163 lines
4.8 KiB
C
163 lines
4.8 KiB
C
/* Simulate breakpoints by patching locations in the target system, for GDB.
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Copyright 1990, 1991, 1995 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 2 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, write to the Free Software
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Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
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#include "defs.h"
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/* Either BREAKPOINT should be defined, or both of LITTLE_BREAKPOINT,
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BIG_BREAKPOINT should be defined. */
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#if defined (BREAKPOINT) || (defined (LITTLE_BREAKPOINT) && defined (BIG_BREAKPOINT))
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/* This file is only useful if BREAKPOINT is set. If not, we punt. */
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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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/* If the target isn't bi-endian, just pretend it is. */
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#if defined(BREAKPOINT) && !defined (LITTLE_BREAKPOINT) && !defined (BIG_BREAKPOINT)
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#define LITTLE_BREAKPOINT BREAKPOINT
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#define BIG_BREAKPOINT BREAKPOINT
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#endif
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/* This is the sequence of bytes we insert for a breakpoint. On some
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machines, breakpoints are handled by the target environment and we
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don't have to worry about them here. */
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static unsigned char big_break_insn[] = BIG_BREAKPOINT;
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static unsigned char little_break_insn[] = LITTLE_BREAKPOINT;
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/* FIXME: We assume big and little breakpoints are the same size. */
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#define BREAKPOINT_LEN (sizeof (big_break_insn))
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/* Use the program counter to determine the contents and size
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of a breakpoint instruction. If no target-dependent macro
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BREAKPOINT_FROM_PC has been defined to implement this function,
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assume that the breakpoint doesn't depend on the PC, and
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use the values of the BIG_BREAKPOINT and LITTLE_BREAKPOINT macros.
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Return a pointer to a string of bytes that encode a breakpoint
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instruction, stores the length of the string to *lenptr,
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and optionally adjust the pc to point to the correct memory location
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for inserting the breakpoint. */
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unsigned char *memory_breakpoint_from_pc (pcptr, lenptr)
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CORE_ADDR *pcptr;
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int *lenptr;
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{
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#ifdef BREAKPOINT_FROM_PC
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return BREAKPOINT_FROM_PC(pcptr, lenptr);
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#else
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if (TARGET_BYTE_ORDER == BIG_ENDIAN)
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{
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*lenptr = sizeof (big_break_insn);
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return big_break_insn;
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}
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else
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{
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*lenptr = sizeof (little_break_insn);
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return little_break_insn;
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}
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#endif
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}
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/* Insert a breakpoint on targets that don't have any better breakpoint
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support. We read the contents of the target location and stash it,
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then overwrite it with a breakpoint instruction. ADDR is the target
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location in the target machine. CONTENTS_CACHE is a pointer to
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memory allocated for saving the target contents. It is guaranteed
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by the caller to be long enough to save BREAKPOINT_LEN bytes (this
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is accomplished via BREAKPOINT_MAX). */
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int
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memory_insert_breakpoint (addr, contents_cache)
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CORE_ADDR addr;
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char *contents_cache;
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{
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int val;
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unsigned char *bp;
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int bplen;
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/* Determine appropriate breakpoint contents and size for this address. */
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bp = memory_breakpoint_from_pc (&addr, &bplen);
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/* Save the memory contents. */
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val = target_read_memory (addr, contents_cache, bplen);
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/* Write the breakpoint. */
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if (val == 0)
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val = target_write_memory (addr, (char *)bp, bplen);
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return val;
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}
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int
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memory_remove_breakpoint (addr, contents_cache)
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CORE_ADDR addr;
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char *contents_cache;
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{
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unsigned char *bp;
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int bplen;
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/* Determine appropriate breakpoint size for this address. */
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bp = memory_breakpoint_from_pc (&addr, &bplen);
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return target_write_memory (addr, contents_cache, bplen);
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}
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/* FIXME: This is a hack and should depend on the debugging target.
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See comment in breakpoint.c where this is used.
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NOTE: this has now been superseded by the memory_breakpoint_from_pc
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function above, but has been left in for older code that depends on it. */
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int memory_breakpoint_size = BREAKPOINT_LEN;
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#else /* BREAKPOINT */
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char nogo[] = "Breakpoints not implemented for this target.";
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int
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memory_insert_breakpoint (addr, contents_cache)
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CORE_ADDR addr;
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char *contents_cache;
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{
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error (nogo);
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return 0; /* lint */
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}
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int
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memory_remove_breakpoint (addr, contents_cache)
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CORE_ADDR addr;
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char *contents_cache;
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{
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error (nogo);
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return 0; /* lint */
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}
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int memory_breakpoint_size = -1;
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#endif /* BREAKPOINT */
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