binutils-gdb/gdb/mem-break.c

/* Simulate breakpoints by patching locations in the target system, for GDB.

   Copyright (C) 1990, 1991, 1992, 1993, 1995, 1997, 1998, 1999, 2000, 2002,
   2007, 2008, 2009, 2010 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"

/* This file is only useful if BREAKPOINT_FROM_PC is set.  If not, we
   punt.  */

#include "symtab.h"
#include "breakpoint.h"
#include "inferior.h"
#include "target.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)
{
  int val;
  const unsigned char *bp;

  /* Determine appropriate breakpoint contents and size for this address.  */
  bp = gdbarch_breakpoint_from_pc
       (gdbarch, &bp_tgt->placed_address, &bp_tgt->placed_size);
  if (bp == NULL)
    error (_("Software breakpoints not implemented for this target."));

  /* Save the memory contents.  */
  bp_tgt->shadow_len = bp_tgt->placed_size;
  val = target_read_memory (bp_tgt->placed_address, bp_tgt->shadow_contents,
			    bp_tgt->placed_size);

  /* Write the breakpoint.  */
  if (val == 0)
    val = target_write_memory (bp_tgt->placed_address, bp,
			       bp_tgt->placed_size);

  return val;
}


int
default_memory_remove_breakpoint (struct gdbarch *gdbarch,
				  struct bp_target_info *bp_tgt)
{
  return target_write_memory (bp_tgt->placed_address, bp_tgt->shadow_contents,
			      bp_tgt->placed_size);
}


int
memory_insert_breakpoint (struct gdbarch *gdbarch,
			  struct bp_target_info *bp_tgt)
{
  return gdbarch_memory_insert_breakpoint (gdbarch, bp_tgt);
}

int
memory_remove_breakpoint (struct gdbarch *gdbarch,
			  struct bp_target_info *bp_tgt)
{
  return gdbarch_memory_remove_breakpoint (gdbarch, bp_tgt);
}