gdb/gdbserver/low-linux.c

   1 /* Low level interface to ptrace, for the remote server for GDB.
   2    Copyright (C) 1995, 1996 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., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
  19
  20 #include "defs.h"
  21 #include <sys/wait.h>
  22 #include "frame.h"
  23 #include "inferior.h"
  24
  25 #include <stdio.h>
  26 #include <sys/param.h>
  27 #include <sys/dir.h>
  28 #include <sys/user.h>
  29 #include <signal.h>
  30 #include <sys/ioctl.h>
  31 #if 0
  32 #include <sgtty.h>
  33 #endif
  34 #include <fcntl.h>
  35
  36 /***************Begin MY defs*********************/
  37 int quit_flag = 0;
  38 char registers[REGISTER_BYTES];
  39
  40 /* Index within `registers' of the first byte of the space for
  41    register N.  */
  42
  43
  44 char buf2[MAX_REGISTER_RAW_SIZE];
  45 /***************End MY defs*********************/
  46
  47 #include <sys/ptrace.h>
  48 #if 0
  49 #include <machine/reg.h>
  50 #endif
  51
  52 extern char **environ;
  53 extern int errno;
  54 extern int inferior_pid;
  55 void quit (), perror_with_name ();
  56 int query ();
  57
  58 /* Start an inferior process and returns its pid.
  59    ALLARGS is a vector of program-name and args.
  60    ENV is the environment vector to pass.  */
  61
  62 int
  63 create_inferior (program, allargs)
  64      char *program;
  65      char **allargs;
  66 {
  67   int pid;
  68
  69   pid = fork ();
  70   if (pid < 0)
  71     perror_with_name ("fork");
  72
  73   if (pid == 0)
  74     {
  75       ptrace (PTRACE_TRACEME, 0, 0, 0);
  76
  77       execv (program, allargs);
  78
  79       fprintf (stderr, "Cannot exec %s: %s.\n", program,
  80                errno < sys_nerr ? sys_errlist[errno] : "unknown error");
  81       fflush (stderr);
  82       _exit (0177);
  83     }
  84
  85   return pid;
  86 }
  87
  88 /* Kill the inferior process.  Make us have no inferior.  */
  89
  90 void
  91 kill_inferior ()
  92 {
  93   if (inferior_pid == 0)
  94     return;
  95   ptrace (PTRACE_KILL, inferior_pid, 0, 0);
  96   wait (0);
  97   /*************inferior_died ();****VK**************/
  98 }
  99
 100 /* Return nonzero if the given thread is still alive.  */
 101 int
 102 mythread_alive (pid)
 103      int pid;
 104 {
 105   return 1;
 106 }
 107
 108 /* Wait for process, returns status */
 109
 110 unsigned char
 111 mywait (status)
 112      char *status;
 113 {
 114   int pid;
 115   union wait w;
 116
 117   pid = wait (&w);
 118   if (pid != inferior_pid)
 119     perror_with_name ("wait");
 120
 121   if (WIFEXITED (w))
 122     {
 123       fprintf (stderr, "\nChild exited with retcode = %x \n", WEXITSTATUS (w));
 124       *status = 'W';
 125       return ((unsigned char) WEXITSTATUS (w));
 126     }
 127   else if (!WIFSTOPPED (w))
 128     {
 129       fprintf (stderr, "\nChild terminated with signal = %x \n", WTERMSIG (w));
 130       *status = 'X';
 131       return ((unsigned char) WTERMSIG (w));
 132     }
 133
 134   fetch_inferior_registers (0);
 135
 136   *status = 'T';
 137   return ((unsigned char) WSTOPSIG (w));
 138 }
 139
 140 /* Resume execution of the inferior process.
 141    If STEP is nonzero, single-step it.
 142    If SIGNAL is nonzero, give it that signal.  */
 143
 144 void
 145 myresume (step, signal)
 146      int step;
 147      int signal;
 148 {
 149   errno = 0;
 150   ptrace (step ? PTRACE_SINGLESTEP : PTRACE_CONT, inferior_pid, 1, signal);
 151   if (errno)
 152     perror_with_name ("ptrace");
 153 }
 154
 155
 156 #if !defined (offsetof)
 157 #define offsetof(TYPE, MEMBER) ((unsigned long) &((TYPE *)0)->MEMBER)
 158 #endif
 159
 160 /* U_REGS_OFFSET is the offset of the registers within the u area.  */
 161 #if !defined (U_REGS_OFFSET)
 162 #define U_REGS_OFFSET \
 163   ptrace (PT_READ_U, inferior_pid, \
 164           (PTRACE_ARG3_TYPE) (offsetof (struct user, u_ar0)), 0) \
 165     - KERNEL_U_ADDR
 166 #endif
 167
 168 /* this table must line up with REGISTER_NAMES in tm-i386v.h */
 169 /* symbols like 'EAX' come from <sys/reg.h> */
 170 static int regmap[] =
 171 {
 172   EAX, ECX, EDX, EBX,
 173   UESP, EBP, ESI, EDI,
 174   EIP, EFL, CS, SS,
 175   DS, ES, FS, GS,
 176 };
 177
 178 int
 179 i386_register_u_addr (blockend, regnum)
 180      int blockend;
 181      int regnum;
 182 {
 183 #if 0
 184   /* this will be needed if fp registers are reinstated */
 185   /* for now, you can look at them with 'info float'
 186    * sys5 wont let you change them with ptrace anyway
 187    */
 188   if (regnum >= FP0_REGNUM && regnum <= FP7_REGNUM)
 189     {
 190       int ubase, fpstate;
 191       struct user u;
 192       ubase = blockend + 4 * (SS + 1) - KSTKSZ;
 193       fpstate = ubase + ((char *)&u.u_fpstate - (char *)&u);
 194       return (fpstate + 0x1c + 10 * (regnum - FP0_REGNUM));
 195     }
 196   else
 197 #endif
 198     return (blockend + 4 * regmap[regnum]);
 199
 200 }
 201
 202 CORE_ADDR
 203 register_addr (regno, blockend)
 204      int regno;
 205      CORE_ADDR blockend;
 206 {
 207   CORE_ADDR addr;
 208
 209   if (regno < 0 || regno >= ARCH_NUM_REGS)
 210     error ("Invalid register number %d.", regno);
 211
 212   REGISTER_U_ADDR (addr, blockend, regno);
 213
 214   return addr;
 215 }
 216
 217 /* Fetch one register.  */
 218
 219 static void
 220 fetch_register (regno)
 221      int regno;
 222 {
 223   register unsigned int regaddr;
 224   char buf[MAX_REGISTER_RAW_SIZE];
 225   register int i;
 226
 227   /* Offset of registers within the u area.  */
 228   unsigned int offset;
 229
 230   offset = U_REGS_OFFSET;
 231
 232   regaddr = register_addr (regno, offset);
 233   for (i = 0; i < REGISTER_RAW_SIZE (regno); i += sizeof (int))
 234     {
 235       errno = 0;
 236       *(int *) &registers[ regno * 4 + i] = ptrace (PTRACE_PEEKUSR, inferior_pid,
 237                                  (PTRACE_ARG3_TYPE) regaddr, 0);
 238       regaddr += sizeof (int);
 239       if (errno != 0)
 240         {
 241           /* Warning, not error, in case we are attached; sometimes the
 242              kernel doesn't let us at the registers.  */
 243           char *err = strerror (errno);
 244           char *msg = alloca (strlen (err) + 128);
 245           sprintf (msg, "reading register %d: %s", regno, err);
 246           error (msg);
 247           goto error_exit;
 248         }
 249     }
 250  error_exit:;
 251 }
 252
 253 /* Fetch all registers, or just one, from the child process.  */
 254
 255 void
 256 fetch_inferior_registers (regno)
 257      int regno;
 258 {
 259   if (regno == -1 || regno == 0)
 260     for (regno = 0; regno < NUM_REGS-NUM_FREGS; regno++)
 261       fetch_register (regno);
 262   else
 263     fetch_register (regno);
 264 }
 265
 266 /* Store our register values back into the inferior.
 267    If REGNO is -1, do this for all registers.
 268    Otherwise, REGNO specifies which register (so we can save time).  */
 269
 270 void
 271 store_inferior_registers (regno)
 272      int regno;
 273 {
 274   register unsigned int regaddr;
 275   char buf[80];
 276   register int i;
 277   unsigned int offset = U_REGS_OFFSET;
 278   int scratch;
 279
 280   if (regno >= 0)
 281     {
 282 #if 0
 283       if (CANNOT_STORE_REGISTER (regno))
 284         return;
 285 #endif
 286       regaddr = register_addr (regno, offset);
 287       errno = 0;
 288 #if 0
 289       if (regno == PCOQ_HEAD_REGNUM || regno == PCOQ_TAIL_REGNUM)
 290         {
 291           scratch = *(int *) &registers[REGISTER_BYTE (regno)] | 0x3;
 292           ptrace (PT_WUREGS, inferior_pid, (PTRACE_ARG3_TYPE) regaddr,
 293                   scratch, 0);
 294           if (errno != 0)
 295             {
 296               /* Error, even if attached.  Failing to write these two
 297                  registers is pretty serious.  */
 298               sprintf (buf, "writing register number %d", regno);
 299               perror_with_name (buf);
 300             }
 301         }
 302       else
 303 #endif
 304         for (i = 0; i < REGISTER_RAW_SIZE (regno); i += sizeof(int))
 305           {
 306             errno = 0;
 307             ptrace (PTRACE_POKEUSR, inferior_pid, (PTRACE_ARG3_TYPE) regaddr,
 308                     *(int *) &registers[REGISTER_BYTE (regno) + i]);
 309             if (errno != 0)
 310               {
 311                 /* Warning, not error, in case we are attached; sometimes the
 312                    kernel doesn't let us at the registers.  */
 313                 char *err = strerror (errno);
 314                 char *msg = alloca (strlen (err) + 128);
 315                 sprintf (msg, "writing register %d: %s",
 316                          regno, err);
 317                 error (msg);
 318                 return;
 319               }
 320             regaddr += sizeof(int);
 321           }
 322     }
 323   else
 324     for (regno = 0; regno < NUM_REGS-NUM_FREGS; regno++)
 325       store_inferior_registers (regno);
 326 }
 327
 328 /* NOTE! I tried using PTRACE_READDATA, etc., to read and write memory
 329    in the NEW_SUN_PTRACE case.
 330    It ought to be straightforward.  But it appears that writing did
 331    not write the data that I specified.  I cannot understand where
 332    it got the data that it actually did write.  */
 333
 334 /* Copy LEN bytes from inferior's memory starting at MEMADDR
 335    to debugger memory starting at MYADDR.  */
 336
 337 read_inferior_memory (memaddr, myaddr, len)
 338      CORE_ADDR memaddr;
 339      char *myaddr;
 340      int len;
 341 {
 342   register int i;
 343   /* Round starting address down to longword boundary.  */
 344   register CORE_ADDR addr = memaddr & -sizeof (int);
 345   /* Round ending address up; get number of longwords that makes.  */
 346   register int count
 347   = (((memaddr + len) - addr) + sizeof (int) - 1) / sizeof (int);
 348   /* Allocate buffer of that many longwords.  */
 349   register int *buffer = (int *) alloca (count * sizeof (int));
 350
 351   /* Read all the longwords */
 352   for (i = 0; i < count; i++, addr += sizeof (int))
 353     {
 354       buffer[i] = ptrace (PTRACE_PEEKTEXT, inferior_pid, addr, 0);
 355     }
 356
 357   /* Copy appropriate bytes out of the buffer.  */
 358   memcpy (myaddr, (char *) buffer + (memaddr & (sizeof (int) - 1)), len);
 359 }
 360
 361 /* Copy LEN bytes of data from debugger memory at MYADDR
 362    to inferior's memory at MEMADDR.
 363    On failure (cannot write the inferior)
 364    returns the value of errno.  */
 365
 366 int
 367 write_inferior_memory (memaddr, myaddr, len)
 368      CORE_ADDR memaddr;
 369      char *myaddr;
 370      int len;
 371 {
 372   register int i;
 373   /* Round starting address down to longword boundary.  */
 374   register CORE_ADDR addr = memaddr & -sizeof (int);
 375   /* Round ending address up; get number of longwords that makes.  */
 376   register int count
 377   = (((memaddr + len) - addr) + sizeof (int) - 1) / sizeof (int);
 378   /* Allocate buffer of that many longwords.  */
 379   register int *buffer = (int *) alloca (count * sizeof (int));
 380   extern int errno;
 381
 382   /* Fill start and end extra bytes of buffer with existing memory data.  */
 383
 384   buffer[0] = ptrace (PTRACE_PEEKTEXT, inferior_pid, addr, 0);
 385
 386   if (count > 1)
 387     {
 388       buffer[count - 1]
 389         = ptrace (PTRACE_PEEKTEXT, inferior_pid,
 390                   addr + (count - 1) * sizeof (int), 0);
 391     }
 392
 393   /* Copy data to be written over corresponding part of buffer */
 394
 395   memcpy ((char *) buffer + (memaddr & (sizeof (int) - 1)), myaddr, len);
 396
 397   /* Write the entire buffer.  */
 398
 399   for (i = 0; i < count; i++, addr += sizeof (int))
 400     {
 401       errno = 0;
 402       ptrace (PTRACE_POKETEXT, inferior_pid, addr, buffer[i]);
 403       if (errno)
 404         return errno;
 405     }
 406
 407   return 0;
 408 }
 409 \f
 410 void
 411 initialize ()
 412 {
 413   inferior_pid = 0;
 414 }
 415
 416 int
 417 have_inferior_p ()
 418 {
 419   return inferior_pid != 0;
 420 }