path: root/gdb/rs6000-nat.c

/* IBM RS/6000 native-dependent code for GDB, the GNU debugger.

   Copyright (C) 1986-2013 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 "inferior.h"
#include "target.h"
#include "gdbcore.h"
#include "symfile.h"
#include "objfiles.h"
#include "libbfd.h"		/* For bfd_default_set_arch_mach (FIXME) */
#include "bfd.h"
#include "exceptions.h"
#include "gdb-stabs.h"
#include "regcache.h"
#include "arch-utils.h"
#include "inf-child.h"
#include "inf-ptrace.h"
#include "ppc-tdep.h"
#include "rs6000-tdep.h"
#include "exec.h"
#include "observer.h"
#include "xcoffread.h"

#include <sys/ptrace.h>
#include <sys/reg.h>

#include <sys/param.h>
#include <sys/dir.h>
#include <sys/user.h>
#include <signal.h>
#include <sys/ioctl.h>
#include <fcntl.h>
#include <errno.h>

#include <a.out.h>
#include <sys/file.h>
#include "gdb_stat.h"
#include "gdb_bfd.h"
#include <sys/core.h>
#define __LDINFO_PTRACE32__	/* for __ld_info32 */
#define __LDINFO_PTRACE64__	/* for __ld_info64 */
#include <sys/ldr.h>
#include <sys/systemcfg.h>
#include "xml-utils.h"

/* On AIX4.3+, sys/ldr.h provides different versions of struct ld_info for
   debugging 32-bit and 64-bit processes.  Define a typedef and macros for
   accessing fields in the appropriate structures.  */

/* In 32-bit compilation mode (which is the only mode from which ptrace()
   works on 4.3), __ld_info32 is #defined as equivalent to ld_info.  */

#ifdef __ld_info32
# define ARCH3264
#endif

/* Return whether the current architecture is 64-bit.  */

#ifndef ARCH3264
# define ARCH64() 0
#else
# define ARCH64() (register_size (target_gdbarch (), 0) == 8)
#endif

/* Union of 32-bit and 64-bit versions of ld_info.  */

typedef union {
#ifndef ARCH3264
  struct ld_info l32;
  struct ld_info l64;
#else
  struct __ld_info32 l32;
  struct __ld_info64 l64;
#endif
} LdInfo;

/* If compiling with 32-bit and 64-bit debugging capability (e.g. AIX 4.x),
   declare and initialize a variable named VAR suitable for use as the arch64
   parameter to the various LDI_*() macros.  */

#ifndef ARCH3264
# define ARCH64_DECL(var)
#else
# define ARCH64_DECL(var) int var = ARCH64 ()
#endif

/* Return LDI's FIELD for a 64-bit process if ARCH64 and for a 32-bit process
   otherwise.  This technique only works for FIELDs with the same data type in
   32-bit and 64-bit versions of ld_info.  */

#ifndef ARCH3264
# define LDI_FIELD(ldi, arch64, field) (ldi)->l32.ldinfo_##field
#else
# define LDI_FIELD(ldi, arch64, field) \
  (arch64 ? (ldi)->l64.ldinfo_##field : (ldi)->l32.ldinfo_##field)
#endif

/* Return various LDI fields for a 64-bit process if ARCH64 and for a 32-bit
   process otherwise.  */

#define LDI_NEXT(ldi, arch64)		LDI_FIELD(ldi, arch64, next)
#define LDI_FD(ldi, arch64)		LDI_FIELD(ldi, arch64, fd)
#define LDI_FILENAME(ldi, arch64)	LDI_FIELD(ldi, arch64, filename)

static void exec_one_dummy_insn (struct regcache *);

static LONGEST rs6000_xfer_shared_libraries
  (struct target_ops *ops, enum target_object object,
   const char *annex, gdb_byte *readbuf, const gdb_byte *writebuf,
   ULONGEST offset, LONGEST len);

/* Given REGNO, a gdb register number, return the corresponding
   number suitable for use as a ptrace() parameter.  Return -1 if
   there's no suitable mapping.  Also, set the int pointed to by
   ISFLOAT to indicate whether REGNO is a floating point register.  */

static int
regmap (struct gdbarch *gdbarch, int regno, int *isfloat)
{
  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);

  *isfloat = 0;
  if (tdep->ppc_gp0_regnum <= regno
      && regno < tdep->ppc_gp0_regnum + ppc_num_gprs)
    return regno;
  else if (tdep->ppc_fp0_regnum >= 0
           && tdep->ppc_fp0_regnum <= regno
           && regno < tdep->ppc_fp0_regnum + ppc_num_fprs)
    {
      *isfloat = 1;
      return regno - tdep->ppc_fp0_regnum + FPR0;
    }
  else if (regno == gdbarch_pc_regnum (gdbarch))
    return IAR;
  else if (regno == tdep->ppc_ps_regnum)
    return MSR;
  else if (regno == tdep->ppc_cr_regnum)
    return CR;
  else if (regno == tdep->ppc_lr_regnum)
    return LR;
  else if (regno == tdep->ppc_ctr_regnum)
    return CTR;
  else if (regno == tdep->ppc_xer_regnum)
    return XER;
  else if (tdep->ppc_fpscr_regnum >= 0
           && regno == tdep->ppc_fpscr_regnum)
    return FPSCR;
  else if (tdep->ppc_mq_regnum >= 0 && regno == tdep->ppc_mq_regnum)
    return MQ;
  else
    return -1;
}

/* Call ptrace(REQ, ID, ADDR, DATA, BUF).  */

static int
rs6000_ptrace32 (int req, int id, int *addr, int data, int *buf)
{
  int ret = ptrace (req, id, (int *)addr, data, buf);
#if 0
  printf ("rs6000_ptrace32 (%d, %d, 0x%x, %08x, 0x%x) = 0x%x\n",
	  req, id, (unsigned int)addr, data, (unsigned int)buf, ret);
#endif
  return ret;
}

/* Call ptracex(REQ, ID, ADDR, DATA, BUF).  */

static int
rs6000_ptrace64 (int req, int id, long long addr, int data, void *buf)
{
#ifdef ARCH3264
  int ret = ptracex (req, id, addr, data, buf);
#else
  int ret = 0;
#endif
#if 0
  printf ("rs6000_ptrace64 (%d, %d, %s, %08x, 0x%x) = 0x%x\n",
	  req, id, hex_string (addr), data, (unsigned int)buf, ret);
#endif
  return ret;
}

/* Fetch register REGNO from the inferior.  */

static void
fetch_register (struct regcache *regcache, int regno)
{
  struct gdbarch *gdbarch = get_regcache_arch (regcache);
  int addr[MAX_REGISTER_SIZE];
  int nr, isfloat;

  /* Retrieved values may be -1, so infer errors from errno.  */
  errno = 0;

  nr = regmap (gdbarch, regno, &isfloat);

  /* Floating-point registers.  */
  if (isfloat)
    rs6000_ptrace32 (PT_READ_FPR, PIDGET (inferior_ptid), addr, nr, 0);

  /* Bogus register number.  */
  else if (nr < 0)
    {
      if (regno >= gdbarch_num_regs (gdbarch))
	fprintf_unfiltered (gdb_stderr,
			    "gdb error: register no %d not implemented.\n",
			    regno);
      return;
    }

  /* Fixed-point registers.  */
  else
    {
      if (!ARCH64 ())
	*addr = rs6000_ptrace32 (PT_READ_GPR, PIDGET (inferior_ptid),
				 (int *) nr, 0, 0);
      else
	{
	  /* PT_READ_GPR requires the buffer parameter to point to long long,
	     even if the register is really only 32 bits.  */
	  long long buf;
	  rs6000_ptrace64 (PT_READ_GPR, PIDGET (inferior_ptid), nr, 0, &buf);
	  if (register_size (gdbarch, regno) == 8)
	    memcpy (addr, &buf, 8);
	  else
	    *addr = buf;
	}
    }

  if (!errno)
    regcache_raw_supply (regcache, regno, (char *) addr);
  else
    {
#if 0
      /* FIXME: this happens 3 times at the start of each 64-bit program.  */
      perror (_("ptrace read"));
#endif
      errno = 0;
    }
}

/* Store register REGNO back into the inferior.  */

static void
store_register (struct regcache *regcache, int regno)
{
  struct gdbarch *gdbarch = get_regcache_arch (regcache);
  int addr[MAX_REGISTER_SIZE];
  int nr, isfloat;

  /* Fetch the register's value from the register cache.  */
  regcache_raw_collect (regcache, regno, addr);

  /* -1 can be a successful return value, so infer errors from errno.  */
  errno = 0;

  nr = regmap (gdbarch, regno, &isfloat);

  /* Floating-point registers.  */
  if (isfloat)
    rs6000_ptrace32 (PT_WRITE_FPR, PIDGET (inferior_ptid), addr, nr, 0);

  /* Bogus register number.  */
  else if (nr < 0)
    {
      if (regno >= gdbarch_num_regs (gdbarch))
	fprintf_unfiltered (gdb_stderr,
			    "gdb error: register no %d not implemented.\n",
			    regno);
    }

  /* Fixed-point registers.  */
  else
    {
      if (regno == gdbarch_sp_regnum (gdbarch))
	/* Execute one dummy instruction (which is a breakpoint) in inferior
	   process to give kernel a chance to do internal housekeeping.
	   Otherwise the following ptrace(2) calls will mess up user stack
	   since kernel will get confused about the bottom of the stack
	   (%sp).  */
	exec_one_dummy_insn (regcache);

      /* The PT_WRITE_GPR operation is rather odd.  For 32-bit inferiors,
         the register's value is passed by value, but for 64-bit inferiors,
	 the address of a buffer containing the value is passed.  */
      if (!ARCH64 ())
	rs6000_ptrace32 (PT_WRITE_GPR, PIDGET (inferior_ptid),
			 (int *) nr, *addr, 0);
      else
	{
	  /* PT_WRITE_GPR requires the buffer parameter to point to an 8-byte
	     area, even if the register is really only 32 bits.  */
	  long long buf;
	  if (register_size (gdbarch, regno) == 8)
	    memcpy (&buf, addr, 8);
	  else
	    buf = *addr;
	  rs6000_ptrace64 (PT_WRITE_GPR, PIDGET (inferior_ptid), nr, 0, &buf);
	}
    }

  if (errno)
    {
      perror (_("ptrace write"));
      errno = 0;
    }
}

/* Read from the inferior all registers if REGNO == -1 and just register
   REGNO otherwise.  */

static void
rs6000_fetch_inferior_registers (struct target_ops *ops,
				 struct regcache *regcache, int regno)
{
  struct gdbarch *gdbarch = get_regcache_arch (regcache);
  if (regno != -1)
    fetch_register (regcache, regno);

  else
    {
      struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);

      /* Read 32 general purpose registers.  */
      for (regno = tdep->ppc_gp0_regnum;
           regno < tdep->ppc_gp0_regnum + ppc_num_gprs;
	   regno++)
	{
	  fetch_register (regcache, regno);
	}

      /* Read general purpose floating point registers.  */
      if (tdep->ppc_fp0_regnum >= 0)
        for (regno = 0; regno < ppc_num_fprs; regno++)
          fetch_register (regcache, tdep->ppc_fp0_regnum + regno);

      /* Read special registers.  */
      fetch_register (regcache, gdbarch_pc_regnum (gdbarch));
      fetch_register (regcache, tdep->ppc_ps_regnum);
      fetch_register (regcache, tdep->ppc_cr_regnum);
      fetch_register (regcache, tdep->ppc_lr_regnum);
      fetch_register (regcache, tdep->ppc_ctr_regnum);
      fetch_register (regcache, tdep->ppc_xer_regnum);
      if (tdep->ppc_fpscr_regnum >= 0)
        fetch_register (regcache, tdep->ppc_fpscr_regnum);
      if (tdep->ppc_mq_regnum >= 0)
	fetch_register (regcache, tdep->ppc_mq_regnum);
    }
}

/* Store our register values back into the inferior.
   If REGNO is -1, do this for all registers.
   Otherwise, REGNO specifies which register (so we can save time).  */

static void
rs6000_store_inferior_registers (struct target_ops *ops,
				 struct regcache *regcache, int regno)
{
  struct gdbarch *gdbarch = get_regcache_arch (regcache);
  if (regno != -1)
    store_register (regcache, regno);

  else
    {
      struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);

      /* Write general purpose registers first.  */
      for (regno = tdep->ppc_gp0_regnum;
           regno < tdep->ppc_gp0_regnum + ppc_num_gprs;
	   regno++)
	{
	  store_register (regcache, regno);
	}

      /* Write floating point registers.  */
      if (tdep->ppc_fp0_regnum >= 0)
        for (regno = 0; regno < ppc_num_fprs; regno++)
          store_register (regcache, tdep->ppc_fp0_regnum + regno);

      /* Write special registers.  */
      store_register (regcache, gdbarch_pc_regnum (gdbarch));
      store_register (regcache, tdep->ppc_ps_regnum);
      store_register (regcache, tdep->ppc_cr_regnum);
      store_register (regcache, tdep->ppc_lr_regnum);
      store_register (regcache, tdep->ppc_ctr_regnum);
      store_register (regcache, tdep->ppc_xer_regnum);
      if (tdep->ppc_fpscr_regnum >= 0)
        store_register (regcache, tdep->ppc_fpscr_regnum);
      if (tdep->ppc_mq_regnum >= 0)
	store_register (regcache, tdep->ppc_mq_regnum);
    }
}


/* Attempt a transfer all LEN bytes starting at OFFSET between the
   inferior's OBJECT:ANNEX space and GDB's READBUF/WRITEBUF buffer.
   Return the number of bytes actually transferred.  */

static LONGEST
rs6000_xfer_partial (struct target_ops *ops, enum target_object object,
		     const char *annex, gdb_byte *readbuf,
		     const gdb_byte *writebuf,
		     ULONGEST offset, LONGEST len)
{
  pid_t pid = ptid_get_pid (inferior_ptid);
  int arch64 = ARCH64 ();

  switch (object)
    {
    case TARGET_OBJECT_AIX_LIBRARIES:
      return rs6000_xfer_shared_libraries (ops, object, annex,
					   readbuf, writebuf,
					   offset, len);
    case TARGET_OBJECT_MEMORY:
      {
	union
	{
	  PTRACE_TYPE_RET word;
	  gdb_byte byte[sizeof (PTRACE_TYPE_RET)];
	} buffer;
	ULONGEST rounded_offset;
	LONGEST partial_len;

	/* Round the start offset down to the next long word
	   boundary.  */
	rounded_offset = offset & -(ULONGEST) sizeof (PTRACE_TYPE_RET);

	/* Since ptrace will transfer a single word starting at that
	   rounded_offset the partial_len needs to be adjusted down to
	   that (remember this function only does a single transfer).
	   Should the required length be even less, adjust it down
	   again.  */
	partial_len = (rounded_offset + sizeof (PTRACE_TYPE_RET)) - offset;
	if (partial_len > len)
	  partial_len = len;

	if (writebuf)
	  {
	    /* If OFFSET:PARTIAL_LEN is smaller than
	       ROUNDED_OFFSET:WORDSIZE then a read/modify write will
	       be needed.  Read in the entire word.  */
	    if (rounded_offset < offset
		|| (offset + partial_len
		    < rounded_offset + sizeof (PTRACE_TYPE_RET)))
	      {
		/* Need part of initial word -- fetch it.  */
		if (arch64)
		  buffer.word = rs6000_ptrace64 (PT_READ_I, pid,
						 rounded_offset, 0, NULL);
		else
		  buffer.word = rs6000_ptrace32 (PT_READ_I, pid,
						 (int *) (uintptr_t)
						 rounded_offset,
						 0, NULL);
	      }

	    /* Copy data to be written over corresponding part of
	       buffer.  */
	    memcpy (buffer.byte + (offset - rounded_offset),
		    writebuf, partial_len);

	    errno = 0;
	    if (arch64)
	      rs6000_ptrace64 (PT_WRITE_D, pid,
			       rounded_offset, buffer.word, NULL);
	    else
	      rs6000_ptrace32 (PT_WRITE_D, pid,
			       (int *) (uintptr_t) rounded_offset,
			       buffer.word, NULL);
	    if (errno)
	      return 0;
	  }

	if (readbuf)
	  {
	    errno = 0;
	    if (arch64)
	      buffer.word = rs6000_ptrace64 (PT_READ_I, pid,
					     rounded_offset, 0, NULL);
	    else
	      buffer.word = rs6000_ptrace32 (PT_READ_I, pid,
					     (int *)(uintptr_t)rounded_offset,
					     0, NULL);
	    if (errno)
	      return 0;

	    /* Copy appropriate bytes out of the buffer.  */
	    memcpy (readbuf, buffer.byte + (offset - rounded_offset),
		    partial_len);
	  }

	return partial_len;
      }

    default:
      return -1;
    }
}

/* Wait for the child specified by PTID to do something.  Return the
   process ID of the child, or MINUS_ONE_PTID in case of error; store
   the status in *OURSTATUS.  */

static ptid_t
rs6000_wait (struct target_ops *ops,
	     ptid_t ptid, struct target_waitstatus *ourstatus, int options)
{
  pid_t pid;
  int status, save_errno;

  do
    {
      set_sigint_trap ();

      do
	{
	  pid = waitpid (ptid_get_pid (ptid), &status, 0);
	  save_errno = errno;
	}
      while (pid == -1 && errno == EINTR);

      clear_sigint_trap ();

      if (pid == -1)
	{
	  fprintf_unfiltered (gdb_stderr,
			      _("Child process unexpectedly missing: %s.\n"),
			      safe_strerror (save_errno));

	  /* Claim it exited with unknown signal.  */
	  ourstatus->kind = TARGET_WAITKIND_SIGNALLED;
	  ourstatus->value.sig = GDB_SIGNAL_UNKNOWN;
	  return inferior_ptid;
	}

      /* Ignore terminated detached child processes.  */
      if (!WIFSTOPPED (status) && pid != ptid_get_pid (inferior_ptid))
	pid = -1;
    }
  while (pid == -1);

  /* AIX has a couple of strange returns from wait().  */

  /* stop after load" status.  */
  if (status == 0x57c)
    ourstatus->kind = TARGET_WAITKIND_LOADED;
  /* signal 0.  I have no idea why wait(2) returns with this status word.  */
  else if (status == 0x7f)
    ourstatus->kind = TARGET_WAITKIND_SPURIOUS;
  /* A normal waitstatus.  Let the usual macros deal with it.  */
  else
    store_waitstatus (ourstatus, status);

  return pid_to_ptid (pid);
}

/* Execute one dummy breakpoint instruction.  This way we give the kernel
   a chance to do some housekeeping and update inferior's internal data,
   including u_area.  */

static void
exec_one_dummy_insn (struct regcache *regcache)
{
#define	DUMMY_INSN_ADDR	AIX_TEXT_SEGMENT_BASE+0x200

  struct gdbarch *gdbarch = get_regcache_arch (regcache);
  int ret, status, pid;
  CORE_ADDR prev_pc;
  void *bp;

  /* We plant one dummy breakpoint into DUMMY_INSN_ADDR address.  We
     assume that this address will never be executed again by the real
     code.  */

  bp = deprecated_insert_raw_breakpoint (gdbarch, NULL, DUMMY_INSN_ADDR);

  /* You might think this could be done with a single ptrace call, and
     you'd be correct for just about every platform I've ever worked
     on.  However, rs6000-ibm-aix4.1.3 seems to have screwed this up --
     the inferior never hits the breakpoint (it's also worth noting
     powerpc-ibm-aix4.1.3 works correctly).  */
  prev_pc = regcache_read_pc (regcache);
  regcache_write_pc (regcache, DUMMY_INSN_ADDR);
  if (ARCH64 ())
    ret = rs6000_ptrace64 (PT_CONTINUE, PIDGET (inferior_ptid), 1, 0, NULL);
  else
    ret = rs6000_ptrace32 (PT_CONTINUE, PIDGET (inferior_ptid),
			   (int *) 1, 0, NULL);

  if (ret != 0)
    perror (_("pt_continue"));

  do
    {
      pid = waitpid (PIDGET (inferior_ptid), &status, 0);
    }
  while (pid != PIDGET (inferior_ptid));

  regcache_write_pc (regcache, prev_pc);
  deprecated_remove_raw_breakpoint (gdbarch, bp);
}


/* Set the current architecture from the host running GDB.  Called when
   starting a child process.  */

static void (*super_create_inferior) (struct target_ops *,char *exec_file, 
				      char *allargs, char **env, int from_tty);
static void
rs6000_create_inferior (struct target_ops * ops, char *exec_file,
			char *allargs, char **env, int from_tty)
{
  enum bfd_architecture arch;
  unsigned long mach;
  bfd abfd;
  struct gdbarch_info info;

  super_create_inferior (ops, exec_file, allargs, env, from_tty);

  if (__power_rs ())
    {
      arch = bfd_arch_rs6000;
      mach = bfd_mach_rs6k;
    }
  else
    {
      arch = bfd_arch_powerpc;
      mach = bfd_mach_ppc;
    }

  /* FIXME: schauer/2002-02-25:
     We don't know if we are executing a 32 or 64 bit executable,
     and have no way to pass the proper word size to rs6000_gdbarch_init.
     So we have to avoid switching to a new architecture, if the architecture
     matches already.
     Blindly calling rs6000_gdbarch_init used to work in older versions of
     GDB, as rs6000_gdbarch_init incorrectly used the previous tdep to
     determine the wordsize.  */
  if (exec_bfd)
    {
      const struct bfd_arch_info *exec_bfd_arch_info;

      exec_bfd_arch_info = bfd_get_arch_info (exec_bfd);
      if (arch == exec_bfd_arch_info->arch)
	return;
    }

  bfd_default_set_arch_mach (&abfd, arch, mach);

  gdbarch_info_init (&info);
  info.bfd_arch_info = bfd_get_arch_info (&abfd);
  info.abfd = exec_bfd;

  if (!gdbarch_update_p (info))
    internal_error (__FILE__, __LINE__,
		    _("rs6000_create_inferior: failed "
		      "to select architecture"));
}


/* Shared Object support.  */

/* Return the LdInfo data for the given process.  Raises an error
   if the data could not be obtained.

   The returned value must be deallocated after use.  */

static LdInfo *
rs6000_ptrace_ldinfo (ptid_t ptid)
{
  const int pid = ptid_get_pid (ptid);
  int ldi_size = 1024;
  LdInfo *ldi = xmalloc (ldi_size);
  int rc = -1;

  while (1)
    {
      if (ARCH64 ())
	rc = rs6000_ptrace64 (PT_LDINFO, pid, (unsigned long) ldi, ldi_size,
			      NULL);
      else
	rc = rs6000_ptrace32 (PT_LDINFO, pid, (int *) ldi, ldi_size, NULL);

      if (rc != -1)
	break; /* Success, we got the entire ld_info data.  */

      if (errno != ENOMEM)
	perror_with_name (_("ptrace ldinfo"));

      /* ldi is not big enough.  Double it and try again.  */
      ldi_size *= 2;
      ldi = xrealloc (ldi, ldi_size);
    }

  return ldi;
}

/* Assuming ABFD refers to a core file, return the LdInfo data
   stored in that core file.  Raises an error if the data could
   not be read or extracted.

   The returned value much be deallocated after use.  */

static LdInfo *
rs6000_core_ldinfo (bfd *abfd)
{
  struct bfd_section *ldinfo_sec;
  int ldinfo_size;
  gdb_byte *ldinfo_buf;
  struct cleanup *cleanup;

  ldinfo_sec = bfd_get_section_by_name (abfd, ".ldinfo");
  if (ldinfo_sec == NULL)
    error (_("cannot find .ldinfo section from core file: %s\n"),
	   bfd_errmsg (bfd_get_error ()));
  ldinfo_size = bfd_get_section_size (ldinfo_sec);

  ldinfo_buf = xmalloc (ldinfo_size);
  cleanup = make_cleanup (xfree, ldinfo_buf);

  if (! bfd_get_section_contents (abfd, ldinfo_sec,
				  ldinfo_buf, 0, ldinfo_size))
    error (_("unable to read .ldinfo section from core file: %s\n"),
	   bfd_errmsg (bfd_get_error ()));

  discard_cleanups (cleanup);
  return (LdInfo *) ldinfo_buf;
}

/* Append to OBJSTACK an XML string description of the shared library
   corresponding to LDI, following the TARGET_OBJECT_AIX_LIBRARIES
   format.  */

static void
rs6000_xfer_shared_library (LdInfo *ldi, struct obstack *obstack)
{
  const int arch64 = ARCH64 ();
  const char *archive_name = LDI_FILENAME (ldi, arch64);
  const char *member_name = archive_name + strlen (archive_name) + 1;
  CORE_ADDR text_addr, data_addr;
  ULONGEST text_size, data_size;
  char *p;

  if (arch64)
    {
      text_addr = ldi->l64.ldinfo_textorg;
      text_size = ldi->l64.ldinfo_textsize;
      data_addr = ldi->l64.ldinfo_dataorg;
      data_size = ldi->l64.ldinfo_datasize;
    }
  else
    {
      /* The text and data addresses are defined as pointers.
	 To avoid sign-extending their value in the assignments
	 below, we cast their value to unsigned long first.  */
      text_addr = (unsigned long) ldi->l32.ldinfo_textorg;
      text_size = ldi->l32.ldinfo_textsize;
      data_addr = (unsigned long) ldi->l32.ldinfo_dataorg;
      data_size = ldi->l32.ldinfo_datasize;
    }

  obstack_grow_str (obstack, "<library name=\"");
  p = xml_escape_text (archive_name);
  obstack_grow_str (obstack, p);
  xfree (p);
  obstack_grow_str (obstack, "\"");

  if (member_name[0] != '\0')
    {
      obstack_grow_str (obstack, " member=\"");
      p = xml_escape_text (member_name);
      obstack_grow_str (obstack, p);
      xfree (p);
      obstack_grow_str (obstack, "\"");
    }

  obstack_grow_str (obstack, " text_addr=\"");
  obstack_grow_str (obstack, core_addr_to_string (text_addr));
  obstack_grow_str (obstack, "\"");

  obstack_grow_str (obstack, " text_size=\"");
  obstack_grow_str (obstack, pulongest (text_size));
  obstack_grow_str (obstack, "\"");

  obstack_grow_str (obstack, " data_addr=\"");
  obstack_grow_str (obstack, core_addr_to_string (data_addr));
  obstack_grow_str (obstack, "\"");

  obstack_grow_str (obstack, " data_size=\"");
  obstack_grow_str (obstack, pulongest (data_size));
  obstack_grow_str (obstack, "\"");

  obstack_grow_str (obstack, "></library>");
}

/* Implement the to_xfer_partial target_ops method for
   TARGET_OBJECT_AIX_LIBRARIES objects.  */

static LONGEST
rs6000_xfer_shared_libraries
  (struct target_ops *ops, enum target_object object,
   const char *annex, gdb_byte *readbuf, const gdb_byte *writebuf,
   ULONGEST offset, LONGEST len)
{
  const int arch64 = ARCH64 ();
  LdInfo *ldi_data;
  LdInfo *ldi;
  struct obstack obstack;
  const char *buf;
  LONGEST len_avail;

  if (writebuf)
    return -1;

  /* Get the ldinfo raw data: If debugging a live process, we get it
     using ptrace.  Otherwise, the info is stored in the .ldinfo
     section of the core file.  */

  if (target_has_execution)
    ldi_data = rs6000_ptrace_ldinfo (inferior_ptid);
  else
    ldi_data = rs6000_core_ldinfo (core_bfd);

  /* Convert the raw data into an XML representation.  */

  obstack_init (&obstack);
  obstack_grow_str (&obstack, "<library-list version=\"1.0\">\n");

  ldi = ldi_data;
  while (1)
    {
      /* Close the fd.  We cannot use it, because we cannot assume
	 that the user of this descriptor will be in the same
	 process.  */
      close (LDI_FD (ldi, arch64));

      rs6000_xfer_shared_library (ldi, &obstack);

      if (!LDI_NEXT (ldi, arch64))
	break;
      ldi = (LdInfo *) ((char *) ldi + LDI_NEXT (ldi, arch64));
    }

  xfree (ldi_data);

  obstack_grow_str0 (&obstack, "</library-list>\n");

  buf = obstack_finish (&obstack);
  len_avail = strlen (buf);
  if (offset >= len_avail)
    len= 0;
  else
    {
      if (len > len_avail - offset)
        len = len_avail - offset;
      memcpy (readbuf, buf + offset, len);
    }

  obstack_free (&obstack, NULL);
  return len;
}

void _initialize_rs6000_nat (void);

void
_initialize_rs6000_nat (void)
{
  struct target_ops *t;

  t = inf_ptrace_target ();
  t->to_fetch_registers = rs6000_fetch_inferior_registers;
  t->to_store_registers = rs6000_store_inferior_registers;
  t->to_xfer_partial = rs6000_xfer_partial;

  super_create_inferior = t->to_create_inferior;
  t->to_create_inferior = rs6000_create_inferior;

  t->to_wait = rs6000_wait;

  add_target (t);
}