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c906108c SS |
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. | |
4 | ||
5 | This file is part of GDB. | |
6 | ||
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. | |
11 | ||
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. | |
16 | ||
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, Boston, MA 02111-1307, USA. */ | |
20 | ||
21 | #include "defs.h" | |
22 | ||
23 | /* This file is only useful if BREAKPOINT is set. If not, we punt. */ | |
24 | ||
25 | #include "symtab.h" | |
26 | #include "breakpoint.h" | |
27 | #include "inferior.h" | |
28 | #include "target.h" | |
29 | ||
30 | ||
31 | /* Use the program counter to determine the contents and size | |
32 | of a breakpoint instruction. If no target-dependent macro | |
33 | BREAKPOINT_FROM_PC has been defined to implement this function, | |
34 | assume that the breakpoint doesn't depend on the PC, and | |
35 | use the values of the BIG_BREAKPOINT and LITTLE_BREAKPOINT macros. | |
36 | Return a pointer to a string of bytes that encode a breakpoint | |
37 | instruction, stores the length of the string to *lenptr, | |
38 | and optionally adjust the pc to point to the correct memory location | |
39 | for inserting the breakpoint. */ | |
40 | ||
41 | unsigned char * | |
42 | memory_breakpoint_from_pc (pcptr, lenptr) | |
43 | CORE_ADDR *pcptr; | |
44 | int *lenptr; | |
45 | { | |
46 | /* {BIG_,LITTLE_}BREAKPOINT is the sequence of bytes we insert for a | |
47 | breakpoint. On some machines, breakpoints are handled by the | |
48 | target environment and we don't have to worry about them here. */ | |
49 | #ifdef BIG_BREAKPOINT | |
50 | if (TARGET_BYTE_ORDER == BIG_ENDIAN) | |
51 | { | |
52 | static unsigned char big_break_insn[] = BIG_BREAKPOINT; | |
53 | *lenptr = sizeof (big_break_insn); | |
54 | return big_break_insn; | |
55 | } | |
56 | #endif | |
57 | #ifdef LITTLE_BREAKPOINT | |
58 | if (TARGET_BYTE_ORDER != BIG_ENDIAN) | |
59 | { | |
60 | static unsigned char little_break_insn[] = LITTLE_BREAKPOINT; | |
61 | *lenptr = sizeof (little_break_insn); | |
62 | return little_break_insn; | |
63 | } | |
64 | #endif | |
65 | #ifdef BREAKPOINT | |
66 | { | |
67 | static unsigned char break_insn[] = BREAKPOINT; | |
68 | *lenptr = sizeof (break_insn); | |
69 | return break_insn; | |
70 | } | |
71 | #endif | |
72 | *lenptr = 0; | |
73 | return NULL; | |
74 | } | |
75 | ||
76 | ||
77 | /* Insert a breakpoint on targets that don't have any better breakpoint | |
78 | support. We read the contents of the target location and stash it, | |
79 | then overwrite it with a breakpoint instruction. ADDR is the target | |
80 | location in the target machine. CONTENTS_CACHE is a pointer to | |
81 | memory allocated for saving the target contents. It is guaranteed | |
82 | by the caller to be long enough to save BREAKPOINT_LEN bytes (this | |
83 | is accomplished via BREAKPOINT_MAX). */ | |
84 | ||
85 | int | |
86 | memory_insert_breakpoint (addr, contents_cache) | |
87 | CORE_ADDR addr; | |
88 | char *contents_cache; | |
89 | { | |
90 | int val; | |
91 | unsigned char *bp; | |
92 | int bplen; | |
93 | ||
94 | /* Determine appropriate breakpoint contents and size for this address. */ | |
95 | bp = BREAKPOINT_FROM_PC (&addr, &bplen); | |
96 | if (bp == NULL) | |
97 | error ("Software breakpoints not implemented for this target."); | |
98 | ||
99 | /* Save the memory contents. */ | |
100 | val = target_read_memory (addr, contents_cache, bplen); | |
101 | ||
102 | /* Write the breakpoint. */ | |
103 | if (val == 0) | |
104 | val = target_write_memory (addr, (char *)bp, bplen); | |
105 | ||
106 | return val; | |
107 | } | |
108 | ||
109 | ||
110 | int | |
111 | memory_remove_breakpoint (addr, contents_cache) | |
112 | CORE_ADDR addr; | |
113 | char *contents_cache; | |
114 | { | |
115 | unsigned char *bp; | |
116 | int bplen; | |
117 | ||
118 | /* Determine appropriate breakpoint contents and size for this address. */ | |
119 | bp = BREAKPOINT_FROM_PC (&addr, &bplen); | |
120 | if (bp == NULL) | |
121 | error ("Software breakpoints not implemented for this target."); | |
122 | ||
123 | return target_write_memory (addr, contents_cache, bplen); | |
124 | } |