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 GDB 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 1, or (at your option)
   9 any later version.
  10
  11 GDB 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 GDB; see the file COPYING.  If not, write to
  18 the Free Software Foundation, 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 "param.h"
  33 #include "signals.h"
  34 #include "symtab.h"
  35 #include "frame.h"
  36 #include "inferior.h"
  37 #include "wait.h"
  38
  39 \f
  40 /* Random system calls, mostly no-ops to prevent link problems  */
  41
  42 ioctl (desc, code, arg)
  43 {}
  44
  45 int (* signal ()) ()
  46 {}
  47
  48 kill ()
  49 {}
  50
  51 getpid ()
  52 {
  53   return 0;
  54 }
  55
  56 sigsetmask ()
  57 {}
  58
  59 chdir ()
  60 {}
  61
  62 char *
  63 getwd (buf)
  64      char *buf;
  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 have_core_file_p ()
 342 {
 343   return 0;
 344 }
 345
 346 kill_command ()
 347 {
 348   inferior_pid = 0;
 349 }
 350
 351 terminal_inferior ()
 352 {}
 353
 354 terminal_ours ()
 355 {}
 356
 357 terminal_init_inferior ()
 358 {}
 359
 360 write_inferior_register ()
 361 {}
 362
 363 read_inferior_register ()
 364 {}
 365
 366 read_memory (memaddr, myaddr, len)
 367      CORE_ADDR memaddr;
 368      char *myaddr;
 369      int len;
 370 {
 371   bcopy (memaddr, myaddr, len);
 372 }
 373
 374 /* Always return 0 indicating success.  */
 375
 376 write_memory (memaddr, myaddr, len)
 377      CORE_ADDR memaddr;
 378      char *myaddr;
 379      int len;
 380 {
 381   bcopy (myaddr, memaddr, len);
 382   return 0;
 383 }
 384
 385 static REGISTER_TYPE saved_regs[NUM_REGS];
 386
 387 REGISTER_TYPE
 388 read_register (regno)
 389      int regno;
 390 {
 391   if (regno < 0 || regno >= NUM_REGS)
 392     error ("Register number %d out of range.", regno);
 393   return saved_regs[regno];
 394 }
 395
 396 void
 397 write_register (regno, value)
 398      int regno;
 399      REGISTER_TYPE value;
 400 {
 401   if (regno < 0 || regno >= NUM_REGS)
 402     error ("Register number %d out of range.", regno);
 403   saved_regs[regno] = value;
 404 }
 405 \f
 406 /* System calls needed in relation to running the "inferior".  */
 407
 408 vfork ()
 409 {
 410   /* Just appear to "succeed".  Say the inferior's pid is 1.  */
 411   return 1;
 412 }
 413
 414 /* These are called by code that normally runs in the inferior
 415    that has just been forked.  That code never runs, when standalone,
 416    and these definitions are so it will link without errors.  */
 417
 418 ptrace ()
 419 {}
 420
 421 setpgrp ()
 422 {}
 423
 424 execle ()
 425 {}
 426
 427 _exit ()
 428 {}
 429 \f
 430 /* Malloc calls these.  */
 431
 432 malloc_warning (str)
 433      char *str;
 434 {
 435   printf ("\n%s.\n\n", str);
 436 }
 437
 438 char *next_free;
 439 char *memory_limit;
 440
 441 char *
 442 sbrk (amount)
 443      int amount;
 444 {
 445   if (next_free + amount > memory_limit)
 446     return (char *) -1;
 447   next_free += amount;
 448   return next_free - amount;
 449 }
 450
 451 /* Various ways malloc might ask where end of memory is.  */
 452
 453 char *
 454 ulimit ()
 455 {
 456   return memory_limit;
 457 }
 458
 459 int
 460 vlimit ()
 461 {
 462   return memory_limit - next_free;
 463 }
 464
 465 getrlimit (addr)
 466      struct rlimit *addr;
 467 {
 468   addr->rlim_cur = memory_limit - next_free;
 469 }
 470 \f
 471 /* Context switching to and from program being debugged.  */
 472
 473 /* GDB calls here to run the user program.
 474    The frame pointer for this function is saved in
 475    gdb_stack by save_frame_pointer; then we restore
 476    all of the user program's registers, including PC and PS.  */
 477
 478 static int fault_code;
 479 static REGISTER_TYPE gdb_stack;
 480
 481 resume ()
 482 {
 483   REGISTER_TYPE restore[NUM_REGS];
 484
 485   PUSH_FRAME_PTR;
 486   save_frame_pointer ();
 487
 488   bcopy (saved_regs, restore, sizeof restore);
 489   POP_REGISTERS;
 490   /* Control does not drop through here!  */
 491 }
 492
 493 save_frame_pointer (val)
 494      CORE_ADDR val;
 495 {
 496   gdb_stack = val;
 497 }
 498
 499 /* Fault handlers call here, running in the user program stack.
 500    They must first push a fault code,
 501    old PC, old PS, and any other info about the fault.
 502    The exact format is machine-dependent and is known only
 503    in the definition of PUSH_REGISTERS.  */
 504
 505 fault ()
 506 {
 507   /* Transfer all registers and fault code to the stack
 508      in canonical order: registers in order of GDB register number,
 509      followed by fault code.  */
 510   PUSH_REGISTERS;
 511
 512   /* Transfer them to saved_regs and fault_code.  */
 513   save_registers ();
 514
 515   restore_gdb ();
 516   /* Control does not reach here */
 517 }
 518
 519 restore_gdb ()
 520 {
 521   CORE_ADDR new_fp = gdb_stack;
 522   /* Switch to GDB's stack  */
 523   POP_FRAME_PTR;
 524   /* Return from the function `resume'.  */
 525 }
 526
 527 /* Assuming register contents and fault code have been pushed on the stack as
 528    arguments to this function, copy them into the standard place
 529    for the program's registers while GDB is running.  */
 530
 531 save_registers (firstreg)
 532      int firstreg;
 533 {
 534   bcopy (&firstreg, saved_regs, sizeof saved_regs);
 535   fault_code = (&firstreg)[NUM_REGS];
 536 }
 537
 538 /* Store into the structure such as `wait' would return
 539    the information on why the program faulted,
 540    converted into a machine-independent signal number.  */
 541
 542 static int fault_table[] = FAULT_TABLE;
 543
 544 int
 545 wait (w)
 546      WAITTYPE *w;
 547 {
 548   WSETSTOP (*w, fault_table[fault_code / FAULT_CODE_UNITS]);
 549   return inferior_pid;
 550 }
 551 \f
 552 /* Allocate a big space in which files for kdb to read will be stored.
 553    Whatever is left is where malloc can allocate storage.
 554
 555    Initialize it, so that there will be space in the executable file
 556    for it.  Then the files can be put into kdb by writing them into
 557    kdb's executable file.  */
 558
 559 /* The default size is as much space as we expect to be available
 560    for kdb to use!  */
 561
 562 #ifndef HEAP_SIZE
 563 #define HEAP_SIZE 400000
 564 #endif
 565
 566 char heap[HEAP_SIZE] = {0};
 567
 568 #ifndef STACK_SIZE
 569 #define STACK_SIZE 100000
 570 #endif
 571
 572 int kdb_stack_beg[STACK_SIZE / sizeof (int)];
 573 int kdb_stack_end;
 574
 575 _initialize_standalone ()
 576 {
 577   register char *next;
 578
 579   /* Find start of data on files.  */
 580
 581   files_start = heap;
 582
 583   /* Find the end of the data on files.  */
 584
 585   for (next - files_start; * (int *) next;
 586        next += * (int *) next)
 587     {}
 588
 589   /* That is where free storage starts for sbrk to give out.  */
 590   next_free = next;
 591
 592   memory_limit = heap + sizeof heap;
 593 }
 594