are not as strictly aligned. That
2118 produces a hole in the frame info that gets filled by the
2121 The GCC behaviour is arguably a bug, but it's effectively now
2122 part of the ABI, so we're now stuck with it, at least at the
2123 object file level. A smart linker may decide, in the process
2124 of compressing duplicate CIE information, that it can rewrite
2125 the entire output section without this extra padding. */
2127 start_offset = start - unit->dwarf_frame_buffer;
2128 if (workaround < ALIGN4 && (start_offset & 3) != 0)
2130 start += 4 - (start_offset & 3);
2131 workaround = ALIGN4;
2134 if (workaround < ALIGN8 && (start_offset & 7) != 0)
2136 start += 8 - (start_offset & 7);
2137 workaround = ALIGN8;
2141 /* Nothing left to try. Arrange to return as if we've consumed
2142 the entire input section. Hopefully we'll get valid info from
2143 the other of .debug_frame/.eh_frame. */
2145 ret = unit->dwarf_frame_buffer + unit->dwarf_frame_size;
2156 Corrupt data in %s:%s; align 4 workaround apparently succeeded"),
2157 unit->dwarf_frame_section->owner->filename,
2158 unit->dwarf_frame_section->name);
2163 Corrupt data in %s:%s; align 8 workaround apparently succeeded"),
2164 unit->dwarf_frame_section->owner->filename,
2165 unit->dwarf_frame_section->name);
2169 complaint (_("Corrupt data in %s:%s"),
2170 unit->dwarf_frame_section->owner->filename,
2171 unit->dwarf_frame_section->name);
2179 qsort_fde_cmp (const void *a, const void *b)
2181 struct dwarf2_fde *aa = *(struct dwarf2_fde **)a;
2182 struct dwarf2_fde *bb = *(struct dwarf2_fde **)b;
2184 if (aa->initial_location == bb->initial_location)
2186 if (aa->address_range != bb->address_range
2187 && aa->eh_frame_p == 0 && bb->eh_frame_p == 0)
2188 /* Linker bug, e.g. gold/10400.
2189 Work around it by keeping stable sort order. */
2190 return (a < b) ? -1 : 1;
2192 /* Put eh_frame entries after debug_frame ones. */
2193 return aa->eh_frame_p - bb->eh_frame_p;
2196 return (aa->initial_location < bb->initial_location) ? -1 : 1;
2200 dwarf2_build_frame_info (struct objfile *objfile)
2202 struct comp_unit *unit;
2203 const gdb_byte *frame_ptr;
2204 struct dwarf2_cie_table cie_table;
2205 struct dwarf2_fde_table fde_table;
2206 struct dwarf2_fde_table *fde_table2;
2208 cie_table.num_entries = 0;
2209 cie_table.entries = NULL;
2211 fde_table.num_entries = 0;
2212 fde_table.entries = NULL;
2214 /* Build a minimal decoding of the DWARF2 compilation unit. */
2215 unit = XOBNEW (&objfile->objfile_obstack, comp_unit);
2216 unit->abfd = objfile->obfd;
2217 unit->objfile = objfile;
2221 if (objfile->separate_debug_objfile_backlink == NULL)
2223 /* Do not read .eh_frame from separate file as they must be also
2224 present in the main file. */
2225 dwarf2_get_section_info (objfile, DWARF2_EH_FRAME,
2226 &unit->dwarf_frame_section,
2227 &unit->dwarf_frame_buffer,
2228 &unit->dwarf_frame_size);
2229 if (unit->dwarf_frame_size)
2231 asection *got, *txt;
2233 /* FIXME: kettenis/20030602: This is the DW_EH_PE_datarel base
2234 that is used for the i386/amd64 target, which currently is
2235 the only target in GCC that supports/uses the
2236 DW_EH_PE_datarel encoding. */
2237 got = bfd_get_section_by_name (unit->abfd, ".got");
2239 unit->dbase = got->vma;
2241 /* GCC emits the DW_EH_PE_textrel encoding type on sh and ia64
2243 txt = bfd_get_section_by_name (unit->abfd, ".text");
2245 unit->tbase = txt->vma;
2249 frame_ptr = unit->dwarf_frame_buffer;
2250 while (frame_ptr < unit->dwarf_frame_buffer + unit->dwarf_frame_size)
2251 frame_ptr = decode_frame_entry (unit, frame_ptr, 1,
2252 &cie_table, &fde_table,
2253 EH_CIE_OR_FDE_TYPE_ID);
2256 catch (const gdb_exception_RETURN_MASK_ERROR &e)
2258 warning (_("skipping .eh_frame info of %s: %s"),
2259 objfile_name (objfile), e.what ());
2261 if (fde_table.num_entries != 0)
2263 xfree (fde_table.entries);
2264 fde_table.entries = NULL;
2265 fde_table.num_entries = 0;
2267 /* The cie_table is discarded by the next if. */
2270 if (cie_table.num_entries != 0)
2272 /* Reinit cie_table: debug_frame has different CIEs. */
2273 xfree (cie_table.entries);
2274 cie_table.num_entries = 0;
2275 cie_table.entries = NULL;
2280 dwarf2_get_section_info (objfile, DWARF2_DEBUG_FRAME,
2281 &unit->dwarf_frame_section,
2282 &unit->dwarf_frame_buffer,
2283 &unit->dwarf_frame_size);
2284 if (unit->dwarf_frame_size)
2286 int num_old_fde_entries = fde_table.num_entries;
2290 frame_ptr = unit->dwarf_frame_buffer;
2291 while (frame_ptr < unit->dwarf_frame_buffer + unit->dwarf_frame_size)
2292 frame_ptr = decode_frame_entry (unit, frame_ptr, 0,
2293 &cie_table, &fde_table,
2294 EH_CIE_OR_FDE_TYPE_ID);
2296 catch (const gdb_exception_RETURN_MASK_ERROR &e)
2298 warning (_("skipping .debug_frame info of %s: %s"),
2299 objfile_name (objfile), e.what ());
2301 if (fde_table.num_entries != 0)
2303 fde_table.num_entries = num_old_fde_entries;
2304 if (num_old_fde_entries == 0)
2306 xfree (fde_table.entries);
2307 fde_table.entries = NULL;
2312 = XRESIZEVEC (struct dwarf2_fde *, fde_table.entries,
2313 fde_table.num_entries);
2316 fde_table.num_entries = num_old_fde_entries;
2317 /* The cie_table is discarded by the next if. */
2321 /* Discard the cie_table, it is no longer needed. */
2322 if (cie_table.num_entries != 0)
2324 xfree (cie_table.entries);
2325 cie_table.entries = NULL; /* Paranoia. */
2326 cie_table.num_entries = 0; /* Paranoia. */
2329 /* Copy fde_table to obstack: it is needed at runtime. */
2330 fde_table2 = XOBNEW (&objfile->objfile_obstack, struct dwarf2_fde_table);
2332 if (fde_table.num_entries == 0)
2334 fde_table2->entries = NULL;
2335 fde_table2->num_entries = 0;
2339 struct dwarf2_fde *fde_prev = NULL;
2340 struct dwarf2_fde *first_non_zero_fde = NULL;
2343 /* Prepare FDE table for lookups. */
2344 qsort (fde_table.entries, fde_table.num_entries,
2345 sizeof (fde_table.entries[0]), qsort_fde_cmp);
2347 /* Check for leftovers from --gc-sections. The GNU linker sets
2348 the relevant symbols to zero, but doesn't zero the FDE *end*
2349 ranges because there's no relocation there. It's (offset,
2350 length), not (start, end). On targets where address zero is
2351 just another valid address this can be a problem, since the
2352 FDEs appear to be non-empty in the output --- we could pick
2353 out the wrong FDE. To work around this, when overlaps are
2354 detected, we prefer FDEs that do not start at zero.
2356 Start by finding the first FDE with non-zero start. Below
2357 we'll discard all FDEs that start at zero and overlap this
2359 for (i = 0; i < fde_table.num_entries; i++)
2361 struct dwarf2_fde *fde = fde_table.entries[i];
2363 if (fde->initial_location != 0)
2365 first_non_zero_fde = fde;
2370 /* Since we'll be doing bsearch, squeeze out identical (except
2371 for eh_frame_p) fde entries so bsearch result is predictable.
2372 Also discard leftovers from --gc-sections. */
2373 fde_table2->num_entries = 0;
2374 for (i = 0; i < fde_table.num_entries; i++)
2376 struct dwarf2_fde *fde = fde_table.entries[i];
2378 if (fde->initial_location == 0
2379 && first_non_zero_fde != NULL
2380 && (first_non_zero_fde->initial_location
2381 < fde->initial_location + fde->address_range))
2384 if (fde_prev != NULL
2385 && fde_prev->initial_location == fde->initial_location)
2388 obstack_grow (&objfile->objfile_obstack, &fde_table.entries[i],
2389 sizeof (fde_table.entries[0]));
2390 ++fde_table2->num_entries;
2394 = (struct dwarf2_fde **) obstack_finish (&objfile->objfile_obstack);
2396 /* Discard the original fde_table. */
2397 xfree (fde_table.entries);
2400 set_objfile_data (objfile, dwarf2_frame_objfile_data, fde_table2);
2403 /* Handle 'maintenance show dwarf unwinders'. */
2406 show_dwarf_unwinders_enabled_p (struct ui_file *file, int from_tty,
2407 struct cmd_list_element *c,
2410 fprintf_filtered (file,
2411 _("The DWARF stack unwinders are currently %s.\n"),
2416 _initialize_dwarf2_frame (void)
2418 dwarf2_frame_data = gdbarch_data_register_pre_init (dwarf2_frame_init);
2419 dwarf2_frame_objfile_data = register_objfile_data ();
2421 add_setshow_boolean_cmd ("unwinders", class_obscure,
2422 &dwarf2_frame_unwinders_enabled_p , _("\
2423 Set whether the DWARF stack frame unwinders are used."), _("\
2424 Show whether the DWARF stack frame unwinders are used."), _("\
2425 When enabled the DWARF stack frame unwinders can be used for architectures\n\
2426 that support the DWARF unwinders. Enabling the DWARF unwinders for an\n\
2427 architecture that doesn't support them will have no effect."),
2429 show_dwarf_unwinders_enabled_p,
2431 &show_dwarf_cmdlist);
2434 selftests::register_test_foreach_arch ("execute_cfa_program",
2435 selftests::execute_cfa_program_test);