gdb/infptrace.c

   1 /* Low level Unix child interface to ptrace, for GDB when running under Unix.
   2    Copyright (C) 1988, 1989, 1990, 1991 Free Software Foundation, Inc.
   3
   4 This file is part of GDB.
   5
   6 This program is free software; you can redistribute it and/or modify
   7 it under the terms of the GNU General Public License as published by
   8 the Free Software Foundation; either version 2 of the License, or
   9 (at your option) any later version.
  10
  11 This program is distributed in the hope that it will be useful,
  12 but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 GNU General Public License for more details.
  15
  16 You should have received a copy of the GNU General Public License
  17 along with this program; if not, write to the Free Software
  18 Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.  */
  19
  20 #include <stdio.h>
  21 #include "defs.h"
  22 #include "param.h"
  23 #include "frame.h"
  24 #include "inferior.h"
  25 #include "target.h"
  26
  27 #ifdef USG
  28 #include <sys/types.h>
  29 #endif
  30
  31 #include <sys/param.h>
  32 #include <sys/dir.h>
  33 #include <signal.h>
  34 #include <sys/ioctl.h>
  35 #ifndef USG
  36 #include <sys/ptrace.h>
  37 #endif
  38
  39 #if !defined (PT_KILL)
  40 #define PT_KILL 8
  41 #define PT_STEP 9
  42 #define PT_CONTINUE 7
  43 #define PT_READ_U 3
  44 #define PT_WRITE_U 6
  45 #define PT_READ_I 1
  46 #define PT_READ_D 2
  47 #define PT_WRITE_I 4
  48 #define PT_WRITE_D 5
  49 #endif /* No PT_KILL.  */
  50
  51 #ifndef PT_ATTACH
  52 #define PT_ATTACH PTRACE_ATTACH
  53 #endif
  54 #ifndef PT_DETACH
  55 #define PT_DETACH PTRACE_DETACH
  56 #endif
  57
  58 #include "gdbcore.h"
  59 #include <sys/user.h>           /* After a.out.h  */
  60 #include <sys/file.h>
  61 #include <sys/stat.h>
  62 \f
  63 /* This function simply calls ptrace with the given arguments.
  64    It exists so that all calls to ptrace are isolated in this
  65    machine-dependent file. */
  66 int
  67 call_ptrace (request, pid, addr, data)
  68      int request, pid, *addr, data;
  69 {
  70   return ptrace (request, pid, addr, data);
  71 }
  72
  73 #ifdef DEBUG_PTRACE
  74 /* For the rest of the file, use an extra level of indirection */
  75 /* This lets us breakpoint usefully on call_ptrace. */
  76 #define ptrace call_ptrace
  77 #endif
  78
  79 /* This is used when GDB is exiting.  It gives less chance of error.*/
  80
  81 void
  82 kill_inferior_fast ()
  83 {
  84   if (inferior_pid == 0)
  85     return;
  86   ptrace (PT_KILL, inferior_pid, 0, 0);
  87   wait ((int *)0);
  88 }
  89
  90 void
  91 kill_inferior (args, from_tty)
  92      char *args;
  93      int from_tty;
  94 {
  95   kill_inferior_fast ();
  96   target_mourn_inferior ();
  97 }
  98
  99 /* Resume execution of the inferior process.
 100    If STEP is nonzero, single-step it.
 101    If SIGNAL is nonzero, give it that signal.  */
 102
 103 void
 104 child_resume (step, signal)
 105      int step;
 106      int signal;
 107 {
 108   errno = 0;
 109
 110   /* An address of (int *)1 tells ptrace to continue from where it was.
 111      (If GDB wanted it to start some other way, we have already written
 112      a new PC value to the child.)  */
 113
 114   if (step)
 115     ptrace (PT_STEP, inferior_pid, (int *)1, signal);
 116   else
 117     ptrace (PT_CONTINUE, inferior_pid, (int *)1, signal);
 118
 119   if (errno)
 120     perror_with_name ("ptrace");
 121 }
 122 \f
 123 #ifdef ATTACH_DETACH
 124 /* Nonzero if we are debugging an attached process rather than
 125    an inferior.  */
 126 extern int attach_flag;
 127
 128 /* Start debugging the process whose number is PID.  */
 129 int
 130 attach (pid)
 131      int pid;
 132 {
 133   errno = 0;
 134   ptrace (PT_ATTACH, pid, 0, 0);
 135   if (errno)
 136     perror_with_name ("ptrace");
 137   attach_flag = 1;
 138   return pid;
 139 }
 140
 141 /* Stop debugging the process whose number is PID
 142    and continue it with signal number SIGNAL.
 143    SIGNAL = 0 means just continue it.  */
 144
 145 void
 146 detach (signal)
 147      int signal;
 148 {
 149   errno = 0;
 150   ptrace (PT_DETACH, inferior_pid, 1, signal);
 151   if (errno)
 152     perror_with_name ("ptrace");
 153   attach_flag = 0;
 154 }
 155 #endif /* ATTACH_DETACH */
 156 \f
 157 #if !defined (FETCH_INFERIOR_REGISTERS)
 158
 159 /* KERNEL_U_ADDR is the amount to subtract from u.u_ar0
 160    to get the offset in the core file of the register values.  */
 161 #if defined (KERNEL_U_ADDR_BSD)
 162 /* Get kernel_u_addr using BSD-style nlist().  */
 163 CORE_ADDR kernel_u_addr;
 164
 165 void
 166 _initialize_kernel_u_addr ()
 167 {
 168   struct nlist names[2];
 169
 170   names[0].n_un.n_name = "_u";
 171   names[1].n_un.n_name = NULL;
 172   if (nlist ("/vmunix", names) == 0)
 173     kernel_u_addr = names[0].n_value;
 174   else
 175     fatal ("Unable to get kernel u area address.");
 176 }
 177 #endif /* KERNEL_U_ADDR_BSD.  */
 178
 179 #if defined (KERNEL_U_ADDR_HPUX)
 180 /* Get kernel_u_addr using HPUX-style nlist().  */
 181 CORE_ADDR kernel_u_addr;
 182
 183 struct hpnlist {
 184         char *          n_name;
 185         long            n_value;
 186         unsigned char   n_type;
 187         unsigned char   n_length;
 188         short           n_almod;
 189         short           n_unused;
 190 };
 191 static struct hpnlist nl[] = {{ "_u", -1, }, { (char *) 0, }};
 192
 193 /* read the value of the u area from the hp-ux kernel */
 194 void _initialize_kernel_u_addr ()
 195 {
 196     struct user u;
 197     nlist ("/hp-ux", &nl);
 198     kernel_u_addr = nl[0].n_value;
 199 }
 200 #endif /* KERNEL_U_ADDR_HPUX.  */
 201
 202 #if !defined (offsetof)
 203 #define offsetof(TYPE, MEMBER) ((unsigned long) &((TYPE *)0)->MEMBER)
 204 #endif
 205
 206 /* U_REGS_OFFSET is the offset of the registers within the u area.  */
 207 #if !defined (U_REGS_OFFSET)
 208 #define U_REGS_OFFSET \
 209   ptrace (PT_READ_U, inferior_pid, \
 210           (int *)(offsetof (struct user, u_ar0)), 0) - KERNEL_U_ADDR
 211 #endif
 212
 213 /* Fetch one register.  */
 214 static void
 215 fetch_register (regno)
 216      int regno;
 217 {
 218   register unsigned int regaddr;
 219   char buf[MAX_REGISTER_RAW_SIZE];
 220   register int i;
 221
 222   /* Offset of registers within the u area.  */
 223   unsigned int offset = U_REGS_OFFSET;
 224
 225   regaddr = register_addr (regno, offset);
 226   for (i = 0; i < REGISTER_RAW_SIZE (regno); i += sizeof (int))
 227     {
 228       *(int *) &buf[i] = ptrace (PT_READ_U, inferior_pid, (int *)regaddr, 0);
 229       regaddr += sizeof (int);
 230     }
 231   supply_register (regno, buf);
 232 }
 233
 234 /* Fetch all registers, or just one, from the child process.  */
 235
 236 void
 237 fetch_inferior_registers (regno)
 238      int regno;
 239 {
 240   if (regno == -1)
 241     for (regno = 0; regno < NUM_REGS; regno++)
 242       fetch_register (regno);
 243   else
 244     fetch_register (regno);
 245 }
 246
 247 /* Registers we shouldn't try to store.  */
 248 #if !defined (CANNOT_STORE_REGISTER)
 249 #define CANNOT_STORE_REGISTER(regno) 0
 250 #endif
 251
 252 /* Store our register values back into the inferior.
 253    If REGNO is -1, do this for all registers.
 254    Otherwise, REGNO specifies which register (so we can save time).  */
 255
 256 int
 257 store_inferior_registers (regno)
 258      int regno;
 259 {
 260   register unsigned int regaddr;
 261   char buf[80];
 262   extern char registers[];
 263   register int i;
 264   int result = 0;
 265
 266   unsigned int offset = U_REGS_OFFSET;
 267
 268   if (regno >= 0)
 269     {
 270       regaddr = register_addr (regno, offset);
 271       for (i = 0; i < REGISTER_RAW_SIZE (regno); i += sizeof(int))
 272         {
 273           errno = 0;
 274           ptrace (PT_WRITE_U, inferior_pid, (int *)regaddr,
 275                   *(int *) &registers[REGISTER_BYTE (regno) + i]);
 276           if (errno != 0)
 277             {
 278               sprintf (buf, "writing register number %d(%d)", regno, i);
 279               perror_with_name (buf);
 280               result = -1;
 281             }
 282           regaddr += sizeof(int);
 283         }
 284     }
 285   else
 286     {
 287       for (regno = 0; regno < NUM_REGS; regno++)
 288         {
 289           if (CANNOT_STORE_REGISTER (regno))
 290             continue;
 291           regaddr = register_addr (regno, offset);
 292           for (i = 0; i < REGISTER_RAW_SIZE (regno); i += sizeof(int))
 293             {
 294               errno = 0;
 295               ptrace (PT_WRITE_U, inferior_pid, (int *)regaddr,
 296                       *(int *) &registers[REGISTER_BYTE (regno) + i]);
 297               if (errno != 0)
 298                 {
 299                   sprintf (buf, "writing register number %d(%d)", regno, i);
 300                   perror_with_name (buf);
 301                   result = -1;
 302                 }
 303               regaddr += sizeof(int);
 304             }
 305         }
 306     }
 307   return result;
 308 }
 309 #endif /* !defined (FETCH_INFERIOR_REGISTERS).  */
 310 \f
 311 /* NOTE! I tried using PTRACE_READDATA, etc., to read and write memory
 312    in the NEW_SUN_PTRACE case.
 313    It ought to be straightforward.  But it appears that writing did
 314    not write the data that I specified.  I cannot understand where
 315    it got the data that it actually did write.  */
 316
 317 /* Copy LEN bytes to or from inferior's memory starting at MEMADDR
 318    to debugger memory starting at MYADDR.   Copy to inferior if
 319    WRITE is nonzero.
 320
 321    Returns the length copied, which is either the LEN argument or zero.
 322    This xfer function does not do partial moves, since child_ops
 323    doesn't allow memory operations to cross below us in the target stack
 324    anyway.  */
 325
 326 int
 327 child_xfer_memory (memaddr, myaddr, len, write, target)
 328      CORE_ADDR memaddr;
 329      char *myaddr;
 330      int len;
 331      int write;
 332      struct target_ops target;          /* ignored */
 333 {
 334   register int i;
 335   /* Round starting address down to longword boundary.  */
 336   register CORE_ADDR addr = memaddr & - sizeof (int);
 337   /* Round ending address up; get number of longwords that makes.  */
 338   register int count
 339     = (((memaddr + len) - addr) + sizeof (int) - 1) / sizeof (int);
 340   /* Allocate buffer of that many longwords.  */
 341   register int *buffer = (int *) alloca (count * sizeof (int));
 342
 343   if (write)
 344     {
 345       /* Fill start and end extra bytes of buffer with existing memory data.  */
 346
 347       if (addr != memaddr || len < (int)sizeof (int)) {
 348         /* Need part of initial word -- fetch it.  */
 349         buffer[0] = ptrace (PT_READ_I, inferior_pid, (int *)addr, 0);
 350       }
 351
 352       if (count > 1)            /* FIXME, avoid if even boundary */
 353         {
 354           buffer[count - 1]
 355             = ptrace (PT_READ_I, inferior_pid,
 356                       (int *)(addr + (count - 1) * sizeof (int)), 0);
 357         }
 358
 359       /* Copy data to be written over corresponding part of buffer */
 360
 361       bcopy (myaddr, (char *) buffer + (memaddr & (sizeof (int) - 1)), len);
 362
 363       /* Write the entire buffer.  */
 364
 365       for (i = 0; i < count; i++, addr += sizeof (int))
 366         {
 367           errno = 0;
 368           ptrace (PT_WRITE_D, inferior_pid, (int *)addr, buffer[i]);
 369           if (errno)
 370             {
 371               /* Using the appropriate one (I or D) is necessary for
 372                  Gould NP1, at least.  */
 373               errno = 0;
 374               ptrace (PT_WRITE_I, inferior_pid, (int *)addr, buffer[i]);
 375             }
 376           if (errno)
 377             return 0;
 378         }
 379     }
 380   else
 381     {
 382       /* Read all the longwords */
 383       for (i = 0; i < count; i++, addr += sizeof (int))
 384         {
 385           errno = 0;
 386           buffer[i] = ptrace (PT_READ_I, inferior_pid, (int *)addr, 0);
 387           if (errno)
 388             return 0;
 389           QUIT;
 390         }
 391
 392       /* Copy appropriate bytes out of the buffer.  */
 393       bcopy ((char *) buffer + (memaddr & (sizeof (int) - 1)), myaddr, len);
 394     }
 395   return len;
 396 }