[PATCH v2] Fix PR gdb/12953: No hardware watchpoints on FreeBSD amd64

Valery Khromov
2011-12-20T20:11:10Z

This patch provides hardware breakpoint/watchpoint support for
FreeBSD/AMD64. Most of the code is borrowed from the i386 implementation.

Also removed not necessary DBREG_DRX macro definition.

gdb/ChangeLog:
2011-12-20 Valery Khromov <valery.khromov@gmail.com>

PR gdb/12953
* Makefile.in (HFILES_NO_SRCDIR): Add amd64bsd-nat.h.
* amd64bsd-nat.c: Add support for debug registers (adapted from
i386bsd-nat.c).
[HAVE_PT_GETDBREGS] (amd64bsd_dr_get, amd64bsd_dr_set,
amd64bsd_dr_set_control, amd64bsd_dr_set_addr, amd64bsd_dr_get_addr,
amd64bsd_dr_get_status, amd64bsd_dr_get_control): New functions.
* amd64bsd-nat.h: New file (adapted from i386bsd-nat.h).
* amd64fbsd-nat.c: Include "amd64bsd-nat.h", "i386-nat.h".
[HAVE_PT_GETDBREGS] (_initialize_amd64fbsd_nat): Add hardware
watchpoints initialization.
* config/i386/fbsd64.mh (NATDEPFILES): Add i386-nat.o.
* i386bsd-nat.c: [HAVE_PT_GETDBREGS] (DBREG_DRX): Delete.
---
gdb/Makefile.in | 2 +-
gdb/amd64bsd-nat.c | 72 +++++++++++++++++++++++++++++++++++++++++++++
gdb/amd64bsd-nat.h | 37 +++++++++++++++++++++++
gdb/amd64fbsd-nat.c | 16 ++++++++++
gdb/config/i386/fbsd64.mh | 2 +-
gdb/i386bsd-nat.c | 6 ----
6 files changed, 127 insertions(+), 8 deletions(-)
create mode 100644 gdb/amd64bsd-nat.h

diff --git a/gdb/Makefile.in b/gdb/Makefile.in
index b71db33..ada8585 100644
--- a/gdb/Makefile.in
+++ b/gdb/Makefile.in
@@ -772,7 +772,7 @@ common/gdb_signals.h common/gdb_thread_db.h common/i386-xstate.h \
common/linux-ptrace.h \
proc-utils.h arm-tdep.h ax-gdb.h ppcnbsd-tdep.h \
cli-out.h gdb_expat.h breakpoint.h infcall.h obsd-tdep.h \
-exec.h m32r-tdep.h osabi.h gdbcore.h solib-som.h \
+exec.h m32r-tdep.h osabi.h gdbcore.h solib-som.h amd64bsd-nat.h \
i386bsd-nat.h xml-support.h xml-tdesc.h alphabsd-tdep.h gdb_obstack.h \
ia64-tdep.h ada-lang.h varobj.h frv-tdep.h nto-tdep.h serial.h \
c-lang.h d-lang.h frame.h event-loop.h block.h cli/cli-setshow.h \
diff --git a/gdb/amd64bsd-nat.c b/gdb/amd64bsd-nat.c
index 7821f2b..21ab3ea 100644
--- a/gdb/amd64bsd-nat.c
+++ b/gdb/amd64bsd-nat.c
@@ -126,3 +126,75 @@ amd64bsd_target (void)
t->to_store_registers = amd64bsd_store_inferior_registers;
return t;
}
+\f
+
+/* Support for debug registers. */
+
+#ifdef HAVE_PT_GETDBREGS
+
+static unsigned long
+amd64bsd_dr_get (ptid_t ptid, int regnum)
+{
+ struct dbreg dbregs;
+
+ if (ptrace (PT_GETDBREGS, PIDGET (inferior_ptid),
+ (PTRACE_TYPE_ARG3) &dbregs, 0) == -1)
+ perror_with_name (_("Couldn't read debug registers"));
+
+ return DBREG_DRX ((&dbregs), regnum);
+}
+
+static void
+amd64bsd_dr_set (int regnum, unsigned long value)
+{
+ struct dbreg dbregs;
+
+ if (ptrace (PT_GETDBREGS, PIDGET (inferior_ptid),
+ (PTRACE_TYPE_ARG3) &dbregs, 0) == -1)
+ perror_with_name (_("Couldn't get debug registers"));
+
+ /* For some mysterious reason, some of the reserved bits in the
+ debug control register get set. Mask these off, otherwise the
+ ptrace call below will fail. */
+ DBREG_DRX ((&dbregs), 7) &= ~(0xffffffff0000fc00);
+
+ DBREG_DRX ((&dbregs), regnum) = value;
+
+ if (ptrace (PT_SETDBREGS, PIDGET (inferior_ptid),
+ (PTRACE_TYPE_ARG3) &dbregs, 0) == -1)
+ perror_with_name (_("Couldn't write debug registers"));
+}
+
+void
+amd64bsd_dr_set_control (unsigned long control)
+{
+ amd64bsd_dr_set (7, control);
+}
+
+void
+amd64bsd_dr_set_addr (int regnum, CORE_ADDR addr)
+{
+ gdb_assert (regnum >= 0 && regnum <= 4);
+
+ amd64bsd_dr_set (regnum, addr);
+}
+
+CORE_ADDR
+amd64bsd_dr_get_addr (int regnum)
+{
+ return amd64bsd_dr_get (inferior_ptid, regnum);
+}
+
+unsigned long
+amd64bsd_dr_get_status (void)
+{
+ return amd64bsd_dr_get (inferior_ptid, 6);
+}
+
+unsigned long
+amd64bsd_dr_get_control (void)
+{
+ return amd64bsd_dr_get (inferior_ptid, 7);
+}
+
+#endif /* PT_GETDBREGS */
diff --git a/gdb/amd64bsd-nat.h b/gdb/amd64bsd-nat.h
new file mode 100644
index 0000000..25eb8d4
--- /dev/null
+++ b/gdb/amd64bsd-nat.h
@@ -0,0 +1,37 @@
+/* Native-dependent code for modern AMD64 BSD's.
+
+ Copyright (C) 2011
+ Free Software Foundation, Inc.
+ Contributed by Valery Khromov, Yandex.
+
+ 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/>. */
+
+#ifndef AMD64BSD_NAT_H
+#define AMD64BSD_NAT_H
+
+/* low level amd64 debug register functions used in amd64fbsd-nat.c. */
+
+extern void amd64bsd_dr_set_control (unsigned long control);
+
+extern void amd64bsd_dr_set_addr (int regnum, CORE_ADDR addr);
+
+extern CORE_ADDR amd64bsd_dr_get_addr (int regnum);
+
+extern unsigned long amd64bsd_dr_get_status (void);
+
+extern unsigned long amd64bsd_dr_get_control (void);
+
+#endif /* amd64bsd-nat.h */
diff --git a/gdb/amd64fbsd-nat.c b/gdb/amd64fbsd-nat.c
index 359138d..ec6d4a4 100644
--- a/gdb/amd64fbsd-nat.c
+++ b/gdb/amd64fbsd-nat.c
@@ -34,6 +34,8 @@
#include "fbsd-nat.h"
#include "amd64-tdep.h"
#include "amd64-nat.h"
+#include "amd64bsd-nat.h"
+#include "i386-nat.h"
\f

/* Offset in `struct reg' where MEMBER is stored. */
@@ -155,6 +157,20 @@ _initialize_amd64fbsd_nat (void)

/* Add some extra features to the common *BSD/i386 target. */
t = amd64bsd_target ();
+
+#ifdef HAVE_PT_GETDBREGS
+
+ i386_use_watchpoints (t);
+
+ i386_dr_low.set_control = amd64bsd_dr_set_control;
+ i386_dr_low.set_addr = amd64bsd_dr_set_addr;
+ i386_dr_low.get_addr = amd64bsd_dr_get_addr;
+ i386_dr_low.get_status = amd64bsd_dr_get_status;
+ i386_dr_low.get_control = amd64bsd_dr_get_control;
+ i386_set_debug_register_length (8);
+
+#endif /* HAVE_PT_GETDBREGS */
+
t->to_pid_to_exec_file = fbsd_pid_to_exec_file;
t->to_find_memory_regions = fbsd_find_memory_regions;
t->to_make_corefile_notes = fbsd_make_corefile_notes;
diff --git a/gdb/config/i386/fbsd64.mh b/gdb/config/i386/fbsd64.mh
index 2266def..24a87bf 100644
--- a/gdb/config/i386/fbsd64.mh
+++ b/gdb/config/i386/fbsd64.mh
@@ -1,6 +1,6 @@
# Host: FreeBSD/amd64
NATDEPFILES= fork-child.o inf-ptrace.o \
- fbsd-nat.o amd64-nat.o amd64bsd-nat.o amd64fbsd-nat.o \
+ fbsd-nat.o i386-nat.o amd64-nat.o amd64bsd-nat.o amd64fbsd-nat.o \
bsd-kvm.o

LOADLIBES= -lkvm
diff --git a/gdb/i386bsd-nat.c b/gdb/i386bsd-nat.c
index 22c79e2..661a07f 100644
--- a/gdb/i386bsd-nat.c
+++ b/gdb/i386bsd-nat.c
@@ -258,12 +258,6 @@ i386bsd_target (void)

#ifdef HAVE_PT_GETDBREGS

-/* Not all versions of FreeBSD/i386 that support the debug registers
- have this macro. */
-#ifndef DBREG_DRX
-#define DBREG_DRX(d, x) ((&d->dr0)[x])
-#endif
-
static unsigned long
i386bsd_dr_get (ptid_t ptid, int regnum)
{