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

 /* Target-dependent code for NetBSD/i386.

    Copyright (C) 1988-2016 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 "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);
   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) 1988-2016 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 "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);
	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);
	}