binutils-gdb/gdb/mem-break.c

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/* Simulate breakpoints by patching locations in the target system, for GDB.
Copyright 1990, 1991, 1995 Free Software Foundation, Inc.
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
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.
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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.
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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., 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA. */
#include "defs.h"
/* This file is only useful if BREAKPOINT is set. If not, we punt. */
#include "symtab.h"
#include "breakpoint.h"
#include "inferior.h"
#include "target.h"
/* Use the program counter to determine the contents and size
of a breakpoint instruction. If no target-dependent macro
BREAKPOINT_FROM_PC has been defined to implement this function,
assume that the breakpoint doesn't depend on the PC, and
use the values of the BIG_BREAKPOINT and LITTLE_BREAKPOINT macros.
Return a pointer to a string of bytes that encode a breakpoint
instruction, stores the length of the string to *lenptr,
and optionally adjust the pc to point to the correct memory location
for inserting the breakpoint. */
unsigned char *
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memory_breakpoint_from_pc (CORE_ADDR *pcptr, int *lenptr)
{
/* {BIG_,LITTLE_}BREAKPOINT 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. */
#ifdef BIG_BREAKPOINT
if (TARGET_BYTE_ORDER == BIG_ENDIAN)
{
static unsigned char big_break_insn[] = BIG_BREAKPOINT;
*lenptr = sizeof (big_break_insn);
return big_break_insn;
}
#endif
#ifdef LITTLE_BREAKPOINT
if (TARGET_BYTE_ORDER != BIG_ENDIAN)
{
static unsigned char little_break_insn[] = LITTLE_BREAKPOINT;
*lenptr = sizeof (little_break_insn);
return little_break_insn;
}
#endif
#ifdef BREAKPOINT
{
static unsigned char break_insn[] = BREAKPOINT;
*lenptr = sizeof (break_insn);
return break_insn;
}
#endif
*lenptr = 0;
return NULL;
}
/* 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. 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 BREAKPOINT_LEN bytes (this
is accomplished via BREAKPOINT_MAX). */
int
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default_memory_insert_breakpoint (CORE_ADDR addr, char *contents_cache)
{
int val;
unsigned char *bp;
int bplen;
/* Determine appropriate breakpoint contents and size for this address. */
bp = BREAKPOINT_FROM_PC (&addr, &bplen);
if (bp == NULL)
error ("Software breakpoints not implemented for this target.");
/* Save the memory contents. */
val = target_read_memory (addr, contents_cache, bplen);
/* Write the breakpoint. */
if (val == 0)
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val = target_write_memory (addr, (char *) bp, bplen);
return val;
}
int
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default_memory_remove_breakpoint (CORE_ADDR addr, char *contents_cache)
{
unsigned char *bp;
int bplen;
/* Determine appropriate breakpoint contents and size for this address. */
bp = BREAKPOINT_FROM_PC (&addr, &bplen);
if (bp == NULL)
error ("Software breakpoints not implemented for this target.");
return target_write_memory (addr, contents_cache, bplen);
}
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int
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memory_insert_breakpoint (CORE_ADDR addr, char *contents_cache)
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{
return MEMORY_INSERT_BREAKPOINT(addr, contents_cache);
}
int
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memory_remove_breakpoint (CORE_ADDR addr, char *contents_cache)
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{
return MEMORY_REMOVE_BREAKPOINT(addr, contents_cache);
}