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130 lines
4.1 KiB
C
130 lines
4.1 KiB
C
/* Simulate breakpoints by patching locations in the target system, for GDB.
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Copyright (C) 1990-2020 Free Software Foundation, Inc.
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Contributed by Cygnus Support. Written by John Gilmore.
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This file is part of GDB.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>. */
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#include "defs.h"
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#include "symtab.h"
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#include "breakpoint.h"
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#include "inferior.h"
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#include "target.h"
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#include "gdbarch.h"
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/* Insert a breakpoint on targets that don't have any better
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breakpoint support. We read the contents of the target location
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and stash it, then overwrite it with a breakpoint instruction.
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BP_TGT->placed_address is the target location in the target
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machine. BP_TGT->shadow_contents is some memory allocated for
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saving the target contents. It is guaranteed by the caller to be
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long enough to save BREAKPOINT_LEN bytes (this is accomplished via
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BREAKPOINT_MAX). */
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int
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default_memory_insert_breakpoint (struct gdbarch *gdbarch,
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struct bp_target_info *bp_tgt)
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{
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CORE_ADDR addr = bp_tgt->placed_address;
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const unsigned char *bp;
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gdb_byte *readbuf;
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int bplen;
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int val;
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/* Determine appropriate breakpoint contents and size for this address. */
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bp = gdbarch_sw_breakpoint_from_kind (gdbarch, bp_tgt->kind, &bplen);
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/* Save the memory contents in the shadow_contents buffer and then
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write the breakpoint instruction. */
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readbuf = (gdb_byte *) alloca (bplen);
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val = target_read_memory (addr, readbuf, bplen);
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if (val == 0)
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{
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/* These must be set together, either before or after the shadow
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read, so that if we're "reinserting" a breakpoint that
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doesn't have a shadow yet, the breakpoint masking code inside
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target_read_memory doesn't mask out this breakpoint using an
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unfilled shadow buffer. The core may be trying to reinsert a
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permanent breakpoint, for targets that support breakpoint
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conditions/commands on the target side for some types of
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breakpoints, such as target remote. */
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bp_tgt->shadow_len = bplen;
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memcpy (bp_tgt->shadow_contents, readbuf, bplen);
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val = target_write_raw_memory (addr, bp, bplen);
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}
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return val;
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}
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int
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default_memory_remove_breakpoint (struct gdbarch *gdbarch,
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struct bp_target_info *bp_tgt)
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{
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int bplen;
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gdbarch_sw_breakpoint_from_kind (gdbarch, bp_tgt->kind, &bplen);
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return target_write_raw_memory (bp_tgt->placed_address, bp_tgt->shadow_contents,
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bplen);
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}
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int
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memory_insert_breakpoint (struct target_ops *ops, struct gdbarch *gdbarch,
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struct bp_target_info *bp_tgt)
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{
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return gdbarch_memory_insert_breakpoint (gdbarch, bp_tgt);
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}
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int
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memory_remove_breakpoint (struct target_ops *ops, struct gdbarch *gdbarch,
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struct bp_target_info *bp_tgt,
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enum remove_bp_reason reason)
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{
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return gdbarch_memory_remove_breakpoint (gdbarch, bp_tgt);
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}
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int
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memory_validate_breakpoint (struct gdbarch *gdbarch,
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struct bp_target_info *bp_tgt)
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{
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CORE_ADDR addr = bp_tgt->placed_address;
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const gdb_byte *bp;
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int val;
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int bplen;
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gdb_byte cur_contents[BREAKPOINT_MAX];
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/* Determine appropriate breakpoint contents and size for this
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address. */
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bp = gdbarch_breakpoint_from_pc (gdbarch, &addr, &bplen);
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if (bp == NULL)
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return 0;
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/* Make sure we see the memory breakpoints. */
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scoped_restore restore_memory
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= make_scoped_restore_show_memory_breakpoints (1);
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val = target_read_memory (addr, cur_contents, bplen);
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/* If our breakpoint is no longer at the address, this means that
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the program modified the code on us, so it is wrong to put back
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the old value. */
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return (val == 0 && memcmp (bp, cur_contents, bplen) == 0);
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}
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