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 = gdbarch_breakpoint_from_pc
  54        (current_gdbarch, &bp_tgt->placed_address, &bp_tgt->placed_size);
  55   if (bp == NULL)
  56     error (_("Software breakpoints not implemented for this target."));
  57
  58   /* Save the memory contents.  */
  59   bp_tgt->shadow_len = bp_tgt->placed_size;
  60   val = target_read_memory (bp_tgt->placed_address, bp_tgt->shadow_contents,
  61                             bp_tgt->placed_size);
  62
  63   /* Write the breakpoint.  */
  64   if (val == 0)
  65     val = target_write_memory (bp_tgt->placed_address, bp,
  66                                bp_tgt->placed_size);
  67
  68   return val;
  69 }
  70
  71
  72 int
  73 default_memory_remove_breakpoint (struct bp_target_info *bp_tgt)
  74 {
  75   return target_write_memory (bp_tgt->placed_address, bp_tgt->shadow_contents,
  76                               bp_tgt->placed_size);
  77 }
  78
  79
  80 int
  81 memory_insert_breakpoint (struct bp_target_info *bp_tgt)
  82 {
  83   return gdbarch_memory_insert_breakpoint (current_gdbarch, bp_tgt);
  84 }
  85
  86 int
  87 memory_remove_breakpoint (struct bp_target_info *bp_tgt)
  88 {
  89   return gdbarch_memory_remove_breakpoint (current_gdbarch, bp_tgt);
  90 }