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 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 /* Mapping between the general-purpose registers in `struct user'
 103    format and GDB's register array layout.  */
 104 static int regmap[] =
 105 {
 106   EAX, ECX, EDX, EBX,
 107   UESP, EBP, ESI, EDI,
 108   EIP, EFL, CS, SS,
 109   DS, ES, FS, GS,
 110   -1, -1, -1, -1,               /* st0, st1, st2, st3 */
 111   -1, -1, -1, -1,               /* st4, st5, st6, st7 */
 112   -1, -1, -1, -1,               /* fctrl, fstat, ftag, fiseg */
 113   -1, -1, -1, -1,               /* fioff, foseg, fooff, fop */
 114   -1, -1, -1, -1,               /* xmm0, xmm1, xmm2, xmm3 */
 115   -1, -1, -1, -1,               /* xmm4, xmm5, xmm6, xmm6 */
 116   -1,                           /* mxcsr */
 117   -1, -1, -1, -1,               /* ymm0h, ymm1h, ymm2h, ymm3h */
 118   -1, -1, -1, -1,               /* ymm4h, ymm5h, ymm6h, ymm6h */
 119   ORIG_EAX
 120 };
 121
 122 /* Which ptrace request retrieves which registers?
 123    These apply to the corresponding SET requests as well.  */
 124
 125 #define GETREGS_SUPPLIES(regno) \
 126   ((0 <= (regno) && (regno) <= 15) || (regno) == I386_LINUX_ORIG_EAX_REGNUM)
 127
 128 #define GETFPXREGS_SUPPLIES(regno) \
 129   (I386_ST0_REGNUM <= (regno) && (regno) < I386_SSE_NUM_REGS)
 130
 131 #define GETXSTATEREGS_SUPPLIES(regno) \
 132   (I386_ST0_REGNUM <= (regno) && (regno) < I386_AVX_NUM_REGS)
 133
 134 /* Does the current host support the GETREGS request?  */
 135 int have_ptrace_getregs =
 136 #ifdef HAVE_PTRACE_GETREGS
 137   1
 138 #else
 139   0
 140 #endif
 141 ;
 142
 143 /* Does the current host support the GETFPXREGS request?  The header
 144    file may or may not define it, and even if it is defined, the
 145    kernel will return EIO if it's running on a pre-SSE processor.
 146
 147    My instinct is to attach this to some architecture- or
 148    target-specific data structure, but really, a particular GDB
 149    process can only run on top of one kernel at a time.  So it's okay
 150    for this to be a simple variable.  */
 151 int have_ptrace_getfpxregs =
 152 #ifdef HAVE_PTRACE_GETFPXREGS
 153   1
 154 #else
 155   0
 156 #endif
 157 ;
 158 \f
 159
 160 /* Accessing registers through the U area, one at a time.  */
 161
 162 /* Fetch one register.  */
 163
 164 static void
 165 fetch_register (struct regcache *regcache, int regno)
 166 {
 167   int tid;
 168   int val;
 169
 170   gdb_assert (!have_ptrace_getregs);
 171   if (regmap[regno] == -1)
 172     {
 173       regcache_raw_supply (regcache, regno, NULL);
 174       return;
 175     }
 176
 177   /* GNU/Linux LWP ID's are process ID's.  */
 178   tid = TIDGET (inferior_ptid);
 179   if (tid == 0)
 180     tid = PIDGET (inferior_ptid); /* Not a threaded program.  */
 181
 182   errno = 0;
 183   val = ptrace (PTRACE_PEEKUSER, tid, 4 * regmap[regno], 0);
 184   if (errno != 0)
 185     error (_("Couldn't read register %s (#%d): %s."),
 186            gdbarch_register_name (get_regcache_arch (regcache), regno),
 187            regno, safe_strerror (errno));
 188
 189   regcache_raw_supply (regcache, regno, &val);
 190 }
 191
 192 /* Store one register. */
 193
 194 static void
 195 store_register (const struct regcache *regcache, int regno)
 196 {
 197   int tid;
 198   int val;
 199
 200   gdb_assert (!have_ptrace_getregs);
 201   if (regmap[regno] == -1)
 202     return;
 203
 204   /* GNU/Linux LWP ID's are process ID's.  */
 205   tid = TIDGET (inferior_ptid);
 206   if (tid == 0)
 207     tid = PIDGET (inferior_ptid); /* Not a threaded program.  */
 208
 209   errno = 0;
 210   regcache_raw_collect (regcache, regno, &val);
 211   ptrace (PTRACE_POKEUSER, tid, 4 * regmap[regno], val);
 212   if (errno != 0)
 213     error (_("Couldn't write register %s (#%d): %s."),
 214            gdbarch_register_name (get_regcache_arch (regcache), regno),
 215            regno, safe_strerror (errno));
 216 }
 217 \f
 218
 219 /* Transfering the general-purpose registers between GDB, inferiors
 220    and core files.  */
 221
 222 /* Fill GDB's register array with the general-purpose register values
 223    in *GREGSETP.  */
 224
 225 void
 226 supply_gregset (struct regcache *regcache, const elf_gregset_t *gregsetp)
 227 {
 228   const elf_greg_t *regp = (const elf_greg_t *) gregsetp;
 229   int i;
 230
 231   for (i = 0; i < I386_NUM_GREGS; i++)
 232     regcache_raw_supply (regcache, i, regp + regmap[i]);
 233
 234   if (I386_LINUX_ORIG_EAX_REGNUM
 235         < gdbarch_num_regs (get_regcache_arch (regcache)))
 236     regcache_raw_supply (regcache, I386_LINUX_ORIG_EAX_REGNUM,
 237                          regp + ORIG_EAX);
 238 }
 239
 240 /* Fill register REGNO (if it is a general-purpose register) in
 241    *GREGSETPS with the value in GDB's register array.  If REGNO is -1,
 242    do this for all registers.  */
 243
 244 void
 245 fill_gregset (const struct regcache *regcache,
 246               elf_gregset_t *gregsetp, int regno)
 247 {
 248   elf_greg_t *regp = (elf_greg_t *) gregsetp;
 249   int i;
 250
 251   for (i = 0; i < I386_NUM_GREGS; i++)
 252     if (regno == -1 || regno == i)
 253       regcache_raw_collect (regcache, i, regp + regmap[i]);
 254
 255   if ((regno == -1 || regno == I386_LINUX_ORIG_EAX_REGNUM)
 256       && I386_LINUX_ORIG_EAX_REGNUM
 257            < gdbarch_num_regs (get_regcache_arch (regcache)))
 258     regcache_raw_collect (regcache, I386_LINUX_ORIG_EAX_REGNUM,
 259                           regp + ORIG_EAX);
 260 }
 261
 262 #ifdef HAVE_PTRACE_GETREGS
 263
 264 /* Fetch all general-purpose registers from process/thread TID and
 265    store their values in GDB's register array.  */
 266
 267 static void
 268 fetch_regs (struct regcache *regcache, int tid)
 269 {
 270   elf_gregset_t regs;
 271   elf_gregset_t *regs_p = &regs;
 272
 273   if (ptrace (PTRACE_GETREGS, tid, 0, (int) &regs) < 0)
 274     {
 275       if (errno == EIO)
 276         {
 277           /* The kernel we're running on doesn't support the GETREGS
 278              request.  Reset `have_ptrace_getregs'.  */
 279           have_ptrace_getregs = 0;
 280           return;
 281         }
 282
 283       perror_with_name (_("Couldn't get registers"));
 284     }
 285
 286   supply_gregset (regcache, (const elf_gregset_t *) regs_p);
 287 }
 288
 289 /* Store all valid general-purpose registers in GDB's register array
 290    into the process/thread specified by TID.  */
 291
 292 static void
 293 store_regs (const struct regcache *regcache, int tid, int regno)
 294 {
 295   elf_gregset_t regs;
 296
 297   if (ptrace (PTRACE_GETREGS, tid, 0, (int) &regs) < 0)
 298     perror_with_name (_("Couldn't get registers"));
 299
 300   fill_gregset (regcache, &regs, regno);
 301
 302   if (ptrace (PTRACE_SETREGS, tid, 0, (int) &regs) < 0)
 303     perror_with_name (_("Couldn't write registers"));
 304 }
 305
 306 #else
 307
 308 static void fetch_regs (struct regcache *regcache, int tid) {}
 309 static void store_regs (const struct regcache *regcache, int tid, int regno) {}
 310
 311 #endif
 312 \f
 313
 314 /* Transfering floating-point registers between GDB, inferiors and cores.  */
 315
 316 /* Fill GDB's register array with the floating-point register values in
 317    *FPREGSETP.  */
 318
 319 void
 320 supply_fpregset (struct regcache *regcache, const elf_fpregset_t *fpregsetp)
 321 {
 322   i387_supply_fsave (regcache, -1, fpregsetp);
 323 }
 324
 325 /* Fill register REGNO (if it is a floating-point register) in
 326    *FPREGSETP with the value in GDB's register array.  If REGNO is -1,
 327    do this for all registers.  */
 328
 329 void
 330 fill_fpregset (const struct regcache *regcache,
 331                elf_fpregset_t *fpregsetp, int regno)
 332 {
 333   i387_collect_fsave (regcache, regno, fpregsetp);
 334 }
 335
 336 #ifdef HAVE_PTRACE_GETREGS
 337
 338 /* Fetch all floating-point registers from process/thread TID and store
 339    thier values in GDB's register array.  */
 340
 341 static void
 342 fetch_fpregs (struct regcache *regcache, int tid)
 343 {
 344   elf_fpregset_t fpregs;
 345
 346   if (ptrace (PTRACE_GETFPREGS, tid, 0, (int) &fpregs) < 0)
 347     perror_with_name (_("Couldn't get floating point status"));
 348
 349   supply_fpregset (regcache, (const elf_fpregset_t *) &fpregs);
 350 }
 351
 352 /* Store all valid floating-point registers in GDB's register array
 353    into the process/thread specified by TID.  */
 354
 355 static void
 356 store_fpregs (const struct regcache *regcache, int tid, int regno)
 357 {
 358   elf_fpregset_t fpregs;
 359
 360   if (ptrace (PTRACE_GETFPREGS, tid, 0, (int) &fpregs) < 0)
 361     perror_with_name (_("Couldn't get floating point status"));
 362
 363   fill_fpregset (regcache, &fpregs, regno);
 364
 365   if (ptrace (PTRACE_SETFPREGS, tid, 0, (int) &fpregs) < 0)
 366     perror_with_name (_("Couldn't write floating point status"));
 367 }
 368
 369 #else
 370
 371 static void fetch_fpregs (struct regcache *regcache, int tid) {}
 372 static void store_fpregs (const struct regcache *regcache, int tid, int regno) {}
 373
 374 #endif
 375 \f
 376
 377 /* Transfering floating-point and SSE registers to and from GDB.  */
 378
 379 /* Fetch all registers covered by the PTRACE_GETREGSET request from
 380    process/thread TID and store their values in GDB's register array.
 381    Return non-zero if successful, zero otherwise.  */
 382
 383 static int
 384 fetch_xstateregs (struct regcache *regcache, int tid)
 385 {
 386   char xstateregs[I386_XSTATE_MAX_SIZE];
 387   struct iovec iov;
 388
 389   if (!have_ptrace_getregset)
 390     return 0;
 391
 392   iov.iov_base = xstateregs;
 393   iov.iov_len = sizeof(xstateregs);
 394   if (ptrace (PTRACE_GETREGSET, tid, (unsigned int) NT_X86_XSTATE,
 395               &iov) < 0)
 396     perror_with_name (_("Couldn't read extended state status"));
 397
 398   i387_supply_xsave (regcache, -1, xstateregs);
 399   return 1;
 400 }
 401
 402 /* Store all valid registers in GDB's register array covered by the
 403    PTRACE_SETREGSET request into the process/thread specified by TID.
 404    Return non-zero if successful, zero otherwise.  */
 405
 406 static int
 407 store_xstateregs (const struct regcache *regcache, int tid, int regno)
 408 {
 409   char xstateregs[I386_XSTATE_MAX_SIZE];
 410   struct iovec iov;
 411
 412   if (!have_ptrace_getregset)
 413     return 0;
 414
 415   iov.iov_base = xstateregs;
 416   iov.iov_len = sizeof(xstateregs);
 417   if (ptrace (PTRACE_GETREGSET, tid, (unsigned int) NT_X86_XSTATE,
 418               &iov) < 0)
 419     perror_with_name (_("Couldn't read extended state status"));
 420
 421   i387_collect_xsave (regcache, regno, xstateregs, 0);
 422
 423   if (ptrace (PTRACE_SETREGSET, tid, (unsigned int) NT_X86_XSTATE,
 424               (int) &iov) < 0)
 425     perror_with_name (_("Couldn't write extended state status"));
 426
 427   return 1;
 428 }
 429
 430 #ifdef HAVE_PTRACE_GETFPXREGS
 431
 432 /* Fill GDB's register array with the floating-point and SSE register
 433    values in *FPXREGSETP.  */
 434
 435 void
 436 supply_fpxregset (struct regcache *regcache,
 437                   const elf_fpxregset_t *fpxregsetp)
 438 {
 439   i387_supply_fxsave (regcache, -1, fpxregsetp);
 440 }
 441
 442 /* Fill register REGNO (if it is a floating-point or SSE register) in
 443    *FPXREGSETP with the value in GDB's register array.  If REGNO is
 444    -1, do this for all registers.  */
 445
 446 void
 447 fill_fpxregset (const struct regcache *regcache,
 448                 elf_fpxregset_t *fpxregsetp, int regno)
 449 {
 450   i387_collect_fxsave (regcache, regno, fpxregsetp);
 451 }
 452
 453 /* Fetch all registers covered by the PTRACE_GETFPXREGS request from
 454    process/thread TID and store their values in GDB's register array.
 455    Return non-zero if successful, zero otherwise.  */
 456
 457 static int
 458 fetch_fpxregs (struct regcache *regcache, int tid)
 459 {
 460   elf_fpxregset_t fpxregs;
 461
 462   if (! have_ptrace_getfpxregs)
 463     return 0;
 464
 465   if (ptrace (PTRACE_GETFPXREGS, tid, 0, (int) &fpxregs) < 0)
 466     {
 467       if (errno == EIO)
 468         {
 469           have_ptrace_getfpxregs = 0;
 470           return 0;
 471         }
 472
 473       perror_with_name (_("Couldn't read floating-point and SSE registers"));
 474     }
 475
 476   supply_fpxregset (regcache, (const elf_fpxregset_t *) &fpxregs);
 477   return 1;
 478 }
 479
 480 /* Store all valid registers in GDB's register array covered by the
 481    PTRACE_SETFPXREGS request into the process/thread specified by TID.
 482    Return non-zero if successful, zero otherwise.  */
 483
 484 static int
 485 store_fpxregs (const struct regcache *regcache, int tid, int regno)
 486 {
 487   elf_fpxregset_t fpxregs;
 488
 489   if (! have_ptrace_getfpxregs)
 490     return 0;
 491
 492   if (ptrace (PTRACE_GETFPXREGS, tid, 0, &fpxregs) == -1)
 493     {
 494       if (errno == EIO)
 495         {
 496           have_ptrace_getfpxregs = 0;
 497           return 0;
 498         }
 499
 500       perror_with_name (_("Couldn't read floating-point and SSE registers"));
 501     }
 502
 503   fill_fpxregset (regcache, &fpxregs, regno);
 504
 505   if (ptrace (PTRACE_SETFPXREGS, tid, 0, &fpxregs) == -1)
 506     perror_with_name (_("Couldn't write floating-point and SSE registers"));
 507
 508   return 1;
 509 }
 510
 511 #else
 512
 513 static int fetch_fpxregs (struct regcache *regcache, int tid) { return 0; }
 514 static int store_fpxregs (const struct regcache *regcache, int tid, int regno) { return 0; }
 515
 516 #endif /* HAVE_PTRACE_GETFPXREGS */
 517 \f
 518
 519 /* Transferring arbitrary registers between GDB and inferior.  */
 520
 521 /* Fetch register REGNO from the child process.  If REGNO is -1, do
 522    this for all registers (including the floating point and SSE
 523    registers).  */
 524
 525 static void
 526 i386_linux_fetch_inferior_registers (struct target_ops *ops,
 527                                      struct regcache *regcache, int regno)
 528 {
 529   int tid;
 530
 531   /* Use the old method of peeking around in `struct user' if the
 532      GETREGS request isn't available.  */
 533   if (!have_ptrace_getregs)
 534     {
 535       int i;
 536
 537       for (i = 0; i < gdbarch_num_regs (get_regcache_arch (regcache)); i++)
 538         if (regno == -1 || regno == i)
 539           fetch_register (regcache, i);
 540
 541       return;
 542     }
 543
 544   /* GNU/Linux LWP ID's are process ID's.  */
 545   tid = TIDGET (inferior_ptid);
 546   if (tid == 0)
 547     tid = PIDGET (inferior_ptid); /* Not a threaded program.  */
 548
 549   /* Use the PTRACE_GETFPXREGS request whenever possible, since it
 550      transfers more registers in one system call, and we'll cache the
 551      results.  But remember that fetch_fpxregs can fail, and return
 552      zero.  */
 553   if (regno == -1)
 554     {
 555       fetch_regs (regcache, tid);
 556
 557       /* The call above might reset `have_ptrace_getregs'.  */
 558       if (!have_ptrace_getregs)
 559         {
 560           i386_linux_fetch_inferior_registers (ops, regcache, regno);
 561           return;
 562         }
 563
 564       if (fetch_xstateregs (regcache, tid))
 565         return;
 566       if (fetch_fpxregs (regcache, tid))
 567         return;
 568       fetch_fpregs (regcache, tid);
 569       return;
 570     }
 571
 572   if (GETREGS_SUPPLIES (regno))
 573     {
 574       fetch_regs (regcache, tid);
 575       return;
 576     }
 577
 578   if (GETXSTATEREGS_SUPPLIES (regno))
 579     {
 580       if (fetch_xstateregs (regcache, tid))
 581         return;
 582     }
 583
 584   if (GETFPXREGS_SUPPLIES (regno))
 585     {
 586       if (fetch_fpxregs (regcache, tid))
 587         return;
 588
 589       /* Either our processor or our kernel doesn't support the SSE
 590          registers, so read the FP registers in the traditional way,
 591          and fill the SSE registers with dummy values.  It would be
 592          more graceful to handle differences in the register set using
 593          gdbarch.  Until then, this will at least make things work
 594          plausibly.  */
 595       fetch_fpregs (regcache, tid);
 596       return;
 597     }
 598
 599   internal_error (__FILE__, __LINE__,
 600                   _("Got request for bad register number %d."), regno);
 601 }
 602
 603 /* Store register REGNO back into the child process.  If REGNO is -1,
 604    do this for all registers (including the floating point and SSE
 605    registers).  */
 606 static void
 607 i386_linux_store_inferior_registers (struct target_ops *ops,
 608                                      struct regcache *regcache, int regno)
 609 {
 610   int tid;
 611
 612   /* Use the old method of poking around in `struct user' if the
 613      SETREGS request isn't available.  */
 614   if (!have_ptrace_getregs)
 615     {
 616       int i;
 617
 618       for (i = 0; i < gdbarch_num_regs (get_regcache_arch (regcache)); i++)
 619         if (regno == -1 || regno == i)
 620           store_register (regcache, i);
 621
 622       return;
 623     }
 624
 625   /* GNU/Linux LWP ID's are process ID's.  */
 626   tid = TIDGET (inferior_ptid);
 627   if (tid == 0)
 628     tid = PIDGET (inferior_ptid); /* Not a threaded program.  */
 629
 630   /* Use the PTRACE_SETFPXREGS requests whenever possible, since it
 631      transfers more registers in one system call.  But remember that
 632      store_fpxregs can fail, and return zero.  */
 633   if (regno == -1)
 634     {
 635       store_regs (regcache, tid, regno);
 636       if (store_xstateregs (regcache, tid, regno))
 637         return;
 638       if (store_fpxregs (regcache, tid, regno))
 639         return;
 640       store_fpregs (regcache, tid, regno);
 641       return;
 642     }
 643
 644   if (GETREGS_SUPPLIES (regno))
 645     {
 646       store_regs (regcache, tid, regno);
 647       return;
 648     }
 649
 650   if (GETXSTATEREGS_SUPPLIES (regno))
 651     {
 652       if (store_xstateregs (regcache, tid, regno))
 653         return;
 654     }
 655
 656   if (GETFPXREGS_SUPPLIES (regno))
 657     {
 658       if (store_fpxregs (regcache, tid, regno))
 659         return;
 660
 661       /* Either our processor or our kernel doesn't support the SSE
 662          registers, so just write the FP registers in the traditional
 663          way.  */
 664       store_fpregs (regcache, tid, regno);
 665       return;
 666     }
 667
 668   internal_error (__FILE__, __LINE__,
 669                   _("Got request to store bad register number %d."), regno);
 670 }
 671 \f
 672
 673 /* Support for debug registers.  */
 674
 675 static unsigned long i386_linux_dr[DR_CONTROL + 1];
 676
 677 /* Get debug register REGNUM value from only the one LWP of PTID.  */
 678
 679 static unsigned long
 680 i386_linux_dr_get (ptid_t ptid, int regnum)
 681 {
 682   int tid;
 683   unsigned long value;
 684
 685   tid = TIDGET (ptid);
 686   if (tid == 0)
 687     tid = PIDGET (ptid);
 688
 689   /* FIXME: kettenis/2001-03-27: Calling perror_with_name if the
 690      ptrace call fails breaks debugging remote targets.  The correct
 691      way to fix this is to add the hardware breakpoint and watchpoint
 692      stuff to the target vector.  For now, just return zero if the
 693      ptrace call fails.  */
 694   errno = 0;
 695   value = ptrace (PTRACE_PEEKUSER, tid,
 696                   offsetof (struct user, u_debugreg[regnum]), 0);
 697   if (errno != 0)
 698 #if 0
 699     perror_with_name (_("Couldn't read debug register"));
 700 #else
 701     return 0;
 702 #endif
 703
 704   return value;
 705 }
 706
 707 /* Set debug register REGNUM to VALUE in only the one LWP of PTID.  */
 708
 709 static void
 710 i386_linux_dr_set (ptid_t ptid, int regnum, unsigned long value)
 711 {
 712   int tid;
 713
 714   tid = TIDGET (ptid);
 715   if (tid == 0)
 716     tid = PIDGET (ptid);
 717
 718   errno = 0;
 719   ptrace (PTRACE_POKEUSER, tid,
 720           offsetof (struct user, u_debugreg[regnum]), value);
 721   if (errno != 0)
 722     perror_with_name (_("Couldn't write debug register"));
 723 }
 724
 725 /* Set DR_CONTROL to ADDR in all LWPs of LWP_LIST.  */
 726
 727 static void
 728 i386_linux_dr_set_control (unsigned long control)
 729 {
 730   struct lwp_info *lp;
 731   ptid_t ptid;
 732
 733   i386_linux_dr[DR_CONTROL] = control;
 734   ALL_LWPS (lp, ptid)
 735     i386_linux_dr_set (ptid, DR_CONTROL, control);
 736 }
 737
 738 /* Set address REGNUM (zero based) to ADDR in all LWPs of LWP_LIST.  */
 739
 740 static void
 741 i386_linux_dr_set_addr (int regnum, CORE_ADDR addr)
 742 {
 743   struct lwp_info *lp;
 744   ptid_t ptid;
 745
 746   gdb_assert (regnum >= 0 && regnum <= DR_LASTADDR - DR_FIRSTADDR);
 747
 748   i386_linux_dr[DR_FIRSTADDR + regnum] = addr;
 749   ALL_LWPS (lp, ptid)
 750     i386_linux_dr_set (ptid, DR_FIRSTADDR + regnum, addr);
 751 }
 752
 753 /* Set address REGNUM (zero based) to zero in all LWPs of LWP_LIST.  */
 754
 755 static void
 756 i386_linux_dr_reset_addr (int regnum)
 757 {
 758   i386_linux_dr_set_addr (regnum, 0);
 759 }
 760
 761 /* Get DR_STATUS from only the one LWP of INFERIOR_PTID.  */
 762
 763 static unsigned long
 764 i386_linux_dr_get_status (void)
 765 {
 766   return i386_linux_dr_get (inferior_ptid, DR_STATUS);
 767 }
 768
 769 /* Unset MASK bits in DR_STATUS in all LWPs of LWP_LIST.  */
 770
 771 static void
 772 i386_linux_dr_unset_status (unsigned long mask)
 773 {
 774   struct lwp_info *lp;
 775   ptid_t ptid;
 776
 777   ALL_LWPS (lp, ptid)
 778     {
 779       unsigned long value;
 780
 781       value = i386_linux_dr_get (ptid, DR_STATUS);
 782       value &= ~mask;
 783       i386_linux_dr_set (ptid, DR_STATUS, value);
 784     }
 785 }
 786
 787 static void
 788 i386_linux_new_thread (ptid_t ptid)
 789 {
 790   int i;
 791
 792   for (i = DR_FIRSTADDR; i <= DR_LASTADDR; i++)
 793     i386_linux_dr_set (ptid, i, i386_linux_dr[i]);
 794
 795   i386_linux_dr_set (ptid, DR_CONTROL, i386_linux_dr[DR_CONTROL]);
 796 }
 797 \f
 798
 799 /* Called by libthread_db.  Returns a pointer to the thread local
 800    storage (or its descriptor).  */
 801
 802 ps_err_e
 803 ps_get_thread_area (const struct ps_prochandle *ph,
 804                     lwpid_t lwpid, int idx, void **base)
 805 {
 806   /* NOTE: cagney/2003-08-26: The definition of this buffer is found
 807      in the kernel header <asm-i386/ldt.h>.  It, after padding, is 4 x
 808      4 byte integers in size: `entry_number', `base_addr', `limit',
 809      and a bunch of status bits.
 810
 811      The values returned by this ptrace call should be part of the
 812      regcache buffer, and ps_get_thread_area should channel its
 813      request through the regcache.  That way remote targets could
 814      provide the value using the remote protocol and not this direct
 815      call.
 816
 817      Is this function needed?  I'm guessing that the `base' is the
 818      address of a a descriptor that libthread_db uses to find the
 819      thread local address base that GDB needs.  Perhaps that
 820      descriptor is defined by the ABI.  Anyway, given that
 821      libthread_db calls this function without prompting (gdb
 822      requesting tls base) I guess it needs info in there anyway.  */
 823   unsigned int desc[4];
 824   gdb_assert (sizeof (int) == 4);
 825
 826 #ifndef PTRACE_GET_THREAD_AREA
 827 #define PTRACE_GET_THREAD_AREA 25
 828 #endif
 829
 830   if (ptrace (PTRACE_GET_THREAD_AREA, lwpid,
 831               (void *) idx, (unsigned long) &desc) < 0)
 832     return PS_ERR;
 833
 834   *(int *)base = desc[1];
 835   return PS_OK;
 836 }
 837 \f
 838
 839 /* The instruction for a GNU/Linux system call is:
 840        int $0x80
 841    or 0xcd 0x80.  */
 842
 843 static const unsigned char linux_syscall[] = { 0xcd, 0x80 };
 844
 845 #define LINUX_SYSCALL_LEN (sizeof linux_syscall)
 846
 847 /* The system call number is stored in the %eax register.  */
 848 #define LINUX_SYSCALL_REGNUM I386_EAX_REGNUM
 849
 850 /* We are specifically interested in the sigreturn and rt_sigreturn
 851    system calls.  */
 852
 853 #ifndef SYS_sigreturn
 854 #define SYS_sigreturn           0x77
 855 #endif
 856 #ifndef SYS_rt_sigreturn
 857 #define SYS_rt_sigreturn        0xad
 858 #endif
 859
 860 /* Offset to saved processor flags, from <asm/sigcontext.h>.  */
 861 #define LINUX_SIGCONTEXT_EFLAGS_OFFSET (64)
 862
 863 /* Resume execution of the inferior process.
 864    If STEP is nonzero, single-step it.
 865    If SIGNAL is nonzero, give it that signal.  */
 866
 867 static void
 868 i386_linux_resume (struct target_ops *ops,
 869                    ptid_t ptid, int step, enum target_signal signal)
 870 {
 871   int pid = PIDGET (ptid);
 872
 873   int request;
 874
 875   if (catch_syscall_enabled () > 0)
 876    request = PTRACE_SYSCALL;
 877   else
 878     request = PTRACE_CONT;
 879
 880   if (step)
 881     {
 882       struct regcache *regcache = get_thread_regcache (pid_to_ptid (pid));
 883       struct gdbarch *gdbarch = get_regcache_arch (regcache);
 884       enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
 885       ULONGEST pc;
 886       gdb_byte buf[LINUX_SYSCALL_LEN];
 887
 888       request = PTRACE_SINGLESTEP;
 889
 890       regcache_cooked_read_unsigned (regcache,
 891                                      gdbarch_pc_regnum (gdbarch), &pc);
 892
 893       /* Returning from a signal trampoline is done by calling a
 894          special system call (sigreturn or rt_sigreturn, see
 895          i386-linux-tdep.c for more information).  This system call
 896          restores the registers that were saved when the signal was
 897          raised, including %eflags.  That means that single-stepping
 898          won't work.  Instead, we'll have to modify the signal context
 899          that's about to be restored, and set the trace flag there.  */
 900
 901       /* First check if PC is at a system call.  */
 902       if (target_read_memory (pc, buf, LINUX_SYSCALL_LEN) == 0
 903           && memcmp (buf, linux_syscall, LINUX_SYSCALL_LEN) == 0)
 904         {
 905           ULONGEST syscall;
 906           regcache_cooked_read_unsigned (regcache,
 907                                          LINUX_SYSCALL_REGNUM, &syscall);
 908
 909           /* Then check the system call number.  */
 910           if (syscall == SYS_sigreturn || syscall == SYS_rt_sigreturn)
 911             {
 912               ULONGEST sp, addr;
 913               unsigned long int eflags;
 914
 915               regcache_cooked_read_unsigned (regcache, I386_ESP_REGNUM, &sp);
 916               if (syscall == SYS_rt_sigreturn)
 917                 addr = read_memory_integer (sp + 8, 4, byte_order) + 20;
 918               else
 919                 addr = sp;
 920
 921               /* Set the trace flag in the context that's about to be
 922                  restored.  */
 923               addr += LINUX_SIGCONTEXT_EFLAGS_OFFSET;
 924               read_memory (addr, (gdb_byte *) &eflags, 4);
 925               eflags |= 0x0100;
 926               write_memory (addr, (gdb_byte *) &eflags, 4);
 927             }
 928         }
 929     }
 930
 931   if (ptrace (request, pid, 0, target_signal_to_host (signal)) == -1)
 932     perror_with_name (("ptrace"));
 933 }
 934
 935 static void (*super_post_startup_inferior) (ptid_t ptid);
 936
 937 static void
 938 i386_linux_child_post_startup_inferior (ptid_t ptid)
 939 {
 940   i386_cleanup_dregs ();
 941   super_post_startup_inferior (ptid);
 942 }
 943
 944 /* Get Linux/x86 target description from running target.  */
 945
 946 static const struct target_desc *
 947 i386_linux_read_description (struct target_ops *ops)
 948 {
 949   static uint64_t xcr0;
 950
 951   if (have_ptrace_getregset == -1)
 952     {
 953       int tid;
 954       uint64_t xstateregs[(I386_XSTATE_SSE_SIZE / sizeof (uint64_t))];
 955       struct iovec iov;
 956
 957       /* GNU/Linux LWP ID's are process ID's.  */
 958       tid = TIDGET (inferior_ptid);
 959       if (tid == 0)
 960         tid = PIDGET (inferior_ptid); /* Not a threaded program.  */
 961
 962       iov.iov_base = xstateregs;
 963       iov.iov_len = sizeof (xstateregs);
 964
 965       /* Check if PTRACE_GETREGSET works.  */
 966       if (ptrace (PTRACE_GETREGSET, tid, (unsigned int) NT_X86_XSTATE,
 967                   &iov) < 0)
 968         have_ptrace_getregset = 0;
 969       else
 970         {
 971           have_ptrace_getregset = 1;
 972
 973           /* Get XCR0 from XSAVE extended state.  */
 974           xcr0 = xstateregs[(I386_LINUX_XSAVE_XCR0_OFFSET
 975                              / sizeof (long long))];
 976         }
 977     }
 978
 979   /* Check the native XCR0 only if PTRACE_GETREGSET is available.  */
 980   if (have_ptrace_getregset
 981       && (xcr0 & I386_XSTATE_AVX_MASK) == I386_XSTATE_AVX_MASK)
 982     return tdesc_i386_avx_linux;
 983   else
 984     return tdesc_i386_linux;
 985 }
 986
 987 void
 988 _initialize_i386_linux_nat (void)
 989 {
 990   struct target_ops *t;
 991
 992   /* Fill in the generic GNU/Linux methods.  */
 993   t = linux_target ();
 994
 995   i386_use_watchpoints (t);
 996
 997   i386_dr_low.set_control = i386_linux_dr_set_control;
 998   i386_dr_low.set_addr = i386_linux_dr_set_addr;
 999   i386_dr_low.reset_addr = i386_linux_dr_reset_addr;
1000   i386_dr_low.get_status = i386_linux_dr_get_status;
1001   i386_dr_low.unset_status = i386_linux_dr_unset_status;
1002   i386_set_debug_register_length (4);
1003
1004   /* Override the default ptrace resume method.  */
1005   t->to_resume = i386_linux_resume;
1006
1007   /* Override the GNU/Linux inferior startup hook.  */
1008   super_post_startup_inferior = t->to_post_startup_inferior;
1009   t->to_post_startup_inferior = i386_linux_child_post_startup_inferior;
1010
1011   /* Add our register access methods.  */
1012   t->to_fetch_registers = i386_linux_fetch_inferior_registers;
1013   t->to_store_registers = i386_linux_store_inferior_registers;
1014
1015   t->to_read_description = i386_linux_read_description;
1016
1017   /* Register the target.  */
1018   linux_nat_add_target (t);
1019   linux_nat_set_new_thread (t, i386_linux_new_thread);
1020 }