Implement breakpoint_kind_from_pc and sw_breakpoint_from_kind for ARM in GDBServer.

ARM can have multiple breakpoint types based on the instruction set
it's currently in: arm, thumb or thumb2.

GDBServer needs to know what breakpoint is to be inserted at location
when inserting a breakpoint.

This is handled by the breakpoint_kind_from_pc and sw_breakpoint_from_kind
target ops introduced in a previous patch, this patch adds the
arm_breakpoint_kind_from_pc and arm_sw_breakpoint_from_kind implementation so
that the proper breakpoint type is returned based on the pc.

Also in order to share some code with GDB a new file called arm.c have been
introduced in arch/.

While this file does not contain much yet future patches will add more
to it thus the inclusion at this stage.

No regressions on Ubuntu 14.04 on ARMv7 and x86.
With gdbserver-{native,extended} / { -marm -mthumb }

gdb/ChangeLog:

	* Makefile.in: Add arm.c/o.
	* arch/arm.c: New file.
	* arch/arm.h: (IS_THUMB_ADDR): Move macro from arm-tdep.c.
	(MAKE_THUMB_ADDR): Likewise.
	(UNMAKE_THUMB_ADDR): Likewise.
	* arm-tdep.c (int thumb_insn_size): Move to arm.c.
	(IS_THUMB_ADDR): Move to arm.h.
	(MAKE_THUMB_ADDR): Likewise.
	(UNMAKE_THUMB_ADDR): Likewise.
	* configure.tgt: Add arm.o to all ARM configs.

gdb/gdbserver/ChangeLog:

	* Makefile.in: Add arm.c/o.
	* configure.srv: Likewise.
	* linux-arm-low.c (arm_breakpoint_kinds): New enum.
	(arm_breakpoint_kind_from_pc): New function.
	(arm_sw_breakpoint_from_kind): Return proper kind.
	(struct linux_target_ops) <breakpoint_kind_from_pc>: Initialize.

2 files changed, 44 insertions, 1 deletions

diff --git a/gdb/arch/arm.c b/gdb/arch/arm.c
new file mode 100644
index 0000000..b11c684
--- /dev/null
+++ b/gdb/arch/arm.c
@@ -0,0 +1,33 @@
+/* Common target dependent code for GDB on ARM systems.
+
+   Copyright (C) 1988-2015 Free Software Foundation, Inc.
+
+   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 "common-defs.h"
+#include "arm.h"
+
+/* Return the size in bytes of the complete Thumb instruction whose
+   first halfword is INST1.  */
+
+int
+thumb_insn_size (unsigned short inst1)
+{
+  if ((inst1 & 0xe000) == 0xe000 && (inst1 & 0x1800) != 0)
+    return 4;
+  else
+    return 2;
+}
diff --git a/gdb/arch/arm.h b/gdb/arch/arm.h
index e0eed60..a054776 100644
--- a/gdb/arch/arm.h
+++ b/gdb/arch/arm.h
@@ -1,5 +1,5 @@
 /* Common target dependent code for GDB on ARM systems.
-   Copyright (C) 2002-2015 Free Software Foundation, Inc.
+   Copyright (C) 1988-2015 Free Software Foundation, Inc.
 
    This file is part of GDB.
 
@@ -58,4 +58,14 @@ enum gdb_regnum {
   ARM_LAST_FP_ARG_REGNUM = ARM_F3_REGNUM
 };
 
+/* Addresses for calling Thumb functions have the bit 0 set.
+   Here are some macros to test, set, or clear bit 0 of addresses.  */
+#define IS_THUMB_ADDR(addr)    ((addr) & 1)
+#define MAKE_THUMB_ADDR(addr)  ((addr) | 1)
+#define UNMAKE_THUMB_ADDR(addr) ((addr) & ~1)
+
+/* Return the size in bytes of the complete Thumb instruction whose
+   first halfword is INST1.  */
+int thumb_insn_size (unsigned short inst1);
+
 #endif