gdb/gdbserver/linux-x86-low.c

   1 /* GNU/Linux/x86-64 specific low level interface, for the remote server
   2    for GDB.
   3    Copyright (C) 2002, 2004, 2005, 2006, 2007, 2008, 2009
   4    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 <assert.h>
  22 #include <signal.h>
  23 #include "server.h"
  24 #include "linux-low.h"
  25 #include "i387-fp.h"
  26
  27 #include "gdb_proc_service.h"
  28
  29 /* NOTE: gdb_proc_service.h may include linux/elf.h.
  30    We need Elf32_Phdr.  If we don't get linux/elf.h we could include
  31    elf.h like linux-ppc-low.c does.  */
  32
  33 /* Defined in auto-generated file reg-i386-linux.c.  */
  34 void init_registers_i386_linux (void);
  35 /* Defined in auto-generated file reg-x86-64-linux.c.  */
  36 void init_registers_x86_64_linux (void);
  37
  38 #include <sys/reg.h>
  39 #include <sys/procfs.h>
  40 #include <sys/ptrace.h>
  41
  42 #ifndef PTRACE_GET_THREAD_AREA
  43 #define PTRACE_GET_THREAD_AREA 25
  44 #endif
  45
  46 /* This definition comes from prctl.h, but some kernels may not have it.  */
  47 #ifndef PTRACE_ARCH_PRCTL
  48 #define PTRACE_ARCH_PRCTL      30
  49 #endif
  50
  51 /* The following definitions come from prctl.h, but may be absent
  52    for certain configurations.  */
  53 #ifndef ARCH_GET_FS
  54 #define ARCH_SET_GS 0x1001
  55 #define ARCH_SET_FS 0x1002
  56 #define ARCH_GET_FS 0x1003
  57 #define ARCH_GET_GS 0x1004
  58 #endif
  59
  60 #ifdef __x86_64__
  61
  62 /* Mapping between the general-purpose registers in `struct user'
  63    format and GDB's register array layout.
  64    Note that the transfer layout uses 64-bit regs.  */
  65 static /*const*/ int i386_regmap[] =
  66 {
  67   RAX * 8, RCX * 8, RDX * 8, RBX * 8,
  68   RSP * 8, RBP * 8, RSI * 8, RDI * 8,
  69   RIP * 8, EFLAGS * 8, CS * 8, SS * 8,
  70   DS * 8, ES * 8, FS * 8, GS * 8
  71 };
  72
  73 #define I386_NUM_REGS (sizeof (i386_regmap) / sizeof (i386_regmap[0]))
  74
  75 /* So code below doesn't have to care, i386 or amd64.  */
  76 #define ORIG_EAX ORIG_RAX
  77
  78 static const int x86_64_regmap[] =
  79 {
  80   RAX * 8, RBX * 8, RCX * 8, RDX * 8,
  81   RSI * 8, RDI * 8, RBP * 8, RSP * 8,
  82   R8 * 8, R9 * 8, R10 * 8, R11 * 8,
  83   R12 * 8, R13 * 8, R14 * 8, R15 * 8,
  84   RIP * 8, EFLAGS * 8, CS * 8, SS * 8,
  85   DS * 8, ES * 8, FS * 8, GS * 8,
  86   -1, -1, -1, -1, -1, -1, -1, -1,
  87   -1, -1, -1, -1, -1, -1, -1, -1,
  88   -1, -1, -1, -1, -1, -1, -1, -1,
  89   -1, -1, -1, -1, -1, -1, -1, -1, -1,
  90   ORIG_RAX * 8
  91 };
  92
  93 #define X86_64_NUM_REGS (sizeof (x86_64_regmap) / sizeof (x86_64_regmap[0]))
  94
  95 #else /* ! __x86_64__ */
  96
  97 /* Mapping between the general-purpose registers in `struct user'
  98    format and GDB's register array layout.  */
  99 static /*const*/ int i386_regmap[] =
 100 {
 101   EAX * 4, ECX * 4, EDX * 4, EBX * 4,
 102   UESP * 4, EBP * 4, ESI * 4, EDI * 4,
 103   EIP * 4, EFL * 4, CS * 4, SS * 4,
 104   DS * 4, ES * 4, FS * 4, GS * 4
 105 };
 106
 107 #define I386_NUM_REGS (sizeof (i386_regmap) / sizeof (i386_regmap[0]))
 108
 109 #endif
 110 \f
 111 /* Called by libthread_db.  */
 112
 113 ps_err_e
 114 ps_get_thread_area (const struct ps_prochandle *ph,
 115                     lwpid_t lwpid, int idx, void **base)
 116 {
 117 #ifdef __x86_64__
 118   int use_64bit = register_size (0) == 8;
 119
 120   if (use_64bit)
 121     {
 122       switch (idx)
 123         {
 124         case FS:
 125           if (ptrace (PTRACE_ARCH_PRCTL, lwpid, base, ARCH_GET_FS) == 0)
 126             return PS_OK;
 127           break;
 128         case GS:
 129           if (ptrace (PTRACE_ARCH_PRCTL, lwpid, base, ARCH_GET_GS) == 0)
 130             return PS_OK;
 131           break;
 132         default:
 133           return PS_BADADDR;
 134         }
 135       return PS_ERR;
 136     }
 137 #endif
 138
 139   {
 140     unsigned int desc[4];
 141
 142     if (ptrace (PTRACE_GET_THREAD_AREA, lwpid,
 143                 (void *) (intptr_t) idx, (unsigned long) &desc) < 0)
 144       return PS_ERR;
 145
 146     *(int *)base = desc[1];
 147     return PS_OK;
 148   }
 149 }
 150 \f
 151 static int
 152 i386_cannot_store_register (int regno)
 153 {
 154   return regno >= I386_NUM_REGS;
 155 }
 156
 157 static int
 158 i386_cannot_fetch_register (int regno)
 159 {
 160   return regno >= I386_NUM_REGS;
 161 }
 162
 163 static void
 164 x86_fill_gregset (void *buf)
 165 {
 166   int i;
 167
 168 #ifdef __x86_64__
 169   if (register_size (0) == 8)
 170     {
 171       for (i = 0; i < X86_64_NUM_REGS; i++)
 172         if (x86_64_regmap[i] != -1)
 173           collect_register (i, ((char *) buf) + x86_64_regmap[i]);
 174       return;
 175     }
 176 #endif
 177
 178   for (i = 0; i < I386_NUM_REGS; i++)
 179     collect_register (i, ((char *) buf) + i386_regmap[i]);
 180
 181   collect_register_by_name ("orig_eax", ((char *) buf) + ORIG_EAX * 4);
 182 }
 183
 184 static void
 185 x86_store_gregset (const void *buf)
 186 {
 187   int i;
 188
 189 #ifdef __x86_64__
 190   if (register_size (0) == 8)
 191     {
 192       for (i = 0; i < X86_64_NUM_REGS; i++)
 193         if (x86_64_regmap[i] != -1)
 194           supply_register (i, ((char *) buf) + x86_64_regmap[i]);
 195       return;
 196     }
 197 #endif
 198
 199   for (i = 0; i < I386_NUM_REGS; i++)
 200     supply_register (i, ((char *) buf) + i386_regmap[i]);
 201
 202   supply_register_by_name ("orig_eax", ((char *) buf) + ORIG_EAX * 4);
 203 }
 204
 205 static void
 206 x86_fill_fpregset (void *buf)
 207 {
 208 #ifdef __x86_64__
 209   i387_cache_to_fxsave (buf);
 210 #else
 211   i387_cache_to_fsave (buf);
 212 #endif
 213 }
 214
 215 static void
 216 x86_store_fpregset (const void *buf)
 217 {
 218 #ifdef __x86_64__
 219   i387_fxsave_to_cache (buf);
 220 #else
 221   i387_fsave_to_cache (buf);
 222 #endif
 223 }
 224
 225 #ifndef __x86_64__
 226
 227 static void
 228 x86_fill_fpxregset (void *buf)
 229 {
 230   i387_cache_to_fxsave (buf);
 231 }
 232
 233 static void
 234 x86_store_fpxregset (const void *buf)
 235 {
 236   i387_fxsave_to_cache (buf);
 237 }
 238
 239 #endif
 240
 241 /* ??? The non-biarch i386 case stores all the i387 regs twice.
 242    Once in i387_.*fsave.* and once in i387_.*fxsave.*.
 243    This is, presumably, to handle the case where PTRACE_[GS]ETFPXREGS
 244    doesn't work.  IWBN to avoid the duplication in the case where it
 245    does work.  Maybe the arch_setup routine could check whether it works
 246    and update target_regsets accordingly, maybe by moving target_regsets
 247    to linux_target_ops and set the right one there, rather than having to
 248    modify the target_regsets global.  */
 249
 250 struct regset_info target_regsets[] =
 251 {
 252 #ifdef HAVE_PTRACE_GETREGS
 253   { PTRACE_GETREGS, PTRACE_SETREGS, sizeof (elf_gregset_t),
 254     GENERAL_REGS,
 255     x86_fill_gregset, x86_store_gregset },
 256 # ifndef __x86_64__
 257 #  ifdef HAVE_PTRACE_GETFPXREGS
 258   { PTRACE_GETFPXREGS, PTRACE_SETFPXREGS, sizeof (elf_fpxregset_t),
 259     EXTENDED_REGS,
 260     x86_fill_fpxregset, x86_store_fpxregset },
 261 #  endif
 262 # endif
 263   { PTRACE_GETFPREGS, PTRACE_SETFPREGS, sizeof (elf_fpregset_t),
 264     FP_REGS,
 265     x86_fill_fpregset, x86_store_fpregset },
 266 #endif /* HAVE_PTRACE_GETREGS */
 267   { 0, 0, -1, -1, NULL, NULL }
 268 };
 269
 270 static CORE_ADDR
 271 x86_get_pc (void)
 272 {
 273   int use_64bit = register_size (0) == 8;
 274
 275   if (use_64bit)
 276     {
 277       unsigned long pc;
 278       collect_register_by_name ("rip", &pc);
 279       return (CORE_ADDR) pc;
 280     }
 281   else
 282     {
 283       unsigned int pc;
 284       collect_register_by_name ("eip", &pc);
 285       return (CORE_ADDR) pc;
 286     }
 287 }
 288
 289 static void
 290 x86_set_pc (CORE_ADDR pc)
 291 {
 292   int use_64bit = register_size (0) == 8;
 293
 294   if (use_64bit)
 295     {
 296       unsigned long newpc = pc;
 297       supply_register_by_name ("rip", &newpc);
 298     }
 299   else
 300     {
 301       unsigned int newpc = pc;
 302       supply_register_by_name ("eip", &newpc);
 303     }
 304 }
 305 \f
 306 static const unsigned char x86_breakpoint[] = { 0xCC };
 307 #define x86_breakpoint_len 1
 308
 309 static int
 310 x86_breakpoint_at (CORE_ADDR pc)
 311 {
 312   unsigned char c;
 313
 314   read_inferior_memory (pc, &c, 1);
 315   if (c == 0xCC)
 316     return 1;
 317
 318   return 0;
 319 }
 320 \f
 321 /* When GDBSERVER is built as a 64-bit application on linux, the
 322    PTRACE_GETSIGINFO data is always presented in 64-bit layout.  Since
 323    debugging a 32-bit inferior with a 64-bit GDBSERVER should look the same
 324    as debugging it with a 32-bit GDBSERVER, we do the 32-bit <-> 64-bit
 325    conversion in-place ourselves.  */
 326
 327 /* These types below (compat_*) define a siginfo type that is layout
 328    compatible with the siginfo type exported by the 32-bit userspace
 329    support.  */
 330
 331 #ifdef __x86_64__
 332
 333 typedef int compat_int_t;
 334 typedef unsigned int compat_uptr_t;
 335
 336 typedef int compat_time_t;
 337 typedef int compat_timer_t;
 338 typedef int compat_clock_t;
 339
 340 struct compat_timeval
 341 {
 342   compat_time_t tv_sec;
 343   int tv_usec;
 344 };
 345
 346 typedef union compat_sigval
 347 {
 348   compat_int_t sival_int;
 349   compat_uptr_t sival_ptr;
 350 } compat_sigval_t;
 351
 352 typedef struct compat_siginfo
 353 {
 354   int si_signo;
 355   int si_errno;
 356   int si_code;
 357
 358   union
 359   {
 360     int _pad[((128 / sizeof (int)) - 3)];
 361
 362     /* kill() */
 363     struct
 364     {
 365       unsigned int _pid;
 366       unsigned int _uid;
 367     } _kill;
 368
 369     /* POSIX.1b timers */
 370     struct
 371     {
 372       compat_timer_t _tid;
 373       int _overrun;
 374       compat_sigval_t _sigval;
 375     } _timer;
 376
 377     /* POSIX.1b signals */
 378     struct
 379     {
 380       unsigned int _pid;
 381       unsigned int _uid;
 382       compat_sigval_t _sigval;
 383     } _rt;
 384
 385     /* SIGCHLD */
 386     struct
 387     {
 388       unsigned int _pid;
 389       unsigned int _uid;
 390       int _status;
 391       compat_clock_t _utime;
 392       compat_clock_t _stime;
 393     } _sigchld;
 394
 395     /* SIGILL, SIGFPE, SIGSEGV, SIGBUS */
 396     struct
 397     {
 398       unsigned int _addr;
 399     } _sigfault;
 400
 401     /* SIGPOLL */
 402     struct
 403     {
 404       int _band;
 405       int _fd;
 406     } _sigpoll;
 407   } _sifields;
 408 } compat_siginfo_t;
 409
 410 #define cpt_si_pid _sifields._kill._pid
 411 #define cpt_si_uid _sifields._kill._uid
 412 #define cpt_si_timerid _sifields._timer._tid
 413 #define cpt_si_overrun _sifields._timer._overrun
 414 #define cpt_si_status _sifields._sigchld._status
 415 #define cpt_si_utime _sifields._sigchld._utime
 416 #define cpt_si_stime _sifields._sigchld._stime
 417 #define cpt_si_ptr _sifields._rt._sigval.sival_ptr
 418 #define cpt_si_addr _sifields._sigfault._addr
 419 #define cpt_si_band _sifields._sigpoll._band
 420 #define cpt_si_fd _sifields._sigpoll._fd
 421
 422 /* glibc at least up to 2.3.2 doesn't have si_timerid, si_overrun.
 423    In their place is si_timer1,si_timer2.  */
 424 #ifndef si_timerid
 425 #define si_timerid si_timer1
 426 #endif
 427 #ifndef si_overrun
 428 #define si_overrun si_timer2
 429 #endif
 430
 431 static void
 432 compat_siginfo_from_siginfo (compat_siginfo_t *to, siginfo_t *from)
 433 {
 434   memset (to, 0, sizeof (*to));
 435
 436   to->si_signo = from->si_signo;
 437   to->si_errno = from->si_errno;
 438   to->si_code = from->si_code;
 439
 440   if (to->si_code < 0)
 441     {
 442       to->cpt_si_ptr = (intptr_t) from->si_ptr;
 443     }
 444   else if (to->si_code == SI_USER)
 445     {
 446       to->cpt_si_pid = from->si_pid;
 447       to->cpt_si_uid = from->si_uid;
 448     }
 449   else if (to->si_code == SI_TIMER)
 450     {
 451       to->cpt_si_timerid = from->si_timerid;
 452       to->cpt_si_overrun = from->si_overrun;
 453       to->cpt_si_ptr = (intptr_t) from->si_ptr;
 454     }
 455   else
 456     {
 457       switch (to->si_signo)
 458         {
 459         case SIGCHLD:
 460           to->cpt_si_pid = from->si_pid;
 461           to->cpt_si_uid = from->si_uid;
 462           to->cpt_si_status = from->si_status;
 463           to->cpt_si_utime = from->si_utime;
 464           to->cpt_si_stime = from->si_stime;
 465           break;
 466         case SIGILL:
 467         case SIGFPE:
 468         case SIGSEGV:
 469         case SIGBUS:
 470           to->cpt_si_addr = (intptr_t) from->si_addr;
 471           break;
 472         case SIGPOLL:
 473           to->cpt_si_band = from->si_band;
 474           to->cpt_si_fd = from->si_fd;
 475           break;
 476         default:
 477           to->cpt_si_pid = from->si_pid;
 478           to->cpt_si_uid = from->si_uid;
 479           to->cpt_si_ptr = (intptr_t) from->si_ptr;
 480           break;
 481         }
 482     }
 483 }
 484
 485 static void
 486 siginfo_from_compat_siginfo (siginfo_t *to, compat_siginfo_t *from)
 487 {
 488   memset (to, 0, sizeof (*to));
 489
 490   to->si_signo = from->si_signo;
 491   to->si_errno = from->si_errno;
 492   to->si_code = from->si_code;
 493
 494   if (to->si_code < 0)
 495     {
 496       to->si_ptr = (void *) (intptr_t) from->cpt_si_ptr;
 497     }
 498   else if (to->si_code == SI_USER)
 499     {
 500       to->si_pid = from->cpt_si_pid;
 501       to->si_uid = from->cpt_si_uid;
 502     }
 503   else if (to->si_code == SI_TIMER)
 504     {
 505       to->si_timerid = from->cpt_si_timerid;
 506       to->si_overrun = from->cpt_si_overrun;
 507       to->si_ptr = (void *) (intptr_t) from->cpt_si_ptr;
 508     }
 509   else
 510     {
 511       switch (to->si_signo)
 512         {
 513         case SIGCHLD:
 514           to->si_pid = from->cpt_si_pid;
 515           to->si_uid = from->cpt_si_uid;
 516           to->si_status = from->cpt_si_status;
 517           to->si_utime = from->cpt_si_utime;
 518           to->si_stime = from->cpt_si_stime;
 519           break;
 520         case SIGILL:
 521         case SIGFPE:
 522         case SIGSEGV:
 523         case SIGBUS:
 524           to->si_addr = (void *) (intptr_t) from->cpt_si_addr;
 525           break;
 526         case SIGPOLL:
 527           to->si_band = from->cpt_si_band;
 528           to->si_fd = from->cpt_si_fd;
 529           break;
 530         default:
 531           to->si_pid = from->cpt_si_pid;
 532           to->si_uid = from->cpt_si_uid;
 533           to->si_ptr = (void* ) (intptr_t) from->cpt_si_ptr;
 534           break;
 535         }
 536     }
 537 }
 538
 539 #endif /* __x86_64__ */
 540
 541 /* Convert a native/host siginfo object, into/from the siginfo in the
 542    layout of the inferiors' architecture.  Returns true if any
 543    conversion was done; false otherwise.  If DIRECTION is 1, then copy
 544    from INF to NATIVE.  If DIRECTION is 0, copy from NATIVE to
 545    INF.  */
 546
 547 static int
 548 x86_siginfo_fixup (struct siginfo *native, void *inf, int direction)
 549 {
 550 #ifdef __x86_64__
 551   /* Is the inferior 32-bit?  If so, then fixup the siginfo object.  */
 552   if (register_size (0) == 4)
 553     {
 554       assert (sizeof (struct siginfo) == sizeof (compat_siginfo_t));
 555
 556       if (direction == 0)
 557         compat_siginfo_from_siginfo ((struct compat_siginfo *) inf, native);
 558       else
 559         siginfo_from_compat_siginfo (native, (struct compat_siginfo *) inf);
 560
 561       return 1;
 562     }
 563 #endif
 564
 565   return 0;
 566 }
 567 \f
 568 /* Return non-zero if the target is 64-bit.  */
 569
 570 static void
 571 x86_arch_setup (void)
 572 {
 573 #ifdef __x86_64__
 574   int pid = pid_of (get_thread_lwp (current_inferior));
 575   char *file = linux_child_pid_to_exec_file (pid);
 576   int use_64bit = elf_64_file_p (file);
 577
 578   free (file);
 579
 580   if (use_64bit < 0)
 581     {
 582       /* This can only happen if /proc/<pid>/exe is unreadable,
 583          but "that can't happen" if we've gotten this far.
 584          Fall through and assume this is a 32-bit program.  */
 585     }
 586   else if (use_64bit)
 587     {
 588       init_registers_x86_64_linux ();
 589
 590       /* Amd64 doesn't have HAVE_LINUX_USRREGS.  */
 591       the_low_target.num_regs = -1;
 592       the_low_target.regmap = NULL;
 593       the_low_target.cannot_fetch_register = NULL;
 594       the_low_target.cannot_store_register = NULL;
 595
 596       /* Amd64 has 16 xmm regs.  */
 597       num_xmm_registers = 16;
 598
 599       return;
 600     }
 601 #endif
 602
 603   /* Ok we have a 32-bit inferior.  */
 604
 605   init_registers_i386_linux ();
 606
 607   the_low_target.num_regs = I386_NUM_REGS;
 608   the_low_target.regmap = i386_regmap;
 609   the_low_target.cannot_fetch_register = i386_cannot_fetch_register;
 610   the_low_target.cannot_store_register = i386_cannot_store_register;
 611
 612   /* I386 has 8 xmm regs.  */
 613   num_xmm_registers = 8;
 614 }
 615
 616 /* This is initialized assuming an amd64 target.
 617    x86_arch_setup will correct it for i386 or amd64 targets.  */
 618
 619 struct linux_target_ops the_low_target =
 620 {
 621   x86_arch_setup,
 622   -1,
 623   NULL,
 624   NULL,
 625   NULL,
 626   x86_get_pc,
 627   x86_set_pc,
 628   x86_breakpoint,
 629   x86_breakpoint_len,
 630   NULL,
 631   1,
 632   x86_breakpoint_at,
 633   NULL,
 634   NULL,
 635   NULL,
 636   NULL,
 637   /* collect_ptrace_register/supply_ptrace_register are not needed in the
 638      native i386 case (no registers smaller than an xfer unit), and are not
 639      used in the biarch case (HAVE_LINUX_USRREGS is not defined).  */
 640   NULL,
 641   NULL,
 642   /* need to fix up i386 siginfo if host is amd64 */
 643   x86_siginfo_fixup,
 644 };