| 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, |
| 20 | Boston, MA 02111-1307, USA. */ |
| 21 | |
| 22 | #include "defs.h" |
| 23 | |
| 24 | /* This file is only useful if BREAKPOINT is set. If not, we punt. */ |
| 25 | |
| 26 | #include "symtab.h" |
| 27 | #include "breakpoint.h" |
| 28 | #include "inferior.h" |
| 29 | #include "target.h" |
| 30 | |
| 31 | |
| 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. */ |
| 41 | |
| 42 | unsigned char * |
| 43 | memory_breakpoint_from_pc (CORE_ADDR *pcptr, int *lenptr) |
| 44 | { |
| 45 | /* {BIG_,LITTLE_}BREAKPOINT is the sequence of bytes we insert for a |
| 46 | breakpoint. On some machines, breakpoints are handled by the |
| 47 | target environment and we don't have to worry about them here. */ |
| 48 | #ifdef BIG_BREAKPOINT |
| 49 | if (TARGET_BYTE_ORDER == BIG_ENDIAN) |
| 50 | { |
| 51 | static unsigned char big_break_insn[] = BIG_BREAKPOINT; |
| 52 | *lenptr = sizeof (big_break_insn); |
| 53 | return big_break_insn; |
| 54 | } |
| 55 | #endif |
| 56 | #ifdef LITTLE_BREAKPOINT |
| 57 | if (TARGET_BYTE_ORDER != BIG_ENDIAN) |
| 58 | { |
| 59 | static unsigned char little_break_insn[] = LITTLE_BREAKPOINT; |
| 60 | *lenptr = sizeof (little_break_insn); |
| 61 | return little_break_insn; |
| 62 | } |
| 63 | #endif |
| 64 | #ifdef BREAKPOINT |
| 65 | { |
| 66 | static unsigned char break_insn[] = BREAKPOINT; |
| 67 | *lenptr = sizeof (break_insn); |
| 68 | return break_insn; |
| 69 | } |
| 70 | #endif |
| 71 | *lenptr = 0; |
| 72 | return NULL; |
| 73 | } |
| 74 | |
| 75 | |
| 76 | /* Insert a breakpoint on targets that don't have any better breakpoint |
| 77 | support. We read the contents of the target location and stash it, |
| 78 | then overwrite it with a breakpoint instruction. ADDR is the target |
| 79 | location in the target machine. CONTENTS_CACHE is a pointer to |
| 80 | memory allocated for saving the target contents. It is guaranteed |
| 81 | by the caller to be long enough to save BREAKPOINT_LEN bytes (this |
| 82 | is accomplished via BREAKPOINT_MAX). */ |
| 83 | |
| 84 | int |
| 85 | default_memory_insert_breakpoint (CORE_ADDR addr, char *contents_cache) |
| 86 | { |
| 87 | int val; |
| 88 | unsigned char *bp; |
| 89 | int bplen; |
| 90 | |
| 91 | /* Determine appropriate breakpoint contents and size for this address. */ |
| 92 | bp = BREAKPOINT_FROM_PC (&addr, &bplen); |
| 93 | if (bp == NULL) |
| 94 | error ("Software breakpoints not implemented for this target."); |
| 95 | |
| 96 | /* Save the memory contents. */ |
| 97 | val = target_read_memory (addr, contents_cache, bplen); |
| 98 | |
| 99 | /* Write the breakpoint. */ |
| 100 | if (val == 0) |
| 101 | val = target_write_memory (addr, (char *) bp, bplen); |
| 102 | |
| 103 | return val; |
| 104 | } |
| 105 | |
| 106 | |
| 107 | int |
| 108 | default_memory_remove_breakpoint (CORE_ADDR addr, char *contents_cache) |
| 109 | { |
| 110 | unsigned char *bp; |
| 111 | int bplen; |
| 112 | |
| 113 | /* Determine appropriate breakpoint contents and size for this address. */ |
| 114 | bp = BREAKPOINT_FROM_PC (&addr, &bplen); |
| 115 | if (bp == NULL) |
| 116 | error ("Software breakpoints not implemented for this target."); |
| 117 | |
| 118 | return target_write_memory (addr, contents_cache, bplen); |
| 119 | } |
| 120 | |
| 121 | |
| 122 | int |
| 123 | memory_insert_breakpoint (CORE_ADDR addr, char *contents_cache) |
| 124 | { |
| 125 | return MEMORY_INSERT_BREAKPOINT(addr, contents_cache); |
| 126 | } |
| 127 | |
| 128 | int |
| 129 | memory_remove_breakpoint (CORE_ADDR addr, char *contents_cache) |
| 130 | { |
| 131 | return MEMORY_REMOVE_BREAKPOINT(addr, contents_cache); |
| 132 | } |