1 /* Simulate breakpoints by patching locations in the target system, for GDB.
3 Copyright (C) 1990-2024 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"
29 /* Insert a breakpoint on targets that don't have any better
30 breakpoint support. We read the contents of the target location
31 and stash it, then overwrite it with a breakpoint instruction.
32 BP_TGT->placed_address is the target location in the target
33 machine. BP_TGT->shadow_contents is some memory allocated for
34 saving the target contents. It is guaranteed by the caller to be
35 long enough to save BREAKPOINT_LEN bytes (this is accomplished via
39 default_memory_insert_breakpoint (struct gdbarch
*gdbarch
,
40 struct bp_target_info
*bp_tgt
)
42 CORE_ADDR addr
= bp_tgt
->placed_address
;
43 const unsigned char *bp
;
48 /* Determine appropriate breakpoint contents and size for this address. */
49 bp
= gdbarch_sw_breakpoint_from_kind (gdbarch
, bp_tgt
->kind
, &bplen
);
51 /* Save the memory contents in the shadow_contents buffer and then
52 write the breakpoint instruction. */
53 readbuf
= (gdb_byte
*) alloca (bplen
);
54 val
= target_read_memory (addr
, readbuf
, bplen
);
57 /* These must be set together, either before or after the shadow
58 read, so that if we're "reinserting" a breakpoint that
59 doesn't have a shadow yet, the breakpoint masking code inside
60 target_read_memory doesn't mask out this breakpoint using an
61 unfilled shadow buffer. The core may be trying to reinsert a
62 permanent breakpoint, for targets that support breakpoint
63 conditions/commands on the target side for some types of
64 breakpoints, such as target remote. */
65 bp_tgt
->shadow_len
= bplen
;
66 memcpy (bp_tgt
->shadow_contents
, readbuf
, bplen
);
68 val
= target_write_raw_memory (addr
, bp
, bplen
);
76 default_memory_remove_breakpoint (struct gdbarch
*gdbarch
,
77 struct bp_target_info
*bp_tgt
)
81 gdbarch_sw_breakpoint_from_kind (gdbarch
, bp_tgt
->kind
, &bplen
);
83 return target_write_raw_memory (bp_tgt
->placed_address
, bp_tgt
->shadow_contents
,
89 memory_insert_breakpoint (struct target_ops
*ops
, struct gdbarch
*gdbarch
,
90 struct bp_target_info
*bp_tgt
)
92 return gdbarch_memory_insert_breakpoint (gdbarch
, bp_tgt
);
96 memory_remove_breakpoint (struct target_ops
*ops
, struct gdbarch
*gdbarch
,
97 struct bp_target_info
*bp_tgt
,
98 enum remove_bp_reason reason
)
100 return gdbarch_memory_remove_breakpoint (gdbarch
, bp_tgt
);
104 memory_validate_breakpoint (struct gdbarch
*gdbarch
,
105 struct bp_target_info
*bp_tgt
)
107 CORE_ADDR addr
= bp_tgt
->placed_address
;
111 gdb_byte cur_contents
[BREAKPOINT_MAX
];
113 /* Determine appropriate breakpoint contents and size for this
115 bp
= gdbarch_breakpoint_from_pc (gdbarch
, &addr
, &bplen
);
120 /* Make sure we see the memory breakpoints. */
121 scoped_restore restore_memory
122 = make_scoped_restore_show_memory_breakpoints (1);
123 val
= target_read_memory (addr
, cur_contents
, bplen
);
125 /* If our breakpoint is no longer at the address, this means that
126 the program modified the code on us, so it is wrong to put back
128 return (val
== 0 && memcmp (bp
, cur_contents
, bplen
) == 0);