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 3 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, see <http://www.gnu.org/licenses/>.  */
22
23#include "defs.h"
24
25/* This file is only useful if BREAKPOINT_FROM_PC is set.  If not, we
26   punt.  */
27
28#include "symtab.h"
29#include "breakpoint.h"
30#include "inferior.h"
31#include "target.h"
32
33
34/* Insert a breakpoint on targets that don't have any better
35   breakpoint support.  We read the contents of the target location
36   and stash it, then overwrite it with a breakpoint instruction.
37   BP_TGT->placed_address is the target location in the target
38   machine.  BP_TGT->shadow_contents is some memory allocated for
39   saving the target contents.  It is guaranteed by the caller to be
40   long enough to save BREAKPOINT_LEN bytes (this is accomplished via
41   BREAKPOINT_MAX).  */
42
43int
44default_memory_insert_breakpoint (struct bp_target_info *bp_tgt)
45{
46  int val;
47  const unsigned char *bp;
48  int bplen;
49
50  /* Determine appropriate breakpoint contents and size for this address.  */
51  bp = gdbarch_breakpoint_from_pc
52       (current_gdbarch, &bp_tgt->placed_address, &bp_tgt->placed_size);
53  if (bp == NULL)
54    error (_("Software breakpoints not implemented for this target."));
55
56  /* Save the memory contents.  */
57  bp_tgt->shadow_len = bp_tgt->placed_size;
58  val = target_read_memory (bp_tgt->placed_address, bp_tgt->shadow_contents,
59			    bp_tgt->placed_size);
60
61  /* Write the breakpoint.  */
62  if (val == 0)
63    val = target_write_memory (bp_tgt->placed_address, bp,
64			       bp_tgt->placed_size);
65
66  return val;
67}
68
69
70int
71default_memory_remove_breakpoint (struct bp_target_info *bp_tgt)
72{
73  return target_write_memory (bp_tgt->placed_address, bp_tgt->shadow_contents,
74			      bp_tgt->placed_size);
75}
76
77
78int
79memory_insert_breakpoint (struct bp_target_info *bp_tgt)
80{
81  return gdbarch_memory_insert_breakpoint (current_gdbarch, bp_tgt);
82}
83
84int
85memory_remove_breakpoint (struct bp_target_info *bp_tgt)
86{
87  return gdbarch_memory_remove_breakpoint (current_gdbarch, bp_tgt);
88}
89