gdb/infptrace.c

   1 /* Low level Unix child interface to ptrace, for GDB when running under Unix.
   2    Copyright 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1998,
   3    1999, 2000, 2001
   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 2 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, write to the Free Software
  20    Foundation, Inc., 59 Temple Place - Suite 330,
  21    Boston, MA 02111-1307, USA.  */
  22
  23 #include "defs.h"
  24 #include "frame.h"
  25 #include "inferior.h"
  26 #include "target.h"
  27 #include "gdb_string.h"
  28 #include "regcache.h"
  29
  30 #include "gdb_wait.h"
  31
  32 #include "command.h"
  33
  34 #ifdef USG
  35 #include <sys/types.h>
  36 #endif
  37
  38 #include <sys/param.h>
  39 #include "gdb_dirent.h"
  40 #include <signal.h>
  41 #include <sys/ioctl.h>
  42
  43 #ifdef HAVE_PTRACE_H
  44 #include <ptrace.h>
  45 #else
  46 #ifdef HAVE_SYS_PTRACE_H
  47 #include <sys/ptrace.h>
  48 #endif
  49 #endif
  50
  51 #if !defined (PT_READ_I)
  52 #define PT_READ_I       1       /* Read word from text space */
  53 #endif
  54 #if !defined (PT_READ_D)
  55 #define PT_READ_D       2       /* Read word from data space */
  56 #endif
  57 #if !defined (PT_READ_U)
  58 #define PT_READ_U       3       /* Read word from kernel user struct */
  59 #endif
  60 #if !defined (PT_WRITE_I)
  61 #define PT_WRITE_I      4       /* Write word to text space */
  62 #endif
  63 #if !defined (PT_WRITE_D)
  64 #define PT_WRITE_D      5       /* Write word to data space */
  65 #endif
  66 #if !defined (PT_WRITE_U)
  67 #define PT_WRITE_U      6       /* Write word to kernel user struct */
  68 #endif
  69 #if !defined (PT_CONTINUE)
  70 #define PT_CONTINUE     7       /* Continue after signal */
  71 #endif
  72 #if !defined (PT_STEP)
  73 #define PT_STEP         9       /* Set flag for single stepping */
  74 #endif
  75 #if !defined (PT_KILL)
  76 #define PT_KILL         8       /* Send child a SIGKILL signal */
  77 #endif
  78
  79 #ifndef PT_ATTACH
  80 #define PT_ATTACH PTRACE_ATTACH
  81 #endif
  82 #ifndef PT_DETACH
  83 #define PT_DETACH PTRACE_DETACH
  84 #endif
  85
  86 #include "gdbcore.h"
  87 #ifndef NO_SYS_FILE
  88 #include <sys/file.h>
  89 #endif
  90 #if 0
  91 /* Don't think this is used anymore.  On the sequent (not sure whether it's
  92    dynix or ptx or both), it is included unconditionally by sys/user.h and
  93    not protected against multiple inclusion.  */
  94 #include "gdb_stat.h"
  95 #endif
  96
  97 #if !defined (FETCH_INFERIOR_REGISTERS)
  98 #include <sys/user.h>           /* Probably need to poke the user structure */
  99 #if defined (KERNEL_U_ADDR_BSD)
 100 #include <a.out.h>              /* For struct nlist */
 101 #endif /* KERNEL_U_ADDR_BSD.  */
 102 #endif /* !FETCH_INFERIOR_REGISTERS */
 103
 104 #if !defined (CHILD_XFER_MEMORY)
 105 static void udot_info (char *, int);
 106 #endif
 107
 108 #if !defined (FETCH_INFERIOR_REGISTERS)
 109 static void fetch_register (int);
 110 static void store_register (int);
 111 #endif
 112
 113 /*
 114  * Some systems (Linux) may have threads implemented as pseudo-processes,
 115  * in which case we may be tracing more than one process at a time.
 116  * In that case, inferior_pid will contain the main process ID and the
 117  * individual thread (process) id mashed together.  These macros are
 118  * used to separate them out.  The definitions may be overridden in tm.h
 119  *
 120  * NOTE: default definitions here are for systems with no threads.
 121  * Useful definitions MUST be provided in tm.h
 122  */
 123
 124 #if !defined (PIDGET)   /* Default definition for PIDGET/TIDGET.  */
 125 #define PIDGET(PID)     PID
 126 #define TIDGET(PID)     0
 127 #endif
 128
 129 void _initialize_kernel_u_addr (void);
 130 void _initialize_infptrace (void);
 131 \f
 132
 133 /* This function simply calls ptrace with the given arguments.
 134    It exists so that all calls to ptrace are isolated in this
 135    machine-dependent file. */
 136 int
 137 call_ptrace (int request, int pid, PTRACE_ARG3_TYPE addr, int data)
 138 {
 139   int pt_status = 0;
 140
 141 #if 0
 142   int saved_errno;
 143
 144   printf ("call_ptrace(request=%d, pid=%d, addr=0x%x, data=0x%x)",
 145           request, pid, addr, data);
 146 #endif
 147 #if defined(PT_SETTRC)
 148   /* If the parent can be told to attach to us, try to do it.  */
 149   if (request == PT_SETTRC)
 150     {
 151       errno = 0;
 152 #if !defined (FIVE_ARG_PTRACE)
 153       pt_status = ptrace (PT_SETTRC, pid, addr, data);
 154 #else
 155       /* Deal with HPUX 8.0 braindamage.  We never use the
 156          calls which require the fifth argument.  */
 157       pt_status = ptrace (PT_SETTRC, pid, addr, data, 0);
 158 #endif
 159       if (errno)
 160         perror_with_name ("ptrace");
 161 #if 0
 162       printf (" = %d\n", pt_status);
 163 #endif
 164       if (pt_status < 0)
 165         return pt_status;
 166       else
 167         return parent_attach_all (pid, addr, data);
 168     }
 169 #endif
 170
 171 #if defined(PT_CONTIN1)
 172   /* On HPUX, PT_CONTIN1 is a form of continue that preserves pending
 173      signals.  If it's available, use it.  */
 174   if (request == PT_CONTINUE)
 175     request = PT_CONTIN1;
 176 #endif
 177
 178 #if defined(PT_SINGLE1)
 179   /* On HPUX, PT_SINGLE1 is a form of step that preserves pending
 180      signals.  If it's available, use it.  */
 181   if (request == PT_STEP)
 182     request = PT_SINGLE1;
 183 #endif
 184
 185 #if 0
 186   saved_errno = errno;
 187   errno = 0;
 188 #endif
 189 #if !defined (FIVE_ARG_PTRACE)
 190   pt_status = ptrace (request, pid, addr, data);
 191 #else
 192   /* Deal with HPUX 8.0 braindamage.  We never use the
 193      calls which require the fifth argument.  */
 194   pt_status = ptrace (request, pid, addr, data, 0);
 195 #endif
 196
 197 #if 0
 198   if (errno)
 199     printf (" [errno = %d]", errno);
 200
 201   errno = saved_errno;
 202   printf (" = 0x%x\n", pt_status);
 203 #endif
 204   return pt_status;
 205 }
 206
 207
 208 #if defined (DEBUG_PTRACE) || defined (FIVE_ARG_PTRACE)
 209 /* For the rest of the file, use an extra level of indirection */
 210 /* This lets us breakpoint usefully on call_ptrace. */
 211 #define ptrace call_ptrace
 212 #endif
 213
 214 /* Wait for a process to finish, possibly running a target-specific
 215    hook before returning.  */
 216
 217 int
 218 ptrace_wait (int pid, int *status)
 219 {
 220   int wstate;
 221
 222   wstate = wait (status);
 223   target_post_wait (wstate, *status);
 224   return wstate;
 225 }
 226
 227 void
 228 kill_inferior (void)
 229 {
 230   int status;
 231
 232   if (inferior_pid == 0)
 233     return;
 234
 235   /* This once used to call "kill" to kill the inferior just in case
 236      the inferior was still running.  As others have noted in the past
 237      (kingdon) there shouldn't be any way to get here if the inferior
 238      is still running -- else there's a major problem elsewere in gdb
 239      and it needs to be fixed.
 240
 241      The kill call causes problems under hpux10, so it's been removed;
 242      if this causes problems we'll deal with them as they arise.  */
 243   ptrace (PT_KILL, inferior_pid, (PTRACE_ARG3_TYPE) 0, 0);
 244   ptrace_wait (0, &status);
 245   target_mourn_inferior ();
 246 }
 247
 248 #ifndef CHILD_RESUME
 249
 250 /* Resume execution of the inferior process.
 251    If STEP is nonzero, single-step it.
 252    If SIGNAL is nonzero, give it that signal.  */
 253
 254 void
 255 child_resume (int pid, int step, enum target_signal signal)
 256 {
 257   errno = 0;
 258
 259   if (pid == -1)
 260     /* Resume all threads.  */
 261     /* I think this only gets used in the non-threaded case, where "resume
 262        all threads" and "resume inferior_pid" are the same.  */
 263     pid = inferior_pid;
 264
 265   /* An address of (PTRACE_ARG3_TYPE)1 tells ptrace to continue from where
 266      it was.  (If GDB wanted it to start some other way, we have already
 267      written a new PC value to the child.)
 268
 269      If this system does not support PT_STEP, a higher level function will
 270      have called single_step() to transmute the step request into a
 271      continue request (by setting breakpoints on all possible successor
 272      instructions), so we don't have to worry about that here.  */
 273
 274   if (step)
 275     {
 276       if (SOFTWARE_SINGLE_STEP_P)
 277         internal_error (__FILE__, __LINE__, "failed internal consistency check");               /* Make sure this doesn't happen. */
 278       else
 279         ptrace (PT_STEP, pid, (PTRACE_ARG3_TYPE) 1,
 280                 target_signal_to_host (signal));
 281     }
 282   else
 283     ptrace (PT_CONTINUE, pid, (PTRACE_ARG3_TYPE) 1,
 284             target_signal_to_host (signal));
 285
 286   if (errno)
 287     {
 288       perror_with_name ("ptrace");
 289     }
 290 }
 291 #endif /* CHILD_RESUME */
 292 \f
 293
 294 #ifdef ATTACH_DETACH
 295 /* Start debugging the process whose number is PID.  */
 296 int
 297 attach (int pid)
 298 {
 299   errno = 0;
 300   ptrace (PT_ATTACH, pid, (PTRACE_ARG3_TYPE) 0, 0);
 301   if (errno)
 302     perror_with_name ("ptrace");
 303   attach_flag = 1;
 304   return pid;
 305 }
 306
 307 /* Stop debugging the process whose number is PID
 308    and continue it with signal number SIGNAL.
 309    SIGNAL = 0 means just continue it.  */
 310
 311 void
 312 detach (int signal)
 313 {
 314   errno = 0;
 315   ptrace (PT_DETACH, inferior_pid, (PTRACE_ARG3_TYPE) 1, signal);
 316   if (errno)
 317     perror_with_name ("ptrace");
 318   attach_flag = 0;
 319 }
 320 #endif /* ATTACH_DETACH */
 321 \f
 322 /* Default the type of the ptrace transfer to int.  */
 323 #ifndef PTRACE_XFER_TYPE
 324 #define PTRACE_XFER_TYPE int
 325 #endif
 326
 327 /* KERNEL_U_ADDR is the amount to subtract from u.u_ar0
 328    to get the offset in the core file of the register values.  */
 329 #if defined (KERNEL_U_ADDR_BSD) && !defined (FETCH_INFERIOR_REGISTERS)
 330 /* Get kernel_u_addr using BSD-style nlist().  */
 331 CORE_ADDR kernel_u_addr;
 332 #endif /* KERNEL_U_ADDR_BSD.  */
 333
 334 void
 335 _initialize_kernel_u_addr (void)
 336 {
 337 #if defined (KERNEL_U_ADDR_BSD) && !defined (FETCH_INFERIOR_REGISTERS)
 338   struct nlist names[2];
 339
 340   names[0].n_un.n_name = "_u";
 341   names[1].n_un.n_name = NULL;
 342   if (nlist ("/vmunix", names) == 0)
 343     kernel_u_addr = names[0].n_value;
 344   else
 345     internal_error (__FILE__, __LINE__,
 346                     "Unable to get kernel u area address.");
 347 #endif /* KERNEL_U_ADDR_BSD.  */
 348 }
 349
 350 #if !defined (FETCH_INFERIOR_REGISTERS)
 351
 352 #if !defined (offsetof)
 353 #define offsetof(TYPE, MEMBER) ((unsigned long) &((TYPE *)0)->MEMBER)
 354 #endif
 355
 356 /* U_REGS_OFFSET is the offset of the registers within the u area.  */
 357 #if !defined (U_REGS_OFFSET)
 358 #define U_REGS_OFFSET \
 359   ptrace (PT_READ_U, inferior_pid, \
 360           (PTRACE_ARG3_TYPE) (offsetof (struct user, u_ar0)), 0) \
 361     - KERNEL_U_ADDR
 362 #endif
 363
 364 /* Registers we shouldn't try to fetch.  */
 365 #if !defined (CANNOT_FETCH_REGISTER)
 366 #define CANNOT_FETCH_REGISTER(regno) 0
 367 #endif
 368
 369 /* Fetch one register.  */
 370
 371 static void
 372 fetch_register (int regno)
 373 {
 374   /* This isn't really an address.  But ptrace thinks of it as one.  */
 375   CORE_ADDR regaddr;
 376   char mess[128];               /* For messages */
 377   register int i;
 378   unsigned int offset;          /* Offset of registers within the u area.  */
 379   char buf[MAX_REGISTER_RAW_SIZE];
 380   int tid;
 381
 382   if (CANNOT_FETCH_REGISTER (regno))
 383     {
 384       memset (buf, '\0', REGISTER_RAW_SIZE (regno));    /* Supply zeroes */
 385       supply_register (regno, buf);
 386       return;
 387     }
 388
 389   /* Overload thread id onto process id */
 390   if ((tid = TIDGET (inferior_pid)) == 0)
 391     tid = inferior_pid;         /* no thread id, just use process id */
 392
 393   offset = U_REGS_OFFSET;
 394
 395   regaddr = register_addr (regno, offset);
 396   for (i = 0; i < REGISTER_RAW_SIZE (regno); i += sizeof (PTRACE_XFER_TYPE))
 397     {
 398       errno = 0;
 399       *(PTRACE_XFER_TYPE *) & buf[i] = ptrace (PT_READ_U, tid,
 400                                                (PTRACE_ARG3_TYPE) regaddr, 0);
 401       regaddr += sizeof (PTRACE_XFER_TYPE);
 402       if (errno != 0)
 403         {
 404           sprintf (mess, "reading register %s (#%d)",
 405                    REGISTER_NAME (regno), regno);
 406           perror_with_name (mess);
 407         }
 408     }
 409   supply_register (regno, buf);
 410 }
 411
 412
 413 /* Fetch register values from the inferior.
 414    If REGNO is negative, do this for all registers.
 415    Otherwise, REGNO specifies which register (so we can save time). */
 416
 417 void
 418 fetch_inferior_registers (int regno)
 419 {
 420   if (regno >= 0)
 421     {
 422       fetch_register (regno);
 423     }
 424   else
 425     {
 426       for (regno = 0; regno < ARCH_NUM_REGS; regno++)
 427         {
 428           fetch_register (regno);
 429         }
 430     }
 431 }
 432
 433 /* Registers we shouldn't try to store.  */
 434 #if !defined (CANNOT_STORE_REGISTER)
 435 #define CANNOT_STORE_REGISTER(regno) 0
 436 #endif
 437
 438 /* Store one register. */
 439
 440 static void
 441 store_register (int regno)
 442 {
 443   /* This isn't really an address.  But ptrace thinks of it as one.  */
 444   CORE_ADDR regaddr;
 445   char mess[128];               /* For messages */
 446   register int i;
 447   unsigned int offset;          /* Offset of registers within the u area.  */
 448   int tid;
 449
 450   if (CANNOT_STORE_REGISTER (regno))
 451     {
 452       return;
 453     }
 454
 455   /* Overload thread id onto process id */
 456   if ((tid = TIDGET (inferior_pid)) == 0)
 457     tid = inferior_pid;         /* no thread id, just use process id */
 458
 459   offset = U_REGS_OFFSET;
 460
 461   regaddr = register_addr (regno, offset);
 462   for (i = 0; i < REGISTER_RAW_SIZE (regno); i += sizeof (PTRACE_XFER_TYPE))
 463     {
 464       errno = 0;
 465       ptrace (PT_WRITE_U, tid, (PTRACE_ARG3_TYPE) regaddr,
 466               *(PTRACE_XFER_TYPE *) & registers[REGISTER_BYTE (regno) + i]);
 467       regaddr += sizeof (PTRACE_XFER_TYPE);
 468       if (errno != 0)
 469         {
 470           sprintf (mess, "writing register %s (#%d)",
 471                    REGISTER_NAME (regno), regno);
 472           perror_with_name (mess);
 473         }
 474     }
 475 }
 476
 477 /* Store our register values back into the inferior.
 478    If REGNO is negative, do this for all registers.
 479    Otherwise, REGNO specifies which register (so we can save time).  */
 480
 481 void
 482 store_inferior_registers (int regno)
 483 {
 484   if (regno >= 0)
 485     {
 486       store_register (regno);
 487     }
 488   else
 489     {
 490       for (regno = 0; regno < ARCH_NUM_REGS; regno++)
 491         {
 492           store_register (regno);
 493         }
 494     }
 495 }
 496 #endif /* !defined (FETCH_INFERIOR_REGISTERS).  */
 497 \f
 498
 499 #if !defined (CHILD_XFER_MEMORY)
 500 /* NOTE! I tried using PTRACE_READDATA, etc., to read and write memory
 501    in the NEW_SUN_PTRACE case.
 502    It ought to be straightforward.  But it appears that writing did
 503    not write the data that I specified.  I cannot understand where
 504    it got the data that it actually did write.  */
 505
 506 /* Copy LEN bytes to or from inferior's memory starting at MEMADDR
 507    to debugger memory starting at MYADDR.   Copy to inferior if
 508    WRITE is nonzero.  TARGET is ignored.
 509
 510    Returns the length copied, which is either the LEN argument or zero.
 511    This xfer function does not do partial moves, since child_ops
 512    doesn't allow memory operations to cross below us in the target stack
 513    anyway.  */
 514
 515 int
 516 child_xfer_memory (CORE_ADDR memaddr, char *myaddr, int len, int write,
 517                    struct mem_attrib *attrib ATTRIBUTE_UNUSED,
 518                    struct target_ops *target)
 519 {
 520   register int i;
 521   /* Round starting address down to longword boundary.  */
 522   register CORE_ADDR addr = memaddr & -sizeof (PTRACE_XFER_TYPE);
 523   /* Round ending address up; get number of longwords that makes.  */
 524   register int count
 525   = (((memaddr + len) - addr) + sizeof (PTRACE_XFER_TYPE) - 1)
 526   / sizeof (PTRACE_XFER_TYPE);
 527   /* Allocate buffer of that many longwords.  */
 528   register PTRACE_XFER_TYPE *buffer
 529   = (PTRACE_XFER_TYPE *) alloca (count * sizeof (PTRACE_XFER_TYPE));
 530
 531   if (write)
 532     {
 533       /* Fill start and end extra bytes of buffer with existing memory data.  */
 534
 535       if (addr != memaddr || len < (int) sizeof (PTRACE_XFER_TYPE))
 536         {
 537           /* Need part of initial word -- fetch it.  */
 538           buffer[0] = ptrace (PT_READ_I, PIDGET (inferior_pid),
 539                               (PTRACE_ARG3_TYPE) addr, 0);
 540         }
 541
 542       if (count > 1)            /* FIXME, avoid if even boundary */
 543         {
 544           buffer[count - 1]
 545             = ptrace (PT_READ_I, PIDGET (inferior_pid),
 546                       ((PTRACE_ARG3_TYPE)
 547                        (addr + (count - 1) * sizeof (PTRACE_XFER_TYPE))),
 548                       0);
 549         }
 550
 551       /* Copy data to be written over corresponding part of buffer */
 552
 553       memcpy ((char *) buffer + (memaddr & (sizeof (PTRACE_XFER_TYPE) - 1)),
 554               myaddr,
 555               len);
 556
 557       /* Write the entire buffer.  */
 558
 559       for (i = 0; i < count; i++, addr += sizeof (PTRACE_XFER_TYPE))
 560         {
 561           errno = 0;
 562           ptrace (PT_WRITE_D, PIDGET (inferior_pid),
 563                   (PTRACE_ARG3_TYPE) addr, buffer[i]);
 564           if (errno)
 565             {
 566               /* Using the appropriate one (I or D) is necessary for
 567                  Gould NP1, at least.  */
 568               errno = 0;
 569               ptrace (PT_WRITE_I, PIDGET (inferior_pid),
 570                       (PTRACE_ARG3_TYPE) addr, buffer[i]);
 571             }
 572           if (errno)
 573             return 0;
 574         }
 575 #ifdef CLEAR_INSN_CACHE
 576       CLEAR_INSN_CACHE ();
 577 #endif
 578     }
 579   else
 580     {
 581       /* Read all the longwords */
 582       for (i = 0; i < count; i++, addr += sizeof (PTRACE_XFER_TYPE))
 583         {
 584           errno = 0;
 585           buffer[i] = ptrace (PT_READ_I, PIDGET (inferior_pid),
 586                               (PTRACE_ARG3_TYPE) addr, 0);
 587           if (errno)
 588             return 0;
 589           QUIT;
 590         }
 591
 592       /* Copy appropriate bytes out of the buffer.  */
 593       memcpy (myaddr,
 594               (char *) buffer + (memaddr & (sizeof (PTRACE_XFER_TYPE) - 1)),
 595               len);
 596     }
 597   return len;
 598 }
 599 \f
 600
 601 static void
 602 udot_info (char *dummy1, int dummy2)
 603 {
 604 #if defined (KERNEL_U_SIZE)
 605   int udot_off;                 /* Offset into user struct */
 606   int udot_val;                 /* Value from user struct at udot_off */
 607   char mess[128];               /* For messages */
 608 #endif
 609
 610   if (!target_has_execution)
 611     {
 612       error ("The program is not being run.");
 613     }
 614
 615 #if !defined (KERNEL_U_SIZE)
 616
 617   /* Adding support for this command is easy.  Typically you just add a
 618      routine, called "kernel_u_size" that returns the size of the user
 619      struct, to the appropriate *-nat.c file and then add to the native
 620      config file "#define KERNEL_U_SIZE kernel_u_size()" */
 621   error ("Don't know how large ``struct user'' is in this version of gdb.");
 622
 623 #else
 624
 625   for (udot_off = 0; udot_off < KERNEL_U_SIZE; udot_off += sizeof (udot_val))
 626     {
 627       if ((udot_off % 24) == 0)
 628         {
 629           if (udot_off > 0)
 630             {
 631               printf_filtered ("\n");
 632             }
 633           printf_filtered ("%04x:", udot_off);
 634         }
 635       udot_val = ptrace (PT_READ_U, inferior_pid, (PTRACE_ARG3_TYPE) udot_off, 0);
 636       if (errno != 0)
 637         {
 638           sprintf (mess, "\nreading user struct at offset 0x%x", udot_off);
 639           perror_with_name (mess);
 640         }
 641       /* Avoid using nonportable (?) "*" in print specs */
 642       printf_filtered (sizeof (int) == 4 ? " 0x%08x" : " 0x%16x", udot_val);
 643     }
 644   printf_filtered ("\n");
 645
 646 #endif
 647 }
 648 #endif /* !defined (CHILD_XFER_MEMORY).  */
 649 \f
 650
 651 void
 652 _initialize_infptrace (void)
 653 {
 654 #if !defined (CHILD_XFER_MEMORY)
 655   add_info ("udot", udot_info,
 656             "Print contents of kernel ``struct user'' for current child.");
 657 #endif
 658 }