gdb/mem-break.c

   1 /* Simulate breakpoints by patching locations in the target system, for GDB.
   2
   3    Copyright (C) 1990, 1991, 1992, 1993, 1995, 1997, 1998, 1999, 2000, 2002,
   4    2007 Free Software Foundation, Inc.
   5
   6    Contributed by Cygnus Support.  Written by John Gilmore.
   7
   8    This file is part of GDB.
   9
  10    This program is free software; you can redistribute it and/or modify
  11    it under the terms of the GNU General Public License as published by
  12    the Free Software Foundation; either version 2 of the License, or
  13    (at your option) any later version.
  14
  15    This program is distributed in the hope that it will be useful,
  16    but WITHOUT ANY WARRANTY; without even the implied warranty of
  17    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18    GNU General Public License for more details.
  19
  20    You should have received a copy of the GNU General Public License
  21    along with this program; if not, write to the Free Software
  22    Foundation, Inc., 51 Franklin Street, Fifth Floor,
  23    Boston, MA 02110-1301, USA.  */
  24
  25 #include "defs.h"
  26
  27 /* This file is only useful if BREAKPOINT_FROM_PC is set.  If not, we
  28    punt.  */
  29
  30 #include "symtab.h"
  31 #include "breakpoint.h"
  32 #include "inferior.h"
  33 #include "target.h"
  34
  35
  36 /* Insert a breakpoint on targets that don't have any better
  37    breakpoint support.  We read the contents of the target location
  38    and stash it, then overwrite it with a breakpoint instruction.
  39    BP_TGT->placed_address is the target location in the target
  40    machine.  BP_TGT->shadow_contents is some memory allocated for
  41    saving the target contents.  It is guaranteed by the caller to be
  42    long enough to save BREAKPOINT_LEN bytes (this is accomplished via
  43    BREAKPOINT_MAX).  */
  44
  45 int
  46 default_memory_insert_breakpoint (struct bp_target_info *bp_tgt)
  47 {
  48   int val;
  49   const unsigned char *bp;
  50   int bplen;
  51
  52   /* Determine appropriate breakpoint contents and size for this address.  */
  53   bp = BREAKPOINT_FROM_PC (&bp_tgt->placed_address, &bp_tgt->placed_size);
  54   if (bp == NULL)
  55     error (_("Software breakpoints not implemented for this target."));
  56
  57   /* Save the memory contents.  */
  58   bp_tgt->shadow_len = bp_tgt->placed_size;
  59   val = target_read_memory (bp_tgt->placed_address, bp_tgt->shadow_contents,
  60                             bp_tgt->placed_size);
  61
  62   /* Write the breakpoint.  */
  63   if (val == 0)
  64     val = target_write_memory (bp_tgt->placed_address, bp,
  65                                bp_tgt->placed_size);
  66
  67   return val;
  68 }
  69
  70
  71 int
  72 default_memory_remove_breakpoint (struct bp_target_info *bp_tgt)
  73 {
  74   return target_write_memory (bp_tgt->placed_address, bp_tgt->shadow_contents,
  75                               bp_tgt->placed_size);
  76 }
  77
  78
  79 int
  80 memory_insert_breakpoint (struct bp_target_info *bp_tgt)
  81 {
  82   return MEMORY_INSERT_BREAKPOINT (bp_tgt);
  83 }
  84
  85 int
  86 memory_remove_breakpoint (struct bp_target_info *bp_tgt)
  87 {
  88   return MEMORY_REMOVE_BREAKPOINT (bp_tgt);
  89 }