gdb/s390-linux-nat.c

   1 /* S390 native-dependent code for GDB, the GNU debugger.
   2    Copyright (C) 2001-2014 Free Software Foundation, Inc.
   3
   4    Contributed by D.J. Barrow (djbarrow@de.ibm.com,barrow_dj@yahoo.com)
   5    for IBM Deutschland Entwicklung GmbH, IBM Corporation.
   6
   7    This file is part of GDB.
   8
   9    This program is free software; you can redistribute it and/or modify
  10    it under the terms of the GNU General Public License as published by
  11    the Free Software Foundation; either version 3 of the License, or
  12    (at your option) any later version.
  13
  14    This program is distributed in the hope that it will be useful,
  15    but WITHOUT ANY WARRANTY; without even the implied warranty of
  16    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17    GNU General Public License for more details.
  18
  19    You should have received a copy of the GNU General Public License
  20    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  21
  22 #include "defs.h"
  23 #include "regcache.h"
  24 #include "inferior.h"
  25 #include "target.h"
  26 #include "linux-nat.h"
  27 #include "auxv.h"
  28 #include "gregset.h"
  29
  30 #include "s390-linux-tdep.h"
  31 #include "elf/common.h"
  32
  33 #include <asm/ptrace.h>
  34 #include <sys/ptrace.h>
  35 #include <asm/types.h>
  36 #include <sys/procfs.h>
  37 #include <sys/ucontext.h>
  38 #include <elf.h>
  39
  40 #ifndef PTRACE_GETREGSET
  41 #define PTRACE_GETREGSET 0x4204
  42 #endif
  43
  44 #ifndef PTRACE_SETREGSET
  45 #define PTRACE_SETREGSET 0x4205
  46 #endif
  47
  48 static int have_regset_last_break = 0;
  49 static int have_regset_system_call = 0;
  50 static int have_regset_tdb = 0;
  51
  52 /* Map registers to gregset/ptrace offsets.
  53    These arrays are defined in s390-tdep.c.  */
  54
  55 #ifdef __s390x__
  56 #define regmap_gregset s390x_regmap_gregset
  57 #else
  58 #define regmap_gregset s390_regmap_gregset
  59 #endif
  60
  61 #define regmap_fpregset s390_regmap_fpregset
  62
  63 /* Fill the regset described by MAP into REGCACHE, using the values
  64    from REGP.  The MAP array represents each register as a pair
  65    (offset, regno) of short integers and is terminated with -1. */
  66
  67 static void
  68 s390_native_supply (struct regcache *regcache, const short *map,
  69                     const gdb_byte *regp)
  70 {
  71   for (; map[0] >= 0; map += 2)
  72     regcache_raw_supply (regcache, map[1], regp ? regp + map[0] : NULL);
  73 }
  74
  75 /* Collect the register REGNO out of the regset described by MAP from
  76    REGCACHE into REGP.  If REGNO == -1, do this for all registers in
  77    this regset. */
  78
  79 static void
  80 s390_native_collect (const struct regcache *regcache, const short *map,
  81                      int regno, gdb_byte *regp)
  82 {
  83   for (; map[0] >= 0; map += 2)
  84     if (regno == -1 || regno == map[1])
  85       regcache_raw_collect (regcache, map[1], regp + map[0]);
  86 }
  87
  88 /* Fill GDB's register array with the general-purpose register values
  89    in *REGP.
  90
  91    When debugging a 32-bit executable running under a 64-bit kernel,
  92    we have to fix up the 64-bit registers we get from the kernel to
  93    make them look like 32-bit registers.  */
  94
  95 void
  96 supply_gregset (struct regcache *regcache, const gregset_t *regp)
  97 {
  98 #ifdef __s390x__
  99   struct gdbarch *gdbarch = get_regcache_arch (regcache);
 100   if (gdbarch_ptr_bit (gdbarch) == 32)
 101     {
 102       enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
 103       ULONGEST pswm = 0, pswa = 0;
 104       gdb_byte buf[4];
 105       const short *map;
 106
 107       for (map = regmap_gregset; map[0] >= 0; map += 2)
 108         {
 109           const gdb_byte *p = (const gdb_byte *) regp + map[0];
 110           int regno = map[1];
 111
 112           if (regno == S390_PSWM_REGNUM)
 113             pswm = extract_unsigned_integer (p, 8, byte_order);
 114           else if (regno == S390_PSWA_REGNUM)
 115             pswa = extract_unsigned_integer (p, 8, byte_order);
 116           else
 117             {
 118               if ((regno >= S390_R0_REGNUM && regno <= S390_R15_REGNUM)
 119                   || regno == S390_ORIG_R2_REGNUM)
 120                 p += 4;
 121               regcache_raw_supply (regcache, regno, p);
 122             }
 123         }
 124
 125       store_unsigned_integer (buf, 4, byte_order, (pswm >> 32) | 0x80000);
 126       regcache_raw_supply (regcache, S390_PSWM_REGNUM, buf);
 127       store_unsigned_integer (buf, 4, byte_order,
 128                               (pswa & 0x7fffffff) | (pswm & 0x80000000));
 129       regcache_raw_supply (regcache, S390_PSWA_REGNUM, buf);
 130       return;
 131     }
 132 #endif
 133
 134   s390_native_supply (regcache, regmap_gregset, (const gdb_byte *) regp);
 135 }
 136
 137 /* Fill register REGNO (if it is a general-purpose register) in
 138    *REGP with the value in GDB's register array.  If REGNO is -1,
 139    do this for all registers.  */
 140
 141 void
 142 fill_gregset (const struct regcache *regcache, gregset_t *regp, int regno)
 143 {
 144 #ifdef __s390x__
 145   struct gdbarch *gdbarch = get_regcache_arch (regcache);
 146   if (gdbarch_ptr_bit (gdbarch) == 32)
 147     {
 148       gdb_byte *psw_p[2];
 149       const short *map;
 150
 151       for (map = regmap_gregset; map[0] >= 0; map += 2)
 152         {
 153           gdb_byte *p = (gdb_byte *) regp + map[0];
 154           int reg = map[1];
 155
 156           if (reg >= S390_PSWM_REGNUM && reg <= S390_PSWA_REGNUM)
 157             psw_p[reg - S390_PSWM_REGNUM] = p;
 158
 159           else if (regno == -1 || regno == reg)
 160             {
 161               if ((reg >= S390_R0_REGNUM && reg <= S390_R15_REGNUM)
 162                   || reg == S390_ORIG_R2_REGNUM)
 163                 {
 164                   memset (p, 0, 4);
 165                   p += 4;
 166                 }
 167               regcache_raw_collect (regcache, reg, p + 4);
 168             }
 169         }
 170
 171       if (regno == -1
 172           || regno == S390_PSWM_REGNUM || regno == S390_PSWA_REGNUM)
 173         {
 174           enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
 175           ULONGEST pswa, pswm;
 176           gdb_byte buf[4];
 177
 178           regcache_raw_collect (regcache, S390_PSWM_REGNUM, buf);
 179           pswm = extract_unsigned_integer (buf, 4, byte_order);
 180           regcache_raw_collect (regcache, S390_PSWA_REGNUM, buf);
 181           pswa = extract_unsigned_integer (buf, 4, byte_order);
 182
 183           if (regno == -1 || regno == S390_PSWM_REGNUM)
 184             store_unsigned_integer (psw_p[0], 8, byte_order,
 185                                     ((pswm & 0xfff7ffff) << 32) |
 186                                     (pswa & 0x80000000));
 187           if (regno == -1 || regno == S390_PSWA_REGNUM)
 188             store_unsigned_integer (psw_p[1], 8, byte_order,
 189                                     pswa & 0x7fffffff);
 190         }
 191       return;
 192     }
 193 #endif
 194
 195   s390_native_collect (regcache, regmap_gregset, regno, (gdb_byte *) regp);
 196 }
 197
 198 /* Fill GDB's register array with the floating-point register values
 199    in *REGP.  */
 200 void
 201 supply_fpregset (struct regcache *regcache, const fpregset_t *regp)
 202 {
 203   s390_native_supply (regcache, regmap_fpregset, (const gdb_byte *) regp);
 204 }
 205
 206 /* Fill register REGNO (if it is a general-purpose register) in
 207    *REGP with the value in GDB's register array.  If REGNO is -1,
 208    do this for all registers.  */
 209 void
 210 fill_fpregset (const struct regcache *regcache, fpregset_t *regp, int regno)
 211 {
 212   s390_native_collect (regcache, regmap_fpregset, regno, (gdb_byte *) regp);
 213 }
 214
 215 /* Find the TID for the current inferior thread to use with ptrace.  */
 216 static int
 217 s390_inferior_tid (void)
 218 {
 219   /* GNU/Linux LWP ID's are process ID's.  */
 220   int tid = ptid_get_lwp (inferior_ptid);
 221   if (tid == 0)
 222     tid = ptid_get_pid (inferior_ptid); /* Not a threaded program.  */
 223
 224   return tid;
 225 }
 226
 227 /* Fetch all general-purpose registers from process/thread TID and
 228    store their values in GDB's register cache.  */
 229 static void
 230 fetch_regs (struct regcache *regcache, int tid)
 231 {
 232   gregset_t regs;
 233   ptrace_area parea;
 234
 235   parea.len = sizeof (regs);
 236   parea.process_addr = (addr_t) &regs;
 237   parea.kernel_addr = offsetof (struct user_regs_struct, psw);
 238   if (ptrace (PTRACE_PEEKUSR_AREA, tid, (long) &parea) < 0)
 239     perror_with_name (_("Couldn't get registers"));
 240
 241   supply_gregset (regcache, (const gregset_t *) &regs);
 242 }
 243
 244 /* Store all valid general-purpose registers in GDB's register cache
 245    into the process/thread specified by TID.  */
 246 static void
 247 store_regs (const struct regcache *regcache, int tid, int regnum)
 248 {
 249   gregset_t regs;
 250   ptrace_area parea;
 251
 252   parea.len = sizeof (regs);
 253   parea.process_addr = (addr_t) &regs;
 254   parea.kernel_addr = offsetof (struct user_regs_struct, psw);
 255   if (ptrace (PTRACE_PEEKUSR_AREA, tid, (long) &parea) < 0)
 256     perror_with_name (_("Couldn't get registers"));
 257
 258   fill_gregset (regcache, &regs, regnum);
 259
 260   if (ptrace (PTRACE_POKEUSR_AREA, tid, (long) &parea) < 0)
 261     perror_with_name (_("Couldn't write registers"));
 262 }
 263
 264 /* Fetch all floating-point registers from process/thread TID and store
 265    their values in GDB's register cache.  */
 266 static void
 267 fetch_fpregs (struct regcache *regcache, int tid)
 268 {
 269   fpregset_t fpregs;
 270   ptrace_area parea;
 271
 272   parea.len = sizeof (fpregs);
 273   parea.process_addr = (addr_t) &fpregs;
 274   parea.kernel_addr = offsetof (struct user_regs_struct, fp_regs);
 275   if (ptrace (PTRACE_PEEKUSR_AREA, tid, (long) &parea) < 0)
 276     perror_with_name (_("Couldn't get floating point status"));
 277
 278   supply_fpregset (regcache, (const fpregset_t *) &fpregs);
 279 }
 280
 281 /* Store all valid floating-point registers in GDB's register cache
 282    into the process/thread specified by TID.  */
 283 static void
 284 store_fpregs (const struct regcache *regcache, int tid, int regnum)
 285 {
 286   fpregset_t fpregs;
 287   ptrace_area parea;
 288
 289   parea.len = sizeof (fpregs);
 290   parea.process_addr = (addr_t) &fpregs;
 291   parea.kernel_addr = offsetof (struct user_regs_struct, fp_regs);
 292   if (ptrace (PTRACE_PEEKUSR_AREA, tid, (long) &parea) < 0)
 293     perror_with_name (_("Couldn't get floating point status"));
 294
 295   fill_fpregset (regcache, &fpregs, regnum);
 296
 297   if (ptrace (PTRACE_POKEUSR_AREA, tid, (long) &parea) < 0)
 298     perror_with_name (_("Couldn't write floating point status"));
 299 }
 300
 301 /* Fetch all registers in the kernel's register set whose number is REGSET,
 302    whose size is REGSIZE, and whose layout is described by REGMAP, from
 303    process/thread TID and store their values in GDB's register cache.  */
 304 static void
 305 fetch_regset (struct regcache *regcache, int tid,
 306               int regset, int regsize, const short *regmap)
 307 {
 308   gdb_byte *buf = alloca (regsize);
 309   struct iovec iov;
 310
 311   iov.iov_base = buf;
 312   iov.iov_len = regsize;
 313
 314   if (ptrace (PTRACE_GETREGSET, tid, (long) regset, (long) &iov) < 0)
 315     {
 316       if (errno == ENODATA)
 317         s390_native_supply (regcache, regmap, NULL);
 318       else
 319         perror_with_name (_("Couldn't get register set"));
 320     }
 321   else
 322     s390_native_supply (regcache, regmap, buf);
 323 }
 324
 325 /* Store all registers in the kernel's register set whose number is REGSET,
 326    whose size is REGSIZE, and whose layout is described by REGMAP, from
 327    GDB's register cache back to process/thread TID.  */
 328 static void
 329 store_regset (struct regcache *regcache, int tid,
 330               int regset, int regsize, const short *regmap)
 331 {
 332   gdb_byte *buf = alloca (regsize);
 333   struct iovec iov;
 334
 335   iov.iov_base = buf;
 336   iov.iov_len = regsize;
 337
 338   if (ptrace (PTRACE_GETREGSET, tid, (long) regset, (long) &iov) < 0)
 339     perror_with_name (_("Couldn't get register set"));
 340
 341   s390_native_collect (regcache, regmap, -1, buf);
 342
 343   if (ptrace (PTRACE_SETREGSET, tid, (long) regset, (long) &iov) < 0)
 344     perror_with_name (_("Couldn't set register set"));
 345 }
 346
 347 /* Check whether the kernel provides a register set with number REGSET
 348    of size REGSIZE for process/thread TID.  */
 349 static int
 350 check_regset (int tid, int regset, int regsize)
 351 {
 352   gdb_byte *buf = alloca (regsize);
 353   struct iovec iov;
 354
 355   iov.iov_base = buf;
 356   iov.iov_len = regsize;
 357
 358   if (ptrace (PTRACE_GETREGSET, tid, (long) regset, (long) &iov) >= 0
 359       || errno == ENODATA)
 360     return 1;
 361   return 0;
 362 }
 363
 364 /* Fetch register REGNUM from the child process.  If REGNUM is -1, do
 365    this for all registers.  */
 366 static void
 367 s390_linux_fetch_inferior_registers (struct target_ops *ops,
 368                                      struct regcache *regcache, int regnum)
 369 {
 370   int tid = s390_inferior_tid ();
 371
 372   if (regnum == -1 || S390_IS_GREGSET_REGNUM (regnum))
 373     fetch_regs (regcache, tid);
 374
 375   if (regnum == -1 || S390_IS_FPREGSET_REGNUM (regnum))
 376     fetch_fpregs (regcache, tid);
 377
 378   if (have_regset_last_break)
 379     if (regnum == -1 || regnum == S390_LAST_BREAK_REGNUM)
 380       fetch_regset (regcache, tid, NT_S390_LAST_BREAK, 8,
 381                     (gdbarch_ptr_bit (get_regcache_arch (regcache)) == 32
 382                      ? s390_regmap_last_break : s390x_regmap_last_break));
 383
 384   if (have_regset_system_call)
 385     if (regnum == -1 || regnum == S390_SYSTEM_CALL_REGNUM)
 386       fetch_regset (regcache, tid, NT_S390_SYSTEM_CALL, 4,
 387                     s390_regmap_system_call);
 388
 389   if (have_regset_tdb)
 390     if (regnum == -1 || S390_IS_TDBREGSET_REGNUM (regnum))
 391       fetch_regset (regcache, tid, NT_S390_TDB, s390_sizeof_tdbregset,
 392                     s390_regmap_tdb);
 393 }
 394
 395 /* Store register REGNUM back into the child process.  If REGNUM is
 396    -1, do this for all registers.  */
 397 static void
 398 s390_linux_store_inferior_registers (struct target_ops *ops,
 399                                      struct regcache *regcache, int regnum)
 400 {
 401   int tid = s390_inferior_tid ();
 402
 403   if (regnum == -1 || S390_IS_GREGSET_REGNUM (regnum))
 404     store_regs (regcache, tid, regnum);
 405
 406   if (regnum == -1 || S390_IS_FPREGSET_REGNUM (regnum))
 407     store_fpregs (regcache, tid, regnum);
 408
 409   /* S390_LAST_BREAK_REGNUM is read-only.  */
 410
 411   if (have_regset_system_call)
 412     if (regnum == -1 || regnum == S390_SYSTEM_CALL_REGNUM)
 413       store_regset (regcache, tid, NT_S390_SYSTEM_CALL, 4,
 414                     s390_regmap_system_call);
 415 }
 416
 417
 418 /* Hardware-assisted watchpoint handling.  */
 419
 420 /* We maintain a list of all currently active watchpoints in order
 421    to properly handle watchpoint removal.
 422
 423    The only thing we actually need is the total address space area
 424    spanned by the watchpoints.  */
 425
 426 struct watch_area
 427 {
 428   struct watch_area *next;
 429   CORE_ADDR lo_addr;
 430   CORE_ADDR hi_addr;
 431 };
 432
 433 static struct watch_area *watch_base = NULL;
 434
 435 static int
 436 s390_stopped_by_watchpoint (struct target_ops *ops)
 437 {
 438   per_lowcore_bits per_lowcore;
 439   ptrace_area parea;
 440   int result;
 441
 442   /* Speed up common case.  */
 443   if (!watch_base)
 444     return 0;
 445
 446   parea.len = sizeof (per_lowcore);
 447   parea.process_addr = (addr_t) & per_lowcore;
 448   parea.kernel_addr = offsetof (struct user_regs_struct, per_info.lowcore);
 449   if (ptrace (PTRACE_PEEKUSR_AREA, s390_inferior_tid (), &parea) < 0)
 450     perror_with_name (_("Couldn't retrieve watchpoint status"));
 451
 452   result = (per_lowcore.perc_storage_alteration == 1
 453             && per_lowcore.perc_store_real_address == 0);
 454
 455   if (result)
 456     {
 457       /* Do not report this watchpoint again.  */
 458       memset (&per_lowcore, 0, sizeof (per_lowcore));
 459       if (ptrace (PTRACE_POKEUSR_AREA, s390_inferior_tid (), &parea) < 0)
 460         perror_with_name (_("Couldn't clear watchpoint status"));
 461     }
 462
 463   return result;
 464 }
 465
 466 static void
 467 s390_fix_watch_points (struct lwp_info *lp)
 468 {
 469   int tid;
 470
 471   per_struct per_info;
 472   ptrace_area parea;
 473
 474   CORE_ADDR watch_lo_addr = (CORE_ADDR)-1, watch_hi_addr = 0;
 475   struct watch_area *area;
 476
 477   tid = ptid_get_lwp (lp->ptid);
 478   if (tid == 0)
 479     tid = ptid_get_pid (lp->ptid);
 480
 481   for (area = watch_base; area; area = area->next)
 482     {
 483       watch_lo_addr = min (watch_lo_addr, area->lo_addr);
 484       watch_hi_addr = max (watch_hi_addr, area->hi_addr);
 485     }
 486
 487   parea.len = sizeof (per_info);
 488   parea.process_addr = (addr_t) & per_info;
 489   parea.kernel_addr = offsetof (struct user_regs_struct, per_info);
 490   if (ptrace (PTRACE_PEEKUSR_AREA, tid, &parea) < 0)
 491     perror_with_name (_("Couldn't retrieve watchpoint status"));
 492
 493   if (watch_base)
 494     {
 495       per_info.control_regs.bits.em_storage_alteration = 1;
 496       per_info.control_regs.bits.storage_alt_space_ctl = 1;
 497     }
 498   else
 499     {
 500       per_info.control_regs.bits.em_storage_alteration = 0;
 501       per_info.control_regs.bits.storage_alt_space_ctl = 0;
 502     }
 503   per_info.starting_addr = watch_lo_addr;
 504   per_info.ending_addr = watch_hi_addr;
 505
 506   if (ptrace (PTRACE_POKEUSR_AREA, tid, &parea) < 0)
 507     perror_with_name (_("Couldn't modify watchpoint status"));
 508 }
 509
 510 static int
 511 s390_insert_watchpoint (CORE_ADDR addr, int len, int type,
 512                         struct expression *cond)
 513 {
 514   struct lwp_info *lp;
 515   struct watch_area *area = xmalloc (sizeof (struct watch_area));
 516
 517   if (!area)
 518     return -1;
 519
 520   area->lo_addr = addr;
 521   area->hi_addr = addr + len - 1;
 522
 523   area->next = watch_base;
 524   watch_base = area;
 525
 526   ALL_LWPS (lp)
 527     s390_fix_watch_points (lp);
 528   return 0;
 529 }
 530
 531 static int
 532 s390_remove_watchpoint (struct target_ops *self,
 533                         CORE_ADDR addr, int len, int type,
 534                         struct expression *cond)
 535 {
 536   struct lwp_info *lp;
 537   struct watch_area *area, **parea;
 538
 539   for (parea = &watch_base; *parea; parea = &(*parea)->next)
 540     if ((*parea)->lo_addr == addr
 541         && (*parea)->hi_addr == addr + len - 1)
 542       break;
 543
 544   if (!*parea)
 545     {
 546       fprintf_unfiltered (gdb_stderr,
 547                           "Attempt to remove nonexistent watchpoint.\n");
 548       return -1;
 549     }
 550
 551   area = *parea;
 552   *parea = area->next;
 553   xfree (area);
 554
 555   ALL_LWPS (lp)
 556     s390_fix_watch_points (lp);
 557   return 0;
 558 }
 559
 560 static int
 561 s390_can_use_hw_breakpoint (struct target_ops *self,
 562                             int type, int cnt, int othertype)
 563 {
 564   return type == bp_hardware_watchpoint;
 565 }
 566
 567 static int
 568 s390_region_ok_for_hw_watchpoint (CORE_ADDR addr, int cnt)
 569 {
 570   return 1;
 571 }
 572
 573 static int
 574 s390_target_wordsize (void)
 575 {
 576   int wordsize = 4;
 577
 578   /* Check for 64-bit inferior process.  This is the case when the host is
 579      64-bit, and in addition bit 32 of the PSW mask is set.  */
 580 #ifdef __s390x__
 581   long pswm;
 582
 583   errno = 0;
 584   pswm = (long) ptrace (PTRACE_PEEKUSER, s390_inferior_tid (), PT_PSWMASK, 0);
 585   if (errno == 0 && (pswm & 0x100000000ul) != 0)
 586     wordsize = 8;
 587 #endif
 588
 589   return wordsize;
 590 }
 591
 592 static int
 593 s390_auxv_parse (struct target_ops *ops, gdb_byte **readptr,
 594                  gdb_byte *endptr, CORE_ADDR *typep, CORE_ADDR *valp)
 595 {
 596   int sizeof_auxv_field = s390_target_wordsize ();
 597   enum bfd_endian byte_order = gdbarch_byte_order (target_gdbarch ());
 598   gdb_byte *ptr = *readptr;
 599
 600   if (endptr == ptr)
 601     return 0;
 602
 603   if (endptr - ptr < sizeof_auxv_field * 2)
 604     return -1;
 605
 606   *typep = extract_unsigned_integer (ptr, sizeof_auxv_field, byte_order);
 607   ptr += sizeof_auxv_field;
 608   *valp = extract_unsigned_integer (ptr, sizeof_auxv_field, byte_order);
 609   ptr += sizeof_auxv_field;
 610
 611   *readptr = ptr;
 612   return 1;
 613 }
 614
 615 #ifdef __s390x__
 616 static unsigned long
 617 s390_get_hwcap (void)
 618 {
 619   CORE_ADDR field;
 620
 621   if (target_auxv_search (&current_target, AT_HWCAP, &field))
 622     return (unsigned long) field;
 623
 624   return 0;
 625 }
 626 #endif
 627
 628 static const struct target_desc *
 629 s390_read_description (struct target_ops *ops)
 630 {
 631   int tid = s390_inferior_tid ();
 632
 633   have_regset_last_break
 634     = check_regset (tid, NT_S390_LAST_BREAK, 8);
 635   have_regset_system_call
 636     = check_regset (tid, NT_S390_SYSTEM_CALL, 4);
 637
 638 #ifdef __s390x__
 639   /* If GDB itself is compiled as 64-bit, we are running on a machine in
 640      z/Architecture mode.  If the target is running in 64-bit addressing
 641      mode, report s390x architecture.  If the target is running in 31-bit
 642      addressing mode, but the kernel supports using 64-bit registers in
 643      that mode, report s390 architecture with 64-bit GPRs.  */
 644
 645   have_regset_tdb = (s390_get_hwcap () & HWCAP_S390_TE) ?
 646     check_regset (tid, NT_S390_TDB, s390_sizeof_tdbregset) : 0;
 647
 648   if (s390_target_wordsize () == 8)
 649     return (have_regset_tdb ? tdesc_s390x_te_linux64 :
 650             have_regset_system_call? tdesc_s390x_linux64v2 :
 651             have_regset_last_break? tdesc_s390x_linux64v1 :
 652             tdesc_s390x_linux64);
 653
 654   if (s390_get_hwcap () & HWCAP_S390_HIGH_GPRS)
 655     return (have_regset_tdb ? tdesc_s390_te_linux64 :
 656             have_regset_system_call? tdesc_s390_linux64v2 :
 657             have_regset_last_break? tdesc_s390_linux64v1 :
 658             tdesc_s390_linux64);
 659 #endif
 660
 661   /* If GDB itself is compiled as 31-bit, or if we're running a 31-bit inferior
 662      on a 64-bit kernel that does not support using 64-bit registers in 31-bit
 663      mode, report s390 architecture with 32-bit GPRs.  */
 664   return (have_regset_system_call? tdesc_s390_linux32v2 :
 665           have_regset_last_break? tdesc_s390_linux32v1 :
 666           tdesc_s390_linux32);
 667 }
 668
 669 void _initialize_s390_nat (void);
 670
 671 void
 672 _initialize_s390_nat (void)
 673 {
 674   struct target_ops *t;
 675
 676   /* Fill in the generic GNU/Linux methods.  */
 677   t = linux_target ();
 678
 679   /* Add our register access methods.  */
 680   t->to_fetch_registers = s390_linux_fetch_inferior_registers;
 681   t->to_store_registers = s390_linux_store_inferior_registers;
 682
 683   /* Add our watchpoint methods.  */
 684   t->to_can_use_hw_breakpoint = s390_can_use_hw_breakpoint;
 685   t->to_region_ok_for_hw_watchpoint = s390_region_ok_for_hw_watchpoint;
 686   t->to_have_continuable_watchpoint = 1;
 687   t->to_stopped_by_watchpoint = s390_stopped_by_watchpoint;
 688   t->to_insert_watchpoint = s390_insert_watchpoint;
 689   t->to_remove_watchpoint = s390_remove_watchpoint;
 690
 691   /* Detect target architecture.  */
 692   t->to_read_description = s390_read_description;
 693   t->to_auxv_parse = s390_auxv_parse;
 694
 695   /* Register the target.  */
 696   linux_nat_add_target (t);
 697   linux_nat_set_new_thread (t, s390_fix_watch_points);
 698 }