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- /* 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);
- }
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