GDB (xrefs)
/tmp/gdb-7.10/gdb/mem-break.c
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1 /* Simulate breakpoints by patching locations in the target system, for GDB.
2 
3  Copyright (C) 1990-2015 Free Software Foundation, Inc.
4 
5  Contributed by Cygnus Support. Written by John Gilmore.
6 
7  This file is part of GDB.
8 
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.
13 
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.
18 
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/>. */
21 
22 #include "defs.h"
23 #include "symtab.h"
24 #include "breakpoint.h"
25 #include "inferior.h"
26 #include "target.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
34  BREAKPOINT_MAX). */
35 
36 int
38  struct bp_target_info *bp_tgt)
39 {
40  CORE_ADDR addr = bp_tgt->reqstd_address;
41  const unsigned char *bp;
42  gdb_byte *readbuf;
43  int bplen;
44  int val;
45 
46  /* Determine appropriate breakpoint contents and size for this address. */
47  bp = gdbarch_breakpoint_from_pc (gdbarch, &addr, &bplen);
48  if (bp == NULL)
49  error (_("Software breakpoints not implemented for this target."));
50 
51  bp_tgt->placed_address = addr;
52  bp_tgt->placed_size = bplen;
53 
54  /* Save the memory contents in the shadow_contents buffer and then
55  write the breakpoint instruction. */
56  readbuf = alloca (bplen);
57  val = target_read_memory (addr, readbuf, bplen);
58  if (val == 0)
59  {
60  /* These must be set together, either before or after the shadow
61  read, so that if we're "reinserting" a breakpoint that
62  doesn't have a shadow yet, the breakpoint masking code inside
63  target_read_memory doesn't mask out this breakpoint using an
64  unfilled shadow buffer. The core may be trying to reinsert a
65  permanent breakpoint, for targets that support breakpoint
66  conditions/commands on the target side for some types of
67  breakpoints, such as target remote. */
68  bp_tgt->shadow_len = bplen;
69  memcpy (bp_tgt->shadow_contents, readbuf, bplen);
70 
71  val = target_write_raw_memory (addr, bp, bplen);
72  }
73 
74  return val;
75 }
76 
77 
78 int
80  struct bp_target_info *bp_tgt)
81 {
83  bp_tgt->placed_size);
84 }
85 
86 
87 int
89  struct bp_target_info *bp_tgt)
90 {
91  return gdbarch_memory_insert_breakpoint (gdbarch, bp_tgt);
92 }
93 
94 int
96  struct bp_target_info *bp_tgt)
97 {
98  return gdbarch_memory_remove_breakpoint (gdbarch, bp_tgt);
99 }
100 
101 int
103  struct bp_target_info *bp_tgt)
104 {
105  CORE_ADDR addr = bp_tgt->placed_address;
106  const gdb_byte *bp;
107  int val;
108  int bplen;
109  gdb_byte cur_contents[BREAKPOINT_MAX];
110  struct cleanup *cleanup;
111  int ret;
112 
113  /* Determine appropriate breakpoint contents and size for this
114  address. */
115  bp = gdbarch_breakpoint_from_pc (gdbarch, &addr, &bplen);
116 
117  if (bp == NULL || bp_tgt->placed_size != bplen)
118  return 0;
119 
120  /* Make sure we see the memory breakpoints. */
122  val = target_read_memory (addr, cur_contents, bplen);
123 
124  /* If our breakpoint is no longer at the address, this means that
125  the program modified the code on us, so it is wrong to put back
126  the old value. */
127  ret = (val == 0 && memcmp (bp, cur_contents, bplen) == 0);
128 
129  do_cleanups (cleanup);
130  return ret;
131 }
CORE_ADDR reqstd_address
Definition: breakpoint.h:235
struct cleanup * make_show_memory_breakpoints_cleanup(int show)
Definition: target.c:1269
bfd_vma CORE_ADDR
Definition: common-types.h:41
#define _(String)
Definition: gdb_locale.h:40
int gdbarch_memory_insert_breakpoint(struct gdbarch *gdbarch, struct bp_target_info *bp_tgt)
Definition: gdbarch.c:2720
#define BREAKPOINT_MAX
Definition: breakpoint.h:46
gdb_byte shadow_contents[BREAKPOINT_MAX]
Definition: breakpoint.h:245
int target_write_raw_memory(CORE_ADDR memaddr, const gdb_byte *myaddr, ssize_t len)
Definition: target.c:1492
CORE_ADDR placed_address
Definition: breakpoint.h:232
int gdbarch_memory_remove_breakpoint(struct gdbarch *gdbarch, struct bp_target_info *bp_tgt)
Definition: gdbarch.c:2737
bfd_byte gdb_byte
Definition: common-types.h:38
int default_memory_remove_breakpoint(struct gdbarch *gdbarch, struct bp_target_info *bp_tgt)
Definition: mem-break.c:79
int target_read_memory(CORE_ADDR memaddr, gdb_byte *myaddr, ssize_t len)
Definition: target.c:1393
const gdb_byte * gdbarch_breakpoint_from_pc(struct gdbarch *gdbarch, CORE_ADDR *pcptr, int *lenptr)
Definition: gdbarch.c:2662
int memory_validate_breakpoint(struct gdbarch *gdbarch, struct bp_target_info *bp_tgt)
Definition: mem-break.c:102
int memory_insert_breakpoint(struct target_ops *ops, struct gdbarch *gdbarch, struct bp_target_info *bp_tgt)
Definition: mem-break.c:88
int memory_remove_breakpoint(struct target_ops *ops, struct gdbarch *gdbarch, struct bp_target_info *bp_tgt)
Definition: mem-break.c:95
int default_memory_insert_breakpoint(struct gdbarch *gdbarch, struct bp_target_info *bp_tgt)
Definition: mem-break.c:37
void error(const char *fmt,...)
Definition: errors.c:38
void do_cleanups(struct cleanup *old_chain)
Definition: cleanups.c:175