35c63cd8ce
When debugging on Windows with GDBserver, the debugger starts
failing after hitting a breakpoint. For instance:
(gdb) b foo
Breakpoint 1 at 0x40177e: file foo.adb, line 5.
(gdb) cont
Continuing.
Breakpoint 1, foo () at foo.adb:5
5 Put_Line ("Hello World."); -- STOP
(gdb) n
Program received signal SIGSEGV, Segmentation fault.
0x00401782 in foo () at foo.adb:5
5 Put_Line ("Hello World."); -- STOP
There are two issues:
1. While trying to re-insert a breakpoint that is still inserted
in memory, insert_bp_location wipes out the breakpoint location's
shadow_contents. As a consequence, we cannot restore the proper
instruction when removing the breakpoint anymore. That's why
the inferior's behavior changes when trying to resume after
the breakpoint was hit.
2. mem-break.c:default_memory_insert_breakpoint passes a breakpoint
location's shadow_contents as the buffer for a memory read.
This reveals a limitation of the various memory-read target
functions. This patch documents this limitation and adjust
the two calls that seem to hit that limitation.
gdb/ChangeLog:
* breakpoint.c (breakpoint_xfer_memory): Add assertion.
Update function description.
(insert_bp_location): Do not wipe bl->target_info out.
* mem-break.c: #include "gdb_string.h".
(default_memory_insert_breakpoint): Do not call target_read_memory
with a pointer to the breakpoint's shadow_contents buffer. Use
a local buffer instead.
* m32r-tdep.c (m32r_memory_insert_breakpoint): Ditto.
96 lines
3 KiB
C
96 lines
3 KiB
C
/* Simulate breakpoints by patching locations in the target system, for GDB.
|
|
|
|
Copyright (C) 1990-1993, 1995, 1997-2000, 2002, 2007-2012 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"
|
|
#include "gdb_string.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;
|
|
gdb_byte *readbuf;
|
|
|
|
/* 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 in the shadow_contents buffer and then
|
|
write the breakpoint instruction. */
|
|
bp_tgt->shadow_len = bp_tgt->placed_size;
|
|
readbuf = alloca (bp_tgt->placed_size);
|
|
val = target_read_memory (bp_tgt->placed_address, readbuf,
|
|
bp_tgt->placed_size);
|
|
if (val == 0)
|
|
{
|
|
memcpy (bp_tgt->shadow_contents, readbuf, bp_tgt->placed_size);
|
|
val = target_write_raw_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_raw_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);
|
|
}
|