gdb/mem-break.c

   1 /* Simulate breakpoints by patching locations in the target system, for GDB.
   2    Copyright 1990, 1991 Free Software Foundation, Inc.
   3    Contributed by Cygnus Support.  Written by John Gilmore.
   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., 675 Mass Ave, Cambridge, MA 02139, USA.  */
  20
  21 #include "defs.h"
  22
  23 #ifdef BREAKPOINT
  24 /* This file is only useful if BREAKPOINT is set.  If not, we punt.  */
  25
  26 #include <stdio.h>
  27 #include "breakpoint.h"
  28 #include "inferior.h"
  29 #include "target.h"
  30
  31 /* This is the sequence of bytes we insert for a breakpoint.  On some
  32    machines, breakpoints are handled by the target environment and we
  33    don't have to worry about them here.  */
  34
  35 static char break_insn[] = BREAKPOINT;
  36
  37 /* This is only to check that BREAKPOINT fits in BREAKPOINT_MAX bytes.  */
  38
  39 static char check_break_insn_size[BREAKPOINT_MAX] = BREAKPOINT;
  40
  41 /* Insert a breakpoint on machines that don't have any better breakpoint
  42    support.  We read the contents of the target location and stash it,
  43    then overwrite it with a breakpoint instruction.  ADDR is the target
  44    location in the target machine.  CONTENTS_CACHE is a pointer to
  45    memory allocated for saving the target contents.  It is guaranteed
  46    by the caller to be long enough to save sizeof BREAKPOINT bytes.
  47    FIXME: This size is target_arch dependent and should be available in
  48    the target_arch transfer vector, if we ever have one...  */
  49
  50 int
  51 memory_insert_breakpoint (addr, contents_cache)
  52      CORE_ADDR addr;
  53      char *contents_cache;
  54 {
  55   int val;
  56
  57   val = target_read_memory (addr, contents_cache, sizeof break_insn);
  58
  59   if (val == 0)
  60     val = target_write_memory (addr, break_insn, sizeof break_insn);
  61
  62   return val;
  63 }
  64
  65
  66 int
  67 memory_remove_breakpoint (addr, contents_cache)
  68      CORE_ADDR addr;
  69      char *contents_cache;
  70 {
  71   return target_write_memory (addr, contents_cache, sizeof break_insn);
  72 }
  73
  74
  75 int memory_breakpoint_size = sizeof (break_insn);
  76
  77
  78 #else  /* BREAKPOINT */
  79
  80 char nogo[] = "Breakpoints not implemented for this target.";
  81
  82 int
  83 memory_insert_breakpoint (addr, contents_cache)
  84      CORE_ADDR addr;
  85      char *contents_cache;
  86 {
  87   error (nogo);
  88   return 0;     /* lint */
  89 }
  90
  91 int
  92 memory_remove_breakpoint (addr, contents_cache)
  93      CORE_ADDR addr;
  94      char *contents_cache;
  95 {
  96   error (nogo);
  97   return 0;     /* lint */
  98 }
  99
 100 int memory_breakpoint_size = -1;
 101
 102 #endif /* BREAKPOINT */