| /* Simulate breakpoints by patching locations in the target system, for GDB. |
| |
| Copyright (C) 1990-2024 Free Software Foundation, Inc. |
| |
| Contributed by Cygnus Support. Written by John Gilmore. |
| |
| This file is part of GDB. |
| |
| This program is free software; you can redistribute it and/or modify |
| it under the terms of the GNU General Public License as published by |
| the Free Software Foundation; either version 3 of the License, or |
| (at your option) any later version. |
| |
| This program is distributed in the hope that it will be useful, |
| but WITHOUT ANY WARRANTY; without even the implied warranty of |
| MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| GNU General Public License for more details. |
| |
| You should have received a copy of the GNU General Public License |
| along with this program. If not, see <http://www.gnu.org/licenses/>. */ |
| |
| #include "symtab.h" |
| #include "breakpoint.h" |
| #include "inferior.h" |
| #include "target.h" |
| #include "gdbarch.h" |
| |
| /* Insert a breakpoint on targets that don't have any better |
| breakpoint support. We read the contents of the target location |
| and stash it, then overwrite it with a breakpoint instruction. |
| BP_TGT->placed_address is the target location in the target |
| machine. BP_TGT->shadow_contents is some memory allocated for |
| saving the target contents. It is guaranteed by the caller to be |
| long enough to save BREAKPOINT_LEN bytes (this is accomplished via |
| BREAKPOINT_MAX). */ |
| |
| int |
| default_memory_insert_breakpoint (struct gdbarch *gdbarch, |
| struct bp_target_info *bp_tgt) |
| { |
| CORE_ADDR addr = bp_tgt->placed_address; |
| const unsigned char *bp; |
| gdb_byte *readbuf; |
| int bplen; |
| int val; |
| |
| /* Determine appropriate breakpoint contents and size for this address. */ |
| bp = gdbarch_sw_breakpoint_from_kind (gdbarch, bp_tgt->kind, &bplen); |
| |
| /* Save the memory contents in the shadow_contents buffer and then |
| write the breakpoint instruction. */ |
| readbuf = (gdb_byte *) alloca (bplen); |
| val = target_read_memory (addr, readbuf, bplen); |
| if (val == 0) |
| { |
| /* These must be set together, either before or after the shadow |
| read, so that if we're "reinserting" a breakpoint that |
| doesn't have a shadow yet, the breakpoint masking code inside |
| target_read_memory doesn't mask out this breakpoint using an |
| unfilled shadow buffer. The core may be trying to reinsert a |
| permanent breakpoint, for targets that support breakpoint |
| conditions/commands on the target side for some types of |
| breakpoints, such as target remote. */ |
| bp_tgt->shadow_len = bplen; |
| memcpy (bp_tgt->shadow_contents, readbuf, bplen); |
| |
| val = target_write_raw_memory (addr, bp, bplen); |
| } |
| |
| return val; |
| } |
| |
| |
| int |
| default_memory_remove_breakpoint (struct gdbarch *gdbarch, |
| struct bp_target_info *bp_tgt) |
| { |
| int bplen; |
| |
| gdbarch_sw_breakpoint_from_kind (gdbarch, bp_tgt->kind, &bplen); |
| |
| return target_write_raw_memory (bp_tgt->placed_address, bp_tgt->shadow_contents, |
| bplen); |
| } |
| |
| |
| int |
| memory_insert_breakpoint (struct target_ops *ops, struct gdbarch *gdbarch, |
| struct bp_target_info *bp_tgt) |
| { |
| return gdbarch_memory_insert_breakpoint (gdbarch, bp_tgt); |
| } |
| |
| int |
| memory_remove_breakpoint (struct target_ops *ops, struct gdbarch *gdbarch, |
| struct bp_target_info *bp_tgt, |
| enum remove_bp_reason reason) |
| { |
| return gdbarch_memory_remove_breakpoint (gdbarch, bp_tgt); |
| } |
| |
| int |
| memory_validate_breakpoint (struct gdbarch *gdbarch, |
| struct bp_target_info *bp_tgt) |
| { |
| CORE_ADDR addr = bp_tgt->placed_address; |
| const gdb_byte *bp; |
| int val; |
| int bplen; |
| gdb_byte cur_contents[BREAKPOINT_MAX]; |
| |
| /* Determine appropriate breakpoint contents and size for this |
| address. */ |
| bp = gdbarch_breakpoint_from_pc (gdbarch, &addr, &bplen); |
| |
| if (bp == NULL) |
| return 0; |
| |
| /* Make sure we see the memory breakpoints. */ |
| scoped_restore restore_memory |
| = make_scoped_restore_show_memory_breakpoints (1); |
| val = target_read_memory (addr, cur_contents, bplen); |
| |
| /* If our breakpoint is no longer at the address, this means that |
| the program modified the code on us, so it is wrong to put back |
| the old value. */ |
| return (val == 0 && memcmp (bp, cur_contents, bplen) == 0); |
| } |