i386nbsd-tdep.c   [plain text]

/* Target-dependent code for NetBSD/i386, for GDB.
   Copyright 1988, 1989, 1991, 1992, 1994, 1996, 2000, 2001, 2002, 2003
   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 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.  */

#include "defs.h"
#include "gdbtypes.h"
#include "gdbcore.h"
#include "regcache.h"
#include "arch-utils.h"
#include "osabi.h"

#include "i386-tdep.h"
#include "i387-tdep.h"
#include "nbsd-tdep.h"

#include "solib-svr4.h"

/* Map a GDB register number to an offset in the reg structure.  */
static int regmap[] =
{
  ( 0 * 4),		/* %eax */
  ( 1 * 4),		/* %ecx */
  ( 2 * 4),		/* %edx */
  ( 3 * 4),		/* %ebx */
  ( 4 * 4),		/* %esp */
  ( 5 * 4),		/* %epb */
  ( 6 * 4),		/* %esi */
  ( 7 * 4),		/* %edi */
  ( 8 * 4),		/* %eip */
  ( 9 * 4),		/* %eflags */
  (10 * 4),		/* %cs */
  (11 * 4),		/* %ss */
  (12 * 4),		/* %ds */
  (13 * 4),		/* %es */
  (14 * 4),		/* %fs */
  (15 * 4),		/* %gs */
};

#define SIZEOF_STRUCT_REG	(16 * 4)

static void
i386nbsd_supply_reg (char *regs, int regno)
{
  int i;

  for (i = 0; i <= 15; i++)
    if (regno == i || regno == -1)
      supply_register (i, regs + regmap[i]);
}

static void
fetch_core_registers (char *core_reg_sect, unsigned core_reg_size, int which,
                      CORE_ADDR ignore)
{
  char *regs, *fsave;

  /* We get everything from one section.  */
  if (which != 0)
    return;

  if (core_reg_size < (SIZEOF_STRUCT_REG + 108))
    {
      warning ("Wrong size register set in core file.");
      return;
    }

  regs = core_reg_sect;
  fsave = core_reg_sect + SIZEOF_STRUCT_REG;

  /* Integer registers.  */
  i386nbsd_supply_reg (regs, -1);

  /* Floating point registers.  */
  i387_supply_fsave (fsave);
}

static void
fetch_elfcore_registers (char *core_reg_sect, unsigned core_reg_size,
			 int which, CORE_ADDR ignore)
{
  switch (which)
    {
    case 0:  /* Integer registers.  */
      if (core_reg_size != SIZEOF_STRUCT_REG)
	warning ("Wrong size register set in core file.");
      else
	i386nbsd_supply_reg (core_reg_sect, -1);
      break;

    case 2:  /* Floating point registers.  */
      if (core_reg_size != 108)
	warning ("Wrong size FP register set in core file."); 
      else
	i387_supply_fsave (core_reg_sect);  
      break;

    case 3:  /* "Extended" floating point registers.  This is gdb-speak
		for SSE/SSE2. */
      if (core_reg_size != 512)
	warning ("Wrong size XMM register set in core file.");
      else
	i387_supply_fxsave (core_reg_sect);
      break;

    default:
      /* Don't know what kind of register request this is; just ignore it.  */
      break;
    }
}

static struct core_fns i386nbsd_core_fns =
{
  bfd_target_unknown_flavour,		/* core_flavour */
  default_check_format,			/* check_format */
  default_core_sniffer,			/* core_sniffer */
  fetch_core_registers,			/* core_read_registers */
  NULL					/* next */
};

static struct core_fns i386nbsd_elfcore_fns =
{
  bfd_target_elf_flavour,		/* core_flavour */
  default_check_format,			/* check_format */
  default_core_sniffer,			/* core_sniffer */
  fetch_elfcore_registers,		/* core_read_registers */
  NULL					/* next */
};

/* Under NetBSD/i386, 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:

	leal	0x10(%esp), %eax
	pushl	%eax
	pushl	%eax
	movl	$0x127, %eax		# __sigreturn14
	int	$0x80

   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.  */
#define RETCODE_INSN1		0x8d
#define RETCODE_INSN2		0x50
#define RETCODE_INSN3		0x50
#define RETCODE_INSN4		0xb8
#define RETCODE_INSN5		0xcd

#define RETCODE_INSN2_OFF	4
#define RETCODE_INSN3_OFF	5
#define RETCODE_INSN4_OFF	6
#define RETCODE_INSN5_OFF	11

static const unsigned char sigtramp_retcode[] =
{
  RETCODE_INSN1, 0x44, 0x24, 0x10,
  RETCODE_INSN2,
  RETCODE_INSN3,
  RETCODE_INSN4, 0x27, 0x01, 0x00, 0x00,
  RETCODE_INSN5, 0x80,
};

static LONGEST
i386nbsd_sigtramp_offset (CORE_ADDR pc)
{
  unsigned char ret[sizeof(sigtramp_retcode)], insn;
  LONGEST off;
  int i;

  if (read_memory_nobpt (pc, &insn, 1) != 0)
    return -1;

  switch (insn)
    {
    case RETCODE_INSN1:
      off = 0;
      break;

    case RETCODE_INSN2:
      /* INSN2 and INSN3 are the same.  Read at the location of PC+1
	 to determine if we're actually looking at INSN2 or INSN3.  */
      if (read_memory_nobpt (pc + 1, &insn, 1) != 0)
	return -1;

      if (insn == RETCODE_INSN3)
	off = RETCODE_INSN2_OFF;
      else
	off = RETCODE_INSN3_OFF;
      break;

    case RETCODE_INSN4:
      off = RETCODE_INSN4_OFF;
      break;

    case RETCODE_INSN5:
      off = RETCODE_INSN5_OFF;
      break;

    default:
      return -1;
    }

  pc -= off;

  if (read_memory_nobpt (pc, (char *) ret, sizeof (ret)) != 0)
    return -1;

  if (memcmp (ret, sigtramp_retcode, sizeof (ret)) == 0)
    return off;

  return -1;
}

static int
i386nbsd_pc_in_sigtramp (CORE_ADDR pc, char *name)
{
  return (nbsd_pc_in_sigtramp (pc, name)
	  || i386nbsd_sigtramp_offset (pc) >= 0);
}

/* From <machine/signal.h>.  */
int i386nbsd_sc_pc_offset = 44;
int i386nbsd_sc_sp_offset = 56;

static void 
i386nbsd_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
{
  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);

  /* Obviously NetBSD is BSD-based.  */
  i386bsd_init_abi (info, gdbarch);

  /* NetBSD has different signal trampoline conventions.  */
  set_gdbarch_pc_in_sigtramp (gdbarch, i386nbsd_pc_in_sigtramp);
  /* FIXME: kettenis/20020906: We should probably provide
     NetBSD-specific versions of these functions if we want to
     recognize signal trampolines that live on the stack.  */
  set_gdbarch_sigtramp_start (gdbarch, NULL);
  set_gdbarch_sigtramp_end (gdbarch, NULL);

  /* NetBSD uses -freg-struct-return by default.  */
  tdep->struct_return = reg_struct_return;

  /* NetBSD has a `struct sigcontext' that's different from the
     origional 4.3 BSD.  */
  tdep->sc_pc_offset = i386nbsd_sc_pc_offset;
  tdep->sc_sp_offset = i386nbsd_sc_sp_offset;
}

/* NetBSD ELF.  */
static void
i386nbsdelf_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
{
  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);

  /* It's still NetBSD.  */
  i386nbsd_init_abi (info, gdbarch);

  /* But ELF-based.  */
  i386_elf_init_abi (info, gdbarch);

  /* NetBSD ELF uses SVR4-style shared libraries.  */
  set_gdbarch_in_solib_call_trampoline (gdbarch,
                                        generic_in_solib_call_trampoline);
  set_solib_svr4_fetch_link_map_offsets (gdbarch,
				 nbsd_ilp32_solib_svr4_fetch_link_map_offsets);

  /* NetBSD ELF uses -fpcc-struct-return by default.  */
  tdep->struct_return = pcc_struct_return;

  /* We support the SSE registers on NetBSD ELF.  */
  tdep->num_xmm_regs = I386_NUM_XREGS - 1;
  set_gdbarch_num_regs (gdbarch, I386_NUM_GREGS + I386_NUM_FREGS
                        + I386_NUM_XREGS);
}

void
_initialize_i386nbsd_tdep (void)
{
  add_core_fns (&i386nbsd_core_fns);
  add_core_fns (&i386nbsd_elfcore_fns);

  gdbarch_register_osabi (bfd_arch_i386, 0, GDB_OSABI_NETBSD_AOUT,
			  i386nbsd_init_abi);
  gdbarch_register_osabi (bfd_arch_i386, 0, GDB_OSABI_NETBSD_ELF,
			  i386nbsdelf_init_abi);
}