gdb/rs6000-nat.c

   1 /* IBM RS/6000 native-dependent code for GDB, the GNU debugger.
   2
   3    Copyright (C) 1986-2013 Free Software Foundation, Inc.
   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 "inferior.h"
  22 #include "target.h"
  23 #include "gdbcore.h"
  24 #include "symfile.h"
  25 #include "objfiles.h"
  26 #include "libbfd.h"             /* For bfd_default_set_arch_mach (FIXME) */
  27 #include "bfd.h"
  28 #include "exceptions.h"
  29 #include "gdb-stabs.h"
  30 #include "regcache.h"
  31 #include "arch-utils.h"
  32 #include "inf-child.h"
  33 #include "inf-ptrace.h"
  34 #include "ppc-tdep.h"
  35 #include "rs6000-tdep.h"
  36 #include "rs6000-aix-tdep.h"
  37 #include "exec.h"
  38 #include "observer.h"
  39 #include "xcoffread.h"
  40
  41 #include <sys/ptrace.h>
  42 #include <sys/reg.h>
  43
  44 #include <sys/param.h>
  45 #include <sys/dir.h>
  46 #include <sys/user.h>
  47 #include <signal.h>
  48 #include <sys/ioctl.h>
  49 #include <fcntl.h>
  50 #include <errno.h>
  51
  52 #include <a.out.h>
  53 #include <sys/file.h>
  54 #include "gdb_stat.h"
  55 #include "gdb_bfd.h"
  56 #include <sys/core.h>
  57 #define __LDINFO_PTRACE32__     /* for __ld_info32 */
  58 #define __LDINFO_PTRACE64__     /* for __ld_info64 */
  59 #include <sys/ldr.h>
  60 #include <sys/systemcfg.h>
  61
  62 /* On AIX4.3+, sys/ldr.h provides different versions of struct ld_info for
  63    debugging 32-bit and 64-bit processes.  Define a typedef and macros for
  64    accessing fields in the appropriate structures.  */
  65
  66 /* In 32-bit compilation mode (which is the only mode from which ptrace()
  67    works on 4.3), __ld_info32 is #defined as equivalent to ld_info.  */
  68
  69 #ifdef __ld_info32
  70 # define ARCH3264
  71 #endif
  72
  73 /* Return whether the current architecture is 64-bit.  */
  74
  75 #ifndef ARCH3264
  76 # define ARCH64() 0
  77 #else
  78 # define ARCH64() (register_size (target_gdbarch (), 0) == 8)
  79 #endif
  80
  81 static void exec_one_dummy_insn (struct regcache *);
  82
  83 static LONGEST rs6000_xfer_shared_libraries
  84   (struct target_ops *ops, enum target_object object,
  85    const char *annex, gdb_byte *readbuf, const gdb_byte *writebuf,
  86    ULONGEST offset, LONGEST len);
  87
  88 /* Given REGNO, a gdb register number, return the corresponding
  89    number suitable for use as a ptrace() parameter.  Return -1 if
  90    there's no suitable mapping.  Also, set the int pointed to by
  91    ISFLOAT to indicate whether REGNO is a floating point register.  */
  92
  93 static int
  94 regmap (struct gdbarch *gdbarch, int regno, int *isfloat)
  95 {
  96   struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
  97
  98   *isfloat = 0;
  99   if (tdep->ppc_gp0_regnum <= regno
 100       && regno < tdep->ppc_gp0_regnum + ppc_num_gprs)
 101     return regno;
 102   else if (tdep->ppc_fp0_regnum >= 0
 103            && tdep->ppc_fp0_regnum <= regno
 104            && regno < tdep->ppc_fp0_regnum + ppc_num_fprs)
 105     {
 106       *isfloat = 1;
 107       return regno - tdep->ppc_fp0_regnum + FPR0;
 108     }
 109   else if (regno == gdbarch_pc_regnum (gdbarch))
 110     return IAR;
 111   else if (regno == tdep->ppc_ps_regnum)
 112     return MSR;
 113   else if (regno == tdep->ppc_cr_regnum)
 114     return CR;
 115   else if (regno == tdep->ppc_lr_regnum)
 116     return LR;
 117   else if (regno == tdep->ppc_ctr_regnum)
 118     return CTR;
 119   else if (regno == tdep->ppc_xer_regnum)
 120     return XER;
 121   else if (tdep->ppc_fpscr_regnum >= 0
 122            && regno == tdep->ppc_fpscr_regnum)
 123     return FPSCR;
 124   else if (tdep->ppc_mq_regnum >= 0 && regno == tdep->ppc_mq_regnum)
 125     return MQ;
 126   else
 127     return -1;
 128 }
 129
 130 /* Call ptrace(REQ, ID, ADDR, DATA, BUF).  */
 131
 132 static int
 133 rs6000_ptrace32 (int req, int id, int *addr, int data, int *buf)
 134 {
 135   int ret = ptrace (req, id, (int *)addr, data, buf);
 136 #if 0
 137   printf ("rs6000_ptrace32 (%d, %d, 0x%x, %08x, 0x%x) = 0x%x\n",
 138           req, id, (unsigned int)addr, data, (unsigned int)buf, ret);
 139 #endif
 140   return ret;
 141 }
 142
 143 /* Call ptracex(REQ, ID, ADDR, DATA, BUF).  */
 144
 145 static int
 146 rs6000_ptrace64 (int req, int id, long long addr, int data, void *buf)
 147 {
 148 #ifdef ARCH3264
 149   int ret = ptracex (req, id, addr, data, buf);
 150 #else
 151   int ret = 0;
 152 #endif
 153 #if 0
 154   printf ("rs6000_ptrace64 (%d, %d, %s, %08x, 0x%x) = 0x%x\n",
 155           req, id, hex_string (addr), data, (unsigned int)buf, ret);
 156 #endif
 157   return ret;
 158 }
 159
 160 /* Fetch register REGNO from the inferior.  */
 161
 162 static void
 163 fetch_register (struct regcache *regcache, int regno)
 164 {
 165   struct gdbarch *gdbarch = get_regcache_arch (regcache);
 166   int addr[MAX_REGISTER_SIZE];
 167   int nr, isfloat;
 168
 169   /* Retrieved values may be -1, so infer errors from errno.  */
 170   errno = 0;
 171
 172   nr = regmap (gdbarch, regno, &isfloat);
 173
 174   /* Floating-point registers.  */
 175   if (isfloat)
 176     rs6000_ptrace32 (PT_READ_FPR, PIDGET (inferior_ptid), addr, nr, 0);
 177
 178   /* Bogus register number.  */
 179   else if (nr < 0)
 180     {
 181       if (regno >= gdbarch_num_regs (gdbarch))
 182         fprintf_unfiltered (gdb_stderr,
 183                             "gdb error: register no %d not implemented.\n",
 184                             regno);
 185       return;
 186     }
 187
 188   /* Fixed-point registers.  */
 189   else
 190     {
 191       if (!ARCH64 ())
 192         *addr = rs6000_ptrace32 (PT_READ_GPR, PIDGET (inferior_ptid),
 193                                  (int *) nr, 0, 0);
 194       else
 195         {
 196           /* PT_READ_GPR requires the buffer parameter to point to long long,
 197              even if the register is really only 32 bits.  */
 198           long long buf;
 199           rs6000_ptrace64 (PT_READ_GPR, PIDGET (inferior_ptid), nr, 0, &buf);
 200           if (register_size (gdbarch, regno) == 8)
 201             memcpy (addr, &buf, 8);
 202           else
 203             *addr = buf;
 204         }
 205     }
 206
 207   if (!errno)
 208     regcache_raw_supply (regcache, regno, (char *) addr);
 209   else
 210     {
 211 #if 0
 212       /* FIXME: this happens 3 times at the start of each 64-bit program.  */
 213       perror (_("ptrace read"));
 214 #endif
 215       errno = 0;
 216     }
 217 }
 218
 219 /* Store register REGNO back into the inferior.  */
 220
 221 static void
 222 store_register (struct regcache *regcache, int regno)
 223 {
 224   struct gdbarch *gdbarch = get_regcache_arch (regcache);
 225   int addr[MAX_REGISTER_SIZE];
 226   int nr, isfloat;
 227
 228   /* Fetch the register's value from the register cache.  */
 229   regcache_raw_collect (regcache, regno, addr);
 230
 231   /* -1 can be a successful return value, so infer errors from errno.  */
 232   errno = 0;
 233
 234   nr = regmap (gdbarch, regno, &isfloat);
 235
 236   /* Floating-point registers.  */
 237   if (isfloat)
 238     rs6000_ptrace32 (PT_WRITE_FPR, PIDGET (inferior_ptid), addr, nr, 0);
 239
 240   /* Bogus register number.  */
 241   else if (nr < 0)
 242     {
 243       if (regno >= gdbarch_num_regs (gdbarch))
 244         fprintf_unfiltered (gdb_stderr,
 245                             "gdb error: register no %d not implemented.\n",
 246                             regno);
 247     }
 248
 249   /* Fixed-point registers.  */
 250   else
 251     {
 252       if (regno == gdbarch_sp_regnum (gdbarch))
 253         /* Execute one dummy instruction (which is a breakpoint) in inferior
 254            process to give kernel a chance to do internal housekeeping.
 255            Otherwise the following ptrace(2) calls will mess up user stack
 256            since kernel will get confused about the bottom of the stack
 257            (%sp).  */
 258         exec_one_dummy_insn (regcache);
 259
 260       /* The PT_WRITE_GPR operation is rather odd.  For 32-bit inferiors,
 261          the register's value is passed by value, but for 64-bit inferiors,
 262          the address of a buffer containing the value is passed.  */
 263       if (!ARCH64 ())
 264         rs6000_ptrace32 (PT_WRITE_GPR, PIDGET (inferior_ptid),
 265                          (int *) nr, *addr, 0);
 266       else
 267         {
 268           /* PT_WRITE_GPR requires the buffer parameter to point to an 8-byte
 269              area, even if the register is really only 32 bits.  */
 270           long long buf;
 271           if (register_size (gdbarch, regno) == 8)
 272             memcpy (&buf, addr, 8);
 273           else
 274             buf = *addr;
 275           rs6000_ptrace64 (PT_WRITE_GPR, PIDGET (inferior_ptid), nr, 0, &buf);
 276         }
 277     }
 278
 279   if (errno)
 280     {
 281       perror (_("ptrace write"));
 282       errno = 0;
 283     }
 284 }
 285
 286 /* Read from the inferior all registers if REGNO == -1 and just register
 287    REGNO otherwise.  */
 288
 289 static void
 290 rs6000_fetch_inferior_registers (struct target_ops *ops,
 291                                  struct regcache *regcache, int regno)
 292 {
 293   struct gdbarch *gdbarch = get_regcache_arch (regcache);
 294   if (regno != -1)
 295     fetch_register (regcache, regno);
 296
 297   else
 298     {
 299       struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
 300
 301       /* Read 32 general purpose registers.  */
 302       for (regno = tdep->ppc_gp0_regnum;
 303            regno < tdep->ppc_gp0_regnum + ppc_num_gprs;
 304            regno++)
 305         {
 306           fetch_register (regcache, regno);
 307         }
 308
 309       /* Read general purpose floating point registers.  */
 310       if (tdep->ppc_fp0_regnum >= 0)
 311         for (regno = 0; regno < ppc_num_fprs; regno++)
 312           fetch_register (regcache, tdep->ppc_fp0_regnum + regno);
 313
 314       /* Read special registers.  */
 315       fetch_register (regcache, gdbarch_pc_regnum (gdbarch));
 316       fetch_register (regcache, tdep->ppc_ps_regnum);
 317       fetch_register (regcache, tdep->ppc_cr_regnum);
 318       fetch_register (regcache, tdep->ppc_lr_regnum);
 319       fetch_register (regcache, tdep->ppc_ctr_regnum);
 320       fetch_register (regcache, tdep->ppc_xer_regnum);
 321       if (tdep->ppc_fpscr_regnum >= 0)
 322         fetch_register (regcache, tdep->ppc_fpscr_regnum);
 323       if (tdep->ppc_mq_regnum >= 0)
 324         fetch_register (regcache, tdep->ppc_mq_regnum);
 325     }
 326 }
 327
 328 /* Store our register values back into the inferior.
 329    If REGNO is -1, do this for all registers.
 330    Otherwise, REGNO specifies which register (so we can save time).  */
 331
 332 static void
 333 rs6000_store_inferior_registers (struct target_ops *ops,
 334                                  struct regcache *regcache, int regno)
 335 {
 336   struct gdbarch *gdbarch = get_regcache_arch (regcache);
 337   if (regno != -1)
 338     store_register (regcache, regno);
 339
 340   else
 341     {
 342       struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
 343
 344       /* Write general purpose registers first.  */
 345       for (regno = tdep->ppc_gp0_regnum;
 346            regno < tdep->ppc_gp0_regnum + ppc_num_gprs;
 347            regno++)
 348         {
 349           store_register (regcache, regno);
 350         }
 351
 352       /* Write floating point registers.  */
 353       if (tdep->ppc_fp0_regnum >= 0)
 354         for (regno = 0; regno < ppc_num_fprs; regno++)
 355           store_register (regcache, tdep->ppc_fp0_regnum + regno);
 356
 357       /* Write special registers.  */
 358       store_register (regcache, gdbarch_pc_regnum (gdbarch));
 359       store_register (regcache, tdep->ppc_ps_regnum);
 360       store_register (regcache, tdep->ppc_cr_regnum);
 361       store_register (regcache, tdep->ppc_lr_regnum);
 362       store_register (regcache, tdep->ppc_ctr_regnum);
 363       store_register (regcache, tdep->ppc_xer_regnum);
 364       if (tdep->ppc_fpscr_regnum >= 0)
 365         store_register (regcache, tdep->ppc_fpscr_regnum);
 366       if (tdep->ppc_mq_regnum >= 0)
 367         store_register (regcache, tdep->ppc_mq_regnum);
 368     }
 369 }
 370
 371
 372 /* Attempt a transfer all LEN bytes starting at OFFSET between the
 373    inferior's OBJECT:ANNEX space and GDB's READBUF/WRITEBUF buffer.
 374    Return the number of bytes actually transferred.  */
 375
 376 static LONGEST
 377 rs6000_xfer_partial (struct target_ops *ops, enum target_object object,
 378                      const char *annex, gdb_byte *readbuf,
 379                      const gdb_byte *writebuf,
 380                      ULONGEST offset, LONGEST len)
 381 {
 382   pid_t pid = ptid_get_pid (inferior_ptid);
 383   int arch64 = ARCH64 ();
 384
 385   switch (object)
 386     {
 387     case TARGET_OBJECT_LIBRARIES_AIX:
 388       return rs6000_xfer_shared_libraries (ops, object, annex,
 389                                            readbuf, writebuf,
 390                                            offset, len);
 391     case TARGET_OBJECT_MEMORY:
 392       {
 393         union
 394         {
 395           PTRACE_TYPE_RET word;
 396           gdb_byte byte[sizeof (PTRACE_TYPE_RET)];
 397         } buffer;
 398         ULONGEST rounded_offset;
 399         LONGEST partial_len;
 400
 401         /* Round the start offset down to the next long word
 402            boundary.  */
 403         rounded_offset = offset & -(ULONGEST) sizeof (PTRACE_TYPE_RET);
 404
 405         /* Since ptrace will transfer a single word starting at that
 406            rounded_offset the partial_len needs to be adjusted down to
 407            that (remember this function only does a single transfer).
 408            Should the required length be even less, adjust it down
 409            again.  */
 410         partial_len = (rounded_offset + sizeof (PTRACE_TYPE_RET)) - offset;
 411         if (partial_len > len)
 412           partial_len = len;
 413
 414         if (writebuf)
 415           {
 416             /* If OFFSET:PARTIAL_LEN is smaller than
 417                ROUNDED_OFFSET:WORDSIZE then a read/modify write will
 418                be needed.  Read in the entire word.  */
 419             if (rounded_offset < offset
 420                 || (offset + partial_len
 421                     < rounded_offset + sizeof (PTRACE_TYPE_RET)))
 422               {
 423                 /* Need part of initial word -- fetch it.  */
 424                 if (arch64)
 425                   buffer.word = rs6000_ptrace64 (PT_READ_I, pid,
 426                                                  rounded_offset, 0, NULL);
 427                 else
 428                   buffer.word = rs6000_ptrace32 (PT_READ_I, pid,
 429                                                  (int *) (uintptr_t)
 430                                                  rounded_offset,
 431                                                  0, NULL);
 432               }
 433
 434             /* Copy data to be written over corresponding part of
 435                buffer.  */
 436             memcpy (buffer.byte + (offset - rounded_offset),
 437                     writebuf, partial_len);
 438
 439             errno = 0;
 440             if (arch64)
 441               rs6000_ptrace64 (PT_WRITE_D, pid,
 442                                rounded_offset, buffer.word, NULL);
 443             else
 444               rs6000_ptrace32 (PT_WRITE_D, pid,
 445                                (int *) (uintptr_t) rounded_offset,
 446                                buffer.word, NULL);
 447             if (errno)
 448               return 0;
 449           }
 450
 451         if (readbuf)
 452           {
 453             errno = 0;
 454             if (arch64)
 455               buffer.word = rs6000_ptrace64 (PT_READ_I, pid,
 456                                              rounded_offset, 0, NULL);
 457             else
 458               buffer.word = rs6000_ptrace32 (PT_READ_I, pid,
 459                                              (int *)(uintptr_t)rounded_offset,
 460                                              0, NULL);
 461             if (errno)
 462               return 0;
 463
 464             /* Copy appropriate bytes out of the buffer.  */
 465             memcpy (readbuf, buffer.byte + (offset - rounded_offset),
 466                     partial_len);
 467           }
 468
 469         return partial_len;
 470       }
 471
 472     default:
 473       return -1;
 474     }
 475 }
 476
 477 /* Wait for the child specified by PTID to do something.  Return the
 478    process ID of the child, or MINUS_ONE_PTID in case of error; store
 479    the status in *OURSTATUS.  */
 480
 481 static ptid_t
 482 rs6000_wait (struct target_ops *ops,
 483              ptid_t ptid, struct target_waitstatus *ourstatus, int options)
 484 {
 485   pid_t pid;
 486   int status, save_errno;
 487
 488   do
 489     {
 490       set_sigint_trap ();
 491
 492       do
 493         {
 494           pid = waitpid (ptid_get_pid (ptid), &status, 0);
 495           save_errno = errno;
 496         }
 497       while (pid == -1 && errno == EINTR);
 498
 499       clear_sigint_trap ();
 500
 501       if (pid == -1)
 502         {
 503           fprintf_unfiltered (gdb_stderr,
 504                               _("Child process unexpectedly missing: %s.\n"),
 505                               safe_strerror (save_errno));
 506
 507           /* Claim it exited with unknown signal.  */
 508           ourstatus->kind = TARGET_WAITKIND_SIGNALLED;
 509           ourstatus->value.sig = GDB_SIGNAL_UNKNOWN;
 510           return inferior_ptid;
 511         }
 512
 513       /* Ignore terminated detached child processes.  */
 514       if (!WIFSTOPPED (status) && pid != ptid_get_pid (inferior_ptid))
 515         pid = -1;
 516     }
 517   while (pid == -1);
 518
 519   /* AIX has a couple of strange returns from wait().  */
 520
 521   /* stop after load" status.  */
 522   if (status == 0x57c)
 523     ourstatus->kind = TARGET_WAITKIND_LOADED;
 524   /* signal 0.  I have no idea why wait(2) returns with this status word.  */
 525   else if (status == 0x7f)
 526     ourstatus->kind = TARGET_WAITKIND_SPURIOUS;
 527   /* A normal waitstatus.  Let the usual macros deal with it.  */
 528   else
 529     store_waitstatus (ourstatus, status);
 530
 531   return pid_to_ptid (pid);
 532 }
 533
 534 /* Execute one dummy breakpoint instruction.  This way we give the kernel
 535    a chance to do some housekeeping and update inferior's internal data,
 536    including u_area.  */
 537
 538 static void
 539 exec_one_dummy_insn (struct regcache *regcache)
 540 {
 541 #define DUMMY_INSN_ADDR AIX_TEXT_SEGMENT_BASE+0x200
 542
 543   struct gdbarch *gdbarch = get_regcache_arch (regcache);
 544   int ret, status, pid;
 545   CORE_ADDR prev_pc;
 546   void *bp;
 547
 548   /* We plant one dummy breakpoint into DUMMY_INSN_ADDR address.  We
 549      assume that this address will never be executed again by the real
 550      code.  */
 551
 552   bp = deprecated_insert_raw_breakpoint (gdbarch, NULL, DUMMY_INSN_ADDR);
 553
 554   /* You might think this could be done with a single ptrace call, and
 555      you'd be correct for just about every platform I've ever worked
 556      on.  However, rs6000-ibm-aix4.1.3 seems to have screwed this up --
 557      the inferior never hits the breakpoint (it's also worth noting
 558      powerpc-ibm-aix4.1.3 works correctly).  */
 559   prev_pc = regcache_read_pc (regcache);
 560   regcache_write_pc (regcache, DUMMY_INSN_ADDR);
 561   if (ARCH64 ())
 562     ret = rs6000_ptrace64 (PT_CONTINUE, PIDGET (inferior_ptid), 1, 0, NULL);
 563   else
 564     ret = rs6000_ptrace32 (PT_CONTINUE, PIDGET (inferior_ptid),
 565                            (int *) 1, 0, NULL);
 566
 567   if (ret != 0)
 568     perror (_("pt_continue"));
 569
 570   do
 571     {
 572       pid = waitpid (PIDGET (inferior_ptid), &status, 0);
 573     }
 574   while (pid != PIDGET (inferior_ptid));
 575
 576   regcache_write_pc (regcache, prev_pc);
 577   deprecated_remove_raw_breakpoint (gdbarch, bp);
 578 }
 579 \f
 580
 581 /* Set the current architecture from the host running GDB.  Called when
 582    starting a child process.  */
 583
 584 static void (*super_create_inferior) (struct target_ops *,char *exec_file,
 585                                       char *allargs, char **env, int from_tty);
 586 static void
 587 rs6000_create_inferior (struct target_ops * ops, char *exec_file,
 588                         char *allargs, char **env, int from_tty)
 589 {
 590   enum bfd_architecture arch;
 591   unsigned long mach;
 592   bfd abfd;
 593   struct gdbarch_info info;
 594
 595   super_create_inferior (ops, exec_file, allargs, env, from_tty);
 596
 597   if (__power_rs ())
 598     {
 599       arch = bfd_arch_rs6000;
 600       mach = bfd_mach_rs6k;
 601     }
 602   else
 603     {
 604       arch = bfd_arch_powerpc;
 605       mach = bfd_mach_ppc;
 606     }
 607
 608   /* FIXME: schauer/2002-02-25:
 609      We don't know if we are executing a 32 or 64 bit executable,
 610      and have no way to pass the proper word size to rs6000_gdbarch_init.
 611      So we have to avoid switching to a new architecture, if the architecture
 612      matches already.
 613      Blindly calling rs6000_gdbarch_init used to work in older versions of
 614      GDB, as rs6000_gdbarch_init incorrectly used the previous tdep to
 615      determine the wordsize.  */
 616   if (exec_bfd)
 617     {
 618       const struct bfd_arch_info *exec_bfd_arch_info;
 619
 620       exec_bfd_arch_info = bfd_get_arch_info (exec_bfd);
 621       if (arch == exec_bfd_arch_info->arch)
 622         return;
 623     }
 624
 625   bfd_default_set_arch_mach (&abfd, arch, mach);
 626
 627   gdbarch_info_init (&info);
 628   info.bfd_arch_info = bfd_get_arch_info (&abfd);
 629   info.abfd = exec_bfd;
 630
 631   if (!gdbarch_update_p (info))
 632     internal_error (__FILE__, __LINE__,
 633                     _("rs6000_create_inferior: failed "
 634                       "to select architecture"));
 635 }
 636 \f
 637
 638 /* Shared Object support.  */
 639
 640 /* Return the LdInfo data for the given process.  Raises an error
 641    if the data could not be obtained.
 642
 643    The returned value must be deallocated after use.  */
 644
 645 static gdb_byte *
 646 rs6000_ptrace_ldinfo (ptid_t ptid)
 647 {
 648   const int pid = ptid_get_pid (ptid);
 649   int ldi_size = 1024;
 650   gdb_byte *ldi = xmalloc (ldi_size);
 651   int rc = -1;
 652
 653   while (1)
 654     {
 655       if (ARCH64 ())
 656         rc = rs6000_ptrace64 (PT_LDINFO, pid, (unsigned long) ldi, ldi_size,
 657                               NULL);
 658       else
 659         rc = rs6000_ptrace32 (PT_LDINFO, pid, (int *) ldi, ldi_size, NULL);
 660
 661       if (rc != -1)
 662         break; /* Success, we got the entire ld_info data.  */
 663
 664       if (errno != ENOMEM)
 665         perror_with_name (_("ptrace ldinfo"));
 666
 667       /* ldi is not big enough.  Double it and try again.  */
 668       ldi_size *= 2;
 669       ldi = xrealloc (ldi, ldi_size);
 670     }
 671
 672   return ldi;
 673 }
 674
 675 /* Implement the to_xfer_partial target_ops method for
 676    TARGET_OBJECT_LIBRARIES_AIX objects.  */
 677
 678 static LONGEST
 679 rs6000_xfer_shared_libraries
 680   (struct target_ops *ops, enum target_object object,
 681    const char *annex, gdb_byte *readbuf, const gdb_byte *writebuf,
 682    ULONGEST offset, LONGEST len)
 683 {
 684   gdb_byte *ldi_buf;
 685   ULONGEST result;
 686   struct cleanup *cleanup;
 687
 688   /* This function assumes that it is being run with a live process.
 689      Core files are handled via gdbarch.  */
 690   gdb_assert (target_has_execution);
 691
 692   if (writebuf)
 693     return -1;
 694
 695   ldi_buf = rs6000_ptrace_ldinfo (inferior_ptid);
 696   gdb_assert (ldi_buf != NULL);
 697   cleanup = make_cleanup (xfree, ldi_buf);
 698   result = rs6000_aix_ld_info_to_xml (target_gdbarch (), ldi_buf,
 699                                       readbuf, offset, len, 1);
 700   xfree (ldi_buf);
 701
 702   do_cleanups (cleanup);
 703   return result;
 704 }
 705
 706 void _initialize_rs6000_nat (void);
 707
 708 void
 709 _initialize_rs6000_nat (void)
 710 {
 711   struct target_ops *t;
 712
 713   t = inf_ptrace_target ();
 714   t->to_fetch_registers = rs6000_fetch_inferior_registers;
 715   t->to_store_registers = rs6000_store_inferior_registers;
 716   t->to_xfer_partial = rs6000_xfer_partial;
 717
 718   super_create_inferior = t->to_create_inferior;
 719   t->to_create_inferior = rs6000_create_inferior;
 720
 721   t->to_wait = rs6000_wait;
 722
 723   add_target (t);
 724 }