1 /* Frame unwinder for frames with DWARF Call Frame Information.
3 Copyright 2003, 2004 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. */
100 struct dwarf2_frame_state
102 /* Each register save state can be described in terms of a CFA slot,
103 another register, or a location expression. */
104 struct dwarf2_frame_state_reg_info
106 struct dwarf2_frame_state_reg
*reg
;
109 /* Used to implement DW_CFA_remember_state. */
110 struct dwarf2_frame_state_reg_info
*prev
;
115 unsigned char *cfa_exp
;
122 /* The PC described by the current frame state. */
125 /* Initial register set from the CIE.
126 Used to implement DW_CFA_restore. */
127 struct dwarf2_frame_state_reg_info initial
;
129 /* The information we care about from the CIE. */
132 ULONGEST retaddr_column
;
135 /* Store the length the expression for the CFA in the `cfa_reg' field,
136 which is unused in that case. */
137 #define cfa_exp_len cfa_reg
139 /* Assert that the register set RS is large enough to store NUM_REGS
140 columns. If necessary, enlarge the register set. */
143 dwarf2_frame_state_alloc_regs (struct dwarf2_frame_state_reg_info
*rs
,
146 size_t size
= sizeof (struct dwarf2_frame_state_reg
);
148 if (num_regs
<= rs
->num_regs
)
151 rs
->reg
= (struct dwarf2_frame_state_reg
*)
152 xrealloc (rs
->reg
, num_regs
* size
);
154 /* Initialize newly allocated registers. */
155 memset (rs
->reg
+ rs
->num_regs
, 0, (num_regs
- rs
->num_regs
) * size
);
156 rs
->num_regs
= num_regs
;
159 /* Copy the register columns in register set RS into newly allocated
160 memory and return a pointer to this newly created copy. */
162 static struct dwarf2_frame_state_reg
*
163 dwarf2_frame_state_copy_regs (struct dwarf2_frame_state_reg_info
*rs
)
165 size_t size
= rs
->num_regs
* sizeof (struct dwarf2_frame_state_reg_info
);
166 struct dwarf2_frame_state_reg
*reg
;
168 reg
= (struct dwarf2_frame_state_reg
*) xmalloc (size
);
169 memcpy (reg
, rs
->reg
, size
);
174 /* Release the memory allocated to register set RS. */
177 dwarf2_frame_state_free_regs (struct dwarf2_frame_state_reg_info
*rs
)
181 dwarf2_frame_state_free_regs (rs
->prev
);
188 /* Release the memory allocated to the frame state FS. */
191 dwarf2_frame_state_free (void *p
)
193 struct dwarf2_frame_state
*fs
= p
;
195 dwarf2_frame_state_free_regs (fs
->initial
.prev
);
196 dwarf2_frame_state_free_regs (fs
->regs
.prev
);
197 xfree (fs
->initial
.reg
);
198 xfree (fs
->regs
.reg
);
203 /* Helper functions for execute_stack_op. */
206 read_reg (void *baton
, int reg
)
208 struct frame_info
*next_frame
= (struct frame_info
*) baton
;
209 struct gdbarch
*gdbarch
= get_frame_arch (next_frame
);
213 regnum
= DWARF2_REG_TO_REGNUM (reg
);
215 buf
= (char *) alloca (register_size (gdbarch
, regnum
));
216 frame_unwind_register (next_frame
, regnum
, buf
);
217 return extract_typed_address (buf
, builtin_type_void_data_ptr
);
221 read_mem (void *baton
, char *buf
, CORE_ADDR addr
, size_t len
)
223 read_memory (addr
, buf
, len
);
227 no_get_frame_base (void *baton
, unsigned char **start
, size_t *length
)
229 internal_error (__FILE__
, __LINE__
,
230 "Support for DW_OP_fbreg is unimplemented");
234 no_get_tls_address (void *baton
, CORE_ADDR offset
)
236 internal_error (__FILE__
, __LINE__
,
237 "Support for DW_OP_GNU_push_tls_address is unimplemented");
241 execute_stack_op (unsigned char *exp
, ULONGEST len
,
242 struct frame_info
*next_frame
, CORE_ADDR initial
)
244 struct dwarf_expr_context
*ctx
;
247 ctx
= new_dwarf_expr_context ();
248 ctx
->baton
= next_frame
;
249 ctx
->read_reg
= read_reg
;
250 ctx
->read_mem
= read_mem
;
251 ctx
->get_frame_base
= no_get_frame_base
;
252 ctx
->get_tls_address
= no_get_tls_address
;
254 dwarf_expr_push (ctx
, initial
);
255 dwarf_expr_eval (ctx
, exp
, len
);
256 result
= dwarf_expr_fetch (ctx
, 0);
259 result
= read_reg (next_frame
, result
);
261 free_dwarf_expr_context (ctx
);
268 execute_cfa_program (unsigned char *insn_ptr
, unsigned char *insn_end
,
269 struct frame_info
*next_frame
,
270 struct dwarf2_frame_state
*fs
)
272 CORE_ADDR pc
= frame_pc_unwind (next_frame
);
275 while (insn_ptr
< insn_end
&& fs
->pc
<= pc
)
277 unsigned char insn
= *insn_ptr
++;
281 if ((insn
& 0xc0) == DW_CFA_advance_loc
)
282 fs
->pc
+= (insn
& 0x3f) * fs
->code_align
;
283 else if ((insn
& 0xc0) == DW_CFA_offset
)
286 insn_ptr
= read_uleb128 (insn_ptr
, insn_end
, &utmp
);
287 offset
= utmp
* fs
->data_align
;
288 dwarf2_frame_state_alloc_regs (&fs
->regs
, reg
+ 1);
289 fs
->regs
.reg
[reg
].how
= DWARF2_FRAME_REG_SAVED_OFFSET
;
290 fs
->regs
.reg
[reg
].loc
.offset
= offset
;
292 else if ((insn
& 0xc0) == DW_CFA_restore
)
294 gdb_assert (fs
->initial
.reg
);
296 dwarf2_frame_state_alloc_regs (&fs
->regs
, reg
+ 1);
297 fs
->regs
.reg
[reg
] = fs
->initial
.reg
[reg
];
304 fs
->pc
= dwarf2_read_address (insn_ptr
, insn_end
, &bytes_read
);
305 insn_ptr
+= bytes_read
;
308 case DW_CFA_advance_loc1
:
309 utmp
= extract_unsigned_integer (insn_ptr
, 1);
310 fs
->pc
+= utmp
* fs
->code_align
;
313 case DW_CFA_advance_loc2
:
314 utmp
= extract_unsigned_integer (insn_ptr
, 2);
315 fs
->pc
+= utmp
* fs
->code_align
;
318 case DW_CFA_advance_loc4
:
319 utmp
= extract_unsigned_integer (insn_ptr
, 4);
320 fs
->pc
+= utmp
* fs
->code_align
;
324 case DW_CFA_offset_extended
:
325 insn_ptr
= read_uleb128 (insn_ptr
, insn_end
, ®
);
326 insn_ptr
= read_uleb128 (insn_ptr
, insn_end
, &utmp
);
327 offset
= utmp
* fs
->data_align
;
328 dwarf2_frame_state_alloc_regs (&fs
->regs
, reg
+ 1);
329 fs
->regs
.reg
[reg
].how
= DWARF2_FRAME_REG_SAVED_OFFSET
;
330 fs
->regs
.reg
[reg
].loc
.offset
= offset
;
333 case DW_CFA_restore_extended
:
334 gdb_assert (fs
->initial
.reg
);
335 insn_ptr
= read_uleb128 (insn_ptr
, insn_end
, ®
);
336 dwarf2_frame_state_alloc_regs (&fs
->regs
, reg
+ 1);
337 fs
->regs
.reg
[reg
] = fs
->initial
.reg
[reg
];
340 case DW_CFA_undefined
:
341 insn_ptr
= read_uleb128 (insn_ptr
, insn_end
, ®
);
342 dwarf2_frame_state_alloc_regs (&fs
->regs
, reg
+ 1);
343 fs
->regs
.reg
[reg
].how
= DWARF2_FRAME_REG_UNDEFINED
;
346 case DW_CFA_same_value
:
347 insn_ptr
= read_uleb128 (insn_ptr
, insn_end
, ®
);
348 dwarf2_frame_state_alloc_regs (&fs
->regs
, reg
+ 1);
349 fs
->regs
.reg
[reg
].how
= DWARF2_FRAME_REG_SAME_VALUE
;
352 case DW_CFA_register
:
353 insn_ptr
= read_uleb128 (insn_ptr
, insn_end
, ®
);
354 insn_ptr
= read_uleb128 (insn_ptr
, insn_end
, &utmp
);
355 dwarf2_frame_state_alloc_regs (&fs
->regs
, reg
+ 1);
356 fs
->regs
.reg
[reg
].how
= DWARF2_FRAME_REG_SAVED_REG
;
357 fs
->regs
.reg
[reg
].loc
.reg
= utmp
;
360 case DW_CFA_remember_state
:
362 struct dwarf2_frame_state_reg_info
*new_rs
;
364 new_rs
= XMALLOC (struct dwarf2_frame_state_reg_info
);
366 fs
->regs
.reg
= dwarf2_frame_state_copy_regs (&fs
->regs
);
367 fs
->regs
.prev
= new_rs
;
371 case DW_CFA_restore_state
:
373 struct dwarf2_frame_state_reg_info
*old_rs
= fs
->regs
.prev
;
377 xfree (fs
->regs
.reg
);
384 insn_ptr
= read_uleb128 (insn_ptr
, insn_end
, &fs
->cfa_reg
);
385 insn_ptr
= read_uleb128 (insn_ptr
, insn_end
, &utmp
);
386 fs
->cfa_offset
= utmp
;
387 fs
->cfa_how
= CFA_REG_OFFSET
;
390 case DW_CFA_def_cfa_register
:
391 insn_ptr
= read_uleb128 (insn_ptr
, insn_end
, &fs
->cfa_reg
);
392 fs
->cfa_how
= CFA_REG_OFFSET
;
395 case DW_CFA_def_cfa_offset
:
396 insn_ptr
= read_uleb128 (insn_ptr
, insn_end
, &fs
->cfa_offset
);
397 /* cfa_how deliberately not set. */
403 case DW_CFA_def_cfa_expression
:
404 insn_ptr
= read_uleb128 (insn_ptr
, insn_end
, &fs
->cfa_exp_len
);
405 fs
->cfa_exp
= insn_ptr
;
406 fs
->cfa_how
= CFA_EXP
;
407 insn_ptr
+= fs
->cfa_exp_len
;
410 case DW_CFA_expression
:
411 insn_ptr
= read_uleb128 (insn_ptr
, insn_end
, ®
);
412 dwarf2_frame_state_alloc_regs (&fs
->regs
, reg
+ 1);
413 insn_ptr
= read_uleb128 (insn_ptr
, insn_end
, &utmp
);
414 fs
->regs
.reg
[reg
].loc
.exp
= insn_ptr
;
415 fs
->regs
.reg
[reg
].exp_len
= utmp
;
416 fs
->regs
.reg
[reg
].how
= DWARF2_FRAME_REG_SAVED_EXP
;
420 case DW_CFA_offset_extended_sf
:
421 insn_ptr
= read_uleb128 (insn_ptr
, insn_end
, ®
);
422 insn_ptr
= read_sleb128 (insn_ptr
, insn_end
, &offset
);
423 offset
+= fs
->data_align
;
424 dwarf2_frame_state_alloc_regs (&fs
->regs
, reg
+ 1);
425 fs
->regs
.reg
[reg
].how
= DWARF2_FRAME_REG_SAVED_OFFSET
;
426 fs
->regs
.reg
[reg
].loc
.offset
= offset
;
429 case DW_CFA_def_cfa_sf
:
430 insn_ptr
= read_uleb128 (insn_ptr
, insn_end
, &fs
->cfa_reg
);
431 insn_ptr
= read_sleb128 (insn_ptr
, insn_end
, &offset
);
432 fs
->cfa_offset
= offset
* fs
->data_align
;
433 fs
->cfa_how
= CFA_REG_OFFSET
;
436 case DW_CFA_def_cfa_offset_sf
:
437 insn_ptr
= read_sleb128 (insn_ptr
, insn_end
, &offset
);
438 fs
->cfa_offset
= offset
* fs
->data_align
;
439 /* cfa_how deliberately not set. */
442 case DW_CFA_GNU_args_size
:
444 insn_ptr
= read_uleb128 (insn_ptr
, insn_end
, &utmp
);
448 internal_error (__FILE__
, __LINE__
, "Unknown CFI encountered.");
453 /* Don't allow remember/restore between CIE and FDE programs. */
454 dwarf2_frame_state_free_regs (fs
->regs
.prev
);
455 fs
->regs
.prev
= NULL
;
458 struct dwarf2_frame_cache
460 /* DWARF Call Frame Address. */
463 /* Saved registers, indexed by GDB register number, not by DWARF
465 struct dwarf2_frame_state_reg
*reg
;
468 /* Initialize the register state REG. If we have a register that acts
469 as a program counter, mark it as a destination for the return
470 address. If we have a register that serves as the stack pointer,
471 arrange for it to be filled with the call frame address (CFA). The
472 other registers are marked as unspecified.
474 We copy the return address to the program counter, since many parts
475 in GDB assume that it is possible to get the return address by
476 unwind the program counter register. However, on ISA's with a
477 dedicated return address register, the CFI usually only contains
478 information to unwind that return address register.
480 The reason we're treating the stack pointer special here is because
481 in many cases GCC doesn't emit CFI for the stack pointer and
482 implicitly assumes that it is equal to the CFA. This makes some
483 sense since the DWARF specification (version 3, draft 8, p. 102)
486 "Typically, the CFA is defined to be the value of the stack pointer
487 at the call site in the previous frame (which may be different from
488 its value on entry to the current frame)."
490 However, this isn't true for all platforms supported by GCC
491 (e.g. IBM S/390 and zSeries). For those targets we should override
492 the defaults given here. */
495 dwarf2_frame_init_reg (struct gdbarch
*gdbarch
, int regnum
,
496 struct dwarf2_frame_state_reg
*reg
)
498 if (regnum
== PC_REGNUM
)
499 reg
->how
= DWARF2_FRAME_REG_RA
;
500 else if (regnum
== SP_REGNUM
)
501 reg
->how
= DWARF2_FRAME_REG_CFA
;
504 static struct dwarf2_frame_cache
*
505 dwarf2_frame_cache (struct frame_info
*next_frame
, void **this_cache
)
507 struct cleanup
*old_chain
;
508 struct gdbarch
*gdbarch
= get_frame_arch (next_frame
);
509 const int num_regs
= NUM_REGS
+ NUM_PSEUDO_REGS
;
510 struct dwarf2_frame_cache
*cache
;
511 struct dwarf2_frame_state
*fs
;
512 struct dwarf2_fde
*fde
;
517 /* Allocate a new cache. */
518 cache
= FRAME_OBSTACK_ZALLOC (struct dwarf2_frame_cache
);
519 cache
->reg
= FRAME_OBSTACK_CALLOC (num_regs
, struct dwarf2_frame_state_reg
);
521 /* Allocate and initialize the frame state. */
522 fs
= XMALLOC (struct dwarf2_frame_state
);
523 memset (fs
, 0, sizeof (struct dwarf2_frame_state
));
524 old_chain
= make_cleanup (dwarf2_frame_state_free
, fs
);
528 Note that if NEXT_FRAME is never supposed to return (i.e. a call
529 to abort), the compiler might optimize away the instruction at
530 NEXT_FRAME's return address. As a result the return address will
531 point at some random instruction, and the CFI for that
532 instruction is probably worthless to us. GCC's unwinder solves
533 this problem by substracting 1 from the return address to get an
534 address in the middle of a presumed call instruction (or the
535 instruction in the associated delay slot). This should only be
536 done for "normal" frames and not for resume-type frames (signal
537 handlers, sentinel frames, dummy frames). The function
538 frame_unwind_address_in_block does just this. It's not clear how
539 reliable the method is though; there is the potential for the
540 register state pre-call being different to that on return. */
541 fs
->pc
= frame_unwind_address_in_block (next_frame
);
543 /* Find the correct FDE. */
544 fde
= dwarf2_frame_find_fde (&fs
->pc
);
545 gdb_assert (fde
!= NULL
);
547 /* Extract any interesting information from the CIE. */
548 fs
->data_align
= fde
->cie
->data_alignment_factor
;
549 fs
->code_align
= fde
->cie
->code_alignment_factor
;
550 fs
->retaddr_column
= fde
->cie
->return_address_register
;
552 /* First decode all the insns in the CIE. */
553 execute_cfa_program (fde
->cie
->initial_instructions
,
554 fde
->cie
->end
, next_frame
, fs
);
556 /* Save the initialized register set. */
557 fs
->initial
= fs
->regs
;
558 fs
->initial
.reg
= dwarf2_frame_state_copy_regs (&fs
->regs
);
560 /* Then decode the insns in the FDE up to our target PC. */
561 execute_cfa_program (fde
->instructions
, fde
->end
, next_frame
, fs
);
563 /* Caclulate the CFA. */
567 cache
->cfa
= read_reg (next_frame
, fs
->cfa_reg
);
568 cache
->cfa
+= fs
->cfa_offset
;
573 execute_stack_op (fs
->cfa_exp
, fs
->cfa_exp_len
, next_frame
, 0);
577 internal_error (__FILE__
, __LINE__
, "Unknown CFA rule.");
580 /* Initialize the register state. */
584 for (regnum
= 0; regnum
< num_regs
; regnum
++)
585 dwarf2_frame_init_reg (gdbarch
, regnum
, &cache
->reg
[regnum
]);
588 /* Go through the DWARF2 CFI generated table and save its register
589 location information in the cache. Note that we don't skip the
590 return address column; it's perfectly all right for it to
591 correspond to a real register. If it doesn't correspond to a
592 real register, or if we shouldn't treat it as such,
593 DWARF2_REG_TO_REGNUM should be defined to return a number outside
594 the range [0, NUM_REGS). */
596 int column
; /* CFI speak for "register number". */
598 for (column
= 0; column
< fs
->regs
.num_regs
; column
++)
600 /* Use the GDB register number as the destination index. */
601 int regnum
= DWARF2_REG_TO_REGNUM (column
);
603 /* If there's no corresponding GDB register, ignore it. */
604 if (regnum
< 0 || regnum
>= num_regs
)
607 /* NOTE: cagney/2003-09-05: CFI should specify the disposition
608 of all debug info registers. If it doesn't, complain (but
609 not too loudly). It turns out that GCC assumes that an
610 unspecified register implies "same value" when CFI (draft
611 7) specifies nothing at all. Such a register could equally
612 be interpreted as "undefined". Also note that this check
613 isn't sufficient; it only checks that all registers in the
614 range [0 .. max column] are specified, and won't detect
615 problems when a debug info register falls outside of the
616 table. We need a way of iterating through all the valid
617 DWARF2 register numbers. */
618 if (fs
->regs
.reg
[column
].how
== DWARF2_FRAME_REG_UNSPECIFIED
)
619 complaint (&symfile_complaints
,
620 "Incomplete CFI data; unspecified registers at 0x%s",
623 cache
->reg
[regnum
] = fs
->regs
.reg
[column
];
627 /* Eliminate any DWARF2_FRAME_REG_RA rules. */
631 for (regnum
= 0; regnum
< num_regs
; regnum
++)
633 if (cache
->reg
[regnum
].how
== DWARF2_FRAME_REG_RA
)
635 struct dwarf2_frame_state_reg
*retaddr_reg
=
636 &fs
->regs
.reg
[fs
->retaddr_column
];
638 /* It seems rather bizarre to specify an "empty" column as
639 the return adress column. However, this is exactly
640 what GCC does on some targets. It turns out that GCC
641 assumes that the return address can be found in the
642 register corresponding to the return address column.
643 Incidentally, that's how should treat a return address
644 column specifying "same value" too. */
645 if (fs
->retaddr_column
< fs
->regs
.num_regs
646 && retaddr_reg
->how
!= DWARF2_FRAME_REG_UNSPECIFIED
647 && retaddr_reg
->how
!= DWARF2_FRAME_REG_SAME_VALUE
)
648 cache
->reg
[regnum
] = *retaddr_reg
;
651 cache
->reg
[regnum
].loc
.reg
= fs
->retaddr_column
;
652 cache
->reg
[regnum
].how
= DWARF2_FRAME_REG_SAVED_REG
;
658 do_cleanups (old_chain
);
665 dwarf2_frame_this_id (struct frame_info
*next_frame
, void **this_cache
,
666 struct frame_id
*this_id
)
668 struct dwarf2_frame_cache
*cache
=
669 dwarf2_frame_cache (next_frame
, this_cache
);
671 (*this_id
) = frame_id_build (cache
->cfa
, frame_func_unwind (next_frame
));
675 dwarf2_frame_prev_register (struct frame_info
*next_frame
, void **this_cache
,
676 int regnum
, int *optimizedp
,
677 enum lval_type
*lvalp
, CORE_ADDR
*addrp
,
678 int *realnump
, void *valuep
)
680 struct gdbarch
*gdbarch
= get_frame_arch (next_frame
);
681 struct dwarf2_frame_cache
*cache
=
682 dwarf2_frame_cache (next_frame
, this_cache
);
684 switch (cache
->reg
[regnum
].how
)
686 case DWARF2_FRAME_REG_UNDEFINED
:
687 /* If CFI explicitly specified that the value isn't defined,
688 mark it as optimized away; the value isn't available. */
695 /* In some cases, for example %eflags on the i386, we have
696 to provide a sane value, even though this register wasn't
697 saved. Assume we can get it from NEXT_FRAME. */
698 frame_unwind_register (next_frame
, regnum
, valuep
);
702 case DWARF2_FRAME_REG_SAVED_OFFSET
:
704 *lvalp
= lval_memory
;
705 *addrp
= cache
->cfa
+ cache
->reg
[regnum
].loc
.offset
;
709 /* Read the value in from memory. */
710 read_memory (*addrp
, valuep
, register_size (gdbarch
, regnum
));
714 case DWARF2_FRAME_REG_SAVED_REG
:
715 regnum
= DWARF2_REG_TO_REGNUM (cache
->reg
[regnum
].loc
.reg
);
716 frame_register_unwind (next_frame
, regnum
,
717 optimizedp
, lvalp
, addrp
, realnump
, valuep
);
720 case DWARF2_FRAME_REG_SAVED_EXP
:
722 *lvalp
= lval_memory
;
723 *addrp
= execute_stack_op (cache
->reg
[regnum
].loc
.exp
,
724 cache
->reg
[regnum
].exp_len
,
725 next_frame
, cache
->cfa
);
729 /* Read the value in from memory. */
730 read_memory (*addrp
, valuep
, register_size (gdbarch
, regnum
));
734 case DWARF2_FRAME_REG_UNSPECIFIED
:
735 /* GCC, in its infinite wisdom decided to not provide unwind
736 information for registers that are "same value". Since
737 DWARF2 (3 draft 7) doesn't define such behavior, said
738 registers are actually undefined (which is different to CFI
739 "undefined"). Code above issues a complaint about this.
740 Here just fudge the books, assume GCC, and that the value is
741 more inner on the stack. */
742 frame_register_unwind (next_frame
, regnum
,
743 optimizedp
, lvalp
, addrp
, realnump
, valuep
);
746 case DWARF2_FRAME_REG_SAME_VALUE
:
747 frame_register_unwind (next_frame
, regnum
,
748 optimizedp
, lvalp
, addrp
, realnump
, valuep
);
751 case DWARF2_FRAME_REG_CFA
:
758 /* Store the value. */
759 store_typed_address (valuep
, builtin_type_void_data_ptr
, cache
->cfa
);
764 internal_error (__FILE__
, __LINE__
, "Unknown register rule.");
768 static const struct frame_unwind dwarf2_frame_unwind
=
771 dwarf2_frame_this_id
,
772 dwarf2_frame_prev_register
775 const struct frame_unwind
*
776 dwarf2_frame_sniffer (struct frame_info
*next_frame
)
778 /* Grab an address that is guarenteed to reside somewhere within the
779 function. frame_pc_unwind(), for a no-return next function, can
780 end up returning something past the end of this function's body. */
781 CORE_ADDR block_addr
= frame_unwind_address_in_block (next_frame
);
782 if (dwarf2_frame_find_fde (&block_addr
))
783 return &dwarf2_frame_unwind
;
789 /* There is no explicitly defined relationship between the CFA and the
790 location of frame's local variables and arguments/parameters.
791 Therefore, frame base methods on this page should probably only be
792 used as a last resort, just to avoid printing total garbage as a
793 response to the "info frame" command. */
796 dwarf2_frame_base_address (struct frame_info
*next_frame
, void **this_cache
)
798 struct dwarf2_frame_cache
*cache
=
799 dwarf2_frame_cache (next_frame
, this_cache
);
804 static const struct frame_base dwarf2_frame_base
=
806 &dwarf2_frame_unwind
,
807 dwarf2_frame_base_address
,
808 dwarf2_frame_base_address
,
809 dwarf2_frame_base_address
812 const struct frame_base
*
813 dwarf2_frame_base_sniffer (struct frame_info
*next_frame
)
815 CORE_ADDR pc
= frame_pc_unwind (next_frame
);
816 if (dwarf2_frame_find_fde (&pc
))
817 return &dwarf2_frame_base
;
822 /* A minimal decoding of DWARF2 compilation units. We only decode
823 what's needed to get to the call frame information. */
827 /* Keep the bfd convenient. */
830 struct objfile
*objfile
;
832 /* Linked list of CIEs for this object. */
833 struct dwarf2_cie
*cie
;
835 /* Address size for this unit - from unit header. */
836 unsigned char addr_size
;
838 /* Pointer to the .debug_frame section loaded into memory. */
839 char *dwarf_frame_buffer
;
841 /* Length of the loaded .debug_frame section. */
842 unsigned long dwarf_frame_size
;
844 /* Pointer to the .debug_frame section. */
845 asection
*dwarf_frame_section
;
847 /* Base for DW_EH_PE_datarel encodings. */
850 /* Base for DW_EH_PE_textrel encodings. */
854 const struct objfile_data
*dwarf2_frame_data
;
857 read_1_byte (bfd
*bfd
, char *buf
)
859 return bfd_get_8 (abfd
, (bfd_byte
*) buf
);
863 read_4_bytes (bfd
*abfd
, char *buf
)
865 return bfd_get_32 (abfd
, (bfd_byte
*) buf
);
869 read_8_bytes (bfd
*abfd
, char *buf
)
871 return bfd_get_64 (abfd
, (bfd_byte
*) buf
);
875 read_unsigned_leb128 (bfd
*abfd
, char *buf
, unsigned int *bytes_read_ptr
)
878 unsigned int num_read
;
888 byte
= bfd_get_8 (abfd
, (bfd_byte
*) buf
);
891 result
|= ((byte
& 0x7f) << shift
);
896 *bytes_read_ptr
= num_read
;
902 read_signed_leb128 (bfd
*abfd
, char *buf
, unsigned int *bytes_read_ptr
)
906 unsigned int num_read
;
915 byte
= bfd_get_8 (abfd
, (bfd_byte
*) buf
);
918 result
|= ((byte
& 0x7f) << shift
);
923 if ((shift
< 32) && (byte
& 0x40))
924 result
|= -(1 << shift
);
926 *bytes_read_ptr
= num_read
;
932 read_initial_length (bfd
*abfd
, char *buf
, unsigned int *bytes_read_ptr
)
936 result
= bfd_get_32 (abfd
, (bfd_byte
*) buf
);
937 if (result
== 0xffffffff)
939 result
= bfd_get_64 (abfd
, (bfd_byte
*) buf
+ 4);
940 *bytes_read_ptr
= 12;
949 /* Pointer encoding helper functions. */
951 /* GCC supports exception handling based on DWARF2 CFI. However, for
952 technical reasons, it encodes addresses in its FDE's in a different
953 way. Several "pointer encodings" are supported. The encoding
954 that's used for a particular FDE is determined by the 'R'
955 augmentation in the associated CIE. The argument of this
956 augmentation is a single byte.
958 The address can be encoded as 2 bytes, 4 bytes, 8 bytes, or as a
959 LEB128. This is encoded in bits 0, 1 and 2. Bit 3 encodes whether
960 the address is signed or unsigned. Bits 4, 5 and 6 encode how the
961 address should be interpreted (absolute, relative to the current
962 position in the FDE, ...). Bit 7, indicates that the address
963 should be dereferenced. */
966 encoding_for_size (unsigned int size
)
971 return DW_EH_PE_udata2
;
973 return DW_EH_PE_udata4
;
975 return DW_EH_PE_udata8
;
977 internal_error (__FILE__
, __LINE__
, "Unsupported address size");
982 size_of_encoded_value (unsigned char encoding
)
984 if (encoding
== DW_EH_PE_omit
)
987 switch (encoding
& 0x07)
989 case DW_EH_PE_absptr
:
990 return TYPE_LENGTH (builtin_type_void_data_ptr
);
991 case DW_EH_PE_udata2
:
993 case DW_EH_PE_udata4
:
995 case DW_EH_PE_udata8
:
998 internal_error (__FILE__
, __LINE__
, "Invalid or unsupported encoding");
1003 read_encoded_value (struct comp_unit
*unit
, unsigned char encoding
,
1004 char *buf
, unsigned int *bytes_read_ptr
)
1006 int ptr_len
= size_of_encoded_value (DW_EH_PE_absptr
);
1010 /* GCC currently doesn't generate DW_EH_PE_indirect encodings for
1012 if (encoding
& DW_EH_PE_indirect
)
1013 internal_error (__FILE__
, __LINE__
,
1014 "Unsupported encoding: DW_EH_PE_indirect");
1016 *bytes_read_ptr
= 0;
1018 switch (encoding
& 0x70)
1020 case DW_EH_PE_absptr
:
1023 case DW_EH_PE_pcrel
:
1024 base
= bfd_get_section_vma (unit
->bfd
, unit
->dwarf_frame_section
);
1025 base
+= (buf
- unit
->dwarf_frame_buffer
);
1027 case DW_EH_PE_datarel
:
1030 case DW_EH_PE_textrel
:
1033 case DW_EH_PE_aligned
:
1035 offset
= buf
- unit
->dwarf_frame_buffer
;
1036 if ((offset
% ptr_len
) != 0)
1038 *bytes_read_ptr
= ptr_len
- (offset
% ptr_len
);
1039 buf
+= *bytes_read_ptr
;
1043 internal_error (__FILE__
, __LINE__
, "Invalid or unsupported encoding");
1046 if ((encoding
& 0x0f) == 0x00)
1047 encoding
|= encoding_for_size (ptr_len
);
1049 switch (encoding
& 0x0f)
1051 case DW_EH_PE_udata2
:
1052 *bytes_read_ptr
+= 2;
1053 return (base
+ bfd_get_16 (unit
->abfd
, (bfd_byte
*) buf
));
1054 case DW_EH_PE_udata4
:
1055 *bytes_read_ptr
+= 4;
1056 return (base
+ bfd_get_32 (unit
->abfd
, (bfd_byte
*) buf
));
1057 case DW_EH_PE_udata8
:
1058 *bytes_read_ptr
+= 8;
1059 return (base
+ bfd_get_64 (unit
->abfd
, (bfd_byte
*) buf
));
1060 case DW_EH_PE_sdata2
:
1061 *bytes_read_ptr
+= 2;
1062 return (base
+ bfd_get_signed_16 (unit
->abfd
, (bfd_byte
*) buf
));
1063 case DW_EH_PE_sdata4
:
1064 *bytes_read_ptr
+= 4;
1065 return (base
+ bfd_get_signed_32 (unit
->abfd
, (bfd_byte
*) buf
));
1066 case DW_EH_PE_sdata8
:
1067 *bytes_read_ptr
+= 8;
1068 return (base
+ bfd_get_signed_64 (unit
->abfd
, (bfd_byte
*) buf
));
1070 internal_error (__FILE__
, __LINE__
, "Invalid or unsupported encoding");
1075 /* GCC uses a single CIE for all FDEs in a .debug_frame section.
1076 That's why we use a simple linked list here. */
1078 static struct dwarf2_cie
*
1079 find_cie (struct comp_unit
*unit
, ULONGEST cie_pointer
)
1081 struct dwarf2_cie
*cie
= unit
->cie
;
1085 if (cie
->cie_pointer
== cie_pointer
)
1095 add_cie (struct comp_unit
*unit
, struct dwarf2_cie
*cie
)
1097 cie
->next
= unit
->cie
;
1101 /* Find the FDE for *PC. Return a pointer to the FDE, and store the
1102 inital location associated with it into *PC. */
1104 static struct dwarf2_fde
*
1105 dwarf2_frame_find_fde (CORE_ADDR
*pc
)
1107 struct objfile
*objfile
;
1109 ALL_OBJFILES (objfile
)
1111 struct dwarf2_fde
*fde
;
1114 fde
= objfile_data (objfile
, dwarf2_frame_data
);
1118 gdb_assert (objfile
->section_offsets
);
1119 offset
= ANOFFSET (objfile
->section_offsets
, SECT_OFF_TEXT (objfile
));
1123 if (*pc
>= fde
->initial_location
+ offset
1124 && *pc
< fde
->initial_location
+ offset
+ fde
->address_range
)
1126 *pc
= fde
->initial_location
+ offset
;
1138 add_fde (struct comp_unit
*unit
, struct dwarf2_fde
*fde
)
1140 fde
->next
= objfile_data (unit
->objfile
, dwarf2_frame_data
);
1141 set_objfile_data (unit
->objfile
, dwarf2_frame_data
, fde
);
1144 #ifdef CC_HAS_LONG_LONG
1145 #define DW64_CIE_ID 0xffffffffffffffffULL
1147 #define DW64_CIE_ID ~0
1150 static char *decode_frame_entry (struct comp_unit
*unit
, char *start
,
1153 /* Decode the next CIE or FDE. Return NULL if invalid input, otherwise
1154 the next byte to be processed. */
1156 decode_frame_entry_1 (struct comp_unit
*unit
, char *start
, int eh_frame_p
)
1160 unsigned int bytes_read
;
1163 ULONGEST cie_pointer
;
1167 length
= read_initial_length (unit
->abfd
, buf
, &bytes_read
);
1171 /* Are we still within the section? */
1172 if (end
> unit
->dwarf_frame_buffer
+ unit
->dwarf_frame_size
)
1178 /* Distinguish between 32 and 64-bit encoded frame info. */
1179 dwarf64_p
= (bytes_read
== 12);
1181 /* In a .eh_frame section, zero is used to distinguish CIEs from FDEs. */
1185 cie_id
= DW64_CIE_ID
;
1191 cie_pointer
= read_8_bytes (unit
->abfd
, buf
);
1196 cie_pointer
= read_4_bytes (unit
->abfd
, buf
);
1200 if (cie_pointer
== cie_id
)
1202 /* This is a CIE. */
1203 struct dwarf2_cie
*cie
;
1206 /* Record the offset into the .debug_frame section of this CIE. */
1207 cie_pointer
= start
- unit
->dwarf_frame_buffer
;
1209 /* Check whether we've already read it. */
1210 if (find_cie (unit
, cie_pointer
))
1213 cie
= (struct dwarf2_cie
*)
1214 obstack_alloc (&unit
->objfile
->objfile_obstack
,
1215 sizeof (struct dwarf2_cie
));
1216 cie
->initial_instructions
= NULL
;
1217 cie
->cie_pointer
= cie_pointer
;
1219 /* The encoding for FDE's in a normal .debug_frame section
1220 depends on the target address size as specified in the
1221 Compilation Unit Header. */
1222 cie
->encoding
= encoding_for_size (unit
->addr_size
);
1224 /* Check version number. */
1225 if (read_1_byte (unit
->abfd
, buf
) != DW_CIE_VERSION
)
1229 /* Interpret the interesting bits of the augmentation. */
1231 buf
= augmentation
+ strlen (augmentation
) + 1;
1233 /* The GCC 2.x "eh" augmentation has a pointer immediately
1234 following the augmentation string, so it must be handled
1236 if (augmentation
[0] == 'e' && augmentation
[1] == 'h')
1239 buf
+= TYPE_LENGTH (builtin_type_void_data_ptr
);
1243 cie
->code_alignment_factor
=
1244 read_unsigned_leb128 (unit
->abfd
, buf
, &bytes_read
);
1247 cie
->data_alignment_factor
=
1248 read_signed_leb128 (unit
->abfd
, buf
, &bytes_read
);
1251 cie
->return_address_register
= read_1_byte (unit
->abfd
, buf
);
1254 cie
->saw_z_augmentation
= (*augmentation
== 'z');
1255 if (cie
->saw_z_augmentation
)
1259 length
= read_unsigned_leb128 (unit
->abfd
, buf
, &bytes_read
);
1263 cie
->initial_instructions
= buf
+ length
;
1267 while (*augmentation
)
1269 /* "L" indicates a byte showing how the LSDA pointer is encoded. */
1270 if (*augmentation
== 'L')
1277 /* "R" indicates a byte indicating how FDE addresses are encoded. */
1278 else if (*augmentation
== 'R')
1280 cie
->encoding
= *buf
++;
1284 /* "P" indicates a personality routine in the CIE augmentation. */
1285 else if (*augmentation
== 'P')
1288 buf
+= size_of_encoded_value (*buf
++);
1292 /* Otherwise we have an unknown augmentation.
1293 Bail out unless we saw a 'z' prefix. */
1296 if (cie
->initial_instructions
== NULL
)
1299 /* Skip unknown augmentations. */
1300 buf
= cie
->initial_instructions
;
1305 cie
->initial_instructions
= buf
;
1308 add_cie (unit
, cie
);
1312 /* This is a FDE. */
1313 struct dwarf2_fde
*fde
;
1315 /* In an .eh_frame section, the CIE pointer is the delta between the
1316 address within the FDE where the CIE pointer is stored and the
1317 address of the CIE. Convert it to an offset into the .eh_frame
1321 cie_pointer
= buf
- unit
->dwarf_frame_buffer
- cie_pointer
;
1322 cie_pointer
-= (dwarf64_p
? 8 : 4);
1325 /* In either case, validate the result is still within the section. */
1326 if (cie_pointer
>= unit
->dwarf_frame_size
)
1329 fde
= (struct dwarf2_fde
*)
1330 obstack_alloc (&unit
->objfile
->objfile_obstack
,
1331 sizeof (struct dwarf2_fde
));
1332 fde
->cie
= find_cie (unit
, cie_pointer
);
1333 if (fde
->cie
== NULL
)
1335 decode_frame_entry (unit
, unit
->dwarf_frame_buffer
+ cie_pointer
,
1337 fde
->cie
= find_cie (unit
, cie_pointer
);
1340 gdb_assert (fde
->cie
!= NULL
);
1342 fde
->initial_location
=
1343 read_encoded_value (unit
, fde
->cie
->encoding
, buf
, &bytes_read
);
1346 fde
->address_range
=
1347 read_encoded_value (unit
, fde
->cie
->encoding
& 0x0f, buf
, &bytes_read
);
1350 /* A 'z' augmentation in the CIE implies the presence of an
1351 augmentation field in the FDE as well. The only thing known
1352 to be in here at present is the LSDA entry for EH. So we
1353 can skip the whole thing. */
1354 if (fde
->cie
->saw_z_augmentation
)
1358 length
= read_unsigned_leb128 (unit
->abfd
, buf
, &bytes_read
);
1359 buf
+= bytes_read
+ length
;
1364 fde
->instructions
= buf
;
1367 add_fde (unit
, fde
);
1373 /* Read a CIE or FDE in BUF and decode it. */
1375 decode_frame_entry (struct comp_unit
*unit
, char *start
, int eh_frame_p
)
1377 enum { NONE
, ALIGN4
, ALIGN8
, FAIL
} workaround
= NONE
;
1380 ptrdiff_t start_offset
;
1384 ret
= decode_frame_entry_1 (unit
, start
, eh_frame_p
);
1388 /* We have corrupt input data of some form. */
1390 /* ??? Try, weakly, to work around compiler/assembler/linker bugs
1391 and mismatches wrt padding and alignment of debug sections. */
1392 /* Note that there is no requirement in the standard for any
1393 alignment at all in the frame unwind sections. Testing for
1394 alignment before trying to interpret data would be incorrect.
1396 However, GCC traditionally arranged for frame sections to be
1397 sized such that the FDE length and CIE fields happen to be
1398 aligned (in theory, for performance). This, unfortunately,
1399 was done with .align directives, which had the side effect of
1400 forcing the section to be aligned by the linker.
1402 This becomes a problem when you have some other producer that
1403 creates frame sections that are not as strictly aligned. That
1404 produces a hole in the frame info that gets filled by the
1407 The GCC behaviour is arguably a bug, but it's effectively now
1408 part of the ABI, so we're now stuck with it, at least at the
1409 object file level. A smart linker may decide, in the process
1410 of compressing duplicate CIE information, that it can rewrite
1411 the entire output section without this extra padding. */
1413 start_offset
= start
- unit
->dwarf_frame_buffer
;
1414 if (workaround
< ALIGN4
&& (start_offset
& 3) != 0)
1416 start
+= 4 - (start_offset
& 3);
1417 workaround
= ALIGN4
;
1420 if (workaround
< ALIGN8
&& (start_offset
& 7) != 0)
1422 start
+= 8 - (start_offset
& 7);
1423 workaround
= ALIGN8
;
1427 /* Nothing left to try. Arrange to return as if we've consumed
1428 the entire input section. Hopefully we'll get valid info from
1429 the other of .debug_frame/.eh_frame. */
1431 ret
= unit
->dwarf_frame_buffer
+ unit
->dwarf_frame_size
;
1441 complaint (&symfile_complaints
,
1442 "Corrupt data in %s:%s; align 4 workaround apparently succeeded",
1443 unit
->dwarf_frame_section
->owner
->filename
,
1444 unit
->dwarf_frame_section
->name
);
1448 complaint (&symfile_complaints
,
1449 "Corrupt data in %s:%s; align 8 workaround apparently succeeded",
1450 unit
->dwarf_frame_section
->owner
->filename
,
1451 unit
->dwarf_frame_section
->name
);
1455 complaint (&symfile_complaints
,
1456 "Corrupt data in %s:%s",
1457 unit
->dwarf_frame_section
->owner
->filename
,
1458 unit
->dwarf_frame_section
->name
);
1467 /* FIXME: kettenis/20030504: This still needs to be integrated with
1468 dwarf2read.c in a better way. */
1470 /* Imported from dwarf2read.c. */
1471 extern asection
*dwarf_frame_section
;
1472 extern asection
*dwarf_eh_frame_section
;
1474 /* Imported from dwarf2read.c. */
1475 extern char *dwarf2_read_section (struct objfile
*objfile
, asection
*sectp
);
1478 dwarf2_build_frame_info (struct objfile
*objfile
)
1480 struct comp_unit unit
;
1483 /* Build a minimal decoding of the DWARF2 compilation unit. */
1484 unit
.abfd
= objfile
->obfd
;
1485 unit
.objfile
= objfile
;
1486 unit
.addr_size
= objfile
->obfd
->arch_info
->bits_per_address
/ 8;
1490 /* First add the information from the .eh_frame section. That way,
1491 the FDEs from that section are searched last. */
1492 if (dwarf_eh_frame_section
)
1494 asection
*got
, *txt
;
1497 unit
.dwarf_frame_buffer
= dwarf2_read_section (objfile
,
1498 dwarf_eh_frame_section
);
1500 unit
.dwarf_frame_size
1501 = bfd_get_section_size_before_reloc (dwarf_eh_frame_section
);
1502 unit
.dwarf_frame_section
= dwarf_eh_frame_section
;
1504 /* FIXME: kettenis/20030602: This is the DW_EH_PE_datarel base
1505 that is used for the i386/amd64 target, which currently is
1506 the only target in GCC that supports/uses the
1507 DW_EH_PE_datarel encoding. */
1508 got
= bfd_get_section_by_name (unit
.abfd
, ".got");
1510 unit
.dbase
= got
->vma
;
1512 /* GCC emits the DW_EH_PE_textrel encoding type on sh and ia64
1514 txt
= bfd_get_section_by_name (unit
.abfd
, ".text");
1516 unit
.tbase
= txt
->vma
;
1518 frame_ptr
= unit
.dwarf_frame_buffer
;
1519 while (frame_ptr
< unit
.dwarf_frame_buffer
+ unit
.dwarf_frame_size
)
1520 frame_ptr
= decode_frame_entry (&unit
, frame_ptr
, 1);
1523 if (dwarf_frame_section
)
1526 unit
.dwarf_frame_buffer
= dwarf2_read_section (objfile
,
1527 dwarf_frame_section
);
1528 unit
.dwarf_frame_size
1529 = bfd_get_section_size_before_reloc (dwarf_frame_section
);
1530 unit
.dwarf_frame_section
= dwarf_frame_section
;
1532 frame_ptr
= unit
.dwarf_frame_buffer
;
1533 while (frame_ptr
< unit
.dwarf_frame_buffer
+ unit
.dwarf_frame_size
)
1534 frame_ptr
= decode_frame_entry (&unit
, frame_ptr
, 0);
1538 /* Provide a prototype to silence -Wmissing-prototypes. */
1539 void _initialize_dwarf2_frame (void);
1542 _initialize_dwarf2_frame (void)
1544 dwarf2_frame_data
= register_objfile_data ();