/* Simulate breakpoints by patching locations in the target system, for GDB. Copyright (C) 1990-2022 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 "defs.h" #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); }