1 /* Simulate breakpoints by patching locations in the target system, for GDB.
3 Copyright (C) 1990-2014 Free Software Foundation, Inc.
5 Contributed by Cygnus Support. Written by John Gilmore.
7 This file is part of GDB.
9 This program is free software; you can redistribute it and/or modify
10 it under the terms of the GNU General Public License as published by
11 the Free Software Foundation; either version 3 of the License, or
12 (at your option) any later version.
14 This program is distributed in the hope that it will be useful,
15 but WITHOUT ANY WARRANTY; without even the implied warranty of
16 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17 GNU General Public License for more details.
19 You should have received a copy of the GNU General Public License
20 along with this program. If not, see <http://www.gnu.org/licenses/>. */
24 #include "breakpoint.h"
27 /* Insert a breakpoint on targets that don't have any better
28 breakpoint support. We read the contents of the target location
29 and stash it, then overwrite it with a breakpoint instruction.
30 BP_TGT->placed_address is the target location in the target
31 machine. BP_TGT->shadow_contents is some memory allocated for
32 saving the target contents. It is guaranteed by the caller to be
33 long enough to save BREAKPOINT_LEN bytes (this is accomplished via
37 default_memory_insert_breakpoint (struct gdbarch
*gdbarch
,
38 struct bp_target_info
*bp_tgt
)
41 const unsigned char *bp
;
44 /* Determine appropriate breakpoint contents and size for this address. */
45 bp
= gdbarch_breakpoint_from_pc
46 (gdbarch
, &bp_tgt
->placed_address
, &bp_tgt
->placed_size
);
48 error (_("Software breakpoints not implemented for this target."));
50 /* Save the memory contents in the shadow_contents buffer and then
51 write the breakpoint instruction. */
52 bp_tgt
->shadow_len
= bp_tgt
->placed_size
;
53 readbuf
= alloca (bp_tgt
->placed_size
);
54 val
= target_read_memory (bp_tgt
->placed_address
, readbuf
,
58 memcpy (bp_tgt
->shadow_contents
, readbuf
, bp_tgt
->placed_size
);
59 val
= target_write_raw_memory (bp_tgt
->placed_address
, bp
,
68 default_memory_remove_breakpoint (struct gdbarch
*gdbarch
,
69 struct bp_target_info
*bp_tgt
)
71 return target_write_raw_memory (bp_tgt
->placed_address
, bp_tgt
->shadow_contents
,
77 memory_insert_breakpoint (struct target_ops
*ops
, struct gdbarch
*gdbarch
,
78 struct bp_target_info
*bp_tgt
)
80 return gdbarch_memory_insert_breakpoint (gdbarch
, bp_tgt
);
84 memory_remove_breakpoint (struct target_ops
*ops
, struct gdbarch
*gdbarch
,
85 struct bp_target_info
*bp_tgt
)
87 return gdbarch_memory_remove_breakpoint (gdbarch
, bp_tgt
);
91 memory_validate_breakpoint (struct gdbarch
*gdbarch
,
92 struct bp_target_info
*bp_tgt
)
94 CORE_ADDR addr
= bp_tgt
->placed_address
;
98 gdb_byte cur_contents
[BREAKPOINT_MAX
];
99 struct cleanup
*cleanup
;
102 /* Determine appropriate breakpoint contents and size for this
104 bp
= gdbarch_breakpoint_from_pc (gdbarch
, &addr
, &bplen
);
106 if (bp
== NULL
|| bp_tgt
->placed_size
!= bplen
)
109 /* Make sure we see the memory breakpoints. */
110 cleanup
= make_show_memory_breakpoints_cleanup (1);
111 val
= target_read_memory (addr
, cur_contents
, bplen
);
113 /* If our breakpoint is no longer at the address, this means that
114 the program modified the code on us, so it is wrong to put back
116 ret
= (val
== 0 && memcmp (bp
, cur_contents
, bplen
) == 0);
118 do_cleanups (cleanup
);