Initial revision

gdb/mem-break.c

@@ -0,0 +1,178 @@
+/* Simulate breakpoints by patching locations in the target system.
+   Copyright (C) 1990 Free Software Foundation, Inc.
+
+This file is part of GDB.
+
+GDB 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 1, or (at your option)
+any later version.
+
+GDB 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 GDB; see the file COPYING.  If not, write to
+the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.  */
+
+#include "defs.h"
+#include "param.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);
+}
+
+
+#if 0
+/* This should move back into breakpoint.c, sad to say.   Encapsulate
+    sizeof (BREAKPOINT) by export it as an int from mem-break.c.  */
+
+/* Like target_read_memory() but if breakpoints are inserted, return
+   the shadow contents instead of the breakpoints themselves.  */
+int
+read_memory_nobpt (memaddr, myaddr, len)
+     CORE_ADDR memaddr;
+     char *myaddr;
+     unsigned len;
+{
+  int status;
+  struct breakpoint *b;
+  ALL_BREAKPOINTS (b)
+    {
+      if (b->address == NULL || !b->inserted)
+	continue;
+      else if (b->address + sizeof (break_insn) <= memaddr)
+	/* The breakpoint is entirely before the chunk of memory
+	   we are reading.  */
+	continue;
+      else if (b->address >= memaddr + len)
+	/* The breakpoint is entirely after the chunk of memory we
+	   are reading.  */
+	continue;
+      else
+	{
+	  /* Copy the breakpoint from the shadow contents, and recurse
+	     for the things before and after.  */
+	  
+	  /* Addresses and length of the part of the breakpoint that
+	     we need to copy.  */
+	  CORE_ADDR membpt = b->address;
+	  unsigned int bptlen = sizeof (break_insn);
+	  /* Offset within shadow_contents.  */
+	  int bptoffset = 0;
+	  
+	  if (membpt < memaddr)
+	    {
+	      /* Only copy the second part of the breakpoint.  */
+	      bptlen -= memaddr - membpt;
+	      bptoffset = memaddr - membpt;
+	      membpt = memaddr;
+	    }
+
+	  if (membpt + bptlen > memaddr + len)
+	    {
+	      /* Only copy the first part of the breakpoint.  */
+	      bptlen -= (membpt + bptlen) - (memaddr + len);
+	    }
+
+	  bcopy (b->shadow_contents + bptoffset,
+		 myaddr + membpt - memaddr, bptlen);
+
+	  if (membpt > memaddr)
+	    {
+	      /* Copy the section of memory before the breakpoint.  */
+	      status = read_memory_nobpt (memaddr, myaddr, membpt - memaddr);
+	      if (status != 0)
+		return status;
+	    }
+
+	  if (membpt + bptlen < memaddr + len)
+	    {
+	      /* Copy the section of memory after the breakpoint.  */
+	      status = read_memory_nobpt
+		(membpt + bptlen,
+		 myaddr + membpt + bptlen - memaddr,
+		 memaddr + len - (membpt + bptlen));
+	      if (status != 0)
+		return status;
+	    }
+	  return 0;
+	}
+    }
+  /* Nothing overlaps.  Just call read_memory_noerr.  */
+  return target_read_memory (memaddr, myaddr, len);
+}
+#endif /* 0 */
+
+#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 */
+}
+
+#endif /* BREAKPOINT */