1 /* Frame unwinder for frames with DWARF Call Frame Information.
3 Copyright (C) 2003-2021 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 "dwarf2/expr.h"
25 #include "dwarf2/leb.h"
27 #include "frame-base.h"
28 #include "frame-unwind.h"
37 #include "complaints.h"
38 #include "dwarf2/frame.h"
39 #include "dwarf2/read.h"
40 #include "dwarf2/public.h"
42 #include "dwarf2/loc.h"
43 #include "dwarf2/frame-tailcall.h"
44 #include "gdbsupport/gdb_binary_search.h"
46 #include "gdbsupport/selftest.h"
47 #include "selftest-arch.h"
49 #include <unordered_map>
55 /* Call Frame Information (CFI). */
57 /* Common Information Entry (CIE). */
61 /* Computation Unit for this CIE. */
62 struct comp_unit
*unit
;
64 /* Offset into the .debug_frame section where this CIE was found.
65 Used to identify this CIE. */
68 /* Constant that is factored out of all advance location
70 ULONGEST code_alignment_factor
;
72 /* Constants that is factored out of all offset instructions. */
73 LONGEST data_alignment_factor
;
75 /* Return address column. */
76 ULONGEST return_address_register
;
78 /* Instruction sequence to initialize a register set. */
79 const gdb_byte
*initial_instructions
;
82 /* Saved augmentation, in case it's needed later. */
85 /* Encoding of addresses. */
88 /* Target address size in bytes. */
91 /* Target pointer size in bytes. */
94 /* True if a 'z' augmentation existed. */
95 unsigned char saw_z_augmentation
;
97 /* True if an 'S' augmentation existed. */
98 unsigned char signal_frame
;
100 /* The version recorded in the CIE. */
101 unsigned char version
;
103 /* The segment size. */
104 unsigned char segment_size
;
107 /* The CIE table is used to find CIEs during parsing, but then
108 discarded. It maps from the CIE's offset to the CIE. */
109 typedef std::unordered_map
<ULONGEST
, dwarf2_cie
*> dwarf2_cie_table
;
111 /* Frame Description Entry (FDE). */
115 /* CIE for this FDE. */
116 struct dwarf2_cie
*cie
;
118 /* First location associated with this FDE. */
119 CORE_ADDR initial_location
;
121 /* Number of bytes of program instructions described by this FDE. */
122 CORE_ADDR address_range
;
124 /* Instruction sequence. */
125 const gdb_byte
*instructions
;
128 /* True if this FDE is read from a .eh_frame instead of a .debug_frame
130 unsigned char eh_frame_p
;
133 typedef std::vector
<dwarf2_fde
*> dwarf2_fde_table
;
135 /* A minimal decoding of DWARF2 compilation units. We only decode
136 what's needed to get to the call frame information. */
140 comp_unit (struct objfile
*objf
)
145 /* Keep the bfd convenient. */
148 /* Pointer to the .debug_frame section loaded into memory. */
149 const gdb_byte
*dwarf_frame_buffer
= nullptr;
151 /* Length of the loaded .debug_frame section. */
152 bfd_size_type dwarf_frame_size
= 0;
154 /* Pointer to the .debug_frame section. */
155 asection
*dwarf_frame_section
= nullptr;
157 /* Base for DW_EH_PE_datarel encodings. */
160 /* Base for DW_EH_PE_textrel encodings. */
164 dwarf2_fde_table fde_table
;
166 /* Hold data used by this module. */
167 auto_obstack obstack
;
170 static struct dwarf2_fde
*dwarf2_frame_find_fde
171 (CORE_ADDR
*pc
, dwarf2_per_objfile
**out_per_objfile
);
173 static int dwarf2_frame_adjust_regnum (struct gdbarch
*gdbarch
, int regnum
,
176 static CORE_ADDR
read_encoded_value (struct comp_unit
*unit
, gdb_byte encoding
,
177 int ptr_len
, const gdb_byte
*buf
,
178 unsigned int *bytes_read_ptr
,
179 CORE_ADDR func_base
);
182 /* See dwarf2-frame.h. */
183 bool dwarf2_frame_unwinders_enabled_p
= true;
185 /* Store the length the expression for the CFA in the `cfa_reg' field,
186 which is unused in that case. */
187 #define cfa_exp_len cfa_reg
189 dwarf2_frame_state::dwarf2_frame_state (CORE_ADDR pc_
, struct dwarf2_cie
*cie
)
190 : pc (pc_
), data_align (cie
->data_alignment_factor
),
191 code_align (cie
->code_alignment_factor
),
192 retaddr_column (cie
->return_address_register
)
197 /* Helper functions for execute_stack_op. */
200 read_addr_from_reg (struct frame_info
*this_frame
, int reg
)
202 struct gdbarch
*gdbarch
= get_frame_arch (this_frame
);
203 int regnum
= dwarf_reg_to_regnum_or_error (gdbarch
, reg
);
205 return address_from_register (regnum
, this_frame
);
208 /* Execute the required actions for both the DW_CFA_restore and
209 DW_CFA_restore_extended instructions. */
211 dwarf2_restore_rule (struct gdbarch
*gdbarch
, ULONGEST reg_num
,
212 struct dwarf2_frame_state
*fs
, int eh_frame_p
)
216 reg
= dwarf2_frame_adjust_regnum (gdbarch
, reg_num
, eh_frame_p
);
217 fs
->regs
.alloc_regs (reg
+ 1);
219 /* Check if this register was explicitly initialized in the
220 CIE initial instructions. If not, default the rule to
222 if (reg
< fs
->initial
.reg
.size ())
223 fs
->regs
.reg
[reg
] = fs
->initial
.reg
[reg
];
225 fs
->regs
.reg
[reg
].how
= DWARF2_FRAME_REG_UNSPECIFIED
;
227 if (fs
->regs
.reg
[reg
].how
== DWARF2_FRAME_REG_UNSPECIFIED
)
229 int regnum
= dwarf_reg_to_regnum (gdbarch
, reg
);
232 incomplete CFI data; DW_CFA_restore unspecified\n\
233 register %s (#%d) at %s"),
234 gdbarch_register_name (gdbarch
, regnum
), regnum
,
235 paddress (gdbarch
, fs
->pc
));
239 class dwarf_expr_executor
: public dwarf_expr_context
243 dwarf_expr_executor (dwarf2_per_objfile
*per_objfile
)
244 : dwarf_expr_context (per_objfile
)
247 struct frame_info
*this_frame
;
249 CORE_ADDR
read_addr_from_reg (int reg
) override
251 return ::read_addr_from_reg (this_frame
, reg
);
254 struct value
*get_reg_value (struct type
*type
, int reg
) override
256 struct gdbarch
*gdbarch
= get_frame_arch (this_frame
);
257 int regnum
= dwarf_reg_to_regnum_or_error (gdbarch
, reg
);
259 return value_from_register (type
, regnum
, this_frame
);
262 void read_mem (gdb_byte
*buf
, CORE_ADDR addr
, size_t len
) override
264 read_memory (addr
, buf
, len
);
267 void get_frame_base (const gdb_byte
**start
, size_t *length
) override
269 invalid ("DW_OP_fbreg");
272 void push_dwarf_reg_entry_value (enum call_site_parameter_kind kind
,
273 union call_site_parameter_u kind_u
,
274 int deref_size
) override
276 invalid ("DW_OP_entry_value");
279 CORE_ADDR
get_object_address () override
281 invalid ("DW_OP_push_object_address");
284 CORE_ADDR
get_frame_cfa () override
286 invalid ("DW_OP_call_frame_cfa");
289 CORE_ADDR
get_tls_address (CORE_ADDR offset
) override
291 invalid ("DW_OP_form_tls_address");
294 void dwarf_call (cu_offset die_offset
) override
296 invalid ("DW_OP_call*");
299 struct value
*dwarf_variable_value (sect_offset sect_off
) override
301 invalid ("DW_OP_GNU_variable_value");
304 CORE_ADDR
get_addr_index (unsigned int index
) override
306 invalid ("DW_OP_addrx or DW_OP_GNU_addr_index");
311 void invalid (const char *op
) ATTRIBUTE_NORETURN
313 error (_("%s is invalid in this context"), op
);
318 execute_stack_op (const gdb_byte
*exp
, ULONGEST len
, int addr_size
,
319 struct frame_info
*this_frame
, CORE_ADDR initial
,
320 int initial_in_stack_memory
, dwarf2_per_objfile
*per_objfile
)
324 dwarf_expr_executor
ctx (per_objfile
);
325 scoped_value_mark free_values
;
327 ctx
.this_frame
= this_frame
;
328 ctx
.gdbarch
= get_frame_arch (this_frame
);
329 ctx
.addr_size
= addr_size
;
330 ctx
.ref_addr_size
= -1;
332 ctx
.push_address (initial
, initial_in_stack_memory
);
335 if (ctx
.location
== DWARF_VALUE_MEMORY
)
336 result
= ctx
.fetch_address (0);
337 else if (ctx
.location
== DWARF_VALUE_REGISTER
)
338 result
= ctx
.read_addr_from_reg (value_as_long (ctx
.fetch (0)));
341 /* This is actually invalid DWARF, but if we ever do run across
342 it somehow, we might as well support it. So, instead, report
343 it as unimplemented. */
345 Not implemented: computing unwound register using explicit value operator"));
352 /* Execute FDE program from INSN_PTR possibly up to INSN_END or up to inferior
353 PC. Modify FS state accordingly. Return current INSN_PTR where the
354 execution has stopped, one can resume it on the next call. */
356 static const gdb_byte
*
357 execute_cfa_program (struct dwarf2_fde
*fde
, const gdb_byte
*insn_ptr
,
358 const gdb_byte
*insn_end
, struct gdbarch
*gdbarch
,
359 CORE_ADDR pc
, struct dwarf2_frame_state
*fs
,
360 CORE_ADDR text_offset
)
362 int eh_frame_p
= fde
->eh_frame_p
;
363 unsigned int bytes_read
;
364 enum bfd_endian byte_order
= gdbarch_byte_order (gdbarch
);
366 while (insn_ptr
< insn_end
&& fs
->pc
<= pc
)
368 gdb_byte insn
= *insn_ptr
++;
372 if ((insn
& 0xc0) == DW_CFA_advance_loc
)
373 fs
->pc
+= (insn
& 0x3f) * fs
->code_align
;
374 else if ((insn
& 0xc0) == DW_CFA_offset
)
377 reg
= dwarf2_frame_adjust_regnum (gdbarch
, reg
, eh_frame_p
);
378 insn_ptr
= safe_read_uleb128 (insn_ptr
, insn_end
, &utmp
);
379 offset
= utmp
* fs
->data_align
;
380 fs
->regs
.alloc_regs (reg
+ 1);
381 fs
->regs
.reg
[reg
].how
= DWARF2_FRAME_REG_SAVED_OFFSET
;
382 fs
->regs
.reg
[reg
].loc
.offset
= offset
;
384 else if ((insn
& 0xc0) == DW_CFA_restore
)
387 dwarf2_restore_rule (gdbarch
, reg
, fs
, eh_frame_p
);
394 fs
->pc
= read_encoded_value (fde
->cie
->unit
, fde
->cie
->encoding
,
395 fde
->cie
->ptr_size
, insn_ptr
,
396 &bytes_read
, fde
->initial_location
);
397 /* Apply the text offset for relocatable objects. */
398 fs
->pc
+= text_offset
;
399 insn_ptr
+= bytes_read
;
402 case DW_CFA_advance_loc1
:
403 utmp
= extract_unsigned_integer (insn_ptr
, 1, byte_order
);
404 fs
->pc
+= utmp
* fs
->code_align
;
407 case DW_CFA_advance_loc2
:
408 utmp
= extract_unsigned_integer (insn_ptr
, 2, byte_order
);
409 fs
->pc
+= utmp
* fs
->code_align
;
412 case DW_CFA_advance_loc4
:
413 utmp
= extract_unsigned_integer (insn_ptr
, 4, byte_order
);
414 fs
->pc
+= utmp
* fs
->code_align
;
418 case DW_CFA_offset_extended
:
419 insn_ptr
= safe_read_uleb128 (insn_ptr
, insn_end
, ®
);
420 reg
= dwarf2_frame_adjust_regnum (gdbarch
, reg
, eh_frame_p
);
421 insn_ptr
= safe_read_uleb128 (insn_ptr
, insn_end
, &utmp
);
422 offset
= utmp
* fs
->data_align
;
423 fs
->regs
.alloc_regs (reg
+ 1);
424 fs
->regs
.reg
[reg
].how
= DWARF2_FRAME_REG_SAVED_OFFSET
;
425 fs
->regs
.reg
[reg
].loc
.offset
= offset
;
428 case DW_CFA_restore_extended
:
429 insn_ptr
= safe_read_uleb128 (insn_ptr
, insn_end
, ®
);
430 dwarf2_restore_rule (gdbarch
, reg
, fs
, eh_frame_p
);
433 case DW_CFA_undefined
:
434 insn_ptr
= safe_read_uleb128 (insn_ptr
, insn_end
, ®
);
435 reg
= dwarf2_frame_adjust_regnum (gdbarch
, reg
, eh_frame_p
);
436 fs
->regs
.alloc_regs (reg
+ 1);
437 fs
->regs
.reg
[reg
].how
= DWARF2_FRAME_REG_UNDEFINED
;
440 case DW_CFA_same_value
:
441 insn_ptr
= safe_read_uleb128 (insn_ptr
, insn_end
, ®
);
442 reg
= dwarf2_frame_adjust_regnum (gdbarch
, reg
, eh_frame_p
);
443 fs
->regs
.alloc_regs (reg
+ 1);
444 fs
->regs
.reg
[reg
].how
= DWARF2_FRAME_REG_SAME_VALUE
;
447 case DW_CFA_register
:
448 insn_ptr
= safe_read_uleb128 (insn_ptr
, insn_end
, ®
);
449 reg
= dwarf2_frame_adjust_regnum (gdbarch
, reg
, eh_frame_p
);
450 insn_ptr
= safe_read_uleb128 (insn_ptr
, insn_end
, &utmp
);
451 utmp
= dwarf2_frame_adjust_regnum (gdbarch
, utmp
, eh_frame_p
);
452 fs
->regs
.alloc_regs (reg
+ 1);
453 fs
->regs
.reg
[reg
].how
= DWARF2_FRAME_REG_SAVED_REG
;
454 fs
->regs
.reg
[reg
].loc
.reg
= utmp
;
457 case DW_CFA_remember_state
:
459 struct dwarf2_frame_state_reg_info
*new_rs
;
461 new_rs
= new dwarf2_frame_state_reg_info (fs
->regs
);
462 fs
->regs
.prev
= new_rs
;
466 case DW_CFA_restore_state
:
468 struct dwarf2_frame_state_reg_info
*old_rs
= fs
->regs
.prev
;
473 bad CFI data; mismatched DW_CFA_restore_state at %s"),
474 paddress (gdbarch
, fs
->pc
));
477 fs
->regs
= std::move (*old_rs
);
482 insn_ptr
= safe_read_uleb128 (insn_ptr
, insn_end
, ®
);
483 fs
->regs
.cfa_reg
= reg
;
484 insn_ptr
= safe_read_uleb128 (insn_ptr
, insn_end
, &utmp
);
486 if (fs
->armcc_cfa_offsets_sf
)
487 utmp
*= fs
->data_align
;
489 fs
->regs
.cfa_offset
= utmp
;
490 fs
->regs
.cfa_how
= CFA_REG_OFFSET
;
493 case DW_CFA_def_cfa_register
:
494 insn_ptr
= safe_read_uleb128 (insn_ptr
, insn_end
, ®
);
495 fs
->regs
.cfa_reg
= dwarf2_frame_adjust_regnum (gdbarch
, reg
,
497 fs
->regs
.cfa_how
= CFA_REG_OFFSET
;
500 case DW_CFA_def_cfa_offset
:
501 insn_ptr
= safe_read_uleb128 (insn_ptr
, insn_end
, &utmp
);
503 if (fs
->armcc_cfa_offsets_sf
)
504 utmp
*= fs
->data_align
;
506 fs
->regs
.cfa_offset
= utmp
;
507 /* cfa_how deliberately not set. */
513 case DW_CFA_def_cfa_expression
:
514 insn_ptr
= safe_read_uleb128 (insn_ptr
, insn_end
, &utmp
);
515 fs
->regs
.cfa_exp_len
= utmp
;
516 fs
->regs
.cfa_exp
= insn_ptr
;
517 fs
->regs
.cfa_how
= CFA_EXP
;
518 insn_ptr
+= fs
->regs
.cfa_exp_len
;
521 case DW_CFA_expression
:
522 insn_ptr
= safe_read_uleb128 (insn_ptr
, insn_end
, ®
);
523 reg
= dwarf2_frame_adjust_regnum (gdbarch
, reg
, eh_frame_p
);
524 fs
->regs
.alloc_regs (reg
+ 1);
525 insn_ptr
= safe_read_uleb128 (insn_ptr
, insn_end
, &utmp
);
526 fs
->regs
.reg
[reg
].loc
.exp
.start
= insn_ptr
;
527 fs
->regs
.reg
[reg
].loc
.exp
.len
= utmp
;
528 fs
->regs
.reg
[reg
].how
= DWARF2_FRAME_REG_SAVED_EXP
;
532 case DW_CFA_offset_extended_sf
:
533 insn_ptr
= safe_read_uleb128 (insn_ptr
, insn_end
, ®
);
534 reg
= dwarf2_frame_adjust_regnum (gdbarch
, reg
, eh_frame_p
);
535 insn_ptr
= safe_read_sleb128 (insn_ptr
, insn_end
, &offset
);
536 offset
*= fs
->data_align
;
537 fs
->regs
.alloc_regs (reg
+ 1);
538 fs
->regs
.reg
[reg
].how
= DWARF2_FRAME_REG_SAVED_OFFSET
;
539 fs
->regs
.reg
[reg
].loc
.offset
= offset
;
542 case DW_CFA_val_offset
:
543 insn_ptr
= safe_read_uleb128 (insn_ptr
, insn_end
, ®
);
544 fs
->regs
.alloc_regs (reg
+ 1);
545 insn_ptr
= safe_read_uleb128 (insn_ptr
, insn_end
, &utmp
);
546 offset
= utmp
* fs
->data_align
;
547 fs
->regs
.reg
[reg
].how
= DWARF2_FRAME_REG_SAVED_VAL_OFFSET
;
548 fs
->regs
.reg
[reg
].loc
.offset
= offset
;
551 case DW_CFA_val_offset_sf
:
552 insn_ptr
= safe_read_uleb128 (insn_ptr
, insn_end
, ®
);
553 fs
->regs
.alloc_regs (reg
+ 1);
554 insn_ptr
= safe_read_sleb128 (insn_ptr
, insn_end
, &offset
);
555 offset
*= fs
->data_align
;
556 fs
->regs
.reg
[reg
].how
= DWARF2_FRAME_REG_SAVED_VAL_OFFSET
;
557 fs
->regs
.reg
[reg
].loc
.offset
= offset
;
560 case DW_CFA_val_expression
:
561 insn_ptr
= safe_read_uleb128 (insn_ptr
, insn_end
, ®
);
562 fs
->regs
.alloc_regs (reg
+ 1);
563 insn_ptr
= safe_read_uleb128 (insn_ptr
, insn_end
, &utmp
);
564 fs
->regs
.reg
[reg
].loc
.exp
.start
= insn_ptr
;
565 fs
->regs
.reg
[reg
].loc
.exp
.len
= utmp
;
566 fs
->regs
.reg
[reg
].how
= DWARF2_FRAME_REG_SAVED_VAL_EXP
;
570 case DW_CFA_def_cfa_sf
:
571 insn_ptr
= safe_read_uleb128 (insn_ptr
, insn_end
, ®
);
572 fs
->regs
.cfa_reg
= dwarf2_frame_adjust_regnum (gdbarch
, reg
,
574 insn_ptr
= safe_read_sleb128 (insn_ptr
, insn_end
, &offset
);
575 fs
->regs
.cfa_offset
= offset
* fs
->data_align
;
576 fs
->regs
.cfa_how
= CFA_REG_OFFSET
;
579 case DW_CFA_def_cfa_offset_sf
:
580 insn_ptr
= safe_read_sleb128 (insn_ptr
, insn_end
, &offset
);
581 fs
->regs
.cfa_offset
= offset
* fs
->data_align
;
582 /* cfa_how deliberately not set. */
585 case DW_CFA_GNU_args_size
:
587 insn_ptr
= safe_read_uleb128 (insn_ptr
, insn_end
, &utmp
);
590 case DW_CFA_GNU_negative_offset_extended
:
591 insn_ptr
= safe_read_uleb128 (insn_ptr
, insn_end
, ®
);
592 reg
= dwarf2_frame_adjust_regnum (gdbarch
, reg
, eh_frame_p
);
593 insn_ptr
= safe_read_uleb128 (insn_ptr
, insn_end
, &utmp
);
594 offset
= utmp
* fs
->data_align
;
595 fs
->regs
.alloc_regs (reg
+ 1);
596 fs
->regs
.reg
[reg
].how
= DWARF2_FRAME_REG_SAVED_OFFSET
;
597 fs
->regs
.reg
[reg
].loc
.offset
= -offset
;
601 if (insn
>= DW_CFA_lo_user
&& insn
<= DW_CFA_hi_user
)
603 /* Handle vendor-specific CFI for different architectures. */
604 if (!gdbarch_execute_dwarf_cfa_vendor_op (gdbarch
, insn
, fs
))
605 error (_("Call Frame Instruction op %d in vendor extension "
606 "space is not handled on this architecture."),
610 internal_error (__FILE__
, __LINE__
,
611 _("Unknown CFI encountered."));
616 if (fs
->initial
.reg
.empty ())
618 /* Don't allow remember/restore between CIE and FDE programs. */
619 delete fs
->regs
.prev
;
620 fs
->regs
.prev
= NULL
;
628 namespace selftests
{
630 /* Unit test to function execute_cfa_program. */
633 execute_cfa_program_test (struct gdbarch
*gdbarch
)
635 struct dwarf2_fde fde
;
636 struct dwarf2_cie cie
;
638 memset (&fde
, 0, sizeof fde
);
639 memset (&cie
, 0, sizeof cie
);
641 cie
.data_alignment_factor
= -4;
642 cie
.code_alignment_factor
= 2;
645 dwarf2_frame_state
fs (0, fde
.cie
);
649 DW_CFA_def_cfa
, 1, 4, /* DW_CFA_def_cfa: r1 ofs 4 */
650 DW_CFA_offset
| 0x2, 1, /* DW_CFA_offset: r2 at cfa-4 */
651 DW_CFA_remember_state
,
652 DW_CFA_restore_state
,
655 const gdb_byte
*insn_end
= insns
+ sizeof (insns
);
656 const gdb_byte
*out
= execute_cfa_program (&fde
, insns
, insn_end
, gdbarch
,
659 SELF_CHECK (out
== insn_end
);
660 SELF_CHECK (fs
.pc
== 0);
662 /* The instructions above only use r1 and r2, but the register numbers
663 used are adjusted by dwarf2_frame_adjust_regnum. */
664 auto r1
= dwarf2_frame_adjust_regnum (gdbarch
, 1, fde
.eh_frame_p
);
665 auto r2
= dwarf2_frame_adjust_regnum (gdbarch
, 2, fde
.eh_frame_p
);
667 SELF_CHECK (fs
.regs
.reg
.size () == (std::max (r1
, r2
) + 1));
669 SELF_CHECK (fs
.regs
.reg
[r2
].how
== DWARF2_FRAME_REG_SAVED_OFFSET
);
670 SELF_CHECK (fs
.regs
.reg
[r2
].loc
.offset
== -4);
672 for (auto i
= 0; i
< fs
.regs
.reg
.size (); i
++)
674 SELF_CHECK (fs
.regs
.reg
[i
].how
== DWARF2_FRAME_REG_UNSPECIFIED
);
676 SELF_CHECK (fs
.regs
.cfa_reg
== 1);
677 SELF_CHECK (fs
.regs
.cfa_offset
== 4);
678 SELF_CHECK (fs
.regs
.cfa_how
== CFA_REG_OFFSET
);
679 SELF_CHECK (fs
.regs
.cfa_exp
== NULL
);
680 SELF_CHECK (fs
.regs
.prev
== NULL
);
683 } // namespace selftests
684 #endif /* GDB_SELF_TEST */
688 /* Architecture-specific operations. */
690 /* Per-architecture data key. */
691 static struct gdbarch_data
*dwarf2_frame_data
;
693 struct dwarf2_frame_ops
695 /* Pre-initialize the register state REG for register REGNUM. */
696 void (*init_reg
) (struct gdbarch
*, int, struct dwarf2_frame_state_reg
*,
697 struct frame_info
*);
699 /* Check whether the THIS_FRAME is a signal trampoline. */
700 int (*signal_frame_p
) (struct gdbarch
*, struct frame_info
*);
702 /* Convert .eh_frame register number to DWARF register number, or
703 adjust .debug_frame register number. */
704 int (*adjust_regnum
) (struct gdbarch
*, int, int);
707 /* Default architecture-specific register state initialization
711 dwarf2_frame_default_init_reg (struct gdbarch
*gdbarch
, int regnum
,
712 struct dwarf2_frame_state_reg
*reg
,
713 struct frame_info
*this_frame
)
715 /* If we have a register that acts as a program counter, mark it as
716 a destination for the return address. If we have a register that
717 serves as the stack pointer, arrange for it to be filled with the
718 call frame address (CFA). The other registers are marked as
721 We copy the return address to the program counter, since many
722 parts in GDB assume that it is possible to get the return address
723 by unwinding the program counter register. However, on ISA's
724 with a dedicated return address register, the CFI usually only
725 contains information to unwind that return address register.
727 The reason we're treating the stack pointer special here is
728 because in many cases GCC doesn't emit CFI for the stack pointer
729 and implicitly assumes that it is equal to the CFA. This makes
730 some sense since the DWARF specification (version 3, draft 8,
733 "Typically, the CFA is defined to be the value of the stack
734 pointer at the call site in the previous frame (which may be
735 different from its value on entry to the current frame)."
737 However, this isn't true for all platforms supported by GCC
738 (e.g. IBM S/390 and zSeries). Those architectures should provide
739 their own architecture-specific initialization function. */
741 if (regnum
== gdbarch_pc_regnum (gdbarch
))
742 reg
->how
= DWARF2_FRAME_REG_RA
;
743 else if (regnum
== gdbarch_sp_regnum (gdbarch
))
744 reg
->how
= DWARF2_FRAME_REG_CFA
;
747 /* Return a default for the architecture-specific operations. */
750 dwarf2_frame_init (struct obstack
*obstack
)
752 struct dwarf2_frame_ops
*ops
;
754 ops
= OBSTACK_ZALLOC (obstack
, struct dwarf2_frame_ops
);
755 ops
->init_reg
= dwarf2_frame_default_init_reg
;
759 /* Set the architecture-specific register state initialization
760 function for GDBARCH to INIT_REG. */
763 dwarf2_frame_set_init_reg (struct gdbarch
*gdbarch
,
764 void (*init_reg
) (struct gdbarch
*, int,
765 struct dwarf2_frame_state_reg
*,
766 struct frame_info
*))
768 struct dwarf2_frame_ops
*ops
769 = (struct dwarf2_frame_ops
*) gdbarch_data (gdbarch
, dwarf2_frame_data
);
771 ops
->init_reg
= init_reg
;
774 /* Pre-initialize the register state REG for register REGNUM. */
777 dwarf2_frame_init_reg (struct gdbarch
*gdbarch
, int regnum
,
778 struct dwarf2_frame_state_reg
*reg
,
779 struct frame_info
*this_frame
)
781 struct dwarf2_frame_ops
*ops
782 = (struct dwarf2_frame_ops
*) gdbarch_data (gdbarch
, dwarf2_frame_data
);
784 ops
->init_reg (gdbarch
, regnum
, reg
, this_frame
);
787 /* Set the architecture-specific signal trampoline recognition
788 function for GDBARCH to SIGNAL_FRAME_P. */
791 dwarf2_frame_set_signal_frame_p (struct gdbarch
*gdbarch
,
792 int (*signal_frame_p
) (struct gdbarch
*,
793 struct frame_info
*))
795 struct dwarf2_frame_ops
*ops
796 = (struct dwarf2_frame_ops
*) gdbarch_data (gdbarch
, dwarf2_frame_data
);
798 ops
->signal_frame_p
= signal_frame_p
;
801 /* Query the architecture-specific signal frame recognizer for
805 dwarf2_frame_signal_frame_p (struct gdbarch
*gdbarch
,
806 struct frame_info
*this_frame
)
808 struct dwarf2_frame_ops
*ops
809 = (struct dwarf2_frame_ops
*) gdbarch_data (gdbarch
, dwarf2_frame_data
);
811 if (ops
->signal_frame_p
== NULL
)
813 return ops
->signal_frame_p (gdbarch
, this_frame
);
816 /* Set the architecture-specific adjustment of .eh_frame and .debug_frame
820 dwarf2_frame_set_adjust_regnum (struct gdbarch
*gdbarch
,
821 int (*adjust_regnum
) (struct gdbarch
*,
824 struct dwarf2_frame_ops
*ops
825 = (struct dwarf2_frame_ops
*) gdbarch_data (gdbarch
, dwarf2_frame_data
);
827 ops
->adjust_regnum
= adjust_regnum
;
830 /* Translate a .eh_frame register to DWARF register, or adjust a .debug_frame
834 dwarf2_frame_adjust_regnum (struct gdbarch
*gdbarch
,
835 int regnum
, int eh_frame_p
)
837 struct dwarf2_frame_ops
*ops
838 = (struct dwarf2_frame_ops
*) gdbarch_data (gdbarch
, dwarf2_frame_data
);
840 if (ops
->adjust_regnum
== NULL
)
842 return ops
->adjust_regnum (gdbarch
, regnum
, eh_frame_p
);
846 dwarf2_frame_find_quirks (struct dwarf2_frame_state
*fs
,
847 struct dwarf2_fde
*fde
)
849 struct compunit_symtab
*cust
;
851 cust
= find_pc_compunit_symtab (fs
->pc
);
855 if (producer_is_realview (COMPUNIT_PRODUCER (cust
)))
857 if (fde
->cie
->version
== 1)
858 fs
->armcc_cfa_offsets_sf
= 1;
860 if (fde
->cie
->version
== 1)
861 fs
->armcc_cfa_offsets_reversed
= 1;
863 /* The reversed offset problem is present in some compilers
864 using DWARF3, but it was eventually fixed. Check the ARM
865 defined augmentations, which are in the format "armcc" followed
866 by a list of one-character options. The "+" option means
867 this problem is fixed (no quirk needed). If the armcc
868 augmentation is missing, the quirk is needed. */
869 if (fde
->cie
->version
== 3
870 && (!startswith (fde
->cie
->augmentation
, "armcc")
871 || strchr (fde
->cie
->augmentation
+ 5, '+') == NULL
))
872 fs
->armcc_cfa_offsets_reversed
= 1;
879 /* See dwarf2-frame.h. */
882 dwarf2_fetch_cfa_info (struct gdbarch
*gdbarch
, CORE_ADDR pc
,
883 struct dwarf2_per_cu_data
*data
,
884 int *regnum_out
, LONGEST
*offset_out
,
885 CORE_ADDR
*text_offset_out
,
886 const gdb_byte
**cfa_start_out
,
887 const gdb_byte
**cfa_end_out
)
889 struct dwarf2_fde
*fde
;
890 dwarf2_per_objfile
*per_objfile
;
893 /* Find the correct FDE. */
894 fde
= dwarf2_frame_find_fde (&pc1
, &per_objfile
);
896 error (_("Could not compute CFA; needed to translate this expression"));
898 gdb_assert (per_objfile
!= nullptr);
900 dwarf2_frame_state
fs (pc1
, fde
->cie
);
902 /* Check for "quirks" - known bugs in producers. */
903 dwarf2_frame_find_quirks (&fs
, fde
);
905 /* First decode all the insns in the CIE. */
906 execute_cfa_program (fde
, fde
->cie
->initial_instructions
,
907 fde
->cie
->end
, gdbarch
, pc
, &fs
,
908 per_objfile
->objfile
->text_section_offset ());
910 /* Save the initialized register set. */
911 fs
.initial
= fs
.regs
;
913 /* Then decode the insns in the FDE up to our target PC. */
914 execute_cfa_program (fde
, fde
->instructions
, fde
->end
, gdbarch
, pc
, &fs
,
915 per_objfile
->objfile
->text_section_offset ());
917 /* Calculate the CFA. */
918 switch (fs
.regs
.cfa_how
)
922 int regnum
= dwarf_reg_to_regnum_or_error (gdbarch
, fs
.regs
.cfa_reg
);
924 *regnum_out
= regnum
;
925 if (fs
.armcc_cfa_offsets_reversed
)
926 *offset_out
= -fs
.regs
.cfa_offset
;
928 *offset_out
= fs
.regs
.cfa_offset
;
933 *text_offset_out
= per_objfile
->objfile
->text_section_offset ();
934 *cfa_start_out
= fs
.regs
.cfa_exp
;
935 *cfa_end_out
= fs
.regs
.cfa_exp
+ fs
.regs
.cfa_exp_len
;
939 internal_error (__FILE__
, __LINE__
, _("Unknown CFA rule."));
944 struct dwarf2_frame_cache
946 /* DWARF Call Frame Address. */
949 /* Set if the return address column was marked as unavailable
950 (required non-collected memory or registers to compute). */
951 int unavailable_retaddr
;
953 /* Set if the return address column was marked as undefined. */
954 int undefined_retaddr
;
956 /* Saved registers, indexed by GDB register number, not by DWARF
958 struct dwarf2_frame_state_reg
*reg
;
960 /* Return address register. */
961 struct dwarf2_frame_state_reg retaddr_reg
;
963 /* Target address size in bytes. */
966 /* The dwarf2_per_objfile from which this frame description came. */
967 dwarf2_per_objfile
*per_objfile
;
969 /* If not NULL then this frame is the bottom frame of a TAILCALL_FRAME
970 sequence. If NULL then it is a normal case with no TAILCALL_FRAME
971 involved. Non-bottom frames of a virtual tail call frames chain use
972 dwarf2_tailcall_frame_unwind unwinder so this field does not apply for
974 void *tailcall_cache
;
977 static struct dwarf2_frame_cache
*
978 dwarf2_frame_cache (struct frame_info
*this_frame
, void **this_cache
)
980 struct gdbarch
*gdbarch
= get_frame_arch (this_frame
);
981 const int num_regs
= gdbarch_num_cooked_regs (gdbarch
);
982 struct dwarf2_frame_cache
*cache
;
983 struct dwarf2_fde
*fde
;
985 const gdb_byte
*instr
;
988 return (struct dwarf2_frame_cache
*) *this_cache
;
990 /* Allocate a new cache. */
991 cache
= FRAME_OBSTACK_ZALLOC (struct dwarf2_frame_cache
);
992 cache
->reg
= FRAME_OBSTACK_CALLOC (num_regs
, struct dwarf2_frame_state_reg
);
997 Note that if the next frame is never supposed to return (i.e. a call
998 to abort), the compiler might optimize away the instruction at
999 its return address. As a result the return address will
1000 point at some random instruction, and the CFI for that
1001 instruction is probably worthless to us. GCC's unwinder solves
1002 this problem by substracting 1 from the return address to get an
1003 address in the middle of a presumed call instruction (or the
1004 instruction in the associated delay slot). This should only be
1005 done for "normal" frames and not for resume-type frames (signal
1006 handlers, sentinel frames, dummy frames). The function
1007 get_frame_address_in_block does just this. It's not clear how
1008 reliable the method is though; there is the potential for the
1009 register state pre-call being different to that on return. */
1010 CORE_ADDR pc1
= get_frame_address_in_block (this_frame
);
1012 /* Find the correct FDE. */
1013 fde
= dwarf2_frame_find_fde (&pc1
, &cache
->per_objfile
);
1014 gdb_assert (fde
!= NULL
);
1015 gdb_assert (cache
->per_objfile
!= nullptr);
1017 /* Allocate and initialize the frame state. */
1018 struct dwarf2_frame_state
fs (pc1
, fde
->cie
);
1020 cache
->addr_size
= fde
->cie
->addr_size
;
1022 /* Check for "quirks" - known bugs in producers. */
1023 dwarf2_frame_find_quirks (&fs
, fde
);
1025 /* First decode all the insns in the CIE. */
1026 execute_cfa_program (fde
, fde
->cie
->initial_instructions
,
1027 fde
->cie
->end
, gdbarch
,
1028 get_frame_address_in_block (this_frame
), &fs
,
1029 cache
->per_objfile
->objfile
->text_section_offset ());
1031 /* Save the initialized register set. */
1032 fs
.initial
= fs
.regs
;
1034 /* Fetching the entry pc for THIS_FRAME won't necessarily result
1035 in an address that's within the range of FDE locations. This
1036 is due to the possibility of the function occupying non-contiguous
1038 LONGEST entry_cfa_sp_offset
;
1039 int entry_cfa_sp_offset_p
= 0;
1040 if (get_frame_func_if_available (this_frame
, &entry_pc
)
1041 && fde
->initial_location
<= entry_pc
1042 && entry_pc
< fde
->initial_location
+ fde
->address_range
)
1044 /* Decode the insns in the FDE up to the entry PC. */
1045 instr
= execute_cfa_program
1046 (fde
, fde
->instructions
, fde
->end
, gdbarch
, entry_pc
, &fs
,
1047 cache
->per_objfile
->objfile
->text_section_offset ());
1049 if (fs
.regs
.cfa_how
== CFA_REG_OFFSET
1050 && (dwarf_reg_to_regnum (gdbarch
, fs
.regs
.cfa_reg
)
1051 == gdbarch_sp_regnum (gdbarch
)))
1053 entry_cfa_sp_offset
= fs
.regs
.cfa_offset
;
1054 entry_cfa_sp_offset_p
= 1;
1058 instr
= fde
->instructions
;
1060 /* Then decode the insns in the FDE up to our target PC. */
1061 execute_cfa_program (fde
, instr
, fde
->end
, gdbarch
,
1062 get_frame_address_in_block (this_frame
), &fs
,
1063 cache
->per_objfile
->objfile
->text_section_offset ());
1067 /* Calculate the CFA. */
1068 switch (fs
.regs
.cfa_how
)
1070 case CFA_REG_OFFSET
:
1071 cache
->cfa
= read_addr_from_reg (this_frame
, fs
.regs
.cfa_reg
);
1072 if (fs
.armcc_cfa_offsets_reversed
)
1073 cache
->cfa
-= fs
.regs
.cfa_offset
;
1075 cache
->cfa
+= fs
.regs
.cfa_offset
;
1080 execute_stack_op (fs
.regs
.cfa_exp
, fs
.regs
.cfa_exp_len
,
1081 cache
->addr_size
, this_frame
, 0, 0,
1082 cache
->per_objfile
);
1086 internal_error (__FILE__
, __LINE__
, _("Unknown CFA rule."));
1089 catch (const gdb_exception_error
&ex
)
1091 if (ex
.error
== NOT_AVAILABLE_ERROR
)
1093 cache
->unavailable_retaddr
= 1;
1100 /* Initialize the register state. */
1104 for (regnum
= 0; regnum
< num_regs
; regnum
++)
1105 dwarf2_frame_init_reg (gdbarch
, regnum
, &cache
->reg
[regnum
], this_frame
);
1108 /* Go through the DWARF2 CFI generated table and save its register
1109 location information in the cache. Note that we don't skip the
1110 return address column; it's perfectly all right for it to
1111 correspond to a real register. */
1113 int column
; /* CFI speak for "register number". */
1115 for (column
= 0; column
< fs
.regs
.reg
.size (); column
++)
1117 /* Use the GDB register number as the destination index. */
1118 int regnum
= dwarf_reg_to_regnum (gdbarch
, column
);
1120 /* Protect against a target returning a bad register. */
1121 if (regnum
< 0 || regnum
>= num_regs
)
1124 /* NOTE: cagney/2003-09-05: CFI should specify the disposition
1125 of all debug info registers. If it doesn't, complain (but
1126 not too loudly). It turns out that GCC assumes that an
1127 unspecified register implies "same value" when CFI (draft
1128 7) specifies nothing at all. Such a register could equally
1129 be interpreted as "undefined". Also note that this check
1130 isn't sufficient; it only checks that all registers in the
1131 range [0 .. max column] are specified, and won't detect
1132 problems when a debug info register falls outside of the
1133 table. We need a way of iterating through all the valid
1134 DWARF2 register numbers. */
1135 if (fs
.regs
.reg
[column
].how
== DWARF2_FRAME_REG_UNSPECIFIED
)
1137 if (cache
->reg
[regnum
].how
== DWARF2_FRAME_REG_UNSPECIFIED
)
1139 incomplete CFI data; unspecified registers (e.g., %s) at %s"),
1140 gdbarch_register_name (gdbarch
, regnum
),
1141 paddress (gdbarch
, fs
.pc
));
1144 cache
->reg
[regnum
] = fs
.regs
.reg
[column
];
1148 /* Eliminate any DWARF2_FRAME_REG_RA rules, and save the information
1149 we need for evaluating DWARF2_FRAME_REG_RA_OFFSET rules. */
1153 for (regnum
= 0; regnum
< num_regs
; regnum
++)
1155 if (cache
->reg
[regnum
].how
== DWARF2_FRAME_REG_RA
1156 || cache
->reg
[regnum
].how
== DWARF2_FRAME_REG_RA_OFFSET
)
1158 const std::vector
<struct dwarf2_frame_state_reg
> ®s
1160 ULONGEST retaddr_column
= fs
.retaddr_column
;
1162 /* It seems rather bizarre to specify an "empty" column as
1163 the return adress column. However, this is exactly
1164 what GCC does on some targets. It turns out that GCC
1165 assumes that the return address can be found in the
1166 register corresponding to the return address column.
1167 Incidentally, that's how we should treat a return
1168 address column specifying "same value" too. */
1169 if (fs
.retaddr_column
< fs
.regs
.reg
.size ()
1170 && regs
[retaddr_column
].how
!= DWARF2_FRAME_REG_UNSPECIFIED
1171 && regs
[retaddr_column
].how
!= DWARF2_FRAME_REG_SAME_VALUE
)
1173 if (cache
->reg
[regnum
].how
== DWARF2_FRAME_REG_RA
)
1174 cache
->reg
[regnum
] = regs
[retaddr_column
];
1176 cache
->retaddr_reg
= regs
[retaddr_column
];
1180 if (cache
->reg
[regnum
].how
== DWARF2_FRAME_REG_RA
)
1182 cache
->reg
[regnum
].loc
.reg
= fs
.retaddr_column
;
1183 cache
->reg
[regnum
].how
= DWARF2_FRAME_REG_SAVED_REG
;
1187 cache
->retaddr_reg
.loc
.reg
= fs
.retaddr_column
;
1188 cache
->retaddr_reg
.how
= DWARF2_FRAME_REG_SAVED_REG
;
1195 if (fs
.retaddr_column
< fs
.regs
.reg
.size ()
1196 && fs
.regs
.reg
[fs
.retaddr_column
].how
== DWARF2_FRAME_REG_UNDEFINED
)
1197 cache
->undefined_retaddr
= 1;
1199 dwarf2_tailcall_sniffer_first (this_frame
, &cache
->tailcall_cache
,
1200 (entry_cfa_sp_offset_p
1201 ? &entry_cfa_sp_offset
: NULL
));
1206 static enum unwind_stop_reason
1207 dwarf2_frame_unwind_stop_reason (struct frame_info
*this_frame
,
1210 struct dwarf2_frame_cache
*cache
1211 = dwarf2_frame_cache (this_frame
, this_cache
);
1213 if (cache
->unavailable_retaddr
)
1214 return UNWIND_UNAVAILABLE
;
1216 if (cache
->undefined_retaddr
)
1217 return UNWIND_OUTERMOST
;
1219 return UNWIND_NO_REASON
;
1223 dwarf2_frame_this_id (struct frame_info
*this_frame
, void **this_cache
,
1224 struct frame_id
*this_id
)
1226 struct dwarf2_frame_cache
*cache
=
1227 dwarf2_frame_cache (this_frame
, this_cache
);
1229 if (cache
->unavailable_retaddr
)
1230 (*this_id
) = frame_id_build_unavailable_stack (get_frame_func (this_frame
));
1231 else if (cache
->undefined_retaddr
)
1234 (*this_id
) = frame_id_build (cache
->cfa
, get_frame_func (this_frame
));
1237 static struct value
*
1238 dwarf2_frame_prev_register (struct frame_info
*this_frame
, void **this_cache
,
1241 struct gdbarch
*gdbarch
= get_frame_arch (this_frame
);
1242 struct dwarf2_frame_cache
*cache
=
1243 dwarf2_frame_cache (this_frame
, this_cache
);
1247 /* Non-bottom frames of a virtual tail call frames chain use
1248 dwarf2_tailcall_frame_unwind unwinder so this code does not apply for
1249 them. If dwarf2_tailcall_prev_register_first does not have specific value
1250 unwind the register, tail call frames are assumed to have the register set
1251 of the top caller. */
1252 if (cache
->tailcall_cache
)
1256 val
= dwarf2_tailcall_prev_register_first (this_frame
,
1257 &cache
->tailcall_cache
,
1263 switch (cache
->reg
[regnum
].how
)
1265 case DWARF2_FRAME_REG_UNDEFINED
:
1266 /* If CFI explicitly specified that the value isn't defined,
1267 mark it as optimized away; the value isn't available. */
1268 return frame_unwind_got_optimized (this_frame
, regnum
);
1270 case DWARF2_FRAME_REG_SAVED_OFFSET
:
1271 addr
= cache
->cfa
+ cache
->reg
[regnum
].loc
.offset
;
1272 return frame_unwind_got_memory (this_frame
, regnum
, addr
);
1274 case DWARF2_FRAME_REG_SAVED_REG
:
1275 realnum
= dwarf_reg_to_regnum_or_error
1276 (gdbarch
, cache
->reg
[regnum
].loc
.reg
);
1277 return frame_unwind_got_register (this_frame
, regnum
, realnum
);
1279 case DWARF2_FRAME_REG_SAVED_EXP
:
1280 addr
= execute_stack_op (cache
->reg
[regnum
].loc
.exp
.start
,
1281 cache
->reg
[regnum
].loc
.exp
.len
,
1283 this_frame
, cache
->cfa
, 1,
1284 cache
->per_objfile
);
1285 return frame_unwind_got_memory (this_frame
, regnum
, addr
);
1287 case DWARF2_FRAME_REG_SAVED_VAL_OFFSET
:
1288 addr
= cache
->cfa
+ cache
->reg
[regnum
].loc
.offset
;
1289 return frame_unwind_got_constant (this_frame
, regnum
, addr
);
1291 case DWARF2_FRAME_REG_SAVED_VAL_EXP
:
1292 addr
= execute_stack_op (cache
->reg
[regnum
].loc
.exp
.start
,
1293 cache
->reg
[regnum
].loc
.exp
.len
,
1295 this_frame
, cache
->cfa
, 1,
1296 cache
->per_objfile
);
1297 return frame_unwind_got_constant (this_frame
, regnum
, addr
);
1299 case DWARF2_FRAME_REG_UNSPECIFIED
:
1300 /* GCC, in its infinite wisdom decided to not provide unwind
1301 information for registers that are "same value". Since
1302 DWARF2 (3 draft 7) doesn't define such behavior, said
1303 registers are actually undefined (which is different to CFI
1304 "undefined"). Code above issues a complaint about this.
1305 Here just fudge the books, assume GCC, and that the value is
1306 more inner on the stack. */
1307 return frame_unwind_got_register (this_frame
, regnum
, regnum
);
1309 case DWARF2_FRAME_REG_SAME_VALUE
:
1310 return frame_unwind_got_register (this_frame
, regnum
, regnum
);
1312 case DWARF2_FRAME_REG_CFA
:
1313 return frame_unwind_got_address (this_frame
, regnum
, cache
->cfa
);
1315 case DWARF2_FRAME_REG_CFA_OFFSET
:
1316 addr
= cache
->cfa
+ cache
->reg
[regnum
].loc
.offset
;
1317 return frame_unwind_got_address (this_frame
, regnum
, addr
);
1319 case DWARF2_FRAME_REG_RA_OFFSET
:
1320 addr
= cache
->reg
[regnum
].loc
.offset
;
1321 regnum
= dwarf_reg_to_regnum_or_error
1322 (gdbarch
, cache
->retaddr_reg
.loc
.reg
);
1323 addr
+= get_frame_register_unsigned (this_frame
, regnum
);
1324 return frame_unwind_got_address (this_frame
, regnum
, addr
);
1326 case DWARF2_FRAME_REG_FN
:
1327 return cache
->reg
[regnum
].loc
.fn (this_frame
, this_cache
, regnum
);
1330 internal_error (__FILE__
, __LINE__
, _("Unknown register rule."));
1334 /* Proxy for tailcall_frame_dealloc_cache for bottom frame of a virtual tail
1335 call frames chain. */
1338 dwarf2_frame_dealloc_cache (struct frame_info
*self
, void *this_cache
)
1340 struct dwarf2_frame_cache
*cache
= dwarf2_frame_cache (self
, &this_cache
);
1342 if (cache
->tailcall_cache
)
1343 dwarf2_tailcall_frame_unwind
.dealloc_cache (self
, cache
->tailcall_cache
);
1347 dwarf2_frame_sniffer (const struct frame_unwind
*self
,
1348 struct frame_info
*this_frame
, void **this_cache
)
1350 if (!dwarf2_frame_unwinders_enabled_p
)
1353 /* Grab an address that is guaranteed to reside somewhere within the
1354 function. get_frame_pc(), with a no-return next function, can
1355 end up returning something past the end of this function's body.
1356 If the frame we're sniffing for is a signal frame whose start
1357 address is placed on the stack by the OS, its FDE must
1358 extend one byte before its start address or we could potentially
1359 select the FDE of the previous function. */
1360 CORE_ADDR block_addr
= get_frame_address_in_block (this_frame
);
1361 struct dwarf2_fde
*fde
= dwarf2_frame_find_fde (&block_addr
, NULL
);
1366 /* On some targets, signal trampolines may have unwind information.
1367 We need to recognize them so that we set the frame type
1370 if (fde
->cie
->signal_frame
1371 || dwarf2_frame_signal_frame_p (get_frame_arch (this_frame
),
1373 return self
->type
== SIGTRAMP_FRAME
;
1375 if (self
->type
!= NORMAL_FRAME
)
1381 static const struct frame_unwind dwarf2_frame_unwind
=
1384 dwarf2_frame_unwind_stop_reason
,
1385 dwarf2_frame_this_id
,
1386 dwarf2_frame_prev_register
,
1388 dwarf2_frame_sniffer
,
1389 dwarf2_frame_dealloc_cache
1392 static const struct frame_unwind dwarf2_signal_frame_unwind
=
1395 dwarf2_frame_unwind_stop_reason
,
1396 dwarf2_frame_this_id
,
1397 dwarf2_frame_prev_register
,
1399 dwarf2_frame_sniffer
,
1401 /* TAILCALL_CACHE can never be in such frame to need dealloc_cache. */
1405 /* Append the DWARF-2 frame unwinders to GDBARCH's list. */
1408 dwarf2_append_unwinders (struct gdbarch
*gdbarch
)
1410 frame_unwind_append_unwinder (gdbarch
, &dwarf2_frame_unwind
);
1411 frame_unwind_append_unwinder (gdbarch
, &dwarf2_signal_frame_unwind
);
1415 /* There is no explicitly defined relationship between the CFA and the
1416 location of frame's local variables and arguments/parameters.
1417 Therefore, frame base methods on this page should probably only be
1418 used as a last resort, just to avoid printing total garbage as a
1419 response to the "info frame" command. */
1422 dwarf2_frame_base_address (struct frame_info
*this_frame
, void **this_cache
)
1424 struct dwarf2_frame_cache
*cache
=
1425 dwarf2_frame_cache (this_frame
, this_cache
);
1430 static const struct frame_base dwarf2_frame_base
=
1432 &dwarf2_frame_unwind
,
1433 dwarf2_frame_base_address
,
1434 dwarf2_frame_base_address
,
1435 dwarf2_frame_base_address
1438 const struct frame_base
*
1439 dwarf2_frame_base_sniffer (struct frame_info
*this_frame
)
1441 CORE_ADDR block_addr
= get_frame_address_in_block (this_frame
);
1443 if (dwarf2_frame_find_fde (&block_addr
, NULL
))
1444 return &dwarf2_frame_base
;
1449 /* Compute the CFA for THIS_FRAME, but only if THIS_FRAME came from
1450 the DWARF unwinder. This is used to implement
1451 DW_OP_call_frame_cfa. */
1454 dwarf2_frame_cfa (struct frame_info
*this_frame
)
1456 if (frame_unwinder_is (this_frame
, &record_btrace_tailcall_frame_unwind
)
1457 || frame_unwinder_is (this_frame
, &record_btrace_frame_unwind
))
1458 throw_error (NOT_AVAILABLE_ERROR
,
1459 _("cfa not available for record btrace target"));
1461 while (get_frame_type (this_frame
) == INLINE_FRAME
)
1462 this_frame
= get_prev_frame (this_frame
);
1463 if (get_frame_unwind_stop_reason (this_frame
) == UNWIND_UNAVAILABLE
)
1464 throw_error (NOT_AVAILABLE_ERROR
,
1465 _("can't compute CFA for this frame: "
1466 "required registers or memory are unavailable"));
1468 if (get_frame_id (this_frame
).stack_status
!= FID_STACK_VALID
)
1469 throw_error (NOT_AVAILABLE_ERROR
,
1470 _("can't compute CFA for this frame: "
1471 "frame base not available"));
1473 return get_frame_base (this_frame
);
1476 /* We store the frame data on the BFD. This is only done if it is
1477 independent of the address space and so can be shared. */
1478 static const struct bfd_key
<comp_unit
> dwarf2_frame_bfd_data
;
1480 /* If any BFD sections require relocations (note; really should be if
1481 any debug info requires relocations), then we store the frame data
1482 on the objfile instead, and do not share it. */
1483 const struct objfile_key
<comp_unit
> dwarf2_frame_objfile_data
;
1486 /* Pointer encoding helper functions. */
1488 /* GCC supports exception handling based on DWARF2 CFI. However, for
1489 technical reasons, it encodes addresses in its FDE's in a different
1490 way. Several "pointer encodings" are supported. The encoding
1491 that's used for a particular FDE is determined by the 'R'
1492 augmentation in the associated CIE. The argument of this
1493 augmentation is a single byte.
1495 The address can be encoded as 2 bytes, 4 bytes, 8 bytes, or as a
1496 LEB128. This is encoded in bits 0, 1 and 2. Bit 3 encodes whether
1497 the address is signed or unsigned. Bits 4, 5 and 6 encode how the
1498 address should be interpreted (absolute, relative to the current
1499 position in the FDE, ...). Bit 7, indicates that the address
1500 should be dereferenced. */
1503 encoding_for_size (unsigned int size
)
1508 return DW_EH_PE_udata2
;
1510 return DW_EH_PE_udata4
;
1512 return DW_EH_PE_udata8
;
1514 internal_error (__FILE__
, __LINE__
, _("Unsupported address size"));
1519 read_encoded_value (struct comp_unit
*unit
, gdb_byte encoding
,
1520 int ptr_len
, const gdb_byte
*buf
,
1521 unsigned int *bytes_read_ptr
,
1522 CORE_ADDR func_base
)
1527 /* GCC currently doesn't generate DW_EH_PE_indirect encodings for
1529 if (encoding
& DW_EH_PE_indirect
)
1530 internal_error (__FILE__
, __LINE__
,
1531 _("Unsupported encoding: DW_EH_PE_indirect"));
1533 *bytes_read_ptr
= 0;
1535 switch (encoding
& 0x70)
1537 case DW_EH_PE_absptr
:
1540 case DW_EH_PE_pcrel
:
1541 base
= bfd_section_vma (unit
->dwarf_frame_section
);
1542 base
+= (buf
- unit
->dwarf_frame_buffer
);
1544 case DW_EH_PE_datarel
:
1547 case DW_EH_PE_textrel
:
1550 case DW_EH_PE_funcrel
:
1553 case DW_EH_PE_aligned
:
1555 offset
= buf
- unit
->dwarf_frame_buffer
;
1556 if ((offset
% ptr_len
) != 0)
1558 *bytes_read_ptr
= ptr_len
- (offset
% ptr_len
);
1559 buf
+= *bytes_read_ptr
;
1563 internal_error (__FILE__
, __LINE__
,
1564 _("Invalid or unsupported encoding"));
1567 if ((encoding
& 0x07) == 0x00)
1569 encoding
|= encoding_for_size (ptr_len
);
1570 if (bfd_get_sign_extend_vma (unit
->abfd
))
1571 encoding
|= DW_EH_PE_signed
;
1574 switch (encoding
& 0x0f)
1576 case DW_EH_PE_uleb128
:
1579 const gdb_byte
*end_buf
= buf
+ (sizeof (value
) + 1) * 8 / 7;
1581 *bytes_read_ptr
+= safe_read_uleb128 (buf
, end_buf
, &value
) - buf
;
1582 return base
+ value
;
1584 case DW_EH_PE_udata2
:
1585 *bytes_read_ptr
+= 2;
1586 return (base
+ bfd_get_16 (unit
->abfd
, (bfd_byte
*) buf
));
1587 case DW_EH_PE_udata4
:
1588 *bytes_read_ptr
+= 4;
1589 return (base
+ bfd_get_32 (unit
->abfd
, (bfd_byte
*) buf
));
1590 case DW_EH_PE_udata8
:
1591 *bytes_read_ptr
+= 8;
1592 return (base
+ bfd_get_64 (unit
->abfd
, (bfd_byte
*) buf
));
1593 case DW_EH_PE_sleb128
:
1596 const gdb_byte
*end_buf
= buf
+ (sizeof (value
) + 1) * 8 / 7;
1598 *bytes_read_ptr
+= safe_read_sleb128 (buf
, end_buf
, &value
) - buf
;
1599 return base
+ value
;
1601 case DW_EH_PE_sdata2
:
1602 *bytes_read_ptr
+= 2;
1603 return (base
+ bfd_get_signed_16 (unit
->abfd
, (bfd_byte
*) buf
));
1604 case DW_EH_PE_sdata4
:
1605 *bytes_read_ptr
+= 4;
1606 return (base
+ bfd_get_signed_32 (unit
->abfd
, (bfd_byte
*) buf
));
1607 case DW_EH_PE_sdata8
:
1608 *bytes_read_ptr
+= 8;
1609 return (base
+ bfd_get_signed_64 (unit
->abfd
, (bfd_byte
*) buf
));
1611 internal_error (__FILE__
, __LINE__
,
1612 _("Invalid or unsupported encoding"));
1617 /* Find CIE with the given CIE_POINTER in CIE_TABLE. */
1618 static struct dwarf2_cie
*
1619 find_cie (const dwarf2_cie_table
&cie_table
, ULONGEST cie_pointer
)
1621 auto iter
= cie_table
.find (cie_pointer
);
1622 if (iter
!= cie_table
.end ())
1623 return iter
->second
;
1628 bsearch_fde_cmp (const dwarf2_fde
*fde
, CORE_ADDR seek_pc
)
1630 if (fde
->initial_location
+ fde
->address_range
<= seek_pc
)
1632 if (fde
->initial_location
<= seek_pc
)
1637 /* Find an existing comp_unit for an objfile, if any. */
1640 find_comp_unit (struct objfile
*objfile
)
1642 bfd
*abfd
= objfile
->obfd
;
1643 if (gdb_bfd_requires_relocations (abfd
))
1644 return dwarf2_frame_objfile_data
.get (objfile
);
1646 return dwarf2_frame_bfd_data
.get (abfd
);
1649 /* Store the comp_unit on OBJFILE, or the corresponding BFD, as
1653 set_comp_unit (struct objfile
*objfile
, struct comp_unit
*unit
)
1655 bfd
*abfd
= objfile
->obfd
;
1656 if (gdb_bfd_requires_relocations (abfd
))
1657 return dwarf2_frame_objfile_data
.set (objfile
, unit
);
1659 return dwarf2_frame_bfd_data
.set (abfd
, unit
);
1662 /* Find the FDE for *PC. Return a pointer to the FDE, and store the
1663 initial location associated with it into *PC. */
1665 static struct dwarf2_fde
*
1666 dwarf2_frame_find_fde (CORE_ADDR
*pc
, dwarf2_per_objfile
**out_per_objfile
)
1668 for (objfile
*objfile
: current_program_space
->objfiles ())
1673 comp_unit
*unit
= find_comp_unit (objfile
);
1676 dwarf2_build_frame_info (objfile
);
1677 unit
= find_comp_unit (objfile
);
1679 gdb_assert (unit
!= NULL
);
1681 dwarf2_fde_table
*fde_table
= &unit
->fde_table
;
1682 if (fde_table
->empty ())
1685 gdb_assert (!objfile
->section_offsets
.empty ());
1686 offset
= objfile
->text_section_offset ();
1688 gdb_assert (!fde_table
->empty ());
1689 if (*pc
< offset
+ (*fde_table
)[0]->initial_location
)
1692 seek_pc
= *pc
- offset
;
1693 auto it
= gdb::binary_search (fde_table
->begin (), fde_table
->end (),
1694 seek_pc
, bsearch_fde_cmp
);
1695 if (it
!= fde_table
->end ())
1697 *pc
= (*it
)->initial_location
+ offset
;
1698 if (out_per_objfile
!= nullptr)
1699 *out_per_objfile
= get_dwarf2_per_objfile (objfile
);
1707 /* Add FDE to FDE_TABLE. */
1709 add_fde (dwarf2_fde_table
*fde_table
, struct dwarf2_fde
*fde
)
1711 if (fde
->address_range
== 0)
1712 /* Discard useless FDEs. */
1715 fde_table
->push_back (fde
);
1718 #define DW64_CIE_ID 0xffffffffffffffffULL
1720 /* Defines the type of eh_frames that are expected to be decoded: CIE, FDE
1725 EH_CIE_TYPE_ID
= 1 << 0,
1726 EH_FDE_TYPE_ID
= 1 << 1,
1727 EH_CIE_OR_FDE_TYPE_ID
= EH_CIE_TYPE_ID
| EH_FDE_TYPE_ID
1730 static const gdb_byte
*decode_frame_entry (struct gdbarch
*gdbarch
,
1731 struct comp_unit
*unit
,
1732 const gdb_byte
*start
,
1734 dwarf2_cie_table
&cie_table
,
1735 dwarf2_fde_table
*fde_table
,
1736 enum eh_frame_type entry_type
);
1738 /* Decode the next CIE or FDE, entry_type specifies the expected type.
1739 Return NULL if invalid input, otherwise the next byte to be processed. */
1741 static const gdb_byte
*
1742 decode_frame_entry_1 (struct gdbarch
*gdbarch
,
1743 struct comp_unit
*unit
, const gdb_byte
*start
,
1745 dwarf2_cie_table
&cie_table
,
1746 dwarf2_fde_table
*fde_table
,
1747 enum eh_frame_type entry_type
)
1749 const gdb_byte
*buf
, *end
;
1751 unsigned int bytes_read
;
1754 ULONGEST cie_pointer
;
1759 length
= read_initial_length (unit
->abfd
, buf
, &bytes_read
, false);
1761 end
= buf
+ (size_t) length
;
1766 /* Are we still within the section? */
1767 if (end
<= buf
|| end
> unit
->dwarf_frame_buffer
+ unit
->dwarf_frame_size
)
1770 /* Distinguish between 32 and 64-bit encoded frame info. */
1771 dwarf64_p
= (bytes_read
== 12);
1773 /* In a .eh_frame section, zero is used to distinguish CIEs from FDEs. */
1777 cie_id
= DW64_CIE_ID
;
1783 cie_pointer
= read_8_bytes (unit
->abfd
, buf
);
1788 cie_pointer
= read_4_bytes (unit
->abfd
, buf
);
1792 if (cie_pointer
== cie_id
)
1794 /* This is a CIE. */
1795 struct dwarf2_cie
*cie
;
1797 unsigned int cie_version
;
1799 /* Check that a CIE was expected. */
1800 if ((entry_type
& EH_CIE_TYPE_ID
) == 0)
1801 error (_("Found a CIE when not expecting it."));
1803 /* Record the offset into the .debug_frame section of this CIE. */
1804 cie_pointer
= start
- unit
->dwarf_frame_buffer
;
1806 /* Check whether we've already read it. */
1807 if (find_cie (cie_table
, cie_pointer
))
1810 cie
= XOBNEW (&unit
->obstack
, struct dwarf2_cie
);
1811 cie
->initial_instructions
= NULL
;
1812 cie
->cie_pointer
= cie_pointer
;
1814 /* The encoding for FDE's in a normal .debug_frame section
1815 depends on the target address size. */
1816 cie
->encoding
= DW_EH_PE_absptr
;
1818 /* We'll determine the final value later, but we need to
1819 initialize it conservatively. */
1820 cie
->signal_frame
= 0;
1822 /* Check version number. */
1823 cie_version
= read_1_byte (unit
->abfd
, buf
);
1824 if (cie_version
!= 1 && cie_version
!= 3 && cie_version
!= 4)
1826 cie
->version
= cie_version
;
1829 /* Interpret the interesting bits of the augmentation. */
1830 cie
->augmentation
= augmentation
= (char *) buf
;
1831 buf
+= (strlen (augmentation
) + 1);
1833 /* Ignore armcc augmentations. We only use them for quirks,
1834 and that doesn't happen until later. */
1835 if (startswith (augmentation
, "armcc"))
1836 augmentation
+= strlen (augmentation
);
1838 /* The GCC 2.x "eh" augmentation has a pointer immediately
1839 following the augmentation string, so it must be handled
1841 if (augmentation
[0] == 'e' && augmentation
[1] == 'h')
1844 buf
+= gdbarch_ptr_bit (gdbarch
) / TARGET_CHAR_BIT
;
1848 if (cie
->version
>= 4)
1850 /* FIXME: check that this is the same as from the CU header. */
1851 cie
->addr_size
= read_1_byte (unit
->abfd
, buf
);
1853 cie
->segment_size
= read_1_byte (unit
->abfd
, buf
);
1858 cie
->addr_size
= gdbarch_dwarf2_addr_size (gdbarch
);
1859 cie
->segment_size
= 0;
1861 /* Address values in .eh_frame sections are defined to have the
1862 target's pointer size. Watchout: This breaks frame info for
1863 targets with pointer size < address size, unless a .debug_frame
1864 section exists as well. */
1866 cie
->ptr_size
= gdbarch_ptr_bit (gdbarch
) / TARGET_CHAR_BIT
;
1868 cie
->ptr_size
= cie
->addr_size
;
1870 buf
= gdb_read_uleb128 (buf
, end
, &uleb128
);
1873 cie
->code_alignment_factor
= uleb128
;
1875 buf
= gdb_read_sleb128 (buf
, end
, &sleb128
);
1878 cie
->data_alignment_factor
= sleb128
;
1880 if (cie_version
== 1)
1882 cie
->return_address_register
= read_1_byte (unit
->abfd
, buf
);
1887 buf
= gdb_read_uleb128 (buf
, end
, &uleb128
);
1890 cie
->return_address_register
= uleb128
;
1893 cie
->return_address_register
1894 = dwarf2_frame_adjust_regnum (gdbarch
,
1895 cie
->return_address_register
,
1898 cie
->saw_z_augmentation
= (*augmentation
== 'z');
1899 if (cie
->saw_z_augmentation
)
1901 uint64_t uleb_length
;
1903 buf
= gdb_read_uleb128 (buf
, end
, &uleb_length
);
1906 cie
->initial_instructions
= buf
+ uleb_length
;
1910 while (*augmentation
)
1912 /* "L" indicates a byte showing how the LSDA pointer is encoded. */
1913 if (*augmentation
== 'L')
1920 /* "R" indicates a byte indicating how FDE addresses are encoded. */
1921 else if (*augmentation
== 'R')
1923 cie
->encoding
= *buf
++;
1927 /* "P" indicates a personality routine in the CIE augmentation. */
1928 else if (*augmentation
== 'P')
1930 /* Skip. Avoid indirection since we throw away the result. */
1931 gdb_byte encoding
= (*buf
++) & ~DW_EH_PE_indirect
;
1932 read_encoded_value (unit
, encoding
, cie
->ptr_size
,
1933 buf
, &bytes_read
, 0);
1938 /* "S" indicates a signal frame, such that the return
1939 address must not be decremented to locate the call frame
1940 info for the previous frame; it might even be the first
1941 instruction of a function, so decrementing it would take
1942 us to a different function. */
1943 else if (*augmentation
== 'S')
1945 cie
->signal_frame
= 1;
1949 /* Otherwise we have an unknown augmentation. Assume that either
1950 there is no augmentation data, or we saw a 'z' prefix. */
1953 if (cie
->initial_instructions
)
1954 buf
= cie
->initial_instructions
;
1959 cie
->initial_instructions
= buf
;
1963 cie_table
[cie
->cie_pointer
] = cie
;
1967 /* This is a FDE. */
1968 struct dwarf2_fde
*fde
;
1971 /* Check that an FDE was expected. */
1972 if ((entry_type
& EH_FDE_TYPE_ID
) == 0)
1973 error (_("Found an FDE when not expecting it."));
1975 /* In an .eh_frame section, the CIE pointer is the delta between the
1976 address within the FDE where the CIE pointer is stored and the
1977 address of the CIE. Convert it to an offset into the .eh_frame
1981 cie_pointer
= buf
- unit
->dwarf_frame_buffer
- cie_pointer
;
1982 cie_pointer
-= (dwarf64_p
? 8 : 4);
1985 /* In either case, validate the result is still within the section. */
1986 if (cie_pointer
>= unit
->dwarf_frame_size
)
1989 fde
= XOBNEW (&unit
->obstack
, struct dwarf2_fde
);
1990 fde
->cie
= find_cie (cie_table
, cie_pointer
);
1991 if (fde
->cie
== NULL
)
1993 decode_frame_entry (gdbarch
, unit
,
1994 unit
->dwarf_frame_buffer
+ cie_pointer
,
1995 eh_frame_p
, cie_table
, fde_table
,
1997 fde
->cie
= find_cie (cie_table
, cie_pointer
);
2000 gdb_assert (fde
->cie
!= NULL
);
2002 addr
= read_encoded_value (unit
, fde
->cie
->encoding
, fde
->cie
->ptr_size
,
2003 buf
, &bytes_read
, 0);
2004 fde
->initial_location
= gdbarch_adjust_dwarf2_addr (gdbarch
, addr
);
2007 fde
->address_range
=
2008 read_encoded_value (unit
, fde
->cie
->encoding
& 0x0f,
2009 fde
->cie
->ptr_size
, buf
, &bytes_read
, 0);
2010 addr
= gdbarch_adjust_dwarf2_addr (gdbarch
, addr
+ fde
->address_range
);
2011 fde
->address_range
= addr
- fde
->initial_location
;
2014 /* A 'z' augmentation in the CIE implies the presence of an
2015 augmentation field in the FDE as well. The only thing known
2016 to be in here at present is the LSDA entry for EH. So we
2017 can skip the whole thing. */
2018 if (fde
->cie
->saw_z_augmentation
)
2020 uint64_t uleb_length
;
2022 buf
= gdb_read_uleb128 (buf
, end
, &uleb_length
);
2030 fde
->instructions
= buf
;
2033 fde
->eh_frame_p
= eh_frame_p
;
2035 add_fde (fde_table
, fde
);
2041 /* Read a CIE or FDE in BUF and decode it. Entry_type specifies whether we
2042 expect an FDE or a CIE. */
2044 static const gdb_byte
*
2045 decode_frame_entry (struct gdbarch
*gdbarch
,
2046 struct comp_unit
*unit
, const gdb_byte
*start
,
2048 dwarf2_cie_table
&cie_table
,
2049 dwarf2_fde_table
*fde_table
,
2050 enum eh_frame_type entry_type
)
2052 enum { NONE
, ALIGN4
, ALIGN8
, FAIL
} workaround
= NONE
;
2053 const gdb_byte
*ret
;
2054 ptrdiff_t start_offset
;
2058 ret
= decode_frame_entry_1 (gdbarch
, unit
, start
, eh_frame_p
,
2059 cie_table
, fde_table
, entry_type
);
2063 /* We have corrupt input data of some form. */
2065 /* ??? Try, weakly, to work around compiler/assembler/linker bugs
2066 and mismatches wrt padding and alignment of debug sections. */
2067 /* Note that there is no requirement in the standard for any
2068 alignment at all in the frame unwind sections. Testing for
2069 alignment before trying to interpret data would be incorrect.
2071 However, GCC traditionally arranged for frame sections to be
2072 sized such that the FDE length and CIE fields happen to be
2073 aligned (in theory, for performance). This, unfortunately,
2074 was done with .align directives, which had the side effect of
2075 forcing the section to be aligned by the linker.
2077 This becomes a problem when you have some other producer that
2078 creates frame sections that are not as strictly aligned. That
2079 produces a hole in the frame info that gets filled by the
2082 The GCC behaviour is arguably a bug, but it's effectively now
2083 part of the ABI, so we're now stuck with it, at least at the
2084 object file level. A smart linker may decide, in the process
2085 of compressing duplicate CIE information, that it can rewrite
2086 the entire output section without this extra padding. */
2088 start_offset
= start
- unit
->dwarf_frame_buffer
;
2089 if (workaround
< ALIGN4
&& (start_offset
& 3) != 0)
2091 start
+= 4 - (start_offset
& 3);
2092 workaround
= ALIGN4
;
2095 if (workaround
< ALIGN8
&& (start_offset
& 7) != 0)
2097 start
+= 8 - (start_offset
& 7);
2098 workaround
= ALIGN8
;
2102 /* Nothing left to try. Arrange to return as if we've consumed
2103 the entire input section. Hopefully we'll get valid info from
2104 the other of .debug_frame/.eh_frame. */
2106 ret
= unit
->dwarf_frame_buffer
+ unit
->dwarf_frame_size
;
2117 Corrupt data in %s:%s; align 4 workaround apparently succeeded"),
2118 bfd_get_filename (unit
->dwarf_frame_section
->owner
),
2119 bfd_section_name (unit
->dwarf_frame_section
));
2124 Corrupt data in %s:%s; align 8 workaround apparently succeeded"),
2125 bfd_get_filename (unit
->dwarf_frame_section
->owner
),
2126 bfd_section_name (unit
->dwarf_frame_section
));
2130 complaint (_("Corrupt data in %s:%s"),
2131 bfd_get_filename (unit
->dwarf_frame_section
->owner
),
2132 bfd_section_name (unit
->dwarf_frame_section
));
2140 fde_is_less_than (const dwarf2_fde
*aa
, const dwarf2_fde
*bb
)
2142 if (aa
->initial_location
== bb
->initial_location
)
2144 if (aa
->address_range
!= bb
->address_range
2145 && aa
->eh_frame_p
== 0 && bb
->eh_frame_p
== 0)
2146 /* Linker bug, e.g. gold/10400.
2147 Work around it by keeping stable sort order. */
2150 /* Put eh_frame entries after debug_frame ones. */
2151 return aa
->eh_frame_p
< bb
->eh_frame_p
;
2154 return aa
->initial_location
< bb
->initial_location
;
2158 dwarf2_build_frame_info (struct objfile
*objfile
)
2160 const gdb_byte
*frame_ptr
;
2161 dwarf2_cie_table cie_table
;
2162 dwarf2_fde_table fde_table
;
2164 struct gdbarch
*gdbarch
= objfile
->arch ();
2166 /* Build a minimal decoding of the DWARF2 compilation unit. */
2167 std::unique_ptr
<comp_unit
> unit (new comp_unit (objfile
));
2169 if (objfile
->separate_debug_objfile_backlink
== NULL
)
2171 /* Do not read .eh_frame from separate file as they must be also
2172 present in the main file. */
2173 dwarf2_get_section_info (objfile
, DWARF2_EH_FRAME
,
2174 &unit
->dwarf_frame_section
,
2175 &unit
->dwarf_frame_buffer
,
2176 &unit
->dwarf_frame_size
);
2177 if (unit
->dwarf_frame_size
)
2179 asection
*got
, *txt
;
2181 /* FIXME: kettenis/20030602: This is the DW_EH_PE_datarel base
2182 that is used for the i386/amd64 target, which currently is
2183 the only target in GCC that supports/uses the
2184 DW_EH_PE_datarel encoding. */
2185 got
= bfd_get_section_by_name (unit
->abfd
, ".got");
2187 unit
->dbase
= got
->vma
;
2189 /* GCC emits the DW_EH_PE_textrel encoding type on sh and ia64
2191 txt
= bfd_get_section_by_name (unit
->abfd
, ".text");
2193 unit
->tbase
= txt
->vma
;
2197 frame_ptr
= unit
->dwarf_frame_buffer
;
2198 while (frame_ptr
< unit
->dwarf_frame_buffer
+ unit
->dwarf_frame_size
)
2199 frame_ptr
= decode_frame_entry (gdbarch
, unit
.get (),
2201 cie_table
, &fde_table
,
2202 EH_CIE_OR_FDE_TYPE_ID
);
2205 catch (const gdb_exception_error
&e
)
2207 warning (_("skipping .eh_frame info of %s: %s"),
2208 objfile_name (objfile
), e
.what ());
2211 /* The cie_table is discarded below. */
2218 dwarf2_get_section_info (objfile
, DWARF2_DEBUG_FRAME
,
2219 &unit
->dwarf_frame_section
,
2220 &unit
->dwarf_frame_buffer
,
2221 &unit
->dwarf_frame_size
);
2222 if (unit
->dwarf_frame_size
)
2224 size_t num_old_fde_entries
= fde_table
.size ();
2228 frame_ptr
= unit
->dwarf_frame_buffer
;
2229 while (frame_ptr
< unit
->dwarf_frame_buffer
+ unit
->dwarf_frame_size
)
2230 frame_ptr
= decode_frame_entry (gdbarch
, unit
.get (), frame_ptr
, 0,
2231 cie_table
, &fde_table
,
2232 EH_CIE_OR_FDE_TYPE_ID
);
2234 catch (const gdb_exception_error
&e
)
2236 warning (_("skipping .debug_frame info of %s: %s"),
2237 objfile_name (objfile
), e
.what ());
2239 fde_table
.resize (num_old_fde_entries
);
2243 struct dwarf2_fde
*fde_prev
= NULL
;
2244 struct dwarf2_fde
*first_non_zero_fde
= NULL
;
2246 /* Prepare FDE table for lookups. */
2247 std::sort (fde_table
.begin (), fde_table
.end (), fde_is_less_than
);
2249 /* Check for leftovers from --gc-sections. The GNU linker sets
2250 the relevant symbols to zero, but doesn't zero the FDE *end*
2251 ranges because there's no relocation there. It's (offset,
2252 length), not (start, end). On targets where address zero is
2253 just another valid address this can be a problem, since the
2254 FDEs appear to be non-empty in the output --- we could pick
2255 out the wrong FDE. To work around this, when overlaps are
2256 detected, we prefer FDEs that do not start at zero.
2258 Start by finding the first FDE with non-zero start. Below
2259 we'll discard all FDEs that start at zero and overlap this
2261 for (struct dwarf2_fde
*fde
: fde_table
)
2263 if (fde
->initial_location
!= 0)
2265 first_non_zero_fde
= fde
;
2270 /* Since we'll be doing bsearch, squeeze out identical (except
2271 for eh_frame_p) fde entries so bsearch result is predictable.
2272 Also discard leftovers from --gc-sections. */
2273 for (struct dwarf2_fde
*fde
: fde_table
)
2275 if (fde
->initial_location
== 0
2276 && first_non_zero_fde
!= NULL
2277 && (first_non_zero_fde
->initial_location
2278 < fde
->initial_location
+ fde
->address_range
))
2281 if (fde_prev
!= NULL
2282 && fde_prev
->initial_location
== fde
->initial_location
)
2285 unit
->fde_table
.push_back (fde
);
2288 unit
->fde_table
.shrink_to_fit ();
2290 set_comp_unit (objfile
, unit
.release ());
2293 /* Handle 'maintenance show dwarf unwinders'. */
2296 show_dwarf_unwinders_enabled_p (struct ui_file
*file
, int from_tty
,
2297 struct cmd_list_element
*c
,
2300 fprintf_filtered (file
,
2301 _("The DWARF stack unwinders are currently %s.\n"),
2305 void _initialize_dwarf2_frame ();
2307 _initialize_dwarf2_frame ()
2309 dwarf2_frame_data
= gdbarch_data_register_pre_init (dwarf2_frame_init
);
2311 add_setshow_boolean_cmd ("unwinders", class_obscure
,
2312 &dwarf2_frame_unwinders_enabled_p
, _("\
2313 Set whether the DWARF stack frame unwinders are used."), _("\
2314 Show whether the DWARF stack frame unwinders are used."), _("\
2315 When enabled the DWARF stack frame unwinders can be used for architectures\n\
2316 that support the DWARF unwinders. Enabling the DWARF unwinders for an\n\
2317 architecture that doesn't support them will have no effect."),
2319 show_dwarf_unwinders_enabled_p
,
2321 &show_dwarf_cmdlist
);
2324 selftests::register_test_foreach_arch ("execute_cfa_program",
2325 selftests::execute_cfa_program_test
);