1 /* Frame unwinder for frames with DWARF Call Frame Information.
3 Copyright (C) 2003-2016 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"
39 #include "dwarf2loc.h"
40 #include "dwarf2-frame-tailcall.h"
44 /* Call Frame Information (CFI). */
46 /* Common Information Entry (CIE). */
50 /* Computation Unit for this CIE. */
51 struct comp_unit *unit;
53 /* Offset into the .debug_frame section where this CIE was found.
54 Used to identify this CIE. */
57 /* Constant that is factored out of all advance location
59 ULONGEST code_alignment_factor;
61 /* Constants that is factored out of all offset instructions. */
62 LONGEST data_alignment_factor;
64 /* Return address column. */
65 ULONGEST return_address_register;
67 /* Instruction sequence to initialize a register set. */
68 const gdb_byte *initial_instructions;
71 /* Saved augmentation, in case it's needed later. */
74 /* Encoding of addresses. */
77 /* Target address size in bytes. */
80 /* Target pointer size in bytes. */
83 /* True if a 'z' augmentation existed. */
84 unsigned char saw_z_augmentation;
86 /* True if an 'S' augmentation existed. */
87 unsigned char signal_frame;
89 /* The version recorded in the CIE. */
90 unsigned char version;
92 /* The segment size. */
93 unsigned char segment_size;
96 struct dwarf2_cie_table
99 struct dwarf2_cie **entries;
102 /* Frame Description Entry (FDE). */
106 /* CIE for this FDE. */
107 struct dwarf2_cie *cie;
109 /* First location associated with this FDE. */
110 CORE_ADDR initial_location;
112 /* Number of bytes of program instructions described by this FDE. */
113 CORE_ADDR address_range;
115 /* Instruction sequence. */
116 const gdb_byte *instructions;
119 /* True if this FDE is read from a .eh_frame instead of a .debug_frame
121 unsigned char eh_frame_p;
124 struct dwarf2_fde_table
127 struct dwarf2_fde **entries;
130 /* A minimal decoding of DWARF2 compilation units. We only decode
131 what's needed to get to the call frame information. */
135 /* Keep the bfd convenient. */
138 struct objfile *objfile;
140 /* Pointer to the .debug_frame section loaded into memory. */
141 const gdb_byte *dwarf_frame_buffer;
143 /* Length of the loaded .debug_frame section. */
144 bfd_size_type dwarf_frame_size;
146 /* Pointer to the .debug_frame section. */
147 asection *dwarf_frame_section;
149 /* Base for DW_EH_PE_datarel encodings. */
152 /* Base for DW_EH_PE_textrel encodings. */
156 static struct dwarf2_fde *dwarf2_frame_find_fde (CORE_ADDR *pc,
157 CORE_ADDR *out_offset);
159 static int dwarf2_frame_adjust_regnum (struct gdbarch *gdbarch, int regnum,
162 static CORE_ADDR read_encoded_value (struct comp_unit *unit, gdb_byte encoding,
163 int ptr_len, const gdb_byte *buf,
164 unsigned int *bytes_read_ptr,
165 CORE_ADDR func_base);
175 struct dwarf2_frame_state_reg_info
177 struct dwarf2_frame_state_reg *reg;
182 enum cfa_how_kind cfa_how;
183 const gdb_byte *cfa_exp;
185 /* Used to implement DW_CFA_remember_state. */
186 struct dwarf2_frame_state_reg_info *prev;
189 /* Structure describing a frame state. */
191 struct dwarf2_frame_state
193 /* Each register save state can be described in terms of a CFA slot,
194 another register, or a location expression. */
195 struct dwarf2_frame_state_reg_info regs;
197 /* The PC described by the current frame state. */
200 /* Initial register set from the CIE.
201 Used to implement DW_CFA_restore. */
202 struct dwarf2_frame_state_reg_info initial;
204 /* The information we care about from the CIE. */
207 ULONGEST retaddr_column;
209 /* Flags for known producer quirks. */
211 /* The ARM compilers, in DWARF2 mode, assume that DW_CFA_def_cfa
212 and DW_CFA_def_cfa_offset takes a factored offset. */
213 int armcc_cfa_offsets_sf;
215 /* The ARM compilers, in DWARF2 or DWARF3 mode, may assume that
216 the CFA is defined as REG - OFFSET rather than REG + OFFSET. */
217 int armcc_cfa_offsets_reversed;
220 /* Store the length the expression for the CFA in the `cfa_reg' field,
221 which is unused in that case. */
222 #define cfa_exp_len cfa_reg
224 /* Assert that the register set RS is large enough to store gdbarch_num_regs
225 columns. If necessary, enlarge the register set. */
228 dwarf2_frame_state_alloc_regs (struct dwarf2_frame_state_reg_info *rs,
231 size_t size = sizeof (struct dwarf2_frame_state_reg);
233 if (num_regs <= rs->num_regs)
236 rs->reg = (struct dwarf2_frame_state_reg *)
237 xrealloc (rs->reg, num_regs * size);
239 /* Initialize newly allocated registers. */
240 memset (rs->reg + rs->num_regs, 0, (num_regs - rs->num_regs) * size);
241 rs->num_regs = num_regs;
244 /* Copy the register columns in register set RS into newly allocated
245 memory and return a pointer to this newly created copy. */
247 static struct dwarf2_frame_state_reg *
248 dwarf2_frame_state_copy_regs (struct dwarf2_frame_state_reg_info *rs)
250 size_t size = rs->num_regs * sizeof (struct dwarf2_frame_state_reg);
251 struct dwarf2_frame_state_reg *reg;
253 reg = (struct dwarf2_frame_state_reg *) xmalloc (size);
254 memcpy (reg, rs->reg, size);
259 /* Release the memory allocated to register set RS. */
262 dwarf2_frame_state_free_regs (struct dwarf2_frame_state_reg_info *rs)
266 dwarf2_frame_state_free_regs (rs->prev);
273 /* Release the memory allocated to the frame state FS. */
276 dwarf2_frame_state_free (void *p)
278 struct dwarf2_frame_state *fs = (struct dwarf2_frame_state *) p;
280 dwarf2_frame_state_free_regs (fs->initial.prev);
281 dwarf2_frame_state_free_regs (fs->regs.prev);
282 xfree (fs->initial.reg);
283 xfree (fs->regs.reg);
288 /* Helper functions for execute_stack_op. */
291 read_addr_from_reg (void *baton, int reg)
293 struct frame_info *this_frame = (struct frame_info *) baton;
294 struct gdbarch *gdbarch = get_frame_arch (this_frame);
295 int regnum = dwarf_reg_to_regnum_or_error (gdbarch, reg);
297 return address_from_register (regnum, this_frame);
300 /* Implement struct dwarf_expr_context_funcs' "get_reg_value" callback. */
302 static struct value *
303 get_reg_value (void *baton, struct type *type, int reg)
305 struct frame_info *this_frame = (struct frame_info *) baton;
306 struct gdbarch *gdbarch = get_frame_arch (this_frame);
307 int regnum = dwarf_reg_to_regnum_or_error (gdbarch, reg);
309 return value_from_register (type, regnum, this_frame);
313 read_mem (void *baton, gdb_byte *buf, CORE_ADDR addr, size_t len)
315 read_memory (addr, buf, len);
318 /* Execute the required actions for both the DW_CFA_restore and
319 DW_CFA_restore_extended instructions. */
321 dwarf2_restore_rule (struct gdbarch *gdbarch, ULONGEST reg_num,
322 struct dwarf2_frame_state *fs, int eh_frame_p)
326 gdb_assert (fs->initial.reg);
327 reg = dwarf2_frame_adjust_regnum (gdbarch, reg_num, eh_frame_p);
328 dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1);
330 /* Check if this register was explicitly initialized in the
331 CIE initial instructions. If not, default the rule to
333 if (reg < fs->initial.num_regs)
334 fs->regs.reg[reg] = fs->initial.reg[reg];
336 fs->regs.reg[reg].how = DWARF2_FRAME_REG_UNSPECIFIED;
338 if (fs->regs.reg[reg].how == DWARF2_FRAME_REG_UNSPECIFIED)
340 int regnum = dwarf_reg_to_regnum (gdbarch, reg);
342 complaint (&symfile_complaints, _("\
343 incomplete CFI data; DW_CFA_restore unspecified\n\
344 register %s (#%d) at %s"),
345 gdbarch_register_name (gdbarch, regnum), regnum,
346 paddress (gdbarch, fs->pc));
350 /* Virtual method table for execute_stack_op below. */
352 static const struct dwarf_expr_context_funcs dwarf2_frame_ctx_funcs =
357 ctx_no_get_frame_base,
358 ctx_no_get_frame_cfa,
360 ctx_no_get_tls_address,
362 ctx_no_get_base_type,
363 ctx_no_push_dwarf_reg_entry_value,
364 ctx_no_get_addr_index
368 execute_stack_op (const gdb_byte *exp, ULONGEST len, int addr_size,
369 CORE_ADDR offset, struct frame_info *this_frame,
370 CORE_ADDR initial, int initial_in_stack_memory)
372 struct dwarf_expr_context *ctx;
374 struct cleanup *old_chain;
376 ctx = new_dwarf_expr_context ();
377 old_chain = make_cleanup_free_dwarf_expr_context (ctx);
378 make_cleanup_value_free_to_mark (value_mark ());
380 ctx->gdbarch = get_frame_arch (this_frame);
381 ctx->addr_size = addr_size;
382 ctx->ref_addr_size = -1;
383 ctx->offset = offset;
384 ctx->baton = this_frame;
385 ctx->funcs = &dwarf2_frame_ctx_funcs;
387 dwarf_expr_push_address (ctx, initial, initial_in_stack_memory);
388 dwarf_expr_eval (ctx, exp, len);
390 if (ctx->location == DWARF_VALUE_MEMORY)
391 result = dwarf_expr_fetch_address (ctx, 0);
392 else if (ctx->location == DWARF_VALUE_REGISTER)
393 result = read_addr_from_reg (this_frame,
394 value_as_long (dwarf_expr_fetch (ctx, 0)));
397 /* This is actually invalid DWARF, but if we ever do run across
398 it somehow, we might as well support it. So, instead, report
399 it as unimplemented. */
401 Not implemented: computing unwound register using explicit value operator"));
404 do_cleanups (old_chain);
410 /* Execute FDE program from INSN_PTR possibly up to INSN_END or up to inferior
411 PC. Modify FS state accordingly. Return current INSN_PTR where the
412 execution has stopped, one can resume it on the next call. */
414 static const gdb_byte *
415 execute_cfa_program (struct dwarf2_fde *fde, const gdb_byte *insn_ptr,
416 const gdb_byte *insn_end, struct gdbarch *gdbarch,
417 CORE_ADDR pc, struct dwarf2_frame_state *fs)
419 int eh_frame_p = fde->eh_frame_p;
420 unsigned int bytes_read;
421 enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
423 while (insn_ptr < insn_end && fs->pc <= pc)
425 gdb_byte insn = *insn_ptr++;
429 if ((insn & 0xc0) == DW_CFA_advance_loc)
430 fs->pc += (insn & 0x3f) * fs->code_align;
431 else if ((insn & 0xc0) == DW_CFA_offset)
434 reg = dwarf2_frame_adjust_regnum (gdbarch, reg, eh_frame_p);
435 insn_ptr = safe_read_uleb128 (insn_ptr, insn_end, &utmp);
436 offset = utmp * fs->data_align;
437 dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1);
438 fs->regs.reg[reg].how = DWARF2_FRAME_REG_SAVED_OFFSET;
439 fs->regs.reg[reg].loc.offset = offset;
441 else if ((insn & 0xc0) == DW_CFA_restore)
444 dwarf2_restore_rule (gdbarch, reg, fs, eh_frame_p);
451 fs->pc = read_encoded_value (fde->cie->unit, fde->cie->encoding,
452 fde->cie->ptr_size, insn_ptr,
453 &bytes_read, fde->initial_location);
454 /* Apply the objfile offset for relocatable objects. */
455 fs->pc += ANOFFSET (fde->cie->unit->objfile->section_offsets,
456 SECT_OFF_TEXT (fde->cie->unit->objfile));
457 insn_ptr += bytes_read;
460 case DW_CFA_advance_loc1:
461 utmp = extract_unsigned_integer (insn_ptr, 1, byte_order);
462 fs->pc += utmp * fs->code_align;
465 case DW_CFA_advance_loc2:
466 utmp = extract_unsigned_integer (insn_ptr, 2, byte_order);
467 fs->pc += utmp * fs->code_align;
470 case DW_CFA_advance_loc4:
471 utmp = extract_unsigned_integer (insn_ptr, 4, byte_order);
472 fs->pc += utmp * fs->code_align;
476 case DW_CFA_offset_extended:
477 insn_ptr = safe_read_uleb128 (insn_ptr, insn_end, ®);
478 reg = dwarf2_frame_adjust_regnum (gdbarch, reg, eh_frame_p);
479 insn_ptr = safe_read_uleb128 (insn_ptr, insn_end, &utmp);
480 offset = utmp * fs->data_align;
481 dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1);
482 fs->regs.reg[reg].how = DWARF2_FRAME_REG_SAVED_OFFSET;
483 fs->regs.reg[reg].loc.offset = offset;
486 case DW_CFA_restore_extended:
487 insn_ptr = safe_read_uleb128 (insn_ptr, insn_end, ®);
488 dwarf2_restore_rule (gdbarch, reg, fs, eh_frame_p);
491 case DW_CFA_undefined:
492 insn_ptr = safe_read_uleb128 (insn_ptr, insn_end, ®);
493 reg = dwarf2_frame_adjust_regnum (gdbarch, reg, eh_frame_p);
494 dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1);
495 fs->regs.reg[reg].how = DWARF2_FRAME_REG_UNDEFINED;
498 case DW_CFA_same_value:
499 insn_ptr = safe_read_uleb128 (insn_ptr, insn_end, ®);
500 reg = dwarf2_frame_adjust_regnum (gdbarch, reg, eh_frame_p);
501 dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1);
502 fs->regs.reg[reg].how = DWARF2_FRAME_REG_SAME_VALUE;
505 case DW_CFA_register:
506 insn_ptr = safe_read_uleb128 (insn_ptr, insn_end, ®);
507 reg = dwarf2_frame_adjust_regnum (gdbarch, reg, eh_frame_p);
508 insn_ptr = safe_read_uleb128 (insn_ptr, insn_end, &utmp);
509 utmp = dwarf2_frame_adjust_regnum (gdbarch, utmp, eh_frame_p);
510 dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1);
511 fs->regs.reg[reg].how = DWARF2_FRAME_REG_SAVED_REG;
512 fs->regs.reg[reg].loc.reg = utmp;
515 case DW_CFA_remember_state:
517 struct dwarf2_frame_state_reg_info *new_rs;
519 new_rs = XNEW (struct dwarf2_frame_state_reg_info);
521 fs->regs.reg = dwarf2_frame_state_copy_regs (&fs->regs);
522 fs->regs.prev = new_rs;
526 case DW_CFA_restore_state:
528 struct dwarf2_frame_state_reg_info *old_rs = fs->regs.prev;
532 complaint (&symfile_complaints, _("\
533 bad CFI data; mismatched DW_CFA_restore_state at %s"),
534 paddress (gdbarch, fs->pc));
538 xfree (fs->regs.reg);
546 insn_ptr = safe_read_uleb128 (insn_ptr, insn_end, ®);
547 fs->regs.cfa_reg = reg;
548 insn_ptr = safe_read_uleb128 (insn_ptr, insn_end, &utmp);
550 if (fs->armcc_cfa_offsets_sf)
551 utmp *= fs->data_align;
553 fs->regs.cfa_offset = utmp;
554 fs->regs.cfa_how = CFA_REG_OFFSET;
557 case DW_CFA_def_cfa_register:
558 insn_ptr = safe_read_uleb128 (insn_ptr, insn_end, ®);
559 fs->regs.cfa_reg = dwarf2_frame_adjust_regnum (gdbarch, reg,
561 fs->regs.cfa_how = CFA_REG_OFFSET;
564 case DW_CFA_def_cfa_offset:
565 insn_ptr = safe_read_uleb128 (insn_ptr, insn_end, &utmp);
567 if (fs->armcc_cfa_offsets_sf)
568 utmp *= fs->data_align;
570 fs->regs.cfa_offset = utmp;
571 /* cfa_how deliberately not set. */
577 case DW_CFA_def_cfa_expression:
578 insn_ptr = safe_read_uleb128 (insn_ptr, insn_end, &utmp);
579 fs->regs.cfa_exp_len = utmp;
580 fs->regs.cfa_exp = insn_ptr;
581 fs->regs.cfa_how = CFA_EXP;
582 insn_ptr += fs->regs.cfa_exp_len;
585 case DW_CFA_expression:
586 insn_ptr = safe_read_uleb128 (insn_ptr, insn_end, ®);
587 reg = dwarf2_frame_adjust_regnum (gdbarch, reg, eh_frame_p);
588 dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1);
589 insn_ptr = safe_read_uleb128 (insn_ptr, insn_end, &utmp);
590 fs->regs.reg[reg].loc.exp = insn_ptr;
591 fs->regs.reg[reg].exp_len = utmp;
592 fs->regs.reg[reg].how = DWARF2_FRAME_REG_SAVED_EXP;
596 case DW_CFA_offset_extended_sf:
597 insn_ptr = safe_read_uleb128 (insn_ptr, insn_end, ®);
598 reg = dwarf2_frame_adjust_regnum (gdbarch, reg, eh_frame_p);
599 insn_ptr = safe_read_sleb128 (insn_ptr, insn_end, &offset);
600 offset *= fs->data_align;
601 dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1);
602 fs->regs.reg[reg].how = DWARF2_FRAME_REG_SAVED_OFFSET;
603 fs->regs.reg[reg].loc.offset = offset;
606 case DW_CFA_val_offset:
607 insn_ptr = safe_read_uleb128 (insn_ptr, insn_end, ®);
608 dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1);
609 insn_ptr = safe_read_uleb128 (insn_ptr, insn_end, &utmp);
610 offset = utmp * fs->data_align;
611 fs->regs.reg[reg].how = DWARF2_FRAME_REG_SAVED_VAL_OFFSET;
612 fs->regs.reg[reg].loc.offset = offset;
615 case DW_CFA_val_offset_sf:
616 insn_ptr = safe_read_uleb128 (insn_ptr, insn_end, ®);
617 dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1);
618 insn_ptr = safe_read_sleb128 (insn_ptr, insn_end, &offset);
619 offset *= fs->data_align;
620 fs->regs.reg[reg].how = DWARF2_FRAME_REG_SAVED_VAL_OFFSET;
621 fs->regs.reg[reg].loc.offset = offset;
624 case DW_CFA_val_expression:
625 insn_ptr = safe_read_uleb128 (insn_ptr, insn_end, ®);
626 dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1);
627 insn_ptr = safe_read_uleb128 (insn_ptr, insn_end, &utmp);
628 fs->regs.reg[reg].loc.exp = insn_ptr;
629 fs->regs.reg[reg].exp_len = utmp;
630 fs->regs.reg[reg].how = DWARF2_FRAME_REG_SAVED_VAL_EXP;
634 case DW_CFA_def_cfa_sf:
635 insn_ptr = safe_read_uleb128 (insn_ptr, insn_end, ®);
636 fs->regs.cfa_reg = dwarf2_frame_adjust_regnum (gdbarch, reg,
638 insn_ptr = safe_read_sleb128 (insn_ptr, insn_end, &offset);
639 fs->regs.cfa_offset = offset * fs->data_align;
640 fs->regs.cfa_how = CFA_REG_OFFSET;
643 case DW_CFA_def_cfa_offset_sf:
644 insn_ptr = safe_read_sleb128 (insn_ptr, insn_end, &offset);
645 fs->regs.cfa_offset = offset * fs->data_align;
646 /* cfa_how deliberately not set. */
649 case DW_CFA_GNU_window_save:
650 /* This is SPARC-specific code, and contains hard-coded
651 constants for the register numbering scheme used by
652 GCC. Rather than having a architecture-specific
653 operation that's only ever used by a single
654 architecture, we provide the implementation here.
655 Incidentally that's what GCC does too in its
658 int size = register_size (gdbarch, 0);
660 dwarf2_frame_state_alloc_regs (&fs->regs, 32);
661 for (reg = 8; reg < 16; reg++)
663 fs->regs.reg[reg].how = DWARF2_FRAME_REG_SAVED_REG;
664 fs->regs.reg[reg].loc.reg = reg + 16;
666 for (reg = 16; reg < 32; reg++)
668 fs->regs.reg[reg].how = DWARF2_FRAME_REG_SAVED_OFFSET;
669 fs->regs.reg[reg].loc.offset = (reg - 16) * size;
674 case DW_CFA_GNU_args_size:
676 insn_ptr = safe_read_uleb128 (insn_ptr, insn_end, &utmp);
679 case DW_CFA_GNU_negative_offset_extended:
680 insn_ptr = safe_read_uleb128 (insn_ptr, insn_end, ®);
681 reg = dwarf2_frame_adjust_regnum (gdbarch, reg, eh_frame_p);
682 insn_ptr = safe_read_uleb128 (insn_ptr, insn_end, &utmp);
683 offset = utmp * fs->data_align;
684 dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1);
685 fs->regs.reg[reg].how = DWARF2_FRAME_REG_SAVED_OFFSET;
686 fs->regs.reg[reg].loc.offset = -offset;
690 internal_error (__FILE__, __LINE__,
691 _("Unknown CFI encountered."));
696 if (fs->initial.reg == NULL)
698 /* Don't allow remember/restore between CIE and FDE programs. */
699 dwarf2_frame_state_free_regs (fs->regs.prev);
700 fs->regs.prev = NULL;
707 /* Architecture-specific operations. */
709 /* Per-architecture data key. */
710 static struct gdbarch_data *dwarf2_frame_data;
712 struct dwarf2_frame_ops
714 /* Pre-initialize the register state REG for register REGNUM. */
715 void (*init_reg) (struct gdbarch *, int, struct dwarf2_frame_state_reg *,
716 struct frame_info *);
718 /* Check whether the THIS_FRAME is a signal trampoline. */
719 int (*signal_frame_p) (struct gdbarch *, struct frame_info *);
721 /* Convert .eh_frame register number to DWARF register number, or
722 adjust .debug_frame register number. */
723 int (*adjust_regnum) (struct gdbarch *, int, int);
726 /* Default architecture-specific register state initialization
730 dwarf2_frame_default_init_reg (struct gdbarch *gdbarch, int regnum,
731 struct dwarf2_frame_state_reg *reg,
732 struct frame_info *this_frame)
734 /* If we have a register that acts as a program counter, mark it as
735 a destination for the return address. If we have a register that
736 serves as the stack pointer, arrange for it to be filled with the
737 call frame address (CFA). The other registers are marked as
740 We copy the return address to the program counter, since many
741 parts in GDB assume that it is possible to get the return address
742 by unwinding the program counter register. However, on ISA's
743 with a dedicated return address register, the CFI usually only
744 contains information to unwind that return address register.
746 The reason we're treating the stack pointer special here is
747 because in many cases GCC doesn't emit CFI for the stack pointer
748 and implicitly assumes that it is equal to the CFA. This makes
749 some sense since the DWARF specification (version 3, draft 8,
752 "Typically, the CFA is defined to be the value of the stack
753 pointer at the call site in the previous frame (which may be
754 different from its value on entry to the current frame)."
756 However, this isn't true for all platforms supported by GCC
757 (e.g. IBM S/390 and zSeries). Those architectures should provide
758 their own architecture-specific initialization function. */
760 if (regnum == gdbarch_pc_regnum (gdbarch))
761 reg->how = DWARF2_FRAME_REG_RA;
762 else if (regnum == gdbarch_sp_regnum (gdbarch))
763 reg->how = DWARF2_FRAME_REG_CFA;
766 /* Return a default for the architecture-specific operations. */
769 dwarf2_frame_init (struct obstack *obstack)
771 struct dwarf2_frame_ops *ops;
773 ops = OBSTACK_ZALLOC (obstack, struct dwarf2_frame_ops);
774 ops->init_reg = dwarf2_frame_default_init_reg;
778 /* Set the architecture-specific register state initialization
779 function for GDBARCH to INIT_REG. */
782 dwarf2_frame_set_init_reg (struct gdbarch *gdbarch,
783 void (*init_reg) (struct gdbarch *, int,
784 struct dwarf2_frame_state_reg *,
785 struct frame_info *))
787 struct dwarf2_frame_ops *ops
788 = (struct dwarf2_frame_ops *) gdbarch_data (gdbarch, dwarf2_frame_data);
790 ops->init_reg = init_reg;
793 /* Pre-initialize the register state REG for register REGNUM. */
796 dwarf2_frame_init_reg (struct gdbarch *gdbarch, int regnum,
797 struct dwarf2_frame_state_reg *reg,
798 struct frame_info *this_frame)
800 struct dwarf2_frame_ops *ops
801 = (struct dwarf2_frame_ops *) gdbarch_data (gdbarch, dwarf2_frame_data);
803 ops->init_reg (gdbarch, regnum, reg, this_frame);
806 /* Set the architecture-specific signal trampoline recognition
807 function for GDBARCH to SIGNAL_FRAME_P. */
810 dwarf2_frame_set_signal_frame_p (struct gdbarch *gdbarch,
811 int (*signal_frame_p) (struct gdbarch *,
812 struct frame_info *))
814 struct dwarf2_frame_ops *ops
815 = (struct dwarf2_frame_ops *) gdbarch_data (gdbarch, dwarf2_frame_data);
817 ops->signal_frame_p = signal_frame_p;
820 /* Query the architecture-specific signal frame recognizer for
824 dwarf2_frame_signal_frame_p (struct gdbarch *gdbarch,
825 struct frame_info *this_frame)
827 struct dwarf2_frame_ops *ops
828 = (struct dwarf2_frame_ops *) gdbarch_data (gdbarch, dwarf2_frame_data);
830 if (ops->signal_frame_p == NULL)
832 return ops->signal_frame_p (gdbarch, this_frame);
835 /* Set the architecture-specific adjustment of .eh_frame and .debug_frame
839 dwarf2_frame_set_adjust_regnum (struct gdbarch *gdbarch,
840 int (*adjust_regnum) (struct gdbarch *,
843 struct dwarf2_frame_ops *ops
844 = (struct dwarf2_frame_ops *) gdbarch_data (gdbarch, dwarf2_frame_data);
846 ops->adjust_regnum = adjust_regnum;
849 /* Translate a .eh_frame register to DWARF register, or adjust a .debug_frame
853 dwarf2_frame_adjust_regnum (struct gdbarch *gdbarch,
854 int regnum, int eh_frame_p)
856 struct dwarf2_frame_ops *ops
857 = (struct dwarf2_frame_ops *) gdbarch_data (gdbarch, dwarf2_frame_data);
859 if (ops->adjust_regnum == NULL)
861 return ops->adjust_regnum (gdbarch, regnum, eh_frame_p);
865 dwarf2_frame_find_quirks (struct dwarf2_frame_state *fs,
866 struct dwarf2_fde *fde)
868 struct compunit_symtab *cust;
870 cust = find_pc_compunit_symtab (fs->pc);
874 if (producer_is_realview (COMPUNIT_PRODUCER (cust)))
876 if (fde->cie->version == 1)
877 fs->armcc_cfa_offsets_sf = 1;
879 if (fde->cie->version == 1)
880 fs->armcc_cfa_offsets_reversed = 1;
882 /* The reversed offset problem is present in some compilers
883 using DWARF3, but it was eventually fixed. Check the ARM
884 defined augmentations, which are in the format "armcc" followed
885 by a list of one-character options. The "+" option means
886 this problem is fixed (no quirk needed). If the armcc
887 augmentation is missing, the quirk is needed. */
888 if (fde->cie->version == 3
889 && (!startswith (fde->cie->augmentation, "armcc")
890 || strchr (fde->cie->augmentation + 5, '+') == NULL))
891 fs->armcc_cfa_offsets_reversed = 1;
898 /* See dwarf2-frame.h. */
901 dwarf2_fetch_cfa_info (struct gdbarch *gdbarch, CORE_ADDR pc,
902 struct dwarf2_per_cu_data *data,
903 int *regnum_out, LONGEST *offset_out,
904 CORE_ADDR *text_offset_out,
905 const gdb_byte **cfa_start_out,
906 const gdb_byte **cfa_end_out)
908 struct dwarf2_fde *fde;
909 CORE_ADDR text_offset;
910 struct dwarf2_frame_state fs;
912 memset (&fs, 0, sizeof (struct dwarf2_frame_state));
916 /* Find the correct FDE. */
917 fde = dwarf2_frame_find_fde (&fs.pc, &text_offset);
919 error (_("Could not compute CFA; needed to translate this expression"));
921 /* Extract any interesting information from the CIE. */
922 fs.data_align = fde->cie->data_alignment_factor;
923 fs.code_align = fde->cie->code_alignment_factor;
924 fs.retaddr_column = fde->cie->return_address_register;
926 /* Check for "quirks" - known bugs in producers. */
927 dwarf2_frame_find_quirks (&fs, fde);
929 /* First decode all the insns in the CIE. */
930 execute_cfa_program (fde, fde->cie->initial_instructions,
931 fde->cie->end, gdbarch, pc, &fs);
933 /* Save the initialized register set. */
934 fs.initial = fs.regs;
935 fs.initial.reg = dwarf2_frame_state_copy_regs (&fs.regs);
937 /* Then decode the insns in the FDE up to our target PC. */
938 execute_cfa_program (fde, fde->instructions, fde->end, gdbarch, pc, &fs);
940 /* Calculate the CFA. */
941 switch (fs.regs.cfa_how)
945 int regnum = dwarf_reg_to_regnum_or_error (gdbarch, fs.regs.cfa_reg);
947 *regnum_out = regnum;
948 if (fs.armcc_cfa_offsets_reversed)
949 *offset_out = -fs.regs.cfa_offset;
951 *offset_out = fs.regs.cfa_offset;
956 *text_offset_out = text_offset;
957 *cfa_start_out = fs.regs.cfa_exp;
958 *cfa_end_out = fs.regs.cfa_exp + fs.regs.cfa_exp_len;
962 internal_error (__FILE__, __LINE__, _("Unknown CFA rule."));
967 struct dwarf2_frame_cache
969 /* DWARF Call Frame Address. */
972 /* Set if the return address column was marked as unavailable
973 (required non-collected memory or registers to compute). */
974 int unavailable_retaddr;
976 /* Set if the return address column was marked as undefined. */
977 int undefined_retaddr;
979 /* Saved registers, indexed by GDB register number, not by DWARF
981 struct dwarf2_frame_state_reg *reg;
983 /* Return address register. */
984 struct dwarf2_frame_state_reg retaddr_reg;
986 /* Target address size in bytes. */
989 /* The .text offset. */
990 CORE_ADDR text_offset;
992 /* True if we already checked whether this frame is the bottom frame
993 of a virtual tail call frame chain. */
994 int checked_tailcall_bottom;
996 /* If not NULL then this frame is the bottom frame of a TAILCALL_FRAME
997 sequence. If NULL then it is a normal case with no TAILCALL_FRAME
998 involved. Non-bottom frames of a virtual tail call frames chain use
999 dwarf2_tailcall_frame_unwind unwinder so this field does not apply for
1001 void *tailcall_cache;
1003 /* The number of bytes to subtract from TAILCALL_FRAME frames frame
1004 base to get the SP, to simulate the return address pushed on the
1006 LONGEST entry_cfa_sp_offset;
1007 int entry_cfa_sp_offset_p;
1010 /* A cleanup that sets a pointer to NULL. */
1013 clear_pointer_cleanup (void *arg)
1015 void **ptr = (void **) arg;
1020 static struct dwarf2_frame_cache *
1021 dwarf2_frame_cache (struct frame_info *this_frame, void **this_cache)
1023 struct cleanup *reset_cache_cleanup, *old_chain;
1024 struct gdbarch *gdbarch = get_frame_arch (this_frame);
1025 const int num_regs = gdbarch_num_regs (gdbarch)
1026 + gdbarch_num_pseudo_regs (gdbarch);
1027 struct dwarf2_frame_cache *cache;
1028 struct dwarf2_frame_state *fs;
1029 struct dwarf2_fde *fde;
1031 const gdb_byte *instr;
1034 return (struct dwarf2_frame_cache *) *this_cache;
1036 /* Allocate a new cache. */
1037 cache = FRAME_OBSTACK_ZALLOC (struct dwarf2_frame_cache);
1038 cache->reg = FRAME_OBSTACK_CALLOC (num_regs, struct dwarf2_frame_state_reg);
1039 *this_cache = cache;
1040 reset_cache_cleanup = make_cleanup (clear_pointer_cleanup, this_cache);
1042 /* Allocate and initialize the frame state. */
1043 fs = XCNEW (struct dwarf2_frame_state);
1044 old_chain = make_cleanup (dwarf2_frame_state_free, fs);
1048 Note that if the next frame is never supposed to return (i.e. a call
1049 to abort), the compiler might optimize away the instruction at
1050 its return address. As a result the return address will
1051 point at some random instruction, and the CFI for that
1052 instruction is probably worthless to us. GCC's unwinder solves
1053 this problem by substracting 1 from the return address to get an
1054 address in the middle of a presumed call instruction (or the
1055 instruction in the associated delay slot). This should only be
1056 done for "normal" frames and not for resume-type frames (signal
1057 handlers, sentinel frames, dummy frames). The function
1058 get_frame_address_in_block does just this. It's not clear how
1059 reliable the method is though; there is the potential for the
1060 register state pre-call being different to that on return. */
1061 fs->pc = get_frame_address_in_block (this_frame);
1063 /* Find the correct FDE. */
1064 fde = dwarf2_frame_find_fde (&fs->pc, &cache->text_offset);
1065 gdb_assert (fde != NULL);
1067 /* Extract any interesting information from the CIE. */
1068 fs->data_align = fde->cie->data_alignment_factor;
1069 fs->code_align = fde->cie->code_alignment_factor;
1070 fs->retaddr_column = fde->cie->return_address_register;
1071 cache->addr_size = fde->cie->addr_size;
1073 /* Check for "quirks" - known bugs in producers. */
1074 dwarf2_frame_find_quirks (fs, fde);
1076 /* First decode all the insns in the CIE. */
1077 execute_cfa_program (fde, fde->cie->initial_instructions,
1078 fde->cie->end, gdbarch,
1079 get_frame_address_in_block (this_frame), fs);
1081 /* Save the initialized register set. */
1082 fs->initial = fs->regs;
1083 fs->initial.reg = dwarf2_frame_state_copy_regs (&fs->regs);
1085 if (get_frame_func_if_available (this_frame, &entry_pc))
1087 /* Decode the insns in the FDE up to the entry PC. */
1088 instr = execute_cfa_program (fde, fde->instructions, fde->end, gdbarch,
1091 if (fs->regs.cfa_how == CFA_REG_OFFSET
1092 && (dwarf_reg_to_regnum (gdbarch, fs->regs.cfa_reg)
1093 == gdbarch_sp_regnum (gdbarch)))
1095 cache->entry_cfa_sp_offset = fs->regs.cfa_offset;
1096 cache->entry_cfa_sp_offset_p = 1;
1100 instr = fde->instructions;
1102 /* Then decode the insns in the FDE up to our target PC. */
1103 execute_cfa_program (fde, instr, fde->end, gdbarch,
1104 get_frame_address_in_block (this_frame), fs);
1108 /* Calculate the CFA. */
1109 switch (fs->regs.cfa_how)
1111 case CFA_REG_OFFSET:
1112 cache->cfa = read_addr_from_reg (this_frame, fs->regs.cfa_reg);
1113 if (fs->armcc_cfa_offsets_reversed)
1114 cache->cfa -= fs->regs.cfa_offset;
1116 cache->cfa += fs->regs.cfa_offset;
1121 execute_stack_op (fs->regs.cfa_exp, fs->regs.cfa_exp_len,
1122 cache->addr_size, cache->text_offset,
1127 internal_error (__FILE__, __LINE__, _("Unknown CFA rule."));
1130 CATCH (ex, RETURN_MASK_ERROR)
1132 if (ex.error == NOT_AVAILABLE_ERROR)
1134 cache->unavailable_retaddr = 1;
1135 do_cleanups (old_chain);
1136 discard_cleanups (reset_cache_cleanup);
1140 throw_exception (ex);
1144 /* Initialize the register state. */
1148 for (regnum = 0; regnum < num_regs; regnum++)
1149 dwarf2_frame_init_reg (gdbarch, regnum, &cache->reg[regnum], this_frame);
1152 /* Go through the DWARF2 CFI generated table and save its register
1153 location information in the cache. Note that we don't skip the
1154 return address column; it's perfectly all right for it to
1155 correspond to a real register. */
1157 int column; /* CFI speak for "register number". */
1159 for (column = 0; column < fs->regs.num_regs; column++)
1161 /* Use the GDB register number as the destination index. */
1162 int regnum = dwarf_reg_to_regnum (gdbarch, column);
1164 /* Protect against a target returning a bad register. */
1165 if (regnum < 0 || regnum >= num_regs)
1168 /* NOTE: cagney/2003-09-05: CFI should specify the disposition
1169 of all debug info registers. If it doesn't, complain (but
1170 not too loudly). It turns out that GCC assumes that an
1171 unspecified register implies "same value" when CFI (draft
1172 7) specifies nothing at all. Such a register could equally
1173 be interpreted as "undefined". Also note that this check
1174 isn't sufficient; it only checks that all registers in the
1175 range [0 .. max column] are specified, and won't detect
1176 problems when a debug info register falls outside of the
1177 table. We need a way of iterating through all the valid
1178 DWARF2 register numbers. */
1179 if (fs->regs.reg[column].how == DWARF2_FRAME_REG_UNSPECIFIED)
1181 if (cache->reg[regnum].how == DWARF2_FRAME_REG_UNSPECIFIED)
1182 complaint (&symfile_complaints, _("\
1183 incomplete CFI data; unspecified registers (e.g., %s) at %s"),
1184 gdbarch_register_name (gdbarch, regnum),
1185 paddress (gdbarch, fs->pc));
1188 cache->reg[regnum] = fs->regs.reg[column];
1192 /* Eliminate any DWARF2_FRAME_REG_RA rules, and save the information
1193 we need for evaluating DWARF2_FRAME_REG_RA_OFFSET rules. */
1197 for (regnum = 0; regnum < num_regs; regnum++)
1199 if (cache->reg[regnum].how == DWARF2_FRAME_REG_RA
1200 || cache->reg[regnum].how == DWARF2_FRAME_REG_RA_OFFSET)
1202 struct dwarf2_frame_state_reg *retaddr_reg =
1203 &fs->regs.reg[fs->retaddr_column];
1205 /* It seems rather bizarre to specify an "empty" column as
1206 the return adress column. However, this is exactly
1207 what GCC does on some targets. It turns out that GCC
1208 assumes that the return address can be found in the
1209 register corresponding to the return address column.
1210 Incidentally, that's how we should treat a return
1211 address column specifying "same value" too. */
1212 if (fs->retaddr_column < fs->regs.num_regs
1213 && retaddr_reg->how != DWARF2_FRAME_REG_UNSPECIFIED
1214 && retaddr_reg->how != DWARF2_FRAME_REG_SAME_VALUE)
1216 if (cache->reg[regnum].how == DWARF2_FRAME_REG_RA)
1217 cache->reg[regnum] = *retaddr_reg;
1219 cache->retaddr_reg = *retaddr_reg;
1223 if (cache->reg[regnum].how == DWARF2_FRAME_REG_RA)
1225 cache->reg[regnum].loc.reg = fs->retaddr_column;
1226 cache->reg[regnum].how = DWARF2_FRAME_REG_SAVED_REG;
1230 cache->retaddr_reg.loc.reg = fs->retaddr_column;
1231 cache->retaddr_reg.how = DWARF2_FRAME_REG_SAVED_REG;
1238 if (fs->retaddr_column < fs->regs.num_regs
1239 && fs->regs.reg[fs->retaddr_column].how == DWARF2_FRAME_REG_UNDEFINED)
1240 cache->undefined_retaddr = 1;
1242 do_cleanups (old_chain);
1243 discard_cleanups (reset_cache_cleanup);
1247 static enum unwind_stop_reason
1248 dwarf2_frame_unwind_stop_reason (struct frame_info *this_frame,
1251 struct dwarf2_frame_cache *cache
1252 = dwarf2_frame_cache (this_frame, this_cache);
1254 if (cache->unavailable_retaddr)
1255 return UNWIND_UNAVAILABLE;
1257 if (cache->undefined_retaddr)
1258 return UNWIND_OUTERMOST;
1260 return UNWIND_NO_REASON;
1264 dwarf2_frame_this_id (struct frame_info *this_frame, void **this_cache,
1265 struct frame_id *this_id)
1267 struct dwarf2_frame_cache *cache =
1268 dwarf2_frame_cache (this_frame, this_cache);
1270 if (cache->unavailable_retaddr)
1271 (*this_id) = frame_id_build_unavailable_stack (get_frame_func (this_frame));
1272 else if (cache->undefined_retaddr)
1275 (*this_id) = frame_id_build (cache->cfa, get_frame_func (this_frame));
1278 static struct value *
1279 dwarf2_frame_prev_register (struct frame_info *this_frame, void **this_cache,
1282 struct gdbarch *gdbarch = get_frame_arch (this_frame);
1283 struct dwarf2_frame_cache *cache =
1284 dwarf2_frame_cache (this_frame, this_cache);
1288 /* Check whether THIS_FRAME is the bottom frame of a virtual tail
1289 call frame chain. */
1290 if (!cache->checked_tailcall_bottom)
1292 cache->checked_tailcall_bottom = 1;
1293 dwarf2_tailcall_sniffer_first (this_frame, &cache->tailcall_cache,
1294 (cache->entry_cfa_sp_offset_p
1295 ? &cache->entry_cfa_sp_offset : NULL));
1298 /* Non-bottom frames of a virtual tail call frames chain use
1299 dwarf2_tailcall_frame_unwind unwinder so this code does not apply for
1300 them. If dwarf2_tailcall_prev_register_first does not have specific value
1301 unwind the register, tail call frames are assumed to have the register set
1302 of the top caller. */
1303 if (cache->tailcall_cache)
1307 val = dwarf2_tailcall_prev_register_first (this_frame,
1308 &cache->tailcall_cache,
1314 switch (cache->reg[regnum].how)
1316 case DWARF2_FRAME_REG_UNDEFINED:
1317 /* If CFI explicitly specified that the value isn't defined,
1318 mark it as optimized away; the value isn't available. */
1319 return frame_unwind_got_optimized (this_frame, regnum);
1321 case DWARF2_FRAME_REG_SAVED_OFFSET:
1322 addr = cache->cfa + cache->reg[regnum].loc.offset;
1323 return frame_unwind_got_memory (this_frame, regnum, addr);
1325 case DWARF2_FRAME_REG_SAVED_REG:
1326 realnum = dwarf_reg_to_regnum_or_error
1327 (gdbarch, cache->reg[regnum].loc.reg);
1328 return frame_unwind_got_register (this_frame, regnum, realnum);
1330 case DWARF2_FRAME_REG_SAVED_EXP:
1331 addr = execute_stack_op (cache->reg[regnum].loc.exp,
1332 cache->reg[regnum].exp_len,
1333 cache->addr_size, cache->text_offset,
1334 this_frame, cache->cfa, 1);
1335 return frame_unwind_got_memory (this_frame, regnum, addr);
1337 case DWARF2_FRAME_REG_SAVED_VAL_OFFSET:
1338 addr = cache->cfa + cache->reg[regnum].loc.offset;
1339 return frame_unwind_got_constant (this_frame, regnum, addr);
1341 case DWARF2_FRAME_REG_SAVED_VAL_EXP:
1342 addr = execute_stack_op (cache->reg[regnum].loc.exp,
1343 cache->reg[regnum].exp_len,
1344 cache->addr_size, cache->text_offset,
1345 this_frame, cache->cfa, 1);
1346 return frame_unwind_got_constant (this_frame, regnum, addr);
1348 case DWARF2_FRAME_REG_UNSPECIFIED:
1349 /* GCC, in its infinite wisdom decided to not provide unwind
1350 information for registers that are "same value". Since
1351 DWARF2 (3 draft 7) doesn't define such behavior, said
1352 registers are actually undefined (which is different to CFI
1353 "undefined"). Code above issues a complaint about this.
1354 Here just fudge the books, assume GCC, and that the value is
1355 more inner on the stack. */
1356 return frame_unwind_got_register (this_frame, regnum, regnum);
1358 case DWARF2_FRAME_REG_SAME_VALUE:
1359 return frame_unwind_got_register (this_frame, regnum, regnum);
1361 case DWARF2_FRAME_REG_CFA:
1362 return frame_unwind_got_address (this_frame, regnum, cache->cfa);
1364 case DWARF2_FRAME_REG_CFA_OFFSET:
1365 addr = cache->cfa + cache->reg[regnum].loc.offset;
1366 return frame_unwind_got_address (this_frame, regnum, addr);
1368 case DWARF2_FRAME_REG_RA_OFFSET:
1369 addr = cache->reg[regnum].loc.offset;
1370 regnum = dwarf_reg_to_regnum_or_error
1371 (gdbarch, cache->retaddr_reg.loc.reg);
1372 addr += get_frame_register_unsigned (this_frame, regnum);
1373 return frame_unwind_got_address (this_frame, regnum, addr);
1375 case DWARF2_FRAME_REG_FN:
1376 return cache->reg[regnum].loc.fn (this_frame, this_cache, regnum);
1379 internal_error (__FILE__, __LINE__, _("Unknown register rule."));
1383 /* Proxy for tailcall_frame_dealloc_cache for bottom frame of a virtual tail
1384 call frames chain. */
1387 dwarf2_frame_dealloc_cache (struct frame_info *self, void *this_cache)
1389 struct dwarf2_frame_cache *cache = dwarf2_frame_cache (self, &this_cache);
1391 if (cache->tailcall_cache)
1392 dwarf2_tailcall_frame_unwind.dealloc_cache (self, cache->tailcall_cache);
1396 dwarf2_frame_sniffer (const struct frame_unwind *self,
1397 struct frame_info *this_frame, void **this_cache)
1399 /* Grab an address that is guarenteed to reside somewhere within the
1400 function. get_frame_pc(), with a no-return next function, can
1401 end up returning something past the end of this function's body.
1402 If the frame we're sniffing for is a signal frame whose start
1403 address is placed on the stack by the OS, its FDE must
1404 extend one byte before its start address or we could potentially
1405 select the FDE of the previous function. */
1406 CORE_ADDR block_addr = get_frame_address_in_block (this_frame);
1407 struct dwarf2_fde *fde = dwarf2_frame_find_fde (&block_addr, NULL);
1412 /* On some targets, signal trampolines may have unwind information.
1413 We need to recognize them so that we set the frame type
1416 if (fde->cie->signal_frame
1417 || dwarf2_frame_signal_frame_p (get_frame_arch (this_frame),
1419 return self->type == SIGTRAMP_FRAME;
1421 if (self->type != NORMAL_FRAME)
1427 static const struct frame_unwind dwarf2_frame_unwind =
1430 dwarf2_frame_unwind_stop_reason,
1431 dwarf2_frame_this_id,
1432 dwarf2_frame_prev_register,
1434 dwarf2_frame_sniffer,
1435 dwarf2_frame_dealloc_cache
1438 static const struct frame_unwind dwarf2_signal_frame_unwind =
1441 dwarf2_frame_unwind_stop_reason,
1442 dwarf2_frame_this_id,
1443 dwarf2_frame_prev_register,
1445 dwarf2_frame_sniffer,
1447 /* TAILCALL_CACHE can never be in such frame to need dealloc_cache. */
1451 /* Append the DWARF-2 frame unwinders to GDBARCH's list. */
1454 dwarf2_append_unwinders (struct gdbarch *gdbarch)
1456 /* TAILCALL_FRAME must be first to find the record by
1457 dwarf2_tailcall_sniffer_first. */
1458 frame_unwind_append_unwinder (gdbarch, &dwarf2_tailcall_frame_unwind);
1460 frame_unwind_append_unwinder (gdbarch, &dwarf2_frame_unwind);
1461 frame_unwind_append_unwinder (gdbarch, &dwarf2_signal_frame_unwind);
1465 /* There is no explicitly defined relationship between the CFA and the
1466 location of frame's local variables and arguments/parameters.
1467 Therefore, frame base methods on this page should probably only be
1468 used as a last resort, just to avoid printing total garbage as a
1469 response to the "info frame" command. */
1472 dwarf2_frame_base_address (struct frame_info *this_frame, void **this_cache)
1474 struct dwarf2_frame_cache *cache =
1475 dwarf2_frame_cache (this_frame, this_cache);
1480 static const struct frame_base dwarf2_frame_base =
1482 &dwarf2_frame_unwind,
1483 dwarf2_frame_base_address,
1484 dwarf2_frame_base_address,
1485 dwarf2_frame_base_address
1488 const struct frame_base *
1489 dwarf2_frame_base_sniffer (struct frame_info *this_frame)
1491 CORE_ADDR block_addr = get_frame_address_in_block (this_frame);
1493 if (dwarf2_frame_find_fde (&block_addr, NULL))
1494 return &dwarf2_frame_base;
1499 /* Compute the CFA for THIS_FRAME, but only if THIS_FRAME came from
1500 the DWARF unwinder. This is used to implement
1501 DW_OP_call_frame_cfa. */
1504 dwarf2_frame_cfa (struct frame_info *this_frame)
1506 if (frame_unwinder_is (this_frame, &record_btrace_tailcall_frame_unwind)
1507 || frame_unwinder_is (this_frame, &record_btrace_frame_unwind))
1508 throw_error (NOT_AVAILABLE_ERROR,
1509 _("cfa not available for record btrace target"));
1511 while (get_frame_type (this_frame) == INLINE_FRAME)
1512 this_frame = get_prev_frame (this_frame);
1513 if (get_frame_unwind_stop_reason (this_frame) == UNWIND_UNAVAILABLE)
1514 throw_error (NOT_AVAILABLE_ERROR,
1515 _("can't compute CFA for this frame: "
1516 "required registers or memory are unavailable"));
1518 if (get_frame_id (this_frame).stack_status != FID_STACK_VALID)
1519 throw_error (NOT_AVAILABLE_ERROR,
1520 _("can't compute CFA for this frame: "
1521 "frame base not available"));
1523 return get_frame_base (this_frame);
1526 const struct objfile_data *dwarf2_frame_objfile_data;
1529 read_1_byte (bfd *abfd, const gdb_byte *buf)
1531 return bfd_get_8 (abfd, buf);
1535 read_4_bytes (bfd *abfd, const gdb_byte *buf)
1537 return bfd_get_32 (abfd, buf);
1541 read_8_bytes (bfd *abfd, const gdb_byte *buf)
1543 return bfd_get_64 (abfd, buf);
1547 read_initial_length (bfd *abfd, const gdb_byte *buf,
1548 unsigned int *bytes_read_ptr)
1552 result = bfd_get_32 (abfd, buf);
1553 if (result == 0xffffffff)
1555 result = bfd_get_64 (abfd, buf + 4);
1556 *bytes_read_ptr = 12;
1559 *bytes_read_ptr = 4;
1565 /* Pointer encoding helper functions. */
1567 /* GCC supports exception handling based on DWARF2 CFI. However, for
1568 technical reasons, it encodes addresses in its FDE's in a different
1569 way. Several "pointer encodings" are supported. The encoding
1570 that's used for a particular FDE is determined by the 'R'
1571 augmentation in the associated CIE. The argument of this
1572 augmentation is a single byte.
1574 The address can be encoded as 2 bytes, 4 bytes, 8 bytes, or as a
1575 LEB128. This is encoded in bits 0, 1 and 2. Bit 3 encodes whether
1576 the address is signed or unsigned. Bits 4, 5 and 6 encode how the
1577 address should be interpreted (absolute, relative to the current
1578 position in the FDE, ...). Bit 7, indicates that the address
1579 should be dereferenced. */
1582 encoding_for_size (unsigned int size)
1587 return DW_EH_PE_udata2;
1589 return DW_EH_PE_udata4;
1591 return DW_EH_PE_udata8;
1593 internal_error (__FILE__, __LINE__, _("Unsupported address size"));
1598 read_encoded_value (struct comp_unit *unit, gdb_byte encoding,
1599 int ptr_len, const gdb_byte *buf,
1600 unsigned int *bytes_read_ptr,
1601 CORE_ADDR func_base)
1606 /* GCC currently doesn't generate DW_EH_PE_indirect encodings for
1608 if (encoding & DW_EH_PE_indirect)
1609 internal_error (__FILE__, __LINE__,
1610 _("Unsupported encoding: DW_EH_PE_indirect"));
1612 *bytes_read_ptr = 0;
1614 switch (encoding & 0x70)
1616 case DW_EH_PE_absptr:
1619 case DW_EH_PE_pcrel:
1620 base = bfd_get_section_vma (unit->abfd, unit->dwarf_frame_section);
1621 base += (buf - unit->dwarf_frame_buffer);
1623 case DW_EH_PE_datarel:
1626 case DW_EH_PE_textrel:
1629 case DW_EH_PE_funcrel:
1632 case DW_EH_PE_aligned:
1634 offset = buf - unit->dwarf_frame_buffer;
1635 if ((offset % ptr_len) != 0)
1637 *bytes_read_ptr = ptr_len - (offset % ptr_len);
1638 buf += *bytes_read_ptr;
1642 internal_error (__FILE__, __LINE__,
1643 _("Invalid or unsupported encoding"));
1646 if ((encoding & 0x07) == 0x00)
1648 encoding |= encoding_for_size (ptr_len);
1649 if (bfd_get_sign_extend_vma (unit->abfd))
1650 encoding |= DW_EH_PE_signed;
1653 switch (encoding & 0x0f)
1655 case DW_EH_PE_uleb128:
1658 const gdb_byte *end_buf = buf + (sizeof (value) + 1) * 8 / 7;
1660 *bytes_read_ptr += safe_read_uleb128 (buf, end_buf, &value) - buf;
1661 return base + value;
1663 case DW_EH_PE_udata2:
1664 *bytes_read_ptr += 2;
1665 return (base + bfd_get_16 (unit->abfd, (bfd_byte *) buf));
1666 case DW_EH_PE_udata4:
1667 *bytes_read_ptr += 4;
1668 return (base + bfd_get_32 (unit->abfd, (bfd_byte *) buf));
1669 case DW_EH_PE_udata8:
1670 *bytes_read_ptr += 8;
1671 return (base + bfd_get_64 (unit->abfd, (bfd_byte *) buf));
1672 case DW_EH_PE_sleb128:
1675 const gdb_byte *end_buf = buf + (sizeof (value) + 1) * 8 / 7;
1677 *bytes_read_ptr += safe_read_sleb128 (buf, end_buf, &value) - buf;
1678 return base + value;
1680 case DW_EH_PE_sdata2:
1681 *bytes_read_ptr += 2;
1682 return (base + bfd_get_signed_16 (unit->abfd, (bfd_byte *) buf));
1683 case DW_EH_PE_sdata4:
1684 *bytes_read_ptr += 4;
1685 return (base + bfd_get_signed_32 (unit->abfd, (bfd_byte *) buf));
1686 case DW_EH_PE_sdata8:
1687 *bytes_read_ptr += 8;
1688 return (base + bfd_get_signed_64 (unit->abfd, (bfd_byte *) buf));
1690 internal_error (__FILE__, __LINE__,
1691 _("Invalid or unsupported encoding"));
1697 bsearch_cie_cmp (const void *key, const void *element)
1699 ULONGEST cie_pointer = *(ULONGEST *) key;
1700 struct dwarf2_cie *cie = *(struct dwarf2_cie **) element;
1702 if (cie_pointer == cie->cie_pointer)
1705 return (cie_pointer < cie->cie_pointer) ? -1 : 1;
1708 /* Find CIE with the given CIE_POINTER in CIE_TABLE. */
1709 static struct dwarf2_cie *
1710 find_cie (struct dwarf2_cie_table *cie_table, ULONGEST cie_pointer)
1712 struct dwarf2_cie **p_cie;
1714 /* The C standard (ISO/IEC 9899:TC2) requires the BASE argument to
1715 bsearch be non-NULL. */
1716 if (cie_table->entries == NULL)
1718 gdb_assert (cie_table->num_entries == 0);
1722 p_cie = ((struct dwarf2_cie **)
1723 bsearch (&cie_pointer, cie_table->entries, cie_table->num_entries,
1724 sizeof (cie_table->entries[0]), bsearch_cie_cmp));
1730 /* Add a pointer to new CIE to the CIE_TABLE, allocating space for it. */
1732 add_cie (struct dwarf2_cie_table *cie_table, struct dwarf2_cie *cie)
1734 const int n = cie_table->num_entries;
1737 || cie_table->entries[n - 1]->cie_pointer < cie->cie_pointer);
1740 = XRESIZEVEC (struct dwarf2_cie *, cie_table->entries, n + 1);
1741 cie_table->entries[n] = cie;
1742 cie_table->num_entries = n + 1;
1746 bsearch_fde_cmp (const void *key, const void *element)
1748 CORE_ADDR seek_pc = *(CORE_ADDR *) key;
1749 struct dwarf2_fde *fde = *(struct dwarf2_fde **) element;
1751 if (seek_pc < fde->initial_location)
1753 if (seek_pc < fde->initial_location + fde->address_range)
1758 /* Find the FDE for *PC. Return a pointer to the FDE, and store the
1759 inital location associated with it into *PC. */
1761 static struct dwarf2_fde *
1762 dwarf2_frame_find_fde (CORE_ADDR *pc, CORE_ADDR *out_offset)
1764 struct objfile *objfile;
1766 ALL_OBJFILES (objfile)
1768 struct dwarf2_fde_table *fde_table;
1769 struct dwarf2_fde **p_fde;
1773 fde_table = ((struct dwarf2_fde_table *)
1774 objfile_data (objfile, dwarf2_frame_objfile_data));
1775 if (fde_table == NULL)
1777 dwarf2_build_frame_info (objfile);
1778 fde_table = ((struct dwarf2_fde_table *)
1779 objfile_data (objfile, dwarf2_frame_objfile_data));
1781 gdb_assert (fde_table != NULL);
1783 if (fde_table->num_entries == 0)
1786 gdb_assert (objfile->section_offsets);
1787 offset = ANOFFSET (objfile->section_offsets, SECT_OFF_TEXT (objfile));
1789 gdb_assert (fde_table->num_entries > 0);
1790 if (*pc < offset + fde_table->entries[0]->initial_location)
1793 seek_pc = *pc - offset;
1794 p_fde = ((struct dwarf2_fde **)
1795 bsearch (&seek_pc, fde_table->entries, fde_table->num_entries,
1796 sizeof (fde_table->entries[0]), bsearch_fde_cmp));
1799 *pc = (*p_fde)->initial_location + offset;
1801 *out_offset = offset;
1808 /* Add a pointer to new FDE to the FDE_TABLE, allocating space for it. */
1810 add_fde (struct dwarf2_fde_table *fde_table, struct dwarf2_fde *fde)
1812 if (fde->address_range == 0)
1813 /* Discard useless FDEs. */
1816 fde_table->num_entries += 1;
1817 fde_table->entries = XRESIZEVEC (struct dwarf2_fde *, fde_table->entries,
1818 fde_table->num_entries);
1819 fde_table->entries[fde_table->num_entries - 1] = fde;
1822 #define DW64_CIE_ID 0xffffffffffffffffULL
1824 /* Defines the type of eh_frames that are expected to be decoded: CIE, FDE
1829 EH_CIE_TYPE_ID = 1 << 0,
1830 EH_FDE_TYPE_ID = 1 << 1,
1831 EH_CIE_OR_FDE_TYPE_ID = EH_CIE_TYPE_ID | EH_FDE_TYPE_ID
1834 static const gdb_byte *decode_frame_entry (struct comp_unit *unit,
1835 const gdb_byte *start,
1837 struct dwarf2_cie_table *cie_table,
1838 struct dwarf2_fde_table *fde_table,
1839 enum eh_frame_type entry_type);
1841 /* Decode the next CIE or FDE, entry_type specifies the expected type.
1842 Return NULL if invalid input, otherwise the next byte to be processed. */
1844 static const gdb_byte *
1845 decode_frame_entry_1 (struct comp_unit *unit, const gdb_byte *start,
1847 struct dwarf2_cie_table *cie_table,
1848 struct dwarf2_fde_table *fde_table,
1849 enum eh_frame_type entry_type)
1851 struct gdbarch *gdbarch = get_objfile_arch (unit->objfile);
1852 const gdb_byte *buf, *end;
1854 unsigned int bytes_read;
1857 ULONGEST cie_pointer;
1862 length = read_initial_length (unit->abfd, buf, &bytes_read);
1866 /* Are we still within the section? */
1867 if (end > unit->dwarf_frame_buffer + unit->dwarf_frame_size)
1873 /* Distinguish between 32 and 64-bit encoded frame info. */
1874 dwarf64_p = (bytes_read == 12);
1876 /* In a .eh_frame section, zero is used to distinguish CIEs from FDEs. */
1880 cie_id = DW64_CIE_ID;
1886 cie_pointer = read_8_bytes (unit->abfd, buf);
1891 cie_pointer = read_4_bytes (unit->abfd, buf);
1895 if (cie_pointer == cie_id)
1897 /* This is a CIE. */
1898 struct dwarf2_cie *cie;
1900 unsigned int cie_version;
1902 /* Check that a CIE was expected. */
1903 if ((entry_type & EH_CIE_TYPE_ID) == 0)
1904 error (_("Found a CIE when not expecting it."));
1906 /* Record the offset into the .debug_frame section of this CIE. */
1907 cie_pointer = start - unit->dwarf_frame_buffer;
1909 /* Check whether we've already read it. */
1910 if (find_cie (cie_table, cie_pointer))
1913 cie = XOBNEW (&unit->objfile->objfile_obstack, struct dwarf2_cie);
1914 cie->initial_instructions = NULL;
1915 cie->cie_pointer = cie_pointer;
1917 /* The encoding for FDE's in a normal .debug_frame section
1918 depends on the target address size. */
1919 cie->encoding = DW_EH_PE_absptr;
1921 /* We'll determine the final value later, but we need to
1922 initialize it conservatively. */
1923 cie->signal_frame = 0;
1925 /* Check version number. */
1926 cie_version = read_1_byte (unit->abfd, buf);
1927 if (cie_version != 1 && cie_version != 3 && cie_version != 4)
1929 cie->version = cie_version;
1932 /* Interpret the interesting bits of the augmentation. */
1933 cie->augmentation = augmentation = (char *) buf;
1934 buf += (strlen (augmentation) + 1);
1936 /* Ignore armcc augmentations. We only use them for quirks,
1937 and that doesn't happen until later. */
1938 if (startswith (augmentation, "armcc"))
1939 augmentation += strlen (augmentation);
1941 /* The GCC 2.x "eh" augmentation has a pointer immediately
1942 following the augmentation string, so it must be handled
1944 if (augmentation[0] == 'e' && augmentation[1] == 'h')
1947 buf += gdbarch_ptr_bit (gdbarch) / TARGET_CHAR_BIT;
1951 if (cie->version >= 4)
1953 /* FIXME: check that this is the same as from the CU header. */
1954 cie->addr_size = read_1_byte (unit->abfd, buf);
1956 cie->segment_size = read_1_byte (unit->abfd, buf);
1961 cie->addr_size = gdbarch_dwarf2_addr_size (gdbarch);
1962 cie->segment_size = 0;
1964 /* Address values in .eh_frame sections are defined to have the
1965 target's pointer size. Watchout: This breaks frame info for
1966 targets with pointer size < address size, unless a .debug_frame
1967 section exists as well. */
1969 cie->ptr_size = gdbarch_ptr_bit (gdbarch) / TARGET_CHAR_BIT;
1971 cie->ptr_size = cie->addr_size;
1973 buf = gdb_read_uleb128 (buf, end, &uleb128);
1976 cie->code_alignment_factor = uleb128;
1978 buf = gdb_read_sleb128 (buf, end, &sleb128);
1981 cie->data_alignment_factor = sleb128;
1983 if (cie_version == 1)
1985 cie->return_address_register = read_1_byte (unit->abfd, buf);
1990 buf = gdb_read_uleb128 (buf, end, &uleb128);
1993 cie->return_address_register = uleb128;
1996 cie->return_address_register
1997 = dwarf2_frame_adjust_regnum (gdbarch,
1998 cie->return_address_register,
2001 cie->saw_z_augmentation = (*augmentation == 'z');
2002 if (cie->saw_z_augmentation)
2006 buf = gdb_read_uleb128 (buf, end, &length);
2009 cie->initial_instructions = buf + length;
2013 while (*augmentation)
2015 /* "L" indicates a byte showing how the LSDA pointer is encoded. */
2016 if (*augmentation == 'L')
2023 /* "R" indicates a byte indicating how FDE addresses are encoded. */
2024 else if (*augmentation == 'R')
2026 cie->encoding = *buf++;
2030 /* "P" indicates a personality routine in the CIE augmentation. */
2031 else if (*augmentation == 'P')
2033 /* Skip. Avoid indirection since we throw away the result. */
2034 gdb_byte encoding = (*buf++) & ~DW_EH_PE_indirect;
2035 read_encoded_value (unit, encoding, cie->ptr_size,
2036 buf, &bytes_read, 0);
2041 /* "S" indicates a signal frame, such that the return
2042 address must not be decremented to locate the call frame
2043 info for the previous frame; it might even be the first
2044 instruction of a function, so decrementing it would take
2045 us to a different function. */
2046 else if (*augmentation == 'S')
2048 cie->signal_frame = 1;
2052 /* Otherwise we have an unknown augmentation. Assume that either
2053 there is no augmentation data, or we saw a 'z' prefix. */
2056 if (cie->initial_instructions)
2057 buf = cie->initial_instructions;
2062 cie->initial_instructions = buf;
2066 add_cie (cie_table, cie);
2070 /* This is a FDE. */
2071 struct dwarf2_fde *fde;
2074 /* Check that an FDE was expected. */
2075 if ((entry_type & EH_FDE_TYPE_ID) == 0)
2076 error (_("Found an FDE when not expecting it."));
2078 /* In an .eh_frame section, the CIE pointer is the delta between the
2079 address within the FDE where the CIE pointer is stored and the
2080 address of the CIE. Convert it to an offset into the .eh_frame
2084 cie_pointer = buf - unit->dwarf_frame_buffer - cie_pointer;
2085 cie_pointer -= (dwarf64_p ? 8 : 4);
2088 /* In either case, validate the result is still within the section. */
2089 if (cie_pointer >= unit->dwarf_frame_size)
2092 fde = XOBNEW (&unit->objfile->objfile_obstack, struct dwarf2_fde);
2093 fde->cie = find_cie (cie_table, cie_pointer);
2094 if (fde->cie == NULL)
2096 decode_frame_entry (unit, unit->dwarf_frame_buffer + cie_pointer,
2097 eh_frame_p, cie_table, fde_table,
2099 fde->cie = find_cie (cie_table, cie_pointer);
2102 gdb_assert (fde->cie != NULL);
2104 addr = read_encoded_value (unit, fde->cie->encoding, fde->cie->ptr_size,
2105 buf, &bytes_read, 0);
2106 fde->initial_location = gdbarch_adjust_dwarf2_addr (gdbarch, addr);
2109 fde->address_range =
2110 read_encoded_value (unit, fde->cie->encoding & 0x0f,
2111 fde->cie->ptr_size, buf, &bytes_read, 0);
2112 addr = gdbarch_adjust_dwarf2_addr (gdbarch, addr + fde->address_range);
2113 fde->address_range = addr - fde->initial_location;
2116 /* A 'z' augmentation in the CIE implies the presence of an
2117 augmentation field in the FDE as well. The only thing known
2118 to be in here at present is the LSDA entry for EH. So we
2119 can skip the whole thing. */
2120 if (fde->cie->saw_z_augmentation)
2124 buf = gdb_read_uleb128 (buf, end, &length);
2132 fde->instructions = buf;
2135 fde->eh_frame_p = eh_frame_p;
2137 add_fde (fde_table, fde);
2143 /* Read a CIE or FDE in BUF and decode it. Entry_type specifies whether we
2144 expect an FDE or a CIE. */
2146 static const gdb_byte *
2147 decode_frame_entry (struct comp_unit *unit, const gdb_byte *start,
2149 struct dwarf2_cie_table *cie_table,
2150 struct dwarf2_fde_table *fde_table,
2151 enum eh_frame_type entry_type)
2153 enum { NONE, ALIGN4, ALIGN8, FAIL } workaround = NONE;
2154 const gdb_byte *ret;
2155 ptrdiff_t start_offset;
2159 ret = decode_frame_entry_1 (unit, start, eh_frame_p,
2160 cie_table, fde_table, entry_type);
2164 /* We have corrupt input data of some form. */
2166 /* ??? Try, weakly, to work around compiler/assembler/linker bugs
2167 and mismatches wrt padding and alignment of debug sections. */
2168 /* Note that there is no requirement in the standard for any
2169 alignment at all in the frame unwind sections. Testing for
2170 alignment before trying to interpret data would be incorrect.
2172 However, GCC traditionally arranged for frame sections to be
2173 sized such that the FDE length and CIE fields happen to be
2174 aligned (in theory, for performance). This, unfortunately,
2175 was done with .align directives, which had the side effect of
2176 forcing the section to be aligned by the linker.
2178 This becomes a problem when you have some other producer that
2179 creates frame sections that are not as strictly aligned. That
2180 produces a hole in the frame info that gets filled by the
2183 The GCC behaviour is arguably a bug, but it's effectively now
2184 part of the ABI, so we're now stuck with it, at least at the
2185 object file level. A smart linker may decide, in the process
2186 of compressing duplicate CIE information, that it can rewrite
2187 the entire output section without this extra padding. */
2189 start_offset = start - unit->dwarf_frame_buffer;
2190 if (workaround < ALIGN4 && (start_offset & 3) != 0)
2192 start += 4 - (start_offset & 3);
2193 workaround = ALIGN4;
2196 if (workaround < ALIGN8 && (start_offset & 7) != 0)
2198 start += 8 - (start_offset & 7);
2199 workaround = ALIGN8;
2203 /* Nothing left to try. Arrange to return as if we've consumed
2204 the entire input section. Hopefully we'll get valid info from
2205 the other of .debug_frame/.eh_frame. */
2207 ret = unit->dwarf_frame_buffer + unit->dwarf_frame_size;
2217 complaint (&symfile_complaints, _("\
2218 Corrupt data in %s:%s; align 4 workaround apparently succeeded"),
2219 unit->dwarf_frame_section->owner->filename,
2220 unit->dwarf_frame_section->name);
2224 complaint (&symfile_complaints, _("\
2225 Corrupt data in %s:%s; align 8 workaround apparently succeeded"),
2226 unit->dwarf_frame_section->owner->filename,
2227 unit->dwarf_frame_section->name);
2231 complaint (&symfile_complaints,
2232 _("Corrupt data in %s:%s"),
2233 unit->dwarf_frame_section->owner->filename,
2234 unit->dwarf_frame_section->name);
2242 qsort_fde_cmp (const void *a, const void *b)
2244 struct dwarf2_fde *aa = *(struct dwarf2_fde **)a;
2245 struct dwarf2_fde *bb = *(struct dwarf2_fde **)b;
2247 if (aa->initial_location == bb->initial_location)
2249 if (aa->address_range != bb->address_range
2250 && aa->eh_frame_p == 0 && bb->eh_frame_p == 0)
2251 /* Linker bug, e.g. gold/10400.
2252 Work around it by keeping stable sort order. */
2253 return (a < b) ? -1 : 1;
2255 /* Put eh_frame entries after debug_frame ones. */
2256 return aa->eh_frame_p - bb->eh_frame_p;
2259 return (aa->initial_location < bb->initial_location) ? -1 : 1;
2263 dwarf2_build_frame_info (struct objfile *objfile)
2265 struct comp_unit *unit;
2266 const gdb_byte *frame_ptr;
2267 struct dwarf2_cie_table cie_table;
2268 struct dwarf2_fde_table fde_table;
2269 struct dwarf2_fde_table *fde_table2;
2271 cie_table.num_entries = 0;
2272 cie_table.entries = NULL;
2274 fde_table.num_entries = 0;
2275 fde_table.entries = NULL;
2277 /* Build a minimal decoding of the DWARF2 compilation unit. */
2278 unit = (struct comp_unit *) obstack_alloc (&objfile->objfile_obstack,
2279 sizeof (struct comp_unit));
2280 unit->abfd = objfile->obfd;
2281 unit->objfile = objfile;
2285 if (objfile->separate_debug_objfile_backlink == NULL)
2287 /* Do not read .eh_frame from separate file as they must be also
2288 present in the main file. */
2289 dwarf2_get_section_info (objfile, DWARF2_EH_FRAME,
2290 &unit->dwarf_frame_section,
2291 &unit->dwarf_frame_buffer,
2292 &unit->dwarf_frame_size);
2293 if (unit->dwarf_frame_size)
2295 asection *got, *txt;
2297 /* FIXME: kettenis/20030602: This is the DW_EH_PE_datarel base
2298 that is used for the i386/amd64 target, which currently is
2299 the only target in GCC that supports/uses the
2300 DW_EH_PE_datarel encoding. */
2301 got = bfd_get_section_by_name (unit->abfd, ".got");
2303 unit->dbase = got->vma;
2305 /* GCC emits the DW_EH_PE_textrel encoding type on sh and ia64
2307 txt = bfd_get_section_by_name (unit->abfd, ".text");
2309 unit->tbase = txt->vma;
2313 frame_ptr = unit->dwarf_frame_buffer;
2314 while (frame_ptr < unit->dwarf_frame_buffer + unit->dwarf_frame_size)
2315 frame_ptr = decode_frame_entry (unit, frame_ptr, 1,
2316 &cie_table, &fde_table,
2317 EH_CIE_OR_FDE_TYPE_ID);
2320 CATCH (e, RETURN_MASK_ERROR)
2322 warning (_("skipping .eh_frame info of %s: %s"),
2323 objfile_name (objfile), e.message);
2325 if (fde_table.num_entries != 0)
2327 xfree (fde_table.entries);
2328 fde_table.entries = NULL;
2329 fde_table.num_entries = 0;
2331 /* The cie_table is discarded by the next if. */
2335 if (cie_table.num_entries != 0)
2337 /* Reinit cie_table: debug_frame has different CIEs. */
2338 xfree (cie_table.entries);
2339 cie_table.num_entries = 0;
2340 cie_table.entries = NULL;
2345 dwarf2_get_section_info (objfile, DWARF2_DEBUG_FRAME,
2346 &unit->dwarf_frame_section,
2347 &unit->dwarf_frame_buffer,
2348 &unit->dwarf_frame_size);
2349 if (unit->dwarf_frame_size)
2351 int num_old_fde_entries = fde_table.num_entries;
2355 frame_ptr = unit->dwarf_frame_buffer;
2356 while (frame_ptr < unit->dwarf_frame_buffer + unit->dwarf_frame_size)
2357 frame_ptr = decode_frame_entry (unit, frame_ptr, 0,
2358 &cie_table, &fde_table,
2359 EH_CIE_OR_FDE_TYPE_ID);
2361 CATCH (e, RETURN_MASK_ERROR)
2363 warning (_("skipping .debug_frame info of %s: %s"),
2364 objfile_name (objfile), e.message);
2366 if (fde_table.num_entries != 0)
2368 fde_table.num_entries = num_old_fde_entries;
2369 if (num_old_fde_entries == 0)
2371 xfree (fde_table.entries);
2372 fde_table.entries = NULL;
2377 = XRESIZEVEC (struct dwarf2_fde *, fde_table.entries,
2378 fde_table.num_entries);
2381 fde_table.num_entries = num_old_fde_entries;
2382 /* The cie_table is discarded by the next if. */
2387 /* Discard the cie_table, it is no longer needed. */
2388 if (cie_table.num_entries != 0)
2390 xfree (cie_table.entries);
2391 cie_table.entries = NULL; /* Paranoia. */
2392 cie_table.num_entries = 0; /* Paranoia. */
2395 /* Copy fde_table to obstack: it is needed at runtime. */
2396 fde_table2 = XOBNEW (&objfile->objfile_obstack, struct dwarf2_fde_table);
2398 if (fde_table.num_entries == 0)
2400 fde_table2->entries = NULL;
2401 fde_table2->num_entries = 0;
2405 struct dwarf2_fde *fde_prev = NULL;
2406 struct dwarf2_fde *first_non_zero_fde = NULL;
2409 /* Prepare FDE table for lookups. */
2410 qsort (fde_table.entries, fde_table.num_entries,
2411 sizeof (fde_table.entries[0]), qsort_fde_cmp);
2413 /* Check for leftovers from --gc-sections. The GNU linker sets
2414 the relevant symbols to zero, but doesn't zero the FDE *end*
2415 ranges because there's no relocation there. It's (offset,
2416 length), not (start, end). On targets where address zero is
2417 just another valid address this can be a problem, since the
2418 FDEs appear to be non-empty in the output --- we could pick
2419 out the wrong FDE. To work around this, when overlaps are
2420 detected, we prefer FDEs that do not start at zero.
2422 Start by finding the first FDE with non-zero start. Below
2423 we'll discard all FDEs that start at zero and overlap this
2425 for (i = 0; i < fde_table.num_entries; i++)
2427 struct dwarf2_fde *fde = fde_table.entries[i];
2429 if (fde->initial_location != 0)
2431 first_non_zero_fde = fde;
2436 /* Since we'll be doing bsearch, squeeze out identical (except
2437 for eh_frame_p) fde entries so bsearch result is predictable.
2438 Also discard leftovers from --gc-sections. */
2439 fde_table2->num_entries = 0;
2440 for (i = 0; i < fde_table.num_entries; i++)
2442 struct dwarf2_fde *fde = fde_table.entries[i];
2444 if (fde->initial_location == 0
2445 && first_non_zero_fde != NULL
2446 && (first_non_zero_fde->initial_location
2447 < fde->initial_location + fde->address_range))
2450 if (fde_prev != NULL
2451 && fde_prev->initial_location == fde->initial_location)
2454 obstack_grow (&objfile->objfile_obstack, &fde_table.entries[i],
2455 sizeof (fde_table.entries[0]));
2456 ++fde_table2->num_entries;
2460 = (struct dwarf2_fde **) obstack_finish (&objfile->objfile_obstack);
2462 /* Discard the original fde_table. */
2463 xfree (fde_table.entries);
2466 set_objfile_data (objfile, dwarf2_frame_objfile_data, fde_table2);
2469 /* Provide a prototype to silence -Wmissing-prototypes. */
2470 void _initialize_dwarf2_frame (void);
2473 _initialize_dwarf2_frame (void)
2475 dwarf2_frame_data = gdbarch_data_register_pre_init (dwarf2_frame_init);
2476 dwarf2_frame_objfile_data = register_objfile_data ();