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/* Target-dependent code for NetBSD/alpha.

   Copyright (C) 2002, 2003, 2004, 2006, 2007, 2008, 2009, 2010

   Free Software Foundation, Inc.

   Contributed by Wasabi Systems, 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 "regcache.h"

#include "regset.h"

#include "value.h"

#include "gdb_assert.h"

#include "gdb_string.h"

#include "alpha-tdep.h"

#include "alphabsd-tdep.h"

#include "nbsd-tdep.h"

#include "solib-svr4.h"

#include "target.h"

/* Core file support.  */

/* Even though NetBSD/alpha used ELF since day one, it used the

   traditional a.out-style core dump format before NetBSD 1.6.  */

/* Sizeof `struct reg' in <machine/reg.h>.  */

#define ALPHANBSD_SIZEOF_GREGS  (32 * 8)

/* Sizeof `struct fpreg' in <machine/reg.h.  */

#define ALPHANBSD_SIZEOF_FPREGS ((32 * 8) + 8)

/* Supply register REGNUM from the buffer specified by FPREGS and LEN

   in the floating-point register set REGSET to register cache

   REGCACHE.  If REGNUM is -1, do this for all registers in REGSET.  */

static void

alphanbsd_supply_fpregset (const struct regset *regset,

                           struct regcache *regcache,

                           int regnum, const void *fpregs, size_t len)

{

  const gdb_byte *regs = fpregs;

  int i;

  gdb_assert (len >= ALPHANBSD_SIZEOF_FPREGS);

  for (i = ALPHA_FP0_REGNUM; i < ALPHA_FP0_REGNUM + 31; i++)

    {

      if (regnum == i || regnum == -1)

        regcache_raw_supply (regcache, i, regs + (i - ALPHA_FP0_REGNUM) * 8);

    }

  if (regnum == ALPHA_FPCR_REGNUM || regnum == -1)

    regcache_raw_supply (regcache, ALPHA_FPCR_REGNUM, regs + 32 * 8);

}

/* Supply register REGNUM from the buffer specified by GREGS and LEN

   in the general-purpose register set REGSET to register cache

   REGCACHE.  If REGNUM is -1, do this for all registers in REGSET.  */

static void

alphanbsd_supply_gregset (const struct regset *regset,

                          struct regcache *regcache,

                          int regnum, const void *gregs, size_t len)

{

  const gdb_byte *regs = gregs;

  int i;

  gdb_assert (len >= ALPHANBSD_SIZEOF_GREGS);

  for (i = 0; i < ALPHA_ZERO_REGNUM; i++)

    {

      if (regnum == i || regnum == -1)

        regcache_raw_supply (regcache, i, regs + i * 8);

    }

  if (regnum == ALPHA_PC_REGNUM || regnum == -1)

    regcache_raw_supply (regcache, ALPHA_PC_REGNUM, regs + 31 * 8);

}

/* Supply register REGNUM from the buffer specified by GREGS and LEN

   in the general-purpose register set REGSET to register cache

   REGCACHE.  If REGNUM is -1, do this for all registers in REGSET.  */

static void

alphanbsd_aout_supply_gregset (const struct regset *regset,

                               struct regcache *regcache,

                               int regnum, const void *gregs, size_t len)

{

  const gdb_byte *regs = gregs;

  int i;

  /* Table to map a GDB register number to a trapframe register index.  */

  static const int regmap[] =

  {

     0,   1,   2,   3,

     4,   5,   6,   7,

     8,   9,  10,  11,

    12,  13,  14,  15,

    30,  31,  32,  16,

    17,  18,  19,  20,

    21,  22,  23,  24,

    25,  29,  26

  };

  gdb_assert (len >= ALPHANBSD_SIZEOF_GREGS);

  for (i = 0; i < ARRAY_SIZE(regmap); i++)

    {

      if (regnum == i || regnum == -1)

        regcache_raw_supply (regcache, i, regs + regmap[i] * 8);

    }

  if (regnum == ALPHA_PC_REGNUM || regnum == -1)

    regcache_raw_supply (regcache, ALPHA_PC_REGNUM, regs + 31 * 8);

  if (len >= ALPHANBSD_SIZEOF_GREGS + ALPHANBSD_SIZEOF_FPREGS)

    {

      regs += ALPHANBSD_SIZEOF_GREGS;

      len -= ALPHANBSD_SIZEOF_GREGS;

      alphanbsd_supply_fpregset (regset, regcache, regnum, regs, len);

    }

}

/* NetBSD/alpha register sets.  */

static struct regset alphanbsd_gregset =

{

  NULL,

  alphanbsd_supply_gregset

};

static struct regset alphanbsd_fpregset =

{

  NULL,

  alphanbsd_supply_fpregset

};

static struct regset alphanbsd_aout_gregset =

{

  NULL,

  alphanbsd_aout_supply_gregset

};

/* Return the appropriate register set for the core section identified

   by SECT_NAME and SECT_SIZE.  */

const struct regset *

alphanbsd_regset_from_core_section (struct gdbarch *gdbarch,

                                    const char *sect_name, size_t sect_size)

{

  if (strcmp (sect_name, ".reg") == 0 && sect_size >= ALPHANBSD_SIZEOF_GREGS)

    {

      if (sect_size >= ALPHANBSD_SIZEOF_GREGS + ALPHANBSD_SIZEOF_FPREGS)

        return &alphanbsd_aout_gregset;

      else

        return &alphanbsd_gregset;

    }

  if (strcmp (sect_name, ".reg2") == 0 && sect_size >= ALPHANBSD_SIZEOF_FPREGS)

    return &alphanbsd_fpregset;

  return NULL;

}

/* Signal trampolines.  */

/* Under NetBSD/alpha, signal handler invocations can be identified by the

   designated code sequence that is used to return from a signal handler.

   In particular, the return address of a signal handler points to the

   following code sequence:

        ldq     a0, 0(sp)

        lda     sp, 16(sp)

        lda     v0, 295(zero)   # __sigreturn14

        call_pal callsys

   Each instruction has a unique encoding, so we simply attempt to match

   the instruction the PC is pointing to with any of the above instructions.

   If there is a hit, we know the offset to the start of the designated

   sequence and can then check whether we really are executing in the

   signal trampoline.  If not, -1 is returned, otherwise the offset from the

   start of the return sequence is returned.  */

static const unsigned char sigtramp_retcode[] =

{

  0x00, 0x00, 0x1e, 0xa6,       /* ldq a0, 0(sp) */

  0x10, 0x00, 0xde, 0x23,       /* lda sp, 16(sp) */

  0x27, 0x01, 0x1f, 0x20,       /* lda v0, 295(zero) */

  0x83, 0x00, 0x00, 0x00,       /* call_pal callsys */

};

#define RETCODE_NWORDS          4

#define RETCODE_SIZE            (RETCODE_NWORDS * 4)

static LONGEST

alphanbsd_sigtramp_offset (struct gdbarch *gdbarch, CORE_ADDR pc)

{

  unsigned char ret[RETCODE_SIZE], w[4];

  LONGEST off;

  int i;

  if (target_read_memory (pc, (char *) w, 4) != 0)

    return -1;

  for (i = 0; i < RETCODE_NWORDS; i++)

    {

      if (memcmp (w, sigtramp_retcode + (i * 4), 4) == 0)

        break;

    }

  if (i == RETCODE_NWORDS)

    return (-1);

  off = i * 4;

  pc -= off;

  if (target_read_memory (pc, (char *) ret, sizeof (ret)) != 0)

    return -1;

  if (memcmp (ret, sigtramp_retcode, RETCODE_SIZE) == 0)

    return off;

  return -1;

}

static int

alphanbsd_pc_in_sigtramp (struct gdbarch *gdbarch,

                          CORE_ADDR pc, char *func_name)

{

  return (nbsd_pc_in_sigtramp (pc, func_name)

          || alphanbsd_sigtramp_offset (gdbarch, pc) >= 0);

}

static CORE_ADDR

alphanbsd_sigcontext_addr (struct frame_info *frame)

{

  /* FIXME: This is not correct for all versions of NetBSD/alpha.

     We will probably need to disassemble the trampoline to figure

     out which trampoline frame type we have.  */

  if (!get_next_frame (frame))

    return 0;

  return get_frame_base (get_next_frame (frame));

}

static void

alphanbsd_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);

  /* NetBSD/alpha does not provide single step support via ptrace(2); we

     must use software single-stepping.  */

  set_gdbarch_software_single_step (gdbarch, alpha_software_single_step);

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

  set_solib_svr4_fetch_link_map_offsets

    (gdbarch, svr4_lp64_fetch_link_map_offsets);

  tdep->dynamic_sigtramp_offset = alphanbsd_sigtramp_offset;

  tdep->pc_in_sigtramp = alphanbsd_pc_in_sigtramp;

  tdep->sigcontext_addr = alphanbsd_sigcontext_addr;

  tdep->jb_pc = 2;

  tdep->jb_elt_size = 8;

  set_gdbarch_regset_from_core_section

    (gdbarch, alphanbsd_regset_from_core_section);

}

static enum gdb_osabi

alphanbsd_core_osabi_sniffer (bfd *abfd)

{

  if (strcmp (bfd_get_target (abfd), "netbsd-core") == 0)

    return GDB_OSABI_NETBSD_ELF;

  return GDB_OSABI_UNKNOWN;

}

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

void _initialize_alphanbsd_tdep (void);

void

_initialize_alphanbsd_tdep (void)

{

  /* BFD doesn't set a flavour for NetBSD style a.out core files.  */

  gdbarch_register_osabi_sniffer (bfd_arch_alpha, bfd_target_unknown_flavour,

                                  alphanbsd_core_osabi_sniffer);

  gdbarch_register_osabi (bfd_arch_alpha, 0, GDB_OSABI_NETBSD_ELF,

                          alphanbsd_init_abi);

}