gdb/i386-linux-nat.c

   1 /* Native-dependent code for GNU/Linux i386.
   2
   3    Copyright (C) 1999-2014 Free Software Foundation, Inc.
   4
   5    This file is part of GDB.
   6
   7    This program is free software; you can redistribute it and/or modify
   8    it under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 3 of the License, or
  10    (at your option) any later version.
  11
  12    This program is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15    GNU General Public License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  19
  20 #include "defs.h"
  21 #include "i386-nat.h"
  22 #include "inferior.h"
  23 #include "gdbcore.h"
  24 #include "regcache.h"
  25 #include "regset.h"
  26 #include "target.h"
  27 #include "linux-nat.h"
  28 #include "linux-btrace.h"
  29 #include "btrace.h"
  30
  31 #include "gdb_assert.h"
  32 #include <string.h>
  33 #include "elf/common.h"
  34 #include <sys/uio.h>
  35 #include <sys/ptrace.h>
  36 #include <sys/user.h>
  37 #include <sys/procfs.h>
  38
  39 #ifdef HAVE_SYS_REG_H
  40 #include <sys/reg.h>
  41 #endif
  42
  43 #ifndef ORIG_EAX
  44 #define ORIG_EAX -1
  45 #endif
  46
  47 #ifdef HAVE_SYS_DEBUGREG_H
  48 #include <sys/debugreg.h>
  49 #endif
  50
  51 /* Prototypes for supply_gregset etc.  */
  52 #include "gregset.h"
  53
  54 #include "i387-tdep.h"
  55 #include "i386-tdep.h"
  56 #include "i386-linux-tdep.h"
  57
  58 /* Defines ps_err_e, struct ps_prochandle.  */
  59 #include "gdb_proc_service.h"
  60
  61 #include "i386-xstate.h"
  62
  63 #ifndef PTRACE_GETREGSET
  64 #define PTRACE_GETREGSET        0x4204
  65 #endif
  66
  67 #ifndef PTRACE_SETREGSET
  68 #define PTRACE_SETREGSET        0x4205
  69 #endif
  70
  71 /* Per-thread arch-specific data we want to keep.  */
  72
  73 struct arch_lwp_info
  74 {
  75   /* Non-zero if our copy differs from what's recorded in the thread.  */
  76   int debug_registers_changed;
  77 };
  78
  79 /* Does the current host support PTRACE_GETREGSET?  */
  80 static int have_ptrace_getregset = -1;
  81 \f
  82
  83 /* The register sets used in GNU/Linux ELF core-dumps are identical to
  84    the register sets in `struct user' that is used for a.out
  85    core-dumps, and is also used by `ptrace'.  The corresponding types
  86    are `elf_gregset_t' for the general-purpose registers (with
  87    `elf_greg_t' the type of a single GP register) and `elf_fpregset_t'
  88    for the floating-point registers.
  89
  90    Those types used to be available under the names `gregset_t' and
  91    `fpregset_t' too, and this file used those names in the past.  But
  92    those names are now used for the register sets used in the
  93    `mcontext_t' type, and have a different size and layout.  */
  94
  95 /* Which ptrace request retrieves which registers?
  96    These apply to the corresponding SET requests as well.  */
  97
  98 #define GETREGS_SUPPLIES(regno) \
  99   ((0 <= (regno) && (regno) <= 15) || (regno) == I386_LINUX_ORIG_EAX_REGNUM)
 100
 101 #define GETFPXREGS_SUPPLIES(regno) \
 102   (I386_ST0_REGNUM <= (regno) && (regno) < I386_SSE_NUM_REGS)
 103
 104 #define GETXSTATEREGS_SUPPLIES(regno) \
 105   (I386_ST0_REGNUM <= (regno) && (regno) < I386_MPX_NUM_REGS)
 106
 107 /* Does the current host support the GETREGS request?  */
 108 int have_ptrace_getregs =
 109 #ifdef HAVE_PTRACE_GETREGS
 110   1
 111 #else
 112   0
 113 #endif
 114 ;
 115
 116 /* Does the current host support the GETFPXREGS request?  The header
 117    file may or may not define it, and even if it is defined, the
 118    kernel will return EIO if it's running on a pre-SSE processor.
 119
 120    My instinct is to attach this to some architecture- or
 121    target-specific data structure, but really, a particular GDB
 122    process can only run on top of one kernel at a time.  So it's okay
 123    for this to be a simple variable.  */
 124 int have_ptrace_getfpxregs =
 125 #ifdef HAVE_PTRACE_GETFPXREGS
 126   -1
 127 #else
 128   0
 129 #endif
 130 ;
 131 \f
 132
 133 /* Accessing registers through the U area, one at a time.  */
 134
 135 /* Fetch one register.  */
 136
 137 static void
 138 fetch_register (struct regcache *regcache, int regno)
 139 {
 140   int tid;
 141   int val;
 142
 143   gdb_assert (!have_ptrace_getregs);
 144   if (i386_linux_gregset_reg_offset[regno] == -1)
 145     {
 146       regcache_raw_supply (regcache, regno, NULL);
 147       return;
 148     }
 149
 150   /* GNU/Linux LWP ID's are process ID's.  */
 151   tid = ptid_get_lwp (inferior_ptid);
 152   if (tid == 0)
 153     tid = ptid_get_pid (inferior_ptid); /* Not a threaded program.  */
 154
 155   errno = 0;
 156   val = ptrace (PTRACE_PEEKUSER, tid,
 157                 i386_linux_gregset_reg_offset[regno], 0);
 158   if (errno != 0)
 159     error (_("Couldn't read register %s (#%d): %s."),
 160            gdbarch_register_name (get_regcache_arch (regcache), regno),
 161            regno, safe_strerror (errno));
 162
 163   regcache_raw_supply (regcache, regno, &val);
 164 }
 165
 166 /* Store one register.  */
 167
 168 static void
 169 store_register (const struct regcache *regcache, int regno)
 170 {
 171   int tid;
 172   int val;
 173
 174   gdb_assert (!have_ptrace_getregs);
 175   if (i386_linux_gregset_reg_offset[regno] == -1)
 176     return;
 177
 178   /* GNU/Linux LWP ID's are process ID's.  */
 179   tid = ptid_get_lwp (inferior_ptid);
 180   if (tid == 0)
 181     tid = ptid_get_pid (inferior_ptid); /* Not a threaded program.  */
 182
 183   errno = 0;
 184   regcache_raw_collect (regcache, regno, &val);
 185   ptrace (PTRACE_POKEUSER, tid,
 186           i386_linux_gregset_reg_offset[regno], val);
 187   if (errno != 0)
 188     error (_("Couldn't write register %s (#%d): %s."),
 189            gdbarch_register_name (get_regcache_arch (regcache), regno),
 190            regno, safe_strerror (errno));
 191 }
 192 \f
 193
 194 /* Transfering the general-purpose registers between GDB, inferiors
 195    and core files.  */
 196
 197 /* Fill GDB's register array with the general-purpose register values
 198    in *GREGSETP.  */
 199
 200 void
 201 supply_gregset (struct regcache *regcache, const elf_gregset_t *gregsetp)
 202 {
 203   const gdb_byte *regp = (const gdb_byte *) gregsetp;
 204   int i;
 205
 206   for (i = 0; i < I386_NUM_GREGS; i++)
 207     regcache_raw_supply (regcache, i,
 208                          regp + i386_linux_gregset_reg_offset[i]);
 209
 210   if (I386_LINUX_ORIG_EAX_REGNUM
 211         < gdbarch_num_regs (get_regcache_arch (regcache)))
 212     regcache_raw_supply (regcache, I386_LINUX_ORIG_EAX_REGNUM, regp
 213                          + i386_linux_gregset_reg_offset[I386_LINUX_ORIG_EAX_REGNUM]);
 214 }
 215
 216 /* Fill register REGNO (if it is a general-purpose register) in
 217    *GREGSETPS with the value in GDB's register array.  If REGNO is -1,
 218    do this for all registers.  */
 219
 220 void
 221 fill_gregset (const struct regcache *regcache,
 222               elf_gregset_t *gregsetp, int regno)
 223 {
 224   gdb_byte *regp = (gdb_byte *) gregsetp;
 225   int i;
 226
 227   for (i = 0; i < I386_NUM_GREGS; i++)
 228     if (regno == -1 || regno == i)
 229       regcache_raw_collect (regcache, i,
 230                             regp + i386_linux_gregset_reg_offset[i]);
 231
 232   if ((regno == -1 || regno == I386_LINUX_ORIG_EAX_REGNUM)
 233       && I386_LINUX_ORIG_EAX_REGNUM
 234            < gdbarch_num_regs (get_regcache_arch (regcache)))
 235     regcache_raw_collect (regcache, I386_LINUX_ORIG_EAX_REGNUM, regp
 236                           + i386_linux_gregset_reg_offset[I386_LINUX_ORIG_EAX_REGNUM]);
 237 }
 238
 239 #ifdef HAVE_PTRACE_GETREGS
 240
 241 /* Fetch all general-purpose registers from process/thread TID and
 242    store their values in GDB's register array.  */
 243
 244 static void
 245 fetch_regs (struct regcache *regcache, int tid)
 246 {
 247   elf_gregset_t regs;
 248   elf_gregset_t *regs_p = &regs;
 249
 250   if (ptrace (PTRACE_GETREGS, tid, 0, (int) &regs) < 0)
 251     {
 252       if (errno == EIO)
 253         {
 254           /* The kernel we're running on doesn't support the GETREGS
 255              request.  Reset `have_ptrace_getregs'.  */
 256           have_ptrace_getregs = 0;
 257           return;
 258         }
 259
 260       perror_with_name (_("Couldn't get registers"));
 261     }
 262
 263   supply_gregset (regcache, (const elf_gregset_t *) regs_p);
 264 }
 265
 266 /* Store all valid general-purpose registers in GDB's register array
 267    into the process/thread specified by TID.  */
 268
 269 static void
 270 store_regs (const struct regcache *regcache, int tid, int regno)
 271 {
 272   elf_gregset_t regs;
 273
 274   if (ptrace (PTRACE_GETREGS, tid, 0, (int) &regs) < 0)
 275     perror_with_name (_("Couldn't get registers"));
 276
 277   fill_gregset (regcache, &regs, regno);
 278
 279   if (ptrace (PTRACE_SETREGS, tid, 0, (int) &regs) < 0)
 280     perror_with_name (_("Couldn't write registers"));
 281 }
 282
 283 #else
 284
 285 static void fetch_regs (struct regcache *regcache, int tid) {}
 286 static void store_regs (const struct regcache *regcache, int tid, int regno) {}
 287
 288 #endif
 289 \f
 290
 291 /* Transfering floating-point registers between GDB, inferiors and cores.  */
 292
 293 /* Fill GDB's register array with the floating-point register values in
 294    *FPREGSETP.  */
 295
 296 void
 297 supply_fpregset (struct regcache *regcache, const elf_fpregset_t *fpregsetp)
 298 {
 299   i387_supply_fsave (regcache, -1, fpregsetp);
 300 }
 301
 302 /* Fill register REGNO (if it is a floating-point register) in
 303    *FPREGSETP with the value in GDB's register array.  If REGNO is -1,
 304    do this for all registers.  */
 305
 306 void
 307 fill_fpregset (const struct regcache *regcache,
 308                elf_fpregset_t *fpregsetp, int regno)
 309 {
 310   i387_collect_fsave (regcache, regno, fpregsetp);
 311 }
 312
 313 #ifdef HAVE_PTRACE_GETREGS
 314
 315 /* Fetch all floating-point registers from process/thread TID and store
 316    thier values in GDB's register array.  */
 317
 318 static void
 319 fetch_fpregs (struct regcache *regcache, int tid)
 320 {
 321   elf_fpregset_t fpregs;
 322
 323   if (ptrace (PTRACE_GETFPREGS, tid, 0, (int) &fpregs) < 0)
 324     perror_with_name (_("Couldn't get floating point status"));
 325
 326   supply_fpregset (regcache, (const elf_fpregset_t *) &fpregs);
 327 }
 328
 329 /* Store all valid floating-point registers in GDB's register array
 330    into the process/thread specified by TID.  */
 331
 332 static void
 333 store_fpregs (const struct regcache *regcache, int tid, int regno)
 334 {
 335   elf_fpregset_t fpregs;
 336
 337   if (ptrace (PTRACE_GETFPREGS, tid, 0, (int) &fpregs) < 0)
 338     perror_with_name (_("Couldn't get floating point status"));
 339
 340   fill_fpregset (regcache, &fpregs, regno);
 341
 342   if (ptrace (PTRACE_SETFPREGS, tid, 0, (int) &fpregs) < 0)
 343     perror_with_name (_("Couldn't write floating point status"));
 344 }
 345
 346 #else
 347
 348 static void
 349 fetch_fpregs (struct regcache *regcache, int tid)
 350 {
 351 }
 352
 353 static void
 354 store_fpregs (const struct regcache *regcache, int tid, int regno)
 355 {
 356 }
 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
 477 fetch_fpxregs (struct regcache *regcache, int tid)
 478 {
 479   return 0;
 480 }
 481
 482 static int
 483 store_fpxregs (const struct regcache *regcache, int tid, int regno)
 484 {
 485   return 0;
 486 }
 487
 488 #endif /* HAVE_PTRACE_GETFPXREGS */
 489 \f
 490
 491 /* Transferring arbitrary registers between GDB and inferior.  */
 492
 493 /* Fetch register REGNO from the child process.  If REGNO is -1, do
 494    this for all registers (including the floating point and SSE
 495    registers).  */
 496
 497 static void
 498 i386_linux_fetch_inferior_registers (struct target_ops *ops,
 499                                      struct regcache *regcache, int regno)
 500 {
 501   int tid;
 502
 503   /* Use the old method of peeking around in `struct user' if the
 504      GETREGS request isn't available.  */
 505   if (!have_ptrace_getregs)
 506     {
 507       int i;
 508
 509       for (i = 0; i < gdbarch_num_regs (get_regcache_arch (regcache)); i++)
 510         if (regno == -1 || regno == i)
 511           fetch_register (regcache, i);
 512
 513       return;
 514     }
 515
 516   /* GNU/Linux LWP ID's are process ID's.  */
 517   tid = ptid_get_lwp (inferior_ptid);
 518   if (tid == 0)
 519     tid = ptid_get_pid (inferior_ptid); /* Not a threaded program.  */
 520
 521   /* Use the PTRACE_GETFPXREGS request whenever possible, since it
 522      transfers more registers in one system call, and we'll cache the
 523      results.  But remember that fetch_fpxregs can fail, and return
 524      zero.  */
 525   if (regno == -1)
 526     {
 527       fetch_regs (regcache, tid);
 528
 529       /* The call above might reset `have_ptrace_getregs'.  */
 530       if (!have_ptrace_getregs)
 531         {
 532           i386_linux_fetch_inferior_registers (ops, regcache, regno);
 533           return;
 534         }
 535
 536       if (fetch_xstateregs (regcache, tid))
 537         return;
 538       if (fetch_fpxregs (regcache, tid))
 539         return;
 540       fetch_fpregs (regcache, tid);
 541       return;
 542     }
 543
 544   if (GETREGS_SUPPLIES (regno))
 545     {
 546       fetch_regs (regcache, tid);
 547       return;
 548     }
 549
 550   if (GETXSTATEREGS_SUPPLIES (regno))
 551     {
 552       if (fetch_xstateregs (regcache, tid))
 553         return;
 554     }
 555
 556   if (GETFPXREGS_SUPPLIES (regno))
 557     {
 558       if (fetch_fpxregs (regcache, tid))
 559         return;
 560
 561       /* Either our processor or our kernel doesn't support the SSE
 562          registers, so read the FP registers in the traditional way,
 563          and fill the SSE registers with dummy values.  It would be
 564          more graceful to handle differences in the register set using
 565          gdbarch.  Until then, this will at least make things work
 566          plausibly.  */
 567       fetch_fpregs (regcache, tid);
 568       return;
 569     }
 570
 571   internal_error (__FILE__, __LINE__,
 572                   _("Got request for bad register number %d."), regno);
 573 }
 574
 575 /* Store register REGNO back into the child process.  If REGNO is -1,
 576    do this for all registers (including the floating point and SSE
 577    registers).  */
 578 static void
 579 i386_linux_store_inferior_registers (struct target_ops *ops,
 580                                      struct regcache *regcache, int regno)
 581 {
 582   int tid;
 583
 584   /* Use the old method of poking around in `struct user' if the
 585      SETREGS request isn't available.  */
 586   if (!have_ptrace_getregs)
 587     {
 588       int i;
 589
 590       for (i = 0; i < gdbarch_num_regs (get_regcache_arch (regcache)); i++)
 591         if (regno == -1 || regno == i)
 592           store_register (regcache, i);
 593
 594       return;
 595     }
 596
 597   /* GNU/Linux LWP ID's are process ID's.  */
 598   tid = ptid_get_lwp (inferior_ptid);
 599   if (tid == 0)
 600     tid = ptid_get_pid (inferior_ptid); /* Not a threaded program.  */
 601
 602   /* Use the PTRACE_SETFPXREGS requests whenever possible, since it
 603      transfers more registers in one system call.  But remember that
 604      store_fpxregs can fail, and return zero.  */
 605   if (regno == -1)
 606     {
 607       store_regs (regcache, tid, regno);
 608       if (store_xstateregs (regcache, tid, regno))
 609         return;
 610       if (store_fpxregs (regcache, tid, regno))
 611         return;
 612       store_fpregs (regcache, tid, regno);
 613       return;
 614     }
 615
 616   if (GETREGS_SUPPLIES (regno))
 617     {
 618       store_regs (regcache, tid, regno);
 619       return;
 620     }
 621
 622   if (GETXSTATEREGS_SUPPLIES (regno))
 623     {
 624       if (store_xstateregs (regcache, tid, regno))
 625         return;
 626     }
 627
 628   if (GETFPXREGS_SUPPLIES (regno))
 629     {
 630       if (store_fpxregs (regcache, tid, regno))
 631         return;
 632
 633       /* Either our processor or our kernel doesn't support the SSE
 634          registers, so just write the FP registers in the traditional
 635          way.  */
 636       store_fpregs (regcache, tid, regno);
 637       return;
 638     }
 639
 640   internal_error (__FILE__, __LINE__,
 641                   _("Got request to store bad register number %d."), regno);
 642 }
 643 \f
 644
 645 /* Support for debug registers.  */
 646
 647 /* Get debug register REGNUM value from only the one LWP of PTID.  */
 648
 649 static unsigned long
 650 i386_linux_dr_get (ptid_t ptid, int regnum)
 651 {
 652   int tid;
 653   unsigned long value;
 654
 655   tid = ptid_get_lwp (ptid);
 656   if (tid == 0)
 657     tid = ptid_get_pid (ptid);
 658
 659   errno = 0;
 660   value = ptrace (PTRACE_PEEKUSER, tid,
 661                   offsetof (struct user, u_debugreg[regnum]), 0);
 662   if (errno != 0)
 663     perror_with_name (_("Couldn't read debug register"));
 664
 665   return value;
 666 }
 667
 668 /* Set debug register REGNUM to VALUE in only the one LWP of PTID.  */
 669
 670 static void
 671 i386_linux_dr_set (ptid_t ptid, int regnum, unsigned long value)
 672 {
 673   int tid;
 674
 675   tid = ptid_get_lwp (ptid);
 676   if (tid == 0)
 677     tid = ptid_get_pid (ptid);
 678
 679   errno = 0;
 680   ptrace (PTRACE_POKEUSER, tid,
 681           offsetof (struct user, u_debugreg[regnum]), value);
 682   if (errno != 0)
 683     perror_with_name (_("Couldn't write debug register"));
 684 }
 685
 686 /* Return the inferior's debug register REGNUM.  */
 687
 688 static CORE_ADDR
 689 i386_linux_dr_get_addr (int regnum)
 690 {
 691   /* DR6 and DR7 are retrieved with some other way.  */
 692   gdb_assert (DR_FIRSTADDR <= regnum && regnum <= DR_LASTADDR);
 693
 694   return i386_linux_dr_get (inferior_ptid, regnum);
 695 }
 696
 697 /* Return the inferior's DR7 debug control register.  */
 698
 699 static unsigned long
 700 i386_linux_dr_get_control (void)
 701 {
 702   return i386_linux_dr_get (inferior_ptid, DR_CONTROL);
 703 }
 704
 705 /* Get DR_STATUS from only the one LWP of INFERIOR_PTID.  */
 706
 707 static unsigned long
 708 i386_linux_dr_get_status (void)
 709 {
 710   return i386_linux_dr_get (inferior_ptid, DR_STATUS);
 711 }
 712
 713 /* Callback for iterate_over_lwps.  Update the debug registers of
 714    LWP.  */
 715
 716 static int
 717 update_debug_registers_callback (struct lwp_info *lwp, void *arg)
 718 {
 719   if (lwp->arch_private == NULL)
 720     lwp->arch_private = XCNEW (struct arch_lwp_info);
 721
 722   /* The actual update is done later just before resuming the lwp, we
 723      just mark that the registers need updating.  */
 724   lwp->arch_private->debug_registers_changed = 1;
 725
 726   /* If the lwp isn't stopped, force it to momentarily pause, so we
 727      can update its debug registers.  */
 728   if (!lwp->stopped)
 729     linux_stop_lwp (lwp);
 730
 731   /* Continue the iteration.  */
 732   return 0;
 733 }
 734
 735 /* Set DR_CONTROL to ADDR in all LWPs of the current inferior.  */
 736
 737 static void
 738 i386_linux_dr_set_control (unsigned long control)
 739 {
 740   ptid_t pid_ptid = pid_to_ptid (ptid_get_pid (inferior_ptid));
 741
 742   iterate_over_lwps (pid_ptid, update_debug_registers_callback, NULL);
 743 }
 744
 745 /* Set address REGNUM (zero based) to ADDR in all LWPs of the current
 746    inferior.  */
 747
 748 static void
 749 i386_linux_dr_set_addr (int regnum, CORE_ADDR addr)
 750 {
 751   ptid_t pid_ptid = pid_to_ptid (ptid_get_pid (inferior_ptid));
 752
 753   gdb_assert (regnum >= 0 && regnum <= DR_LASTADDR - DR_FIRSTADDR);
 754
 755   iterate_over_lwps (pid_ptid, update_debug_registers_callback, NULL);
 756 }
 757
 758 /* Called when resuming a thread.
 759    If the debug regs have changed, update the thread's copies.  */
 760
 761 static void
 762 i386_linux_prepare_to_resume (struct lwp_info *lwp)
 763 {
 764   int clear_status = 0;
 765
 766   /* NULL means this is the main thread still going through the shell,
 767      or, no watchpoint has been set yet.  In that case, there's
 768      nothing to do.  */
 769   if (lwp->arch_private == NULL)
 770     return;
 771
 772   if (lwp->arch_private->debug_registers_changed)
 773     {
 774       struct i386_debug_reg_state *state
 775         = i386_debug_reg_state (ptid_get_pid (lwp->ptid));
 776       int i;
 777
 778       /* See amd64_linux_prepare_to_resume for Linux kernel note on
 779          i386_linux_dr_set calls ordering.  */
 780
 781       for (i = DR_FIRSTADDR; i <= DR_LASTADDR; i++)
 782         if (state->dr_ref_count[i] > 0)
 783           {
 784             i386_linux_dr_set (lwp->ptid, i, state->dr_mirror[i]);
 785
 786             /* If we're setting a watchpoint, any change the inferior
 787                had done itself to the debug registers needs to be
 788                discarded, otherwise, i386_stopped_data_address can get
 789                confused.  */
 790             clear_status = 1;
 791           }
 792
 793       i386_linux_dr_set (lwp->ptid, DR_CONTROL, state->dr_control_mirror);
 794
 795       lwp->arch_private->debug_registers_changed = 0;
 796     }
 797
 798   if (clear_status || lwp->stopped_by_watchpoint)
 799     i386_linux_dr_set (lwp->ptid, DR_STATUS, 0);
 800 }
 801
 802 static void
 803 i386_linux_new_thread (struct lwp_info *lp)
 804 {
 805   struct arch_lwp_info *info = XCNEW (struct arch_lwp_info);
 806
 807   info->debug_registers_changed = 1;
 808
 809   lp->arch_private = info;
 810 }
 811
 812 /* linux_nat_new_fork hook.   */
 813
 814 static void
 815 i386_linux_new_fork (struct lwp_info *parent, pid_t child_pid)
 816 {
 817   pid_t parent_pid;
 818   struct i386_debug_reg_state *parent_state;
 819   struct i386_debug_reg_state *child_state;
 820
 821   /* NULL means no watchpoint has ever been set in the parent.  In
 822      that case, there's nothing to do.  */
 823   if (parent->arch_private == NULL)
 824     return;
 825
 826   /* Linux kernel before 2.6.33 commit
 827      72f674d203cd230426437cdcf7dd6f681dad8b0d
 828      will inherit hardware debug registers from parent
 829      on fork/vfork/clone.  Newer Linux kernels create such tasks with
 830      zeroed debug registers.
 831
 832      GDB core assumes the child inherits the watchpoints/hw
 833      breakpoints of the parent, and will remove them all from the
 834      forked off process.  Copy the debug registers mirrors into the
 835      new process so that all breakpoints and watchpoints can be
 836      removed together.  The debug registers mirror will become zeroed
 837      in the end before detaching the forked off process, thus making
 838      this compatible with older Linux kernels too.  */
 839
 840   parent_pid = ptid_get_pid (parent->ptid);
 841   parent_state = i386_debug_reg_state (parent_pid);
 842   child_state = i386_debug_reg_state (child_pid);
 843   *child_state = *parent_state;
 844 }
 845
 846 \f
 847
 848 /* Called by libthread_db.  Returns a pointer to the thread local
 849    storage (or its descriptor).  */
 850
 851 ps_err_e
 852 ps_get_thread_area (const struct ps_prochandle *ph,
 853                     lwpid_t lwpid, int idx, void **base)
 854 {
 855   /* NOTE: cagney/2003-08-26: The definition of this buffer is found
 856      in the kernel header <asm-i386/ldt.h>.  It, after padding, is 4 x
 857      4 byte integers in size: `entry_number', `base_addr', `limit',
 858      and a bunch of status bits.
 859
 860      The values returned by this ptrace call should be part of the
 861      regcache buffer, and ps_get_thread_area should channel its
 862      request through the regcache.  That way remote targets could
 863      provide the value using the remote protocol and not this direct
 864      call.
 865
 866      Is this function needed?  I'm guessing that the `base' is the
 867      address of a descriptor that libthread_db uses to find the
 868      thread local address base that GDB needs.  Perhaps that
 869      descriptor is defined by the ABI.  Anyway, given that
 870      libthread_db calls this function without prompting (gdb
 871      requesting tls base) I guess it needs info in there anyway.  */
 872   unsigned int desc[4];
 873   gdb_assert (sizeof (int) == 4);
 874
 875 #ifndef PTRACE_GET_THREAD_AREA
 876 #define PTRACE_GET_THREAD_AREA 25
 877 #endif
 878
 879   if (ptrace (PTRACE_GET_THREAD_AREA, lwpid,
 880               (void *) idx, (unsigned long) &desc) < 0)
 881     return PS_ERR;
 882
 883   *(int *)base = desc[1];
 884   return PS_OK;
 885 }
 886 \f
 887
 888 /* The instruction for a GNU/Linux system call is:
 889        int $0x80
 890    or 0xcd 0x80.  */
 891
 892 static const unsigned char linux_syscall[] = { 0xcd, 0x80 };
 893
 894 #define LINUX_SYSCALL_LEN (sizeof linux_syscall)
 895
 896 /* The system call number is stored in the %eax register.  */
 897 #define LINUX_SYSCALL_REGNUM I386_EAX_REGNUM
 898
 899 /* We are specifically interested in the sigreturn and rt_sigreturn
 900    system calls.  */
 901
 902 #ifndef SYS_sigreturn
 903 #define SYS_sigreturn           0x77
 904 #endif
 905 #ifndef SYS_rt_sigreturn
 906 #define SYS_rt_sigreturn        0xad
 907 #endif
 908
 909 /* Offset to saved processor flags, from <asm/sigcontext.h>.  */
 910 #define LINUX_SIGCONTEXT_EFLAGS_OFFSET (64)
 911
 912 /* Resume execution of the inferior process.
 913    If STEP is nonzero, single-step it.
 914    If SIGNAL is nonzero, give it that signal.  */
 915
 916 static void
 917 i386_linux_resume (struct target_ops *ops,
 918                    ptid_t ptid, int step, enum gdb_signal signal)
 919 {
 920   int pid = ptid_get_pid (ptid);
 921
 922   int request;
 923
 924   if (catch_syscall_enabled () > 0)
 925    request = PTRACE_SYSCALL;
 926   else
 927     request = PTRACE_CONT;
 928
 929   if (step)
 930     {
 931       struct regcache *regcache = get_thread_regcache (pid_to_ptid (pid));
 932       struct gdbarch *gdbarch = get_regcache_arch (regcache);
 933       enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
 934       ULONGEST pc;
 935       gdb_byte buf[LINUX_SYSCALL_LEN];
 936
 937       request = PTRACE_SINGLESTEP;
 938
 939       regcache_cooked_read_unsigned (regcache,
 940                                      gdbarch_pc_regnum (gdbarch), &pc);
 941
 942       /* Returning from a signal trampoline is done by calling a
 943          special system call (sigreturn or rt_sigreturn, see
 944          i386-linux-tdep.c for more information).  This system call
 945          restores the registers that were saved when the signal was
 946          raised, including %eflags.  That means that single-stepping
 947          won't work.  Instead, we'll have to modify the signal context
 948          that's about to be restored, and set the trace flag there.  */
 949
 950       /* First check if PC is at a system call.  */
 951       if (target_read_memory (pc, buf, LINUX_SYSCALL_LEN) == 0
 952           && memcmp (buf, linux_syscall, LINUX_SYSCALL_LEN) == 0)
 953         {
 954           ULONGEST syscall;
 955           regcache_cooked_read_unsigned (regcache,
 956                                          LINUX_SYSCALL_REGNUM, &syscall);
 957
 958           /* Then check the system call number.  */
 959           if (syscall == SYS_sigreturn || syscall == SYS_rt_sigreturn)
 960             {
 961               ULONGEST sp, addr;
 962               unsigned long int eflags;
 963
 964               regcache_cooked_read_unsigned (regcache, I386_ESP_REGNUM, &sp);
 965               if (syscall == SYS_rt_sigreturn)
 966                 addr = read_memory_unsigned_integer (sp + 8, 4, byte_order)
 967                   + 20;
 968               else
 969                 addr = sp;
 970
 971               /* Set the trace flag in the context that's about to be
 972                  restored.  */
 973               addr += LINUX_SIGCONTEXT_EFLAGS_OFFSET;
 974               read_memory (addr, (gdb_byte *) &eflags, 4);
 975               eflags |= 0x0100;
 976               write_memory (addr, (gdb_byte *) &eflags, 4);
 977             }
 978         }
 979     }
 980
 981   if (ptrace (request, pid, 0, gdb_signal_to_host (signal)) == -1)
 982     perror_with_name (("ptrace"));
 983 }
 984
 985 static void (*super_post_startup_inferior) (ptid_t ptid);
 986
 987 static void
 988 i386_linux_child_post_startup_inferior (ptid_t ptid)
 989 {
 990   i386_cleanup_dregs ();
 991   super_post_startup_inferior (ptid);
 992 }
 993
 994 /* Get Linux/x86 target description from running target.  */
 995
 996 static const struct target_desc *
 997 i386_linux_read_description (struct target_ops *ops)
 998 {
 999   int tid;
1000   static uint64_t xcr0;
1001
1002   /* GNU/Linux LWP ID's are process ID's.  */
1003   tid = ptid_get_lwp (inferior_ptid);
1004   if (tid == 0)
1005     tid = ptid_get_pid (inferior_ptid); /* Not a threaded program.  */
1006
1007 #ifdef HAVE_PTRACE_GETFPXREGS
1008   if (have_ptrace_getfpxregs == -1)
1009     {
1010       elf_fpxregset_t fpxregs;
1011
1012       if (ptrace (PTRACE_GETFPXREGS, tid, 0, (int) &fpxregs) < 0)
1013         {
1014           have_ptrace_getfpxregs = 0;
1015           have_ptrace_getregset = 0;
1016           return tdesc_i386_mmx_linux;
1017         }
1018     }
1019 #endif
1020
1021   if (have_ptrace_getregset == -1)
1022     {
1023       uint64_t xstateregs[(I386_XSTATE_SSE_SIZE / sizeof (uint64_t))];
1024       struct iovec iov;
1025
1026       iov.iov_base = xstateregs;
1027       iov.iov_len = sizeof (xstateregs);
1028
1029       /* Check if PTRACE_GETREGSET works.  */
1030       if (ptrace (PTRACE_GETREGSET, tid, (unsigned int) NT_X86_XSTATE,
1031                   &iov) < 0)
1032         have_ptrace_getregset = 0;
1033       else
1034         {
1035           have_ptrace_getregset = 1;
1036
1037           /* Get XCR0 from XSAVE extended state.  */
1038           xcr0 = xstateregs[(I386_LINUX_XSAVE_XCR0_OFFSET
1039                              / sizeof (long long))];
1040         }
1041     }
1042
1043   /* Check the native XCR0 only if PTRACE_GETREGSET is available.  */
1044   if (have_ptrace_getregset)
1045     {
1046       switch ((xcr0 & I386_XSTATE_ALL_MASK))
1047         {
1048         case I386_XSTATE_MPX_MASK:
1049           return tdesc_i386_mpx_linux;
1050         case I386_XSTATE_AVX_MASK:
1051           return tdesc_i386_avx_linux;
1052         default:
1053           return tdesc_i386_linux;
1054         }
1055     }
1056   else
1057     return tdesc_i386_linux;
1058 }
1059
1060 /* Enable branch tracing.  */
1061
1062 static struct btrace_target_info *
1063 i386_linux_enable_btrace (ptid_t ptid)
1064 {
1065   struct btrace_target_info *tinfo;
1066   struct gdbarch *gdbarch;
1067
1068   errno = 0;
1069   tinfo = linux_enable_btrace (ptid);
1070
1071   if (tinfo == NULL)
1072     error (_("Could not enable branch tracing for %s: %s."),
1073            target_pid_to_str (ptid), safe_strerror (errno));
1074
1075   /* Fill in the size of a pointer in bits.  */
1076   gdbarch = target_thread_architecture (ptid);
1077   tinfo->ptr_bits = gdbarch_ptr_bit (gdbarch);
1078
1079   return tinfo;
1080 }
1081
1082 /* Disable branch tracing.  */
1083
1084 static void
1085 i386_linux_disable_btrace (struct btrace_target_info *tinfo)
1086 {
1087   enum btrace_error errcode = linux_disable_btrace (tinfo);
1088
1089   if (errcode != BTRACE_ERR_NONE)
1090     error (_("Could not disable branch tracing."));
1091 }
1092
1093 /* Teardown branch tracing.  */
1094
1095 static void
1096 i386_linux_teardown_btrace (struct btrace_target_info *tinfo)
1097 {
1098   /* Ignore errors.  */
1099   linux_disable_btrace (tinfo);
1100 }
1101
1102 /* -Wmissing-prototypes */
1103 extern initialize_file_ftype _initialize_i386_linux_nat;
1104
1105 void
1106 _initialize_i386_linux_nat (void)
1107 {
1108   struct target_ops *t;
1109
1110   /* Fill in the generic GNU/Linux methods.  */
1111   t = linux_target ();
1112
1113   i386_use_watchpoints (t);
1114
1115   i386_dr_low.set_control = i386_linux_dr_set_control;
1116   i386_dr_low.set_addr = i386_linux_dr_set_addr;
1117   i386_dr_low.get_addr = i386_linux_dr_get_addr;
1118   i386_dr_low.get_status = i386_linux_dr_get_status;
1119   i386_dr_low.get_control = i386_linux_dr_get_control;
1120   i386_set_debug_register_length (4);
1121
1122   /* Override the default ptrace resume method.  */
1123   t->to_resume = i386_linux_resume;
1124
1125   /* Override the GNU/Linux inferior startup hook.  */
1126   super_post_startup_inferior = t->to_post_startup_inferior;
1127   t->to_post_startup_inferior = i386_linux_child_post_startup_inferior;
1128
1129   /* Add our register access methods.  */
1130   t->to_fetch_registers = i386_linux_fetch_inferior_registers;
1131   t->to_store_registers = i386_linux_store_inferior_registers;
1132
1133   t->to_read_description = i386_linux_read_description;
1134
1135   /* Add btrace methods.  */
1136   t->to_supports_btrace = linux_supports_btrace;
1137   t->to_enable_btrace = i386_linux_enable_btrace;
1138   t->to_disable_btrace = i386_linux_disable_btrace;
1139   t->to_teardown_btrace = i386_linux_teardown_btrace;
1140   t->to_read_btrace = linux_read_btrace;
1141
1142   /* Register the target.  */
1143   linux_nat_add_target (t);
1144   linux_nat_set_new_thread (t, i386_linux_new_thread);
1145   linux_nat_set_new_fork (t, i386_linux_new_fork);
1146   linux_nat_set_forget_process (t, i386_forget_process);
1147   linux_nat_set_prepare_to_resume (t, i386_linux_prepare_to_resume);
1148 }