1 /* Simulate breakpoints by patching locations in the target system, for GDB. 2 3 Copyright (C) 1990-2013 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 #include "gdb_string.h" 28 29 30 /* Insert a breakpoint on targets that don't have any better 31 breakpoint support. We read the contents of the target location 32 and stash it, then overwrite it with a breakpoint instruction. 33 BP_TGT->placed_address is the target location in the target 34 machine. BP_TGT->shadow_contents is some memory allocated for 35 saving the target contents. It is guaranteed by the caller to be 36 long enough to save BREAKPOINT_LEN bytes (this is accomplished via 37 BREAKPOINT_MAX). */ 38 39 int 40 default_memory_insert_breakpoint (struct gdbarch *gdbarch, 41 struct bp_target_info *bp_tgt) 42 { 43 int val; 44 const unsigned char *bp; 45 gdb_byte *readbuf; 46 47 /* Determine appropriate breakpoint contents and size for this address. */ 48 bp = gdbarch_breakpoint_from_pc 49 (gdbarch, &bp_tgt->placed_address, &bp_tgt->placed_size); 50 if (bp == NULL) 51 error (_("Software breakpoints not implemented for this target.")); 52 53 /* Save the memory contents in the shadow_contents buffer and then 54 write the breakpoint instruction. */ 55 bp_tgt->shadow_len = bp_tgt->placed_size; 56 readbuf = alloca (bp_tgt->placed_size); 57 val = target_read_memory (bp_tgt->placed_address, readbuf, 58 bp_tgt->placed_size); 59 if (val == 0) 60 { 61 memcpy (bp_tgt->shadow_contents, readbuf, bp_tgt->placed_size); 62 val = target_write_raw_memory (bp_tgt->placed_address, bp, 63 bp_tgt->placed_size); 64 } 65 66 return val; 67 } 68 69 70 int 71 default_memory_remove_breakpoint (struct gdbarch *gdbarch, 72 struct bp_target_info *bp_tgt) 73 { 74 return target_write_raw_memory (bp_tgt->placed_address, bp_tgt->shadow_contents, 75 bp_tgt->placed_size); 76 } 77 78 79 int 80 memory_insert_breakpoint (struct gdbarch *gdbarch, 81 struct bp_target_info *bp_tgt) 82 { 83 return gdbarch_memory_insert_breakpoint (gdbarch, bp_tgt); 84 } 85 86 int 87 memory_remove_breakpoint (struct gdbarch *gdbarch, 88 struct bp_target_info *bp_tgt) 89 { 90 return gdbarch_memory_remove_breakpoint (gdbarch, bp_tgt); 91 } 92