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/* Target-dependent code for OpenBSD/alpha.

   Copyright (C) 2006, 2007, 2008 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 "frame.h"

#include "gdbcore.h"

#include "osabi.h"

#include "obsd-tdep.h"

#include "alpha-tdep.h"

#include "alphabsd-tdep.h"

#include "solib-svr4.h"

/* Signal trampolines.  */

/* The OpenBSD kernel maps the signal trampoline at some random

   location in user space, which means that the traditional BSD way of

   detecting it won't work.

   The signal trampoline will be mapped at an address that is page

   aligned.  We recognize the signal trampoline by looking for the

   sigreturn system call.  */

static const int alphaobsd_page_size = 8192;

static LONGEST

alphaobsd_sigtramp_offset (CORE_ADDR pc)

{

  return (pc & (alphaobsd_page_size - 1));

}

static int

alphaobsd_pc_in_sigtramp (CORE_ADDR pc, char *name)

{

  CORE_ADDR start_pc = (pc & ~(alphaobsd_page_size - 1));

  unsigned insn;

  if (name)

    return 0;

  /* Check for "".  */

  insn = alpha_read_insn (start_pc + 5 * ALPHA_INSN_SIZE);

  if (insn != 0x201f0067)

    return 0;

  /* Check for "".  */

  insn = alpha_read_insn (start_pc + 6 * ALPHA_INSN_SIZE);

  if (insn != 0x00000083)

    return 0;

  return 1;

}

static CORE_ADDR

alphaobsd_sigcontext_addr (struct frame_info *next_frame)

{

  CORE_ADDR pc = frame_pc_unwind (next_frame);

  if (alphaobsd_sigtramp_offset (pc) < 3 * ALPHA_INSN_SIZE)

    {

      /* On entry, a pointer the `struct sigcontext' is passed in %a2.  */

      return frame_unwind_register_unsigned (next_frame, ALPHA_A0_REGNUM + 2);

    }

  else if (alphaobsd_sigtramp_offset (pc) < 4 * ALPHA_INSN_SIZE)

    {

      /* It is stored on the stack Before calling the signal handler.  */

      CORE_ADDR sp;

      sp = frame_unwind_register_unsigned (next_frame, ALPHA_SP_REGNUM);

      return get_frame_memory_unsigned (next_frame, sp, 8);

    }

  else

    {

      /* It is reloaded into %a0 for the sigreturn(2) call.  */

      return frame_unwind_register_unsigned (next_frame, ALPHA_A0_REGNUM);

    }

}

static void

alphaobsd_init_abi(struct gdbarch_info info, struct gdbarch *gdbarch)

{

  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);

  /* Hook into the DWARF CFI frame unwinder.  */

  alpha_dwarf2_init_abi (info, gdbarch);

  /* Hook into the MDEBUG frame unwinder.  */

  alpha_mdebug_init_abi (info, gdbarch);

  /* OpenBSD/alpha 3.0 and earlier does not provide single step

     support via ptrace(2); use software single-stepping for now.  */

  set_gdbarch_software_single_step (gdbarch, alpha_software_single_step);

  /* OpenBSD/alpha has SVR4-style shared libraries.  */

  set_solib_svr4_fetch_link_map_offsets

    (gdbarch, svr4_lp64_fetch_link_map_offsets);

  set_gdbarch_skip_solib_resolver (gdbarch, obsd_skip_solib_resolver);

  tdep->dynamic_sigtramp_offset = alphaobsd_sigtramp_offset;

  tdep->pc_in_sigtramp = alphaobsd_pc_in_sigtramp;

  tdep->sigcontext_addr = alphaobsd_sigcontext_addr;

  tdep->jb_pc = 2;

  tdep->jb_elt_size = 8;

  set_gdbarch_regset_from_core_section

    (gdbarch, alphanbsd_regset_from_core_section);

}

/* Provide a prototype to silence -Wmissing-prototypes.  */

void _initialize_alphaobsd_tdep (void);

void

_initialize_alphaobsd_tdep (void)

{

  gdbarch_register_osabi (bfd_arch_alpha, 0, GDB_OSABI_OPENBSD_ELF,

                          alphaobsd_init_abi);

}