gdb/standalone.c

   1 /* Interface to bare machine for GDB running as kernel debugger.
   2    Copyright (C) 1986, 1989, 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 <sys/ioctl.h>
  22 #include <errno.h>
  23 #include <sys/types.h>
  24 #include <sys/stat.h>
  25
  26 #if defined (SIGTSTP) && defined (SIGIO)
  27 #include <sys/time.h>
  28 #include <sys/resource.h>
  29 #endif /* SIGTSTP and SIGIO defined (must be 4.2) */
  30
  31 #include "defs.h"
  32 #include "signals.h"
  33 #include "symtab.h"
  34 #include "frame.h"
  35 #include "inferior.h"
  36 #include "wait.h"
  37
  38 \f
  39 /* Random system calls, mostly no-ops to prevent link problems  */
  40
  41 ioctl (desc, code, arg)
  42 {}
  43
  44 int (* signal ()) ()
  45 {}
  46
  47 kill ()
  48 {}
  49
  50 getpid ()
  51 {
  52   return 0;
  53 }
  54
  55 sigsetmask ()
  56 {}
  57
  58 chdir ()
  59 {}
  60
  61 char *
  62 getcwd (buf, len)
  63      char *buf;
  64      unsigned int len;
  65 {
  66   buf[0] = '/';
  67   buf[1] = 0;
  68   return buf;
  69 }
  70
  71 /* Used to check for existence of .gdbinit.  Say no.  */
  72
  73 access ()
  74 {
  75   return -1;
  76 }
  77
  78 exit ()
  79 {
  80   error ("Fatal error; restarting.");
  81 }
  82 \f
  83 /* Reading "files".  The contents of some files are written into kdb's
  84    data area before it is run.  These files are used to contain the
  85    symbol table for kdb to load, and the source files (in case the
  86    kdb user wants to print them).  The symbols are stored in a file
  87    named "kdb-symbols" in a.out format (except that all the text and
  88    data have been stripped to save room).
  89
  90    The files are stored in the following format:
  91    int     number of bytes of data for this file, including these four.
  92    char[]  name of the file, ending with a null.
  93    padding to multiple of 4 boundary.
  94    char[]  file contents.  The length can be deduced from what was
  95            specified before.  There is no terminating null here.
  96
  97    If the int at the front is zero, it means there are no more files.
  98
  99    Opening a file in kdb returns a nonzero value to indicate success,
 100    but the value does not matter.  Only one file can be open, and only
 101    for reading.  All the primitives for input from the file know
 102    which file is open and ignore what is specified for the descriptor
 103    or for the stdio stream.
 104
 105    Input with fgetc can be done either on the file that is open
 106    or on stdin (which reads from the terminal through tty_input ()  */
 107
 108 /* Address of data for the files stored in format described above.  */
 109 char *files_start;
 110
 111 /* The file stream currently open:  */
 112
 113 char *sourcebeg;                /* beginning of contents */
 114 int sourcesize;                 /* size of contents */
 115 char *sourceptr;                /* current read pointer */
 116 int sourceleft;                 /* number of bytes to eof */
 117
 118 /* "descriptor" for the file now open.
 119    Incremented at each close.
 120    If specified descriptor does not match this,
 121    it means the program is trying to use a closed descriptor.
 122    We report an error for that.  */
 123
 124 int sourcedesc;
 125
 126 open (filename, modes)
 127      char *filename;
 128      int modes;
 129 {
 130   register char *next;
 131
 132   if (modes)
 133     {
 134       errno = EROFS;
 135       return -1;
 136     }
 137
 138   if (sourceptr)
 139     {
 140       errno = EMFILE;
 141       return -1;
 142     }
 143
 144   for (next - files_start; * (int *) next;
 145        next += * (int *) next)
 146     {
 147       if (!STRCMP (next + 4, filename))
 148         {
 149           sourcebeg = next + 4 + strlen (next + 4) + 1;
 150           sourcebeg = (char *) (((int) sourcebeg + 3) & (-4));
 151           sourceptr = sourcebeg;
 152           sourcesize = next + * (int *) next - sourceptr;
 153           sourceleft = sourcesize;
 154           return sourcedesc;
 155         }
 156     }
 157   return 0;
 158 }
 159
 160 close (desc)
 161      int desc;
 162 {
 163   sourceptr = 0;
 164   sourcedesc++;
 165   /* Don't let sourcedesc get big enough to be confused with stdin.  */
 166   if (sourcedesc == 100)
 167     sourcedesc = 5;
 168 }
 169
 170 FILE *
 171 fopen (filename, modes)
 172      char *filename;
 173      char *modes;
 174 {
 175   return (FILE *) open (filename, *modes == 'w');
 176 }
 177
 178 FILE *
 179 fdopen (desc)
 180      int desc;
 181 {
 182   return (FILE *) desc;
 183 }
 184
 185 fclose (desc)
 186      int desc;
 187 {
 188   close (desc);
 189 }
 190
 191 fstat (desc, statbuf)
 192      struct stat *statbuf;
 193 {
 194   if (desc != sourcedesc)
 195     {
 196       errno = EBADF;
 197       return -1;
 198     }
 199   statbuf->st_size = sourcesize;
 200 }
 201
 202 myread (desc, destptr, size, filename)
 203      int desc;
 204      char *destptr;
 205      int size;
 206      char *filename;
 207 {
 208   int len = min (sourceleft, size);
 209
 210   if (desc != sourcedesc)
 211     {
 212       errno = EBADF;
 213       return -1;
 214     }
 215
 216   bcopy (sourceptr, destptr, len);
 217   sourceleft -= len;
 218   return len;
 219 }
 220
 221 int
 222 fread (bufp, numelts, eltsize, stream)
 223 {
 224   register int elts = min (numelts, sourceleft / eltsize);
 225   register int len = elts * eltsize;
 226
 227   if (stream != sourcedesc)
 228     {
 229       errno = EBADF;
 230       return -1;
 231     }
 232
 233   bcopy (sourceptr, bufp, len);
 234   sourceleft -= len;
 235   return elts;
 236 }
 237
 238 int
 239 fgetc (desc)
 240      int desc;
 241 {
 242
 243   if (desc == (int) stdin)
 244     return tty_input ();
 245
 246   if (desc != sourcedesc)
 247     {
 248       errno = EBADF;
 249       return -1;
 250     }
 251
 252   if (sourceleft-- <= 0)
 253     return EOF;
 254   return *sourceptr++;
 255 }
 256
 257 lseek (desc, pos)
 258      int desc;
 259      int pos;
 260 {
 261
 262   if (desc != sourcedesc)
 263     {
 264       errno = EBADF;
 265       return -1;
 266     }
 267
 268   if (pos < 0 || pos > sourcesize)
 269     {
 270       errno = EINVAL;
 271       return -1;
 272     }
 273
 274   sourceptr = sourcebeg + pos;
 275   sourceleft = sourcesize - pos;
 276 }
 277 \f
 278 /* Output in kdb can go only to the terminal, so the stream
 279    specified may be ignored.  */
 280
 281 printf (a1, a2, a3, a4, a5, a6, a7, a8, a9)
 282 {
 283   char buffer[1024];
 284   sprintf (buffer, a1, a2, a3, a4, a5, a6, a7, a8, a9);
 285   display_string (buffer);
 286 }
 287
 288 fprintf (ign, a1, a2, a3, a4, a5, a6, a7, a8, a9)
 289 {
 290   char buffer[1024];
 291   sprintf (buffer, a1, a2, a3, a4, a5, a6, a7, a8, a9);
 292   display_string (buffer);
 293 }
 294
 295 fwrite (buf, numelts, size, stream)
 296      register char *buf;
 297      int numelts, size;
 298 {
 299   register int i = numelts * size;
 300   while (i-- > 0)
 301     fputc (*buf++, stream);
 302 }
 303
 304 fputc (c, ign)
 305 {
 306   char buf[2];
 307   buf[0] = c;
 308   buf[1] = 0;
 309   display_string (buf);
 310 }
 311
 312 /* sprintf refers to this, but loading this from the
 313    library would cause fflush to be loaded from it too.
 314    In fact there should be no need to call this (I hope).  */
 315
 316 _flsbuf ()
 317 {
 318   error ("_flsbuf was actually called.");
 319 }
 320
 321 fflush (ign)
 322 {
 323 }
 324 \f
 325 /* Entries into core and inflow, needed only to make things link ok.  */
 326
 327 exec_file_command ()
 328 {}
 329
 330 core_file_command ()
 331 {}
 332
 333 char *
 334 get_exec_file (err)
 335      int err;
 336 {
 337   /* Makes one printout look reasonable; value does not matter otherwise.  */
 338   return "run";
 339 }
 340
 341 /* Nonzero if there is a core file.  */
 342
 343 have_core_file_p ()
 344 {
 345   return 0;
 346 }
 347
 348 kill_command ()
 349 {
 350   inferior_pid = 0;
 351 }
 352
 353 terminal_inferior ()
 354 {}
 355
 356 terminal_ours ()
 357 {}
 358
 359 terminal_init_inferior ()
 360 {}
 361
 362 write_inferior_register ()
 363 {}
 364
 365 read_inferior_register ()
 366 {}
 367
 368 read_memory (memaddr, myaddr, len)
 369      CORE_ADDR memaddr;
 370      char *myaddr;
 371      int len;
 372 {
 373   bcopy (memaddr, myaddr, len);
 374 }
 375
 376 /* Always return 0 indicating success.  */
 377
 378 write_memory (memaddr, myaddr, len)
 379      CORE_ADDR memaddr;
 380      char *myaddr;
 381      int len;
 382 {
 383   bcopy (myaddr, memaddr, len);
 384   return 0;
 385 }
 386
 387 static REGISTER_TYPE saved_regs[NUM_REGS];
 388
 389 REGISTER_TYPE
 390 read_register (regno)
 391      int regno;
 392 {
 393   if (regno < 0 || regno >= NUM_REGS)
 394     error ("Register number %d out of range.", regno);
 395   return saved_regs[regno];
 396 }
 397
 398 void
 399 write_register (regno, value)
 400      int regno;
 401      REGISTER_TYPE value;
 402 {
 403   if (regno < 0 || regno >= NUM_REGS)
 404     error ("Register number %d out of range.", regno);
 405   saved_regs[regno] = value;
 406 }
 407 \f
 408 /* System calls needed in relation to running the "inferior".  */
 409
 410 vfork ()
 411 {
 412   /* Just appear to "succeed".  Say the inferior's pid is 1.  */
 413   return 1;
 414 }
 415
 416 /* These are called by code that normally runs in the inferior
 417    that has just been forked.  That code never runs, when standalone,
 418    and these definitions are so it will link without errors.  */
 419
 420 ptrace ()
 421 {}
 422
 423 setpgrp ()
 424 {}
 425
 426 execle ()
 427 {}
 428
 429 _exit ()
 430 {}
 431 \f
 432 /* Malloc calls these.  */
 433
 434 malloc_warning (str)
 435      char *str;
 436 {
 437   printf ("\n%s.\n\n", str);
 438 }
 439
 440 char *next_free;
 441 char *memory_limit;
 442
 443 char *
 444 sbrk (amount)
 445      int amount;
 446 {
 447   if (next_free + amount > memory_limit)
 448     return (char *) -1;
 449   next_free += amount;
 450   return next_free - amount;
 451 }
 452
 453 /* Various ways malloc might ask where end of memory is.  */
 454
 455 char *
 456 ulimit ()
 457 {
 458   return memory_limit;
 459 }
 460
 461 int
 462 vlimit ()
 463 {
 464   return memory_limit - next_free;
 465 }
 466
 467 getrlimit (addr)
 468      struct rlimit *addr;
 469 {
 470   addr->rlim_cur = memory_limit - next_free;
 471 }
 472 \f
 473 /* Context switching to and from program being debugged.  */
 474
 475 /* GDB calls here to run the user program.
 476    The frame pointer for this function is saved in
 477    gdb_stack by save_frame_pointer; then we restore
 478    all of the user program's registers, including PC and PS.  */
 479
 480 static int fault_code;
 481 static REGISTER_TYPE gdb_stack;
 482
 483 resume ()
 484 {
 485   REGISTER_TYPE restore[NUM_REGS];
 486
 487   PUSH_FRAME_PTR;
 488   save_frame_pointer ();
 489
 490   bcopy (saved_regs, restore, sizeof restore);
 491   POP_REGISTERS;
 492   /* Control does not drop through here!  */
 493 }
 494
 495 save_frame_pointer (val)
 496      CORE_ADDR val;
 497 {
 498   gdb_stack = val;
 499 }
 500
 501 /* Fault handlers call here, running in the user program stack.
 502    They must first push a fault code,
 503    old PC, old PS, and any other info about the fault.
 504    The exact format is machine-dependent and is known only
 505    in the definition of PUSH_REGISTERS.  */
 506
 507 fault ()
 508 {
 509   /* Transfer all registers and fault code to the stack
 510      in canonical order: registers in order of GDB register number,
 511      followed by fault code.  */
 512   PUSH_REGISTERS;
 513
 514   /* Transfer them to saved_regs and fault_code.  */
 515   save_registers ();
 516
 517   restore_gdb ();
 518   /* Control does not reach here */
 519 }
 520
 521 restore_gdb ()
 522 {
 523   CORE_ADDR new_fp = gdb_stack;
 524   /* Switch to GDB's stack  */
 525   POP_FRAME_PTR;
 526   /* Return from the function `resume'.  */
 527 }
 528
 529 /* Assuming register contents and fault code have been pushed on the stack as
 530    arguments to this function, copy them into the standard place
 531    for the program's registers while GDB is running.  */
 532
 533 save_registers (firstreg)
 534      int firstreg;
 535 {
 536   bcopy (&firstreg, saved_regs, sizeof saved_regs);
 537   fault_code = (&firstreg)[NUM_REGS];
 538 }
 539
 540 /* Store into the structure such as `wait' would return
 541    the information on why the program faulted,
 542    converted into a machine-independent signal number.  */
 543
 544 static int fault_table[] = FAULT_TABLE;
 545
 546 int
 547 wait (w)
 548      WAITTYPE *w;
 549 {
 550   WSETSTOP (*w, fault_table[fault_code / FAULT_CODE_UNITS]);
 551   return inferior_pid;
 552 }
 553 \f
 554 /* Allocate a big space in which files for kdb to read will be stored.
 555    Whatever is left is where malloc can allocate storage.
 556
 557    Initialize it, so that there will be space in the executable file
 558    for it.  Then the files can be put into kdb by writing them into
 559    kdb's executable file.  */
 560
 561 /* The default size is as much space as we expect to be available
 562    for kdb to use!  */
 563
 564 #ifndef HEAP_SIZE
 565 #define HEAP_SIZE 400000
 566 #endif
 567
 568 char heap[HEAP_SIZE] = {0};
 569
 570 #ifndef STACK_SIZE
 571 #define STACK_SIZE 100000
 572 #endif
 573
 574 int kdb_stack_beg[STACK_SIZE / sizeof (int)];
 575 int kdb_stack_end;
 576
 577 _initialize_standalone ()
 578 {
 579   register char *next;
 580
 581   /* Find start of data on files.  */
 582
 583   files_start = heap;
 584
 585   /* Find the end of the data on files.  */
 586
 587   for (next - files_start; * (int *) next;
 588        next += * (int *) next)
 589     {}
 590
 591   /* That is where free storage starts for sbrk to give out.  */
 592   next_free = next;
 593
 594   memory_limit = heap + sizeof heap;
 595 }
 596