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/* Signal trampoline unwinder, for GDB the GNU Debugger.

   Copyright (C) 2004, 2007, 2008, 2009, 2010 Free Software Foundation, Inc.

   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 3 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, see <http://www.gnu.org/licenses/>.  */

#include "defs.h"

#include "tramp-frame.h"

#include "frame-unwind.h"

#include "gdbcore.h"

#include "symtab.h"

#include "objfiles.h"

#include "target.h"

#include "trad-frame.h"

#include "frame-base.h"

#include "gdb_assert.h"

struct frame_data

{

  const struct tramp_frame *tramp_frame;

};

struct tramp_frame_cache

{

  CORE_ADDR func;

  const struct tramp_frame *tramp_frame;

  struct trad_frame_cache *trad_cache;

};

static struct trad_frame_cache *

tramp_frame_cache (struct frame_info *this_frame,

                   void **this_cache)

{

  struct tramp_frame_cache *tramp_cache = (*this_cache);

  if (tramp_cache->trad_cache == NULL)

    {

      tramp_cache->trad_cache = trad_frame_cache_zalloc (this_frame);

      tramp_cache->tramp_frame->init (tramp_cache->tramp_frame,

                                      this_frame,

                                      tramp_cache->trad_cache,

                                      tramp_cache->func);

    }

  return tramp_cache->trad_cache;

}

static void

tramp_frame_this_id (struct frame_info *this_frame,

                     void **this_cache,

                     struct frame_id *this_id)

{

  struct trad_frame_cache *trad_cache

    = tramp_frame_cache (this_frame, this_cache);

  trad_frame_get_id (trad_cache, this_id);

}

static struct value *

tramp_frame_prev_register (struct frame_info *this_frame,

                           void **this_cache,

                           int prev_regnum)

{

  struct trad_frame_cache *trad_cache

    = tramp_frame_cache (this_frame, this_cache);

  return trad_frame_get_register (trad_cache, this_frame, prev_regnum);

}

static CORE_ADDR

tramp_frame_start (const struct tramp_frame *tramp,

                   struct frame_info *this_frame, CORE_ADDR pc)

{

  struct gdbarch *gdbarch = get_frame_arch (this_frame);

  enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);

  int ti;

  /* Search through the trampoline for one that matches the

     instruction sequence around PC.  */

  for (ti = 0; tramp->insn[ti].bytes != TRAMP_SENTINEL_INSN; ti++)

    {

      CORE_ADDR func = pc - tramp->insn_size * ti;

      int i;

      for (i = 0; 1; i++)

        {

          gdb_byte buf[sizeof (tramp->insn[0])];

          ULONGEST insn;

          if (tramp->insn[i].bytes == TRAMP_SENTINEL_INSN)

            return func;

          if (!safe_frame_unwind_memory (this_frame,

                                         func + i * tramp->insn_size,

                                         buf, tramp->insn_size))

            break;

          insn = extract_unsigned_integer (buf, tramp->insn_size, byte_order);

          if (tramp->insn[i].bytes != (insn & tramp->insn[i].mask))

            break;

        }

    }

  /* Trampoline doesn't match.  */

  return 0;

}

static int

tramp_frame_sniffer (const struct frame_unwind *self,

                     struct frame_info *this_frame,

                     void **this_cache)

{

  const struct tramp_frame *tramp = self->unwind_data->tramp_frame;

  CORE_ADDR pc = get_frame_pc (this_frame);

  CORE_ADDR func;

  struct tramp_frame_cache *tramp_cache;

  /* tausq/2004-12-12: We used to assume if pc has a name or is in a valid

     section, then this is not a trampoline.  However, this assumption is

     false on HPUX which has a signal trampoline that has a name; it can

     also be false when using an alternative signal stack.  */

  func = tramp_frame_start (tramp, this_frame, pc);

  if (func == 0)

    return 0;

  tramp_cache = FRAME_OBSTACK_ZALLOC (struct tramp_frame_cache);

  tramp_cache->func = func;

  tramp_cache->tramp_frame = tramp;

  (*this_cache) = tramp_cache;

  return 1;

}

void

tramp_frame_prepend_unwinder (struct gdbarch *gdbarch,

                              const struct tramp_frame *tramp_frame)

{

  struct frame_data *data;

  struct frame_unwind *unwinder;

  int i;

  /* Check that the instruction sequence contains a sentinel.  */

  for (i = 0; i < ARRAY_SIZE (tramp_frame->insn); i++)

    {

      if (tramp_frame->insn[i].bytes == TRAMP_SENTINEL_INSN)

        break;

    }

  gdb_assert (i < ARRAY_SIZE (tramp_frame->insn));

  gdb_assert (tramp_frame->insn_size <= sizeof (tramp_frame->insn[0].bytes));

  data = GDBARCH_OBSTACK_ZALLOC (gdbarch, struct frame_data);

  unwinder = GDBARCH_OBSTACK_ZALLOC (gdbarch, struct frame_unwind);

  data->tramp_frame = tramp_frame;

  unwinder->type = tramp_frame->frame_type;

  unwinder->unwind_data = data;

  unwinder->sniffer = tramp_frame_sniffer;

  unwinder->this_id = tramp_frame_this_id;

  unwinder->prev_register = tramp_frame_prev_register;

  frame_unwind_prepend_unwinder (gdbarch, unwinder);

}