1 /* Simulate breakpoints by patching locations in the target system, for GDB.
2 Copyright 1990, 1991, 1995 Free Software Foundation, Inc.
3 Contributed by Cygnus Support. Written by John Gilmore.
5 This file is part of GDB.
7 This program is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 2 of the License, or
10 (at your option) any later version.
12 This program is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
17 You should have received a copy of the GNU General Public License
18 along with this program; if not, write to the Free Software
19 Foundation, Inc., 59 Temple Place - Suite 330,
20 Boston, MA 02111-1307, USA. */
24 /* This file is only useful if BREAKPOINT is set. If not, we punt. */
27 #include "breakpoint.h"
32 /* Use the program counter to determine the contents and size
33 of a breakpoint instruction. If no target-dependent macro
34 BREAKPOINT_FROM_PC has been defined to implement this function,
35 assume that the breakpoint doesn't depend on the PC, and
36 use the values of the BIG_BREAKPOINT and LITTLE_BREAKPOINT macros.
37 Return a pointer to a string of bytes that encode a breakpoint
38 instruction, stores the length of the string to *lenptr,
39 and optionally adjust the pc to point to the correct memory location
40 for inserting the breakpoint. */
43 memory_breakpoint_from_pc (pcptr
, lenptr
)
47 /* {BIG_,LITTLE_}BREAKPOINT is the sequence of bytes we insert for a
48 breakpoint. On some machines, breakpoints are handled by the
49 target environment and we don't have to worry about them here. */
51 if (TARGET_BYTE_ORDER
== BIG_ENDIAN
)
53 static unsigned char big_break_insn
[] = BIG_BREAKPOINT
;
54 *lenptr
= sizeof (big_break_insn
);
55 return big_break_insn
;
58 #ifdef LITTLE_BREAKPOINT
59 if (TARGET_BYTE_ORDER
!= BIG_ENDIAN
)
61 static unsigned char little_break_insn
[] = LITTLE_BREAKPOINT
;
62 *lenptr
= sizeof (little_break_insn
);
63 return little_break_insn
;
68 static unsigned char break_insn
[] = BREAKPOINT
;
69 *lenptr
= sizeof (break_insn
);
78 /* Insert a breakpoint on targets that don't have any better breakpoint
79 support. We read the contents of the target location and stash it,
80 then overwrite it with a breakpoint instruction. ADDR is the target
81 location in the target machine. CONTENTS_CACHE is a pointer to
82 memory allocated for saving the target contents. It is guaranteed
83 by the caller to be long enough to save BREAKPOINT_LEN bytes (this
84 is accomplished via BREAKPOINT_MAX). */
87 memory_insert_breakpoint (addr
, contents_cache
)
95 /* Determine appropriate breakpoint contents and size for this address. */
96 bp
= BREAKPOINT_FROM_PC (&addr
, &bplen
);
98 error ("Software breakpoints not implemented for this target.");
100 /* Save the memory contents. */
101 val
= target_read_memory (addr
, contents_cache
, bplen
);
103 /* Write the breakpoint. */
105 val
= target_write_memory (addr
, (char *) bp
, bplen
);
112 memory_remove_breakpoint (addr
, contents_cache
)
114 char *contents_cache
;
119 /* Determine appropriate breakpoint contents and size for this address. */
120 bp
= BREAKPOINT_FROM_PC (&addr
, &bplen
);
122 error ("Software breakpoints not implemented for this target.");
124 return target_write_memory (addr
, contents_cache
, bplen
);
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