gdb/gdbserver/linux-low.c

   1 /* Low level interface to ptrace, for the remote server for GDB.
   2    Copyright 1995, 1996, 1998, 1999, 2000, 2001, 2002
   3    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 2 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, write to the Free Software
  19    Foundation, Inc., 59 Temple Place - Suite 330,
  20    Boston, MA 02111-1307, USA.  */
  21
  22 #include "server.h"
  23 #include <sys/wait.h>
  24
  25 #include <stdio.h>
  26 #include <sys/param.h>
  27 #include <sys/dir.h>
  28 #include <sys/ptrace.h>
  29 #include <sys/user.h>
  30 #include <signal.h>
  31 #include <sys/ioctl.h>
  32 #include <fcntl.h>
  33 #include <string.h>
  34 #include <stdlib.h>
  35 #include <unistd.h>
  36
  37 #define PTRACE_ARG3_TYPE long
  38 #define PTRACE_XFER_TYPE int
  39
  40 extern int errno;
  41 extern int num_regs;
  42 extern int regmap[];
  43
  44 /* Start an inferior process and returns its pid.
  45    ALLARGS is a vector of program-name and args. */
  46
  47 int
  48 create_inferior (char *program, char **allargs)
  49 {
  50   int pid;
  51
  52   pid = fork ();
  53   if (pid < 0)
  54     perror_with_name ("fork");
  55
  56   if (pid == 0)
  57     {
  58       ptrace (PTRACE_TRACEME, 0, 0, 0);
  59
  60       execv (program, allargs);
  61
  62       fprintf (stderr, "Cannot exec %s: %s.\n", program,
  63                strerror (errno));
  64       fflush (stderr);
  65       _exit (0177);
  66     }
  67
  68   return pid;
  69 }
  70
  71 /* Attach to an inferior process.  */
  72
  73 int
  74 myattach (int pid)
  75 {
  76   if (ptrace (PTRACE_ATTACH, pid, 0, 0) != 0)
  77     {
  78       fprintf (stderr, "Cannot attach to process %d: %s (%d)\n", pid,
  79                errno < sys_nerr ? sys_errlist[errno] : "unknown error",
  80                errno);
  81       fflush (stderr);
  82       _exit (0177);
  83     }
  84
  85   return 0;
  86 }
  87
  88 /* Kill the inferior process.  Make us have no inferior.  */
  89
  90 void
  91 kill_inferior (void)
  92 {
  93   if (inferior_pid == 0)
  94     return;
  95   ptrace (PTRACE_KILL, inferior_pid, 0, 0);
  96   wait (0);
  97 }
  98
  99 /* Return nonzero if the given thread is still alive.  */
 100 int
 101 mythread_alive (int pid)
 102 {
 103   return 1;
 104 }
 105
 106 /* Wait for process, returns status */
 107
 108 unsigned char
 109 mywait (char *status)
 110 {
 111   int pid;
 112   union wait w;
 113
 114   enable_async_io ();
 115   pid = waitpid (inferior_pid, (int *)&w, 0);
 116   disable_async_io ();
 117   if (pid != inferior_pid)
 118     perror_with_name ("wait");
 119
 120   if (WIFEXITED (w))
 121     {
 122       fprintf (stderr, "\nChild exited with retcode = %x \n", WEXITSTATUS (w));
 123       *status = 'W';
 124       return ((unsigned char) WEXITSTATUS (w));
 125     }
 126   else if (!WIFSTOPPED (w))
 127     {
 128       fprintf (stderr, "\nChild terminated with signal = %x \n", WTERMSIG (w));
 129       *status = 'X';
 130       return ((unsigned char) WTERMSIG (w));
 131     }
 132
 133   fetch_inferior_registers (0);
 134
 135   *status = 'T';
 136   return ((unsigned char) WSTOPSIG (w));
 137 }
 138
 139 /* Resume execution of the inferior process.
 140    If STEP is nonzero, single-step it.
 141    If SIGNAL is nonzero, give it that signal.  */
 142
 143 void
 144 myresume (int step, int signal)
 145 {
 146   errno = 0;
 147   ptrace (step ? PTRACE_SINGLESTEP : PTRACE_CONT, inferior_pid, 1, signal);
 148   if (errno)
 149     perror_with_name ("ptrace");
 150 }
 151
 152 #define REGISTER_RAW_SIZE(regno) register_size((regno))
 153
 154 int
 155 register_addr (int regnum)
 156 {
 157   int addr;
 158
 159   if (regnum < 0 || regnum >= num_regs)
 160     error ("Invalid register number %d.", regnum);
 161
 162   addr = regmap[regnum];
 163   if (addr == -1)
 164     addr = 0;
 165
 166   return addr;
 167 }
 168
 169 /* Fetch one register.  */
 170
 171 static void
 172 fetch_register (int regno)
 173 {
 174   CORE_ADDR regaddr;
 175   register int i;
 176
 177   if (regno >= num_regs)
 178     return;
 179   if (cannot_fetch_register (regno))
 180     return;
 181
 182   regaddr = register_addr (regno);
 183   if (regaddr == -1)
 184     return;
 185   for (i = 0; i < REGISTER_RAW_SIZE (regno); i += sizeof (PTRACE_XFER_TYPE))
 186     {
 187       errno = 0;
 188       *(PTRACE_XFER_TYPE *) (register_data (regno) + i) =
 189         ptrace (PTRACE_PEEKUSER, inferior_pid, (PTRACE_ARG3_TYPE) regaddr, 0);
 190       regaddr += sizeof (PTRACE_XFER_TYPE);
 191       if (errno != 0)
 192         {
 193           /* Warning, not error, in case we are attached; sometimes the
 194              kernel doesn't let us at the registers.  */
 195           char *err = strerror (errno);
 196           char *msg = alloca (strlen (err) + 128);
 197           sprintf (msg, "reading register %d: %s", regno, err);
 198           error (msg);
 199           goto error_exit;
 200         }
 201     }
 202 error_exit:;
 203 }
 204
 205 /* Fetch all registers, or just one, from the child process.  */
 206
 207 void
 208 fetch_inferior_registers (int regno)
 209 {
 210   if (regno == -1 || regno == 0)
 211     for (regno = 0; regno < num_regs; regno++)
 212       fetch_register (regno);
 213   else
 214     fetch_register (regno);
 215 }
 216
 217 /* Store our register values back into the inferior.
 218    If REGNO is -1, do this for all registers.
 219    Otherwise, REGNO specifies which register (so we can save time).  */
 220
 221 void
 222 store_inferior_registers (int regno)
 223 {
 224   CORE_ADDR regaddr;
 225   int i;
 226
 227   if (regno >= 0)
 228     {
 229       if (regno >= num_regs)
 230         return;
 231
 232       if (cannot_store_register (regno))
 233         return;
 234
 235       regaddr = register_addr (regno);
 236       if (regaddr == -1)
 237         return;
 238       errno = 0;
 239       for (i = 0; i < REGISTER_RAW_SIZE (regno); i += sizeof (int))
 240         {
 241           errno = 0;
 242           ptrace (PTRACE_POKEUSER, inferior_pid, (PTRACE_ARG3_TYPE) regaddr,
 243                   *(int *) (register_data (regno) + i));
 244           if (errno != 0)
 245             {
 246               /* Warning, not error, in case we are attached; sometimes the
 247                  kernel doesn't let us at the registers.  */
 248               char *err = strerror (errno);
 249               char *msg = alloca (strlen (err) + 128);
 250               sprintf (msg, "writing register %d: %s",
 251                        regno, err);
 252               error (msg);
 253               return;
 254             }
 255           regaddr += sizeof (int);
 256         }
 257     }
 258   else
 259     for (regno = 0; regno < num_regs; regno++)
 260       store_inferior_registers (regno);
 261 }
 262
 263 /* Copy LEN bytes from inferior's memory starting at MEMADDR
 264    to debugger memory starting at MYADDR.  */
 265
 266 void
 267 read_inferior_memory (CORE_ADDR memaddr, char *myaddr, int len)
 268 {
 269   register int i;
 270   /* Round starting address down to longword boundary.  */
 271   register CORE_ADDR addr = memaddr & -(CORE_ADDR) sizeof (PTRACE_XFER_TYPE);
 272   /* Round ending address up; get number of longwords that makes.  */
 273   register int count
 274     = (((memaddr + len) - addr) + sizeof (PTRACE_XFER_TYPE) - 1)
 275       / sizeof (PTRACE_XFER_TYPE);
 276   /* Allocate buffer of that many longwords.  */
 277   register PTRACE_XFER_TYPE *buffer
 278     = (PTRACE_XFER_TYPE *) alloca (count * sizeof (PTRACE_XFER_TYPE));
 279
 280   /* Read all the longwords */
 281   for (i = 0; i < count; i++, addr += sizeof (PTRACE_XFER_TYPE))
 282     {
 283       buffer[i] = ptrace (PTRACE_PEEKTEXT, inferior_pid, (PTRACE_ARG3_TYPE) addr, 0);
 284     }
 285
 286   /* Copy appropriate bytes out of the buffer.  */
 287   memcpy (myaddr, (char *) buffer + (memaddr & (sizeof (PTRACE_XFER_TYPE) - 1)), len);
 288 }
 289
 290 /* Copy LEN bytes of data from debugger memory at MYADDR
 291    to inferior's memory at MEMADDR.
 292    On failure (cannot write the inferior)
 293    returns the value of errno.  */
 294
 295 int
 296 write_inferior_memory (CORE_ADDR memaddr, char *myaddr, int len)
 297 {
 298   register int i;
 299   /* Round starting address down to longword boundary.  */
 300   register CORE_ADDR addr = memaddr & -(CORE_ADDR) sizeof (PTRACE_XFER_TYPE);
 301   /* Round ending address up; get number of longwords that makes.  */
 302   register int count
 303   = (((memaddr + len) - addr) + sizeof (PTRACE_XFER_TYPE) - 1) / sizeof (PTRACE_XFER_TYPE);
 304   /* Allocate buffer of that many longwords.  */
 305   register PTRACE_XFER_TYPE *buffer = (PTRACE_XFER_TYPE *) alloca (count * sizeof (PTRACE_XFER_TYPE));
 306   extern int errno;
 307
 308   /* Fill start and end extra bytes of buffer with existing memory data.  */
 309
 310   buffer[0] = ptrace (PTRACE_PEEKTEXT, inferior_pid,
 311                       (PTRACE_ARG3_TYPE) addr, 0);
 312
 313   if (count > 1)
 314     {
 315       buffer[count - 1]
 316         = ptrace (PTRACE_PEEKTEXT, inferior_pid,
 317                   (PTRACE_ARG3_TYPE) (addr + (count - 1)
 318                                       * sizeof (PTRACE_XFER_TYPE)),
 319                   0);
 320     }
 321
 322   /* Copy data to be written over corresponding part of buffer */
 323
 324   memcpy ((char *) buffer + (memaddr & (sizeof (PTRACE_XFER_TYPE) - 1)), myaddr, len);
 325
 326   /* Write the entire buffer.  */
 327
 328   for (i = 0; i < count; i++, addr += sizeof (PTRACE_XFER_TYPE))
 329     {
 330       errno = 0;
 331       ptrace (PTRACE_POKETEXT, inferior_pid, (PTRACE_ARG3_TYPE) addr, buffer[i]);
 332       if (errno)
 333         return errno;
 334     }
 335
 336   return 0;
 337 }
 338 \f
 339 void
 340 initialize_low (void)
 341 {
 342   init_registers ();
 343 }