1 /* Frame unwinder for frames with DWARF Call Frame Information.
3 Copyright 2003 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 2 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, write to the Free Software
21 Foundation, Inc., 59 Temple Place - Suite 330,
22 Boston, MA 02111-1307, USA. */
25 #include "dwarf2expr.h"
26 #include "elf/dwarf2.h"
28 #include "frame-base.h"
29 #include "frame-unwind.h"
36 #include "gdb_assert.h"
37 #include "gdb_string.h"
39 #include "complaints.h"
40 #include "dwarf2-frame.h"
42 /* Call Frame Information (CFI). */
44 /* Common Information Entry (CIE). */
48 /* Offset into the .debug_frame section where this CIE was found.
49 Used to identify this CIE. */
52 /* Constant that is factored out of all advance location
54 ULONGEST code_alignment_factor
;
56 /* Constants that is factored out of all offset instructions. */
57 LONGEST data_alignment_factor
;
59 /* Return address column. */
60 ULONGEST return_address_register
;
62 /* Instruction sequence to initialize a register set. */
63 unsigned char *initial_instructions
;
66 /* Encoding of addresses. */
67 unsigned char encoding
;
69 /* True if a 'z' augmentation existed. */
70 unsigned char saw_z_augmentation
;
72 struct dwarf2_cie
*next
;
75 /* Frame Description Entry (FDE). */
79 /* CIE for this FDE. */
80 struct dwarf2_cie
*cie
;
82 /* First location associated with this FDE. */
83 CORE_ADDR initial_location
;
85 /* Number of bytes of program instructions described by this FDE. */
86 CORE_ADDR address_range
;
88 /* Instruction sequence. */
89 unsigned char *instructions
;
92 struct dwarf2_fde
*next
;
95 static struct dwarf2_fde
*dwarf2_frame_find_fde (CORE_ADDR
*pc
);
98 /* Structure describing a frame state. */
102 /* Make certain that 0 maps onto the correct enum value; the
103 corresponding structure is being initialized using memset zero.
104 This indicates that CFI didn't provide any information at all
105 about a register, leaving how to obtain its value totally
109 /* The term "undefined" comes from the DWARF2 CFI spec which this
110 code is moddeling; it indicates that the register's value is
111 "undefined". GCC uses the less formal term "unsaved". Its
112 definition is a combination of REG_UNDEFINED and REG_UNSPECIFIED.
113 The failure to differentiate the two helps explain a few problems
114 with the CFI generated by GCC. */
121 /* These aren't defined by the DWARF2 CFI specification, but are
122 used internally by GDB. */
123 REG_RA
, /* Return Address. */
124 REG_CFA
/* Call Frame Address. */
127 struct dwarf2_frame_state
129 /* Each register save state can be described in terms of a CFA slot,
130 another register, or a location expression. */
131 struct dwarf2_frame_state_reg_info
133 struct dwarf2_frame_state_reg
141 enum dwarf2_reg_rule how
;
145 /* Used to implement DW_CFA_remember_state. */
146 struct dwarf2_frame_state_reg_info
*prev
;
151 unsigned char *cfa_exp
;
158 /* The PC described by the current frame state. */
161 /* Initial register set from the CIE.
162 Used to implement DW_CFA_restore. */
163 struct dwarf2_frame_state_reg_info initial
;
165 /* The information we care about from the CIE. */
168 ULONGEST retaddr_column
;
171 /* Store the length the expression for the CFA in the `cfa_reg' field,
172 which is unused in that case. */
173 #define cfa_exp_len cfa_reg
175 /* Assert that the register set RS is large enough to store NUM_REGS
176 columns. If necessary, enlarge the register set. */
179 dwarf2_frame_state_alloc_regs (struct dwarf2_frame_state_reg_info
*rs
,
182 size_t size
= sizeof (struct dwarf2_frame_state_reg
);
184 if (num_regs
<= rs
->num_regs
)
187 rs
->reg
= (struct dwarf2_frame_state_reg
*)
188 xrealloc (rs
->reg
, num_regs
* size
);
190 /* Initialize newly allocated registers. */
191 memset (rs
->reg
+ rs
->num_regs
, 0, (num_regs
- rs
->num_regs
) * size
);
192 rs
->num_regs
= num_regs
;
195 /* Copy the register columns in register set RS into newly allocated
196 memory and return a pointer to this newly created copy. */
198 static struct dwarf2_frame_state_reg
*
199 dwarf2_frame_state_copy_regs (struct dwarf2_frame_state_reg_info
*rs
)
201 size_t size
= rs
->num_regs
* sizeof (struct dwarf2_frame_state_reg_info
);
202 struct dwarf2_frame_state_reg
*reg
;
204 reg
= (struct dwarf2_frame_state_reg
*) xmalloc (size
);
205 memcpy (reg
, rs
->reg
, size
);
210 /* Release the memory allocated to register set RS. */
213 dwarf2_frame_state_free_regs (struct dwarf2_frame_state_reg_info
*rs
)
217 dwarf2_frame_state_free_regs (rs
->prev
);
224 /* Release the memory allocated to the frame state FS. */
227 dwarf2_frame_state_free (void *p
)
229 struct dwarf2_frame_state
*fs
= p
;
231 dwarf2_frame_state_free_regs (fs
->initial
.prev
);
232 dwarf2_frame_state_free_regs (fs
->regs
.prev
);
233 xfree (fs
->initial
.reg
);
234 xfree (fs
->regs
.reg
);
239 /* Helper functions for execute_stack_op. */
242 read_reg (void *baton
, int reg
)
244 struct frame_info
*next_frame
= (struct frame_info
*) baton
;
248 regnum
= DWARF2_REG_TO_REGNUM (reg
);
250 buf
= (char *) alloca (register_size (current_gdbarch
, regnum
));
251 frame_unwind_register (next_frame
, regnum
, buf
);
252 return extract_typed_address (buf
, builtin_type_void_data_ptr
);
256 read_mem (void *baton
, char *buf
, CORE_ADDR addr
, size_t len
)
258 read_memory (addr
, buf
, len
);
262 no_get_frame_base (void *baton
, unsigned char **start
, size_t *length
)
264 internal_error (__FILE__
, __LINE__
,
265 "Support for DW_OP_fbreg is unimplemented");
269 no_get_tls_address (void *baton
, CORE_ADDR offset
)
271 internal_error (__FILE__
, __LINE__
,
272 "Support for DW_OP_GNU_push_tls_address is unimplemented");
276 execute_stack_op (unsigned char *exp
, ULONGEST len
,
277 struct frame_info
*next_frame
, CORE_ADDR initial
)
279 struct dwarf_expr_context
*ctx
;
282 ctx
= new_dwarf_expr_context ();
283 ctx
->baton
= next_frame
;
284 ctx
->read_reg
= read_reg
;
285 ctx
->read_mem
= read_mem
;
286 ctx
->get_frame_base
= no_get_frame_base
;
287 ctx
->get_tls_address
= no_get_tls_address
;
289 dwarf_expr_push (ctx
, initial
);
290 dwarf_expr_eval (ctx
, exp
, len
);
291 result
= dwarf_expr_fetch (ctx
, 0);
294 result
= read_reg (next_frame
, result
);
296 free_dwarf_expr_context (ctx
);
303 execute_cfa_program (unsigned char *insn_ptr
, unsigned char *insn_end
,
304 struct frame_info
*next_frame
,
305 struct dwarf2_frame_state
*fs
)
307 CORE_ADDR pc
= frame_pc_unwind (next_frame
);
310 while (insn_ptr
< insn_end
&& fs
->pc
<= pc
)
312 unsigned char insn
= *insn_ptr
++;
316 if ((insn
& 0xc0) == DW_CFA_advance_loc
)
317 fs
->pc
+= (insn
& 0x3f) * fs
->code_align
;
318 else if ((insn
& 0xc0) == DW_CFA_offset
)
321 insn_ptr
= read_uleb128 (insn_ptr
, insn_end
, &utmp
);
322 offset
= utmp
* fs
->data_align
;
323 dwarf2_frame_state_alloc_regs (&fs
->regs
, reg
+ 1);
324 fs
->regs
.reg
[reg
].how
= REG_SAVED_OFFSET
;
325 fs
->regs
.reg
[reg
].loc
.offset
= offset
;
327 else if ((insn
& 0xc0) == DW_CFA_restore
)
329 gdb_assert (fs
->initial
.reg
);
331 dwarf2_frame_state_alloc_regs (&fs
->regs
, reg
+ 1);
332 fs
->regs
.reg
[reg
] = fs
->initial
.reg
[reg
];
339 fs
->pc
= dwarf2_read_address (insn_ptr
, insn_end
, &bytes_read
);
340 insn_ptr
+= bytes_read
;
343 case DW_CFA_advance_loc1
:
344 utmp
= extract_unsigned_integer (insn_ptr
, 1);
345 fs
->pc
+= utmp
* fs
->code_align
;
348 case DW_CFA_advance_loc2
:
349 utmp
= extract_unsigned_integer (insn_ptr
, 2);
350 fs
->pc
+= utmp
* fs
->code_align
;
353 case DW_CFA_advance_loc4
:
354 utmp
= extract_unsigned_integer (insn_ptr
, 4);
355 fs
->pc
+= utmp
* fs
->code_align
;
359 case DW_CFA_offset_extended
:
360 insn_ptr
= read_uleb128 (insn_ptr
, insn_end
, ®
);
361 insn_ptr
= read_uleb128 (insn_ptr
, insn_end
, &utmp
);
362 offset
= utmp
* fs
->data_align
;
363 dwarf2_frame_state_alloc_regs (&fs
->regs
, reg
+ 1);
364 fs
->regs
.reg
[reg
].how
= REG_SAVED_OFFSET
;
365 fs
->regs
.reg
[reg
].loc
.offset
= offset
;
368 case DW_CFA_restore_extended
:
369 gdb_assert (fs
->initial
.reg
);
370 insn_ptr
= read_uleb128 (insn_ptr
, insn_end
, ®
);
371 dwarf2_frame_state_alloc_regs (&fs
->regs
, reg
+ 1);
372 fs
->regs
.reg
[reg
] = fs
->initial
.reg
[reg
];
375 case DW_CFA_undefined
:
376 insn_ptr
= read_uleb128 (insn_ptr
, insn_end
, ®
);
377 dwarf2_frame_state_alloc_regs (&fs
->regs
, reg
+ 1);
378 fs
->regs
.reg
[reg
].how
= REG_UNDEFINED
;
381 case DW_CFA_same_value
:
382 insn_ptr
= read_uleb128 (insn_ptr
, insn_end
, ®
);
383 dwarf2_frame_state_alloc_regs (&fs
->regs
, reg
+ 1);
384 fs
->regs
.reg
[reg
].how
= REG_SAME_VALUE
;
387 case DW_CFA_register
:
388 insn_ptr
= read_uleb128 (insn_ptr
, insn_end
, ®
);
389 insn_ptr
= read_uleb128 (insn_ptr
, insn_end
, &utmp
);
390 dwarf2_frame_state_alloc_regs (&fs
->regs
, reg
+ 1);
391 fs
->regs
.reg
[reg
].how
= REG_SAVED_REG
;
392 fs
->regs
.reg
[reg
].loc
.reg
= utmp
;
395 case DW_CFA_remember_state
:
397 struct dwarf2_frame_state_reg_info
*new_rs
;
399 new_rs
= XMALLOC (struct dwarf2_frame_state_reg_info
);
401 fs
->regs
.reg
= dwarf2_frame_state_copy_regs (&fs
->regs
);
402 fs
->regs
.prev
= new_rs
;
406 case DW_CFA_restore_state
:
408 struct dwarf2_frame_state_reg_info
*old_rs
= fs
->regs
.prev
;
412 xfree (fs
->regs
.reg
);
419 insn_ptr
= read_uleb128 (insn_ptr
, insn_end
, &fs
->cfa_reg
);
420 insn_ptr
= read_uleb128 (insn_ptr
, insn_end
, &utmp
);
421 fs
->cfa_offset
= utmp
;
422 fs
->cfa_how
= CFA_REG_OFFSET
;
425 case DW_CFA_def_cfa_register
:
426 insn_ptr
= read_uleb128 (insn_ptr
, insn_end
, &fs
->cfa_reg
);
427 fs
->cfa_how
= CFA_REG_OFFSET
;
430 case DW_CFA_def_cfa_offset
:
431 insn_ptr
= read_uleb128 (insn_ptr
, insn_end
, &fs
->cfa_offset
);
432 /* cfa_how deliberately not set. */
438 case DW_CFA_def_cfa_expression
:
439 insn_ptr
= read_uleb128 (insn_ptr
, insn_end
, &fs
->cfa_exp_len
);
440 fs
->cfa_exp
= insn_ptr
;
441 fs
->cfa_how
= CFA_EXP
;
442 insn_ptr
+= fs
->cfa_exp_len
;
445 case DW_CFA_expression
:
446 insn_ptr
= read_uleb128 (insn_ptr
, insn_end
, ®
);
447 dwarf2_frame_state_alloc_regs (&fs
->regs
, reg
+ 1);
448 insn_ptr
= read_uleb128 (insn_ptr
, insn_end
, &utmp
);
449 fs
->regs
.reg
[reg
].loc
.exp
= insn_ptr
;
450 fs
->regs
.reg
[reg
].exp_len
= utmp
;
451 fs
->regs
.reg
[reg
].how
= REG_SAVED_EXP
;
455 case DW_CFA_offset_extended_sf
:
456 insn_ptr
= read_uleb128 (insn_ptr
, insn_end
, ®
);
457 insn_ptr
= read_sleb128 (insn_ptr
, insn_end
, &offset
);
458 offset
+= fs
->data_align
;
459 dwarf2_frame_state_alloc_regs (&fs
->regs
, reg
+ 1);
460 fs
->regs
.reg
[reg
].how
= REG_SAVED_OFFSET
;
461 fs
->regs
.reg
[reg
].loc
.offset
= offset
;
464 case DW_CFA_def_cfa_sf
:
465 insn_ptr
= read_uleb128 (insn_ptr
, insn_end
, &fs
->cfa_reg
);
466 insn_ptr
= read_sleb128 (insn_ptr
, insn_end
, &offset
);
467 fs
->cfa_offset
= offset
* fs
->data_align
;
468 fs
->cfa_how
= CFA_REG_OFFSET
;
471 case DW_CFA_def_cfa_offset_sf
:
472 insn_ptr
= read_sleb128 (insn_ptr
, insn_end
, &offset
);
473 fs
->cfa_offset
= offset
* fs
->data_align
;
474 /* cfa_how deliberately not set. */
477 case DW_CFA_GNU_args_size
:
479 insn_ptr
= read_uleb128 (insn_ptr
, insn_end
, &utmp
);
483 internal_error (__FILE__
, __LINE__
, "Unknown CFI encountered.");
488 /* Don't allow remember/restore between CIE and FDE programs. */
489 dwarf2_frame_state_free_regs (fs
->regs
.prev
);
490 fs
->regs
.prev
= NULL
;
493 struct dwarf2_frame_cache
495 /* DWARF Call Frame Address. */
498 /* Saved registers, indexed by GDB register number, not by DWARF
500 struct dwarf2_frame_state_reg
*reg
;
503 static struct dwarf2_frame_cache
*
504 dwarf2_frame_cache (struct frame_info
*next_frame
, void **this_cache
)
506 struct cleanup
*old_chain
;
507 const int num_regs
= NUM_REGS
+ NUM_PSEUDO_REGS
;
508 struct dwarf2_frame_cache
*cache
;
509 struct dwarf2_frame_state
*fs
;
510 struct dwarf2_fde
*fde
;
515 /* Allocate a new cache. */
516 cache
= FRAME_OBSTACK_ZALLOC (struct dwarf2_frame_cache
);
517 cache
->reg
= FRAME_OBSTACK_CALLOC (num_regs
, struct dwarf2_frame_state_reg
);
519 /* Allocate and initialize the frame state. */
520 fs
= XMALLOC (struct dwarf2_frame_state
);
521 memset (fs
, 0, sizeof (struct dwarf2_frame_state
));
522 old_chain
= make_cleanup (dwarf2_frame_state_free
, fs
);
526 Note that if NEXT_FRAME is never supposed to return (i.e. a call
527 to abort), the compiler might optimize away the instruction at
528 NEXT_FRAME's return address. As a result the return address will
529 point at some random instruction, and the CFI for that
530 instruction is probably worthless to us. GCC's unwinder solves
531 this problem by substracting 1 from the return address to get an
532 address in the middle of a presumed call instruction (or the
533 instruction in the associated delay slot). This should only be
534 done for "normal" frames and not for resume-type frames (signal
535 handlers, sentinel frames, dummy frames). The function
536 frame_unwind_address_in_block does just this. It's not clear how
537 reliable the method is though; there is the potential for the
538 register state pre-call being different to that on return. */
539 fs
->pc
= frame_unwind_address_in_block (next_frame
);
541 /* Find the correct FDE. */
542 fde
= dwarf2_frame_find_fde (&fs
->pc
);
543 gdb_assert (fde
!= NULL
);
545 /* Extract any interesting information from the CIE. */
546 fs
->data_align
= fde
->cie
->data_alignment_factor
;
547 fs
->code_align
= fde
->cie
->code_alignment_factor
;
548 fs
->retaddr_column
= fde
->cie
->return_address_register
;
550 /* First decode all the insns in the CIE. */
551 execute_cfa_program (fde
->cie
->initial_instructions
,
552 fde
->cie
->end
, next_frame
, fs
);
554 /* Save the initialized register set. */
555 fs
->initial
= fs
->regs
;
556 fs
->initial
.reg
= dwarf2_frame_state_copy_regs (&fs
->regs
);
558 /* Then decode the insns in the FDE up to our target PC. */
559 execute_cfa_program (fde
->instructions
, fde
->end
, next_frame
, fs
);
561 /* Caclulate the CFA. */
565 cache
->cfa
= read_reg (next_frame
, fs
->cfa_reg
);
566 cache
->cfa
+= fs
->cfa_offset
;
571 execute_stack_op (fs
->cfa_exp
, fs
->cfa_exp_len
, next_frame
, 0);
575 internal_error (__FILE__
, __LINE__
, "Unknown CFA rule.");
578 /* Initialize the register rules. If we have a register that acts
579 as a program counter, mark it as a destination for the return
580 address. If we have a register that serves as the stack pointer,
581 arrange for it to be filled with the call frame address (CFA).
582 The other registers are marked as unspecified.
584 We copy the return address to the program counter, since many
585 parts in GDB assume that it is possible to get the return address
586 by unwind the program counter register. However, on ISA's with a
587 dedicated return address register, the CFI usually only contains
588 information to unwind that return address register.
590 The reason we're treating the stack pointer special here is
591 because in many cases GCC doesn't emit CFI for the stack pointer
592 and implicitly assumes that it is equal to the CFA. This makes
593 some sense since the DWARF specification (version 3, draft 8,
596 "Typically, the CFA is defined to be the value of the stack
597 pointer at the call site in the previous frame (which may be
598 different from its value on entry to the current frame)."
600 However, this isn't true for all platforms supported by GCC
601 (e.g. IBM S/390 and zSeries). For those targets we should
602 override the defaults given here. */
606 for (regnum
= 0; regnum
< num_regs
; regnum
++)
608 if (regnum
== PC_REGNUM
)
609 cache
->reg
[regnum
].how
= REG_RA
;
610 else if (regnum
== SP_REGNUM
)
611 cache
->reg
[regnum
].how
= REG_CFA
;
613 cache
->reg
[regnum
].how
= REG_UNSPECIFIED
;
617 /* Go through the DWARF2 CFI generated table and save its register
618 location information in the cache. Note that we don't skip the
619 return address column; it's perfectly all right for it to
620 correspond to a real register. If it doesn't correspond to a
621 real register, or if we shouldn't treat it as such,
622 DWARF2_REG_TO_REGNUM should be defined to return a number outside
623 the range [0, NUM_REGS). */
625 int column
; /* CFI speak for "register number". */
627 for (column
= 0; column
< fs
->regs
.num_regs
; column
++)
629 /* Use the GDB register number as the destination index. */
630 int regnum
= DWARF2_REG_TO_REGNUM (column
);
632 /* If there's no corresponding GDB register, ignore it. */
633 if (regnum
< 0 || regnum
>= num_regs
)
636 /* NOTE: cagney/2003-09-05: CFI should specify the disposition
637 of all debug info registers. If it doesn't, complain (but
638 not too loudly). It turns out that GCC assumes that an
639 unspecified register implies "same value" when CFI (draft
640 7) specifies nothing at all. Such a register could equally
641 be interpreted as "undefined". Also note that this check
642 isn't sufficient; it only checks that all registers in the
643 range [0 .. max column] are specified, and won't detect
644 problems when a debug info register falls outside of the
645 table. We need a way of iterating through all the valid
646 DWARF2 register numbers. */
647 if (fs
->regs
.reg
[column
].how
== REG_UNSPECIFIED
)
648 complaint (&symfile_complaints
,
649 "Incomplete CFI data; unspecified registers at 0x%s",
652 cache
->reg
[regnum
] = fs
->regs
.reg
[column
];
656 /* Eliminate any REG_RA rules. */
660 for (regnum
= 0; regnum
< num_regs
; regnum
++)
662 if (cache
->reg
[regnum
].how
== REG_RA
)
664 if (fs
->retaddr_column
< fs
->regs
.num_regs
)
665 cache
->reg
[regnum
] = fs
->regs
.reg
[fs
->retaddr_column
];
668 /* It turns out that GCC assumes that if the return
669 address column is "empty" the return address can be
670 found in the register corresponding to the return
672 cache
->reg
[regnum
].loc
.reg
= fs
->retaddr_column
;
673 cache
->reg
[regnum
].how
= REG_SAVED_REG
;
679 do_cleanups (old_chain
);
686 dwarf2_frame_this_id (struct frame_info
*next_frame
, void **this_cache
,
687 struct frame_id
*this_id
)
689 struct dwarf2_frame_cache
*cache
=
690 dwarf2_frame_cache (next_frame
, this_cache
);
692 (*this_id
) = frame_id_build (cache
->cfa
, frame_func_unwind (next_frame
));
696 dwarf2_frame_prev_register (struct frame_info
*next_frame
, void **this_cache
,
697 int regnum
, int *optimizedp
,
698 enum lval_type
*lvalp
, CORE_ADDR
*addrp
,
699 int *realnump
, void *valuep
)
701 struct dwarf2_frame_cache
*cache
=
702 dwarf2_frame_cache (next_frame
, this_cache
);
704 switch (cache
->reg
[regnum
].how
)
707 /* If CFI explicitly specified that the value isn't defined,
708 mark it as optimized away; the value isn't available. */
715 /* In some cases, for example %eflags on the i386, we have
716 to provide a sane value, even though this register wasn't
717 saved. Assume we can get it from NEXT_FRAME. */
718 frame_unwind_register (next_frame
, regnum
, valuep
);
722 case REG_SAVED_OFFSET
:
724 *lvalp
= lval_memory
;
725 *addrp
= cache
->cfa
+ cache
->reg
[regnum
].loc
.offset
;
729 /* Read the value in from memory. */
730 read_memory (*addrp
, valuep
,
731 register_size (current_gdbarch
, regnum
));
736 regnum
= DWARF2_REG_TO_REGNUM (cache
->reg
[regnum
].loc
.reg
);
737 frame_register_unwind (next_frame
, regnum
,
738 optimizedp
, lvalp
, addrp
, realnump
, valuep
);
743 *lvalp
= lval_memory
;
744 *addrp
= execute_stack_op (cache
->reg
[regnum
].loc
.exp
,
745 cache
->reg
[regnum
].exp_len
,
746 next_frame
, cache
->cfa
);
750 /* Read the value in from memory. */
751 read_memory (*addrp
, valuep
,
752 register_size (current_gdbarch
, regnum
));
756 case REG_UNSPECIFIED
:
757 /* GCC, in its infinite wisdom decided to not provide unwind
758 information for registers that are "same value". Since
759 DWARF2 (3 draft 7) doesn't define such behavior, said
760 registers are actually undefined (which is different to CFI
761 "undefined"). Code above issues a complaint about this.
762 Here just fudge the books, assume GCC, and that the value is
763 more inner on the stack. */
764 frame_register_unwind (next_frame
, regnum
,
765 optimizedp
, lvalp
, addrp
, realnump
, valuep
);
769 frame_register_unwind (next_frame
, regnum
,
770 optimizedp
, lvalp
, addrp
, realnump
, valuep
);
780 /* Store the value. */
781 store_typed_address (valuep
, builtin_type_void_data_ptr
, cache
->cfa
);
786 internal_error (__FILE__
, __LINE__
, "Unknown register rule.");
790 static const struct frame_unwind dwarf2_frame_unwind
=
793 dwarf2_frame_this_id
,
794 dwarf2_frame_prev_register
797 const struct frame_unwind
*
798 dwarf2_frame_sniffer (struct frame_info
*next_frame
)
800 /* Grab an address that is guarenteed to reside somewhere within the
801 function. frame_pc_unwind(), for a no-return next function, can
802 end up returning something past the end of this function's body. */
803 CORE_ADDR block_addr
= frame_unwind_address_in_block (next_frame
);
804 if (dwarf2_frame_find_fde (&block_addr
))
805 return &dwarf2_frame_unwind
;
811 /* There is no explicitly defined relationship between the CFA and the
812 location of frame's local variables and arguments/parameters.
813 Therefore, frame base methods on this page should probably only be
814 used as a last resort, just to avoid printing total garbage as a
815 response to the "info frame" command. */
818 dwarf2_frame_base_address (struct frame_info
*next_frame
, void **this_cache
)
820 struct dwarf2_frame_cache
*cache
=
821 dwarf2_frame_cache (next_frame
, this_cache
);
826 static const struct frame_base dwarf2_frame_base
=
828 &dwarf2_frame_unwind
,
829 dwarf2_frame_base_address
,
830 dwarf2_frame_base_address
,
831 dwarf2_frame_base_address
834 const struct frame_base
*
835 dwarf2_frame_base_sniffer (struct frame_info
*next_frame
)
837 CORE_ADDR pc
= frame_pc_unwind (next_frame
);
838 if (dwarf2_frame_find_fde (&pc
))
839 return &dwarf2_frame_base
;
844 /* A minimal decoding of DWARF2 compilation units. We only decode
845 what's needed to get to the call frame information. */
849 /* Keep the bfd convenient. */
852 struct objfile
*objfile
;
854 /* Linked list of CIEs for this object. */
855 struct dwarf2_cie
*cie
;
857 /* Address size for this unit - from unit header. */
858 unsigned char addr_size
;
860 /* Pointer to the .debug_frame section loaded into memory. */
861 char *dwarf_frame_buffer
;
863 /* Length of the loaded .debug_frame section. */
864 unsigned long dwarf_frame_size
;
866 /* Pointer to the .debug_frame section. */
867 asection
*dwarf_frame_section
;
869 /* Base for DW_EH_PE_datarel encodings. */
872 /* Base for DW_EH_PE_textrel encodings. */
876 const struct objfile_data
*dwarf2_frame_data
;
879 read_1_byte (bfd
*bfd
, char *buf
)
881 return bfd_get_8 (abfd
, (bfd_byte
*) buf
);
885 read_4_bytes (bfd
*abfd
, char *buf
)
887 return bfd_get_32 (abfd
, (bfd_byte
*) buf
);
891 read_8_bytes (bfd
*abfd
, char *buf
)
893 return bfd_get_64 (abfd
, (bfd_byte
*) buf
);
897 read_unsigned_leb128 (bfd
*abfd
, char *buf
, unsigned int *bytes_read_ptr
)
900 unsigned int num_read
;
910 byte
= bfd_get_8 (abfd
, (bfd_byte
*) buf
);
913 result
|= ((byte
& 0x7f) << shift
);
918 *bytes_read_ptr
= num_read
;
924 read_signed_leb128 (bfd
*abfd
, char *buf
, unsigned int *bytes_read_ptr
)
928 unsigned int num_read
;
937 byte
= bfd_get_8 (abfd
, (bfd_byte
*) buf
);
940 result
|= ((byte
& 0x7f) << shift
);
945 if ((shift
< 32) && (byte
& 0x40))
946 result
|= -(1 << shift
);
948 *bytes_read_ptr
= num_read
;
954 read_initial_length (bfd
*abfd
, char *buf
, unsigned int *bytes_read_ptr
)
958 result
= bfd_get_32 (abfd
, (bfd_byte
*) buf
);
959 if (result
== 0xffffffff)
961 result
= bfd_get_64 (abfd
, (bfd_byte
*) buf
+ 4);
962 *bytes_read_ptr
= 12;
971 /* Pointer encoding helper functions. */
973 /* GCC supports exception handling based on DWARF2 CFI. However, for
974 technical reasons, it encodes addresses in its FDE's in a different
975 way. Several "pointer encodings" are supported. The encoding
976 that's used for a particular FDE is determined by the 'R'
977 augmentation in the associated CIE. The argument of this
978 augmentation is a single byte.
980 The address can be encoded as 2 bytes, 4 bytes, 8 bytes, or as a
981 LEB128. This is encoded in bits 0, 1 and 2. Bit 3 encodes whether
982 the address is signed or unsigned. Bits 4, 5 and 6 encode how the
983 address should be interpreted (absolute, relative to the current
984 position in the FDE, ...). Bit 7, indicates that the address
985 should be dereferenced. */
988 encoding_for_size (unsigned int size
)
993 return DW_EH_PE_udata2
;
995 return DW_EH_PE_udata4
;
997 return DW_EH_PE_udata8
;
999 internal_error (__FILE__
, __LINE__
, "Unsupported address size");
1004 size_of_encoded_value (unsigned char encoding
)
1006 if (encoding
== DW_EH_PE_omit
)
1009 switch (encoding
& 0x07)
1011 case DW_EH_PE_absptr
:
1012 return TYPE_LENGTH (builtin_type_void_data_ptr
);
1013 case DW_EH_PE_udata2
:
1015 case DW_EH_PE_udata4
:
1017 case DW_EH_PE_udata8
:
1020 internal_error (__FILE__
, __LINE__
, "Invalid or unsupported encoding");
1025 read_encoded_value (struct comp_unit
*unit
, unsigned char encoding
,
1026 char *buf
, unsigned int *bytes_read_ptr
)
1028 int ptr_len
= size_of_encoded_value (DW_EH_PE_absptr
);
1032 /* GCC currently doesn't generate DW_EH_PE_indirect encodings for
1034 if (encoding
& DW_EH_PE_indirect
)
1035 internal_error (__FILE__
, __LINE__
,
1036 "Unsupported encoding: DW_EH_PE_indirect");
1038 *bytes_read_ptr
= 0;
1040 switch (encoding
& 0x70)
1042 case DW_EH_PE_absptr
:
1045 case DW_EH_PE_pcrel
:
1046 base
= bfd_get_section_vma (unit
->bfd
, unit
->dwarf_frame_section
);
1047 base
+= (buf
- unit
->dwarf_frame_buffer
);
1049 case DW_EH_PE_datarel
:
1052 case DW_EH_PE_textrel
:
1055 case DW_EH_PE_aligned
:
1057 offset
= buf
- unit
->dwarf_frame_buffer
;
1058 if ((offset
% ptr_len
) != 0)
1060 *bytes_read_ptr
= ptr_len
- (offset
% ptr_len
);
1061 buf
+= *bytes_read_ptr
;
1065 internal_error (__FILE__
, __LINE__
, "Invalid or unsupported encoding");
1068 if ((encoding
& 0x0f) == 0x00)
1069 encoding
|= encoding_for_size (ptr_len
);
1071 switch (encoding
& 0x0f)
1073 case DW_EH_PE_udata2
:
1074 *bytes_read_ptr
+= 2;
1075 return (base
+ bfd_get_16 (unit
->abfd
, (bfd_byte
*) buf
));
1076 case DW_EH_PE_udata4
:
1077 *bytes_read_ptr
+= 4;
1078 return (base
+ bfd_get_32 (unit
->abfd
, (bfd_byte
*) buf
));
1079 case DW_EH_PE_udata8
:
1080 *bytes_read_ptr
+= 8;
1081 return (base
+ bfd_get_64 (unit
->abfd
, (bfd_byte
*) buf
));
1082 case DW_EH_PE_sdata2
:
1083 *bytes_read_ptr
+= 2;
1084 return (base
+ bfd_get_signed_16 (unit
->abfd
, (bfd_byte
*) buf
));
1085 case DW_EH_PE_sdata4
:
1086 *bytes_read_ptr
+= 4;
1087 return (base
+ bfd_get_signed_32 (unit
->abfd
, (bfd_byte
*) buf
));
1088 case DW_EH_PE_sdata8
:
1089 *bytes_read_ptr
+= 8;
1090 return (base
+ bfd_get_signed_64 (unit
->abfd
, (bfd_byte
*) buf
));
1092 internal_error (__FILE__
, __LINE__
, "Invalid or unsupported encoding");
1097 /* GCC uses a single CIE for all FDEs in a .debug_frame section.
1098 That's why we use a simple linked list here. */
1100 static struct dwarf2_cie
*
1101 find_cie (struct comp_unit
*unit
, ULONGEST cie_pointer
)
1103 struct dwarf2_cie
*cie
= unit
->cie
;
1107 if (cie
->cie_pointer
== cie_pointer
)
1117 add_cie (struct comp_unit
*unit
, struct dwarf2_cie
*cie
)
1119 cie
->next
= unit
->cie
;
1123 /* Find the FDE for *PC. Return a pointer to the FDE, and store the
1124 inital location associated with it into *PC. */
1126 static struct dwarf2_fde
*
1127 dwarf2_frame_find_fde (CORE_ADDR
*pc
)
1129 struct objfile
*objfile
;
1131 ALL_OBJFILES (objfile
)
1133 struct dwarf2_fde
*fde
;
1136 fde
= objfile_data (objfile
, dwarf2_frame_data
);
1140 gdb_assert (objfile
->section_offsets
);
1141 offset
= ANOFFSET (objfile
->section_offsets
, SECT_OFF_TEXT (objfile
));
1145 if (*pc
>= fde
->initial_location
+ offset
1146 && *pc
< fde
->initial_location
+ offset
+ fde
->address_range
)
1148 *pc
= fde
->initial_location
+ offset
;
1160 add_fde (struct comp_unit
*unit
, struct dwarf2_fde
*fde
)
1162 fde
->next
= objfile_data (unit
->objfile
, dwarf2_frame_data
);
1163 set_objfile_data (unit
->objfile
, dwarf2_frame_data
, fde
);
1166 #ifdef CC_HAS_LONG_LONG
1167 #define DW64_CIE_ID 0xffffffffffffffffULL
1169 #define DW64_CIE_ID ~0
1172 static char *decode_frame_entry (struct comp_unit
*unit
, char *start
,
1175 /* Decode the next CIE or FDE. Return NULL if invalid input, otherwise
1176 the next byte to be processed. */
1178 decode_frame_entry_1 (struct comp_unit
*unit
, char *start
, int eh_frame_p
)
1182 unsigned int bytes_read
;
1185 ULONGEST cie_pointer
;
1189 length
= read_initial_length (unit
->abfd
, buf
, &bytes_read
);
1193 /* Are we still within the section? */
1194 if (end
> unit
->dwarf_frame_buffer
+ unit
->dwarf_frame_size
)
1200 /* Distinguish between 32 and 64-bit encoded frame info. */
1201 dwarf64_p
= (bytes_read
== 12);
1203 /* In a .eh_frame section, zero is used to distinguish CIEs from FDEs. */
1207 cie_id
= DW64_CIE_ID
;
1213 cie_pointer
= read_8_bytes (unit
->abfd
, buf
);
1218 cie_pointer
= read_4_bytes (unit
->abfd
, buf
);
1222 if (cie_pointer
== cie_id
)
1224 /* This is a CIE. */
1225 struct dwarf2_cie
*cie
;
1228 /* Record the offset into the .debug_frame section of this CIE. */
1229 cie_pointer
= start
- unit
->dwarf_frame_buffer
;
1231 /* Check whether we've already read it. */
1232 if (find_cie (unit
, cie_pointer
))
1235 cie
= (struct dwarf2_cie
*)
1236 obstack_alloc (&unit
->objfile
->psymbol_obstack
,
1237 sizeof (struct dwarf2_cie
));
1238 cie
->initial_instructions
= NULL
;
1239 cie
->cie_pointer
= cie_pointer
;
1241 /* The encoding for FDE's in a normal .debug_frame section
1242 depends on the target address size as specified in the
1243 Compilation Unit Header. */
1244 cie
->encoding
= encoding_for_size (unit
->addr_size
);
1246 /* Check version number. */
1247 if (read_1_byte (unit
->abfd
, buf
) != DW_CIE_VERSION
)
1251 /* Interpret the interesting bits of the augmentation. */
1253 buf
= augmentation
+ strlen (augmentation
) + 1;
1255 /* The GCC 2.x "eh" augmentation has a pointer immediately
1256 following the augmentation string, so it must be handled
1258 if (augmentation
[0] == 'e' && augmentation
[1] == 'h')
1261 buf
+= TYPE_LENGTH (builtin_type_void_data_ptr
);
1265 cie
->code_alignment_factor
=
1266 read_unsigned_leb128 (unit
->abfd
, buf
, &bytes_read
);
1269 cie
->data_alignment_factor
=
1270 read_signed_leb128 (unit
->abfd
, buf
, &bytes_read
);
1273 cie
->return_address_register
= read_1_byte (unit
->abfd
, buf
);
1276 cie
->saw_z_augmentation
= (*augmentation
== 'z');
1277 if (cie
->saw_z_augmentation
)
1281 length
= read_unsigned_leb128 (unit
->abfd
, buf
, &bytes_read
);
1285 cie
->initial_instructions
= buf
+ length
;
1289 while (*augmentation
)
1291 /* "L" indicates a byte showing how the LSDA pointer is encoded. */
1292 if (*augmentation
== 'L')
1299 /* "R" indicates a byte indicating how FDE addresses are encoded. */
1300 else if (*augmentation
== 'R')
1302 cie
->encoding
= *buf
++;
1306 /* "P" indicates a personality routine in the CIE augmentation. */
1307 else if (*augmentation
== 'P')
1310 buf
+= size_of_encoded_value (*buf
++);
1314 /* Otherwise we have an unknown augmentation.
1315 Bail out unless we saw a 'z' prefix. */
1318 if (cie
->initial_instructions
== NULL
)
1321 /* Skip unknown augmentations. */
1322 buf
= cie
->initial_instructions
;
1327 cie
->initial_instructions
= buf
;
1330 add_cie (unit
, cie
);
1334 /* This is a FDE. */
1335 struct dwarf2_fde
*fde
;
1337 /* In an .eh_frame section, the CIE pointer is the delta between the
1338 address within the FDE where the CIE pointer is stored and the
1339 address of the CIE. Convert it to an offset into the .eh_frame
1343 cie_pointer
= buf
- unit
->dwarf_frame_buffer
- cie_pointer
;
1344 cie_pointer
-= (dwarf64_p
? 8 : 4);
1347 /* In either case, validate the result is still within the section. */
1348 if (cie_pointer
>= unit
->dwarf_frame_size
)
1351 fde
= (struct dwarf2_fde
*)
1352 obstack_alloc (&unit
->objfile
->psymbol_obstack
,
1353 sizeof (struct dwarf2_fde
));
1354 fde
->cie
= find_cie (unit
, cie_pointer
);
1355 if (fde
->cie
== NULL
)
1357 decode_frame_entry (unit
, unit
->dwarf_frame_buffer
+ cie_pointer
,
1359 fde
->cie
= find_cie (unit
, cie_pointer
);
1362 gdb_assert (fde
->cie
!= NULL
);
1364 fde
->initial_location
=
1365 read_encoded_value (unit
, fde
->cie
->encoding
, buf
, &bytes_read
);
1368 fde
->address_range
=
1369 read_encoded_value (unit
, fde
->cie
->encoding
& 0x0f, buf
, &bytes_read
);
1372 /* A 'z' augmentation in the CIE implies the presence of an
1373 augmentation field in the FDE as well. The only thing known
1374 to be in here at present is the LSDA entry for EH. So we
1375 can skip the whole thing. */
1376 if (fde
->cie
->saw_z_augmentation
)
1380 length
= read_unsigned_leb128 (unit
->abfd
, buf
, &bytes_read
);
1381 buf
+= bytes_read
+ length
;
1386 fde
->instructions
= buf
;
1389 add_fde (unit
, fde
);
1395 /* Read a CIE or FDE in BUF and decode it. */
1397 decode_frame_entry (struct comp_unit
*unit
, char *start
, int eh_frame_p
)
1399 enum { NONE
, ALIGN4
, ALIGN8
, FAIL
} workaround
= NONE
;
1402 ptrdiff_t start_offset
;
1406 ret
= decode_frame_entry_1 (unit
, start
, eh_frame_p
);
1410 /* We have corrupt input data of some form. */
1412 /* ??? Try, weakly, to work around compiler/assembler/linker bugs
1413 and mismatches wrt padding and alignment of debug sections. */
1414 /* Note that there is no requirement in the standard for any
1415 alignment at all in the frame unwind sections. Testing for
1416 alignment before trying to interpret data would be incorrect.
1418 However, GCC traditionally arranged for frame sections to be
1419 sized such that the FDE length and CIE fields happen to be
1420 aligned (in theory, for performance). This, unfortunately,
1421 was done with .align directives, which had the side effect of
1422 forcing the section to be aligned by the linker.
1424 This becomes a problem when you have some other producer that
1425 creates frame sections that are not as strictly aligned. That
1426 produces a hole in the frame info that gets filled by the
1429 The GCC behaviour is arguably a bug, but it's effectively now
1430 part of the ABI, so we're now stuck with it, at least at the
1431 object file level. A smart linker may decide, in the process
1432 of compressing duplicate CIE information, that it can rewrite
1433 the entire output section without this extra padding. */
1435 start_offset
= start
- unit
->dwarf_frame_buffer
;
1436 if (workaround
< ALIGN4
&& (start_offset
& 3) != 0)
1438 start
+= 4 - (start_offset
& 3);
1439 workaround
= ALIGN4
;
1442 if (workaround
< ALIGN8
&& (start_offset
& 7) != 0)
1444 start
+= 8 - (start_offset
& 7);
1445 workaround
= ALIGN8
;
1449 /* Nothing left to try. Arrange to return as if we've consumed
1450 the entire input section. Hopefully we'll get valid info from
1451 the other of .debug_frame/.eh_frame. */
1453 ret
= unit
->dwarf_frame_buffer
+ unit
->dwarf_frame_size
;
1463 complaint (&symfile_complaints
,
1464 "Corrupt data in %s:%s; align 4 workaround apparently succeeded",
1465 unit
->dwarf_frame_section
->owner
->filename
,
1466 unit
->dwarf_frame_section
->name
);
1470 complaint (&symfile_complaints
,
1471 "Corrupt data in %s:%s; align 8 workaround apparently succeeded",
1472 unit
->dwarf_frame_section
->owner
->filename
,
1473 unit
->dwarf_frame_section
->name
);
1477 complaint (&symfile_complaints
,
1478 "Corrupt data in %s:%s",
1479 unit
->dwarf_frame_section
->owner
->filename
,
1480 unit
->dwarf_frame_section
->name
);
1489 /* FIXME: kettenis/20030504: This still needs to be integrated with
1490 dwarf2read.c in a better way. */
1492 /* Imported from dwarf2read.c. */
1493 extern asection
*dwarf_frame_section
;
1494 extern asection
*dwarf_eh_frame_section
;
1496 /* Imported from dwarf2read.c. */
1497 extern char *dwarf2_read_section (struct objfile
*objfile
, asection
*sectp
);
1500 dwarf2_build_frame_info (struct objfile
*objfile
)
1502 struct comp_unit unit
;
1505 /* Build a minimal decoding of the DWARF2 compilation unit. */
1506 unit
.abfd
= objfile
->obfd
;
1507 unit
.objfile
= objfile
;
1508 unit
.addr_size
= objfile
->obfd
->arch_info
->bits_per_address
/ 8;
1512 /* First add the information from the .eh_frame section. That way,
1513 the FDEs from that section are searched last. */
1514 if (dwarf_eh_frame_section
)
1516 asection
*got
, *txt
;
1519 unit
.dwarf_frame_buffer
= dwarf2_read_section (objfile
,
1520 dwarf_eh_frame_section
);
1522 unit
.dwarf_frame_size
1523 = bfd_get_section_size_before_reloc (dwarf_eh_frame_section
);
1524 unit
.dwarf_frame_section
= dwarf_eh_frame_section
;
1526 /* FIXME: kettenis/20030602: This is the DW_EH_PE_datarel base
1527 that is used for the i386/amd64 target, which currently is
1528 the only target in GCC that supports/uses the
1529 DW_EH_PE_datarel encoding. */
1530 got
= bfd_get_section_by_name (unit
.abfd
, ".got");
1532 unit
.dbase
= got
->vma
;
1534 /* GCC emits the DW_EH_PE_textrel encoding type on sh and ia64
1536 txt
= bfd_get_section_by_name (unit
.abfd
, ".text");
1538 unit
.tbase
= txt
->vma
;
1540 frame_ptr
= unit
.dwarf_frame_buffer
;
1541 while (frame_ptr
< unit
.dwarf_frame_buffer
+ unit
.dwarf_frame_size
)
1542 frame_ptr
= decode_frame_entry (&unit
, frame_ptr
, 1);
1545 if (dwarf_frame_section
)
1548 unit
.dwarf_frame_buffer
= dwarf2_read_section (objfile
,
1549 dwarf_frame_section
);
1550 unit
.dwarf_frame_size
1551 = bfd_get_section_size_before_reloc (dwarf_frame_section
);
1552 unit
.dwarf_frame_section
= dwarf_frame_section
;
1554 frame_ptr
= unit
.dwarf_frame_buffer
;
1555 while (frame_ptr
< unit
.dwarf_frame_buffer
+ unit
.dwarf_frame_size
)
1556 frame_ptr
= decode_frame_entry (&unit
, frame_ptr
, 0);
1560 /* Provide a prototype to silence -Wmissing-prototypes. */
1561 void _initialize_dwarf2_frame (void);
1564 _initialize_dwarf2_frame (void)
1566 dwarf2_frame_data
= register_objfile_data ();