/usr/src/gnu/usr.bin/binutils/gdb/dwarf2-frame.c

Bug Summary

File:	src/gnu/usr.bin/binutils/gdb/dwarf2-frame.c
Warning:	line 1429, column 16 Access to field 'cie' results in a dereference of a null pointer (loaded from variable 'fde')
Annotated Source Code

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clang -cc1 -cc1 -triple amd64-unknown-openbsd7.0 -analyze -disable-free -disable-llvm-verifier -discard-value-names -main-file-name dwarf2-frame.c -analyzer-store=region -analyzer-opt-analyze-nested-blocks -analyzer-checker=core -analyzer-checker=apiModeling -analyzer-checker=unix -analyzer-checker=deadcode -analyzer-checker=security.insecureAPI.UncheckedReturn -analyzer-checker=security.insecureAPI.getpw -analyzer-checker=security.insecureAPI.gets -analyzer-checker=security.insecureAPI.mktemp -analyzer-checker=security.insecureAPI.mkstemp -analyzer-checker=security.insecureAPI.vfork -analyzer-checker=nullability.NullPassedToNonnull -analyzer-checker=nullability.NullReturnedFromNonnull -analyzer-output plist -w -setup-static-analyzer -mrelocation-model pic -pic-level 1 -pic-is-pie -mframe-pointer=all -relaxed-aliasing -fno-rounding-math -mconstructor-aliases -munwind-tables -target-cpu x86-64 -target-feature +retpoline-indirect-calls -target-feature +retpoline-indirect-branches -tune-cpu generic -debugger-tuning=gdb -fcoverage-compilation-dir=/usr/src/gnu/usr.bin/binutils/obj/gdb -resource-dir /usr/local/lib/clang/13.0.0 -D PIE_DEFAULT=1 -I . -I /usr/src/gnu/usr.bin/binutils/gdb -I /usr/src/gnu/usr.bin/binutils/gdb/config -D LOCALEDIR="/usr/share/locale" -D HAVE_CONFIG_H -I /usr/src/gnu/usr.bin/binutils/gdb/../include/opcode -I ../bfd -I /usr/src/gnu/usr.bin/binutils/gdb/../bfd -I /usr/src/gnu/usr.bin/binutils/gdb/../include -I ../intl -I /usr/src/gnu/usr.bin/binutils/gdb/../intl -D MI_OUT=1 -D TUI=1 -internal-isystem /usr/local/lib/clang/13.0.0/include -internal-externc-isystem /usr/include -O2 -fdebug-compilation-dir=/usr/src/gnu/usr.bin/binutils/obj/gdb -ferror-limit 19 -fwrapv -D_RET_PROTECTOR -ret-protector -fgnuc-version=4.2.1 -fcommon -vectorize-loops -vectorize-slp -fno-builtin-malloc -fno-builtin-calloc -fno-builtin-realloc -fno-builtin-valloc -fno-builtin-free -fno-builtin-strdup -fno-builtin-strndup -analyzer-output=html -faddrsig -D__GCC_HAVE_DWARF2_CFI_ASM=1 -o /home/ben/Projects/vmm/scan-build/2022-01-12-194120-40624-1 -x c /usr/src/gnu/usr.bin/binutils/gdb/dwarf2-frame.c
1/* Frame unwinder for frames with DWARF Call Frame Information.

 Copyright 2003, 2004 Free Software Foundation, Inc.

 Contributed by Mark Kettenis.

 This file is part of GDB.

 This program is free software; you can redistribute it and/or modify
 it under the terms of the GNU General Public License as published by
 the Free Software Foundation; either version 2 of the License, or
 (at your option) any later version.

 This program is distributed in the hope that it will be useful,
 but WITHOUT ANY WARRANTY; without even the implied warranty of
 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 GNU General Public License for more details.

 You should have received a copy of the GNU General Public License
 along with this program; if not, write to the Free Software
 Foundation, Inc., 59 Temple Place - Suite 330,
 Boston, MA 02111-1307, USA.  */

24#include "defs.h"
25#include "dwarf2expr.h"
26#include "elf/dwarf2.h"
27#include "frame.h"
28#include "frame-base.h"
29#include "frame-unwind.h"
30#include "gdbcore.h"
31#include "gdbtypes.h"
32#include "symtab.h"
33#include "objfiles.h"
34#include "regcache.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).  */

46struct dwarf2_cie
47{
/* Offset into the .debug_frame section where this CIE was found.
   Used to identify this CIE.  */
ULONGESTunsigned long cie_pointer;

/* Constant that is factored out of all advance location
   instructions.  */
ULONGESTunsigned long code_alignment_factor;

/* Constants that is factored out of all offset instructions.  */
LONGESTlong data_alignment_factor;

/* Return address column.  */
ULONGESTunsigned long return_address_register;

/* Instruction sequence to initialize a register set.  */
unsigned char *initial_instructions;
unsigned char *end;

/* Encoding of addresses.  */
unsigned char encoding;

/* True if a 'z' augmentation existed.  */
unsigned char saw_z_augmentation;

struct dwarf2_cie *next;
73};

75/* Frame Description Entry (FDE).  */

77struct dwarf2_fde
78{
/* CIE for this FDE.  */
struct dwarf2_cie *cie;

/* First location associated with this FDE.  */
CORE_ADDR initial_location;

/* Number of bytes of program instructions described by this FDE.  */
CORE_ADDR address_range;

/* Instruction sequence.  */
unsigned char *instructions;
unsigned char *end;

struct dwarf2_fde *next;
93};

95static struct dwarf2_fde *dwarf2_frame_find_fde (CORE_ADDR *pc);
96

98/* Structure describing a frame state.  */

100struct dwarf2_frame_state
101{
/* Each register save state can be described in terms of a CFA slot,
   another register, or a location expression.  */
struct dwarf2_frame_state_reg_info
{
  struct dwarf2_frame_state_reg *reg;
  int num_regs;

  /* Used to implement DW_CFA_remember_state.  */
  struct dwarf2_frame_state_reg_info *prev;
} regs;

LONGESTlong cfa_offset;
ULONGESTunsigned long cfa_reg;
unsigned char *cfa_exp;
enum {
  CFA_UNSET,
  CFA_REG_OFFSET,
  CFA_EXP
} cfa_how;

/* The PC described by the current frame state.  */
CORE_ADDR pc;

/* Initial register set from the CIE.
   Used to implement DW_CFA_restore.  */
struct dwarf2_frame_state_reg_info initial;

/* The information we care about from the CIE.  */
LONGESTlong data_align;
ULONGESTunsigned long code_align;
ULONGESTunsigned long retaddr_column;
133};

135/* Store the length the expression for the CFA in the `cfa_reg' field,
 which is unused in that case.  */
137#define cfa_exp_lencfa_reg cfa_reg

139/* Assert that the register set RS is large enough to store NUM_REGS
 columns.  If necessary, enlarge the register set.  */

142static void
143dwarf2_frame_state_alloc_regs (struct dwarf2_frame_state_reg_info *rs,
	       int num_regs)
145{
size_t size = sizeof (struct dwarf2_frame_state_reg);

if (num_regs <= rs->num_regs)
  return;

rs->reg = (struct dwarf2_frame_state_reg *)
  xrealloc (rs->reg, num_regs * size);

/* Initialize newly allocated registers.  */
memset (rs->reg + rs->num_regs, 0, (num_regs - rs->num_regs) * size);
rs->num_regs = num_regs;
157}

159/* Copy the register columns in register set RS into newly allocated
 memory and return a pointer to this newly created copy.  */

162static struct dwarf2_frame_state_reg *
163dwarf2_frame_state_copy_regs (struct dwarf2_frame_state_reg_info *rs)
164{
size_t size = rs->num_regs * sizeof (struct dwarf2_frame_state_reg_info);
struct dwarf2_frame_state_reg *reg;

reg = (struct dwarf2_frame_state_reg *) xmalloc (size);
memcpy (reg, rs->reg, size);

return reg;
172}

174/* Release the memory allocated to register set RS.  */

176static void
177dwarf2_frame_state_free_regs (struct dwarf2_frame_state_reg_info *rs)
178{
if (rs)
  {
    dwarf2_frame_state_free_regs (rs->prev);

    xfree (rs->reg);
    xfree (rs);
  }
186}

188/* Release the memory allocated to the frame state FS.  */

190static void
191dwarf2_frame_state_free (void *p)
192{
struct dwarf2_frame_state *fs = p;

dwarf2_frame_state_free_regs (fs->initial.prev);
dwarf2_frame_state_free_regs (fs->regs.prev);
xfree (fs->initial.reg);
xfree (fs->regs.reg);
xfree (fs);
200}
201

203/* Helper functions for execute_stack_op.  */

205static CORE_ADDR
206read_reg (void *baton, int reg)
207{
struct frame_info *next_frame = (struct frame_info *) baton;
struct gdbarch *gdbarch = get_frame_arch (next_frame);
int regnum;
char *buf;

regnum = DWARF2_REG_TO_REGNUM (reg)(gdbarch_dwarf2_reg_to_regnum (current_gdbarch, reg));

buf = (char *) alloca (register_size (gdbarch, regnum))__builtin_alloca(register_size (gdbarch, regnum));
frame_unwind_register (next_frame, regnum, buf);
return extract_typed_address (buf, builtin_type_void_data_ptr);
218}

220static void
221read_mem (void *baton, char *buf, CORE_ADDR addr, size_t len)
222{
read_memory (addr, buf, len);
224}

226static void
227no_get_frame_base (void *baton, unsigned char **start, size_t *length)
228{
internal_error (__FILE__"/usr/src/gnu/usr.bin/binutils/gdb/dwarf2-frame.c", __LINE__229,
  "Support for DW_OP_fbreg is unimplemented");
231}

233static CORE_ADDR
234no_get_tls_address (void *baton, CORE_ADDR offset)
235{
internal_error (__FILE__"/usr/src/gnu/usr.bin/binutils/gdb/dwarf2-frame.c", __LINE__236,
  "Support for DW_OP_GNU_push_tls_address is unimplemented");
238}

240static CORE_ADDR
241execute_stack_op (unsigned char *exp, ULONGESTunsigned long len,
  struct frame_info *next_frame, CORE_ADDR initial)
243{
struct dwarf_expr_context *ctx;
CORE_ADDR result;

ctx = new_dwarf_expr_context ();
ctx->baton = next_frame;
ctx->read_reg = read_reg;
ctx->read_mem = read_mem;
ctx->get_frame_base = no_get_frame_base;
ctx->get_tls_address = no_get_tls_address;

dwarf_expr_push (ctx, initial);
dwarf_expr_eval (ctx, exp, len);
result = dwarf_expr_fetch (ctx, 0);

if (ctx->in_reg)
  result = read_reg (next_frame, result);

free_dwarf_expr_context (ctx);

return result;
264}
265

267static void
268execute_cfa_program (unsigned char *insn_ptr, unsigned char *insn_end,
     struct frame_info *next_frame,
     struct dwarf2_frame_state *fs)
271{
CORE_ADDR pc = frame_pc_unwind (next_frame);
int bytes_read;

while (insn_ptr < insn_end && fs->pc <= pc)
  {
    unsigned char insn = *insn_ptr++;
    ULONGESTunsigned long utmp, reg;
    LONGESTlong offset;

    if ((insn & 0xc0) == DW_CFA_advance_loc)
fs->pc += (insn & 0x3f) * fs->code_align;
    else if ((insn & 0xc0) == DW_CFA_offset)
{
 reg = insn & 0x3f;
 insn_ptr = read_uleb128 (insn_ptr, insn_end, &utmp);
 offset = utmp * fs->data_align;
 dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1);
 fs->regs.reg[reg].how = DWARF2_FRAME_REG_SAVED_OFFSET;
 fs->regs.reg[reg].loc.offset = offset;
}
    else if ((insn & 0xc0) == DW_CFA_restore)
{
 gdb_assert (fs->initial.reg)((void) ((fs->initial.reg) ? 0 : (internal_error ("/usr/src/gnu/usr.bin/binutils/gdb/dwarf2-frame.c"
, 294, "%s: Assertion `%s' failed.", __PRETTY_FUNCTION__, "fs->initial.reg"
), 0)));
 reg = insn & 0x3f;
 dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1);
 fs->regs.reg[reg] = fs->initial.reg[reg];
}
    else
{
 switch (insn)
   {
   case DW_CFA_set_loc:
     fs->pc = dwarf2_read_address (insn_ptr, insn_end, &bytes_read);
     insn_ptr += bytes_read;
     break;

   case DW_CFA_advance_loc1:
     utmp = extract_unsigned_integer (insn_ptr, 1);
     fs->pc += utmp * fs->code_align;
     insn_ptr++;
     break;
   case DW_CFA_advance_loc2:
     utmp = extract_unsigned_integer (insn_ptr, 2);
     fs->pc += utmp * fs->code_align;
     insn_ptr += 2;
     break;
   case DW_CFA_advance_loc4:
     utmp = extract_unsigned_integer (insn_ptr, 4);
     fs->pc += utmp * fs->code_align;
     insn_ptr += 4;
     break;

   case DW_CFA_offset_extended:
     insn_ptr = read_uleb128 (insn_ptr, insn_end, &reg);
     insn_ptr = read_uleb128 (insn_ptr, insn_end, &utmp);
     offset = utmp * fs->data_align;
     dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1);
     fs->regs.reg[reg].how = DWARF2_FRAME_REG_SAVED_OFFSET;
     fs->regs.reg[reg].loc.offset = offset;
     break;

   case DW_CFA_restore_extended:
     gdb_assert (fs->initial.reg)((void) ((fs->initial.reg) ? 0 : (internal_error ("/usr/src/gnu/usr.bin/binutils/gdb/dwarf2-frame.c"
, 334, "%s: Assertion `%s' failed.", __PRETTY_FUNCTION__, "fs->initial.reg"
), 0)));
     insn_ptr = read_uleb128 (insn_ptr, insn_end, &reg);
     dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1);
     fs->regs.reg[reg] = fs->initial.reg[reg];
     break;

   case DW_CFA_undefined:
     insn_ptr = read_uleb128 (insn_ptr, insn_end, &reg);
     dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1);
     fs->regs.reg[reg].how = DWARF2_FRAME_REG_UNDEFINED;
     break;

   case DW_CFA_same_value:
     insn_ptr = read_uleb128 (insn_ptr, insn_end, &reg);
     dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1);
     fs->regs.reg[reg].how = DWARF2_FRAME_REG_SAME_VALUE;
     break;

   case DW_CFA_register:
     insn_ptr = read_uleb128 (insn_ptr, insn_end, &reg);
     insn_ptr = read_uleb128 (insn_ptr, insn_end, &utmp);
     dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1);
     fs->regs.reg[reg].how = DWARF2_FRAME_REG_SAVED_REG;
     fs->regs.reg[reg].loc.reg = utmp;
     break;

   case DW_CFA_remember_state:
     {
struct dwarf2_frame_state_reg_info *new_rs;

new_rs = XMALLOC (struct dwarf2_frame_state_reg_info)((struct dwarf2_frame_state_reg_info*) xmalloc (sizeof (struct
 dwarf2_frame_state_reg_info)));
*new_rs = fs->regs;
fs->regs.reg = dwarf2_frame_state_copy_regs (&fs->regs);
fs->regs.prev = new_rs;
     }
     break;

   case DW_CFA_restore_state:
     {
struct dwarf2_frame_state_reg_info *old_rs = fs->regs.prev;

if (old_rs == NULL((void*)0))
  {
    complaint (&symfile_complaints, "\
378bad CFI data; mismatched DW_CFA_restore_state at 0x%s", paddr (fs->pc));
  }
else
  {
    xfree (fs->regs.reg);
    fs->regs = *old_rs;
    xfree (old_rs);
  }
     }
     break;

   case DW_CFA_def_cfa:
     insn_ptr = read_uleb128 (insn_ptr, insn_end, &fs->cfa_reg);
     insn_ptr = read_uleb128 (insn_ptr, insn_end, &utmp);
     fs->cfa_offset = utmp;
     fs->cfa_how = CFA_REG_OFFSET;
     break;

   case DW_CFA_def_cfa_register:
     insn_ptr = read_uleb128 (insn_ptr, insn_end, &fs->cfa_reg);
     fs->cfa_how = CFA_REG_OFFSET;
     break;

   case DW_CFA_def_cfa_offset:
     insn_ptr = read_uleb128 (insn_ptr, insn_end, &fs->cfa_offset);
     /* cfa_how deliberately not set.  */
     break;

   case DW_CFA_nop:
     break;

   case DW_CFA_def_cfa_expression:
     insn_ptr = read_uleb128 (insn_ptr, insn_end, &fs->cfa_exp_lencfa_reg);
     fs->cfa_exp = insn_ptr;
     fs->cfa_how = CFA_EXP;
     insn_ptr += fs->cfa_exp_lencfa_reg;
     break;

   case DW_CFA_expression:
     insn_ptr = read_uleb128 (insn_ptr, insn_end, &reg);
     dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1);
     insn_ptr = read_uleb128 (insn_ptr, insn_end, &utmp);
     fs->regs.reg[reg].loc.exp = insn_ptr;
     fs->regs.reg[reg].exp_len = utmp;
     fs->regs.reg[reg].how = DWARF2_FRAME_REG_SAVED_EXP;
     insn_ptr += utmp;
     break;

   case DW_CFA_offset_extended_sf:
     insn_ptr = read_uleb128 (insn_ptr, insn_end, &reg);
     insn_ptr = read_sleb128 (insn_ptr, insn_end, &offset);
     offset *= fs->data_align;
     dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1);
     fs->regs.reg[reg].how = DWARF2_FRAME_REG_SAVED_OFFSET;
     fs->regs.reg[reg].loc.offset = offset;
     break;

   case DW_CFA_def_cfa_sf:
     insn_ptr = read_uleb128 (insn_ptr, insn_end, &fs->cfa_reg);
     insn_ptr = read_sleb128 (insn_ptr, insn_end, &offset);
     fs->cfa_offset = offset * fs->data_align;
     fs->cfa_how = CFA_REG_OFFSET;
     break;

   case DW_CFA_def_cfa_offset_sf:
     insn_ptr = read_sleb128 (insn_ptr, insn_end, &offset);
     fs->cfa_offset = offset * fs->data_align;
     /* cfa_how deliberately not set.  */
     break;

   case DW_CFA_val_expression:
     insn_ptr = read_uleb128 (insn_ptr, insn_end, &reg);
     dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1);
     insn_ptr = read_uleb128 (insn_ptr, insn_end, &utmp);
     fs->regs.reg[reg].loc.exp = insn_ptr;
     fs->regs.reg[reg].exp_len = utmp;
     fs->regs.reg[reg].how = DWARF2_FRAME_REG_SAVED_VAL_EXP;
     insn_ptr += utmp;
     break;

   case DW_CFA_GNU_args_size:
     /* Ignored.  */
     insn_ptr = read_uleb128 (insn_ptr, insn_end, &utmp);
     break;

   default:
     internal_error (__FILE__"/usr/src/gnu/usr.bin/binutils/gdb/dwarf2-frame.c", __LINE__464, "Unknown CFI encountered.");
   }
}
  }

/* Don't allow remember/restore between CIE and FDE programs.  */
dwarf2_frame_state_free_regs (fs->regs.prev);
fs->regs.prev = NULL((void*)0);
472}
473

475/* Architecture-specific operations.  */

477/* Per-architecture data key.  */
478static struct gdbarch_data *dwarf2_frame_data;

480struct dwarf2_frame_ops
481{
/* Pre-initialize the register state REG for register REGNUM.  */
void (*init_reg) (struct gdbarch *, int, struct dwarf2_frame_state_reg *);
484};

486/* Default architecture-specific register state initialization
 function.  */

489static void
490dwarf2_frame_default_init_reg (struct gdbarch *gdbarch, int regnum,
	       struct dwarf2_frame_state_reg *reg)
492{
/* If we have a register that acts as a program counter, mark it as
   a destination for the return address.  If we have a register that
   serves as the stack pointer, arrange for it to be filled with the
   call frame address (CFA).  The other registers are marked as
   unspecified.

   We copy the return address to the program counter, since many
   parts in GDB assume that it is possible to get the return address
   by unwinding the program counter register.  However, on ISA's
   with a dedicated return address register, the CFI usually only
   contains information to unwind that return address register.

   The reason we're treating the stack pointer special here is
   because in many cases GCC doesn't emit CFI for the stack pointer
   and implicitly assumes that it is equal to the CFA.  This makes
   some sense since the DWARF specification (version 3, draft 8,
   p. 102) says that:

   "Typically, the CFA is defined to be the value of the stack
   pointer at the call site in the previous frame (which may be
   different from its value on entry to the current frame)."

   However, this isn't true for all platforms supported by GCC
   (e.g. IBM S/390 and zSeries).  Those architectures should provide
   their own architecture-specific initialization function.  */

if (regnum == PC_REGNUM(gdbarch_pc_regnum (current_gdbarch)))
  reg->how = DWARF2_FRAME_REG_RA;
else if (regnum == SP_REGNUM(gdbarch_sp_regnum (current_gdbarch)))
  reg->how = DWARF2_FRAME_REG_CFA;
523}

525/* Return a default for the architecture-specific operations.  */

527static void *
528dwarf2_frame_init (struct obstack *obstack)
529{
struct dwarf2_frame_ops *ops;

ops = OBSTACK_ZALLOC (obstack, struct dwarf2_frame_ops)(memset (__extension__ ({ struct obstack *__h = ((obstack)); __extension__
 ({ struct obstack *__o = (__h); int __len = ((sizeof (struct
 dwarf2_frame_ops))); if (__o->chunk_limit - __o->next_free
 < __len) _obstack_newchunk (__o, __len); ((__o)->next_free
 += (__len)); (void) 0; }); __extension__ ({ struct obstack *
__o1 = (__h); void *value; value = (void *) __o1->object_base
; if (__o1->next_free == value) __o1->maybe_empty_object
 = 1; __o1->next_free = (((((__o1->next_free) - (char *
) 0)+__o1->alignment_mask) & ~ (__o1->alignment_mask
)) + (char *) 0); if (__o1->next_free - (char *)__o1->chunk
 > __o1->chunk_limit - (char *)__o1->chunk) __o1->
next_free = __o1->chunk_limit; __o1->object_base = __o1
->next_free; value; }); }), 0, sizeof (struct dwarf2_frame_ops
)));
ops->init_reg = dwarf2_frame_default_init_reg;
return ops;
535}

537/* Set the architecture-specific register state initialization
 function for GDBARCH to INIT_REG.  */

540void
541dwarf2_frame_set_init_reg (struct gdbarch *gdbarch,
	   void (*init_reg) (struct gdbarch *, int,
			     struct dwarf2_frame_state_reg *))
544{
struct dwarf2_frame_ops *ops = gdbarch_data (gdbarch, dwarf2_frame_data);

ops->init_reg = init_reg;
548}

550/* Pre-initialize the register state REG for register REGNUM.  */

552static void
553dwarf2_frame_init_reg (struct gdbarch *gdbarch, int regnum,
       struct dwarf2_frame_state_reg *reg)
555{
struct dwarf2_frame_ops *ops = gdbarch_data (gdbarch, dwarf2_frame_data);

ops->init_reg (gdbarch, regnum, reg);
559}
560

562struct dwarf2_frame_cache
563{
/* DWARF Call Frame Address.  */
CORE_ADDR cfa;

/* Saved registers, indexed by GDB register number, not by DWARF
   register number.  */
struct dwarf2_frame_state_reg *reg;
570};

572static struct dwarf2_frame_cache *
573dwarf2_frame_cache (struct frame_info *next_frame, void **this_cache)
574{
struct cleanup *old_chain;
struct gdbarch *gdbarch = get_frame_arch (next_frame);
const int num_regs = NUM_REGS(gdbarch_num_regs (current_gdbarch)) + NUM_PSEUDO_REGS(gdbarch_num_pseudo_regs (current_gdbarch));
struct dwarf2_frame_cache *cache;
struct dwarf2_frame_state *fs;
struct dwarf2_fde *fde;

if (*this_cache)
  return *this_cache;

/* Allocate a new cache.  */
cache = FRAME_OBSTACK_ZALLOC (struct dwarf2_frame_cache)((struct dwarf2_frame_cache *) frame_obstack_zalloc (sizeof (
struct dwarf2_frame_cache)));
cache->reg = FRAME_OBSTACK_CALLOC (num_regs, struct dwarf2_frame_state_reg)((struct dwarf2_frame_state_reg *) frame_obstack_zalloc ((num_regs
) * sizeof (struct dwarf2_frame_state_reg)));

/* Allocate and initialize the frame state.  */
fs = XMALLOC (struct dwarf2_frame_state)((struct dwarf2_frame_state*) xmalloc (sizeof (struct dwarf2_frame_state
)));
memset (fs, 0, sizeof (struct dwarf2_frame_state));
old_chain = make_cleanup (dwarf2_frame_state_free, fs);

/* Unwind the PC.

   Note that if NEXT_FRAME is never supposed to return (i.e. a call
   to abort), the compiler might optimize away the instruction at
   NEXT_FRAME's return address.  As a result the return address will
   point at some random instruction, and the CFI for that
   instruction is probably worthless to us.  GCC's unwinder solves
   this problem by substracting 1 from the return address to get an
   address in the middle of a presumed call instruction (or the
   instruction in the associated delay slot).  This should only be
   done for "normal" frames and not for resume-type frames (signal
   handlers, sentinel frames, dummy frames).  The function
   frame_unwind_address_in_block does just this.  It's not clear how
   reliable the method is though; there is the potential for the
   register state pre-call being different to that on return.  */
fs->pc = frame_unwind_address_in_block (next_frame);

/* Find the correct FDE.  */
fde = dwarf2_frame_find_fde (&fs->pc);
gdb_assert (fde != NULL)((void) ((fde != ((void*)0)) ? 0 : (internal_error ("/usr/src/gnu/usr.bin/binutils/gdb/dwarf2-frame.c"
, 613, "%s: Assertion `%s' failed.", __PRETTY_FUNCTION__, "fde != NULL"
), 0)));

/* Extract any interesting information from the CIE.  */
fs->data_align = fde->cie->data_alignment_factor;
fs->code_align = fde->cie->code_alignment_factor;
fs->retaddr_column = fde->cie->return_address_register;

/* First decode all the insns in the CIE.  */
execute_cfa_program (fde->cie->initial_instructions,
       fde->cie->end, next_frame, fs);

/* Save the initialized register set.  */
fs->initial = fs->regs;
fs->initial.reg = dwarf2_frame_state_copy_regs (&fs->regs);

/* Then decode the insns in the FDE up to our target PC.  */
execute_cfa_program (fde->instructions, fde->end, next_frame, fs);

/* Caclulate the CFA.  */
switch (fs->cfa_how)
  {
  case CFA_REG_OFFSET:
    cache->cfa = read_reg (next_frame, fs->cfa_reg);
    cache->cfa += fs->cfa_offset;
    break;

  case CFA_EXP:
    cache->cfa =
execute_stack_op (fs->cfa_exp, fs->cfa_exp_lencfa_reg, next_frame, 0);
    break;

  default:
    internal_error (__FILE__"/usr/src/gnu/usr.bin/binutils/gdb/dwarf2-frame.c", __LINE__645, "Unknown CFA rule.");
  }

/* Initialize the register state.  */
{
  int regnum;

  for (regnum = 0; regnum < num_regs; regnum++)
    dwarf2_frame_init_reg (gdbarch, regnum, &cache->reg[regnum]);
}

/* Go through the DWARF2 CFI generated table and save its register
   location information in the cache.  Note that we don't skip the
   return address column; it's perfectly all right for it to
   correspond to a real register.  If it doesn't correspond to a
   real register, or if we shouldn't treat it as such,
   DWARF2_REG_TO_REGNUM should be defined to return a number outside
   the range [0, NUM_REGS).  */
{
  int column;		/* CFI speak for "register number".  */

  for (column = 0; column < fs->regs.num_regs; column++)
    {
/* Use the GDB register number as the destination index.  */
int regnum = DWARF2_REG_TO_REGNUM (column)(gdbarch_dwarf2_reg_to_regnum (current_gdbarch, column));

/* If there's no corresponding GDB register, ignore it.  */
if (regnum < 0 || regnum >= num_regs)
 continue;

/* NOTE: cagney/2003-09-05: CFI should specify the disposition
  of all debug info registers.  If it doesn't, complain (but
  not too loudly).  It turns out that GCC assumes that an
  unspecified register implies "same value" when CFI (draft
  7) specifies nothing at all.  Such a register could equally
  be interpreted as "undefined".  Also note that this check
  isn't sufficient; it only checks that all registers in the
  range [0 .. max column] are specified, and won't detect
  problems when a debug info register falls outside of the
  table.  We need a way of iterating through all the valid
  DWARF2 register numbers.  */
if (fs->regs.reg[column].how == DWARF2_FRAME_REG_UNSPECIFIED)
 complaint (&symfile_complaints,
     "Incomplete CFI data; unspecified registers at 0x%s",
     paddr (fs->pc));
else
 cache->reg[regnum] = fs->regs.reg[column];
    }
}

/* Eliminate any DWARF2_FRAME_REG_RA rules.  */
{
  int regnum;

  for (regnum = 0; regnum < num_regs; regnum++)
    {
if (cache->reg[regnum].how == DWARF2_FRAME_REG_RA)
 {
   struct dwarf2_frame_state_reg *retaddr_reg =
     &fs->regs.reg[fs->retaddr_column];

   /* It seems rather bizarre to specify an "empty" column as
             the return adress column.  However, this is exactly
             what GCC does on some targets.  It turns out that GCC
             assumes that the return address can be found in the
             register corresponding to the return address column.
             Incidentally, that's how should treat a return address
             column specifying "same value" too.  */
   if (fs->retaddr_column < fs->regs.num_regs
&& retaddr_reg->how != DWARF2_FRAME_REG_UNSPECIFIED
&& retaddr_reg->how != DWARF2_FRAME_REG_SAME_VALUE)
     cache->reg[regnum] = *retaddr_reg;
   else
     {
cache->reg[regnum].loc.reg = fs->retaddr_column;
cache->reg[regnum].how = DWARF2_FRAME_REG_SAVED_REG;
     }
 }
    }
}

do_cleanups (old_chain);

*this_cache = cache;
return cache;
730}

732static void
733dwarf2_frame_this_id (struct frame_info *next_frame, void **this_cache,
      struct frame_id *this_id)
735{
struct dwarf2_frame_cache *cache =
  dwarf2_frame_cache (next_frame, this_cache);

(*this_id) = frame_id_build (cache->cfa, frame_func_unwind (next_frame));
740}

742static void
743dwarf2_frame_prev_register (struct frame_info *next_frame, void **this_cache,
	    int regnum, int *optimizedp,
	    enum lval_type *lvalp, CORE_ADDR *addrp,
	    int *realnump, void *valuep)
747{
struct gdbarch *gdbarch = get_frame_arch (next_frame);
struct dwarf2_frame_cache *cache =
  dwarf2_frame_cache (next_frame, this_cache);
CORE_ADDR value;

switch (cache->reg[regnum].how)
  {
  case DWARF2_FRAME_REG_UNDEFINED:
    /* If CFI explicitly specified that the value isn't defined,
mark it as optimized away; the value isn't available.  */
    *optimizedp = 1;
    *lvalp = not_lval;
    *addrp = 0;
    *realnump = -1;
    if (valuep)
{
 /* In some cases, for example %eflags on the i386, we have
    to provide a sane value, even though this register wasn't
    saved.  Assume we can get it from NEXT_FRAME.  */
 frame_unwind_register (next_frame, regnum, valuep);
}
    break;

  case DWARF2_FRAME_REG_SAVED_OFFSET:
    *optimizedp = 0;
    *lvalp = lval_memory;
    *addrp = cache->cfa + cache->reg[regnum].loc.offset;
    *realnump = -1;
    if (valuep)
{
 /* Read the value in from memory.  */
 read_memory (*addrp, valuep, register_size (gdbarch, regnum));
}
    break;

  case DWARF2_FRAME_REG_SAVED_REG:
    regnum = DWARF2_REG_TO_REGNUM (cache->reg[regnum].loc.reg)(gdbarch_dwarf2_reg_to_regnum (current_gdbarch, cache->reg
[regnum].loc.reg));
    frame_register_unwind (next_frame, regnum,
	     optimizedp, lvalp, addrp, realnump, valuep);
    break;

  case DWARF2_FRAME_REG_SAVED_EXP:
    *optimizedp = 0;
    *lvalp = lval_memory;
    *addrp = execute_stack_op (cache->reg[regnum].loc.exp,
		 cache->reg[regnum].exp_len,
		 next_frame, cache->cfa);
    *realnump = -1;
    if (valuep)
{
 /* Read the value in from memory.  */
 read_memory (*addrp, valuep, register_size (gdbarch, regnum));
}
    break;

  case DWARF2_FRAME_REG_SAVED_VAL_EXP:
    *optimizedp = 0;
    *lvalp = not_lval;
    *addrp = 0;
    value = execute_stack_op (cache->reg[regnum].loc.exp,
		cache->reg[regnum].exp_len,
		next_frame, cache->cfa);
    *realnump = -1;
    if (valuep)
{
 /* Store the value.  */
 store_typed_address (valuep, builtin_type_void_data_ptr, value);
}
    break;

  case DWARF2_FRAME_REG_UNSPECIFIED:
    /* GCC, in its infinite wisdom decided to not provide unwind
information for registers that are "same value".  Since
DWARF2 (3 draft 7) doesn't define such behavior, said
registers are actually undefined (which is different to CFI
"undefined").  Code above issues a complaint about this.
Here just fudge the books, assume GCC, and that the value is
more inner on the stack.  */
    frame_register_unwind (next_frame, regnum,
	     optimizedp, lvalp, addrp, realnump, valuep);
    break;

  case DWARF2_FRAME_REG_SAME_VALUE:
    frame_register_unwind (next_frame, regnum,
	     optimizedp, lvalp, addrp, realnump, valuep);
    break;

  case DWARF2_FRAME_REG_CFA:
    *optimizedp = 0;
    *lvalp = not_lval;
    *addrp = 0;
    *realnump = -1;
    if (valuep)
{
 /* Store the value.  */
 store_typed_address (valuep, builtin_type_void_data_ptr, cache->cfa);
}
    break;

  default:
    internal_error (__FILE__"/usr/src/gnu/usr.bin/binutils/gdb/dwarf2-frame.c", __LINE__848, "Unknown register rule.");
  }
850}

852static const struct frame_unwind dwarf2_frame_unwind =
853{
NORMAL_FRAME,
dwarf2_frame_this_id,
dwarf2_frame_prev_register
857};

859const struct frame_unwind *
860dwarf2_frame_sniffer (struct frame_info *next_frame)
861{
/* Grab an address that is guarenteed to reside somewhere within the
   function.  frame_pc_unwind(), for a no-return next function, can
   end up returning something past the end of this function's body.  */
CORE_ADDR block_addr = frame_unwind_address_in_block (next_frame);
if (dwarf2_frame_find_fde (&block_addr))
  return &dwarf2_frame_unwind;

return NULL((void*)0);
870}
871

873/* There is no explicitly defined relationship between the CFA and the
 location of frame's local variables and arguments/parameters.
 Therefore, frame base methods on this page should probably only be
 used as a last resort, just to avoid printing total garbage as a
 response to the "info frame" command.  */

879static CORE_ADDR
880dwarf2_frame_base_address (struct frame_info *next_frame, void **this_cache)
881{
struct dwarf2_frame_cache *cache =
  dwarf2_frame_cache (next_frame, this_cache);

return cache->cfa;
886}

888static const struct frame_base dwarf2_frame_base =
889{
&dwarf2_frame_unwind,
dwarf2_frame_base_address,
dwarf2_frame_base_address,
dwarf2_frame_base_address
894};

896const struct frame_base *
897dwarf2_frame_base_sniffer (struct frame_info *next_frame)
898{
CORE_ADDR pc = frame_pc_unwind (next_frame);
if (dwarf2_frame_find_fde (&pc))
  return &dwarf2_frame_base;

return NULL((void*)0);
904}
905
906/* A minimal decoding of DWARF2 compilation units.  We only decode
 what's needed to get to the call frame information.  */

909struct comp_unit
910{
/* Keep the bfd convenient.  */
bfd *abfd;

struct objfile *objfile;

/* Linked list of CIEs for this object.  */
struct dwarf2_cie *cie;

/* Pointer to the .debug_frame section loaded into memory.  */
char *dwarf_frame_buffer;

/* Length of the loaded .debug_frame section.  */
unsigned long dwarf_frame_size;

/* Pointer to the .debug_frame section.  */
asection *dwarf_frame_section;

/* Base for DW_EH_PE_datarel encodings.  */
bfd_vma dbase;

/* Base for DW_EH_PE_textrel encodings.  */
bfd_vma tbase;
933};

935const struct objfile_data *dwarf2_frame_objfile_data;

937static unsigned int
938read_1_byte (bfd *bfd, char *buf)
939{
return bfd_get_8 (abfd, (bfd_byte *) buf)(*(unsigned char *) ((bfd_byte *) buf) & 0xff);
941}

943static unsigned int
944read_4_bytes (bfd *abfd, char *buf)
945{
return bfd_get_32 (abfd, (bfd_byte *) buf)((*((abfd)->xvec->bfd_getx32)) ((bfd_byte *) buf));
947}

949static ULONGESTunsigned long
950read_8_bytes (bfd *abfd, char *buf)
951{
return bfd_get_64 (abfd, (bfd_byte *) buf)((*((abfd)->xvec->bfd_getx64)) ((bfd_byte *) buf));
953}

955static ULONGESTunsigned long
956read_unsigned_leb128 (bfd *abfd, char *buf, unsigned int *bytes_read_ptr)
957{
ULONGESTunsigned long result;
unsigned int num_read;
int shift;
unsigned char byte;

result = 0;
shift = 0;
num_read = 0;

do
  {
    byte = bfd_get_8 (abfd, (bfd_byte *) buf)(*(unsigned char *) ((bfd_byte *) buf) & 0xff);
    buf++;
    num_read++;
    result |= ((byte & 0x7f) << shift);
    shift += 7;
  }
while (byte & 0x80);

*bytes_read_ptr = num_read;

return result;
980}

982static LONGESTlong
983read_signed_leb128 (bfd *abfd, char *buf, unsigned int *bytes_read_ptr)
984{
LONGESTlong result;
int shift;
unsigned int num_read;
unsigned char byte;

result = 0;
shift = 0;
num_read = 0;

do
  {
    byte = bfd_get_8 (abfd, (bfd_byte *) buf)(*(unsigned char *) ((bfd_byte *) buf) & 0xff);
    buf++;
    num_read++;
    result |= ((byte & 0x7f) << shift);
    shift += 7;
  }
while (byte & 0x80);

if ((shift < 32) && (byte & 0x40))
  result |= -(1 << shift);

*bytes_read_ptr = num_read;

return result;
1010}

1012static ULONGESTunsigned long
1013read_initial_length (bfd *abfd, char *buf, unsigned int *bytes_read_ptr)
1014{
LONGESTlong result;

result = bfd_get_32 (abfd, (bfd_byte *) buf)((*((abfd)->xvec->bfd_getx32)) ((bfd_byte *) buf));
if (result == 0xffffffff)
  {
    result = bfd_get_64 (abfd, (bfd_byte *) buf + 4)((*((abfd)->xvec->bfd_getx64)) ((bfd_byte *) buf + 4));
    *bytes_read_ptr = 12;
  }
else
  *bytes_read_ptr = 4;

return result;
1027}
1028

1030/* Pointer encoding helper functions.  */

1032/* GCC supports exception handling based on DWARF2 CFI.  However, for
 technical reasons, it encodes addresses in its FDE's in a different
 way.  Several "pointer encodings" are supported.  The encoding
 that's used for a particular FDE is determined by the 'R'
 augmentation in the associated CIE.  The argument of this
 augmentation is a single byte.  

 The address can be encoded as 2 bytes, 4 bytes, 8 bytes, or as a
 LEB128.  This is encoded in bits 0, 1 and 2.  Bit 3 encodes whether
 the address is signed or unsigned.  Bits 4, 5 and 6 encode how the
 address should be interpreted (absolute, relative to the current
 position in the FDE, ...).  Bit 7, indicates that the address
 should be dereferenced.  */

1046static unsigned char
1047encoding_for_size (unsigned int size)
1048{
switch (size)
  {
  case 2:
    return DW_EH_PE_udata20x02;
  case 4:
    return DW_EH_PE_udata40x03;
  case 8:
    return DW_EH_PE_udata80x04;
  default:
    internal_error (__FILE__"/usr/src/gnu/usr.bin/binutils/gdb/dwarf2-frame.c", __LINE__1058, "Unsupported address size");
  }
1060}

1062static unsigned int
1063size_of_encoded_value (unsigned char encoding)
1064{
if (encoding == DW_EH_PE_omit0xff)
  return 0;

switch (encoding & 0x07)
  {
  case DW_EH_PE_absptr0x00:
    return TYPE_LENGTH (builtin_type_void_data_ptr)(builtin_type_void_data_ptr)->length;
  case DW_EH_PE_udata20x02:
    return 2;
  case DW_EH_PE_udata40x03:
    return 4;
  case DW_EH_PE_udata80x04:
    return 8;
  default:
    internal_error (__FILE__"/usr/src/gnu/usr.bin/binutils/gdb/dwarf2-frame.c", __LINE__1079, "Invalid or unsupported encoding");
  }
1081}

1083static CORE_ADDR
1084read_encoded_value (struct comp_unit *unit, unsigned char encoding,
    char *buf, unsigned int *bytes_read_ptr)
1086{
int ptr_len = size_of_encoded_value (DW_EH_PE_absptr0x00);
ptrdiff_t offset;
CORE_ADDR base;

/* GCC currently doesn't generate DW_EH_PE_indirect encodings for
   FDE's.  */
if (encoding & DW_EH_PE_indirect0x80)
  internal_error (__FILE__"/usr/src/gnu/usr.bin/binutils/gdb/dwarf2-frame.c", __LINE__1094, 
    "Unsupported encoding: DW_EH_PE_indirect");

*bytes_read_ptr = 0;

switch (encoding & 0x70)
  {
  case DW_EH_PE_absptr0x00:
    base = 0;
    break;
  case DW_EH_PE_pcrel0x10:
    base = bfd_get_section_vma (unit->bfd, unit->dwarf_frame_section)((unit->dwarf_frame_section)->vma + 0);
    base += (buf - unit->dwarf_frame_buffer);
    break;
  case DW_EH_PE_datarel0x30:
    base = unit->dbase;
    break;
  case DW_EH_PE_textrel0x20:
    base = unit->tbase;
    break;
  case DW_EH_PE_funcrel0x40:
    /* FIXME: kettenis/20040501: For now just pretend
       DW_EH_PE_funcrel is equivalent to DW_EH_PE_absptr.  For
       reading the initial location of an FDE it should be treated
       as such, and currently that's the only place where this code
       is used.  */
    base = 0;
    break;
  case DW_EH_PE_aligned0x50:
    base = 0;
    offset = buf - unit->dwarf_frame_buffer;
    if ((offset % ptr_len) != 0)
{
 *bytes_read_ptr = ptr_len - (offset % ptr_len);
 buf += *bytes_read_ptr;
}
    break;
  default:
    internal_error (__FILE__"/usr/src/gnu/usr.bin/binutils/gdb/dwarf2-frame.c", __LINE__1132, "Invalid or unsupported encoding");
  }

if ((encoding & 0x07) == 0x00)
  encoding |= encoding_for_size (ptr_len);

switch (encoding & 0x0f)
  {
  case DW_EH_PE_udata20x02:
    *bytes_read_ptr += 2;
    return (base + bfd_get_16 (unit->abfd, (bfd_byte *) buf)((*((unit->abfd)->xvec->bfd_getx16)) ((bfd_byte *) buf
)));
  case DW_EH_PE_udata40x03:
    *bytes_read_ptr += 4;
    return (base + bfd_get_32 (unit->abfd, (bfd_byte *) buf)((*((unit->abfd)->xvec->bfd_getx32)) ((bfd_byte *) buf
)));
  case DW_EH_PE_udata80x04:
    *bytes_read_ptr += 8;
    return (base + bfd_get_64 (unit->abfd, (bfd_byte *) buf)((*((unit->abfd)->xvec->bfd_getx64)) ((bfd_byte *) buf
)));
  case DW_EH_PE_sdata20x0A:
    *bytes_read_ptr += 2;
    return (base + bfd_get_signed_16 (unit->abfd, (bfd_byte *) buf)((*((unit->abfd)->xvec->bfd_getx_signed_16)) ((bfd_byte
 *) buf)));
  case DW_EH_PE_sdata40x0B:
    *bytes_read_ptr += 4;
    return (base + bfd_get_signed_32 (unit->abfd, (bfd_byte *) buf)((*((unit->abfd)->xvec->bfd_getx_signed_32)) ((bfd_byte
 *) buf)));
  case DW_EH_PE_sdata80x0C:
    *bytes_read_ptr += 8;
    return (base + bfd_get_signed_64 (unit->abfd, (bfd_byte *) buf)((*((unit->abfd)->xvec->bfd_getx_signed_64)) ((bfd_byte
 *) buf)));
  default:
    internal_error (__FILE__"/usr/src/gnu/usr.bin/binutils/gdb/dwarf2-frame.c", __LINE__1159, "Invalid or unsupported encoding");
  }
1161}
1162

1164/* GCC uses a single CIE for all FDEs in a .debug_frame section.
 That's why we use a simple linked list here.  */

1167static struct dwarf2_cie *
1168find_cie (struct comp_unit *unit, ULONGESTunsigned long cie_pointer)
1169{
struct dwarf2_cie *cie = unit->cie;

while (cie)
  {
    if (cie->cie_pointer == cie_pointer)
return cie;

    cie = cie->next;
  }

return NULL((void*)0);
1181}

1183static void
1184add_cie (struct comp_unit *unit, struct dwarf2_cie *cie)
1185{
cie->next = unit->cie;
unit->cie = cie;
1188}

1190/* Find the FDE for *PC.  Return a pointer to the FDE, and store the
 inital location associated with it into *PC.  */

1193static struct dwarf2_fde *
1194dwarf2_frame_find_fde (CORE_ADDR *pc)
1195{
struct objfile *objfile;

ALL_OBJFILES (objfile)for ((objfile) = object_files; (objfile) != ((void*)0); (objfile
) = (objfile)->next)
  {
    struct dwarf2_fde *fde;
    CORE_ADDR offset;

    fde = objfile_data (objfile, dwarf2_frame_objfile_data);
    if (fde == NULL((void*)0))
continue;

    gdb_assert (objfile->section_offsets)((void) ((objfile->section_offsets) ? 0 : (internal_error (
"/usr/src/gnu/usr.bin/binutils/gdb/dwarf2-frame.c", 1207, "%s: Assertion `%s' failed."
, __PRETTY_FUNCTION__, "objfile->section_offsets"), 0)));
    offset = ANOFFSET (objfile->section_offsets, SECT_OFF_TEXT (objfile))((((objfile->sect_index_text == -1) ? (internal_error ("/usr/src/gnu/usr.bin/binutils/gdb/dwarf2-frame.c"
, 1208, "sect_index_text not initialized"), -1) : objfile->
sect_index_text) == -1) ? (internal_error ("/usr/src/gnu/usr.bin/binutils/gdb/dwarf2-frame.c"
, 1208, "Section index is uninitialized"), -1) : objfile->
section_offsets->offsets[((objfile->sect_index_text == -
1) ? (internal_error ("/usr/src/gnu/usr.bin/binutils/gdb/dwarf2-frame.c"
, 1208, "sect_index_text not initialized"), -1) : objfile->
sect_index_text)]);

    while (fde)
{
 if (*pc >= fde->initial_location + offset
     && *pc < fde->initial_location + offset + fde->address_range)
   {
     *pc = fde->initial_location + offset;
     return fde;
   }

 fde = fde->next;
}
  }

return NULL((void*)0);
1224}

1226static void
1227add_fde (struct comp_unit *unit, struct dwarf2_fde *fde)
1228{
fde->next = objfile_data (unit->objfile, dwarf2_frame_objfile_data);
set_objfile_data (unit->objfile, dwarf2_frame_objfile_data, fde);
1231}

1233#ifdef CC_HAS_LONG_LONG1
1234#define DW64_CIE_ID0xffffffffffffffffULL 0xffffffffffffffffULL
1235#else
1236#define DW64_CIE_ID0xffffffffffffffffULL ~0
1237#endif

1239static char *decode_frame_entry (struct comp_unit *unit, char *start,
		 int eh_frame_p);

1242/* Decode the next CIE or FDE.  Return NULL if invalid input, otherwise
 the next byte to be processed.  */
1244static char *
1245decode_frame_entry_1 (struct comp_unit *unit, char *start, int eh_frame_p)
1246{
char *buf;
LONGESTlong length;
unsigned int bytes_read;
int dwarf64_p;
ULONGESTunsigned long cie_id;
ULONGESTunsigned long cie_pointer;
char *end;

buf = start;
length = read_initial_length (unit->abfd, buf, &bytes_read);
buf += bytes_read;
end = buf + length;

/* Are we still within the section? */
if (end > unit->dwarf_frame_buffer + unit->dwarf_frame_size)
9
←
Assuming the condition is false→
10
←
Taking false branch→
31
←
Assuming the condition is false→
32
←
Taking false branch→
  return NULL((void*)0);

if (length == 0)
11
←
Assuming 'length' is not equal to 0→
12
←
Taking false branch→
33
←
Assuming 'length' is not equal to 0→
34
←
Taking false branch→
  return end;

/* Distinguish between 32 and 64-bit encoded frame info.  */
dwarf64_p = (bytes_read == 12);
35
←
Assuming 'bytes_read' is not equal to 12→

/* In a .eh_frame section, zero is used to distinguish CIEs from FDEs.  */
if (eh_frame_p12.1
'eh_frame_p' is 0
1
'eh_frame_p' is 0
)
13
←
Taking false branch→
36
←
Taking false branch→
  cie_id = 0;
else if (dwarf64_p13.1
'dwarf64_p' is 0
1
'dwarf64_p' is 0
)
14
←
Taking false branch→
37
←
Taking false branch→
  cie_id = DW64_CIE_ID0xffffffffffffffffULL;
else
  cie_id = DW_CIE_ID0xffffffff;

if (dwarf64_p14.1
'dwarf64_p' is 0
1
'dwarf64_p' is 0
)
15
←
Taking false branch→
38
←
Taking false branch→
  {
    cie_pointer = read_8_bytes (unit->abfd, buf);
    buf += 8;
  }
else
  {
    cie_pointer = read_4_bytes (unit->abfd, buf);
    buf += 4;
  }

if (cie_pointer == cie_id)
16
←
Assuming 'cie_pointer' is not equal to 'cie_id'→
17
←
Taking false branch→
39
←
Assuming 'cie_pointer' is not equal to 'cie_id'→
40
←
Taking false branch→
  {
    /* This is a CIE.  */
    struct dwarf2_cie *cie;
    char *augmentation;
    unsigned int cie_version;

    /* Record the offset into the .debug_frame section of this CIE.  */
    cie_pointer = start - unit->dwarf_frame_buffer;

    /* Check whether we've already read it.  */
    if (find_cie (unit, cie_pointer))
return end;

    cie = (struct dwarf2_cie *)
obstack_alloc (&unit->objfile->objfile_obstack,__extension__ ({ struct obstack *__h = (&unit->objfile
->objfile_obstack); __extension__ ({ struct obstack *__o =
 (__h); int __len = ((sizeof (struct dwarf2_cie))); if (__o->
chunk_limit - __o->next_free < __len) _obstack_newchunk
 (__o, __len); ((__o)->next_free += (__len)); (void) 0; })
; __extension__ ({ struct obstack *__o1 = (__h); void *value;
 value = (void *) __o1->object_base; if (__o1->next_free
 == value) __o1->maybe_empty_object = 1; __o1->next_free
 = (((((__o1->next_free) - (char *) 0)+__o1->alignment_mask
) & ~ (__o1->alignment_mask)) + (char *) 0); if (__o1->
next_free - (char *)__o1->chunk > __o1->chunk_limit -
 (char *)__o1->chunk) __o1->next_free = __o1->chunk_limit
; __o1->object_base = __o1->next_free; value; }); })
       sizeof (struct dwarf2_cie))__extension__ ({ struct obstack *__h = (&unit->objfile
->objfile_obstack); __extension__ ({ struct obstack *__o =
 (__h); int __len = ((sizeof (struct dwarf2_cie))); if (__o->
chunk_limit - __o->next_free < __len) _obstack_newchunk
 (__o, __len); ((__o)->next_free += (__len)); (void) 0; })
; __extension__ ({ struct obstack *__o1 = (__h); void *value;
 value = (void *) __o1->object_base; if (__o1->next_free
 == value) __o1->maybe_empty_object = 1; __o1->next_free
 = (((((__o1->next_free) - (char *) 0)+__o1->alignment_mask
) & ~ (__o1->alignment_mask)) + (char *) 0); if (__o1->
next_free - (char *)__o1->chunk > __o1->chunk_limit -
 (char *)__o1->chunk) __o1->next_free = __o1->chunk_limit
; __o1->object_base = __o1->next_free; value; }); });
    cie->initial_instructions = NULL((void*)0);
    cie->cie_pointer = cie_pointer;

    /* The encoding for FDE's in a normal .debug_frame section
       depends on the target address size.  */
    cie->encoding = DW_EH_PE_absptr0x00;

    /* Check version number.  */
    cie_version = read_1_byte (unit->abfd, buf);
    if (cie_version != 1 && cie_version != 3)
return NULL((void*)0);
    buf += 1;

    /* Interpret the interesting bits of the augmentation.  */
    augmentation = buf;
    buf = augmentation + strlen (augmentation) + 1;

    /* The GCC 2.x "eh" augmentation has a pointer immediately
       following the augmentation string, so it must be handled
       first.  */
    if (augmentation[0] == 'e' && augmentation[1] == 'h')
{
 /* Skip.  */
 buf += TYPE_LENGTH (builtin_type_void_data_ptr)(builtin_type_void_data_ptr)->length;
 augmentation += 2;
}

    cie->code_alignment_factor =
read_unsigned_leb128 (unit->abfd, buf, &bytes_read);
    buf += bytes_read;

    cie->data_alignment_factor =
read_signed_leb128 (unit->abfd, buf, &bytes_read);
    buf += bytes_read;

    if (cie_version == 1)
{
 cie->return_address_register = read_1_byte (unit->abfd, buf);
 bytes_read = 1;
}
    else
cie->return_address_register = read_unsigned_leb128 (unit->abfd, buf,
					     &bytes_read);
    buf += bytes_read;

    cie->saw_z_augmentation = (*augmentation == 'z');
    if (cie->saw_z_augmentation)
{
 ULONGESTunsigned long length;

 length = read_unsigned_leb128 (unit->abfd, buf, &bytes_read);
 buf += bytes_read;
 if (buf > end)
   return NULL((void*)0);
 cie->initial_instructions = buf + length;
 augmentation++;
}

    while (*augmentation)
{
 /* "L" indicates a byte showing how the LSDA pointer is encoded.  */
 if (*augmentation == 'L')
   {
     /* Skip.  */
     buf++;
     augmentation++;
   }

 /* "R" indicates a byte indicating how FDE addresses are encoded.  */
 else if (*augmentation == 'R')
   {
     cie->encoding = *buf++;
     augmentation++;
   }

 /* "P" indicates a personality routine in the CIE augmentation.  */
 else if (*augmentation == 'P')
   {
     /* Skip.  */
     buf += size_of_encoded_value (*buf++);
     augmentation++;
   }

 /* Otherwise we have an unknown augmentation.
    Bail out unless we saw a 'z' prefix.  */
 else
   {
     if (cie->initial_instructions == NULL((void*)0))
return end;

     /* Skip unknown augmentations.  */
     buf = cie->initial_instructions;
     break;
   }
}

    cie->initial_instructions = buf;
    cie->end = end;

    add_cie (unit, cie);
  }
else
  {
    /* This is a FDE.  */
    struct dwarf2_fde *fde;

    /* In an .eh_frame section, the CIE pointer is the delta between the
address within the FDE where the CIE pointer is stored and the
address of the CIE.  Convert it to an offset into the .eh_frame
section.  */
    if (eh_frame_p17.1
'eh_frame_p' is 0
1
'eh_frame_p' is 0
)
18
←
Taking false branch→
41
←
Taking false branch→
{
 cie_pointer = buf - unit->dwarf_frame_buffer - cie_pointer;
 cie_pointer -= (dwarf64_p ? 8 : 4);
}

    /* In either case, validate the result is still within the section.  */
    if (cie_pointer >= unit->dwarf_frame_size)
19
←
Assuming 'cie_pointer' is < field 'dwarf_frame_size'→
20
←
Taking false branch→
42
←
Assuming 'cie_pointer' is < field 'dwarf_frame_size'→
43
←
Taking false branch→
return NULL((void*)0);

    fde = (struct dwarf2_fde *)
49
←
Null pointer value stored to 'fde'→
obstack_alloc (&unit->objfile->objfile_obstack,__extension__ ({ struct obstack *__h = (&unit->objfile
->objfile_obstack); __extension__ ({ struct obstack *__o =
 (__h); int __len = ((sizeof (struct dwarf2_fde))); if (__o->
chunk_limit - __o->next_free < __len) _obstack_newchunk
 (__o, __len); ((__o)->next_free += (__len)); (void) 0; })
; __extension__ ({ struct obstack *__o1 = (__h); void *value;
 value = (void *) __o1->object_base; if (__o1->next_free
 == value) __o1->maybe_empty_object = 1; __o1->next_free
 = (((((__o1->next_free) - (char *) 0)+__o1->alignment_mask
) & ~ (__o1->alignment_mask)) + (char *) 0); if (__o1->
next_free - (char *)__o1->chunk > __o1->chunk_limit -
 (char *)__o1->chunk) __o1->next_free = __o1->chunk_limit
; __o1->object_base = __o1->next_free; value; }); })
21
←
Assuming the condition is false→
22
←
Taking false branch→
23
←
Assuming 'value' is not equal to field 'next_free'→
24
←
Taking false branch→
25
←
Assuming the condition is false→
26
←
Taking false branch→
44
←
Assuming the condition is false→
45
←
Taking false branch→
46
←
Taking true branch→
47
←
Assuming the condition is false→
48
←
Taking false branch→
       sizeof (struct dwarf2_fde))__extension__ ({ struct obstack *__h = (&unit->objfile
->objfile_obstack); __extension__ ({ struct obstack *__o =
 (__h); int __len = ((sizeof (struct dwarf2_fde))); if (__o->
chunk_limit - __o->next_free < __len) _obstack_newchunk
 (__o, __len); ((__o)->next_free += (__len)); (void) 0; })
; __extension__ ({ struct obstack *__o1 = (__h); void *value;
 value = (void *) __o1->object_base; if (__o1->next_free
 == value) __o1->maybe_empty_object = 1; __o1->next_free
 = (((((__o1->next_free) - (char *) 0)+__o1->alignment_mask
) & ~ (__o1->alignment_mask)) + (char *) 0); if (__o1->
next_free - (char *)__o1->chunk > __o1->chunk_limit -
 (char *)__o1->chunk) __o1->next_free = __o1->chunk_limit
; __o1->object_base = __o1->next_free; value; }); });
    fde->cie = find_cie (unit, cie_pointer);
50
←
Access to field 'cie' results in a dereference of a null pointer (loaded from variable 'fde')
    if (fde->cie26.1
Field 'cie' is equal to NULL
 == NULL((void*)0))
27
←
Taking true branch→
{
 decode_frame_entry (unit, unit->dwarf_frame_buffer + cie_pointer,
28
←
Calling 'decode_frame_entry'→
	      eh_frame_p);
 fde->cie = find_cie (unit, cie_pointer);
}

    gdb_assert (fde->cie != NULL)((void) ((fde->cie != ((void*)0)) ? 0 : (internal_error ("/usr/src/gnu/usr.bin/binutils/gdb/dwarf2-frame.c"
, 1437, "%s: Assertion `%s' failed.", __PRETTY_FUNCTION__, "fde->cie != NULL"
), 0)));

    fde->initial_location =
read_encoded_value (unit, fde->cie->encoding, buf, &bytes_read);
    buf += bytes_read;

    fde->address_range =
read_encoded_value (unit, fde->cie->encoding & 0x0f, buf, &bytes_read);
    buf += bytes_read;

    /* A 'z' augmentation in the CIE implies the presence of an
augmentation field in the FDE as well.  The only thing known
to be in here at present is the LSDA entry for EH.  So we
can skip the whole thing.  */
    if (fde->cie->saw_z_augmentation)
{
 ULONGESTunsigned long length;

 length = read_unsigned_leb128 (unit->abfd, buf, &bytes_read);
 buf += bytes_read + length;
 if (buf > end)
   return NULL((void*)0);
}

    fde->instructions = buf;
    fde->end = end;

    add_fde (unit, fde);
  }

return end;
1468}

1470/* Read a CIE or FDE in BUF and decode it.  */
1471static char *
1472decode_frame_entry (struct comp_unit *unit, char *start, int eh_frame_p)
1473{
enum { NONE, ALIGN4, ALIGN8, FAIL } workaround = NONE;
char *ret;
const char *msg;
ptrdiff_t start_offset;

while (1)
7
←
Loop condition is true.  Entering loop body→
29
←
Loop condition is true.  Entering loop body→
  {
    ret = decode_frame_entry_1 (unit, start, eh_frame_p);
8
←
Calling 'decode_frame_entry_1'→
30
←
Calling 'decode_frame_entry_1'→
    if (ret != NULL((void*)0))
break;

    /* We have corrupt input data of some form.  */

    /* ??? Try, weakly, to work around compiler/assembler/linker bugs
and mismatches wrt padding and alignment of debug sections.  */
    /* Note that there is no requirement in the standard for any
alignment at all in the frame unwind sections.  Testing for
alignment before trying to interpret data would be incorrect.

However, GCC traditionally arranged for frame sections to be
sized such that the FDE length and CIE fields happen to be
aligned (in theory, for performance).  This, unfortunately,
was done with .align directives, which had the side effect of
forcing the section to be aligned by the linker.

This becomes a problem when you have some other producer that
creates frame sections that are not as strictly aligned.  That
produces a hole in the frame info that gets filled by the 
linker with zeros.

The GCC behaviour is arguably a bug, but it's effectively now
part of the ABI, so we're now stuck with it, at least at the
object file level.  A smart linker may decide, in the process
of compressing duplicate CIE information, that it can rewrite
the entire output section without this extra padding.  */

    start_offset = start - unit->dwarf_frame_buffer;
    if (workaround < ALIGN4 && (start_offset & 3) != 0)
{
 start += 4 - (start_offset & 3);
 workaround = ALIGN4;
 continue;
}
    if (workaround < ALIGN8 && (start_offset & 7) != 0)
{
 start += 8 - (start_offset & 7);
 workaround = ALIGN8;
 continue;
}

    /* Nothing left to try.  Arrange to return as if we've consumed
the entire input section.  Hopefully we'll get valid info from
the other of .debug_frame/.eh_frame.  */
    workaround = FAIL;
    ret = unit->dwarf_frame_buffer + unit->dwarf_frame_size;
    break;
  }

switch (workaround)
  {
  case NONE:
    break;

  case ALIGN4:
    complaint (&symfile_complaints,
 "Corrupt data in %s:%s; align 4 workaround apparently succeeded",
 unit->dwarf_frame_section->owner->filename,
 unit->dwarf_frame_section->name);
    break;

  case ALIGN8:
    complaint (&symfile_complaints,
 "Corrupt data in %s:%s; align 8 workaround apparently succeeded",
 unit->dwarf_frame_section->owner->filename,
 unit->dwarf_frame_section->name);
    break;

  default:
    complaint (&symfile_complaints,
 "Corrupt data in %s:%s",
 unit->dwarf_frame_section->owner->filename,
 unit->dwarf_frame_section->name);
    break;
  }

return ret;
1560}
1561

1563/* FIXME: kettenis/20030504: This still needs to be integrated with
 dwarf2read.c in a better way.  */

1566/* Imported from dwarf2read.c.  */
1567extern asection *dwarf_frame_section;
1568extern asection *dwarf_eh_frame_section;

1570/* Imported from dwarf2read.c.  */
1571extern char *dwarf2_read_section (struct objfile *objfile, asection *sectp);

1573void
1574dwarf2_build_frame_info (struct objfile *objfile)
1575{
struct comp_unit unit;
char *frame_ptr;

/* Build a minimal decoding of the DWARF2 compilation unit.  */
unit.abfd = objfile->obfd;
unit.objfile = objfile;
unit.dbase = 0;
unit.tbase = 0;

/* First add the information from the .eh_frame section.  That way,
   the FDEs from that section are searched last.  */
if (dwarf_eh_frame_section)
1
Assuming 'dwarf_eh_frame_section' is null→
2
←
Taking false branch→
  {
    asection *got, *txt;

    unit.cie = NULL((void*)0);
    unit.dwarf_frame_buffer = dwarf2_read_section (objfile,
				     dwarf_eh_frame_section);

    unit.dwarf_frame_size = bfd_get_section_size (dwarf_eh_frame_section)((dwarf_eh_frame_section)->_raw_size);
    unit.dwarf_frame_section = dwarf_eh_frame_section;

    /* FIXME: kettenis/20030602: This is the DW_EH_PE_datarel base
that is used for the i386/amd64 target, which currently is
the only target in GCC that supports/uses the
DW_EH_PE_datarel encoding.  */
    got = bfd_get_section_by_name (unit.abfd, ".got");
    if (got)
unit.dbase = got->vma;

    /* GCC emits the DW_EH_PE_textrel encoding type on sh and ia64
       so far.  */
    txt = bfd_get_section_by_name (unit.abfd, ".text");
    if (txt)
unit.tbase = txt->vma;

    frame_ptr = unit.dwarf_frame_buffer;
    while (frame_ptr < unit.dwarf_frame_buffer + unit.dwarf_frame_size)
frame_ptr = decode_frame_entry (&unit, frame_ptr, 1);
  }

if (dwarf_frame_section)
3
←
Assuming 'dwarf_frame_section' is non-null→
4
←
Taking true branch→
  {
    unit.cie = NULL((void*)0);
    unit.dwarf_frame_buffer = dwarf2_read_section (objfile,
				     dwarf_frame_section);
    unit.dwarf_frame_size = bfd_get_section_size (dwarf_frame_section)((dwarf_frame_section)->_raw_size);
    unit.dwarf_frame_section = dwarf_frame_section;

    frame_ptr = unit.dwarf_frame_buffer;
    while (frame_ptr < unit.dwarf_frame_buffer + unit.dwarf_frame_size)
5
←
Loop condition is true.  Entering loop body→
frame_ptr = decode_frame_entry (&unit, frame_ptr, 0);
6
←
Calling 'decode_frame_entry'→
  }
1629}

1631/* Provide a prototype to silence -Wmissing-prototypes.  */
1632void _initialize_dwarf2_frame (void);

1634void
1635_initialize_dwarf2_frame (void)
1636{
dwarf2_frame_data = gdbarch_data_register_pre_init (dwarf2_frame_init);
dwarf2_frame_objfile_data = register_objfile_data ();
1639}