gdb/i386nbsd-tdep.c - binutils-gdb - Git at Google

 /* Target-dependent code for NetBSD/i386.

    Copyright (C) 1988, 1989, 1991, 1992, 1994, 1996, 2000, 2001, 2002, 2003,
    2004, 2007, 2008, 2009 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 "arch-utils.h"
 #include "frame.h"
 #include "gdbcore.h"
 #include "regcache.h"
 #include "regset.h"
 #include "osabi.h"
 #include "symtab.h"
 #include "trad-frame.h"
 #include "tramp-frame.h"

 #include "gdb_assert.h"
 #include "gdb_string.h"

 #include "i386-tdep.h"
 #include "i387-tdep.h"
 #include "nbsd-tdep.h"
 #include "solib-svr4.h"

 /* From <machine/reg.h>.  */
 static int i386nbsd_r_reg_offset[] =
 {
   0 * 4,			/* %eax */
   1 * 4,			/* %ecx */
   2 * 4,			/* %edx */
   3 * 4,			/* %ebx */
   4 * 4,			/* %esp */
   5 * 4,			/* %ebp */
   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 */
 };

 /* From <machine/signal.h>.  */
 int i386nbsd_sc_reg_offset[] =
 {
   10 * 4,			/* %eax */
   9 * 4,			/* %ecx */
   8 * 4,			/* %edx */
   7 * 4,			/* %ebx */
   14 * 4,			/* %esp */
   6 * 4,			/* %ebp */
   5 * 4,			/* %esi */
   4 * 4,			/* %edi */
   11 * 4,			/* %eip */
   13 * 4,			/* %eflags */
   12 * 4,			/* %cs */
   15 * 4,			/* %ss */
   3 * 4,			/* %ds */
   2 * 4,			/* %es */
   1 * 4,			/* %fs */
   0 * 4				/* %gs */
 };

 /* From <machine/mcontext.h>.  */
 int i386nbsd_mc_reg_offset[] =
 {
   11 * 4,			/* %eax */
   10 * 4,			/* %ecx */
   9 * 4,			/* %edx */
   8 * 4,			/* %ebx */
   7 * 4,			/* %esp */
   6 * 4,			/* %ebp */
   5 * 4,			/* %esi */
   4 * 4,			/* %edi */
   14 * 4,			/* %eip */
   16 * 4,			/* %eflags */
   15 * 4,			/* %cs */
   18 * 4,			/* %ss */
   3 * 4,			/* %ds */
   2 * 4,			/* %es */
   1 * 4,			/* %fs */
   0 * 4				/* %gs */
 };

 static void i386nbsd_sigtramp_cache_init (const struct tramp_frame *,
 					  struct frame_info *,
 					  struct trad_frame_cache *,
 					  CORE_ADDR);

 static const struct tramp_frame i386nbsd_sigtramp_sc16 =
 {
   SIGTRAMP_FRAME,
   1,
   {
     { 0x8d, -1 }, { 0x44, -1 }, { 0x24, -1 }, { 0x10, -1 },
 			/* leal  0x10(%esp), %eax */
     { 0x50, -1 },	/* pushl %eax */
     { 0x50, -1 },	/* pushl %eax */
     { 0xb8, -1 }, { 0x27, -1 }, {0x01, -1 }, {0x00, -1 }, {0x00, -1 },
 			/* movl  $0x127, %eax		# __sigreturn14 */
     { 0xcd, -1 }, { 0x80, -1},
 			/* int   $0x80 */
     { 0xb8, -1 }, { 0x01, -1 }, {0x00, -1 }, {0x00, -1 }, {0x00, -1 },
 			/* movl  $0x1, %eax		# exit */
     { 0xcd, -1 }, { 0x80, -1},
 			/* int   $0x80 */
     { TRAMP_SENTINEL_INSN, -1 }
   },
   i386nbsd_sigtramp_cache_init
 };

 static const struct tramp_frame i386nbsd_sigtramp_sc2 =
 {
   SIGTRAMP_FRAME,
   1,
   {
     { 0x8d, -1 }, { 0x44, -1 }, { 0x24, -1 }, { 0x0c, -1 },
 			/* leal  0x0c(%esp), %eax */
     { 0x89, -1 }, { 0x44, -1 }, { 0x24, -1 }, { 0x04, -1 },
 			/* movl  %eax, 0x4(%esp) */
     { 0xb8, -1 }, { 0x27, -1 }, {0x01, -1 }, {0x00, -1 }, {0x00, -1 },
 			/* movl  $0x127, %eax		# __sigreturn14 */
     { 0xcd, -1 }, { 0x80, -1},
 			/* int   $0x80 */
     { 0x89, -1 }, { 0x44, -1 }, { 0x24, -1 }, { 0x04, -1 },
 			/* movl  %eax, 0x4(%esp) */
     { 0xb8, -1 }, { 0x01, -1 }, {0x00, -1 }, {0x00, -1 }, {0x00, -1 },
 			/* movl  $0x1, %eax */
     { 0xcd, -1 }, { 0x80, -1},
 			/* int   $0x80 */
     { TRAMP_SENTINEL_INSN, -1 }
   },
   i386nbsd_sigtramp_cache_init
 };

 static const struct tramp_frame i386nbsd_sigtramp_si2 =
 {
   SIGTRAMP_FRAME,
   1,
   {
     { 0x8b, -1 }, { 0x44, -1 }, { 0x24, -1 }, { 0x08, -1 },
 			/* movl  8(%esp),%eax */
     { 0x89, -1 }, { 0x44, -1 }, { 0x24, -1 }, { 0x04, -1 },
 			/* movl  %eax, 0x4(%esp) */
     { 0xb8, -1 }, { 0x34, -1 }, { 0x01, -1 }, { 0x00, -1 }, { 0x00, -1 },
 			/* movl  $0x134, %eax            # setcontext */
     { 0xcd, -1 }, { 0x80, -1 },
 			/* int   $0x80 */
     { 0x89, -1 }, { 0x44, -1 }, { 0x24, -1 }, { 0x04, -1 },
 			/* movl  %eax, 0x4(%esp) */
     { 0xb8, -1 }, { 0x01, -1 }, { 0x00, -1 }, { 0x00, -1 }, { 0x00, -1 },
 			/* movl  $0x1, %eax */
     { 0xcd, -1 }, { 0x80, -1 },
 			/* int   $0x80 */
     { TRAMP_SENTINEL_INSN, -1 }
   },
   i386nbsd_sigtramp_cache_init
 };

 static const struct tramp_frame i386nbsd_sigtramp_si31 =
 {
   SIGTRAMP_FRAME,
   1,
   {
     { 0x8d, -1 }, { 0x84, -1 }, { 0x24, -1 },
         { 0x8c, -1 }, { 0x00, -1 }, { 0x00, -1 }, { 0x00, -1 },
 			/* leal  0x8c(%esp), %eax */
     { 0x89, -1 }, { 0x44, -1 }, { 0x24, -1 }, { 0x04, -1 },
 			/* movl  %eax, 0x4(%esp) */
     { 0xb8, -1 }, { 0x34, -1 }, { 0x01, -1 }, { 0x00, -1 }, { 0x00, -1 },
 			/* movl  $0x134, %eax            # setcontext */
     { 0xcd, -1 }, { 0x80, -1},
 			/* int   $0x80 */
     { 0x89, -1 }, { 0x44, -1 }, { 0x24, -1 }, { 0x04, -1 },
 			/* movl  %eax, 0x4(%esp) */
     { 0xb8, -1 }, { 0x01, -1 }, {0x00, -1 }, {0x00, -1 }, {0x00, -1 },
 			/* movl  $0x1, %eax */
     { 0xcd, -1 }, { 0x80, -1},
 			/* int   $0x80 */
     { TRAMP_SENTINEL_INSN, -1 }
   },
   i386nbsd_sigtramp_cache_init
 };

 static const struct tramp_frame i386nbsd_sigtramp_si4 =
 {
   SIGTRAMP_FRAME,
   1,
   {
     { 0x8d, -1 }, { 0x84, -1 }, { 0x24, -1 },
         { 0x8c, -1 }, { 0x00, -1 }, { 0x00, -1 }, { 0x00, -1 },
 			/* leal  0x8c(%esp), %eax */
     { 0x89, -1 }, { 0x44, -1 }, { 0x24, -1 }, { 0x04, -1 },
 			/* movl  %eax, 0x4(%esp) */
     { 0xb8, -1 }, { 0x34, -1 }, { 0x01, -1 }, { 0x00, -1 }, { 0x00, -1 },
 			/* movl  $0x134, %eax            # setcontext */
     { 0xcd, -1 }, { 0x80, -1},
 			/* int   $0x80 */
     { 0xc7, -1 }, { 0x44, -1 }, { 0x24, -1 }, { 0x04, -1 },
         { 0xff, -1 }, { 0xff, -1 }, { 0xff, -1 }, { 0xff, -1 },
 			/* movl   $0xffffffff,0x4(%esp) */
     { 0xb8, -1 }, { 0x01, -1 }, {0x00, -1 }, {0x00, -1 }, {0x00, -1 },
 			/* movl  $0x1, %eax */
     { 0xcd, -1 }, { 0x80, -1},
 			/* int   $0x80 */
     { TRAMP_SENTINEL_INSN, -1 }
   },
   i386nbsd_sigtramp_cache_init
 };

 static void
 i386nbsd_sigtramp_cache_init (const struct tramp_frame *self,
 			      struct frame_info *this_frame,
 			      struct trad_frame_cache *this_cache,
 			      CORE_ADDR func)
 {
   struct gdbarch *gdbarch = get_frame_arch (this_frame);
   struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
   enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
   CORE_ADDR sp = get_frame_register_unsigned (this_frame, I386_ESP_REGNUM);
   CORE_ADDR base;
   int *reg_offset;
   int num_regs;
   int i;

   if (self == &i386nbsd_sigtramp_sc16 || self == &i386nbsd_sigtramp_sc2)
     {
       reg_offset = i386nbsd_sc_reg_offset;
       num_regs = ARRAY_SIZE (i386nbsd_sc_reg_offset);

       /* Read in the sigcontext address */
       base = read_memory_unsigned_integer (sp + 8, 4, byte_order);
     }
   else
     {
       reg_offset = i386nbsd_mc_reg_offset;
       num_regs = ARRAY_SIZE (i386nbsd_mc_reg_offset);

       /* Read in the ucontext address */
       base = read_memory_unsigned_integer (sp + 8, 4, byte_order);
       /* offsetof(ucontext_t, uc_mcontext) == 36 */
       base += 36;
     }

   for (i = 0; i < num_regs; i++)
     if (reg_offset[i] != -1)
       trad_frame_set_reg_addr (this_cache, i, base + reg_offset[i]);

   /* Construct the frame ID using the function start.  */
   trad_frame_set_id (this_cache, frame_id_build (sp, func));
 }


 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 a different `struct reg'.  */
   tdep->gregset_reg_offset = i386nbsd_r_reg_offset;
   tdep->gregset_num_regs = ARRAY_SIZE (i386nbsd_r_reg_offset);
   tdep->sizeof_gregset = 16 * 4;

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

   /* NetBSD uses tramp_frame sniffers for signal trampolines. */
   tdep->sigcontext_addr= 0;
   tdep->sigtramp_start = 0;
   tdep->sigtramp_end = 0;
   tdep->sigtramp_p = 0;
   tdep->sc_reg_offset = 0;
   tdep->sc_num_regs = 0;

   tramp_frame_prepend_unwinder (gdbarch, &i386nbsd_sigtramp_sc16);
   tramp_frame_prepend_unwinder (gdbarch, &i386nbsd_sigtramp_sc2);
   tramp_frame_prepend_unwinder (gdbarch, &i386nbsd_sigtramp_si2);
   tramp_frame_prepend_unwinder (gdbarch, &i386nbsd_sigtramp_si31);
   tramp_frame_prepend_unwinder (gdbarch, &i386nbsd_sigtramp_si4);
 }

 /* 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_solib_svr4_fetch_link_map_offsets
     (gdbarch, svr4_ilp32_fetch_link_map_offsets);

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

 /* Provide a prototype to silence -Wmissing-prototypes.  */
 extern initialize_file_ftype _initialize_i386nbsd_tdep;

 void
 _initialize_i386nbsd_tdep (void)
 {
   gdbarch_register_osabi (bfd_arch_i386, 0, GDB_OSABI_NETBSD_ELF,
 			  i386nbsdelf_init_abi);
 }
	/* Target-dependent code for NetBSD/i386.

	Copyright (C) 1988, 1989, 1991, 1992, 1994, 1996, 2000, 2001, 2002, 2003,
	2004, 2007, 2008, 2009 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 "arch-utils.h"
	#include "frame.h"
	#include "gdbcore.h"
	#include "regcache.h"
	#include "regset.h"
	#include "osabi.h"
	#include "symtab.h"
	#include "trad-frame.h"
	#include "tramp-frame.h"

	#include "gdb_assert.h"
	#include "gdb_string.h"

	#include "i386-tdep.h"
	#include "i387-tdep.h"
	#include "nbsd-tdep.h"
	#include "solib-svr4.h"

	/* From <machine/reg.h>. */
	static int i386nbsd_r_reg_offset[] =
	{
	0 * 4, /* %eax */
	1 * 4, /* %ecx */
	2 * 4, /* %edx */
	3 * 4, /* %ebx */
	4 * 4, /* %esp */
	5 * 4, /* %ebp */
	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 */
	};

	/* From <machine/signal.h>. */
	int i386nbsd_sc_reg_offset[] =
	{
	10 * 4, /* %eax */
	9 * 4, /* %ecx */
	8 * 4, /* %edx */
	7 * 4, /* %ebx */
	14 * 4, /* %esp */
	6 * 4, /* %ebp */
	5 * 4, /* %esi */
	4 * 4, /* %edi */
	11 * 4, /* %eip */
	13 * 4, /* %eflags */
	12 * 4, /* %cs */
	15 * 4, /* %ss */
	3 * 4, /* %ds */
	2 * 4, /* %es */
	1 * 4, /* %fs */
	0 * 4 /* %gs */
	};

	/* From <machine/mcontext.h>. */
	int i386nbsd_mc_reg_offset[] =
	{
	11 * 4, /* %eax */
	10 * 4, /* %ecx */
	9 * 4, /* %edx */
	8 * 4, /* %ebx */
	7 * 4, /* %esp */
	6 * 4, /* %ebp */
	5 * 4, /* %esi */
	4 * 4, /* %edi */
	14 * 4, /* %eip */
	16 * 4, /* %eflags */
	15 * 4, /* %cs */
	18 * 4, /* %ss */
	3 * 4, /* %ds */
	2 * 4, /* %es */
	1 * 4, /* %fs */
	0 * 4 /* %gs */
	};

	static void i386nbsd_sigtramp_cache_init (const struct tramp_frame *,
	struct frame_info *,
	struct trad_frame_cache *,
	CORE_ADDR);

	static const struct tramp_frame i386nbsd_sigtramp_sc16 =
	{
	SIGTRAMP_FRAME,
	1,
	{
	{ 0x8d, -1 }, { 0x44, -1 }, { 0x24, -1 }, { 0x10, -1 },
	/* leal 0x10(%esp), %eax */
	{ 0x50, -1 }, /* pushl %eax */
	{ 0x50, -1 }, /* pushl %eax */
	{ 0xb8, -1 }, { 0x27, -1 }, {0x01, -1 }, {0x00, -1 }, {0x00, -1 },
	/* movl $0x127, %eax # __sigreturn14 */
	{ 0xcd, -1 }, { 0x80, -1},
	/* int $0x80 */
	{ 0xb8, -1 }, { 0x01, -1 }, {0x00, -1 }, {0x00, -1 }, {0x00, -1 },
	/* movl $0x1, %eax # exit */
	{ 0xcd, -1 }, { 0x80, -1},
	/* int $0x80 */
	{ TRAMP_SENTINEL_INSN, -1 }
	},
	i386nbsd_sigtramp_cache_init
	};

	static const struct tramp_frame i386nbsd_sigtramp_sc2 =
	{
	SIGTRAMP_FRAME,
	1,
	{
	{ 0x8d, -1 }, { 0x44, -1 }, { 0x24, -1 }, { 0x0c, -1 },
	/* leal 0x0c(%esp), %eax */
	{ 0x89, -1 }, { 0x44, -1 }, { 0x24, -1 }, { 0x04, -1 },
	/* movl %eax, 0x4(%esp) */
	{ 0xb8, -1 }, { 0x27, -1 }, {0x01, -1 }, {0x00, -1 }, {0x00, -1 },
	/* movl $0x127, %eax # __sigreturn14 */
	{ 0xcd, -1 }, { 0x80, -1},
	/* int $0x80 */
	{ 0x89, -1 }, { 0x44, -1 }, { 0x24, -1 }, { 0x04, -1 },
	/* movl %eax, 0x4(%esp) */
	{ 0xb8, -1 }, { 0x01, -1 }, {0x00, -1 }, {0x00, -1 }, {0x00, -1 },
	/* movl $0x1, %eax */
	{ 0xcd, -1 }, { 0x80, -1},
	/* int $0x80 */
	{ TRAMP_SENTINEL_INSN, -1 }
	},
	i386nbsd_sigtramp_cache_init
	};

	static const struct tramp_frame i386nbsd_sigtramp_si2 =
	{
	SIGTRAMP_FRAME,
	1,
	{
	{ 0x8b, -1 }, { 0x44, -1 }, { 0x24, -1 }, { 0x08, -1 },
	/* movl 8(%esp),%eax */
	{ 0x89, -1 }, { 0x44, -1 }, { 0x24, -1 }, { 0x04, -1 },
	/* movl %eax, 0x4(%esp) */
	{ 0xb8, -1 }, { 0x34, -1 }, { 0x01, -1 }, { 0x00, -1 }, { 0x00, -1 },
	/* movl $0x134, %eax # setcontext */
	{ 0xcd, -1 }, { 0x80, -1 },
	/* int $0x80 */
	{ 0x89, -1 }, { 0x44, -1 }, { 0x24, -1 }, { 0x04, -1 },
	/* movl %eax, 0x4(%esp) */
	{ 0xb8, -1 }, { 0x01, -1 }, { 0x00, -1 }, { 0x00, -1 }, { 0x00, -1 },
	/* movl $0x1, %eax */
	{ 0xcd, -1 }, { 0x80, -1 },
	/* int $0x80 */
	{ TRAMP_SENTINEL_INSN, -1 }
	},
	i386nbsd_sigtramp_cache_init
	};

	static const struct tramp_frame i386nbsd_sigtramp_si31 =
	{
	SIGTRAMP_FRAME,
	1,
	{
	{ 0x8d, -1 }, { 0x84, -1 }, { 0x24, -1 },
	{ 0x8c, -1 }, { 0x00, -1 }, { 0x00, -1 }, { 0x00, -1 },
	/* leal 0x8c(%esp), %eax */
	{ 0x89, -1 }, { 0x44, -1 }, { 0x24, -1 }, { 0x04, -1 },
	/* movl %eax, 0x4(%esp) */
	{ 0xb8, -1 }, { 0x34, -1 }, { 0x01, -1 }, { 0x00, -1 }, { 0x00, -1 },
	/* movl $0x134, %eax # setcontext */
	{ 0xcd, -1 }, { 0x80, -1},
	/* int $0x80 */
	{ 0x89, -1 }, { 0x44, -1 }, { 0x24, -1 }, { 0x04, -1 },
	/* movl %eax, 0x4(%esp) */
	{ 0xb8, -1 }, { 0x01, -1 }, {0x00, -1 }, {0x00, -1 }, {0x00, -1 },
	/* movl $0x1, %eax */
	{ 0xcd, -1 }, { 0x80, -1},
	/* int $0x80 */
	{ TRAMP_SENTINEL_INSN, -1 }
	},
	i386nbsd_sigtramp_cache_init
	};

	static const struct tramp_frame i386nbsd_sigtramp_si4 =
	{
	SIGTRAMP_FRAME,
	1,
	{
	{ 0x8d, -1 }, { 0x84, -1 }, { 0x24, -1 },
	{ 0x8c, -1 }, { 0x00, -1 }, { 0x00, -1 }, { 0x00, -1 },
	/* leal 0x8c(%esp), %eax */
	{ 0x89, -1 }, { 0x44, -1 }, { 0x24, -1 }, { 0x04, -1 },
	/* movl %eax, 0x4(%esp) */
	{ 0xb8, -1 }, { 0x34, -1 }, { 0x01, -1 }, { 0x00, -1 }, { 0x00, -1 },
	/* movl $0x134, %eax # setcontext */
	{ 0xcd, -1 }, { 0x80, -1},
	/* int $0x80 */
	{ 0xc7, -1 }, { 0x44, -1 }, { 0x24, -1 }, { 0x04, -1 },
	{ 0xff, -1 }, { 0xff, -1 }, { 0xff, -1 }, { 0xff, -1 },
	/* movl $0xffffffff,0x4(%esp) */
	{ 0xb8, -1 }, { 0x01, -1 }, {0x00, -1 }, {0x00, -1 }, {0x00, -1 },
	/* movl $0x1, %eax */
	{ 0xcd, -1 }, { 0x80, -1},
	/* int $0x80 */
	{ TRAMP_SENTINEL_INSN, -1 }
	},
	i386nbsd_sigtramp_cache_init
	};

	static void
	i386nbsd_sigtramp_cache_init (const struct tramp_frame *self,
	struct frame_info *this_frame,
	struct trad_frame_cache *this_cache,
	CORE_ADDR func)
	{
	struct gdbarch *gdbarch = get_frame_arch (this_frame);
	struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
	enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
	CORE_ADDR sp = get_frame_register_unsigned (this_frame, I386_ESP_REGNUM);
	CORE_ADDR base;
	int *reg_offset;
	int num_regs;
	int i;

	if (self == &i386nbsd_sigtramp_sc16 \|\| self == &i386nbsd_sigtramp_sc2)
	{
	reg_offset = i386nbsd_sc_reg_offset;
	num_regs = ARRAY_SIZE (i386nbsd_sc_reg_offset);

	/* Read in the sigcontext address */
	base = read_memory_unsigned_integer (sp + 8, 4, byte_order);
	}
	else
	{
	reg_offset = i386nbsd_mc_reg_offset;
	num_regs = ARRAY_SIZE (i386nbsd_mc_reg_offset);

	/* Read in the ucontext address */
	base = read_memory_unsigned_integer (sp + 8, 4, byte_order);
	/* offsetof(ucontext_t, uc_mcontext) == 36 */
	base += 36;
	}

	for (i = 0; i < num_regs; i++)
	if (reg_offset[i] != -1)
	trad_frame_set_reg_addr (this_cache, i, base + reg_offset[i]);

	/* Construct the frame ID using the function start. */
	trad_frame_set_id (this_cache, frame_id_build (sp, func));
	}


	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 a different `struct reg'. */
	tdep->gregset_reg_offset = i386nbsd_r_reg_offset;
	tdep->gregset_num_regs = ARRAY_SIZE (i386nbsd_r_reg_offset);
	tdep->sizeof_gregset = 16 * 4;

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

	/* NetBSD uses tramp_frame sniffers for signal trampolines. */
	tdep->sigcontext_addr= 0;
	tdep->sigtramp_start = 0;
	tdep->sigtramp_end = 0;
	tdep->sigtramp_p = 0;
	tdep->sc_reg_offset = 0;
	tdep->sc_num_regs = 0;

	tramp_frame_prepend_unwinder (gdbarch, &i386nbsd_sigtramp_sc16);
	tramp_frame_prepend_unwinder (gdbarch, &i386nbsd_sigtramp_sc2);
	tramp_frame_prepend_unwinder (gdbarch, &i386nbsd_sigtramp_si2);
	tramp_frame_prepend_unwinder (gdbarch, &i386nbsd_sigtramp_si31);
	tramp_frame_prepend_unwinder (gdbarch, &i386nbsd_sigtramp_si4);
	}

	/* 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_solib_svr4_fetch_link_map_offsets
	(gdbarch, svr4_ilp32_fetch_link_map_offsets);

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

	/* Provide a prototype to silence -Wmissing-prototypes. */
	extern initialize_file_ftype _initialize_i386nbsd_tdep;

	void
	_initialize_i386nbsd_tdep (void)
	{
	gdbarch_register_osabi (bfd_arch_i386, 0, GDB_OSABI_NETBSD_ELF,
	i386nbsdelf_init_abi);
	}