gdb/i386-linux-nat.c

   1 /* Native-dependent code for Linux running on i386's, for GDB.
   2
   3 This file is part of GDB.
   4
   5 This program is free software; you can redistribute it and/or modify
   6 it under the terms of the GNU General Public License as published by
   7 the Free Software Foundation; either version 2 of the License, or
   8 (at your option) any later version.
   9
  10 This program is distributed in the hope that it will be useful,
  11 but WITHOUT ANY WARRANTY; without even the implied warranty of
  12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13 GNU General Public License for more details.
  14
  15 You should have received a copy of the GNU General Public License
  16 along with this program; if not, write to the Free Software
  17 Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
  18
  19 #include "defs.h"
  20 #include "inferior.h"
  21 #include "gdbcore.h"
  22
  23 /* For i386_linux_skip_solib_resolver */
  24 #include "symtab.h"
  25 #include "frame.h"
  26 #include "symfile.h"
  27 #include "objfiles.h"
  28
  29 #include <sys/ptrace.h>
  30 #include <sys/user.h>
  31 #include <sys/procfs.h>
  32
  33 #ifdef HAVE_SYS_REG_H
  34 #include <sys/reg.h>
  35 #endif
  36
  37 /*
  38  * Some systems (Linux) may have threads implemented as pseudo-processes,
  39  * in which case we may be tracing more than one process at a time.
  40  * In that case, inferior_pid will contain the main process ID and the
  41  * individual thread (process) id mashed together.  These macros are
  42  * used to separate them out.  The definitions may be overridden in tm.h
  43  */
  44
  45 #if !defined (PIDGET)   /* Default definition for PIDGET/TIDGET.  */
  46 #define PIDGET(PID)     PID
  47 #define TIDGET(PID)     0
  48 #endif
  49
  50 /* This is a duplicate of the table in i386-xdep.c. */
  51
  52 static int regmap[] =
  53 {
  54   EAX, ECX, EDX, EBX,
  55   UESP, EBP, ESI, EDI,
  56   EIP, EFL, CS, SS,
  57   DS, ES, FS, GS,
  58 };
  59
  60
  61 /* Which ptrace request retrieves which registers?
  62    These apply to the corresponding SET requests as well.  */
  63 #define GETREGS_SUPPLIES(regno) \
  64   (0 <= (regno) && (regno) <= 15)
  65 #define GETFPREGS_SUPPLIES(regno) \
  66   (FP0_REGNUM <= (regno) && (regno) <= LAST_FPU_CTRL_REGNUM)
  67 #define GETXFPREGS_SUPPLIES(regno) \
  68   (FP0_REGNUM <= (regno) && (regno) <= MXCSR_REGNUM)
  69
  70 /* Does the current host support the GETXFPREGS request?  The header
  71    file may or may not define it, and even if it is defined, the
  72    kernel will return EIO if it's running on a pre-SSE processor.
  73
  74    PTRACE_GETXFPREGS is a Cygnus invention, since we wrote our own
  75    Linux kernel patch for SSE support.  That patch may or may not
  76    actually make it into the official distribution.  If you find that
  77    years have gone by since this stuff was added, and Linux isn't
  78    using PTRACE_GETXFPREGS, that means that our patch didn't make it,
  79    and you can delete this, and the related code.
  80
  81    My instinct is to attach this to some architecture- or
  82    target-specific data structure, but really, a particular GDB
  83    process can only run on top of one kernel at a time.  So it's okay
  84    for this to be a simple variable.  */
  85 int have_ptrace_getxfpregs =
  86 #ifdef HAVE_PTRACE_GETXFPREGS
  87   1
  88 #else
  89   0
  90 #endif
  91 ;
  92
  93
  94 \f
  95 /* Transfering the general registers between GDB, inferiors and core files.  */
  96
  97 /* Given a pointer to a general register set in struct user format
  98    (gregset_t *), unpack the register contents and supply them as
  99    gdb's idea of the current register values. */
 100 void
 101 supply_gregset (gregsetp)
 102      gregset_t *gregsetp;
 103 {
 104   register int regi;
 105   register greg_t *regp = (greg_t *) gregsetp;
 106
 107   for (regi = 0; regi < NUM_GREGS; regi++)
 108     {
 109       supply_register (regi, (char *) (regp + regmap[regi]));
 110     }
 111 }
 112
 113
 114 /* Fill in a gregset_t object with selected data from a gdb-format
 115    register file.
 116    - GREGSETP points to the gregset_t object to be filled.
 117    - GDB_REGS points to the GDB-style register file providing the data.
 118    - VALID is an array indicating which registers in GDB_REGS are
 119      valid; the parts of *GREGSETP that would hold registers marked
 120      invalid in GDB_REGS are left unchanged.  If VALID is zero, all
 121      registers are assumed to be valid.  */
 122 void
 123 convert_to_gregset (gregset_t *gregsetp,
 124                     char *gdb_regs,
 125                     signed char *valid)
 126 {
 127   int regi;
 128   register greg_t *regp = (greg_t *) gregsetp;
 129
 130   for (regi = 0; regi < NUM_GREGS; regi++)
 131     if (! valid || valid[regi])
 132       *(regp + regmap[regi]) = * (int *) &registers[REGISTER_BYTE (regi)];
 133 }
 134
 135
 136 /* Store GDB's value for REGNO in *GREGSETP.  If REGNO is -1, do all
 137    of them.  */
 138 void
 139 fill_gregset (gregset_t *gregsetp,
 140               int regno)
 141 {
 142   if (regno == -1)
 143     convert_to_gregset (gregsetp, registers, 0);
 144   else if (regno >= 0 && regno < NUM_GREGS)
 145     {
 146       signed char valid[NUM_GREGS];
 147       memset (valid, 0, sizeof (valid));
 148       valid[regno] = 1;
 149       convert_to_gregset (gregsetp, registers, valid);
 150     }
 151 }
 152
 153
 154 /* Read the general registers from the process, and store them
 155    in registers[].  */
 156 static void
 157 fetch_regs (int tid)
 158 {
 159   int ret, regno;
 160   gregset_t buf;
 161
 162   ret = ptrace (PTRACE_GETREGS, tid, 0, (int) &buf);
 163   if (ret < 0)
 164     {
 165       warning ("Couldn't get registers");
 166       return;
 167     }
 168
 169   supply_gregset (&buf);
 170 }
 171
 172
 173 /* Set the inferior's general registers to the values in registers[]
 174    --- but only those registers marked as valid.  */
 175 static void
 176 store_regs (int tid)
 177 {
 178   int ret, regno;
 179   gregset_t buf;
 180
 181   ret = ptrace (PTRACE_GETREGS, tid, 0, (int) &buf);
 182   if (ret < 0)
 183     {
 184       warning ("Couldn't get registers");
 185       return;
 186     }
 187
 188   convert_to_gregset (&buf, registers, register_valid);
 189
 190   ret = ptrace (PTRACE_SETREGS, tid, 0, (int)buf);
 191   if (ret < 0)
 192     {
 193       warning ("Couldn't write registers");
 194       return;
 195     }
 196 }
 197
 198
 199 \f
 200 /* Transfering floating-point registers between GDB, inferiors and cores.  */
 201
 202 /* What is the address of st(N) within the fpregset_t structure F?  */
 203 #define FPREGSET_T_FPREG_ADDR(f, n) \
 204   ((char *) &(f)->st_space + (n) * 10)
 205
 206 /* Fill GDB's register file with the floating-point register values in
 207    *FPREGSETP.  */
 208 void
 209 supply_fpregset (fpregset_t *fpregsetp)
 210 {
 211   int i;
 212
 213   /* Supply the floating-point registers.  */
 214   for (i = 0; i < 8; i++)
 215     supply_register (FP0_REGNUM + i, FPREGSET_T_FPREG_ADDR (fpregsetp, i));
 216
 217   supply_register (FCTRL_REGNUM, (char *) &fpregsetp->cwd);
 218   supply_register (FSTAT_REGNUM, (char *) &fpregsetp->swd);
 219   supply_register (FTAG_REGNUM,  (char *) &fpregsetp->twd);
 220   supply_register (FCOFF_REGNUM, (char *) &fpregsetp->fip);
 221   supply_register (FDS_REGNUM,   (char *) &fpregsetp->fos);
 222   supply_register (FDOFF_REGNUM, (char *) &fpregsetp->foo);
 223
 224   /* Extract the code segment and opcode from the  "fcs" member.  */
 225   {
 226     long l;
 227
 228     l = fpregsetp->fcs & 0xffff;
 229     supply_register (FCS_REGNUM, (char *) &l);
 230
 231     l = (fpregsetp->fcs >> 16) & ((1 << 11) - 1);
 232     supply_register (FOP_REGNUM, (char *) &l);
 233   }
 234 }
 235
 236
 237 /* Fill in an fpregset_t structure with selected data from a
 238    gdb-format register file.
 239    - FPREGSETP points to the structure to be filled.
 240    - GDB_REGS points to the GDB-style register file providing the data.
 241    - VALID is an array indicating which registers in GDB_REGS are
 242      valid; the parts of *FPREGSETP that would hold registers marked
 243      invalid in GDB_REGS are left unchanged.  If VALID is zero, all
 244      registers are assumed to be valid.  */
 245 void
 246 convert_to_fpregset (fpregset_t *fpregsetp,
 247                      char *gdb_regs,
 248                      signed char *valid)
 249 {
 250   int i;
 251
 252   /* Fill in the floating-point registers.  */
 253   for (i = 0; i < 8; i++)
 254     if (!valid || valid[i])
 255       memcpy (FPREGSET_T_FPREG_ADDR (fpregsetp, i),
 256               &registers[REGISTER_BYTE (FP0_REGNUM + i)],
 257               REGISTER_RAW_SIZE(FP0_REGNUM + i));
 258
 259 #define fill(MEMBER, REGNO)                                             \
 260   if (! valid || valid[(REGNO)])                                        \
 261     memcpy (&fpregsetp->MEMBER, &registers[REGISTER_BYTE (REGNO)],      \
 262             sizeof (fpregsetp->MEMBER))
 263
 264   fill (cwd, FCTRL_REGNUM);
 265   fill (swd, FSTAT_REGNUM);
 266   fill (twd, FTAG_REGNUM);
 267   fill (fip, FCOFF_REGNUM);
 268   fill (foo, FDOFF_REGNUM);
 269   fill (fos, FDS_REGNUM);
 270
 271 #undef fill
 272
 273   if (! valid || valid[FCS_REGNUM])
 274     fpregsetp->fcs
 275       = ((fpregsetp->fcs & ~0xffff)
 276          | (* (int *) &registers[REGISTER_BYTE (FCS_REGNUM)] & 0xffff));
 277
 278   if (! valid || valid[FOP_REGNUM])
 279     fpregsetp->fcs
 280       = ((fpregsetp->fcs & 0xffff)
 281          | ((*(int *) &registers[REGISTER_BYTE (FOP_REGNUM)] & ((1 << 11) - 1))
 282             << 16));
 283 }
 284
 285
 286 /* Given a pointer to a floating point register set in (fpregset_t *)
 287    format, update all of the registers from gdb's idea of the current
 288    floating point register set.  */
 289
 290 void
 291 fill_fpregset (fpregset_t *fpregsetp,
 292                int regno)
 293 {
 294   convert_to_fpregset (fpregsetp, registers, 0);
 295 }
 296
 297
 298 /* Get the whole floating point state of the process and store the
 299    floating point stack into registers[].  */
 300 static void
 301 fetch_fpregs (int tid)
 302 {
 303   int ret, regno;
 304   fpregset_t buf;
 305
 306   ret = ptrace (PTRACE_GETFPREGS, tid, 0, (int) &buf);
 307   if (ret < 0)
 308     {
 309       warning ("Couldn't get floating point status");
 310       return;
 311     }
 312
 313   /* ptrace fills an fpregset_t, so we can use the same function we do
 314      for core files.  */
 315   supply_fpregset (&buf);
 316 }
 317
 318
 319 /* Set the inferior's floating-point registers to the values in
 320    registers[] --- but only those registers marked valid.  */
 321 static void
 322 store_fpregs (int tid)
 323 {
 324   int ret;
 325   fpregset_t buf;
 326
 327   ret = ptrace (PTRACE_GETFPREGS, tid, 0, (int) &buf);
 328   if (ret < 0)
 329     {
 330       warning ("Couldn't get floating point status");
 331       return;
 332     }
 333
 334   convert_to_fpregset (&buf, registers, register_valid);
 335
 336   ret = ptrace (PTRACE_SETFPREGS, tid, 0, (int) &buf);
 337   if (ret < 0)
 338     {
 339       warning ("Couldn't write floating point status");
 340       return;
 341     }
 342 }
 343
 344 \f
 345 /* Transfering floating-point and SSE registers to and from GDB.  */
 346
 347
 348 /* PTRACE_GETXFPREGS is a Cygnus invention, since we wrote our own
 349    Linux kernel patch for SSE support.  That patch may or may not
 350    actually make it into the official distribution.  If you find that
 351    years have gone by since this code was added, and Linux isn't using
 352    PTRACE_GETXFPREGS, that means that our patch didn't make it, and
 353    you can delete this code.  */
 354
 355 #ifdef HAVE_PTRACE_GETXFPREGS
 356 static void
 357 supply_xfpregset (struct user_xfpregs_struct *xfpregs)
 358 {
 359   int reg;
 360
 361   /* Supply the floating-point registers.  */
 362   for (reg = 0; reg < 8; reg++)
 363     supply_register (FP0_REGNUM + reg, (char *) &xfpregs->st_space[reg]);
 364
 365   {
 366     supply_register (FCTRL_REGNUM, (char *) &xfpregs->cwd);
 367     supply_register (FSTAT_REGNUM, (char *) &xfpregs->swd);
 368     supply_register (FTAG_REGNUM,  (char *) &xfpregs->twd);
 369     supply_register (FCOFF_REGNUM, (char *) &xfpregs->fip);
 370     supply_register (FDS_REGNUM,   (char *) &xfpregs->fos);
 371     supply_register (FDOFF_REGNUM, (char *) &xfpregs->foo);
 372
 373     /* Extract the code segment and opcode from the  "fcs" member.  */
 374     {
 375       long l;
 376
 377       l = xfpregs->fcs & 0xffff;
 378       supply_register (FCS_REGNUM, (char *) &l);
 379
 380       l = (xfpregs->fcs >> 16) & ((1 << 11) - 1);
 381       supply_register (FOP_REGNUM, (char *) &l);
 382     }
 383   }
 384
 385   /* Supply the SSE registers.  */
 386   for (reg = 0; reg < 8; reg++)
 387     supply_register (XMM0_REGNUM + reg, (char *) &xfpregs->xmm_space[reg]);
 388   supply_register (MXCSR_REGNUM, (char *) &xfpregs->mxcsr);
 389 }
 390
 391
 392 static void
 393 convert_to_xfpregset (struct user_xfpregs_struct *xfpregs,
 394                       char *gdb_regs,
 395                       signed char *valid)
 396 {
 397   int reg;
 398
 399   /* Fill in the floating-point registers.  */
 400   for (reg = 0; reg < 8; reg++)
 401     if (!valid || valid[reg])
 402       memcpy (&xfpregs->st_space[reg],
 403               &registers[REGISTER_BYTE (FP0_REGNUM + reg)],
 404               REGISTER_RAW_SIZE(FP0_REGNUM + reg));
 405
 406 #define fill(MEMBER, REGNO)                                             \
 407   if (! valid || valid[(REGNO)])                                        \
 408     memcpy (&xfpregs->MEMBER, &registers[REGISTER_BYTE (REGNO)],        \
 409             sizeof (xfpregs->MEMBER))
 410
 411   fill (cwd, FCTRL_REGNUM);
 412   fill (swd, FSTAT_REGNUM);
 413   fill (twd, FTAG_REGNUM);
 414   fill (fip, FCOFF_REGNUM);
 415   fill (foo, FDOFF_REGNUM);
 416   fill (fos, FDS_REGNUM);
 417
 418 #undef fill
 419
 420   if (! valid || valid[FCS_REGNUM])
 421     xfpregs->fcs
 422       = ((xfpregs->fcs & ~0xffff)
 423          | (* (int *) &registers[REGISTER_BYTE (FCS_REGNUM)] & 0xffff));
 424
 425   if (! valid || valid[FOP_REGNUM])
 426     xfpregs->fcs
 427       = ((xfpregs->fcs & 0xffff)
 428          | ((*(int *) &registers[REGISTER_BYTE (FOP_REGNUM)] & ((1 << 11) - 1))
 429             << 16));
 430
 431   /* Fill in the XMM registers.  */
 432   for (reg = 0; reg < 8; reg++)
 433     if (! valid || valid[reg])
 434       memcpy (&xfpregs->xmm_space[reg],
 435               &registers[REGISTER_BYTE (XMM0_REGNUM + reg)],
 436               REGISTER_RAW_SIZE (XMM0_REGNUM + reg));
 437 }
 438
 439
 440 /* Make a PTRACE_GETXFPREGS request, and supply all the register
 441    values that yields to GDB.  */
 442 static int
 443 fetch_xfpregs (int tid)
 444 {
 445   int ret;
 446   struct user_xfpregs_struct xfpregs;
 447
 448   if (! have_ptrace_getxfpregs)
 449     return 0;
 450
 451   ret = ptrace (PTRACE_GETXFPREGS, tid, 0, &xfpregs);
 452   if (ret == -1)
 453     {
 454       if (errno == EIO)
 455         {
 456           have_ptrace_getxfpregs = 0;
 457           return 0;
 458         }
 459
 460       warning ("couldn't read floating-point and SSE registers.");
 461       return 0;
 462     }
 463
 464   supply_xfpregset (&xfpregs);
 465   return 1;
 466 }
 467
 468
 469 /* Send all the valid register values in GDB's register file covered
 470    by the PTRACE_SETXFPREGS request to the inferior.  */
 471 static int
 472 store_xfpregs (int tid)
 473 {
 474   int ret;
 475   struct user_xfpregs_struct xfpregs;
 476
 477   if (! have_ptrace_getxfpregs)
 478     return 0;
 479
 480   ret = ptrace (PTRACE_GETXFPREGS, tid, 0, &xfpregs);
 481   if (ret == -1)
 482     {
 483       if (errno == EIO)
 484         {
 485           have_ptrace_getxfpregs = 0;
 486           return 0;
 487         }
 488
 489       warning ("couldn't read floating-point and SSE registers.");
 490       return 0;
 491     }
 492
 493   convert_to_xfpregset (&xfpregs, registers, register_valid);
 494
 495   if (ptrace (PTRACE_SETXFPREGS, tid, 0, &xfpregs) < 0)
 496     {
 497       warning ("Couldn't write floating-point and SSE registers.");
 498       return 0;
 499     }
 500
 501   return 1;
 502 }
 503
 504
 505 /* Fill the XMM registers in the register file with dummy values.  For
 506    cases where we don't have access to the XMM registers.  I think
 507    this is cleaner than printing a warning.  For a cleaner solution,
 508    we should gdbarchify the i386 family.  */
 509 static void
 510 dummy_sse_values ()
 511 {
 512   /* C doesn't have a syntax for NaN's, so write it out as an array of
 513      longs.  */
 514   static long dummy[4] = { 0xffffffff, 0xffffffff, 0xffffffff, 0xffffffff };
 515   static long mxcsr = 0x1f80;
 516   int reg;
 517
 518   for (reg = 0; reg < 8; reg++)
 519     supply_register (XMM0_REGNUM + reg, (char *) dummy);
 520   supply_register (MXCSR_REGNUM, (char *) &mxcsr);
 521 }
 522
 523 #else
 524
 525 /* Stub versions of the above routines, for systems that don't have
 526    PTRACE_GETXFPREGS.  */
 527 static int store_xfpregs (int tid) { return 0; }
 528 static int fetch_xfpregs (int tid) { return 0; }
 529 static void dummy_sse_values () {}
 530
 531 #endif
 532
 533 \f
 534 /* Transferring arbitrary registers between GDB and inferior.  */
 535
 536 /* Fetch registers from the child process.
 537    Fetch all if regno == -1, otherwise fetch all ordinary
 538    registers or all floating point registers depending
 539    upon the value of regno. */
 540
 541 void
 542 fetch_inferior_registers (int regno)
 543 {
 544   /* linux lwp id's are process id's */
 545   int tid;
 546
 547   if ((tid = TIDGET (inferior_pid)) == 0)
 548     tid = inferior_pid;         /* not a threaded program */
 549
 550   /* Use the xfpregs requests whenever possible, since they transfer
 551      more registers in one system call, and we'll cache the results.
 552      But remember that fetch_xfpregs can fail, and return zero.  */
 553   if (regno == -1)
 554     {
 555       fetch_regs (tid);
 556       if (fetch_xfpregs (tid))
 557         return;
 558       fetch_fpregs (tid);
 559       return;
 560     }
 561
 562   if (GETREGS_SUPPLIES (regno))
 563     {
 564       fetch_regs (tid);
 565       return;
 566     }
 567
 568   if (GETXFPREGS_SUPPLIES (regno))
 569     {
 570       if (fetch_xfpregs (tid))
 571         return;
 572
 573       /* Either our processor or our kernel doesn't support the SSE
 574          registers, so read the FP registers in the traditional way,
 575          and fill the SSE registers with dummy values.  It would be
 576          more graceful to handle differences in the register set using
 577          gdbarch.  Until then, this will at least make things work
 578          plausibly.  */
 579       fetch_fpregs (tid);
 580       dummy_sse_values ();
 581       return;
 582     }
 583
 584   internal_error ("i386-linux-nat.c (fetch_inferior_registers): "
 585                   "got request for bad register number %d", regno);
 586 }
 587
 588
 589 /* Store our register values back into the inferior.
 590    If REGNO is -1, do this for all registers.
 591    Otherwise, REGNO specifies which register, which
 592    then determines whether we store all ordinary
 593    registers or all of the floating point registers. */
 594
 595 void
 596 store_inferior_registers (regno)
 597      int regno;
 598 {
 599   /* linux lwp id's are process id's */
 600   int tid;
 601
 602   if ((tid = TIDGET (inferior_pid)) == 0)
 603     tid = inferior_pid;         /* not a threaded program */
 604
 605   /* Use the xfpregs requests whenever possible, since they transfer
 606      more registers in one system call.  But remember that
 607      store_xfpregs can fail, and return zero.  */
 608   if (regno == -1)
 609     {
 610       store_regs (tid);
 611       if (store_xfpregs (tid))
 612         return;
 613       store_fpregs (tid);
 614       return;
 615     }
 616
 617   if (GETREGS_SUPPLIES (regno))
 618     {
 619       store_regs (tid);
 620       return;
 621     }
 622
 623   if (GETXFPREGS_SUPPLIES (regno))
 624     {
 625       if (store_xfpregs (tid))
 626         return;
 627
 628       /* Either our processor or our kernel doesn't support the SSE
 629          registers, so just write the FP registers in the traditional way.  */
 630       store_fpregs (tid);
 631       return;
 632     }
 633
 634   internal_error ("i386-linux-nat.c (store_inferior_registers): "
 635                   "got request to store bad register number %d", regno);
 636 }
 637
 638
 639 \f
 640 /* Interpreting register set info found in core files.  */
 641
 642 /* Provide registers to GDB from a core file.
 643
 644    (We can't use the generic version of this function in
 645    core-regset.c, because Linux has *three* different kinds of
 646    register set notes.  core-regset.c would have to call
 647    supply_xfpregset, which most platforms don't have.)
 648
 649    CORE_REG_SECT points to an array of bytes, which are the contents
 650    of a `note' from a core file which BFD thinks might contain
 651    register contents.  CORE_REG_SIZE is its size.
 652
 653    WHICH says which register set corelow suspects this is:
 654    0 --- the general register set, in gregset format
 655    2 --- the floating-point register set, in fpregset format
 656    3 --- the extended floating-point register set, in struct
 657          user_xfpregs_struct format
 658
 659    DUMMY isn't used on Linux.  */
 660 static void
 661 i386_linux_fetch_core_registers (char *core_reg_sect,
 662                                  unsigned core_reg_size,
 663                                  int which,
 664                                  CORE_ADDR dummy)
 665 {
 666   gregset_t gregset;
 667   fpregset_t fpregset;
 668
 669   switch (which)
 670     {
 671     case 0:
 672       if (core_reg_size != sizeof (gregset))
 673         warning ("wrong size gregset struct in core file");
 674       else
 675         {
 676           memcpy (&gregset, core_reg_sect, sizeof (gregset));
 677           supply_gregset (&gregset);
 678         }
 679       break;
 680
 681     case 2:
 682       if (core_reg_size != sizeof (fpregset))
 683         warning ("wrong size fpregset struct in core file");
 684       else
 685         {
 686           memcpy (&fpregset, core_reg_sect, sizeof (fpregset));
 687           supply_fpregset (&fpregset);
 688         }
 689       break;
 690
 691 #ifdef HAVE_PTRACE_GETXFPREGS
 692       {
 693         struct user_xfpregs_struct xfpregset;
 694       case 3:
 695         if (core_reg_size != sizeof (struct user_xfpregs_struct))
 696           warning ("wrong size user_xfpregs_struct in core file");
 697         else
 698           {
 699             memcpy (&xfpregset, core_reg_sect, sizeof (xfpregset));
 700             supply_xfpregset (&xfpregset);
 701           }
 702         break;
 703       }
 704 #endif
 705
 706     default:
 707       /* We've covered all the kinds of registers we know about here,
 708          so this must be something we wouldn't know what to do with
 709          anyway.  Just ignore it.  */
 710       break;
 711     }
 712 }
 713
 714
 715 static struct core_fns i386_linux_nat_core_fns =
 716 {
 717   bfd_target_elf_flavour,               /* core_flavour */
 718   default_check_format,                 /* check_format */
 719   default_core_sniffer,                 /* core_sniffer */
 720   i386_linux_fetch_core_registers,      /* core_read_registers */
 721   NULL                                  /* next */
 722 };
 723
 724 \f
 725 /* Calling functions in shared libraries.  */
 726
 727 /* Find the minimal symbol named NAME, and return both the minsym
 728    struct and its objfile.  This probably ought to be in minsym.c, but
 729    everything there is trying to deal with things like C++ and
 730    SOFUN_ADDRESS_MAYBE_TURQUOISE, ...  Since this is so simple, it may
 731    be considered too special-purpose for general consumption.  */
 732
 733 static struct minimal_symbol *
 734 find_minsym_and_objfile (char *name, struct objfile **objfile_p)
 735 {
 736   struct objfile *objfile;
 737
 738   ALL_OBJFILES (objfile)
 739     {
 740       struct minimal_symbol *msym;
 741
 742       ALL_OBJFILE_MSYMBOLS (objfile, msym)
 743         {
 744           if (SYMBOL_NAME (msym)
 745               && STREQ (SYMBOL_NAME (msym), name))
 746             {
 747               *objfile_p = objfile;
 748               return msym;
 749             }
 750         }
 751     }
 752
 753   return 0;
 754 }
 755
 756
 757 static CORE_ADDR
 758 skip_hurd_resolver (CORE_ADDR pc)
 759 {
 760   /* The HURD dynamic linker is part of the GNU C library, so many
 761      GNU/Linux distributions use it.  (All ELF versions, as far as I
 762      know.)  An unresolved PLT entry points to "_dl_runtime_resolve",
 763      which calls "fixup" to patch the PLT, and then passes control to
 764      the function.
 765
 766      We look for the symbol `_dl_runtime_resolve', and find `fixup' in
 767      the same objfile.  If we are at the entry point of `fixup', then
 768      we set a breakpoint at the return address (at the top of the
 769      stack), and continue.
 770
 771      It's kind of gross to do all these checks every time we're
 772      called, since they don't change once the executable has gotten
 773      started.  But this is only a temporary hack --- upcoming versions
 774      of Linux will provide a portable, efficient interface for
 775      debugging programs that use shared libraries.  */
 776
 777   struct objfile *objfile;
 778   struct minimal_symbol *resolver
 779     = find_minsym_and_objfile ("_dl_runtime_resolve", &objfile);
 780
 781   if (resolver)
 782     {
 783       struct minimal_symbol *fixup
 784         = lookup_minimal_symbol ("fixup", 0, objfile);
 785
 786       if (fixup && SYMBOL_VALUE_ADDRESS (fixup) == pc)
 787         return (SAVED_PC_AFTER_CALL (get_current_frame ()));
 788     }
 789
 790   return 0;
 791 }
 792
 793
 794 /* See the comments for SKIP_SOLIB_RESOLVER at the top of infrun.c.
 795    This function:
 796    1) decides whether a PLT has sent us into the linker to resolve
 797       a function reference, and
 798    2) if so, tells us where to set a temporary breakpoint that will
 799       trigger when the dynamic linker is done.  */
 800
 801 CORE_ADDR
 802 i386_linux_skip_solib_resolver (CORE_ADDR pc)
 803 {
 804   CORE_ADDR result;
 805
 806   /* Plug in functions for other kinds of resolvers here.  */
 807   result = skip_hurd_resolver (pc);
 808   if (result)
 809     return result;
 810
 811   return 0;
 812 }
 813
 814
 815 \f
 816 /* Module initialization.  */
 817
 818 void
 819 _initialize_i386_linux_nat ()
 820 {
 821   add_core_fns (&i386_linux_nat_core_fns);
 822 }