binutils-gdb/gdb/mem-break.c

/* Simulate breakpoints by patching locations in the target system, for GDB.
   Copyright 1990, 1991 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 2 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, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.  */

#include "defs.h"

#ifdef BREAKPOINT
/* This file is only useful if BREAKPOINT is set.  If not, we punt.  */

#include <stdio.h>
#include "breakpoint.h"
#include "inferior.h"
#include "target.h"

/* This is the sequence of bytes we insert for a breakpoint.  On some
   machines, breakpoints are handled by the target environment and we
   don't have to worry about them here.  */

static char break_insn[] = BREAKPOINT;

/* This is only to check that BREAKPOINT fits in BREAKPOINT_MAX bytes.  */

static char check_break_insn_size[BREAKPOINT_MAX] = BREAKPOINT;

/* Insert a breakpoint on machines 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.  ADDR is the target
   location in the target machine.  CONTENTS_CACHE is a pointer to 
   memory allocated for saving the target contents.  It is guaranteed
   by the caller to be long enough to save sizeof BREAKPOINT bytes.
   FIXME: This size is target_arch dependent and should be available in
   the target_arch transfer vector, if we ever have one...  */

int
memory_insert_breakpoint (addr, contents_cache)
     CORE_ADDR addr;
     char *contents_cache;
{
  int val;

  val = target_read_memory (addr, contents_cache, sizeof break_insn);

  if (val == 0)
    val = target_write_memory (addr, break_insn, sizeof break_insn);

  return val;
}


int
memory_remove_breakpoint (addr, contents_cache)
     CORE_ADDR addr;
     char *contents_cache;
{
  return target_write_memory (addr, contents_cache, sizeof break_insn);
}


int memory_breakpoint_size = sizeof (break_insn);


#else  /* BREAKPOINT */

char nogo[] = "Breakpoints not implemented for this target.";

int
memory_insert_breakpoint (addr, contents_cache)
     CORE_ADDR addr;
     char *contents_cache;
{
  error (nogo);
  return 0;	/* lint */
}

int
memory_remove_breakpoint (addr, contents_cache)
     CORE_ADDR addr;
     char *contents_cache;
{
  error (nogo);
  return 0;	/* lint */
}

int memory_breakpoint_size = -1;

#endif /* BREAKPOINT */