gdb/i386-linux-nat.c

   1 /* Native-dependent code for GNU/Linux i386.
   2
   3    Copyright (C) 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008,
   4    2009, 2010, 2011 Free Software Foundation, Inc.
   5
   6    This file is part of GDB.
   7
   8    This program is free software; you can redistribute it and/or modify
   9    it under the terms of the GNU General Public License as published by
  10    the Free Software Foundation; either version 3 of the License, or
  11    (at your option) any later version.
  12
  13    This program is distributed in the hope that it will be useful,
  14    but WITHOUT ANY WARRANTY; without even the implied warranty of
  15    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16    GNU General Public License for more details.
  17
  18    You should have received a copy of the GNU General Public License
  19    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  20
  21 #include "defs.h"
  22 #include "i386-nat.h"
  23 #include "inferior.h"
  24 #include "gdbcore.h"
  25 #include "regcache.h"
  26 #include "regset.h"
  27 #include "target.h"
  28 #include "linux-nat.h"
  29
  30 #include "gdb_assert.h"
  31 #include "gdb_string.h"
  32 #include "elf/common.h"
  33 #include <sys/uio.h>
  34 #include <sys/ptrace.h>
  35 #include <sys/user.h>
  36 #include <sys/procfs.h>
  37
  38 #ifdef HAVE_SYS_REG_H
  39 #include <sys/reg.h>
  40 #endif
  41
  42 #ifndef ORIG_EAX
  43 #define ORIG_EAX -1
  44 #endif
  45
  46 #ifdef HAVE_SYS_DEBUGREG_H
  47 #include <sys/debugreg.h>
  48 #endif
  49
  50 #ifndef DR_FIRSTADDR
  51 #define DR_FIRSTADDR 0
  52 #endif
  53
  54 #ifndef DR_LASTADDR
  55 #define DR_LASTADDR 3
  56 #endif
  57
  58 #ifndef DR_STATUS
  59 #define DR_STATUS 6
  60 #endif
  61
  62 #ifndef DR_CONTROL
  63 #define DR_CONTROL 7
  64 #endif
  65
  66 /* Prototypes for supply_gregset etc.  */
  67 #include "gregset.h"
  68
  69 #include "i387-tdep.h"
  70 #include "i386-tdep.h"
  71 #include "i386-linux-tdep.h"
  72
  73 /* Defines ps_err_e, struct ps_prochandle.  */
  74 #include "gdb_proc_service.h"
  75
  76 #include "i386-xstate.h"
  77
  78 #ifndef PTRACE_GETREGSET
  79 #define PTRACE_GETREGSET        0x4204
  80 #endif
  81
  82 #ifndef PTRACE_SETREGSET
  83 #define PTRACE_SETREGSET        0x4205
  84 #endif
  85
  86 /* Does the current host support PTRACE_GETREGSET?  */
  87 static int have_ptrace_getregset = -1;
  88 \f
  89
  90 /* The register sets used in GNU/Linux ELF core-dumps are identical to
  91    the register sets in `struct user' that is used for a.out
  92    core-dumps, and is also used by `ptrace'.  The corresponding types
  93    are `elf_gregset_t' for the general-purpose registers (with
  94    `elf_greg_t' the type of a single GP register) and `elf_fpregset_t'
  95    for the floating-point registers.
  96
  97    Those types used to be available under the names `gregset_t' and
  98    `fpregset_t' too, and this file used those names in the past.  But
  99    those names are now used for the register sets used in the
 100    `mcontext_t' type, and have a different size and layout.  */
 101
 102 /* Which ptrace request retrieves which registers?
 103    These apply to the corresponding SET requests as well.  */
 104
 105 #define GETREGS_SUPPLIES(regno) \
 106   ((0 <= (regno) && (regno) <= 15) || (regno) == I386_LINUX_ORIG_EAX_REGNUM)
 107
 108 #define GETFPXREGS_SUPPLIES(regno) \
 109   (I386_ST0_REGNUM <= (regno) && (regno) < I386_SSE_NUM_REGS)
 110
 111 #define GETXSTATEREGS_SUPPLIES(regno) \
 112   (I386_ST0_REGNUM <= (regno) && (regno) < I386_AVX_NUM_REGS)
 113
 114 /* Does the current host support the GETREGS request?  */
 115 int have_ptrace_getregs =
 116 #ifdef HAVE_PTRACE_GETREGS
 117   1
 118 #else
 119   0
 120 #endif
 121 ;
 122
 123 /* Does the current host support the GETFPXREGS request?  The header
 124    file may or may not define it, and even if it is defined, the
 125    kernel will return EIO if it's running on a pre-SSE processor.
 126
 127    My instinct is to attach this to some architecture- or
 128    target-specific data structure, but really, a particular GDB
 129    process can only run on top of one kernel at a time.  So it's okay
 130    for this to be a simple variable.  */
 131 int have_ptrace_getfpxregs =
 132 #ifdef HAVE_PTRACE_GETFPXREGS
 133   -1
 134 #else
 135   0
 136 #endif
 137 ;
 138 \f
 139
 140 /* Accessing registers through the U area, one at a time.  */
 141
 142 /* Fetch one register.  */
 143
 144 static void
 145 fetch_register (struct regcache *regcache, int regno)
 146 {
 147   int tid;
 148   int val;
 149
 150   gdb_assert (!have_ptrace_getregs);
 151   if (i386_linux_gregset_reg_offset[regno] == -1)
 152     {
 153       regcache_raw_supply (regcache, regno, NULL);
 154       return;
 155     }
 156
 157   /* GNU/Linux LWP ID's are process ID's.  */
 158   tid = TIDGET (inferior_ptid);
 159   if (tid == 0)
 160     tid = PIDGET (inferior_ptid); /* Not a threaded program.  */
 161
 162   errno = 0;
 163   val = ptrace (PTRACE_PEEKUSER, tid,
 164                 i386_linux_gregset_reg_offset[regno], 0);
 165   if (errno != 0)
 166     error (_("Couldn't read register %s (#%d): %s."),
 167            gdbarch_register_name (get_regcache_arch (regcache), regno),
 168            regno, safe_strerror (errno));
 169
 170   regcache_raw_supply (regcache, regno, &val);
 171 }
 172
 173 /* Store one register. */
 174
 175 static void
 176 store_register (const struct regcache *regcache, int regno)
 177 {
 178   int tid;
 179   int val;
 180
 181   gdb_assert (!have_ptrace_getregs);
 182   if (i386_linux_gregset_reg_offset[regno] == -1)
 183     return;
 184
 185   /* GNU/Linux LWP ID's are process ID's.  */
 186   tid = TIDGET (inferior_ptid);
 187   if (tid == 0)
 188     tid = PIDGET (inferior_ptid); /* Not a threaded program.  */
 189
 190   errno = 0;
 191   regcache_raw_collect (regcache, regno, &val);
 192   ptrace (PTRACE_POKEUSER, tid,
 193           i386_linux_gregset_reg_offset[regno], val);
 194   if (errno != 0)
 195     error (_("Couldn't write register %s (#%d): %s."),
 196            gdbarch_register_name (get_regcache_arch (regcache), regno),
 197            regno, safe_strerror (errno));
 198 }
 199 \f
 200
 201 /* Transfering the general-purpose registers between GDB, inferiors
 202    and core files.  */
 203
 204 /* Fill GDB's register array with the general-purpose register values
 205    in *GREGSETP.  */
 206
 207 void
 208 supply_gregset (struct regcache *regcache, const elf_gregset_t *gregsetp)
 209 {
 210   const gdb_byte *regp = (const gdb_byte *) gregsetp;
 211   int i;
 212
 213   for (i = 0; i < I386_NUM_GREGS; i++)
 214     regcache_raw_supply (regcache, i,
 215                          regp + i386_linux_gregset_reg_offset[i]);
 216
 217   if (I386_LINUX_ORIG_EAX_REGNUM
 218         < gdbarch_num_regs (get_regcache_arch (regcache)))
 219     regcache_raw_supply (regcache, I386_LINUX_ORIG_EAX_REGNUM,
 220                           regp + i386_linux_gregset_reg_offset[I386_LINUX_ORIG_EAX_REGNUM]);
 221 }
 222
 223 /* Fill register REGNO (if it is a general-purpose register) in
 224    *GREGSETPS with the value in GDB's register array.  If REGNO is -1,
 225    do this for all registers.  */
 226
 227 void
 228 fill_gregset (const struct regcache *regcache,
 229               elf_gregset_t *gregsetp, int regno)
 230 {
 231   gdb_byte *regp = (gdb_byte *) gregsetp;
 232   int i;
 233
 234   for (i = 0; i < I386_NUM_GREGS; i++)
 235     if (regno == -1 || regno == i)
 236       regcache_raw_collect (regcache, i,
 237                             regp + i386_linux_gregset_reg_offset[i]);
 238
 239   if ((regno == -1 || regno == I386_LINUX_ORIG_EAX_REGNUM)
 240       && I386_LINUX_ORIG_EAX_REGNUM
 241            < gdbarch_num_regs (get_regcache_arch (regcache)))
 242     regcache_raw_collect (regcache, I386_LINUX_ORIG_EAX_REGNUM,
 243                           regp + i386_linux_gregset_reg_offset[I386_LINUX_ORIG_EAX_REGNUM]);
 244 }
 245
 246 #ifdef HAVE_PTRACE_GETREGS
 247
 248 /* Fetch all general-purpose registers from process/thread TID and
 249    store their values in GDB's register array.  */
 250
 251 static void
 252 fetch_regs (struct regcache *regcache, int tid)
 253 {
 254   elf_gregset_t regs;
 255   elf_gregset_t *regs_p = &regs;
 256
 257   if (ptrace (PTRACE_GETREGS, tid, 0, (int) &regs) < 0)
 258     {
 259       if (errno == EIO)
 260         {
 261           /* The kernel we're running on doesn't support the GETREGS
 262              request.  Reset `have_ptrace_getregs'.  */
 263           have_ptrace_getregs = 0;
 264           return;
 265         }
 266
 267       perror_with_name (_("Couldn't get registers"));
 268     }
 269
 270   supply_gregset (regcache, (const elf_gregset_t *) regs_p);
 271 }
 272
 273 /* Store all valid general-purpose registers in GDB's register array
 274    into the process/thread specified by TID.  */
 275
 276 static void
 277 store_regs (const struct regcache *regcache, int tid, int regno)
 278 {
 279   elf_gregset_t regs;
 280
 281   if (ptrace (PTRACE_GETREGS, tid, 0, (int) &regs) < 0)
 282     perror_with_name (_("Couldn't get registers"));
 283
 284   fill_gregset (regcache, &regs, regno);
 285
 286   if (ptrace (PTRACE_SETREGS, tid, 0, (int) &regs) < 0)
 287     perror_with_name (_("Couldn't write registers"));
 288 }
 289
 290 #else
 291
 292 static void fetch_regs (struct regcache *regcache, int tid) {}
 293 static void store_regs (const struct regcache *regcache, int tid, int regno) {}
 294
 295 #endif
 296 \f
 297
 298 /* Transfering floating-point registers between GDB, inferiors and cores.  */
 299
 300 /* Fill GDB's register array with the floating-point register values in
 301    *FPREGSETP.  */
 302
 303 void
 304 supply_fpregset (struct regcache *regcache, const elf_fpregset_t *fpregsetp)
 305 {
 306   i387_supply_fsave (regcache, -1, fpregsetp);
 307 }
 308
 309 /* Fill register REGNO (if it is a floating-point register) in
 310    *FPREGSETP with the value in GDB's register array.  If REGNO is -1,
 311    do this for all registers.  */
 312
 313 void
 314 fill_fpregset (const struct regcache *regcache,
 315                elf_fpregset_t *fpregsetp, int regno)
 316 {
 317   i387_collect_fsave (regcache, regno, fpregsetp);
 318 }
 319
 320 #ifdef HAVE_PTRACE_GETREGS
 321
 322 /* Fetch all floating-point registers from process/thread TID and store
 323    thier values in GDB's register array.  */
 324
 325 static void
 326 fetch_fpregs (struct regcache *regcache, int tid)
 327 {
 328   elf_fpregset_t fpregs;
 329
 330   if (ptrace (PTRACE_GETFPREGS, tid, 0, (int) &fpregs) < 0)
 331     perror_with_name (_("Couldn't get floating point status"));
 332
 333   supply_fpregset (regcache, (const elf_fpregset_t *) &fpregs);
 334 }
 335
 336 /* Store all valid floating-point registers in GDB's register array
 337    into the process/thread specified by TID.  */
 338
 339 static void
 340 store_fpregs (const struct regcache *regcache, int tid, int regno)
 341 {
 342   elf_fpregset_t fpregs;
 343
 344   if (ptrace (PTRACE_GETFPREGS, tid, 0, (int) &fpregs) < 0)
 345     perror_with_name (_("Couldn't get floating point status"));
 346
 347   fill_fpregset (regcache, &fpregs, regno);
 348
 349   if (ptrace (PTRACE_SETFPREGS, tid, 0, (int) &fpregs) < 0)
 350     perror_with_name (_("Couldn't write floating point status"));
 351 }
 352
 353 #else
 354
 355 static void fetch_fpregs (struct regcache *regcache, int tid) {}
 356 static void store_fpregs (const struct regcache *regcache, int tid, int regno) {}
 357
 358 #endif
 359 \f
 360
 361 /* Transfering floating-point and SSE registers to and from GDB.  */
 362
 363 /* Fetch all registers covered by the PTRACE_GETREGSET request from
 364    process/thread TID and store their values in GDB's register array.
 365    Return non-zero if successful, zero otherwise.  */
 366
 367 static int
 368 fetch_xstateregs (struct regcache *regcache, int tid)
 369 {
 370   char xstateregs[I386_XSTATE_MAX_SIZE];
 371   struct iovec iov;
 372
 373   if (!have_ptrace_getregset)
 374     return 0;
 375
 376   iov.iov_base = xstateregs;
 377   iov.iov_len = sizeof(xstateregs);
 378   if (ptrace (PTRACE_GETREGSET, tid, (unsigned int) NT_X86_XSTATE,
 379               &iov) < 0)
 380     perror_with_name (_("Couldn't read extended state status"));
 381
 382   i387_supply_xsave (regcache, -1, xstateregs);
 383   return 1;
 384 }
 385
 386 /* Store all valid registers in GDB's register array covered by the
 387    PTRACE_SETREGSET request into the process/thread specified by TID.
 388    Return non-zero if successful, zero otherwise.  */
 389
 390 static int
 391 store_xstateregs (const struct regcache *regcache, int tid, int regno)
 392 {
 393   char xstateregs[I386_XSTATE_MAX_SIZE];
 394   struct iovec iov;
 395
 396   if (!have_ptrace_getregset)
 397     return 0;
 398
 399   iov.iov_base = xstateregs;
 400   iov.iov_len = sizeof(xstateregs);
 401   if (ptrace (PTRACE_GETREGSET, tid, (unsigned int) NT_X86_XSTATE,
 402               &iov) < 0)
 403     perror_with_name (_("Couldn't read extended state status"));
 404
 405   i387_collect_xsave (regcache, regno, xstateregs, 0);
 406
 407   if (ptrace (PTRACE_SETREGSET, tid, (unsigned int) NT_X86_XSTATE,
 408               (int) &iov) < 0)
 409     perror_with_name (_("Couldn't write extended state status"));
 410
 411   return 1;
 412 }
 413
 414 #ifdef HAVE_PTRACE_GETFPXREGS
 415
 416 /* Fetch all registers covered by the PTRACE_GETFPXREGS request from
 417    process/thread TID and store their values in GDB's register array.
 418    Return non-zero if successful, zero otherwise.  */
 419
 420 static int
 421 fetch_fpxregs (struct regcache *regcache, int tid)
 422 {
 423   elf_fpxregset_t fpxregs;
 424
 425   if (! have_ptrace_getfpxregs)
 426     return 0;
 427
 428   if (ptrace (PTRACE_GETFPXREGS, tid, 0, (int) &fpxregs) < 0)
 429     {
 430       if (errno == EIO)
 431         {
 432           have_ptrace_getfpxregs = 0;
 433           return 0;
 434         }
 435
 436       perror_with_name (_("Couldn't read floating-point and SSE registers"));
 437     }
 438
 439   i387_supply_fxsave (regcache, -1, (const elf_fpxregset_t *) &fpxregs);
 440   return 1;
 441 }
 442
 443 /* Store all valid registers in GDB's register array covered by the
 444    PTRACE_SETFPXREGS request into the process/thread specified by TID.
 445    Return non-zero if successful, zero otherwise.  */
 446
 447 static int
 448 store_fpxregs (const struct regcache *regcache, int tid, int regno)
 449 {
 450   elf_fpxregset_t fpxregs;
 451
 452   if (! have_ptrace_getfpxregs)
 453     return 0;
 454
 455   if (ptrace (PTRACE_GETFPXREGS, tid, 0, &fpxregs) == -1)
 456     {
 457       if (errno == EIO)
 458         {
 459           have_ptrace_getfpxregs = 0;
 460           return 0;
 461         }
 462
 463       perror_with_name (_("Couldn't read floating-point and SSE registers"));
 464     }
 465
 466   i387_collect_fxsave (regcache, regno, &fpxregs);
 467
 468   if (ptrace (PTRACE_SETFPXREGS, tid, 0, &fpxregs) == -1)
 469     perror_with_name (_("Couldn't write floating-point and SSE registers"));
 470
 471   return 1;
 472 }
 473
 474 #else
 475
 476 static int fetch_fpxregs (struct regcache *regcache, int tid) { return 0; }
 477 static int store_fpxregs (const struct regcache *regcache, int tid, int regno) { return 0; }
 478
 479 #endif /* HAVE_PTRACE_GETFPXREGS */
 480 \f
 481
 482 /* Transferring arbitrary registers between GDB and inferior.  */
 483
 484 /* Fetch register REGNO from the child process.  If REGNO is -1, do
 485    this for all registers (including the floating point and SSE
 486    registers).  */
 487
 488 static void
 489 i386_linux_fetch_inferior_registers (struct target_ops *ops,
 490                                      struct regcache *regcache, int regno)
 491 {
 492   int tid;
 493
 494   /* Use the old method of peeking around in `struct user' if the
 495      GETREGS request isn't available.  */
 496   if (!have_ptrace_getregs)
 497     {
 498       int i;
 499
 500       for (i = 0; i < gdbarch_num_regs (get_regcache_arch (regcache)); i++)
 501         if (regno == -1 || regno == i)
 502           fetch_register (regcache, i);
 503
 504       return;
 505     }
 506
 507   /* GNU/Linux LWP ID's are process ID's.  */
 508   tid = TIDGET (inferior_ptid);
 509   if (tid == 0)
 510     tid = PIDGET (inferior_ptid); /* Not a threaded program.  */
 511
 512   /* Use the PTRACE_GETFPXREGS request whenever possible, since it
 513      transfers more registers in one system call, and we'll cache the
 514      results.  But remember that fetch_fpxregs can fail, and return
 515      zero.  */
 516   if (regno == -1)
 517     {
 518       fetch_regs (regcache, tid);
 519
 520       /* The call above might reset `have_ptrace_getregs'.  */
 521       if (!have_ptrace_getregs)
 522         {
 523           i386_linux_fetch_inferior_registers (ops, regcache, regno);
 524           return;
 525         }
 526
 527       if (fetch_xstateregs (regcache, tid))
 528         return;
 529       if (fetch_fpxregs (regcache, tid))
 530         return;
 531       fetch_fpregs (regcache, tid);
 532       return;
 533     }
 534
 535   if (GETREGS_SUPPLIES (regno))
 536     {
 537       fetch_regs (regcache, tid);
 538       return;
 539     }
 540
 541   if (GETXSTATEREGS_SUPPLIES (regno))
 542     {
 543       if (fetch_xstateregs (regcache, tid))
 544         return;
 545     }
 546
 547   if (GETFPXREGS_SUPPLIES (regno))
 548     {
 549       if (fetch_fpxregs (regcache, tid))
 550         return;
 551
 552       /* Either our processor or our kernel doesn't support the SSE
 553          registers, so read the FP registers in the traditional way,
 554          and fill the SSE registers with dummy values.  It would be
 555          more graceful to handle differences in the register set using
 556          gdbarch.  Until then, this will at least make things work
 557          plausibly.  */
 558       fetch_fpregs (regcache, tid);
 559       return;
 560     }
 561
 562   internal_error (__FILE__, __LINE__,
 563                   _("Got request for bad register number %d."), regno);
 564 }
 565
 566 /* Store register REGNO back into the child process.  If REGNO is -1,
 567    do this for all registers (including the floating point and SSE
 568    registers).  */
 569 static void
 570 i386_linux_store_inferior_registers (struct target_ops *ops,
 571                                      struct regcache *regcache, int regno)
 572 {
 573   int tid;
 574
 575   /* Use the old method of poking around in `struct user' if the
 576      SETREGS request isn't available.  */
 577   if (!have_ptrace_getregs)
 578     {
 579       int i;
 580
 581       for (i = 0; i < gdbarch_num_regs (get_regcache_arch (regcache)); i++)
 582         if (regno == -1 || regno == i)
 583           store_register (regcache, i);
 584
 585       return;
 586     }
 587
 588   /* GNU/Linux LWP ID's are process ID's.  */
 589   tid = TIDGET (inferior_ptid);
 590   if (tid == 0)
 591     tid = PIDGET (inferior_ptid); /* Not a threaded program.  */
 592
 593   /* Use the PTRACE_SETFPXREGS requests whenever possible, since it
 594      transfers more registers in one system call.  But remember that
 595      store_fpxregs can fail, and return zero.  */
 596   if (regno == -1)
 597     {
 598       store_regs (regcache, tid, regno);
 599       if (store_xstateregs (regcache, tid, regno))
 600         return;
 601       if (store_fpxregs (regcache, tid, regno))
 602         return;
 603       store_fpregs (regcache, tid, regno);
 604       return;
 605     }
 606
 607   if (GETREGS_SUPPLIES (regno))
 608     {
 609       store_regs (regcache, tid, regno);
 610       return;
 611     }
 612
 613   if (GETXSTATEREGS_SUPPLIES (regno))
 614     {
 615       if (store_xstateregs (regcache, tid, regno))
 616         return;
 617     }
 618
 619   if (GETFPXREGS_SUPPLIES (regno))
 620     {
 621       if (store_fpxregs (regcache, tid, regno))
 622         return;
 623
 624       /* Either our processor or our kernel doesn't support the SSE
 625          registers, so just write the FP registers in the traditional
 626          way.  */
 627       store_fpregs (regcache, tid, regno);
 628       return;
 629     }
 630
 631   internal_error (__FILE__, __LINE__,
 632                   _("Got request to store bad register number %d."), regno);
 633 }
 634 \f
 635
 636 /* Support for debug registers.  */
 637
 638 static unsigned long i386_linux_dr[DR_CONTROL + 1];
 639
 640 /* Get debug register REGNUM value from only the one LWP of PTID.  */
 641
 642 static unsigned long
 643 i386_linux_dr_get (ptid_t ptid, int regnum)
 644 {
 645   int tid;
 646   unsigned long value;
 647
 648   tid = TIDGET (ptid);
 649   if (tid == 0)
 650     tid = PIDGET (ptid);
 651
 652   /* FIXME: kettenis/2001-03-27: Calling perror_with_name if the
 653      ptrace call fails breaks debugging remote targets.  The correct
 654      way to fix this is to add the hardware breakpoint and watchpoint
 655      stuff to the target vector.  For now, just return zero if the
 656      ptrace call fails.  */
 657   errno = 0;
 658   value = ptrace (PTRACE_PEEKUSER, tid,
 659                   offsetof (struct user, u_debugreg[regnum]), 0);
 660   if (errno != 0)
 661 #if 0
 662     perror_with_name (_("Couldn't read debug register"));
 663 #else
 664     return 0;
 665 #endif
 666
 667   return value;
 668 }
 669
 670 /* Set debug register REGNUM to VALUE in only the one LWP of PTID.  */
 671
 672 static void
 673 i386_linux_dr_set (ptid_t ptid, int regnum, unsigned long value)
 674 {
 675   int tid;
 676
 677   tid = TIDGET (ptid);
 678   if (tid == 0)
 679     tid = PIDGET (ptid);
 680
 681   errno = 0;
 682   ptrace (PTRACE_POKEUSER, tid,
 683           offsetof (struct user, u_debugreg[regnum]), value);
 684   if (errno != 0)
 685     perror_with_name (_("Couldn't write debug register"));
 686 }
 687
 688 /* Set DR_CONTROL to ADDR in all LWPs of LWP_LIST.  */
 689
 690 static void
 691 i386_linux_dr_set_control (unsigned long control)
 692 {
 693   struct lwp_info *lp;
 694   ptid_t ptid;
 695
 696   i386_linux_dr[DR_CONTROL] = control;
 697   ALL_LWPS (lp, ptid)
 698     i386_linux_dr_set (ptid, DR_CONTROL, control);
 699 }
 700
 701 /* Set address REGNUM (zero based) to ADDR in all LWPs of LWP_LIST.  */
 702
 703 static void
 704 i386_linux_dr_set_addr (int regnum, CORE_ADDR addr)
 705 {
 706   struct lwp_info *lp;
 707   ptid_t ptid;
 708
 709   gdb_assert (regnum >= 0 && regnum <= DR_LASTADDR - DR_FIRSTADDR);
 710
 711   i386_linux_dr[DR_FIRSTADDR + regnum] = addr;
 712   ALL_LWPS (lp, ptid)
 713     i386_linux_dr_set (ptid, DR_FIRSTADDR + regnum, addr);
 714 }
 715
 716 /* Set address REGNUM (zero based) to zero in all LWPs of LWP_LIST.  */
 717
 718 static void
 719 i386_linux_dr_reset_addr (int regnum)
 720 {
 721   i386_linux_dr_set_addr (regnum, 0);
 722 }
 723
 724 /* Get DR_STATUS from only the one LWP of INFERIOR_PTID.  */
 725
 726 static unsigned long
 727 i386_linux_dr_get_status (void)
 728 {
 729   return i386_linux_dr_get (inferior_ptid, DR_STATUS);
 730 }
 731
 732 /* Unset MASK bits in DR_STATUS in all LWPs of LWP_LIST.  */
 733
 734 static void
 735 i386_linux_dr_unset_status (unsigned long mask)
 736 {
 737   struct lwp_info *lp;
 738   ptid_t ptid;
 739
 740   ALL_LWPS (lp, ptid)
 741     {
 742       unsigned long value;
 743
 744       value = i386_linux_dr_get (ptid, DR_STATUS);
 745       value &= ~mask;
 746       i386_linux_dr_set (ptid, DR_STATUS, value);
 747     }
 748 }
 749
 750 static void
 751 i386_linux_new_thread (ptid_t ptid)
 752 {
 753   int i;
 754
 755   for (i = DR_FIRSTADDR; i <= DR_LASTADDR; i++)
 756     i386_linux_dr_set (ptid, i, i386_linux_dr[i]);
 757
 758   i386_linux_dr_set (ptid, DR_CONTROL, i386_linux_dr[DR_CONTROL]);
 759 }
 760 \f
 761
 762 /* Called by libthread_db.  Returns a pointer to the thread local
 763    storage (or its descriptor).  */
 764
 765 ps_err_e
 766 ps_get_thread_area (const struct ps_prochandle *ph,
 767                     lwpid_t lwpid, int idx, void **base)
 768 {
 769   /* NOTE: cagney/2003-08-26: The definition of this buffer is found
 770      in the kernel header <asm-i386/ldt.h>.  It, after padding, is 4 x
 771      4 byte integers in size: `entry_number', `base_addr', `limit',
 772      and a bunch of status bits.
 773
 774      The values returned by this ptrace call should be part of the
 775      regcache buffer, and ps_get_thread_area should channel its
 776      request through the regcache.  That way remote targets could
 777      provide the value using the remote protocol and not this direct
 778      call.
 779
 780      Is this function needed?  I'm guessing that the `base' is the
 781      address of a a descriptor that libthread_db uses to find the
 782      thread local address base that GDB needs.  Perhaps that
 783      descriptor is defined by the ABI.  Anyway, given that
 784      libthread_db calls this function without prompting (gdb
 785      requesting tls base) I guess it needs info in there anyway.  */
 786   unsigned int desc[4];
 787   gdb_assert (sizeof (int) == 4);
 788
 789 #ifndef PTRACE_GET_THREAD_AREA
 790 #define PTRACE_GET_THREAD_AREA 25
 791 #endif
 792
 793   if (ptrace (PTRACE_GET_THREAD_AREA, lwpid,
 794               (void *) idx, (unsigned long) &desc) < 0)
 795     return PS_ERR;
 796
 797   *(int *)base = desc[1];
 798   return PS_OK;
 799 }
 800 \f
 801
 802 /* The instruction for a GNU/Linux system call is:
 803        int $0x80
 804    or 0xcd 0x80.  */
 805
 806 static const unsigned char linux_syscall[] = { 0xcd, 0x80 };
 807
 808 #define LINUX_SYSCALL_LEN (sizeof linux_syscall)
 809
 810 /* The system call number is stored in the %eax register.  */
 811 #define LINUX_SYSCALL_REGNUM I386_EAX_REGNUM
 812
 813 /* We are specifically interested in the sigreturn and rt_sigreturn
 814    system calls.  */
 815
 816 #ifndef SYS_sigreturn
 817 #define SYS_sigreturn           0x77
 818 #endif
 819 #ifndef SYS_rt_sigreturn
 820 #define SYS_rt_sigreturn        0xad
 821 #endif
 822
 823 /* Offset to saved processor flags, from <asm/sigcontext.h>.  */
 824 #define LINUX_SIGCONTEXT_EFLAGS_OFFSET (64)
 825
 826 /* Resume execution of the inferior process.
 827    If STEP is nonzero, single-step it.
 828    If SIGNAL is nonzero, give it that signal.  */
 829
 830 static void
 831 i386_linux_resume (struct target_ops *ops,
 832                    ptid_t ptid, int step, enum target_signal signal)
 833 {
 834   int pid = PIDGET (ptid);
 835
 836   int request;
 837
 838   if (catch_syscall_enabled () > 0)
 839    request = PTRACE_SYSCALL;
 840   else
 841     request = PTRACE_CONT;
 842
 843   if (step)
 844     {
 845       struct regcache *regcache = get_thread_regcache (pid_to_ptid (pid));
 846       struct gdbarch *gdbarch = get_regcache_arch (regcache);
 847       enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
 848       ULONGEST pc;
 849       gdb_byte buf[LINUX_SYSCALL_LEN];
 850
 851       request = PTRACE_SINGLESTEP;
 852
 853       regcache_cooked_read_unsigned (regcache,
 854                                      gdbarch_pc_regnum (gdbarch), &pc);
 855
 856       /* Returning from a signal trampoline is done by calling a
 857          special system call (sigreturn or rt_sigreturn, see
 858          i386-linux-tdep.c for more information).  This system call
 859          restores the registers that were saved when the signal was
 860          raised, including %eflags.  That means that single-stepping
 861          won't work.  Instead, we'll have to modify the signal context
 862          that's about to be restored, and set the trace flag there.  */
 863
 864       /* First check if PC is at a system call.  */
 865       if (target_read_memory (pc, buf, LINUX_SYSCALL_LEN) == 0
 866           && memcmp (buf, linux_syscall, LINUX_SYSCALL_LEN) == 0)
 867         {
 868           ULONGEST syscall;
 869           regcache_cooked_read_unsigned (regcache,
 870                                          LINUX_SYSCALL_REGNUM, &syscall);
 871
 872           /* Then check the system call number.  */
 873           if (syscall == SYS_sigreturn || syscall == SYS_rt_sigreturn)
 874             {
 875               ULONGEST sp, addr;
 876               unsigned long int eflags;
 877
 878               regcache_cooked_read_unsigned (regcache, I386_ESP_REGNUM, &sp);
 879               if (syscall == SYS_rt_sigreturn)
 880                 addr = read_memory_integer (sp + 8, 4, byte_order) + 20;
 881               else
 882                 addr = sp;
 883
 884               /* Set the trace flag in the context that's about to be
 885                  restored.  */
 886               addr += LINUX_SIGCONTEXT_EFLAGS_OFFSET;
 887               read_memory (addr, (gdb_byte *) &eflags, 4);
 888               eflags |= 0x0100;
 889               write_memory (addr, (gdb_byte *) &eflags, 4);
 890             }
 891         }
 892     }
 893
 894   if (ptrace (request, pid, 0, target_signal_to_host (signal)) == -1)
 895     perror_with_name (("ptrace"));
 896 }
 897
 898 static void (*super_post_startup_inferior) (ptid_t ptid);
 899
 900 static void
 901 i386_linux_child_post_startup_inferior (ptid_t ptid)
 902 {
 903   i386_cleanup_dregs ();
 904   super_post_startup_inferior (ptid);
 905 }
 906
 907 /* Get Linux/x86 target description from running target.  */
 908
 909 static const struct target_desc *
 910 i386_linux_read_description (struct target_ops *ops)
 911 {
 912   int tid;
 913   static uint64_t xcr0;
 914
 915   /* GNU/Linux LWP ID's are process ID's.  */
 916   tid = TIDGET (inferior_ptid);
 917   if (tid == 0)
 918     tid = PIDGET (inferior_ptid); /* Not a threaded program.  */
 919
 920 #ifdef HAVE_PTRACE_GETFPXREGS
 921   if (have_ptrace_getfpxregs == -1)
 922     {
 923       elf_fpxregset_t fpxregs;
 924
 925       if (ptrace (PTRACE_GETFPXREGS, tid, 0, (int) &fpxregs) < 0)
 926         {
 927           have_ptrace_getfpxregs = 0;
 928           have_ptrace_getregset = 0;
 929           return tdesc_i386_mmx_linux;
 930         }
 931     }
 932 #endif
 933
 934   if (have_ptrace_getregset == -1)
 935     {
 936       uint64_t xstateregs[(I386_XSTATE_SSE_SIZE / sizeof (uint64_t))];
 937       struct iovec iov;
 938
 939       iov.iov_base = xstateregs;
 940       iov.iov_len = sizeof (xstateregs);
 941
 942       /* Check if PTRACE_GETREGSET works.  */
 943       if (ptrace (PTRACE_GETREGSET, tid, (unsigned int) NT_X86_XSTATE,
 944                   &iov) < 0)
 945         have_ptrace_getregset = 0;
 946       else
 947         {
 948           have_ptrace_getregset = 1;
 949
 950           /* Get XCR0 from XSAVE extended state.  */
 951           xcr0 = xstateregs[(I386_LINUX_XSAVE_XCR0_OFFSET
 952                              / sizeof (long long))];
 953         }
 954     }
 955
 956   /* Check the native XCR0 only if PTRACE_GETREGSET is available.  */
 957   if (have_ptrace_getregset
 958       && (xcr0 & I386_XSTATE_AVX_MASK) == I386_XSTATE_AVX_MASK)
 959     return tdesc_i386_avx_linux;
 960   else
 961     return tdesc_i386_linux;
 962 }
 963
 964 void
 965 _initialize_i386_linux_nat (void)
 966 {
 967   struct target_ops *t;
 968
 969   /* Fill in the generic GNU/Linux methods.  */
 970   t = linux_target ();
 971
 972   i386_use_watchpoints (t);
 973
 974   i386_dr_low.set_control = i386_linux_dr_set_control;
 975   i386_dr_low.set_addr = i386_linux_dr_set_addr;
 976   i386_dr_low.reset_addr = i386_linux_dr_reset_addr;
 977   i386_dr_low.get_status = i386_linux_dr_get_status;
 978   i386_dr_low.unset_status = i386_linux_dr_unset_status;
 979   i386_set_debug_register_length (4);
 980
 981   /* Override the default ptrace resume method.  */
 982   t->to_resume = i386_linux_resume;
 983
 984   /* Override the GNU/Linux inferior startup hook.  */
 985   super_post_startup_inferior = t->to_post_startup_inferior;
 986   t->to_post_startup_inferior = i386_linux_child_post_startup_inferior;
 987
 988   /* Add our register access methods.  */
 989   t->to_fetch_registers = i386_linux_fetch_inferior_registers;
 990   t->to_store_registers = i386_linux_store_inferior_registers;
 991
 992   t->to_read_description = i386_linux_read_description;
 993
 994   /* Register the target.  */
 995   linux_nat_add_target (t);
 996   linux_nat_set_new_thread (t, i386_linux_new_thread);
 997 }