[thirdparty/binutils-gdb.git] / gdb / xtensa-linux-nat.c

/* Xtensa GNU/Linux native support.

   Copyright (C) 2007-2013 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 "gdb_string.h"
#include "frame.h"
#include "inferior.h"
#include "gdbcore.h"
#include "regcache.h"
#include "gdb_assert.h"
#include "target.h"
#include "linux-nat.h"

#include <stdint.h>
#include <sys/types.h>
#include <sys/param.h>
#include <signal.h>
#include <sys/user.h>
#include <sys/ioctl.h>
#include "gdb_wait.h"
#include <fcntl.h>
#include <sys/procfs.h>
#include <sys/ptrace.h>

#include "gregset.h"
#include "xtensa-tdep.h"

/* Extended register set depends on hardware configs.
   Keeping these definitions separately allows to introduce
   hardware-specific overlays.  */
#include "xtensa-xtregs.c"

static int
get_thread_id (ptid_t ptid)
{
  int tid = TIDGET (ptid);
  if (0 == tid)
    tid = PIDGET (ptid);
  return tid;
}
#define GET_THREAD_ID(PTID)	get_thread_id (PTID)

void
fill_gregset (const struct regcache *regcache,
	      gdb_gregset_t *gregsetp, int regnum)
{
  int i;
  xtensa_elf_gregset_t *regs = (xtensa_elf_gregset_t *) gregsetp;
  struct gdbarch *gdbarch = get_regcache_arch (regcache);

  if (regnum == gdbarch_pc_regnum (gdbarch) || regnum == -1)
    regcache_raw_collect (regcache, gdbarch_pc_regnum (gdbarch), &regs->pc);
  if (regnum == gdbarch_ps_regnum (gdbarch) || regnum == -1)
    regcache_raw_collect (regcache, gdbarch_ps_regnum (gdbarch), &regs->ps);

  if (regnum == gdbarch_tdep (gdbarch)->wb_regnum || regnum == -1)
    regcache_raw_collect (regcache,
			  gdbarch_tdep (gdbarch)->wb_regnum,
			  &regs->windowbase);
  if (regnum == gdbarch_tdep (gdbarch)->ws_regnum || regnum == -1)
    regcache_raw_collect (regcache,
			  gdbarch_tdep (gdbarch)->ws_regnum,
			  &regs->windowstart);
  if (regnum == gdbarch_tdep (gdbarch)->lbeg_regnum || regnum == -1)
    regcache_raw_collect (regcache,
			  gdbarch_tdep (gdbarch)->lbeg_regnum,
			  &regs->lbeg);
  if (regnum == gdbarch_tdep (gdbarch)->lend_regnum || regnum == -1)
    regcache_raw_collect (regcache,
			  gdbarch_tdep (gdbarch)->lend_regnum,
			  &regs->lend);
  if (regnum == gdbarch_tdep (gdbarch)->lcount_regnum || regnum == -1)
    regcache_raw_collect (regcache,
			  gdbarch_tdep (gdbarch)->lcount_regnum,
			  &regs->lcount);
  if (regnum == gdbarch_tdep (gdbarch)->sar_regnum || regnum == -1)
    regcache_raw_collect (regcache,
			  gdbarch_tdep (gdbarch)->sar_regnum,
			  &regs->sar);
  if (regnum >=gdbarch_tdep (gdbarch)->ar_base
      && regnum < gdbarch_tdep (gdbarch)->ar_base
		    + gdbarch_tdep (gdbarch)->num_aregs)
    regcache_raw_collect (regcache,regnum,
			  &regs->ar[regnum - gdbarch_tdep (gdbarch)->ar_base]);
  else if (regnum == -1)
    {
      for (i = 0; i < gdbarch_tdep (gdbarch)->num_aregs; ++i)
	regcache_raw_collect (regcache,
			      gdbarch_tdep (gdbarch)->ar_base + i,
			      &regs->ar[i]);
    }
}

void
supply_gregset_reg (struct regcache *regcache,
		    const gdb_gregset_t *gregsetp, int regnum)
{
  int i;
  xtensa_elf_gregset_t *regs = (xtensa_elf_gregset_t *) gregsetp;

  struct gdbarch *gdbarch = get_regcache_arch (regcache);

  if (regnum == gdbarch_pc_regnum (gdbarch) || regnum == -1)
    regcache_raw_supply (regcache, gdbarch_pc_regnum (gdbarch), &regs->pc);
  if (regnum == gdbarch_ps_regnum (gdbarch) || regnum == -1)
    regcache_raw_supply (regcache, gdbarch_ps_regnum (gdbarch), &regs->ps);

  if (regnum == gdbarch_tdep (gdbarch)->wb_regnum || regnum == -1)
    regcache_raw_supply (regcache,
			  gdbarch_tdep (gdbarch)->wb_regnum,
			  &regs->windowbase);
  if (regnum == gdbarch_tdep (gdbarch)->ws_regnum || regnum == -1)
    regcache_raw_supply (regcache,
			  gdbarch_tdep (gdbarch)->ws_regnum,
			  &regs->windowstart);
  if (regnum == gdbarch_tdep (gdbarch)->lbeg_regnum || regnum == -1)
    regcache_raw_supply (regcache,
			  gdbarch_tdep (gdbarch)->lbeg_regnum,
			  &regs->lbeg);
  if (regnum == gdbarch_tdep (gdbarch)->lend_regnum || regnum == -1)
    regcache_raw_supply (regcache,
			  gdbarch_tdep (gdbarch)->lend_regnum,
			  &regs->lend);
  if (regnum == gdbarch_tdep (gdbarch)->lcount_regnum || regnum == -1)
    regcache_raw_supply (regcache,
			  gdbarch_tdep (gdbarch)->lcount_regnum,
			  &regs->lcount);
  if (regnum == gdbarch_tdep (gdbarch)->sar_regnum || regnum == -1)
    regcache_raw_supply (regcache,
			  gdbarch_tdep (gdbarch)->sar_regnum,
			  &regs->sar);
  if (regnum >=gdbarch_tdep (gdbarch)->ar_base
      && regnum < gdbarch_tdep (gdbarch)->ar_base
		    + gdbarch_tdep (gdbarch)->num_aregs)
    regcache_raw_supply (regcache,regnum,
			  &regs->ar[regnum - gdbarch_tdep (gdbarch)->ar_base]);
  else if (regnum == -1)
    {
      for (i = 0; i < gdbarch_tdep (gdbarch)->num_aregs; ++i)
	regcache_raw_supply (regcache,
			      gdbarch_tdep (gdbarch)->ar_base + i,
			      &regs->ar[i]);
    }
}

void
supply_gregset (struct regcache *regcache, const gdb_gregset_t *gregsetp)
{
  supply_gregset_reg (regcache, gregsetp, -1);
}

void
fill_fpregset (const struct regcache *regcache,
	       gdb_fpregset_t *fpregsetp, int regnum)
{
  return;
}

void 
supply_fpregset (struct regcache *regcache,
		 const gdb_fpregset_t *fpregsetp)
{
  return;
}

/* Fetch greg-register(s) from process/thread TID
   and store value(s) in GDB's register array.  */

static void
fetch_gregs (struct regcache *regcache, int regnum)
{
  int tid = GET_THREAD_ID (inferior_ptid);
  const gdb_gregset_t regs;
  int areg;
  
  if (ptrace (PTRACE_GETREGS, tid, 0, (long) &regs) < 0)
    {
      perror_with_name (_("Couldn't get registers"));
      return;
    }
 
  supply_gregset_reg (regcache, &regs, regnum);
}

/* Store greg-register(s) in GDB's register 
   array into the process/thread specified by TID.  */

static void
store_gregs (struct regcache *regcache, int regnum)
{
  int tid = GET_THREAD_ID (inferior_ptid);
  gdb_gregset_t regs;
  int areg;

  if (ptrace (PTRACE_GETREGS, tid, 0, (long) &regs) < 0)
    {
      perror_with_name (_("Couldn't get registers"));
      return;
    }

  fill_gregset (regcache, &regs, regnum);

  if (ptrace (PTRACE_SETREGS, tid, 0, (long) &regs) < 0)
    {
      perror_with_name (_("Couldn't write registers"));
      return;
    }
}

static int xtreg_lo;
static int xtreg_high;

/* Fetch/Store Xtensa TIE registers.  Xtensa GNU/Linux PTRACE
   interface provides special requests for this.  */

static void
fetch_xtregs (struct regcache *regcache, int regnum)
{
  int tid = GET_THREAD_ID (inferior_ptid);
  const xtensa_regtable_t *ptr;
  char xtregs [XTENSA_ELF_XTREG_SIZE];

  if (ptrace (PTRACE_GETXTREGS, tid, 0, (long)&xtregs) < 0)
    perror_with_name (_("Couldn't get extended registers"));

  for (ptr = xtensa_regmap_table; ptr->name; ptr++)
    if (regnum == ptr->gdb_regnum || regnum == -1)
      regcache_raw_supply (regcache, ptr->gdb_regnum,
			   xtregs + ptr->ptrace_offset);
}

static void
store_xtregs (struct regcache *regcache, int regnum)
{
  int tid = GET_THREAD_ID (inferior_ptid);
  const xtensa_regtable_t *ptr;
  char xtregs [XTENSA_ELF_XTREG_SIZE];

  if (ptrace (PTRACE_GETXTREGS, tid, 0, (long)&xtregs) < 0)
    perror_with_name (_("Couldn't get extended registers"));

  for (ptr = xtensa_regmap_table; ptr->name; ptr++)
    if (regnum == ptr->gdb_regnum || regnum == -1)
      regcache_raw_collect (regcache, ptr->gdb_regnum,
			    xtregs + ptr->ptrace_offset);

  if (ptrace (PTRACE_SETXTREGS, tid, 0, (long)&xtregs) < 0)
    perror_with_name (_("Couldn't write extended registers"));
}

void
xtensa_linux_fetch_inferior_registers (struct target_ops *ops,
				       struct regcache *regcache, int regnum)
{
  if (regnum == -1)
    {
      fetch_gregs (regcache, regnum);
      fetch_xtregs (regcache, regnum);
    }
  else if ((regnum < xtreg_lo) || (regnum > xtreg_high))
    fetch_gregs (regcache, regnum);
  else
    fetch_xtregs (regcache, regnum);
}

void
xtensa_linux_store_inferior_registers (struct target_ops *ops,
				       struct regcache *regcache, int regnum)
{
  if (regnum == -1)
    {
      store_gregs (regcache, regnum);
      store_xtregs (regcache, regnum);
    }
  else if ((regnum < xtreg_lo) || (regnum > xtreg_high))
    store_gregs (regcache, regnum);
  else
    store_xtregs (regcache, regnum);
}

void _initialize_xtensa_linux_nat (void);

void
_initialize_xtensa_linux_nat (void)
{
  struct target_ops *t;
  const xtensa_regtable_t *ptr;

  /* Calculate the number range for extended registers.  */
  xtreg_lo = 1000000000;
  xtreg_high = -1;
  for (ptr = xtensa_regmap_table; ptr->name; ptr++)
    {
      if (ptr->gdb_regnum < xtreg_lo)
	xtreg_lo = ptr->gdb_regnum;
      if (ptr->gdb_regnum > xtreg_high)
	xtreg_high = ptr->gdb_regnum;
    }

  /* Fill in the generic GNU/Linux methods.  */
  t = linux_target ();

  /* Add our register access methods.  */
  t->to_fetch_registers = xtensa_linux_fetch_inferior_registers;
  t->to_store_registers = xtensa_linux_store_inferior_registers;

  linux_nat_add_target (t);
}
Commit	Line	Data
94a0e877 MG	1	/* Xtensa GNU/Linux native support.
94a0e877 MG	2
8acc9f48	3	Copyright (C) 2007-2013 Free Software Foundation, Inc.
94a0e877 MG	4
	5	This file is part of GDB.
	6
	7	This program is free software; you can redistribute it and/or modify
	8	it under the terms of the GNU General Public License as published by
	9	the Free Software Foundation; either version 3 of the License, or
	10	(at your option) any later version.
	11
	12	This program is distributed in the hope that it will be useful,
	13	but WITHOUT ANY WARRANTY; without even the implied warranty of
	14	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	15	GNU General Public License for more details.
	16
	17	You should have received a copy of the GNU General Public License
	18	along with this program. If not, see <http://www.gnu.org/licenses/>. */
	19
	20	#include "defs.h"
	21	#include "gdb_string.h"
	22	#include "frame.h"
	23	#include "inferior.h"
	24	#include "gdbcore.h"
	25	#include "regcache.h"
	26	#include "gdb_assert.h"
	27	#include "target.h"
	28	#include "linux-nat.h"
	29
	30	#include <stdint.h>
	31	#include <sys/types.h>
	32	#include <sys/param.h>
	33	#include <signal.h>
	34	#include <sys/user.h>
	35	#include <sys/ioctl.h>
	36	#include "gdb_wait.h"
	37	#include <fcntl.h>
	38	#include <sys/procfs.h>
	39	#include <sys/ptrace.h>
	40
	41	#include "gregset.h"
	42	#include "xtensa-tdep.h"
	43
	44	/* Extended register set depends on hardware configs.
	45	Keeping these definitions separately allows to introduce
	46	hardware-specific overlays. */
	47	#include "xtensa-xtregs.c"
	48
4e841acf	49	static int
94a0e877 MG	50	get_thread_id (ptid_t ptid)
	51	{
	52	int tid = TIDGET (ptid);
	53	if (0 == tid)
	54	tid = PIDGET (ptid);
	55	return tid;
	56	}
	57	#define GET_THREAD_ID(PTID) get_thread_id (PTID)
	58
	59	void
	60	fill_gregset (const struct regcache *regcache,
	61	gdb_gregset_t *gregsetp, int regnum)
	62	{
	63	int i;
	64	xtensa_elf_gregset_t regs = (xtensa_elf_gregset_t ) gregsetp;
	65	struct gdbarch *gdbarch = get_regcache_arch (regcache);
	66
	67	if (regnum == gdbarch_pc_regnum (gdbarch) \|\| regnum == -1)
	68	regcache_raw_collect (regcache, gdbarch_pc_regnum (gdbarch), &regs->pc);
	69	if (regnum == gdbarch_ps_regnum (gdbarch) \|\| regnum == -1)
	70	regcache_raw_collect (regcache, gdbarch_ps_regnum (gdbarch), &regs->ps);
	71
	72	if (regnum == gdbarch_tdep (gdbarch)->wb_regnum \|\| regnum == -1)
	73	regcache_raw_collect (regcache,
	74	gdbarch_tdep (gdbarch)->wb_regnum,
	75	&regs->windowbase);
	76	if (regnum == gdbarch_tdep (gdbarch)->ws_regnum \|\| regnum == -1)
	77	regcache_raw_collect (regcache,
	78	gdbarch_tdep (gdbarch)->ws_regnum,
	79	&regs->windowstart);
	80	if (regnum == gdbarch_tdep (gdbarch)->lbeg_regnum \|\| regnum == -1)
	81	regcache_raw_collect (regcache,
	82	gdbarch_tdep (gdbarch)->lbeg_regnum,
	83	&regs->lbeg);
	84	if (regnum == gdbarch_tdep (gdbarch)->lend_regnum \|\| regnum == -1)
	85	regcache_raw_collect (regcache,
	86	gdbarch_tdep (gdbarch)->lend_regnum,
	87	&regs->lend);
	88	if (regnum == gdbarch_tdep (gdbarch)->lcount_regnum \|\| regnum == -1)
	89	regcache_raw_collect (regcache,
	90	gdbarch_tdep (gdbarch)->lcount_regnum,
	91	&regs->lcount);
	92	if (regnum == gdbarch_tdep (gdbarch)->sar_regnum \|\| regnum == -1)
	93	regcache_raw_collect (regcache,
	94	gdbarch_tdep (gdbarch)->sar_regnum,
	95	&regs->sar);
	96	if (regnum >=gdbarch_tdep (gdbarch)->ar_base
	97	&& regnum < gdbarch_tdep (gdbarch)->ar_base
	98	+ gdbarch_tdep (gdbarch)->num_aregs)
	99	regcache_raw_collect (regcache,regnum,
	100	&regs->ar[regnum - gdbarch_tdep (gdbarch)->ar_base]);
	101	else if (regnum == -1)
	102	{
	103	for (i = 0; i < gdbarch_tdep (gdbarch)->num_aregs; ++i)
	104	regcache_raw_collect (regcache,
	105	gdbarch_tdep (gdbarch)->ar_base + i,
	106	&regs->ar[i]);
	107	}
	108	}
	109
	110	void
	111	supply_gregset_reg (struct regcache *regcache,
	112	const gdb_gregset_t *gregsetp, int regnum)
	113	{
114	int i;
115	xtensa_elf_gregset_t regs = (xtensa_elf_gregset_t ) gregsetp;
116
117	struct gdbarch *gdbarch = get_regcache_arch (regcache);
118
119	if (regnum == gdbarch_pc_regnum (gdbarch) \|\| regnum == -1)
120	regcache_raw_supply (regcache, gdbarch_pc_regnum (gdbarch), &regs->pc);
121	if (regnum == gdbarch_ps_regnum (gdbarch) \|\| regnum == -1)
122	regcache_raw_supply (regcache, gdbarch_ps_regnum (gdbarch), &regs->ps);
123
124	if (regnum == gdbarch_tdep (gdbarch)->wb_regnum \|\| regnum == -1)
125	regcache_raw_supply (regcache,
126	gdbarch_tdep (gdbarch)->wb_regnum,
127	&regs->windowbase);
128	if (regnum == gdbarch_tdep (gdbarch)->ws_regnum \|\| regnum == -1)
129	regcache_raw_supply (regcache,
130	gdbarch_tdep (gdbarch)->ws_regnum,
131	&regs->windowstart);
132	if (regnum == gdbarch_tdep (gdbarch)->lbeg_regnum \|\| regnum == -1)
133	regcache_raw_supply (regcache,
134	gdbarch_tdep (gdbarch)->lbeg_regnum,
135	&regs->lbeg);
136	if (regnum == gdbarch_tdep (gdbarch)->lend_regnum \|\| regnum == -1)
137	regcache_raw_supply (regcache,
138	gdbarch_tdep (gdbarch)->lend_regnum,
139	&regs->lend);
140	if (regnum == gdbarch_tdep (gdbarch)->lcount_regnum \|\| regnum == -1)
141	regcache_raw_supply (regcache,
142	gdbarch_tdep (gdbarch)->lcount_regnum,
143	&regs->lcount);
144	if (regnum == gdbarch_tdep (gdbarch)->sar_regnum \|\| regnum == -1)
145	regcache_raw_supply (regcache,
146	gdbarch_tdep (gdbarch)->sar_regnum,
147	&regs->sar);
148	if (regnum >=gdbarch_tdep (gdbarch)->ar_base
149	&& regnum < gdbarch_tdep (gdbarch)->ar_base
150	+ gdbarch_tdep (gdbarch)->num_aregs)
151	regcache_raw_supply (regcache,regnum,
152	&regs->ar[regnum - gdbarch_tdep (gdbarch)->ar_base]);
153	else if (regnum == -1)
154	{
155	for (i = 0; i < gdbarch_tdep (gdbarch)->num_aregs; ++i)
156	regcache_raw_supply (regcache,
157	gdbarch_tdep (gdbarch)->ar_base + i,
158	&regs->ar[i]);
159	}
160	}
161
162	void
163	supply_gregset (struct regcache regcache, const gdb_gregset_t gregsetp)
164	{
165	supply_gregset_reg (regcache, gregsetp, -1);
166	}
167
168	void
169	fill_fpregset (const struct regcache *regcache,
170	gdb_fpregset_t *fpregsetp, int regnum)
171	{
172	return;
173	}
174
175	void
176	supply_fpregset (struct regcache *regcache,
177	const gdb_fpregset_t *fpregsetp)
178	{
179	return;
180	}
181
182	/* Fetch greg-register(s) from process/thread TID
183	and store value(s) in GDB's register array. */
184
185	static void
186	fetch_gregs (struct regcache *regcache, int regnum)
187	{
188	int tid = GET_THREAD_ID (inferior_ptid);
189	const gdb_gregset_t regs;
190	int areg;
191
192	if (ptrace (PTRACE_GETREGS, tid, 0, (long) &regs) < 0)
193	{
194	perror_with_name (_("Couldn't get registers"));
195	return;
196	}
197
198	supply_gregset_reg (regcache, &regs, regnum);
199	}
200
201	/* Store greg-register(s) in GDB's register
202	array into the process/thread specified by TID. */
203
204	static void
205	store_gregs (struct regcache *regcache, int regnum)
206	{
207	int tid = GET_THREAD_ID (inferior_ptid);
208	gdb_gregset_t regs;
209	int areg;
210
211	if (ptrace (PTRACE_GETREGS, tid, 0, (long) &regs) < 0)
212	{
213	perror_with_name (_("Couldn't get registers"));
214	return;
215	}
216
217	fill_gregset (regcache, &regs, regnum);
218
219	if (ptrace (PTRACE_SETREGS, tid, 0, (long) &regs) < 0)
220	{
221	perror_with_name (_("Couldn't write registers"));
222	return;
223	}
224	}
225
226	static int xtreg_lo;
227	static int xtreg_high;
228
229	/* Fetch/Store Xtensa TIE registers. Xtensa GNU/Linux PTRACE
230	interface provides special requests for this. */
231
232	static void
233	fetch_xtregs (struct regcache *regcache, int regnum)
234	{
235	int tid = GET_THREAD_ID (inferior_ptid);
236	const xtensa_regtable_t *ptr;
237	char xtregs [XTENSA_ELF_XTREG_SIZE];
238
239	if (ptrace (PTRACE_GETXTREGS, tid, 0, (long)&xtregs) < 0)
240	perror_with_name (_("Couldn't get extended registers"));
241
242	for (ptr = xtensa_regmap_table; ptr->name; ptr++)
243	if (regnum == ptr->gdb_regnum \|\| regnum == -1)
244	regcache_raw_supply (regcache, ptr->gdb_regnum,
245	xtregs + ptr->ptrace_offset);
246	}
247
248	static void
249	store_xtregs (struct regcache *regcache, int regnum)
250	{
251	int tid = GET_THREAD_ID (inferior_ptid);
252	const xtensa_regtable_t *ptr;
253	char xtregs [XTENSA_ELF_XTREG_SIZE];
254
255	if (ptrace (PTRACE_GETXTREGS, tid, 0, (long)&xtregs) < 0)
256	perror_with_name (_("Couldn't get extended registers"));
257
258	for (ptr = xtensa_regmap_table; ptr->name; ptr++)
259	if (regnum == ptr->gdb_regnum \|\| regnum == -1)
260	regcache_raw_collect (regcache, ptr->gdb_regnum,
261	xtregs + ptr->ptrace_offset);
262
263	if (ptrace (PTRACE_SETXTREGS, tid, 0, (long)&xtregs) < 0)
264	perror_with_name (_("Couldn't write extended registers"));
265	}
266
267	void
28439f5e PA	268	xtensa_linux_fetch_inferior_registers (struct target_ops *ops,
28439f5e PA	269	struct regcache *regcache, int regnum)
94a0e877 MG	270	{
	271	if (regnum == -1)
	272	{
	273	fetch_gregs (regcache, regnum);
	274	fetch_xtregs (regcache, regnum);
	275	}
	276	else if ((regnum < xtreg_lo) \|\| (regnum > xtreg_high))
	277	fetch_gregs (regcache, regnum);
	278	else
	279	fetch_xtregs (regcache, regnum);
	280	}
	281
	282	void
28439f5e PA	283	xtensa_linux_store_inferior_registers (struct target_ops *ops,
28439f5e PA	284	struct regcache *regcache, int regnum)
94a0e877 MG	285	{
	286	if (regnum == -1)
	287	{
	288	store_gregs (regcache, regnum);
	289	store_xtregs (regcache, regnum);
	290	}
	291	else if ((regnum < xtreg_lo) \|\| (regnum > xtreg_high))
	292	store_gregs (regcache, regnum);
	293	else
	294	store_xtregs (regcache, regnum);
	295	}
	296
	297	void _initialize_xtensa_linux_nat (void);
	298
	299	void
	300	_initialize_xtensa_linux_nat (void)
	301	{
	302	struct target_ops *t;
	303	const xtensa_regtable_t *ptr;
	304
	305	/* Calculate the number range for extended registers. */
	306	xtreg_lo = 1000000000;
	307	xtreg_high = -1;
	308	for (ptr = xtensa_regmap_table; ptr->name; ptr++)
	309	{
	310	if (ptr->gdb_regnum < xtreg_lo)
	311	xtreg_lo = ptr->gdb_regnum;
	312	if (ptr->gdb_regnum > xtreg_high)
	313	xtreg_high = ptr->gdb_regnum;
	314	}
	315
	316	/* Fill in the generic GNU/Linux methods. */
	317	t = linux_target ();
	318
	319	/* Add our register access methods. */
	320	t->to_fetch_registers = xtensa_linux_fetch_inferior_registers;
	321	t->to_store_registers = xtensa_linux_store_inferior_registers;
	322
	323	linux_nat_add_target (t);
	324	}