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/>. */
24 /* Local non-gdb includes. */
26 #include "complaints.h"
27 #include "dwarf2-frame-tailcall.h"
28 #include "dwarf2-frame.h"
30 #include "dwarf2expr.h"
31 #include "dwarf2loc.h"
32 #include "dwarf2read.h"
33 #include "frame-base.h"
34 #include "frame-unwind.h"
45 #include "common/selftest.h"
46 #include "selftest-arch.h"
51 /* Call Frame Information (CFI). */
53 /* Common Information Entry (CIE). */
57 /* Computation Unit for this CIE. */
58 struct comp_unit
*unit
;
60 /* Offset into the .debug_frame section where this CIE was found.
61 Used to identify this CIE. */
64 /* Constant that is factored out of all advance location
66 ULONGEST code_alignment_factor
;
68 /* Constants that is factored out of all offset instructions. */
69 LONGEST data_alignment_factor
;
71 /* Return address column. */
72 ULONGEST return_address_register
;
74 /* Instruction sequence to initialize a register set. */
75 const gdb_byte
*initial_instructions
;
78 /* Saved augmentation, in case it's needed later. */
81 /* Encoding of addresses. */
84 /* Target address size in bytes. */
87 /* Target pointer size in bytes. */
90 /* True if a 'z' augmentation existed. */
91 unsigned char saw_z_augmentation
;
93 /* True if an 'S' augmentation existed. */
94 unsigned char signal_frame
;
96 /* The version recorded in the CIE. */
97 unsigned char version
;
99 /* The segment size. */
100 unsigned char segment_size
;
103 struct dwarf2_cie_table
106 struct dwarf2_cie
**entries
;
109 /* Frame Description Entry (FDE). */
113 /* CIE for this FDE. */
114 struct dwarf2_cie
*cie
;
116 /* First location associated with this FDE. */
117 CORE_ADDR initial_location
;
119 /* Number of bytes of program instructions described by this FDE. */
120 CORE_ADDR address_range
;
122 /* Instruction sequence. */
123 const gdb_byte
*instructions
;
126 /* True if this FDE is read from a .eh_frame instead of a .debug_frame
128 unsigned char eh_frame_p
;
131 struct dwarf2_fde_table
134 struct dwarf2_fde
**entries
;
137 /* A minimal decoding of DWARF2 compilation units. We only decode
138 what's needed to get to the call frame information. */
142 /* Keep the bfd convenient. */
145 struct objfile
*objfile
;
147 /* Pointer to the .debug_frame section loaded into memory. */
148 const gdb_byte
*dwarf_frame_buffer
;
150 /* Length of the loaded .debug_frame section. */
151 bfd_size_type dwarf_frame_size
;
153 /* Pointer to the .debug_frame section. */
154 asection
*dwarf_frame_section
;
156 /* Base for DW_EH_PE_datarel encodings. */
159 /* Base for DW_EH_PE_textrel encodings. */
163 static struct dwarf2_fde
*dwarf2_frame_find_fde (CORE_ADDR
*pc
,
164 CORE_ADDR
*out_offset
);
166 static int dwarf2_frame_adjust_regnum (struct gdbarch
*gdbarch
, int regnum
,
169 static CORE_ADDR
read_encoded_value (struct comp_unit
*unit
, gdb_byte encoding
,
170 int ptr_len
, const gdb_byte
*buf
,
171 unsigned int *bytes_read_ptr
,
172 CORE_ADDR func_base
);
175 /* See dwarf2-frame.h. */
176 int dwarf2_frame_unwinders_enabled_p
= 1;
178 /* Store the length the expression for the CFA in the `cfa_reg' field,
179 which is unused in that case. */
180 #define cfa_exp_len cfa_reg
182 dwarf2_frame_state::dwarf2_frame_state (CORE_ADDR pc_
, struct dwarf2_cie
*cie
)
183 : pc (pc_
), data_align (cie
->data_alignment_factor
),
184 code_align (cie
->code_alignment_factor
),
185 retaddr_column (cie
->return_address_register
)
190 /* Helper functions for execute_stack_op. */
193 read_addr_from_reg (struct frame_info
*this_frame
, int reg
)
195 struct gdbarch
*gdbarch
= get_frame_arch (this_frame
);
196 int regnum
= dwarf_reg_to_regnum_or_error (gdbarch
, reg
);
198 return address_from_register (regnum
, this_frame
);
201 /* Execute the required actions for both the DW_CFA_restore and
202 DW_CFA_restore_extended instructions. */
204 dwarf2_restore_rule (struct gdbarch
*gdbarch
, ULONGEST reg_num
,
205 struct dwarf2_frame_state
*fs
, int eh_frame_p
)
209 reg
= dwarf2_frame_adjust_regnum (gdbarch
, reg_num
, eh_frame_p
);
210 fs
->regs
.alloc_regs (reg
+ 1);
212 /* Check if this register was explicitly initialized in the
213 CIE initial instructions. If not, default the rule to
215 if (reg
< fs
->initial
.reg
.size ())
216 fs
->regs
.reg
[reg
] = fs
->initial
.reg
[reg
];
218 fs
->regs
.reg
[reg
].how
= DWARF2_FRAME_REG_UNSPECIFIED
;
220 if (fs
->regs
.reg
[reg
].how
== DWARF2_FRAME_REG_UNSPECIFIED
)
222 int regnum
= dwarf_reg_to_regnum (gdbarch
, reg
);
225 incomplete CFI data; DW_CFA_restore unspecified\n\
226 register %s (#%d) at %s"),
227 gdbarch_register_name (gdbarch
, regnum
), regnum
,
228 paddress (gdbarch
, fs
->pc
));
232 class dwarf_expr_executor
: public dwarf_expr_context
236 struct frame_info
*this_frame
;
238 CORE_ADDR
read_addr_from_reg (int reg
) override
240 return ::read_addr_from_reg (this_frame
, reg
);
243 struct value
*get_reg_value (struct type
*type
, int reg
) override
245 struct gdbarch
*gdbarch
= get_frame_arch (this_frame
);
246 int regnum
= dwarf_reg_to_regnum_or_error (gdbarch
, reg
);
248 return value_from_register (type
, regnum
, this_frame
);
251 void read_mem (gdb_byte
*buf
, CORE_ADDR addr
, size_t len
) override
253 read_memory (addr
, buf
, len
);
256 void get_frame_base (const gdb_byte
**start
, size_t *length
) override
258 invalid ("DW_OP_fbreg");
261 void push_dwarf_reg_entry_value (enum call_site_parameter_kind kind
,
262 union call_site_parameter_u kind_u
,
263 int deref_size
) override
265 invalid ("DW_OP_entry_value");
268 CORE_ADDR
get_object_address () override
270 invalid ("DW_OP_push_object_address");
273 CORE_ADDR
get_frame_cfa () override
275 invalid ("DW_OP_call_frame_cfa");
278 CORE_ADDR
get_tls_address (CORE_ADDR offset
) override
280 invalid ("DW_OP_form_tls_address");
283 void dwarf_call (cu_offset die_offset
) override
285 invalid ("DW_OP_call*");
288 struct value
*dwarf_variable_value (sect_offset sect_off
) override
290 invalid ("DW_OP_GNU_variable_value");
293 CORE_ADDR
get_addr_index (unsigned int index
) override
295 invalid ("DW_OP_GNU_addr_index");
300 void invalid (const char *op
) ATTRIBUTE_NORETURN
302 error (_("%s is invalid in this context"), op
);
307 execute_stack_op (const gdb_byte
*exp
, ULONGEST len
, int addr_size
,
308 CORE_ADDR offset
, struct frame_info
*this_frame
,
309 CORE_ADDR initial
, int initial_in_stack_memory
)
313 dwarf_expr_executor ctx
;
314 scoped_value_mark free_values
;
316 ctx
.this_frame
= this_frame
;
317 ctx
.gdbarch
= get_frame_arch (this_frame
);
318 ctx
.addr_size
= addr_size
;
319 ctx
.ref_addr_size
= -1;
322 ctx
.push_address (initial
, initial_in_stack_memory
);
325 if (ctx
.location
== DWARF_VALUE_MEMORY
)
326 result
= ctx
.fetch_address (0);
327 else if (ctx
.location
== DWARF_VALUE_REGISTER
)
328 result
= ctx
.read_addr_from_reg (value_as_long (ctx
.fetch (0)));
331 /* This is actually invalid DWARF, but if we ever do run across
332 it somehow, we might as well support it. So, instead, report
333 it as unimplemented. */
335 Not implemented: computing unwound register using explicit value operator"));
342 /* Execute FDE program from INSN_PTR possibly up to INSN_END or up to inferior
343 PC. Modify FS state accordingly. Return current INSN_PTR where the
344 execution has stopped, one can resume it on the next call. */
346 static const gdb_byte
*
347 execute_cfa_program (struct dwarf2_fde
*fde
, const gdb_byte
*insn_ptr
,
348 const gdb_byte
*insn_end
, struct gdbarch
*gdbarch
,
349 CORE_ADDR pc
, struct dwarf2_frame_state
*fs
)
351 int eh_frame_p
= fde
->eh_frame_p
;
352 unsigned int bytes_read
;
353 enum bfd_endian byte_order
= gdbarch_byte_order (gdbarch
);
355 while (insn_ptr
< insn_end
&& fs
->pc
<= pc
)
357 gdb_byte insn
= *insn_ptr
++;
361 if ((insn
& 0xc0) == DW_CFA_advance_loc
)
362 fs
->pc
+= (insn
& 0x3f) * fs
->code_align
;
363 else if ((insn
& 0xc0) == DW_CFA_offset
)
366 reg
= dwarf2_frame_adjust_regnum (gdbarch
, reg
, eh_frame_p
);
367 insn_ptr
= safe_read_uleb128 (insn_ptr
, insn_end
, &utmp
);
368 offset
= utmp
* fs
->data_align
;
369 fs
->regs
.alloc_regs (reg
+ 1);
370 fs
->regs
.reg
[reg
].how
= DWARF2_FRAME_REG_SAVED_OFFSET
;
371 fs
->regs
.reg
[reg
].loc
.offset
= offset
;
373 else if ((insn
& 0xc0) == DW_CFA_restore
)
376 dwarf2_restore_rule (gdbarch
, reg
, fs
, eh_frame_p
);
383 fs
->pc
= read_encoded_value (fde
->cie
->unit
, fde
->cie
->encoding
,
384 fde
->cie
->ptr_size
, insn_ptr
,
385 &bytes_read
, fde
->initial_location
);
386 /* Apply the objfile offset for relocatable objects. */
387 fs
->pc
+= ANOFFSET (fde
->cie
->unit
->objfile
->section_offsets
,
388 SECT_OFF_TEXT (fde
->cie
->unit
->objfile
));
389 insn_ptr
+= bytes_read
;
392 case DW_CFA_advance_loc1
:
393 utmp
= extract_unsigned_integer (insn_ptr
, 1, byte_order
);
394 fs
->pc
+= utmp
* fs
->code_align
;
397 case DW_CFA_advance_loc2
:
398 utmp
= extract_unsigned_integer (insn_ptr
, 2, byte_order
);
399 fs
->pc
+= utmp
* fs
->code_align
;
402 case DW_CFA_advance_loc4
:
403 utmp
= extract_unsigned_integer (insn_ptr
, 4, byte_order
);
404 fs
->pc
+= utmp
* fs
->code_align
;
408 case DW_CFA_offset_extended
:
409 insn_ptr
= safe_read_uleb128 (insn_ptr
, insn_end
, ®
);
410 reg
= dwarf2_frame_adjust_regnum (gdbarch
, reg
, eh_frame_p
);
411 insn_ptr
= safe_read_uleb128 (insn_ptr
, insn_end
, &utmp
);
412 offset
= utmp
* fs
->data_align
;
413 fs
->regs
.alloc_regs (reg
+ 1);
414 fs
->regs
.reg
[reg
].how
= DWARF2_FRAME_REG_SAVED_OFFSET
;
415 fs
->regs
.reg
[reg
].loc
.offset
= offset
;
418 case DW_CFA_restore_extended
:
419 insn_ptr
= safe_read_uleb128 (insn_ptr
, insn_end
, ®
);
420 dwarf2_restore_rule (gdbarch
, reg
, fs
, eh_frame_p
);
423 case DW_CFA_undefined
:
424 insn_ptr
= safe_read_uleb128 (insn_ptr
, insn_end
, ®
);
425 reg
= dwarf2_frame_adjust_regnum (gdbarch
, reg
, eh_frame_p
);
426 fs
->regs
.alloc_regs (reg
+ 1);
427 fs
->regs
.reg
[reg
].how
= DWARF2_FRAME_REG_UNDEFINED
;
430 case DW_CFA_same_value
:
431 insn_ptr
= safe_read_uleb128 (insn_ptr
, insn_end
, ®
);
432 reg
= dwarf2_frame_adjust_regnum (gdbarch
, reg
, eh_frame_p
);
433 fs
->regs
.alloc_regs (reg
+ 1);
434 fs
->regs
.reg
[reg
].how
= DWARF2_FRAME_REG_SAME_VALUE
;
437 case DW_CFA_register
:
438 insn_ptr
= safe_read_uleb128 (insn_ptr
, insn_end
, ®
);
439 reg
= dwarf2_frame_adjust_regnum (gdbarch
, reg
, eh_frame_p
);
440 insn_ptr
= safe_read_uleb128 (insn_ptr
, insn_end
, &utmp
);
441 utmp
= dwarf2_frame_adjust_regnum (gdbarch
, utmp
, eh_frame_p
);
442 fs
->regs
.alloc_regs (reg
+ 1);
443 fs
->regs
.reg
[reg
].how
= DWARF2_FRAME_REG_SAVED_REG
;
444 fs
->regs
.reg
[reg
].loc
.reg
= utmp
;
447 case DW_CFA_remember_state
:
449 struct dwarf2_frame_state_reg_info
*new_rs
;
451 new_rs
= new dwarf2_frame_state_reg_info (fs
->regs
);
452 fs
->regs
.prev
= new_rs
;
456 case DW_CFA_restore_state
:
458 struct dwarf2_frame_state_reg_info
*old_rs
= fs
->regs
.prev
;
463 bad CFI data; mismatched DW_CFA_restore_state at %s"),
464 paddress (gdbarch
, fs
->pc
));
467 fs
->regs
= std::move (*old_rs
);
472 insn_ptr
= safe_read_uleb128 (insn_ptr
, insn_end
, ®
);
473 fs
->regs
.cfa_reg
= reg
;
474 insn_ptr
= safe_read_uleb128 (insn_ptr
, insn_end
, &utmp
);
476 if (fs
->armcc_cfa_offsets_sf
)
477 utmp
*= fs
->data_align
;
479 fs
->regs
.cfa_offset
= utmp
;
480 fs
->regs
.cfa_how
= CFA_REG_OFFSET
;
483 case DW_CFA_def_cfa_register
:
484 insn_ptr
= safe_read_uleb128 (insn_ptr
, insn_end
, ®
);
485 fs
->regs
.cfa_reg
= dwarf2_frame_adjust_regnum (gdbarch
, reg
,
487 fs
->regs
.cfa_how
= CFA_REG_OFFSET
;
490 case DW_CFA_def_cfa_offset
:
491 insn_ptr
= safe_read_uleb128 (insn_ptr
, insn_end
, &utmp
);
493 if (fs
->armcc_cfa_offsets_sf
)
494 utmp
*= fs
->data_align
;
496 fs
->regs
.cfa_offset
= utmp
;
497 /* cfa_how deliberately not set. */
503 case DW_CFA_def_cfa_expression
:
504 insn_ptr
= safe_read_uleb128 (insn_ptr
, insn_end
, &utmp
);
505 fs
->regs
.cfa_exp_len
= utmp
;
506 fs
->regs
.cfa_exp
= insn_ptr
;
507 fs
->regs
.cfa_how
= CFA_EXP
;
508 insn_ptr
+= fs
->regs
.cfa_exp_len
;
511 case DW_CFA_expression
:
512 insn_ptr
= safe_read_uleb128 (insn_ptr
, insn_end
, ®
);
513 reg
= dwarf2_frame_adjust_regnum (gdbarch
, reg
, eh_frame_p
);
514 fs
->regs
.alloc_regs (reg
+ 1);
515 insn_ptr
= safe_read_uleb128 (insn_ptr
, insn_end
, &utmp
);
516 fs
->regs
.reg
[reg
].loc
.exp
.start
= insn_ptr
;
517 fs
->regs
.reg
[reg
].loc
.exp
.len
= utmp
;
518 fs
->regs
.reg
[reg
].how
= DWARF2_FRAME_REG_SAVED_EXP
;
522 case DW_CFA_offset_extended_sf
:
523 insn_ptr
= safe_read_uleb128 (insn_ptr
, insn_end
, ®
);
524 reg
= dwarf2_frame_adjust_regnum (gdbarch
, reg
, eh_frame_p
);
525 insn_ptr
= safe_read_sleb128 (insn_ptr
, insn_end
, &offset
);
526 offset
*= fs
->data_align
;
527 fs
->regs
.alloc_regs (reg
+ 1);
528 fs
->regs
.reg
[reg
].how
= DWARF2_FRAME_REG_SAVED_OFFSET
;
529 fs
->regs
.reg
[reg
].loc
.offset
= offset
;
532 case DW_CFA_val_offset
:
533 insn_ptr
= safe_read_uleb128 (insn_ptr
, insn_end
, ®
);
534 fs
->regs
.alloc_regs (reg
+ 1);
535 insn_ptr
= safe_read_uleb128 (insn_ptr
, insn_end
, &utmp
);
536 offset
= utmp
* fs
->data_align
;
537 fs
->regs
.reg
[reg
].how
= DWARF2_FRAME_REG_SAVED_VAL_OFFSET
;
538 fs
->regs
.reg
[reg
].loc
.offset
= offset
;
541 case DW_CFA_val_offset_sf
:
542 insn_ptr
= safe_read_uleb128 (insn_ptr
, insn_end
, ®
);
543 fs
->regs
.alloc_regs (reg
+ 1);
544 insn_ptr
= safe_read_sleb128 (insn_ptr
, insn_end
, &offset
);
545 offset
*= fs
->data_align
;
546 fs
->regs
.reg
[reg
].how
= DWARF2_FRAME_REG_SAVED_VAL_OFFSET
;
547 fs
->regs
.reg
[reg
].loc
.offset
= offset
;
550 case DW_CFA_val_expression
:
551 insn_ptr
= safe_read_uleb128 (insn_ptr
, insn_end
, ®
);
552 fs
->regs
.alloc_regs (reg
+ 1);
553 insn_ptr
= safe_read_uleb128 (insn_ptr
, insn_end
, &utmp
);
554 fs
->regs
.reg
[reg
].loc
.exp
.start
= insn_ptr
;
555 fs
->regs
.reg
[reg
].loc
.exp
.len
= utmp
;
556 fs
->regs
.reg
[reg
].how
= DWARF2_FRAME_REG_SAVED_VAL_EXP
;
560 case DW_CFA_def_cfa_sf
:
561 insn_ptr
= safe_read_uleb128 (insn_ptr
, insn_end
, ®
);
562 fs
->regs
.cfa_reg
= dwarf2_frame_adjust_regnum (gdbarch
, reg
,
564 insn_ptr
= safe_read_sleb128 (insn_ptr
, insn_end
, &offset
);
565 fs
->regs
.cfa_offset
= offset
* fs
->data_align
;
566 fs
->regs
.cfa_how
= CFA_REG_OFFSET
;
569 case DW_CFA_def_cfa_offset_sf
:
570 insn_ptr
= safe_read_sleb128 (insn_ptr
, insn_end
, &offset
);
571 fs
->regs
.cfa_offset
= offset
* fs
->data_align
;
572 /* cfa_how deliberately not set. */
575 case DW_CFA_GNU_args_size
:
577 insn_ptr
= safe_read_uleb128 (insn_ptr
, insn_end
, &utmp
);
580 case DW_CFA_GNU_negative_offset_extended
:
581 insn_ptr
= safe_read_uleb128 (insn_ptr
, insn_end
, ®
);
582 reg
= dwarf2_frame_adjust_regnum (gdbarch
, reg
, eh_frame_p
);
583 insn_ptr
= safe_read_uleb128 (insn_ptr
, insn_end
, &utmp
);
584 offset
= utmp
* fs
->data_align
;
585 fs
->regs
.alloc_regs (reg
+ 1);
586 fs
->regs
.reg
[reg
].how
= DWARF2_FRAME_REG_SAVED_OFFSET
;
587 fs
->regs
.reg
[reg
].loc
.offset
= -offset
;
591 if (insn
>= DW_CFA_lo_user
&& insn
<= DW_CFA_hi_user
)
593 /* Handle vendor-specific CFI for different architectures. */
594 if (!gdbarch_execute_dwarf_cfa_vendor_op (gdbarch
, insn
, fs
))
595 error (_("Call Frame Instruction op %d in vendor extension "
596 "space is not handled on this architecture."),
600 internal_error (__FILE__
, __LINE__
,
601 _("Unknown CFI encountered."));
606 if (fs
->initial
.reg
.empty ())
608 /* Don't allow remember/restore between CIE and FDE programs. */
609 delete fs
->regs
.prev
;
610 fs
->regs
.prev
= NULL
;
618 namespace selftests
{
620 /* Unit test to function execute_cfa_program. */
623 execute_cfa_program_test (struct gdbarch
*gdbarch
)
625 struct dwarf2_fde fde
;
626 struct dwarf2_cie cie
;
628 memset (&fde
, 0, sizeof fde
);
629 memset (&cie
, 0, sizeof cie
);
631 cie
.data_alignment_factor
= -4;
632 cie
.code_alignment_factor
= 2;
635 dwarf2_frame_state
fs (0, fde
.cie
);
639 DW_CFA_def_cfa
, 1, 4, /* DW_CFA_def_cfa: r1 ofs 4 */
640 DW_CFA_offset
| 0x2, 1, /* DW_CFA_offset: r2 at cfa-4 */
641 DW_CFA_remember_state
,
642 DW_CFA_restore_state
,
645 const gdb_byte
*insn_end
= insns
+ sizeof (insns
);
646 const gdb_byte
*out
= execute_cfa_program (&fde
, insns
, insn_end
, gdbarch
,
649 SELF_CHECK (out
== insn_end
);
650 SELF_CHECK (fs
.pc
== 0);
652 /* The instructions above only use r1 and r2, but the register numbers
653 used are adjusted by dwarf2_frame_adjust_regnum. */
654 auto r1
= dwarf2_frame_adjust_regnum (gdbarch
, 1, fde
.eh_frame_p
);
655 auto r2
= dwarf2_frame_adjust_regnum (gdbarch
, 2, fde
.eh_frame_p
);
657 SELF_CHECK (fs
.regs
.reg
.size () == (std::max (r1
, r2
) + 1));
659 SELF_CHECK (fs
.regs
.reg
[r2
].how
== DWARF2_FRAME_REG_SAVED_OFFSET
);
660 SELF_CHECK (fs
.regs
.reg
[r2
].loc
.offset
== -4);
662 for (auto i
= 0; i
< fs
.regs
.reg
.size (); i
++)
664 SELF_CHECK (fs
.regs
.reg
[i
].how
== DWARF2_FRAME_REG_UNSPECIFIED
);
666 SELF_CHECK (fs
.regs
.cfa_reg
== 1);
667 SELF_CHECK (fs
.regs
.cfa_offset
== 4);
668 SELF_CHECK (fs
.regs
.cfa_how
== CFA_REG_OFFSET
);
669 SELF_CHECK (fs
.regs
.cfa_exp
== NULL
);
670 SELF_CHECK (fs
.regs
.prev
== NULL
);
673 } // namespace selftests
674 #endif /* GDB_SELF_TEST */
678 /* Architecture-specific operations. */
680 /* Per-architecture data key. */
681 static struct gdbarch_data
*dwarf2_frame_data
;
683 struct dwarf2_frame_ops
685 /* Pre-initialize the register state REG for register REGNUM. */
686 void (*init_reg
) (struct gdbarch
*, int, struct dwarf2_frame_state_reg
*,
687 struct frame_info
*);
689 /* Check whether the THIS_FRAME is a signal trampoline. */
690 int (*signal_frame_p
) (struct gdbarch
*, struct frame_info
*);
692 /* Convert .eh_frame register number to DWARF register number, or
693 adjust .debug_frame register number. */
694 int (*adjust_regnum
) (struct gdbarch
*, int, int);
697 /* Default architecture-specific register state initialization
701 dwarf2_frame_default_init_reg (struct gdbarch
*gdbarch
, int regnum
,
702 struct dwarf2_frame_state_reg
*reg
,
703 struct frame_info
*this_frame
)
705 /* If we have a register that acts as a program counter, mark it as
706 a destination for the return address. If we have a register that
707 serves as the stack pointer, arrange for it to be filled with the
708 call frame address (CFA). The other registers are marked as
711 We copy the return address to the program counter, since many
712 parts in GDB assume that it is possible to get the return address
713 by unwinding the program counter register. However, on ISA's
714 with a dedicated return address register, the CFI usually only
715 contains information to unwind that return address register.
717 The reason we're treating the stack pointer special here is
718 because in many cases GCC doesn't emit CFI for the stack pointer
719 and implicitly assumes that it is equal to the CFA. This makes
720 some sense since the DWARF specification (version 3, draft 8,
723 "Typically, the CFA is defined to be the value of the stack
724 pointer at the call site in the previous frame (which may be
725 different from its value on entry to the current frame)."
727 However, this isn't true for all platforms supported by GCC
728 (e.g. IBM S/390 and zSeries). Those architectures should provide
729 their own architecture-specific initialization function. */
731 if (regnum
== gdbarch_pc_regnum (gdbarch
))
732 reg
->how
= DWARF2_FRAME_REG_RA
;
733 else if (regnum
== gdbarch_sp_regnum (gdbarch
))
734 reg
->how
= DWARF2_FRAME_REG_CFA
;
737 /* Return a default for the architecture-specific operations. */
740 dwarf2_frame_init (struct obstack
*obstack
)
742 struct dwarf2_frame_ops
*ops
;
744 ops
= OBSTACK_ZALLOC (obstack
, struct dwarf2_frame_ops
);
745 ops
->init_reg
= dwarf2_frame_default_init_reg
;
749 /* Set the architecture-specific register state initialization
750 function for GDBARCH to INIT_REG. */
753 dwarf2_frame_set_init_reg (struct gdbarch
*gdbarch
,
754 void (*init_reg
) (struct gdbarch
*, int,
755 struct dwarf2_frame_state_reg
*,
756 struct frame_info
*))
758 struct dwarf2_frame_ops
*ops
759 = (struct dwarf2_frame_ops
*) gdbarch_data (gdbarch
, dwarf2_frame_data
);
761 ops
->init_reg
= init_reg
;
764 /* Pre-initialize the register state REG for register REGNUM. */
767 dwarf2_frame_init_reg (struct gdbarch
*gdbarch
, int regnum
,
768 struct dwarf2_frame_state_reg
*reg
,
769 struct frame_info
*this_frame
)
771 struct dwarf2_frame_ops
*ops
772 = (struct dwarf2_frame_ops
*) gdbarch_data (gdbarch
, dwarf2_frame_data
);
774 ops
->init_reg (gdbarch
, regnum
, reg
, this_frame
);
777 /* Set the architecture-specific signal trampoline recognition
778 function for GDBARCH to SIGNAL_FRAME_P. */
781 dwarf2_frame_set_signal_frame_p (struct gdbarch
*gdbarch
,
782 int (*signal_frame_p
) (struct gdbarch
*,
783 struct frame_info
*))
785 struct dwarf2_frame_ops
*ops
786 = (struct dwarf2_frame_ops
*) gdbarch_data (gdbarch
, dwarf2_frame_data
);
788 ops
->signal_frame_p
= signal_frame_p
;
791 /* Query the architecture-specific signal frame recognizer for
795 dwarf2_frame_signal_frame_p (struct gdbarch
*gdbarch
,
796 struct frame_info
*this_frame
)
798 struct dwarf2_frame_ops
*ops
799 = (struct dwarf2_frame_ops
*) gdbarch_data (gdbarch
, dwarf2_frame_data
);
801 if (ops
->signal_frame_p
== NULL
)
803 return ops
->signal_frame_p (gdbarch
, this_frame
);
806 /* Set the architecture-specific adjustment of .eh_frame and .debug_frame
810 dwarf2_frame_set_adjust_regnum (struct gdbarch
*gdbarch
,
811 int (*adjust_regnum
) (struct gdbarch
*,
814 struct dwarf2_frame_ops
*ops
815 = (struct dwarf2_frame_ops
*) gdbarch_data (gdbarch
, dwarf2_frame_data
);
817 ops
->adjust_regnum
= adjust_regnum
;
820 /* Translate a .eh_frame register to DWARF register, or adjust a .debug_frame
824 dwarf2_frame_adjust_regnum (struct gdbarch
*gdbarch
,
825 int regnum
, int eh_frame_p
)
827 struct dwarf2_frame_ops
*ops
828 = (struct dwarf2_frame_ops
*) gdbarch_data (gdbarch
, dwarf2_frame_data
);
830 if (ops
->adjust_regnum
== NULL
)
832 return ops
->adjust_regnum (gdbarch
, regnum
, eh_frame_p
);
836 dwarf2_frame_find_quirks (struct dwarf2_frame_state
*fs
,
837 struct dwarf2_fde
*fde
)
839 struct compunit_symtab
*cust
;
841 cust
= find_pc_compunit_symtab (fs
->pc
);
845 if (producer_is_realview (COMPUNIT_PRODUCER (cust
)))
847 if (fde
->cie
->version
== 1)
848 fs
->armcc_cfa_offsets_sf
= 1;
850 if (fde
->cie
->version
== 1)
851 fs
->armcc_cfa_offsets_reversed
= 1;
853 /* The reversed offset problem is present in some compilers
854 using DWARF3, but it was eventually fixed. Check the ARM
855 defined augmentations, which are in the format "armcc" followed
856 by a list of one-character options. The "+" option means
857 this problem is fixed (no quirk needed). If the armcc
858 augmentation is missing, the quirk is needed. */
859 if (fde
->cie
->version
== 3
860 && (!startswith (fde
->cie
->augmentation
, "armcc")
861 || strchr (fde
->cie
->augmentation
+ 5, '+') == NULL
))
862 fs
->armcc_cfa_offsets_reversed
= 1;
869 /* See dwarf2-frame.h. */
872 dwarf2_fetch_cfa_info (struct gdbarch
*gdbarch
, CORE_ADDR pc
,
873 struct dwarf2_per_cu_data
*data
,
874 int *regnum_out
, LONGEST
*offset_out
,
875 CORE_ADDR
*text_offset_out
,
876 const gdb_byte
**cfa_start_out
,
877 const gdb_byte
**cfa_end_out
)
879 struct dwarf2_fde
*fde
;
880 CORE_ADDR text_offset
;
883 /* Find the correct FDE. */
884 fde
= dwarf2_frame_find_fde (&pc1
, &text_offset
);
886 error (_("Could not compute CFA; needed to translate this expression"));
888 dwarf2_frame_state
fs (pc1
, fde
->cie
);
890 /* Check for "quirks" - known bugs in producers. */
891 dwarf2_frame_find_quirks (&fs
, fde
);
893 /* First decode all the insns in the CIE. */
894 execute_cfa_program (fde
, fde
->cie
->initial_instructions
,
895 fde
->cie
->end
, gdbarch
, pc
, &fs
);
897 /* Save the initialized register set. */
898 fs
.initial
= fs
.regs
;
900 /* Then decode the insns in the FDE up to our target PC. */
901 execute_cfa_program (fde
, fde
->instructions
, fde
->end
, gdbarch
, pc
, &fs
);
903 /* Calculate the CFA. */
904 switch (fs
.regs
.cfa_how
)
908 int regnum
= dwarf_reg_to_regnum_or_error (gdbarch
, fs
.regs
.cfa_reg
);
910 *regnum_out
= regnum
;
911 if (fs
.armcc_cfa_offsets_reversed
)
912 *offset_out
= -fs
.regs
.cfa_offset
;
914 *offset_out
= fs
.regs
.cfa_offset
;
919 *text_offset_out
= text_offset
;
920 *cfa_start_out
= fs
.regs
.cfa_exp
;
921 *cfa_end_out
= fs
.regs
.cfa_exp
+ fs
.regs
.cfa_exp_len
;
925 internal_error (__FILE__
, __LINE__
, _("Unknown CFA rule."));
930 struct dwarf2_frame_cache
932 /* DWARF Call Frame Address. */
935 /* Set if the return address column was marked as unavailable
936 (required non-collected memory or registers to compute). */
937 int unavailable_retaddr
;
939 /* Set if the return address column was marked as undefined. */
940 int undefined_retaddr
;
942 /* Saved registers, indexed by GDB register number, not by DWARF
944 struct dwarf2_frame_state_reg
*reg
;
946 /* Return address register. */
947 struct dwarf2_frame_state_reg retaddr_reg
;
949 /* Target address size in bytes. */
952 /* The .text offset. */
953 CORE_ADDR text_offset
;
955 /* True if we already checked whether this frame is the bottom frame
956 of a virtual tail call frame chain. */
957 int checked_tailcall_bottom
;
959 /* If not NULL then this frame is the bottom frame of a TAILCALL_FRAME
960 sequence. If NULL then it is a normal case with no TAILCALL_FRAME
961 involved. Non-bottom frames of a virtual tail call frames chain use
962 dwarf2_tailcall_frame_unwind unwinder so this field does not apply for
964 void *tailcall_cache
;
966 /* The number of bytes to subtract from TAILCALL_FRAME frames frame
967 base to get the SP, to simulate the return address pushed on the
969 LONGEST entry_cfa_sp_offset
;
970 int entry_cfa_sp_offset_p
;
973 static struct dwarf2_frame_cache
*
974 dwarf2_frame_cache (struct frame_info
*this_frame
, void **this_cache
)
976 struct gdbarch
*gdbarch
= get_frame_arch (this_frame
);
977 const int num_regs
= gdbarch_num_cooked_regs (gdbarch
);
978 struct dwarf2_frame_cache
*cache
;
979 struct dwarf2_fde
*fde
;
981 const gdb_byte
*instr
;
984 return (struct dwarf2_frame_cache
*) *this_cache
;
986 /* Allocate a new cache. */
987 cache
= FRAME_OBSTACK_ZALLOC (struct dwarf2_frame_cache
);
988 cache
->reg
= FRAME_OBSTACK_CALLOC (num_regs
, struct dwarf2_frame_state_reg
);
993 Note that if the next frame is never supposed to return (i.e. a call
994 to abort), the compiler might optimize away the instruction at
995 its return address. As a result the return address will
996 point at some random instruction, and the CFI for that
997 instruction is probably worthless to us. GCC's unwinder solves
998 this problem by substracting 1 from the return address to get an
999 address in the middle of a presumed call instruction (or the
1000 instruction in the associated delay slot). This should only be
1001 done for "normal" frames and not for resume-type frames (signal
1002 handlers, sentinel frames, dummy frames). The function
1003 get_frame_address_in_block does just this. It's not clear how
1004 reliable the method is though; there is the potential for the
1005 register state pre-call being different to that on return. */
1006 CORE_ADDR pc1
= get_frame_address_in_block (this_frame
);
1008 /* Find the correct FDE. */
1009 fde
= dwarf2_frame_find_fde (&pc1
, &cache
->text_offset
);
1010 gdb_assert (fde
!= NULL
);
1012 /* Allocate and initialize the frame state. */
1013 struct dwarf2_frame_state
fs (pc1
, fde
->cie
);
1015 cache
->addr_size
= fde
->cie
->addr_size
;
1017 /* Check for "quirks" - known bugs in producers. */
1018 dwarf2_frame_find_quirks (&fs
, fde
);
1020 /* First decode all the insns in the CIE. */
1021 execute_cfa_program (fde
, fde
->cie
->initial_instructions
,
1022 fde
->cie
->end
, gdbarch
,
1023 get_frame_address_in_block (this_frame
), &fs
);
1025 /* Save the initialized register set. */
1026 fs
.initial
= fs
.regs
;
1028 if (get_frame_func_if_available (this_frame
, &entry_pc
))
1030 /* Decode the insns in the FDE up to the entry PC. */
1031 instr
= execute_cfa_program (fde
, fde
->instructions
, fde
->end
, gdbarch
,
1034 if (fs
.regs
.cfa_how
== CFA_REG_OFFSET
1035 && (dwarf_reg_to_regnum (gdbarch
, fs
.regs
.cfa_reg
)
1036 == gdbarch_sp_regnum (gdbarch
)))
1038 cache
->entry_cfa_sp_offset
= fs
.regs
.cfa_offset
;
1039 cache
->entry_cfa_sp_offset_p
= 1;
1043 instr
= fde
->instructions
;
1045 /* Then decode the insns in the FDE up to our target PC. */
1046 execute_cfa_program (fde
, instr
, fde
->end
, gdbarch
,
1047 get_frame_address_in_block (this_frame
), &fs
);
1051 /* Calculate the CFA. */
1052 switch (fs
.regs
.cfa_how
)
1054 case CFA_REG_OFFSET
:
1055 cache
->cfa
= read_addr_from_reg (this_frame
, fs
.regs
.cfa_reg
);
1056 if (fs
.armcc_cfa_offsets_reversed
)
1057 cache
->cfa
-= fs
.regs
.cfa_offset
;
1059 cache
->cfa
+= fs
.regs
.cfa_offset
;
1064 execute_stack_op (fs
.regs
.cfa_exp
, fs
.regs
.cfa_exp_len
,
1065 cache
->addr_size
, cache
->text_offset
,
1070 internal_error (__FILE__
, __LINE__
, _("Unknown CFA rule."));
1073 CATCH (ex
, RETURN_MASK_ERROR
)
1075 if (ex
.error
== NOT_AVAILABLE_ERROR
)
1077 cache
->unavailable_retaddr
= 1;
1081 throw_exception (ex
);
1085 /* Initialize the register state. */
1089 for (regnum
= 0; regnum
< num_regs
; regnum
++)
1090 dwarf2_frame_init_reg (gdbarch
, regnum
, &cache
->reg
[regnum
], this_frame
);
1093 /* Go through the DWARF2 CFI generated table and save its register
1094 location information in the cache. Note that we don't skip the
1095 return address column; it's perfectly all right for it to
1096 correspond to a real register. */
1098 int column
; /* CFI speak for "register number". */
1100 for (column
= 0; column
< fs
.regs
.reg
.size (); column
++)
1102 /* Use the GDB register number as the destination index. */
1103 int regnum
= dwarf_reg_to_regnum (gdbarch
, column
);
1105 /* Protect against a target returning a bad register. */
1106 if (regnum
< 0 || regnum
>= num_regs
)
1109 /* NOTE: cagney/2003-09-05: CFI should specify the disposition
1110 of all debug info registers. If it doesn't, complain (but
1111 not too loudly). It turns out that GCC assumes that an
1112 unspecified register implies "same value" when CFI (draft
1113 7) specifies nothing at all. Such a register could equally
1114 be interpreted as "undefined". Also note that this check
1115 isn't sufficient; it only checks that all registers in the
1116 range [0 .. max column] are specified, and won't detect
1117 problems when a debug info register falls outside of the
1118 table. We need a way of iterating through all the valid
1119 DWARF2 register numbers. */
1120 if (fs
.regs
.reg
[column
].how
== DWARF2_FRAME_REG_UNSPECIFIED
)
1122 if (cache
->reg
[regnum
].how
== DWARF2_FRAME_REG_UNSPECIFIED
)
1124 incomplete CFI data; unspecified registers (e.g., %s) at %s"),
1125 gdbarch_register_name (gdbarch
, regnum
),
1126 paddress (gdbarch
, fs
.pc
));
1129 cache
->reg
[regnum
] = fs
.regs
.reg
[column
];
1133 /* Eliminate any DWARF2_FRAME_REG_RA rules, and save the information
1134 we need for evaluating DWARF2_FRAME_REG_RA_OFFSET rules. */
1138 for (regnum
= 0; regnum
< num_regs
; regnum
++)
1140 if (cache
->reg
[regnum
].how
== DWARF2_FRAME_REG_RA
1141 || cache
->reg
[regnum
].how
== DWARF2_FRAME_REG_RA_OFFSET
)
1143 const std::vector
<struct dwarf2_frame_state_reg
> ®s
1145 ULONGEST retaddr_column
= fs
.retaddr_column
;
1147 /* It seems rather bizarre to specify an "empty" column as
1148 the return adress column. However, this is exactly
1149 what GCC does on some targets. It turns out that GCC
1150 assumes that the return address can be found in the
1151 register corresponding to the return address column.
1152 Incidentally, that's how we should treat a return
1153 address column specifying "same value" too. */
1154 if (fs
.retaddr_column
< fs
.regs
.reg
.size ()
1155 && regs
[retaddr_column
].how
!= DWARF2_FRAME_REG_UNSPECIFIED
1156 && regs
[retaddr_column
].how
!= DWARF2_FRAME_REG_SAME_VALUE
)
1158 if (cache
->reg
[regnum
].how
== DWARF2_FRAME_REG_RA
)
1159 cache
->reg
[regnum
] = regs
[retaddr_column
];
1161 cache
->retaddr_reg
= regs
[retaddr_column
];
1165 if (cache
->reg
[regnum
].how
== DWARF2_FRAME_REG_RA
)
1167 cache
->reg
[regnum
].loc
.reg
= fs
.retaddr_column
;
1168 cache
->reg
[regnum
].how
= DWARF2_FRAME_REG_SAVED_REG
;
1172 cache
->retaddr_reg
.loc
.reg
= fs
.retaddr_column
;
1173 cache
->retaddr_reg
.how
= DWARF2_FRAME_REG_SAVED_REG
;
1180 if (fs
.retaddr_column
< fs
.regs
.reg
.size ()
1181 && fs
.regs
.reg
[fs
.retaddr_column
].how
== DWARF2_FRAME_REG_UNDEFINED
)
1182 cache
->undefined_retaddr
= 1;
1187 static enum unwind_stop_reason
1188 dwarf2_frame_unwind_stop_reason (struct frame_info
*this_frame
,
1191 struct dwarf2_frame_cache
*cache
1192 = dwarf2_frame_cache (this_frame
, this_cache
);
1194 if (cache
->unavailable_retaddr
)
1195 return UNWIND_UNAVAILABLE
;
1197 if (cache
->undefined_retaddr
)
1198 return UNWIND_OUTERMOST
;
1200 return UNWIND_NO_REASON
;
1204 dwarf2_frame_this_id (struct frame_info
*this_frame
, void **this_cache
,
1205 struct frame_id
*this_id
)
1207 struct dwarf2_frame_cache
*cache
=
1208 dwarf2_frame_cache (this_frame
, this_cache
);
1210 if (cache
->unavailable_retaddr
)
1211 (*this_id
) = frame_id_build_unavailable_stack (get_frame_func (this_frame
));
1212 else if (cache
->undefined_retaddr
)
1215 (*this_id
) = frame_id_build (cache
->cfa
, get_frame_func (this_frame
));
1218 static struct value
*
1219 dwarf2_frame_prev_register (struct frame_info
*this_frame
, void **this_cache
,
1222 struct gdbarch
*gdbarch
= get_frame_arch (this_frame
);
1223 struct dwarf2_frame_cache
*cache
=
1224 dwarf2_frame_cache (this_frame
, this_cache
);
1228 /* Check whether THIS_FRAME is the bottom frame of a virtual tail
1229 call frame chain. */
1230 if (!cache
->checked_tailcall_bottom
)
1232 cache
->checked_tailcall_bottom
= 1;
1233 dwarf2_tailcall_sniffer_first (this_frame
, &cache
->tailcall_cache
,
1234 (cache
->entry_cfa_sp_offset_p
1235 ? &cache
->entry_cfa_sp_offset
: NULL
));
1238 /* Non-bottom frames of a virtual tail call frames chain use
1239 dwarf2_tailcall_frame_unwind unwinder so this code does not apply for
1240 them. If dwarf2_tailcall_prev_register_first does not have specific value
1241 unwind the register, tail call frames are assumed to have the register set
1242 of the top caller. */
1243 if (cache
->tailcall_cache
)
1247 val
= dwarf2_tailcall_prev_register_first (this_frame
,
1248 &cache
->tailcall_cache
,
1254 switch (cache
->reg
[regnum
].how
)
1256 case DWARF2_FRAME_REG_UNDEFINED
:
1257 /* If CFI explicitly specified that the value isn't defined,
1258 mark it as optimized away; the value isn't available. */
1259 return frame_unwind_got_optimized (this_frame
, regnum
);
1261 case DWARF2_FRAME_REG_SAVED_OFFSET
:
1262 addr
= cache
->cfa
+ cache
->reg
[regnum
].loc
.offset
;
1263 return frame_unwind_got_memory (this_frame
, regnum
, addr
);
1265 case DWARF2_FRAME_REG_SAVED_REG
:
1266 realnum
= dwarf_reg_to_regnum_or_error
1267 (gdbarch
, cache
->reg
[regnum
].loc
.reg
);
1268 return frame_unwind_got_register (this_frame
, regnum
, realnum
);
1270 case DWARF2_FRAME_REG_SAVED_EXP
:
1271 addr
= execute_stack_op (cache
->reg
[regnum
].loc
.exp
.start
,
1272 cache
->reg
[regnum
].loc
.exp
.len
,
1273 cache
->addr_size
, cache
->text_offset
,
1274 this_frame
, cache
->cfa
, 1);
1275 return frame_unwind_got_memory (this_frame
, regnum
, addr
);
1277 case DWARF2_FRAME_REG_SAVED_VAL_OFFSET
:
1278 addr
= cache
->cfa
+ cache
->reg
[regnum
].loc
.offset
;
1279 return frame_unwind_got_constant (this_frame
, regnum
, addr
);
1281 case DWARF2_FRAME_REG_SAVED_VAL_EXP
:
1282 addr
= execute_stack_op (cache
->reg
[regnum
].loc
.exp
.start
,
1283 cache
->reg
[regnum
].loc
.exp
.len
,
1284 cache
->addr_size
, cache
->text_offset
,
1285 this_frame
, cache
->cfa
, 1);
1286 return frame_unwind_got_constant (this_frame
, regnum
, addr
);
1288 case DWARF2_FRAME_REG_UNSPECIFIED
:
1289 /* GCC, in its infinite wisdom decided to not provide unwind
1290 information for registers that are "same value". Since
1291 DWARF2 (3 draft 7) doesn't define such behavior, said
1292 registers are actually undefined (which is different to CFI
1293 "undefined"). Code above issues a complaint about this.
1294 Here just fudge the books, assume GCC, and that the value is
1295 more inner on the stack. */
1296 return frame_unwind_got_register (this_frame
, regnum
, regnum
);
1298 case DWARF2_FRAME_REG_SAME_VALUE
:
1299 return frame_unwind_got_register (this_frame
, regnum
, regnum
);
1301 case DWARF2_FRAME_REG_CFA
:
1302 return frame_unwind_got_address (this_frame
, regnum
, cache
->cfa
);
1304 case DWARF2_FRAME_REG_CFA_OFFSET
:
1305 addr
= cache
->cfa
+ cache
->reg
[regnum
].loc
.offset
;
1306 return frame_unwind_got_address (this_frame
, regnum
, addr
);
1308 case DWARF2_FRAME_REG_RA_OFFSET
:
1309 addr
= cache
->reg
[regnum
].loc
.offset
;
1310 regnum
= dwarf_reg_to_regnum_or_error
1311 (gdbarch
, cache
->retaddr_reg
.loc
.reg
);
1312 addr
+= get_frame_register_unsigned (this_frame
, regnum
);
1313 return frame_unwind_got_address (this_frame
, regnum
, addr
);
1315 case DWARF2_FRAME_REG_FN
:
1316 return cache
->reg
[regnum
].loc
.fn (this_frame
, this_cache
, regnum
);
1319 internal_error (__FILE__
, __LINE__
, _("Unknown register rule."));
1323 /* Proxy for tailcall_frame_dealloc_cache for bottom frame of a virtual tail
1324 call frames chain. */
1327 dwarf2_frame_dealloc_cache (struct frame_info
*self
, void *this_cache
)
1329 struct dwarf2_frame_cache
*cache
= dwarf2_frame_cache (self
, &this_cache
);
1331 if (cache
->tailcall_cache
)
1332 dwarf2_tailcall_frame_unwind
.dealloc_cache (self
, cache
->tailcall_cache
);
1336 dwarf2_frame_sniffer (const struct frame_unwind
*self
,
1337 struct frame_info
*this_frame
, void **this_cache
)
1339 if (!dwarf2_frame_unwinders_enabled_p
)
1342 /* Grab an address that is guarenteed to reside somewhere within the
1343 function. get_frame_pc(), with a no-return next function, can
1344 end up returning something past the end of this function's body.
1345 If the frame we're sniffing for is a signal frame whose start
1346 address is placed on the stack by the OS, its FDE must
1347 extend one byte before its start address or we could potentially
1348 select the FDE of the previous function. */
1349 CORE_ADDR block_addr
= get_frame_address_in_block (this_frame
);
1350 struct dwarf2_fde
*fde
= dwarf2_frame_find_fde (&block_addr
, NULL
);
1355 /* On some targets, signal trampolines may have unwind information.
1356 We need to recognize them so that we set the frame type
1359 if (fde
->cie
->signal_frame
1360 || dwarf2_frame_signal_frame_p (get_frame_arch (this_frame
),
1362 return self
->type
== SIGTRAMP_FRAME
;
1364 if (self
->type
!= NORMAL_FRAME
)
1370 static const struct frame_unwind dwarf2_frame_unwind
=
1373 dwarf2_frame_unwind_stop_reason
,
1374 dwarf2_frame_this_id
,
1375 dwarf2_frame_prev_register
,
1377 dwarf2_frame_sniffer
,
1378 dwarf2_frame_dealloc_cache
1381 static const struct frame_unwind dwarf2_signal_frame_unwind
=
1384 dwarf2_frame_unwind_stop_reason
,
1385 dwarf2_frame_this_id
,
1386 dwarf2_frame_prev_register
,
1388 dwarf2_frame_sniffer
,
1390 /* TAILCALL_CACHE can never be in such frame to need dealloc_cache. */
1394 /* Append the DWARF-2 frame unwinders to GDBARCH's list. */
1397 dwarf2_append_unwinders (struct gdbarch
*gdbarch
)
1399 /* TAILCALL_FRAME must be first to find the record by
1400 dwarf2_tailcall_sniffer_first. */
1401 frame_unwind_append_unwinder (gdbarch
, &dwarf2_tailcall_frame_unwind
);
1403 frame_unwind_append_unwinder (gdbarch
, &dwarf2_frame_unwind
);
1404 frame_unwind_append_unwinder (gdbarch
, &dwarf2_signal_frame_unwind
);
1408 /* There is no explicitly defined relationship between the CFA and the
1409 location of frame's local variables and arguments/parameters.
1410 Therefore, frame base methods on this page should probably only be
1411 used as a last resort, just to avoid printing total garbage as a
1412 response to the "info frame" command. */
1415 dwarf2_frame_base_address (struct frame_info
*this_frame
, void **this_cache
)
1417 struct dwarf2_frame_cache
*cache
=
1418 dwarf2_frame_cache (this_frame
, this_cache
);
1423 static const struct frame_base dwarf2_frame_base
=
1425 &dwarf2_frame_unwind
,
1426 dwarf2_frame_base_address
,
1427 dwarf2_frame_base_address
,
1428 dwarf2_frame_base_address
1431 const struct frame_base
*
1432 dwarf2_frame_base_sniffer (struct frame_info
*this_frame
)
1434 CORE_ADDR block_addr
= get_frame_address_in_block (this_frame
);
1436 if (dwarf2_frame_find_fde (&block_addr
, NULL
))
1437 return &dwarf2_frame_base
;
1442 /* Compute the CFA for THIS_FRAME, but only if THIS_FRAME came from
1443 the DWARF unwinder. This is used to implement
1444 DW_OP_call_frame_cfa. */
1447 dwarf2_frame_cfa (struct frame_info
*this_frame
)
1449 if (frame_unwinder_is (this_frame
, &record_btrace_tailcall_frame_unwind
)
1450 || frame_unwinder_is (this_frame
, &record_btrace_frame_unwind
))
1451 throw_error (NOT_AVAILABLE_ERROR
,
1452 _("cfa not available for record btrace target"));
1454 while (get_frame_type (this_frame
) == INLINE_FRAME
)
1455 this_frame
= get_prev_frame (this_frame
);
1456 if (get_frame_unwind_stop_reason (this_frame
) == UNWIND_UNAVAILABLE
)
1457 throw_error (NOT_AVAILABLE_ERROR
,
1458 _("can't compute CFA for this frame: "
1459 "required registers or memory are unavailable"));
1461 if (get_frame_id (this_frame
).stack_status
!= FID_STACK_VALID
)
1462 throw_error (NOT_AVAILABLE_ERROR
,
1463 _("can't compute CFA for this frame: "
1464 "frame base not available"));
1466 return get_frame_base (this_frame
);
1469 const struct objfile_data
*dwarf2_frame_objfile_data
;
1472 read_1_byte (bfd
*abfd
, const gdb_byte
*buf
)
1474 return bfd_get_8 (abfd
, buf
);
1478 read_4_bytes (bfd
*abfd
, const gdb_byte
*buf
)
1480 return bfd_get_32 (abfd
, buf
);
1484 read_8_bytes (bfd
*abfd
, const gdb_byte
*buf
)
1486 return bfd_get_64 (abfd
, buf
);
1490 read_initial_length (bfd
*abfd
, const gdb_byte
*buf
,
1491 unsigned int *bytes_read_ptr
)
1495 result
= bfd_get_32 (abfd
, buf
);
1496 if (result
== 0xffffffff)
1498 result
= bfd_get_64 (abfd
, buf
+ 4);
1499 *bytes_read_ptr
= 12;
1502 *bytes_read_ptr
= 4;
1508 /* Pointer encoding helper functions. */
1510 /* GCC supports exception handling based on DWARF2 CFI. However, for
1511 technical reasons, it encodes addresses in its FDE's in a different
1512 way. Several "pointer encodings" are supported. The encoding
1513 that's used for a particular FDE is determined by the 'R'
1514 augmentation in the associated CIE. The argument of this
1515 augmentation is a single byte.
1517 The address can be encoded as 2 bytes, 4 bytes, 8 bytes, or as a
1518 LEB128. This is encoded in bits 0, 1 and 2. Bit 3 encodes whether
1519 the address is signed or unsigned. Bits 4, 5 and 6 encode how the
1520 address should be interpreted (absolute, relative to the current
1521 position in the FDE, ...). Bit 7, indicates that the address
1522 should be dereferenced. */
1525 encoding_for_size (unsigned int size
)
1530 return DW_EH_PE_udata2
;
1532 return DW_EH_PE_udata4
;
1534 return DW_EH_PE_udata8
;
1536 internal_error (__FILE__
, __LINE__
, _("Unsupported address size"));
1541 read_encoded_value (struct comp_unit
*unit
, gdb_byte encoding
,
1542 int ptr_len
, const gdb_byte
*buf
,
1543 unsigned int *bytes_read_ptr
,
1544 CORE_ADDR func_base
)
1549 /* GCC currently doesn't generate DW_EH_PE_indirect encodings for
1551 if (encoding
& DW_EH_PE_indirect
)
1552 internal_error (__FILE__
, __LINE__
,
1553 _("Unsupported encoding: DW_EH_PE_indirect"));
1555 *bytes_read_ptr
= 0;
1557 switch (encoding
& 0x70)
1559 case DW_EH_PE_absptr
:
1562 case DW_EH_PE_pcrel
:
1563 base
= bfd_get_section_vma (unit
->abfd
, unit
->dwarf_frame_section
);
1564 base
+= (buf
- unit
->dwarf_frame_buffer
);
1566 case DW_EH_PE_datarel
:
1569 case DW_EH_PE_textrel
:
1572 case DW_EH_PE_funcrel
:
1575 case DW_EH_PE_aligned
:
1577 offset
= buf
- unit
->dwarf_frame_buffer
;
1578 if ((offset
% ptr_len
) != 0)
1580 *bytes_read_ptr
= ptr_len
- (offset
% ptr_len
);
1581 buf
+= *bytes_read_ptr
;
1585 internal_error (__FILE__
, __LINE__
,
1586 _("Invalid or unsupported encoding"));
1589 if ((encoding
& 0x07) == 0x00)
1591 encoding
|= encoding_for_size (ptr_len
);
1592 if (bfd_get_sign_extend_vma (unit
->abfd
))
1593 encoding
|= DW_EH_PE_signed
;
1596 switch (encoding
& 0x0f)
1598 case DW_EH_PE_uleb128
:
1601 const gdb_byte
*end_buf
= buf
+ (sizeof (value
) + 1) * 8 / 7;
1603 *bytes_read_ptr
+= safe_read_uleb128 (buf
, end_buf
, &value
) - buf
;
1604 return base
+ value
;
1606 case DW_EH_PE_udata2
:
1607 *bytes_read_ptr
+= 2;
1608 return (base
+ bfd_get_16 (unit
->abfd
, (bfd_byte
*) buf
));
1609 case DW_EH_PE_udata4
:
1610 *bytes_read_ptr
+= 4;
1611 return (base
+ bfd_get_32 (unit
->abfd
, (bfd_byte
*) buf
));
1612 case DW_EH_PE_udata8
:
1613 *bytes_read_ptr
+= 8;
1614 return (base
+ bfd_get_64 (unit
->abfd
, (bfd_byte
*) buf
));
1615 case DW_EH_PE_sleb128
:
1618 const gdb_byte
*end_buf
= buf
+ (sizeof (value
) + 1) * 8 / 7;
1620 *bytes_read_ptr
+= safe_read_sleb128 (buf
, end_buf
, &value
) - buf
;
1621 return base
+ value
;
1623 case DW_EH_PE_sdata2
:
1624 *bytes_read_ptr
+= 2;
1625 return (base
+ bfd_get_signed_16 (unit
->abfd
, (bfd_byte
*) buf
));
1626 case DW_EH_PE_sdata4
:
1627 *bytes_read_ptr
+= 4;
1628 return (base
+ bfd_get_signed_32 (unit
->abfd
, (bfd_byte
*) buf
));
1629 case DW_EH_PE_sdata8
:
1630 *bytes_read_ptr
+= 8;
1631 return (base
+ bfd_get_signed_64 (unit
->abfd
, (bfd_byte
*) buf
));
1633 internal_error (__FILE__
, __LINE__
,
1634 _("Invalid or unsupported encoding"));
1640 bsearch_cie_cmp (const void *key
, const void *element
)
1642 ULONGEST cie_pointer
= *(ULONGEST
*) key
;
1643 struct dwarf2_cie
*cie
= *(struct dwarf2_cie
**) element
;
1645 if (cie_pointer
== cie
->cie_pointer
)
1648 return (cie_pointer
< cie
->cie_pointer
) ? -1 : 1;
1651 /* Find CIE with the given CIE_POINTER in CIE_TABLE. */
1652 static struct dwarf2_cie
*
1653 find_cie (struct dwarf2_cie_table
*cie_table
, ULONGEST cie_pointer
)
1655 struct dwarf2_cie
**p_cie
;
1657 /* The C standard (ISO/IEC 9899:TC2) requires the BASE argument to
1658 bsearch be non-NULL. */
1659 if (cie_table
->entries
== NULL
)
1661 gdb_assert (cie_table
->num_entries
== 0);
1665 p_cie
= ((struct dwarf2_cie
**)
1666 bsearch (&cie_pointer
, cie_table
->entries
, cie_table
->num_entries
,
1667 sizeof (cie_table
->entries
[0]), bsearch_cie_cmp
));
1673 /* Add a pointer to new CIE to the CIE_TABLE, allocating space for it. */
1675 add_cie (struct dwarf2_cie_table
*cie_table
, struct dwarf2_cie
*cie
)
1677 const int n
= cie_table
->num_entries
;
1680 || cie_table
->entries
[n
- 1]->cie_pointer
< cie
->cie_pointer
);
1683 = XRESIZEVEC (struct dwarf2_cie
*, cie_table
->entries
, n
+ 1);
1684 cie_table
->entries
[n
] = cie
;
1685 cie_table
->num_entries
= n
+ 1;
1689 bsearch_fde_cmp (const void *key
, const void *element
)
1691 CORE_ADDR seek_pc
= *(CORE_ADDR
*) key
;
1692 struct dwarf2_fde
*fde
= *(struct dwarf2_fde
**) element
;
1694 if (seek_pc
< fde
->initial_location
)
1696 if (seek_pc
< fde
->initial_location
+ fde
->address_range
)
1701 /* Find the FDE for *PC. Return a pointer to the FDE, and store the
1702 inital location associated with it into *PC. */
1704 static struct dwarf2_fde
*
1705 dwarf2_frame_find_fde (CORE_ADDR
*pc
, CORE_ADDR
*out_offset
)
1707 for (objfile
*objfile
: current_program_space
->objfiles ())
1709 struct dwarf2_fde_table
*fde_table
;
1710 struct dwarf2_fde
**p_fde
;
1714 fde_table
= ((struct dwarf2_fde_table
*)
1715 objfile_data (objfile
, dwarf2_frame_objfile_data
));
1716 if (fde_table
== NULL
)
1718 dwarf2_build_frame_info (objfile
);
1719 fde_table
= ((struct dwarf2_fde_table
*)
1720 objfile_data (objfile
, dwarf2_frame_objfile_data
));
1722 gdb_assert (fde_table
!= NULL
);
1724 if (fde_table
->num_entries
== 0)
1727 gdb_assert (objfile
->section_offsets
);
1728 offset
= ANOFFSET (objfile
->section_offsets
, SECT_OFF_TEXT (objfile
));
1730 gdb_assert (fde_table
->num_entries
> 0);
1731 if (*pc
< offset
+ fde_table
->entries
[0]->initial_location
)
1734 seek_pc
= *pc
- offset
;
1735 p_fde
= ((struct dwarf2_fde
**)
1736 bsearch (&seek_pc
, fde_table
->entries
, fde_table
->num_entries
,
1737 sizeof (fde_table
->entries
[0]), bsearch_fde_cmp
));
1740 *pc
= (*p_fde
)->initial_location
+ offset
;
1742 *out_offset
= offset
;
1749 /* Add a pointer to new FDE to the FDE_TABLE, allocating space for it. */
1751 add_fde (struct dwarf2_fde_table
*fde_table
, struct dwarf2_fde
*fde
)
1753 if (fde
->address_range
== 0)
1754 /* Discard useless FDEs. */
1757 fde_table
->num_entries
+= 1;
1758 fde_table
->entries
= XRESIZEVEC (struct dwarf2_fde
*, fde_table
->entries
,
1759 fde_table
->num_entries
);
1760 fde_table
->entries
[fde_table
->num_entries
- 1] = fde
;
1763 #define DW64_CIE_ID 0xffffffffffffffffULL
1765 /* Defines the type of eh_frames that are expected to be decoded: CIE, FDE
1770 EH_CIE_TYPE_ID
= 1 << 0,
1771 EH_FDE_TYPE_ID
= 1 << 1,
1772 EH_CIE_OR_FDE_TYPE_ID
= EH_CIE_TYPE_ID
| EH_FDE_TYPE_ID
1775 static const gdb_byte
*decode_frame_entry (struct comp_unit
*unit
,
1776 const gdb_byte
*start
,
1778 struct dwarf2_cie_table
*cie_table
,
1779 struct dwarf2_fde_table
*fde_table
,
1780 enum eh_frame_type entry_type
);
1782 /* Decode the next CIE or FDE, entry_type specifies the expected type.
1783 Return NULL if invalid input, otherwise the next byte to be processed. */
1785 static const gdb_byte
*
1786 decode_frame_entry_1 (struct comp_unit
*unit
, const gdb_byte
*start
,
1788 struct dwarf2_cie_table
*cie_table
,
1789 struct dwarf2_fde_table
*fde_table
,
1790 enum eh_frame_type entry_type
)
1792 struct gdbarch
*gdbarch
= get_objfile_arch (unit
->objfile
);
1793 const gdb_byte
*buf
, *end
;
1795 unsigned int bytes_read
;
1798 ULONGEST cie_pointer
;
1803 length
= read_initial_length (unit
->abfd
, buf
, &bytes_read
);
1807 /* Are we still within the section? */
1808 if (end
> unit
->dwarf_frame_buffer
+ unit
->dwarf_frame_size
)
1814 /* Distinguish between 32 and 64-bit encoded frame info. */
1815 dwarf64_p
= (bytes_read
== 12);
1817 /* In a .eh_frame section, zero is used to distinguish CIEs from FDEs. */
1821 cie_id
= DW64_CIE_ID
;
1827 cie_pointer
= read_8_bytes (unit
->abfd
, buf
);
1832 cie_pointer
= read_4_bytes (unit
->abfd
, buf
);
1836 if (cie_pointer
== cie_id
)
1838 /* This is a CIE. */
1839 struct dwarf2_cie
*cie
;
1841 unsigned int cie_version
;
1843 /* Check that a CIE was expected. */
1844 if ((entry_type
& EH_CIE_TYPE_ID
) == 0)
1845 error (_("Found a CIE when not expecting it."));
1847 /* Record the offset into the .debug_frame section of this CIE. */
1848 cie_pointer
= start
- unit
->dwarf_frame_buffer
;
1850 /* Check whether we've already read it. */
1851 if (find_cie (cie_table
, cie_pointer
))
1854 cie
= XOBNEW (&unit
->objfile
->objfile_obstack
, struct dwarf2_cie
);
1855 cie
->initial_instructions
= NULL
;
1856 cie
->cie_pointer
= cie_pointer
;
1858 /* The encoding for FDE's in a normal .debug_frame section
1859 depends on the target address size. */
1860 cie
->encoding
= DW_EH_PE_absptr
;
1862 /* We'll determine the final value later, but we need to
1863 initialize it conservatively. */
1864 cie
->signal_frame
= 0;
1866 /* Check version number. */
1867 cie_version
= read_1_byte (unit
->abfd
, buf
);
1868 if (cie_version
!= 1 && cie_version
!= 3 && cie_version
!= 4)
1870 cie
->version
= cie_version
;
1873 /* Interpret the interesting bits of the augmentation. */
1874 cie
->augmentation
= augmentation
= (char *) buf
;
1875 buf
+= (strlen (augmentation
) + 1);
1877 /* Ignore armcc augmentations. We only use them for quirks,
1878 and that doesn't happen until later. */
1879 if (startswith (augmentation
, "armcc"))
1880 augmentation
+= strlen (augmentation
);
1882 /* The GCC 2.x "eh" augmentation has a pointer immediately
1883 following the augmentation string, so it must be handled
1885 if (augmentation
[0] == 'e' && augmentation
[1] == 'h')
1888 buf
+= gdbarch_ptr_bit (gdbarch
) / TARGET_CHAR_BIT
;
1892 if (cie
->version
>= 4)
1894 /* FIXME: check that this is the same as from the CU header. */
1895 cie
->addr_size
= read_1_byte (unit
->abfd
, buf
);
1897 cie
->segment_size
= read_1_byte (unit
->abfd
, buf
);
1902 cie
->addr_size
= gdbarch_dwarf2_addr_size (gdbarch
);
1903 cie
->segment_size
= 0;
1905 /* Address values in .eh_frame sections are defined to have the
1906 target's pointer size. Watchout: This breaks frame info for
1907 targets with pointer size < address size, unless a .debug_frame
1908 section exists as well. */
1910 cie
->ptr_size
= gdbarch_ptr_bit (gdbarch
) / TARGET_CHAR_BIT
;
1912 cie
->ptr_size
= cie
->addr_size
;
1914 buf
= gdb_read_uleb128 (buf
, end
, &uleb128
);
1917 cie
->code_alignment_factor
= uleb128
;
1919 buf
= gdb_read_sleb128 (buf
, end
, &sleb128
);
1922 cie
->data_alignment_factor
= sleb128
;
1924 if (cie_version
== 1)
1926 cie
->return_address_register
= read_1_byte (unit
->abfd
, buf
);
1931 buf
= gdb_read_uleb128 (buf
, end
, &uleb128
);
1934 cie
->return_address_register
= uleb128
;
1937 cie
->return_address_register
1938 = dwarf2_frame_adjust_regnum (gdbarch
,
1939 cie
->return_address_register
,
1942 cie
->saw_z_augmentation
= (*augmentation
== 'z');
1943 if (cie
->saw_z_augmentation
)
1945 uint64_t uleb_length
;
1947 buf
= gdb_read_uleb128 (buf
, end
, &uleb_length
);
1950 cie
->initial_instructions
= buf
+ uleb_length
;
1954 while (*augmentation
)
1956 /* "L" indicates a byte showing how the LSDA pointer is encoded. */
1957 if (*augmentation
== 'L')
1964 /* "R" indicates a byte indicating how FDE addresses are encoded. */
1965 else if (*augmentation
== 'R')
1967 cie
->encoding
= *buf
++;
1971 /* "P" indicates a personality routine in the CIE augmentation. */
1972 else if (*augmentation
== 'P')
1974 /* Skip. Avoid indirection since we throw away the result. */
1975 gdb_byte encoding
= (*buf
++) & ~DW_EH_PE_indirect
;
1976 read_encoded_value (unit
, encoding
, cie
->ptr_size
,
1977 buf
, &bytes_read
, 0);
1982 /* "S" indicates a signal frame, such that the return
1983 address must not be decremented to locate the call frame
1984 info for the previous frame; it might even be the first
1985 instruction of a function, so decrementing it would take
1986 us to a different function. */
1987 else if (*augmentation
== 'S')
1989 cie
->signal_frame
= 1;
1993 /* Otherwise we have an unknown augmentation. Assume that either
1994 there is no augmentation data, or we saw a 'z' prefix. */
1997 if (cie
->initial_instructions
)
1998 buf
= cie
->initial_instructions
;
2003 cie
->initial_instructions
= buf
;
2007 add_cie (cie_table
, cie
);
2011 /* This is a FDE. */
2012 struct dwarf2_fde
*fde
;
2015 /* Check that an FDE was expected. */
2016 if ((entry_type
& EH_FDE_TYPE_ID
) == 0)
2017 error (_("Found an FDE when not expecting it."));
2019 /* In an .eh_frame section, the CIE pointer is the delta between the
2020 address within the FDE where the CIE pointer is stored and the
2021 address of the CIE. Convert it to an offset into the .eh_frame
2025 cie_pointer
= buf
- unit
->dwarf_frame_buffer
- cie_pointer
;
2026 cie_pointer
-= (dwarf64_p
? 8 : 4);
2029 /* In either case, validate the result is still within the section. */
2030 if (cie_pointer
>= unit
->dwarf_frame_size
)
2033 fde
= XOBNEW (&unit
->objfile
->objfile_obstack
, struct dwarf2_fde
);
2034 fde
->cie
= find_cie (cie_table
, cie_pointer
);
2035 if (fde
->cie
== NULL
)
2037 decode_frame_entry (unit
, unit
->dwarf_frame_buffer
+ cie_pointer
,
2038 eh_frame_p
, cie_table
, fde_table
,
2040 fde
->cie
= find_cie (cie_table
, cie_pointer
);
2043 gdb_assert (fde
->cie
!= NULL
);
2045 addr
= read_encoded_value (unit
, fde
->cie
->encoding
, fde
->cie
->ptr_size
,
2046 buf
, &bytes_read
, 0);
2047 fde
->initial_location
= gdbarch_adjust_dwarf2_addr (gdbarch
, addr
);
2050 fde
->address_range
=
2051 read_encoded_value (unit
, fde
->cie
->encoding
& 0x0f,
2052 fde
->cie
->ptr_size
, buf
, &bytes_read
, 0);
2053 addr
= gdbarch_adjust_dwarf2_addr (gdbarch
, addr
+ fde
->address_range
);
2054 fde
->address_range
= addr
- fde
->initial_location
;
2057 /* A 'z' augmentation in the CIE implies the presence of an
2058 augmentation field in the FDE as well. The only thing known
2059 to be in here at present is the LSDA entry for EH. So we
2060 can skip the whole thing. */
2061 if (fde
->cie
->saw_z_augmentation
)
2063 uint64_t uleb_length
;
2065 buf
= gdb_read_uleb128 (buf
, end
, &uleb_length
);
2073 fde
->instructions
= buf
;
2076 fde
->eh_frame_p
= eh_frame_p
;
2078 add_fde (fde_table
, fde
);
2084 /* Read a CIE or FDE in BUF and decode it. Entry_type specifies whether we
2085 expect an FDE or a CIE. */
2087 static const gdb_byte
*
2088 decode_frame_entry (struct comp_unit
*unit
, const gdb_byte
*start
,
2090 struct dwarf2_cie_table
*cie_table
,
2091 struct dwarf2_fde_table
*fde_table
,
2092 enum eh_frame_type entry_type
)
2094 enum { NONE
, ALIGN4
, ALIGN8
, FAIL
} workaround
= NONE
;
2095 const gdb_byte
*ret
;
2096 ptrdiff_t start_offset
;
2100 ret
= decode_frame_entry_1 (unit
, start
, eh_frame_p
,
2101 cie_table
, fde_table
, entry_type
);
2105 /* We have corrupt input data of some form. */
2107 /* ??? Try, weakly, to work around compiler/assembler/linker bugs
2108 and mismatches wrt padding and alignment of debug sections. */
2109 /* Note that there is no requirement in the standard for any
2110 alignment at all in the frame unwind sections. Testing for
2111 alignment before trying to interpret data would be incorrect.
2113 However, GCC traditionally arranged for frame sections to be
2114 sized such that the FDE length and CIE fields happen to be
2115 aligned (in theory, for performance). This, unfortunately,
2116 was done with .align directives, which had the side effect of
2117 forcing the section to be aligned by the linker.
2119 This becomes a problem when you have some other producer that
2120 creates frame sections that are not as strictly aligned. That
2121 produces a hole in the frame info that gets filled by the
2124 The GCC behaviour is arguably a bug, but it's effectively now
2125 part of the ABI, so we're now stuck with it, at least at the
2126 object file level. A smart linker may decide, in the process
2127 of compressing duplicate CIE information, that it can rewrite
2128 the entire output section without this extra padding. */
2130 start_offset
= start
- unit
->dwarf_frame_buffer
;
2131 if (workaround
< ALIGN4
&& (start_offset
& 3) != 0)
2133 start
+= 4 - (start_offset
& 3);
2134 workaround
= ALIGN4
;
2137 if (workaround
< ALIGN8
&& (start_offset
& 7) != 0)
2139 start
+= 8 - (start_offset
& 7);
2140 workaround
= ALIGN8
;
2144 /* Nothing left to try. Arrange to return as if we've consumed
2145 the entire input section. Hopefully we'll get valid info from
2146 the other of .debug_frame/.eh_frame. */
2148 ret
= unit
->dwarf_frame_buffer
+ unit
->dwarf_frame_size
;
2159 Corrupt data in %s:%s; align 4 workaround apparently succeeded"),
2160 unit
->dwarf_frame_section
->owner
->filename
,
2161 unit
->dwarf_frame_section
->name
);
2166 Corrupt data in %s:%s; align 8 workaround apparently succeeded"),
2167 unit
->dwarf_frame_section
->owner
->filename
,
2168 unit
->dwarf_frame_section
->name
);
2172 complaint (_("Corrupt data in %s:%s"),
2173 unit
->dwarf_frame_section
->owner
->filename
,
2174 unit
->dwarf_frame_section
->name
);
2182 qsort_fde_cmp (const void *a
, const void *b
)
2184 struct dwarf2_fde
*aa
= *(struct dwarf2_fde
**)a
;
2185 struct dwarf2_fde
*bb
= *(struct dwarf2_fde
**)b
;
2187 if (aa
->initial_location
== bb
->initial_location
)
2189 if (aa
->address_range
!= bb
->address_range
2190 && aa
->eh_frame_p
== 0 && bb
->eh_frame_p
== 0)
2191 /* Linker bug, e.g. gold/10400.
2192 Work around it by keeping stable sort order. */
2193 return (a
< b
) ? -1 : 1;
2195 /* Put eh_frame entries after debug_frame ones. */
2196 return aa
->eh_frame_p
- bb
->eh_frame_p
;
2199 return (aa
->initial_location
< bb
->initial_location
) ? -1 : 1;
2203 dwarf2_build_frame_info (struct objfile
*objfile
)
2205 struct comp_unit
*unit
;
2206 const gdb_byte
*frame_ptr
;
2207 struct dwarf2_cie_table cie_table
;
2208 struct dwarf2_fde_table fde_table
;
2209 struct dwarf2_fde_table
*fde_table2
;
2211 cie_table
.num_entries
= 0;
2212 cie_table
.entries
= NULL
;
2214 fde_table
.num_entries
= 0;
2215 fde_table
.entries
= NULL
;
2217 /* Build a minimal decoding of the DWARF2 compilation unit. */
2218 unit
= XOBNEW (&objfile
->objfile_obstack
, comp_unit
);
2219 unit
->abfd
= objfile
->obfd
;
2220 unit
->objfile
= objfile
;
2224 if (objfile
->separate_debug_objfile_backlink
== NULL
)
2226 /* Do not read .eh_frame from separate file as they must be also
2227 present in the main file. */
2228 dwarf2_get_section_info (objfile
, DWARF2_EH_FRAME
,
2229 &unit
->dwarf_frame_section
,
2230 &unit
->dwarf_frame_buffer
,
2231 &unit
->dwarf_frame_size
);
2232 if (unit
->dwarf_frame_size
)
2234 asection
*got
, *txt
;
2236 /* FIXME: kettenis/20030602: This is the DW_EH_PE_datarel base
2237 that is used for the i386/amd64 target, which currently is
2238 the only target in GCC that supports/uses the
2239 DW_EH_PE_datarel encoding. */
2240 got
= bfd_get_section_by_name (unit
->abfd
, ".got");
2242 unit
->dbase
= got
->vma
;
2244 /* GCC emits the DW_EH_PE_textrel encoding type on sh and ia64
2246 txt
= bfd_get_section_by_name (unit
->abfd
, ".text");
2248 unit
->tbase
= txt
->vma
;
2252 frame_ptr
= unit
->dwarf_frame_buffer
;
2253 while (frame_ptr
< unit
->dwarf_frame_buffer
+ unit
->dwarf_frame_size
)
2254 frame_ptr
= decode_frame_entry (unit
, frame_ptr
, 1,
2255 &cie_table
, &fde_table
,
2256 EH_CIE_OR_FDE_TYPE_ID
);
2259 CATCH (e
, RETURN_MASK_ERROR
)
2261 warning (_("skipping .eh_frame info of %s: %s"),
2262 objfile_name (objfile
), e
.message
);
2264 if (fde_table
.num_entries
!= 0)
2266 xfree (fde_table
.entries
);
2267 fde_table
.entries
= NULL
;
2268 fde_table
.num_entries
= 0;
2270 /* The cie_table is discarded by the next if. */
2274 if (cie_table
.num_entries
!= 0)
2276 /* Reinit cie_table: debug_frame has different CIEs. */
2277 xfree (cie_table
.entries
);
2278 cie_table
.num_entries
= 0;
2279 cie_table
.entries
= NULL
;
2284 dwarf2_get_section_info (objfile
, DWARF2_DEBUG_FRAME
,
2285 &unit
->dwarf_frame_section
,
2286 &unit
->dwarf_frame_buffer
,
2287 &unit
->dwarf_frame_size
);
2288 if (unit
->dwarf_frame_size
)
2290 int num_old_fde_entries
= fde_table
.num_entries
;
2294 frame_ptr
= unit
->dwarf_frame_buffer
;
2295 while (frame_ptr
< unit
->dwarf_frame_buffer
+ unit
->dwarf_frame_size
)
2296 frame_ptr
= decode_frame_entry (unit
, frame_ptr
, 0,
2297 &cie_table
, &fde_table
,
2298 EH_CIE_OR_FDE_TYPE_ID
);
2300 CATCH (e
, RETURN_MASK_ERROR
)
2302 warning (_("skipping .debug_frame info of %s: %s"),
2303 objfile_name (objfile
), e
.message
);
2305 if (fde_table
.num_entries
!= 0)
2307 fde_table
.num_entries
= num_old_fde_entries
;
2308 if (num_old_fde_entries
== 0)
2310 xfree (fde_table
.entries
);
2311 fde_table
.entries
= NULL
;
2316 = XRESIZEVEC (struct dwarf2_fde
*, fde_table
.entries
,
2317 fde_table
.num_entries
);
2320 fde_table
.num_entries
= num_old_fde_entries
;
2321 /* The cie_table is discarded by the next if. */
2326 /* Discard the cie_table, it is no longer needed. */
2327 if (cie_table
.num_entries
!= 0)
2329 xfree (cie_table
.entries
);
2330 cie_table
.entries
= NULL
; /* Paranoia. */
2331 cie_table
.num_entries
= 0; /* Paranoia. */
2334 /* Copy fde_table to obstack: it is needed at runtime. */
2335 fde_table2
= XOBNEW (&objfile
->objfile_obstack
, struct dwarf2_fde_table
);
2337 if (fde_table
.num_entries
== 0)
2339 fde_table2
->entries
= NULL
;
2340 fde_table2
->num_entries
= 0;
2344 struct dwarf2_fde
*fde_prev
= NULL
;
2345 struct dwarf2_fde
*first_non_zero_fde
= NULL
;
2348 /* Prepare FDE table for lookups. */
2349 qsort (fde_table
.entries
, fde_table
.num_entries
,
2350 sizeof (fde_table
.entries
[0]), qsort_fde_cmp
);
2352 /* Check for leftovers from --gc-sections. The GNU linker sets
2353 the relevant symbols to zero, but doesn't zero the FDE *end*
2354 ranges because there's no relocation there. It's (offset,
2355 length), not (start, end). On targets where address zero is
2356 just another valid address this can be a problem, since the
2357 FDEs appear to be non-empty in the output --- we could pick
2358 out the wrong FDE. To work around this, when overlaps are
2359 detected, we prefer FDEs that do not start at zero.
2361 Start by finding the first FDE with non-zero start. Below
2362 we'll discard all FDEs that start at zero and overlap this
2364 for (i
= 0; i
< fde_table
.num_entries
; i
++)
2366 struct dwarf2_fde
*fde
= fde_table
.entries
[i
];
2368 if (fde
->initial_location
!= 0)
2370 first_non_zero_fde
= fde
;
2375 /* Since we'll be doing bsearch, squeeze out identical (except
2376 for eh_frame_p) fde entries so bsearch result is predictable.
2377 Also discard leftovers from --gc-sections. */
2378 fde_table2
->num_entries
= 0;
2379 for (i
= 0; i
< fde_table
.num_entries
; i
++)
2381 struct dwarf2_fde
*fde
= fde_table
.entries
[i
];
2383 if (fde
->initial_location
== 0
2384 && first_non_zero_fde
!= NULL
2385 && (first_non_zero_fde
->initial_location
2386 < fde
->initial_location
+ fde
->address_range
))
2389 if (fde_prev
!= NULL
2390 && fde_prev
->initial_location
== fde
->initial_location
)
2393 obstack_grow (&objfile
->objfile_obstack
, &fde_table
.entries
[i
],
2394 sizeof (fde_table
.entries
[0]));
2395 ++fde_table2
->num_entries
;
2399 = (struct dwarf2_fde
**) obstack_finish (&objfile
->objfile_obstack
);
2401 /* Discard the original fde_table. */
2402 xfree (fde_table
.entries
);
2405 set_objfile_data (objfile
, dwarf2_frame_objfile_data
, fde_table2
);
2408 /* Handle 'maintenance show dwarf unwinders'. */
2411 show_dwarf_unwinders_enabled_p (struct ui_file
*file
, int from_tty
,
2412 struct cmd_list_element
*c
,
2415 fprintf_filtered (file
,
2416 _("The DWARF stack unwinders are currently %s.\n"),
2421 _initialize_dwarf2_frame (void)
2423 dwarf2_frame_data
= gdbarch_data_register_pre_init (dwarf2_frame_init
);
2424 dwarf2_frame_objfile_data
= register_objfile_data ();
2426 add_setshow_boolean_cmd ("unwinders", class_obscure
,
2427 &dwarf2_frame_unwinders_enabled_p
, _("\
2428 Set whether the DWARF stack frame unwinders are used."), _("\
2429 Show whether the DWARF stack frame unwinders are used."), _("\
2430 When enabled the DWARF stack frame unwinders can be used for architectures\n\
2431 that support the DWARF unwinders. Enabling the DWARF unwinders for an\n\
2432 architecture that doesn't support them will have no effect."),
2434 show_dwarf_unwinders_enabled_p
,
2436 &show_dwarf_cmdlist
);
2439 selftests::register_test_foreach_arch ("execute_cfa_program",
2440 selftests::execute_cfa_program_test
);