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 /* Either BREAKPOINT should be defined, or both of LITTLE_BREAKPOINT, 24 BIG_BREAKPOINT should be defined. */ 25 26 #if defined (BREAKPOINT) || (defined (LITTLE_BREAKPOINT) && defined (BIG_BREAKPOINT)) 27 28 /* This file is only useful if BREAKPOINT is set. If not, we punt. */ 29 30 #include "symtab.h" 31 #include "breakpoint.h" 32 #include "inferior.h" 33 #include "target.h" 34 35 /* If the target isn't bi-endian, just pretend it is. */ 36 #if defined(BREAKPOINT) && !defined (LITTLE_BREAKPOINT) && !defined (BIG_BREAKPOINT) 37 #define LITTLE_BREAKPOINT BREAKPOINT 38 #define BIG_BREAKPOINT BREAKPOINT 39 #endif 40 41 /* This is the sequence of bytes we insert for a breakpoint. On some 42 machines, breakpoints are handled by the target environment and we 43 don't have to worry about them here. */ 44 45 static unsigned char big_break_insn[] = BIG_BREAKPOINT; 46 static unsigned char little_break_insn[] = LITTLE_BREAKPOINT; 47 48 /* FIXME: We assume big and little breakpoints are the same size. */ 49 #define BREAKPOINT_LEN (sizeof (big_break_insn)) 50 51 /* Insert a breakpoint on targets that don't have any better breakpoint 52 support. We read the contents of the target location and stash it, 53 then overwrite it with a breakpoint instruction. ADDR is the target 54 location in the target machine. CONTENTS_CACHE is a pointer to 55 memory allocated for saving the target contents. It is guaranteed 56 by the caller to be long enough to save BREAKPOINT_LEN bytes (this 57 is accomplished via BREAKPOINT_MAX). */ 58 59 int 60 memory_insert_breakpoint (addr, contents_cache) 61 CORE_ADDR addr; 62 char *contents_cache; 63 { 64 int val; 65 66 val = target_read_memory (addr, contents_cache, BREAKPOINT_LEN); 67 68 if (val == 0) 69 { 70 if (TARGET_BYTE_ORDER == BIG_ENDIAN) 71 val = target_write_memory (addr, (char *)big_break_insn, 72 BREAKPOINT_LEN); 73 else 74 val = target_write_memory (addr, (char *)little_break_insn, 75 BREAKPOINT_LEN); 76 } 77 78 return val; 79 } 80 81 82 int 83 memory_remove_breakpoint (addr, contents_cache) 84 CORE_ADDR addr; 85 char *contents_cache; 86 { 87 return target_write_memory (addr, contents_cache, BREAKPOINT_LEN); 88 } 89 90 91 /* FIXME: This is a hack and should depend on the debugging target. 92 See comment in breakpoint.c where this is used. */ 93 94 int memory_breakpoint_size = BREAKPOINT_LEN; 95 96 97 #else /* BREAKPOINT */ 98 99 char nogo[] = "Breakpoints not implemented for this target."; 100 101 int 102 memory_insert_breakpoint (addr, contents_cache) 103 CORE_ADDR addr; 104 char *contents_cache; 105 { 106 error (nogo); 107 return 0; /* lint */ 108 } 109 110 int 111 memory_remove_breakpoint (addr, contents_cache) 112 CORE_ADDR addr; 113 char *contents_cache; 114 { 115 error (nogo); 116 return 0; /* lint */ 117 } 118 119 int memory_breakpoint_size = -1; 120 121 #endif /* BREAKPOINT */ 122